Programmable metal ion-induced patterned multicolour carboxymethylcellulose-based fluorescent hydrogels for information encoding and encryption.

To enhance the usability, security, and data capacity of information encryption materials, an interpenetrating polymer network was developed through copolymerization of carboxymethyl cellulose and acrylamide. Using dimethyl sulfoxide as the solvent, gold nanoclusters and coumarin derivatives were introduced to produce three types of hydrogels that emit red, blue, and green fluorescence. These hydrogels exhibited fluorescence changes in response to Hg and Fe ions, enabling patterning. Leveraging their adhesive properties, the hydrogels were immobilized onto black substrates and Rubik's Cube surfaces to form a programmable functional matrix. Information encoding and encryption were realized through physical and chemical stimuli, ultraviolet light, and mobile scanning. The fluorescence quenching mechanism, associated with internal filtering and static quenching, was linked to imidazole, carboxyl, amide, and azomethylene groups. This metal ion-induced, multi-color, carboxymethyl cellulose-based fluorescent hydrogel patterning strategy, integrated with smartphone-scanning technology, offers a novel platform for advanced information storage and meets the increasing demand for digital encryption solutions.