Biomimetic Double‐Protein Semi‐ <scp>IPN</scp> Hydrogels: Synergistic Protein–Polysaccharide Biomatrices for Healing, Immunomodulation, and Mineralization

This study introduces a biomimetic dual-protein semi-interpenetrating polymer network (semi-IPN) platform integrating collagen (C) and the phosphorylated globular protein ovalbumin within a bioactive polyurethane (PU) cross-linked matrix. Unlike previously reported collagen-PU-polysaccharide systems, the structural incorporation of a second protein phase enables cooperative regulation of mineral nucleation, interfacial charge distribution, and biological response. Three polysaccharides-starch (CA-A), carboxymethyl cellulose (CA-CMC), and xanthan gum (CA-GX)-were incorporated to modulate network architecture and functionality. Ovalbumin reduced gelation time (t₁/₂≈30 min), while polysaccharide chemistry governed crosslink density, swelling behavior, crystallinity, and degradation kinetics. CA-GX achieved the highest crosslinking degree (~63%), whereas CA-A exhibited pronounced swelling (~1125%). CA-CMC developed dendritic fibrillar domains with enhanced semicrystallinity, resembling extracellular matrix organization. The semi-IPN structure, confirmed by urea linkage formation, improved viscoelastic strength (G'≈420 Pa) and thermal stability (T_max≈380°C). All scaffolds were cytocompatible and supported fibroblast, monocyte, and bone-marrow-derived cell metabolism. The dual-protein architecture contributed to hemocompatibility, regulated platelet adhesion, selective antibacterial activity (stronger against Gram-negative bacteria), modulation of inflammatory markers (reduced TNF-α expression), and significant in vitro mineralization, with CA-CMC promoting nearly a 200% increase in carbonated hydroxyapatite deposition in simulated body fluid. By integrating structural collagen fibrils with a mineralization-active globular protein within a tunable polysaccharide-PU framework, this work establishes a multifunctional hybrid scaffold platform capable of coordinated soft- and hard-tissue regenerative responses beyond single-protein semi-IPN systems.