Ru(bpy)₃ ²⁺-DBAE Coreactant-SDS Enhancer Systems on Automated Electrochemiluminescence Immunoassay Analyzer...

This work reports one Ru(bpy)₃ ²⁺-N,N-dibutylethanolamine (DBAE) coreactant-sodium dodecyl sulfate (SDS) enhancer system on an automated electrochemiluminescence immunoassay (ECLIA) analyzer for the ECL immunoassay of carbohydrate antigen 19-9 (CA19-9). The ECL intensity of the MB@SA•biotin-GSK-Ru1 bio-conjugates in DBAE solution on the automated ECLIA analyzer, which employs a platinum working electrode under the "Heterogeneous" model, demonstrates a 333% enhancement in comparison with that of the conventional tri-n-propylamine coreactant. Subsequently, the developed novel DBAE coreactant-based automated ECL method was estimated by the determination of CA19-9, while the MB@SA•biotin-Ab1 was taken as the capture probe and the Ru(bpy)₃ ²⁺ derivative-labeled CA19-9 antibody (Ab2-Ru1) was employed as signal probe. In the presence of the SDS enhancer, the relative ECL intensity of the formed "sandwich" MB@SA•biotin-Ab1/CA19-9/Ab2-Ru1 biocomplexes exhibits a 4.3-fold enhancement on the automated ECLIA analyzer. Notably, under the optimized conditions, the increased ECL intensity was directly in proportion to the concentration of CA19-9 in the range from 0.5 to 8.0 U/mL with a limit of detection of 0.25 U/mL. This approach has the potential to be extended to magnetic bead-based automated ECL methods for the sensitive detection of clinical protein biomarkers.