Horseradish Peroxidase-Triggered Polydopamine-Modified Chitosan Hydrogels for Electrically Programmed and...

The exceptional multiple responsiveness of hydrogels has garnered significant attention for their potential in storing dynamic information. Self-erasing information observable by the naked eye provides an alternative method for data security. Herein, we report a polydopamine (PDA)-modified chitosan (CS) hydrogel that automatically reveals information without external stimuli. Information is embedded in a CS hydrogel containing horseradish peroxidase through an electrical writing process, creating localized high pH regions that trigger rapid enzymatic polymerization of dopamine (DA) into dark PDA. However, unwritten regions experience slower self-oxidation kinetics in air. This mismatched DA oxidation leads to information revelation and time-dependent erasure. The information lifetime can be precisely regulated by the number of electrical writing cycles and the magnitude of the electric current, enabling complex information decryption and allowing for the recognition of valid and invalid signals. These results offer valuable insights into fabricating and applying patterned hydrogels for information storage.