Phospholipid asymmetry in biomimetic vesicles alters membrane permeability.

Artificial cell membranes are rarely able to capture a key structural component of biological cells, namely the asymmetric distribution of phospholipids in the inner and outer leaflets. Here we show a straightforward method for generating biomimetic asymmetric vesicles that mimic the composition of human red blood cells using a plug-and-play microfluidic device. Small molecule diffusion was compared between symmetric and asymmetric vesicles using quinine hemisulphate. Asymmetric vesicles showed an 85% lower permeability than symmetric vesicles, suggesting that asymmetry is an important, yet undervalued, consideration in the design of vesicles for a variety of applications from the fundamental study of drug-membrane interactions to the use of vesicles for drug delivery.