(259n) Impedance Analysis of Ion Transport through Supported Lipid Bilayers on Accessible Mesoporous Silica Thin Films
As the barriers between cells and external environment, biological membranes exhibit highly selective permeability to molecules and ions, which is maintained by its main component, amphipathic lipid molecules and the embedded membrane proteins. Supported lipid bilayers allow the use of surface analysis techniques and are model systems for exploring the application of lipid bilayers in biosensing, selective separations and drug delivery. Mesoporous silica thin films are advantageous supports due their biocompatible properties and nanoporous architecture, which creates space for the incorporation of proteins and provides molecules or ions reservoirs underneath the lipid bilayer. Combining the high surface area silica thin film with the selective permeable lipid bilayers suggests potential applications for efficient selective aqueous solute separations and biosensing. While this biomimetic membranes hold great potential, an important step in these applications is to thoroughly examine the transport processes in composite synthetic membranes. In transport applications, the pore accessibility of silica thin film is a priority. In this work, silica thin films with orthogonally aligned hexagonal pore arrays, which offer continuous channels for molecule transport, are prepared. The thin film pore accessibility is characterized by electrochemical impedance spectroscopy (EIS) technique. Furthermore, the effect of lipid bilayer preparation methods on the silica thin film (in the form of pore enveloping, pore filling, tethering) on ion transport is explored, as a lipid bilayer with high electrically insulation is essential for detecting activity of proteins or biomimetic carriers in the bilayer. This study provides insights for making better barriers on mesoporous support for carrier-mediated membrane separation process.