Browsing by Author "Muntele, C"

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    Enhanced biocompatibility of GPC by ion implantation and deposition
    Zimmerman, R; Gürhan, I; Muntele, C; Ila, D; Rodrigues, M; Özdal-Kurt, F; Sen, BH
    Biocompatible Glassy Polymeric Carbon (GPC) is used for artificial heart valves and in other biomedical applications. Although it is ideally suited for implants in the blood stream, tissue that normally forms around the moving parts of a GPC heart valve sometimes loses adhesion and creates embolisms downstream. We have previously shown that oxygen ion implantation slightly enhances cell adhesion to GPC. Here we compare silver ion implantation and silver deposition, each of which strongly inhibits cell attachment on GPC. Inhibition of cell adhesion is the more desirable improvement to current GPC cardiac implants. In vitro biocompatibility tests have been carried out with model cell lines to demonstrate that traces of silver can favorably influence the surface of GPC for biomedical applications. (c) 2007 Published by Elsevier B.V.
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    Modification of surface morphology of UHMWPE for biomedical implants
    Oztarhan, A; Urkac, ES; Kaya, N; Yenigul, M; Tihminlioglu, F; Ezdesir, A; Zimmerman, R; Budak, S; Muntele, C; Chhay, B; Ila, D; Oks, E; Nikolaev, A; Tek, Z; Eltem, R
    Ultra High Molecular Weight Polyethylene (UHMWPE) samples were implanted with metal and metal-gas hybrid ions (Ag, Ag+N, C+H, C+H+Ar, Ti+O) by using improved MEVVA Ion implantation technique [1,2]. An extraction voltage of 30 kV and influence of 1017 ions/cm2 were attempted in this experiment. to change their surface morphologies in order to understand the effect of ion implantation on the surface properties of UHMWPEs. Characterizations of the implanted samples with RBS, ATR - FTIR, spectra were compared with the un-implanted ones. Implanted and unimplanted samples were also thermally characterized by TGA and DSC. It was generally observed that C-H bond concentration seemed to be decreasing with ion implantation and the results indicated that the chain structure of UHMWPE were changed and crosslink density and polymer crystallinity were increased compared to unimplanted ones resulting in increased hardness. It was also observed that nano size cracks (approx. 10nm) were significantly disappeared after Ag implantation, which also has an improved antibacterial effect. Contact angle measurements showed that wettability of samples increased with ion implantation. Results showed that metal and metal+gas hybrid ion implantation could be an effective way to improve the surface properties of UHMWPE to be used in hip and knee prosthesis.
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    Polymeric thermal analysis of C+H and C+H+Ar ion implanted UHMWPE samples
    Kaya, N; Oztarhan, AM; Urkac, ES; Ila, D; Budak, S; Oks, E; Nikolaev, A; Ezdesir, A; Tihminlioglu, F; Tek, Z; Cetiner, S; Muntele, C
    Chemical surface characterization of C + H hybrid ion implanted UHMWPE samples were carried out using DSC (differential scanning calorimeter) and TGA (thermal gravimetric analysis) techniques. Samples were implanted with a fluence of 10(17) ion/cm(2) and an extraction voltage of 30 kV. The study of TGA and DSC curves showed that: (1) Polymeric decomposition temperature increased, (2) T-m, Delta C-p and Delta H-m values changed while Delta C-p and Delta H-m increased. T-g value could not be measured, because of some experimental limitations. However, the increase in Delta H-m values showed that T-g values increased, (3) the branch density which indicated the increase in number of cross-link (M-c) decreased in ion implanted samples and (4) increase in Delta H-m values indicated increase in crystallinity of implanted surface of UHMWPE samples. Published by Elsevier B.V.
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    Thermal characterization of Ag and Ag plus N ion implanted ultra-high molecular weight polyethylene (UHMWPE)
    Urkac, ES; Oztarhan, A; Tihminlioglu, F; Kaya, N; Ila, D; Muntele, C; Budak, S; Oks, E; Nikolaev, A; Ezdesir, A; Tek, Z
    Most of total hip joints are composed of ultra-high molecular weight polyethylene (UHMWPE). However, as ultra-high molecular weight polyethylene is too stable in a body, wear debris may accumulate and cause biological response such as bone absorption and loosening of prosthesis. In this study, ultra-high molecular weight polyethylene samples were Ag and Ag + N hybrid ion implanted by using MEVVA ion implantation technique to improve its surface properties. Samples were implanted with a fluence of 10(17) ion/cm(2) and extraction voltage of 30 kV. Implanted and unimplanted samples were investigated by thermo-gravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), optical microscopy (OM) and contact Angle measurement. Thermal characterization results showed that the ion bombardment induced an increase in the % crystallinity, onset and termination degradation temperatures of UHMWPE. (c) 2007 Elsevier B.V. All rights reserved.
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    Investigation of cell growth on ion beam patterns on GPC surface
    Zimmerman, R; Muntele, C; Gurhan, I; Ozdal-Kurt, F; Sen, BH; Rodrigues, M; Ila, D
    We have used implanted silver ions near the surface of Glassy Polymeric Carbon (GPC) to completely inhibit cell attachment and adhesion to GPC. The effect improves the safety and function of the GPC heart valve exposed to the blood stream. The strength, durability and low density make GPC a favored material for in vivo medical applications, including transcutaneous electrodes and replacement heart valves. However, the possible release of endothelial tissue that forms on the smooth surfaces of the GPC heart valve has the potential of creating an embolism. We have shown that L929 endothelial cells avoid silver implanted areas of GPC but attach and strongly adhere to areas close to silver implanted surfaces. Patterned ion implantation permits precise control of tissue growth on GPC and other biocompatible substrates. Cell growth inhibited by silver ion implanted patterns on an otherwise biocompatible substrate may be useful for in vitro studies of the way that cells sense and move away from inhospitable environments. (C) 2009 Published by Elsevier B.V.
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    Cell adhesion study of the titanium alloys exposed to glow discharge
    Abidzina, V; Deliloglu-Gürhan, I; Özdal-Kurt, F; Sen, BH; Tereshko, I; Elkin, I; Budak, S; Muntele, C; Ila, D
    Titanium for biomedical application stems mainly from its advantageous bulk mechanical properties in combination with a high degree of biocompatibility that is largely attributable to their surface properties. This work is focused on the investigation of surface properties of treated titanium and cell adhesion to titanium treated in glow-discharge plasma. Pure titanium samples (grade 4) were exposed to low-energy ion irradiation in a specially constructed plasma generator, where materials were irradiated by ions of residual gases in vacuum. The ion energy was 1-10 keV. The irradiation dose was maintained at 10(17) ions cm(-2). The irradiation time varied from 5 to 60 min. Rutherford backscattering spectrometry (RBS) was used for surface studies. RBS showed the presence of iron on the titanium surface that occurred from the cathode of plasma generator. In vitro biocompatibility test have been carried out with model cell lines (L929 mouse fibroblasts) to demonstrate that low-energy ion irradiation can favorably influence the surface of titanium for biomedical application. Scanning electron microscopy (SEM) was the main tool to demonstrate the cell attachment properties. (c) 2007 Elsevier B.V. All rights reserved.