Porphyrin functionalized montmorillonite Loaded Cu2O-Fe3O4 as a sustainable peroxidase nanozyme for colorimetric determination of hydroquinone

Abstract

Designing sustainable efficient peroxidase nanozymes and elucidating its peroxidase-like mechanism are very important for constructing colorimetric sensing platforms. Herein, a sustainable peroxidase nanozyme, porphyrin functionalized montmorillonite (PorMMT) loaded Cu2O-Fe3O4 nanocomposites, is prepared by the two-step hydrothermal method and can be recycled conveniently by virtue of magnetism of Fe3O4 from the composite (Cu2O-Fe3O4/PorMMT). Cu2O-Fe3O4/PorMMT peroxidase nanozyme can quickly catalyze the oxidation of the colourless substrate 3,3′,5,5′-tetramethylbiphenylamine (TMB) by H2O2 into a blue product (oxTMB) only in 3 min. Compared with pure MMT, Cu2O and Fe3O4 individual, Cu2O-Fe3O4/PorMMT exhibits the higher peroxidase-like activity. The catalytic activity of Cu2O-Fe3O4/PorMMT is reached the maximum at pH = 4 and T = 50 ℃. The catalytic behaviors of Cu2O-Fe3O4/PorMMT follow the Michaelis-Menten kinetic equation. The catalytic mechanism of Cu2O-Fe3O4/PorMMT is from the produced active species including superoxide free radicals (•O2−) and holes (h+). Based on the peroxidase-like activity of Cu2O-Fe3O4/PorMMT, a fast convenient colorimetric sensing platform has been designed to detect H2O2 and hydroquinone (HQ), respectively. H2O2 detection can be realized in the linear range of 510 mM with the limit of detection (LOD) of 2.68 mM, as well as hydroquinone (HQ) in the linear range of 550 μM with a much lower LOD of 4.37 μM. The convenient visual sensing platform has a potential application in monitoring HQ remains in lakes and rivers near dressing plants.