Polyoxometalate-incorporated metal–organic frameworks as electrochemical sensors for ascorbic acid, dopamine and uric acid

Real-time analysis of small-molecule metabolites such as ascorbic acid (AA), dopamine (DA), and uric acid (UA) is valuable for investigating biological systems and supporting disease diagnosis. As a representative metal-organic framework (MOF), MIL-101(Cr) combines strong chemical stability with a large specific surface area, demonstrating considerable potential in numerous fields. Herein, we demonstrated a series of polyoxometalate (POM)-incorporated bimetallic MOF composites, MIL-101(Cr₂Fe)-POM-T (POM = SiW₁₂ or PW₁₂, T = 180 or 220), which were evaluated as electrochemical sensors for measuring AA, DA, and UA. Among them, MIL-101(Cr₂Fe)-PW₁₂-220 delivered the strongest electrochemical sensing response in 0.1 M PBS (pH = 7.0). After optimization, MIL-101(Cr₂Fe)-PW₁₂-220 demonstrated a broad linear detection range (412−6550, 1−160, and 2−160 μM) and low limits of detection (51.1, 0.385, and 0.644 μM, S/N = 3) when AA, DA, and UA were measured individually. In addition, MIL-101(Cr₂Fe)-PW₁₂-220 also enabled AA, DA, and UA analysis in human serum samples, supported by its broad linear range, low detection limits, selectivity, and stability.