title: Biodegradation and bioabsorption innovation of the functionally graded bovine bone-originated apatite with blood permeability.
abstract: Bioabsorbable and functionally graded apatite (fg-HAp) ceramics were designed using bovine bone by the calcination and partial dissolution-precipitation methods. The fg-HAp ceramics that were developed had gradual distributions of the degree of crystallinity and the grain size of single-phase hydroxyapatite from the surface layer of the pore wall to the bulk structure region. Calcination at 1073 K gave a specific surface area of 30 m2 x g-1 and porosities of 60-80%. The pore structure of the fg-HAp was classified into two regions: a macro-pore region (100-600 microm) originating from spongy bone and a micro-pore region (10-160 nm) related to body fluid permeation and blood permeability. By implantation in subcutaneous tissue of rat, it was confirmed that body fluid permeated the bulk region of the fg-HAp ceramics through the micro-pores. The volumetric populations occupied by body fluid were 60% at 4 weeks and 68% at 8 weeks in the ceramics explants, indicating drastic bioabsorption, although the body fluid was found to be immunopositive for an albumin as the main serum protein in blood. On the fg-HAp ceramics developed here, the bioabsorption rate could be controlled by careful selection of the calcination temperature. These ceramics can be applied as new biomimetic ceramics exhibiting surface and bulk degradations and cellular absorption by giant cells.
authors.affiliation: Hokkaido Industrial Research Institute, Nishi-11, Kita-19, Kita-ku, Sapporo 060-0819, Japan. akazawa@hokkaido-iri.go.jp
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Akazawa
authors.forename: Masaru
authors.initials: M
authors.lastname: Murata
authors.forename: Tomoya
authors.initials: T
authors.lastname: Sasaki
authors.forename: Junichi
authors.initials: J
authors.lastname: Tazaki
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Tohru
authors.initials: T
authors.lastname: Kanno
authors.forename: Katsuo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Makoto
authors.initials: M
authors.lastname: Arisue
mesh_terms: D000327:Adsorption; D000818:Animals; D001672:Biocompatible Materials / Q000302:isolation & purification* / Q000493:pharmacokinetics; D001673:Biodegradation, Environmental; D001842:Bone and Bones / Q000737:chemistry*; D002417:Cattle; D002516:Ceramics / Q000302:isolation & purification / Q000493:pharmacokinetics; D011232:Chemical Precipitation; D003460:Crystallization; D006882:Hydroxyapatites / Q000097:blood / Q000302:isolation & purification* / Q000493:pharmacokinetics; D066298:In Vitro Techniques; D008297:Male; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D010539:Permeability; D019736:Prostheses and Implants; D051381:Rats; D017208:Rats, Wistar; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D006882:Hydroxyapatites