Tyrone Porter

• PhD
• Professor at University of Texas at Austin

The problem of attenuation and sound speed of bubbly media has remained partially unsolved. Comprehensive data regarding pressure-dependent changes of the attenuation and sound speed of a bubbly medium are not available. Our theoretical understanding of the problem is limited to linear or semi-linear theoretical models, which are not accurate in th...

No PDF available ABSTRACT Acoustic vaporization of perfluorobutane-based phase-shift nanoemulsions (PSNE) can be used to nucleate inertial cavitation (IC) in vivo. The acoustic pressure amplitude must exceed a threshold for vaporization of PFB-based nanoemulsions. Two focused ultrasound transducers with a center frequency of 837 kHz were oriented s...

The problem of attenuation and sound speed of bubbly media has remained partially unsolved. Comprehensive data regarding pressure-dependent changes of the attenuation and sound speed of a bubbly medium are not available. Our theoretical understanding of the problem is limited to linear or semi-linear theoretical models, which are not accurate in th...

This report is an updated report for our previous work "Probing the pressure dependence of sound speed and attenuation in bubbly media: Experimental observations and numerical calculations". In this report, we investigate in detail the influence of the bubble-bubble interactions on the changes of sound speed and attenuation in bubbly media. Togethe...

A lipid coated bubble (LCB) oscillator is a very interesting non-smooth oscillator with many important applications ranging from industry and chemistry to medicine. However, due to the complex behavior of the coating intermixed with the nonlinear behavior of the bubble itself, the dynamics of the LCB are not well understood. In this work, lipid coa...

Attenuation and sound speed of bubbly media are one of the fundamental problems in acoustics. The problem is of general interest due to the wide range of applications related to the physics of the bubbly media including but not limited to underwater acoustics, oceanography, sonochemistry, and several medical applications (e.g. contrast-enhanced ima...

A lipid coated bubble (LCB) oscillator is a very interesting non-smooth oscillator with many important applications ranging from industry and chemistry to medicine. However, due to the complex behavior of the coating intermixed with the nonlinear behavior of the bubble itself, the dynamics of the LCB are not well understood. In this work, lipid coa...

Nonlinear behavior of bubbles, and most importantly \(\frac{1}{2}\)-order subharmonics (SH), are used to increase the contrast-to-tissue ratio (CTR) in diagnostic ultrasound (US) and to monitor bubble-mediated therapeutic US. It is shown experimentally and numerically that when bubbles are sonicated with a frequency that is twice their resonance fr...

Tumor immunity is a rapidly evolving area of research consisting of many possible permutations of immune cell tumor interactions that are dependent upon cell type, tumor type, and stage in tumor progression. At the same time, the majority of cancer immunotherapies have been focused on modulating the T cell-mediated antitumor immune response and hav...

This study presents the fundamental equations governing the pressure dependent disipation mechanisms in the oscillations of coated bubbles. A simple generalized model (GM) for coated bubbles accounting for the effect of compressibility of the liquid is presented. The GM was then coupled with nonlinear ODEs that account for the thermal effects. Star...

No PDF available ABSTRACT Ultrasound nonthermal ablation is an emerging noninvasive technology for transcranial ablation. Nonthermal ablation has been achieved previously through inertial cavitation of ultrasound contrast agents (UCA). However, it is possible to generate unwanted damage in pre-focal regions due to the presence of UCA throughout the...

A simple generalized model (GM) for coated bubbles accounting for the effect of compressibility of the liquid is presented. The GM was then coupled with nonlinear ODEs that account for the thermal effects. Starting with mass and momentum conservation equations for a bubbly liquid and using the GM, nonlinear pressure dependent terms were derived for...

The acoustic bubble is an example of a highly nonlinear system which is the building block of several applications and phenomena ranging from underwater acoustics to sonochemistry and medicine. Nonlinear behavior of bubbles, and most importantly 1/2 order subharmonics (SH), are used to increase the contrast to tissue ratio (CTR) in diagnostic ultra...

High intensity focused ultrasound (HIFU) mechanical ablation is an emerging technique for non-invasive transcranial surgery. Lesions are created by driving inertial cavitation in tissue, which requires significantly less peak pressure and time-averaged power compared with traditional thermal ablation. The utility of mechanical ablation could be ext...

Magnetic resonance image-guided focused ultrasound has emerged as a viable non-invasive technique for the treatment of central nervous system-related diseases/disorders. Application of mechanical and thermal effects associated with focused transcranial ultrasound has been studied extensively in pre-clinical models, which has paved the way for clini...

