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Pattinson O, Keller SB, Evans ND, Pierron F, Carugo D. An Acoustic Device for Ultra High-Speed Quantification of Cell Strain During Cell-Microbubble Interaction. ACS Biomater Sci Eng 2023; 9:5912-5923. [PMID: 37747762 PMCID: PMC10565720 DOI: 10.1021/acsbiomaterials.3c00757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 09/11/2023] [Indexed: 09/26/2023]
Abstract
Microbubbles utilize high-frequency oscillations under ultrasound stimulation to induce a range of therapeutic effects in cells, often through mechanical stimulation and permeabilization of cells. One of the largest challenges remaining in the field is the characterization of interactions between cells and microbubbles at therapeutically relevant frequencies. Technical limitations, such as employing sufficient frame rates and obtaining sufficient image resolution, restrict the quantification of the cell's mechanical response to oscillating microbubbles. Here, a novel methodology was developed to address many of these limitations and improve the image resolution of cell-microbubble interactions at high frame rates. A compact acoustic device was designed to house cells and microbubbles as well as a therapeutically relevant acoustic field while being compatible with a Shimadzu HPV-X camera. Cell viability tests confirmed the successful culture and proliferation of cells, and the attachment of DSPC- and cationic DSEPC-microbubbles to osteosarcoma cells was quantified. Microbubble oscillation was observed within the device at a frame rate of 5 million FPS, confirming suitable acoustic field generation and ultra high-speed image capture. High spatial resolution in these images revealed observable deformation in cells following microbubble oscillation and supported the first use of digital image correlation for strain quantification in a single cell. The novel acoustic device provided a simple, effective method for improving the spatial resolution of cell-microbubble interaction images, presenting the opportunity to develop an understanding of the mechanisms driving the therapeutic effects of oscillating microbubbles upon ultrasound exposure.
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Affiliation(s)
- Oliver Pattinson
- Faculty
of Engineering and Physical Sciences, University
of Southampton, University Road, Southampton SO17 1BJ, United Kingdom
| | - Sara B. Keller
- Department
of Engineering Science, University of Oxford, Old Road, Headington, Oxford OX3 7LD, U.K.
| | - Nicholas D. Evans
- Faculty
of Engineering and Physical Sciences, University
of Southampton, University Road, Southampton SO17 1BJ, United Kingdom
| | - Fabrice Pierron
- Faculty
of Engineering and Physical Sciences, University
of Southampton, University Road, Southampton SO17 1BJ, United Kingdom
| | - Dario Carugo
- Nuffield
Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences
(NDORMS), University of Oxford, Old Road, Headington, Oxford OX3 7LD, United Kingdom
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2
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Biomechanical Sensing Using Gas Bubbles Oscillations in Liquids and Adjacent Technologies: Theory and Practical Applications. BIOSENSORS 2022; 12:bios12080624. [PMID: 36005019 PMCID: PMC9406219 DOI: 10.3390/bios12080624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/06/2022] [Accepted: 08/07/2022] [Indexed: 11/17/2022]
Abstract
Gas bubbles present in liquids underpin many natural phenomena and human-developed technologies that improve the quality of life. Since all living organisms are predominantly made of water, they may also contain bubbles—introduced both naturally and artificially—that can serve as biomechanical sensors operating in hard-to-reach places inside a living body and emitting signals that can be detected by common equipment used in ultrasound and photoacoustic imaging procedures. This kind of biosensor is the focus of the present article, where we critically review the emergent sensing technologies based on acoustically driven oscillations of bubbles in liquids and bodily fluids. This review is intended for a broad biosensing community and transdisciplinary researchers translating novel ideas from theory to experiment and then to practice. To this end, all discussions in this review are written in a language that is accessible to non-experts in specific fields of acoustics, fluid dynamics and acousto-optics.
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3
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Beekers I, Langeveld SAG, Meijlink B, van der Steen AFW, de Jong N, Verweij MD, Kooiman K. Internalization of targeted microbubbles by endothelial cells and drug delivery by pores and tunnels. J Control Release 2022; 347:460-475. [PMID: 35545132 DOI: 10.1016/j.jconrel.2022.05.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 04/09/2022] [Accepted: 05/03/2022] [Indexed: 12/15/2022]
Abstract
Ultrasound insonification of microbubbles can locally enhance drug delivery by increasing the cell membrane permeability. To aid development of a safe and effective therapeutic microbubble, more insight into the microbubble-cell interaction is needed. In this in vitro study we aimed to investigate the initial 3D morphology of the endothelial cell membrane adjacent to individual microbubbles (n = 301), determine whether this morphology was affected upon binding and by the type of ligand on the microbubble, and study its influence on microbubble oscillation and the drug delivery outcome. High-resolution 3D confocal microscopy revealed that targeted microbubbles were internalized by endothelial cells, while this was not the case for non-targeted or IgG1-κ control microbubbles. The extent of internalization was ligand-dependent, since αvβ3-targeted microbubbles were significantly more internalized than CD31-targeted microbubbles. Ultra-high-speed imaging (~17 Mfps) in combination with high-resolution confocal microscopy (n = 246) showed that microbubble internalization resulted in a damped microbubble oscillation upon ultrasound insonification (2 MHz, 200 kPa peak negative pressure, 10 cycles). Despite damped oscillation, the cell's susceptibility to sonoporation (as indicated by PI uptake) was increased for internalized microbubbles. Monitoring cell membrane integrity (n = 230) showed the formation of either a pore, for intracellular delivery, or a tunnel (i.e. transcellular perforation), for transcellular delivery. Internalized microbubbles caused fewer transcellular perforations and smaller pore areas than non-internalized microbubbles. In conclusion, studying microbubble-mediated drug delivery using a state-of-the-art imaging system revealed receptor-mediated microbubble internalization and its effect on microbubble oscillation and resulting membrane perforation by pores and tunnels.
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Affiliation(s)
- Inés Beekers
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands; Department of Health, ORTEC B.V., Houtsingel 5, 2719 EA Zoetermeer, the Netherlands.
| | - Simone A G Langeveld
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Bram Meijlink
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Antonius F W van der Steen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Nico de Jong
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands; Laboratory of Medical Imaging, Department of Imaging Physics, Delft University of Technology, Building 22, Room D218, Lorentzweg 1, 2628 CJ Delft, the Netherlands
| | - Martin D Verweij
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands; Laboratory of Medical Imaging, Department of Imaging Physics, Delft University of Technology, Building 22, Room D218, Lorentzweg 1, 2628 CJ Delft, the Netherlands
| | - Klazina Kooiman
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands
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4
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Rong N, Zhang M, Wang Y, Wu H, Qi H, Fu X, Li D, Yang C, Wang Y, Fan Z. Effects of extracellular matrix rigidity on sonoporation facilitated by targeted microbubbles: Bubble attachment, bubble dynamics, and cell membrane permeabilization. ULTRASONICS SONOCHEMISTRY 2020; 67:105125. [PMID: 32298974 DOI: 10.1016/j.ultsonch.2020.105125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 02/19/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
In this study, we investigated the effects of extracellular matrix rigidity, an important physical property of microenvironments regulating cell morphology and functions, on sonoporation facilitated by targeted microbubbles, highlighting the role of microbubbles. We conducted mechanistic studies at the cellular level on physiologically relevant soft and rigid substrates. By developing a unique imaging strategy, we first resolved details of the 3D attachment configurations between targeted microbubbles and cell membrane. High-speed video microscopy then unveiled bubble dynamics driven by a single ultrasound pulse. Finally, we evaluated the cell membrane permeabilization using a small molecule model drug. Our results demonstrate that: (1) stronger targeted microbubble attachment was formed for cells cultured on the rigid substrate, while six different attachment configurations were revealed in total; (2) more violent bubble oscillation was observed for cells cultured on the rigid substrate, while one third of bubbles attached to cells on the soft substrate exhibited deformation shortly after ultrasound was turned off; (3) higher acoustic pressure was needed to permeabilize the cell membrane for cells on the soft substrate, while under the same ultrasound condition, acoustically-activated microbubbles generated larger pores as compared to cells cultured on the soft substrate. The current findings provide new insights to understand the underlying mechanisms of sonoporation in a physiologically relevant context and may be useful for the clinical translation of sonoporation.
