Formation and regulation of fullerene-incorporation in liposomes under the phase transition temperature

Abstract

The fullerene-exchange reaction from a cyclodextrin cavity to liposomes represents one of the best methods to prepare lipid membrane-incorporated [70]fullerenes (C₇₀). The C₇₀-exchange reaction occurred completely at temperatures above the phase transition temperature (T_m) of the liposomes; however, lowering the temperature to below the T_m led to C₇₀ aggregation outside the liposomes. This observation has limited the development of more functional LMIC₇₀ using a variety of liposome compositions. In this paper, this reaction was found to occur efficiently by the addition of small amounts of lipids bearing a π-moiety. The π-moieties act as a gate when hydrophobic C₇₀ migrates into the hydrophilic liposome surface. Therefore, the π-moieties should exist in the polar head groups of the lipids and the C₇₀-exchange reaction can be controlled by pH.