Efficient conjugation of anti-HBsAg antibody to modified core-shell magnetic nanoparticles (Fe(3)O(4)@SiO(2)/NH(2))

[Image: see text] Introduction: Further development of magnetic-based detection techniques could be of significant use in increasing the sensitivity of detection and quantification of hepatitis B virus (HBV) infection. The present work addresses the fabrication and characterization of a new bio-nano composite based on the immobilization of goat anti-HBsAg antibody on modified core-shell magnetic nanoparticles (NPs) by (3-aminopropyl) triethoxysilane (APTES), named Fe(3)O(4)@SiO(2)/NH(2), and magnetic NPs modified by chitosan (Fe(3)O(4)@CS). Methods: At the first step, Fe(3)O(4) was modified with the silica and APTES (Fe(3)O(4)@SiO(2)/NH(2)) and chitosan (Fe(3)O(4)@CS) separately. The goat anti-HBsAg antibody was activated by two different protocols: Sodium periodate and EDC-NHS. Then the resulted composites were conjugated with activated goat anti-HBsAg IgG. An external magnet collected Bio-super magnetic NPs (BSMNPs) and the remained solution was analyzed by the Bradford method to check the amount of attached antibody to the surface of BSMNPs. Results: The findings indicated that activation of antibodies by sodium periodate method 15-17 µg antibody immobilized on 1 mg of super magnetic nanoparticles (SMNPs). However, in the EDC-NHS method, 8-10 µg of antibody was conjugated with 1 mg of SMNPs. The resulting bio-magnetic NPs were applied for interaction with the HBsAg target using enzyme-linked immunosorbent assay (ELISA). About 1 µg antigen attached to 1 mg SMNPs, which demonstrated that the fabricated materials are applicable in the detection scope of HBsAg. Conclusion: In the present study, we developed new antibody-conjugated magnetic NPs for the detection of HBsAg using an efficient conjugation strategy. The results demonstrated that the binding capacity of Fe(3)O(4)@SiO(2)/NH(2) was comparable with commercially available products. Our designed method for conjugating anti-HBsAg antibody to a magnetic nanoparticle opens the way to produce a high capacity of magnetic NPs.