target‐stimulated DNAzyme concatamers released from aptasensor for highly sensitive and specific detection of progesterone

Aiming at the detection of ultralow concentration target progesterone (Pro), a novel electrochemical aptasensor based on DNAzyme concatamers signal amplification strategy was proposed. The strategy consists of target DNA strands (TDNAs), and two different hairpin DNA molecules (H1 and H2). The signal is amplified by the large amount of DNAzyme. The TDNAs modified on the electrode open H1 structures in sequence and propagate a reaction of hybridization events between two alternating hairpins (H1and H2) to obtain abundant DNAzyme concatamers. Upon target Pro introduction, a specific Pro-TDNAs reaction was executed, thereby resulting in the release of DNAzyme concatamers from the electrode. Subsequent differential pulse voltammetry(DPV) detection of aminoazobenzene (DAP) resulting by DNAzyme catalyze the oxidation of o-phenylenediamine (OPD) with the aid of hydrogen peroxide (H2O2). Likewise, a small amount of target Pro can efficiently induce the release of a large number of the DNAzyme from the electrode in the form of DNAzyme concatamer. Under optimal conditions, the the proposed assay presents good electrochemical responses for determination of target Pro in the range of 0.5 to 15ng/mL with the detection limit of 0.36ng/mL. In addition, the resulting sensor can successfully distinguish Pro from coexisting interfering substance and show good stability and high repeatability. What's more, the methodology has also been demonstrated by assaying Pro-spiked samples in serum.