Browsing by Author "Alava, J.I."
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Item Bone cell adhesion on ion implanted titanium alloys(2005-06-22) Braceras, I.; Onate, J.I.; Goikoetxea, L.; Viviente, J.L.; Alava, J.I.; de Maeztu, M.A.; Tecnalia Research & Innovation; Biomateriales; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThe authors have previously reported than ion implantation can have a significant effect on osseointegration of an implant, specially when the latter is introduced in areas of poorer bone density. These results indicate that this process is particularly suited for implant devices introduced in elderly patients or in those regions that have a poor quality of bone. The aim of this work is directed to study osteoblast adhesion on Ti alloy surfaces with different ion implantation treatments, so osseoconductive properties of several surfaces can be assessed. Polished discs of Ti–6Al–4V and Ti CP GR1 titanium alloy have been prepared and ion implanted with different species and parameters (dose and energy). Afterwards, the samples have been sterilized by UV light, inoculated with 1.5×105 human bone cells and incubated during 4 h at 37 C and 5% CO2 atmosphere. Then, once fixed and rinsed, image analysis has been used to quantify the number of cells attached to the Ti discs. On a second round of tests, cell proliferation tests have been conducted during 24, 48, 144 and 192 h, respectively. Furthermore, surface analysis techniques (e.g. AFM) have been applied to learn about the qualitative behavior, i.e. morphology, of the attached cells. Cell attachment has shown to be highly sensitive to ion implantation parameters. Although some quantitative differences have been observed, the more significant differences were qualitative. AFM analysis has shown that the star-shaped bone cells attached spread more and occupied larger surfaces like in osseointegration prone surfaces, most probably due to extracellular matrix synthesized around them, while other surfaces showed mainly large and narrow shaped or round shaped bone cells often with great cellular nucleus in the middle of the cells and little extracellular matrix around. So, ion implanted surfaces that facilitate osseointegration have been identified, in terms of initial bone cell attachment quality, where although the number of attached cells were not necessarily always larger, they tended to occupy wider areas with healthier cells.Item Enhancing Osteoconduction of PLLA-Based Nanocomposite Scaffolds for Bone Regeneration Using Different Biomimetic Signals to MSCs(2012-02) Ciapetti, Gabriela; Granchi, Donatella; Devescovi, Valentina; Baglio, Serena R.; Leonardi, Elisa; Martini, Desirèe; Jurado, Maria Jesus; Olalde, Beatriz; Armentano, Ilaria; Kenny, Josè M.; Walboomers, Frank X.; Alava, J.I.; Baldini, Nicola; Tecnalia Research & Innovation; BiomaterialesIn bone engineering, the adhesion, proliferation and differentiation of mesenchymal stromal cells rely on signaling from chemico-physical structure of the substrate, therefore prompting the design of mimetic “extracellular matrix”-like scaffolds. In this study, three-dimensional porous poly-L-lactic acid (PLLA)-based scaffolds have been mixed with different components, including single walled carbon nanotubes (CNT), micro-hydroxyapatite particles (HA), and BMP2, and treated with plasma (PT), to obtain four different nanocomposites: PLLA + CNT, PLLA + CNTHA, PLLA + CNT + HA + BMP2 and PLLA + CNT + HA + PT. Adult bone marrow mesenchymal stromal cells (MSCs) were derived from the femur of orthopaedic patients, seeded on the scaffolds and cultured under osteogenic induction up to differentiation and mineralization. The release of specific metabolites and temporal gene expression profiles of marrow-derived osteoprogenitors were analyzed at definite time points, relevant to in vitro culture as well asin vivo differentiation. As a result, the role of the different biomimetic components added to the PLLA matrix was deciphered, with BMP2-added scaffolds showing the highest biomimetic activity on cells differentiating to mature osteoblasts. The modification of a polymeric scaffold with reinforcing components which also work as biomimetic cues for cells can effectively direct osteoprogenitor cells differentiation, so as to shorten the time required for mineralization.Item Improved osseointegration in ion implantation-treated dental implants(2002-09) Braceras, I.; Alava, J.I.; Onate, J.I.; Brizuela, Marta; García-Luis, A.; Garagorri, N.; Viviente, J.L.; de Maeztu, M.A.; Oate, J. I.; INGENIERÍA DE SUPERFICIES; Tecnalia Research & Innovation; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSImplants for knee, hip and dental part replacement are becoming increasingly used in surgery. Unfortunately, their use is