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Yu J, Cheng W, Ni J, Li C, Su X, Yan H, Bao F, Hou L. High-Speed Generation of Microbubbles with Constant Cumulative Production in a Glass Capillary Microfluidic Bubble Generator. MICROMACHINES 2024; 15:752. [PMID: 38930722 PMCID: PMC11205313 DOI: 10.3390/mi15060752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/29/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024]
Abstract
This work reports a simple bubble generator for the high-speed generation of microbubbles with constant cumulative production. To achieve this, a gas-liquid co-flowing microfluidic device with a tiny capillary orifice as small as 5 μm is fabricated to produce monodisperse microbubbles. The diameter of the microbubbles can be adjusted precisely by tuning the input gas pressure and flow rate of the continuous liquid phase. The co-flowing structure ensures the uniformity of the generated microbubbles, and the surfactant in the liquid phase prevents coalescence of the collected microbubbles. The diameter coefficient of variation (CV) of the generated microbubbles can reach a minimum of 1.3%. Additionally, the relationship between microbubble diameter and the gas channel orifice is studied using the low Capillary number (Ca) and Weber number (We) of the liquid phase. Moreover, by maintaining a consistent gas input pressure, the CV of the cumulative microbubble volume can reach 3.6% regardless of the flow rate of the liquid phase. This method not only facilitates the generation of microbubbles with morphologic stability under variable flow conditions, but also ensures that the cumulative microbubble production over a certain period of time remains constant, which is important for the volume-dominated application of chromatographic analysis and the component analysis of natural gas.
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Affiliation(s)
- Jian Yu
- Key Laboratory of Measuring & Online Assessment of Energy for Jiangsu Province Market Regulation, Suzhou Institute of Metrology, Suzhou 215128, China (C.L.)
- Zhejiang Provincial Key Laboratory of Flow Measurement Technology, China Jiliang University, Hangzhou 310018, China
| | - Wei Cheng
- Key Laboratory of Measuring & Online Assessment of Energy for Jiangsu Province Market Regulation, Suzhou Institute of Metrology, Suzhou 215128, China (C.L.)
| | - Jinchun Ni
- Key Laboratory of Measuring & Online Assessment of Energy for Jiangsu Province Market Regulation, Suzhou Institute of Metrology, Suzhou 215128, China (C.L.)
| | - Changwu Li
- Key Laboratory of Measuring & Online Assessment of Energy for Jiangsu Province Market Regulation, Suzhou Institute of Metrology, Suzhou 215128, China (C.L.)
| | - Xinggen Su
- Dalian Institute of Metrology Inspection and Testing Co., Ltd., Dalian 116000, China
| | - Hui Yan
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Fubing Bao
- Zhejiang Provincial Key Laboratory of Flow Measurement Technology, China Jiliang University, Hangzhou 310018, China
| | - Likai Hou
- Zhejiang Provincial Key Laboratory of Flow Measurement Technology, China Jiliang University, Hangzhou 310018, China
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2
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Wang P, Tan C, Ji X, Bai J, Yu ACH, Qin P. Sensitivity improvement of subharmonic-based pressure measurement using phospholipid-coated monodisperse microbubbles. ULTRASONICS SONOCHEMISTRY 2024; 104:106830. [PMID: 38432151 PMCID: PMC10920959 DOI: 10.1016/j.ultsonch.2024.106830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 02/09/2024] [Accepted: 02/22/2024] [Indexed: 03/05/2024]
Abstract
The use of the subharmonic signal from microbubbles exposed to ultrasound is a promising safe and cost-effective approach for the non-invasive measurement of blood pressure. Achieving a high sensitivity of the subharmonic amplitude to the ambient overpressure is crucial for clinical applications. However, currently used microbubbles have a wide size distribution and diverse shell properties. This causes uncertainty in the response of the subharmonic amplitude to changes in ambient pressure, which limits the sensitivity. The aim of this study was to use monodisperse microbubbles to improve the sensitivity of subharmonic-based pressure measurements. With the same shell materials and gas core, we used a flow-focusing microfluidic chip and a mechanical agitation method to fabricate monodisperse (∼2.45-µm mean radius and 4.7 % polydisperse index) and polydisperse microbubbles (∼1.51-µm mean radius and 48.4 % polydisperse index), respectively. We varied the ultrasound parameters (i.e., the frequency, peak negative pressure (PNP) and pulse length), and found that there was an optimal excitation frequency (2.8 MHz) for achieving maximal subharmonic emission for monodisperse microbubbles, but not for polydisperse microbubbles. Three distinct regimes (occurrence, growth, and saturation) were identified in the response of the subharmonic amplitude to increasing PNP for both monodisperse and polydisperse microbubbles. For the polydisperse microbubbles, the subharmonic amplitude decreased either monotonically or non-monotonically with ambient overpressure, depending on the PNP. By contrast, for the monodisperse microbubbles, there was only a monotonic decrease at all PNPs. The maximum sensitivity (1.18 dB/kPa, R2 = 0.97) of the subharmonic amplitude to ambient overpressure for the monodisperse microbubbles was ∼6.5 times higher than that for the polydisperse microbubbles (0.18 dB/kPa, R2 = 0.88). These results show that monodisperse microbubbles can achieve a more consistent response of the subharmonic signal to changes in ambient overpressure and greatly improve the measurement sensitivity.
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Affiliation(s)
- Pengcheng Wang
- School of Sensing Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chunjie Tan
- School of Sensing Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiang Ji
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Jingfeng Bai
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030, China.
| | - Alfred C H Yu
- Schlegel Research Institute for Aging, University of Waterloo, Waterloo, ON, N2L3G1, Canada
| | - Peng Qin
- School of Sensing Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
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3
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Khan AH, Ganguli A, Edirisinghe M, Dalvi SV. Experimental and Computational Investigation of Microbubble Formation in a Single Capillary Embedded T-junction Microfluidic Device. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:18971-18982. [PMID: 38087401 DOI: 10.1021/acs.langmuir.3c02982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
In recent years, there has been a notable increase in the interest toward microfluidic devices for microbubble synthesis. The upsurge can be primarily attributed to the exceptional control these devices offer in terms of both the size and the size distribution of microbubbles. Among various microfluidic devices available, capillary-embedded T-junction microfluidic (CETM) devices have been extensively used for the synthesis of microbubbles. One distinguishing feature of CETM devices from conventional T-junction devices is the existence of a wall at the right-most end, which causes a backflow of the continuous phase at the mixing zone during microbubble formation. The back flow at the mixing zone can have several implications during microbubble formation. It can possibly affect the local velocity and shearing force at the mixing zone, which in turn can affect the size and production rate of the microbubbles. Therefore, in this work, we experimentally and computationally understand the process of microbubble formation in CETM devices. The process is modeled using computational fluid dynamics (CFD) with the volume-of-fluid approach, which solves the Navier-Stokes equations for both the gas and liquid phases. Three scenarios with a constant liquid velocity of 0.053 m/s with varying gas velocity and three with a constant gas velocity of 0.049 m/s at different liquid velocities were explored. Increase in the liquid and gas velocity during microbubble formation was found to enhance production rates in both experiments and simulations. Additionally, the change in microbubble size with the change in liquid velocity was found to agree closely with the findings of the simulation with a coefficient of variation of 10%. When plotted against the time required for microbubble generation, the fluctuations in the pressure showed recurrent crests and troughs throughout the microbubble formation process. The understanding of microbubble formation in CETM devices in the presence of backflow will allow improvement in size reduction of microbubbles.
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Affiliation(s)
- Aaqib H Khan
- Chemical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar, Gujarat 382355, India
| | - Arijit Ganguli
- School of Engineering and Applied Sciences, Ahmedabad University, Ahmedabad, Gujarat 380009, India
| | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London (UCL), London WC1E 7JE, U.K
| | - Sameer V Dalvi
- Chemical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar, Gujarat 382355, India
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4
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Zalloum IO, Jafari Sojahrood A, Paknahad AA, Kolios MC, Tsai SSH, Karshafian R. Controlled Tempering of Lipid Concentration and Microbubble Shrinkage as a Possible Mechanism for Fine-Tuning Microbubble Size and Shell Properties. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:17622-17631. [PMID: 38016673 DOI: 10.1021/acs.langmuir.3c01599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
The acoustic response of microbubbles (MBs) depends on their resonance frequency, which is dependent on the MB size and shell properties. Monodisperse MBs with tunable shell properties are thus desirable for optimizing and controlling the MB behavior in acoustics applications. By utilizing a novel microfluidic method that uses lipid concentration to control MB shrinkage, we generated monodisperse MBs of four different initial diameters at three lipid concentrations (5.6, 10.0, and 16.0 mg/mL) in the aqueous phase. Following shrinkage, we measured the MB resonance frequency and determined its shell stiffness and viscosity. The study demonstrates that we can generate monodisperse MBs of specific sizes and tunable shell properties by controlling the MB initial diameter and aqueous phase lipid concentration. Our results indicate that the resonance frequency increases by 180-210% with increasing lipid concentration (from 5.6 to 16.0 mg/mL), while the bubble diameter is kept constant. Additionally, we find that the resonance frequency decreases by 260-300% with an increasing MB final diameter (from 5 to 12 μm), while the lipid concentration is held constant. For example, our results depict that the resonance frequency increases by ∼195% with increasing lipid concentration from 5.6 to 16.0 mg/mL, for ∼11 μm final diameter MBs. Additionally, we find that the resonance frequency decreases by ∼275% with increasing MB final diameter from 5 to 12 μm when we use a lipid concentration of 5.6 mg/mL. We also determine that MB shell viscosity and stiffness increase with increasing lipid concentration and MB final diameter, and the level of change depends on the degree of shrinkage experienced by the MB. Specifically, we find that by increasing the concentration of lipids from 5.6 to 16.0 mg/mL, the shell stiffness and viscosity of ∼11 μm final diameter MBs increase by ∼400 and ∼200%, respectively. This study demonstrates the feasibility of fine-tuning the MB acoustic response to ultrasound by tailoring the MB initial diameter and lipid concentration.
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Affiliation(s)
- Intesar O Zalloum
- Department of Physics, Toronto Metropolitan University, Toronto M5B 2K3, Ontario, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto M5B 1T8, Ontario, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto M5B 1W8, Ontario, Canada
| | - Amin Jafari Sojahrood
- Department of Physics, Toronto Metropolitan University, Toronto M5B 2K3, Ontario, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto M5B 1T8, Ontario, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto M5B 1W8, Ontario, Canada
| | - Ali A Paknahad
- Department of Mechanical and Industrial Engineering, Toronto Metropolitan University, 350 Victoria Street, Toronto M5B 2K3, Ontario, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto M5B 1T8, Ontario, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto M5B 1W8, Ontario, Canada
| | - Michael C Kolios
- Department of Physics, Toronto Metropolitan University, Toronto M5B 2K3, Ontario, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto M5B 1T8, Ontario, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto M5B 1W8, Ontario, Canada
| | - Scott S H Tsai
- Department of Mechanical and Industrial Engineering, Toronto Metropolitan University, 350 Victoria Street, Toronto M5B 2K3, Ontario, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto M5B 1T8, Ontario, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto M5B 1W8, Ontario, Canada
- Graduate Program in Biomedical Engineering, Toronto Metropolitan University, 350 Victoria Street, Toronto M5B 2K3, Ontario, Canada
| | - Raffi Karshafian
- Department of Physics, Toronto Metropolitan University, Toronto M5B 2K3, Ontario, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto M5B 1T8, Ontario, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto M5B 1W8, Ontario, Canada
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5
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van Elburg B, Deprez J, van den Broek M, De Smedt SC, Versluis M, Lajoinie G, Lentacker I, Segers T. Dependence of sonoporation efficiency on microbubble size: An in vitro monodisperse microbubble study. J Control Release 2023; 363:747-755. [PMID: 37778466 DOI: 10.1016/j.jconrel.2023.09.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/24/2023] [Accepted: 09/26/2023] [Indexed: 10/03/2023]
Abstract
Sonoporation is the process where intracellular drug delivery is facilitated by ultrasound-driven microbubble oscillations. Several mechanisms have been proposed to relate microbubble dynamics to sonoporation including shear and normal stress. The present work aims to gain insight into the role of microbubble size on sonoporation and thereby into the relevant mechanism(s) of sonoporation. To this end, we measured the sonoporation efficiency while varying microbubble size using monodisperse microbubble suspensions. Sonoporation experiments were performed in vitro on cell monolayers using a single ultrasound pulse with a fixed frequency of 1 MHz while the acoustic pressure amplitude and pulse length were varied at 250, 500, and 750 kPa, and 10, 100, and 1000 cycles, respectively. Sonoporation efficiency was quantified using flow cytometry by measuring the FITC-dextran (4 kDa and 2 MDa) fluorescence intensity in 10,000 cells per experiment to average out inherent variations in the bioresponse. Using ultra-high-speed imaging at 10 million frames per second, we demonstrate that the bubble oscillation amplitude is nearly independent of the equilibrium bubble radius at acoustic pressure amplitudes that induce sonoporation (≥ 500 kPa). However, we show that sonoporation efficiency is strongly dependent on the equilibrium bubble size and that under all explored driving conditions most efficiently induced by bubbles with a radius of 4.7 μm. Polydisperse microbubbles with a typical ultrasound contrast agent size distribution perform almost an order of magnitude lower in terms of sonoporation efficiency than the 4.7-μm bubbles. We elucidate that for our system shear stress is highly unlikely the mechanism of action. By contrast, we show that sonoporation efficiency correlates well with an estimate of the bubble-induced normal stress.
