Formation of Oligopeptide-Based Polymeric Membranes at Interfaces between Aqueous Phases and Thermotropic Liquid Crystals

We report a method for the synthesis of oligopeptide-based polymeric membranes at interfaces between aqueous phases and immiscible liquid crystals. The polymeric membrane was generated by contacting an aqueous solution of the oligopeptide SNKTRIDEANQRATK{Nle}L with a thermotropic liquid crystal, 4-cyano-4‘-pentylbiphenyl, doped with adipoyl chloride (cross-linking reagent). We report characterization of the membrane by scanning electron microscopy and measurements of the permeability of the membrane to phospholipids. The permeability of the polymeric membrane to phospholipids was evaluated by monitoring the orientational response of the liquid crystal upon contact with an aqueous dispersion of vesicles of l-α-dilauroyl phosphatidylcholine. We measured incubation of the membrane in an aqueous solution of trypsin to cause an increase in the permeability of the polymeric membrane to the phospholipids. In contrast, polymeric membranes incubated in aqueous solutions of α-chymotrypsin and bovine serum albumin did not exhibit enhanced permeability, as revealed by the orientational response of the liquid crystals. These results suggest new materials and methods for reporting the presence of enzymes.