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Shakya G, Cattaneo M, Guerriero G, Prasanna A, Fiorini S, Supponen O. Ultrasound-responsive microbubbles and nanodroplets: A pathway to targeted drug delivery. Adv Drug Deliv Rev 2024; 206:115178. [PMID: 38199257 DOI: 10.1016/j.addr.2023.115178] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/21/2023] [Accepted: 12/31/2023] [Indexed: 01/12/2024]
Abstract
Ultrasound-responsive agents have shown great potential as targeted drug delivery agents, effectively augmenting cell permeability and facilitating drug absorption. This review focuses on two specific agents, microbubbles and nanodroplets, and provides a sequential overview of their drug delivery process. Particular emphasis is given to the mechanical response of the agents under ultrasound, and the subsequent physical and biological effects on the cells. Finally, the state-of-the-art in their pre-clinical and clinical implementation are discussed. Throughout the review, major challenges that need to be overcome in order to accelerate their clinical translation are highlighted.
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Affiliation(s)
- Gazendra Shakya
- Institute of Fluid Dynamics, D-MAVT, Sonneggstrasse 3, ETH Zurich, Zurich, 8092, Switzerland
| | - Marco Cattaneo
- Institute of Fluid Dynamics, D-MAVT, Sonneggstrasse 3, ETH Zurich, Zurich, 8092, Switzerland
| | - Giulia Guerriero
- Institute of Fluid Dynamics, D-MAVT, Sonneggstrasse 3, ETH Zurich, Zurich, 8092, Switzerland
| | - Anunay Prasanna
- Institute of Fluid Dynamics, D-MAVT, Sonneggstrasse 3, ETH Zurich, Zurich, 8092, Switzerland
| | - Samuele Fiorini
- Institute of Fluid Dynamics, D-MAVT, Sonneggstrasse 3, ETH Zurich, Zurich, 8092, Switzerland
| | - Outi Supponen
- Institute of Fluid Dynamics, D-MAVT, Sonneggstrasse 3, ETH Zurich, Zurich, 8092, Switzerland.
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Mondou P, Mériaux S, Nageotte F, Vappou J, Novell A, Larrat B. State of the art on microbubble cavitation monitoring and feedback control for blood-brain-barrier opening using focused ultrasound. Phys Med Biol 2023; 68:18TR03. [PMID: 37369229 DOI: 10.1088/1361-6560/ace23e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 06/27/2023] [Indexed: 06/29/2023]
Abstract
Focused ultrasound (FUS) is a non-invasive and highly promising method for targeted and reversible blood-brain barrier permeabilization. Numerous preclinical studies aim to optimize the localized delivery of drugs using this method in rodents and non-human primates. Several clinical trials have been initiated to treat various brain diseases in humans using simultaneous BBB permeabilization and drug injection. This review presents the state of the art ofin vitroandin vivocavitation control algorithms for BBB permeabilization using microbubbles (MB) and FUS. Firstly, we describe the different cavitation states, their physical significance in terms of MB behavior and their translation into the spectral composition of the backscattered signal. Next, we report the different indexes calculated and used during the ultrasonic monitoring of cavitation. Finally, the differentin vitroandin vivocavitation control strategies described in the literature are presented and compared.
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Affiliation(s)
- Paul Mondou
- Université de Strasbourg, CNRS, ICube, UMR7357, Strasbourg, France
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France
| | - Sébastien Mériaux
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France
| | - Florent Nageotte
- Université de Strasbourg, CNRS, ICube, UMR7357, Strasbourg, France
| | - Jonathan Vappou
- Université de Strasbourg, CNRS, ICube, UMR7357, Strasbourg, France
| | - Anthony Novell
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, SHFJ, 91401 , Orsay, France
| | - Benoit Larrat
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France
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Liu WW, Ko HC, Li PC. Sonoporation based on repeated vaporization of gold nanodroplets. Med Phys 2022; 49:2761-2773. [PMID: 35172015 PMCID: PMC9450513 DOI: 10.1002/mp.15544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 01/24/2022] [Accepted: 02/09/2022] [Indexed: 11/09/2022] Open
Abstract
Background Gold nanodroplets (AuNDs) have been proposed as agents for photothermal therapy and photoacoustic imaging. Previously, we demonstrated that the sonoporation can be more effectively achieved with synchronized optical and acoustic droplet vaporization. By applying a laser pulse at the rarefactional phase of the ultrasound (US) pulse, the vaporization threshold can be reached at a considerably lower laser average power. However, a large loading quantity of the AuNDs may increase the risk of air embolism. The destruction of phase‐shifted AuNDs at the inertial cavitation stage leads to a reduced drug delivery performance. And it also causes instability of echogenicity during therapeutic monitoring. Purpose In this study, we propose to further improve the sonoporation effectiveness with repeated vaporization. In other words, the AuNDs repeatedly undergo vaporization and recondensation so that sonoporation effects are accumulated over time at lower energy requirements. Previously, repeated vaporization has been demonstrated as an imaging contrast agent. In this study, we aim to adopt this repeated vaporization scheme for sonoporation. Methods Perfluoropentane NDs with a shell made of human serum albumin were used as the US contrast agents. Laser pulses at 808 nm and US pulses of 1 MHz were delivered for triggering vaporization and inertial cavitation of NDs. We detected the vaporization and cavitation effects under different activation firings, US peak negative pressures (PNPs), and laser fluences using 5‐ and 10‐MHz focused US receivers. Numbers of calcein‐AM and propidium iodide signals uptake by BNL hepatocarcinoma cancer cells were used to evaluate the sonoporation and cell death rate of the cells. Results We demonstrate that sonoporation can be realized based on repeatable vaporization instead of the commonly adopted inertial cavitation effects. In addition, it is found that the laser fluence and the acoustic pressure can be reduced. As an example, we demonstrate that the acoustic and optical energy for achieving a similar level of sonoporation rate can be as low as 0.44 MPa for the US PNP and 4.01 mJ/cm2 for the laser fluence, which are lower than those with our previous approach (0.53 MPa and 4.95 mJ/cm2, respectively). Conclusion We demonstrated the feasibility of vaporization‐based sonoporation at a lower optical and acoustic energy. It is an advantageous method that can enhance drug delivery efficiency, therapeutic safety and potentially deliver an upgraded gene therapy strategy for improved theragnosis.
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Affiliation(s)
- Wei-Wen Liu
- Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, 106, Taiwan
| | - Hung-Chih Ko
- Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, 106, Taiwan
| | - Pai-Chi Li
- Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, 106, Taiwan.,Department of Electrical Engineering, National Taiwan University, Taipei, 106, Taiwan
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Lu X, Jin H, Quesada C, Farrell EC, Huang L, Aliabouzar M, Kripfgans OD, Fowlkes JB, Franceschi RT, Putnam AJ, Fabiilli ML. Spatially-directed cell migration in acoustically-responsive scaffolds through the controlled delivery of basic fibroblast growth factor. Acta Biomater 2020; 113:217-227. [PMID: 32553916 DOI: 10.1016/j.actbio.2020.06.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/22/2020] [Accepted: 06/09/2020] [Indexed: 12/24/2022]
Abstract
Hydrogels are commonly used in regenerative medicine for the delivery of growth factors (GFs). The spatial and temporal presentations of GFs are critical for directing regenerative processes, yet conventional hydrogels do not enable such control. We have developed a composite hydrogel, termed an acoustically-responsive scaffold (ARS), where release of a GF is non-invasively and spatiotemporally-controlled using focused ultrasound. The ARS consists of a fibrin matrix doped with a GF-loaded, phase-shift emulsion. The GF is released when the ARS is exposed to suprathreshold ultrasound via a mechanism termed acoustic droplet vaporization. In this study, we investigate how different spatial patterns of suprathreshold ultrasound can impact the biological response upon in vivo implantation of an ARS containing basic fibroblast growth factor (bFGF). ARSs were fabricated with either perfluorohexane (bFGF-C6-ARS) or perflurooctane (bFGF-C8-ARS) within the phase-shift emulsion. Ultrasound generated stable bubbles in bFGF-C6-ARS, which inhibited matrix compaction, whereas transiently stable bubbles were generated in bFGF-C8-ARS, which decreased in height by 44% within one day of implantation. The rate of bFGF release and distance of host cell migration were up to 6.8-fold and 8.1-fold greater, respectively, in bFGF-C8-ARS versus bFGF-C6-ARS. Ultrasound increased the formation of macropores within the fibrin matrix of bFGF-C8-ARS by 2.7-fold. These results demonstrate that spatially patterning suprathreshold ultrasound within bFGF-C8-ARS can be used to elicit a spatially-directed response from the host. Overall, these findings can be used in developing strategies to spatially pattern regenerative processes. STATEMENT OF SIGNIFICANCE: Hydrogels are commonly used in regenerative medicine for the delivery of growth factors (GFs). The spatial and temporal presentations of GFs are critical for directing regenerative processes, yet conventional hydrogels do not enable such control. We have developed a composite hydrogel, termed an acoustically-responsive scaffold (ARS), where GF release is non-invasively and spatiotemporally-controlled using focused ultrasound. The ARS consists of a fibrin matrix doped with a phase-shift emulsion loaded with GF, which is released when the ARS is exposed to ultrasound. In this in vivo study, we demonstrate that spatially patterning ultrasound within an ARS containing basic fibroblast growth factor (bFGF) can elicit a spatially-directed response from the host. Overall, these findings can be used in developing strategies to spatially pattern regenerative processes.
