Tyrosine-Decorated Gold Nanoclusters Chelated Cerium(III) for Fluorescence Detection of Dopamine

In this work, a tyrosine-decorated gold nanocluster (Tyr-GNC)–cerium(III) complex was established for the fluorescent detection of dopamine (DA). Tris–HCl buffer was used for synthesizing Tyr-GNC; thus, Tyr-GNC could emit fluorescence even under neutral conditions. The quantum yield (QY) of Tyr-GNC was 13.3%. Trivalent cerium ions (Ce³⁺) chelated hydroxyl and amino groups of tyrosine to form GNC–Ce³⁺. Also, DA showed a higher quenching efficiency in the fluorescence of GNC–Ce³⁺ than that of GNC. The mechanism was that Ce³⁺ chelated with DA and promoted its oxidative self-aggregation under alkaline buffer, and, at the same time, the oxidative product quenched the fluorescence of Tyr-GNC by the inner filter effect (IFE). In DA detection, GNC–Ce³⁺ showed a wide detection range (0.1–1000 μM) and a low detection limit (10.85 nM) for DA with high selectivity. The platform was successfully applied to DA detection in human plasma. This work proposed insight into the interaction between GNC–Ce³⁺ and DA, which has broad application prospects in clinical diagnosis.