Metal and metal oxide nanoparticles (NPs) have been increasingly utilized in many industries to harness their documented antibacterial properties. However, the mechanism(s) of action is still debated in the literature. The aim of this study is to understand how changes in outer membrane charge of a test bacteria Haemophilus influenzae alter the antibacterial activity of ZnO NPs of average sizes of 20 nM and 60 nM. H. influenzae outer membrane charge was altered through use of the wild strain (Rd) and mutant lines H543 and H446. Results indicate that antibacterial effects are both concentration and size dependent, with smaller NPs causing increased antibacterial response. Most critically, antibacterial assays and collected TEM images demonstrate that increasing negative charge on the outer membrane of bacteria decreased the antibacterial activity of the ZnO NPs. Finally, this work demonstrates the possibility of using ZnO NPs to treat H. influenzae infection in clinical settings.

金属和金属氧化物纳米粒子 (NPs) 已越来越多地用于许多行业，以利用其记录在案的抗菌特性。然而，文献中仍对作用机制进行了辩论。本研究的目的是了解测试细菌流感嗜血杆菌外膜电荷的变化如何改变平均尺寸为 20 nM 和 60 nM 的 ZnO NPs 的抗菌活性。流感嗜血杆菌通过使用野生菌株 (Rd) 和突变系 H543 和 H446 改变了外膜电荷。结果表明，抗菌作用与浓度和大小有关，较小的 NP 会导致抗菌反应增加。最关键的是，抗菌测定和收集的 TEM 图像表明，增加细菌外膜上的负电荷会降低 ZnO NPs 的抗菌活性。最后，这项工作证明了在临床环境中使用 ZnO NPs 治疗流感嗜血杆菌感染的可能性。