Cephalopod-Inspired Design of Photomechanically Modulated Display Systems for On-Demand Fluorescent Patterning

Cephalopod-Inspired Nanomaterials for Optical and Thermal Regulation: Mechanisms, Applications and Perspectives

The manipulation of interactions between light and matter plays a crucial role in the evolution of organisms and a better life for humans. As a result of natural selection, precise light-regulatory systems of biology have been engineered that provide many powerful and promising bioinspired strategies. As the "king of disguise", cephalopods, which can perfectly control the propagation of light and thus achieve excellent surrounding-matching via their delicate skin structure, have made themselves an exciting source of inspiration for developing optical and thermal regulation nanomaterials. This review presents cutting-edge advancements in cephalopod-inspired optical and thermal regulation nanomaterials, highlighting the key milestones and breakthroughs achieved thus far. We begin with the underlying mechanisms of the adaptive color-changing ability of cephalopods, as well as their special hierarchical skin structure. Then, different types of bioinspired nanomaterials and devices are comprehensively summarized. Furthermore, some advanced and emerging applications of these nanomaterials and devices, including camouflage, thermal management, pixelation, medical health, sensing and wireless communication, are addressed. Finally, some remaining but significant challenges and potential directions for future work are discussed. We anticipate that this comprehensive review will promote the further development of cephalopod-inspired nanomaterials for optical and thermal regulation and trigger ideas for bioinspired design of nanomaterials in multidisciplinary applications.

Dual-Mode Hydrogels with Structural and Fluorescent Colors toward Multistage Secure Information Encryption

Constructing an anti-counterfeiting material with non-interference dual optical modes is an effective way to improve information security. However, it remains challenging to achieve multistage secure information encryption due to the limited stimulus responsiveness and color tunability of the current dual-mode materials. Herein, a dual-mode hydrogel with both independently tunable structural and fluorescent colors toward multistage information encryption, is reported. In this hydrogel system, the rigid lamellar structure of poly(dodecylglyceryl itaconate) (pDGI) formed by shear flow-induced self-assembly provides the restricted domains wherein monomers undergo polymerization to form a hydrogel network, producing structural color. The introduction of fluorescent monomer 6-acrylamidopicolinate (6APA) as a complexation site provides the possibility of fluorescent color formation. The hydrogel's angle-dependent structural color can be controlled by adjusting the crosslinking density and water content. Additionally, the fluorescence color can be modulated by adjusting the ratio of lanthanide ions. Information of dual-mode can be displayed separately in different channels and synergistically overlayed to read the ultimate message. Thus, a multistage information encryption system based on this hydrogel is devised through the programed decryption process. This strategy holds tremendous potential as a platform for encrypting and safeguarding valuable and authentic information in the field of anti-counterfeiting.

Cephalopod-Inspired Chemical-Gated Hydrogel Actuation Systems for Information 3D-Encoding Display

Cephalopods evolve the acetylcholine-gated actuation control function of their skin muscles, which enables their dynamic/static multimode display capacities for achieving perfectly spatial control over the colors/patterns on every inch of skin. Reproduction of artificial analogs that exhibit similar multimodal display is essential to reach advanced information three-dimensional (3D) encoding with higher security than the classic 2D-encoding strategy, but remains underdeveloped. The core difficulty is how to replicate such chemical-gated actuation control function into artificial soft actuating systems. Herein, this work proposes to develop azobenzene-functionalized poly(acrylamide) (PAAm) hydrogel systems, whose upper critical solution temperature (UCST) type actuation responsiveness can be intelligently programmed or even gated by the addition of hydrophilic α-cyclodextrin (α-CD) molecules for reversible association with pendant azobenzene moieties via supramolecular host-guest interactions. By employing such α-CD-gated hydrogel actuator as an analogue of cephalopods' skin muscle, biomimetic mechanically modulated multicolor fluorescent display systems are designed, which demonstrate a conceptually new α-CD-gated "thermal stimulation-hydrogel actuation-fluorescence output" display mechanism. Consequently, high-security 3D-encoding information carriers with an unprecedented combination of single-input multiple-output, dynamic/static dual-mode and spatially controlled display capacities are achieved. This bioinspired strategy brings functional-integrated features for artificial display systems and opens previously unidentified avenues for information security.