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Affiliation(s)
- Ning Rong
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Meiru Zhang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Yulin Wang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Hao Wu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Hui Qi
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Xing Fu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Dachao Li
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Chunmei Yang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Yan Wang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Zhenzhen Fan
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China; State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
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5
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Comparison of Bubble Size Distributions Inferred from Acoustic, Optical Visualisation, and Laser Diffraction. COLLOIDS AND INTERFACES 2019. [DOI: 10.3390/colloids3040065] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Bubble measurement has been widely discussed in the literature and comparison studies have been widely performed to validate the results obtained for various forms of bubble size inferences. This paper explores three methods used to obtain a bubble size distribution—optical detection, laser diffraction and acoustic inferences—for a bubble cloud. Each of these methods has advantages and disadvantages due to their intrinsic inference methodology or design flaws due to lack of specificity in measurement. It is clearly demonstrated that seeing bubbles and hearing them are substantially and quantitatively different. The main hypothesis being tested is that for a bubble cloud, acoustic methods are able to detect smaller bubbles compared to the other techniques, as acoustic measurements depend on an intrinsic bubble property, whereas photonics and optical methods are unable to “see” a smaller bubble that is behind a larger bubble. Acoustic methods provide a real-time size distribution for a bubble cloud, whereas for other techniques, appropriate adjustments or compromises must be made in order to arrive at robust data. Acoustic bubble spectrometry consistently records smaller bubbles that were not detected by the other techniques. The difference is largest for acoustic methods and optical methods, with size differences ranging from 5–79% in average bubble size. Differences in size between laser diffraction and optical methods ranged from 5–68%. The differences between laser diffraction and acoustic methods are less, and range between 0% (i.e., in agreement) up to 49%. There is a wider difference observed between the optical method, laser diffraction and acoustic methods whilst good agreement between laser diffraction and acoustic methods. The significant disagreement between laser diffraction and acoustic method (35% and 49%) demonstrates the hypothesis, as there is a higher proportion of smaller bubbles in these measurements (i.e., the smaller bubbles ‘hide’ during measurement via laser diffraction). This study, which shows that acoustic bubble spectrometry is able to detect smaller bubbles than laser diffraction and optical techniques. This is supported by heat and mass transfer studies that show enhanced performance due to increased interfacial area of microbubbles, compared to fine bubbles.
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6
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Roovers S, Deprez J, Priwitaningrum D, Lajoinie G, Rivron N, Declercq H, De Wever O, Stride E, Le Gac S, Versluis M, Prakash J, De Smedt SC, Lentacker I. Sonoprinting liposomes on tumor spheroids by microbubbles and ultrasound. J Control Release 2019; 316:79-92. [PMID: 31676384 DOI: 10.1016/j.jconrel.2019.10.051] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/24/2019] [Accepted: 10/28/2019] [Indexed: 12/12/2022]
Abstract
Ultrasound-triggered drug-loaded microbubbles have great potential for drug delivery due to their ability to locally release drugs and simultaneously enhance their delivery into the target tissue. We have recently shown that upon applying ultrasound, nanoparticle-loaded microbubbles can deposit nanoparticles onto cells grown in 2D monolayers, through a process that we termed "sonoprinting". However, the rigid surfaces on which cell monolayers are typically growing might be a source of acoustic reflections and aspherical microbubble oscillations, which can influence microbubble-cell interactions. In the present study, we aim to reveal whether sonoprinting can also occur in more complex and physiologically relevant tissues, by using free-floating 3D tumor spheroids as a tissue model. We show that both monospheroids (consisting of tumor cells alone) and cospheroids (consisting of tumor cells and fibroblasts, which produce an extracellular matrix) can be sonoprinted. Using doxorubicin-liposome-loaded microbubbles, we show that sonoprinting allows to deposit large amounts of doxorubicin-containing liposomes to the outer cell layers of the spheroids, followed by doxorubicin release into the deeper layers of the spheroids, resulting in a significant reduction in cell viability. Sonoprinting may become an attractive approach to deposit drug patches at the surface of tissues, thereby promoting the delivery of drugs into target tissues.
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Affiliation(s)
- S Roovers
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Ghent University, Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - J Deprez
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Ghent University, Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - D Priwitaningrum
- Targeted Therapeutics, Department of Biomaterials Science and Technology, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
| | - G Lajoinie
- Physics of Fluids Group, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
| | - N Rivron
- Institute of Molecular Biotechnology, Austrian Academy of Sciences, Vienna, Austria
| | - H Declercq
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium; Tissue Engineering Group, Department of Human Structure and Repair, Ghent University, Belgium
| | - O De Wever
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium; Laboratory Experimental Cancer Research (LECR), Ghent University, Ghent, Belgium
| | - E Stride
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK
| | - S Le Gac
- Applied Microfluidics for BioEngineering Research, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
| | - M Versluis
- Physics of Fluids Group, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
| | - J Prakash
- Targeted Therapeutics, Department of Biomaterials Science and Technology, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center, University of Twente, Enschede, the Netherlands
| | - S 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.
| | - I Lentacker
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Ghent University, Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent, Belgium
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7
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Roovers S, Lajoinie G, De Cock I, Brans T, Dewitte H, Braeckmans K, Versluis M, De Smedt SC, Lentacker I. Sonoprinting of nanoparticle-loaded microbubbles: Unraveling the multi-timescale mechanism. Biomaterials 2019; 217:119250. [DOI: 10.1016/j.biomaterials.2019.119250] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 05/20/2019] [Accepted: 06/05/2019] [Indexed: 12/12/2022]
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8
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Roovers S, Segers T, Lajoinie G, Deprez J, Versluis M, De Smedt SC, Lentacker I. The Role of Ultrasound-Driven Microbubble Dynamics in Drug Delivery: From Microbubble Fundamentals to Clinical Translation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10173-10191. [PMID: 30653325 DOI: 10.1021/acs.langmuir.8b03779] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In the last couple of decades, ultrasound-driven microbubbles have proven excellent candidates for local drug delivery applications. Besides being useful drug carriers, microbubbles have demonstrated the ability to enhance cell and tissue permeability and, as a consequence, drug uptake herein. Notwithstanding the large amount of evidence for their therapeutic efficacy, open issues remain. Because of the vast number of ultrasound- and microbubble-related parameters that can be altered and the variability in different models, the translation from basic research to (pre)clinical studies has been hindered. This review aims at connecting the knowledge gained from fundamental microbubble studies to the therapeutic efficacy seen in in vitro and in vivo studies, with an emphasis on a better understanding of the response of a microbubble upon exposure to ultrasound and its interaction with cells and tissues. More specifically, we address the acoustic settings and microbubble-related parameters (i.e., bubble size and physicochemistry of the bubble shell) that play a key role in microbubble-cell interactions and in the associated therapeutic outcome. Additionally, new techniques that may provide additional control over the treatment, such as monodisperse microbubble formulations, tunable ultrasound scanners, and cavitation detection techniques, are discussed. An in-depth understanding of the aspects presented in this work could eventually lead the way to more efficient and tailored microbubble-assisted ultrasound therapy in the future.
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Affiliation(s)
- Silke Roovers
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , Ghent , Belgium
| | - Tim Segers
- Physics of Fluids Group, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Guillaume Lajoinie
- Physics of Fluids Group, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Joke Deprez
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , Ghent , Belgium
| | - Michel Versluis
- Physics of Fluids Group, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Stefaan C De Smedt
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , Ghent , Belgium
| | - Ine Lentacker
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , Ghent , Belgium
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Skachkov I, Luan Y, van Tiel ST, van der Steen AFW, de Jong N, Bernsen MR, Kooiman K. SPIO labeling of endothelial cells using ultrasound and targeted microbubbles at diagnostic pressures. PLoS One 2018; 13:e0204354. [PMID: 30235336 PMCID: PMC6147550 DOI: 10.1371/journal.pone.0204354] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 09/06/2018] [Indexed: 02/07/2023] Open
Abstract
In vivo cell tracking of therapeutic, tumor, and endothelial cells is an emerging field and a promising technique for imaging cardiovascular disease and cancer development. Site-specific labeling of endothelial cells with the MRI contrast agent superparamagnetic iron oxide (SPIO) in the absence of toxic agents is challenging. Therefore, the aim of this in vitro study was to find optimal parameters for efficient and safe SPIO-labeling of endothelial cells using ultrasound-activated CD31-targeted microbubbles for future MRI tracking. Ultrasound at a frequency of 1 MHz (10,000 cycles, repetition rate of 20 Hz) was used for varying applied peak negative pressures (10–160 kPa, i.e. low mechanical index (MI) of 0.01–0.16), treatment durations (0–30 s), time of SPIO addition (-5 min– 15 min with respect to the start of the ultrasound), and incubation time after SPIO addition (5 min– 3 h). Iron specific Prussian Blue staining in combination with calcein-AM based cell viability assays were applied to define the most efficient and safe conditions for SPIO-labeling. Optimal SPIO labeling was observed when the ultrasound parameters were 40 kPa peak negative pressure (MI 0.04), applied for 30 s just before SPIO addition (0 min). Compared to the control, this resulted in an approximate 12 times increase of SPIO uptake in endothelial cells in vitro with 85% cell viability. Therefore, ultrasound-activated targeted ultrasound contrast agents show great potential for effective and safe labeling of endothelial cells with SPIO.
