Iota-carrageenan and amidated low-methoxyl pectin gel with shear-thinning behavior for extrusion-based 3D printing of pancreatic tissue scaffold

Abstract

Hydrogels made from natural biopolymers are widely explored in tissue engineering due to their biocompatibility and tunable mechanical properties. This study investigates the rheological properties of iota-carrageenan (IC), amidated low-methoxyl pectin (ALMP), and their mixture (IC-ALMP) using linear small amplitude oscillatory shear and nonlinear large amplitude oscillatory shear. The cytocompatibility of the IC-ALMP bioink is evaluated through the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, while its printability is assessed via spreading ratio and pore printability measurements to determine its potential for tissue scaffold development. IC and IC-ALMP exhibit predominantly elastic behavior, whereas ALMP behaves as a fluid. Both IC and IC-ALMP maintain solid-like properties at low strain levels but lose their elastic network at critical strains of 112% and 97%, respectively. The IC-ALMP mixture also demonstrates shear-thinning behavior, enhancing its 3D printing potential. It achieves a pore value of 0.95 and a spreading ratio of 1.25. The MTT assay confirmed over 90\% survival of NIT-1 beta cells, indicating its non-toxic nature. These findings suggest that IC-ALMP bioink possesses favorable mechanical properties and cytocompatibility, making it a promising candidate for tissue scaffold development.