Nanogel cage based on oxidized sodium alginate sacrificial template: Enhanced stability and protein crosslinking performance of immobilized TGase

To address the challenges of natural enzyme instability and mass transfer limitations in traditional immobilization techniques, this study proposes a sacrificial template strategy to develop cage-like nanogels (GNI-TG) that integrate efficient substrate transport with enzyme conformation protection, significantly enhancing enzyme stability and catalytic efficiency. The study employed methacrylated/quaternized dual-modified dextrin (MQD) to construct the continuous matrix of the nanogel, while designing Ca 2+ -ethylenediaminetetraacetic acid (EDTA) dynamic-responsive oxidized sodium alginate (OSA) as the sacrificial template. Structural analysis confirmed that the OSA and MQD formed a stable TG-protected structure through synergistic cross-linking mechanisms involving covalent Schiff base bonding and non-covalent interactions. GNI-TG retained 70 % of initial enzyme activity while demonstrating exceptional thermal stability (>50 % activity after 70 °C treatment) and broad pH adaptability (>70 % activity within pH 4–9). Leveraging polysaccharide-protein synergistic effects, GNI-TG significantly enhanced the comprehensive performance of whey protein/gelatin hydrogels. Compared to physically crosslinked and free TG crosslinked systems, CNI-TG crosslinked hydrogels exhibited superior gel strength (536.4 g), compressive strength (28.12 kPa), water-holding capacity (>99 %), thermal stability (T m  = 138.4 °C), elastic behavior (G' > 1500 Pa), and network recovery (96.3 % recovery rate). This study establishes an enzyme immobilization paradigm through covalent anchoring, electrostatic assembly, and sacrificial templating strategies, demonstrating broad applicability in food processing, biocatalysis, and biomedical fields.