DNA binding and dispersion activities of titanium dioxide nanoparticles with UV/vis spectrophotometry, fluorescence spectroscopy and physicochemical analysis at physiological temperature

Abstract

Overexposure of TiO2 NPs has raised concerns over safety. This study focuses on stability and DNA binding activity of TiO2 NPs in water and cell culture growth media RPMI-1640 at physiological temperature. Borosil Mansingh Survismeter was used to assess dispersion and physicochemical properties. Values of density, viscosity, surface tension, particle size, friccohesity and activation energy were calculated for a range of TiO2 NP concentrations (25μM/L to 125μM/L). The results demonstrate higher limiting density and viscosity in culture media than water, suggesting a stronger association of TiO2 NPs in growth media. Interaction of TiO2 NPs with human genomic DNA was analyzed by UV–visible spectroscopy and fluorescence spectroscopy. UV–visible spectroscopy showed hyperchromic effect due to strong stacking interactions between human genomic DNA and TiO2 NPs. Fluorescence spectral characteristics revealed that with increasing concentrations of TiO2 NPs bound to DNA, there was a marked decrease in fluorescence spectra which indicates interaction of TiO2 NP with human genomic DNA. Understanding structural and physicochemical properties of TiO2 NPs and their interaction with human genomic DNA will be important for in vitro genotoxicity studies as stability of nano form in media is a major concern.