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

Abstract

Poisonous mushrooms may cause fatal harm to humans and animals, but its rapid detection faces a great challenge. The study reports synthesis of gold-aspartic acid, glycine acid-functionalized and boron-doped graphene quantum dot nanohybrid (AGB-GQD@Au) and application in electrochemical detection of α-amanitin. AGB-GQD was prepared by pyrolysis and reacted with chloroauric acid to form gold nanoparticles. AGB-GQD@Au offers 12.5 nm-sized particles and Schottky heterojunction, which improves 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 target-induced DNA cycle amplification. α-Amanitin specifically hybridizes with aptamer in duplex DNA to release auxiliary strand DNA. The released DNA triggers DNA cycle and brings one redox probe to electrode surface. By the DNA cycle, one target brings many redox probes to the electrode surface, producing significant signal amplification. The detection signal was further enhanced by catalysis of AGB-GQD@Au towards redox of thionine. Differential pulse voltammetric current increases linearly with the increasing α-amanitin in the range of 4-4×105 fM with 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.

Keywords: Gold-graphene composite, Schottky heterojunction catalyst, aptasensor, Electrochemical sensor