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Affiliation(s)
- Ilya Skachkov
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
| | - Ying Luan
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
| | - Sandra T. van Tiel
- Department of Radiology & Nucleair Medicine, Erasmus MC, Rotterdam, the Netherlands
| | - Antonius F. W. van der Steen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
- Laboratory of Acoustical Wavefield Imaging, Faculty of Applied Sciences, Delft University of Technology, Delft, the Netherlands
| | - Nico de Jong
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
- Laboratory of Acoustical Wavefield Imaging, Faculty of Applied Sciences, Delft University of Technology, Delft, the Netherlands
| | - Monique R. Bernsen
- Department of Radiology & Nucleair Medicine, Erasmus MC, Rotterdam, the Netherlands
| | - Klazina Kooiman
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
- * E-mail:
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10
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Christensen-Jeffries K, Harput S, Brown J, Wells PNT, Aljabar P, Dunsby C, Tang MX, Eckersley RJ. Microbubble Axial Localization Errors in Ultrasound Super-Resolution Imaging. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2017; 64:1644-1654. [PMID: 28829309 DOI: 10.1109/tuffc.2017.2741067] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Acoustic super-resolution imaging has allowed the visualization of microvascular structure and flow beyond the diffraction limit using standard clinical ultrasound systems through the localization of many spatially isolated microbubble signals. The determination of each microbubble position is typically performed by calculating the centroid, finding a local maximum, or finding the peak of a 2-D Gaussian function fit to the signal. However, the backscattered signal from a microbubble depends not only on diffraction characteristics of the waveform, but also on the microbubble behavior in the acoustic field. Here, we propose a new axial localization method by identifying the onset of the backscattered signal. We compare the accuracy of localization methods using in vitro experiments performed at 7-cm depth and 2.3-MHz center frequency. We corroborate these findings with simulation results based on the Marmottant model. We show experimentally and in simulations that detecting the onset of the returning signal provides considerably increased accuracy for super-resolution. Resulting experimental cross-sectional profiles in super-resolution images demonstrate at least 5.8 times improvement in contrast ratio and more than 1.8 times reduction in spatial spread (provided by 90% of the localizations) for the onset method over centroiding, peak detection, and 2-D Gaussian fitting methods. Simulations estimate that these latter methods could create errors in relative bubble positions as high as at these experimental settings, while the onset method reduced the interquartile range of these errors by a factor of over 2.2. Detecting the signal onset is, therefore, expected to considerably improve the accuracy of super-resolution.
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11
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Kooiman K, van Rooij T, Qin B, Mastik F, Vos HJ, Versluis M, Klibanov AL, de Jong N, Villanueva FS, Chen X. Focal areas of increased lipid concentration on the coating of microbubbles during short tone-burst ultrasound insonification. PLoS One 2017; 12:e0180747. [PMID: 28686673 PMCID: PMC5501608 DOI: 10.1371/journal.pone.0180747] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 06/20/2017] [Indexed: 01/13/2023] Open
Abstract
Acoustic behavior of lipid-coated microbubbles has been widely studied, which has led to several numerical microbubble dynamics models that incorporate lipid coating behavior, such as buckling and rupture. In this study we investigated the relationship between microbubble acoustic and lipid coating behavior on a nanosecond scale by using fluorescently labeled lipids. It is hypothesized that a local increased concentration of lipids, appearing as a focal area of increased fluorescence intensity (hot spot) in the fluorescence image, is related to buckling and folding of the lipid layer thereby highly influencing the microbubble acoustic behavior. To test this hypothesis, the lipid microbubble coating was fluorescently labeled. The vibration of the microbubble (n = 177; 2.3–10.3 μm in diameter) upon insonification at an ultrasound frequency of 0.5 or 1 MHz at 25 or 50 kPa acoustic pressure was recorded with the UPMC Cam, an ultra-high-speed fluorescence camera, operated at ~4–5 million frames per second. During short tone-burst excitation, hot spots on the microbubble coating occurred at relative vibration amplitudes > 0.3 irrespective of frequency and acoustic pressure. Around resonance, the majority of the microbubbles formed hot spots. When the microbubble also deflated acoustically, hot spot formation was likely irreversible. Although compression-only behavior (defined as substantially more microbubble compression than expansion) and subharmonic responses were observed in those microbubbles that formed hot spots, both phenomena were also found in microbubbles that did not form hot spots during insonification. In conclusion, this study reveals hot spot formation of the lipid monolayer in the microbubble’s compression phase. However, our experimental results show that there is no direct relationship between hot spot formation of the lipid coating and microbubble acoustic behaviors such as compression-only and the generation of a subharmonic response. Hence, our hypothesis that hot spots are related to acoustic buckling could not be verified.
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Affiliation(s)
- Klazina Kooiman
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- Netherlands Heart Institute, Utrecht, the Netherlands
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
- * E-mail:
| | - Tom van Rooij
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
| | - Bin Qin
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Frits Mastik
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
| | - Hendrik J. Vos
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
- Laboratory of Acoustical Wavefield Imaging, Faculty of Applied Sciences, Delft University of Technology, Delft, the Netherlands
| | - Michel Versluis
- Physics of Fluids Group, MIRA Institute for Biomedical Technology and Technical Medicine and MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands
| | - Alexander L. Klibanov
- Cardiovascular Division, Department of Medicine, University of Virginia, Charlottesville, Virginia, United States of America
| | - Nico de Jong
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, the Netherlands
- Laboratory of Acoustical Wavefield Imaging, Faculty of Applied Sciences, Delft University of Technology, Delft, the Netherlands
| | - Flordeliza S. Villanueva
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
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12
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Raymond JL, Luan Y, Peng T, Huang SL, McPherson DD, Versluis M, de Jong N, Holland CK. Loss of gas from echogenic liposomes exposed to pulsed ultrasound. Phys Med Biol 2016; 61:8321-8339. [PMID: 27811382 DOI: 10.1088/0031-9155/61/23/8321] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The destruction of echogenic liposomes (ELIP) in response to pulsed ultrasound excitations has been studied acoustically previously. However, the mechanism underlying the loss of echogenicity due to cavitation nucleated by ELIP has not been fully clarified. In this study, an ultra-high speed imaging approach was employed to observe the destruction phenomena of single ELIP exposed to ultrasound bursts at a center frequency of 6 MHz. We observed a rapid size reduction during the ultrasound excitation in 139 out of 397 (35%) ultra- high-speed recordings. The shell dilation rate, which is defined as the microbubble wall velocity divided by the instantaneous radius, [Formula: see text] /R, was extracted from the radius versus time response of each ELIP, and was found to be correlated with the deflation. Fragmentation and surface mode vibrations were also observed and are shown to depend on the applied acoustic pressure and initial radius. Results from this study can be utilized to optimize the theranostic application of ELIP, e.g. by tuning the size distribution or the excitation frequency.
