Au nanoparticles grafted sandwich platform used amplified small molecule electrochemical aptasensor.

We report a sensitively amplified electrochemical aptasensor using adenosine triphosphate (ATP) as a model. ATP is a multifunctional nucleotide that is most important as a "molecular currency" of intracellular energy transfer. In the sensing process, duplexes consisting of partly complementary strand (PCS1), ATP aptamer (ABA) and another partly complementary strand (PCS2) were immobilized onto Au electrode through the 5'-HS on the PCS1. Meanwhile, PCS2 was grafted with the Au nanoparticles (AuNPs) to amplify the detection signals. In the absence of ATP, probe methylene blue (MB) bound to the DNA duplexes and also bound to guanine bases specifically to produce a strong differential pulse voltammetry (DPV) signal. But when ATP exists, the ABA-PCS2 or ABA-PCS1 part duplexes might be destroyed, which decreased the amount of MB on the electrode and led to obviously decreased DPV signal. This phenomenon can be used to detect ATP and get a very sensitive detection limit low to 0.1nM, and the detection range could extend up to 10(-7)M. Compared to the sensing platform without PCS2 grafted AuNPs, amplified function of this sensing system was also evidently proved. Therefore, such PCS1-ABA-PCS2/AuNPs sensing system could provide a promising signal-amplified model for aptamer-based small-molecules detection.