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

Abstract

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/m 3 , respectively). Furthermore, this cellulose-based gel displayed bright green fluorescence under UV light, which could be quenched by Fe 3+ 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.

Light-responsive smart nanopapers and ink: design for information storage and encryption

“…Photoresponsive nanopapers are widely used for information storage, including writing and erasing. 34 It is well known that traditional “absorbing” storage can be used in white-light environments but not in dark environments; in contrast, “emissive” storage is more suitable for dark environments due to the influence of backlighting. Therefore, we designed a new type of dual-function information storage with “absorbing” and “emitting” functions (Fig.…”

Lanthanide-Functionalized Carbon Quantum Dot-Based Dual-Emission Hydrogels for Multilevel Anti-counterfeiting and Repeatable Information Loading

“…In the process of ion printing, encrypted information is acquired by the CDs@PVA-Alg film, facilitated by the spontaneous diffusion of Eu 3+ and Tb 3+ ions from the filter paper into the hydrophilic hydrogel. (Figure a) . In the process of decryption, the film displays the letter pattern with a red “US” and a green “ST” under 254 nm UV light, resulting in a “USST” output signal.…”

“…According to the research conducted by Wang et al, information was loaded into hydrogels using ion printing. Briefly, filter paper, shaped as needed, was immersed in EuCl 3 solutions (0.05, 0.5 mM) and TbCl 3 solutions (0.02, 0.2 mM) for 1 min.…”

“…Counterfeiting represents a global issue and poses a serious threat to public safety, social stability, and national security. Consequently, there has been rapid progress in the development of encryption/decryption strategies and anti-counterfeiting materials in recent decades. − To prevent counterfeiting, a various of anti-counterfeiting materials, such as two-dimensional codes, barcodes, watermarks, laser holograms, and luminescent patterns, , have been researched and applied to address the challenges posed by counterfeit products or misleading information. Nonetheless, it is difficult for traditional anti-counterfeiting materials (e.g., two-dimensional codes, barcodes, watermarks) to effectively prevent counterfeiting due to their ease of replication.…”

“…Wang et al prepared a cellulose-based hydrogel whose fluorescence could be suppressed by Fe 3+ ions and restored in an ascorbic acid/EDTA-2Na mixed solution. As a result, encoded information can be easily entered and interpreted via ion printing technology, enabling simple display and erasure processes . Several reports have been published on the separate application of luminescent hydrogel materials for multilevel anti-counterfeiting and repeatable information loading. , However, examples of the dual functionality of multilevel anti-counterfeiting and repeatable information loading based on the same type of material have not yet been reported.…”