Graduate Thesis Or Dissertation
 

Synthesis and evaluation of PEO-coated materials for microchannel-based hemodialysis

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/4j03d259t

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  • The marked increase in surface-to-volume ratio associated with microscale devices for hemodialysis leads to problems with hemocompatibility and blood flow distribution that are more challenging to manage than those encountered at the conventional scale. In this work, stable surface modifications with pendant polyethylene oxide (PEO) chains were produced on polycarbonate microchannel and polyacrylonitrile membrane materials used in construction of microchannel hemodialyzer test articles. These coatings were evaluated in relation to protein repulsion, impact on urea permeability through the membrane, and impact on bubble retention through single-channel test articles. PEO layers were prepared by radiolytic grafting of PEO-PBD-PEO (PBD = polybutadiene) triblock copolymers to microchannel and membrane materials. Protein adsorption was detected by measurement of surface-bound enzyme activity following contact of uncoated and PEO-coated surfaces with β-galactosidase. Protein adsorption was decreased on PEO-coated polycarbonate and polydimethyl siloxane (PDMS) materials by 80% when compared to the level recorded on uncoated materials. Protein adsorption on membrane materials was not decreased with PEO-PBD-PEO treatment; a PEI (polyethylene imide) layer exists on the AN69 ST membrane which is intended to trap heparin during membrane pre-treatment. It is still unclear how this PEI layer interacts with PEO-PBD-PEO. Neither the PEO-PBD-PEO triblocks nor the irradiation process was observed to have any effect on polyacrylonitrile membrane permeability to urea, nor did the presence of additional fibrinogen and bovine serum albumin (BSA) in the urea filtrate. The PEO-PBD-PEO treatment was not able to visibly reduce bubble retention during flow through single-channel polycarbonate test articles, however, the rough surfaces of the laser-etched polycarbonate microchannels may be causing this bubble retention. This surface treatment holds promise as a means for imparting safe, efficacious coatings to blood processing equipment that ensure good hemocompatibility and blood flow distribution, with no adverse effects on mass transfer.
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