Functionalizable coaxial PLLA/PDLA nanofibers with stereocomplexes at the internal interface

Multifunctionality of electrospun polylactic acid (PLA) nonwovens was generated by the morphological design of nanofibers. Coaxial fibers with a lower number average molar mass M-n PLLA core and a higher M-n PDLA shell form PDLA-PLLA stereocrystals at the interface, induced by annealing. In tensile tests under physiological conditions, the core-shell fibers with higher crystallinity (22% compared to 11-14%) had lower Young's moduli E (9 +/- 1 MPa) and lower elongation at break epsilon(b) (26 +/- 3%) than PDLA alone (E= 31 +/- 9 MPa, epsilon(b) = 80 +/- 5%), which can be attributed to simultaneous crystallization and relaxation effects. Gelatin incorporated in the PDLA phase was presented on the outer surface providing a biointerface putatively favorable for cell adherence. Gelatin incorporation did not influence the crystallization behavior but slightly lowered T-g (60 -> 54 degrees C). Employing exclusively polymers established in the clinic, multifunctionality was generated by design.