Polyvinylpyrrolidone‐Stabilized Blue‐Emitting Copper Nanoclusters as Fluorescence Probe for Selective Detection of Dopamine

Abstract Dopamine (DA), a critical catecholamine in mammals, functions as a significant biological indicator for specific diseases. The precise and timely identification of DA is essential for disease monitoring and prevention. In this study, copper nanoclusters (Cu NCs) were synthesized using polyvinyl pyrrolidone (PVP) as the protective ligand and L‐ascorbic acid (L‐AA) as the reducing agent via a simple hydrothermal process. The produced PVP−Cu NCs displayed strong blue emission at 427 nm when excited at 365 nm. In alkaline conditions, DA was able to selectively inhibit the fluorescence of PVP−Cu NCs. The investigation of the mechanism revealed that dopamine self‐polymerization resulted in the formation of polydopamine, which inhibited the emission of PVP−Cu NCs at 427 nm due to the inner filter effect (IFE). Based on the above phenomenon, a simple and selective analytical method for DA determination was developed. The fluorescence intensity of PVP−Cu NCs demonstrated a reliable response to DA concentrations within the range of 5 to 200 μM, with a detection limit (LOD) of 1.32 μM. The proposed method was successfully utilized for the precise detection of DA in human urine samples, indicating its potential application in biomedical dopamine detection.