Rheological Characterisation and Printability Assessment of an Optimised Bioink for Extrusion-Based 3D Bioprinting

The performance of extrusion-based 3D bioprinting depends critically on the rheology of bioinks, which must balance printability with post-deposition structural fidelity. Here we present a statistically optimised, human-compatible hydrogel formulation (hyaluronic acid, sodium alginate, Dextran-40), originally identified via Design of Experiment (DoE) methodology for target viscosity, and now subjected to comprehensive rheological validation. Flow curve analysis confirms the bioink's shearthinning profile, supporting its suitability for extrusion. Oscillatory amplitude and frequency sweep tests reveal a stable viscoelastic response within the linear viscoelastic region. In combination with pronounced shear-thinning behaviour and rapid thixotropic recovery, this supports the bioink’s ability to maintain structural integrity following deposition. A three-stage thixotropy test demonstrates rapid viscosity recovery following high shear, while temperature ramp testing shows expected increases in viscosity as temperature decreases, with no gelation observed in the printing-relevant range. Collectively, these findings validate the formulation’s suitability for cell-laden printing applications and offer a reproducible rheological benchmark for future bioink development in soft tissue engineering.