Study on the particle texture dependence of protein adsorption by using synthetic micrometer-sized calcium hydroxyapatite particles

Rod-like calcium hydroxyapatites (Hap) with micrometer size were produced by supplying Ca(CH3COO)(2) and NH4H2PO4 solutions into a CH3COONH4 solution by varying their feeding rate at 85 +/- 5 degreesC and pH 7.4 +/- 0.2 under nitrogen atmosphere and vigorously stirring. The size of the Hap particles was increased with increase in feeding time (t(F)) of the solutions with increase in the t(F) the mean particle width and lengths were increased from 0.02 to 0.47 mum and from 0.12 to 5.21 mum, respectively. All these particles were highly crystallized and exhibited a single crystal and Ca-deficient natures with Ca/P atomic ratios of 1.50-1.59. TG and chemical analyses indicated that the chemical composition of the particles can be expressed to Ca10-x-y(HPO4)(x)(PO4)(6-x)(OH)(2-x-27).nH(2)O. The amount of adsorbed bovine serum albumin (BSA) onto the synthesized micrometer-sized Hap particles is strongly dependent upon their mean particle length (LP), while that of lysozyme (LSZ) onto the Hap particles exhibited a minor dependence on the L-p This protein adsorption behavior observed in,he present paper provided a definitive evidence that the C sites exposed on ac or bc crystal faces are the adsorption sites for BSA. (C) 2002 Elsevier Science B.V. All rights reserved.