Visualization of single multivalent receptor-ligand complexes by transmission electron microscopy

Gold nanoparticle labels enable the position of receptors (concanavalin A) bound to multivalent ligands (see picture; top: straptavidin-conjugated gold particles, middle: receptors, bottom: ligand) assembled using the ring-opening metathesis polymerization to be determined by transmission electron microscopy. The number of concanavalin A tetramers incorporated into the receptor-ligand complexes depends on the ligand valency. The results illustrate a general approach for the elucidation of the stoichiometry of individual multivalent ligand-receptor complexes, which is critical for understanding the mechanism of multivalent binding events.