There is a need for biomimetic materials for use in blood-contacting devices. Blood contacting surfaces maintain their patency through physico-chemical properties of a functional endothelium. A poly(carbonate-urea) urethane (PCU) is used as a base material to examine the feasibility of L-Arginine methyl ester (L-AME) functionalized material for use in implants and coatings. The study hypothesizes that L-AME, incorporated into PCU, functions as a bioactive porogen, releasing upon contact with blood to interact with endothelial nitric oxide synthase (eNOS) present in blood. Endothelial progenitor cells (EPC) were successfully cultured on L-AME functionalized material, indicating that L-AME -increases cell viability. L-AME functionalized material potentially has broad applications in blood-contacting medical devices, as well as various other applications requiring endogenous up-regulation of nitric oxide, such as wound healing. This study presents an in-vitro investigation to demonstrate the novel antithrombogenic properties of L-AME, when in solution and when present within a polyurethane-based polymer.There is a need for biomimetic materials, which can resist thrombosis associated with blood contacting devices which include 1 ; cardiovascular implants, such as vascular bypass grafts, synthetic heart valves, vascular access devices, cardiac patches, coatings for stents, pacemakers as well as implants for wound healing. Several materials currently in clinical use such as polytetrafluoroethylene (ePTFE), polyethylene terephthalate (Dacron ® ) and polyurethane are suboptimal 2 , and often lead to graft failure due to their inherent thrombogenic nature 3 . Ideal materials should possess suitable mechanical properties that provide the required structural support, and mimic the properties of the endothelium; the inner-most blood-contacting tissue in the cardiovascular system. The endothelium, maintains smooth blood flow and nitric oxide (NO) is a key player. NO has the ability to inhibit platelet aggregation and activation, and produce smooth muscle relaxation through activation of the cyclic guanylate monophosphate (cGMP) pathway 4 . It also inhibits smooth muscle cell proliferation. Moreover, NO aids endothelialization, wound healing; although the mechanism in unclear, it has been shown to promote re-epithelialization and collagen formation, as well as angiogenesis 5 . L-Arginine (L-Arg), a commonly occurring amino acid, is an endogenous substrate of nitric oxide synthase (NOS) 6 , a family of enzymes including neuronal NOS (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS), which all catalyze the formation of NO (along with citrulline) from L-Arg 7 . L-Arg therefore possesses anti-thrombogenic properties. eNOS produces the majority of the NO within the vascular system, and is present in red blood cells, which means that NO can be produced even in the absence of an endothelium 8,9 . Hence, L-Arg is important in cardiovascular physiology, and L-Arg supplementation in individuals with hypercholesterolemia or ath...

Introduction: Mimicking physiological functions of nitric oxide (NO) has applications in regenerative medicine. However, few NO delivery systems have progressed to clinical trials owing to limitations in delivery. Materials and methods: A novel NO delivery system was explored by integrating S-nitro-N-acetylpenicillamine-functionalized long-chain aliphatic hydrocarbons (LCAHs) into a polyurethane-based polymer. Results and discussion: Contact angle analysis determined the novel delivery system to be significantly more hydrophobic than control. Chemilluminscence showed a four-phase NO release profile of the delivery system with more stable and prolong NO release than control. Conclusion: LCAHs can optimize the duration and rate of NO delivery and present a viable option for use in surgical implants and biomedical applications.