Pre-crosslinked ozonized alginate-agar hydrogel with anthocyanin for advanced 3D printing

Three-dimensional (3D) printing technology has garnered significant attention for its versatility and potential in creating personalized materials and designs. This study explores the use of ozonized sodium alginate (SA), extracted from seaweed, as a base for hydrogel ink—where ozonation serves to enhance the material’s properties. Hydrogels based on either ozonized or commercial SA were developed by pre-crosslinking with CaCl 2 , incorporating agar, and enriching with a powdered anthocyanin-rich extract to provide additional functional benefits. The formulations exhibited notable differences in physicochemical properties (zeta potential and hydrodynamic diameter) and structural characteristics (MIR-ATR spectroscopy and microstructure), suggesting probable interactions among the hydrogel components. Both formulations displayed viscoelastic behavior, with the ozonized SA hydrogel showing a higher storage modulus (G′), though it was less resistant to deformation. Optimized 3D printing parameters were established through printability testing. Cubic 3D structures printed from both formulations—using a 1.2-mm nozzle diameter and a printing speed of 5.0 mm/s—remained stable for up to 24 h and exhibited similar texture profiles. While formulation adjustments may be necessary to further enhance mechanical properties, this study highlights the promising potential of ozonized SA-based hydrogels. The combination of SA, agar, and anthocyanin-rich extract presents a compelling opportunity for applications in the food and medical industries. • Ozonized sodium alginate (SA) hydrogel demonstrated 3D-printing-compatible rheology. • 3D-printed constructs with ozonized SA had a texture profile like commercial SA. • Powdered anthocyanin-rich hydrogel formulation exhibited good 3D printability. • Enriched ozonized SA-based hydrogels pave the way for diverse applications.