A Study of the Printability of Alginate-Based Bioinks by 3D Bioprinting for Articular Cartilage Tissue Engineering

Three-dimensional bioprinting combined with natural hydrogels is a promising technology for the treatment of several pathologies and different tissue regeneration. One of the most studied tissues is cartilage, a complex and avascular tissue that displays a limited self-repair capacity after injuries. Herein, the development of alginate-based hydrogels and scaffolds containing different microstructure is presented and the printability of alginate by 3D bioprinting is studied. Rheological characterization was performed for the determination of viscosity and viscoelastic properties of hydrogels and mechanical characterization was carried out for the determination of compressive modulus of alginate hydrogels. All these characteristics were correlated with alginate behaviour during 3D bioprinting process. For the printability evaluation filament diameter, perimeter of the pores, area of the pores and shrinkage of alginate scaffolds were measured. The results demonstrate that alginate microstructure has a great influence on its printability and on hydrogels' physicochemical properties. Molecular weight of alginate determines its viscosity while M/G ratio determines cross-linking conditions and mechanical properties that vary with cross-linking density. These results suggest the importance of an exhaustive control of the viscoelastic and mechanical properties of alginate hydrogels to obtain structures with high resolution and precision.