VASCULAR PROSTHESES MANUFACTURED BY SPRAY-ATOMEATION OF POLYMERS

Objectives: The use of porous materials for vascular prostheses can give some advantages over continuous surfaces. Porous surfaces encourage the formation of a thin neo-intimal layer onto the material, as has been shown by Karapinar et al. Matching the mechanical properties of the graft with physiological values also benefits the acceptance of the graft in the body. It Is therefore highly desirable to produce porous materials from biocompatlble polymers. Our goal is to develop a manufacturing process for vascular grafts, which produces thin fibers from a polymer solution, and has a higher throughput than electrospining. Methods: A pneumatic spray gun is used to atomize a polymer-solution and to form small droplets, which then dry and deform to fibers during their flight to the target. The nearly dry fibers then form a non-woven textile on the target The target can rotate and the spray gun can move in two axes. Factors like atomization pressure, material flow, solvent, concentration and polymer used can also be varied. Sprayed samples are inspected by microscope and subjected to tensile tests. Sterilization tests have been conducted with gamma, ETO, plasma and steam sterilization. Results: It is possible to spray fibers with a diameter of 1 mu m. The permeability of the textiles can be influenced by changing spraying parameters. Different polymers (PCU and PLA) have been successfully tested for this manufacturing process. The PLA can be used as a scaffold for tissue engineering, whereas the PCU can be used for polymeric graft prostheses. The PCU textiles showed good mechanical properties and a linear stress-strain behavior. The material can be sterilized by gamma, ETO and plasma sterilization. Conclusions: The spraying process shows promising results for the production of non-woven materials with properties beneficial to their application as grafts and scaffolds.