Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic.
Author Affiliations Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic.
Int J Nanomedicine. 2021 May 24;16:3541-3554. doi: 10.2147/IJN.S300428. eCollection 2021.
Nanomaterials for antimicrobial applications have gained interest in recent years due to the increasing bacteria resistance to conventional antibiotics. Wound sterilization, water treatment and surface decontamination all avail from multifunctional materials that also possess excellent antibacterial properties, eg zinc oxide (ZnO). Here, we assess and compare the effects of synthesized hedgehog-like ZnO structures and commercial ZnO particles with and without mixing on the inactivation of bacteria on surfaces and in liquid environments.
Gram-positive () and Gram-negative () bacteria in microbial culture medium were added to reverse spin bioreactors that contained different concentrations of each ZnO type to enable dynamic mixing of the bacteria-ZnO suspensions. Optical density of the bacteria-ZnO suspensions was measured in real-time and the number of viable bacteria after 24 h exposure was determined using standard microbiological techniques. The concentration of zinc ion generated from ZnO dissolution in different liquid types was estimated from the dynamic interaction exposure. Static antibacterial tests without agitation in liquid media and on agar surface were performed for comparison.
A correlation between increasing ZnO particle concentration and reduction in viable bacteria was not monotonous. The lowest concentration tested (10 µg/mL) even stimulated bacteria growth. The hedgehog ZnO was significantly more antibacterial than commercial ZnO particles at higher concentrations (up to 1000 µg/mL tested), more against than . Minimum inhibitory concentration in microwell plates was correlated with those results. No inhibition was detected for any ZnO type deposited on agar surface. Zinc ion release was greatly suppressed in cultivation media. Scanning electron microscopy images revealed that ZnO needles can pierce membrane of bacteria whereas the commercial ZnO nanoparticles rather agglomerate on the cell surface.
The inhibition effects are thus mainly controlled by the interaction dynamics between bacteria and ZnO, where mixing greatly enhances antibacterial efficacy of all ZnO particles. The efficacy is modulated also by ZnO particle shapes, where hedgehog ZnO has superior effect, in particular at lower concentrations. However, at too low concentrations, ZnO can stimulate bacteria growth and must be thus used with caution.
由于常规抗生素对细菌的耐药性不断增加，近年来，用于抗菌应用的纳米材料引起了人们的兴趣。伤口消毒、水处理和表面去污都可以利用多功能材料来实现，这些材料还具有优异的抗菌性能，例如氧化锌 (ZnO)。在这里，我们评估和比较了合成刺猬状 ZnO 结构和具有和不具有混合的商业 ZnO 颗粒对表面和液体环境中细菌失活的影响。
在含有不同浓度的每种 ZnO 类型的反向旋转生物反应器中加入微生物培养基中的革兰氏阳性菌（）和革兰氏阴性菌（），以实现细菌-ZnO 悬浮液的动态混合。实时测量细菌-ZnO 悬浮液的吸光度，并使用标准微生物技术确定暴露 24 小时后存活细菌的数量。从动态相互作用暴露中估计 ZnO 在不同液体类型中溶解产生的锌离子浓度。为了进行比较，还在液体介质中和琼脂表面上进行了没有搅拌的静态抗菌测试。
随着 ZnO 颗粒浓度的增加，存活细菌减少的相关性并不单调。测试的最低浓度（10 µg/mL）甚至刺激了细菌的生长。与商业 ZnO 颗粒相比，刺猬状 ZnO 在更高浓度（测试高达 1000 µg/mL）下具有更强的抗菌作用，对 比 更有效。微孔板中的最小抑菌浓度与这些结果相关。任何类型的 ZnO 都没有抑制作用沉积在琼脂表面上。在培养介质中，锌离子释放受到极大抑制。扫描电子显微镜图像显示，ZnO 针可以刺穿细菌的膜，而商业 ZnO 纳米颗粒则在细胞表面上聚集。
因此，抑制效果主要由细菌与 ZnO 之间的相互作用动力学控制，其中混合大大增强了所有 ZnO 颗粒的抗菌效果。效果还受 ZnO 颗粒形状的调节，其中刺猬状 ZnO 具有优越的效果，特别是在较低的浓度下。然而，在浓度过低时，ZnO 会刺激细菌生长，因此必须谨慎使用。
