Water Solubilization of Fullerene Derivatives by β-(1,3-1,6)-D-Glucan and Their Photodynamic Activities toward Macrophages

Anionic and neutral fullerene derivatives were dissolved in water by using beta-(1,3-1,6)-D-glucan (beta-1,3-glucan) as a solubilizing agent. In the water-solubilized complexes, the concentrations of fullerene derivatives were approximate to 0.30 mm and the average particle sizes were approximate to 90 nm. The beta-1,3-glucan-complexed fullerene derivative with a carboxylic acid was found to have higher photodynamic activity toward macrophages under visible-light irradiation (lambda > 610 nm) than other beta-1,3-glucan-complexed fullerene derivatives. This result suggests that carboxylic acid moieties in the complex enhance the binding affinity with beta-1,3-glucan receptors on the surface of macrophages when the beta-1,3-glucan is recognized. In contrast, all beta-1,3-glucan-complexed fullerene derivatives showed no photodynamic activity toward HeLa cells under the same conditions.