Cellulose self-erasing material with dual functions in information encryption

Materials capable of multiple encryption, color-changing visualizations, and time-dependent functionalities are ideal for efficient and secure information storage and transmission. In this study, a time-dependent self-erasing material (TDSEM) containing urease developed through the in-situ synthesis of gold nanoclusters on the surface of cellulose nanocrystal (CNC) chemically bonding fluorescein isothiocyanate. CNC not only played an important role as a long-term stabilizer for the material, but also acted as a bridge facilitating the assembly of organic and inorganic interfaces, enabling the integrated system to achieve multi-color regulation and fluorescence resonance energy transfer. The TDSEM demonstrated excellent pH responsiveness, cyclic stability, and durability. The information was encoded by directly introducing HCl/urea into the TDSEM, and automatically erased over time. Additionally, the fluorescence intensity and color (transitioning from red to orange to green) were modulated over a time scale by adjusting the urea concentration, thus precisely controlling the time to retrieve the correct information (22 min). The confidentiality of the encoded information was enhanced by dual "locking" of time and color, ensuring that decryption only occurred "time color key". This time-dependent and color-varying dual functions provide valuable insights for the development of advanced information encryption and anti-counterfeiting technologies.