Photoinduced interaction of colloidal TiO2 nanoparticles with lysozyme: Evidences from spectroscopic studies

The interaction between colloidal TiO2 nanoparticles and lysozyme (LYSO) was studied using absorption, steady state and time resolved fluorescence, FT-IR and synchronous fluorescence spectroscopic measurements. The apparent association constant has been deduced from the absorption spectral changes of LYSO–colloidal TiO2 nanoparticles using Benesi–Hildebrand equation. The number of binding sites and the apparent binding constant were calculated from relevant fluorescence data. Based on Forsterʹs non-radiation energy transfer theory, distance between the donor (LYSO) and the acceptor (TiO2) has also been calculated. The conformational changes of LYSO have been analyzed by means of FT-IR and synchronous fluorescence spectroscopy. In addition, the effect of metal ions on the binding constants of LYSO–TiO2 complex has also been discussed.