Understanding the antimicrobial mechanism of metal nanoparticles using super resolution fluorescence microscopy

细菌对抗生素的耐药性已成为美国和世界各地公共健康的最大威胁之一。在众多的替代抗菌剂中，金属纳米粒子因其具有抑制细菌生长和杀灭细菌的能力而引起了人们的广泛兴趣和关注。然而，金属纳米颗粒的抗菌作用的确切机制仍然知之甚少。该项目将建立金属纳米颗粒作为常用抗生素替代品的抗菌行为的基本机制。研究小组将开发和使用具有卓越空间和时间分辨率的先进成像工具和技术，以调查单个活细菌与银纳米颗粒之间的相互作用，并获得关于银纳米颗粒抗菌效果的知识。这项研究的结果将为金属纳米颗粒的设计和生产提供指导原则，用于食品安全和医院感染治疗中的抗菌剂应用，从而改善美国公共健康并造福社会。此外，还将开展全面的教育和外联活动，培养美国下一代科学家和工程师的兴趣，并向他们提供纳米材料及其应用方面的经验和知识。这将加强和提高美国未来在STEM领域的竞争优势。本研究的目标是在单细胞水平上定量了解纳米银的抗菌机理及其与活细菌的相互作用。这将通过开发使用超分辨率荧光显微镜的方法来实现，这将允许以20纳米的空间分辨率和10-30毫秒的时间分辨率研究单个生物分子(例如蛋白质、DNA和脂类)及其动力学。这项研究的目标将通过(1)确定纳米银对类核相关蛋白的空间组织和功能的影响；(2)量化纳米银对细菌膜的破坏；以及(3)测量纳米银的依赖性？对颗粒形状、电荷和表面修饰的有效性。超分辨荧光显微镜的结果将得到常规生物技术和化验的验证和补充。这项研究将解决目前围绕金属纳米颗粒的抗菌机制存在的争议，部分原因是缺乏对单个活细菌的时间和空间分辨率。其结果将是在细胞和分子水平上更好地理解纳米生物界面。这项研究将提供有价值的定量信息，以指导抗菌应用的金属纳米颗粒的合理设计和制备。这项研究中开发的方法预计也适用于其他纳米结构和不同类型的细菌。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Antibiotic resistance of bacteria has become one of the biggest threats to public health in the United States and all over the world. Among the alternative antimicrobial agents, metal nanoparticles have attracted broad interests and attention due to their capabilities for suppressing the growth of bacteria and killing bacteria. However, the exact mechanisms for the antimicrobial effects of metal nanoparticles remain poorly understood. This project will establish the fundamental mechanisms of the antimicrobial behavior of metal nanoparticles as alternatives to commonly prescribed antibiotics. The research team will develop and use advanced imaging tools and techniques with superior spatial and temporal resolution to investigate the interactions between individual live bacteria and silver nanoparticles and obtain knowledge of silver nanoparticles' antimicrobial effects. Results from this research will provide guiding principles on the design and production of metal nanoparticles for antimicrobial applications in food safety and hospital infection-treatments, thus improving U.S. public health and benefiting society. Furthermore, comprehensive education and outreach activities will be implemented to cultivate the interests of America's next generation of scientists and engineers, and provide them with experience in and knowledge of nanomaterials and their applications. This will reinforce and improve the United States' future competitive strengths in STEM fields.The goal of this research is to obtain a quantitative understanding of the antimicrobial mechanism of silver nanoparticles and their interactions with live bacteria at the single-cell level. This will be accomplished by developing methodologies using super-resolution fluorescence microscopy, which will allow the studies of individual biomolecules (e.g., proteins, DNA, and lipids) and their dynamics with a spatial resolution of 20 nanometers and a temporal resolution of 10-30 milliseconds. The goal of the research will be achieved by (1) identifying the effects of silver nanoparticles on spatial organization and function of nucleoid-associated proteins; (2) quantifying how bacterial membrane is damaged by silver nanoparticles; and (3) measuring the dependence of silver nanoparticles? effectiveness on particle shapes, charges, and surface modifications. The results from super-resolution fluorescence microscopy will be validated and complemented by conventional biological techniques and assays. This research will address the current existing controversies surrounding the antimicrobial mechanisms of metal nanoparticles, which are due in part to the lack of both temporal and spatial resolution on single live bacteria. The result will be a better understanding of the nano-bio interface at the cellular and molecular levels. This research will provide valuable, quantitative information necessary to guide the rational design and fabrication of metal nanoparticles for antimicrobial applications. The methodologies developed in this research are expected to be applicable to other nanostructures and different types of bacteria.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.