Bioactivity and mechanical properties of scaffolds based on calcium aluminate and bioactive glass

Abstract

Abstract Scaffolds were developed from mixtures of calcium aluminate (CA) and a bioactive glass (BG) and the effect of glass content on the mechanical strength and bioactivity of scaffolds was studied. Three different mixtures were tested: 95CA-5BG, 92.5CA-7.5BG and 90AC-10BG wt.%. Also, for comparison purposes, pure CA was used. In order to obtain the calcium aluminate cements (CAC), mixtures were hydrated using a water/mixture ratio by weight (w/c) of 0.4 and, with the resulting pastes, scaffolds were made by the lost-spheres method using PMMA beads. These materials showed interconnected pores (215 μm average diameter). Obtained scaffolds were loaded with antibiotic (gentamicin sulfate) and its release kinetics was studied. The evaluation of the in-vitro bioactivity was carried out by immersing scaffolds in a simulated body fluid (SBF) for 1, 7, 14 or 21 days at 36.5 °C. Compressive strength was evaluated before and after each immersion period. In all cases the formation of a Ca,P-rich compound on the surface of the scaffolds was detected after immersion in SBF. The amount of the bioactive compound formed as well as compressive strength increased as the amount of bioglass was increased. A controlled antibiotic release in SBF, with diffusion-controlled kinetics, was observed. In addition, scaffolds were not hemolytic. According to the results obtained, these materials are promising candidates for biomedical applications as drug delivery systems.