Antimicrobial Nonapeptide Leucinostatin A-Dependent Effects on the Physical Properties of Phospholipid Model Membranes

“…27 Also, the fact that it is hard to detect a clear transition in solution is not unexpected for lipid samples that are not made of pure components or that have additives such as cholesterol. 35 While the presence of Tween 80, mannitol, and even the drug in the vesicles would be expected to further broaden/shift the transition point, 27,[35][36][37][38][39][40] this effect could unfortunately not be demonstrated with this system. Note that in each of the tables, the actual stabilizing solution temperature near the nozzle is significantly lower than that of the water bath used to heat the medium.…”

Section: Effect Of Stabilizing Solution Temperaturementioning

confidence: 97%

Phospholipid-stabilized nanoparticles of cyclosporine a by rapid expansion from supercritical to aqueous solution

et al. 2004

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INTRODUCTIONThe purpose of this research was to form stable suspensions of submicron particles of cyclosporine A, a water-insoluble drug, by rapid expansion from supercritical to aqueous solution (RESAS). A solution of cyclosporine A in CO 2 was expanded into an aqueous solution containing phospholipid vesicles mixed with nonionic surfactants to provide stabilization against particle growth resulting from collisions in the expanding jet. The products were evaluated by measuring drug loading with high performance liquid chromatography (HPLC), particle sizing by dynamic light scattering (DLS), and particle morphology by transmission electron microscopy (TEM) and x-ray diffraction. The ability of the surfactant molecules to orient at the surface of the particles and provide steric stabilization could be manipulated by changing process variables including temperature and suspension concentration. Suspensions with high payloads (up to 54 mg/mL) could be achieved with a mean diameter of 500 nm and particle size distribution ranging from 40 to 920 nm. This size range is several hundred nanometers smaller than that produced by RESAS for particles stabilized by Tween 80 alone. The high drug payloads (~10 times greater than the equilibrium solubility), the small particle sizes, and the long-term stability make this process attractive for development.The often low bioavailability of water-insoluble drugs leads to poor pharmacokinetic performance in the body. Techniques to improve bioavailability in oral or parenteral applications of water-insoluble drugs include powder micronization, the formation of micron-and submicron-size dispersions, solubility enhancement in aqueous solution by addition of appropriate surfactants, organic solvents or buffers, or drug-carrier systems such as liposomes. The payloads for drugs in liposomes are often limited because of the low volume fraction of hydrophobic regions. 1 The use of surfactants or organic solvents in parenteral administration can lead to phlebitis, anaphylaxis, hypotension, or even vasodilation.

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“…More importantly, the biomembrane provides the structural integrity of cells against external stimulation, for instance, mechanical stress. The main phase transition temperature of a di-palmitoyl-phosphatidylcholine (DPPC) vesicle is at 41.5 C, where the DPPC bilayer transforms from ripple gel to liquid crystalline phase [13], [14]. It has been recently shown that the bending modulus of the DPPC bilayer is significantly changed when temperature has gone through [15].…”

Section: Introductionmentioning

confidence: 99%

Shape Recovery of an Optically Trapped Vesicle: Effect of Flow Velocity and Temperature

Foo

Chan²,

Liu³

2004

IEEE Trans.on Nanobioscience

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A new biophysical approach based on optical tweezers is developed to measure the time-dependent shape transformation and recovery of a single liposome, which is induced by the sudden stop of a moving liposome from various flow velocities at constant temperature. A simple viscoelastic model has been applied to correlate the temporal geometric parameter of the deformed liposome with a characteristic time constant, i.e., the ratio of membrane viscosity to elasticity. Our results show that membrane viscosity becomes dominant in governing the shape recovery rate when sample temperature goes beyond the main phase transition temperature of the phospholipid bilayer. More importantly, flow speed and vesicle size are demonstrated as key physical determinants for the shape recovery of liposome.

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Antimicrobial Nonapeptide Leucinostatin A-Dependent Effects on the Physical Properties of Phospholipid Model Membranes

Cited by 45 publications

References 50 publications

Liposomal delivery improves the growth-inhibitory and apoptotic activity of low doses of gemcitabine in multiple myeloma cancer cells

Liposomal delivery improves the growth-inhibitory and apoptotic activity of low doses of gemcitabine in multiple myeloma cancer cells

Phospholipid-stabilized nanoparticles of cyclosporine a by rapid expansion from supercritical to aqueous solution

Shape Recovery of an Optically Trapped Vesicle: Effect of Flow Velocity and Temperature

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