Competitive electrochemiluminescence aptasensor based on the Ru(II) derivative utilizing intramolecular ECL emission for E2 detection

One competitive aptasensor based on novel intramolecular ECL emission system was investigated for ultrasensitive detection of E2. It should be noted that the Ru(II) derivative for the mechanism of intramolecular ECL could improve electron transfer efficiency and reduce energy consumption. The Ru(II) derivatives were prepared by optimizing distribution ratio of Ru(dcbpy)32+ and carbohydrazide for acquiring the ECL signal maximum. Stimulated by In3+/In+ redox reversible electron pair in the InVO4/β-AgVO3 heterostructures, the InVO4/β-AgVO3 heterostructures were designed as co-reaction accelerator to expedite ECL emission reaction between CON4H6• and Ru(dcbpy)33+. Taking advantage of associative competition between cDNA and E2 with aptamer, the ECL signal realized further amplification. The specific binding of the aptamer to E2, was stronger than that to the cDNA by hybridization. A mass of Ru(II) derivatives could adsorb and embed into the hybridized double-stranded DNA to immobilize on the electrode surface and generate satisfactory ECL signal. The specific binding of the aptamer to E2 decreased the cDNA content on electrode surface, which contributed to lessen the adsorption amount of Ru(dcbpy)32+ and distinctly affected the ECL signal. Under optimal conditions, the proposed biosensor provided an admirable linearity to the level of E2 between 0.001 nmol/L and 100 nmol/L with a low detection limit of 0.27 pmol/L. The proposed aptasensor not only stimulates more interest in the mechanism of intramolecular ECL but also has towardly development potential for constructing competitive strategies.