Transient pulsations of small gas bubbles in water

Flynn, H. G.; Church, Charles C.

doi:10.1121/1.396614

Cited by 134 publications

(64 citation statements)

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“…One possible source is bubbles undergoing stable cavitation [14,15], where the bubbles oscillate in the acoustic field near, but not quite at the points of implosion. Stable cavitation with a subharmonic component has been previously reported [15][16][17][18][19][20].…”

Section: Proposed Mechanismmentioning

confidence: 99%

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Further investigation of the mechanism of Doxorubicin release from P105 micelles using kinetic models

Stevenson-Abouelnasr

Husseini

Pitt

2007

Colloids and Surfaces B: Biointerfaces

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The kinetics of the release of Doxorubicin from Pluronic P105 micelles during ultrasonication and its subsequent re-encapsulation upon cessation of insonation were investigated. Four mechanisms are proposed to explain the acoustically-triggered Doxorubicin (Dox) release and re-encapsulation from Pluronic P105 micelles. The four mechanisms are: micelle destruction; destruction of cavitating nuclei; reassembly of micelles, and the re-encapsulation of Dox. The first mechanism, the destruction of micelles during insonation, causes the release of Dox into solution. The micelles are destroyed because of cavitation events produced by collapsing nuclei, or bubbles in the insonated solution. The second mechanism, the slow destruction of cavitating nuclei, results in a slow partial recovery phase, when a small amount of Dox is re-encapsulated. The third and fourth mechanisms, the reassembly of micelles and the re-encapsulatin of Dox, are independent of ultrasound. These two mechanism are responsible for maintaining the drug release at a partial level, and for recovery after insonation ceases. A normal distribution was used to describe micellar size. Parameters for the model were determined based upon the best observed fit to experimental data. The resulting model provides a good approximation to experimental data for the release of Dox from Pluronic P105 micelles.

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Section: Proposed Mechanismmentioning

confidence: 99%

“…(4) into the above equation yields the following relation. (16) As new micelles are formed, they add to the capacity for their group to encapsulate Dox. The rate of encapsulation of the free drug is assumed to be first order with respect to the amount of free Dox, F, and the remaining capacity for the micellar group to store Dox.…”

Section: Encapsulated Doxmentioning

confidence: 99%

Further investigation of the mechanism of Doxorubicin release from P105 micelles using kinetic models

Stevenson-Abouelnasr

Husseini

Pitt

2007

Colloids and Surfaces B: Biointerfaces

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“…Inertial cavitation occurs at higher acoustic pressure and is associated with several physical phenomena (23). During the rapid collapse of the gas bubble the inward moving wall of fluid has sufficient inertia so that it cannot reverse direction when the acoustic pressure reverses direction, but continues to compress the gas in the bubble to a very small volume.…”

Section: Inertial Cavitationmentioning

confidence: 99%

The role of ultrasound and magnetic resonance in local drug delivery

Deckers

Rome

Moonen

2008

Magnetic Resonance Imaging

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Local drug delivery has recently attracted much attention since it represents a strategy to increase the drug concentration at the target location and decrease systemic toxicity effects. Ultrasound can be used in different ways to trigger regional drug delivery. It can cause the local drug release from a carrier vehicle and the local increase of cell membrane permeability either by a mechanical action or by a temperature increase. Ultrasound contrast agents may enhance these effects by means of cavitation. Ultrasound can be focused deep inside the body into a small region with dimensions on the order of 1 mm. Several types of drug microcarriers have been proposed, from nano-to micrometer sized particles. The objective of real-time imaging of local drug delivery is to assure that the delivery takes place in the target region, that the drug concentration and the resulting physiological reaction are sufficient, and to intervene if necessary. Ultrasound and nuclear imaging techniques play an important role. MRI is rather insensitive but allows precise targeting of (focused) ultrasound, can provide real-time temperature maps, and gives access to a variety of imaging biomarkers that may be used to assess drug action. Examples from recent articles illustrate the potential of the principles of ultrasound-triggered local drug delivery.

