Probing binding processes of HSA adsorbed on rGO-AgNCs surfaces using multispectroscopic techniques

Protein molecules tend to be adsorbed on the surfaces of nanoparticles, thereby easily forming nanoparticle protein corona (NPC). Herein, the foundational study of NPC formation of human serum albumin (HSA) absorbed on the surfaces of reduced graphene oxide sliver nanocomposites (rGO-AgNCs) was studied using UV–visible, fluorescence, and circular dichroism (CD) spectroscopy. When the rGO-AgNCs were added to the HSA solution, the adsorption spectra of HSA showed a slight blue shift, which indicated the formation of NPC. The fluorescence data revealed that the static quenching procedure was the main quenching mechanism. Also, Δ G θ  < 0 indicated that the absorption process was spontaneous in thermodynamics, and HSA tends to bind to the surfaces of the rGO-AgNCs. Furthermore, Δ H θ  < 0 and Δ S θ  < 0 suggested that the binding was an enthalpy-driven process, and the main forces were the van der Waals forces and hydrogen bonds. The results of the synchronous fluorescence, three-dimensional emission experiments, and the α -helix content decrement indicated that the rGO-AgNCs slightly altered the HSA conformation. The morphological investigation and analysis using scanning probe microscopy (SPM) demonstrated that the NPC was formed on the surfaces of rGO-AgNCs.