Evaluation of Tau Protein Interaction with Titanium Oxide Nanoparticles Using Fluoresecence Spectroscopy

INTRODUCTION: Due to the vast applications of nanoparticles in the medical field, as well as the production and targeting of biomolecules, studies on the properties of these particles are essential. Titanium oxide nanoparticles (TiO2 NPs) have antibacterial activity and are recognized as photocatalytic materials which are applied in drug delivery system. In this study, the interaction of TiO2 NPs with tau, as a protein model of the nervous system, was investigated by fluorescence spectroscopy. METHODS: The intrinsic fluorescence intensity of tau protein upon interaction with varying concentrations of TiO2 NPs (4–20 mM) was performed by exciting the protein sample (4 mM, phosphate buffer pH 7.4, 10 mM) at 270 nm, using a spectrofluorometer MPF-4 model at three different temperatures of 289, 310, and 315 K. RESULTS: After addition of varying concentrations of TiO2 NP, the fluorescence intensity of tau showed a continuous reduction around 305 nm. Also, it was observed that TiO2 NP effectively quenched tau protein fluorescence via static quenching mechanism, with association constants range from 6 × 107 M-1 to 3 × 107 M-1 at temperature range of 298–315 K. In addition, positive values of ΔSº and ΔHº indicated that the interaction of TiO2 with protein and subsequent complex formation is mediated by hydrophobic interactions. CONCLUSION: In brief, these results exhibit potential details regarding the structure alteration of tau in biological systems to design and decorate new medicinal agents using TiO2 NPs as potential applicant in biomedical and pharmaceutical applications.

Keywords:

Titanium Oxide Nanoparticle , Tau , Thermodynamic , Fluorescence Spectroscopy , Interaction