A Novel Stereocomplex Poly(lactic acid) with Shish-Kebab Crystals and Bionic Surface Structures as Bioimplant Materials for Tissue Engineering Applications.

The development of green material possessing with great mechanical properties and biocompatibility has become a primary goal for high-performance biological material applications. Herein, the oriented shish-kebab crystals of stereocomplex poly(lactic acid) (SC-PLA) are first reported to be successfully fabricated through a feasible solid-state drawing (SSD) process to simultaneously enhance the mechanical performance and biocompatibility. The resultant biomaterial exhibits a tensile strength of 373 MPa and elongation about 9%, with elastic modulus about 8.1 GPa. Such an outstanding toughening effect is due to an amalgamation of enhanced crystallinity of epitaxial secondary growth lamellae and orientation degree of the fibrous backbone of the SC-PLA samples, both gradually increasing with the draw ratio of SSD increasing. Uniquely distinguished from the typical biomedical polymer with the smooth surface structure, the as-obtained SC-PLA samples possess a surface morphology of parallel microgrooves within ridge structures, attributing to the highly oriented fibrous backbone structure complemented with regularly arranged epitaxial lamellas. This unique trait well represents the human vascular endothelial microstructure that is desirable for cell adhesion-growth to extend its proliferation, differentiation, and activity on the surface of SC-PLA.

Improving Mechanical Properties and Biocompatibilities by Highly Oriented Long Chain Branching Poly(lactic acid) with Bionic Surface Structures.

Exploiting the solid-state drawing (SSD) process toward polymer materials for medical implant devices is of significance to simultaneously improve the mechanical property and biocompatibility. Herein, for the first time, the bionic implants with a microvalley surface of oriented long chain branching PLA (b-PLA) was fabricated by a feasible SSD process. The as-obtained b-PLAs could not only show a high tensile strength (278.1 MPa) and modulus (4.32 GPa) but also bear a superior protein adsorption as high as 622 ng/cm2. Such exceptional mechanical properties and biocompatibility could be ascribed to the SSD process-induced highly orientation degree and the morphology of parallel grooves within ridges structures, resulting in the greatly enhanced crystallinity and surface hydrophobicity as well as a biocompatible vascular endothelial microstructure for cell to adhesion and growth and thus an improved proliferation, differentiation, and activity of osteoblasts with spindle-shaped and spread morphology on surface of the b-PLAs. These findings may pave the way for designing the novel biomaterials for vascular stent or tissue engineering devices by the SSD process.