摘要
Metallic silver （Ag） and its ability to combat infection have been known since ancient history. In the wake of nanotechnology advancement, silver＇s efficacy to fight broad spectrum bacterial infections is further improved in the form of Ag nanoparticles （NPs）. Recent studies have ascribed the broad spectrum antimicrobial properties of Ag NPs to dissociation of Ag＊ ions from the NPs, which may not be entirely applicable when the size of Ag NPs decreases to the sub-2 nm range [denoted Ag nanoclusters （NCs）]. In this paper we report that ultrasmall glutathione （GSH）-protected Ag^＋-rich NCs （Ag^＋-R NCs for short, with a predominance of Ag＋ species in the NCs） have much higher antimicrobial activities towards both gram-negative and gram-positive bacteria than the reference NC, GSH-Ag^＋-R NCs. They have the same size and surface ligand, but with different oxidation states of the core silver. This interesting finding suggests that the undissociated Ag^＋-R NCs armed with abundant Ag^＋ ions on the surface are highly active in bacterial killing, which was not observed in the system of their larger counterpart, Ag NPs.
自从古代史，金属性的银(Ag ) 和它与感染作斗争的能力被知道了。在纳米技术前进的 wake，与宽广光谱作斗争的银功效细菌的感染进一步在 Ag nanoparticles (NP ) 形式被改进。当 Ag NP 的尺寸减少到 sub-2 nm 范围时，最近的研究从 NP 归功于 Ag NP 的宽广光谱抗菌剂性质到 Ag+ 离子的分离，它不能是完全适用的[表示 Ag nanoclusters (NC )] 。在我们报导的这份报纸，那 ultrasmall 谷胱甘肽(GSH ) 保护了 Ag+ 富有的 NC (Ag+-R NC 作为缩写，与在 NC 的 Ag+ 种类的优势) 比参考书 NC 向克否定、克积极的细菌举办高得多的抗菌剂活动， GSH-Ag0-R NC。他们有一样的尺寸和表面 ligand，但是与核心银的不同氧化状态。这有趣的发现建议在表面上用丰富的 Ag+ 离子武装的未离解的 Ag+-R NC 在细菌的杀死是高度活跃的，它没在他们的更大的对应物的系统被观察， Ag NP。
