Iron and nitrogen co-doped MXene quantum dots: A novel dual-mode electrochemical and fluorescence sensor for dopamine detection

초록

Background: MXene quantum dots (MQDs) possess excellent conductivity, abundant active sites, and unique optical properties, yet their metal/heteroatom-modified sensing applications remain underexplored. Here, we report Fe- and N-co-doped MXene quantum dots (FeOMQDs) for the detection of dopamine (DA). Methods: FeOMQDs were synthesized via a one-step hydrothermal process using MXene sheets, FeCl3, and ophenylenediamine, and characterized by FTIR, TEM, and XPS. Their fluorescence and electrochemical properties were exploited for DA sensing. Significant Findings: The fluorescence sensing mechanism is governed by DA-induced quenching of FeOMQDs photoluminescence through metal-analyte complexation. The platform exhibited a linear range of 1-10 nM with a detection limit of 0.56 nM. For electrochemical analysis, FeOMQDs were immobilized on glassy carbon electrodes (GCE) and screen-printed electrodes (SPE), followed by evaluation via cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Enhanced electrocatalytic activity toward DA oxidation was observed, attributed to the synergistic interactions between Fe centers and the MXene matrix. The FeOMQDs-GCE demonstrated a linear range of 2-20 nM with detection limits of 1.8 nM (CV) and 1.09 nM (DPV), along with an extended linear range of 40-1000 nM in CV studies. The probes showed excellent reproducibility, stability, and selectivity, with reliable recovery in human serum, confirming their promise for practical bioanalytical applications.

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