In vitro degradation behavior of shape memory PLLA-TMC random copolymers

Poly (lactic acid) (PLA) and poly (trimethylene carbonate) (PTMC) have been in-depth investigated in tissue engineering due to its excellent biocompatibility and controllable biodegradability. However, the acid metabolites of PLA degradation can accelerate the degradation process, resulting in tissue inflammation and postoperative allergy. Here three poly (L-lactide-co-trimethylene carbonate) (PLLA-TMC) random copolymers with L-lactide / 1.3-trimethylene carbonate ratios of 60:40, 70:30, 80:20 (PLTMC64, PLTMC73, PLTMC82 respectively) were synthesized to control the acid degradation and improve the compression resilience. The results showed that LA units on copolymers could improve water uptake and tension strength, reduce weight loss during the degradation (PLTMC82 for 6.53% after 16 weeks in enzymolysis). The crystallization, thermal properties and the surface and section morphology of copolymers were measured in detail for up to 16 weeks. Cell proliferation assay verified that PLLA-TMC copolymers presented excellent biocompatibility. The shape recovered rate of PLTMC73 was the most suitable for surgeons to complete complex implant operation, and 3D bioprinting bone repair scaffolds and 3D structured vascular scaffolds of PLTMC73 both possessed desired shape memory effect. Therefore, PLTMC with appropriate degradation rate and mechanical properties, intrinsically biocompatibility, and excellent shape memory ability, could provide a promising alternative in the field of cardiovascular and bone tissue repair engineering.