Linking the physicochemical properties of calcined titania nanoparticles with their biocidal activity

Abstract

Titanium dioxide nanoparticles (nTiO2) show biocidal activity when exposed to UV illumination. Modification of their physical properties can expand their photoresponse region toward visible light. In this study, such modification was made through a sol-gel synthesis followed by calcination at a range of temperatures (250–900◦C), generating a series of nTiO2 particles with different crystal phases, sizes, porosities, zeta potentials, and BET surface areas. The unique properties of nTiO2 were linked to their toxicity to the marine bacterium, Vibrio fischeri. A modified “Flash” high-through put assay was used to test the viability of these marine organisms after short term (15–60 min) exposure under visible light only to the individual groups of nTiO2 (500–2000 µg/mL). Linear regression analysis indicated that across all concentrations and time points, high biocidal activity correlated with the amorphous and anatase crystal phases, high BET surface area, high pore volume and small crystal size. The linkage between physicochemistry and nanotoxicity would be helpful for future design of more efficient and sustainable nTiO2 .