Sénéchal Annie, Carrigan Shawn D, Tabrizian Maryam
Department of Biomedical Engineering, McGill University, 3775 University Street, Montreal, QC, Canada H3A 2B4.
Langmuir. 2004 May 11;20(10):4172-7. doi: 10.1021/la035847y.
The aim of this study was to compare the initial adhesion forces of the uropathogen Enterococcus faecalis with the medical-grade polymers polyurethane (PU), polyamide (PA), and poly(tetrafluoroethylene) (PTFE). To quantify the cell-substrate adhesion forces, a method was developed using atomic force microscopy (AFM) in liquid that allows for the detachment of individual live cells from a polymeric surface through the application of increasing force using unmodified cantilever tips. Results show that the lateral force required to detach E. faecalis cells from a substrate differed depending on the nature of the polymeric surface: a force of 19 +/- 4 nN was required to detach cells from PU, 6 +/- 4 nN from PA, and 0.7 +/- 0.3 nN from PTFE. Among the unfluorinated polymers (PU and PA), surface wettability was inversely proportional to the strength of adhesion. AFM images also demonstrated qualitative differences in bacterial adhesion; PU was covered by clusters of cells with few cell singlets present, whereas PA was predominantly covered by individual cells. Moreover, extracellular material could be observed on some clusters of PU-adhered cells as well as in the adjacent region surrounding cells adhered on PA. E. faecalis adhesion to the fluorinated polymer (PTFE) showed different characteristics; only a few individual cells were found, and bacteria were easily damaged, and thus detached, by the tip. This work demonstrates the utility of AFM for measurement of cell-substrate lateral adhesion forces and the contribution these forces make toward understanding the initial stages of bacterial adhesion. Further, it suggests that initial adhesion can be controlled, through appropriate biomaterial design, to prevent subsequent formation of aggregates and biofilms.
本研究的目的是比较尿路致病菌粪肠球菌与医用级聚合物聚氨酯（PU）、聚酰胺（PA）和聚四氟乙烯（PTFE）之间的初始粘附力。为了量化细胞与底物的粘附力，开发了一种在液体中使用原子力显微镜（AFM）的方法，该方法允许通过使用未修饰的悬臂尖端施加逐渐增加的力，将单个活细胞从聚合物表面分离。结果表明，将粪肠球菌细胞从底物上分离所需的侧向力因聚合物表面的性质而异：从PU上分离细胞需要19±4 nN的力，从PA上分离需要6±4 nN的力，从PTFE上分离需要0.7±0.3 nN的力。在未氟化的聚合物（PU和PA）中，表面润湿性与粘附强度成反比。AFM图像还显示了细菌粘附的定性差异；PU被细胞簇覆盖，单个细胞很少，而PA主要被单个细胞覆盖。此外，在一些粘附在PU上的细胞簇以及粘附在PA上的细胞周围区域也可以观察到细胞外物质。粪肠球菌对氟化聚合物（PTFE）的粘附表现出不同的特征；只发现了少数单个细胞，并且细菌很容易被尖端损坏并因此分离。这项工作证明了AFM在测量细胞与底物侧向粘附力方面的实用性，以及这些力对理解细菌粘附初始阶段的贡献。此外，它表明可以通过适当的生物材料设计来控制初始粘附，以防止随后聚集体和生物膜的形成。
