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

The study reported one concept for fabrication of glutamic acid functionalized graphene quantum dot-gold hybrid. The hybrid exhibits nanostar-like structure, excellent redox behaviors and was successfully applied in fabrication of electrochemical aptasensor for detection of acetamiprid with ultrahigh sensitivity and selectivity. [Display omitted] •We report synthesis of functional graphene quantum dot-gold and use as redox probe with catalyst.•Hybrid of graphene quantum dot and gold nanostars offers an obviously enhanced catalytic activity.•The proposed aptasensor exhibits ultra high sensitivity and selectivity of acetamiprid detection.•The acetamiprid sensing nanoplatform can be easily extended to detect a variety of insecticides. 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.