Fabrication of Dex-Loaded Shape Memory Polymer Based Composite Nanofibers ：for Potential Bone Tissue Engineering

Biodegradable shape memory polymers （SMPs） are a class of intelligent materials with great potential for imparting biomaterial scaffolds multifunetionality in the field of tissue engineering and regenerative medicine. In this study, the biodegradable SMP poly（ D, L-lactide-co-trimethylene carbonate） （PLMC） incorporated with the ,dexamethasone （Dex）, which was a kind of synthetic bone-formation inducing factor, was fabricated into nanofibers via dectrospinning. The morphology, constituent, thermal and mechanical properties of the produced Dex/PLMC composite nanofibers were characterized by scanning electron microscopy （SEM）, Fourier transform ：infrared spectroscopy （ FTIR ）, differential scanning calorimetry （DSC）, and tensile testing, respectively. Then, ultrasound was ,employed as a remote stimulus to regulate the Dex releasing behavior from the composite nanofibers. It was found that the generated Dex/ PLMC composite nanofibers had a uniform and smooth morphology with a diameter of ca. 564 nm. Mechanical testing results showed that incorporation of the Dex gave rise to improved mechanical performance with the tensile strength, Young＇ s modulus and strain- at-break increased by 18.2 %, 20. 0 % and 64.4 %, respectively. DSC data revealed that the glass transition temperature （ Tg ） of the composite nanofibers, i. e., the thermal transition temperature （Ttrans） for activating shape memory effect, was 39. 7 ℃. Moreover, the release kinetics of the encapsulated Dex in the aanofibers could be manipulated by varying the acoustic power and insonation duration. These results suggested that the newly developed Dex/PLMC nanofibers could be a promising drug delivery system for applications in bone tissue engineering （BTE）.

Fabrication of Dex-Loaded Shape Memory Polymer Based Composite Nanofibers for Potential Bone Tissue Engineering