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“…The response of the bubbles to the acoustic wave was simulated by solving the Gilmore-Akulichev (eq1) formulation for bubble dynamics [30][31][32][33][34]. The calculations assumed that the ultrasound waves were not corrupted by nonlinear propagation distortion and that the bubble remained spherical throughout the simulation.…”

Section: Simulation Parametersmentioning

confidence: 99%

“…Ultrasound thermal ablation uses the energy in the ultrasound waves to heat and kill targeted tissue and has been extensively studied [2][3][4][5][6][7][8][9][10][11][12][13][14]. In addition to killing tissue, ultrasound therapies are being successfully developed to enhance thrombolysis [15,16], improve drug and gene delivery [17][18][19][20][21][22], control bleeding and hemorrhaging from severe trauma [13,24], and erode or liquefy tissue by controlled technique [7,[25][26][27][28][29][30]. Many of these developing therapies have been found to depend upon or be significantly enhanced by the cavitation of microbubbles.…”

Section: Introductionmentioning

confidence: 99%

Dependence of Cavitation Bubble Size on Pressure Amplitude at Therapeutic Levels

Carvell¹,

Bigelow²

2009

AIP Conference Proceedings

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High-intensity, focused ultrasound therapy is a minimally invasive therapy technique that is effective and relatively safe. It can be used in areas including histotripsy, thermal ablation, and administering medication. Inertial cavitation is used to improve these therapy methods. The purpose of this study was to determine the effect of pressure amplitude on cavitation resonance frequency/bubble size at therapeutic field levels. Earlier work has indicated that the resonance size depends on pressure amplitude; however, the investigation only considered pressure amplitudes up to 1 MPa [1]. Our study was conducted by simulating the response of bubbles to linearly propagating sine waves using the Gilmore-Akulichev formulation to solve for the bubble response. The frequency of the sine wave varied from 1 to 5 MHz while the amplitude of the sine wave varied from 0.0001 to 9 MPa. The resonance size for a particular frequency of excitation and amplitude was determined by finding the initial bubble size that resulted in the maximum bubble expansion for an air bubble in water. The simulations demonstrated a downshift in resonance size with increasing pressure amplitude. Therefore, smaller bubbles will have a more dramatic response to ultrasound at therapeutic levels. KeywordsBubble dynamics, cavitation, therapeutics, high pressure, sound pressure Disciplines Biomedical | Biomedical Devices and Instrumentation | Electrical and Computer Engineering CommentsThe following article appeared in AIP Conference Proceedings 1113 (2009) Abstract High-intensity, focused ultrasound therapy is a minimally invasive therapy technique that is effective and relatively safe. It can be used in areas including histotripsy, thermal ablation, and administering medication. Inertial cavitation is used to improve these therapy methods. The purpose of this study was to determine the effect of pressure amplitude on cavitation resonance frequency/bubble size at therapeutic field levels. Earlier work has indicated that the resonance size depends on pressure amplitude; however, the investigation only considered pressure amplitudes up to 1 MPa [1]. Our study was conducted by simulating the response of bubbles to linearly propagating sine waves using the Gilmore-Akulichev formulation to solve for the bubble response. The frequency of the sine wave varied from 1 to 5 MHz while the amplitude of the sine wave varied from 0.0001 to 9 MPa. The resonance size for a particular frequency of excitation and amplitude was determined by finding the initial bubble size that resulted in the maximum bubble expansion for an air bubble in water. The simulations demonstrated a downshift in resonance size with increasing pressure amplitude. Therefore, smaller bubbles will have a more dramatic response to ultrasound at therapeutic levels..

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Transient pulsations of small gas bubbles in water

Cited by 134 publications

References 0 publications

Further investigation of the mechanism of Doxorubicin release from P105 micelles using kinetic models

Further investigation of the mechanism of Doxorubicin release from P105 micelles using kinetic models

The role of ultrasound and magnetic resonance in local drug delivery

Dependence of Cavitation Bubble Size on Pressure Amplitude at Therapeutic Levels

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