The antibacterial effect of ZnO nanoparticles is tested against Staphylococcus aureus, (a Gram-positive pathogenic bacterium) from a particle-size, concentration, and surface-defects point of view. Activation of antibacterial activity was achieved by standard well diffusion agar and minimum inhibitory concentration procedures. Our results show that smaller-sized particles are more effective inhibitors of bacterial activity when used in a certain optimum concentration. To reveal the underlying mechanism of the observed size and concentration-dependent bacterial activity inhibition, we measured the concentrations of Zn2+ ions released in each suspension by an inductive couple plasma optical emission spectrophotometer. Additionally, photoluminance spectra of our samples show significant surface defects (mainly oxygen vacancies) that generate reactive oxygen species. The underlying mechanism of the observed size- and concentration-dependent bacterial activity inhibition is attributed primarily to the release of Zn2+ ions and generation of reactive oxygen species that interact and penetrate the cell membrane, causing lethal damage to the cell. Finally, the antibacterial effectiveness and maximum sensitivity of our nanoparticles is confirmed by optical density measurements.

中文翻译：

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化学工程球形氧化锌纳米颗粒对细菌生长的大小依赖性抑制

从粒径、浓度和表面缺陷的角度测试了 ZnO 纳米颗粒对金黄色葡萄球菌（一种革兰氏阳性病原菌）的抗菌作用。通过标准孔扩散琼脂和最小抑菌浓度程序实现抗菌活性的激活。我们的结果表明，当以某个最佳浓度使用时，较小尺寸的颗粒是更有效的细菌活性抑制剂。为了揭示观察到的大小和浓度依赖性细菌活性抑制的潜在机制，我们通过电感耦合等离子体光学发射分光光度计测量了每个悬浮液中释放的 Zn2+ 离子的浓度。此外，我们样品的光致发光光谱显示出产生活性氧的显着表面缺陷（主要是氧空位）。观察到的大小和浓度依赖性细菌活性抑制的潜在机制主要归因于 Zn2+ 离子的释放和活性氧的产生，这些活性氧与细胞膜相互作用并穿透细胞膜，对细胞造成致命损伤。最后，我们的纳米粒子的抗菌效果和最大灵敏度通过光密度测量得到证实。