The influence of bile salts on the response of liposomes to ultrasound

Mujoo, Himang; Reynolds, John N. J.; Tucker, Ian G.

doi:10.3109/08982104.2015.1019515

Cited by 6 publications

(8 citation statements)

References 41 publications

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“…While extrusion generates shear forces that cause disruption of the lipid, Triton X is a non‐ionic surfactant that is commonly applied to disrupt lipid membranes . Of the 2 treatments, extrusion caused the greater increase in fluorescence compared to Triton X.…”

Section: Discussionmentioning

confidence: 99%

“…Liposomes were prepared using the thin film hydration method as described in an earlier publication . Lipid composition for liposomes included DSPC:Chol (87‐13 mol %) and DOPE:DSPC:Chol (30‐57‐13 mol %).…”

Section: Methodsmentioning

confidence: 99%

“…Lipid composition for liposomes included DSPC:Chol (87‐13 mol %) and DOPE:DSPC:Chol (30‐57‐13 mol %). DSPC (Tm: 55°C) was added as a lamellar lipid to promote the formation of liposomes, cholesterol to increase rigidity of the liposomal membrane and DOPE (Tm: ‐16°C) was added as a membrane destabiliser . The dried lipid film was hydrated with a medium containing FITC‐Dex (50 μg/mL) and QSY ® 9‐BSA (250 μg/mL) which was isosmotic with PBS.…”

Section: Methodsmentioning

confidence: 99%

“…Liposomes were prepared using the thin film hydration method as described in an earlier publication. 15 Size characterisation were performed before ultracentrifugation and in the resuspended pellet (after the second cycle). Also, DLS was used to determine the presence liposomes in the supernatant.…”

Section: Liposomal Studies 241 | Liposome Preparationmentioning

confidence: 99%

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A real‐time in vitro assay to evaluate the release of macromolecules from liposomes

Mujoo

Reynolds

Tucker

2017

Drug Testing and Analysis

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The availability of a real-time assay to experimentally investigate the release of encapsulated proteins would be beneficial given the interest in the use of liposomes as a drug delivery vehicle. Although simple assays for small molecular weight substances exist, assays to evaluate macromolecules do not. Here we describe a method that detects the release of model macromolecules from liposomes in real time. The assay employs the intermolecular distance-dependent phenomenon of fluorescence resonance energy transfer (FRET) between the fluorophore donor, fluorescein (FITC), and fluorescent quencher, QSY 9. The macromolecular species were conjugated to the markers fluorescein (44kDa dextran) and QSY 9 (67 kDa bovine serum albumin, BSA). Following confirmation of quenching between FITC-Dex and QSY 9-BSA, liposomes were loaded with the macromolecular markers and subjected to various treatments (high-pressure extrusion and Triton X solubilisation) to cause release from liposomes. An increase in FITC fluorescence was observed when liposomes were subjected to extrusion cycles. Surprisingly, the addition of Triton X did not cause an increase in fluorescence probably because the FRET pair became associated with mixed micelles. This assay method should be useful in studies to investigate the mechanisms by which macromolecules are released from liposomes, particularly when liposomes are exposed to release-triggers (eg, temperature change, pH change, ultrasound). Such understanding will underpin the formulation of triggered liposomal delivery systems for macromolecules.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Liposomal Studies 241 | Liposome Preparationmentioning

confidence: 99%

See 2 more Smart Citations

A real‐time in vitro assay to evaluate the release of macromolecules from liposomes

Mujoo

Reynolds

Tucker

2017

Drug Testing and Analysis

Self Cite

View full text Add to dashboard Cite

show abstract

“…They also found that liposomes made of taurocholate and DOPE showed less sensitivity to high frequency US than liposomes containing only DOPE. It was speculated that this phenomenon was because of a preferred shape arising from the combination of taurocholate and DOPE in the phospholipid bilayer [174].…”

Section: Ultrasound-responsivementioning

confidence: 99%

Stimulus-responsive liposomes as smart nanoplatforms for drug delivery applications

Zangabad

Mirkiani

Shahsavari

et al. 2017

Nanotechnology Reviews

120

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Liposomes are known to be promising nanoparticles (NPs) for drug delivery applications. Among different types of self-assembled NPs, liposomes stand out for their non-toxic nature, and their possession of dual hydrophilic-hydrophobic domains. Advantages of liposomes include the ability to solubilize hydrophobic drugs, the ability to incorporate different hydrophilic and lipophilic drugs at the same time, lessening the exposure of host organs to potentially toxic drugs and allowing modification of the surface by a variety of different chemical groups. This modification of the surface, or of the individual constituents, may be used to achieve two important goals. Firstly, ligands for active targeting can be attached that are recognized by cognate receptors over-expressed on the target cells of tissues. Secondly, modification can be used to impart a stimulus-responsive or "smart" character to the liposomes, whereby the cargo is released on demand only when certain internal stimuli (pH, reducing agents, specific enzymes) or external stimuli (light, magnetic field or ultrasound) are present. Here, we review the field of smart liposomes for drug delivery applications.

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Molecular Study of Ultrasound-Triggered Release of Fluorescein from Liposomes

et al. 2021

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Several investigations have suggested that ultrasound triggers the release of drugs encapsulated into liposomes at acoustic pressures low enough to avoid cavitation or high hyperthermia. However, the mechanism leading to this triggered release as well as the adequate composition of the liposome membrane remain unknown. Here, we investigate the ultrasound triggered release of fluorescein disodium salt encapsulated into liposomes made of 1,2-dioleoyl-sn-glycero-3-phosphocholi (DOPC) or 1,2-distearoylphosphatidylethanolamie (DSPC) lipids with various concentrations of cholesterol (from 0 to 44 mol%).The passive release of encapsulated fluorescein was first characterized. It was observed to be higher when the membrane is in a fluid phase and increased with temperature but decreased upon addition of cholesterol. Next, the release of fluorescein was measured at 1 different acoustic frequencies (0.8, 1.1, 3.3 MHz) and peak-to-peak pressures (0, 2, 2.5, 5, 8 MPa). Measurements were performed at temperatures where DOPC and DSPC liposomes were respectively in the fluid or gel phase. We found that the release rate did not depend on the ultrasound frequency. For DOPC liposomes, the ultrasoundtriggered release of fluorescein decreased with increasing concentration of cholesterol in liposomes, while the behavior was more complex for DSPC liposomes. Overall, the triggered release from DSPC liposomes was up to ten times less than DOPC liposomes.Molecular dynamics simulations performed on a pure DOPC membrane showed that a membrane experiences, under a directional pressure of ±2.4 MPa, various changes in properties such as the area per lipid (APL). An increase in APL was notably observed when the simulation box was laterally stretched or perpendicularly compressed, which was accompanied by an increase in the number of water molecules crossing the membrane. This suggests that ultrasound most probably enhances the diffusion of encapsulated molecules at small acoustic pressures by increasing the distance between lipids.

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The influence of bile salts on the response of liposomes to ultrasound

Abstract: Bile salts may be used to increase or decrease the sensitivity of liposomes to low frequency ultrasound.

Cited by 6 publications

References 41 publications

A real‐time in vitro assay to evaluate the release of macromolecules from liposomes

A real‐time in vitro assay to evaluate the release of macromolecules from liposomes

Stimulus-responsive liposomes as smart nanoplatforms for drug delivery applications

Molecular Study of Ultrasound-Triggered Release of Fluorescein from Liposomes

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