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Affiliation(s)
- Xiaofang Lu
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | - Hai Jin
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; School of Medicine, Second Affiliated Hospital of South China University of Technology, Guangzhou, China
| | - Carole Quesada
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | - Easton C Farrell
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | - Leidan Huang
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Department of Ultrasound, Second Affiliated Hospital of Army Medical University, Chongqing, China
| | - Mitra Aliabouzar
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | - Oliver D Kripfgans
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - J Brian Fowlkes
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Renny T Franceschi
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA; Dental School, University of Michigan, Ann Arbor, MI, USA
| | - Andrew J Putnam
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Mario L Fabiilli
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.
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Aliabouzar M, Jivani A, Lu X, Kripfgans OD, Fowlkes JB, Fabiilli ML. Standing wave-assisted acoustic droplet vaporization for single and dual payload release in acoustically-responsive scaffolds. ULTRASONICS SONOCHEMISTRY 2020; 66:105109. [PMID: 32248042 PMCID: PMC7217719 DOI: 10.1016/j.ultsonch.2020.105109] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 03/20/2020] [Accepted: 03/25/2020] [Indexed: 05/04/2023]
Abstract
An ultrasound standing wave field (SWF) has been utilized in many biomedical applications. Here, we demonstrate how a SWF can enhance drug release using acoustic droplet vaporization (ADV) in an acoustically-responsive scaffold (ARS). ARSs are composite fibrin hydrogels containing payload-carrying, monodispersed perfluorocarbon (PFC) emulsions and have been used to stimulate regenerative processes such as angiogenesis. Elevated amplitudes in the SWF significantly enhanced payload release from ARSs containing dextran-loaded emulsions (nominal diameter: 6 μm) compared to the -SWF condition, both at sub- and suprathreshold excitation pressures. At 2.5 MHz and 4 MPa peak rarefactional pressure, the cumulative percentage of payload released from ARSs reached 84.1 ± 5.4% and 66.1 ± 4.4% under + SWF and -SWF conditions, respectively, on day 10. A strategy for generating a SWF for an in situ ARS is also presented. For dual-payload release studies, bi-layer ARSs containing a different payload within each layer were exposed to temporally staggered ADV at 3.25 MHz (day 0) and 8.6 MHz (day 4). Sequential payload release was demonstrated using dextran payloads as well as two growth factors relevant to angiogenesis: basic fibroblast growth factor (bFGF) and platelet-derived growth factor BB (PDGF-BB). In addition, bubble growth and fibrin degradation were characterized in the ARSs under +SWF and -SWF conditions. These results highlight the utility of a SWF for modulating single and dual payload release from an ARS and can be used in future therapeutic studies.
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Affiliation(s)
- Mitra Aliabouzar
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | - Aniket Jivani
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Depatment of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Xiaofang Lu
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | - Oliver D Kripfgans
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - J Brian Fowlkes
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Mario L Fabiilli
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.
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Aliabouzar M, Lu X, Kripfgans OD, Fowlkes JB, Fabiilli ML. Acoustic Droplet Vaporization in Acoustically Responsive Scaffolds: Effects of Frequency of Excitation, Volume Fraction and Threshold Determination Method. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:3246-3260. [PMID: 31561948 PMCID: PMC6823163 DOI: 10.1016/j.ultrasmedbio.2019.08.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 08/11/2019] [Accepted: 08/23/2019] [Indexed: 05/03/2023]
Abstract
Ultrasound-induced vaporization of liquid perfluorocarbon (PFC) droplets into microbubbles, termed acoustic droplet vaporization (ADV), has potential therapeutic and diagnostic applications. Recently, we demonstrated how ADV-a threshold-based phenomenon-can modulate the release of biomolecules from composite hydrogels, thereby stimulating regenerative processes, such as angiogenesis. These composite hydrogels, called acoustically responsive scaffolds (ARSs), consist of monodispersed, micron size PFC emulsions embedded within a fibrin matrix. This study investigated the effects of frequency of excitation (2.25, 5, 7.5 and 10 MHz) and volume fraction (0.05%, 0.2% and 1% [v/v]) of monodispersed, double emulsions in the ARSs on the ADV threshold. We determined and compared the ADV thresholds via acoustic methods, including active detection, passive detection and attenuation, as well as an echogenicity-based method using B-mode imaging. The ADV threshold determined via these four techniques showed an increasing trend with frequency of excitation. Further analysis of the wave propagation showed that the amplitudes of high frequency harmonics were diminished in ARSs with high volume fractions of emulsion. The ADV threshold inversely correlated with the volume fraction of emulsion at the lowest excitation frequency. However, at higher frequencies, possibly due to the high acoustic reflectivity of the PFC emulsions, the ADV threshold correlated directly with the volume fraction of the emulsion. Additionally, the ADV efficiency correlated with the supra-threshold acoustic pressure. Overall, these results elucidate fundamental acoustic properties of the ARSs, which can be used in future applications.
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Affiliation(s)
- Mitra Aliabouzar
- Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Xiaofang Lu
- Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Oliver D Kripfgans
- Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA; Applied Physics Program, University of Michigan, Ann Arbor, Michigan, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - J Brian Fowlkes
- Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA; Applied Physics Program, University of Michigan, Ann Arbor, Michigan, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Mario L Fabiilli
- Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA; Applied Physics Program, University of Michigan, Ann Arbor, Michigan, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
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7
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Numerical Simulations of the Nonlinear Interaction of a Bubble Cloud and a High Intensity Focused Ultrasound Field. ACOUSTICS 2019. [DOI: 10.3390/acoustics1040049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We studied the effects of a small bubble cloud located at the pre-focal area of a high-intensity focused ultrasound field. Our objective is to show that bubbles can modify the bioeffects of an ultrasound treatment in muscle tissue. We model a three-dimensional ultrasound field in an idealized configuration of real operating conditions. Simulations are performed using a combined method based on the Khokhlov-Zabolotskaya-Kuznetsov equation, describing the ultrasound propagation, and a Rayleigh-Plesset equation, modeling the bubble oscillations. The nonlinear interaction of the ultrasound field and the bubble oscillations is considered. Results with and without bubbles for different void fractions of the cloud and different acoustic powers are compared. The cloud induces scattering, nonlinear distortion, and shielding of ultrasound, which increase the mechanical index in the pre-focal zone, shift the location, reduce the size, and modify the shape of the volume of tissue of high mechanical index values, and lower the pressure at the intended focus considerably. Although some hypothesis and parameters used in the models do not fit the real HIFU situations, the simulation results suggest that the effects caused by a bubble cloud located in the pre-focal area should be considered and monitored to ensure the safety of high-intensity focused ultrasound treatments.
