Enhanced rheological behaviors of alginate hydrogels with carrageenan for extrusion-based bioprinting.

Three-dimensional (3D) bioprinting using biocompatible materials is widely used in the field of tissue engineering and regenerative medicine. However, precise printing of 3D structures is challenging due to weak and uncontrollable mechanical properties of various hydrogels, thus limiting their potential in preclinical and clinical applications. In this study, our goal is to demonstrate the feasibility of precise fabrication of alginate/carrageenan composite scaffolds using extrusion-based 3D bioprinting. At first, the proper concentration of crosslinking agents was determined by the assessment of shear modulus of alginate-based hydrogels. Moreover, alginate/carrageenan composite hydrogels were prepared with different concentrations of carrageenan and used to measure their rheological properties. Based on the assessed viscosities and shear moduli of alginate and alginate/carrageenan hydrogels, printing resolutions in different printing parameters were simulated and presented in the printability maps. In addition, alginate and alginate/carrageenan scaffolds were bioprinted with various printing parameters and used to compare their printability with the simulated results. Also, 3D deposition of both alginate and alginate/carrageenan hydrogels were assessed and compared with each other by continuous monitoring of shape fidelity in 3D structures in ten layers and similar printing resolution. Finally, the cell viability of the 3D alginate/carrageenan composite scaffolds, printed using optimized printing parameters, was evaluated using live/dead staining and confocal fluorescence imaging. Thus, the results in the study show the potential uses of carrageenan for a prospective bioink with remarkable mechanical properties suitable for precise fabrication of 3D hydrogel scaffolds using bioprinting techniques.