Magnetic separation and enzymatic catalysis conjugated colorimetric immunosensor for Hepatitis B surface antigen detection

Hepatitis B Surface Antigen (HBsAg) is usually recognized as an earliest diagnostic markers for Hepatitis B Virus (HBV) infections. The precise and sensitive determination of HBsAg is crucial for the diagnostic of HBV infection. In this paper, a colorimetric immunosensor has been successfully designed and fabricated based on conjugating magnetic separation and enzymatic catalysis, for point-of-care detection of HBsAg. The HBsAg was simultaneously captured by the biotinylated HBsAg primary antibody (biotin-Ab 1 ) labeled immunomagnetic nanoparticles and detection antibody (Ab 2 ). In conjugation with Ab 2 , horseradish peroxidase (HRP) labeled rabbit anti-goat secondary antibody was linked with chromogenic agents to induce the colorimetric signal. As a result, a good linear relation was achieved between the concentration of HBsAg and OD 450 nm (absorbance values at 450 nm) in the 0.1–20 ng mL −1 ranges, demonstrating a great specificity to HBsAg with a limit of detection of 0.012 ng mL −1 . Furthermore, considering its succeed in real human serum sample test, this immunosensor could make contribute to potential applications in rapid diagnosis, effective prevention of epidemic and infectious diseases.