Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C. Evin, P.O. Box: 19835-389, Tehran, Iran.
Res Microbiol. 2011 Jun;162(5):542-9. doi: 10.1016/j.resmic.2011.04.009. Epub 2011 Apr 21.
Antibacterial activity of silver nanoparticles (AgNPs) was investigated using Staphylococcus aureus PTCC1431 as a model of Gram-positive bacteria. The mechanism of antibacterial activity of AgNPs was then studied by analyzing the growth, morphology, and molecular variations in the cell wall. Experimental data showed that AgNPs at a concentration of 4 μg/ml completely inhibited bacterial growth. Transmission electron microscopy results confirmed cell wall damage produced by AgNPs as well as accumulation of AgNPs in the bacterial membrane. Meanwhile, the AgNP-treated bacteria were monitored by circular dichroism to reveal peptidoglycan variations. Some degree of variation in the α-helix position of the peptide chain was observed. Moreover, increasing the AgNP concentration to 8 μg/ml resulted in release of muramic acid (MA) into the medium, which could be attributed to cell wall distraction. A gas chromatography-tandem mass spectrometry analysis and release of MA, as a bacterial indicator, showed that glycan strands may also be decomposed as a result of AgNP treatment.
采用金黄色葡萄球菌 PTCC1431 作为革兰氏阳性菌模型，研究了银纳米粒子（AgNPs）的抗菌活性。然后通过分析细胞壁的生长、形态和分子变化来研究 AgNPs 的抗菌活性机制。实验数据表明，浓度为 4μg/ml 的 AgNPs 完全抑制了细菌生长。透射电子显微镜结果证实了 AgNPs 对细胞壁的损伤以及 AgNPs 在细菌膜中的积累。同时，通过圆二色性监测 AgNP 处理的细菌，以揭示肽聚糖的变化。观察到肽链的α-螺旋位置发生了一定程度的变化。此外，将 AgNP 浓度增加到 8μg/ml 会导致乳酰基（MA）释放到培养基中，这可能归因于细胞壁的分散。气相色谱-串联质谱分析和 MA 的释放作为细菌指标表明，聚糖链也可能因 AgNP 处理而分解。
