An oligothiophene-based "turn-on" fluorescent probe: Ultrasensitive detection and bioimaging of hypochlorite in environmental and living systems.

Hypochlorite (ClO-) is widely used for disinfection and sterilization but its overuse poses risks to environmental and food safety as well as human health. Developing effective detection tools is therefore of great importance. Herein, we report an oligothiophene-based fluorescent probe 2TS for ClO- detection in environmental and biological samples. 2TS exhibits a highly specific "turn-on" fluorescence response to ClO- with rapid response (<10 s), excellent sensitivity (LOD = 6.3 nM), good photostability (≥6 h), and wide pH tolerance (4-10). 2TS not only permits sensitive and quantitative ClO- determination in water, bleach, disinfectant, and soil matrices with satisfactory recoveries (97.20-102.20%), but also facilitates on-site visual detection of ClO- in fresh produce, thereby contributing to food safety monitoring. 2TS-loaded test strips allow rapid naked-eye detection of ClO- in aqueous media, and smartphone-assisted RGB analysis further provides instrument-free quantitative detection on food surfaces and test strips. Moreover, its good biocompatibility enables real-time bioimaging of ClO- in living cells, onion tissues, and zebrafish. This work offers a simple and effective fluorescent tool for visual monitoring and bioimaging of ClO- in diverse environmental and biological systems.