Influence of nesting shell size on brightness longevity and resistance to ultrasound-induced dissolution during enhanced B-mode contrast imaging

Wallace, Nicole; Dicker, Stephen; Lewin, Peter A.; Wrenn, Steven P.

doi:10.1016/j.ultras.2014.06.019

Cited by 11 publications

(8 citation statements)

References 37 publications

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“…This is consistent with increased activity found in other nested microbubble formulations for a decrease in microbubble concentration [22].…”

Section: Resultssupporting

confidence: 90%

“…The average liposome diameters for each homogenizing speed are the same order of magnitude owing to fact that the speed does not have as large of an effect on the flexible membrane as it would with a stiffer polymer shell used for imaging purposes (see [22]). A Beckmann-Coulter Z1 Particle Counter (Beckmann-Coulter, Brea, CA) was used to confirm that when using the same amount of material during synthesis, the number of nested microbubbles increases with homogenizer speed.…”

Section: Variation Of Homogenizer Speed During Formulationmentioning

confidence: 99%

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Ultrasound triggered drug delivery with liposomal nested microbubbles

Wallace

Wrenn

2015

Ultrasonics

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When ultrasound contrast agent microbubbles are nested within a liposome, damage to the liposome membrane caused by both stable and inertial cavitation of the microbubble allows for release of the aqueous core of the liposome. Triggered release was not accomplished unless microbubbles were present within the liposome. Leakage was tested using fluorescence assays developed specifically for this drug delivery vehicle and qualitative measurements using an optical microscope. These studies were done using a 1 MHz focused ultrasound transducer while varying parameters including peak negative ultrasound pressure, average liposome diameter, and microbubble concentration. Two regimes exist for membrane disruption caused by cavitating microbubbles. A faster release rate, as well as permanent membrane damage are seen for samples exposed to high pressure (2.1-3.7 MPa). A slower release rate and dilation/temporary poration are characteristic of stable cavitation for low pressure studies (0.54-1.7 MPa).

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“…This is consistent with increased activity found in other nested microbubble formulations for a decrease in microbubble concentration [22].…”

Section: Resultssupporting

confidence: 90%

Section: Variation Of Homogenizer Speed During Formulationmentioning

confidence: 99%

Ultrasound triggered drug delivery with liposomal nested microbubbles

Wallace

Wrenn

2015

Ultrasonics

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“…Furthermore, the nested configuration enables simultaneous targeted imaging and drug delivery without sacrificing drug‐carrying capacity. For improved UCA, Wallace et al [ 115 ] investigated the use and feasibility of phospholipid‐encapsulated MBs nested within the water core of polymer MBs. The nested formula provides comparable contrast to the traditional formula with at least nine times longer contrast duration.…”

Section: Strategies Of Dds Based On Nbsmentioning

confidence: 99%

Drug delivery system based on nanobubbles

Jin

Yang

Chen

et al. 2022

Interdisciplinary Materials

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Ultrasound (US) medical technology is widely used due to its advantages of safety, speed, and low cost. With the rapid development of biomedical nanotechnology, micro/nanobubbles, as US contrast agents, are not only valuable in US imaging diagnosis but also show broad application prospects in drug delivery. Nanobubbles (NBs) have more advantages as drug delivery systems (DDSs) due to their smaller size and longer circulation time compared with microbubbles. In this review, the fundamentals of NBs, including classification, stability mechanism, and preparation methods are summarized.Then, the strategies of a DDS based on NBs, including direct delivery, codelivery, target delivery, and stimuli-responsive delivery are reviewed and discussed. The three main applications of NBs-based DDSs, namely tumor theranostics, brain drug delivery, and vascular disease theranostics were highlighted. The challenges and future directions of the NBs-based DDSs are also considered and discussed.

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“…The mechanism of encapsulation is not well understood. 3,5 The success of double emulsion processes of this kind has been shown to depend upon the presence of a particular triglyceride (TG), namely triolein (TO), which consists of three monounsaturated 18-carbon chains connected to a glycerol backbone. 6 This TO-dependence is previously unexplained.…”

Section: Introductionmentioning

confidence: 99%

Triglycerides Stabilize Water/Organic Interfaces of Changing Area via Conformational Flexibility

Kinard,

Wrenn

2024

Langmuir

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The role of triglycerides (TGs) in both natural and synthetic biological membranes has long been the subject of study, involving metabolism, disease, and colloidal synthesis. TGs have been found to be critical components for successful liposomal encapsulation via a water/oil/water double emulsion, which this work endeavors to explain. TGs can occupy multiple positions in biological membranes. The glycerol backbone can reside at the water/organic interface, adjacent to phospholipid headgroups ("m" conformation), typically with relatively low (<3%) solubility. The glycerol backbone can also occupy hydrophobic regions, where it is isolated from water ("h" or "oil" conformation). This can occur in either midmembrane positions or phospholipid-coated lipid droplets (LDs). These conformations can be distinguished using 13 C-nuclear magnetic resonance spectroscopy (NMR), which determines the degree of hydration of the TG backbone. Using this method, it was revealed that TGs transition from "m" to "h" conformation as the organic solvent is removed via evaporation. A new transitional TG backbone position has been identified with a level of hydration between "m" and "h". These results suggest that TGs can temporarily coat and stabilize the large water/organic interfaces present after emulsification. As the organic solvent is removed and interfaces shrink, the TGs recede into midmembrane spaces or bud off into LDs, which are confirmed via transmission electron microscopy (TEM) and can be removed via centrifugation. Encapsulation efficiency is found to be inversely related to both the saturation and length of the TG acyl chains, indicating that membrane fluidization is a key property arising from the presence of TGs. Beyond clarification of a mechanism for high-efficiency liposomal encapsulation, these results implicate TGs as components that are able to stabilize biological membrane transitions involving a changing interfacial area and curvature. This role for TGs may be of use in the formulation of drug delivery systems as well as in the investigation of membrane transitions in life sciences.

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Influence of nesting shell size on brightness longevity and resistance to ultrasound-induced dissolution during enhanced B-mode contrast imaging

Cited by 11 publications

References 37 publications

Ultrasound triggered drug delivery with liposomal nested microbubbles

Ultrasound triggered drug delivery with liposomal nested microbubbles

Drug delivery system based on nanobubbles

Triglycerides Stabilize Water/Organic Interfaces of Changing Area via Conformational Flexibility

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