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Lu X, Dong X, Natla S, Kripfgans OD, Fowlkes JB, Wang X, Franceschi R, Putnam AJ, Fabiilli ML. Parametric Study of Acoustic Droplet Vaporization Thresholds and Payload Release From Acoustically-Responsive Scaffolds. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:2471-2484. [PMID: 31235205 PMCID: PMC6689245 DOI: 10.1016/j.ultrasmedbio.2019.05.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 05/16/2019] [Accepted: 05/22/2019] [Indexed: 05/11/2023]
Abstract
Hydrogels are commonly used for the delivery of bioactive molecules, especially growth factors and cytokines capable of stimulating tissue regeneration. Regenerative processes are regulated by the concentrations and spatiotemporal presentations of these molecules. With conventional hydrogels, these critical delivery parameters cannot be actively modulated after implantation. We have developed composite hydrogel scaffolds where payload release is non-invasively modulated, in an on-demand manner, using ultrasound (US). These acoustically-responsive scaffolds (ARSs) consist of a fibrin matrix doped with a payload-carrying, perfluorocarbon (PFC) double emulsion. Previously, acoustic droplet vaporization (ADV) was used to trigger release of a pro-angiogenic growth factor, encapsulated in the ARS, which stimulated blood vessel formation in vivo. In the present study, we assess how characteristics of the monodispersed emulsion, fibrin matrix, and US impact ADV thresholds and the release efficiency of a dextran payload. ADV thresholds increased with the molecular weight of the PFC in the emulsion and inversely with the volume fraction of emulsion in the ARS. Payload release from ARSs with perfluoroheptane (C7) or perfluorooctane (C8) emulsions was dependent on the number of z-planes of US used to generate ADV and inversely dependent on the lateral spacing. Conversely, release from ARSs with perfluoropentane (C5) or perfluorohexane (C6) emulsions was less dependent on these US exposure parameters. After ADV, payload diffusion decreased significantly in ARSs with C5 or C6 emulsions compared with ARSs with C7 or C8 emulsions. The expansion of the ARS after ADV decreased with the molecular weight of the PFC. Non-selective release increased with the molecular weight of the PFC and thrombin concentration. Overall, these findings can be used for optimization of ARS properties and US parameters in future therapeutic applications.
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Affiliation(s)
- Xiaofang Lu
- Department of Radiology, University of Michigan Health System, Ann Arbor, USA
| | - Xiaoxiao Dong
- Department of Radiology, University of Michigan Health System, Ann Arbor, USA; Department of Ultrasound, Army Medical University, Chongqing, China
| | - Sam Natla
- Department of Radiology, University of Michigan Health System, Ann Arbor, USA
| | - Oliver D Kripfgans
- Department of Radiology, University of Michigan Health System, Ann Arbor, USA; Applied Physics Program, University of Michigan, Ann Arbor, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA
| | - J Brian Fowlkes
- Department of Radiology, University of Michigan Health System, Ann Arbor, USA; Applied Physics Program, University of Michigan, Ann Arbor, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA
| | - Xueding Wang
- Department of Radiology, University of Michigan Health System, Ann Arbor, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA
| | - Renny Franceschi
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA; Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, USA; Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, USA
| | - Andrew J Putnam
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA
| | - Mario L Fabiilli
- Department of Radiology, University of Michigan Health System, Ann Arbor, USA; Applied Physics Program, University of Michigan, Ann Arbor, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA.
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Desgranges S, Lorton O, Gui-Levy L, Guillemin P, Celicanin Z, Hyacinthe JN, Breguet R, Crowe LA, Becker CD, Soulié M, Taulier N, Contino-Pépin C, Salomir R. Micron-sized PFOB liquid core droplets stabilized with tailored-made perfluorinated surfactants as a new class of endovascular sono-sensitizers for focused ultrasound thermotherapy. J Mater Chem B 2019; 7:927-939. [DOI: 10.1039/c8tb01491d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The effect of micro-droplet concentration on HIFU beam absorption.
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10
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Xin Y, Zhang A, Xu LX, Fowlkes JB. The effects on thermal lesion shape and size from bubble clouds produced by acoustic droplet vaporization. Biomed Eng Online 2018; 17:163. [PMID: 30373677 PMCID: PMC6206628 DOI: 10.1186/s12938-018-0596-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Accepted: 10/25/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Bubbles formed by acoustic droplet vaporization (ADV) have proven to be an effective method for significant enlargement of the thermal lesions produced by high intensity focused ultrasound (HIFU). We investigated the influences of bubble cloud shape and droplet concentration on HIFU thermal lesions, as these relate to the ADV technique. METHODS Unlike previous studies where the droplets were simultaneously vaporized with the HIFU exposure for thermal lesion formation, droplets were vaporized by pulse wave (PW) ultrasound prior to continuous wave (CW) ultrasound heating in this experimental study. Under different experimental conditions, we recorded and quantified by the image processing methods the morphology and size of the bubble clouds created and the corresponding thermal lesions formed. RESULTS The results demonstrated that different ADV droplet concentrations produced a variety of thermal lesion shapes and sizes. The lesion volume could be increased using PW ultrasound followed by CW exposure, especially for higher droplet concentrations, e.g. 3.41 × 106/mL yielded a tenfold increase over that seen using CW alone. CONCLUSION These findings could lead to optimization of HIFU therapy by selecting a bubble forming strategy and droplet concentrations, especially using lower ultrasound powers which is desirable in clinical applications.
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Affiliation(s)
- Ying Xin
- School of Biomedical Engineering, 400 Med-X Research Institute, Shanghai Jiao Tong University, 1954 Huashan Rd, Shanghai, China
| | - Aili Zhang
- School of Biomedical Engineering, 400 Med-X Research Institute, Shanghai Jiao Tong University, 1954 Huashan Rd, Shanghai, China.
| | - Lisa X Xu
- School of Biomedical Engineering, 400 Med-X Research Institute, Shanghai Jiao Tong University, 1954 Huashan Rd, Shanghai, China
| | - J Brian Fowlkes
- Department of Radiology, University of Michigan Health System, 3226C Medical Sciences Building I, 1301 Catherine Street, Ann Arbor, MI, USA.
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11
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Chang N, Lu S, Qin D, Xu T, Han M, Wang S, Wan M. Efficient and controllable thermal ablation induced by short-pulsed HIFU sequence assisted with perfluorohexane nanodroplets. ULTRASONICS SONOCHEMISTRY 2018; 45:57-64. [PMID: 29705325 DOI: 10.1016/j.ultsonch.2018.02.033] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 02/05/2018] [Accepted: 02/19/2018] [Indexed: 06/08/2023]
Abstract
A HIFU sequence with extremely short pulse duration and high pulse repetition frequency can achieve thermal ablation at a low acoustic power using inertial cavitation. Because of its cavitation-dependent property, the therapeutic outcome is unreliable when the treatment zone lacks cavitation nuclei. To overcome this intrinsic limitation, we introduced perfluorocarbon nanodroplets as extra cavitation nuclei into short-pulsed HIFU-mediated thermal ablation. Two types of nanodroplets were used with perfluorohexane (PFH) as the core material coated with bovine serum albumin (BSA) or an anionic fluorosurfactant (FS) to demonstrate the feasibility of this study. The thermal ablation process was recorded by high-speed photography. The inertial cavitation activity during the ablation was revealed by sonoluminescence (SL). The high-speed photography results show that the thermal ablation volume increased by ∼643% and 596% with BSA-PFH and FS-PFH, respectively, than the short-pulsed HIFU alone at an acoustic power of 19.5 W. Using nanodroplets, much larger ablation volumes were created even at a much lower acoustic power. Meanwhile, the treatment time for ablating a desired volume significantly reduced in the presence of nanodroplets. Moreover, by adjusting the treatment time, lesion migration towards the HIFU transducer could also be avoided. The SL results show that the thermal lesion shape was significantly dependent on the inertial cavitation in this short-pulsed HIFU-mediated thermal ablation. The inertial cavitation activity became more predictable by using nanodroplets. Therefore, the introduction of PFH nanodroplets as extra cavitation nuclei made the short-pulsed HIFU thermal ablation more efficient by increasing the ablation volume and speed, and more controllable by reducing the acoustic power and preventing lesion migration.
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Affiliation(s)
- Nan Chang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Shukuan Lu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Dui Qin
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Tianqi Xu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Meng Han
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Supin Wang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China.
| | - Mingxi Wan
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China.
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12
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Chen Q, Yu J, Kim K. Review: optically-triggered phase-transition droplets for photoacoustic imaging. Biomed Eng Lett 2018; 8:223-229. [PMID: 30603205 DOI: 10.1007/s13534-018-0069-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 04/20/2018] [Accepted: 04/21/2018] [Indexed: 12/28/2022] Open
Abstract
Optically-triggered phase-transition droplets have been introduced as a promising contrast agent for photoacoustic and ultrasound imaging that not only provide significantly enhanced contrast but also have potential as photoacoustic theranostic molecular probes incorporated with targeting molecules and therapeutics. For further understanding the dynamics of optical droplet vaporization process, an innovative, methodical analysis by concurrent acoustical and ultrafast optical recordings, comparing with a theoretical model has been employed. In addition, the repeatability of the droplet vaporization-recondensation process, which enables continuous photoacoustic imaging has been studied through the same approach. Further understanding the underlying physics of the optical droplet vaporization and associated dynamics may guide the optimal design of the droplets. Some innovative approaches in preclinical studies have been recently demonstrated, including sono-photoacoustic imaging, dual-modality of photoacoustic and ultrasound imaging, and super-resolution photoacoustic imaging. In this review, current development of optically triggered phase-transition droplets and understanding on the vaporization dynamics, their applications are introduced and future directions are discussed.
