Construction of Biomimetic Interface by Layer-by-Layer Self-Assembly Technique for Electrochemical Amperometric Immunosensing Applications

A novel biomimetic interface for developing label-free amperometric immunosensor based on layer-by-layer (LBL) self-assembly of positively charged ferrocene-chitosan/multiwalled carbon nanotubes (CS-Fc/MWNTs) and negatively charged gold nanoparticles (Au NPs) onto 3-mercaptopropanesulfonic sodium salt (MPS)-modified gold electrode surface was described. Through LBL self-assembly of CS-Fc/MWNTs and Au NPs, the constructed three-dimensional mutilayer network structure could provide more steric sites and ideal platform for further immobilization of biomolecules without loss of their activity. By using hepatitis B surface antigen (HBsAg) as a model, the constructed immunosensor exhibited a specific response to HBsAg linearly in the concentration range of 0.1–350 ng mL−1 with a detection limit of 0.037 ng mL−1 (S/N = 3). The relative error between the results obtained from the immunosensor and the standard method proposed by ELISA was −4.46% to 8.33%, indicating that the two methods were in acceptable agreement and the proposed method could be applied to determination of HBsAg in human serum for clinical diagnosis.