Development of Impedance Electrode Detection Strips for Quantitative Detection of Human Chorionic Gonadotropin

In this study, an impedance electrode chip that we developed was used for the detection of human chorionic gonadotropin (hCG) sandwich immunoreactivity, as well as gold nanoparticle (AuNP)-conjugated antibodies as labels to facilitate detection. The immune response of the tested specimen and quantitative impedance measurement analysis results were used for identification. An LCR meter, which is a type of electronic test equipment used to measure the inductance (L), capacitance (C), and resistance (R) of an electronic component, was used to detect the electrical signal of the impedance electrode chip, and the changes in immune response were analyzed through impedance value changes to establish the electrical measurement data of hCG. To avoid signal measurement problems caused by poor bonding between the nitrocellulose (NC) membrane and the detection electrode, the NC membrane was fixed directly onto the surface of the detection electrode by a polymer solution phase conversion method, and quantitative impedance signals at different hCG concentrations were successfully measured. The results showed that using this method successfully broke through the traditional naked -eye identification concentration limit of 25 mIU/mL, reaching a lower concentration of 6.25 mIU/ mL, and the coefficient of determination between the impedance value signal and the hCG concentration reached 0.9899, which means that the self-made electrode chip can quantitatively detect and analyze the hCG concentration.