P105 – Enzyme-Based Nitric Oxide Releasing Thin Films and Fibers

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Nitric Oxide


Nitric oxide (NO) is a powerful biological species involved in a number of physiological processes. Particularly, nitric oxide flux counteracts platelet aggregation, and therefore prevents the thrombosis cascade in the inner walls of blood vessels. Nitric oxide releasing coatings are thus used to prevent thrombus formation on the surface of blood-contacting medical devices and surfaces. Previous work in our lab has shown that nitric oxide synthase based thin films release fluxes of nitric oxide upon enzymatic conversion of the substrate L-arginine or N-hydroxy-arginine. In this work, we compare and contrast nitric oxide release from thin films as well as from electrospun fibers embedding nitric oxide synthase oxygenase domain. First, we report improved enzyme loading in layer-by-layer thin films of inducible nitric oxide synthase oxygenase (iNOSoxy) on polyethylenimine (PEI). We examine the effect of pH of the enzyme solution used to adsorb iNOSoxy from the solution on enzyme loading. We also examine the effect of adsorption pH on the overall activity of the enzyme in terms of NO flux released when the modified surface is exposed to a solution containing the ingredients of the NOS reaction. Second, we introduce a method of embedding active iNOSoxy in electrospun fibers of polycaprolactone (PCL), polyethylene-co-vinyl acetate (PEVA), and polyvinyl alcohol (PVA). We used scanning electron microscopy and fluorescence to characterize the NOSoxy-containing electrospun fibers. The activity of embedded iNOSoxy within the electrospun fibers is measured and used to optimize electrospinning conditions. Performances of NOS-containing layer-by-layer thin films and polymer-based electrospun fibers are compared and contrasted.