The construction of peroxidase-like Cu-BDC@FeMo6 for colorimetric detection of H2O2 and dopamine

Artificial mimic enzymes have attracted wide attention for their superior characteristics to natural enzymes in extensive applications of diagnosis and therapy. In this paper, a nanozyme Cu-BDC@FeMo6 was designed and fabricated by embedding polyoxometalate (NH4)3[FeMo6O18(OH)6]·6H2O (FeMo6) into a copper-based metal–organic framework (Cu-BDC). The integration of FeMo6 and Cu MOF based on the synergies of oxidability of FeMo6 and oxygen-driven reversible Cu+/Cu2+ enhanced the peroxidase mimicking activity, which accomplished the sensitive visual monitoring of H2O2 and dopamine (DA). The detection of H2O2 was driven by Cu-BDC@FeMo6 catalyzing the oxidation of TMB with colorimetric evolution to blue, and consecutive monitoring DA via the reverse process of reduction of ox-TMB was further achieved. The limit of detection (LOD) of H2O2 and DA were 10 μM and 2.27 μM, with excellent stability, and outstanding selectivity. The mechanism of the catalysis was further evaluated, and the generation of O2·- played a crucial role in the catalysis for oxidation. The logic gate design was constructed to illustrate the process and application. This work provides a feasible reference for the reasonable design of simulated enzyme in biosensor applications.