Papers by Keyword: Coral

Abstract: Synthesis of porous hydroxyapatite-collagen composites for bone implant applications has been carried out. Hydroxyapatite synthesized from coral by the precipitation method, while Collagen synthesized from chicken claws. Collagen formation was carried out by freeze-dry technique with variations in freezing time of 2, 4 and 6 hours at -80 ° C. The next process was by drying in a lyophilizer. Characterization of samples was carried out using Fourier Transform Infra Red (FTIR), Scanning Electron Microscopy (SEM), compressive strength test and cytotoxicity test with Microtetrazolium (MTT) assay. FTIR results proved that collagen uptake and hydroxyapatite combine chemically. This is indicated by the absorption of functional groups that did not coincide between collagen and hydroxyapatite functional groups with composites. SEM observations showed that the largest pore size was obtained at freezing for 2 hours which was 774 μm and the smallest in freezing for 6 hours was 640 μm. This pore size was an important parameter of the bone implant because it played a role in the osteoinductive process. The composite compressive strength test results for freezing 2 hours, 4 hours and 6 hours respectively was 737 KPa, 842 KPa and 707.7 KPa. The results of the cytotoxicity test with MTT showed the percentage of cell viability above 100%. This means that the Hydroxyapatite-collagen composite is non-toxic. So, the sample formed has qualified as a bone implant candidate.

Abstract: Calcium phosphate materials can be produced using a number of wet methods that are based on hydrothermal or co-precipitation methods that might use acidic or basic chemical environments. In our previously published works, we have investigated calcium phosphates such as monetite, hydroxyapatite, and whitlockite which were successfully produced by mechano-chemical methods and/or hydrothermal treatments from a range of marine shells and corals which were obtained from the Great Barrier Reef. The aim of the current work was to analyze and compare the mechanisms of conversion of one hard coral species and one calcified algae species from the Great Barrier Reef.

Abstract: The development of the calcium phosphate ceramics (CPC) using natural materials such as coral, eggshell, bovine bone, fish bone etc., from Indian origin have been reviewed. The CPCs from natural sources has the benefit that they inherit some of the properties of the raw materials such as the macro-and micro-pore structure, optimal composition, similar morphology etc., as well as the advantage of unlimited world wide availability at a very low raw material cost. Hydroxyapatite (HA), carbonated HA and fluorapatite from natural coral genus "Goniopora” has been obtained. Growth factor loaded coralline HA has been found to significantly accelerate early-stage bone formation in in vivo rabbit model studies. Sea shells have been tested as the source of calcium for electrochemical deposition of HA on titanium implants. Deproteinized hydroxyl carbonate apatite phase was formed by heating adult bovine tibia at 500o C. As eggshell could be easily procured, a great deal of effort has been made to utilize this resource as value-added CPCs including nanocrystalline HA (OHA), calcium deficient HA (CDHA), TCP, tetracalcium phosphate (TTCP) etc., which are the most widely used bone substitutes. Also OHA showed higher antibiotic delivery and more controlled protein release profile compared to the synthetic apatites. Eggshell derived CPCs were also found to have minor amount of Mg, Sr, Si and Na ions inherited from the eggshell. As these ions are crucial for bio-mineralization of eggshell, the influence of multi-ions substituted CPCs as a potential bioceramic for bone regenerative applications has been emphasised.

Abstract: Coral and converted coralline hydroxyapatites have been widely used in biomedical application as orbital implant and bone graft substitute. The aim of this study was to characterize the physical and chemical properties of various corals found in Bidong Island and determines their potential for development of bone graft substitute. Five species of coral which is commonly found in Bidong Island, Terengganu was collected and identified. The physical properties of corals such as density and porosity were determined using the Archimedes Principle, whereas a mechanical strength was determined using a universal testing machine. The structure of corals such as pore sizes and shape, distribution and pore connectivity was observed using Scanning Electron Microscope (SEM). Chemical properties of corals were characterized using X-ray diffraction (XRD), and energy dispersive x-ray (SEM-EDX). Five species of coral were identified as Leptoria, Porites, Platygyra, Acropora and Pocillopora. The densities of corals range from 2.00 to 19.00 g/cm³ while the porosity range from 15 to 60%. The corals structure consists of interconnected open pores with mean pore sizes in range of 100 to 600μm. Their compressive strengths are in the range of 4.92 to 27 MPa, which is higher than the reported strength for cancellous bone. SEM-EDX analysis shows the elements calcium carbonate (C, O and Ca) found in Platygyra. This result was supported by XRD analysis, which shows the calcium carbonate phase in form of aragonite presence in Platygyra. Aragonite phase was suitable for transforming coral to hydroxyapatite via hydrothermal treatment. Based on this finding, coral species in Bidong Island, Terengganu has been great potential to be used as bone graft substitutes.