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Affiliation(s)
- Benjamin van Elburg
- Physics of Fluids Group and Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
| | - Joke Deprez
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Ghent University, Ghent, Belgium
| | - Martin van den Broek
- BIOS / Lab on a Chip Group, Max-Planck Center Twente for Complex Fluid Dynamics, MESA+ Institute for Nanotechnology, University of Twente, Enschede, Netherlands
| | - Stefaan C De Smedt
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Ghent University, Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Michel Versluis
- Physics of Fluids Group and Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
| | - Guillaume Lajoinie
- Physics of Fluids Group and Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
| | - Ine Lentacker
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Ghent University, Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Tim Segers
- BIOS / Lab on a Chip Group, Max-Planck Center Twente for Complex Fluid Dynamics, MESA+ Institute for Nanotechnology, University of Twente, Enschede, Netherlands.
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6
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Aliabouzar M, Kripfgans OD, Brian Fowlkes J, Fabiilli ML. Bubble nucleation and dynamics in acoustic droplet vaporization: a review of concepts, applications, and new directions. Z Med Phys 2023; 33:387-406. [PMID: 36775778 PMCID: PMC10517405 DOI: 10.1016/j.zemedi.2023.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 12/30/2022] [Accepted: 01/09/2023] [Indexed: 02/12/2023]
Abstract
The development of phase-shift droplets has broadened the scope of ultrasound-based biomedical applications. When subjected to sufficient acoustic pressures, the perfluorocarbon phase in phase-shift droplets undergoes a phase-transition to a gaseous state. This phenomenon, termed acoustic droplet vaporization (ADV), has been the subject of substantial research over the last two decades with great progress made in design of phase-shift droplets, fundamental physics of bubble nucleation and dynamics, and applications. Here, we review experimental approaches, carried out via high-speed microscopy, as well as theoretical models that have been proposed to study the fundamental physics of ADV including vapor nucleation and ADV-induced bubble dynamics. In addition, we highlight new developments of ADV in tissue regeneration, which is a relatively recently exploited application. We conclude this review with future opportunities of ADV for advanced applications such as in situ microrheology and pressure estimation.
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Affiliation(s)
- Mitra Aliabouzar
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.
| | - Oliver D Kripfgans
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - J Brian Fowlkes
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Mario L Fabiilli
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
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7
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Cooley MB, Wulftange WJ, Wegierak D, Goreke U, Abenojar EC, Gurkan UA, Exner AA. Real-time imaging of nanobubble ultrasound contrast agent flow, extravasation, and diffusion through an extracellular matrix using a microfluidic model. LAB ON A CHIP 2023; 23:3453-3466. [PMID: 37424286 DOI: 10.1039/d3lc00514c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Lipid shell-stabilized nanoparticles with a perfluorocarbon gas-core, or nanobubbles, have recently attracted attention as a new contrast agent for molecular ultrasound imaging and image-guided therapy. Due to their small size (∼275 nm diameter) and flexible shell, nanobubbles have been shown to extravasate through hyperpermeable vasculature (e.g., in tumors). However, little is known about the dynamics and depth of extravasation of intact, acoustically active nanobubbles. Accordingly, in this work, we developed a microfluidic chip with a lumen and extracellular matrix (ECM) and imaging method that allows real-time imaging and characterization of the extravasation process with high-frequency ultrasound. The microfluidic device has a lumen and is surrounded by an extracellular matrix with tunable porosity. The combination of ultrasound imaging and the microfluidic chip advantageously produces real-time images of the entire length and depth of the matrix. This captures the matrix heterogeneity, offering advantages over other imaging techniques with smaller fields of view. Results from this study show that nanobubbles diffuse through a 1.3 μm pore size (2 mg mL-1) collagen I matrix 25× faster with a penetration depth that was 0.19 mm deeper than a 3.7 μm (4 mg mL-1) matrix. In the 3.7 μm pore size matrix, nanobubbles diffused 92× faster than large nanobubbles (∼875 nm diameter). Decorrelation time analysis was successfully used to differentiate flowing and extra-luminally diffusing nanobubbles. In this work, we show for the first time that combination of an ultrasound-capable microfluidic chip and real-time imaging provided valuable insight into spatiotemporal nanoparticle movement through a heterogeneous extracellular matrix. This work could help accurately predict parameters (e.g., injection dosage) that improve translation of nanoparticles from in vitro to in vivo environments.
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Affiliation(s)
- Michaela B Cooley
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - William J Wulftange
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Dana Wegierak
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Utku Goreke
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA.
| | - Eric C Abenojar
- Department of Radiology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
| | - Umut A Gurkan
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA.
| | - Agata A Exner
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Department of Radiology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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8
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Huang B, Ge X, Rubinstein BY, Chen X, Wang L, Xie H, Leshansky AM, Li Z. Gas-assisted microfluidic step-emulsification for generating micron- and submicron-sized droplets. MICROSYSTEMS & NANOENGINEERING 2023; 9:86. [PMID: 37435566 PMCID: PMC10330193 DOI: 10.1038/s41378-023-00558-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 05/27/2023] [Accepted: 05/30/2023] [Indexed: 07/13/2023]
Abstract
Micron- and submicron-sized droplets have extensive applications in biomedical diagnosis and drug delivery. Moreover, accurate high-throughput analysis requires a uniform droplet size distribution and high production rates. Although the previously reported microfluidic coflow step-emulsification method can be used to generate highly monodispersed droplets, the droplet diameter (d) is constrained by the microchannel height (b), d ≳ 3 b , while the production rate is limited by the maximum capillary number of the step-emulsification regime, impeding emulsification of highly viscous liquids. In this paper, we report a novel, gas-assisted coflow step-emulsification method, where air serves as the innermost phase of a precursor hollow-core air/oil/water emulsion. Air gradually diffuses out, producing oil droplets. The size of the hollow-core droplets and the ultrathin oil layer thickness both follow the scaling laws of triphasic step-emulsification. The minimal droplet size attains d ≈ 1.7 b , inaccessible in standard all-liquid biphasic step-emulsification. The production rate per single channel is an order-of-magnitude higher than that in the standard all-liquid biphasic step-emulsification and is also superior to alternative emulsification methods. Due to low gas viscosity, the method can also be used to generate micron- and submicron-sized droplets of high-viscosity fluids, while the inert nature of the auxiliary gas offers high versatility.
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Affiliation(s)
- Biao Huang
- Department of Aerospace Engineering, Beijing Institute of Technology, No. 5 ZhongGuanCunNan Street, HaiDian District, Beijing, 100081 China
| | - Xinjin Ge
- State Key Laboratory of Engines, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin, 300350 China
| | | | - Xianchun Chen
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, No. 5 ZhongGuanCunNan Street, HaiDian District, Beijing, 100081 China
| | - Lu Wang
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, No. 5 ZhongGuanCunNan Street, HaiDian District, Beijing, 100081 China
| | - Huiying Xie
- Department of Aerospace Engineering, Beijing Institute of Technology, No. 5 ZhongGuanCunNan Street, HaiDian District, Beijing, 100081 China
| | - Alexander M. Leshansky
- Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa, 32000 Israel
| | - Zhenzhen Li
- Department of Aerospace Engineering, Beijing Institute of Technology, No. 5 ZhongGuanCunNan Street, HaiDian District, Beijing, 100081 China
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9
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Navarro-Becerra JA, Borden MA. Targeted Microbubbles for Drug, Gene, and Cell Delivery in Therapy and Immunotherapy. Pharmaceutics 2023; 15:1625. [PMID: 37376072 DOI: 10.3390/pharmaceutics15061625] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/18/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023] Open
Abstract
Microbubbles are 1-10 μm diameter gas-filled acoustically-active particles, typically stabilized by a phospholipid monolayer shell. Microbubbles can be engineered through bioconjugation of a ligand, drug and/or cell. Since their inception a few decades ago, several targeted microbubble (tMB) formulations have been developed as ultrasound imaging probes and ultrasound-responsive carriers to promote the local delivery and uptake of a wide variety of drugs, genes, and cells in different therapeutic applications. The aim of this review is to summarize the state-of-the-art of current tMB formulations and their ultrasound-targeted delivery applications. We provide an overview of different carriers used to increase drug loading capacity and different targeting strategies that can be used to enhance local delivery, potentiate therapeutic efficacy, and minimize side effects. Additionally, future directions are proposed to improve the tMB performance in diagnostic and therapeutic applications.
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Affiliation(s)
| | - Mark A Borden
- Mechanical Engineering Department, University of Colorado Boulder, Boulder, CO 80309, USA
- Biomedical Engineering Program, University of Colorado Boulder, Boulder, CO 80309, USA
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10
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Chabouh G, van Elburg B, Versluis M, Segers T, Quilliet C, Coupier G. Buckling of lipidic ultrasound contrast agents under quasi-static load. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20220025. [PMID: 36774952 DOI: 10.1098/rsta.2022.0025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 11/10/2022] [Indexed: 06/18/2023]
Abstract
Collapse of lipidic ultrasound contrast agents under high-frequency compressive load has been historically interpreted by the vanishing of surface tension. By contrast, buckling of elastic shells is known to occur when costly compressible stress is released through bending. Through quasi-static compression experiments on lipidic shells, we analyse the buckling events in the framework of classical elastic buckling theory and deduce the mechanical characteristics of these shells. They are then compared with that obtained through acoustic characterization. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.
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Affiliation(s)
- Georges Chabouh
- Université Grenoble Alpes, CNRS, LIPhy, Grenoble 38000, France
| | - Benjamin van Elburg
- Physics of Fluids Group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
| | - Michel Versluis
- Physics of Fluids Group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
| | - Tim Segers
- BIOS/Lab-on-a-Chip Group, Max Planck Center Twente for Complex Fluid Dynamics, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands
| | | | - Gwennou Coupier
- Université Grenoble Alpes, CNRS, LIPhy, Grenoble 38000, France
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11
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Kim K, Lee J, Park MH. Microbubble Delivery Platform for Ultrasound-Mediated Therapy in Brain Cancers. Pharmaceutics 2023; 15:pharmaceutics15020698. [PMID: 36840020 PMCID: PMC9959315 DOI: 10.3390/pharmaceutics15020698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 02/15/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
The blood-brain barrier (BBB) is one of the most selective endothelial barriers that protect the brain and maintains homeostasis in neural microenvironments. This barrier restricts the passage of molecules into the brain, except for gaseous or extremely small hydrophobic molecules. Thus, the BBB hinders the delivery of drugs with large molecular weights for the treatment of brain cancers. Various methods have been used to deliver drugs to the brain by circumventing the BBB; however, they have limitations such as drug diversity and low delivery efficiency. To overcome this challenge, microbubbles (MBs)-based drug delivery systems have garnered a lot of interest in recent years. MBs are widely used as contrast agents and are recently being researched as a vehicle for delivering drugs, proteins, and gene complexes. The MBs are 1-10 μm in size and consist of a gas core and an organic shell, which cause physical changes, such as bubble expansion, contraction, vibration, and collapse, in response to ultrasound. The physical changes in the MBs and the resulting energy lead to biological changes in the BBB and cause the drug to penetrate it, thus enhancing the therapeutic effect. Particularly, this review describes a state-of-the-art strategy for fabricating MB-based delivery platforms and their use with ultrasound in brain cancer therapy.
