FeIIFeIII layered double hydroxide nanosheets (FeIIFeIII LDHNS) as an enzyme mimic for colorimetric detection of H2O2

Abstract

In this study, a new, rapid, sensitive, and convenient approach for colorimetric detection of H₂O₂ using Fe^IIFe^III layered double hydroxide nanosheets (Fe^IIFe^III LDHNS) is reported. The Fe^IIFe^III LDHNS were constructed from a mixture of divalent and trivalent Fe ions by a co-precipitation method. Fe^IIFe^III LDHNS were found to possess superior intrinsic peroxidase-like activity. They were used to catalyze the oxidation of a peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) diammonium salt in the presence of H₂O₂ to produce a blue and green solution product, respectively, that provided colorimetric detection of H₂O₂. The colorimetric detection of H₂O₂ was conveniently carried out by incubating at room temperature. Moreover, for the ABTS substrate, the experiment was facilely and successfully carried out in deionized water at a pH of approximately 5.6. The colorimetric assays displayed linearity for H₂O₂ determination by using TMB and ABTS systems in the range of 0.1–50 μM and 0.5–20 μM, respectively, and the corresponding limits of detection were found to be 0.05 μM and 0.2 μM, respectively. The catalytic reaction follows Michaelis–Menten kinetics and exhibits strong affinity towards TMB, ABTS, and H₂O₂ substrates. This selective approach could be applied for H₂O₂ detection in real milk and disinfectant samples. It is expected that there is great potential for the proposed method for exact detection of H₂O₂ in biotechnology, clinical diagnoses, the food industry, and other industries.