CdSe-ZnS quantum dots for selective and sensitive detection and quantification of hypochlorite.

Four types of water-soluble quantum dots (QDs) grafted with different organic coating layers were fabricated, and their sensitivities for hypochlorite/hypochlorous acid (HClO) were examined. It was found that QDs with HClO reactive (methylamino and sulphide groups) coating layers exhibited a protective effect on HClO quenching of QD fluorescence, whereas QDs with hydrocarbon and carboxylate coating layers showed least protection to QD fluorescence quenching by HClO and, thus, has the highest sensitivity for the detection of HClO. The QDs with carboxylate coating layers (QDs-poly-CO(2)(-)) was successfully applied to the quantification of HClO in tap water. The excellent selectivity of the QDs-poly-CO(2)(-) toward hypochlorite against other reactive oxygen species allowed us to monitor myeloperoxidase activity. Finally, the QDs-poly-CO(2)(-) was also used for the detection of hypochlorite in HL60 cells by fluorescent imaging. Hence, QD-poly-CO(2)(-) exhibits great promise as a selective and sensitive HClO probe in chemical and biological systems.