An atomic force microscopy study in the detection of hepatitis B surface antigen by enzyme-linked immunosorbent assay

Atomic force microscopy (AFM) was employed to study certain enzyme immunoassay steps for the detection of hepatitis B surface antigen (HBsAg). Physical adsorption of monoclonal antibodies (mAb), blocking of surface active sites free of antibodies by neutral proteins, and capture of HBsAg particles by sensitized surfaces were visualized successively in microplate wells of standard immunological plates from various manufacturers. The previously undescribed details such as "etching holes" up to 20 nm in depth were observed on the surface of plates some companies. The quantitative relationships between the optical density (OD) values obtained by enzyme immunoassay (EIA) and the number of antigen-antibody complexes in AFM were calculated.