An amperometric immunosensor based on immobilization of hepatitis B surface antibody on gold electrode modified gold nanoparticles and horseradish peroxidase

An amperometric immunosensor based on the gold nanoparticles (nano-Au) and horseradish peroxidase (HRP)-modified gold electrode for the determination of hepatitis B surface antigen (HBsAg) has been developed. The novelty of the methodology was the first use of the HRP, instead of bovine serum albumin (BSA), to block the possible remaining active sites of the gold nanoparticles monolayer, avoid the nonspecific adsorption and amplify the response of the antigen-antibody reaction at the same time. Tests performed with this immunosensor showed good linearity and sensitivity when it was evaluated on several clinical samples. The system was optimized to realize a reliable determination of HBsAg in the range of 2.56-563.2 ng/ml with a detection limit of 0.85 ng/ml. Moreover, the proposed sensor was comparable to BSA-blocked immunosensor in terms of the linearity and sensitivity.