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Affiliation(s)
- Qiyang Chen
- 1Department of Medicine and Heart and Vascular Institute, Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA 15261 USA.,2Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 USA
| | - Jaesok Yu
- 1Department of Medicine and Heart and Vascular Institute, Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA 15261 USA.,2Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 USA
| | - Kang Kim
- 1Department of Medicine and Heart and Vascular Institute, Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA 15261 USA.,2Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 USA.,McGowan Institute of Regenerative Medicine, University of Pittsburgh, UPMC, Pittsburgh, PA 15219 USA.,4Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261 USA
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13
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Chong WK, Papadopoulou V, Dayton PA. Imaging with ultrasound contrast agents: current status and future. Abdom Radiol (NY) 2018; 43:762-772. [PMID: 29508011 DOI: 10.1007/s00261-018-1516-1] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Microbubble ultrasound contrast agents (UCAs) were recently approved by the Food and Drug administration for non-cardiac imaging. The physical principles of UCAs, methods of administration, dosage, adverse effects, and imaging techniques both current and future are described. UCAs consist of microbubbles in suspension which strongly interact with the ultrasound beam and are readily detectable by ultrasound imaging systems. They are confined to the blood pool when administered intravenously, unlike iodinated and gadolinium contrast agents. UCAs have a proven safety record based on over two decades of use, during which they have been used in echocardiography in the U.S. and for non-cardiac imaging in the rest of the world. Adverse effects are less common with UCAs than CT/MR contrast agents. Compared to CT and MR, contrast-enhanced ultrasound has the advantages of real-time imaging, portability, and reduced susceptibility to metal and motion artifact. UCAs are not nephrotoxic and can be used in renal failure. High acoustic amplitudes can cause microbubbles to fragment in a manner that can result in short-term increases in capillary permeability or capillary rupture. These bioeffects can be beneficial and have been used to enhance drug delivery under appropriate conditions. Imaging with a mechanical index of < 0.4 preserves the microbubbles and is not typically associated with substantial bioeffects. Molecularly targeted ultrasound contrast agents are created by conjugating the microbubble shell with a peptide, antibody, or other ligand designed to target an endothelial biomarker associated with tumor angiogenesis or inflammation. These microbubbles then accumulate in the microvasculature at target sites where they can be imaged. Ultrasound contrast agents are a valuable addition to the diagnostic imaging toolkit. They will facilitate cross-sectional abdominal imaging in situations where contrast-enhanced CT and MR are contraindicated or impractical.
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Affiliation(s)
- Wui K Chong
- Department of Diagnostic Radiology, University of Texas MD Anderson Cancer Center, Unit 1473 | FCT15.5092, 1400 Pressler Street, Houston, TX, 77030, USA.
| | - Virginie Papadopoulou
- UNC-NC State Joint Department of Biomedical Engineering, Chapel Hill, NC, 27599, USA
| | - Paul A Dayton
- UNC Biomedical Research Imaging Center, Chapel Hill, NC, 27599, USA
- UNC-NC State Joint Department of Biomedical Engineering, Chapel Hill, NC, 27599, USA
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14
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Xin Y, Zhang A, Xu LX, Brian Fowlkes J. Numerical Study of Bubble Area Evolution During Acoustic Droplet Vaporization-Enhanced HIFU Treatment. J Biomech Eng 2018; 139:2635775. [PMID: 28654938 DOI: 10.1115/1.4037150] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Indexed: 01/05/2023]
Abstract
Acoustic droplet vaporization has the potential to shorten treatment time of high-intensity focused ultrasound (HIFU) while minimizing the possible effects of microbubbles along the propagation path. Distribution of the bubbles formed from the droplets during the treatment is the major factor shaping the therapeutic region. A numerical model was proposed to simulate the bubble area evolution during this treatment. Using a linear acoustic equation to describe the ultrasound field, a threshold range was defined that determines the amount of bubbles vaporized in the treated area. Acoustic parameters, such as sound speed, acoustic attenuation coefficient, and density, were treated as a function of the bubble size distribution and the gas void fraction, which were related to the vaporized bubbles in the medium. An effective pressure factor was proposed to account for the influence of the existing bubbles on the vaporization of the nearby droplets. The factor was obtained by fitting one experimental result and was then used to calculate bubble clouds in other experimental cases. Comparing the simulation results to these other experiments validated the model. The dynamic change of the pressure and the bubble distribution after exposure to over 20 pulses of HIFU are obtained. It is found that the bubble area grows from a grainlike shape to a "tadpole," with comparable dimensions and shape to those observed in experiments. The process was highly dynamic with the shape of the bubble area changing with successive HIFU pulses and the focal pressure. The model was further used to predict the shape of the bubble region triggered by HIFU when a bubble wall pre-exists. The results showed that the bubble wall helps prevent droplet vaporization on the distal side of the wall and forms a particularly shaped region with bubbles. This simulation model has predictive potential that could be beneficial in applications, such as cancer treatment, by parametrically studying conditions associated with these treatments and designing treatment protocols.
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Affiliation(s)
- Ying Xin
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030, China; 400 Med-X Research Institute, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, China e-mail:
| | - Aili Zhang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030, China; 400 Med-X Research Institute, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, China e-mail:
| | - Lisa X Xu
- Fellow ASME School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030, China; 400 Med-X Research Institute, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, China e-mail:
| | - J Brian Fowlkes
- Department of Radiology, University of Michigan Health System, 3226C Medical Sciences Building I, 1301 Catherine Street, Ann Arbor, MI 48109-5667 e-mail:
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15
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Ishijima A, Tanaka J, Azuma T, Minamihata K, Yamaguchi S, Kobayashi E, Nagamune T, Sakuma I. The lifetime evaluation of vapourised phase-change nano-droplets. ULTRASONICS 2016; 69:97-105. [PMID: 27082763 DOI: 10.1016/j.ultras.2016.04.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 04/01/2016] [Accepted: 04/03/2016] [Indexed: 05/20/2023]
Abstract
Phase-change nano-droplets (PCNDs) are sub-micron particles that are coated with phospholipid and contain liquid-state perfluorocarbons such as perfluoropentane (boiling point=29°C) and perfluorohexane (boiling point=57°C), which can vapourise upon application of ultrasound. The bubbles generated by such reactions can serve as ultrasound contrast agents or HIFU sensitisers. However, the lifetime of bubbles generated from PCNDs on μs-order is not well known. Knowledge of the condition of PCND-derived bubbles on μs-order is essential for producing bubbles customised for specific purposes. In this study, we use an optical measurement system to measure the vapourisation and stability of the bubbles (bubble-lifetime) as well as the stability-controlling method of the nucleated bubbles on μs-order while changing the internal composition of PCNDs and the ambient temperature. PCND-derived bubbles remain in a bubble state when the boiling point of the internal composition is lower than the ambient temperature, but lose their optical contrast after approximately 10μs by re-condensation or dissolution when the boiling point of the internal composition is higher than the ambient temperature. We reveal that the superheating condition significantly affects the fate of vapourised PCNDs and that the bubble-lifetime can be controlled by changing both the ambient temperature conditions and the internal composition of PCNDs.
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Affiliation(s)
- Ayumu Ishijima
- Department of Precision Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan
| | - Jun Tanaka
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan
| | - Takashi Azuma
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan.