Acoustic cavitation can be used to temporarily disrupt cell membranes for intracellular delivery of large biomolecules. Termed sonoporation, the ability of this technique for efficient intracellular delivery (i.e., >50% of initial cell population showing uptake) while maintaining cell viability (i.e., >50% of initial cell population viable) has pro...

p53, The tumour suppressor protein encoded by P53 gene, is the most commonly altered protein in the human malignancies. MDM2 controls the p53 activity through an autoregulatory feedback loop. p53 activates the expression of MDM2 and in return, MDM2 blocks the p53 activity through various mechanisms. Nutlins, including nutlin-3, are a new class of s...

The recent emergence of immunotherapies is transforming cancer treatments. Although many cancer immunotherapies are finding enormous success for treating hematologic tumors, a major obstacle for the treatment of solid tumors is localizing immune cells to the tumor site. Therefore, we have developed a technology that is capable of directing immune c...

Results of the measurements of sound speed and attenuation in a bubbly medium are reported. Monodisperse bubble solutions are sonicated with broadband ultrasound pulses with pressure amplitudes ranging between 12.5-100 kPa. Fundamental relationships between the frequency dependent attenuation, sound speed and pressure are established. A new model f...

The ability to tailor acoustic cavitation of contrast agents is pivotal for ultrasound applications in enhanced imaging, drug delivery, and cancer therapy, etc. A biopolymer-based system of microbubbles and nanobubbles was developed as acoustic reporters that consist of extremely porous hard-shells. Despite the existence of an incompressible shell,...

The blood-brain barrier (BBB) limits transport of nanoparticles from the circulation to the brain parenchyma. Angiopep-2, a peptide which functions as a brain transport vector, can be coupled to nanoparticles in order to facilitate binding and internalization by brain endothelial cells (ECs), and subsequent BBB penetration. This multi-step process...

Representative calibration curves of fluorescent dextrans. The concentration of dextran in the x-axis, expressed as the number of dextrans, in units of micromoles, per liter of solution (µM), was determined by adding a measured mass of dextran to a measured volume of PBS. Fluorescence in the y-axis was measured using a SpectraMax M5 plate reader wh...

Representative calibration curves of Ang2-liposomes. The concentration of liposomes in the x-axis, expressed as the number of liposomes, in units of picomoles per liter of solution (pM), was determined using a qNANO (Izon Science). Fluorescence in the y-axis was measured using a SpectraMax M5 plate reader where the volume of all samples was kept co...

Thermal ablation of solid tumors via focused ultrasound (FUS) is a non-invasive image-guided alternative to conventional surgical resection. However, the usefulness of the technique is limited in vascularized organs because of convection of heat, resulting in long sonication times and unpredictable thermal lesion formation. Acoustic cavitation has...

High intensity focused ultrasound (HIFU) thermal ablation is an emerging technique for noninvasive transcranial surgery. One of the major issues of transcranial HIFU thermal ablation is that the pressure and power required to generate lesions is relatively high and could induce skull heating and pain in some cases. Artificial nuclei like phase shif...

Background: The proximal aorta normally functions as a critical shock absorber that protects small downstream vessels from damage by pressure and flow pulsatility generated by the heart during systole. This shock absorber function is impaired with age because of aortic stiffening. Methods and results: We examined the contribution of common genet...

Cavitation, or the creation and oscillation of bubbles, has a pivotal role in a variety of biomedical applications that involve ultrasound. For example, stable oscillating bubbles (stable cavitation) can reversibly permeabilize biological interfaces, including cell membranes and the blood-brain barrier. Bubbles that collapse inertially (inertial ca...

The use of ultrasound in biomedical applications has evolved dramatically in the last few decades. Biomedical ultrasound first gained widespread use clinically as an imaging modality for monitoring pregnancy and diagnosing cardiovascular diseases. The introduction of encapsulated microbubbles as contrast agents enabled the development of contrast-e...

Focused ultrasound (FUS) has the potential to enable precise, image-guided noninvasive surgery for the treatment of cancer in which tumors are identified and destroyed in a single integrated procedure. However, success of the method in highly vascular organs has been limited due to heat losses to perfusion, requiring development of techniques to lo...

Measurements of microbubble (MB) shell parameters is a challenging task because of the nonlinear dynamics of MBs. Shell parameter estimations that are typically based on solving linear models will generate inaccurate results, especially at higher pressure excitations. These approaches also often ignore the analysis of sound speed which provides use...

