In this work, we study the interactions between gold nanocluster (Au n NCs, n = 2, 4, and 6) and D-penicillamine (DPA) anticancer drug by different computational methods to study the ability of Au n NCs to act as a nanocarrier for DPA for the first time. We calculated the binding energies of all Au n NCs-DPA complexes in the gas and water phases by density functional theory. The binding energies calculated by two different functionals, B3LYP and M062X, of the Au n NCs-DPA complexes in the solvent phase are lower than those in the gas phase, suggesting that the partially covalent and partially electrostatic bonding stabilizes the complexes. Atoms-in-molecules analysis showed that the intermolecular hydrogen and covalent bonding play an important role in the formation of these complexes. The interactions between Au n NCs-DPA complexes and water molecules also were studied by molecular dynamics simulations to summarize the effect of solvent on the binding between Au n NCs and DPA. Radial distribution functions and coordination numbers of the interactions between Au n NCs-DPA complexes and water are computed and showed that Au 6 NCs has the strongest interactions with DPA with compared to other complexes. The adsorption and deformation energies of DPA molecules on AuNCs surface has a 6 nm size with different shapes (sphere and box) and are calculated by MC simulations; the adsorption energies for all configurations in sphere and box shapes are negative which revealed that the adsorption of the drug molecule is exothermic and energetically favorable, and this indicated that the adsorption of DPA on the AuNPs surface is spontaneous due to existence of the weak intermolecular interaction. So, the drug molecule can be easily released from Au n NPs.

中文翻译：

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金纳米团簇作为 D-青霉胺抗癌药物新型纳米载体的能力：一项计算化学研究

在这项工作中，我们通过不同的计算方法研究了金纳米团簇（Au n NCs，n = 2、4 和 6）与 D-青霉胺 (DPA) 抗癌药物之间的相互作用，以研究 Au n NCs 作为抗癌药物的能力。首次用于 DPA 的纳米载体。我们通过密度泛函理论计算了气相和水相中所有 Au n NCs-DPA 复合物的结合能。Au n NCs-DPA 复合物在溶剂相中由两种不同的泛函 B3LYP 和 M062X 计算的结合能低于气相中的结合能，表明部分共价和部分静电键合稳定了配合物。分子中原子分析表明，分子间氢和共价键在这些复合物的形成中起着重要作用。还通过分子动力学模拟研究了 Au n NCs-DPA 复合物与水分子之间的相互作用，以总结溶剂对 Au n NCs 与 DPA 之间结合的影响。计算了 Au n NCs-DPA 配合物与水之间相互作用的径向分布函数和配位数，结果表明，与其他配合物相比，Au 6 NCs 与 DPA 的相互作用最强。DPA分子在AuNCs表面的吸附和变形能大小为6nm，不同形状（球体和盒体），通过MC模拟计算；球体和盒体形状的所有构型的吸附能均为负，表明药物分子的吸附是放热的且在能量上有利，这表明由于弱分子间相互作用的存在，DPA 在 AuNPs 表面的吸附是自发的。因此，药物分子可以很容易地从 Au n NPs 中释放出来。