| | - Kosuke Minamihata
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan
| | - Satoshi Yamaguchi
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo, Japan
| | - Etsuko Kobayashi
- Department of Precision Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan
| | - Teruyuki Nagamune
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan
| | - Ichiro Sakuma
- Department of Precision Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan
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Drug-Loaded Perfluorocarbon Nanodroplets for Ultrasound-Mediated Drug Delivery. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 880:221-41. [DOI: 10.1007/978-3-319-22536-4_13] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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17
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Kang ST, Lin YC, Yeh CK. Mechanical bioeffects of acoustic droplet vaporization in vessel-mimicking phantoms. ULTRASONICS SONOCHEMISTRY 2014; 21:1866-74. [PMID: 24690297 DOI: 10.1016/j.ultsonch.2014.03.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 03/10/2014] [Accepted: 03/10/2014] [Indexed: 05/13/2023]
Abstract
This study investigated the mechanical bioeffects exerted by acoustic droplet vaporization (ADV) under different experimental conditions using vessel phantoms with a 200-μm inner diameter but different stiffness for imitating the microvasculature in various tumors. High-speed microscopy, passive cavitation detection, and ultrasound attenuation measurement were conducted to determine the morphological characteristics of vascular damage and clarify the mechanisms by which the damage was initiated and developed. The results show that phantom erosion was initiated under successive ultrasound exposure (2 MHz, 3 cycles) at above 8-MPa peak negative pressures (PNPs) when ADV occurred with inertial cavitation (IC), producing lesions whose morphological characteristics were dependent on the amount of vaporized droplets. Slight injury occurred at droplet concentrations below (2.6±0.2)×10(6) droplets/mL, forming shallow and rugged surfaces on both sides of the vessel walls. Increasing the droplet concentration to up to (2.6±0.2)×10(7) droplets/mL gradually suppressed the damage on the distal wall, and turned the rugged surface on the proximal wall into tunnels rapidly elongating in the direction opposite to ultrasound propagation. Increasing the PNP did not increase the maximum tunnel depth after the ADV efficiency reached a plateau (about 71.6±2.7% at 10 MPa). Increasing the pulse duration effectively increased the maximum tunnel depth to more than 10 times the diameter of the vessel even though there was no marked enhancement in IC dose. It can be inferred that substantial bubble generation in single ADV events may simultaneously distort the acoustic pressure distribution. The backward ultrasound reinforcement and forward ultrasound shielding relative to the direction of wave propagation augment the propensity of backward erosion. The results of the present work provide information that is valuable for the prevention or utilization of ADV-mediated mechanical bioeffects in clinical applications.
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Affiliation(s)
- Shih-Tsung Kang
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan
| | - Yi-Chen Lin
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan
| | - Chih-Kuang Yeh
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
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18
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Qiao Y, Zong Y, Yin H, Chang N, Li Z, Wan M. Spatial and temporal observation of phase-shift nano-emulsions assisted cavitation and ablation during focused ultrasound exposure. ULTRASONICS SONOCHEMISTRY 2014; 21:1745-1751. [PMID: 24746925 DOI: 10.1016/j.ultsonch.2014.03.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Revised: 03/29/2014] [Accepted: 03/29/2014] [Indexed: 06/03/2023]
Abstract
BACKGROUND Phase-shift nano-emulsions (PSNEs) with a small initial diameter in nanoscale have the potential to leak out of the blood vessels and to accumulate at the target point of tissue. At desired location, PSNEs can undergo acoustic droplet vaporization (ADV) process, change into gas bubbles and enhance focused ultrasound efficiency. The threshold of droplet vaporization and influence of acoustic parameters have always been research hotspots in order to spatially control the potential of bioeffects and optimize experimental conditions. However, when the pressure is much higher than PSNEs' vaporization threshold, there were little reports on their cavitation and thermal effects. OBJECT In this study, PSNEs induced cavitation and ablation effects during pulsed high-intensity focused ultrasound (HIFU) exposure were investigated, including the spatial and temporal information and the influence of acoustic parameters. METHODS Two kinds of tissue-mimicking phantoms with uniform PSNEs were prepared because of their optical transparency. The Sonoluminescence (SL) method was employed to visualize the cavitation activities. And the ablation process was observed as the heat deposition could produce white lesion. RESULTS Precisely controlled HIFU cavitation and ablation can be realized at a relatively low input power. But when the input power was high, PSNEs can accelerate cavitation and ablation in pre-focal region. The cavitation happened layer by layer advancing the transducer. While the lesion appeared to be separated into two parts, one in pre-focal region stemmed from one point and grew quickly, the other in focal region grew much more slowly. The influence of duty cycle has also been examined. Longer pulse off time would cause heat transfer to the surrounding media, and generate smaller lesion. On the other hand, this would give outer layer bubbles enough time to dissolve, and inner bubbles can undergo violent collapse and emit bright light.
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Affiliation(s)
- Yangzi Qiao
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Yujin Zong
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Hui Yin
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Nan Chang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Zhaopeng Li
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Mingxi Wan
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China.
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19
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Kripfgans OD, Zhang M, Fabiilli ML, Carson PL, Padilla F, Swanson SD, Mougenot C, Fowlkes JB, Mougenot C. Acceleration of ultrasound thermal therapy by patterned acoustic droplet vaporization. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2014; 135:537-44. [PMID: 24437794 PMCID: PMC3985868 DOI: 10.1121/1.4828832] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 09/11/2013] [Accepted: 10/21/2013] [Indexed: 05/28/2023]
Abstract
One application of acoustic droplet vaporization (ADV), a method of converting biocompatible microdroplets into microbubbles, is to enhance locally high intensity focused ultrasound (HIFU) therapy. Two objectives are pursued here: (1) the controlled creation of a bubble trench prior to HIFU using ADV and (2) use of the trench for increasing ablation volumes, lowering acoustic powers, and decreasing therapy duration. Thermally responsive phantoms were made with perfluorocarbon emulsion. Compound lesions were formed in a laboratory setting and a clinical magnetic resonance imaging (MRI)-guided HIFU system. Linear and spiral patterned compound lesions were generated in trenches. A larger fraction of the HIFU beam is contained to increase the generation of heat. Using the laboratory system, a 90 mm linear length spiral trench was formed in 30 s with mechanical beam steering. Comparatively, the clinical HIFU system formed a 19.9 mm linear length spiral trench in approximately 1 s with electronic beam steering. Lesions were imaged optically and with MRI. A uniform thermal ablation volume of 3.25 mL was achieved in 55.4 s (4-times faster than standard clinical HIFU and 14-times larger volume versus sum of individual lesions). Single lesions showed a 400% volume increase.
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Affiliation(s)
- Oliver D Kripfgans
- Department of Radiology, University of Michigan Health System, 1301 Catherine Street, Med Sci 1, Room 3218D, Ann Arbor, Michigan 48109-5667
| | - Man Zhang
- Department of Radiology, University of Michigan Health System, 1301 Catherine Street, Med Sci 1, Room 3218D, Ann Arbor, Michigan 48109-5667
| | - Mario L Fabiilli
- Department of Radiology, University of Michigan Health System, 1301 Catherine Street, Med Sci 1, Room 3218D, Ann Arbor, Michigan 48109-5667
| | - Paul L Carson
- Department of Radiology, University of Michigan Health System, 1301 Catherine Street, Med Sci 1, Room 3218D, Ann Arbor, Michigan 48109-5667
| | - Frederic Padilla
- Department of Radiology, University of Michigan Health System, 1301 Catherine Street, Med Sci 1, Room 3218D, Ann Arbor, Michigan 48109-5667
| | - Scott D Swanson
- Department of Radiology, University of Michigan Health System, 1301 Catherine Street, Med Sci 1, Room 3218D, Ann Arbor, Michigan 48109-5667
| | - Charles Mougenot
- Department of Radiology, University of Michigan Health System, 1301 Catherine Street, Med Sci 1, Room 3218D, Ann Arbor, Michigan 48109-5667
| | - J Brian Fowlkes
- Department of Radiology, University of Michigan Health System, 1301 Catherine Street, Med Sci 1, Room 3218D, Ann Arbor, Michigan 48109-5667
| | - Charles Mougenot
- Philips Healthcare, 281 Hilmount Road, Markham, Ontario L6C 2S3, Canada
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20
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Sheeran PS, Dayton PA. Improving the performance of phase-change perfluorocarbon droplets for medical ultrasonography: current progress, challenges, and prospects. SCIENTIFICA 2014; 2014:579684. [PMID: 24991447 PMCID: PMC4058811 DOI: 10.1155/2014/579684] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 04/02/2014] [Indexed: 05/12/2023]
Abstract
Over the past two decades, perfluorocarbon (PFC) droplets have been investigated for biomedical applications across a wide range of imaging modalities. More recently, interest has increased in "phase-change" PFC droplets (or "phase-change" contrast agents), which can convert from liquid to gas with an external energy input. In the field of ultrasound, phase-change droplets present an attractive alternative to traditional microbubble agents for many diagnostic and therapeutic applications. Despite the progress, phase-change PFC droplets remain far from clinical implementation due to a number of challenges. In this review, we survey our recent work to enhance the performance of phase-change agents for ultrasound through a variety of techniques in order to provide increased efficacy in therapeutic applications of ultrasound and enable previously unexplored applications in diagnostic and molecular imaging.
