Tereshchenko A. Influence of biomolecules adsorption on the optical properties of TiO2 nanostructured films

The dissertation is devoted to the study of the influence of biomolecules adsorption on the examples of the bovine leukemia virus gp51 immune complex proteins and porphyrin to the optical properties of nanostructured TiO2 films, as well as to the establishment of correlation mechanism between optical and adsorption characteristics of TiO2. In this regard, a comprehensive study of the optical, structural and adsorption properties of nanostructured TiO2 films has been carried out. The regularities of interaction of TiO2 with biological objects and their influence to the optical properties of TiO2 are determined. The main aspects of the interaction mechanism between TiO2 nanoparticles and biomolecules are established: the main reason of the changes in the photoluminescence spectra of TiO2 as a result of gp51 proteins adsorption on the TiO2 surface is the electrostatic interaction between the surface negative charge TiO2 and the positive partial charges of the gp51 proteins. It is also shown that the structure of TiO2/gp51 immunosensor can be interpreted as a model based on a imaginary flat capasitor, which is formed due to the charge distribution at TiO2/gp51 interphase as a result of the immobilization of gp51 protein. It is proved that the effects of the displacement of the TiO2 photoluminescence maximum and the fact of its adsorption sensitivity towards antigens anti-gp51 are determined by barrier effects, i.e. by changing of the TiO2 surface potential barrier as a result of the adsorption of gp51 and its subsequent reduction after the interaction of TiO2/gp51 with anti-gp51. An optical biosensor prototype based on porphyrin-modified TiO2 nanostructured films for determination of valine amino acid has been developed. A complex analysis of recombination transitions was carried out taking into account the influence of surface charge and adsorption of biomolecules on the surface of TiO2.