Alginate-Gelatin Composite Hydrogels for Next-Generation 3D Bio-Printing in Tissue Engineering

The development of hydrogel bioinks faces several obstacles, including optimizing the printing parameters of bioinks, maintaining tissue vascularization, and ensuring good mechanical strength, among others. In this work, alginate-gelatin hydrogel bioinks are developed assessing the physical properties, including swelling properties, thermal properties, stiffness, and rheological properties and cell survivability. CaCl ₂ was used as a cross-linker to enhance the bio-inks’ mechanical stability. FTIR analysis of Ca ²⁺ crosslinked with sodium alginate-gelatin (SA-G) reports a slight shift in symmetric stretching carboxyl groups. Morphological structure of optimized SA-G bio-ink showed well porous interconnected net like structure. The swelling results show an inverse relationship with increasing the proportion of sodium alginate. Stiffness indicates the resistance of the hydrogel bioink's surface to deformation under applied load. Higher stiffness indicates solid behaviour, while lower stiffness indicates a viscous structure. The storage modulus (G'), loss modulus (G"), and phase angle, as measured by a rotational rheometer, which indicates the solid point, viscous point, and viscoelastic point. Cells (Schwann cells, Cancer cells and the co culture cells) survivability in 2D or monolayer system confirms the non-toxicity of the developed hydrogels for 3D/4D bioprinting. The 3D bio-printing was carried by extrusion bio printing process. 3D bio printed structure's stability and well size porous structure were analyzed by pore size and the life dead assay showed the live and dead cells after the bio-printing at day 10 using fluorescence microscopy. Thus the developed hydrogel can play a crucial roles for tissue engineering.