A new colorimetric and near-infrared fluorescent probe for biothiols and its application to image GSH in living cells and zebrafish

A new near-infrared (NIR) fluorescent probe based on 2-Methylchromone was exploited for relay recognition of Cu 2+ and biothiols. The mechanism involved in complex between metal ion and probe, and subsequent displacement reaction, which make the probe can detect GSH by NIR fluorescence turn on emission. Probe showed a fluorescence band at 718 nm in PBS-EtOH (3:2, v/v, 10 mM PBS, pH 7.4) solution. Upon the addition of Cu 2+ , a large fluorescence quenching was observed due to the coordination between probe 1 and Cu 2+ . The 1 -Cu 2+ could be used to detect biothiols utilizing high affinity of biothiols with Cu 2+ . This “on-off-on” fluorescent probe was also successfully applied to image GSH in MCF-7 cells and zebrafish.