Krychowiak-Maśnicka Marta, Wojciechowska Weronika Paulina, Bogaj Karolina, Bielicka-Giełdoń Aleksandra, Czechowska Ewa, Ziąbka Magdalena, Narajczyk Magdalena, Kawiak Anna, Mazur Tomasz, Szafranek Beata, Królicka Aleksandra
University of Gdansk, Intercollegiate Faculty of Biotechnology, Laboratory of Biologically Active Compounds, Gdansk, Poland.
University of Gdansk, Faculty of Chemistry, Gdansk, Poland.
Nanotechnol Sci Appl. 2024 Dec 6;17:227-246. doi: 10.2147/NSA.S489407. eCollection 2024.
Although it is well known that the size, shape, and surface chemistry affect the biological potential of silver nanoparticles (AgNPs), the published studies that have considered the influence of AgNP surface on antibacterial activity have not provided conclusive results. This is the first study whose objective was to determine the significance of the surface net charge of AgNPs on their antibacterial potential, attraction to bacterial cells, and cell envelope disruption, considering differences in bacterial surface properties.
We evaluated five commercial AgNP colloids with identical size and shape but different surface ligands. We thoroughly characterized their physicochemical properties, including the zeta potential, hydrodynamic diameter, and polydispersity index, and determined the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), along with silver absorption into bacterial cells. Moreover, we investigated structural changes in bacteria treated with AgNPs by using a crystal violet assay and electron microscopy.
The zeta potential of AgNPs ranged from -47.6 to +68.5 mV, with a hydrodynamic diameter of 29-87 nm and a polydispersity index of 0.349-0.863. Bacterial susceptibility varied significantly (0.5 ≤ MIC ≤ 256 µg Ag/mL; 1 ≤ MBC ≤ 256 µg Ag/mL); we found the lowest susceptibility in bacteria with a cell wall or a polysaccharide capsule. The most active AgNPs (0.5 ≤ MIC ≤ 32 µg Ag/mL; 2 ≤ MBC ≤ 64 µg Ag/mL) had a moderate surface charge (-21.5 and +14.9 mV). The antibacterial potential was unrelated to ion dissolution or cell envelope disruption, and bacterial cells absorbed less of the most active AgNPs (1.75-7.65%).
Contrary to previous reports, we found that a moderate surface charge is crucial for the antibacterial activity of AgNPs, and that a significant attraction of the nanoparticle to the cell surface reduces the antibacterial potential of AgNPs. These findings challenge the existing views on AgNP antibacterial mechanisms and interactions with bacterial cells.
尽管众所周知，银纳米颗粒（AgNP）的尺寸、形状和表面化学性质会影响其生物学潜力，但已发表的考虑AgNP表面对抗菌活性影响的研究尚未得出确凿结果。这是第一项旨在确定AgNP表面净电荷对其抗菌潜力、对细菌细胞的吸引力以及细胞壁破坏的重要性的研究，同时考虑了细菌表面性质的差异。
我们评估了五种尺寸和形状相同但表面配体不同的商用AgNP胶体。我们全面表征了它们的物理化学性质，包括zeta电位、流体动力学直径和多分散指数，并确定了最低抑菌浓度（MIC）和最低杀菌浓度（MBC），以及银在细菌细胞中的吸收情况。此外，我们通过结晶紫测定法和电子显微镜研究了用AgNP处理的细菌的结构变化。
AgNP的zeta电位范围为-47.6至+68.5 mV，流体动力学直径为29-87 nm，多分散指数为0.349-0.863。细菌敏感性差异显著（0.5≤MIC≤256μg Ag/mL；1≤MBC≤256μg Ag/mL）；我们发现具有细胞壁或多糖荚膜的细菌敏感性最低。活性最高的AgNP（0.5≤MIC≤32μg Ag/mL；2≤MBC≤64μg Ag/mL）具有中等表面电荷（-21.5和+14.9 mV）。抗菌潜力与离子溶解或细胞壁破坏无关，并且细菌细胞吸收的活性最高的AgNP较少（1.75-7.65%）。
与先前的报道相反，我们发现中等表面电荷对AgNP的抗菌活性至关重要，并且纳米颗粒对细胞表面的显著吸引力会降低AgNP的抗菌潜力。这些发现挑战了关于AgNP抗菌机制及其与细菌细胞相互作用的现有观点。
