Browsing by Author "Chou, Joshua"

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    Adhesion and Scratch Testing of Antibiotic Loaded Poly-Lactic Acid Biocomposite Thin Films on Metallic Implants
    (Trans Tech Publications, 2018-10) Karacan, Ipek; Chou, Joshua; Ben-Nissan, Besim; Macha, Innocent J; Juritza, Arion; Wang, Andy H; Muller, Wolfgang H; Grossin, David; Taraschi, Valerio; Oktar, Faik N; Swain, Michael
    Surface modifications have been progressively applied in order to improve the mechanical, biological and chemical properties of metallic dental and orthopedic implants. Therefore, the novel and multifunctional biocomposites coating matrices, which also consist of local and targeted drug delivery systems, are the most recent applications in the medical field. In this study, gentamicin antibiotic containing HAp bioceramics were utilized in a biodegradable poly-lactic acid thin film matrix which was applied to Ti6Al4V metallic implant surfaces. Nanoindentation and scratch test methods were applied. It was observed that, bonding between coating and the substrate is strong enough to be used in implant applications. Additionally, it was observed that the hardness and Young's Modulus values of uncoated Ti6Al4V disc were 4.3 and 125.2 GPa, respectively. However, under the same testing conditions, it was also observed that the H values (0.6-0.8GPa) and the E (50-60 GPa) values of PLA-HAp biocomposite coated samples are slightly higher than the H values (0.4-0.6 GPa) and the E values (40-50GPa) of only PLA coated sample.
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    An Alternative Synthesis Method for Di Calcium Phosphate (Monetite) Powders from Mediterranean Mussel (Mytilus galloprovincialis) Shells
    (Springer NATURE, 2013-08) Macha, Innocent J; Ozyegin, Lutfiye S; Chou, Joshua; Samur, Ramazan; Oktar, Faik N; Ben-Nissan, Besim
    Marine species, such as corals, sea shells and nacres, attract special interest in bioceramics field for bone graft, bone cements and drug delivery applications. Most of the marine structures are made up of pure calcium carbonate (calcite or aragonite) with a very small amount of an organic matrix. In the past the most common way to transform these structures to hydroxyapatite was hydrothermal transformation method. This current work introduces a new approach for producing fine powders of calcium phosphates from Mediterranean mussel (Mytilus galloprovincialis) shells. A comparative study was carried out to investigate the differences of these powders under only hot plate heating and hot plate heating together with ultrasonic agitation while H3PO4 was added. The temperature of the hotplate was kept constant at 80 oC and then, H3PO4 was added drop wise into the solution for 2 hrs. The mixture was then placed into an oven at 100 oC for 24 hrs. They were further calcined at 800 oC for 3 hrs. XRD, FTIR and ICP-MS were used to identify the structure and composition. It was found that the final powders were predominantly monetite, with some tricalcium phosphate as a secondary phase. This relatively simple and efficient method can be easily applied to produce calcium phosphate precursor powders for a range of biomedical applications.
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    Multifunctional-Dual Drug Delivery Poly-Lactic Acid Biocomposite Coating with Hydroxyapatite for Bone Implants
    (Trans Tech Publications Inc, 2018-10) Karacan, Ipek; Chou, Joshua; Macha, Innocent J; Cazalbou, Sophie; Milthorpe, Bruce
    The new novel implant designs include the functionality of advanced drug delivery systems in order to improve osteointegration and to inhibit the implant-related post-operative infections. In this research, Ti6Al4V metallic implants were coated with the multifunctional-dual slow drug delivery coating which includes a polymeric matrix system based on a poly-lactic acid thin film and a bioactive ceramic hydroxyapatite. This system consists of two different kinds of pharmaceuticals, which are gentamicin and simvastatin. It is reported in this paper that the simvastatin and gentamicin containing poly-lactic acid coating which was applied uniformly and successfully with and without hydroxyapatite microspheres. Most importantly, the release rate of drugs was controlled with PLA matrix and HAp microspheres which have different dissolution rates in order to prevent the high dosages causing adverse side-effects of drugs.