title: A novel strategy for preparing nanoporous biphasic calcium phosphate of controlled composition via a modified nanoparticle-assembly method.
abstract: Biphasic calcium phosphate (BCP) consisting of hydroxyapatite (HAp) and β-tricalcium phosphate is usually prepared by thermal decomposition of calcium-deficient HAp (CDHAp). However, the calcium deficiency and morphology of CDHAp are difficult to manipulate in parallel. In this study, we report a novel strategy for controlling the composition of nanoporous BCP by using only CDHAp nanoparticles with specific properties (Ca/P molar ratio, 1.61; particle size, 50 nm) as a building block and by adjusting the calcium deficiency of the nanoparticle-assembled CDHAp (Ca/P molar ratio, 1.50-1.67; pore size, 8 nm) with the addition of water-soluble Ca(NO3)2 or (NH4)2HPO4. After thermal treatment at 1000 °C, the composition of BCP could be predictably controlled by adjusting the Ca/P ratio of the nanoparticle-assembled CDHAp. Changes in the Ca/P ratio did not significantly affect the surface morphology of BCP, but the grain size (210-300 nm) and pore size (140-170 nm) tended to increase slightly as the Ca/P ratio decreased. The porosity significantly decreased upon the addition of Ca salts (porosity, 20%) or PO4 salts (porosity, 14%) compared with that of the sample without additives (porosity, 53%). In vitro tests demonstrated enhanced cell adhesion on nanoporous BCP compared with densely sintered pure HAp, and cell differentiation was promoted on the nanoporous pure HAp.
authors.affiliation: Graduate School of Dentistry, Department of Orthodontics, Osaka Dental University, 8-1 Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan. Electronic address: keiko-k@cc.osaka-dent.ac.jp.
authors.forename: Keiko
authors.initials: K
authors.lastname: Fujiwara
authors.affiliation: Department of Biomaterials, Osaka Dental University, 8-1 Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan. Electronic address: okada-m@cc.osaka-dent.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okada
authors.affiliation: Department of Biomaterials, Osaka Dental University, 8-1 Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
authors.forename: Shoji
authors.initials: S
authors.lastname: Takeda
authors.affiliation: Graduate School of Dentistry, Department of Orthodontics, Osaka Dental University, 8-1 Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Matsumoto
mesh_terms: D016475:3T3 Cells; D000818:Animals; D018786:Bone Substitutes / Q000138:chemical synthesis*; D002130:Calcium Phosphates / Q000138:chemical synthesis*; D002448:Cell Adhesion / Q000502:physiology*; D003460:Crystallization / Q000379:methods*; D006244:Hardness; D006358:Hot Temperature; D008422:Materials Testing; D051379:Mice; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D058608:Nanopores / Q000648:ultrastructure*; D010316:Particle Size; D016062:Porosity; D013499:Surface Properties
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; C485829:calcium phosphate, dibasic, anhydrous
keywords: Assembly; Calcium phosphate; Nanoparticle; Nanopore; Osteoblast