Tailored degradation of biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/calcium...

Biodegradable materials, which are currently available for bone tissue regeneration, still have limitations regarding their degradation rate, mechanical stability and/or biological response. Thus, a novel generation of materials for bioactive bone scaffolds is needed that triggers hydroxyapatite formation and can be tailored to suit application-specific requirements. In this study we developed ternary bioactive composite materials composed of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), calcium silicate and poly(lactide-co-glycolide) (PHBV/CS/PLGA), which merged the good bioactivity of CS/PHBV composite and the improved degradation velocity of PHBV/PLGA blend. Bioactive character of all composites was proven by formation of hydroxyapatite-like crystals after already one week of incubation in simulated body fluid. Addition of PLGA significantly increased initial ultimate tensile strength (UTS0) and Young's modulus of the ternary composites from 14.3±1.1 MPa (binary composite) to 22.3±2.6 MPa and 1.23±0.05 GPa up to 1.64±0.14 GPa, respectively. Furthermore the degradation rate (measured as a decrease of UTS during degradation) could be successfully tailored and was in range of -0.033 UTS0 to -0.118 UTS0 MPa/week. The bioacceptance of the materials was proven in vitro using 2-D (conventional setup) and 3-D (multicellular spheroids) human bone marrow stromal cell cultures.