Surface chemistry of gold nanoparticles determines interactions with bovine serum albumin

Protein coronas provide a novel technique for the bio identification of nanoparticles in physiological environments, to further elucidate the biological effects of nanoparticles in biomedical applications. Herein, we investigated the adsorption of bovine serum albumin (BSA) on gold nanoparticles (AuNPs) with different surface modifications (citrate, cysteine, polyethylene glycol (PEG), and cetyltrimethylammonium bromide (CTAB)) using UV-vis absorption spectroscopy, fluorescence spectroscopy, circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques. It was revealed that the binding of AuNPs modified with citrate, cysteine, PEG (2k), and CTAB to BSA, appeared to be of the static quenching type, with binding constants in the range of from 10⁸ to 10¹⁰ M^-1. We also found that the conformation of BSA underwent various changes upon association with the different AuNP surface modifications. In addition, the preliminary results indicated that the thicknesses of protein coronas and the aggregation behaviors of AuNPs were closely related to their surface properties. These findings offered important insights into the essence of the interactions between nanoparticles and proteins toward the development of safe and effective nanomaterials in biological systems.