(601g) Preparation of Poly(L-lactic acid) Nanofibrous Scaffold with a Rough Surface in Supercritical Carbon Dioxide

Phase inversion using supercritical carbon dioxide (SC-CO₂) has been widely used in the development of tissue engineering scaffolds, and particular attention has been paid to obtaining desired morphology without additional post-treatments. However, the main challenge of this technique is the difficulty to generate a three-dimensional (3D) nanofiber structure with a rough surface in one step. Here, a poly(_L-lactic acid) (PLLA) 3D nanofiber scaffold with a rough surface is obtained via phase inversion using SC-CO₂ by carefully choosing fabrication conditions and porogens. It is found that this method can effectively modulate the structure morphology, promote the crystallization process of semicrystalline polymer, and induce the formation of rough structure on the surface of nanofiber. Meanwhile, the porogen of ammonium bicarbonate (AB) can produce a 3D structure with large pores, and porogen of menthol can improve the interconnectivity between the micropores of nanofibers. A significant increase in the fiber diameter was observed as the menthol content increases. Furthermore, the menthol may affect the mutual transition between the α' and α crystals of PLLA during the phase separation process. In addition, the results of protein adsorption, cell adhesion and proliferation assays indicate that cells tend to have a higher viability on the nanofiber scaffold. This process combines the characteristic properties of SC-CO₂ and the solubility of menthol to tailor the morphology of polymeric scaffolds, which may have potential applications in tissue engineering.