APPLICATIONS OF IMPEDANCE SPECTROSCOPY IN BIOCHEMISTRY AND BIOPHYSICS

The present study is intended to demonstrate the application of impeda nce spectroscopy to two very different fields of biophysical research. The core component of our measuring setup is a self-constructed conti nuous wave impedance spectrometer together with special measuring cham bers which are individually designed for the systems under investigati on. We directed our attention towards: i) the investigation of solid s upported lipid bilayers in general, especially systems which are suita ble for protein reconstitution such as dimethyldioctadecylammonium bro mide (DODAB) immobilized onto a gold electrode, precovered with a nega tively charged monolayer of 3-mercaptopropionic acid. Impedance spectr oscopy allows to study the stability, the thickness and the electrode coverage of those artificial membranes as well as the observation of i on transport mediated by ionophores like gramicidin D incorporated int o a DODAB-bilayer. ii) The characterization of the passive electrical properties of epithelial and endothelial cell monolayers in general an d especially the determination of their transepithelial (transendothel ial) electrical resistances as a measure for epithelial barrier functi on. From impedance spectra, as reported here, we are able to follow th e formation and modulation of cell layer permeability to small ions.