Interaction Studies of Greenly Synthesized Gold Nanoparticles with Bovine Serum Albumin (BSA) Using Fluorescence Spectroscopy.

In the present study, gold nanoparticles (AuNPs) with an average particle size of -41.23 nm were synthesized using eco-friendly reducing material (i.e., aqueous Nelumbo nucifera root extract). Rapid reduction results in the formation of polydispersed nanoparticles. The formation of AuNPs was characterized by surface plasmon resonance (SPR) which was determined by UV-Vis spectra (band at 544 nm), FTIR, SEM-EDX, TEM, HR-TEM, and XRD. This study aims to investigate the interaction between AuNPs and Bovine Serum Albumin (BSA) using fluorescence spectroscopy. The analysis of fluorescence spectra and intensity at physiological pH in an aqueous solution indicates that AuNPs have a potent ability to quench the BSA fluorescence by both quenching mechanisms. Resonance light scattering spectra indicated the formation of BSA-AuNPs complex. The number of binding sites and binding constants were determined based on fluorescence quenching at different temperatures. The thermodynamic parameters were also calculated at various temperatures that indicate that hydrophobic forces are abundant in the AuNPs-BSA complex. Negative ΔG degrees values suggest that the binding process is spontaneous. Synchronous fluorescence spectra showed a blue shift and CD spectra showed an increase in a-helicity content which is an indication of increasing hydrophobicity.