Synthesis and Characterization of TiO2 Nanoparticles: Applications in Research on the Interaction of Colloidal TiO2 with Human Serum Albumin by Fluorescence Spectroscopy

Titanium dioxide (TiO2) nanoparticles (NPs) are widely used as an important kind of biomaterials due to their large surface area, enhanced chemical reactivity and easy penetration into cells. Nano TiO2 with pure anatase phase was successfully prepared by solvothermal method. Its particle size was about 21 nm, while the larger specific surface area of TiO2 was 77.43 m2/g. The interaction of colloidal TiO2 with human serum albumin was studied by using absorption spectra and fluorescence spectra. The apparent binding constants (K) were 345.780 × 105, 4.376 × 105, 0.035 × 105 at 298, 303 and 308 K, respectively. In addition, the number of binding sites (n) was gradually decreased with the increase of temperature, which indicated that the quenching mechanism of albumin by colloidal TiO2 was static fluorescence quenching process. Based on fluorescence resonance energy transfer, the energy transfer efficiency (E) and critical transfer distance (r0) between donor (human serum albumin, HSA) and acceptor (colloidal TiO2) were calculated to be 0.862 and 6.244 nm, which suggested that non-radiative energy transfer occurred between TiO2 and HSA. Furthermore, the conformational changes of HSA were shown by synchronous fluorescence.