Double-site DNA walker based ternary electrochemiluminescent biosensor

Abstract

A novel biosensor was developed on the basis of Ru(dcbpy)(bpy)₂²⁺/tripropylamine (TPrA)/TiO₂ nanocrystallines (TiO₂ NCs) as efficient electrochemiluminescence (ECL) ternary system and enzyme-driven double-site DNA walker as signal amplification strategy for the sensitive detection of carcinoembryonic antigen (CEA). Specifically, coreaction accelerator anatase TiO₂ NCs with catalytic activity could accelerate the oxidization of TPrA for prominently stimulating the ECL performance of Ru(dcbpy)(bpy)₂²⁺/TPrA system to achieve the "signal on" state. Subsequently, numerous double-site walker DNA, converted from the target (CEA)-induced protein-aptamer cycle amplification, would trigger the detachment of Ru(dcbpy)(bpy)₂²⁺ to reach the state of "signal-off". Benefiting from the above advantages, the developed ECL biosensor achieved outstanding sensitivity with a linear range from 500 pg/mL to 50 fg/mL and a detection limit down to 10.5 fg/mL. More importantly, the proposed strategy opens a new path for employing the ECL ternary system for sensitive detection of biomolecules and disease diagnosis.

Keywords: Anatase TiO(2) nanocrystallines; Coreaction accelerator; Double-site DNA walker; Electrochemiluminescence.