Direct Growth of Poly-Glutamic Acid Film on Peroxidase Mimicking PCN-222(Mn) for Constructing a Novel Sensitive Nonenzymatic Electrochemical Hydrogen Peroxide Biosensor

Abstract

Metalloporphyrinic frameworks have demonstrated to be an alternative candidate for natural enzymes due to their diverse structures and unique peroxidase-mimicking properties. In this study, a manganese–metalloporphyrin framework (PCN-222(Mn)) was synthesized as a biomimetic metal–organic framework (MOF). This catalyst exhibited highly intrinsic peroxidase-like activity with 3,3′,5,5′-tetramethylbenzidine as the chromogenic substrate. Additionally, a higher peroxidase-like activity was observed in a wider pH range (from 3.0 to 8.0), which is undoubtedly advantageous for PCN-222(Mn) to detect H2O2 under physiological and pathological environments. Based on the excellent peroxidase-mimicking activities of PCN-222(Mn), a novel hydrogen peroxide (H2O2) nonenzymic amperometric biosensor was constructed through electro-polymerizing a conductive and stable poly-glutamic acid (PGA) film on the surface of a PCN-222(Mn)-modified electrode (PGA/PCN-222(Mn)/GCE). Resulting from the synergistic activity of PCN-222(Mn) and PGA film, a sensitive, selective, and reliable method was established for H2O2 detection with a linear range of 5 × 10–7 to 1.01 × 10–3 mol/L and detection limit of 3.1 × 10–8 mol/L. In addition, PGA/PCN-222(Mn) has a long-term stability and can be used over 90 cycles without any decrease in analytical performance. These outstanding performances of the developed approach in sensitive and selective determination of H2O2 from human serum provides effective proof for its potential application in monitoring low-abundance H2O2 from complicated biological samples. This research not only expands the electrochemical applications of metalloporphyrin frameworks but also demonstrates a promising strategy for increasing the conductivity and stability of MOF-based electrode materials.

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