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Affiliation(s)
- Jason L Raymond
- Biomedical Engineering Program, University of Cincinnati, Cardiovascular Center 3940, 231 Albert Sabin Way, Cincinnati, OH 45267-0586, USA
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13
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Gourevich D, Volovick A, Dogadkin O, Wang L, Mulvana H, Medan Y, Melzer A, Cochran S. In Vitro Investigation of the Individual Contributions of Ultrasound-Induced Stable and Inertial Cavitation in Targeted Drug Delivery. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:1853-64. [PMID: 25887690 DOI: 10.1016/j.ultrasmedbio.2015.03.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 03/01/2015] [Accepted: 03/11/2015] [Indexed: 05/23/2023]
Abstract
Ultrasound-mediated targeted drug delivery is a therapeutic modality under development with the potential to treat cancer. Its ability to produce local hyperthermia and cell poration through cavitation non-invasively makes it a candidate to trigger drug delivery. Hyperthermia offers greater potential for control, particularly with magnetic resonance imaging temperature measurement. However, cavitation may offer reduced treatment times, with real-time measurement of ultrasonic spectra indicating drug dose and treatment success. Here, a clinical magnetic resonance imaging-guided focused ultrasound surgery system was used to study ultrasound-mediated targeted drug delivery in vitro. Drug uptake into breast cancer cells in the vicinity of ultrasound contrast agent was correlated with occurrence and quantity of stable and inertial cavitation, classified according to subharmonic spectra. During stable cavitation, intracellular drug uptake increased by a factor up to 3.2 compared with the control. Reported here are the value of cavitation monitoring with a clinical system and its subsequent employment for dose optimization.
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Affiliation(s)
- Dana Gourevich
- Institute for Medical Science and Technology, School of Medicine, University of Dundee, Dundee, United Kingdom; Capsutech Ltd., Nazareth, Israel
| | - Alexander Volovick
- Institute for Medical Science and Technology, School of Medicine, University of Dundee, Dundee, United Kingdom; InSightec Ltd., Haifa, Israel
| | - Osnat Dogadkin
- Institute for Medical Science and Technology, School of Medicine, University of Dundee, Dundee, United Kingdom; InSightec Ltd., Haifa, Israel
| | - Lijun Wang
- Institute for Medical Science and Technology, School of Medicine, University of Dundee, Dundee, United Kingdom
| | - Helen Mulvana
- School of Engineering, University of Glasgow, Glasgow, United Kingdom
| | - Yoav Medan
- Department of Biomedical Engineering, Technion, Haifa, Israel
| | - Andreas Melzer
- Institute for Medical Science and Technology, School of Medicine, University of Dundee, Dundee, United Kingdom
| | - Sandy Cochran
- Institute for Medical Science and Technology, School of Medicine, University of Dundee, Dundee, United Kingdom.
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14
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Maksimov AO, Burov BA, Salomatin AS, Chernykh DV. Sounds of marine seeps: a study of bubble activity near a rigid boundary. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2014; 136:1065. [PMID: 25190382 DOI: 10.1121/1.4892753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A passive acoustic method for detecting environmentally dangerous gas leaks from pipelines and methane naturally leaking from the seabed has been investigated. Gas escape involves the formation and release of bubbles of different sizes. Each bubble emits a sound at a specific frequency. Determination of the bubble radius from the frequency of its signature passive acoustic emission by use of so-called Minnaert formula has a restricted area of applicability near the seabed. The point is that the inertial mass and the damping constant of the birthing bubble are markedly different from those of a free bubble. The theoretical model for the bubble volume oscillations near the seabed has been proposed and an analytical solution has been derived. It was shown that the bispherical coordinates provide separation of variables and are more suitable for analysis of the volume oscillations of these constrained bubbles. Explicit formulas have been derived, which describe the dependence of the bubble emission near a rigid wall on its size and the separation distance between the bubble and the boundary.
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Affiliation(s)
- A O Maksimov
- Pacific Oceanological Institute, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok 690041, Russia
| | - B A Burov
- Pacific Oceanological Institute, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok 690041, Russia
| | - A S Salomatin
- Pacific Oceanological Institute, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok 690041, Russia
| | - D V Chernykh
- Pacific Oceanological Institute, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok 690041, Russia
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15
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Luan Y, Lajoinie G, Gelderblom E, Skachkov I, van der Steen AFW, Vos HJ, Versluis M, De Jong N. Lipid shedding from single oscillating microbubbles. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:1834-46. [PMID: 24798388 DOI: 10.1016/j.ultrasmedbio.2014.02.031] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 02/11/2014] [Accepted: 02/25/2014] [Indexed: 05/23/2023]
Abstract
Lipid-coated microbubbles are used clinically as contrast agents for ultrasound imaging and are being developed for a variety of therapeutic applications. The lipid encapsulation and shedding of the lipids by acoustic driving of the microbubble has a crucial role in microbubble stability and in ultrasound-triggered drug delivery; however, little is known about the dynamics of lipid shedding under ultrasound excitation. Here we describe a study that optically characterized the lipid shedding behavior of individual microbubbles on a time scale of nanoseconds to microseconds. A single ultrasound burst of 20 to 1000 cycles, with a frequency of 1 MHz and an acoustic pressure varying from 50 to 425 kPa, was applied. In the first step, high-speed fluorescence imaging was performed at 150,000 frames per second to capture the instantaneous dynamics of lipid shedding. Lipid detachment was observed within the first few cycles of ultrasound. Subsequently, the detached lipids were transported by the surrounding flow field, either parallel to the focal plane (in-plane shedding) or in a trajectory perpendicular to the focal plane (out-of-plane shedding). In the second step, the onset of lipid shedding was studied as a function of the acoustic driving parameters, for example, pressure, number of cycles, bubble size and oscillation amplitude. The latter was recorded with an ultrafast framing camera running at 10 million frames per second. A threshold for lipid shedding under ultrasound excitation was found for a relative bubble oscillation amplitude >30%. Lipid shedding was found to be reproducible, indicating that the shedding event can be controlled.
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Affiliation(s)
- Ying Luan
- Biomedical Engineering Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands.
| | - Guillaume Lajoinie
- Physics of Fluids Group and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Erik Gelderblom
- Physics of Fluids Group and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Ilya Skachkov
- Biomedical Engineering Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Antonius F W van der Steen
- Biomedical Engineering Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands; Acoustical Wavefield Imaging, Delft University of Technology, Delft, The Netherlands
| | - Hendrik J Vos
- Biomedical Engineering Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands; Acoustical Wavefield Imaging, Delft University of Technology, Delft, The Netherlands
| | - Michel Versluis
- Physics of Fluids Group and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Nico De Jong
- Biomedical Engineering Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands; Acoustical Wavefield Imaging, Delft University of Technology, Delft, The Netherlands
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16
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Kooiman K, Vos HJ, Versluis M, de Jong N. Acoustic behavior of microbubbles and implications for drug delivery. Adv Drug Deliv Rev 2014; 72:28-48. [PMID: 24667643 DOI: 10.1016/j.addr.2014.03.003] [Citation(s) in RCA: 238] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 02/11/2014] [Accepted: 03/18/2014] [Indexed: 12/21/2022]
Abstract
Ultrasound contrast agents are valuable in diagnostic ultrasound imaging, and they increasingly show potential for drug delivery. This review focuses on the acoustic behavior of flexible-coated microbubbles and rigid-coated microcapsules and their contribution to enhanced drug delivery. Phenomena relevant to drug delivery, such as non-spherical oscillations, shear stress, microstreaming, and jetting will be reviewed from both a theoretical and experimental perspective. Further, the two systems for drug delivery, co-administration and the microbubble as drug carrier system, are reviewed in relation to the microbubble behavior. Finally, future prospects are discussed that need to be addressed for ultrasound contrast agents to move from a pre-clinical tool into a clinical setting.
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17
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Papadopoulou V, Tang MX, Balestra C, Eckersley RJ, Karapantsios TD. Circulatory bubble dynamics: from physical to biological aspects. Adv Colloid Interface Sci 2014; 206:239-49. [PMID: 24534474 DOI: 10.1016/j.cis.2014.01.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 01/21/2014] [Accepted: 01/22/2014] [Indexed: 12/21/2022]
Abstract
Bubbles can form in the body during or after decompression from pressure exposures such as those undergone by scuba divers, astronauts, caisson and tunnel workers. Bubble growth and detachment physics then becomes significant in predicting and controlling the probability of these bubbles causing mechanical problems by blocking vessels, displacing tissues, or inducing an inflammatory cascade if they persist for too long in the body before being dissolved. By contrast to decompression induced bubbles whose site of initial formation and exact composition are debated, there are other instances of bubbles in the bloodstream which are well-defined. Gas emboli unwillingly introduced during surgical procedures and ultrasound microbubbles injected for use as contrast or drug delivery agents are therefore also discussed. After presenting the different ways that bubbles can end up in the human bloodstream, the general mathematical formalism related to the physics of bubble growth and detachment from decompression is reviewed. Bubble behavior in the bloodstream is then discussed, including bubble dissolution in blood, bubble rheology and biological interactions for the different cases of bubble and blood composition considered.
