C60 IN MODEL BIOLOGICAL-SYSTEMS - A VISIBLE-UV ABSORPTION STUDY OF SOLVENT-DEPENDENT PARAMETERS AND SOLUTE AGGREGATION

A study was made of the solubilization of C60 in various solvents and systems of biological interest, i.e., octanols, micelles, and liposomes, using visible-UV absorption spectroscopy as a diagnostic tool. The state of incorporation of C60 molecules in micellar and colloidal liposome solutions was monitored using a number of spectroscopic criteria of solute-solvent and solute-solute interactions based on comparison with spectra obtained in alkane and octanol solvents and from thin films of C60. Spectral red shifts and intensity modifications of C60 absorption and C60 aggregation are discussed in terms of environment-dependent physical parameters. The results indicate that C60 can be dispersed in micellar solutions of Triton X-100 and Triton X- 100 R-S, the fullerene molecules being localized in the inner hydrophobic part of the micelles. C60 was shown to be incorporated, mainly as aggregates, into phosphatidylcholine liposome colloidal solutions. It is concluded that micellar and liposome solutions can be prepared which could be used to transfer individual C60 molecules, or groups of molecules, to biological cells.