Design of a Biologically Relevant Supported Bilayer Platform for the Study of Membrane Active Peptides

Abstract

Membrane active peptides represent a class of soluble proteins that interact and disrupt the plasma membrane. Examples of these include antimicrobial peptides, cancer therapeutics, and cell-penetrating peptides. These peptides are amphipathic and, in a concentration dependent manner, can self assemble to destabilize the lipid bilayer. These peptides are rich in positively charged lysine and arginine residues and thus have a strong preference for negatively charged bilayers. In order to study the insertion mechanism and kinetics of these peptides, we have designed a negatively charged, supported bilayer platform on silicon. The negative charge serves to electrostatically drive peptides to bind to the lipid bilayer interface. Furthermore, this platform is electrically addressable through electrochemical impedance spectroscopy, which yields bilayer resistance, thickness, and structural heterogeneity data. This platform consists of an asymmetrical bilayer with 10 mol% negatively charged POPS, cholesterol, and POPC in the upper leaflet and DPhPC lipids in the lower leaflet, all supported by a PEG cushion on a silicon wafer. Resistances up to 2∗104 Oημ cm2 and capacitances of 0.8 υF cm−2 have been measured for the platform. The high resistance allows for high accuracy in the detection of the activity of membrane active peptides of interest.