Finely manipulating room temperature phosphorescence by dynamic lanthanide coordination toward multi-level information security

Room temperature phosphorescence materials have garnered significant attention due to their unique optical properties and promising applications. However, it remains a great challenge to finely manipulate phosphorescent properties to achieve desirable phosphorescent performance on demand. Here, we show a feasible strategy to finely manipulate organic phosphorescent performance by introducing dynamic lanthanide coordination. The organic phosphors of terpyridine phenylboronic acids possessing excellent coordination ability are covalently embedded into a polyvinyl alcohol matrix, leading to ultralong organic room temperature phosphorescence with a lifetime of up to 0.629 s. Notably, such phosphorescent performance, including intensity and lifetime, can be well controlled by varying the lanthanide dopant. Relying on the excellent modulable performance of these lanthanide-manipulated phosphorescence films, multi-level information encryption including attacker-misleading and spatial-time-resolved applications is successfully demonstrated with greatly improved security level. This work opens an avenue for finely manipulating phosphorescent properties to meet versatile uses in optical applications.

Soft multi-layer actuators integrated with the functions of electrical energy harvest and storage

Soft multi-layer actuators are smart, lightweight, and flexible, which can be used in a wide range of fields such as artificial muscles, advanced medical devices, and wearable devices. The research on the actuation property of the soft actuators has made significant progress, paving the way for the controllable motions of the actuators. However, compared with the intelligence and adaptability of life in nature, these actuators still have the problem of insufficient intelligence. The phenomenon is reflected in a lack of continuous supply of energy. Therefore, it has become a development trend to combine functions such as energy harvesting, storage, and conversion with actuators to build intelligent actuators. This concept presents a synopsis of the advancements made in soft actuators that have been coupled with the capabilities of electrical energy harvesting and storage. The design concepts and typical applications of this soft smart actuators are introduced in detail. Finally, the future research directions and applications of smart actuators are prospected from our perspective.

Stimulus-responsive polymer materials toward multi-mode and multi-level information anti-counterfeiting: recent advances and future challenges

Information storage and security is one of the perennial hot issues in society, while the further advancements of related chemical anti-counterfeiting systems remain a formidable challenge. As emerging anti-counterfeiting materials, stimulus-responsive polymers (SRPs) have attracted extensive attention due to their unique stimulus-responsiveness and charming discoloration performance. At the same time, single-channel decryption technology with low-security levels has been unable to effectively prevent information from being stolen or mimicked. As a result, it would be of great significance to develop SRPs with multi-mode and multi-level anti-counterfeiting characteristics. This study summarizes the latest achievements in advance anti-counterfeiting strategies based on SRPs, including multi-mode anti-counterfeiting (static information) and multi-level anti-counterfeiting (dynamic information). In addition, the promising applications of such materials in anti-counterfeiting labels, identification platforms, intelligent displays, and others are briefly reviewed. Finally, the challenges and opportunities in this emerging field are discussed. This review serves as a useful resource for manipulating SRP-based anti-counterfeiting materials and creating cutting-edge information security and encryption systems.

Biomimetic 3D Color-Changing Hydrogel Actuators Constructed Based on Soft Permeable Photonic Crystals

The integration of photonic crystals and self-shaping actuators is a promising method for constructing powerful biomimetic color-changing actuators. The major barrier is that common photonic crystals generally block the transfer/orientation of monomers/fillers and hence hinder the formation of heterogeneous structures for programmed 3D deformations as well as degrade the deformation capacity and mechanical properties of actuators. Herein, we present the construction of complex and strong 3D color-changing hydrogel actuators by asymmetric photolithography based on soft, permeable photonic crystals. The soft permeable photonic crystals are assembled by hydrogel microspheres with an ultralow volume fraction. During the asymmetric photolithography, the monomers in precursor solutions can thus transfer freely to generate heterogeneous microstructures, spatially patterned internal stresses, and interpenetrating networks for programming the deformation trajectories and initial 3D configurations and enhancing mechanical properties of actuators. Various 3D color-changing hydrogel actuators (e.g., flower and scroll painting) are constructed for applications such as information encryption and display.

