Experimental demonstration of lateral cohesion in a layer of adsorbed protein and in layers of gold-antibody complexes bound to surface immobilised antigen.

The spatial distribution of ferritin molecules adsorbed on quartz surfaces and the spatial distribution of antibody-coated colloidal gold particles over an antigen-coated surface was studied by electron microscopy. Ferritin molecules were found to initially adsorb in small clusters at 2.5 X 10(9) sites/cm2. The initial nucleation was followed by growth of the clusters. Gold antibody complexes were initially bound to the antigen-coated surface as single particles, and formation of clusters was a secondary event at higher particle densities. The results indicate that lateral cohesion between macromolecules may play a role in the stability of adsorbed layers of protein and surface immobilised antigen-antibody complexes.