Interaction of graphene oxide with bovine serum albumin: A fluorescence quenching study

Fluorescence quenching was used to elucidate the binding interaction mechanism between bovine serum albumin (BSA) and graphene oxide (GO). By analyzing the values of Stern-Volmer quenching constant (K_SV) and binding constant (K_A) which were affected by temperature, we supposed that the quenching process between GO and BSA was mainly determined by static quenching, combined with dynamic quenching. The study of thermodynamics showed that the values of enthalpy change (∆H), entropy change (∆S) and Free Energy (∆G) were all negative, which implied that the weak interaction of the molecular between BSA and GO was Van der Waals interaction or hydrogen bond, and the quenching process was exothermic and spontaneous. The red shift in the synchronous fluorescence spectra suggested that the conformation of tryptophan was changed in the presence of GO. According to Förster's non-radiative energy transfer theory, the distance r between BSA (donor) and GO (acceptor) was calculated and indicated the occurrence of energy transfer from BSA to GO had high probability. The AFM observation and Raman spectroscopy revealed that the interaction between BSA and GO has occurred. Compared with other literatures, the explosion of surface topography about BSA and GO was paid more attention on in this study.