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Affiliation(s)
- Kibeom Kim
- Department of Chemistry and Life Science, Sahmyook University, Seoul 01795, Republic of Korea
| | - Jungmin Lee
- Convergence Research Center, Nanobiomaterials Institute, Sahmyook University, Seoul 01795, Republic of Korea
| | - Myoung-Hwan Park
- Department of Chemistry and Life Science, Sahmyook University, Seoul 01795, Republic of Korea
- Convergence Research Center, Nanobiomaterials Institute, Sahmyook University, Seoul 01795, Republic of Korea
- Department of Convergence Science, Sahmyook University, Seoul 01795, Republic of Korea
- N to B Co., Ltd., Seoul 01795, Republic of Korea
- Correspondence:
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12
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Silwal A, Upadhyay A, Shakya G, Inzunza-Ibarra M, Murray T, Ding X, Borden MA. Photoacoustic Vaporization of Endoskeletal Droplets Loaded with Zinc Naphthalocyanine. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:168-176. [PMID: 36524827 DOI: 10.1021/acs.langmuir.2c02320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Vaporizable endoskeletal droplets are solid hydrocarbons in liquid fluorocarbon droplets in which melting of the hydrocarbon phase leads to the vaporization of the fluorocarbon phase. In prior work, vaporization of the endoskeletal droplets was achieved thermally by heating the surrounding aqueous medium. In this work, we introduce a near-infrared (NIR) optically absorbing naphthalocyanine dye (zinc 2,11,20,29-tetra-tert-butyl-2,3-naphthalocynanine) into the solid hydrocarbon (eicosane, n-C20H42) core of liquid fluorocarbon (C5F12) drops suspended in an aqueous medium. Droplets with a uniform diameter of 11.7 ± 0.7 μm were formed using a flow-focusing microfluidic device. The solid hydrocarbon formed a crumpled spherical structure within the liquid fluorocarbon droplet. The photoactivation behavior of these dye-containing endoskeletal droplets was investigated using NIR laser irradiation. When exposed to a pulsed laser of 720 nm wavelength, the dye-containing droplets vaporized at an average laser fluence of 65 mJ/cm2, whereas blank droplets without the dye did not vaporize at any fluence up to 100 mJ/cm2. Furthermore, dye-loaded droplets with a smaller, polydisperse size distribution were prepared using a simple shaking method and studied in a flow phantom for their photoacoustic signal and ultrasound contrast imaging. These results demonstrate that dye-containing endoskeletal droplets can be made to vaporize by externally applied optical energy. Such droplets may be useful for a variety of photoacoustic applications for sensing, imaging, and therapy.
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Affiliation(s)
- Anish Silwal
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado80309, United States
| | - Awaneesh Upadhyay
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado80309, United States
| | - Gazendra Shakya
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado80309, United States
| | - Marco Inzunza-Ibarra
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado80309, United States
| | - Todd Murray
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado80309, United States
- Biomaterial Engineering Program, University of Colorado, Boulder, Colorado80309, United States
| | - Xiaoyun Ding
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado80309, United States
- Biomaterial Engineering Program, University of Colorado, Boulder, Colorado80309, United States
| | - Mark A Borden
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado80309, United States
- Biomaterial Engineering Program, University of Colorado, Boulder, Colorado80309, United States
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13
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Batchelor DB, Armistead FJ, Ingram N, Peyman SA, McLaughlan JR, Coletta PL, Evans SD. The Influence of Nanobubble Size and Stability on Ultrasound Enhanced Drug Delivery. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:13943-13954. [PMID: 36322191 PMCID: PMC9671049 DOI: 10.1021/acs.langmuir.2c02303] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Lipid-shelled nanobubbles (NBs) are emerging as potential dual diagnostic and therapeutic agents. Similar to their micron-scale counterparts, microbubbles (1-10 μm), they can act as ultrasound contrast agents as well as locally enhance therapeutic uptake. Recently, it has been shown that the reduced size of NBs (<1 μm) promotes increased uptake and accumulation in tumor interstitial space, which can enhance their diagnostic and therapeutic performance. However, accurate characterization of NB size and concentration is challenging and may limit their translation into clinical use. Their submicron nature limits accuracy of conventional microscopy techniques, while common light scattering techniques fail to distinguish between subpopulations present in NB samples (i.e., bubbles and liposomes). Due to the difficulty in the characterization of NBs, relatively little is known about the influence of size on their therapeutic performance. In this study, we describe a novel method of using a commercially available nanoparticle tracking analysis system, to distinguish between NBs and liposomes based on their differing optical properties. We used this technique to characterize three NB populations of varying size, isolated via centrifugation, and subsequently used this to assess their potential for enhancing localized delivery. Confocal fluorescence microscopy and image analysis were used to quantify the ultrasound enhanced uptake of fluorescent dextran into live colorectal cancer cells. Our results showed that the amount of localized uptake did not follow the expected trends, in which larger NB populations out-perform smaller NBs, at matched concentration. To understand this observed behavior, the stability of each NB population was assessed. It was found that dilution of the NB samples from their stock concentration influences their stability, and it is hypothesized that both the total free lipid and interbubble distance play a role in NB lifetime, in agreement with previously proposed theories and models.
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Affiliation(s)
- Damien
V. B. Batchelor
- Molecular
and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Fern J. Armistead
- Molecular
and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Nicola Ingram
- Leeds
Institute of Medical Research, Wellcome Trust Brenner Building, St James’s University Hospital, LeedsLS9 7TF, United Kingdom
- Faculty
of Electronic and Electrical Engineering, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Sally A. Peyman
- Molecular
and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - James R. McLaughlan
- Leeds
Institute of Medical Research, Wellcome Trust Brenner Building, St James’s University Hospital, LeedsLS9 7TF, United Kingdom
- Faculty
of Electronic and Electrical Engineering, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - P. Louise Coletta
- Leeds
Institute of Medical Research, Wellcome Trust Brenner Building, St James’s University Hospital, LeedsLS9 7TF, United Kingdom
| | - Stephen D. Evans
- Molecular
and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, LeedsLS2 9JT, United Kingdom
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14
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Zalloum IO, Paknahad AA, Kolios MC, Karshafian R, Tsai SSH. Controlled Shrinkage of Microfluidically Generated Microbubbles by Tuning Lipid Concentration. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:13021-13029. [PMID: 36260341 DOI: 10.1021/acs.langmuir.2c01439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Monodisperse microbubbles with diameters less than 10 μm are desirable in several ultrasound imaging and therapeutic delivery applications. However, conventional approaches to synthesize microbubbles, which are usually agitation-based, produce polydisperse bubbles that are less desirable because of their heterogeneous response when exposed to an ultrasound field. Microfluidics technology has the unique advantage of generating size-controlled monodisperse microbubbles, and it is now well established that the diameter of microfluidically made microbubbles can be tuned by varying the liquid flow rate, gas pressure, and dimensions of the microfluidic channel. It is also observed that once the microbubbles form, the bubbles shrink and eventually stabilize to a quasi-equilibrium diameter, and that the rate of stabilization is related to the lipid solution. However, how the lipid solution concentration affects the degree of bubble shrinkage, and the stable size of microbubbles, has not been thoroughly examined. Here, we investigate whether and how the lipid concentration affects the degree of microbubble shrinkage. Namely, we utilize a flow-focusing microfluidic geometry to generate monodisperse bubbles, and observe the effect of gas composition (2.5, 1.42, and 0.17 wt % octafluoropropane in nitrogen) and lipid concentration (1-16 mg/mL) on the degree of microbubble shrinkage. For the lipid system and gas utilized in these experiments, we observe a monotonic increase in the degree of microbubble shrinkage with decreasing lipid concentration, and no dependency on the gas composition. We hypothesize that the degree of shrinkage is related to lipid concentration by the self-assembly of lipids on the gas-liquid interface during bubble generation and subsequent lipid packing on the interface during shrinkage, which is arrested when a maximum packing density is achieved. We anticipate that this approach for creating and tuning the size of monodisperse microbubbles will find utility in biomedical applications, such as contrast-enhanced ultrasound imaging and ultrasound-triggered gene delivery.
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Affiliation(s)
- Intesar O Zalloum
- Department of Physics, Toronto Metropolitan University, Toronto, Ontario M5B 2K3, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto, Ontario M5B 1T8, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto, Ontario M5B 1W8, Canada
| | - Ali A Paknahad
- Department of Mechanical and Industrial Engineering, Toronto Metropolitan University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto, Ontario M5B 1T8, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto, Ontario M5B 1W8, Canada
| | - Michael C Kolios
- Department of Physics, Toronto Metropolitan University, Toronto, Ontario M5B 2K3, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto, Ontario M5B 1T8, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto, Ontario M5B 1W8, Canada
| | - Raffi Karshafian
- Department of Physics, Toronto Metropolitan University, Toronto, Ontario M5B 2K3, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto, Ontario M5B 1T8, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto, Ontario M5B 1W8, Canada
| | - Scott S H Tsai
- Department of Mechanical and Industrial Engineering, Toronto Metropolitan University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael's Hospital, 209 Victoria Street, Toronto, Ontario M5B 1T8, Canada
- Keenan Research Centre for Biomedical Science, Unity Health Toronto, 209 Victoria Street, Toronto, Ontario M5B 1W8, Canada
- Graduate Program in Biomedical Engineering, Toronto Metropolitan University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada
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15
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Azami RH, Aliabouzar M, Osborn J, Kumar KN, Forsberg F, Eisenbrey JR, Mallik S, Sarkar K. Material Properties, Dissolution and Time Evolution of PEGylated Lipid-Shelled Microbubbles: Effects of the Polyethylene Glycol Hydrophilic Chain Configurations. ULTRASOUND IN MEDICINE & BIOLOGY 2022; 48:1720-1732. [PMID: 35697583 PMCID: PMC9357055 DOI: 10.1016/j.ultrasmedbio.2022.04.216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 03/21/2022] [Accepted: 04/21/2022] [Indexed: 05/12/2023]
Abstract
Polyethylene glycol (PEG) is often added to the lipid coating of a contrast microbubble to prevent coalescence and improve circulation. At high surface density, PEG chains are known to undergo a transition from a mushroom configuration to an extended brush configuration. We investigated the effects of PEG chain configuration on attenuation and dissolution of microbubbles by varying the molar ratio of the PEGylated lipid in the shell with three (0%, 2% and 5%) in the mushroom configuration and two (10% and 20%) in the brush configuration. We measured attenuation through the bubble suspensions and used it to obtain the characteristic rheological properties of their shells according to two interfacial rheological models. The interfacial elasticity was found to be significantly lower in the brush regime (∼0.6 N/m) than in the mushroom regime (∼1.3 N/m), but similar in value within each regime. The dissolution behavior of microbubbles under acoustic excitation inside an air-saturated medium was studied by measuring the time-dependent attenuation. Total attenuation recorded a transient increase because of growth resulting from air influx and an eventual decrease caused by dissolution. Microbubble shell composition with varying PEG concentrations had significant effects on dissolution dynamics.
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Affiliation(s)
- Roozbeh H Azami
- Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, USA
| | - Mitra Aliabouzar
- Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, USA
| | - Jenna Osborn
- Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, USA
| | - Krishna N Kumar
- Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, USA
| | - Flemming Forsberg
- Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - John R Eisenbrey
- Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Sanku Mallik
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota, USA
| | - Kausik Sarkar
- Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, USA.