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Affiliation(s)
- Paul S. Sheeran
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC 27599, USA
| | - Paul A. Dayton
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC 27599, USA
- *Paul A. Dayton:
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21
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Fabiilli ML, Wilson CG, Padilla F, Martín-Saavedra FM, Fowlkes JB, Franceschi RT. Acoustic droplet-hydrogel composites for spatial and temporal control of growth factor delivery and scaffold stiffness. Acta Biomater 2013; 9:7399-409. [PMID: 23535233 DOI: 10.1016/j.actbio.2013.03.027] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 01/29/2013] [Accepted: 03/13/2013] [Indexed: 10/27/2022]
Abstract
Wound healing is regulated by temporally and spatially restricted patterns of growth factor signaling, but there are few delivery vehicles capable of the "on-demand" release necessary for recapitulating these patterns. Recently we described a perfluorocarbon double emulsion that selectively releases a protein payload upon exposure to ultrasound through a process known as acoustic droplet vaporization (ADV). In this study, we describe a delivery system composed of fibrin hydrogels doped with growth factor-loaded double emulsion for applications in tissue regeneration. Release of immunoreactive basic fibroblast growth factor (bFGF) from the composites increased up to 5-fold following ADV and delayed release was achieved by delaying exposure to ultrasound. Releasates of ultrasound-treated materials significantly increased the proliferation of endothelial cells compared to sham controls, indicating that the released bFGF was bioactive. ADV also triggered changes in the ultrastructure and mechanical properties of the fibrin as bubble formation and consolidation of the fibrin in ultrasound-treated composites were accompanied by up to a 22-fold increase in shear stiffness. ADV did not reduce the viability of cells suspended in composite scaffolds. These results demonstrate that an acoustic droplet-hydrogel composite could have broad utility in promoting wound healing through on-demand control of growth factor release and/or scaffold architecture.
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22
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Sheeran PS, Matsunaga TO, Dayton PA. Phase-transition thresholds and vaporization phenomena for ultrasound phase-change nanoemulsions assessed via high-speed optical microscopy. Phys Med Biol 2013; 58:4513-34. [PMID: 23760161 DOI: 10.1088/0031-9155/58/13/4513] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ultrasonically activated phase-change contrast agents (PCCAs) based on perfluorocarbon droplets have been proposed for a variety of therapeutic and diagnostic clinical applications. When generated at the nanoscale, droplets may be small enough to exit the vascular space and then be induced to vaporize with high spatial and temporal specificity by externally-applied ultrasound. The use of acoustical techniques for optimizing ultrasound parameters for given applications can be a significant challenge for nanoscale PCCAs due to the contributions of larger outlier droplets. Similarly, optical techniques can be a challenge due to the sub-micron size of nanodroplet agents and resolution limits of optical microscopy. In this study, an optical method for determining activation thresholds of nanoscale emulsions based on the in vitro distribution of bubbles resulting from vaporization of PCCAs after single, short (<10 cycles) ultrasound pulses is evaluated. Through ultra-high-speed microscopy it is shown that the bubbles produced early in the pulse from vaporized droplets are strongly affected by subsequent cycles of the vaporization pulse, and these effects increase with pulse length. Results show that decafluorobutane nanoemulsions with peak diameters on the order of 200 nm can be optimally vaporized with short pulses using pressures amenable to clinical diagnostic ultrasound machines.
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Affiliation(s)
- Paul S Sheeran
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC 27599, USA
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23
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Wang X, Chen H, Zheng Y, Ma M, Chen Y, Zhang K, Zeng D, Shi J. Au-nanoparticle coated mesoporous silica nanocapsule-based multifunctional platform for ultrasound mediated imaging, cytoclasis and tumor ablation. Biomaterials 2012; 34:2057-68. [PMID: 23246067 DOI: 10.1016/j.biomaterials.2012.11.044] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Accepted: 11/23/2012] [Indexed: 02/07/2023]
Abstract
Au nanoparticles-coated, perfluorohexane-encapsulated and PEGylated mesoporous silica nanocapsule-based enhancement agents (MSNC@Au-PFH-PEG, abb. as MAPP) have been synthesized, for the ultrasound-induced cytoclasis, contrast-intensified ultrasound (US) imaging and US-guided high intensity focused ultrasound (HIFU) surgical therapy. Both the US-induced thermal effect and US triggered release of loaded model drug with MAPP under US exposure indicated the excellent US sensitivity of MAPP and its applicability for the combined chemo-/thermal therapy and future potential for HIFU ablation; US imaging under different modes verify the attractive US contrast intensification by using MAPP; US-guided HIFU therapy ex vivo and in vivo with MAPP is found to be highly efficient on rabbit VX2 xenograft tumor ablation due to the high thermal energy accumulation and increased mechanical/thermal effects from US-induced PFH bubble cavitations. MAPP can be promisingly used as an inorganic theranostic platform for contrast-intensified US imaging, combined chemotherapy and efficient HIFU tumor ablation under the guidance by the intensified US.
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Affiliation(s)
- Xia Wang
- State Key Laboratory of High Performance Ceramic and Superfine Microstructures, Shanghai Institute of Ceramics Chinese Academy of Science, Shanghai 200050, China
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Abstract
The intersection of particles and directed energy is a rich source of novel and useful technology that is only recently being realized for medicine. One of the most promising applications is directed drug delivery. This review focuses on phase-shift nanoparticles (that is, particles of submicron size) as well as micron-scale particles whose action depends on an external-energy triggered, first-order phase shift from a liquid to gas state of either the particle itself or of the surrounding medium. These particles have tremendous potential for actively disrupting their environment for altering transport properties and unloading drugs. This review covers in detail ultrasound and laser-activated phase-shift nano- and micro-particles and their use in drug delivery. Phase-shift based drug-delivery mechanisms and competing technologies are discussed.
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25
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Sheeran PS, Dayton PA. Phase-change contrast agents for imaging and therapy. Curr Pharm Des 2012; 18:2152-65. [PMID: 22352770 DOI: 10.2174/138161212800099883] [Citation(s) in RCA: 172] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 12/29/2011] [Indexed: 01/24/2023]
Abstract
Phase-change contrast agents (PCCAs) for ultrasound-based applications have resulted in novel ways of approaching diagnostic and therapeutic techniques beyond what is possible with microbubble contrast agents and liquid emulsions. When subjected to sufficient pressures delivered by an ultrasound transducer, stabilized droplets undergo a phase-transition to the gaseous state and a volumetric expansion occurs. This phenomenon, termed acoustic droplet vaporization, has been proposed as a means to address a number of in vivo applications at the microscale and nanoscale. In this review, the history of PCCAs, physical mechanisms involved, and proposed applications are discussed with a summary of studies demonstrated in vivo. Factors that influence the design of PCCAs are discussed, as well as the need for future studies to characterize potential bioeffects for administration in humans and optimization of ultrasound parameters.
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Affiliation(s)
- Paul S Sheeran
- Joint Department of Biomedical Engineering, The University of North Carolina, Chapel Hill, 27599, USA
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Rapoport N. Phase-shift, stimuli-responsive perfluorocarbon nanodroplets for drug delivery to cancer. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2012; 4:492-510. [PMID: 22730185 DOI: 10.1002/wnan.1176] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This review focuses on phase-shift perfluorocarbon nanoemulsions whose action depends on an ultrasound-triggered phase shift from a liquid to gas state. For drug-loaded perfluorocarbon nanoemulsions, microbubbles are formed under the action of tumor-directed ultrasound and drug is released locally into tumor volume in this process. This review covers in detail mechanisms involved in the droplet-to-bubble transition as well as mechanisms of ultrasound-mediated drug delivery.
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Affiliation(s)
- Natalya Rapoport
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA.
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Bardin D, Martz TD, Sheeran PS, Shih R, Dayton PA, Lee AP. High-speed, clinical-scale microfluidic generation of stable phase-change droplets for gas embolotherapy. LAB ON A CHIP 2011; 11:3990-8. [PMID: 22011845 PMCID: PMC3637946 DOI: 10.1039/c1lc20615j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
In this study we report on a microfluidic device and droplet formation regime capable of generating clinical-scale quantities of droplet emulsions suitable in size and functionality for in vivo therapeutics. By increasing the capillary number-based on the flow rate of the continuous outer phase-in our flow-focusing device, we examine three modes of droplet breakup: geometry-controlled, dripping, and jetting. Operation of our device in the dripping regime results in the generation of highly monodisperse liquid perfluoropentane droplets in the appropriate 3-6 μm range at rates exceeding 10(5) droplets per second. Based on experimental results relating droplet diameter and the ratio of the continuous and dispersed phase flow rates, we derive a power series equation, valid in the dripping regime, to predict droplet size, D(d) approximately equal 27(Q(C)/Q(D))(-5/12). The volatile droplets in this study are stable for weeks at room temperature yet undergo rapid liquid-to-gas phase transition, and volume expansion, above a uniform thermal activation threshold. The opportunity exists to potentiate locoregional cancer therapies such as thermal ablation and percutaneous ethanol injection using thermal or acoustic vaporization of these monodisperse phase-change droplets to intentionally occlude the vessels of a cancer.
