A redox cycling-amplified electrochemical immunosensor for α-fetoprotein sensitive detection via polydopamine nanolabels.

A sandwich-type electrochemical immunosensor for sensitive detection of a tumor marker, α-fetoprotein (AFP), was fabricated by employing polydopamine-detection antibody nanoparticles (PDANPs-Ab2) as selective redox cycling-based signal amplifiers on an electrodeposited nano-gold electrode. In this research, PDANPs prepared through oxidative polymerization of dopamine were found to amplify the oxidation charge transfer of the electrochemical mediator (1,1'-ferrocene dimethanol, FDM), which was supported by cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) investigation. Therefore, PDANPs were utilized as label materials of electrochemical immunosensors to enhance sensitivity for the first time.