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

The fullerene-exchange reaction from a cyclodextrin cavity to liposomes represents one of the best methods to prepare lipid membrane-incorporated [70]fullerenes (C(70)). The C(70)-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 C(70) aggregation outside the liposomes. This observation has limited the development of more functional LMIC(70) 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 C(70) migrates into the hydrophilic liposome surface. Therefore, the π-moieties should exist in the polar head groups of the lipids and the C(70)-exchange reaction can be controlled by pH.