Organic-Nanowire-SiO₂ Core-Shell Microlasers with Highly Polarized and Narrow Emissions for Biological Imaging

Development of luminescence probes with polarized and narrow emissions simultaneously is helpful for removing multiply scattered light and enables multiplexing detection, but it remains challenging to use conventional organic dyes, fluorescence proteins, and quantum dots. Here, we demonstrated smart one-dimensional microlaser probes (MLPs) by coating a thin layer of silica shell on the surface of organic nanowires (ONWs) of 1,4-dimethoxy-2,5-di[4'-(methylthio)styryl]benzene (TDSB), namely, ONW@SiO₂ core-shell structures. Different from the Fabry-Pérot (FP) cavity formed between two end-faces of semiconductor nanowires, whispering gallery mode (WGM) microresonators are built within the rectangular cross section of ONW@SiO₂ MLPs. This enables a lasing threshold as low as 1.54 μJ/cm², above which lasing emissions are obtained with a full width at half-maximum (fwhm) < 5 nm and a degree of polarization (DOP) > 83%. Meanwhile, small dimensions of ONW@SiO₂ MLPs with a side-length of ca. 500 nm and a length of 3-8 μm help to reduce their perturbations in living cells. With the help of mesoporous silica shells, which provide both high biocompatibility and good photostability, ONW@SiO₂ MLPs can be easily introduced into the cell cytoplasm through natural endocytosis. Using their narrow and highly polarized lasing emissions in vitro, we demonstrate that it is possible to tag individual cells using ONW@SiO₂ MLPs with high stability.