Non-covalent complexes of polycationic/polyanionic fullerene C60 derivatives with cyanine dyes: spectral properties and superoxide generation under NIR light irradiation

Polycationic/polyanionic fullerene C60 derivatives and heptamethine cyanine dyes IR780, IR783, IR806, IR820 and piperazine-substituted derivative of IR780 dye form complexes through an electrostatic interaction in aqueous solutions. The fluorescence of the dye is strongly quenched in such complexes, and they efficiently generate superoxide anion-radical under near-infrared (NIR) irradiation due to the photoinduced electron transfer from the photoexcited dye to the fullerene core. The superoxide generation efficiency under NIR light irradiation increases 52 times for the IR783−(polycationic fullerene derivative) complex compared to the native dye. The demonstrated results show promising potential of such [cyanine dye]−fullerene structures as new NIR type I photosensitizers for the photodynamic therapy.