Abstract: In Nature, calcium carbonate biomineralizations are the most abundant mineralized structures of biological origin. Because many exhibit remarkable characteristics, several attempts have been made to use them as substitution materials for bone reconstruction or as models for generating biomimetic composites that exhibit tailored properties. CaCO₃ biomineralizations contain small amounts of amalgamate of proteins and polysaccharides that are secreted during the calcification process. They contribute to control the morphology of the crystallites and to spatially organize them in well-defined microstructures. These macromolecules, collectively defined as the skeletal matrix, have been the focus of a large number of studies aiming at synthesizing in vitro biomimetic materials, according to a bottom-up approach. However, recent proteomic investigations performed on the organic matrices associated to mollusc shells or to coral skeletons have quashed our hopes to generate, with only few macromolecular ingredients, biomimetic materials with properties approaching to those of natural biominerals. As a mean value, each matrix comprises a minimum of few tens of different proteins that seem to be strictly associated to calcium carbonate biominerals. Among the proteins that are currently detected, one finds RLCDs-containing proteins (Repetitive-Low-Complexity Domains), enzymes, proteins with protease inhibitors domains and at last, proteins that contains typical ECM (ExtraCellular Matrix) domains. Today, we still do not understand how the skeletal matrix works, and unveiling its complex functioning is one of the challenges for the coming decade, both from fundamental and applied viewpoints. Is it realistic to attempt generating abiotically, in a test tube at room temperature, biomimetic composites that mimic natural biomineralizations in their properties If so, and by supposing that we know the individual functions of all the components of the matrix, is there a minimal number of proteins required for producing in vitro calcium carbonate biomaterials that approximate natural biominerals These issues are of importance for the future research directions in biomaterials science.

Abstract: Simvastatin has been shown to succesfully stimulate bone regeneration and attention has being focussed on developing appropriate delivery carriers for its release. The challenge of deliverying therapeutic concentration of pharmaceutical compunds has being the centre of focus in drug delivery developments. This study examines the in-vivo effects of simvastatin released from β-TCP macrospheres derived from coral exoxskeletons. The results indicates that the controlled release of simvastatin can promote bone formation comparable with direct injection. Furthermore the results showed that the release of simvastatin delivery rates can be controlled by additional coating of an apatite coating. Analysis by CT scans, SEM, amount of new bone formed and mechanical strength tests, showed that by controlling the release of simvastatin bone formation can be stimulated to a therapeutic level.

Abstract: Glass decoration elements have been known for centuries. Many of them are preserved in a good shape. Actually the glass production development was started from tiny pieces called glass beads. Some of these products belong to very important historical objects which undergoing conservator activity to preserve our cultural heritage. To realize such enterprise very detailed research should be done. This paper is about testing of different glass decoration elements which belong to historical objects, in order to get information about their history and technology production. This research was carried out on small pieces of glass borrowed from historical objects in partnership between AGH - Technical University of Science and Technology and four different conservator groups. Testing made use of non-destructive techniques, like: EDS, FTIR, AFM.

Abstract: A porous silicon-containing hydroxyapatite has been prepared using natural coral as a calcium source to obtain a biomaterial having an improved biocompatibility. From the XRD analysis, it was confirmed that the single-phase hydroxyapatite containing silicon has formed without revealing the presence of extra phases related to silicon dioxide or other calcium phosphate species. Silicon content is ranged from 0.5wt% to 1wt% by weight. The porous silicon-containing hydroxyapatite blocks were inserted into the 5mm diameter of drill holes made through the lateral femoral condyles of New Zealand white rabbits. The new bony formation did not begin after 1 week. At 3 week, bony ongrowth to the inserted porous silicon-containing hydroxyapatite block could be found, and the new bone surrounded the inserted block entirely after 24weeks. Based on in-vivo test, Si-containing porous hydroxyapatite derived from coral possesses high biodegradability and can be considered a useful material for bone implants.

Abstract: In the present work, natural coral from Brazilian reefs were studied according to their crystallography by X-ray diffraction and microstructure by Scanning Electron Microscopy (SEM/EDX). FTIR spectroscopy was also used to evaluate the chemical functionalities and major components present in the material. The SEM morphology results have shown a tri-dimensional coral structure with porous ranging from 50 to 200 µm. Aragonite was identified as the major crystalline phase through XRD analysis and FTIR spectroscopy. Strontium calcium carbonate, (Sr,Ca)CO3, was also identified by XRD analysis. After sintering at 900º/1h, the conversion from aragonite to CaO and calcite was observed. These results have endorsed the high potential application of natural coral materials as 3D scaffolds for biomedical application, because of calcium carbonate compounds can be converted to HA by hydrothermal and biomimetic coating processes.