A novel ECL biosensor for β-lactamase detection: Using RU(II) linked-ampicillin complex as the recognition element

In this work, Ru(phen)2(cpaphen)2+ linked-ampicillin (Ru-Amp), as the novel specific recognition element, was proposed to construct a simple and sensitive electrogenerated chemiluminescence (ECL) biosensor for the determination of β-lactamase. Here, Ru-Amp complex acted not only as a novel specific recognition element for β-lactamase but also as the ECL Luminescent reagent. Through electrostatic adsorption and the intermolecular π-π interactions, a large amount of Ru-Amp was immobilized to gold nanoparticles (TA@AuNPs) prepared by thiophenemalonic acid (TA) to obtain Ru-Amp/TA@AuNPs nanocomposites. The nanocomposites, which can produce very stable films exhibiting excellent ECL behaviors, were self-assembled on the CNTs-Nf modified glassy carbon electrode surface. The presence of the target β-lactamase resulted in autonomous hydrolysis reaction of Amp, achievement of the efficient ECL emission and highly sensitive detection of β-lactamase. The biosensor for β-lactamase detection was developed with excellent sensitivity of a concentration variation from 50 pg mL−1 to 100 ng mL−1 with a low detection limit of 37 pg mL−1. An ECL assay offers the proposed method opportunities for designing new Ru-based ECL luminophores for biosensing applications.