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Affiliation(s)
- David Bardin
- Department of Biomedical Engineering, University of California, Irvine, CA 92697
| | - Thomas D. Martz
- Curriculum of Applied Sciences and Engineering – Materials Science, The University of North Carolina, Chapel Hill, NC 27599
| | - Paul S. Sheeran
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC 27599
| | - Roger Shih
- Department of Biomedical Engineering, University of California, Irvine, CA 92697
| | - Paul A. Dayton
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC 27599
| | - Abraham P. Lee
- Department of Biomedical Engineering, University of California, Irvine, CA 92697
- Corresponding Author, , Address: 3406 Engineering Hall, University of California, Irvine, Irvine, CA 92697, Phone: (949) 824-9691, Fax: (949) 824-1727
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Sheeran PS, Wong VP, Luois S, Mcfarland RJ, Ross WD, Feingold S, Matsunaga TO, Dayton PA. Decafluorobutane as a phase-change contrast agent for low-energy extravascular ultrasonic imaging. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:1518-30. [PMID: 21775049 PMCID: PMC4450864 DOI: 10.1016/j.ultrasmedbio.2011.05.021] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 05/09/2011] [Accepted: 05/16/2011] [Indexed: 05/03/2023]
Abstract
Currently available microbubbles used for ultrasound imaging and therapeutics are limited to intravascular space due to their size distribution in the micron range. Phase-change contrast agents (PCCAs) have been proposed as a means to overcome this limitation, since droplets formed in the hundred nanometer size range might be able to extravasate through leaky microvasculature, after which they could be activated to form larger highly echogenic microbubbles. Existing PCCAs in the sub-micron size range require substantial acoustic energy to be vaporized, increasing the likelihood of unwanted bioeffects. Thus, there exists a need for PCCAs with reduced acoustic activation energies for use in imaging studies. In this article, it is shown that decafluorobutane, which is normally a gas at room temperature, can be incorporated into metastable liquid sub-micron droplets with appropriate encapsulation methods. The resulting droplets are activatable with substantially less energy than other favored PCCA compounds. Decafluorobutane nanodroplets may present a new means to safely extend ultrasound imaging beyond the vascular space.
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Affiliation(s)
- Paul S. Sheeran
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC, USA
| | - Vincent P. Wong
- Biomedical Engineering Graduate Interdisciplinary Program, The University of Arizona, Tucson, AZ, USA
| | - Samantha Luois
- Undergraduate Biology Research Program, The University of Arizona, Tucson, AZ, USA
- Department of Radiology Research, The University of Arizona, Tucson, AZ, USA
| | - Ryan J. Mcfarland
- Department of Radiology Research, The University of Arizona, Tucson, AZ, USA
| | - William D. Ross
- Department of Internal Medicine, School of Medicine, The University of Arizona, Tucson, AZ, USA
| | - Steven Feingold
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC, USA
| | - Terry O. Matsunaga
- Undergraduate Biology Research Program, The University of Arizona, Tucson, AZ, USA
- Department of Radiology Research, The University of Arizona, Tucson, AZ, USA
| | - Paul A. Dayton
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC, USA
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Zhang M, Fabiilli ML, Haworth KJ, Padilla F, Swanson SD, Kripfgans OD, Carson PL, Fowlkes JB. Acoustic droplet vaporization for enhancement of thermal ablation by high intensity focused ultrasound. Acad Radiol 2011; 18:1123-32. [PMID: 21703883 DOI: 10.1016/j.acra.2011.04.012] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 03/30/2011] [Accepted: 04/08/2011] [Indexed: 01/19/2023]
Abstract
RATIONALE AND OBJECTIVES Acoustic droplet vaporization (ADV) shows promise for spatial control and acceleration of thermal lesion production. The investigators hypothesized that microbubbles generated by ADV could enhance high-intensity focused ultrasound (HIFU) thermal ablation by controlling and increasing local energy absorption. MATERIALS AND METHODS Thermal lesions were produced in tissue-mimicking phantoms using focused ultrasound (1.44 MHz) with a focal intensity of 4000 W · cm(-2) in degassed water at 37°C. The average lesion volume was measured by visible change in optical opacity and by T2-weighted magnetic resonance imaging. In addition, in vivo HIFU lesions were generated in a canine liver before and after an intravenous injection of droplets with a similar acoustic setup. RESULTS Thermal lesions were sevenfold larger in phantoms containing droplets (3 × 10(5) droplets/mL) compared to phantoms without droplets. The mean lesion volume with a 2-second HIFU exposure in droplet-containing phantoms was comparable to that made by a 5-second exposure in phantoms without droplets. In the in vivo study, the average lesion volumes without and with droplets were 0.017 ± 0.006 cm(3) (n = 4; 5-second exposure) and 0.265 ± 0.005 cm(3) (n = 3; 5-second exposure), respectively, a factor of 15 difference. The shape of ADV bubbles imaged with B-mode ultrasound was very similar to the actual lesion shape as measured optically and by magnetic resonance imaging. CONCLUSION ADV bubbles may facilitate clinical HIFU ablation by reducing treatment time or requisite in situ total acoustic power and provide ultrasonic imaging feedback of the thermal therapy.
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Affiliation(s)
- Man Zhang
- Department of Radiology, University of Michigan Health System, Ann Arbor, 48109, USA.
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Rapoport NY, Nam KH, Gao Z, Kennedy A. Application of Ultrasound for Targeted Nanotherapy of Malignant Tumors. ACOUSTICAL PHYSICS 2009; 55:594-601. [PMID: 20160872 PMCID: PMC2771883 DOI: 10.1134/s1063771009040162] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The article describes the study of targeted chemotherapeutic intervention on solid tumors by means of ultrasound and doxorubicin- or paclitaxel-loaded perfluoropentane nanoemulsions. Nanodroplets of the emulsions accumulated in a tumor by passive targeting. Under the action of a tumor-directed therapeutic ultrasound, the nanodroplets converted into vapor microbubbles. In vivo, the nanodroplets strongly retained the loaded drugs; yet, under ultrasound-mediated vaporization they released the drugs into the tumor tissue, thereby implementing effective targeting into the tumor. The tumors subjected to this treatment regressed effectively; however, after some time they recurred. The recurring tumors were more resistant to the repeated therapy than the primary ones. At present, the causes of of the resistance development and methods for its elimination are unclear and they are under investigation.
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Affiliation(s)
- N Ya Rapoport
- Department of Bioengineering, University of Utah, USA
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Vanhille C, Campos-Pozuelo C. Nonlinear ultrasonic waves in bubbly liquids with nonhomogeneous bubble distribution: Numerical experiments. ULTRASONICS SONOCHEMISTRY 2009; 16:669-685. [PMID: 19171496 DOI: 10.1016/j.ultsonch.2008.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 11/18/2008] [Accepted: 11/18/2008] [Indexed: 05/27/2023]
Abstract
This paper deals with the nonlinear propagation of ultrasonic waves in mixtures of air bubbles in water, but for which the bubble distribution is nonhomogeneous. The problem is modelled by means of a set of differential equations which describes the coupling of the acoustic field and bubbles vibration, and solved in the time domain via the use and adaptation of the SNOW-BL code. The attenuation and nonlinear effects are assumed to be due to the bubbles exclusively. The nonhomogeneity of the bubble distribution is introduced by the presence of bubble layers (or clouds) which can act as acoustic screens, and alters the behaviour of the ultrasonic waves. The effect of the spatial distribution of bubbles on the nonlinearity of the acoustic field is analyzed. Depending on the bubble density, dimension, shape, and position of the layers, its effects on the acoustic field change. Effects such as shielding and resonance of the bubbly layers are especially studied. The numerical experiments are carried out in two configurations: linear and nonlinear, i.e. for low and high excitation pressure amplitude, respectively, and the features of the phenomenon are compared. The parameters of the medium are chosen such as to reproduce air bubbly water involved in the stable cavitation process.
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Affiliation(s)
- Christian Vanhille
- ESCET, Universidad Rey Juan Carlos, Tulipán, s/n. 28933 Móstoles, Madrid, Spain.
