Comparison of Protein Binding and Fluorescence Quenching by Gold and Iron Oxide Nanoparticles: pH and Temperature Dependence

Analysis of protein binding affinity to nanoparticles is essential for understanding how nanoparticles behave in biological systems and for optimizing their applications in medicine and biotechnology. This study demonstrates the dependence of protein binding and fluorescence quenching constants (HEWL and BSA) in the presence of gold (AuNP) or iron oxide (IONP) nanoparticles on pH and temperature. The highest binding and quenching constants were observed for proteins with gold nanoparticles (~109 M−1). No clear effect of pH or temperature on either the binding or quenching constants of proteins with gold nanoparticles was detected. Conversely, different temperature trends were observed for the binding and quenching constants at different pH levels and for different proteins with iron oxide nanoparticles. It was shown that the nature of the nanoparticles has the strongest influence on their interactions with proteins, while the influence of environmental conditions can be considered secondary.