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Hierarchically structured Fe3O4-doped MnO2 microspheres as an enhanced peroxidase-like catalyst for low limit of detection

Wang, Jianzhi, Huang, Fei, Wang, Xianming, Wan, Yinjia, Xue, Yanan, Cai, Ning, Chen, Weimin, Yu, Faquan
Process biochemistry 2019 v.83 pp. 35-43
X-ray diffraction, catalysts, catalytic activity, detection limit, enzyme kinetics, glucose, hot water treatment, hydrogen peroxide, iron oxides, manganese dioxide, microparticles, nanoparticles, synergism, transmission electron microscopy
In order to lower the limit of detection of glucose, a peroxidase-like artificial enzyme with elevated catalysis capacity has been achieved. Fe3O4-doped MnO2 microspheres were fabricated through a two-step hydrothermal method for this purpose. TEM revealed that down-sized Fe3O4 nanoparticles were dispersed throughout the urchin-like MnO2 burrs. An additional XRD peak beyond Fe3O4 and MnO2 nanoparticles was observed, indicating a dislocation structure was formed. The defect in structure as well as the synergistic effect would allow extra enzyme ability. Based on the steady-state kinetic analyses and Michaelis–Menten model, the Michaelis–Menten constants (Km and vmax) were figured out. The results showed that the Fe3O4–MnO2 composite has elevated affinity toward the substrate TMB and H2O2. The limit of detection for glucose was estimated to be 0.75 μmol L−1 based on the Fe3O4–MnO2 composite artificial enzyme. The superparamagnetic properties endowed the material easy separation. The composite of this structure will provide a highly sensitive candidate method for accurate detection of glucose.