Ready-to-print alginate inks: The effect of different divalent cations on physico-chemical properties of 3D printable alginate hydrogels

Abstract

Studies about the use of different divalent cations to produce 3D printed scaffolds are almost limited to their application as secondary crosslinking agents after the printing of alginate. For this reason, this research aims to demonstrate the possibility to develop alginate hydrogel-inks for 3D-printing application, exploiting the ionotropic gelation in a preprint step, by paying attention to the role of divalent cations on hydrogel-inks properties. The investigation of transversal relaxation time highlighted differences among inks (barium-ink 90.04 ms, calcium-ink 84.33 ms, and zinc-ink 75.05 ms) suggesting a potential influence of different cations. If all the inks showed a shear thinning behaviour with similar flowability index (0.153±0.018), they were characterised by different consistency index (from 2420 to 574 Pa•s), extrudability and homogeneity, parameters that influence the printing setup. In fact, to reach the same flowability and thus low deviation in the layer width for all inks, a variation in printing pressure and speed was necessary. Overall, it can be deduced that alginate inks preparation following a preprint crosslinking approach could be a valid method to overcome the alginate printability issues underlining the possibility to select the crosslinking cation according to the technological properties wanted for the final matrix.

Keywords

• Alginate
• Ionic crosslinking
• Hydrogel-inks
• 3D printing