Cellulose-based fluorescent materials for real-time visual detection of Fe³⁺/Cu²⁺ ions and anti-counterfeiting

Transition metals such as Fe³⁺ and Cu²⁺ are essential for fundamental biological processes, yet their excess can trigger diverse symptoms and diseases. Therefore, precise detection of Fe³⁺/Cu²⁺ via real-time and visual analytical techniques is urgently required. In this work, cellulose-based fluorescent material was designed via Steglich esterification by grafting perylene-3,4,9,10-tetracarboxylic acid (PTCA) onto cellulose acetate (CA) backbone. The resulting materials (CA-PTCA) exhibited bright yellow fluorescence, which was quenched in the presence of Fe³⁺/Cu²⁺, providing a highly sensitive detection platform. The fluorescence quenching by Fe³⁺ occurs via a photoinduced electron transfer (PET) mechanism with CA-PTCA, while that by Cu²⁺ proceeds through coordination. Moreover, the excellent processability of the CA backbone enables CA-PTCA to be fabricated into diverse material forms, including inks, coatings, films, aerogels, and fibers, all of which retain outstanding fluorescence properties. This work highlights the potential of cellulose-based fluorescent materials for multifunctional applications in sensing and information encryption.