A novel immunosensor based on gold nanoparticles and poly-(2,6-pyridinediamine)/multiwall carbon nanotubes composite for immunoassay of human chorionic gonadotrophin

A novel multilayer film based on gold nanoparticles (GNPs) and poly-(2,6-pyridinediamine)/multiwall carbon nanotubes composite (pPA/MWNTs) was exploited to develop a highly sensitive amperometric immunosensor for detecting human chorionic gonadotrophin (HCG). In this method, pPA/MWNTs composite was prepared by electro-polymerizing PA onto MWNTs modified electrode, and then GNPs were used as a linker to immobilize HCG antibody onto the pPA/MWNTs modified electrode. Cyclic voltammetry (CV) and scanning electron microscopy (SEM) were employed to characterize the assembly process and the performance of the immunosensor. Because of the synergistic effect of pPA and MWNTs, and the unique properties of GNPs, the obtained immunosensor exhibited a wide linear response to HCG in two range from 1.0 to 10.0 and 10.0 to 160.0 mIU mL−1 with a relatively low detection limit of 0.3 mIU mL−1 (S/N = 3), as well as good stability and repeatability.