Facile preparation of four-in-one nanozyme catalytic platform and the application in selective detection of catechol and hydroquinone

Development of nanomaterials with multienzyme-like activities (nanozymes) via a simple way has attracted paramounting attention. Generally, enzymatic activity is closely related to the size, surface state, material type, etc. Bimetallic oxides are very appealing owing to their mixed valence and structural advantages. Herein, we reported an eco-friendly strategy to synthesize Co1.5Mn1.5O4 nanozyme via sol-gel method. This nanozyme functionally mimics four major enzymes, i.e. laccase, peroxidase (POD), oxidase (OXD), and catalase (CAT). Accordingly, a colorimetric sensing platform was designed to distinguish isomers of organic pollutants ‒catechol (CC) and hydroquinone (HQ) by using Co1.5Mn1.5O4 as the sole catalyst. In particular, laccase-like activity of Co1.5Mn1.5O4 enables it to directly oxidize CC into yellow o-benzoquinone with good linearity in the range of 1∼1000 μM and a detection limit of 0.35 μM. Meanwhile, HQ can discolor the oxidized substrate that was pre-oxidized with the aid of oxidase-like activity of the nanozyme (linear range: 0.05∼100 μM, detection limit: 0.04 μM). The established colorimetric method has been successfully utilized for selective sensing of CC, HQ in water samples with good selectivity and high sensitivity. Our study contributes to green synthesis of metal-based nanomaterials with multi-enzyme mimicking activities and uncovers new usage of nanozyme in discriminating of environmental pollutants.