Browsing by Author "Grossin, David"

Now showing 1 - 8 of 8
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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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    Biocompatibility of a new biodegradable polymer-hydroxyapatite composite for biomedical applications
    (Elservier, 2017-04) Macha, Innocent J; Ben-Nissan, Besim; Santos, Jerran; Cazalbou, Sophie; Stamboulis, Artemis; Grossin, David; Giordano, Gerard
    The rise in the number of musculoskeletal disorders (MSDs) due to an increasingly aging population has led to a growing demand for medication to prevent and treat these diseases. An increased interest in the development of new drugs to allow treatment of these diseases in their very early stages is currently observed. The current approach on local direct delivery of medication and key minerals to support bone repair and regeneration at the defect site, from flexible degradable devices, seems to be an effective strategy. Polylactic acid (PLA) and microspheres of hydrothermally converted coralline hydroxyapatite (cHAp) were used to develop PLA thin film composites as drug delivery systems. The PLA provided flexibility and biodegradability of the systems, while coralline hydroxyapatite provided the required calcium and phosphate ions for bone regeneration. These coralline hydroxyapatite microspheres have a unique architecture of interconnected porosity, are bioactive in nature and suitable for drug loading and controlled slow drug release. The cell attachment and morphology of the PLA thin film composites were evaluated in vitro using cell cultures of human adipose derived stem cells (hADSC). It was shown that hADSC cells exhibited a strong attachment and proliferation on PLA thin film-cHAp composites, signifying high biocompatibility and a potential for osteointegration due to the presence of HAp.
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    Comparative Study of Conversion of Coral with Ammonium Dihydrogen Phosphate and Orthophosphoric Acid to Produce Calcium Phosphates
    (Springer NATURE, 2014-01) Cegla, Rabea-Naemi Rosa; Macha, Innocent J; Ben-Nissan, Besim; Grossin, David; Heness, Greg; Ren-Jei, Chung
    Biogenic materials like corals, which are readily available, could be used to produce bioceramic materials and address significant advantages due to their unique structures and chemical compositions that contain Mg and Sr. Many conversion processes has been in the past proposed. In this work, a comparison study between the conversion of coral with orthophosphoric acid and ammonium dihydrogen phosphate was conducted. The resultant structures and compositions were studied using XRD, ICP-MS, SEM and FTIR. The results show that with phosphoric acid the coral was converted into mainly monetite (92%). The ammonium dihydrogen phosphate converted approximately 76% of the coral to hydroxyapatite through solid state reactions. The two routes proved to be effective in producing bioceramic materials from corals under moderate conditions of temperature with a basic condition favouring the yield of hydroxyapatite.
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    Comparative Study of Conversion of Coral with Ammonium Dihydrogen Phosphate and Orthophosphoric Acid to Produce Calcium Phosphates
    (Springer NATURE, 2014) Cegla, Rabea-Naemi Rosa; Macha, Innocent J; Ben-Nissan, Besim; Grossin, David; Heness, Greg; Chung, Ren-Jei
    Biogenic materials like corals, which are readily available, could be used to produce bioceramic materials and address significant advantages due to their unique structures and chemical compositions that contain Mg and Sr. Many conversion processes has been in the past proposed. In this work, a comparison study between the conversion of coral with orthophosphoric acid and ammonium dihydrogen phosphate was conducted. The resultant structures and compositions were studied using XRD, ICP-MS, SEM and FTIR. The results show that with phosphoric acid the coral was converted into mainly monetite (92%). The ammonium dihydrogen phosphate converted approximately 76% of the coral to hydroxyapatite through solid state reactions. The two routes proved to be effective in producing bioceramic materials from corals under moderate conditions of temperature with a basic condition favouring the yield of hydroxyapatite.
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    Comparative study of Coral Conversion, Part 2: Microstructural evolution of calcium phosphate
    (Springer NATURE, 2015-06) Macha, Innocent J; Boonyang, Upsorn; Cazalbou, Sophie; Ben-Nissan, Besim; Charvillat, Cédric; Oktar, Faik N; Grossin, David
    Calcium phosphate materials can be easily produced by a number of wet chemical methods that involve both acidic and basic environments. In our previous study, we investigated calcium phosphates such as monetite (DCPA), hydroxyapatite (HAp) and whitlockite which were successfully produced by mechano-chemical method from corals obtained from the Great Barrier Reef. It was observed that a number of synthesis factors such as the pH of the environment, the reaction temperature and the chemistry influenced the crystal size formed. A number of theories have been suggested on the mechanisms of crystal formation; however, very few mechanisms have been universally accepted. The present work was aimed to explore the evolution of crystalline calcium phosphate and their morphology with respect to the pH of the environment and reaction time. Conversion of coral to calcium phosphates was carried out with stoichiometric amount of required H3PO4 or (NH4)2HPO4, to obtain hydroxyapatite or tricalcium phosphate (TCP) phases. The acidic or basic solution was added, drop wise, at a rate of 2 mL min-1, to 6 g of coral powder suspended in 300 mL of distilled water at 80 ± 0.5°C on a hot plate with magnetic stirrer. The pH of reaction was monitored. Crystal morphology and the phases were identified by XRD, FTIR, and SEM studies. It was observed that under acidic conditions (H3PO4), dissolution and then precipitation influences the crystal morphology and transition from plate like to rod like hydroxyapatite structure. During the first hour of the dissolution a monetite and hydroxyapatite mixture precipitates and then the full conversion to hydroxyapatite is observed. However under basic conditions (NH4)2HPO4), pH is only marginally changed within the environment and just surface conversion of the calcium carbonate structure of coral to hydroxyapatite and a very small amount of tri-calcium phosphate is observed. The mechanism can be classified as the solid state topotactic ion-exchange reaction mechanism.
