| Abstract Scope |
Changing the phosphate-to-borate ratio of Na-Ca-borophosphate glasses creates compositions that form acidic, pH-neutral, or basic solutions when they react in aqueous environments, and so may be useful for different biomedical applications, particularly those that require the controlled release of ions that stimulate desired physiological responses. In the present study, particles (<20 microns) from pH-neutral glasses with the nominal molar compositions 16Na2O·(24-x)CaO·xTMO·40B2O3·20P2O5, where TMO = CoO, CuO, or ZnO and x=0,4, were exposed to Kokubo’s simulated body fluid (SBF) in a single-pass flow through system at 37°C and at flow rates of 1 or 2 mL/hr. Glass dissolution kinetics, calculated from the respective B-release rates, increased with flow rate but were unaffected by the choice of TMO. The release rates of the TM-ions to SBF varied greatly, in the order Cu2+>>Co2+>Zn2+. Instead of being released to solution, the Co- and Zn-ions were incorporated into calcium phosphate precipitation products. |