Rapidly and ultra-sensitive colorimetric detection of HO and glucose based on ferrous-metal organic framework with enhanced peroxidase-mimicking activity.

In this article, a novel metal-organic framework, namely MIL-101(Fe), was firstly synthesized via a facile method. In the presence of HO, MIL-101(Fe) possesses excellent peroxidase-like activity toward the classical chromogenic substrate, N,N-Diethyl-p-phenylenediamine sulfate salt (DPD). The substitution of Fe enhances the construction of Fe(II)-oxo nodes and accelerates electrons transfer between DPD and HO, thereby improving the peroxidase-mimicking catalytic activity of MIL-101(Fe) nanoenzyme. Additionally, DPD molecules could be adsorbed readily onto the surface of the nanoparticles due to the π-π interaction. The study of Michaelis constant indicates that the MIL-101(Fe) exhibits a higher affinity towards DPD (0.16 mM) in contrast to horseradish peroxidase (0.78 mM). In view of the impressive catalytic performance of MIL-101(Fe), two reliable monitoring platforms for the rapid detection of HO and glucose were established with extremely low detection limits of 18.04 nM and 0.87 μM in the ranges of 40-5000 nM and 1.2-300 μM, respectively. The study of the catalytic mechanism indicates that DPD oxidation is attributed to the hydroxyl radical (·OH) produced from the decomposition of HO catalyzed by MIL-101(Fe). Furthermore, the developed sensor indicates high selectivity and stability and can be effectively appropriate for the detection of HO and glucose in real samples. This work not only provides a novel nanozyme with superior catalytic performance for biological analysis, but also broadens the application field of MIL-101(Fe) material.