Detection of hepatitis B surface antigen using immunovoltammetry with nano-magnetic microsphere

A novel method for detecting hepatitis B surface antigen (HBsAg) using nano-magnetic polymer carboxyl microsphere was reported. The surface of the nano-magnetic polymer carboxyl microsphere covalently bound with hepatitis B surface antibody (HBsAb), and then captured HBsAg and hepatitis B secondary antibody labeled with horseradish peroxide enzyme. The microsphere with sandwich complex was separated magnetically from sample solution and the enzyme labeled at the complex catalyzed the reaction of 2-aminohydroxybenzene and hydrogen peroxide in the buffer solution. The electroactive product 2-hydroxy-3-aminophenoxazine was detected using differential pulse voltammetry. The peak current was linear with the concentration of HBsAg in the range of 0.2 - 1.0 and 1.0 similar to 500 ng . mL respectively. The detection limit was found to be 0.06 ng . mL(-1). The method has been used to detect the concentration of hepatitis B virus in human serum and the sensitivity was much higher than that of enzyme-linked immunosorbent assay (ELISA) used in diagnostic analysis.