Templating Polypeptides on Self-Assembled Hemicylindrical Surface Micelles

Abstract

The adsorption of both random coil and α-helical poly l-arginine (PLA) on a surface templated by sodium dodecyl sulfate (SDS) hemicylindrical micelles is investigated and compared. Both secondary structures of PLA irreversibly adsorb on the SDS hemimicelles preserving the secondary conformation present in solution. However, the hemicylindrical SDS surface micelles induce aligned ordering of the α-helical PLA molecules by the adsorption of them into the grooves and at the top of the hemimicelles. For random coil PLA, ordering is not promoted by the surface hemimicelles. The surface concentration of the α-helical PLA is approximately 2 times larger than that for the random coil PLA although electrostatic attraction to the surface is largely screened by the presence of NaClO4 for the α-helical case. The results indicate that the adsorption process for α-helical PLA case is governed by a combination of electrostatic and van der Waals forces. Neutron reflectivity data show that the templated surface of surface micelles is not appreciably distorted by PLA adsorption. The nanostructure of surface micelles can induce order of a subsequent layer of adsorbed molecules allowing construction of macromolecular assemblies.