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Affiliation(s)
- Virginie Papadopoulou
- Department of Bioengineering, Imperial College London, London, UK; Environmental & Occupational Physiology Lab., Haute Ecole Paul Henri Spaak, Brussels, Belgium.
| | - Meng-Xing Tang
- Department of Bioengineering, Imperial College London, London, UK
| | - Costantino Balestra
- Environmental & Occupational Physiology Lab., Haute Ecole Paul Henri Spaak, Brussels, Belgium; DAN Europe Research Division, Belgium
| | - Robert J Eckersley
- Biomedical Engineering Department, Division of Imaging Sciences, King's College London, London, UK
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18
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Paul S, Nahire R, Mallik S, Sarkar K. Encapsulated microbubbles and echogenic liposomes for contrast ultrasound imaging and targeted drug delivery. COMPUTATIONAL MECHANICS 2014; 53:413-435. [PMID: 26097272 PMCID: PMC4470369 DOI: 10.1007/s00466-013-0962-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Micron- to nanometer-sized ultrasound agents, like encapsulated microbubbles and echogenic liposomes, are being developed for diagnostic imaging and ultrasound mediated drug/gene delivery. This review provides an overview of the current state of the art of the mathematical models of the acoustic behavior of ultrasound contrast microbubbles. We also present a review of the in vitro experimental characterization of the acoustic properties of microbubble based contrast agents undertaken in our laboratory. The hierarchical two-pronged approach of modeling contrast agents we developed is demonstrated for a lipid coated (Sonazoid™) and a polymer shelled (poly D-L-lactic acid) contrast microbubbles. The acoustic and drug release properties of the newly developed echogenic liposomes are discussed for their use as simultaneous imaging and drug/gene delivery agents. Although echogenicity is conclusively demonstrated in experiments, its physical mechanisms remain uncertain. Addressing questions raised here will accelerate further development and eventual clinical approval of these novel technologies.
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Affiliation(s)
- Shirshendu Paul
- Department of Mechanical Engineering, University of Delaware, Newark DE 19716, USA
| | - Rahul Nahire
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo ND 58108, USA
| | - Sanku Mallik
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo ND 58108, USA
| | - Kausik Sarkar
- Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052, USA
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19
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Shpak O, Kokhuis TJA, Luan Y, Lohse D, de Jong N, Fowlkes B, Fabiilli M, Versluis M. Ultrafast dynamics of the acoustic vaporization of phase-change microdroplets. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2013; 134:1610-21. [PMID: 23927201 DOI: 10.1121/1.4812882] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Acoustically sensitive emulsions are a promising tool for medical applications such as localized drug delivery. The physical mechanisms underlying the ultrasound-triggered nucleation and subsequent vaporization of these phase-change emulsions are largely unexplored. Here, the acoustic vaporization of individual micron-sized perfluoropentane (PFP) droplets is studied at a nanoseconds timescale. Highly diluted emulsions of PFP-in-water and oil-in-PFP-in-water droplets, ranging from 3.5 to 11 μm in radius, were prepared and the nucleation and growth of the vapor bubbles was imaged at frame rates of up to 20 Mfps. The droplet vaporization dynamics was observed to have three distinct regimes: (1) prior to nucleation, a regime of droplet deformation and oscillatory translations within the surrounding fluid along the propagation direction of the applied ultrasound; (2) a regime characterized by the rapid growth of a vapor bubble enhanced by ultrasound-driven rectified heat transfer; and (3) a final phase characterized by a relatively slow expansion, after ultrasound stops, that is fully dominated by heat transfer. A method to measure the moment of inception of the nucleation event with respect to the phase of the ultrasound wave is proposed. A simple physical model captures quantitatively all of the features of the subsequent vapor bubble growth.
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Affiliation(s)
- Oleksandr Shpak
- Physics of Fluids Group and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
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20
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Carroll JM, Lauderbaugh LK, Calvisi ML. Application of nonlinear sliding mode control to ultrasound contrast agent microbubbles. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2013; 134:216-222. [PMID: 23862799 DOI: 10.1121/1.4803902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A sliding mode control system is developed and applied to a spherical model of a contrast agent microbubble that simulates its radial response to ultrasound. The model uses a compressible form of the Rayleigh-Plesset equation combined with a thin-shell model. A nonlinear control law for the second-order model is derived and used to design and simulate the controller. The effect of the controller on the contrast agent response is investigated for various control scenarios. This work demonstrates the feasibility of using a nonlinear control system to modulate the dynamic response of ultrasound contrast agents, but highlights the need for improved feedback mechanisms and control input methods. Possible applications of the nonlinear control system to contrast agents illustrated in this work include radius stabilization in the presence of an acoustic wave, radial growth and subsequent collapse, and generation of periodic radial oscillations while a contrast agent is within an acoustic forcing regime known to cause a chaotic response.
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Affiliation(s)
- James M Carroll
- Department of Mechanical and Aerospace Engineering, University of Colorado, Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, Colorado 80918, USA
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21
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Carroll JM, Calvisi ML, Lauderbaugh LK. Dynamical analysis of the nonlinear response of ultrasound contrast agent microbubbles. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2013; 133:2641-2649. [PMID: 23654372 DOI: 10.1121/1.4796128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The nonlinear response of spherical ultrasound contrast agent microbubbles is investigated to understand the effects of common shells on the dynamics. A compressible form of the Rayleigh-Plesset equation is combined with a thin-shell model developed by Lars Hoff to simulate the radial response of contrast agents subject to ultrasound. The responses of Albunex, Sonazoid, and polymer shells are analyzed through the application of techniques from dynamical systems theory such as Poincaré sections, phase portraits, and bifurcation diagrams to illustrate the qualitative dynamics and transition to chaos that occurs under certain changes in system parameters. Corresponding calculations of Lyapunov exponents provide quantitative data on the system dynamics. The results indicate that Albunex and polymer shells sufficiently stabilize the response to prevent transition to the chaotic regime throughout typical clinical ranges of ultrasound pressure and frequency. By contrast, Sonazoid shells delay the onset of chaos relative to an unshelled bubble but do not prevent it. A contour plot identifying regions of periodic and chaotic behavior over clinical ranges of ultrasound pressure and frequency is provided for Sonazoid. This work characterizes the nonlinear response of various ultrasound contrast agents, and shows that shell properties have a profound influence on the dynamics.
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Affiliation(s)
- James M Carroll
- Department of Mechanical and Aerospace Engineering, University of Colorado, Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, Colorado 80918, USA
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22
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Casey J, Sennoga C, Mulvana H, Hajnal JV, Tang MX, Eckersley RJ. Single bubble acoustic characterization and stability measurement of adherent microbubbles. ULTRASOUND IN MEDICINE & BIOLOGY 2013; 39:903-914. [PMID: 23473537 DOI: 10.1016/j.ultrasmedbio.2012.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 12/10/2012] [Accepted: 12/11/2012] [Indexed: 06/01/2023]
Abstract
This article examines how the acoustic and stability characteristics of single lipid-shelled microbubbles (MBs) change as a result of adherence to a target surface. For individual adherent and non-adherent MBs, the backscattered echo from a narrowband 2-MHz, 90-kPa peak negative pressure interrogation pulse was obtained. These measurements were made in conjunction with an increasing amplitude broadband disruption pulse. It was found that, for the given driving frequency, adherence had little effect on the fundamental response of an MB. Examination of the second harmonic response indicated an increase of the resonance frequency for an adherent MB: resonance radius increasing of 0.3 ± 0.1 μm for an adherent MB. MB stability was seen to be closely related to MB resonance and gave further evidence of a change in the resonance frequency due to adherence.
