Solubilization of fullerene C60 in micellar solutions of different solubilizers.

Fullerene (C(60)), the third carbon allotrope, is a classical engineered material with the potential application in biomedicine. However, extremely high hydrophobicity of fullerene hampers its direct biomedical evaluation and application. In this work, we investigated the solubilization of fullerene using 9 different solubility enhancers: Tween 20, Tween 60, Tween 80, Triton X-100, PVP, polyoxyethylene (10) lauryl ether, n-dodecyl trimethylammonium chloride, myristyl trimethylammonium bromide and sodium dodecyl sulphate and evaluated its antioxidant activity in biorelevant media. The presence of C(60) entrapped in surfactant micelles was confirmed by UV/VIS spectrometry. The efficacy of each modifier was evaluated by chemometric analysis using experimental data for investigating the relationship between solubilization and particle size distribution. Hierarchical clustering and principal component analysis was applied and showed that non-ionic surfactants provide better solubilization efficacy (>85%). A correlation was established (r=0.975) between the degree of solubilization and the surfactant structure. This correlation may be used for prediction of C(60) solubilization with non-tested solubility modifiers. Since the main potential biomedical applications of fullerene are based on its free radical quenching ability, we tested the antioxidant potential of fullerene micellar solutions. Lipid peroxidation tests showed that the micellar solutions of fullerene with Triton and polyoxyethylene lauryl ether kept high radical scavenging activity, comparable to that of aqueous suspension of fullerene and BHT. The results of this work provide a platform for further solubilization and testing of pristine fullerene and its hydrophobic derivatives in a biological benign environment.