Department of Chemistry, ‡Macromolecular Science and Engineering Center, and §Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan , Ann Arbor, Michigan 48109, United States.
Langmuir. 2018 Feb 6;34(5):2057-2062. doi: 10.1021/acs.langmuir.7b03668. Epub 2018 Jan 27.
Antimicrobial peptides (AMPs) in free solution can kill bacteria by disrupting bacterial cell membranes. Their modes of action have been extensively studied, and various models ranging from pore formation to carpet-like mechanisms were proposed. Surface-immobilized AMPs have been used as coatings to kill bacteria and as sensors to capture bacteria, but the interaction mechanisms of surface-immobilized AMPs and bacteria are not fully understood. In this research, an analytical platform, sum frequency generation (SFG) microscope, which is composed of an SFG vibrational spectrometer and a fluorescence microscope, was used to probe molecular interactions between surface-immobilized AMPs and bacteria in situ in real time at the solid/liquid interface. SFG probed the molecular structure of surface-immobilized AMPs while interacting with bacteria, and fluorescence images of dead bacteria were monitored as a function of time during the peptide-bacteria interaction. It was believed that upon bacteria contact, the surface-immobilized peptides changed their orientation and killed bacteria. This research demonstrated that the SFG microscope platform can examine the structure and function (bacterial killing) at the same time in the same sample environment, providing in-depth understanding on the structure-activity relationships of surface-immobilized AMPs.
抗菌肽（AMPs）在游离溶液中可以通过破坏细菌细胞膜来杀死细菌。它们的作用模式已经得到了广泛的研究，提出了各种模型，从孔形成到地毯样机制。表面固定的 AMP 已被用作涂层来杀死细菌和作为传感器来捕获细菌，但表面固定的 AMP 和细菌之间的相互作用机制还不完全清楚。在这项研究中，采用了一种分析平台，即和频产生（SFG）显微镜，它由 SFG 振动光谱仪和荧光显微镜组成，用于原位实时探测固/液界面上表面固定的 AMPs 和细菌之间的分子相互作用。SFG 探测了与细菌相互作用时表面固定 AMPs 的分子结构，同时监测了作为肽-细菌相互作用过程中时间函数的死细菌的荧光图像。据信，在与细菌接触时，表面固定的肽改变了它们的方向并杀死了细菌。这项研究表明，SFG 显微镜平台可以在相同的样品环境中同时检查结构和功能（杀菌），提供对表面固定 AMPs 的结构-活性关系的深入了解。
