Electrochemical impedance spectrum reveals structural details of distribution of pores and defects in supported phospholipid bilayers.

In this study we developed a methodology for solving an inverse problem to obtain structural information about distribution of nanoscale defects in surface supported, tethered bilayer membranes (tBLMs) using the electrochemical impedance spectroscopy (EIS) technique. We demonstrate that the EIS spectra contain physical information about the electrical and structural parameters of tBLMs as well as information about distribution of density of defects in membranes. Such defects can be naturally occurring collapsed sites of bilayers due to imperfections of solid substrates onto which tBLMs are assembled. Also, the membrane defects can be introduced artificially by insertion of pore-forming toxin proteins into phospholipid bilayers or by other means such as electroporation. The proposed methodology can be used for the development of precision biosensors sensitive to agents impairing integrity of biological membranes, and in general studies of protein membrane interactions that involves damage of phospholipid bilayers.