Study on Conjugation of Quantum Dot with Anti-Hepatitis B Surface Antigen Antibody

Goat anti-Hepatitis B surface antibodies were covalently linked onto carboxyls capped quantum dots (QD) under activation of ethyl-(dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS). The effect on the QD-antibody (QD-Ab) of 4 different blocking reagents, ethanol amine, tris-(hydroxymethyl)-aminomethane (Tris), methoxy- poly(ethylene glycol) amine (PEG5000-NH2) and bovine serum albumin (BSA), was studied. Electrophoresis mobility and particle sizes of QD-Ab bioconjugates were characterized with agarose and SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Immunological property of bioconjugates was compared by dot blot immunoassays. The results showed that QD-Ab bioconjugates can be prepared by covalently linking HBsAg antibody and QD. From the results of dot blot immunoassays, it is believed that PEG2000-NH2 blocked QD-Ab conjugates possessbetter immunological properties, which can be used to detect 1. 57 ng HBsAg proteins by dot blot immunoassay.