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  • 1.
    Shbeh, Mohammed
    et al.
    Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, UK.
    Wally, Zena J.
    Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Sheffield, UK.Insigneo Institute for in Silico Medicine, University of Sheffield, Pam Liversidge Building, Sheffield, UK.The University of Kufa, College of Dentistry, Department of Prosthodontic, Iraq.
    Elbadawi, Mohammed
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Mosalagae, Mosalagae
    Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, UK.
    Al-Alak, Hassan
    University of Kufa, Faculty of Engineering, Department of Materials Engineering, Iraq.
    C. Reilly, Gwendolen
    Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, UK.Insigneo Institute for in Silico Medicine, University of Sheffield, Pam Liversidge Building, Sheffield, UK.
    Goodall, Russell
    Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, UK.
    Incorporation of HA into porous titanium to form Ti-HA biocomposite foams2019Ingår i: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 96, s. 193-203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ti foams are advanced materials with great potential for biomedical applications as they can promote bone ingrowth, cell migration and attachment through providing interconnected porous channels that allow the penetration of the bone-forming cells and provide them with anchorage sites. However, Ti is a bio-inert material and thus only mechanical integration is achieved between the porous implant and the surrounding tissue, not the chemical integration which would be desirable. In this work particles of a biologically active material (Hydroxyapatite, HA) are blended with titanium powder, and used to produce Ti foams through the use of Metal Injection Moulding (MIM) in combination with a space holder. This produces titanium foams with incorporated HA, potentially inducing more favourable bone response to an implant from the surrounding tissue and improving the osseointegration of the Ti foams. To be able to do this, samples need to show sufficient mechanical and biocompatibility properties, and the foams produced were assessed for their mechanical behaviour and in vitro biological response. It was found that the incorporation of high levels of HA into the Ti foams induces brittleness in the structure and reduces the load bearing ability of the titanium foams as the chemical interaction between Ti and HA results in weak ceramic phases. However, adding small amounts of HA (about 2 vol%) was found to increase the yield strength of the Ti foams by 61% from 31.6 MPa to 50.9 MPa. Biological tests were also carried out in order to investigate the suitability of the foams for biomedical applications. It was found that Ti foams both with and without HA (at the 2 vol% addition level) support calcium and collagen production and have a good level of biocompatibility, with no significant difference observed between samples with and without the HA addition.

  • 2.
    Elbadawi, Mohammed
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Rheological and Mechanical Investigation into the Effect of Different Molecular Weight Poly(ethylene glycol)s on Polycaprolactone-Ciprofloxacin Filaments2019Ingår i: ACS Omega, E-ISSN 2470-1343, Vol. 4, nr 3, s. 5412-5423Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fused deposition fabrication (FDF) three-dimensional printing is a potentially transformative technology for fabricating pharmaceuticals. The state-of-the-art technology is still in its infancy and requires a concerted effort to realize its potential. One aspect includes the processing parameters of FDF and the effect of formulation thereto, which, to date, have not been thoroughly investigated. To progress understanding, the effect of different molecular weight poly(ethylene glycol)s (PEG) on polycaprolactone (PCL) loaded with ciprofloxacin (CIP) was investigated. A rheometer was used, and adapted accordingly, to analyze three processing aspects pertaining to FDF: viscosity, solidification, and adhesion. The results revealed that both CIP and PEG affected all three processing parameters. The salient findings were that the ternary blend with 10% w/w PEG 8000 exhibited rheological and adhesive properties ideal for FDF, as it provided a desirably shear-thinning filament that solidified rapidly, and improved the adhesion strength, in comparison to both the PCL-CIP binary blend and other ternary blends. In contrast, the ternary blend with 15% w/w PEG 200 was unfavorable; despite having a greater plasticizing effect, whereby the viscosity was markedly reduced, the sample provided no benefit to the solidification behavior of PCL-CIP and, in addition, failed to display adhesive behavior, which is a necessity for a successful print in FDF. The original findings herein set the precedent that the effect of drug and PEG on FDF processing should be considered beyond solely modifying the viscosity.

  • 3.
    Elbadawi, Mohammed
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap. Department of Mechanical Engineering, University of Sheffield, Sheffield, United Kingdom.
    Wally, Zena J.
    Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK.
    Reaney, Ian
    Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK.
    Porous Hydroxyapatite-Bioactive Glass Hybrid Scaffolds Fabricated via Ceramic Honeycomb Extrusion2018Ingår i: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 101, nr 8, s. 3541-3556Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The successful fabrication of hydroxyapatite-bioactive glass scaffolds using honeycomb extrusion is presented herein. Hydroxyapatite was combined with either 10 wt% stoichiometric Bioglass® (BG1), calcium-excess Bioglass® (BG2) or canasite (CAN). For all composite materials, glass-induced partial phase transformation of the HA into the mechanically weaker β-tricalcium phosphate (TCP) occurred but XRD data demonstrated that BG2 exhibited a lower volume fraction of TCP than BG1. Consequently, the maximum compressive strength observed for BG1 and BG2 were 30.3 ± 3.9 and 56.7 ± 6.9 MPa, respectively, for specimens sintered at 1300 °C. CAN scaffolds, in contrast, collapsed when handled when sintered below 1300 °C, and thus failed. The microstructure illustrated a morphology similar to that of BG1 sintered at 1200 °C, and hence a comparable compressive strength (11.4 ± 3.1 MPa). The results highlight the great potential offered by honeycomb extrusion for fabricating high-strength porous scaffolds. The compressive strengths exceed that of commercial scaffolds, and biological tests revealed an increase in cell viability over seven days for all hybrid scaffolds. Thus it is expected that the incorporation of 10 wt% bioactive glass will provide the added advantage of enhanced bioactivity in concert with improved mechanical stability.

