Fluorescent probe for Cu²⁺ and the secondary application of the resultant complex to detect cysteine

A special fluorescent probe has been developed, one that demonstrated excellent "off-on-type" change in fluorescence with high selectivity toward Cu²⁺. Interestingly, the probe-Cu²⁺ complex could detect cysteine due to the ability of this amino acid to strongly coordinate Cu²⁺, and no obvious interference was observed from other amino acids and anions. According to the proposed mechanism, addition of cysteine induced decomplexation of the probe-Cu²⁺ form. Furthermore, the results of confocal microscopy experiments demonstrated the potential of using the probe to image Cu²⁺ in living cells and mice.