Surface properties of nanoparticles (NPs) could greatly influence their biomedical efficacy. This paradigm drives many NPs-based antimicrobial agents as the common belief that a more positively charged surface would favor intimate interactions with the negatively charged bacterial cell wall, leading to a higher overall antimicrobial efficacy. Surprisingly, this study shows the opposite effect when using ultrasmall gold nanoclusters (Au NCs) as a model to investigate the effect of surface properties on their antimicrobial performance. Leveraging on the molecular properties of ultrasmall Au NCs, the surface properties of thiolate-protected Au NCs could be precisely controlled at the atomic level, generating a family of Au NCs with the same number of gold atoms but different surface properties. By tuning the type and ratio of surface ligands on Au NCs, more negatively charged Au NCs would produce more reactive oxygen species (ROS), leading to a better bacterial killing efficiency. This finding is in stark contrast to the previous paradigm and suggests the complexities of the nanomaterial-cell interactions, shedding some light on the design of high-performance NP-based antimicrobial agents.

中文翻译：

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金纳米团簇的表面配体化学决定了其抗菌能力

纳米粒子（NPs）的表面性质可能会极大地影响其生物医学功效。这种范例推动了许多基于NPs的抗菌剂的产生，因为人们普遍认为带正电的表面会促进与带负电的细菌细胞壁的紧密相互作用，从而导致更高的整体抗菌功效。出乎意料的是，这项研究显示了使用超小金纳米团簇（Au NCs）作为模型来研究表面特性对其抗菌性能的影响时的相反效果。利用超小型Au NCs的分子性质，可以在原子水平上精确控制硫醇盐保护的Au NCs的表面性质，从而生成具有相同金原子数但表面性质不同的Au Au NCs系列。通过调节Au NCs上表面配体的类型和比例，带更多负电荷的Au NCs将产生更多的活性氧（ROS），从而导致更好的细菌杀灭效率。这一发现与以前的范例形成鲜明对比，并暗示了纳米材料与细胞相互作用的复杂性，为高性能基于NP的抗菌剂的设计提供了一些启示。