Selective protein adsorption and blood compatibility of hydroxy-carbonate apatites

✍ Scribed by Takemoto, Shinji ;Kusudo, Yuko ;Tsuru, Kanji ;Hayakawa, Satoshi ;Osaka, Akiyoshi ;Takashima, Seisuke

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 147 KB
• Volume: 69A
• Category: Article
• ISSN: 0021-9304
• DOI: 10.1002/jbm.a.30039

✦ Synopsis

Abstract

We examined the blood compatibility and protein adsorption on hydroxyapatite and hydroxy‐carbonate apatite. Those apatites were synthesized under a 0, 5, or 15% CO~2~‐containing N~2~ atmosphere by a wet‐chemical method with a strong ammonia alkali solution of calcium nitrate and diammonium hydrogen phosphate (5:3 in molar ratio) and subsequent calcination in the range of 105–700°C. From infrared (IR) analysis, the carbonate ions substituted both phosphate ions and hydroxyl ions in the hydroxyapatite lattice; the intensities of IR bands assignable to phosphate ions and hydroxyl ions were reduced on calcinations. The specific surface areas of synthesized apatites decreased with increasing calcination temperature. Blood‐clotting properties were evaluated in terms of active partial thromboplastin time, prothrombin time, and the amount of fibrinogen for the plasma in contact with the apatites, indicating that all the apatites barely influenced the blood clotting system. The apatites were in contact with a solution containing both bovine serum albumin (BSA) and β~2~‐microglobulin (β~2~‐MG), and the amounts of those proteins adsorbed on them were examined: the amount of absorbed BSA and β~2~‐MG gradually increased with the calcination temperature below 500°C, while it showed a sudden increase when more than 600°C. Hydroxy‐carbonate apatite synthesized under a 15% CO~2~‐containing N~2~ atmosphere and calcined below 400°C had the greatest selectivity in adsorbing β~2~‐MG. Thus, a higher selectivity for β~2~‐MG adsorption was empirically correlated to carbonate ions incorporated in the hydroxyapatite lattice. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 544–551, 2004