A graphene quantum dot-based fluorescent nanoprobe for hypochlorite detection in water and in living cells

The authors describe a fluorometric nanoprobe for hypochlorite ion. It was prepared by covalently linking o-phenylenediamine to graphene quantum dots (GQDs). The probe displays green fluorescence with excitation/emission peaks at 440/534 nm. In the presence of chlorite, oPD is oxidized to form a quinone-iminium compound which induces a reduction in fluorescence intensity. The nanoprobe enables chlorite to be determined with a 69 nM limit of detection. The probe is highly selective, well water soluble and biocompatible. It was successfully employed in the determination of chlorite in spiked tap water and living cells. The method is believed to represent a promising tool for the determination of chlorite in environmental, biological and clinical samples.