Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; University of Science and Technology of China, Hefei 230026, China; Lu'an Branch, Anhui Institute of Innovation for Industrial Technology, Lu'an 237100, China.
Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; University of Science and Technology of China, Hefei 230026, China.
Colloids Surf B Biointerfaces. 2024 Nov;243:114131. doi: 10.1016/j.colsurfb.2024.114131. Epub 2024 Jul 29.
Identifying the antibacterial mechanisms of elemental silver at the nanoscale remains a significant challenge due to the intertwining behaviors between the particles and their released ions. The open question is which of the above factor dominate the antibacterial behaviors when silver nanoparticles (Ag NPs) with different sizes. Considering the high reactivity of Ag NPs, prior research has primarily concentrated on coated particles, which inevitably hinder the release of Ag ions due to additional chemical agents. In this study, we synthesized various Ag NPs, both coated and uncoated, using the laser ablation in liquids (LAL) technique. By analyzing both the changes in particle size and Ag ions release, the impacts of various Ag NPs on the cellular activity and morphological changes of gram-negative (E. coil) and gram-positive (S. aureus) bacteria were evaluated. Our findings revealed that for uncoated Ag NPs, smaller particles exhibited greater ions release efficiency and enhanced antibacterial efficacy. Specifically, particles approximately 1.5 nm in size released up to 55 % of their Ag ions within 4 h, significantly inhibiting bacterial growth. Additionally, larger particles tended to aggregate on the bacterial cell membrane surface, whereas smaller particles were more likely to be internalized by the bacteria. Notably, treatment with smaller Ag NPs led to more pronounced bacterial morphological changes and elevated levels of intracellular reactive oxygen species (ROS). We proposed that the bactericidal activity of Ag NPs stems from the synergistic effect between particle-cell interaction and the ionic silver, which is dependent on the crucial parameter of particle size.
由于纳米尺度下的银颗粒与其释放的离子之间存在相互交织的行为，因此确定元素银的抗菌机制仍然是一个重大挑战。目前尚未解决的问题是，当银纳米颗粒（Ag NPs）具有不同的尺寸时，上述哪个因素主导其抗菌行为。考虑到 Ag NPs 的高反应性，先前的研究主要集中在涂层颗粒上，由于额外的化学试剂，这不可避免地阻碍了 Ag 离子的释放。在本研究中，我们使用激光烧蚀液体（LAL）技术合成了各种涂覆和未涂覆的 Ag NPs。通过分析颗粒尺寸的变化和 Ag 离子的释放，评估了不同 Ag NPs 对革兰氏阴性（E. coil）和革兰氏阳性（S. aureus）细菌的细胞活性和形态变化的影响。我们的研究结果表明，对于未涂覆的 Ag NPs，较小的颗粒表现出更高的离子释放效率和增强的抗菌效果。具体而言，粒径约为 1.5nm 的颗粒在 4 小时内释放了高达 55%的 Ag 离子，显著抑制了细菌的生长。此外，较大的颗粒往往会在细菌细胞膜表面聚集，而较小的颗粒则更容易被细菌内化。值得注意的是，较小的 Ag NPs 处理会导致更明显的细菌形态变化和细胞内活性氧（ROS）水平升高。我们提出，Ag NPs 的杀菌活性源自颗粒-细胞相互作用和离子银之间的协同效应，这取决于颗粒尺寸这一关键参数。
