Peroxidase-mimetic activity of a nanozyme with uniformly dispersed Fe 3 O 4 NPs supported by mesoporous graphitized carbon for determination of glucose

A Fe 3 O 4 /mesoporous graphitized carbon (Fe 3 O 4 /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 Fe 3 O 4 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 Fe 3 O 4 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 Fe 3 O 4 /m-GC. K m values for tetramethylbenzidine (TMB) and H 2 O 2 were 26.8 and 15.8 times lower than that of natural horseradish peroxidase, respectively. Taking advantage of the peroxidase-mimetic activity of Fe 3 O 4 /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. Graphical abstract Fig 1 A Schematic illustration of the preparation process of Fe 3 O 4 /m-GC, B schematic illustration of a proposed synergistic catalytic mechanism of TMB oxidation by Fe 3 O 4 /m-GC.