Li Ju, Rong Kaifeng, Zhao Huiping, Li Fei, Lu Zhong, Chen Rong
Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Xiongchu Avenue, Wuhan 430073, PR China.
J Nanosci Nanotechnol. 2013 Oct;13(10):6806-13. doi: 10.1166/jnn.2013.7781.
Silver nanoparticles (AgNPs) with different sizes (5, 15 and 55 nm) were synthesized via simple method, and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray microanalysis (EDX) and ultraviolet-visible absorption spectroscopy (UV-Vis). The antibacterial activities of the prepared AgNPs against Gram-negative Escherichia coli (E. coli), Gram-positive Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis) were evaluated by inhibition zone, inhibition curve, and colony counting methods. The results showed that the AgNPs exhibited obvious bacterium-selective and size-dependent antibacterial activities. The Gram-positive bacteria S. aureus and B. subtilis were more sensitive to AgNPs than Gram-negative bacterium E. coli. Interestingly, AgNPs displayed remarkably antibacterial activities against B. subtilis among Gram-positive bacteria, regardless of whether in separately or cocultured bacteria. It also showed that AgNPs with 5 nm in size presented the highest antibacterial activity against both Gram-negative and Gram-positive bacteria. The effects of AgNPs on the membrane leakage of the reducing sugars from three bacteria were also measured by 3,5-dinitrosalicylic acid method. The leakage amount of reducing sugars from B. subtilis was the highest among the tested bacteria, indicating that AgNPs could damage the structure of bacteria cell membrane and resulted in the leakage of reducing sugars, leading to the death of bacteria.
通过简单方法合成了不同尺寸（5、15和55纳米）的银纳米颗粒（AgNPs），并采用粉末X射线衍射（XRD）、透射电子显微镜（TEM）、能量色散X射线微分析（EDX）和紫外可见吸收光谱（UV-Vis）对其进行了表征。通过抑菌圈、抑制曲线和菌落计数法评估了所制备的AgNPs对革兰氏阴性大肠杆菌（E. coli）、革兰氏阳性金黄色葡萄球菌（S. aureus）和枯草芽孢杆菌（B. subtilis）的抗菌活性。结果表明，AgNPs表现出明显的细菌选择性和尺寸依赖性抗菌活性。革兰氏阳性菌金黄色葡萄球菌和枯草芽孢杆菌比革兰氏阴性菌大肠杆菌对AgNPs更敏感。有趣的是，无论在单独培养还是共培养的细菌中，AgNPs对革兰氏阳性菌中的枯草芽孢杆菌都表现出显著的抗菌活性。还表明，尺寸为5纳米的AgNPs对革兰氏阴性菌和革兰氏阳性菌均表现出最高的抗菌活性。采用3,5-二硝基水杨酸法测定了AgNPs对三种细菌还原糖膜泄漏的影响。在所测试的细菌中，枯草芽孢杆菌的还原糖泄漏量最高，表明AgNPs可破坏细菌细胞膜结构，导致还原糖泄漏，从而导致细菌死亡。
