A dual-signaling strategy for ultrasensitive detection of bisphenol A by aptamer-based electrochemical biosensor

A facile label-free aptamer-based electrochemical biosensor has been developed for sensitive detection of bisphenol A (BPA) based on a dual-signaling amplification strategy. The aptasensor was constructed by electro-deposition of gold nanoparticles (AuNPs) onto a glassy carbon electrode (GCE), where a thiolated-modified BPA aptamer was immobilized through self-assembly and then hybridized with the biotin-modified complementary DNA probe (cDNA) to form a double-stranded DNA. Upon the highly specific interaction between the target BPA and its aptamer, cDNA was released from the electrode surface and BPA was immobilized on the sensing interface. Streptavidin-modified horseradish peroxidase-functionalized gold nanoparticle (avidin-HRP-AuNP) was chosen as the nanoprobe, due to its catalytic activity to the oxidation of hydroquinone (HQ) in the presence of H2O2. As a result, the captured amounts of avidin-HRP-AuNP decrease with the increase of the BPA concentration and produce a series of decreasing catalytic peak currents. In addition, BPA has a redox activity and could provide an additional signal transformation. By superimposing the two signal changes, BPA was detected sensitively in a linear range from 0.001 to 1 nM with a detection limit of 0.41 pM. The aptasensor exhibited good selectivity toward BPA even in the presence of the interferents at 100-fold concentrations. This method would be readily applicable for sensitive detection of other redox analytes, merely by changing the anti-BPA aptamer/cDNA pair with a correspondent anti-target molecule aptamer and cDNA. (C) 2016 Elsevier B.V. All rights reserved.