Formulation and characterization of an interpenetrating network hydrogel of locust bean gum and cellulose microfibrils for 3D printing

Locust bean gum (LBG) and cellulose microfibers (CMFs) in an interpenetrating hydrogel were developed as a bioink for 3D printing. X-ray diffractometry and scanning electron microscopy revealed the intermolecular interactions of the constituent polymers, especially in the matrix containing 3-5% LBG. Thermogravimetric analysis revealed the relatively high thermal stability of the hydrogels. Flow behavior index, viscoelasticity, and gel strength increased as LBG increased from 1-5% in the matrix. As expected, for a 3D printed construct from an interpenetrating hydrogel of 1% CMFs with 4% LBG, the highest conformity to the designed 3D model was obtained when it was printed at a 50% infill density and a 10 mm/s printing speed, with a 0.8 mm nozzle diameter and 0.4 mm layer height. In addition, the CMFs with 4% LBG hydrogel maintained high shape stability until 6 h after printing. Therefore, CMFs/LBG-based hydrogels are expected to be useful as a bioink. Industrial relevance: Interpenetrating network hydrogels produced from natural polysaccharides have attracted the attention of the food and biomedical industries because of their good mechanical properties and non-toxicity. In particular, utilization of legal food ingredients such as cellulose and locust bean gum might be valuable. 3D printing can ease the fabrication of complex structures using interpenetrating network bioinks, facilitating accuracy, reproducibility, and throughput, to produce customized food and biomedical products.