The interaction of sonochemically synthesized gold nanoparticles with serum albumins

Spherical gold nanoparticles of approximately 16 nm were synthesized using a sonochemical reduction method and characterized using UV–vis spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The binding of these gold nanoparticles with bovine serum albumin (BSA) and human serum albumin (HSA) was investigated using UV–vis absorption and fluorescence spectroscopic techniques. A strong quenching of the fluorescence from serum albumins was observed due to the formation of a ground state complex with gold nanoparticles (static quenching). The fluorescence quenching constants, number of binding sites and binding constants were determined using Stern–Volmer and Benesi–Hildebrand plots. Using Forster Resonance Energy Transfer (FRET) theory, the distance between the donor (serum albumins) and acceptor (gold nanoparticles) was obtained, which showed that HSA has more affinity towards sonochemically synthesized gold nanoparticles compared to gold nanoparticles synthesized using other methods.