Comprehensive Multispectroscopic Analysis on the Interaction and Corona Formation of Human Serum Albumin with Gold/Silver Alloy Nanoparticles

In the present investigation, we have systernatically studied the binding-mechanism of model protein human serum albumin (HSA) with gold/silver alloy, nanoparticles (Au/Ag NPs) using multiple spectroscopic techniques. Absorption spectral studies of NPs in the presence of increasing concentrations of HSA resulted in a, slight red shift of the surface plasmon resonance band (SPR), if Au/Ag NPs, suggesting-, changes in the refractive index around the,nanoparticle surface owing to the adsorption of HSA. The results from high-resolution tratismission electron Microscopy (HR-TEM); dynamic light scattering (DLS), and zeta potential analysis substantiated the formation of a dense layer of HSA on the surface of Au/Ag NPs. The formation of a ground-state complex between HSA and Au/Ag NPs was evident from the outcome of the steady-state emission titration experiments of the HSA-Au/Ag NPs system. The binding parameters computed from corrected emission quenching data revealed that NSA exhibited a significant binding affinity toward Au/Ag NPs. The identical fluorescence lifetime values of NSA and HSA-Au/Ag NPs froth time-resolved fluorescence spectroscopic analysis further authenticated the findings of steady-state emission measurements. The formation of NSA corona on the Au/Ag NPs surface was established on the Bash of experimental quenching data and theoretical values. The occurrence of partial unfolding of HSA upon its interaction with the Au/Ag NPs Surface was established by Using an extrinsic fluotophore 1-anilino-8-naphthalenesulfonic acid (AS). Absotption, Fourier transform infrared (FT-IR), Raman, circular dichroism (CD); and excitation emission matrix (3D) spectral studies were also carried out to explore Au/Ag NPs-induced tertiary and secondary conformational changes of NSA. The influence of Au/Ag NPs on the esterase-like activity of NSA was established by probing the hydrolysis of p-nitrophenyl acetate.