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Affiliation(s)
- Jonathan Casey
- Imaging Sciences Department, Imperial College, London, UK
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23
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Thomas DH, Butler M, Pelekasis N, Anderson T, Stride E, Sboros V. The acoustic signature of decaying resonant phospholipid microbubbles. Phys Med Biol 2013; 58:589-99. [DOI: 10.1088/0031-9155/58/3/589] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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24
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Faez T, Emmer M, Kooiman K, Versluis M, van der Steen A, de Jong N. 20 years of ultrasound contrast agent modeling. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2013; 60:7-20. [PMID: 23287909 DOI: 10.1109/tuffc.2013.2533] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The merits of ultrasound contrast agents (UCAs) were already known in the 1960s. It was, however, not until the 1990s that UCAs were clinically approved and marketed. In these years, it was realized that the UCAs are not just efficient ultrasound scatterers, but that their main constituent, the coated gas microbubble, acts as a nonlinear resonator and, as such, is capable of generating harmonic energy. Subharmonic, ultraharmonic, and higher harmonic frequencies of the transmitted ultrasound frequency have been reported. This opened up new prospects for their use and several detection strategies have been developed to exploit this harmonic energy to discriminate the contrast bubbles from surrounding tissue. This insight created a need for tools to study coated bubble behavior in an ultrasound field and the first models were developed. Since then, 20 years have elapsed, in which a broad range of UCAs and UCA models have been developed. Although the models have helped in understanding the responses of coated bubbles, the influence of the coating has not been fully elucidated to date and UCA models are still being improved. The aim of this review paper is to offer an overview in these developments and indicate future directions for research.
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Affiliation(s)
- Telli Faez
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands.
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25
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Loughran J, Sennoga C, J Eckersley R, Tang MX. Effect of ultrasound on adherent microbubble contrast agents. Phys Med Biol 2012; 57:6999-7014. [PMID: 23044731 DOI: 10.1088/0031-9155/57/21/6999] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
An investigation into the effect of clinical ultrasound exposure on adherent microbubbles is described. A flow phantom was constructed in which targeted microbubbles were attached using biotin-streptavidin linkages. Microbubbles were insonated by broadband imaging pulses (centred at 2.25 MHz) over a range of pressures (peak negative pressure (PNP) = 60-375 kPa). Individual adherent bubbles were observed optically and classified as either being isolated or with a single neighbouring bubble. It is found that bubble detachment and deflation are two significant effects, even during low amplitude ultrasound exposure. Specifically, while at very low acoustic pressure (PNP < 75 kPa) 95% of the bubbles were not affected, at medium pressure (151 kPa < P < 225 kPa) 53% of the bubbles detached and at higher pressures (301 kPa < P < 375 kPa) 96% of the bubbles detached. In addition, more than 50% of the bubbles underwent deflation at pressures between 301 and 375 kPa. At pressures between 226 and 300 kPa, more adherent bubbles detached when there was a neighbouring bubble, suggesting the role of multiple scattering and secondary Bjerknes force on bubble detachment. The flow shear, primary and secondary Bjerknes forces exerted on each bubble were calculated and compared to the estimated forces acting on the bubble due to oscillations. The oscillation force is shown to be much higher than other forces. The mechanisms of bubble detachment are discussed.
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Affiliation(s)
- Jonathan Loughran
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
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26
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Xi X, Cegla F, Mettin R, Holsteyns F, Lippert A. Collective bubble dynamics near a surface in a weak acoustic standing wave field. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2012; 132:37-47. [PMID: 22779453 DOI: 10.1121/1.4726009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The transport of bubbles to a neighboring surface is very important in surface chemistry, bioengineering, and ultrasonic cleaning, etc. This paper proposes a multi-bubble transport method by using an acoustic standing wave field and establishes a model that explains the multi-bubble translation by expressing the balance between Bjerknes forces and hydrodynamic forces on a bubble in a liquid medium. Results indicated that the influence of primary Bjerknes force, secondary Bjerknes force, and buoyancy force on the bubble translation depends on the position of the target bubble in the acoustic field. Moreover, it was found that increasing the size of a bubble or pressure amplitude can accelerate the bubble motion and enhance the bubble-bubble interaction. The secondary Bjerknes force between two bubbles can switch from an attractive one when they oscillate in phase to a repulsive one when the bubble oscillations are out of phase. These findings provide an insight into the multi-bubble translation near a surface and can be applied to future bubble motion control studies, especially in drug delivery, sonoporation, and ultrasonic cleaning.
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Affiliation(s)
- Xiaoyu Xi
- Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, United Kingdom
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27
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Hay TA, Ilinskii YA, Zabolotskaya EA, Hamilton MF. Model for bubble pulsation in liquid between parallel viscoelastic layers. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2012; 132:124-37. [PMID: 22779461 PMCID: PMC3407159 DOI: 10.1121/1.4707489] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 02/03/2012] [Accepted: 04/02/2012] [Indexed: 05/20/2023]
Abstract
A model is presented for a pulsating spherical bubble positioned at a fixed location in a viscous, compressible liquid between parallel viscoelastic layers of finite thickness. The Green's function for particle displacement is found and utilized to derive an expression for the radiation load imposed on the bubble by the layers. Although the radiation load is derived for linear harmonic motion it may be incorporated into an equation for the nonlinear radial dynamics of the bubble. This expression is valid if the strain magnitudes in the viscoelastic layer remain small. Dependence of bubble pulsation on the viscoelastic and geometric parameters of the layers is demonstrated through numerical simulations.
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Affiliation(s)
- Todd A Hay
- Applied Research Laboratories, The University of Texas at Austin, Austin, Texas 78713-8029, USA.
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28
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Suslov SA, Ooi A, Manasseh R. Nonlinear dynamic behavior of microscopic bubbles near a rigid wall. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:066309. [PMID: 23005208 DOI: 10.1103/physreve.85.066309] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Indexed: 05/05/2023]
Abstract
The nonlinear dynamic behavior of microscopic bubbles near a rigid wall is investigated. Oscillations are driven by the ultrasonic pressure field that arises in various biomedical applications such as ultrasound imaging or targeted drug delivery. It is known that, when bubbles approach a blood-vessel wall, their linear dynamic response is modified. This modification may be very useful for real-time detection of bubbles that have found targets; in future therapeutic technologies, it may be useful for controlled release of medical agents encapsulating microbubbles. In this paper, the nonlinear response of microbubbles near a wall is studied. The Keller-Miksis-Parlitz equation is adopted, but modified to account for the presence of a rigid wall. This base model describes the time evolution of the bubble surface, which is assumed to remain spherical, and accounts for the effect of acoustic radiation losses owing to liquid compressibility in the momentum conservation. Two situations are considered: the base case of an isolated bubble in an unbounded medium, and a bubble near a rigid wall. In the latter case, the wall influence is modeled by including a symmetrically oscillating image bubble. The bubble dynamics is traced using a numerical solution of the model equation. Subsequently, Floquet theory is used to accurately detect the bifurcation point where bubble oscillations stop following the driving ultrasound frequency and undergo period-changing bifurcations. Of particular interest is the detection of the subcritical period-tripling and -quadrupling transition. The parametric bifurcation maps are obtained as functions of nondimensional parameters representing the bubble radius, the frequency and pressure amplitude of the driving ultrasound field, and the distance from the wall. It is shown that the presence of the wall generally stabilises the bubble dynamics, so that much larger values of the pressure amplitude are needed to generate nonlinear responses. Thus, a clinical protocol in which selected nonlinear harmonics are examined under varying insonation amplitudes may be useful in detecting microbubble proximity to walls.
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Affiliation(s)
- Sergey A Suslov
- Mathematics, H38, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
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Mulvana H, Eckersley RJ, Tang MX, Pankhurst Q, Stride E. Theoretical and experimental characterisation of magnetic microbubbles. ULTRASOUND IN MEDICINE & BIOLOGY 2012; 38:864-875. [PMID: 22480944 DOI: 10.1016/j.ultrasmedbio.2012.01.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 01/26/2012] [Accepted: 01/27/2012] [Indexed: 05/31/2023]
Abstract
In addition to improving image contrast, microbubbles have shown great potential in molecular imaging and drug/gene delivery. Previous work by the authors showed that considerable improvements in gene transfection efficiency were obtained using microbubbles loaded with magnetic nanoparticles under simultaneous exposure to ultrasound and magnetic fields. The aim of this study was to characterise the effect of nanoparticles on the dynamic and acoustic response of the microbubbles. High-speed video microscopy indicated that the amplitude of oscillation was very similar for magnetic and nonmagnetic microbubbles of the same size for the same ultrasound exposure (0.5 MHz, 100 kPa, 12-cycle pulse) and that this was minimally affected by an imposed magnetic field. The linear scattering to attenuation ratio (STAR) was also similar for suspensions of both bubble types although the nonlinear STAR was ~50% lower for the magnetic microbubbles. Both the video and acoustic data were supported by the results from theoretical modelling.
