Photoelectron microscopy of erythrocyte ghosts; imaging of lectin binding sites with colloidal gold markers

Images of human red cell ghosts have been obtained by photoelectron microscopy (photoemission electron microscopy or PEM) without any staining, metal coating or shadowing. Membrane folding, when it occurs in these collapsed structures, shows up clearly even though the membrane itself is only 5–10 nm in thickness. Using red cell ghosts as a model system, it is shown that colloidal gold can act as a photoemissive marker. Specific lectin binding sites on the cell surface were labeled with a colloidal gold-wheat germ agglutinin complex. The gold particles were readily detectable against the weaker emission from the cell surface.