UBC Theses and Dissertations

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UBC Theses and Dissertations

Improving platelet storage bags : antifouling polymer coatings, antimicrobial peptides and surface topography Hadjesfandiari, Narges


This thesis is aimed at developing an antibacterial and biocompatible coating for platelet storage bags. Platelets are blood cells that play an essential role in stopping bleeding. Stored platelets for transfusion have a limited shelf life due to the loss of platelet quality upon storage and the risk of bacterial growth in the storage bags. The hydrophobic surface of plasticized polyvinyl chloride platelet storage bags is conducive to bacterial adhesion, biofilm formation and platelet adhesion. In Chapter 1 platelet transfusion and the associated challenges as well as biomaterials’ surface characteristics and biocompatibility are introduced. In Chapter 2 some hydrophilic polymer brushes are developed on platelet bag surfaces and characterized. Polymer coatings made of poly(N,N-dimethylacrylamide) (PDMA) and a copolymer of DMA and N-(3-aminopropyl)methacrylamide hydrochloride (APMA) (DMA/APMA: 5/1) could inhibit bacterial adhesion on platelet bag surfaces under growth conditions by 95 % and 70 % respectively. These coated surfaces also showed decreased platelet adhesion. To add bactericidal activity to the coating, antimicrobial peptides (AMPs) are then conjugated to polymer brushes and characterized in Chapter 3. These coated substrates increased the level of platelet adhesion and activation, however. Tuning the amount of peptide on bag surfaces and reproducing coated surface characteristics (with or without peptides) were both challenging. Taking another approach in Chapter 4, mussel-inspired chemistry is used to coat platelet bags as well as gold and silicon wafers with the antifouling polymeric system. The optimum polymer coating could resist fibrinogen adsorption, bacterial and platelet adhesion. An AMP-containing bactericidal coating was also synthesized and coated on silicon wafers using this approach. AMPs were mapped on the modified surfaces and they showed bactericidal activity in vitro. A significance of the applied methods in this thesis is their compatibility with commercial biomaterials containing leachable plasticizers. The chemical composition and morphology of some platelet bags used in Canada are studied in Chapter 5. Evaluation of bacterial and platelet adhesion on their surfaces suggests fabricating bags with only one textured surface inside and positioning it above a non-textured surface. Potential commercial application of the coatings developed here has been a perspective of this project.

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