Double-site DNA walker based ternary electrochemiluminescent biosensor.

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.

Novel ABEI/Dissolved O2/Ag3BiO3 Nanocrystals ECL Ternary System with High Luminous Efficiency for Ultrasensitive Determination of MicroRNA.

Herein, a ternary electrochemiluminescence (ECL) sensing platform with high luminous efficiency was established for ultrasensitive bioanalysis of the microRNA-21 (miR-21) from cancer cell based on N-(aminobutyl)-N-(ethylisoluminol) (ABEI) as ECL emitter, dissolved O2 as coreactant, and silver bismuth oxide nanocrystals (Ag3BiO3 NCs) as coreaction accelerator. Specifically, a novel coreaction accelerator Ag3BiO3 NCs was introduced into the ABEI/dissolved O2 system to form an ECL ternary system, which could promote the reduction of dissolved O2 to generate great deal of superoxide anion radical (O2•-), reacting with the ABEI to dramatically enhance the ECL performance. Simultaneously, a small amount of target miR-21 could trigger a one-step DNA self-assembly to form the DNA nanonet for embedding abundance ABEI with the assistance of doxorubicin hydrochloride (Dox), realizing the high-intense ECL response. Furthermore, owing to the thin-layer and porous structure, the obtained DNA nanonet could shorten the electron-transfer path of the ternary ECL system to reduce the energy loss, further improving the sensitivity of the sensing platform. As expected, the developed ECL sensing platform of miR-21 detection manifested prominent sensitivity with a low detection limit of 7.1 aM in the concentration of miR-21 range from 10 aM to 100 pM. Satisfactorily, the proposed sensing platform was triumphantly applied to detect miRNA in tumor cell lysates. Consequently, the designed strategy broadened the application of ABEI in biological analysis and hewed out a new path to establish the ECL ternary system with high luminous efficiency.