Nowadays, information security has become a global issue with extensive influence, covering multiple aspects such as the economy, military, and daily life [1], [2]. A growing number of information security challenges, including information leakage and unauthorized access and use of data, continue to arise. Thus, ensuring the diversity and security of information transmission is crucial. In recent decades, people have made significant efforts in information storage and encryption, which have promoted the development of information storage, encryption/decryption, and anti-counterfeiting technologies [3], [4], [5].

The development history of information storage is closely linked to the advancement of information technology. In the early days, punched cards shouldered the responsibility for information storage in many fields due to their unique punching method [6]. And yet the limitations of paper carriers made large-capacity storage a challenge. Subsequently, technological innovations gave rise to a series of new storage tools, and hard disk drives achieved a qualitative leap in storage capacity [7], [8], [9], [10]. However, traditional hard or dry media for storing information are mostly static and lack functionality, making them difficult to use in damp, flexible and dynamic environments. In recent years, advancements in research on innovative materials have broadened the concept of information storage. This evolution extends beyond the traditional preservation of digital data to a paradigm that utilizes the intrinsic properties of materials for functional information encoding and responsive release. Within this framework, innovative materials derived from soft matter have garnered considerable attention due to their capacity to convey multidimensional information, encompassing chemical, optical, and mechanical properties, as well as their intelligent responses to environmental stimuli. Hydrogels, as intelligent materials derived from soft matter, have garnered widespread attention owing to their ability to carry multi-dimensional information and their intelligent responsiveness to environmental stimuli [4], [11].

Given the unique hydrophilicity, biocompatibility, and stimulus responsiveness of chitosan hydrogels, their potential for addressing unmet needs in encrypted storage, biomedical data preservation, and environmental information sensing deserves a systematic summary and discussion. Compared with synthetic hydrogels (see Table S1), chitosan, as the only cationic polysaccharide in nature, has unique biological properties, including antibacterial ability, antioxidant activity, biocompatibility, controllable physical properties and excellent biodegradability [12], [13]. Meanwhile, technologies such as dynamic self-assembly, electrodeposition and 3D printing provide key support for the information storage application of chitosan hydrogels [14], [15], [16]. These technologies, through the precise modulation of the microstructure and functionalities of hydrogels, impart to them capacities for dynamic response, programmable deformation, and multi-stable storage. These unique capabilities have established a new paradigm for encoding, erasing, and processing information in flexible media, thus paving the way for bionic intelligent storage systems.

This review delves into the utilization of chitosan hydrogel in advancing information storage research. The focus is on three main aspects: firstly, a detailed discussion on various preparation methods of chitosan hydrogels, encompassing techniques such as physical crosslinking, chemical modification, and composite functionalization; secondly, a thorough examination of the unique information storage mechanism; lastly, a comprehensive overview is presented of the potential applications in dynamic information storage, including high-security encrypted anticounterfeiting labels, rewritable flexible storage devices, biocompatible live information storage systems, and other innovative uses. These investigations not only surpass the constraints of conventional storage media in terms of flexibility and environmental adaptability but also establish a fundamental theoretical framework and technical foundation for the advancement of next-generation intelligent bioelectronic devices. Notably, chitosan hydrogels, owing to their exceptional biodegradability, environmental responsiveness, and controllable physical and chemical properties, exhibit distinct advantages in realizing biointegrated information storage, thereby paving the way for novel avenues in interdisciplinary fields such as medical information storage and biosensing.