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.
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