Thermodynamics Studies on the BSA Adsorption onto Zinc Oxide Surfaces with Different Morphologies

Zinc oxide(ZnO) materials with four different morphologies of were synthesized by polymer template method, which were ZnO nanoparticles (ZnO NPs), ZnO nanorods(ZnO NRs), ZnO nanosheets (ZnO NSs) and ZnO nanobeams(ZnO NBs), respectively. They were characterized by scanning electron microscopy (SEM), X-ray diffraction(XRD), energy dispersive spectroscopy(EDS). Fourier transform infrared spectra (FTIR) and circular dichroism spectra (CD) were used to analyse the adsorption of bovine serum albumin (BSA) layer onto ZnO. Adsorption of BSA onto ZnO was investigated under different temperatures, and the adsorption thermodynamics and interaction mechanisms were discussed. The results indicate that the isothermal adsorption of BSA can be described by the Langmuir and modified Langmuir adsorption models. With the increase of adsorption temperature, the quantity of BSA absorbed onto ZnO increased. Thermodynamic parameters( Delta G, Delta H, Delta S) show that adsorption processes of BSA onto ZnO were endothermic (Delta H>0) and spontaneous( Delta G<0) in nature. The adsorption behavior was controlled by electrostatic interaction and hydrogen bonding. The analysis shows that the ZnO NRs is better for BSA adsorption.