3D-printable supramolecular hydrogels with shear-thinning property: fabricating strength tunable bioink via dual crosslinking

3-dimensional (3D) bioprinting technology provides promising strategy in the fabrication of artificial tissues and organs. As the fundamental element in bioprinting process, preparation of bioink with ideal mechanical properties without sacrifice of biocompatibility is a great challenge. In this study, a supramolecular hydrogel-based bioink is prepared by polyethylene glycol (PEG) grafted chitosan, α-cyclodextrin (α-CD) and gelatin. It has a primary crosslinking structure through the aggregation of the pseudo-polyrotaxane-like side chains, which are formed from the host-guest interactions between α-CD and PEG side chain. Apparent viscosity measurement shows the shear-shinning property of this bioink, which might be due to the reversibility of the physical crosslinking. Moreover, with β-glycerophosphate at different concentrations as the secondary crosslinking agent, the printed constructs demonstrate different Young's modulus (p < 0.001). They could also maintain the Young's modulus in cell culture condition for at least 21 days (p < 0.05). By co-culturing each component with fibroblasts, CCK-8 assay demonstrate cellular viability is higher than 80%. After bioprinting and culturing, immunofluorescence staining with quantification indicate the expression of Ki-67, Paxillin, and N-cadherin is higher in day 14 than those in day 3 (p < 0.05). Oil red O and Nissl body specific staining reflect strength tunable bioink may have impact on the cell fate of mesenchymal stem cells (p < 0.05). This work might provide new idea for advanced bioink in the application of re-establishing complicated tissues and organs.