High-sensitive electrochemiluminescent analysis based on co-reactive high-molecular polymer and dual catalysis to...

In this work, we found that polyethyleneimine (PEI), a widely applied organic high-molecular polymer, could act as a new co-reactant to obviously improve the electrochemiluminescence (ECL) of S₂O₈^2--O₂ system. And owing to its abundant amine groups in the polymeric structure, PEI was further used to covalently crosslink with massive L-cysteine (L-Cys), an effective co-reactant of S₂O₈^2--O₂ ECL system, to obtain a new co-reactive high-molecular polymer (PEI-L-Cys) with higher co-reaction efficiency. As loading platform, hierarchically branched Au/Pd dendrimers (Au/Pd DRs G₂) were prepared to immoblize the obtained PEI-L-Cys, detection antibody, and bolocking reagent glucose oxidase (GOD). With the existence of target carcinoembryonicantigen (CEA), an ECL immunosensor was constructed through the sandwiched immunoreaction between the capture antibody on the electrode and the bioconjugate based on Au/Pd DRs G₂. Besides the high enhancement of PEI-L-Cys, the ECL signal was also greatly increased by the dual catalysis to generate O₂ in situ around the electrode induced by the synergistic effect of GOD and Au/Pd DRs G₂ in presence with D-glucose. Especially, due to the special hierarchically branched bimetallic structure, the Au/Pd DRs G₂ had more excellent catalytic effect to H₂O₂ decomposition in this process. As a result, the proposed ECL immunosensor realized the ultrasensitive detection of CEA, which could provide meaningful reference to the prevention and treatment of related disease.