Chemically stable fluorescent anti-counterfeiting labels achieved by UV-induced photolysis of nanocellulose.

Carbon-based fluorescent security labels are effective methods to prevent counterfeiting. However, the properties of poor optical stability, complex and energy-consuming synthesis processes and weak bonding with substrates of carbon-based fluorescent materials limit their application prospects. Here, a novel in situ fluorescent patterning strategy is developed to achieve covert, chemically stable and solvent-tolerant cellulose-based security labels by UV exposure. The unsaturated double bonds as the origin of the fluorescence were generated during the photodegradation process under UV exposure. The fluorescent emission of cellulose-based materials reveals excellent stability under acidic, alkaline, reducing, oxidizing and non-polar solvent environments. These advantages give the cellulose nanofiber based security label fantastic potential applications.