Fabrication and evaluation of a chitin whisker/poly(l-lactide) composite scaffold by the direct trisolvent-ink writing method for bone tissue engineering

Although poly(l-lactide) (PLLA) based porous scaffolds have been widely fabricated through 3D printing, their poor mechanical properties and osteogenic activity still do not meet the needs of bone tissue repair. Herein, chitin whiskers (CHWs), having outstanding mechanical properties, excellent cell affinity, osteogenic activity,etc. were designed to introduce into the PLLA matrix. Moreover, a trisolvent system, including dichloromethane (DCM), 2-butoxyethanlol (2-Bu) and dibutyl phthalate (DBP), instead of a single solvent system of DCM was chosen to prepare CHW/PLLA (CP) composite inks. Then, the CP porous composite scaffolds were further fabricatedviathe direct ink writing method. The as-printed CP composite scaffolds have good 3D porous structures with a pore size of 400 +/- 14 mu m and a porosity of 80 +/- 5%. Compared with the pure PLLA scaffold, the CP composite scaffolds showed significantly superior hydrophilicity and compression performance, and also were more conducive to cell adhesion, proliferation, and up-regulating alkaline phosphate activity and calcium deposition due to the presence of CHWs. Moreover, these promoting effects of CHWs are positively related to the content of the whiskers in the range of 0-20 wt%. However, as the content of CHWs further increased to 40 wt%, the compression performance, cell affinity and osteogenic activity of the corresponding 40%CP composite scaffold decreased, which may be attributed to the different microstructure of the scaffold from other composite scaffolds. Interestingly, compared with these scaffolds containing a lower mass content of CHWs, only the 40%CP composite scaffold exhibited significant anti-inflammatory properties. These robust CP composite scaffolds offer a new route for bone tissue engineering application.