Papers by Keyword: Bioactive

Abstract: One of factor causing the failure of Ti-6Al-4V Extra Low Interstitial (ELI)-based material implants, does not have bioactive properties in the implantation process, thus not supporting the osseointegration process in the body. For this reason, coating with hydroxyapatite (HA) suspension is necessary. This research used the dip-coating method and added Zirconium Oxide (ZrO₂) into nanosized commercial HA to be suspensions (17%wt and 20%wt) to strengthen the adhesion of the coating. The specimens were heated at 800, 900, and 950°C to densify the layers. Bioactivity increased along with the increasing calcium/phosphate (Ca/P) ratio of the HA layers in the test specimens. The specimens were immersed in Simulated Body Fluid (SBF), namely Hank’s Solution, for 1, 2, 3, and 4 weeks. ZrO₂ added to the HA suspensions of Ti-6Al-4V ELI can increase the Ca/P ratio from 1.51 in the first immersion week to 1.62 in the fourth. The bioactivity level is also proven by the accumulation of calcium and phosphate on the surface of the coating. The Ca/P value close to the Ca/P ratio of HA of 1.67 is good for improving the osseointegration process in the body.

Abstract: In this work, the thermal treatment temperature effect on phase formation and bioactivity of glass-ceramics based on the SiO₂-Na₂O-CaO-P₂O₅ system has been studied. The chemical composition of the system is 45 wt.% SiO₂, 24.5 wt.% Na₂O, 24.5 wt.% CaO and 6 wt.% P₂O₅ (45S5). The rice husk ash is used as the natural raw materials instead of commercial SiO_2. All of the investigated compositions were prepared by melting the glass mixtures at 1350°C for 3 h. The resulting glass samples were heated at different thermal treatment temperatures ranging from 750 to 1050°C with fixed dwell-time for 4 h for crystallization. Phase identification of the 45S5 glass ceramics was carried out by X-Ray diffraction (XRD). Moreover, the physical properties such as density, porosity and mechanical properties were systematically investigated. It was found that, the increasing of heat treatment temperature led to the increasing of the Na₂Ca₂Si₃O₉ phase and obtaining better bioactive behavior after incubation of glass-ceramics in simulated body fluid (SBF) for 7 days. The maximum hardness value of 4.02 GPa was achieved after heating at 1050°C for 4 h. However, the density value has slightly changed with various heat treatment temperatures.

Abstract: The healing mechanism of osteoconductive biphasic calcium phosphate granules was investigated by a histological assessment of early-stage bone deposition and remodeling. The deposition of de novo bone on the scaffold granules was observed to initiate at the defect periphery by week one and in the bulk of the defect incorporating the granules by week four. New bone tissue was deposited in the space provided by the macroporosity and was observed in direct apposition to the implanted material confirming the bioactivity of the biphasic calcium phosphate. The granules were removed through a cell-mediated resorption process that was observed to begin as early as week two following surgery. Mature lamellar bone, fatty bone marrow, and vascularization was observed throughout the bulk of the defect with the cortical shell healed by week twelve. This healing mechanism was found to balance bone formation and implant resorption resulting in complete healing of the corticocancellous defect in the rabbit femoral condyle.

Abstract: In this paper, grapes were processed by using high frequency electromagnetic field in order to obtain a high quality wine in terms of bioactive compounds content with antioxidant activity. The experimental setup comprise an applicator with adjustable power between 100-1000 W, software assisted, in order to process three varieties of grapes (Muscat Ottonel, Merlot, Pinot Noir), that were harvested in 2014 in the Crişana-Sântimreu vineyard. The total polyphenol compounds were measured using the Folin-Ciocalteu spectrophotometric method, and the antioxidant capacity was determined by the FRAP method. The results have shown that the use of high frequency electromagnetic field in grape processing leads to the diffusion of the bioactive compounds with antioxidant activity in the final product. In the same time, it is also an effective method in terms of energy consumption.

Abstract: Freeze-dried β-wollastonite (β-CaSiO₃) powders were synthesized via sol-gel, combined with autoclaved, sintered and finally freeze-dried at -50 °C for 12 h using rice straw ash and calcined limestone as the starting materials. To prepare β-CaSiO₃, the precursor ratio of SiO₂:CaO was set at 45:55. Pure β-CaSiO₃ was obtained after sintering at 950 °C for 3 h. The bioactivity of freeze-dried β-CaSiO₃ was investigated by soaking the cylinderical shape samples in simulated body fluid (SBF) up to 21 days. The surface compositional, morphological and structural changes of the samples before and after soaking were analyzed via X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) coupled with EDS. Sintered freeze-dried β-CaSiO₃ has a porous structure and changed to cauliflower-like after soaking in simulated body fluid solution. After 21 days of soaking process, an amorphous calcium phosphate (ACP) and calcium deficient hydroxyapatite (CDHA) were formed with the molar ratio of Ca/P between 1.76 to 1.63.

Abstract: In this work, Ag-AgCl-TiO₂ coating was fabricated on titanium substrates to obtain an implant material having excellent antibacterial property and bioactivity. The coating was investigated by scanning electron microscopy and X-ray diffraction. The bioactivity of coatings was examined by simulated body fluid soaking test. To verify the susceptibility of implant material surface to bacterial adhesion, S. aureus (Sau), E. coli (Eco), K. pneumoniae (Kpn), P. Aeruginosa (Pae), four types of major pathogen were chosen for in vitro antibacterial analyses. The results showed that Ag-AgCl-TiO₂ coating had excellent antibacterial property and bioactivity.

Abstract: This study evaluates the effect of two novel particulate silicon-doped calcium phosphate graft materials as compared to the currently clinically used material β-TCP on osteogenesis and bone formation after implantation in critical-size defects the sheep scapula. These materials were developed in order to create biodegradable bone substitute materials that degrade rapidly, but still stimulate osteogenesis at the same time, thereby resulting in bone repair and regeneration with fully functional bone tissue. All bone substitute materials studied facilitated excellent bony regeneration of critical-size defects in the sheep scapula. Of the three grafting materials studied, the calcium alkali orthophosphate material with the crystalline phase Ca₂KNa (PO₄)₂, with a small amorphous portion containing magnesium potassium phosphate and a small addition of sodium magnesium silicate had the greatest stimulatory effect on bone formation and expression of osteogenic markers, while exhibiting the highest biodegradability.

Abstract: The present study concerns the production and characterization of porous hydroxyapatite/niobo-phosphate glass ceramics to be used for bone repair. The scaffolds were produced by hydrothermal deposition of monetite on polyurethane sponge substrates, further converted to hydroxyapatite in an alkali solution. After heat treatment, elimination of the organic sponge provides a three-dimensional (3D) structure. Niobo-phosphate glasses were added to the heat treated struts and the scaffolds were sintered. The porous bodies were characterized by field-emission gun scanning electron microscope (FEG-SEM) with energy-dispersive X-ray spectroscopy (EDS).

Abstract: Silica-based porous bioactive ceramics was prepared by gel-casting method using silica xerogel powder. Xerogel was derived from rice husk ash. 42 vol.% solid containing slurry was prepared in 1:30 (MBAM:AM) monomer cross-linker solution. The srurry was thixotropic. Gel-casted body was machined efficiently. Dired cast body was sintered at 1100oC. Apatite layer was formed on silica body during In vitro bioactivity experiment. The results suggest that the gel-casted silica ceramics can be used as a bioceramics.