Green synthesis and physical characterization of Au nanoparticles and their interaction with bovine serum albumin

In this study, we used morin as a reducing agent for the synthesis of stable and nearly spherical Au nanoparticles (M–AuNPs), which were characterized by UV–vis, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The binding characteristics and molecular mechanism of the interaction between the M–AuNPs and bovine serum albumin (BSA) were explored by UV–vis absorbance, fluorescence spectroscopy, and circular dichroism spectra (CD). The results showed that the quenching mechanisms were based on static quenching. The thermodynamic parameters ΔG, ΔH and ΔS, suggested that the reaction was spontaneous, and mainly driven by electrostatic interactions. Site marker competitive displacement experiments indicated that MAuNPs bound with high affinity to site I (subdomain IIA) of BSA. Synchronous fluorescence and CD spectra demonstrated that BSA conformation was slightly altered in the presence of M–AuNPs. In addition, the effect of pH, temperature, morin quantity, and reaction time were investigated.