Multilayer structured amperometric immunosensor based on gold nanoparticles and Prussian blue nanoparticles/nanocomposite functionalized interface

In this paper, a novel strategy for the fabrication of sensitive reagentless amperometric immunosensor was proposed. Firstly, Prussian blue nanoparticles (PBNPs) as redox probe were immobilized on three dimensional structured membrane of the gold colloidal nanoparticles (AuNPs) doped chitosan-multiwall carbon nanotubes (CS-MWNTs) homogeneous composite (CS-MWNTs-AuNPs) by electrostatic interactions between the negatively charged PBNPs and the positively charged amino groups of CS and strong binding interaction between GNPs and nitrile group (–CN) of PBNPs. Subsequently, the gold nanoparticles (GNPs) were electrodeposited on the surface of the composite by electrochemical reduction of gold chloride tetrahydrate (HAuCl4) to immobilize antibody biomolecules (anti-CEA) and avoid the leakage of PBNPs. The stepwise assembly process was characterized by means of cyclic voltammetry (CV) and electrochemical impendance spectroscopy (EIS). Furthermore, the morphology of the prepared nanomaterials was researched by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Under the optimized conditions, the decrease of CVs current of determination CEA was proportional to concentration ranges from 0.3 to 120 ng/mL with a detection limit of 0.1 ng/mL at a signal-to-noise of 3. Moreover, the proposed immunosensor exhibited good accuracy, high sensitivity and stability.