Laboratory for Biointerfaces, Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland; University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering (FB40), Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands.
Laboratory for Biointerfaces, Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland.
J Colloid Interface Sci. 2019 Sep 15;552:247-257. doi: 10.1016/j.jcis.2019.05.043. Epub 2019 May 14.
Many materials used in the medical settings such as catheters and contact lenses as well as most biological tissues are not purely elastic, but rather viscoelastic. While substrate elasticity has been investigated for its influence on bacterial adhesion, the impact of substrate viscosity has not been explored. Here, the importance of considering substrate viscosity is explored by using polydimethylsiloxane (PDMS) as the substrate material, whose mechanical properties can be tuned from predominantly elastic to viscous by varying cross-linking degree. Interfacial rheology and atomic force microscopy analysis prove that PDMS with a low cross-linking degree exhibits both low stiffness and high viscosity. This degree of viscoelasticity confers to PDMS a remarkable stress relaxation, a good capability to deform and an increased adhesive force. Bacterial adhesion assays were conducted under flow conditions to study the impact of substrate viscosity on Escherichia coli adhesion. The viscous PDMS not only enhanced E. coli adhesion but also conferred greater resistance to desorption against shear stress at air/liquid interface, compared to the PDMS with high crosslinking degree. These findings highlight the importance to consider substrate viscosity while studying bacterial adhesion. The current work provides new insights to an improved understanding of how bacteria interact with complex viscoelastic environments.
许多在医疗环境中使用的材料，如导管和隐形眼镜以及大多数生物组织，都不是纯粹的弹性体，而是粘弹性体。虽然已经研究了基底弹性对细菌粘附的影响，但基底粘度的影响尚未得到探索。在这里，通过使用聚二甲基硅氧烷（PDMS）作为基底材料来探索考虑基底粘度的重要性，其机械性能可以通过改变交联度从主要弹性变为粘性。界面流变学和原子力显微镜分析证明，交联度低的 PDMS 表现出低刚度和高粘度。这种粘弹性赋予 PDMS 显著的应力松弛、良好的变形能力和增加的粘附力。在流动条件下进行细菌粘附实验，以研究基底粘度对大肠杆菌粘附的影响。与交联度高的 PDMS 相比，粘性 PDMS 不仅增强了大肠杆菌的粘附，而且赋予了更大的抵抗剪切应力在气/液界面上解吸的能力。这些发现强调了在研究细菌粘附时考虑基底粘度的重要性。目前的工作为更好地理解细菌如何与复杂的粘弹性环境相互作用提供了新的见解。
