A label-free electrochemical immunosensor for hepatitis B based on hyaluronic acid–carbon nanotube hybrid film

• An immunosensor for anti-HBc based on hyaluronic acid (HA) and CNT was developed.
• The amino-CNT and HA was strongly attached by amide bonds forming a sensible film.
• Anti-HBc was detected without labeled antigens or antibodies by SWV.
• It was possible to measure anti-HBc in clinical range found in blood.

An electrochemical immunosensor developed for detection of antibodies to hepatitis B core protein (anti-HBc) is described. Anti-HBc is the earliest serological marker from hepatitis B virus (HBV) infection, remaining all life after contact with virus, being considered the most important marker for uses in screening of blood bank. A nanohybrid surface assembled onto a glassy carbon electrode consisting of amino carbon nanotubes recovered by hyaluronic acid was used as sensing platform to detect the anti-HBc. All the steps of electrode surface modification were characterized by Scanning Electronic Microscopy and extensively evaluated by electrochemical techniques. The electrode response was measured by direct anti-HBc antigen interactions by square wave voltammetry, dispensing uses of label or chemical mediators. Under optimal conditions, the anodic peak current which was proportional to the anti-HBs concentration. The immunosensor response was linear toward anti-HBc in concentrations up to 6 ng mL−1, with a detection limit of 0.03 ng mL−1. The linear range achieved was according to clinical level, indicating the immunosensor as promising tool for use as a criterion for blood bag disposal. The enhancement of the hyaluronic acid by carbon nanotube promoted an increase of charge electron transfer, besides a stable platform for HBc.

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