OP: Super-resolution imaging of plasmon-molecule interactions

光学显微镜，如那些发现在几乎每一个高中看细胞，有一个固有的限制，其空间分辨率。它们无法分辨两个距离比光波长更近的物体，可见光的波长约为500 nm，或约为人类头发直径的1/100。最近，超分辨率显微镜已经开发出来，可以分辨相距仅10 nm的单个分子。超分辨率显微镜在成像其他分子（如蛋白质）附近的荧光染料时取得了巨大的成功，但当分子位于金属纳米结构附近时，它就有麻烦了。当分子与金属中松散的电子相互作用时，问题就出现了，这模糊了它的位置。在化学系大分子，超分子和纳米化学项目的支持下，坦普尔大学的Willets教授正在研究荧光分子与金属纳米颗粒的相互作用。Willets教授和她的学生正在开发能够更好地确定荧光分子位置的方案。 该项目可以为生产更高保真的超分辨率图像铺平道路，这可能有助于推进生物传感，纳米医学和太阳能转换的纳米技术。这项工作还为研究生和本科生提供培训机会，促进国家科学劳动力的发展。此外，Willets实验室还积极参与费城市中心Freire Charter School九年级的科学课程，帮助学生培养对科学探索和发现的欣赏。Willets教授与她的学生一起工作，用荧光标记的DNA在特定位置功能化金纳米棒和纳米球。 然后使用超分辨率成像和偏振分辨显微镜的组合来跟踪荧光分子的位置和取向如何影响荧光分子的定位精度。 在超分辨率成像中，通过将单个荧光分子的衍射限制发射拟合到模型函数（例如二维高斯）来定位单个荧光分子，以以优于10 nm的精度定位它们的空间位置。 然而，荧光发射体和纳米结构的等离子体振子模式之间的耦合影响定位精度，导致荧光分子的计算位置从其真实位置偏移。 理论建模提供了对单个分子相对于等离子体纳米结构的位置和取向如何影响定位误差的洞察。 通过创建定义明确的混合有机等离子体纳米粒子，该团队正在开发新的分析工具，以提取隐藏在荧光图像中的信息，以提高超分辨率图像与实际纳米结构属性之间的一致性。该奖项反映了NSF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。

Optical microscopes, such as those found in almost every high school to look at cells, have an inherent limit to their spatial resolution. They cannot resolve two objects that are closer to each other than the wavelength of light, which for visible colors is about 500 nm, or about 1/100 the diameter of a human hair. Recently super-resolution microscopes have been developed that can resolve individual molecules that are only 10 nm apart. Super-resolution microscopy has had tremendous success when imaging fluorescent dyes near other molecules, such as proteins, but it has trouble when the molecule is located near a metal nanostructure. The problem arises when the molecule interacts with the loosely held electrons in the metal, which blurs its location. With support from the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Willets at Temple University is studying the interaction of fluorescent molecules with metal nanoparticles. Professor Willets and her students are developing protocols that can better pinpoint the location of the fluorescent molecule. The project could pave the way to producing higher fidelity super-resolution images, which may help to advance nanotechnologies for biosensing, nanomedicine, and solar energy conversion. The work also provides training opportunities for graduate and undergraduate students, furthering the development of the Nation's scientific workforce. In addition, the Willets lab is actively engaged with the 9th grade science classes at Freire Charter School in downtown Philadelphia, helping the students to foster an appreciation for scientific exploration and discovery.Working alongside her students, Professor Willets is functionalizing gold nanorods and nanospheres at specific sites with fluorescently-labeled DNA. A combination of super-resolution imaging and polarization-resolved microscopy is then used to track how the position and orientation of the fluorescent molecules impacts the localization precision of the fluorescent molecule. In super-resolution imaging, single fluorescent molecules are localized by fitting their diffraction-limited emission to a model function, such as a two-dimensional Gaussian, to localize their spatial position with better than 10 nm precision. However, coupling between the fluorescent emitter and the plasmon modes of the nanostructure impacts the localization accuracy, resulting in the calculated position of the fluorescent molecule being shifted from its true position. Theoretical modeling provides insight into how the position and orientation of a single molecule relative to the plasmonic nanostructure affects the localization error. By creating well-defined hybrid organic-plasmonic nanoparticles, the team is developing new analysis tools to extract information hidden in the fluorescence images to improve agreement between the super-resolved images and the actual nanostructure properties.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.