Steady state, time resolved, and circular dichroism spectroscopic studies to reveal the nature of interactions of zinc oxide nanoparticles with transport protein bovine serum albumin and to monitor the possible protein conformational changes

In this paper, the interaction between bovine serum albumin (BSA) and zinc oxide (ZnO) nanoparticles was investigated by fluorescence quenching spectra, circular dichroism (CD), and synchronous spectra under physiological conditions. From the analysis of the steady state and time resolved fluorescence quenching of BSA in aqueous solution in presence of ZnO it was observed that the nature of the quenching is of static-type quenching. The Stern-Volmer quenching constant K-S at different temperatures were determined and the thermodynamic parameters Delta H, Delta G, and Delta S were computed. The experiment revealed that the electrostatic interaction was the predominant force in stabilizing the complex. The effect of ZnO on the conformation of BSA has been analyzed by synchronous spectra and CD spectrum. Although the observed results demonstrate some conformational changes in BSA in presence of ZnO nanoparticles, the secondary structure of BSA, predominantly of alpha-helix, is found to retain its identity.