Dipartimento di Chimica, Sezione di Chimica Generale, Università di Pavia, Pavia, Italy.
Langmuir. 2012 May 29;28(21):8140-8. doi: 10.1021/la3003838. Epub 2012 May 15.
In the present paper, we study the mechanism of antibacterial activity of glutathione (GSH) coated silver nanoparticles (Ag NPs) on model Gram negative and Gram positive bacterial strains. Interference in bacterial cell replication is observed for both cellular strains when exposed to GSH stabilized colloidal silver in solution, and microbicidal activity was studied when GSH coated Ag NPs are (i) dispersed in colloidal suspensions or (ii) grafted on thiol-functionalized glass surfaces. The obtained results confirm that the effect of dispersed GSH capped Ag NPs (GSH Ag NPs) on Escherichia coli is more intense because it can be associated with the penetration of the colloid into the cytoplasm, with the subsequent local interaction of silver with cell components causing damages to the cells. Conversely, for Staphylococcus aureus, since the thick peptidoglycan layer of the cell wall prevents the penetration of the NPs inside the cytoplasm, the antimicrobial effect is limited and seems related to the interaction with the bacterial surfaces. Experiments on GSH Ag NPs grafted on glass allowed us to elucidate more precisely the antibacterial mechanism, showing that the action is reduced because of GSH coating and the limitation of the translational freedom of NPs.
在本论文中，我们研究了谷胱甘肽（GSH）包覆的银纳米粒子（Ag NPs）对革兰氏阴性和革兰氏阳性细菌模型菌株的抗菌活性机制。当暴露于溶液中的 GSH 稳定胶体银时，两种细胞菌株都观察到对细菌细胞复制的干扰，并且当 GSH 包覆的 Ag NPs （i）分散在胶体悬浮液中或（ii）接枝在巯基功能化的玻璃表面上时，研究了杀菌活性。所得结果证实，分散的 GSH 封端的 Ag NPs（GSH Ag NPs）对大肠杆菌的作用更为强烈，因为它可以与胶体进入细胞质有关，随后银与细胞成分的局部相互作用导致细胞损伤。相反，对于金黄色葡萄球菌，由于细胞壁的厚肽聚糖层阻止了 NPs 穿透细胞质，因此抗菌作用受到限制，并且似乎与与细菌表面的相互作用有关。在接枝在玻璃上的 GSH Ag NPs 上进行的实验使我们能够更精确地阐明抗菌机制，表明由于 GSH 涂层和 NPs 的平移自由度受限，作用降低。
