Effects of multivalent histamine supported on gold nanoparticles: activation of histamine receptors by derivatized histamine at subnanomolar concentrations†
Colloidal gold nanoparticles with a functionalized ligand shell were synthesized and used as new histamine receptor agonists. Mercaptoundecanoic acid moieties were attached to the surface of the nanoparticles and derivatized with native histamine. The multivalent presentation of the immobilized ligands carried by the gold nanoparticles resulted in extremely low activation concentrations for histamine receptors on rat colonic epithelium. As a functional read-out system, chloride secretion resulting from stimulation of neuronal and epithelial histamine H1 and H2 receptors was measured in Ussing chamber experiments. These responses were strictly attributed to the histamine entities as histamine-free particles Au–MUDOLS or the monovalent ligand AcS–MUDA–HA proved to be ineffective. The vitality of the tissues used was not impaired by the nanoparticles.