Conventional Non-Fluorescent Polymers: Unconventional Security Inks for Data Storage and Multidimensional Photonic Cryptography

Traditional security inks relying on fluorescent/phosphorescent molecules are facing increasing risks of forgery or tampering due to their simple readout scheme (i.e., UV-light irradiation) and the advancement of counterfeiting technologies. In this work, a multidimensional data-encryption method based on non-fluorescent polymers via a "lock-key" mechanism is developed. The non-fluorescent invisible polymer inks serve as the "lock" for data-encryption, while the anti-rigidochromic fluorophores that can distinctively light up the polymer inks with programed emissions are "keys" for decryption. The emission of decrypted data is prescribed by polymer chemical structure, molecular weight, topology, copolymer sequence, and phase structure, and shows distinct intensity, wavelength, and chirality compared with the intrinsic emission of fluorophores. Therefore, the data is triply encrypted and naturally gains a high-security level, e.g., only one out of 20 000 keys can access the only correct readout from 40 000 000 possible outputs in a three-polymers-based data-encryption matrix. Note that fluorophores lacking anti-rigidochrimism cannot selectively light up the inks and fail in data-decryption. Further, the diverse topologies, less well-defined structures, and random-coiled shapes of polymers make it impossible for them to be imitated. This work offers a new design for security inks and boosts data security levels beyond the reach of conventional fluorescent inks.

An Adaptive Multispectral Mechano-Optical System for Multipurpose Applications

Mechano-optical systems with on-demand adaptability and a broad spectrum from the visible to microwave are critical for complex multiband electromagnetic (EM) applications. Most existing material systems merely have dynamic optical or microwave tunability because their EM wave response is strongly wavelength-dependent. Inspired by cephalopod skin, we develop an adaptive multispectral mechano-optical system based on bilayer acrylic dielectric elastomer (ADE)/silver nanowire (AgNW) films, which reconfigures the surface morphology between wrinkles and cracks via mechanical contraction and stretching. Such morphological evolution regulates the direct transmission/reflection and scattering behavior of visible-infrared light and simultaneously alters the conductive network in a AgNW film to influence its microwave characteristics. The designed system features switching between visible-infrared-microwave transparency and opacity, continuous regulation, wide spectral window (0.38-15.5 μm and 24,200-36,600 μm), excellent recyclability (500 times), and rapid response time (<1 s). These grant the system great potential as platforms for various promising applications such as smart windows, switchable EM devices, dynamic thermal management, adaptive visual stealth, and human motion detection.

Bioinspired HOF-based luminescent skin sensor with triple mechanochromism responses for the recognition and collection of human biophysical signals

It is promising to develop luminescent force-sensitive bionic skin sensor (FBSS) with multiple mechanochromism (MC) responses for the sensing and collection of human biophysical signals. Herein, four bilayer hydrogen-bonded organic framework (HOF)-based polydimethylsiloxane (PDMS) elastic films (1-4) with full-color MC responses are fabricated by doping various luminescent HOF materials (HOF-TJ-1, R, Y, and G) into different PDMS layers. 1-4 as luminescent FBSSs possess stretched-, bended-, and pressed-MC properties. In stretching and bending processes, the color-switching performances of 1-4 are from initial blue to red, yellow, and green, and 4 exhibits an increased blue emission. Under pressing strain of 0-40%, the blue emission of 1-4 is strengthened. In stretched-, bended-, and pressed-MC processes, 1-4 show ultralow detection limits and excellent recyclability with 6000, 20 000, and 10 000 times, respectively. The MC mechanisms in stretched, bent, and pressed processes are investigated in depth via finite element simulation. Moreover, three intelligent applications, such as finger motion sensing, hand gesture recognition, and tactile-enhanced palm information collection have been well realized based on luminescent MC responses of 1. This work provides the facile synthetic method to fabricate full-color HOF-based luminescent FBSSs, greatly expands the types of luminescent MC responses, and enriches the applications of luminescent FBSS.

