Preparation of Electrochemical Immunosensor Using Gold Nanoclusters as Signal Amplification Labels

A cheap and portable electrochemical immunosensor based on the silver-enhanced colloidal gold electrochemical stripping technique and gold nanoclusters (AuNCs) labels was proposed for the detection of human IgG. Inspired by adhesive proteins that secreted by marine mussels, the stable and robust film-poly (dopamine) was used to immobilize biomolecules (Ab1) on an indium tin oxide (ITO) electrode for the fabrication of immunosensor. Then, human IgG and AuNCs-Ab2 were immobilized to the Ab1 modified ITO electrode successively. The process for the fabrication of sandwich immunosensor was monitored by electrochemical impedance spectroscopy. Through immunoreaction between antigen and antibody, IgG could be quantitatively determined by anodic stripping voltammetry. On the basis of the dual signal amplification of AuNCs labels and silver enhancement technique, the sensitivity was improved to 0.5 pg mL. Moreover, the proposed immunosensor could be used in clinical diagnosis.