A ratiometric electrochemiluminescent biosensor for Con A detecting based on competition of dissolved oxygen.

A novel ratiometric electrochemiluminescent (ECL) biosensor was designed for the detection of concanavalin A (Con A) based on two ECL emitters competing for the dissolved oxygen (O2). In this strategy, CdTe quantum dots (QDs) were used as the cathodic emitter and N-(aminobutyl)-N-(ethylisoluminol) (ABEI) was used as the anodic emitter. With the presence of dissolved O2 utilized as co-reactant, CdTe QDs showed an ECL emission at - 1.7 V, and ABEI showed an emission at + 0.6 V. Phenoxy-derivatized dextran (Dexp), as a recognition element, was immobilized by graphene oxide functionalized CdTe QDs (G-CdTe QDs) to recognize Con A, and further combine with Dexp, gold and platinum nanoparticles decorated ABEI (Dexp-Au-Pt-ABEI) to form a sandwich structure. With the increasing concentration of analyte Con A, the ECL signal of cathodic CdTe QDs decreased and the anodic response of ABEI increased, thus achieving a ratiometry detection of Con A with a wide linear range from 1.0 × 10-4 ng/mL to 10 ng/mL. The detection limit was low to 3.0 × 10-5 ng/mL. This proposed ratiometric ECL biosensor not only conquered the false errors caused by external interferences, but excluded the disability caused by exogenous co-reactant via the application of common dissolved O2. It also exhibited an excellent stability, selectivity and reproducibility.

A novel electrochemiluminescent biosensor based on resonance energy transfer between poly(9,9-di-n-octylfluorenyl-2,7-diyl) and 3,4,9,10-perylenetetracar-boxylic acid for insulin detection.

An electrochemiluminescencent (ECL) biosensor was designed for the determination of insulin using a novel ECL resonance energy transfer (ECL-RET) strategy. In this strategy, carboxyl poly(9,9-dioctyfluorenyl-2,7-diyl) dots (PFO dots) were worked as ECL donor and 3,4,9,10-perylenetetracar-boxylic acid (PTCA) exploited as ECL acceptor, and hydrogen peroxide (H2O2) employed as the coreactant. The ECL donor and ECL acceptor were separately labeled with primary antibody (Ab1) and secondary antibody (Ab2), forming a sensing interface to the analyte target, insulin. In this expected sandwich-type ECL biosensor, PFO dots acted as sensing platform and PTCA employed as labels to quench the ECL emission of PFO dots. During the determination process, ECL signal of PFO dots was decreased in a gradual way by the increase of insulin concentration, and the quenching mechanism was also investigated. Under the optimal experimental conditions, the constructed biosensor exhibited an excellent performance, including a wide linear range from 1.0 × 10-5ng/mL to 1.0 × 102ng/mL, low detection limit of 3.0 × 10-6ng/mL, good stability and selectivity for the detection of insulin. This pair of PFO-PTCA, as a new donor-acceptor pair in ECL-RET system, would provide a promising platform for bioanalysis in ECL field.