Biodegradable poly (lactic acid-co-trimethylene carbonate)/chitosan microsphere scaffold with shape-memory effect for bone tissue engineering.

Poly (lactic acid) (PLA), although extensively used as biomedical materials, has the distinct disadvantage of producing acidic byproducts which can lead to tissue inflammatory reactions and clinic failure. Here we presented a combination of Poly (lactic acid-co-trimethylene carbonate) and natural polymer chitosan, improving its compression resilience and reducing its acidic byproducts. In this case, we developed 3D scaffolds using solvent/nonsolvent technique sintered PLA-TMC and PLA-TMC/Chitosan microspheres with selected particle size (355-500 μm). By controlling the preparation methods and parameters, the porosity, pore size and mechanical properties of microsphere scaffolds can be designed and controlled. Strikingly, PLA-TMC/15 % Chitosan microsphere scaffolds possess shape-memory effect and rapidly recovered to initial shape when heated to 37℃ within 300 s. The microsphere scaffolds had a 3D porous architecture with pore size ranging from 105.67 ± 12.51 μm to 129.69 ± 11.39 μm. The mechanical and physicochemical properties of microspheres and scaffolds were characterized in details. Moreover, all microsphere scaffolds were qualified as their compressive modulus (120.36 MPa -195.32 MPa) matched the cancellous bone during 16 weeks degradation. Furthermore, CCK8 cell proliferation assay and ALP activity assay verified that the scaffolds were non-toxic and conductive to cell adhesion. The scaffolds are expected to be used in bone regeneration and bone repair field.