An ultrasensitive electrochemical aptasensor for thrombin based on the triplex-amplification of hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme and horseradish peroxidase decorated FeTe nanorods

Abstract

In the present study, we fabricated an ultrasensitive sandwich-type electrochemical aptasensor for thrombin (TB) based on a triplex signal amplification strategy. The hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme (HRP-DNAzyme) as well as blocking reagent-horseradish peroxidase (HRP) and iron telluride nanorods (FeTe NRs) could simultaneously amplify the electrochemical signal of thionine (Thi) in the presence of H₂O₂. Herein, FeTe NRs, as a newly discovered HRP-mimicking enzyme, were employed to construct an aptasensor for the first time. And, the FeTe NRs decorated by gold nanoparticles (abbreviated as AuNPs@FeTe NRs), were not only used as carriers of secondary thrombin aptamer (TBA 2), electron mediator thionine (Thi) and HRP, but also catalyzed the electrochemical reaction of Thi in the presence of H₂O₂. As can be seen from experiment results, with the triplex signal amplification strategy, the reduction peak current of the fabricated aptasensor was logarithmically related to the concentration of thrombin (TB) over a wide range from 1 pM to 20 nM, and a detection limit of 0.5 pM was obtained. Hence, the proposed aptamer-based sandwich sensing approach for amplified detection of TB could provide a promising way for highly sensitive determination of other analytes.