Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Anal Chem. 2013 Jun 4;85(11):5436-43. doi: 10.1021/ac400245j. Epub 2013 May 21.
Silver nanoparticles (Ag NPs) are extensively used as an antibacterial additive in commercial products and their release has caused environmental risk. However, conventional methods for the toxicity detection of Ag NPs are very time consuming and the mechanisms of action are not clear. We developed a new, in situ, rapid, and sensitive fingerprinting approach, using surface-enhanced Raman spectroscopy (SERS), to study the antibacterial activity and mechanism of Ag NPs of 80 and 18 nm (Ag80 and Ag18, respectively), by using the strong electromagnetic enhancement generated by Ag NPs. Sensitive spectra changes representing various biomolecules in bacteria were observed with increasing concentrations of Ag NPs. They not only allowed SERS to monitor the antibacterial activity of Ag NPs of different sizes in different water media but also to study the antibacterial mechanism at the molecular level. Ag18 were found to be more toxic than Ag80 in water, but their toxicity declined to a similar level in the PBS medium. The antibacterial mechanism was proposed on the basis of a careful identification of the chemical origins by comparing the SERS spectra with model compounds. The dramatic change in protein, hypoxanthine, adenosine, and guanosine bands suggested that Ag NPs have a significant impact on the protein and metabolic processes of purine. Finally, by adding nontoxic and SERS active Au NPs, SERS was successfully utilized to study the action mode of the NPs unable to produce an observable SERS signal. This work opens a window for the future extensive SERS studies of the antibacterial mechanism of a great variety of non-SERS-active NPs.
银纳米颗粒（Ag NPs）被广泛用作商业产品中的抗菌添加剂，其释放对环境造成了风险。然而，传统的 Ag NPs 毒性检测方法非常耗时，作用机制也不清楚。我们开发了一种新的原位、快速和灵敏的指纹分析方法，使用表面增强拉曼光谱（SERS），通过 Ag NPs 产生的强电磁场增强，研究了 80nm 和 18nm 的 Ag NPs（分别为 Ag80 和 Ag18）的抗菌活性和作用机制。随着 Ag NPs 浓度的增加，观察到代表细菌中各种生物分子的敏感光谱变化。它们不仅允许 SERS 监测不同大小的 Ag NPs 在不同水介质中的抗菌活性，还可以在分子水平上研究抗菌机制。Ag18 在水中比 Ag80 更具毒性，但在 PBS 介质中其毒性下降到相似水平。基于对模型化合物的 SERS 光谱进行仔细的化学起源识别，提出了抗菌机制。蛋白质、次黄嘌呤、腺嘌呤和鸟嘌呤带的剧烈变化表明 Ag NPs 对蛋白质和嘌呤代谢过程有重大影响。最后，通过添加无毒且具有 SERS 活性的 Au NPs，成功地利用 SERS 研究了无法产生可观测 SERS 信号的 NPs 的作用模式。这项工作为未来广泛研究各种非 SERS 活性 NPs 的抗菌机制开辟了新的途径。
