Particle Size Distribution in DMPC Vesicles Solutions Undergoing Different Sonication Times

Abstract

Size distribution of dimyristoylphosphatidylcholine liposome suspensions was investigated by dynamic-light scattering (DLS) as a function of the sonication time (t(s)). Cumulant expansion (second- and third-order) and regularized Laplace inversion (CONTIN) of dynamic single-angle laser light-scattering data were performed. With both methods, the intensity-weighted mean hydrodynamic radius r(I) depended on the investigated lengthscale. The number-weighted mean hydrodynamic radius (r(N)), obtained from CONTIN by modeling dimyristoylphosphatidylcholine vesicles as thin-walled hollow spheres, resulted as independent on the lengthscale. However, the r(N) value obtained from cumulant expansions remained lengthscale-dependent. Therefore, the number-weighted radius distribution function is highly asymmetric. The number-weighted mean radius, the standard deviation, and the number-weighted radius at the peak (r(N)(peak)) all decreased to a plateau when increasing sonication time. At t(s) longer than 1 h, the r(N)(peak) compares well with the radius of unilamellar vesicles in equilibrium with monomers predicted on a thermodynamic basis. The reliability of our analysis is proved by the comparison of experimental Rayleigh ratios with simulated ones, using the normalized number-weighted radius distribution function p(N)(r) determined by DLS data. A perfect agreement was obtained at longer sonication times, and the average aggregation number was determined. At lower t(s) values, simulations did not match experimental data, and this discrepancy was ascribed to the presence of large and floppy unilamellar vesicles with ellipsoidal shapes. Our investigation shows that, from single-angle DLS data, the radius distribution function of the vesicles can only be obtained if p(N)(r) is known.

Supported Lipid Bilayer on Nanocrystalline Diamond: Dual Optical and Field‐Effect Sensor for Membrane Disruption

“…Small unilamellar vesicles (SUVs) were obtained by sonicating the lipid suspension for 15 minutes with a bath-type sonicator (Transsonic 460/H from Elma) operated under a power of 170 W. This method gave a particle size distribution between 25 nm and 30 nm. [30,31] The solution of lipid vesicles was then incubated with the clean diamond samples for 2 hours at 60 8C to form an intact bilayer on the surface, after which excess vesicles in the bulk were removed by rinsing with de-ionized water. 0.5% and 0.0025% of Rho-PE was mixed with the lipid mixture for FRAP and FCS measurements, respectively.…”

Effect of Sonication on Polymeric Aggregates Formed by Poly(ethylene oxide)‐Based Amphiphilic Block Copolymers

“…[2][3][4][5][6] For polymeric aggregates, the effect of sonication has been scarcely and fragmentally studied. [2,[5][6] Kataoka and coworkers [2] found that poly(ethylene oxide)-block-poly(amino acid) block copolymers, after dialysis from organic solvent to water, formed large associates of polymeric micelles, which could be separated into well-dispersed micelles by the aid of sonication.…”

Selective Deposition of Lipid Membranes on Locally Anodic-Oxidized Silicon Surface

“…Vesicles were assembled by stirring the lipid solution and then small unilamellar vesicles were prepared by mild sonication using a bath-type sonicator. The size of vesicles is estimated to be about 10-50 nm from the reported experimental results using similar conditions [28]. To accelerate the vesicle rupture on the substrate surface, the lipid solution temperature was kept at 60…”