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    Comparative Study of Coral Conversion, Part 3: Intermediate Products in the First Half an Hour
    (2015-12) Macha, Innocent J; Charvillat, Cédric; Cazalbou, Sophie; Grossin, David; Boonyang, Upsorn; Ben-Nissan, Besim
    Understanding what really happen during reaction will pave a way to tune the final product for well-defined morphology and purity. We focused into improving in-depth understanding of the reaction mechanisms and the intermediates products participating in the reaction of coralline materials with orthophosphoric and ammonium phosphate solutions under mechano-chemical reaction technique. The results suggest that within 30 minutes of reaction under ammonium phosphate solution only HAp phase is produced through solid-state iron exchange reaction. On the other hand, under orthophosphoric acid solution, intermediate phases such as octacalcium phosphate (OCP) and monetite form and convert to hydroxyapatite HAp at different times. Other phase that formed as an intermediate was identified as brushite. It was also observed that pH plays a big role in the formation of these phases due to their different pH stability. The results also confirm our previous hypothesis that under orthophosphoric acid phosphate solution the reaction mechanism is dissolution-recrystallization while under ammonium phosphate solution is solid-state topotactic ion exchange reaction mechanism. It is envisaged that there are possibilities of the formation of intermediate products within or before the fir
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    Conversion of Marine Structures to Calcium Phosphate Materials: Mechanisms of Conversion using two Different Phosphate Solutions
    (2016-03) Macha, Innocent J; Grossin, David; Ben-Nissan, Besim
    Marine structure, coralline materials were converted to calcium phosphate using two different phosphate solutions. The aim was to study the conversion mechanisms under acidic and basic environment at moderate conditions of temperature. Crystal growth and morphology of converted corals were characterized by XRD and SEM respectively. The results suggested that under acidic conditions (H3PO4), dissolution and precipitation control and direct the crystal formation and morphology in which transition from plate like to rod like hydroxyapatite structure was favoured. Metastable phase such as monetite formed and transformed to HAp during reaction. During the first hour of the dissolution a monetite and hydroxyapatite mixture precipitates and then the full conversion to hydroxyapatite is observed. On the other hand, under basic conditions (NH4)2HPO4, just diffusional surface conversion of the calcium carbonate structure of coralline materials to hydroxyapatite and a very small amount of tri-calcium phosphate is observed. The mechanism can be classified as the solid-state topotactic ion-exchange reaction mechanism.
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    In vitro bioactivity and stem cells attachment of three-dimensionally ordered macroporous bioactive glass incorporating iron oxides
    (Elservier, 2016-11) Charoensuk, Thanida; Sirisathitkul, Chitnarong; Boonyang, Upsorn; Macha, Innocent J; Santos, Jerran; Grossin, David; Ben-Nissan, Besim
    Three-dimensionally ordered macroporous bioactive SiO2-CaO-Na2O-P2O5 glass (3DOM-BG) is synthesized by using the sol-gel method. After an in vitro test in simulated body fluid (SBF), the hydroxyapatite (HAp) crystalline phase is clearly formed on its surface as confirmed by X-ray diffractometry (XRD) and Raman spectroscopy. Magnetic 3DOM-BG/Fe samples are synthesized by partial substitution of SiO2 with iron oxide. Whilst the HAp layer is not confirmed, energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and XRD analysis reveal calcium phosphate layer on the surface of 3DOM-BG/Fe samples after the SBF soaking. The growth of HAp-like layer is slower with increasing iron oxides. The initial mechanism that thought to induce bone formation is reduced due to the replacement of Ca2 + with Fe ions in the glass network. The formation of HAp-like layer is modified by the sedimentation of Ca and P while the nonmagnetic 3DOM-BG forms the calcium phosphate by the ionic exchange following the Hench mechanism. The adult human adipose tissue-derived stem cells (hADSCs) can be closely attached and well spread on the flat-plate of all 3DOM-BG/Fe and 3DOM-BG. Without detectable cytotoxicity possibly induced by iron oxides, the osteoblast can be grown and proliferated. In addition to these bioactivity and biocompatibility, porous structures can allow their possible use in targeted drug delivery and magnetic properties of 3DOM-BG/Fe can essentially be implemented in hyperthermia therapy.