In nature, cephalopods dynamically change the color of local or overall skin by mechanically expanding/contracting pigment cells through muscle traction, thereby transmitting warning, courtship information, or camouflage to protect themselves. Inspired by this, scholars at home and abroad have proposed numerous information display and color camouflage systems in the past decade, such as using fluorescent molecules to directly write static information on the substrate material or constructing dynamic information through reversible covalent or non covalent networks responsive to stimuli. However, a single display mode exacerbates the risk of information being deciphered, and these strategies are difficult to achieve the conversion between static and dynamic information modes after preparation, let alone switch between the two display modes as needed according to changes in the environment. Therefore, compared with the color changing ability of cephalopods, existing information display systems still have significant gaps and shortcomings in color changing mechanisms and display results.

In recent years, researchers have gradually understood the core color changing mechanism of cephalopod skin through anatomical analysis. Cephalopods convert perceived external stimuli into bioelectric signals and transmit them to the radial muscle cell membrane that wraps around pigment cells through neurotransmitters. These bioelectrical signals trigger the relaxation/contraction of radial muscles, thereby driving pigment cells to undergo volume changes and achieving dynamic changes in skin color. In addition, based on the analysis of environmental requirements, cephalopods also release nerve inhibitors (acetylcholine) at specific points in the body to reset membrane potential, accurately inactivating certain radial muscle cells that wrap around pigment cells, thereby hindering the contraction of local pigment cells and achieving customized control of skin color. After a period of time, these secreted acetylcholine will be metabolically absorbed, allowing muscle cells to regain their deformability. It is precisely through the unique chemical gating driving strategy of muscle tissue surrounding pigment cells that cephalopods are able to achieve multi color and patterning of their skin based on the method of "electric triggering muscle driving pigment cell deformation" without changing the arrangement and composition of their own pigment cells, in order to adapt to the dynamic changes of the environment. Therefore, in artificial information systems, designing and developing similar gate control units to achieve a "single input multiple outputs" and dynamic/static collaborative mode is of scientific significance for existing information display and encryption processes.

Chen Tao and Lu Wei, researchers of Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, are committed to the bionic construction, function and intelligent regulation of fluorescent polymer hydrogels. Recently, the team cooperated with Zhao Chuanzhuang, a professor of Ningbo University, to imitate the chemical gated camouflage behavior of cephalopods, and reported the chemical gated hydrogel drive system, so as to achieve 3D multimodal display of fluorescence information. The team designed and synthesized azoacrylamide monomer (ABAM), and copolymerized it with acrylamide monomer (AAm) to obtain P (AAm co ABAM) hydrogel. In this gel system, due to the hydrophobic effect of azobenzene groups, the polymer chain is pulled closer, which promotes the formation of chain hydrogen bonds between the hydrogen bond donor (- NH2) and the hydrogen bond acceptor (C=O) of the acrylamide chain segments between the chains, and induces the system to produce a temperature sensitive behavior with the highest critical eutectic temperature (UCST). On this basis, similar to the role of acetylcholine in the chemical gating process of cephalopods, researchers have incorporated cyclodextrin（ α- CD) into the surrounding environment of gel. At this point, based on α- The host guest interaction between CD and azobenzene groups results in hydrophobic azobenzene groups being α- CD wrapping shielding gradually restores the mobility of acrylamide chains and moves away from each other, making it difficult for polymer chains to form chain hydrogen bonds, thus gradually losing their UCST type temperature sensitive properties.

On this basis, the researchers used the interfacial diffusion polymerization strategy to grow PAAm passive layer gel on the surface of P (AAm co ABAM) hydrogel, and constructed a double-layer hydrogel driver with chemical gating characteristics. The research further used the same method to combine the driver with the fluorescent hydrogel, and with the help of the display panel, jointly constructed an information display system based on chemical gating of "thermal trigger driving deformation fluorescence output". In this system, the rise of ambient temperature triggered the UCST type volume swelling of P (AAm co ABAM) layer hydrogel, which led to the displacement of the bottom layer fluorescent hydrogel, and finally dynamically and accurately output fluorescent information on the display panel. By reasonably configuring the length of the fluorescent hydrogel, this synchronous temperature sensitive driving behavior will never be able to fully display the two-dimensional code pattern, thus realizing the hiding and encryption of the target information. When decryption is required, it can be used α- CD fixedly shields the temperature sensitive characteristics of one of the hydrogel drivers, so that it always displays static fluorescence information under external stimulation. In this case, only the remaining hydrogel drivers need to be driven and deformed by heating, and the complete two-dimensional code pattern can be displayed. This biologically inspired chemical gating strategy achieves display capabilities of single input multiple output, dynamic/static dual-mode, and spatiotemporal regulation, providing the possibility of functional integration for artificial display systems and opening up new avenues for improving information security.

The related achievements are titled Cephalopod Inspired Chemical gated Hydrogel Execution Systems for Information 3D Encoding Display and published in Advanced Materials. The research work has received support from the National Natural Science Foundation of China, the National Key Research and Development Program, and the Zhejiang Provincial Natural Science Foundation.