FeNPs@Co3O4 hollow nanocages hybrids as effective peroxidase mimics for glucose biosensing

Abstract

Constructing hollow mesoporous nanostructures for dispersing catalytically active sites has attracted growing interest. Here, for the first time, Co3O4 hollow nanocages (Co3O4 HNCs) derived from ZIF-67 were prepared for loading iron nanoparticles (FeNPs), resulting in FeNPs@Co3O4 hollow nanocages (FeNPs@Co3O4 HNCs). FeNPs@Co3O4 HNCs were characterized by SEM, TEM, XRD, XPS and FT-IR. The FeNPs@Co3O4 HNCs composites could catalyze the oxidation of TMB into blue product by H2O2, showing better peroxidase-like activity than FeNPs and Co3O4 HNCs. Notably, kinetic studies indicated that FeNPs@Co3O4 HNCs behaved an excellent affinity to H2O2 with Km value of 0.019 mM, which was 195 times lower than that of HRP. On this basis, a facile colorimetric biosensing method was established to detect glucose. The linear range was 0.5–30 μM, and the limit of detection was 0.05 μM. The proposed sensor was successfully used to determine glucose in human serum samples. The highly catalytic performance of FeNPs@Co3O4 HNCs is attributed to its porous hollow structure, which is beneficial for dispersion of in situ formed FeNPs and for reducing the agglomeration. Further, the FeNPs@Co3O4 HNCs catalysts with porous character provide an essential way to expose active sites as far as possible to the substrate and increase the catalytic active sites.