Meso-pyridinium substituted BODIPY dyes as mitochondria-targeted probes for the detection of cysteine in living cells and in vivo

Cysteine (Cys) is a crucial bio-thiol attributing to its significant role in many physiological and pathological processes and maintaining redox dynamic balance. In mitochondria, ROS can cause oxidative damage, and Cys can solve this problem by acting as an antioxidant. Herein, we designed and synthesized a series of meso-pyridin and meso-pyridinium substituted BODIPY dyes as fluorescent probes to distinguish Cys. Through screening the responsive behaviors of the all probes toward biothiols, we obtained an appropriate mitochondria-targeted probe BDP-S-o-Py+ for Cys-specific detection. Density functional theory (DFT) calculations were used to demonstrate the different reactivity of the probes. BDP-S-o-Py+ could detect Cys with fast response under biological environment. The probe BDP-S-o-Py+ had a low limit of detection (LOD, 72 nM) at the linear dynamic range from 0 to 50 μM. In particularly, BDP-S-o-Py+ could be used for imaging of mitochondrial Cys in living cells, and was capable of monitoring endogenous Cys in vivo, successfully.