A sensitive signal-off aptasensor for adenosine triphosphate based on the quenching of Ru(bpy)32+-doped silica nanoparticles electrochemiluminescence by ferrocene

In this paper, a novel and sensitive signal-off electrochemiluminescence (ECL) aptasensor was proposed for the detection of adenosine triphosphate (ATP) on a nanoporous gold (NPG) modified glassy carbon electrode. The NPG was easily synthesized by a selective dissolution of silver from silver/gold alloy in nitric acid. The ECL aptasensor consisted of two main elements: an ECL substrate, made by modifying the amino group functionalized Ru(bpy)32+-doped silica (Ru-silica), and an ECL intensity switch, which contains two probes, split from one aptamer. The first probe (ssDNA1) was functionalized with a thiol group at one end and attached to Ru-silica through the linking agent of N-succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate. The other one (ssDNA2) is ferrocene-labeled probe, which was functionalized with ferrocene tag at the amino group functionalized end. We demonstrated that the ssDNA1/ATP/ssDNA2 sandwich composites layer could be formed in the presence of ATP, and lead to a quenching of Ru(bpy)32+. However, only a slight decrease could be observed in the absence of ATP. Under optimal conditions, the proposed biosensor provided a wide linear response range over 0.1 pmol L−1-10.0 nmol L−1 with a detection limit of 0.03 pmol L−1.