In order to gain the insights into the molecular interactions between liposomes and AAO membranes, we first investigated the influence of surface charge of liposomes on the immobilization into AAO membranes. Liposomes with neutral and cationic surface were newly prepared by tuning the lipid composition (cf. Experimental section and Supporting information, Figure ). The immobilized amount of these liposomes, determined by the fluorescence analysis of the supernatant, was compared with that of the anionic liposomes. The largest immobilization efficiency of liposomes was observed for cationic liposomes among them (83%, Figure ). The immobilized amount of neutral liposomes was 26% (Figure ), which was comparable to that of anionic ones (18%, cf. Figure ). Together with the negatively charged property of AAO pore surface, the results show that electrostatic interaction favorably works for cationic liposomes. Electrostatic repulsion, on the other hand, occurs for anionic liposomes, which is consistent with the observation that their immobilization efficiency is enhanced as increasing NaCl concentration in the buffer (Figure ). Collectively, anionic liposomes used in the above section were immobilized into the AAO pores despite electrostatic repulsion. It is thus highly likely that the immobilization proceeds via ion-exchange reaction between phospholipids and surface hydroxyl groups on AAO pore, as observed for the interaction with phosphate group-carrying small molecules and oligopeptides. This is supported by the observation that phosphate buffer competes the immobilization of model liposomes (data not shown).