Design of Magnetic κ-Carrageenan-Collagen Bioinks for 3D Bioprinting

Bioprinting approaches are of great promise for tissue engineering (TE) applications, given that they allow the fabrication of constructs able to mimic native tissues' mechanical and topographical features. In this study, a novel bioink comprising κ-carrageenan (κc), collagen, and magnetic nanoparticles (MNPs) was designed for 3D bioprinting applications. κc is suitable for use in bioprinting due to its gelation and mechanical properties. Combining this polysaccharide with collagen and MNPs for remote stimulation of the printed scaffold, we successfully achieved a 3D-printed functional structure. Mechanical compressive tests yielded Young’s moduli ranging from 8.25 to 18.4 kPa. The addition of collagen caused this value to decrease, as expected, while the addition of MNPs had an opposing effect. The hydrogels also exhibited water contents over 97% in all formulations. Rheological assessments indicated a sol-gel transition temperature at 23-25ºC, making these bioinks suitable for extrusion-based bioprinting at room temperature. Printability analyses demonstrated excellent fidelity and structural integrity of the printed constructs, in addition to a high mesenchymal stem/stromal cell (MSC) viability after bioprinting. Finally, as proof-of-concept, it was observed that bioprinted MSCs stimulated with an external magnetic field of 80 mT were able to increase the number of tubes formed by human umbilical vein endothelial cells. In conclusion, this study constitutes a valuable approach for 3D bioprinting of multifunctional materials using novel bioink compositions, thus advancing TE technologies while creating new paths for future research in regenerative medicine applications.