Enhanced Biocompatibility of GPC by MeV Ion Bombardment
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Enhanced Biocompatibility of GPC by MeV Ion Bombardment 1 2 1 1 3 R. Zimmerman , I. Gurhan , S. Sarkisov , C. Muntele1, and D. Ila and M. Rodrigues 1 Center for Irradiation of Materials, Alabama A&M University, Normal, AL 2 Ege University Faculty of Engineering, Izmir, Turkey 3 University of Sao Paulo, Ribeirao Preto SP Brazil
I ABSTRACT
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Glassy Polymeric Carbon (GPC) is completely biocompatible and is widely used
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as a material for artificial heart valves and in other biomedical applications. Although it
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is ideally suited for fluid flow in the blood stream, collagenous tissue that normally forms
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around the moving parts of a GPC heart valve sometimes loses adhesion and creates
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embolisms downstream. We have shown that moderate fluence of MeV ions, especially
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oxygen ions, increases the surface roughness of GPC on a scale appropriate for enhancing
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tissue adhesion. Silver ion implantation is shown to inhibit cell growth on GPC. Ion
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bombardment also increases the surface hardness of GPC, already an extremely hard
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material. In vitro biocompatibility tests have been carried out with model cell lines to
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demonstrate that MeV ion bombardment can favorably influence the surface of GPC for
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biomedical applications.
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Key Words Carbon biomaterials, Carbon, Tissue adhesion Corresponding Author Robert Zimmerman Alabama A&M University Research Institute P. O. Box 1447 Normal, ALABAMA 35672 TEL 256372 5854 FAX 256 372 5868 [email protected]
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II INTRODUCTION
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Glassy Polymeric Carbon (GPC) is an outstanding and versatile biomaterial [1-5]
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owing to its electrical, mechanical and chemical properties, which include exceptional
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biocompatibility. The density (1.45 g/cm3) of GPC is significantly lower than that of
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graphite from which one may deduce a relative pore volume of about 35% although the
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material is among the most impermeable known. Its structure has intertwined graphene
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planes that enclose voids.
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The strength, durability and low density make GPC a favored material for the
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manufacture of replacement heart valves. However the low adhesion at the interface with
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biological tissue [6] has the potential of creating an embolism when endothelial tissue
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that naturally encapsulates the implant is released into the blood stream. Greater tissue
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adhesion can be achieved by making the surface rough. The texture dimensions and
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chemical affinity of the surface should be adequate to allow strong adherence of tissue on
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the material surface. Alternatively, surface treatment by an appropriate ion implantation
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may be expected to inhibit cell growth or give the cells no adherence at all.
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We report the use of oxygen ion bombardment to increase the surface roughness, to enhance cell adhesion, and implantation of silver ions that inhibit cell growth.
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III EXPERIMENTAL METHODS
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GPC samples were prepared from liquid resol C7H8O2 precursor in accordance
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