The presence of bubbles changes the attenuation and sound speed of a medium. These changes in medium properties depend on the nonlinear behavior of bubbles which are not well understood. Previous studies employed linear models for the calculation of the attenuation and sound speed of bubbly mediums. These predictions are not valid in the regime of...

Subharmonic emissions from lipid-coated microbubbles, which is not radiated by tissues, can be leveraged to improve contrast-enhanced diagnosticultrasound. In our work, we investigated subharmonic emissions from monodisperse lipid-coated microbubbles under different acoustic pressure and frequencies. First, the resonance frequency of microbubble mo...

http://www.fusfoundation.org/symposium/2016/docs/FUSF_Symposium_2016_Abstracts_web.pdf

Existence of bubbles in a medium changes the attenuation and sound speed (Cs) of the medium. The relationship between the nonlinear oscillations of the MBs and acoustical parameters of the medium is not fully understood. In this work, monodisperse solutions of lipid coated bubbles with mean diameter of 5.2 micron and peak concentration of (5000 mic...

Presence of the MBs in the sound field increases the attenuation of the medium and changes the sound speed. A detailed knowledge about the attenuation of the medium is critical for controlling and optimizing the behavior of the MBs in applications. However, existing models of ultrasound attenuation in bubbly mediums are based on linear approximatio...

The main objective of this study was to examine liposome extravasation across the BBB as a function of size after disruption via ultrasound and microbubbles. The liposomes were labeled with gadolinium (Gd) and fluorophore, thus enabling detection of extravasated liposomes via MRIin vivo and fluorescence methods in tissue, respectively. Liposomes la...

Broadband attenuation of ultrasoundmeasured at different excitation pressures being different raises a serious theoretical concern, because the underlying assumption of linear and independent propagation of different frequency components nominally requires attenuation to be independent of excitation. This issue is investigated by examining ultrasou...

Broadband attenuation of ultrasound measured at different excitation pressures being different raises a serious theoretical concern, because the underlying assumption of linear and independent propagation of different frequency components nominally requires attenuation to be independent of excitation. Here, this issue is investigated by examining u...

Brain drug delivery is a major challenge for therapy of central nervous system (CNS) diseases. Biochemical modifications of drugs or drug nanocarriers, methods of local delivery, and blood-brain barrier (BBB) disruption with focused ultrasound and microbubbles are promising approaches which enhance transport or bypass the BBB. These approaches are...

The size, drug loading, drug release kinetics, localization, biodistribution, and stability of a given polymeric nanoparticle (NP) system depend on the composition of the NP core as well as its surface properties. In this study, novel, pH-responsive, and lipid-coated NPs, which expand in size from a diameter of approximately 100 nm to 1000 nm in th...

Localized, targeted delivery of small interfering ribonucleic acid (siRNA) has been the foremost hurdle in the use of siRNA for the treatment of various diseases. Major advances have been achieved in the synthesis of siRNA, which have led to greater target messenger RNA (mRNA) silencing and stability under physiologic conditions. Although numerous...

Subharmonic imaging is an ultrasound imaging method which utilizes the subharmonic response of a contrast agent to ultrasound excitation. It is possible to achieve high agent-to-tissue contrast because tissues do not emit subharmonic signals. In this project, we investigated the relationship between subharmonic emissions from monodisperse lipid-coa...

Phagocytosis had been attributed predominantly to “professional” phagocytes such as macrophages, which play critical roles in adipose tissue inflammation. However, recently, macrophage-like phagocytic activity has been reported in B1 B lymphocytes. Intrigued by the long-established correlation between high fat diet (HFD)-induced obesity and immune...

The ability of low boiling point liquid perfluorocarbons (PFCs) to undergo a phase change from a liquid to a gas upon ultrasound irradiation makes PFC-based emulsions promising vehicles for triggered delivery of payloads. However, loading hydrophilic agents into PFC-based emulsions is difficult due to their insolubility in PFC. Here, we address thi...

Compositions and methods for transport or release of therapeutic and diagnostic agents or metabolites or other analytes from cells, compartments within cells, or through cell layers or barriers are described. The compositions include a membrane barrier transport enhancing agent and are usually administered in combination with an enhancer and/or exp...

The acoustic attenuation spectrum of lipid-coated microbubble suspensions was measured in order to characterize the linear acoustic behavior of ultrasound contrast agents. For that purpose, microbubbles samples were generated with a very narrow size distribution by using microfluidics techniques. A performance as good as optical characterization te...

