6 Conclusions
A carrageenan-based bioink gel system was established using 1.5% w/v
carrageenan to induce rapid gelation of the silk and injectability
during printing, allowing the formation of self-standing gel constructs.
The printability of carrageenan-based hydrogel was found to improve with
increasing concentrations of alginate and MCNTs in the composite
hydrogels, and it was found to be the best with the alginate
concentration of 1.5% w/v and MCNT concentration of 0.05% w/v. We
optimised the printing parameters based on the rheological properties
and applied them on kc-s and kc-c composites. Using this approach, we
demonstrated excellent structural strength and printability of the
carrageenan composite without significant negative effects on the cell
viability (>93% average cell viability). With respect to
shear force gradients in different areas of the gel filament, we found
that despite the different printing pressures, the average cell survival
rate of the printed gel also had a certain gradient, and the difference
in each area was approximately 5%. This shear force gradient affects
the microstructure of the gel filaments and can induce cell growth while
responding to the material’s response to shear stress. The
carrageenan-based bioink system was found to be compatible with HUVECs
loaded in the gel matrix, kc-s, and kc-c, supporting better cell growth
relative to carrageenan gel. It could achieve precise adjustment of the
pore size, porosity, and pore distribution of the hydrogel structure by
optimising the printing parameters and realising the precise preparation
of the internal structure of the 3D hydrogel-based tissue engineering
scaffold. Finally, with the optimal printing conditions, the carrageenan
composite hydrogels (kc-s and kc-c) demonstrated the potential as a
prospective bioink for fabricating purposes and as a promising
3D-printed scaffold with remarkable mechanical properties, while
maintaining the structural and biological activity, in the field of
tissue engineering and regenerative medicine.