Ultratough and Adhesive Polyacrylamide Grafted Chitosan Hydrogel Reinforced by Whey Protein for Dual-Mode Food Quality Tracking and Multilevel Information Encryption.

Food spoilage and product counterfeiting demand unified smart packaging solutions. This work reports a super-tough and highly adhesive hydrogel integrating anticounterfeiting and real-time freshness monitoring. The hydrogel, constructed from a polyacrylamide-grafted-chitosan network physically crosslinked with whey protein, exhibited a 2035% breaking elongation and 1.13 MJ/m3 toughness. It demonstrated exceptional defect tolerance (7.9 kJ/m2 tearing energy) and dynamic broad-spectrum adhesion (∼21 kPa on glass). When doped with nitrogen-doped carbon dots, the hydrogel displayed pH- and ammonia-responsive dual-mode fluorescence, enabling rewritable texts and smartphone-readable QR codes for high-security anticounterfeiting. Furthermore, it serves as a real-time indicator for monitoring chicken breast freshness. It provided accurate visual alerts synchronized with spoilage thresholds at 25 and 4 °C, exhibiting remarkable logistic correlation (R2 > 0.98) with TVB-N and pH levels. Overall, this work provides an intelligent platform integrating structural resilience, real-time food quality tracking, and data security for next-generation smart packaging.