Synthesis, characterization and biocompatibility of novel biodegradable poly[((R)-3-hydroxybutyrate)-block-(D,L-lactide-block- (ε-caprolactone)] triblock copolymers

Background: Biodegradable block copolymers have attracted particular attention in both fundamental and applied research because of their unique chain architecture, biodegradability and biocompatibility. Hence, biodegradable poly[((R)-3-hydroxybutyrate)-block-(D,L-lactide) -block-(e-caprolactone)](PHB-PLA-PCL) triblock copolymers were synthesized, characterized and evaluated for their biocompatibility. Results: The results from nuclear magnetic resonance spectroscopy, gel permeation chromatography and thermogravimetric analysis showed that the novel triblock copolymers were successfully synthesized. Differential scanning calorimetry and wide-angle X-ray diffiraction showed that the crystallinity of PHB in the copolymers decreased compared with methyl-PHB (LMPHB) oligomer precursor. Blood compatibility experiments showed that the blood coagulation time became longer accompanied by a reduced number of platelets adhering to films of the copolymers with decreasing PHB content in the triblocks. Murine osteoblast MC3T3-E1 cells cultured on the triblock copolymer films spread and proliferated significantly better compared with their growth on homopolymers of PHB, PLA and PCL, respectively. Conclusion: For the first time, PHB-PLA-PCL triblock copolymers were synthesized using low molecular weight LMPHB oligomer as the macroinitiator through ring-opening polymerization with D,L-lactide and ε-caprolactone. The triblock copolymers exhibited flexible properties with good biocompatibility; they could be developed into promising biomedical materials for in vivo applications.