Ultrasensitive immunoassay for CA125 detection using acid site compound as signal and enhancer

A novel sensitive electrochemical immunosensor was proposed for detection of CA125 based on ferrocenecarboxylic acid (FA), HCl-doped polyaniline (H-PANI) and chitosan hydrochloride (CS-HCl), which were used as substrate materials to generate signal and to enlarge specific surface area. The composite of these three materials (acid center compound, FA@H-PANI@CS-HCl) can be connected by hydrogen (H) in each molecule. Ag@Co3O4 nanosheets were used in the immunosensor to amplify the antibody capacity and to enhance the sensitivity of the immunoassay. This kind of sensor was novel, concise and it is the first time to be used in the detection of CA125. The biosensor exhibited low detection limit (0.25 pg/mL) and wide linear range (0.001-25 ng/mL). The stability, selectivity and reproducibility were acceptable. Serum sample analysis proved that the proposed sensor owned well precision and it might be used in potential clinic testing application in the future.