Basic studies on biocompatible polymers

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Basic Studies on Biocompatible Polymers Coating synthetic materials with polymer 'brushes' has been found to resist but not eliminate rejection reactions that occur when unprotected foreign material contacts blood or tissues. We propose basic studies on some polymer systems we are using to (a) construct more biocompatible blood bags and (b) to replace human serum albumin (HSA) or deliver drugs with hyperbranched polyglycidol (HPG) that shares many of HSA's properties. POLYMER BRUSHES: Brushes refer to surfaces from which soluble polymers are grown at sufficiently high density that they are forced into an unusually extended, high energy structure. We have found that they can strongly affect the degree and type of protein adsorption that occurs when any material is exposed to blood or complex mixtures of proteins, rejecting to varying degrees many protein species at particular brush densities. We plan basic studies on brushes grown on both polystyrene latex particles and on flat polyvinyl chloride or silica chips to better understand these interactions. Specifically we will use AFM with 'colloidal' tips to study the properties of brush/protein systems; compare these to contact angle studies using phase separated aqueous two phase polymer mixtures, a parameter that is extremely sensitive to macromolecular structures on surfaces; utilize the new UBC TOF-SIMS instrument to study the composition of mixed protein films on brushes exposed to protein mixtures and understand the role of radius of curvature on brush behavior. HPGs: Hyperbranched polymers act somewhat like proteins because of their compact solution configuration and can be easily derivatized via the many OH groups available. Hydrophobic binding is critical for an HSA mimic and for drug delivery; detailed studies of this kind of reaction will be made as a function of structural properties as well as a thermodynamic study of mixtures containing HPGs to examine their interactions with water, other polymers and proteins. Using various HPG derivatives we will determine the access a second macromolecular species has to the interior of an HPG molecule and how to control it.