The Density Functional Theory Study On The Modulation Of Amino Acid Ligand To The Au Core Structure And Characteristics

Peptide coated Au nanoclusters have been widely used in many fields because of its unique physical and chemical properties,such as biosensing,biomedicine and catalysis.In these novel systems,the peptide coatings render Au NCs biocompatibility,and specificity property.The important biological effects of the peptide coated Au NCs stem from their stable molecular structures and the corresponding physicochemical properties.The molecular structures are for peptide coated Au NCs in their targeting agent designs.In the peptide-Au NC coupled molecular structure,the impact of amino acid ligand to the core of Au NC is the fundamental problem in geometry optimization of the Au core/amino acid interface.The interaction mechanism is helpful to understand the peptide coated Au NC construction which is still far from clear.In this study,we used density functional theory?DFT?to investigate the modulation of the structure and properties of an amino acid ligand to Au₁₃ core.We figured out two different bonding sites all over the Au₁₃ core with Oh point symmetry as the adjacent Au-Au site and the diagonal Au-Au site,therefore we could get two isomers of Au₁₃?Cys-Au-Cys?system as Iso1 and Iso2.To study the impact of Cys-Au-Cys ligand on the atomic structure of Au₁₃ core,we optimized the configuration and calculated the electronic properties by DFT calculations.The geometry optimization results show that the configuration of Iso1 is more stable than that of the Iso2.What's more,the core of Iso1 has more obvious deformation than Iso2 through the RMSD results.In addition,the frontier molecular orbital calculation results show that the Au core determines the UV-Vis absorption spectra of Au₁₃?Cys-Au-Cys?.Therefore,the peak absorption wavelength of Iso1 performs more blue shift than Iso2 compared with that of the original Au₁₃ core.We hope the fundamental knowledge could support the basic ideas for peptide coated Au NCs design and construction studies.