3D Bioprinted Natural Hydrogels: Rheological Characterization, Cytotoxicity, and Printability Assessment of a Polysaccharide-Based Bioink

The creation of natural bioinks suitable for three-dimensional (3D) bioprinting remains a significant challenge in developing functional and biocompatible materials for tissue engineering. In this work, a novel bioink formulation was designed using food-grade polysaccharides, κ-carrageenan (KC), tragacanth gum (TG), and konjac glucomannan (KG), and thoroughly evaluated. Each component was tested at varying concentrations through rheological analysis, in vitro cytotoxicity assays (MTS test with HEK293T cells), and printability assessments using a commercial bioprinter. Optimal concentration ranges were identified as ≥2% for KC, ≥1.5% for TG, and 1.5-2% for KG, which were then combined into two candidate hydrogel formulations (A and B). Both exhibited viscoelastic behavior and pseudoplastic flow characteristics. Formulation B (2% KG) demonstrated greater structural rigidity (<i>G</i>' ≈ 40 kPa) and excellent print fidelity (>84%) under multiple extrusion conditions, while formulation A (1.5% KG), though mechanically less robust, showed superior biocompatibility, achieving 86.5% cell viability after 24 h and 82.1% after 48 h. Overall, the study underscores the promise of food-derived polysaccharides as sustainable and customizable bioink components, with potential applications in engineered tissue scaffolds, in vitro models, and biocompatible 3D-printed systems.