Biocompatibility studies and characterization of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/polycaprolactone blends.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is a biocompatible and bioresorbable copolymer that has generated research interest as a bone scaffold material. However, its brittleness and degradation characteristics can be improved upon. We hypothesized that blending with medical-grade polycaprolactone (PCL) can improve degradation and mechanical characteristics. Here, we report the development of solvent-blended PHBHHx/PCL for application as a potential biomaterial for tissue engineering. Enhanced yield strength, yield strain and Young's modulus occurred at 30/70 blend when compared with PHBHHx and PCL. Polarized light microscopy demonstrated PHBHHx and PCL to exist as morphologically and optically distinct phases and, together with thermal analyses, revealed immiscibility. Hydrophilicity improved with the addition of PCL. Accelerated hydrolytic studies suggested predictable behavior of PHBHHx/PCL. Notably, 30/70 blend exhibited similar degradation behavior to PCL in terms of changes in crystallinity, molecular weight, morphology, and mass loss. Finally, human fetal mesenchymal stem cells (hfMSCs) were evaluated on PHBHHx/PCL using live/dead assay and results suggested encouraging hfMSC adhesion and proliferative capacity, with near-confluence occurring in PHBHHx and 30/70 blend after 5 days. Taken together, these are encouraging results for the further development of PHBHHx/PCL as a potential biomaterial for tissue engineering.