Gold Nanoparticles Surface Chemical Determines The Interaction With Protein

Protein is the fundamental material for all of the life processes,and all kinds of chemical reactions in biological systems are inseparable from the proteins.Therefore,there are none life activities without the proteins.Gold nanoparticles(AuNPs)have been widely applied in biology,chemistry,medicine,information science and the other fields because of their unique properties,such as small size effect,surface effect,optical effect,quantum effect and biocompatibility.In recent years,the related research of AuNPs has been paid especial attentions.As a drug and drug carrier,AuNPs can enter a physiological environment,and then its surface is immediately covered by a layer of proteins,forming what is known as the protein‘corona’.The protein‘corona’ gives AuNP a new biological identity that is distinct from its synthetic identity,altering its biological effects and toxicity.Therefore,the study on the interaction between AuNPs with different surface chemical properties and bovine serum albumin(BSA)has great significance to fully understand the impact factors for the formation of protein‘corona’and develop the safe and effective biological nanomaterials.As a part of the National Natural Science Foundation of China(Nos.21303043),In this paper,we selected BSA and AuNPs with different surface chemical properties as the research objects.The interaction between BSA and AuNPs with different surface chemical properties was studied by using UV-vis absorption spectroscopy,fluorescence spectroscopy,circular dichroism(CD),Fourier transform infrared spectroscopy(FTIR),dynamic light scattering(DLS)and transmission electron microscope(TEM)techniques.The results of fluorescence spectra and UV-vis absorption reveal the effects of the different surface chemical properties on the interaction mechanism of Au NPs with BSA.It is found that AuNPs modified with cysteine,glutathione,PEG(2K)and peptide interact with BSA to form the complexes,which indicates that the binding processes are a static quenching type.While the binding of Au NPs modified with polymer PEG(5K),PEG-COOH(5K)to BSA does not form complexes,which implies that these interactions may be dynamic quenching processes.The conformational changes of BSA were analyzed with synchronous fluorescence spectroscopy,CD and FTIR.The results demonstrate that the conformation of BSA does not change when AuNPs coated with PEG(5K)and peptide.However,Au NPs modified withcysteine,glutathione,PEG(2K),PEG-COOH(5K),CTAB have a great effect on the secondary structure of BSA.In addition,the results of DLS reveal the thickness of protein corona on AuNPs with the different surface chemical properties,which illustrates that the surface chemical properties of AuNPs have great influence on the thickness of protein corona.Finally,the effects of BSA on the aggregation behaviors of AuNPs with the different surface chemical properties were evaluated using UV-vis absorption spectroscopy.The results preliminarily indicate that the mainly impact factor on the aggregation behavior of AuNPs may be the surface charge.This work will provide an important references for the further understanding the interaction essence of nanomaterials with proteins and the biological effects of nanoparticles.