Cellulose Luminescent Hydrogels Loaded with Stable Carbon Dots for Duplicable Information Encryption and Anti-counterfeiting

Luminescent hydrogels with flexibility and biocompatibility have attracted considerable interest in anti-counterfeiting application. However, conventional luminous substance is prone to release into the surrounding environment, causing accumulation and biotoxicity. The green synthesis of repeatable fluorescent materials from biomass remains challenging. Herein, we report the assembly of nano-cellulose hydrogel doped with naturally originated and multiple active sited carbon dots (CDs) and demonstrate the sustainable usage of information encryption. The problem of CDs leaching from the hydrogel matrix was solved via strong chemical interactions between the CDs and cellulose nanofibers. The facilely prepared hydrogels showed extraordinary mechanical properties and fatigue resistance (i.e., the stress, compressive modulus, and compressive toughness were up to 1607.30 kPa, 368.33 kPa, and 191.54 kJ/m3, respectively). Furthermore, this cellulose-based gel displayed bright green fluorescence under UV light, which could be quenched by Fe3+ ions and recovered in an ascorbic acid/EDTA-2Na mixture solution. Therefore, coded information can be easily input and interpreted via ionoprinting technique, realizing a simple display and erasing procedure. This elaborately designed biomimetic hydrogel can serve as effective communication media to improve security and expand critical applications in optoelectronic storage devices.