Interaction and nanotoxic effect of TiO2 nanoparticle on fibrinogen by multi-spectroscopic method

Toxicological effects of nanoparticles (NPs) are still poorly documented while there are great demands for industrial applications and daily life. The aim of this study is to evaluate the influence of physicochemical characteristics on TiO2 NP toxicological effects toward protein. In order to better understand the physicochemical basis of the toxic of NP in industrial applications and under conditions of environmental exposure, we performed an array of photophysical measurements to quantify the interaction of TiO2 NP with protein. Fluorescence quenching, circular dichroism, dynamic light scattering and transmission electron microscopy measurements were performed on TiO2 NP having a diameter range from 10 to 35 nm in the performance of protein. We find that the TiO2 NP strongly associates with protein where the binding constant, as well as the degree of cooperativity of particle-protein binding, depends on particle size. We also find tentative evidence that the protein undergoes conformational change upon association with the NP. These results indicate that exposure to TiO2 NP may have an unfavorable effect on human health by inactivating functional proteins. (C) 2012 Elsevier B.V. All rights reserved.