Production of hydrogel inks for fresh 3D printing based on esterified pectin

Fresh 3D printing allows tissue and organ equivalents to be prototyped for biomedical applications by extruding hydrogel "ink" into a bath with a supportive gel containing an active crosslinking component. The aim of this work is to select the conditions for the formation of a supportive gelatin matrix, to obtain hydrogel inks and functional products based on esterified pectin.
The following research objects were selected: aqueous solutions of thermally reversible gelatin protein (2.5-3 wt. %) and UP (2-6 wt. %), as well as solutions of CaCl2, an ion-type crosslinking agent for UP, selected in a molar ratio.
As a result of the research work, cooling curves of gelatin and UP solutions were obtained, presented in Arrhenius coordinates, on the basis of which the values of the activation energy of the viscous flow and the gelation process were obtained. The concentration dependences of the gelation temperature and dynamic viscosity were obtained, and the effect of concentration on the mechanism of structure formation was studied. The concentration dependences of dynamic viscosity indices on pH for equiviscid and equiconcentrated solutions are investigated. The working concentrations of a gelatin-based hydrogel bath and UP ink have been established. The effect of the molar content of calcium chloride on the mechanism and rate of Ca2+-induced gelation of unipectin working solutions has been studied. The strength characteristics of gel systems and the frame-type products based on them were determined using a rupture testing machine (RKM X.1.01 PS, Russia). A complex of biological tests of the cytocompatibility and hemocompatibility of the hydrogel components of the system was carried out.
Based on the conducted research, it was found that the implemented approach to the adaptation of hydrogels based on esterified pectin opens up new opportunities for the production of carcass structures using the technology of fresh printing on a 3D bioprinter (Fabion, Russia).