Direct-write assembly of microperiodic silk fibroin scaffolds for tissue engineering applications

Three-dimensional, microperiodic scaffolds of regeneration silk fibroin have been fabricated for tissue engineering by direct ink writing. The ink, which consisted of silk fibroin solution from the Bombyx mori silk worm, was deposited in a layer-by-layer fashion through a fine nozzle to produce a 3D array of silk fibers of diameter 5 mu m. The extruded fibers crystallized when deposited into a methanol-rich reservoir, retaining a pore structure necessary for media transport. The rheological properties of the silk fibroin solutions were investigated and the crystallized silk fibers were characterized for structure and mechanical properties by infrared spectroscopy and nanoindentation, respectively. The scaffolds supported human bone marrow-derived mesenchymal stem cell (hMSC) adhesion, and growth. Cells cultured under chondrogenic conditions on these scaffolds supported enhanced chondrogenic differentiation based on increased glucosaminoglycan production compared to standard pellet culture. Our results suggest that 3D silk fibroin scaffolds may find potential application as tissue engineering constructs due to the precise control of their scaffold architecture and their biocompatibility.