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Eshpuniyani B, Fowlkes JB, Bull JL. A Boundary Element Model of Microbubble Sticking and Sliding in the Microcirculation. INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2008; 51:5700-5711. [PMID: 19885367 PMCID: PMC2678726 DOI: 10.1016/j.ijheatmasstransfer.2008.04.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A pressure driven 2-D channel flow at very low Reynolds numbers (Stokes flow) with a bubble sticking and sliding along one of the walls is studied computationally using the boundary element method (BEM). The moving three phase contact lines are modeled using a Tanner law wherein the contact line speed is linearly proportional to the deviation of the contact angle from its equilibrium value. Results are presented with and without the effect of contact angle hysteresis. Including contact angle hysteresis allows us to predict the stick-slide behavior of bubbles, which in turn affects the long term evolution and dynamics of the bubbles. It is shown that the initial rapid contraction or expansion of the bubbles to achieve local equilibrium with the surrounding pressure field results in cusps and bulges in the wall normal stress profiles. The wall shear stress also increases (with opposite signs upstream and downstream of the bubble) as the fluid rushes in or out of the channel inlet and outlet. In the long term, bubbles slowly expand as they slide along the channel wall. Contact lines are found to correspond to peaks in the wall normal and shear stress profiles at all times. The effectiveness of bubbles in occluding flow through the channel is also examined.
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Affiliation(s)
| | - J. Brian Fowlkes
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Joseph L. Bull
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
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Vanhille C, Campos-Pozuelo C. Nonlinear ultrasonic propagation in bubbly liquids: a numerical model. ULTRASOUND IN MEDICINE & BIOLOGY 2008; 34:792-808. [PMID: 18314254 DOI: 10.1016/j.ultrasmedbio.2007.11.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 10/31/2007] [Accepted: 11/06/2007] [Indexed: 05/26/2023]
Abstract
In this paper, we investigate the problem of ultrasonic propagation in liquids with bubbles. A new numerical algorithm is constructed to solve the acoustic field-bubbles vibration coupled system. For this purpose, a second-order equation written in a volume formulation is considered for bubbles vibration and coupled with the linear nondissipative wave equation, i.e., attenuation and nonlinear effects are supposed to occur exclusively because of the presence of bubbles. Nonlinear characteristics of the phenomenon are particularly analyzed and illustrated. Plane harmonic waves are first considered in a mixture of air bubbles in water, and conclusions about changes in the wave speed, attenuation, harmonic distortion, effective nonlinearity parameter and nonlinear effects with distance are given. In particular, a law relating the second-harmonic progression with the density of bubbles is found. The propagation of plane pulses is also analyzed to give results on nonlinear attenuation, changes of frequency, and self-demodulation. The influence of the resonance frequency of bubbles on the nonlinear field is then determined. Differences and similarities with nonlinear acoustics in homogeneous fluid are shown and commented. The possibilities and limits of an equivalent nonlinear fluid are then discussed. The propagation of a high-frequency pulsed signal in a bubbly liquid used in a biological application is also the subject of numerical experiments, for frequencies near and beyond the resonance frequency of the bubbles.
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Sassaroli E, Hynynen K. Cavitation threshold of microbubbles in gel tunnels by focused ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 2007; 33:1651-60. [PMID: 17590501 PMCID: PMC2078601 DOI: 10.1016/j.ultrasmedbio.2007.04.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2006] [Revised: 04/20/2007] [Accepted: 04/26/2007] [Indexed: 05/11/2023]
Abstract
The investigation of inertial cavitation in micro-tunnels has significant implications for the development of therapeutic applications of ultrasound such as ultrasound-mediated drug and gene delivery. The threshold for inertial cavitation was investigated using a passive cavitation detector with a center frequency of 1 MHz. Micro-tunnels of various diameters (90 to 800 microm) embedded in gel were fabricated and injected with a solution of Optison(trade mark) contrast agent of concentrations 1.2% and 0.2% diluted in water. An ultrasound pulse of duration 500 ms and center frequency 1.736 MHz was used to insonate the microbubbles. The acoustic pressure was increased at 1-s intervals until broadband noise emission was detected. The pressure threshold at which broadband noise emission was observed was found to be dependent on the diameter of the micro-tunnels, with an average increase of 1.2 to 1.5 between the smallest and the largest tunnels, depending on the microbubble concentration. The evaluation of inertial cavitation in gel tunnels rather than tubes provides a novel opportunity to investigate microbubble collapse in a situation that simulates in vivo blood vessels better than tubes with solid walls do.
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Affiliation(s)
- Elisabetta Sassaroli
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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Rapoport N, Gao Z, Kennedy A. Multifunctional Nanoparticles for Combining Ultrasonic Tumor Imaging and Targeted Chemotherapy. ACTA ACUST UNITED AC 2007; 99:1095-106. [PMID: 17623798 DOI: 10.1093/jnci/djm043] [Citation(s) in RCA: 389] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Drug delivery in polymeric micelles combined with tumor irradiation by ultrasound results in effective drug targeting, but this technique requires prior tumor imaging. A technology that combined ultrasound imaging with ultrasound-mediated nanoparticle-based targeted chemotherapy could therefore have important applications in cancer treatment. METHODS Mixtures of drug-loaded polymeric micelles and perfluoropentane (PFP) nano/microbubbles stabilized by the same biodegradable block copolymer were prepared. Size distribution of nanoparticles was measured by dynamic light scattering. Cavitation activity (oscillation, growth, and collapse of microbubbles) under ultrasound was assessed based on the changes in micelle/microbubble volume ratios. The effect of the nano/microbubbles on the ultrasound-mediated cellular uptake of doxorubicin (Dox) in MDA MB231 breast tumors in vitro and in vivo (in mice bearing xenograft tumors) was determined by flow cytometry. Statistical tests were two-sided. RESULTS Phase state and nanoparticle sizes were sensitive to the copolymer/perfluorocarbon volume ratio. At physiologic temperatures, nanodroplets converted into nano/microbubbles. Doxorubicin was localized in the microbubble walls formed by the block copolymer. Upon intravenous injection into mice, Dox-loaded micelles and nanobubbles extravasated selectively into the tumor interstitium, where the nanobubbles coalesced to produce microbubbles with a strong, durable ultrasound contrast. Doxorubicin was strongly retained in the microbubbles but released in response to therapeutic ultrasound. Microbubbles cavitated under the action of tumor-directed ultrasound, which enhanced intracellular Dox uptake by tumor cells in vitro to a statistically significant extent relative to that observed with unsonicated microbubbles (drug uptake ratio = 4.60; 95% confidence interval [CI] = 1.70 to 12.47; P = .017) and unsonicated micelles (drug uptake ratio = 7.97; 95% CI = 3.72 to 17.08; P = .0032) and resulted in tumor regression in the mouse model. CONCLUSIONS Multifunctional nanoparticles that are tumor-targeted drug carriers, long-lasting ultrasound contrast agents, and enhancers of ultrasound-mediated drug delivery have been developed and deserve further exploration as cancer therapeutics.
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Affiliation(s)
- Natalya Rapoport
- Department of Bioengineering, University of Utah, 20 S. 2030 E. Rm 108, Salt Lake City, UT 84112, USA.
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Coussios CC, Farny CH, Haar GT, Roy RA. Role of acoustic cavitation in the delivery and monitoring of cancer treatment by high-intensity focused ultrasound (HIFU). Int J Hyperthermia 2007; 23:105-20. [PMID: 17578336 DOI: 10.1080/02656730701194131] [Citation(s) in RCA: 243] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Acoustic cavitation has been shown to play a key role in a wide array of novel therapeutic ultrasound applications. This paper presents a brief discussion of the physics of thermally relevant acoustic cavitation in the context of high-intensity focussed ultrasound (HIFU). Models for how different types of cavitation activity can serve to accelerate tissue heating are presented, and results suggest that the bulk of the enhanced heating effect can be attributed to the absorption of broadband acoustic emissions generated by inertial cavitation. Such emissions can be readily monitored using a passive cavitation detection (PCD) scheme and could provide a means for real-time treatment monitoring. It is also shown that the appearance of hyperechoic regions (or bright-ups) on B-mode ultrasound images constitutes neither a necessary nor a sufficient condition for inertial cavitation activity to have occurred during HIFU exposure. Once instigated at relatively large HIFU excitation amplitudes, bubble activity tends to grow unstable and to migrate toward the source transducer, causing potentially undesirable pre-focal damage. Potential means of controlling inertial cavitation activity using pulsed excitation so as to confine it to the focal region are presented, with the intention of harnessing cavitation-enhanced heating for optimal HIFU treatment delivery. The role of temperature elevation in mitigating bubble-enhanced heating effects is also discussed, along with other bubble-field effects such as multiple scattering and shielding.
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Affiliation(s)
- C C Coussios
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.
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