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Updated: Jan 26, 2026

Deep-Tissue Three-Photon Fluorescence Microscopy in Intact Mouse and Zebrafish Brain
Published on: January 13, 2022
Highly photostable two-photon NIR AIEgens with tunable organelle specificity and deep tissue penetration
Guangle Niu1, Ruoyao Zhang2, Yuan Gu3
1HKUST-Shenzhen Research Institute, No. 9 Yuexing 1st RD, South Area, Hi-tech Park, Nanshan, Shenzhen, 518057, China; Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Institute for Advanced Study, Institute of Molecular Functional Materials, And Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, China.
Abstract:
Photostability is a particularly important parameter for fluorescence imaging especially long-term dynamic tracking in live samples. However, many organic fluorophores show poor photostability under one-photon and two-photon continuous irradiation. In addition, these traditional fluorophores also suffer from aggregation-caused quenching (ACQ) in aggregate state in insolvable water environment. Therefore, it remains challenging to develop photostable and ACQ-free fluorophores for biological imaging. In this work, we developed two highly photostable aggregation-induced emission luminogens (AIEgens) based on the cyanostilbene core for in vitro and ex vivo bioimaging. These AIEgens named CS-Py+SO3- and CS-Py+ exhibit near-infrared solid-state emission, large Stokes shift (>180 nm), high fluorescence quantum yield (12.8%-13.7%) and good two-photon absorption cross section (up to 88 GM). CS-Py+SO3- and CS-Py+ show specific organelle staining with high biocompatibility in membrane and mitochondria in live cells, respectively. In addition, selective two-photon mitochondria visualization in live rat skeletal muscle tissues with deep-tissue penetration (about 100 μm) is successfully realized by using CS-Py+. Furthermore, these AIEgens especially CS-Py+ exhibit remarkably high resistance to photobleaching under one-photon and two-photon continuous irradiation. These highly photostable AIEgens could be potentially utilized in visualizing and tracking specific organelle-associated dynamic changes in live systems.
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