Abstract: Hydroxyapatite is a bioceramic material of great interest for use as bone substitute because of its similarity with the composition of biological apatite. Cationic and anionic substitutions in the apatite structure have been made in order to optimize the synthesis and accelerate the process of bone repair. In the present study, niobate apatite was synthesized by a patented aqueous precipitation method. The bioactivity of the samples was assessed by X-ray diffraction analyses (XRD), energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy with field emission gun (FEG-SEM; FEI Quanta FEG 250) in the samples before and after an incubation period in simulated body fluid. The results showed that after 3 days a bone-like apatite coating was formed onto the niobate apatite surface. A peculiar morphology comprised by nanosized wires was also observed on the niobate apatite surface.
Abstract: The low crystalline hydroxyl carbonate apatite forming capacity of a poly (70lactic-co-30glycolic acid)/15CaO-85SiO2 composite, which had a dual pore structure, was newly examined in simulated body fluid. The bioactive 15CaO-85SiO2 particles were synthesized by a sol-gel method using tetraethyl orthosilicate (TEOS) and calcium nitrate tetrahydrate under acidic condition followed by the heat treatment at 600°C for 3h. The poly (70lactic-co-30glycolic acid)/15CaO-85SiO2 composite was then prepared by a solvent casting using dimethylformide as a solvent. The composite was loaded into a high pressure chamber and then carbon dioxide gas was introduced achieving a final pressure of 20 MPa. After 3 days, carbon dioxide gas was released quickly and resultantly the dual pore structure was obtained. The samples were observed by FE-SEM and its bioactivity was tested in simulated body fluid.
Abstract: The aim of this study was to investigate the influence of biogenic and synthetic starting materials on properties of porous hydroxyapatite (HAp) bioceramics. HAp powders were synthesized by modified precipitation method using biogenic calcium carbonates (ostrich (Struthio camelus) egg shells, hen (Gallus gallus domesticus) egg shells, snail (Viviparus contectus) shells) and synthetic calcium oxides (Sigma-Aldrich and Fluka). Specific surface area, molecular structure and morphology of obtained powders were determined. As-synthesized HAp powders had a varied specific surface area with a wide range from 83 to 150 m2g-1 depending on CaO source. Porous bodies of HAp were prepared by in situ viscous mass foaming with NH4HCO3 as pore forming agent. Foamed and dried green bodies were sintered at 1100 °C. The obtained bioceramics were investigated using Archimedes method, field emission scanning electron microscopy and Brunauer-Emmett-Teller method. There are considerable differences between porous HAp bioceramics structures prepared from different sources of CaO. The choice of starting material substantially affects the macro-and microstructure of prepared porous bioceramics.
Abstract: Introduction: Many polymer supports for cell seeding formulations based on chitosan are usually prepared by chemical cross-linking with glutaraldehyde, urea formaldehyde, epichlorohydrine, even if the chemical cross-linking agents possibly induce toxicity and other undesirable effects.
Experimental: Derivatized poly (vinyl alcohol) was blended and foamed with chitosan to produce porous scaffolds with improved elastic and mechanical properties and also acceptable water solubility. Derivatized PVA (in example phosphorylated PVA) (P-PVA) also exhibited improved hydrophilicity, anionic properties and molecular electrostatic repulsion, and retained the bulk morphological features, compatible property, and solution stability.
Results: Porous scaffolds formed by derivatized PVA crosslinked with chitosan proved a good cytocompatibility for human fibroblasts. Viability and apoptosis assays were performed indicating that this porous scaffold allow cell multiplication and scarce apoptotic induction.
Conclusion: Tested porous scaffolds may represent an interesting support for three dimensional cell cultures destined to simulate tumor or normal tissue microenvironment.
Abstract: Casein is a phosphoprotein and accordingly, its capacity to induce formation of apatite was investigated using a biomimetic method. The protein was physically immobilized into a synthetic polymer network generating hybrid scaffolds. The obtained hydrogels contained uniformly distributed nanosized casein grains. The incubation of such materials in synthetic body fluid (SBF 1.25x) led to formation of nanosized biologic-like apatite. The resulting materials have been characterized by infrared spectrometry and scanning electron microscopy.
Abstract: Apatite containing-polymer beads have been prepared using two methods. The first series of scaffolds is obtained using an effortless procedure consisting in mixing the mineral phase in the polymer precursors, followed by crosslinking. The resulting materials contained agglomerates of inorganic particles. The second series of materials is generated through a more complex synthesis involving the alternate Ca2+/PO43- soaking of the polymer beads. This leads to formation of nanometric apatite phase homogeneously distributed within and on the surface of the polymer substrates. The resulting materials have been characterized by infrared spectrometry, X-ray diffraction and scanning electron microscopy.
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 objective of this work is to understand the influence of time on thermal oxidation of CP-Ti Grade II at 850 oC. Thermal treatments were performed for 5 minutes, 15 minutes, 30 minutes, 60 minutes and 120 minutes of isothermal stage. The response of titanium to oxidation at same temperatures and various timings has been investigated, in terms of layer thickness, phase evolution. A variety of experimental and analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM) and ball cratering test have been used to characterize the result of thermal oxidized surfaces. The results showed that oxygen diffused on Ti structure can produce a thick oxide layer with rutile (TiO2) between 3,50 and 10,34 microns, which exhibited good adhesion with the substrate.
Abstract: nanobioactive glasses are biocompatible and osteoconductive materials which can be mixed with solution of biocompatible polymers to make nanobiocomposite paste for hard and even soft tissue treatment. In this study, bioactive glass based on CaO-SiO2-P2O5 system was produced via sol-gel technique and mixed with a solution phase. The solution phase was a 1:1 mixture of 3% hyaluronic acid solution and 3% sodium alginate solution in v/v. Rheological behaviors of the paste in rotation and oscillation modes were measured. For surface reactivity measurements, the paste was immersed in simulated body fluid (SBF) for different intervals and then characterized by SEM. The paste exhibited a superior injectability even from syringes with too narrow tips. It was a thixotropic fluid with shear thinning behavior. The results of surface reactivity revealed precipitation of apatite phase on the paste surfaces meanwhile an appropriate structural stability was observed against disintegration (anti-washout behavior). It seems that this biocomposite paste is an appropriate alternative for injectable bone substitute materials.