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16
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Khan AH, Jiang X, Kaushik A, Nair HS, Edirisinghe M, Mercado-Shekhar KP, Shekhar H, Dalvi SV. Combining Ultrasound and Capillary-Embedded T-Junction Microfluidic Devices to Scale Up the Production of Narrow-Sized Microbubbles through Acoustic Fragmentation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10288-10304. [PMID: 35943351 DOI: 10.1021/acs.langmuir.2c01676] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Microbubbles are tiny gas-filled bubbles that have a variety of applications in ultrasound imaging and therapeutic drug delivery. Microbubbles can be synthesized using a number of techniques including sonication, amalgamation, and saline shaking. These approaches can produce highly concentrated microbubble suspensions but offer minimal control over the size and polydispersity of the microbubbles. One of the simplest and effective methods for producing monodisperse microbubbles is capillary-embedded T-junction microfluidic devices, which offer great control over the microbubble size. However, lower production rates (∼200 bubbles/s) and large microbubble sizes (∼300 μm) limit the applicability of such devices for biomedical applications. To overcome the limitations of these technologies, we demonstrate in this work an alternative approach to combine a capillary-embedded T-junction device with ultrasound to enhance the generation of narrow-sized microbubbles in aqueous suspensions. Two T-junction microfluidic devices were connected in parallel and combined with an ultrasonic horn to produce lipid-coated SF6 core microbubbles in the size range of 1-8 μm. The rate of microbubble production was found to increase from 180 microbubbles/s in the absence of ultrasound to (6.5 ± 1.2) × 106 bubble/s in the presence of ultrasound (100% ultrasound amplitude). When stored in a closed environment, the microbubbles were observed to be stable for up to 30 days, with the concentration of the microbubble suspension decreasing from ∼2.81 × 109/mL to ∼2.3 × 106/mL and the size changing from 1.73 ± 0.2 to 1.45 ± 0.3 μm at the end of 30 days. The acoustic response of these microbubbles was examined using broadband attenuation spectroscopy, and flow phantom imaging was performed to determine the ability of these microbubble suspensions to enhance the contrast relative to the surrounding tissue. Overall, this approach of coupling ultrasound with microfluidic parallelization enabled the continuous production of stable microbubbles at high production rates and low polydispersity using simple T-junction devices.
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Affiliation(s)
- Aaqib H Khan
- Chemical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, Gujarat, India
| | - Xinyue Jiang
- Department of Mechanical Engineering, University College London (UCL), London WC1E 7JE, U.K
| | - Anuj Kaushik
- Electrical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, Gujarat, India
| | - Hari S Nair
- Biological Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, Gujarat, India
| | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London (UCL), London WC1E 7JE, U.K
| | - Karla P Mercado-Shekhar
- Biological Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, Gujarat, India
| | - Himanshu Shekhar
- Electrical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, Gujarat, India
| | - Sameer V Dalvi
- Chemical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, Gujarat, India
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17
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Counil C, Abenojar E, Perera R, Exner AA. Extrusion: A New Method for Rapid Formulation of High-Yield, Monodisperse Nanobubbles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200810. [PMID: 35587613 PMCID: PMC9233137 DOI: 10.1002/smll.202200810] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/24/2022] [Indexed: 06/03/2023]
Abstract
Shell-stabilized gas microbubbles (MB) and nanobubbles (NB) are frequently used for biomedical ultrasound imaging and therapeutic applications. While it is widely recognized that monodisperse bubbles can be more effective in these applications, the efficient formulation of uniform bubbles at high concentrations is difficult to achieve. Here, it is demonstrated that a standard mini-extruder setup, commonly used to make vesicles or liposomes, can be used to quickly and efficiently generate monodisperse NBs with high yield. In this highly reproducible technique, the NBs obtained have an average diameter of 0.16 ± 0.05 µm and concentration of 6.2 ± 1.8 × 1010 NBs mL-1 compared to 0.32 ± 0.1 µm and 3.2 ± 0.7 × 1011 mL-1 for NBs made using mechanical agitation. Parameters affecting the extrusion and NB generation process including the temperature, concentration of the lipid solution, and the number of passages through the extruder are also examined. Moreover, it is demonstrated that extruded NBs show a strong acoustic response in vitro and a strong and persistent US signal enhancement under nonlinear contrast enhanced ultrasound imaging in mice. The extrusion process is a new, efficient, and scalable technique that can be used to easily produce high yield smaller monodispersed nanobubbles.
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Affiliation(s)
- Claire Counil
- Department of Radiology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-7207, USA
| | - Eric Abenojar
- Department of Radiology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-7207, USA
| | - Reshani Perera
- Department of Radiology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-7207, USA
| | - Agata A Exner
- Department of Radiology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-7207, USA
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18
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Krafft MP, Riess JG. Therapeutic oxygen delivery by perfluorocarbon-based colloids. Adv Colloid Interface Sci 2021; 294:102407. [PMID: 34120037 DOI: 10.1016/j.cis.2021.102407] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 03/18/2021] [Accepted: 03/25/2021] [Indexed: 02/06/2023]
Abstract
After the protocol-related indecisive clinical trial of Oxygent, a perfluorooctylbromide/phospholipid nanoemulsion, in cardiac surgery, that often unduly assigned the observed untoward effects to the product, the development of perfluorocarbon (PFC)-based O2 nanoemulsions ("blood substitutes") has come to a low. Yet, significant further demonstrations of PFC O2-delivery efficacy have continuously been reported, such as relief of hypoxia after myocardial infarction or stroke; protection of vital organs during surgery; potentiation of O2-dependent cancer therapies, including radio-, photodynamic-, chemo- and immunotherapies; regeneration of damaged nerve, bone or cartilage; preservation of organ grafts destined for transplantation; and control of gas supply in tissue engineering and biotechnological productions. PFC colloids capable of augmenting O2 delivery include primarily injectable PFC nanoemulsions, microbubbles and phase-shift nanoemulsions. Careful selection of PFC and other colloid components is critical. The basics of O2 delivery by PFC nanoemulsions will be briefly reminded. Improved knowledge of O2 delivery mechanisms has been acquired. Advanced, size-adjustable O2-delivering nanoemulsions have been designed that have extended room-temperature shelf-stability. Alternate O2 delivery options are being investigated that rely on injectable PFC-stabilized microbubbles or phase-shift PFC nanoemulsions. The latter combine prolonged circulation in the vasculature, capacity for penetrating tumor tissues, and acute responsiveness to ultrasound and other external stimuli. Progress in microbubble and phase-shift emulsion engineering, control of phase-shift activation (vaporization), understanding and control of bubble/ultrasound/tissue interactions is discussed. Control of the phase-shift event and of microbubble size require utmost attention. Further PFC-based colloidal systems, including polymeric micelles, PFC-loaded organic or inorganic nanoparticles and scaffolds, have been devised that also carry substantial amounts of O2. Local, on-demand O2 delivery can be triggered by external stimuli, including focused ultrasound irradiation or tumor microenvironment. PFC colloid functionalization and targeting can help adjust their properties for specific indications, augment their efficacy, improve safety profiles, and expand the range of their indications. Many new medical and biotechnological applications involving fluorinated colloids are being assessed, including in the clinic. Further uses of PFC-based colloidal nanotherapeutics will be briefly mentioned that concern contrast diagnostic imaging, including molecular imaging and immune cell tracking; controlled delivery of therapeutic energy, as for noninvasive surgical ablation and sonothrombolysis; and delivery of drugs and genes, including across the blood-brain barrier. Even when the fluorinated colloids investigated are designed for other purposes than O2 supply, they will inevitably also carry and deliver a certain amount of O2, and may thus be considered for O2 delivery or co-delivery applications. Conversely, O2-carrying PFC nanoemulsions possess by nature a unique aptitude for 19F MR imaging, and hence, cell tracking, while PFC-stabilized microbubbles are ideal resonators for ultrasound contrast imaging and can undergo precise manipulation and on-demand destruction by ultrasound waves, thereby opening multiple theranostic opportunities.
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Affiliation(s)
- Marie Pierre Krafft
- University of Strasbourg, Institut Charles Sadron (CNRS), 23 rue du Loess, 67034 Strasbourg, France.
| | - Jean G Riess
- Harangoutte Institute, 68160 Ste Croix-aux-Mines, France
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19
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Wang S, Zhou L, Wang X, Hu J, Li P, Lin G, Gao Y, Zhang L, Wang C. Collective Dynamics of Bulk Nanobubbles with Size-Dependent Surface Tension. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:7986-7994. [PMID: 34157841 DOI: 10.1021/acs.langmuir.1c00973] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
It has been suggested that irreversible adsorption at the gas/liquid interface of bulk nanobubbles will reduce the Laplace pressure, leading to their stability. However, most previous studies have focused on the stability of individual nanobubbles. Bulk nanobubbles are polydispersed suspensions, and gas molecules can diffuse between bubbles, leading to their collective dynamics, which may be crucial to understanding their formation process and stability. In this study, we proposed a mean-field theory for computing the evolution of the size-distribution function of bulk nanobubbles with size-dependent surface tension. We applied this theory to investigate the evolution of bulk nanobubbles with insoluble surfactants pinned at their gas/water interface. The results show that Ostwald ripening can be suppressed when enough surfactants are adsorbed. Bulk nanobubbles can be produced by the shrinkage of microbubbles in an air-saturated solution. The mean stable size is controlled by the amount of surfactants and the initial microbubble concentration; these predictions are qualitatively consistent with the experimental results of micro/nanobubbles produced using the microfluidic method.
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Affiliation(s)
- Shuo Wang
- Institute for advanced study, Shenzhen University, Shenzhen 518060, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Limin Zhou
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai Synchrotron Radiation Facility, Shanghai 201204, China
| | - Xingya Wang
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai Synchrotron Radiation Facility, Shanghai 201204, China
| | - Jun Hu
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai Synchrotron Radiation Facility, Shanghai 201204, China
- Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai 201800, China
| | - Pan Li
- School of Environmental Science and Engineering, Tongji University, Shanghai 200082, China
| | - Guanhua Lin
- Institute for advanced study, Shenzhen University, Shenzhen 518060, China
| | - Yongxiang Gao
- Institute for advanced study, Shenzhen University, Shenzhen 518060, China
| | - Lijuan Zhang
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai Synchrotron Radiation Facility, Shanghai 201204, China
- Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai 201800, China
| | - Chunlei Wang
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai Synchrotron Radiation Facility, Shanghai 201204, China
- Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai 201800, China
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20
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Collado-Lara G, Heymans SV, Godart J, D'Agostino E, D'hooge J, Van Den Abeele K, Vos HJ, de Jong N. Effect of a Radiotherapeutic Megavoltage Beam on Ultrasound Contrast Agents. ULTRASOUND IN MEDICINE & BIOLOGY 2021; 47:1857-1867. [PMID: 33810887 DOI: 10.1016/j.ultrasmedbio.2021.02.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 06/12/2023]
Abstract
Collateral damage to healthy surrounding tissue during conventional radiotherapy increases when deviations from the treatment plan occur. Ultrasound contrast agents (UCAs) are a possible candidate for radiation dose monitoring. This study investigated the size distribution and acoustic response of two commercial formulations, SonoVue/Lumason and Definity/Luminity, as a function of dose on clinical megavoltage photon beam exposure (24 Gy). SonoVue samples exhibited a decrease in concentration of bubbles smaller than 7 µm, together with an increase in acoustic attenuation and a decrease in acoustic scattering. Definity samples did not exhibit a significant response to radiation, suggesting that the effect of megavoltage photons depends on the UCA formulation. For SonoVue, the influence of the megavoltage photon beam was especially apparent at the second harmonic frequency, and can be captured using pulse inversion and amplitude modulation (3.5-dB decrease for the maximum dose), which could eventually be used for dosimetry in a well-controlled environment.
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Affiliation(s)
- Gonzalo Collado-Lara
- Biomedical Engineering, Department of Cardiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands.
| | - Sophie V Heymans
- Department of Physics, KU Leuven Campus Kulak, Kortrijk, Belgium
| | - Jeremy Godart
- Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands
| | | | - Jan D'hooge
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | | | - Hendrik J Vos
- Biomedical Engineering, Department of Cardiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Nico de Jong
- Biomedical Engineering, Department of Cardiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
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21
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Abou-Saleh RH, Armistead FJ, Batchelor DVB, Johnson BRG, Peyman SA, Evans SD. Horizon: Microfluidic platform for the production of therapeutic microbubbles and nanobubbles. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:074105. [PMID: 34340422 DOI: 10.1063/5.0040213] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 06/17/2021] [Indexed: 06/13/2023]
Abstract
Microbubbles (MBs) have a multitude of applications including as contrast agents in ultrasound imaging and as therapeutic drug delivery vehicles, with further scope for combining their diagnostic and therapeutic properties (known as theranostics). MBs used clinically are commonly made by mechanical agitation or sonication methods, which offer little control over population size and dispersity. Furthermore, clinically used MBs are yet to be used therapeutically and further research is needed to develop these theranostic agents. In this paper, we present our MB production instrument "Horizon," which is a robust, portable, and user-friendly instrument, integrating the key components for producing MBs using microfluidic flow-focusing devices. In addition, we present the system design and specifications of Horizon and the optimized protocols that have so far been used to produce MBs with specific properties. These include MBs with tailored size and low dispersity (monodisperse); MBs with a diameter of ∼2 μm, which are more disperse but also produced in higher concentration; nanobubbles with diameters of 100-600 nm; and therapeutic MBs with drug payloads for targeted delivery. Multiplexed chips were able to improve production rates up to 16-fold while maintaining production stability. This work shows that Horizon is a versatile instrument with potential for mass production and use across many research facilities, which could begin to bridge the gap between therapeutic MB research and clinical use.
