Signal-on electrochemiluminescence aptasensor for bisphenol A based on hybridization chain reaction and electrically heated electrode

A simple and sensitive electrochemiluminescence (ECL) aptasensor has been developed for bisphenol A (BPA) detection. The capture DNA (CDNA) was modified on the heated indium-tin-oxide (ITO) working electrode surface firstly and then hybridized with BPA aptamer to form double strand DNA (dsDNA). The presence of target can cause the releasing of aptamer from the electrode surface since the aptamer prefers to switch its configuration to combine with BPA. Subsequently, the free CDNA will induce hybridization chain reaction (HCR) to produce long dsDNA on the electrode surface. Ru(phen)32+ can integrate into the grooves of dsDNA to act as an ECL reagent, thus enhanced ECL signal can be detected. The temperature control during the processes of target recognition and HCR were realized through the heated electrode instead of the bulk solution heating. Furthermore, the performance of the ECL aptasensor can be further enhanced at elevated electrode temperature. Under the optimized conditions, the ECL intensity of the system has a linear relationship with the logarithm of BPA concentration in the range of 2.0 pM-50 nM. The limit of detection (LOD) at 55 °C (electrode surface temperature) was calculated to be 1.5 pM, which was approximately 6.5-fold lower than that at 25 °C. The proposed biosensor has been applied to detect the BPA in drink samples with satisfactory results.