Ru(bpy) 3 2+ ‐DBAE Coreactant‐SDS Enhancer Systems on Automated Electrochemiluminescence Immunoassay Analyzer Containing Pt Electrode for Highly Sensitive Detection of Carbohydrate Antigen 19‐9

ABSTRACT 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.