Highly sensitive tetracycline detection using a triple amplification aptasensor based on graphene-carbon nanotube, Exonuclease I, and gold nanoprobes

Abstract

Enhancing the sensitivity of targeted substance detection is crucial, yet prior research seldom incorporates more than two signal amplification methods. In this study, we introduced a novel triple signal amplification strategy for tetracycline detection using an aptasensor. This strategy integrates a graphene and multi-walled carbon nanotubes composite (GO-MWCNTs), Exonuclease I (Exo I), and a hybrid DNA-gold nanoparticle (AuNPs)-horseradish peroxidase (HRP) system. The GO-MWCNTs serve as a conductive carrier, boosting electron transfer for initial signal amplification. Exo I, targeting single-stranded DNA, facilitates target recovery and secondary signal amplification. The gold nanoprobe, through specific base pairing, binds to the tetracycline aptamer’s complementary chains on the electrode surface. Horseradish peroxidase’s catalytic action then generates a robust electrochemical signal, culminating in three-stage signal amplification. This optimized approach achieved a low detection limit of 3.3 × 10−4 ng mL−1, with a range from 1 × 10−3 ng mL−1 to 1 × 103 ng mL−1. Notably, the aptasensor demonstrated high selectivity, repeatability, stability, and reliability. These findings offer a promising reference for developing effective aptasensors in antibiotic detection.