Department of Materials Science and Engineering, Liaocheng University, Liaocheng 252000, China.
Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Int J Mol Sci. 2020 Nov 22;21(22):8836. doi: 10.3390/ijms21228836.
This article reviews the recent developments in the synthesis, antibacterial activity, and visible-light photocatalytic bacterial inactivation of nano-zinc oxide. Polycrystalline wurtzite ZnO nanostructures with a hexagonal lattice having different shapes can be synthesized by means of vapor-, liquid-, and solid-phase processing techniques. Among these, ZnO hierarchical nanostructures prepared from the liquid phase route are commonly used for antimicrobial activity. In particular, plant extract-mediated biosynthesis is a single step process for preparing nano-ZnO without using surfactants and toxic chemicals. The phytochemical molecules of natural plant extracts are attractive agents for reducing and stabilizing zinc ions of zinc salt precursors to form green ZnO nanostructures. The peel extracts of certain citrus fruits like grapefruits, lemons and oranges, acting as excellent chelating agents for zinc ions. Furthermore, phytochemicals of the plant extracts capped on ZnO nanomaterials are very effective for killing various bacterial strains, leading to low minimum inhibitory concentration (MIC) values. Bioactive phytocompounds from green ZnO also inhibit hemolysis of infected red blood cells and inflammatory activity of mammalian immune system. In general, three mechanisms have been adopted to explain bactericidal activity of ZnO nanomaterials, including direct contact killing, reactive oxygen species (ROS) production, and released zinc ion inactivation. These toxic effects lead to the destruction of bacterial membrane, denaturation of enzyme, inhibition of cellular respiration and deoxyribonucleic acid replication, causing leakage of the cytoplasmic content and eventual cell death. Meanwhile, antimicrobial activity of doped and modified ZnO nanomaterials under visible light can be attributed to photogeneration of ROS on their surfaces. Thus particular attention is paid to the design and synthesis of visible light-activated ZnO photocatalysts with antibacterial properties.
本文综述了纳米氧化锌的合成、抗菌活性和可见光光催化杀菌性能的最新进展。多晶纤锌矿 ZnO 纳米结构具有不同形状的六方晶格，可以通过气相、液相和固相加工技术合成。在这些方法中，液相法制备的 ZnO 分级纳米结构通常用于抗菌活性。特别是，植物提取物介导的生物合成是一种无需使用表面活性剂和有毒化学品制备纳米 ZnO 的单步工艺。天然植物提取物的植物化学分子是一种很有吸引力的试剂，可以将锌盐前体的锌离子还原和稳定，形成绿色 ZnO 纳米结构。某些柑橘类水果（如葡萄柚、柠檬和橙子）的果皮提取物，作为锌离子的优良螯合剂。此外，植物提取物的植物化学物质覆盖在 ZnO 纳米材料上，对杀死各种细菌菌株非常有效，导致最低抑菌浓度（MIC）值较低。来自绿色 ZnO 的生物活性植物化合物也抑制感染的红细胞的溶血和哺乳动物免疫系统的炎症活性。一般来说，已经采用了三种机制来解释 ZnO 纳米材料的杀菌活性，包括直接接触杀伤、活性氧（ROS）的产生和释放锌离子失活。这些毒性作用导致细菌膜的破坏、酶的变性、细胞呼吸和脱氧核糖核酸复制的抑制，导致细胞质内容物的泄漏和最终的细胞死亡。同时，掺杂和改性 ZnO 纳米材料在可见光下的抗菌活性可以归因于其表面上 ROS 的光生。因此，特别关注具有抗菌性能的可见光激活 ZnO 光催化剂的设计和合成。
