Preparation and photo-induced activities of water-soluble amyloid β-C 60 complexes.

We have shown that fullerene (C 60 ) becomes soluble in water by mixing fullerene and amyloid β peptide (Aβ40) whose fibril structures are considered to be associated with Alzheimer's disease. The water-solubility of fullerene arises from the generation of a nanosized complex between fullerene and the monomer species of Aβ40 (Aβ40-C 60 ). The prepared Aβ40-C 60 exhibits photo-induced activity with visible light to induce the inhibition of Aβ40 fibrillation and the cytotoxicity for cultured HeLa cells. The observed photo-induced phenomena result from the generation of singlet oxygen via photoexcitation, inducing oxidative damage to Aβ40 and HeLa cells. The oxidized Aβ40 following photoexcitation of Aβ40-C 60 was confirmed by mass spectrometry.