The long chain branching poly(L-lactide)s were prepared by reactive processing of linear PLA using pyromellitic dianhydride and polyfunctional epoxy ether as the branching agent and their vascular stents were fabricated via 3D-printing.
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.
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.
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