ATOMIC-FORCE MICROSCOPIC STUDY OF SPECIFIC ANTIGEN ANTIBODY BINDING/

Using atomic force microscopy (AFM), we systematically studied the bin ding of three pairs of specific antigen/antibody systems: bovine serum albumin, tobacco etch virus capsid protein, and tobacco mosaic virus capsid protein and their respective specific antibodies. Our goals wer e to find a substrate for antigen immobilization, characterize individ ual antigen/antibody complexes, and investigate the antigen/antibody b inding process. We found that the antigen protein can be immobilized o n a -COOH-terminated self-assembled monolayer surface. Individual anti gens and antigen/antibody complexes are easily identified from AFM ima ges taken in liquid or under ambient laboratory conditions. The in sit u studies suggest that antibody-antigen reactions occur in less than 4 min in buffer and that the reaction complexes are stable adsorbates o nce formed. As control experiments, nonspecific antibodies of equal an d higher concentrations than those of specific antibodies have been us ed. There was no binding between nonspecific antibodies and the antige n-immobilized surfaces. The experimental results suggest that the proc edure established here may be used for specific antibody detection. In addition, this study has also enhanced our understanding of antigen/a ntibody binding processes.