Preparation and characterization of gelatin/sodium alginate hydrogel with a focus on improving rheological behavior and 3D printability

Introduction: Among a wide range of natural and synthetic polymers, gelatin and sodium alginate have received much attention for the preparation of hydrogels. In addition, 3D printing is of great interest with the ability to fabricate precise and porous structures for tissue engineering, as the printing of hydrogels showed many problems due to the change in rheological behavior. Methods: In this research, gelatin and sodium alginate hydrogels were prepared in different percentage compositions. The chemical structure of the prepared hydrogels was investigated by FTIR tests. Moreover, the swelling rate and degradation rate of hydrogels were evaluated. The viscosity of hydrogels was evaluated at different shear rates. Based on the result of the rheological test, the printability of the sample was investigated.Findings: The FTIR results showed that the simultaneous presence of these two polymers in the hydrogel structure causes physical interactions. The results of the swelling and degradation test indicated that increasing the amount of gelatin in the hydrogel structure increased water absorption (up to 215%) and the degradation rate of the hydrogel. Additionally, the viscosity measurement results showed the pure gelatin and alginate hydrogels have low shear thinning behavior, while the combination of these two hydrogels resulted in a series of reversible interactions and changes in free volume in the hydrogel structure, which caused shear thinning behavior with a 10-fold decrease in the viscosity of the hydrogel.