Cholesteric Liquid Crystal Polymeric Coatings for Colorful Artificial Muscles and Motile Humidity Sensor Skin Integrated with Magnetic Composites

Structural colorful cholesterics show impressive susceptibility to external stimulation, leading to applications in electro/mechano-chromic devices. However, out-of-plane actuation of structural colorful actuators based on cholesterics and the integration with other stimulation remains underdeveloped. Herein, colorful actuators and motile humidity sensors are developed using humidity-responsive cholesteric liquid crystal networks (CLCNs) and magnetic composites. The developed colorful actuator can exhibit synergistic out-of-plane shape morphing and color change in response to humidity, with CLCNs as colorful artificial muscles. Through the integration with magnetic control, the motile sensor can be navigated to open and confined spaces with the aid of friction to detect local relative humidity. The integration of multi-stimulation actuation of cholesteric magnetic actuators will expand the research frontier of structural colorful actuators and motile sensors for confined spaces.

Mechanical tough and multicolor aggregation-induced emissive polymeric hydrogels for fluorescent patterning

Aggregation-induced emissive fluorogens (AIEgens) are promising building blocks for fluorescent polymeric hydrogels (FPHs) because intense fluorescence intensities are usually guaranteed by spontaneous aggregates of hydrophobic AIEgens in a hydrophilic polymer network. However, most AIE-active FPHs are single-color fluorescent and cannot display tunable emission colors. Additionally, efforts to produce mechanically strong AIE-active hydrogels have been largely ignored, restricting their potential uses. Herein, we present the synthesis of an AIE-active methyl picolinate-substituted 1,8-naphthalimide monomer (MP-NI) for fabricating mechanical tough and multicolor FPHs. Owing to the introduction of bulky and coordinative methyl picolinate group, these specially designed MP-NI molecules were forced to adopt propeller-shaped conformation that renders them with intense aggregation-induced blue emission. Moreover, the MP-NI moieties grafted in a hydrogel matrix can sensitize red and green fluorescence of Eu³⁺and Tb³⁺ via antenna effect. Consequently, multicolor fluorescent hydrogels that sustain a high stress of 1 MPa were obtained by chemically introducing MP-NI moieties into dually cross-linked alginate polymer networks with high-density metal (Ca²⁺/Tb³⁺/Eu³⁺) coordination and hydrogen bonding crosslinks. Their capacity to enable the writing of arbitrary multicolor fluorescent patterns using Eu³⁺/Tb³⁺ as inks were finally demonstrated, suggesting their potential uses for smart display and information encryption.

4D Direct Laser Writing of Submerged Structural Colors at the Microscale

Biomimetic stimuli-responsive structure colors (SCs) can improve the visualization and identification in the micro functional structure field such as information encryption/decryption and smart actuators. However, it is still challenging to develop the ability to 4D print arbitrary submerged colorful patterns with stimuli-responsive materials at the microscale. Herein, a hydrogel photoresist with feature resolution (98 nm) for the fabrication of 4D microscopic SCs by the femtosecond direct laser writing method is developed. The 4D printed woodpile SCs are grouped as pixel palettes with various laser parameters and they spanned almost the entire color space. The coloring mechanism of diffraction gratings is not only investigated by optics microscopy and spectroscopy but also supported by simulation. Moreover, the 4D printed hydrogel-integrated amphichromatic fish constructions and pixelated painting can visually discolor reversibly by regulating the solution pH. This finding promises an ideal coloring method for sensors, anti-counterfeiting labels, and transformable photonic devices.

