Controllable Coumarin-Based NIR Fluorophores: Selective Subcellular Imaging, Cell Membrane Potential Indicating and Enhanced Photodynamic Therapy

Fluorescent materials with advanced functionalities provide powerful tools to visualize subcellular microstructures and monitor subcellular dynamic functions, which significantly boost our understanding of complex biological phenomena and manipulation of biological behaviors. However, realization of diverse biological applications from single molecular backbone is still a challenging endeavor. In this contribution, a series of coumarin-based cationic fluorophores (Cou-n, n = 1 to 4) with near-infrared emission (675 nm) and large Stokes shifts (110 nm) have been developed. Benefited to their excellent biocompatibilities and alkyl chain dependent lipophilicities, Cou-1 and Cou-3 could selectively and ultra-fast (< 30 s) stain the cell plasma membrane and mitochondria in washing-free manner, respectively. Meanwhile, Cou-1 could sensitively response the change of plasma membrane potential, which enabled Cou-1 to successfully indicate the cell passage number. Taking advantages of specific mitochondria targetin...