Andoy Nesha May Octavio, Patel Meera, Lui Ching Lam Jane, Sullan Ruby May Arana
Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1065 Military Trail, Toronto, ON M1C 1A4, Canada.
Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON M5S 3H6, Canada.
Microorganisms. 2021 Oct 19;9(10):2176. doi: 10.3390/microorganisms9102176.
Interactions between a widely used polycationic polymer, polyethyleneimine (PEI), and a Gram-negative bacteria, , are investigated using atomic force microscopy (AFM) quantitative imaging. The effect of PEI, a known membrane permeabilizer, is characterized by probing both the structure and elasticity of the bacterial cell envelope. At low concentrations, PEI induced nanoscale membrane perturbations all over the bacterial surface. Despite these structural changes, no change in cellular mechanics (Young's modulus) was detected and the growth of is barely affected. However, at high PEI concentrations, dramatic changes in both structure and cell mechanics are observed. When immobilized on a flat surface, the ability of PEI to alter the membrane structure and reduce bacterial elasticity is diminished. We further probe this immobilization-induced effect by covalently attaching the polymer to the surface of polydopamine nanoparticles (PDNP). The nanoparticle-immobilized PEI (PDNP-PEI), though not able to induce major structural changes on the outer membrane of (in contrast to the flat surface), was able to bind to and reduce the Young's modulus of the bacteria. Taken together, our data demonstrate that the state of polycationic polymers, whether bound or free-which greatly dictates their overall configuration-plays a major role on how they interact with and disrupt bacterial membranes.
利用原子力显微镜（AFM）定量成像技术，研究了一种广泛使用的聚阳离子聚合物聚乙烯亚胺（PEI）与革兰氏阴性菌之间的相互作用。通过探测细菌细胞壁的结构和弹性，对已知的膜通透剂PEI的作用进行了表征。在低浓度下，PEI在细菌表面诱导了纳米级的膜扰动。尽管有这些结构变化，但未检测到细胞力学（杨氏模量）的变化，且细菌的生长几乎未受影响。然而，在高PEI浓度下，观察到结构和细胞力学都发生了显著变化。当固定在平面上时，PEI改变膜结构和降低细菌弹性的能力减弱。我们通过将聚合物共价连接到聚多巴胺纳米颗粒（PDNP）表面，进一步探究这种固定化诱导效应。固定在纳米颗粒上的PEI（PDNP-PEI）虽然不能在细菌外膜上诱导主要的结构变化（与平面表面情况相反），但能够结合并降低细菌的杨氏模量。综上所述，我们的数据表明，聚阳离子聚合物的状态，无论是结合态还是游离态——这在很大程度上决定了它们的整体构型——在它们与细菌膜相互作用并破坏细菌膜的方式中起着主要作用。
