Immunogold labels: cell-surface markers in atomic force microscopy

The feasibility of using immunogold labels as cell-surface markers in atomic force microscopy is shown in this paper. The atomic force microscope (AFM) was used to image the surface of immunogold-labeled human lymphocytes. The lymphocytes were isolated from whole blood and labeled by an indirect immunolabeling method using the monoclonal antibody anti-CD3 and a secondary antibody (Goat-anti-Mouse) linked to 30 nm colloidal gold particles. Some of the samples were enhanced by silver deposition o­nto the gold particles. The AFM images reveal the colloidal gold particles o­n the cell surface, with and without silver enhancement. Individual immunogold (-silver) particles are clearly resolved from the cell surface thus determining the location of antigens. The 30 nm gold particles appear in the AFM images having an average size of about 80 nm due to convolution between gold particle and AFM tip