Collagen-Inspired Nano-fibrous Poly(L-lactic acid) Scaffolds for Bone Tissue Engineering Created from Reverse Solid Freeform Fabrication

Reverse solid freeform (SFF) fabrication was used to create highly-controlled macroporous structures in nano-fibrous poly (L-lactic acid) (PLLA) scaffolds. By using a computer-aided design (CAD) program to create a negative template for the scaffold, the three-dimensional (3-D) mold was created on a 3-D printer using a wax. After the template was printed, a solution of PLLA in tetrahydrofuran (THF) was cast into the mold, and was subsequently phase separated at -70°C which gives the nano-fibrous morphology. This resulted in a 3-D nano-fibrous scaffold with a uniform fiber mesh throughout the entire matrix, and greatly increased the surface area within the scaffold. Fiber diameters in these scaffolds were 50-500 nm, similar to type I collagen, and the densities of the fiber meshes can be altered by changing the polymer concentration. To examine the scaffold's potential for tissue regeneration, MC3T3-E1 osteoblasts were seeded and cultured on the scaffolds. Results show that the osteoblasts attached and proliferated on the scaffolds. After 6 weeks in culture, bone-like tissue was evident within the nano-fibrous scaffolds. By having the ability to control the macroporous architecture, interconnectivity, orientation, and external shape of the scaffold, as well as the nanometer-scaled fibrous features in the pore walls, this SFF fabrication/phase separation technique has great potential to design and create ideal scaffolds for bone tissue engineering.