  • 4.
    Elbadawi, Mohammed
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Meredith, James
    Mosalagae, Mosalagae
    Reaney, Ian M
    Porous hydroxyapatite scaffolds fabricated from nano-sized powder via honeycomb extrusion2017Ingår i: Advanced Materials Letters, ISSN 0976-3961, E-ISSN 0976-397X, Vol. 8, nr 4, s. 377-385Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, we have developed hydroxyapatite (HA) scaffolds for synthetic bone graft from nano-sized HA particles using ceramic extrusion. We also demonstrate that these HA scaffolds show enhanced compressive strength (29.4 MPa), whilst possessing large pore sizes (> 600 µm) that are suitable for bone grafting. The extrusion process involved forming a ceramic paste by mixing the HA powder with a binder and distilled water. The ceramic paste was then fabricated using a ram extruder that was fitted with a honeycomb die to impart large, structured pores. Several green bodies were extruded and then subjected to the same drying and thermal debinding treatment. The samples underwent three different sintering temperatures and two varied dwell times, in order to determine the optimum sintering parameters. The scaffolds were then analysed for their chemical, physical, mechanical and biological properties to elucidate the effects of the sintering parameters on extruded HA scaffolds. The results revealed that the nano-sized particles exhibited a high sinterability, and XRD analysis showed phase purity until 1300 oC. At 1300 oC, trace amounts of phase impurities were detected, however, scaffolds sintered at this temperature exhibited the highest mean compressive strength. The findings demonstrated that traces of phase impurities were not detrimental to the scaffold’s compressive strength. In addition, scanning electron microscopy and density measurements revealed a highly densified solid phase was attained.

  • 5.
    Elbadawi, Mohammed
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Mosalagae, Mosalagae
    Goodall, Russell
    Tape casting and lost carbonate sintering processes for production of heat sinks for portable electronics2017Ingår i: Advanced Materials Letters, ISSN 0976-3961, E-ISSN 0976-397X, Vol. 8, nr 7, s. 807-812Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Porous copper was fabricated by means of a powder metallurgy process applied to tape casting. Lost Carbonate Sintering (LCS) was employed to control porosity within the component during processing. The weight ratio of the potassium carbonate introduced into the matrix ranged from 30-40 wt%. Additives such as; plasticizers, binders, dispersant and solvents were utilized to control the properties throughout the processes and ease fabrication. The component was debinded and sintered at 400 °C and 900 °C respectively, under vacuum. The potassium carbonate was removed from the sintered component via dissolution in water. By using X-ray Florescence (XRF) and Energy Dispersive X-ray Spectrometry (EDS) techniques, the effectiveness of the dissolution route at removing the space holder was investigated. The results shows that porous copper produced in this way has porosity ranging from 75-85 % and pore size from 500-766 mm. The component produced has thickness ranging from 1300 -1800 mm.

  • 6.
    Elbadawi, Mohammed
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap. Department of Mechanical Engineering, University of Sheffield.
    Meredith, James
    Department of Mechanical Engineering, University of Sheffield.
    Hopkins, Lynne
    Department of Material Science and Engineering, University of Sheffield.
    Reaney, Ian
    Department of Material Science and Engineering, University of Sheffield.
    Progress in Bioactive Metal and, Ceramic Implants for Load-Bearing Application2016Ingår i: Advanced Techniques in Bone Regeneration / [ed] Alessandro Rozim Zorzi and Joao Batista de Miranda, Croatia: INTECH, 2016Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    The field of biomaterials is an exuberant and enticing field, attracting interest across a number of scientific disciplines. Synthetic materials such as metals and ceramics have helped civilisation accomplish many feats, and this can also be said for the achievements in orthopaedic applications. Metals and ceramics have achieved success in non-load-bearing applications and attempts are made to translate the accomplishments into weight-bearing applications. For this, a material needs to be porous but with sufficient strength to withstand daily loading; however, both properties are mutually exclusive. The implant must also avoid causing adverse reactions and toxicity and, preferably, bond to the surrounding tissues. Metals such as stainless steels and chromium-cobalt alloys have been used due to their excellent mechanical properties that can withstand daily activities, but retrospective studies have alluded to the possibilities of significant adverse reaction when implanted within the human body, caused by the elution of metal ions. Lessons from metals have also demonstrated that materials with significantly higher mechanical properties will not necessarily enhance the longevity of the implant—such is the complexity of the human body. Ceramics, on the other hand, exhibit excellent biocompatibility, but their mechanical properties are a significant hindrance for load-bearing use. Thus, the chapter herein provides a select overview of contemporary research undertaken to address the aforementioned drawbacks for both metals and ceramics. Furthermore, the chapter includes a section of how metals and ceramics can be combined in a multi-material approach to bring together their respective properties to achieve a desirable characteristics.

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