Benzimidazole-based turn-on fluorescence probe developed for highly specific and ultrasensitive detection of hypochlorite ions in living cells

Hypochlorite (ClO-), as one of the active oxygen species (ROS), plays an essential role in the cellular defence system and organism immunity. In this paper, we successfully synthesized a new 'turn-on' fluorescent probe BMF based on benzimidazole and characterized it by spectroscopic methods. The designed probe can quickly respond to ClO- with the obvious colour change from pink to colourless. Notably, the probe BMF exhibited almost no fluorescence, but showed strong fluorescence after adding ClO-, including an excellent fluorescence turn-on effect. The fluorescence turn-on phenomenon of BMF was attributed to the strong oxidation of ClO-, which severed the connecting double bond and disrupted the intramolecular charge transfer (ICT) system, plus light-induced electron transfer effect between the fluorophore and the recognition group was discontinued. In addition, the cytotoxicity assay showed that the probe had lower cytotoxicity. Based on these advantages, we demonstrated that probe BMF might be a good candidate for detecting ClO- in biological systems.