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Affiliation(s)
- Radwa H Abou-Saleh
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Fern J Armistead
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Damien V B Batchelor
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Benjamin R G Johnson
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Sally A Peyman
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Stephen D Evans
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
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22
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van Elburg B, Collado-Lara G, Bruggert GW, Segers T, Versluis M, Lajoinie G. Feedback-controlled microbubble generator producing one million monodisperse bubbles per second. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:035110. [PMID: 33820052 DOI: 10.1063/5.0032140] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Monodisperse lipid-coated microbubbles are a promising route to unlock the full potential of ultrasound contrast agents for medical diagnosis and therapy. Here, we present a stand-alone lab-on-a-chip instrument that allows microbubbles to be formed with high monodispersity at high production rates. Key to maintaining a long-term stable, controlled, and safe operation of the microfluidic device with full control over the output size distribution is an optical transmission-based measurement technique that provides real-time information on the production rate and bubble size. We feed the data into a feedback loop and demonstrate that this system can control the on-chip bubble radius (2.5 μm-20 μm) and the production rate up to 106 bubbles/s. The freshly formed phospholipid-coated bubbles stabilize after their formation to a size approximately two times smaller than their initial on-chip bubble size without loss of monodispersity. The feedback control technique allows for full control over the size distribution of the agent and can aid the development of microfluidic platforms operated by non-specialist end users.
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Affiliation(s)
- Benjamin van Elburg
- Physics of Fluids Group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Gonzalo Collado-Lara
- Physics of Fluids Group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Gert-Wim Bruggert
- Physics of Fluids Group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Tim Segers
- Physics of Fluids Group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Michel Versluis
- Physics of Fluids Group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Guillaume Lajoinie
- Physics of Fluids Group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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23
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Chabouh G, Dollet B, Quilliet C, Coupier G. Spherical oscillations of encapsulated microbubbles: Effect of shell compressibility and anisotropy. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 149:1240. [PMID: 33639825 DOI: 10.1121/10.0003500] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 01/21/2021] [Indexed: 06/12/2023]
Abstract
We introduce a model that describes spherical oscillations of encapsulated microbubbles in an unbounded surrounding fluid. A Rayleigh-Plesset-like equation is derived by coupling the Navier-Stokes equation that describes fluid dynamics with the Navier equation that describes solid dynamics via the internal/external boundary conditions. While previous models were restricted to incompressible isotropic shells, the solid shell is modeled here as a compressible viscoelastic isotropic material and then generalized to an anisotropic material. The exact value of the resonance frequency is calculated analytically, and the damping constant is computed in the approximation of weak damping. A correction of the widely used Church model for incompressible shells is evidenced, and the effects of shell compressibility and anisotropy are discussed.
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Affiliation(s)
- Georges Chabouh
- Université Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - Benjamin Dollet
- Université Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | | | - Gwennou Coupier
- Université Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
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24
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25
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Helbert A, Gaud E, Segers T, Botteron C, Frinking P, Jeannot V. Monodisperse versus Polydisperse Ultrasound Contrast Agents: In Vivo Sensitivity and safety in Rat and Pig. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:3339-3352. [PMID: 33008649 DOI: 10.1016/j.ultrasmedbio.2020.07.031] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 07/24/2020] [Accepted: 07/30/2020] [Indexed: 05/21/2023]
Abstract
Recent advances in the field of monodisperse microbubble synthesis by flow focusing allow for the production of foam-free, highly concentrated and monodisperse lipid-coated microbubble suspensions. It has been found that in vitro, such monodisperse ultrasound contrast agents (UCAs) improve the sensitivity of contrast-enhanced ultrasound imaging. Here, we present the first in vivo study in the left ventricle of rat and pig with this new monodisperse bubble agent. We systematically characterize the acoustic sensitivity and safety of the agent at an imaging frequency of 2.5 MHz as compared with three commercial polydisperse UCAs (SonoVue/Lumason, Definity/Luminity and Optison) and one research-grade polydisperse agent with the same shell composition as the monodisperse bubbles. The monodisperse microbubbles, which had a diameter of 4.2 μm, crossed the pulmonary vasculature, and their echo signal could be measured at least as long as that of the polydisperse UCAs, indicating that microfluidically formed monodisperse microbubbles are stable in vivo. Furthermore, it was found that the sensitivity of the monodisperse agent, expressed as the mean echo power per injected bubble, was at least 10 times higher than that of the polydisperse UCAs. Finally, the safety profile of the monodisperse microbubble suspension was evaluated by injecting 400 and 2000 times the imaging dose, and neither physiologic nor pathologic changes were found, which is a first indication that monodisperse lipid-coated microbubbles formed by flow focusing are safe for in vivo use. The more uniform acoustic response and corresponding increased imaging sensitivity of the monodisperse agent may boost emerging applications of microbubbles and ultrasound such as molecular imaging and therapy.
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Affiliation(s)
- Alexandre Helbert
- Bracco Suisse S.A., Route de la Galaise 31, 1228 Plan-les-Ouates, Switzerland
| | - Emmanuel Gaud
- Bracco Suisse S.A., Route de la Galaise 31, 1228 Plan-les-Ouates, Switzerland
| | - Tim Segers
- Physics of Fluids Group, MESA + Institute for Nanotechnology, Technical Medical (TechMed) Center, University of Twente, Enschede, The Netherlands; Former employee of Bracco Suisse S.A
| | | | | | - Victor Jeannot
- Bracco Suisse S.A., Route de la Galaise 31, 1228 Plan-les-Ouates, Switzerland.
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26
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Versluis M, Stride E, Lajoinie G, Dollet B, Segers T. Ultrasound Contrast Agent Modeling: A Review. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:2117-2144. [PMID: 32546411 DOI: 10.1016/j.ultrasmedbio.2020.04.014] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 04/11/2020] [Accepted: 04/14/2020] [Indexed: 05/21/2023]
Abstract
Ultrasound is extensively used in medical imaging, being safe and inexpensive and operating in real time. Its scope of applications has been widely broadened by the use of ultrasound contrast agents (UCAs) in the form of microscopic bubbles coated by a biocompatible shell. Their increased use has motivated a large amount of research to understand and characterize their physical properties as well as their interaction with the ultrasound field and their surrounding environment. Here we review the theoretical models that have been proposed to study and predict the behavior of UCAs. We begin with a brief introduction on the development of UCAs. We then present the basics of free-gas-bubble dynamics upon which UCA modeling is based. We review extensively the linear and non-linear models for shell elasticity and viscosity and present models for non-spherical and asymmetric bubble oscillations, especially in the presence of surrounding walls or tissue. Then, higher-order effects such as microstreaming, shedding and acoustic radiation forces are considered. We conclude this review with promising directions for the modeling and development of novel agents.
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Affiliation(s)
- Michel Versluis
- Physics of Fluids Group, MESA+ Institute for Nanotechnology, Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands.
| | - Eleanor Stride
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, UK
| | - Guillaume Lajoinie
- Physics of Fluids Group, MESA+ Institute for Nanotechnology, Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
| | - Benjamin Dollet
- Centre National de la Recherche Scientifique (CNRS), Laboratoire Interdisciplinaire de Physique (LIPhy), Université Grenoble Alpes, Grenoble, France
| | - Tim Segers
- Physics of Fluids Group, MESA+ Institute for Nanotechnology, Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
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27
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Stride E, Segers T, Lajoinie G, Cherkaoui S, Bettinger T, Versluis M, Borden M. Microbubble Agents: New Directions. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:1326-1343. [PMID: 32169397 DOI: 10.1016/j.ultrasmedbio.2020.01.027] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 01/09/2020] [Accepted: 01/26/2020] [Indexed: 05/24/2023]
Abstract
Microbubble ultrasound contrast agents have now been in use for several decades and their safety and efficacy in a wide range of diagnostic applications have been well established. Recent progress in imaging technology is facilitating exciting developments in techniques such as molecular, 3-D and super resolution imaging and new agents are now being developed to meet their specific requirements. In parallel, there have been significant advances in the therapeutic applications of microbubbles, with recent clinical trials demonstrating drug delivery across the blood-brain barrier and into solid tumours. New agents are similarly being tailored toward these applications, including nanoscale microbubble precursors offering superior circulation times and tissue penetration. The development of novel agents does, however, present several challenges, particularly regarding the regulatory framework. This article reviews the developments in agents for diagnostic, therapeutic and "theranostic" applications; novel manufacturing techniques; and the opportunities and challenges for their commercial and clinical translation.
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Affiliation(s)
- Eleanor Stride
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.
| | - Tim Segers
- Physics of Fluids Group, Technical Medical (TechMed) Centre, MESA+ Institute for Nanotechnology, University of Twente, The Netherlands
| | - Guillaume Lajoinie
- Physics of Fluids Group, Technical Medical (TechMed) Centre, MESA+ Institute for Nanotechnology, University of Twente, The Netherlands
| | - Samir Cherkaoui
- Bracco Suisse SA - Business Unit Imaging, Global R&D, Plan-les-Ouates, Switzerland
| | - Thierry Bettinger
- Bracco Suisse SA - Business Unit Imaging, Global R&D, Plan-les-Ouates, Switzerland
| | - Michel Versluis
- Physics of Fluids Group, Technical Medical (TechMed) Centre, MESA+ Institute for Nanotechnology, University of Twente, The Netherlands
| | - Mark Borden
- Mechanical Engineering Department, University of Colorado, Boulder, CO, USA
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28
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Lytra A, Sboros V, Giannakopoulos A, Pelekasis N. Modeling atomic force microscopy and shell mechanical properties estimation of coated microbubbles. SOFT MATTER 2020; 16:4661-4681. [PMID: 32391535 DOI: 10.1039/d0sm00300j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We present an extensive comparison with experimental data of our theoretical/numerical model for the static response of coated microbubbles (MBs) subject to compression from an atomic force microscope (afm). The mechanics of the MB's coating is described in the context of elastic thin shell theory. The encapsulated fluid is treated as compressible/incompressible pertaining to a gas/liquid, while the thinning of the liquid film between the MB and the afm cantilever is modeled via introduction of an interaction potential and the resulting disjoining pressure. As the external force increases, the experimental force-deformation (f-d) curves of MBs covered with polymer have an initial linear response (Reissner regime), followed by a non-linear curved downwards response (Pogorelov regime) where buckling takes place. On the other hand, the f-d curve for MBs covered with lipid monolayers initially follows the Reissner regime, but buckling is bypassed to a curved upwards regime where internal gas pressure dominates. The elastic properties, namely Young's modulus and shell thickness, for MB's covered with polymer can be estimated by combining the buckling point and the slope of the Reissner regime or the slopes of Reissner and Pogorelov regimes. Comparison of the present model with afm f-d curves for polymer shows satisfactory agreement. The area dilatation and bending moduli are shown to be the appropriate independent elastic parameters of MBs covered with phospholipid monolayers and are estimated by combination of the transition from Reissner to pressure dominated regime. Simulations and experiments in this case are in excellent agreement.
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Affiliation(s)
- A Lytra
- Department of Mechanical Engineering, University of Thessaly, Volos, 38334, Greece.
| | - V Sboros
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - A Giannakopoulos
- School of Applied Mathematics, Physics and Mechanics, National Technical University of Athens, Athens, 15780, Greece
| | - N Pelekasis
- Department of Mechanical Engineering, University of Thessaly, Volos, 38334, Greece.
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29
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Frinking P, Segers T, Luan Y, Tranquart F. Three Decades of Ultrasound Contrast Agents: A Review of the Past, Present and Future Improvements. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:892-908. [PMID: 31941587 DOI: 10.1016/j.ultrasmedbio.2019.12.008] [Citation(s) in RCA: 131] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 06/10/2023]
Abstract
Initial reports from the 1960s describing the observations of ultrasound contrast enhancement by tiny gaseous bubbles during echocardiographic examinations prompted the development of the first ultrasound contrast agent in the 1980s. Current commercial contrast agents for echography, such as Definity, Optison, Sonazoid and SonoVue, have proven to be successful in a variety of on- and off-label clinical indications. Whereas contrast-specific technology has seen dramatic progress after the introduction of the first approved agents in the 1990s, successful clinical translation of new developments has been limited during the same period, while understanding of microbubble physical, chemical and biologic behavior has improved substantially. It is expected that for a successful development of future opportunities, such as ultrasound molecular imaging and therapeutic applications using microbubbles, new creative developments in microbubble engineering and production dedicated to further optimizing microbubble performance are required, and that they cannot rely on bubble technology developed more than 3 decades ago.
