Lignin-Derived Carbon Dot/Cellulose Nanofiber Films for Real-Time Food Freshness Monitoring

Herein, a facile, environmental-friendly, and sustainable strategy for efficient separation, conversion, and utilization of lignocellulose components was developed. Lignocellulose components were separated by green deep eutectic solvent (DES). The extracted lignin had potential for downstream production of aromatic chemicals and was used to synthesize lignin-doped carbon dots (CDs) in a ratiometric fluorescent probe for detecting biogenic amines (BAs) that were generated from food spoilage. The preparation of CDs provided an efficient strategy to convert biomass waste into carbon-based nanomaterials. This probe exhibited a sensitive, rapid, and linear response to BAs with a low detection limit of 0.045 μM. The retained cellulose with the crystal I structure was used to prepare cellulose nanofibers (CNFs) via oxidation and mechanical treatment. Furthermore, the CNFs were used as a matrix to fabricate CDs/CNFs films for real-time and visual food freshness monitoring. From biomass waste to rational applications, this study not only expanded the comprehensive utilization of lignocellulose in a green and environment-friendly manner but also demonstrated the prospects of CDs-based composite films in on-site monitoring of food quality and safety.