Liposome-Surface-Initiated ARGET ATRP: Surface Softness Generated by "Grafting from" Polymerization.

Liposomes are self-assembled vesicles of amphiphilic lipid molecules, which have been investigated as models of cells, or tools for drug delivery systems. In these systems, the surface property of the liposomes plays an important role. In this study, we demonstrated a novel polymer modification of liposome surfaces using a controlled radical polymerization, "activators regenerated by electron transfer for atom transfer radical polymerization", in aqueous media without a deoxygenation step. Dynamic light scattering and 1H NMR measurement indicated the successful modification of the polymer on the liposome surface. The molecular weight of the grafted polymer chain was systematically controlled by changing the monomer concentrations in the "grafting from" polymerization. Moreover, the modification resulted in a notable increase in surface softness as indicated by electrophoretic behavior, which was comparable to the surface of cells. The preparation method and the characterization presented in this study would be a helpful guideline in designing the polymer/liposome hybrid having target surface properties.