sometimes accompanied by failure due to infection, inflammation, integration problems with the surrounding tissues or bone, and implant failure due to mishandling. Surface treatment, such as ion implantation, has been identified as a good candidate to modify the surface properties of the implant to significantly improve its osseointegration. This work reports on the ion implantation of light ions in commercial Ti6Al4V dental implants and subsequent osseointegration tests. Various light ions were implanted (C, N, CO, Ne) with energy ranging from 45 to 100 keV and doses up to 5×10e17 ions/cm2. Both ion-implanted and control dental implants were inserted in the tibial plateau of adult rabbits, the epiphysis and diaphysis of the tibia for the evaluation of their degree of osseointegration. After 3 months the implants were extracted and several histological sections were prepared from whole bones for evaluation of their osseointegration in the tibia. In addition, the surface of the implant, and the interface between the bone and the implant were examined by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques. Some ion implantation treatments did not significantly change the performance of the dental implants relative to the untreated implants, while tests showed that the ion implantation of CO remarkably improved the osseointegration properties, i.e. the percentage of bone and implant in contact.Item Wear reduction effect on ultra-high-molecular-weight polyethylene by application of hard coatings and ion implantation on cobalt chromium alloy, as measured in a knee wear simulation machine(2001-07) Onate, J.I.; Comin, M.; Braceras, I.; García-Luis, A.; Viviente, J.L.; Brizuela, Marta; Garagorri, N.; Peris, J.L.; Alava, J.I.; Oate, J. I.; Garcia, A.; Tecnalia Research & Innovation; INGENIERÍA DE SUPERFICIES; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThe most important factor affecting performance and longevity of hip joint and knee implants is the wear rate of the ultra-high-molecular-weight polyethylene (UHMWPE) component. UHMWPE wear debris has been linked to complications including tissue inflammation, bone loss (osteolysis) and implant loosening. Reduction of debris has been addressed by investigating new polyethylene formulations, manufacturing and finishing processes, including surface treatments and coatings both on plastic and metallic components. There have been many studies on the effect of surface treatments and hard coatings on cobalt chromium and titanium alloys for prosthetic applications. However, most of them have used laboratory tribo-testers without much correlation to articulating movements in human joints. In this work, hard coatings (TiN and DLC) and surface treatments (nitrogen ion implantation) have been investigated as potential candidates to reduce wear of UHMWPE, when applied on the counter face cobalt chromium alloy. Also the effect of applying nitrogen ion implantation on the UHMWPE surface itself has been investigated. To evaluate wear performance a special knee wear simulator has been used with a combined rolling-sliding movement that corresponds to the most unfavourable situation in the knee. As testing materials, conventional coated and uncoated Co–Cr as well as Al2O3 femoral heads were used against UHMWPE plates to obtain comparative data. Testing was carried out at 50 MPa using distilled water at 37±2°C as a lubricant. Wear measurements on UHMWPE were made following ASTM F732 standard by weight loss measurements and also by laser profilometry. The results, up to 5 million wear cycles that represent approximately 3 years of implant life, clearly have demonstrated the beneficial effects of diamond-like carbon (DLC) and ion implantation (both on Co–Cr and UHMWPE) in reducing wear of UHMWPE. Similar values were also obtained for Al2O3 ceramic material. A wear reduction up to approximately five times was obtained by the former materials, in comparison with the uncoated control specimen. However, the ion plated TiN coating increased significantly wear on the UHMWPE. Transference of UHMWPE to the ball was very evident with the uncoated control and TiN coated Co–Cr, as observed by SEM, but with DLC and the ceramic material this occurred to a much lesser extent. Some micro-delamination at the worn surface of the UHMWPE was observed when wearing against uncoated Co–Cr, but was not clear in the rest options. Ion implantation and DLC can thus be two good candidate treatments to reduce wear of UHMWPE in cobalt chromium knee and hip joint implants in substitution of a more expensive ceramic material. This DLC has passed all biocompatible tests in accordance with FDA regulations and ISO 10993 standards for implantable devices. An example of a uniformly DLC coated femoral head and knee implant is shown.