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Affiliation(s)
- Peter Frinking
- Tide Microfluidics, Capitool 41, Enschede, The Netherlands.
| | - Tim Segers
- Physics of Fluids group, University of Twente, Enschede, The Netherlands
| | - Ying Luan
- R&D Pharmaceutical Diagnostics, General Electric Healthcare, Amersham, UK
| | - François Tranquart
- R&D Pharmaceutical Diagnostics, General Electric Healthcare, Amersham, UK
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30
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Staton JA, Stearns SW, Dungan SR. Mechanism of Time-Dependent Adsorption for Phosphatidylcholine onto a Clean Air-Water Interface from a Dispersion of Vesicles: Effect of Temperature and Acyl Chain Length. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16850-16861. [PMID: 31815494 DOI: 10.1021/acs.langmuir.9b02904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Dynamic surface tension measurements were used to track adsorption kinetics for dilauroylphosphatidylcholine (DLPC) or dimyristoylphosphatidylcholine (DMPC) from monodisperse vesicle dispersions to an air-water interface at elevated temperatures ≥30 °C. Effects of vesicle concentration, aqueous solubility of the lipids, and temperature T on the adsorption kinetics were determined, and the controlling transport pathway was identified. Adsorption dynamics were tracked for 0.1-10 mM DLPC at 30 and 38 °C and for 1-10 mM DMPC at 30, 50, and 58 °C. Experimental results were compared to theoretical predictions for a reaction-enhanced, molecular transport mechanism, which was previously shown to effectively predict DLPC adsorption kinetics at 22 °C. At higher temperatures, for DLPC concentrations ≥0.25 mM or DMPC concentrations ≥1 mM, a weak dependence of adsorption time on concentration was observed, again consistent with the reaction-enhanced molecular pathway. Molecular release rates from vesicles increased with increasing temperature or decreasing acyl chain length. At equivalent ratios T/Tm of the dispersion temperature to the lipid chain phase transition temperature Tm, measured adsorption times for DLPC were approximately 10-fold shorter than those for DMPC, suggesting that the fluidity of the acyl tails is not the only lipid property determining adsorption rates. Despite the significant difference in aqueous solubility and chain phase transition temperature between DLPC and DMPC, the results provide further evidence for an adsorption mechanism that is well described by diffusion of molecular lipid, with rates of molecular diffusion near the interface enhanced by release from nearby vesicles.
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31
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de Leon A, Perera R, Hernandez C, Cooley M, Jung O, Jeganathan S, Abenojar E, Fishbein G, Sojahrood AJ, Emerson CC, Stewart PL, Kolios MC, Exner AA. Contrast enhanced ultrasound imaging by nature-inspired ultrastable echogenic nanobubbles. NANOSCALE 2019; 11:15647-15658. [PMID: 31408083 PMCID: PMC6716144 DOI: 10.1039/c9nr04828f] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Advancement of ultrasound molecular imaging applications requires not only a reduction in size of the ultrasound contrast agents (UCAs) but also a significant improvement in the in vivo stability of the shell-stabilized gas bubble. The transition from first generation to second generation UCAs was marked by an advancement in stability as air was replaced by a hydrophobic gas, such as perfluoropropane and sulfur hexafluoride. Further improvement can be realized by focusing on how well the UCAs shell can retain the encapsulated gas under extreme mechanical deformations. Here we report the next generation of UCAs for which we engineered the shell structure to impart much better stability under repeated prolonged oscillation due to ultrasound, and large changes in shear and turbulence as it circulates within the body. By adapting an architecture with two layers of contrasting elastic properties similar to bacterial cell envelopes, our ultrastable nanobubbles (NBs) withstand continuous in vitro exposure to ultrasound with minimal signal decay and have a significant delay on the onset of in vivo signal decay in kidney, liver, and tumor. Development of ultrastable NBs can potentially expand the role of ultrasound in molecular imaging, theranostics, and drug delivery.
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Affiliation(s)
- Al de Leon
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Reshani Perera
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Christopher Hernandez
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Michaela Cooley
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Olive Jung
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Selva Jeganathan
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Eric Abenojar
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Grace Fishbein
- Department of Physics, Ryerson University, Toronto, ON, Canada
| | | | - Corey C Emerson
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Phoebe L Stewart
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | | | - Agata A Exner
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA. and Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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32
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Hall RL, Juan-Sing ZD, Hoyt K, Sirsi SR. Formulation and Characterization of Chemically Cross-linked Microbubble Clusters. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10977-10986. [PMID: 31310715 PMCID: PMC7061884 DOI: 10.1021/acs.langmuir.9b00475] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The purpose of this study is to introduce a new concept of chemically cross-linked microbubble clusters (CCMCs), which are individual microbubble ultrasound contrast agents (UCAs) physically tethered together. We demonstrate a facile means of their production, characterize their size and stability, and describe how they can potentially be used in biomedical applications. By tethering UCAs together into CCMCs, we propose that novel methods of ultrasound mediated imaging and therapy can be developed through unique interbubble interactions in an ultrasound field. One of the major challenges in generating CCMCs is controlling aggregate sizes and maintaining stability against Ostwald ripening and coalescence. In this study, we demonstrate that chemically cross-linked microbubble clusters can produce small (<10 μm) quasi-stable complexes that slowly fuse into bubbles with individual gas cores. Furthermore, we demonstrate that this process can be driven with low-intensity ultrasound pulses, enabling a rapid fusion of clusters which could potentially be used to develop novel ultrasound contrast imaging and drug delivery strategies in future studies. The development of novel microbubble clusters presents a simple yet robust process for generating novel UCAs with a design that could allow for more versatility in contrast-enhanced ultrasound (CEUS), molecular imaging, and drug delivery applications. Additionally, microbubble clustering is a unique way to control size, shell, and gas compositions that can be used to study bubble ripening and coalescence in a highly controlled environment or study the behavior of mixed-microbubble populations.
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Affiliation(s)
- Ronald L. Hall
- University of Texas at Dallas, Richardson, Texas, 75080, United States
| | | | - Kenneth Hoyt
- University of Texas at Dallas, Richardson, Texas, 75080, United States
- University of Texas Southwestern, Dallas, Texas, 75390, United States
| | - Shashank R. Sirsi
- University of Texas at Dallas, Richardson, Texas, 75080, United States
- University of Texas Southwestern, Dallas, Texas, 75390, United States
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33
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Borden MA. Intermolecular Forces Model for Lipid Microbubble Shells. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10042-10051. [PMID: 30543753 DOI: 10.1021/acs.langmuir.8b03641] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lipid-coated microbubbles are currently used clinically as ultrasound contrast agents for echocardiography and radiology and are being developed for many new diagnostic and therapeutic applications. Accordingly, there is a growing need to engineer specific formulations by employing rational design to guide lipid selection and processing. This approach requires a quantitative relationship between lipid chemistry and interfacial properties of the microbubble shell. Just such a model is proposed here on the basis of lateral Coulomb and van der Waals interactions between lipid head- and tailgroups, using previous coarse graining and force fields developed for molecular dynamics simulations. The model predicts with sufficient accuracy the monolayer permeability, the elasticity as a function of either lipid composition or temperature, and the equilibrium spreading surface tension of the lipid onto an air/water interface. In the future, the intermolecular forces model could be employed to elucidate more complex phenomena and to engineer novel microbubble formulations.
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Affiliation(s)
- Mark Andrew Borden
- Mechanical Engineering , University of Colorado , Boulder , Colorado 80309-0427 , United States
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Owen J, Kamila S, Shrivastava S, Carugo D, Bernardino de la Serna J, Mannaris C, Pereno V, Browning R, Beguin E, McHale AP, Callan JF, Stride E. The Role of PEG-40-stearate in the Production, Morphology, and Stability of Microbubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10014-10024. [PMID: 30485112 DOI: 10.1021/acs.langmuir.8b02516] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Phospholipid coated microbubbles are currently in widespread clinical use as ultrasound contrast agents and under investigation for therapeutic applications. Previous studies have demonstrated the importance of the coating nanostructure in determining microbubble stability and its dependence upon both composition and processing method. While the influence of different phospholipids has been widely investigated, the role of other constituents such as emulsifiers has received comparatively little attention. Herein, we present an examination of the impact of polyethylene glycol (PEG) derivatives upon microbubble structure and properties. We present data using both pegylated phospholipids and a fluorescent PEG-40-stearate analogue synthesized in-house to directly observe its distribution in the microbubble coating. We examined microbubbles of clinically relevant sizes, investigating both their surface properties and population size distribution and stability. Domain formation was observed only on the surface of larger microbubbles, which were found to contain a higher concentration of PEG-40-stearate. Lipid analogue dyes were also found to influence domain formation compared with PEG-40-stearate alone. "Squeezing out" of PEG-40-stearate was not observed from any of the microbubble sizes investigated. At ambient temperature, microbubbles formulated with DSPE-PEG(2000) were found to be more stable than those containing PEG-40-stearate. At 37 °C, however, the stability in serum was found to be the same for both formulations, and no difference in acoustic backscatter was detected. This could potentially reduce the cost of PEGylated microbubbles and facilitate simpler attachment of targeting or therapeutic species. However, whether PEG-40-stearate sufficiently shields microbubbles to inhibit physiological clearance mechanisms still requires investigation.
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Affiliation(s)
- Joshua Owen
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Sukanta Kamila
- School of Pharmacy and Pharmaceutical Science , University of Ulster , Coleraine BT52 1SA , United Kingdom
| | - Shamit Shrivastava
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Dario Carugo
- Faculty of Engineering and the Environment , University of Southampton , Highfield, Southampton SO17 1BJ , United Kingdom
| | - Jorge Bernardino de la Serna
- Central Laser Facility , STFC Rutherford Appleton Laboratory , Harwell Campus , Didcot OX11 0QX , United Kingdom
| | - Christophoros Mannaris
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Valerio Pereno
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Richard Browning
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Estelle Beguin
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Anthony P McHale
- School of Pharmacy and Pharmaceutical Science , University of Ulster , Coleraine BT52 1SA , United Kingdom
| | - John F Callan
- School of Pharmacy and Pharmaceutical Science , University of Ulster , Coleraine BT52 1SA , United Kingdom
| | - Eleanor Stride
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
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Ha JH, Mazumdar H, Kim TH, Lee JM, Na JG, Chung BG. Algorithm Analysis of Gas Bubble Generation in a Microfluidic Device. BIOCHIP JOURNAL 2019. [DOI: 10.1007/s13206-018-3203-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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36
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Valadbaigi P, Ettelaie R, Kulak AN, Murray BS. Generation of ultra-stable Pickering microbubbles via poly alkylcyanoacrylates. J Colloid Interface Sci 2019; 536:618-627. [DOI: 10.1016/j.jcis.2018.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/01/2018] [Accepted: 10/03/2018] [Indexed: 12/16/2022]
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Helfield B. A Review of Phospholipid Encapsulated Ultrasound Contrast Agent Microbubble Physics. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:282-300. [PMID: 30413335 DOI: 10.1016/j.ultrasmedbio.2018.09.020] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 08/11/2018] [Accepted: 09/20/2018] [Indexed: 06/08/2023]
Abstract
Ultrasound contrast agent microbubbles have expanded the utility of biomedical ultrasound from anatomic imaging to the assessment of microvascular blood flow characteristics and ultrasound-assisted therapeutic applications. Central to their effectiveness in these applications is their resonant and non-linear oscillation behaviour. This article reviews the salient physics of an oscillating microbubble in an ultrasound field, with particular emphasis on phospholipid-coated agents. Both the theoretical underpinnings of bubble vibration and the experimental evidence of non-linear encapsulated bubble dynamics and scattering are discussed and placed within the context of current and emerging applications.
