Systematic investigations on the production of Calcium Phosphate based inorganic nanoparticles

Abstract

Calcium phosphate ceramic is good candidate for bone substitutes due to their chemical and structural similarity to bone structural. High purity calcium phosphate powders have been synthesized through sol-gel technique using calcium nitrate tetrahydrate and phosphoric pentoxide as the precursors for calcium and phosphorus, respectively. The sol-gel prepared calcium phosphate nanoparticle was characterized for its phase purity, chemical homogeneity and bioactivity. Fourier transform infrared (FTIR) spectroscopy was used to identify the functional groups of calcium phosphate which is phosphate ( 960 to 965 cm-1), hydroxyl (.1800 cm-1, 632 cm-1 and 474 cm-1) and carbonyl (1550 cm-1, 1457 cm-1 and 880 cm-1 ) X-ray diffraction (XRD) analysis was carried out to study the phase composition, crystallinity and the crystallite size of calcium phosphate nanoparticles that were experimented at different physical conditions. FTIR result combined with the X-ray diffraction exhibited single phase of calcium phosphate with carbonate peaks in the FTIR spectrum. Photomicrograph or scanning electron microscopy (SEM) showed that the obtained powder after applying different physical condition of parameters (temperature, stirring speed and aging time) is composed of calcium phosphate nanoparticles (38-50 nm). The dissolution rate of calcium phosphate nanoparticles was higher than conventional calcium phosphate nanoparticles and closer to biological apatite due to its nanostructure dimensions. It was concluded that sol-gel prepared calcium phosphate nanoparticles had superior bioresorption and similar chemical and crystal structural to natural bone apatite. The optimization of calcium phosphate nanoparticles by using the Central Composite Design (CCD) software is a well known and widely used statistical technique for optimization. This method requires a systematic number of experiments to be carried out and include interactive effects among the variables. Effect of temperature (600-800 oC), stirring speed (100-600 rpm) and aging time (2- 6 hour) on the production of calcium phosphate based on inorganic nanoparticles. Calcium phosphate with the crystallite size of 44.314 nm was produced at 800 oC, 350 rpm and 4 hr as the optimum conditions in the biomedical range (30-50 nm). Under these conditions, the experimental percentage error was 0.12 %, 0.14 % and 0.17 %, showing a close agreement with value predicted by the model.