A/W Bioactive Glass Particles in HEPES Solutions
A/W bioactive glass (BG) particles (600-1000 microns) were soaked in 0.1 M 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) solutions (0.01 g BG per 1 mL solution) at three pH ranges (acidic: 4.45-6.31, neutral: 7.45-7.64 and basic: 10.31-10.42). Crystalline calcium phosphates developed on BG surfaces after soaking in either acidic or neutral solutions. Electron diffraction (ED) results showed that whitlockite and octa-calcium phosphate (OCP) were the newly developed materials on BG in the acidic HEPES solution after soaking for 7 d and 14 d, respectively. Whitlockite also developed on the BG particles in the neutral solution of 0.5Na-HEPES after soaking for 14 d. No crystalline materials developed on BG surfaces after soaking in the basic Na-HEPES solution up to 14 d. The results of this study demonstrated that the pH of a soaking solution strongly affect both the ions release of the A/W BG particles, and the development of crystalline calcium phosphates on BG particles.
Panjian Li, Kai Zhang and Clifford W. Colwell, Jr.
K. Zhang et al., "A/W Bioactive Glass Particles in HEPES Solutions ", Key Engineering Materials, Vols. 284-286, pp. 501-504, 2005