A fluorometric and mitochondrion-targetable probe for rapid, naked-eye test of hypochlorite in real samples

Abstract Hypochlorite anion is a ubiquitous reactive molecule in the terminal disinfection systems, inflammatory stress and immune systems. Thus, rapid and visual monitoring ClO − in water and biological samples is very meaningful for water quality safety and toxicity assessment of contaminants. Herein, a colorimetric and fluorometric probe (Rh-ClO) based on rhodamine B fluorophore and thiophene-2-carbohydrazide has been unveiled and successfully utilized for ClO − detection in water samples and HeLa cells. Upon addition of ClO − , color changes of solution from colorless to pink were immediately visible to the naked-eyes, meanwhile, brilliant red fluorescence was observed under excited at UV light (365 nm). Rh-ClO displayed high selectivity and sensitivity for ClO − , and the detection limit was 7 μmol/L calculated from the fluorescence titration. With the aid of its merits including rapid response to ClO − within 10 s, Rh-ClO and its test paper could successfully detect ClO − in water. Additionally, HeLa cells image co-stained with Rh-ClO and Rh123 demonstrated that Rh-ClO possessed excellent and fast cell-membrane permeability and mitochondrion-targetability. It was clearly confirmed that Rh-ClO would be a promising probe for rapid tracking of ClO − in water samples and in mitochondria of living cells.