Multianalyte Electrochemical Biosensor Based on Aptamer- and Nanoparticle-Integrated Bio-Barcode Amplification

In the present work, a signal-on electrochemical sensing strategy for the simultaneous detection of adenosine and thrombin is developed based on switching structures of aptamers. An Au electrode as the sensing surface is modified with two kinds of thiolated capture probes complementary to the linker DNA that contains either an adenosine aptamer or thrombin aptamer. The capture probes hybridize with their corresponding linker DNA. which has prehybridized with the reporter DNA loaded onto the gold nanoparticles (AUNPs). The AUNP contained two kinds of bio-barcode DNA: one is complementary to file linker DNA (reporter), whereas the other is not (signal) and is tagged with different metal sulfide nanoparticles. Thus a "'sandwich-type" sensing interface is Fabricated for adenosine and thrombin. With the introduction of adenosine and thrombin, the aptamer parts hind with their targets and fold to form the complex structures. As a result, the bio-barcoded AuNPs are released into solution. The metal sulfide nanoparticles are measured by anodic stripping voltammetry (ASV), and the concentrations of adenosine and thrombin are proportional to the signal of either metal ion. With the dual amplification of file bio-barcoded AuNP and the pre-concentration of metal ions through ASV technology, detection limits as low as 6.6x10(-12) M for adenosine and 1.0x10(-12) M for thrombin are achieved. The sonsor exhibits excellent selectivity and detectability in biological samples.