We discuss two fronts of our research that demonstrate the new possibilities of optical microscopy for materials and biological systems, respectively. On one front, we developed a facile, label-free approach based on interference reflection microscopy (IRM) to record the in situ reaction dynamics of graphene with ~300 nm spatial resolution and video-rate temporal resolution. We thus reveal rich spatiotemporal heterogeneities in the redox reactions of graphene, as well as elucidate how such reactions may be effectively driven in a reversible, controlled manner by electrochemistry. Moreover, we report light-assisted diazonium functionalization of graphene, and show drastically different local reaction rates for different graphene structures and light wavelengths. On a different front, we recently developed single-molecule displacement/diffusivity mapping (SMdM), a super-resolution method that enables the nanoscale mapping of intracellular diffusivity through determining the instantaneous displacements of single fluorescent protein molecules freely diffusing inside the cell. We thus show that diffusion in the cytoplasm and in the nucleus to both be spatially heterogeneous at the nanoscale, and identify positive net charge as an overlooked key factor for intercellular diffusion slowdown.

Optical microscopy of dynamic systems: From graphene reactions to intracellular diffusion

2019 Fall National Meeting

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