Physicochemical Characteristics of Magnesium Hydroxyapatite (MgHA) Derived via Wet Precipitation Method / C. M. Mardziah ... [et al.]

Hydroxyapatite (HA) has been known for so many decades as an implant material for medical applications due to its chemical composition that is very similar to the inorganic component of human bone. However, synthetic HA possesses relatively low mechanical strength characteristic, making it less suitable to be used in load bearing applications. Thus, the presence of metal ion like magnesium (Mg) is expected to improve the properties of synthetic HA as biomedical devices. The main objective of this research is to develop and characterize the magnesium hydroxyapatite (MgHA) nanopowders derived from the wet precipitation method. The amount of Mg, which acts as a metallic dopant in HA were varied at 0, 5 and 10% and calcined at 700C for imperative comparison. The resultant nanopowders were then characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) to examine their physicochemical properties. Morphological evaluation by FESEM showed that the particle size of 10% MgHA powders was larger and spherical in shape but still highly agglomerated at calcination temperature of 700C. This result coincides with the data obtained from the XRD analysis, which revealed that the particle size of pure HA, 5 and 10% MgHA after calcination was 87 nm, 98 nm and 116 nm, respectively. These results demonstrate that doping Mg into HA has caused an increase in the particle size, proving that Mg acts as a sintering additive during the calcination process

Strontium-doped hydroxyapatite nanopowder via sol-gel method : effect of strontium concentration and calcination temperature on phase behavior

Strontium doped hydroxyapatite (Sr-doped HA) nanopowder has been synthesized using a sol-gel method. The concentration of strontium was varied at 2, 5, 10 and 15 mol%. The as synthesized powders were calcined at temperatures of 500 -900ºC. The calcined white Sr-doped HA powders were characterized using differential and thermogravimetric analysis (TG/DTA), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Morphological evaluation by FESEM measurement shows that the particles of the Sr-doped HA agglomerates are globular in shape with an average size of 1-2 mm in diameter while the primary particles have a diameter of 30-150 nm in average. The calcined powders contained hydroxyapatite phase only for all doping concentration except for the smallest doping concentration, 2 mol%, where â-TCP appeared as the secondary phase. This indicates that the substitution of Sr atoms for Ca atoms have stabilized the HA phase, leading to the inhibition of the appearance of â-TCP phase upon high temperature calcination. Even, for 2 mol% Sr-doped HA, the appearance of â-TCP peak only started to appear at a temperature as high as of 900ˆC, compared to non- Sr doping HA which appeared at a temperature below 800ºC. © Society for Biomaterials and Artificial Organs (India), 20090119-3

Conversion of strontium hydroxyapatite nanopowders to porous scaffolds for bone implant application

The fabrication of strontium hydroxyapatite (SrHA) porous scaffolds was accomplished by using polymeric sponge method. To prepare the porous samples, the synthesized SrHA nanopowders were mixed with distilled water and appropriate amount of dispersing agent followed by drying in the ambient air and sintering at 1300°C. The compressive strength of the materials was strongly influenced by the porosity, while there was almost no dependence on the crystallinity of the powders since XRD patterns showed high crystallinity of HA phase for all porous samples. Morphological evaluation by FESEM revealed that the SrHA scaffolds were characterized by macro-micro interconnected porosity, which replicates the morphology of the cancellous bone. Compression test on the porous scaffolds demonstrated that doping 10 mol% of strontium in HA has increased the compressive strength by a factor of two compared to the undoped HA with 1.81±0.26 MPa at 41% porosity