Pre-Crosslinking with Hydrogel Microparticles Enhances the Printability of Alginate-Based Inks

This study introduces a pre-crosslinking strategy for alginate and oxidized alginate bioinks using alginate-based hydrogel microparticles (HMPs) as calcium ion reservoirs to enhance printability in extrusion-based bioprinting. Incorporation of HMPs significantly increased ink yield stress and viscosity while reducing loss angle, enabling stable printing of low-concentration alginate formulations without pH reduction or addition of foreign materials. Post-crosslinking mechanical analysis revealed that increased HMP content led to reduced elastic modulus and more porous microstructures, attributed to altered calcium diffusion and network formation. In vitro studies demonstrated sustained NIH/3T3 fibroblast viability and proliferation in gelatin-modified, HMP pre-crosslinked hydrogels, supporting their suitability for 3D cell culture and bioprinting applications.