Nano-beta-tricalcium phosphates synthesis and biodegradation: 1. Effect of microwave and SO ₄ ²⁻ ions on β-TCP synthesis and its characterization

Abstract

Nano-sized calcium deficient hydroxyapatite (CDHA) powders with an average particle size less than 100 nm were prepared by a co-precipitation method at low temperature. The initial Ca/P molar ratio was chosen to be less than the stoichiometric ratio of beta-TCP (1.5). Additionally, lowering the temperature and pH values accelerated HPO(4)(2-) incorporation in the CDHA structure. HPO(4)(2-) is considered as an essential source for beta-TCP formation. Sulfate ion doping during the maturation period is proved to be an effective step to eliminate the pyrophosphate P(2)O(7)(2-) phase that results during the calcination of CDHA with Ca/P < 1.5. Furthermore, the heating effect of microwave irradiation resulted in an increase in Ca ion concentration and lowered the CDHA deficiency which affected beta-TCP purity despite its ability to reduce the particle size. A purity of 99.32% beta-TCP with respect to the P(2)O(7)(2-) phase was achieved by increasing the sulfate ion concentration from 2% to 3% and the calcination temperatures from 900 degrees C to 1100 degrees C.

Nanodimensional and Nanocrystalline Calcium Orthophosphates

“…The same technique was used to synthesize nano-sized particles of amorphous TCP of 25 -60 nm size [520][521][522][523], those after calcinations transformed into α-TCP or β-TCP. Nanodimensional β-TCP powders with an average grain size of ~ 100 nm [173,524] and less [525] were prepared by wet precipitation methods, followed by calcining at elevated temperatures. Furthermore, a sol-gel technique [526], reverse micelle-mediated synthesis [527] and a polystyrene template method [528] are also applicable.…”

Nanodimensional and Nanocrystalline Apatites and Other Calcium Orthophosphates in Biomedical Engineering, Biology and Medicine

“…The same technique might be used to synthesize amorphous nanoparticles of unidentified TCP of 25–60 nm size [419,420,421,422], those after calcinations transformed into α-TCP or β-TCP. Nanodimensional β-TCP powders with an average grain size of ~100 nm [161,423] and less [424] were prepared by wet precipitation methods, followed by calcining at elevated temperatures. Both a sol-gel technique [425] and reverse micelle-mediated synthesis [426] are also applicable.…”

Production and characterization of natural rubber–Ca/P blends for biomedical purposes

“…The physical disintegration into smaller particles can also occur due to biological interactions. In this process, Ca 2+ ions may be released into the environment and the proportion of calcium and phosphorous altered [11,32]. Fig.…”