Electrochemical detection of omethoate and acetamiprid in vegetable and fruit with high sensitivity and selectivity based on pomegranate-like gold nanoparticle and double target-induced DNA cycle signal amplification

The study reports synthesis of gold-graphene quantum dot nanohybrid via reduction of chloroauric acid with arginine and aspartic acid-functionalized graphene quantum dot (Arg/Asp-GQD). The Arg/Asp-GQD-Au offers pomegranate-like architecture and Schottky heterojunction and was used for construction of electrochemical sensor for detection of omethoate and acetamiprid coupled with double target-induced DNA cycles. Target molecule hybridizes with aptamer DNA in duplex DNA to release auxiliary strand DNA. This triggers the DNA cycle and brings one redox probe to electrode surface. By the DNA cycle, one target molecule can transfer many redox probes to electrode surface and produces a significant signal amplification. The detection signal was enhanced by catalysis of Arg/Asp-GQD-Au toward redox of these probes due to its excellent catalytic activity. Differential pulse voltammetric peak current linearly increases with increasing target concentration between 5 × 10−14 and 5 × 10−10 M with detection limit of 1.67 × 10−14 Μ (S/N = 3) for omethoate and between 1 × 10−14 and 5 × 10−10 M with detection limit of 3.33 × 10−15 M (S/N = 3) for acetamiprid. The proposed method provides a much better sensitivity and selectivity and was successfully applied to detection of omethoate and acetamiprid in vegetable and fruit.