Surface-modified TiO nanoparticles with ascorbic acid: Antioxidant properties and efficiency against DNA damage in vitro.

The antigenotoxic and antioxidative properties of surface-modified TiO nanoparticles (NPs) with ascorbic acid (AA) were compared with those of constituents (free AA and bare TiO NPs). Colloids consisting of the TiO NPs with anatase crystal structure were prepared by acidic hydrolysis of TiCl. The synthesized TiO NPs were characterized using transmission electron microscopy and X-ray diffraction analysis. The charge transfer (CT) complex formation between surface Ti atoms and AA is indicated by immediate appearance of red color. Composition and stability constants of CT complex were determined using Job's method and Banesi-Hildebrand analysis, respectively. The surface structure of CT complex was determined from infra-red spectra of free and bound AA to the surface Ti atoms. The experimental data were supported with quantum chemical calculations based on density functional theory (DFT). The antigenotoxic potential of CT complex was evaluated in leukocytes of whole blood cells in vitro by comet assay method. For evaluation of antioxidant properties, total antioxidant status (TAS) and total oxidant status (TOS) were determined in human serum pool in vitro. The presented results indicate that bare TiO NPs have more pronounced antigenotoxic effects in comparison with either surface-modified TiO NPs with AA or free AA. No significant differences between the antigenotoxic and antioxidative properties of free and bound AA on the TiO NPs were noticed in the investigated concentration range. It seems that surface-modified TiO NPs with AA and/or similar compounds can be used to maintain its beneficial activities.