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Affiliation(s)
- Brandon Helfield
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
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38
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Segers T, Lassus A, Bussat P, Gaud E, Frinking P. Improved coalescence stability of monodisperse phospholipid-coated microbubbles formed by flow-focusing at elevated temperatures. LAB ON A CHIP 2018; 19:158-167. [PMID: 30511070 DOI: 10.1039/c8lc00886h] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Monodisperse phospholipid-coated ultrasound contrast agent (UCA) microbubbles can be directly synthesized in a lab-on-a-chip flow-focusing device. However, high total lipid concentrations are required to minimize on-chip bubble coalescence. Here, we characterize the coalescence probability and the long-term size stability of microbubbles formed using DPPC and DSPC based lipid mixtures as a function of temperature. We show that the coalescence probability can be dramatically reduced by increasing the temperature during bubble formation. Moreover, it is shown that the increased coalescence stability can be explained from an exponential increase of the relative viscosity in the thin liquid film between the colliding bubbles. Furthermore, it was found that the relative viscosity of a DPPC lipid mixture is 7.6 times higher than that of a DSPC mixture and that it can be explained solely from the higher DPPC liposome concentration. Regarding long-term bubble stability, the ratio of the initial on-chip bubble size to the final stable bubble size was always found to be 2.2 for DPPC and DSPC coated bubbles with 10 mol% DPPE-PEG5000, independent of the temperature. Moreover, it was demonstrated that the microbubble suspensions formed at elevated temperatures are highly stable over a time window of 2 to 4 days when collected in a vial. All in all, this work shows that, by increasing the temperature during bubble formation from room temperature to 70 °C, the efficiency of the use of phospholipids in microbubble formation by flow-focusing can be increased by 5 times.
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Affiliation(s)
- Tim Segers
- Bracco Suisse S.A., Route de la Galaise 31, 1228 Geneva, Switzerland.
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Segers T, Gaud E, Versluis M, Frinking P. High-precision acoustic measurements of the nonlinear dilatational elasticity of phospholipid coated monodisperse microbubbles. SOFT MATTER 2018; 14:9550-9561. [PMID: 30357244 DOI: 10.1039/c8sm00918j] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The acoustic response of phospholipid-coated microbubble ultrasound contrast agents (UCA) is dramatically affected by their stabilizing shell. The interfacial shell elasticity increases the resonance frequency, the shell viscosity increases damping, and the nonlinear shell viscoelasticity increases the generation of harmonic echoes that are routinely used in contrast-enhanced ultrasound imaging. To date, the surface area-dependent interfacial properties of the phospholipid coating have never been measured due to the extremely short time scales of the MHz frequencies at which the microscopic bubbles are driven. Here, we present high-precision acoustic measurements of the dilatational nonlinear viscoelastic shell properties of phospholipid-coated microbubbles. These highly accurate measurements are now accessible for the first time by tuning the surface dilatation, that is, the lipid packing density, of well-controlled monodisperse bubble suspensions through the ambient pressure. Upon compression, the shell elasticity of bubbles coated with DPPC and DPPE-PEG5000 was found to increase up to an elasticity of 0.6 N m-1 after which the monolayer collapses and the elasticity vanishes. During bubble expansion, the elasticity drops monotonically in two stages, first to an elasticity of 0.35 N m-1, and then more rapidly to zero. Integration of the elasticity vs. surface area curves showed that, indeed, a phospholipid-coated microbubble is in a tensionless state upon compression, and that it reaches the interfacial tension of the surrounding medium upon expansion. The measurements presented in this work reveal the detailed features of the nonlinear dilatational shell behavior of micron-sized lipid-coated bubbles.
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Affiliation(s)
- Tim Segers
- Bracco Suisse S.A., Route de la Galaise 31, 1228 Geneva, Switzerland.
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40
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Borden MA, Song KH. Reverse engineering the ultrasound contrast agent. Adv Colloid Interface Sci 2018; 262:39-49. [PMID: 30396507 PMCID: PMC6268001 DOI: 10.1016/j.cis.2018.10.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 10/09/2018] [Accepted: 10/22/2018] [Indexed: 12/31/2022]
Abstract
In this review, a brief history and current state-of-the-art is given to stimulate the rational design of new microbubbles through the reverse engineering of current ultrasound contrast agents (UCAs). It is shown that an effective microbubble should be biocompatible, echogenic and stable. Physical mechanisms and engineering calculations have been provided to illustrate these properties and how they can be achieved. The reverse-engineering design paradigm is applied to study current FDA-approved and commercially available UCAs. Given the sophistication of microbubble designs reported in the literature, rapid development and adoption of ultrasound device hardware and techniques, and the growing number of revolutionary biomedical applications moving toward the clinic, the field of Microbubble Engineering is fertile for breakthroughs in next-generation UCA technology. It is up to current and future microbubble engineers and clinicians to push forward with regulatory approval and clinical adoption of advanced UCA technologies in the years to come.
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Affiliation(s)
- Mark A Borden
- Mechanical Engineering, University of Colorado, Boulder, CO 80309-0427, USA.
| | - Kang-Ho Song
- Mechanical Engineering, University of Colorado, Boulder, CO 80309-0427, USA
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41
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Pulsipher KW, Hammer DA, Lee D, Sehgal CM. Engineering Theranostic Microbubbles Using Microfluidics for Ultrasound Imaging and Therapy: A Review. ULTRASOUND IN MEDICINE & BIOLOGY 2018; 44:2441-2460. [PMID: 30241729 PMCID: PMC6643280 DOI: 10.1016/j.ultrasmedbio.2018.07.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 07/05/2018] [Accepted: 07/27/2018] [Indexed: 05/05/2023]
Abstract
Microbubbles interact with ultrasound in various ways to enable their applications in ultrasound imaging and diagnosis. To generate high contrast and maximize therapeutic efficacy, microbubbles of high uniformity are required. Microfluidic technology, which enables precise control of small volumes of fluid at the sub-millimeter scale, has provided a versatile platform on which to produce highly uniform microbubbles for potential applications in ultrasound imaging and diagnosis. Here, we describe fundamental microfluidic principles and the most common types of microfluidic devices used to produce sub-10 μm microbubbles, appropriate for biomedical ultrasound. Bubbles can be engineered for specific applications by tailoring the bubble size, inner gas and shell composition and by functionalizing for additional imaging modalities, therapeutics or targeting ligands. To translate the laboratory-scale discoveries to widespread clinical use of these microfluidic-based microbubbles, increased bubble production is needed. We present various strategies recently developed to improve scale-up. We conclude this review by describing some outstanding problems in the field and presenting areas for future use of microfluidics in ultrasound.
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Affiliation(s)
- Katherine W Pulsipher
- Department of Chemical and Biomolecular Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Daniel A Hammer
- Department of Chemical and Biomolecular Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Daeyeon Lee
- Department of Chemical and Biomolecular Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Chandra M Sehgal
- Department of Radiology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA.
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42
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Zhu L, Wang L, Liu Y, Xu D, Fang K, Guo Y. CAIX aptamer-functionalized targeted nanobubbles for ultrasound molecular imaging of various tumors. Int J Nanomedicine 2018; 13:6481-6495. [PMID: 30410333 PMCID: PMC6199208 DOI: 10.2147/ijn.s176287] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Purpose Targeted nanobubbles can penetrate the tumor vasculature and achieve ultrasound molecular imaging (USMI) of tumor parenchymal cells. However, most targeted nanobubbles only achieve USMI of tumor parenchymal cells from one organ, and their distribution, loading ability, and binding ability in tumors are not clear. Therefore, targeted nanobubbles loaded with carbonic anhydrase IX (CAIX) aptamer were fabricated for USMI of various tumors, and the morphological basis of USMI with targeted nanobubbles was investigated. Materials and methods The specificity of CAIX aptamer at the cellular level was measured by immunofluorescence and flow cytometry. Targeted nanobubbles loaded with CAIX aptamer were prepared by a maleimidethiol coupling reaction, and their binding ability to CAIX-positive tumor cells was analyzed in vitro. USMI of targeted and non-targeted nanobubbles was performed in tumor-bearing nude mice. The distribution, loading ability, and binding ability of targeted nanobubbles in xenograft tumor tissues were demonstrated by immunofluorescence. Results CAIX aptamer could specifically bind to CAIX-positive 786-O and Hela cells, rather than CAIX-negative BxPC-3 cells. Targeted nanobubbles loaded with CAIX aptamer had the advantages of small size, uniform distribution, regular shape, and high safety, and they could specifically accumulate around 786-O and Hela cells, while not binding to BxPC-3 cells in vitro. Targeted nanobubbles had significantly higher peak intensity and larger area under the curve than non-targeted nanobubbles in 786-O and Hela xenograft tumor tissues, while there was no significant difference in the imaging effects of targeted and non-targeted nanobubbles in BxPC-3 xenograft tumor tissues. Immunofluorescence demonstrated targeted nanobubbles could still load CAIX aptamer after penetrating the tumor vasculature and specifically binding to CAIX-positive tumor cells in xenograft tumor tissues. Conclusion Targeted nanobubbles loaded with CAIX aptamer have a good imaging effect in USMI of tumor parenchymal cells, and can improve the accuracy of early diagnosis of malignant tumors from various organs.
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Affiliation(s)
- Lianhua Zhu
- Department of Ultrasound, Southwest Hospital, Third Military Medical University (Army Medical University), Shapingba District, Chongqing, China,
| | - Luofu Wang
- Department of Urology, Daping Hospital, Third Military Medical University (Army Medical University), Yuzhong District, Chongqing, China
| | - Yu Liu
- Department of Ultrasound, Southwest Hospital, Third Military Medical University (Army Medical University), Shapingba District, Chongqing, China,
| | - Dan Xu
- Department of Ultrasound, Southwest Hospital, Third Military Medical University (Army Medical University), Shapingba District, Chongqing, China,
| | - Kejing Fang
- Department of Ultrasound, Southwest Hospital, Third Military Medical University (Army Medical University), Shapingba District, Chongqing, China,
| | - Yanli Guo
- Department of Ultrasound, Southwest Hospital, Third Military Medical University (Army Medical University), Shapingba District, Chongqing, China,
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43
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Segers T, Kruizinga P, Kok MP, Lajoinie G, de Jong N, Versluis M. Monodisperse Versus Polydisperse Ultrasound Contrast Agents: Non-Linear Response, Sensitivity, and Deep Tissue Imaging Potential. ULTRASOUND IN MEDICINE & BIOLOGY 2018; 44:1482-1492. [PMID: 29705522 DOI: 10.1016/j.ultrasmedbio.2018.03.019] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/21/2018] [Accepted: 03/21/2018] [Indexed: 05/21/2023]
Abstract
It has been proposed that monodisperse microbubble ultrasound contrast agents further increase the signal-to-noise ratio of contrast-enhanced ultrasound imaging. Here, the sensitivity of a polydisperse pre-clinical agent was compared experimentally with that of its size- and acoustically sorted derivatives by using narrowband pressure- and frequency-dependent scattering and attenuation measurements. The sorted monodisperse agents had up to a two-orders-of-magnitude increase in sensitivity, that is, in the average scattering cross section per bubble. Moreover, we found, for the first time, that the highly non-linear response of acoustically sorted microbubbles can be exploited to confine scattering and attenuation to the focal region of ultrasound fields used in clinical imaging. This property is a result of minimal pre-focal scattering and attenuation and can be used to minimize shadowing effects in deep tissue imaging. Moreover, it potentially allows for more localized therapy using microbubbles through the spatial control of resonant microbubble oscillations.
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Affiliation(s)
- Tim Segers
- Physics of Fluids Group and TechMed Centre, University of Twente, Enschede, The Netherlands.
| | - Pieter Kruizinga
- Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands
| | - Maarten P Kok
- Physics of Fluids Group and TechMed Centre, University of Twente, Enschede, The Netherlands
| | - Guillaume Lajoinie
- Physics of Fluids Group and TechMed Centre, University of Twente, Enschede, The Netherlands
| | - Nico de Jong
- Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands; Acoustical Wavefield imaging, Delft University of Technology, Delft, The Netherlands
| | - Michel Versluis
- Physics of Fluids Group and TechMed Centre, University of Twente, Enschede, The Netherlands; MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands
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44
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Song R, Peng C, Xu X, Wang J, Yu M, Hou Y, Zou R, Yao S. Controllable Formation of Monodisperse Polymer Microbubbles as Ultrasound Contrast Agents. ACS APPLIED MATERIALS & INTERFACES 2018; 10:14312-14320. [PMID: 29637761 DOI: 10.1021/acsami.7b17258] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Microbubbles have been widely used as ultrasound contrast agents in clinical diagnosis and hold great potential for ultrasound-mediated therapy. However, polydispersed population and short half-life time (<10 min) of the microbubbles still limit their applications in imaging and therapy. To tackle these problems, we develop a microfluidic flow-focusing approach to produce monodisperse microbubbles stabilized by Poly(lactic-co-glycolic acid) (PLGA) as the polymer shell. The size of PLGA microbubbles can be tightly controlled from ∼600 nm to ∼7 μm with a coefficient of variation less than 4% in size distribution for ensuring highly homogeneous echogenic behavior of PLGA polymer microbubbles in ultrasound fields. Both in vitro and in vivo experiments showed that the monodisperse PLGA microbubbles had excellent echogenicity and elongated sonographic duration time (>3 times) for ultrasound imaging in comparison with the commercial lipid microbubbles.
