Tragacanth gum hydrogels with cellulose nanocrystals: A study on optimizing properties and printability

This study investigates a novel all-polysaccharide hydrogel composed of tragacanth gum (TG) and cellulose nanocrystals (CNCs), eliminating the need for toxic crosslinkers. Designed for potential tissue engineering applications, these hydrogels were fabricated using 3D printing and freeze-drying techniques to create scaffolds with interconnected macropores, facilitating nutrient transport. SEM images revealed that the hydrogels contained macropores with a diameter of 100-115 μm. Notably, increasing the CNC content within the TG matrix (30-50 %) resulted in a decrease in porosity from 83 % to 76 %, attributed to enhanced polymer-nanocrystal interactions that produced denser networks. Despite the reduced porosity, the hydrogels demonstrated high swelling ratios (890-1090 %) due to the high water binding capacity of the hydrogel. Mechanical testing showed that higher CNC concentrations significantly improved compressive strength (27.7-49.5 kPa) and toughness (362-707 kJ/m³), highlighting the enhanced mechanical properties of the hydrogels. Thermal analysis confirmed stability up to 400 °C and verified ionic crosslinking with CaCl₂. Additionally, hemolysis tests indicated minimal hemolytic activity, affirming the biocompatibility of the TG/CNC hydrogels. These findings highlight the potential of these hydrogels as advanced materials for 3D-printed scaffolds and injectable hydrogels, offering customizable porosity, superior mechanical strength, thermal stability, and biocompatibility.