Thermosensitive liposomes have emerged as a viable strategy for localized delivery and triggered release of chemotherapy. MR-guided focused ultrasound (MRgFUS) has the capability of heating tumors in a controlled manner, and when combined with thermosensitive liposomes can potentially reduce tumor burden in vivo. However, the impact of this drug de...

Advanced tumors are often inoperable due to their size and proximity to critical vascular structures. High intensity focused ultrasound (HIFU) has been developed to non-invasively thermally ablate inoperable solid tumors. However, the clinical feasibility of HIFU ablation therapy has been limited by the long treatment times (on the order of hours)...

Ultrasound (US)-targeted microbubbles (MB) destruction (UTMD) is a promising non-viral physical strategy for gene delivery. Our previous studies showed that US/MB mediated plasmid DNA (pDNA) gene transfer significantly enhanced transgene expression in murine and dog models. The efficiency of US/MB-mediated transfection could be improved by packagin...

At the dawn of a new era in medicine, the future of biomedical acoustics is bright. In the last century, we witnessed the introduction of ultrasound contrast agents, lithotripsy, and the visualization of ultrasoundimages in three dimensions. Currently, scientists are developing acoustic-based techniques for opening the blood–brain barrier transient...

In this study, frequency-dependent attenuation was measured acoustically for monodisperse lipid-coated microbubble suspensions as a function of excitation pressure and radius. The resonance frequency was identified from the attenuation spectra and had an inverse relationship with mean microbubble diameter and excitation pressure. A reduction in the...

Recent advances in ultrasound-related technologies have had a significant impact on enhancing image quality as well as offering new approaches for quantitative ultrasonic imaging and therapeutic applications. The presentations associated with this session will provide an overview of advances in ultrasound image formation, the development of using n...

Application of high-intensity focused ultrasound to drug-loaded superhydrophobic meshes affords triggered drug release by displacing an entrapped air layer. The air layer within the superhydrophobic meshes is characterized using direct visualization and B-mode imaging. Drug-loaded superhydrophobic meshes are cytotoxic in an in vitro assay after ult...

Acoustic cavitation offers a unique approach to small interfering RNA (siRNA) delivery compared to current methods. Typically, preformed microbubbles are used as cavitation nuclei to permeabilize cells and facilitate siRNA entry into the cytoplasm. However, microbubbles are restricted to the vasculature space and suffer from stability issues that l...

Background The clinical feasibility of using high-intensity focused ultrasound (HIFU) for ablation of solid tumors is limited by the high acoustic pressures and long treatment times required. The presence of microbubbles during sonication can increase the absorption of acoustic energy and accelerate heating. However, formation of microbubbles withi...

Liposomes are a promising class of nanomedicine with the potential to provide site-specific chemotherapy, thus improving the quality of cancer patient care. First-generation liposomes have emerged as one of the first nanomedicines used clinically for localized delivery of chemotherapy. Second-generation liposomes, i.e. stimuli-responsive liposomes,...

Magnetic resonance-guided high intensity focused ultrasound (MRgHIFU) is being explored as a non-invasive technology to treat solid tumors. However, the clinical use of HIFU for tumor ablation applications is currently limited by the long treatment times required. Phase-shift nanoemulsions (PSNE), consisting of liquid perfluorocarbon droplets that...

High-intensity focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To enhance localized heating and improve thermal ablation in tumors, lipid-coated perfluorocarbon droplets have been developed which can be vaporized by HIFU. The vasculature in many tumors is abnormally leaky due to their rapid growth, and nanoparticles are abl...

Wes Nyborg was a pioneer in the field of biomedical ultrasound. In particular, Nyborg conducted extensive studies that provided insight into how bubbles oscillating in liquids generated forces that could alter the anatomy and/or physiology of cells. While these studies demonstrated that acoustic cavitation is instrumental in a variety of bioeffects...

Cardiovascular diseases are widely prevalent in western societies, and their associated costs number in the billions of dollars and affect millions of patients each year. Nanovectors targeted to tissues involved in cardiovascular diseases offer great opportunities to improve cardiovascular treatment through their imaging and drug delivery capabilit...

In this study, the response of solid tumors implanted in rat hindlimbs to doxorubicin (DOX) released locally from a novel polymer-modified thermosensitive liposome (pTSL) was investigated. The pTSL was engineered to release encapsulated DOX at lower thermal doses than traditional thermosensitive liposomes. Rat mammary adenocarcinoma cells were impl...

