A novel pyrene-based fluorescent probe for the rapid and efficient detection of Co2+ in HeLa cells and natural water samples

Excessive levels of Co2+ in the environment can cause serious diseases to humans and affect the growth of crops. Therefore, it is necessary to develop effective methods for monitoring Co2+. In the present work, a novel, low-toxic fluorescent probe, PEPA, for the rapid and efficient detection of Co2+ is synthesized. PEPA shows high sensitivity, with a limit of detection of 0.104 μM and a fast response to Co2+ (<4 min). The detection mechanism was confirmed by FT-IR, HRMS and DFT calculations. Co2+ can restrict the free rotation of the CN group and the pyrazine ring of PEPA, resulting in the enhancement of fluorescence. In addition, the recognition process of Co2+ can be realized with the naked eye (i.e., a color change from colorless to blue fluorescence). The successful detection of Co2+ in test strips and environmental water samples provides strong support for its application potential. Interestingly, the recovery rate of Co2+ detected by PEPA can reach 93% after being recovered four times. Importantly, PEPA was suitable for the fluorescence imaging of exogenous Co2+ in HeLa cells.