Promoting Fullerene Solubility

Fullerenes are touted for a variety of applications, including solar energy and medicine. But their uses are hampered by their limited solubility. One way around the problem is to derivatize the carbon cage. Another is to dissolve fullerenes in the lipid bilayer of artificial vesicles known as liposomes, an approach that is of particular interest for drug delivery. According to a new computational study, key factors promoting dissolution rather than aggregation of fullerenes in lipid membranes are lipid chain density and chain packing (Phys. Rev. Lett. 2014, DOI: 10.1103/physrevlett.112.068102). Jonathan Barnoud, Giulia Rossi, and Luca Monticelli of France’s National Institute of Health & Medical Research examined the thermodynamics of fullerene aggregation in phospholipid membranes as well as in three liquid alkanes. They found that entropy normally drives fullerenes to aggregate. In membranes, however, energy costs associated with solvent density and packing reduce aggregation. The results point to ways to promote dissolution of fullerenes by tuning the chemical composition of lipid bilayers, the researchers say.