Comparison of reactions of bioactive glasses in different aqueous solutions

In vitro reactions of bioactive glasses are commonly studied in different types of aqueous solutions, such as simulated body fluid (SBF), TRIS-buffer, and phosphate-buffered saline (PBS). SBF and TRIS have been used to study the reactions of bioactive glasses while PBS has been used to evaluate hydrolysis of polymer/bioactive glass composites. We compared the reactions of 45S5, s53P4, 1-98, and 13-93 in these solutions. Glasses were tested as granulates or fibers. The pH changes were recorded as a function of immersion time. Ions dissolved from the glasses were determined using ICP-AES. Formation of silica and apatite layers on the glasses was characterized using SEM-EDXA. The glasses reacted very differently in the three solutions. SBF produced the expected silica and apatite layers associated with the bioactive behavior. In TRIS no apatite layer formation was observed with the fiber samples. In PBS the apatite layer formation was the most rapid, and the glass itself dissolved at much higher rate than in the other solutions.