Biodegradable cellulose nanocrystal composites doped with carbon dots for packaging and anticounterfeiting applications.

Developing sustainable and multifunctional materials is imperative for advancing anti-counterfeiting measures, sensing technologies, and intelligent packaging solutions. Concurrently, materials based on carbon dots (CDs) and cellulose nanocrystals (CNCs) are becoming established in such applications. Therefore, herein, we present the fabrication and characterization of water-based CDs and CNCs from (black lentil: BL). The carbon dots (CD) were doped with nitrogen (NCD) and sulfur (SCD). These CDs were then utilized as anti-counterfeit inks and multifunctional sensor films when loaded in a biodegradable CNC matrix. These CD, SCD, and NCD exhibited diameters of 3.7, 5.3, and 5.5 nm, respectively, with bandgap values ranging from 3.65 eV to 2.95 eV. For anti-counterfeiting, CDs/CNC-based inks were applied to white sheets, rendering them invisible under normal lighting conditions and visible under UV light (365 nm). NCD exhibited sensitivity towards pH changes (2-12), demonstrating the sensing potential of NCD/CNC films for monitoring food freshness. Additionally, NCD/CNC-based films have exhibited effective control over microbial load due to nitrogen doping. These films biodegrade within 29 days when buried in soil after use. This innovative approach presents multifunctional films that address critical needs in sensing, anti-counterfeiting, and intelligent packaging and opens new avenues for creating eco-friendly, multifunctional materials.