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Affiliation(s)
| | - Chuan Peng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Department of Ultrasound , Sun Yat-sen University Cancer Center , 510060 Guangzhou , China
| | | | - Jianwei Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Department of Ultrasound , Sun Yat-sen University Cancer Center , 510060 Guangzhou , China
| | | | | | - Ruhai Zou
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Department of Ultrasound , Sun Yat-sen University Cancer Center , 510060 Guangzhou , China
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45
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Das D, Sivasubramanian K, Yang C, Pramanik M. On-chip generation of microbubbles in photoacoustic contrast agents for dual modal ultrasound/photoacoustic in vivo animal imaging. Sci Rep 2018; 8:6401. [PMID: 29686407 PMCID: PMC5913135 DOI: 10.1038/s41598-018-24713-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 04/10/2018] [Indexed: 12/12/2022] Open
Abstract
Dual-modal photoacoustic (PA) and ultrasound (US) contrast agents are becoming increasingly popular in recent years. Here, a flow-focusing junction based microfluidic device is used for the generation of nitrogen microbubbles (<7 μm) in two photoacoustic contrast agents: methylene blue (MB) and black ink (BI). The microbubble diameter and production rate could be precisely controlled in both MB and BI solutions. Microbubbles were collected from the outlet of the microfluidic device and optical microscope was used to study the size distributions in both solutions. Next, the microbubbles in both solutions were injected into tubes for phantom imaging experiments. Signal to noise ratio (SNR) of both US, PA imaging experiments were calculated to be 51 dB, 58 dB in MB + microbubbles and 56 dB, 61 dB in BI + microbubbles, respectively. Finally, the microbubbles were injected into the urinary bladder of rats for in vivo animal imaging. The SNR in US imaging with MB + microbubbles and BI + microbubbles were 41 dB and 48 dB, respectively. Similarly, the SNR in PA imaging with the same solutions were 32 dB and 36 dB, respectively. The effect of size and concentration of microbubbles in both MB and BI solutions, on the US and PA signals, has been examined.
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Affiliation(s)
- Dhiman Das
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459, Singapore
| | - Kathyayini Sivasubramanian
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459, Singapore
| | - Chun Yang
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Manojit Pramanik
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459, Singapore.
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Beekers I, van Rooij T, Verweij MD, Versluis M, de Jong N, Trietsch SJ, Kooiman K. Acoustic Characterization of a Vessel-on-a-Chip Microfluidic System for Ultrasound-Mediated Drug Delivery. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2018; 65:570-581. [PMID: 29610087 DOI: 10.1109/tuffc.2018.2803137] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Ultrasound in the presence of gas-filled microbubbles can be used to enhance local uptake of drugs and genes. To study the drug delivery potential and its underlying physical and biological mechanisms, an in vitro vessel model should ideally include 3-D cell culture, perfusion flow, and membrane-free soft boundaries. Here, we propose an organ-on-a-chip microfluidic platform to study ultrasound-mediated drug delivery: the OrganoPlate. The acoustic propagation into the OrganoPlate was determined to assess the feasibility of controlled microbubble actuation, which is required to study the microbubble-cell interaction for drug delivery. The pressure field in the OrganoPlate was characterized non-invasively by studying experimentally the well-known response of microbubbles and by simulating the acoustic wave propagation in the system. Microbubble dynamics in the OrganoPlate were recorded with the Brandaris 128 ultrahigh-speed camera (17 million frames/s) and a control experiment was performed in an OptiCell, an in vitro monolayer cell culture chamber that is conventionally used to study ultrasound-mediated drug delivery. When insonified at frequencies between 1 and 2 MHz, microbubbles in the OrganoPlate experienced larger oscillation amplitudes resulting from higher local pressures. Microbubbles responded similarly in both systems when insonified at frequencies between 2 and 4 MHz. Numerical simulations performed with a 3-D finite-element model of ultrasound propagation into the OrganoPlate and the OptiCell showed the same frequency-dependent behavior. The predictable and homogeneous pressure field in the OrganoPlate demonstrates its potential to develop an in vitro 3-D cell culture model, well suited to study ultrasound-mediated drug delivery.
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47
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Lum JS, Stobbe DM, Borden MA, Murray TW. Photoacoustic technique to measure temperature effects on microbubble viscoelastic properties. APPLIED PHYSICS LETTERS 2018; 112:111905. [PMID: 29576628 PMCID: PMC5851782 DOI: 10.1063/1.5005548] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 02/27/2018] [Indexed: 06/08/2023]
Abstract
Phospholipid-coated microbubbles are being developed for several biomedical applications, but little is known about the effect of temperature on the viscoelastic properties of the shell. Here, we report on the use of a photoacoustic technique to study the shell properties of individual microbubbles as a function of temperature. The microbubbles were driven into small-amplitude oscillations by ultrasound waves generated from the absorption of an intensity-modulated infrared laser, and these oscillations were detected by forward-light scattering of a second blue laser. The drive laser modulation frequency was swept to determine the resonant response of 2-4 μm radius microbubbles. Lipid shell elasticity and viscosity were determined by modeling the microbubble response as a linear harmonic oscillator. The results from slow heating showed a linear decrease in elasticity and viscosity between 21 and 53 °C and a corresponding increase in the maximum oscillation amplitude. Rapid heating to 38 °C, on the other hand, showed a transient response in the viscoelastic properties, suggesting shell rupture and reformation during microbubble growth and subsequent dissolution. These effects are important for biomedical applications, which require warming of the microbubbles to body temperature.
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Affiliation(s)
- Jordan S. Lum
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - David M. Stobbe
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Mark A. Borden
- Authors to whom correspondence should be addressed: . Telephone: 303.492.7236 and . Telephone: 303.492.7750
| | - Todd W. Murray
- Authors to whom correspondence should be addressed: . Telephone: 303.492.7236 and . Telephone: 303.492.7750
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48
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Slenders E, Seneca S, Pramanik SK, Smisdom N, Adriaensens P, vandeVen M, Ethirajan A, Ameloot M. Dynamics of the phospholipid shell of microbubbles: a fluorescence photoselection and spectral phasor approach. Chem Commun (Camb) 2018; 54:4854-4857. [DOI: 10.1039/c8cc01012a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The lipid organization of microbubbles is important in many applications.
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Affiliation(s)
- Eli Slenders
- Biomedical Research Institute (BIOMED)
- Hasselt University
- Agoralaan Bldg. C
- 3590 Diepenbeek
- Belgium
| | - Senne Seneca
- Institute for Materials Research (IMO)
- Hasselt University
- Wetenschapspark 1 and Agoralaan Bldg. D
- 3590 Diepenbeek
- Belgium
| | - Sumit Kumar Pramanik
- Institute for Materials Research (IMO)
- Hasselt University
- Wetenschapspark 1 and Agoralaan Bldg. D
- 3590 Diepenbeek
- Belgium
| | - Nick Smisdom
- Biomedical Research Institute (BIOMED)
- Hasselt University
- Agoralaan Bldg. C
- 3590 Diepenbeek
- Belgium
| | - Peter Adriaensens
- Institute for Materials Research (IMO)
- Hasselt University
- Wetenschapspark 1 and Agoralaan Bldg. D
- 3590 Diepenbeek
- Belgium
| | - Martin vandeVen
- Biomedical Research Institute (BIOMED)
- Hasselt University
- Agoralaan Bldg. C
- 3590 Diepenbeek
- Belgium
| | - Anitha Ethirajan
- Institute for Materials Research (IMO)
- Hasselt University
- Wetenschapspark 1 and Agoralaan Bldg. D
- 3590 Diepenbeek
- Belgium
| | - Marcel Ameloot
- Biomedical Research Institute (BIOMED)
- Hasselt University
- Agoralaan Bldg. C
- 3590 Diepenbeek
- Belgium
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Salari A, Gnyawali V, Griffiths IM, Karshafian R, Kolios MC, Tsai SSH. Shrinking microbubbles with microfluidics: mathematical modelling to control microbubble sizes. SOFT MATTER 2017; 13:8796-8806. [PMID: 29135012 DOI: 10.1039/c7sm01418j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Microbubbles have applications in industry and life-sciences. In medicine, small encapsulated bubbles (<10 μm) are desirable because of their utility in drug/oxygen delivery, sonoporation, and ultrasound diagnostics. While there are various techniques for generating microbubbles, microfluidic methods are distinguished due to their precise control and ease-of-fabrication. Nevertheless, sub-10 μm diameter bubble generation using microfluidics remains challenging, and typically requires expensive equipment and cumbersome setups. Recently, our group reported a microfluidic platform that shrinks microbubbles to sub-10 μm diameters. The microfluidic platform utilizes a simple microbubble-generating flow-focusing geometry, integrated with a vacuum shrinkage system, to achieve microbubble sizes that are desirable in medicine, and pave the way to eventual clinical uptake of microfluidically generated microbubbles. A theoretical framework is now needed to relate the size of the microbubbles produced and the system's input parameters. In this manuscript, we characterize microbubbles made with various lipid concentrations flowing in solutions that have different interfacial tensions, and monitor the changes in bubble size along the microfluidic channel under various vacuum pressures. We use the physics governing the shrinkage mechanism to develop a mathematical model that predicts the resulting bubble sizes and elucidates the dominant parameters controlling bubble sizes. The model shows a good agreement with the experimental data, predicting the resulting microbubble sizes under different experimental input conditions. We anticipate that the model will find utility in enabling users of the microfluidic platform to engineer bubbles of specific sizes.
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Affiliation(s)
- A Salari
- Biomedical Engineering Graduate Program, Ryerson University, Toronto, Canada
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50
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Segers T, Lohse D, Versluis M, Frinking P. Universal Equations for the Coalescence Probability and Long-Term Size Stability of Phospholipid-Coated Monodisperse Microbubbles Formed by Flow Focusing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:10329-10339. [PMID: 28872315 DOI: 10.1021/acs.langmuir.7b02547] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Resonantly driven monodisperse phospholipid-coated microbubbles are expected to substantially increase the sensitivity and efficiency in contrast-enhanced ultrasound imaging and therapy. They can be produced in a microfluidic flow-focusing device, but questions remain as to the role of the device geometry, the liquid and gas flow, and the phospholipid formulation on bubble stability. Here, we develop a model based on simple continuum mechanics equations that reveals the scaling of the coalescence probability with the key physical parameters. It is used to characterize short-term coalescence behavior and long-term size stability as a function of flow-focusing geometry, bulk viscosity, lipid cosolvent mass fraction, lipid concentration, lipopolymer molecular weight, and lipopolymer molar fraction. All collected data collapse on two master curves given by universal equations for the coalescence probability and the long-term size stability. This work is therefore a route to a more fundamental understanding of the physicochemical monolayer properties of microfluidically formed bubbles and their coalescence behavior in a flow-focusing device.
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Affiliation(s)
- Tim Segers
- Bracco Suisse S.A., Route de la Galaise 31, 1228 Geneva, Switzerland
| | - Detlef Lohse
- Physics of Fluids group, MIRA Institute for Biomedical Technology and Technical Medicine, MESA+ Institute for Nanotechnology, University of Twente , Postbus 217, 7500 AE Enschede, The Netherlands
| | - Michel Versluis
- Physics of Fluids group, MIRA Institute for Biomedical Technology and Technical Medicine, MESA+ Institute for Nanotechnology, University of Twente , Postbus 217, 7500 AE Enschede, The Netherlands
| | - Peter Frinking
- Bracco Suisse S.A., Route de la Galaise 31, 1228 Geneva, Switzerland
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