Viscoelastic properties of thermosensitive gelatin/tragacanth hydrogel as novel ink suitable for additive manufacturing: Effect of various additives on system's viscoelastic characteristics and printability.

In this study, a novel hydrogel ink made from gelatin and tragacanth gum was prepared. Two additives and a crosslinking agent were added to improve the viscoelastic properties of the material during gelation and its printability. Alginic acid was introduced as a crosslinking agent along with additives such as rice starch and halloysite nanotubes (HNT). Two rheological measurement modes, rotational and oscillatory, were utilized to measure the steady state viscosity and complex moduli, respectively. Auxiliary measurements such as Fourier‐transform spectroscopy infrared and gel permeation chromatography were implemented to determine the bonds formed and the molecular weight of gelatin and tragacanth gum, respectively. We have demonstrated how these additives can affect fluid uptake by examining them in water at ambient temperature and also in 1× PBS at both ambient and normal body temperatures. The printability was analyzed by the grid pattern dispensed by interconnected filaments. It was observed that the sample containing HNT and rice starch show the best properties. The hydrogel nanocomposite, unlike the pure gelatin films, retains water and buffer solution for 72 h with minimum changes. Moreover, the printability criterion (Pr) was improved from 0.3 for pure gelatin to about 1 for the sample containing alginate, HNT, and rice starch. [ABSTRACT FROM AUTHOR]