Fast-responsive and multi-applicable fluorescent turn-off chemodosimeter for monitoring hypochlorite: application to test strips, water samples, disinfectants and bioimaging

Due to the twin-demic of COVID-19 and flu virus, disinfectants containing ClO- have been widely used nowadays. Therefore, it is urgent to develop a sensor capable of efficiently detecting toxic hypochlorite. We present the invention and assessment of a fast-responsive and multi-applicable chemodosimeter sensor ETA (2-(2-((1E,2E)-3-(4-(dimethylamino)phenyl)allylidene)hydrazineyl)-N,N,N-trimethyl-2-oxoethan-1-aminium chloride) for monitoring ClO‑. In pure water, adding ClO- to ETA caused a turn-off fluorescence within 2 sec. These changes made it possible to quickly detect ClO- with a high level of selectivity. ETA displayed a low detection limit (0.68 μM) to ClO-. Using UV-vis titrations, ESI-MS and DFT calculations, we were able to demonstrate the detection mechanism, in which ETA was cleaved by ClO-. In particular, we established the possibility for reliable ClO- detection in environmental systems such as actual water samples, disinfectants, living cells, zebrafish and celery, in addition to confirming the practicality of ETA utilizing test strips.

Detection of environmentally hazardous hypochlorite in pure water with a novel fluorescent chemosensor: Application to water samples, commercial disinfectants, test strips, and zebrafish

With the increasing use of chlorinated disinfectants or bleaches such as sodium hypochlorite in the coronavirus disease 2019 (COVID-19) pandemic, the effectual detection of toxic hypochlorite is very important. In this study, a novel hydrazide-based fluorescence chemosensor DHT-Cl ((E)-2-(2-(3,5-dichloro-2-hydroxybenzylidene)hydrazinyl)-N,N,N-trimethyl-2-oxoethan-1-aminium chloride) was synthesized. DHT-Cl could selectively detect environmentally hazardous hypochlorite in pure water through a fluorescence turn-off process. The detection limit for hypochlorite was determined to be 0.57 μM. DHT-Cl can monitor hypochlorite with little interference even in the presence of other analytes. Practically, DHT-Cl detected hypochlorite in water samples, commercial disinfectants, test strips, and living zebrafish. The hypochlorite detection mechanism through cleavage of the CN bond was illustrated by 1H NMR spectroscopy titration, ESI-mass spectrometry and quantum calculations.