The role of (HCO3)− ions in SBF on the interaction with bioactive glass-ceramic scaffold

Abstract

Simulated Body Fluid (SBF) has concentrations of inorganic elements nearly equal to those of human blood plasma (BP). However, there are some differences between SBF and BP which can distort the results of in vitro bioactivity tests. Contrary to BP, SBF has a too low concentration of (HCO3)- ions (only 4 instead of 27 mmol·dm−3) and on the contrary a higher concentration of Cl− ions (introduced by the TRIS-HCl buffer). Indeed, the main difference between SBF and BP is the presence of the TRIS buffer in SBF which is used for neutral pH maintaining. The aim of this work was to study the effect of (HCO3)- ions in non-buffered SBF on the solubility of a bioactive glass-ceramic material and the formation of a new phase on the sample surface. A highly reactive glass-ceramic scaffold derived from 45S5 bioactive glass was tested under static-dynamic conditions using SBF solution with different (HCO3)- ion concentrations (4, 20 and 27 mmol·dm−3). The results were compared with data obtained using standardized buffered SBF solution. A non-buffered SBF solution with a concentration of (HCO3)- ions closer to the real concentration in BP was shown to have the potential to replace the standardized SBF solution since the ISO 23317:2014 using SBF can give false-positive results of in vitro bioactivity tests.