Highly Active Single-Atom Nanozymes with High-Loading Iridium for Sensitive Detection of Pesticides

Abstract

Single-atom nanozymes (SAzymes) are novel mimic-enzyme materials with atomically doped active sites. They play a pivotal role in the field of nanozymes because of their excellent catalytic activities, high utilization efficiency of the metal atoms, and simple model of active sites. Herein, the peroxidase (POD)-like SAzymes with high-loading iridium (Ir) (5.31%) on graphene oxide (GO) nanosheets [Ir­(III)/GO] were prepared through a coordination reaction between the Ir­(III) complex and the oxygen-containing groups in GO. The preparation strategy avoids nitrogen doping and pyrolysis procedures which are the usually used strategies to improve the GO-based enzyme mimic activity. Ascribed to the highly active Ir atoms, Ir­(III)/GO SAzymes demonstrate outstanding POD-like activity without the oxidase-like activity. In advantage of the excellent POD-like activity, a simple and sensitive colorimetric pesticide detection platform is established. The developed sensing platform offers an excellent “switch-on” pirimicarb (PIB) detection in the linear range of 10–300 nM with a limit of detection (LOD) of 2.81 nM. Moreover, the detection platform was fabricated into a portable test kit, which is composed of a test swab and sample processing tube. In the aid of a color-reading APP, the test kit can detect PIB with the LOD of 3.31 nM. It is astonishing to get this excellent detection sensitivity just using the simple colorimetric strategy. This work not only provides a novel strategy to synthesize Ir-based SAzymes but also exhibits the super capability of Ir­(III)/GO in the biosensing field.

Regulating Second Coordination Shell of Ce Atom Site and Reshaping of Carrier Enable Single-Atom Nanozyme to Efficiently Express Oxidase-like Activity

“…Next, PEG@P@Ce–N/S–C was constructed into a detection kit using medical swabs as carriers (Figure D). The flocking texture on medical swabs has better coloring ability and water absorption than traditional visualization devices such as test strips . The signal is characterized by a gradual fading of the swab as BuChE activity increases.…”

Nanozymes: powerful catalytic materials for environmental pollutant detection and degradation

“…190 With low cost, excellent stability, and robust performance, nanomaterials with peroxidase- or oxidase (OXD)-like activities can be integrated with bioenzymes to fabricate natural enzyme–nanozyme cascade systems for pesticide detection. 157–163,165–177,191 Very recently, we explored an Fe-based phosphotungstate (Fe-PTs) with a notable peroxidase-like feature at neutral pH to establish a portable multi-enzyme biosensor for pesticide analysis. 176 The electrostatic interaction between positively charged TMB and negatively charged Fe-PTs as well as the promoted regeneration of Fe 2+ was supposed to play crucial roles in enabling the material to show favorable peroxidase-mimetic activity under neutral conditions.…”