Dr. John Brash

Distinguished University Professor

A major theme of our studies is the interfacial behavior of proteins which is of great importance in biotechnology, diagnostics, and medical devices. Many of the products of biotechnology are genetically engineered proteins - e.g. insulin and growth factors. Processing presents unique problems due to the instability of these complex macro-molecules. For example, chromatography involving interaction of the proteins with solid surfaces is often used in final purification but can lead to molecular distortion and a biologically inactive, even though pure, product. An example in the medical devices field is blood compatible materials for arterial grafts, blood pumps and heart valves. A major unsolved problem here is blood coagulation/thrombosis believed to be initiated by the adsorption of plasma proteins to the surface of the implant. In these contexts we are studying the adsorption of a range of proteins using tube flow, serum replacement (equivalent to CSTR), and packed column experiments in conjunction with radiolabelled proteins. Media range from buffered solutions to blood. Specific interests are the kinetics, equilibria and reversibility of adsorption and changes in the structure and biologic function of adsorbed proteins. A prime objective is to correlate specific interactions with surface properties, e.g. wettability, electric charge, chemical composition. Materials for study, mostly polymers, are synthesized in the laboratory or are acquired from collaborating research groups around the world.