Peroxidase-mimetic activity of a nanozyme with uniformly dispersed Fe3O4 NPs supported by mesoporous graphitized carbon for determination of glucose

Abstract

A Fe₃O₄/mesoporous graphitized carbon (Fe₃O₄/m-GC) composite was prepared through a facile calcination method with iron-based metal-organic frameworks (Fe-MOFs) as a sacrificial template. After carbonization, the Fe₃O₄ nanoparticles were uniformly dispersed in the mesoporous carbon support, resulting in spatial structural stability. The mesoporous carbon support obtained was highly graphitized and exhibited eminent electrical conductivity, which accelerated the electron transfer between the Fe₃O₄ nanoparticles by Fe(II)/Fe(III) redox cycles and m-GC by C = C_sp2/C-C_sp3 redox cycles, leading to the excellent peroxidase-mimetic activity of Fe₃O₄/m-GC. K_m values for tetramethylbenzidine (TMB) and H₂O₂ were 26.8 and 15.8 times lower than that of natural horseradish peroxidase, respectively. Taking advantage of the peroxidase-mimetic activity of Fe₃O₄/m-GC, a colorimetric assay was fabricated for detecting glucose in the range 0.5 ~ 200 μM, with a limit of detection of 0.24 μM. Fig 1 A Schematic illustration of the preparation process of Fe₃O₄/m-GC, B schematic illustration of a proposed synergistic catalytic mechanism of TMB oxidation by Fe₃O₄/m-GC.

Keywords: Carbonization; Colorimetry; Fe3O4/mesoporous graphitized carbon; Glucose determination; Metal organic framework; Synergistic catalysis.