Europium/beet red network as dual-mode labels for perishable food monitoring and light-induced active preservation

Perishable food spoilage poses an increasing threat to public health, necessitating intelligent systems that integrate real-time freshness monitoring with active preservation. Herein, we constructed a smart dual-mode (fluorescence-colorimetric) sensor through coordination-driven assembly of europium ions (Eu 3+ ) with natural anthocyanin pigment (beet red, BR) forming flower-like nanostructures (Eu-BR) with photodynamically enhanced antimicrobial activity. Capitalizing on chromophore properties of BR and antenna effect of Eu 3+ , Eu-BR achieves ratio fluorescence/colorimetric sensing of pH to detect food freshness. The hierarchical material architecture amplified photodynamic potential of Eu-BR with enhanced light harvesting and electron transfer, achieving higher bacterial inhibition of S. aureus ATCC 29213 (99.62 %) and E.coli O157:H7 (99.39 %) under visible light-induced. Leveraging the biochemical principle that microbial metabolism generates volatile amines during meat decomposition, we developed a paper-based smart Eu-BR labels, achieving tripartite freshness classification of meat (fresh → medium fresh → spoilage) by detectable variations in fluorescence intensity and colorimetric responses. Notably, Eu-BR-functionalized labels achieve active light-activated preservation, effectively inhibiting bacterial growth (54.18 ± 1.9 % within 48 h). This mitigates spoilage indicators in shrimp and meat-including TVB-N accumulation, pH fluctuations, and weight loss-thereby extending product shelf-life.