In this study, the relationship between backscatter coefficient (BSC) and the size of Ultrasound Contrast Agents (UCAs) microbubbles has been investigated in vitro. Monodisperse lipid-coated microbubbles were produced using a flow-focusing microfluidic device. A single-element unfocused transducer with center frequency 2.25 MHz was used to measure...

Incidence of intra-cranial hemorrhage linked to treatment of ischemic stroke with recombinant tissue plasminogen activator (rt-PA) has led to interest in adjuvant therapies such as ultrasound (US) or plasminogen, to enhance rt-PA efficacy and improve patient safety. High-frequency US (∼MHz) such as 2-MHz transcranial Doppler (TCD) has demonstrated...

Ultrasound contrast agents (UCAs) are used clinically to aid detection and diagnosis of abnormal blood flow or perfusion. Characterization of UCAs can aid in the optimization of ultrasound parameters for enhanced image contrast. In this study echogenic liposomes (ELIPs) were characterized acoustically by measuring the frequency-dependent attenuatio...

Phase‐shift nanoemulsion (PSNE) consists of dodecafluoropentane nanodroplets stabilized with phospholipid monolayer shell. These nanodroplets are pressure sensitive and can be vaporized into gas bubbles by a short ultrasound pulse (t<50 ms), provided the pressure exceeds a well‐defined threshold. This property provides means of on‐site and on‐deman...

At the dawn of a new era in medicine, the future of biomedical acoustics is bright. In the last century, we witnessed the introduction of ultrasound contrast agents, lithotripsy, and the visualization of ultrasound images in three dimensions. Currently, scientists are developing acoustic-based techniques for opening the blood-brain barrier transien...

Acoustic techniques were employed to investigate the relationship between the mean size of monodispersions of lipid coated microbubbles and frequency dependent attenuation. Flow focusing microfluidic devices were constructed to produce several populations of monodisperse lipid coated microbubbles (i.e. with narrow size distribution). The mean diame...

In this study, a flow-focusing microfluidic device was used to prepare lipid-coated microbubbles with a narrow size distribution. Size-controlled monodisperse microbubbles have been successfully produced with mean diameters ranging from 3.4-12.5 μm. These bubble populations were suspended in an exposure chamber and attenuation coefficients were mea...

Phase-shift nanoemulsions have the potential to nucleate bubbles and enhance high-intensity focused ultrasound (HIFU) cancer therapy. This emulsion consists of albumin-coated dodecafluoropentane (DDFP) droplets with a mean diameter of approximately 260 nm at 37°C. It is known that superheated perfluorocarbon droplets can be vaporized with microseco...

A novel polymer-modified thermosensitive liposome (pTSL) was developed for the delivery of Doxorubicin (DOX) for cancer therapy. Copolymers containing temperature-responsive N-isopropylacrylamide (NIPAAm) and pH-responsive propylacrylic acid (PAA) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, yielding...

In this study, we demonstrate the feasibility of using a phase-shift nanoemulsion (PSNE) as nuclei for bubble-enhanced heating and lesion formation during high-intensity focused ultrasound (HIFU) thermal ablation. In our experiments, different concentrations of PSNE (5%-15%) uniformly distributed throughout gel phantoms made from acrylamide and alb...

Monodisperse populations of lipid‐coated microbubbles were produced using a flow‐focusing microfluidic device. The microbubbles were formed by forcing a lipid solution and perfluorocarbon gas through a narrow orifice simultaneously. The average bubble size depended on the lipid solution flow rate, the gas pressure, and the size of the inlet microch...

It has been demonstrated that cavitating bubbles can increase the heating rate during HIFU thermal ablation. We are developing a pressure‐sensitive phase‐shift nanoemulsion (PSNE) to nucleate acoustic cavitation in a controlled manner. In this study, we demonstrate the ability to nucleate cavitation with PSNE dispersed throughout acrylamide gels. T...

In this paper, we describe a technique for producing populations of ultrasound contrast agents (UCA) with a narrow size distribution. Using acoustic techniques, we measure the frequency-dependent attenuation coefficient for suspensions of ultrasound contrast agents with varying size distributions, ranging from narrow to wide. Our results demonstrat...

Echogenic liposomes (ELIPs) are being developed for use as ultrasonic contrast agents and as drug carriers for ultrasound-targeted drug delivery. Physical and acoustical characterization of ELIPs is necessary in order to determine the optimum parameters for diagnostic and therapeutic applications. In this study, ELIP samples at concentrations of 10...

