High peroxidase-like activity of metallic cobalt nanoparticles encapsulated in metal-organic frameworks derived carbon for biosensing

Encapsulating metal nanoparticles (NPs) into carbon materials is a promising strategy for the fabrication of nanozymes with high activity. Here, for the first time, the proof-of-concept is demonstrated by fabricating CoNPs embedded in NH2-MIL-88(Fe) MOFs-derived magnetic carbon (MC) through in situ reduction of cobalt precursors by NaBH4. The obtained CoNPs/MC was characterized by TEM, SEM, XPS, XRD, Raman spectrum, and FT-IR. The CoNPs/MC exhibits much higher peroxidase-like activity than pure CoNPs and magnetic carbon. The high peroxidase-like activity of the CoNPs/MC is attributed to the decomposition of H2O2 to generate center dot OH and O-2(center dot-)-radicals, resulting in TMB color reaction. Also, CoNPs/MC is robust in a wide range of pH and temperature, indicating a promising peroxidase-like candidate. On this basis, a colorimetric assay was developed by combining glucose oxidase with CoNPs/MC for glucose biosensing. The linear range for glucose detection is from 0.25 to 30 mu M with a lower detection limit of 156 nM. The CoNPs/MC-based colorimetric method has been successfully used to assay the content of glucose in real biological samples such as human serums. Our work reveals the high potential of encapsulating metal NPs into carbon materials for the fabrication of nanozymes with stable and high activity. (C) 2017 Elsevier B.V. All rights reserved.