Multicolor Colorimetric Sensor for Detection of Omethoate Based on the Inhibition of the Enzyme-Induced Metallization of Gold Nanorods

Human eyes are highly sensitive to multiple color changes, but most reported colorimetric sensors for the detection of toxic organophosphorus pesticides (OPs) only exhibit one or two color changes. Herein, an ultrasensitive multicolor colorimetric sensor was designed for the detection of omethoate (a typical highly toxic OP) based on inhibiting alkaline phosphatase (ALP)-induced silver metallization on the surface of gold nanorods (Au NRs). The proposed assay exhibited a sensitive response to ALP with a limit of detection (LOD) of 0.53 U/L. Under the optimal condition, inhibition of the ALP activity by different omethoate concentrations caused the proposed sensing platform to exhibit a series of high-resolution rainbow-like multicolor changes with an omethoate LOD of 83.2 ng/L. The proposed assay also had a good recovery rate of 95.67–108.92% for practical samples. The proposed assay is promising for the rapid visual detection of omethoate for food safety.