Optical properties of gelatin/CdS bionanocomposite and its conformational change**

Tang Shi-hua; Li You-qun; Wang Jun; Wang Bai-yang

doi:10.3969/j.issn.2095-4344.2013.34.016

摘要： BACKGROUND:The properties, integration mechanism and conformation change of protein are closely related with the biological effects of nanocomposites. OBJECTIVE:To study the optical properties and integration mechanism of gelatin/CdS bionanocomposite, and to analyze the conformation change of gelatin macromolecule at pH 12.0. METHODS:The gelatin/CdS bionanocomposites were synthesized via one-pot chemical route with the materials of gelatin, cadmium acetate and Na 2 S?9H 2 O through adding the Cd2+and S2?solution into the gelatin dilute solution at the temperature of 296, 302 and 308 K, and with the concentration of 8×10?6-1.2×10?3 RESULTS AND CONCLUSION:Transmission electron microscopy images showed that the morphology of gelatin/CdS nanocomposites was mainly chain-shaped. The ultraviolet-visible spectroscopy showed that the gelatin/CdS nanocomposites band gap was decreased with the increasing in both the CdS concentration and temperature, and they showed an obvious quantum size effect. The dynamic light scattering showed that theζpotential was negative and decreased slightly with the increasing in concentration of CdS. The Fourier transform infrared spectroscopy showed that level ofα-helix andβ-sheets in gelatin macromolecular conformation was decreased and theβ-turns level was increased. The gelatin/Cd 2+complex and gelatin/CdS nanocomposites were formed on the basis of various observations, the most plausible mechanism is proposed for the integration of gelatin/CdS nanocomposites, which includes the coordination (Cd2+with the oxygen of carbonyl group in gelatin molecular chain), vulcanization and surface coated. The shape,ζpotential and optical properties of samples were characterized by transmission electron microscope, dynamic light scattering, X-ray diffraction, ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy.