Structure and properties of the precipitates formed from condensed solutions of the revised simulated body fluid

Precipitation experiments with aqueous solutions of the Kokubo's revised simulated body fluid (rSBF) equal to 2, 4, 8, and 12 times the ionic concentration of human blood plasma were performed. Instead of Hepes, solution pH was adjusted to the desired value of 7.40 +/- 0.02 by either bubbling of CO2 or addition of HCl. The experiments were performed in tightly closed plastic vessels kept at 37.0 +/- 0.2degreesC for 72 h under permanent shaking. Afterward, the suspensions were filtrated, and the precipitates were collected and analyzed. The results revealed that increasing the concentration of rSBF resulted in great changes in both the structure and the chemical composition of the precipitates. Phosphate substitution for carbonate (although the amounts of calcium and magnesium remained unchanged) and crystallinity decreasing were the most important modifications found in the precipitates formed from the highly condensed solutions of rSBF. (C) 2003 Wiley Periodicals, Inc.