Highly sensitive and selective electrochemical aptasensor with gold-aspartic acid, glycine acid-functionalized and boron-doped graphene quantum dot nanohybrid for detection of α-amanitin in blood

Poisonous mushroom may cause fatal harm to human and animal, but its rapid detection still faces a great challenge. The paper reports synthesis of gold-aspartic acid, glycine acid-functionalized and boron-doped graphene quantum dot nanohybrid (AGB-GQD@Au) for the electrochemical detection of α-amanitin. AGB-GQD was prepared by pyrolysis and then reacted with chloroauric acid to produce gold nanoparticles. AGB-GQD@Au offers 12.5 nm-sized particles and Schottky heterojunction, improving the catalytic activity. AGB-GQD@Au connected with hairpin DNA and thionine by Au-S bonds was used as redox probe for electrochemical detection of α-amanitin coupled with one target-induced DNA cycle amplification strategy. α-Amanitin specifically hybridizes with aptamer in duplex DNA to release auxiliary strand DNA. The released DNA triggers one DNA cycle process and brings one redox probe to the electrode surface. By the DNA cycle, one target brings many redox probes to the electrode surface, producing a significant signal amplification. The detection signal was further enhanced by the catalysis of AGB-GQD@Au towards redox of thionine. Differential pulse voltammetric current increases linearly with the increasing α-amanitin in the range from 4 to 4 × 105 fM with the detection limit of 1.2 fΜ (S/N = 3). The analytical method provides advantages of sensitivity, selectivity and repeatability. It has been successfully applied in electrochemical detection of α-amanitin in blood.