Investigation of Nitric Oxide Synthase (NOS) Redox and Catalytic Activity in Electrospun Fibers

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Nitric oxide (NO) is known to counteract platelet aggregation in mammals, and thus can stop the thrombosis cascade on the surface of blood-contacting medical devices. Nitric oxide synthases (NOSs) are enzymes responsible for catalytic conversion of the substrate L-arginine to NO and L-citrulline. By using NO releasing biomaterial that mimic mammalian tissue, one may be able to solve the issue of thrombosis on the surface of foreign devices implanted or used as part of cardiovascular procedures. In the past, we have tested the use of NOS enzymes in layer-by-layer thin films as a source of in-situ NO generation and release. Our objective in the current work is to use NOS enzymes trapped in electrospun fibers as a biocompatible platform for NO release.

Methods and Results:

In this project, we investigate the possibility to use nitric oxide synthase (NOS) as NO-making component trapped in aqueous pockets of electrospun biopolymer matrices. The polymers used in this preliminary work are polycaprolactone (PCL) and Polyurethane (PU). A guided stream of polymer solution containing suspended aqueous pockets of enzyme solution is directed towards a collector drum (or an electrode) in strong electric field. In its path of acceleration towards the target, the solvent evaporates and the charged jet thins-out leaving a fibrous membrane, devoid of solvent and containing ‘nodes’ of aqueous pockets with entrapped NOS enzymes. Surface characterizations such as Transmission Electron Microscopic (TEM) and Atomic Force Microscopic (AFM) imaging are carried out on the newly formed NOS-containing electrospun fibers. Further, the NOS-modified membranes are tested electrochemically using a characteristic electrocatalytic reaction mediated by entrapped NOS enzymes. Finally, the NOS-containing electrospun membranes are subject to assays under various conditions to determine the structural integrity of NOS enzymes and their enzymatic activity. Just like the case of our layer-by-layer films reported earlier, we find that the entrapped NOS in electrospun fiber conserves its redox activity and catalytic function. Results on NO flux measurements under physiologically relevant conditions will be presented and discussed.


Abstract 2496

Presented at:
220th ECS Meeting
MA2011-02, October 9 - October 14, 2011, Boston, MA