Study On The Interaction Of Nano-TiO₂ And Its Composites With Three Proteins

Objective: Nano-Ti O2 and its composites, including nano-Ti O2/Si O2, nano-Ti O2/Fe3O4, and nano-Ti O2/FA were selected as research. Lysozyme(LYSO), Bovine hemoglobin(BHb), γ-globulin were used as model proteins. Study the interaction of nano-Ti O2 and its composites with three proteins by using spectroscopic methods, Zeta potential method and turbidimetric method under simulation physiological condition, the toxicity on three proteins were explored simultaneously.Methods: The changes of the UV absorbance before and after the interaction between nano-Ti O2 with its composites and three proteins were studied by the ultraviolet difference spectra. Their interaction mechanism, correlating parameters and the type of interaction force were obtained by the fluorescence spectroscopy. The effect of nano-Ti O2 and its composites on the conformation of three proteins were investigated by the synchronous fluorescence spectra. The changes of secondary structure of LYSO before and after the interaction with nano-Ti O2 and its composites were further studied by the circular dichroism. The conventional turbidimetric method was used to determine the lysozyme activity in the presence of nano-Ti O2 and its composites. The change of surface charge after interaction of nano-Ti O2 and its composites with LYSO and γ-globulin was measured by Zeta potential method.Results:The result of ultraviolet difference spectra initially revealed that nano-Ti O2 and its composites could interact with three proteins. Fluorescence spectra furtherly indicated that the nano-Ti O2 and its composites combined three proteins firmly, and intrinsic fluorescence of three proteins had been significantly quenched by nano-Ti O2 and its composites, the mechanism of fluorescence quenching were static quenching. The major driving forces of interaction nano-Ti O2/Si O2 with lysozyme was electrostatic, the rest of nano-particles and proteins were hydrogen bond and Van der Waals. The 1:1 ground state compounds were formed between the nanoparticles and three proteins. The strength of force was different between nano-Ti O2 with its composites and three proteins. For lysozyme, the order of force strength was Ti O2/FA>Ti O2/Si O2>Ti O2/Fe3O4>Ti O2; for bovine hemoglobin, the order was Ti O2/FA>Ti O2/Si O2>Ti O2>Ti O2/Fe3O4; for γ-globulin, the order was Ti O2/FA>Ti O2>Ti O2/Si O2>Ti O2/Fe3O4. The result of synchronous fluorescence spectra demonstrated that the conformations of three proteins were changed differently by nano-Ti O2 and its composites. The result of circular dichroism indicated that nano-Ti O2 and its composites had an impact on the secondary structure of LYSO. The turbidmetry proved that the activity of lysozyme was inhibited by nano-Ti O2 and its composites, the order of the inhibitory effect was Ti O2/FA>Ti O2/Si O2>Ti O2/Fe3O4>Ti O2. The results of Zeta potential showed that nano-Ti O2 and its composites interact with lysozyme and γ-globulin, making them surface charge varying differently.Conclusions: Nano-Ti O2 and its composites could interact with three proteins. The conformations of three proteins were changed differently by nano-Ti O2 and its composites.