Imaging the substructures of individual IgE antibodies with atomic force microscopy

The interaction between antibodies and substrates directly affects its conformation and thus its immune function. Therefore, it is desirable to study the structure of antibodies at the single molecule level. Herein, the substructures of Immunoglobulin E (IgE) on solid surfaces were investigated. For this purpose, the tapping-mode atomic force microscopy (AFM) was applied to observe the individual IgE substructures adsorbed onto Mg2+ and Na+ modified mica substrates in air. As expected, the AFM images revealed that the IgE antibodies exhibited different conformations on the surface of mica substrate, consisting of the four basic orientations: three domain, two equivalent domain, two unequal domain and single domain morphologies. Moreover, the differences of the different orientations in single IgE antibodies were also identified clearly.