Proteins at interfaces and modification of surfaces for biological applications

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This research is in the area of biomaterials, i.e. materials that are used in contact with a biological system whether it be the human body, a bodily fluid like blood or tears, or any fluid that contains biological components. Our work is focused on biocompatibility and on understanding how proteins and cells interact at the interface between the biomaterial and the biosystem. In addition we exploit our developing understanding of these biointeractions in the design of new materials. The work has two main themes: (1) Protein interfacial behaviour: Proteins have a strong tendency to adsorb at interfaces and this has important consequences for a number of areas of biotechnology (eg medical devices, diagnostic systems, food processing, biosensors and protein separation and purification). There is a need for improved understanding of protein adsorption so that it can be controlled as required for a given purpose. We will be addressing the following broad questions: (a) the nature of protein surface binding, (b) the orientation of adsorbed proteins, (c) conformational changes and alteration of biologic function. We will study the adsorption kinetics and equilibria of selected protein-surface systems and develop mechanistic models of adsorption. In this work we make use of advanced experimental methods such as neutron reflectometry (collaboration with NRC Chalk River) and methods requiring synchrotron radiation (Canadian Light Source). (2) Modification of solid surfaces: Surface modification is of great importance in biotechnology applications such as biosensors, bioprocess equipment and medical devices. In general one wants to keep the bulk properties of the material intact while tailoring the surface to impart specific properties, especially resistance to biofouling. Contact lenses, for example, are gradually "spoiled" by the uptake of proteins from tear fluid. Our research in this area is based on two main approaches: (a) modification of surfaces using gold-thiol chemistry, (b) polymer grafting using atom transfer radical polymerization (ATRP) a novel polymerization method which allows control over the polymer molecular weight distribution. Emphasis will be on non fouling surfaces.