Incorporation and characterization of biological molecules in droplet-interface bilayer networks for novel active systems

摘要

Biological molecules including phospholipids and proteins offer scientists and engineers a diverse selection ofmaterials to develop new types of active materials and smart systems based on ion conduction. The inherentenergy-coupling abilities of these components create novel kinds of transduction elements. Networks formed fromdroplet-interface bilayers (DIB) are a promising construct for creating cell mimics that allow for the assemblyand study of these active biological molecules. The current-voltage relationship of symmetric, "lipid-in" droplet-interface bilayers are characterized using electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV)."Lipid-in" diphytanoyl phosphatidylcholine (DPhPC) droplet-interface bilayers have specific resistances of nearly10MΩ·cm~2and rupture at applied potentials greater than 300mV, indicating the "lipid-in" approach produceshigher quality interfacial membranes than created using the original "lipid-out" method. The incorporationof phospholipids into the droplet interior allows for faster monolayer formation but does not inhibit the self-insertion of transmembrane proteins into bilayer interfaces that separate adjacent droplets. Alamethicin proteinsinserted into single and multi-DIB networks produce a voltage-dependent membrane conductance and currentmeasurements on bilayers containing this type of protein exhibit a reversible, 3-4 order-of-magnitude conductanceincrease upon application of voltage.