Diffusion-controlled synthesis of gold nanoparticles: nano-liposomes as mass transfer barrier

Lipid vesicles and other types of amphiphilic materials are of great interest in the size-controlled synthesis of metal nanoparticles. In this study, we prepared nano-sized liposomes encapsulating tetrachloroauric acid for the facile synthesis of gold nanoparticles with controlled size over a range of 2–5 nm at room temperature. The semi-permeable character of the lipid membrane to the varying concentrations of reducing agent—sodium borohydride-regulated the particle formation kinetics. Diffusion of the reducing agent through the liposomal membrane in a controlled manner resulted in ultrasmall nanoparticles of a narrow size distribution with less aggregation as compared to the solution-based preparation method.