Persistent Inhibition of Cell Growth on Silver Implanted Glassy Polymeric Carbon
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0950-D04-19
Persistent Inhibition of Cell Growth on Silver Implanted Glassy Polymeric Carbon Robert L. Zimmerman1, Ismet Gürhan2, F. Ozdal-Kurt3, B. H. Sen4, Marcello Rodrigues5, and Daryush Ila1 1 Alabama A&M University, 4900 Meridian Street, Normal, AL, 35762 2 Faculty of Engineering, Ege University, Izmir, 87985, Turkey 3 CBU Faculty of Science, Manisa, 45673, Turkey 4 EU Faculty of Dentistry, Izmir, 34679, Turkey 5 University of São Paulo, Ribeirão Preto, 49100, Brazil INTRODUCTION: The electrical, mechanical and chemical properties of (GPC) make it an exceptionally versatile biomaterial. Like other forms of pure carbon, GPC objects implanted in living tissue remain inert and have no biological influence on neighboring organs. Cells of connective tissue eventually encapsulate the GPC object. The formation of a completely biocompatible interface with biological tissue is an important attribute for carbon trans coetaneous electrodes or semi permanent fluid delivery tubes. The strength, durability and low density make GPC a favored material for the manufacture of replacement heart valves. However, the low adhesion at the interface with biological tissue [1] has the potential of creating an embolism when endothelial tissue that naturally encapsulates the implant is released into the blood stream. AAMU researchers have reported [2, 3] the use of oxygen ion bombardment to increase the surface roughness, to enhance cell adhesion, and they have shown [4, 5] that implanted silver ions near the surface of GPC inhibit cell attachment and adhesion. Both enhancement and inhibition of cell attachment to GPC are desirable modifications of GPC for particular medical applications. Silver ions implanted in GPC with the AAMU Pelletron ion accelerator at the Howard J. Foster Center for Irradiation of Materials (CIM), completely inhibit the growth of cells on the surface of GPC, without significant toxic effect elsewhere. The depth and distribution of the silver ions and their kinematic products expected from a SRIM [6] simulation is shown in Figure 1. Figure 2 shows the boundary between silver ion implanted areas of GPC and areas with no treatment. The cell growth tests have been carried out in collaboration with biologists at the Ege University, Izmir, Turkey [5]. EXPERIMENTAL METHOD: The GPC samples were prepared from phenol resin and heat treated to 700oC by methods that have been reported elsewhere [7-10 ]. The GPC samples, typically a few hundred microns thick and 1 x 5 cm2 area, were placed in an evacuated implantation chamber where a 1 MeV silver ions, accelerated by the AAMU Pelletron ion accelerator, were scanned uniformly across the area of the GPC sample. Silver foil masks covered parts of the sample to permit patterned implantation of the fast silver ions. Figure 1 shows the SRIM [6] simulation of the effect that individual 1 MeV silver ions have near the GPC surface exposed to the ion beam. The incident silver ions stop and
remain in a diffuse layer about 550 nm below the surface. Before coming to rest, each silver
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