Hormone–PAMAM Dendrimer Conjugates: Polymer Dynamics and Tether Structure Affect Ligand Access to Receptors

An open and closed case: Estradiol was conjugated to a PAMAM dendrimer (gray circle) through a short (17α-phenylethynyl) or a long (hexaethyleneglycol) tether to evaluate how ligand access to a receptor is affected. With the short tether (a), the hormone is free and solvent exposed, with unimpeded access to the estrogen receptor, while the long tether (b) wraps around the hormone and the dendrimer and markedly reduces access to the receptor.