A Dipeptide-derived Dansyl Fluorescent Probe for the Detection of Cu²⁺ in Aqueous Solutions

A novel dansyl-based fluorescent probe (DG) was designed via the introduction of a dipeptide, glycyl-L-glutamine. DG showed good selectivity and sensitivity towards Cu²⁺ in aqueous solutions in the pH span of ~ 6-12. The coordination of Cu²⁺ with the dipeptide moiety led to the fluorescent quenching of the dansyl fluorophore. The association constant value for Cu²⁺ was 0.78 × 10⁴ M^- 1 in a 1 to 1 stoichiometric ratio. The detection limit in HEPES buffer solution (10 mM, pH 7.4) was 1.52 µM. DG also showed strong anti-interference capability in the presence of other metal ions. It was worth noting that DG maintained the detection ability towards Cu²⁺ in real water samples and cell imaging, implying the potential application opportunities in complicated environments.