A label-free and reagentless immunoelectrode for antibodies against hepatitis B core antigen (anti-HBc) detection

An electrochemical immunosensor devoted the core hepatitis B antibody detection, based on polytyramine (PTy) and carbon nanotubes (CNT) composite was developed. The antibody interactions with immobilized antigens were detected by reduction on the electron transfer from ionic species coming from reactive amine groups of PTy. The synthesis in acid medium of PTy-CNT composite favorite a great amount of NH₃⁺ ionic species, forming a nanocomposite with high catalytic activity on the electrode surface. As proof-of-concept, antibodies against the core hepatitis B virus were label-free and reagentless electrochemically detected by square wave voltammetry (SWV) through decrease on cathodic peaks. It was recently reported that hepatitis B core antigen antibodies (anti-HBc) is a powerful biomarker for hepatitis B virus (HBV) infection, being more specific than HBsAg due to the possibility of detecting the occult HBV infections. The nanostructured film was characterized by atomic force microscopy and electrochemical techniques. This immunosensor showed linear responses from 1.0 to 5.0 ng mL^-1 and a limit of detection of 0.89 ng mL^-1 anti-HBc. It was also tested in assays with negative and positive blood samples using 0.1 M KCl as electrolyte support on readings showing specific responses. This easy reagentless detection platform, showing a remarkable potential to development of bolder and simpler HBV assay for screening of blood bags, in attempting to circumvent point-of-care testing limitations.