▎ 摘　　要

A highly sensitive and selective approach for cobalt(II) detection based on the aggregation induced emission quenching strategy, which is opposite to aggregation induced emission enhancement, was developed using graphene quantum dots (GQDs). The detection could be achieved in the range of 10 nM-5 mM and the limit of detection was 2 nM. Importantly, the as-prepared GQDs showed a specific response to cobalt(II) with excellent stability in A549 cells owing to their good biocompatibility and longtime anti-photobleaching. Thus, these environmentally and bio-friendly carbon nanomaterials were employed to visualize and monitor significant physiological changes of living cells induced by cobalt(II). This shows great potential for in vitro analysis of cobalt(II).