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Affiliation(s)
- Helen Mulvana
- Department of Imaging Sciences, Imperial College London, London, United Kingdom
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Sijl J, Vos HJ, Rozendal T, de Jong N, Lohse D, Versluis M. Combined optical and acoustical detection of single microbubble dynamics. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 130:3271-81. [PMID: 22087999 DOI: 10.1121/1.3626155] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
A detailed understanding of the response of single microbubbles subjected to ultrasound is fundamental to a full understanding of the contrast-enhancing abilities of microbubbles in medical ultrasound imaging, in targeted molecular imaging with ultrasound, and in ultrasound-mediated drug delivery with microbubbles. Here, single microbubbles are isolated and their ultrasound-induced radial dynamics recorded with an ultra-high-speed camera at up to 25 million frames per second. The sound emission is recorded simultaneously with a calibrated single element transducer. It is shown that the sound emission can be predicted directly from the optically recorded radial dynamics, and vice versa, that the nanometer-scale radial dynamics can be predicted from the acoustic response recorded in the far field.
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Affiliation(s)
- Jeroen Sijl
- Physics of Fluids Group and MIRA Institute of Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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Martynov S, Kostson E, Saffari N, Stride E. Forced vibrations of a bubble in a liquid-filled elastic vessel. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 130:2700-2708. [PMID: 22087898 DOI: 10.1121/1.3646904] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
There is increasing demand for accurate characterization of the in vivo behavior of microbubble agents used for ultrasound imaging and therapy. This study examines bubble-vessel interaction, in particular the propagation of disturbances along the vessel wall. Finite element simulations of a 3 μm radius microbubble suspended in a viscous liquid and enclosed in a 4 μm radius elastic vessel were performed, and the results compared with existing analytical results for wave propagation in elastic liquid-filled tubes. The vessel wall was shown to have a significant effect upon the amplitude of bubble oscillation and hence acoustic radiation from it, as well as distension of the vessel wall. It was found that the most important factor was the ratio of the excitation frequency to the natural "ring" frequency of the vessel which in turn depends upon its dimensions and mechanical properties. As this ratio increases, the motion of the vessel wall becomes increasingly localized to the site of the bubble. It was also shown that the validity of the results obtained using the applied model of vessel elasticity is limited to frequencies below the ring frequency, and this should be taken into account in the development of protocols for ultrasound safety and/or therapeutic procedures.
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Affiliation(s)
- Sergey Martynov
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom.
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Vos HJ, Dollet B, Versluis M, de Jong N. Nonspherical shape oscillations of coated microbubbles in contact with a wall. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:935-48. [PMID: 21601137 DOI: 10.1016/j.ultrasmedbio.2011.02.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 02/18/2011] [Accepted: 02/21/2011] [Indexed: 05/24/2023]
Abstract
In this experimental study, the nonspherical and translational behavior of individual coated microbubbles of different sizes, in contact with a 20-μm thickness cellulose wall, are observed and categorized systematically. Images from two orthogonally positioned microscopes are merged and then recorded with an ultra-fast framing camera. Large nonspherical deformations were found with 2.25 MHz frequency ultrasound pulses having driving pressures from 80 to 325 kPa. A parametric model combining potential flow theory with a viscous boundary layer at the wall is developed and used to calculate stresses from the optically recorded microbubble oscillations. Peak shear stress of up to 300 kPa and normal stresses of up to 1 MPa are estimated when microbubbles are insonifed with a 2.25 MHz pulse at 325 kPa. The clinical relevance of these results is discussed.
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Affiliation(s)
- Hendrik J Vos
- Biomedical Engineering, Thoraxcentrum, Erasmus MC, Rotterdam, The Netherlands
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Sprague MR, Chérin E, Foster FS. A new transducer receive transfer function calibration method: application to microbubble backscattering cross-section measurements at high frequency. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2011; 58:1159-1168. [PMID: 21693398 DOI: 10.1109/tuffc.2011.1926] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
When comparing acoustic scattering experiments with theory, the relationship between the pressure generated by a scatterer at the surface of a transducer and the induced voltage must be known. Methods have been previously proposed to measure the receive transfer function that rely on several assumptions. A new, experimental method for measuring the acoustic response of a spherically-focused transducer, using a hydrophone at twice the focal distance, is proposed that requires a minimum number of assumptions and calculations. The receive transfer function of a spherically-focused, high-frequency transducer was calculated, and found to be within 10% of the receive transfer function calculated assuming reciprocity. Further, using the receive transfer function, the effective backscattering cross-section of bound microbubbles interrogated at 30 MHz was measured to be, on average, 65% of the geometric backscattering cross-section, with significant size-independent variability. These results give insight into selecting the optimal microbubble size distribution for linear microbubble imaging at high frequencies.
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Affiliation(s)
- Michael R Sprague
- University of Toronto, Department of Medical Biophysics, Toronto, Ontario, Canada
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Sonoporation of endothelial cells by vibrating targeted microbubbles. J Control Release 2011; 154:35-41. [PMID: 21514333 DOI: 10.1016/j.jconrel.2011.04.008] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 04/01/2011] [Accepted: 04/06/2011] [Indexed: 12/20/2022]
Abstract
Molecular imaging using ultrasound makes use of targeted microbubbles. In this study we investigated whether these microbubbles could also be used to induce sonoporation in endothelial cells. Lipid-coated microbubbles were targeted to CD31 and insonified at 1 MHz at low peak negative acoustic pressures at six sequences of 10 cycle sine-wave bursts. Vibration of the targeted microbubbles was recorded with the Brandaris-128 high-speed camera (~13 million frames per second). In total, 31 cells were studied that all had one microbubble (1.2-4.2 micron in diameter) attached per cell. After insonification at 80 kPa, 30% of the cells (n=6) had taken up propidium iodide, while this was 20% (n=1) at 120 kPa and 83% (n=5) at 200 kPa. Irrespective of the peak negative acoustic pressure, uptake of propidium iodide was observed when the relative vibration amplitude of targeted microbubbles was greater than 0.5. No relationship was found between the position of the microbubble on the cell and induction of sonoporation. This study shows that targeted microbubbles can also be used to induce sonoporation, thus making it possible to combine molecular imaging and drug delivery.
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Prabowo F, Ohl CD. Surface oscillation and jetting from surface attached acoustic driven bubbles. ULTRASONICS SONOCHEMISTRY 2011; 18:431-435. [PMID: 20727814 DOI: 10.1016/j.ultsonch.2010.07.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Revised: 07/10/2010] [Accepted: 07/21/2010] [Indexed: 05/29/2023]
Abstract
We report on an experimental study of the onset of surface oscillation and jetting of bubbles attached to a rigid surface. The driving frequency is 16.27 kHz and the radius of the spherical capped bubble is 160 ± 5 μm. The acoustic amplitude is increased from 0 to 0.085 bar while the oscillation is recorded with a high-speed camera at 180,000 frames/s over 8100 periods of oscillations. The radial and surface modes are analyzed from a Fourier decomposition. With increasing pressure amplitude we find three regimes: pure radial oscillation, development of surface oscillations, and a chaotic surface oscillation regime. These regimes appear abrupt and are repeatable. In the chaotic regime, fast liquid jetting towards the rigid surface is observed.
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Affiliation(s)
- Firdaus Prabowo
- Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
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Sprague MR, Chérin E, Goertz DE, Foster FS. Nonlinear emission from individual bound microbubbles at high frequencies. ULTRASOUND IN MEDICINE & BIOLOGY 2010; 36:313-24. [PMID: 20018429 DOI: 10.1016/j.ultrasmedbio.2009.08.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 07/25/2009] [Accepted: 08/17/2009] [Indexed: 05/21/2023]
Abstract
Targeted microbubbles detected with high-frequency ultrasound can establish the molecular expression of blood vessels with submillimeter resolution. To improve microbubble-specific imaging at high frequencies, the subharmonic and second harmonic signal from individual microbubbles were measured as a function of size and pressure. Single phospholipid-shell microbubbles (1.1 to 5.0 microm in diameter) bound to gelatin, co-aligned with an optical microscope and transducer, were insonated with 30 MHz Gaussian-enveloped pulses at pressures from 20 kPa to 1 MPa with -6 dB one-way bandwidths of 11%, 20% and 45%. A subharmonic signal (15 MHz) was detected above a pressure threshold of 110 kPa--independent of bandwidth. The signal peaked for microbubbles 1.60 microm in diameter subject to 20% and 11% bandwidth pulses, and 1.80 microm for 45% bandwidth pulses, for pressures up to 400 kPa, agreeing with the notion that microbubbles insonated at twice their resonant frequency preferentially emit a subharmonic component. For pressures between 400 kPa and 1 MPa, a broader range of microbubbles emitted a subharmonic signal, and microbubbles below 1.70 mum in diameter were disrupted. The second harmonic signal measured, within the limited experimental conditions, was consistent with nonlinear propagation. Further, the results shed light on the effect of the shell on the phase of the subharmonic signal with respect to the fundamental signal.
