DHTA-modified CuCe layered double hydroxide-reinforced Gelatin/oxidized starch hydrogel pads: Synergistic antibiosis, antioxidation, and Ammonia sensing for shrimp fresh-keeping.

Oxidative deterioration, microbial proliferation, and accumulation of spoilage exudates are the primary factors triggering freshness loss in aquatic products. Traditional preservation approaches mainly depend on plastic packaging and cold-chain logistics, which cannot fundamentally resolve spoilage-related problems. To tackle these bottlenecks and develop innovative preservation materials, we designed a 2,5-dihydroxyterephthalic acid (DHTA)-modified CuCe layered double hydroxide (LDH). The Ce4+/Ce3+ and Cu2+/Cu+ redox couples provided multienzyme-like antioxidant activity, while the Cu₂O crystals imparted excellent antibacterial properties, accompanied by distinct color changes in response to ammonia. Subsequently, CuCe-LDH-DHTA was introduced into gelatin/dialdehyde starch to obtain a composite preservation pad (OGCL). The addition of CuCe-LDH-DHTA enhanced the crosslinking of the matrix pad, improved its Young's modulus, and endowed OGCL with antibacterial and antioxidant properties. The results demonstrated that the composite pad could effectively absorb spoilage exudates and extend the shelf life of shrimp. Specifically, the 72 h total volatile basic nitrogen (TVB-N) content of shrimp in the experimental group approached 20 mg/100 g, which was 58% lower than that of the control group, and its ammonia-responsive property showed great potential as a freshness indicator. Finally, cytotoxicity was evaluated using the CCK-8 assay. OGCL-3-10 exhibited no apparent cytotoxicity while inhibiting 99.99% bacterial growth. The cellular reactive oxygen species-scavenging assay further confirmed its antioxidant activity at the cellular level.