Information-Storage Expansion Enabled by a Resilient Aggregation-Induced-Emission-Active Nanocomposite Hydrogel

Advanced materials with high performance and distinctive function are one of the main driving forces for the development of human society. The selection of appropriate materials and adequately utilizing their features to apply them in a specific area rationally are of great significance but remain challenging. Herein, an aggregation-induced emission (AIE)-active nanocomposite (NC) hydrogel is developed by introducing a pH-responsive AIE luminogen (AIEgen) into a Laponite XLS/polyacrylamide-based NC hydrogel (Laponite is a trademark of the company BYK Additives Ltd.). The AIEgen can protonate to interact with the negatively charged clay through the electrostatic interaction, which results in a drastic fluorescence enhancement due to the restriction of intramolecular motion by the rigid clay to the protonated AIEgen. This behavior facilitates the input of fluorescent information with a high contrast ratio in the hydrogel by acid stimulation. Moreover, by utilizing the excellent resilience of the hydrogel, hierarchically inputting and displaying the information in the original and stretched states of the hydrogel film is realized, which achieves information-storage expansion and dual-encryption via switching between stretching and restoring the film. This work showcases fully and synergistically utilizing the superiorities of various advanced materials to achieve superior applications and should guide the future development of advanced materials in emerging areas.

Reconfigurable Fluorescent Liquid Crystal Elastomers for Integrated Visual and Haptic Information Storage

The rapid advancements in information technology require new information storage and display materials. However, the development of on-demand information storage systems with multiple modes remains a significant challenge. As a pioneering approach, this study designed an integrated visual and haptic information storage and display using a reconfigurable fluorescent liquid crystal elastomer (FLCE) with dynamic covalent bonds. The FLCEs were fabricated in two steps of amine-acrylate aza-Michael addition and photopolymerization, and they simultaneously exhibited phototunable fluorescence caused by the reversible Z/E photoisomerization of the chromophores and a reprogrammable shape owing to the catalyst-free transesterification. In addition, we established various information storage and display modes featuring the characteristics of reversibly photoswitchable fluorescence, shape memory, and thermally reconfigurable shape with a reconfigurable FLCE system. Moreover, a strategy to display the information by incorporating both visual and haptic feedback is implemented for fulfilling the needs of the visually impaired and related users. Such reconfigurable FLCE systems will aid in the development of on-demand information storage, display, and protection devices.

Recent Progress in Smart Polymeric Gel-Based Information Storage for Anti-Counterfeiting

Information security protection has a tremendous impact on human life, social stability and national security, leading to the rapid development of anti-counterfeiting materials and related techniques. However, the traditional stored information on hard or dry media is often static and lacks functions, which makes it challenging to deal with increasing and powerful counterfeiting technologies. Modified intelligent polymeric gels exhibit color changes and shape morphing under external stimuli, which give them great potential for applications in information storage. This paper provides an overview of the latest progress in polymeric gel-based information storage materials in relation to counterfeiting. Following a brief introduction of anti-counterfeiting materials, the preparation methods for intelligent gels with adjustable colors (e.g., chemical colors and physical colors) and various encryption/decryption modes involving dimensions and diverse colors are outlined. Finally, the challenges and prospects for information storage and anti-counterfeiting based on smart gels are discussed.

Point-of-Care Immunoassay Based on a Multipixel Dual-Channel Pressure Sensor Array with Visual Sensing Capability of Full-Color Switching and Reliable Electrical Signals

The point-of-care (POC) method with affordability and portability for the sensitive detection of biological substances is an emerging topic in rapid disease screening and personalized medicine. In this work, we demonstrated a diverse responsive platform based on a dual-channel pressure sensor (DCPS). The DCPS had a multilayer flexible architecture consisting of a photonic hydrogel with chromatic transitions and a piezoresistive pressure sensor as the electrical data transmission unit, both of which had the property of pressure-induced mechanical stimulus feedback. By incorporating a platinum nanoparticles-labeled detection antibody (PtNPs-dAb) into the sandwich-type immunoreaction for the target carcinoembryonic antigen (CEA, as a model analyte), gas decomposition could be triggered by the addition of hydrogen peroxide (H₂O₂) to induce a significant increase under pressure in a closed chamber. Meanwhile, the DCPS enabled an accurate electrical signal output, and the photonic hydrogel converted spatiotemporal stimuli into eye-readable colorations with string brilliance. In this way, the target concentration could be quantificationally related to the electrical response and intuitively perceived through visible color alterations. Under optimal conditions, a sensitive determination of CEA was performed in a detectable range of 0.3-60 ng/mL with a limit of detection (LOD) of 0.13 ng/mL. In addition, the proposed protocol had satisfactory selectivity, accuracy, and reproducibility. Furthermore, an array-based immunoassay device was fabricated to conceptually validate its application potential in high-throughput biomedical detection and inspire a dual-signal POC diagnostic platform in a friendly way for resource-limited settings.

