Visible light sensitized inactivation of MS-2 bacteriophage by a cationic amine-functionalized C60 derivative

Recently, we reported the successful synthesis of various hexakis C60 derivatives (i.e., C60 with six functional groups containing NH3+-, CO2H-, or OH-terminals) with enhanced stability in water for aqueous phase application (Lee et al., Environ. Sci. Technol. 2009, 43, pp 6604-6610). Among these newly synthesized C60 derivatives, the cationic hexakis C60 derivative with amine functionality, C60(CR2)6 (R=CO2(CH2)2NH3+CF3CO2-), was found to exhibit remarkable efficiency to inactivate Escherichia coli and MS-2 bacteriophage under UVA irradiation. Herein, we report that this amine-functionalized C60 derivative is also photoactive in response to visible light from both commercial fluorescence lamps and sunlight. Efficient production of 1O2, facile reaction of 1O2 with proteins in MS-2 phage capsid and electrostatic attraction between positively charged C60 derivative and negatively charged MS-2 phage collectively contributed to high efficiency of MS-2 phage inactivation in this photocatalytic disinfection system. The rate of 1O2 production was evaluated using a probe compound, furfuryl alcohol, and 1O2 CT (the product of 1O2 concentration and exposure time) required to achieve a target level of virus inactivation was quantitatively analyzed. The unique visible-light sensitized virucidal property makes this C60 derivative highly desirable for the development of sustainable disinfection strategies that do not require continuous chemical addition nor an external energy source other than ambient light.