Photochemical and antimicrobial properties of novel C60 derivatives in aqueous systems.

Four novel hexakis C60 derivatives with varying functionalities were synthesized, and their photochemical properties and photodynamic disinfection efficiencies were quantitatively evaluated. All these C. derivatives generated O2 more efficiently than commercial multihydroxylated C60 (fullerol), as assessed by furfuryl alcohol consumption and electron paramagnetic resonance analysis. Despite significant agglomeration/aggregation in the aqueous phase to micrometer-sized particles, nanosecond laser flash photolysis showed that the lifetime of triplet state (a key intermediate for energy transfer responsible for (1)O2 production) was comparable to reported values for pristine C. in organic phase. As a result of facile (1)O2 production, the Co derivatives efficiently inactivated Escherichie coli and MS-2 bacteriophage. Cationic aminofullerene hexakis, which likely exerted electrostatic attraction, exhibited exceptionally rapid virus inactivation even compared to commercial nano-TiO2 photocatalyst These unique photodynamic, hydrophilic and cationic properties may be instrumental for the development of next generation photocatalysts for disinfection applications. The high ROS (reactive oxygen species) production activity and associated cytotoxicity are concerns for potential releases of functionalized Ca to the environment, and require careful assessment apart from other forms of C60 (e.g., nC60) that have been widely studied as model nanomaterials but behave differently.