Touch-Responsive Hydrogel for Biomimetic Flytrap-Like Soft Actuator

Stimuli-responsive hydrogel is regarded as one of the most promising smart soft materials for the next-generation advanced technologies and intelligence robots, but the limited variety of stimulus has become a non-negligible issue restricting its further development. Herein, we develop a new stimulus of "touch" (i.e., spatial contact with foreign object) for smart materials and propose a flytrap-inspired touch-responsive polymeric hydrogel based on supersaturated salt solution, exhibiting multiple responsive behaviors in crystallization, heat releasing, and electric signal under touch stimulation. Furthermore, utilizing flytrap-like cascade response strategy, a soft actuator with touch-responsive actuation is fabricated by employing the touch-responsive hydrogel and the thermo-responsive hydrogel. This investigation provides a facile and versatile strategy to design touch-responsive smart materials, enabling a profound potential application in intelligence areas.

Spontaneous and Continuous Actuators Driven by Fluctuations in Ambient Humidity for Energy-Harvesting Applications

Self-oscillating soft actuators that enable spontaneous and continuous motion under an external stimulus with no human intervention have attracted extensive attention due to the great value of the realization of more sustainable and low-power-consumption actuators. However, the achievement of such actuators that collect chemical energy from the fluctuations in ambient humidity is still a great challenge. Here, an actuator film based on spiropyran@agarose (SP@AG) that can spontaneously and continuously collect chemical energy from the fluctuations in ambient humidity is developed. It is noteworthy that the SP@AG film has excellent self-oscillation behavior and a high oscillation amplitude (184°) under the size (40 × 8 mm) or load of 116 mg (about 5.2 times of the film weight). Moreover, on the basis of the self-oscillating motion, an energy conversion device is constructed by integrating the soft actuator with a piezoelectric PVDF film, which can spontaneously and continuously generate an output voltage of about 30 mV. Finally, a proof of concept for an "intelligent light-controllable window" that can open under humidity stimulus and change color under light is proposed herein. Overall, the self-oscillating actuator driven by fluctuations in ambient humidity shows immense potential in response to the atmospheric humidity of day-night rhythm and humid-energy-harvesting devices.

Mimicking Color-Changing Organisms to Enable the Multicolors and Multifunctions of Smart Fluorescent Polymeric Hydrogels

Fluorescent polymer hydrogels (FPHs) are of significant interest for diverse emerging applications such as visualized sensing, smart display, camouflaging skins, soft actuators/robots, because they can synergize the features of classic fluorescent polymers and hydrogels. With great efforts in the past decades, the major challenge in this field has been believed to be not whether a given FPH of interest can be prepared but how to fabricate robust FPHs with multicolor tunability and multifunctional synergy. Such materials will conceptually minimize the contribution of passive materials to the mass and size of the final system, holding great potential to facilitate multiple applications. To this end, one promising way is to learn from the Nature that has superb capability to forge delicate or sometimes beyond-imagination materials. Chameleons and cephalopods serve as typical examples, which are famous for not only diverse skin color adaptability under changing environmental demands, but also synergistic skin color and body gesture changes to communicate, warn, camouflage, etc. Biological studies revealed their structural color-changing capacity derives from different types of skin chromatophores and their rational multilayer arrangement in under-skin tissues. Besides, their superb ability to heterogeneously integrate soft tissues with disparate functions into topology-optimized architectures has led to various multifunctional performances. Such natural strategies, if replicated and implemented in artificial systems, would significantly benefit and advance the development of robust FPHs for various applications.In this Account, we summarizes the key advances of smart FPHs mainly achieved by our groups. We start by introducing the unique hierarchical multilayer structures of skin chromatophores in structural color-changing reptiles, followed by an in-depth discussion on how a rational integration of bioinspiration and man-made design makes it possible to largely expand the fluorescence color-changing range of smart FPHs to almost cover the whole visible spectrum. Then, to closely mimic the multifunctional behaviors of chameleons and cephalopods, we further develop efficient strategies to introduce supramolecular interactions or heterogeneously integrating smart FPHs with other soft materials with disparate functions, producing a number of multifunctional fluorescent polymeric hydrogel systems. These robust FPHs can find many frontier applications, including bioinspired synergistic color/shape switchable hydrogel actuators/robots, smart systems with on-demand fluorescent patterning capacities for displaying or information encryption, as well as robust chemosensors for important food or environmental analytes. We expect that the discussion presented in this Account would promote better understanding of the discoloration systems in nature, and advance the development of bioinspired color-changing materials.

