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.

Naphthalene-benzoindole derived two novel fluorometric pH-Responsive probes for environmental systems and bioimaging.

In this work, we designed a kind of novel fluorescent probes based on naphthalene-benzoindole conjugate derived for sensitively monitoring the pH fluctuation in environment and biological systems. In the spectral method, these two probes both show significant red shift, color change and fluorescence quenching due to the effect of intramolecular charge transfer (ICT) mechanism. Moreover, we found that the probe bearing with carboxyl group displayed a more hydrophilicity than the one bearing with hydrogen atom instead, and the former exhibits a faster response and higher fluorescence intensity. Besides, the probe bearing with carboxyl group shows lower cytotoxicity, evidences by the vitro study. It indicates that this probe has great potential in application in living cell imaging as well as pH-fluctuation monitoring.