Investigation of Peroxynitrite–Biomembrane Interactions Using Biomimetic Interfaces
Peroxynitrite (ONOO− or PON for short) and its associated radical products are clinically important reactive nitrogen oxide species that play key roles in several devastating diseases. Some PON-induced disease processes involve lipid oxidation or nitration. Peroxidation of phospholipids can compromise a biomembrane's integrity and alter its fluidity and electrochemical resistance. The inherent complexity of intact biomembranes makes investigation of PON-induced damage challenging. The use of biomimetic interfaces consisting of synthetic bilayer lipid membranes (BLM) that have a known composition enables controlled studies to be performed and hypotheses to be tested. A variety of characterization tools are available to study the effect of PON on such biomimetic interfaces. Traditional electrophysiology approaches can be used to study transient pore formation in unsupported, planar BLM. Application of electrochemical impedance spectroscopy to BLM that are tethered to electrodes can be used to measure biomembrane capacitance and ion permeability. Optical methods based on hydrophobic fluorescent probes that partition into biomembranes can provide parallel measurements. Simultaneous use of multiple characterization tools could provide real-time, label-free measurements of PON concentration and its effect on biomembrane properties. This chapter summarizes mechanisms by which PON damages membrane lipids, describes common biomimetic interface platforms and electrochemical and optical techniques used to characterize them, and demonstrates a novel application of a biomimetic interface to measure the effect of PON exposure on a biomembrane's electrochemical resistance.