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Affiliation(s)
- Michael R Sprague
- Department of Medical Biophysics, Sunnybrook Research Institute, University of Toronto, Ontario, Canada
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Guidi F, Vos HJ, Mori R, de Jong N, Tortoli P. Microbubble characterization through acoustically induced deflation. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2010; 57:193-202. [PMID: 20040446 DOI: 10.1109/tuffc.2010.1398] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Ultrasound contrast agents (UCA) populations are typically polydisperse and contain microbubbles with radii over a given range. Although the behavior of microbubbles of certain sizes might be masked by the behavior of others, the acoustic characterization of UCA is typically made on full populations. In this paper, we have combined acoustic and optical methods to investigate the response of isolated lipid-shelled microbubbles to low-pressure (49 and 62 kPa peak negative pressure) ultrasound tone bursts. These bursts induced slow deflation of the microbubbles. The experimental setup included a microscope connected to a fast camera acquiring one frame per pulse transmitted by a single-element transducer. The behavior of each bubble was measured at multiple frequencies, by cyclically changing the transmission frequency over the range of 2 to 4 MHz during subsequent pulse repetition intervals. The bubble echoes were captured by a second transducer and coherently recorded. More than 50 individual microbubbles were observed. Microbubbles with radii larger than 3 mum did not experience any size reduction. Smaller bubbles slowly deflated, generally until the radius reached a value around 1.4 microm, independent of the initial microbubble size. The detected pressure amplitude backscattered at 2.5 cm distance was very low, decreasing from about 5 Pa down to 1 Pa at 2 MHz as the bubbles deflated. The resonant radius was evaluated from the echo amplitude normalized with respect to the geometrical cross section. At 2-MHz excitation, deflating microbubbles showed highest normalized echo when the radius was 2.2 microm while at higher excitation frequencies, the resonant radius was lower. The relative phase shift of the echo during the deflation process was also measured. It was found to exceed pi/2 in all cases. A heuristic procedure based on the analysis of multiple bubbles of a same population was used to estimate the undamped natural frequency. It was found that a microbubble of 1.7 microm has an undamped natural frequency of 2 MHz. The difference between this size and the resonant radius is discussed as indicative of significant damping.
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Affiliation(s)
- Francesco Guidi
- Department of Electronics and Telecommunications, Universita degli Studi di Firenze, Florence, Italy.
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de Jong N, Emmer M, van Wamel A, Versluis M. Ultrasonic characterization of ultrasound contrast agents. Med Biol Eng Comput 2009; 47:861-73. [PMID: 19468770 PMCID: PMC2727586 DOI: 10.1007/s11517-009-0497-1] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Accepted: 04/16/2009] [Indexed: 11/30/2022]
Abstract
The main constituent of an ultrasound contrast agent (UCA) is gas-filled microbubbles. An average UCA contains billions per ml. These microbubbles are excellent ultrasound scatterers due to their high compressibility. In an ultrasound field they act as resonant systems, resulting in harmonic energy in the backscattered ultrasound signal, such as energy at the subharmonic, ultraharmonic and higher harmonic frequencies. This harmonic energy is exploited for contrast enhanced imaging to discriminate the contrast agent from surrounding tissue. The amount of harmonic energy that the contrast agent bubbles generate depends on the bubble characteristics in combination with the ultrasound field applied. This paper summarizes different strategies to characterize the UCAs. These strategies can be divided into acoustic and optical methods, which focus on the linear or nonlinear responses of the contrast agent bubbles. In addition, the characteristics of individual bubbles can be determined or the bubbles can be examined when they are part of a population. Recently, especially optical methods have proven their value to study individual bubbles. This paper concludes by showing some examples of optically observed typical behavior of contrast bubbles in ultrasound fields.
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Affiliation(s)
- Nico de Jong
- Biomedical Engineering (Thoraxcenter), Erasmus University Medical Center, Rotterdam, The Netherlands.
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Ultrasound triggered image-guided drug delivery. Eur J Radiol 2009; 70:242-53. [PMID: 19272727 DOI: 10.1016/j.ejrad.2009.01.051] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 01/14/2009] [Indexed: 12/27/2022]
Abstract
The integration of therapeutic interventions with diagnostic imaging has been recognized as one of the next technological developments that will have a major impact on medical treatments. Important advances in this field are based on a combination of progress in guiding and monitoring ultrasound energy, novel drug classes becoming available, the development of smart delivery vehicles, and more in depth understanding of the mechanisms of the cellular and molecular basis of diseases. Recent research demonstrates that both pressure sensitive and temperature sensitive delivery systems hold promise for local treatment. The use of ultrasound for the delivery of drugs has been demonstrated in particular the field of cardiology and oncology for a variety of therapeutics ranging from small drug molecules to biologics and nucleic acids.
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Sijl J, Gaud E, Frinking PJA, Arditi M, de Jong N, Lohse D, Versluis M. Acoustic characterization of single ultrasound contrast agent microbubbles. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2008; 124:4091-7. [PMID: 19206831 DOI: 10.1121/1.2997437] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Individual ultrasound contrast agent microbubbles (BR14) were characterized acoustically. The bubbles were excited at a frequency of 2 MHz and at peak-negative pressure amplitudes of 60 and 100 kPa. By measuring the transmit and receive transfer functions of both the transmit and receive transducers, echoes of individual bubbles were recorded quantitatively and compared to simulated data. At 100 kPa driving pressure, a second harmonic response was observed for bubbles with a size close to their resonance size. Power spectra were derived from the echo waveforms of bubbles of different sizes. These spectra were in good agreement with those calculated from a Rayleigh-Plesset-type model, incorporating the viscoelastic properties of the phospholipid shell. Small bubbles excited below their resonance frequency have a response dominated by the characteristics of their phospholipid shell, whereas larger bubbles, excited above resonance, have a response identical to those of uncoated bubbles of similar size.
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Affiliation(s)
- Jeroen Sijl
- Physics of Fluids Group, University of Twente, Enschede, The Netherlands.
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Dollet B, van der Meer SM, Garbin V, de Jong N, Lohse D, Versluis M. Nonspherical oscillations of ultrasound contrast agent microbubbles. ULTRASOUND IN MEDICINE & BIOLOGY 2008; 34:1465-73. [PMID: 18450362 DOI: 10.1016/j.ultrasmedbio.2008.01.020] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 01/30/2008] [Accepted: 01/31/2008] [Indexed: 05/13/2023]
Abstract
The occurrence of nonspherical oscillations (or surface modes) of coated microbubbles, used as ultrasound contrast agents in medical imaging, is investigated using ultra-high-speed optical imaging. Optical tweezers designed to micromanipulate single bubbles in 3-D are used to trap the bubbles far from any boundary, enabling a controlled study of the nonspherical oscillations of free-floating bubbles. Nonspherical oscillations appear as a parametric instability and display subharmonic behavior: they oscillate at half the forcing frequency, which was fixed at 1.7 MHz in this study. Surface modes are shown to preferentially develop for a bubble radius near the resonance of radial oscillations. In the studied range of acoustic pressures, the growth of surface modes saturates at a level far below bubble breakage. With the definition of a single, dimensionless deformation parameter, the amplitude of nonspherical deformation is quantified as a function of the bubble radius (between 1.5 and 5 microm) and of the acoustic pressure (up to 200 kPa).
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Affiliation(s)
- Benjamin Dollet
- Physics of Fluids Group, Department of Science and Technology, University of Twente, Enschede, The Netherlands.
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