Gold nanoparticles (AuNPs) have attracted a great deal of attention in many fields of biology and medicine, due to their potential applications in drug release, targeted drug delivery, and photo-thermal therapy. Here, we study the interactions of the side-chain methyl group of alanine peptide residue with gold nanocluster (Au_nNCs, n = 2 to 10) and different shapes of AuNPs. The cyclo alanine dipeptide, c(AA), has been chosen as a protein model to elucidate the effect of (CH₃−) group along with the most repetitive moiety in a protein, the peptide backbone on that interaction. The binding energies and the complexation behavior of the Au_nNCs−c(AA) complexes were studied by density-functional theory (DFT), atoms-in-molecules theory (AIM), and natural bond orbital analysis (NBO) in gas phase and water implicit solvent. The adsorption of c(AA) on 3 nm AuNPs surface with different shapes was studied by Monte Carlo simulation. The studied AuNPs shapes were sphere, simple box, cylinder, and cone. The interaction of c(AA) and 3 nm sphere-AuNP in water explicitly was also investigated with molecular dynamics simulation. Such studies provide quantitative and qualitative information that helps us to understand the AuNP-protein interactions.

金纳米颗粒（AuNPs）由于其在药物释放，靶向药物递送和光热疗法中的潜在应用，已在生物学和医学的许多领域引起了广泛关注。在这里，我们研究了丙氨酸肽残基的侧链甲基与金纳米簇（Au _n NCs，n  = 2至10）和不同形状的AuNPs的相互作用。已选择环丙氨酸二肽c（AA）作为蛋白质模型，以阐明（CH _3-）基团以及蛋白质中最重复的部分，即该相互作用的肽骨架，的作用。Au _n NCs- c的结合能和络合行为（AA）配合物通过密度泛函理论（DFT），分子内原子理论（AIM）和气相和水隐含溶剂中的自然键轨道分析（NBO）进行了研究。通过蒙特卡罗模拟研究了c（AA）在3 nm AuNPs表面上的吸附形状。研究的AuNPs形状为球形，简单盒子，圆柱体和圆锥体。还使用分子动力学模拟研究了c（AA）与3 nm球形AuNP在水中的相互作用。这些研究提供了定量和定性的信息，有助于我们了解AuNP-蛋白质的相互作用。