Mineralisation of bioceramics in simulated plasma with physiological CO2/HCO −3buffer and albumin

Abstract

A carbonated simulated inorganic plasma (CSIP) physiologically buffered with carbonate-hydrogencarbonate, where a flow of CO₂ at controlled partial pressure enables pH control between 7.3–7.4 while maintaining a constant HCO⁻₃ concentration within the plasmatic range (24 to 27 mmol dm⁻³), was previously developed and reported by the authors. The present work represents a step forward, by introducing albumin in this solution, to produce albumin-containing CSIP (CSIPA). Mineralisation studies were performed on three materials (two calcium phosphate ceramics and a glass of the Si-Ca-Mg-P system) in CSIPA, and compared with those performed in traditional Tris-buffered Kokubo's SBF containing albumin (SBFA). It was found that the formation of apatite deposits in CSIPA is favoured when compared not only with SBFA, but also with albumin-free CSIP. The results indicate that the presence of HCO⁻₃ in physiological concentration and/or the absence of Tris/HCl buffer may alter the role of albumin in the mineralising medium. The results also suggest that CSIPA-simulated plasma not only mimics in vivo biomineralisation more closely than traditional SBF, but may also be a suitable medium for biomimetic deposition of apatite.