Focused ultrasound surgery (FUS) is a noninvasive medical treatment for solid tumors by using ultrasound-mediated hyperthermia. The objectives of this study are to develop and characterize a submicron agent to yield higher thermal doses and eventual lead to a more efficient FUS protocol. The submicron agent, named as phase shift nano-emulsion (PSNE...

A major component of harbor mud is the clay mineral kaolinite, Al(2)Si(2)O(5)(OH)(4). Isomorphous substitution, Al atoms occasionally replacing Si atoms, causes a net positive charge of roughly one electronic charge per 400 Si atoms. Kaolinite platelets have diameters and thicknesses of the order of 1 mum and 20 nm. The platelet's positive charge i...

Acoustic cavitation has proven to be important for several therapeutic applications of ultrasound. However, acoustic cavitation is difficult to initiate and sustain in the absence of cavitation nuclei, particularly in tissue. Phase shift emulsions are ideal candidates for cavitation nuclei for in vivo applications. These emulsions, which consist of...

Echogenic liposomes (ELIP) are submicron-sized phospholipid vesicles that contain both gas and fluid. With antibody conjugation and drug incorporation, these liposomes can be used as novel targeted diagnostic and therapeutic ultrasound contrast agents. The utility of liposomes for contrast depends upon their stability in an acoustic field, whereas...

The purpose of this study was to identify the pressure threshold for the destruction of Optison (octafluoropropane contrast agent; Amersham Health, Princeton, NJ) using a laboratory-assembled 3.5-MHz pulsed ultrasound system and a clinical diagnostic ultrasound scanner. A 3.5-MHz focused transducer and a linear array with a center frequency of 6.9...

A video microscopy technique was developed to monitor the lytic activity of recombinant tissue plasminogen activator (rt‐PA) in combination with 2‐MHz transcranial Dopplerultrasound (TCD). Human whole blood clots formed on silk sutures were treated with TCD pulses alone [pulse length=10 cycles, pulse repetition frequency (PRF)=10.5 kHz, P neg=0.18−...

Pulsed ultrasound, when used as an adjuvant to recombinant tissue plasminogen activator (rt-PA), has been shown to enhance thrombolysis in the laboratory as well as in clinical trials for the treatment of ischemic stroke. The exact mechanism of this enhancement has not yet been elucidated. In this work, stable and inertial cavitation (SC and IC) ar...

This study was performed to identify the affect of variations in the surface activity of the polymer poly(propylacrylic acid) (PPAA) on cavitation-induced hemolysis. The surface activity of PPAA was varied by changing the molecular weight (MW 1=43 kDa and MW 2=60 kDa) and the solution pH (pH=5.0, 6.1, and 7.4). Acoustic energy was delivered with a...

Liposomes are submicron‐sized phospholipid vehicles that contain both gas and fluid. Entrapped microbubbles within the liposome cause them to be echogenic. With antibody conjugation and thrombolytic drug incorporation, such as rt‐PA, these liposomes can be used as novel targeted diagnostic ultrasound echo contrast agents to deliver a drug locally....

Echogenic liposomes (ELIP) are vesicles with a phospholipid bilayer shell that can serve as ultrasound contrast agents (UCA) for diagnostic purposes and for targeted drug delivery. The efficacy of ELIP as an UCA depends upon its stability in an acoustic field, whereas the use of ELIP for drug delivery will require releasing the encapsulated drug ra...

The persistence of acoustic cavitation in a pulsed wave ultrasound regime depends upon the ability of cavitation nuclei, i.e., bubbles, to survive the off time between pulses. Due to the dependence of bubble dissolution on surface tension, surface-active agents may affect the stability of bubbles against dissolution. In this study, measurements of...

Poly(propylacrylic acid) is a pH‐sensitive membrane disruptive polymer designed to release therapeutic molecules from endosomes to the cell cytoplasm before degradation. In mildly acidic environments, the polymer becomes more hydrophobic and less soluble in aqueous medium. Previous research has demonstrated the capacity of polyelectrolytes and ther...

A report on focused ultrasound and poly(2-ethylacrylic acid) (PEAA) acting synergistically to disrupt lipid bilayers in vitro was presented. It was noticed that focused ultrasound applied to red blood cells (RBC) in the presence of PEAA at pH 6.1 produced 60% hemolysis of 108 cells. The synergy between ultrasound and PEAA at pH = 6.1 occurred becau...