Vesicle adsorption on SiO2 and TiO2: Dependence on vesicle size

Abstract

Kinetics of vesicle adsorption on ${\mathrm{SiO}}_2$ and ${\mathrm{TiO}}_2$ surfaces was investigated for vesicle sizes from 25 to 200 nm. On ${\mathrm{SiO}}_2,$ nonruptured vesicles are adsorbed up to a critical coverage, ${\Theta }_c,$ after which spontaneous rupture and bilayer formation occurs in qualitatively the same manner for all vesicle sizes. On ${\mathrm{TiO}}_2,$ adsorption of nonruptured vesicles continues up to saturation. A comparison between the kinetics at low coverages on ${\mathrm{SiO}}_2$ and ${\mathrm{TiO}}_2,$ where intact vesicles adsorb on both surfaces, reveals that the vesicles on ${\mathrm{SiO}}_2$ are more flattened than nonruptured vesicles adsorbed on ${\mathrm{TiO}}_2,$ indicating a stronger vesicle-surface interaction on ${\mathrm{SiO}}_2.$