Stimulated emission depletion microscopy provides a powerful sub-diffraction imaging modality for life science studies. Conventionally, stimulated emission depletion requires a relatively high light intensity to obtain an adequate depletion efficiency through only light-matter interaction. Here we show efficient emission depletion for a class of lanthanide-doped upconversion nanoparticles with the assistance of interionic cross relaxation, which significantly lowers the laser intensity requirements of optical depletion. We demonstrate two-color super-resolution imaging using upconversion nanoparticles (resolution ~ 66 nm) with a single pair of excitation/depletion beams. In addition, we show super-resolution imaging of immunostained cytoskeleton structures of fixed cells (resolution ~ 82 nm) using upconversion nanoparticles. These achievements provide a new perspective for the development of photoswitchable luminescent probes and will broaden the applications of lanthanide-doped nanoparticles for sub-diffraction microscopic imaging.

中文翻译：

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通过在上转换纳米粒子中采用交叉弛豫来实现高效发射耗尽纳米技术。

受激发射耗竭显微镜为生命科学研究提供了强大的亚衍射成像模态。常规地，受激发射耗尽需要相对高的光强度以仅通过光-物质相互作用来获得足够的耗尽效率。在这里，我们展示了借助离子间交叉弛豫技术对一类镧系元素掺杂的上转换纳米粒子的有效发射损耗，这大大降低了光学损耗对激光强度的要求。我们演示了使用上转换纳米粒子（分辨率约66 nm）和一对激发/耗尽光束的双色超分辨率成像。此外，我们显示了使用上转换纳米颗粒的固定细胞免疫染色细胞骨架结构的超分辨率成像（分辨率〜82 nm）。