Microfluidic one-step fabrication of structurally tunable alginate hydrogel microspheres via multiphase shear-induced emulsification/internal gelation

Alginate hydrogels are widely studied for biomedical applications due to their biocompatibility and tunable properties, yet conventional microsphere fabrication faces challenges in structural precision, process complexity, and flexibility. This study addresses the critical challenge of precise structural control in alginate microsphere fabrication by developing an innovative one-step microfluidic strategy based on multiphase shear-induced emulsification/internal gelation. Using a phase-sequence inversion technique in a coaxial capillary device, we achieve selective generation of solid-core or capsule-type architectures. Through synergistic optimization of flow parameters, concentrations, and viscosities, we demonstrate precise regulation of microsphere diameter (500–950 μm) and morphology (aspect ratio 0.95–1.05). Systematic investigations reveal distinct volumetric shrinkage behaviors during thermal curing, with capsule-type microspheres exhibiting accelerated contraction kinetics. The integration of TiO₂/Fe₃O₄ nanoparticles into capsule structures enables complete photocatalytic degradation of methylene blue, validating environmental remediation utility. This work establishes a scalable platform for tunable hydrogel carrier fabrication, advancing microfluidic droplet engineering fundamentals for biomedicine and environmental applications.