title: Nano-sized ceramic particles of hydroxyapatite calcined with an anti-sintering agent.
abstract: Nano-sized crystals of calcined hydroxyapatite (HAp) having spherical morphologies were fabricated by calcination at 800 degrees C for 1 h with an anti-sintering agent surrounding the original HAp particles and the agent was subsequently removed by washing after calcination. The original HAp particles were prepared by a modified emulsion system, and surrounded with poly(acrylic acid, calcium salt) (PAA-Ca) by utilizing a precipitation reaction between calcium hydroxide and poly(acrylic acid) adsorbed on the HAp particle surfaces in an aqueous medium. In the case of calcination without PAA-Ca, micron-sized particles consisting of sintered polycrystals were mainly observed by scanning electron microscopy, indicating the calcination-induced sintering among the crystals. On the other hand, most of the crystals calcined with the anti-sintering agent were observed as isolated particles, and the mean size of the HAp crystals was around 80 nm. This result indicates that PAA-Ca and its thermally decomposed product, CaO, surrounding the HAp crystals could protect them against calcination-induced sintering during calcination at 800 degrees C. The HAp crystals calcined with PAA-Ca showed high crystallinity, and no other calcium phosphate phases could be detected.
authors: Department of Bioengineering, Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan.
authors: Masahiro
authors: M
authors: Okada
authors: Tsutomu
authors: T
authors: Furuzono
mesh_terms: D000180:Acrylic Resins; D002516:Ceramics / Q000737:chemistry; D017886:Durapatite / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D036103:Nanotechnology; D010316:Particle Size
chemical_list: D000180:Acrylic Resins; C006903:carbopol 940; D017886:Durapatite