【作者】 李楠；

【导师】 赵宏康； 赵丽娜；

【作者基本信息】 北京理工大学 ， 凝聚态物理， 2016， 硕士

【摘要】 多肽保护的金团簇具有独特的物理化学性质,因而被广泛应用于生物感应、生物医药以及催化等诸多方向。研究发现,多肽保护层赋予了金纳米团簇生物相容性和特异性,而且多肽保护的金纳米团簇具有稳定的分子结构,因此体系才能够发挥其生物效应。在靶向药物的结构设计中,多肽保护金团簇的分子结构具有重要意义。而在多肽保护金团簇结构的研究中,氨基酸配体对金核的影响是氨基酸与金团簇界面上几何结构探究的根本性问题。目前,氨基酸与金核的相互作用机制尚不明确,我们对此问题的研究有助于理解构建多肽保护金团簇的机理。在本研究中,运用密度泛函理论计算的方法,探究一个氨基酸配体对Au₁₃核结构和特性的调制。由Au₁₃核的对称性穷举得到金核与氨基酸配体（Cys-Au-Cys）成键的邻位和对位两个位点,继而相应地构建出两种初始构型Iso1、Iso2。采用密度泛函理论的计算方法对简化的两个构型Au₁₃（Cys-Au-Cys）进行结构优化以及电子特性的计算,来探究Au₁₃核因受到一个氨基酸配体调制后的变化。几何优化结果表明,构型Iso1较构型Iso2更稳定。同时通过分析体系的RMSD得出,Iso1的金核比Iso2的金核发生了较为明显的形变。此外,体系的分子前线轨道计算结果表明,Au₁₃核决定了结构Au₁₃（Cys-Au-Cys）的紫外可见吸收光谱,因此与原始Au₁₃核的紫外可见吸收光谱相比,优化后构型发生了蓝移现象,并且随着Iso1金核的剧烈扭曲,其蓝移也更明显。总之,在一个氨基酸配体的调制下,Au₁₃核的原子结构和电子特性达到新的稳定状态。我们希望这能够为多肽保护金纳米团簇结构的搭建和设计提供理论基础。更多还原

【Abstract】 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.更多还原