Electrochemical aptasensor for detection of acetamiprid in vegetables with graphene aerogel-glutamic acid functionalized graphene quantum dot/gold nanostars as redox probe with catalyst

Abstract

Glutamic acid-functionalized graphene quantum dots (Glu-GQD) was prepared by pyrolysis of citric acid and glutamic acid and used as reducing agent and stabilizer to produce Glu-GQD/Au in the presence of tannic acid. The resulting Glu-GQD/Au was covalently connected with aptamer (Apt) of acetamiprid to obtain one redox probe with catalyst. The study shows that Glu-GQD/Au offers nanostar-like structure with average particle size of 102.5 nm, composing of several nanometer-sized gold nanocrystals with the rich of sharp edges and corners. The unique structure makes gold nanostars good electrocatalytic activity, which was further improved by combination with Glu-GQD. In the redox probe, Glu-GQD can carry out reversible redox reaction on the electrode surface due to its high electroactivity. Gold nanostars in-situ catalyzes redox reactions of Glu-GQD and leads to an improved electrochemical behavior. Aptamer can specifically bind with acetamiprid and produce sensitive and selective electrochemical response. The electrochemical aptasensor based on Glu-GQD/Au-Apt/graphene aerogel exhibits ultrahigh sensitivity and selectivity for detection of acetamiprid. The differential pulse voltammetric signal linearly decreases with increasing acetamiprid concentration in the range from 1.0 fM to 1 × 105 fM with detection limit of 0.37 fM (S/N = 3). The aptasensor has been successfully applied in electrochemical detection of acetamiprid in vegetables.