CAREER: Chemical Imaging through Ultrahigh-Throughput Single-Molecule Spectroscopy and Spectrally-Resolved Superresolution Microscopy

在化学系化学测量和成像计划的支持下，加州大学伯克利分校的徐教授正在开发超高分辨率和超快化学成像的新策略。这项正在开发中的技术将使他能够获得单个分子的光谱特征，以用于识别目的以及这些分子的空间位置。此外，他的方法收集数据的速度比目前可行的速度快得多，例如，在密集样本中，数百万个单分子的位置可以在几分钟内收集到。这项技术一旦开发出来，将成为在复杂环境中研究单分子的一种非常强大的方法。例如，它可以用来研究纳米级分子的不均匀分布，或者实时监测分子与纳米结构的相互作用，这是现有技术还无法实现的。这种新的测量能力将在化学、生物物理学、细胞生物学和材料科学中得到许多应用。徐教授还对将他从研究中学到的东西融入到他的教学中感兴趣。他正在为感兴趣的学生开发先进显微镜和单分子光谱学的新课程。他还热衷于指导学生，特别是那些来自代表人数较少的少数群体的学生，在校园里担任董事和校长(RC)和加州机会(CalOp)学者的教师导师。徐教授和他的研究生正在与当地的志愿者项目湾区学校科学家(BASIS)合作，为当地贫困的公立学校开发新的科学演示和教材。徐教授正在努力克服现代超高分辨率光学成像技术的局限性，将单分子光谱学的空间、时间和光谱维度结合在一起。事实上，目前测量单分子荧光光谱的方法受到吞吐量和空间分辨率低的限制。与此同时，新兴的超分辨率显微镜方法提供了出色的空间分辨率，但没有光谱信息。通过开发一种新的方案，在广域内对单分子的荧光进行光谱分散，并通过光开关实现分子的稀疏性，徐的方法能够以超高吞吐量(几分钟内达到数百万个分子)实现同时的光谱测量和单分子的超局部化。这种光谱分辨的超分辨率显微镜能力将提供大量单分子的光谱信息以及纳米空间分辨率。因此，它可以对单分子在不同化学环境中的行为进行询问，对脂质双层和细胞膜进行建模，并以光谱和空间分辨的方式揭示等离子体纳米结构增强单分子荧光的机制。

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Xu at University of California, Berkeley, is developing new strategies for super high resolution and super fast chemical imaging. The technique in development will allow him to obtain spectral signatures of individual molecules for identification purposes as well as the spatial location of these molecules. Moreover, his approach collects data at a much faster speed than what currently feasible, e.g positions of millions of single molecules in dense samples can be collected in minutes. The technique, once developed, will be a very powerful approach for the study of single molecules in a complex environment. For example, it can be used to study uneven distribution of molecules at nanometer scales or to monitor molecule-nanostructure interactions in real time, which cannot yet be achieved by existing techniques. This new measurement capability will find many applications in chemistry, biophysics, cell biology, and materials science. Professor Xu is also interested in integrating what he learns from research into his teaching. He is developing new courses on advanced microscopy and single-molecule spectroscopy for students who are interested. He is also passionate in mentoring students, especially those from underrepresented minority groups, by serving as a Faculty Mentor to Regents' and Chancellor's (RC) and Cal Opportunity (CalOp) Scholars on campus. Professor Xu and his graduate students are teaming up with Bay Area Scientists in Schools (BASIS), a local volunteer program, to develop new science demos and teaching materials for local, underprivileged public schools.Professor Xu is working to overcome the limitations of modern super high resolution optical imaging techniques by bringing together the spatial, temporal, and spectral dimensions of single-molecule spectroscopy. Indeed, current approaches for the measurement of the fluorescence spectra of single molecules are limited by low throughput and spatial resolution. Meanwhile, emerging super-resolution microscopy methods offer outstanding spatial resolution but no spectral information. Through the development of a new scheme to spectrally disperse the fluorescence of single molecules in the wide-field and achieving molecular sparseness via photoswitching, Xu's approach enables concurrent spectral measurement and super-localization of single molecules with ultrahigh throughput (millions of molecules in a few minutes). Such spectrally-resolved super-resolution microscopy capabilities would offer spectral information for large amount of single molecules together with nanometer spatial resolution. It can therefore enable the interrogation of the behavior of single molecules in different chemical environments, modeling lipid bilayers and cell plasma membranes, and revealing, in a spectrally and spatially resolved fashion, the mechanisms of single-molecule fluorescence enhancement by plasmonic nanostructures.