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

细菌的抗生素耐药性已经成为美国乃至全世界公众健康面临的最大威胁之一。其中，金属纳米颗粒由于具有抑制细菌生长和杀灭细菌的能力而引起了广泛的关注。然而，金属纳米颗粒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先进的成像工具和技术，具有优越的空间和时间分辨率，以研究单个活细菌与纳米银的相互作用，并获得纳米银的抗菌作用的知识。这项研究的结果将为设计和生产用于食品安全和医院感染治疗的抗菌金属纳米颗粒提供指导原则，从而改善美国公众健康，造福社会。此外，将实施全面的教育和推广活动，以培养美国下一代科学家和工程师的兴趣，并为他们提供纳米材料及其应用的经验和知识。这将加强和提高美国未来在STEM领域的竞争优势。本研究的目的是在单细胞水平上定量了解银纳米颗粒的抗菌机制及其与活菌的相互作用。这将通过开发使用超分辨率荧光显微镜的方法来完成，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和脂质）及其动力学。研究目标将通过以下途径实现：(1)确定银纳米粒子对核相关蛋白空间组织和功能的影响；(2)量化纳米银对细菌膜的破坏；(3)测定纳米银的依赖性？对粒子形状、电荷和表面修饰的影响。超分辨率荧光显微镜的结果将通过传统的生物技术和分析得到验证和补充。本研究将解决目前围绕金属纳米颗粒抗菌机制存在的争议，这些争议部分是由于缺乏对单个活细菌的时间和空间分辨率。结果将在细胞和分子水平上更好地理解纳米生物界面。这项研究将为指导合理设计和制造用于抗菌应用的金属纳米颗粒提供有价值的定量信息。本研究开发的方法有望应用于其他纳米结构和不同类型的细菌。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.