A Dual-Ion Synergistic Catalysis Utilizing Zn2+-Regulated CdSySe1-y ECL Immunosensor Employed for the Ultrasensitive CA19-9 Detection.

Carbohydrate antigen 19-9 is a well-known malignancy biomarker, and its sensitive detection is particularly crucial in the diagnosis and assessment of pancreatic cancer. In this study, an ultrasensitive CA19-9 immunosensor was constructed using the Zn2+-regulated CdSySe1-y (Zn-CdSySe1-y) nanospheres (NSs) as the electrochemiluminescence (ECL) emitter and FeCoS2 nano octahedrons (NOs) as a coreactant enhancer. The microstructure of ternary transition metal chalcogenide CdSySe1-y was precisely tuned by Zn2+ doping to avoid aggregation and thus enable stable and efficient cathodic ECL responses. The bimetallic sulfide FeCoS2 was synthesized using a metal organic framework (MOF) as the template by ion permeation. It was able to catalyze the coreactant efficiently due to the synergistic effect of the Fe2+ and Co2+. The immunosensor exhibited low detection limit (7.6 × 10-5 U mL-1) in the wide linear range of 0.0001-100 U mL-1, offering a sensitive CA19-9 detection method.