IgG antibody and antibody–antigen complex imaging by scanning tunneling microscopy

Abstract
We have examined two preparations of biomolecules labeled with colloidal gold markers using scanning tunneling microscopy. In the first preparation, we studied gold labeled IgG antibodies. In the second preparation, we studied unlabeled IgG antibodies which were complexed with gold labeled antigen (bovine serum albumin). Images of these noncrystalline biological specimens, obtained under atmospheric conditions, revealed features on a nanometer scale. The images show details of molecular organization in addition to the classical antibody configuration.