A unique phenothiazine-based fluorescent probe using benzothiazolium as a reactivity regulator for the specific detection of hypochlorite in drinking water and living organisms

As a common disinfectant and an essential reactive oxygen species (ROS), hypochlorite (ClO−) plays vital roles in both water treatment and cell metabolism, but its abnormal level can cause serious harm to human health. Therefore, quantifying ClO− level in drinking water and living organisms is extremely significant. Herein, we decorated different cationic heterocycles on phenothiazine core to construct three fluorescent probes for ClO−. According to the results, only benzothiazolium moiety reasonably adjusted the electron cloud density at sulfur atom of phenothiazine core for the specific oxidation with ClO−, thus endowing the prepared probe PT-BT with a perfect selectivity for ClO−. Meanwhile, PT-BT exhibited a low detection limit (38 nM) and a fast response (within 20 s) toward ClO−. Furthermore, this probe was utilized to fabricate a ready-to-use test strip, which could quantitatively measure ClO− level in real water samples by a portable smartphone sensing platform. Notably, PT-BT targeted mitochondria efficiently, and successfully visualized endogenous ClO− in living cells and zebrafish larvae. Especially, PT-BT was able to monitor the dynamic change of ClO− level in inflammatory mice. These results strongly manifested that probe PT-BT was a promising tool for detecting ClO− in drinking water and living organisms. A unique phenothiazine-based fluorescent probe PT-BT using benzothiazolium as a reactivity regulator has been explored. PT-BT could not only quantify ClO− in real water samples by a portable smartphone sensing platform, but also monitor the dynamic level of ClO− in living cells, zebrafish larvae and inflammatory mice. [Display omitted] •A mitochondria-targeted fluorescent probe PT-BT was explored for ClO− detection.•PT-BT exhibited high selectivity, excellent sensitivity and fast response toward ClO−.•PT-BT could quantify the level of ClO− in real water samples by a portable smartphone sensing platform.•PT-BT successfully visualized the endogenous ClO− in living cells and zebrafish larva.•PT-BT was potential to monitor the dynamic level of ClO− in inflammatory mice.