Investigations on the complexation and binding mechanism of bovine serum albumin with Ag-doped TiO2 nanoparticles

Abstract

It is essential to study the interactions between nanoparticles and proteins to better understand the biological interactions of nanoparticles. In this study, we studied the protein adsorption mode on the surface of Ag-doped TiO₂ nanoparticles (NPs) using a model protein, bovine serum albumin (BSA). The mechanism of binding BSA to the Ag-doped TiO₂ NPs was studied by applying fluorescence quenching, absorbance measurements, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy techniques. The strong binding between BSA and Ag-doped TiO₂ NPs was confirmed by a high value of binding constant (K = 2.65 × 10⁵ L mol⁻¹). We also studied the thermal stability of BSA in the presence of the Ag-doped TiO₂ NPs. Thermodynamic parameters indicated that the adsorption of BSA on the Ag-doped TiO₂ NPs was a spontaneous, natural and exothermic process. The effect of Ag-doped TiO₂ NPs on the transportation function of BSA was also studied using a fluorescence spectroscopic technique. Fluorescence spectroscopic data suggested the existence of a strong interaction between BSA and the surface of the Ag-doped TiO₂ NPs, which indicated that the binding affinities of some selected amino acids in BSA changed. This, in turn, clearly confirms that the Ag-doped TiO₂ NPs affect the transportation capability of BSA in blood.