Ratiometric electrochemical immunoassay based on internal reference value was presented.
Polythionine–gold (PTh–Au) and K3[Fe(CN)6] were used as stable internal reference signal and indicator signal respectively.
The concentration of target was quantified through the ratio values.
The reproducibility of the electrochemical immunoassay was significantly enhanced.
A high sensing performance of tumor marker (CEA as a model analyte) was obtained.