Color-Tunable Fluorescent Hierarchical Nanoassemblies with Concentration-Encoded Emission

Cephalopods possess a dynamic coloration behavior to change their iridescence due to the concentration-induced optical properties of chromatophores and hierarchical assembly of reflectin. However, cephalopods rarely have iridescence in the darkfield. It would be interesting to develop color-tunable fluorescent hierarchical nanoassemblies with concentration-encoded emission. Herein, to construct the bioavailable fluorophore with dynamic coloration properties, a histidine-rich peptide is designed, which can self-assemble into hierarchical nanoassemblies stabilized by hydrogen bonds and π-π stacking interactions. The peptidyl nanoassemblies emit fluorescent iridescence, encompassing the blue to orange region due to the assembly-induced emission. The fluorescence of histidine-rich peptides is color-tunable and reversible, which can be dynamically controlled in a concentration-encoded mode. Due to the coloration ability of histidine-rich peptides, fluorescent polychromatic human cells are developed, highlighting its potential role as a fluorescent candidate for future applications such as bioimaging, implantable light-emitting diodes, and photochromic camouflage.

pH Oscillator-Driven Jellyfish-like Hydrogel Actuator with Dissipative Synergy between Deformation and Fluorescence Color Change

Development of soft actuators with complex practical functions is significant for imitating the behaviors of living organisms. However, it is still a challenge to fabricate artificial soft actuators with jellyfish-like synergistic deformation and fluorescence color change (SDFC) and autonomous dynamic behavior, but such a system could obviously endow the classic soft actuators with more functions. Herein, we proposed to utilize tetra(4-pyridylphenyl)ethylene (TPE-4N) luminogen with pH-responsive aggregation-induced emission (AIE) to fabricate the AIE active hydrogel, which could be further employed to obtain an anisotropic bilayer soft actuator based on strong interfacial adhesion with acrylic acid (AA) gels. Furthermore, artificial flower-shape actuators showing SDFC behaviors were demonstrated. On the basis of these findings, jellyfish-inspired autonomous gel actuators driven by a pH oscillator have been fabricated, in which periodical SDFC behaviors completely regulated by the system itself without repetitive on/off switches of external stimuli were well synchronized with the pH oscillator. The described combination of nonlinear chemistry and responsive hydrogels actuator opens pathways toward out-of-equilibrium SDFC devices with autonomous behavior useful for biomimetic fields.

Highly Plasticized Lanthanide Luminescence for Information Storage and Encryption Applications

The development of new storage media to meet the demands for diverse information storage scenarios is a great challenge. Here, a series of lanthanide-based luminescent organogels with ultrastrong mechanical performance and outstanding plasticity are developed for patterned information storage and encryption applications. The organogels possessing outstanding mechanical properties and tunable luminescent colors are prepared by electrostatic and coordinative interactions between natural DNA, synthetic ligands, and rare earth (RE) ions. The organogel-REs can be stretched by 180 times and show an ultrastrong breaking strength of 80 MPa. A series of applications with both information storage and encryption, such as self-information pattern, quick response (QR) code, and barcode, are successfully demonstrated by the organogel-REs. The developed information storage systems have various advantages of good processability, high stretchability, excellent stability, and versatile design of information patterns. Therefore, the organogel-RE-based information storage systems are suitable for applications under different scenarios, such as flexible devices under repeating rude operations. The advancements will enable the design and development of luminescent organogel-REs as information storage and encryption media for various scenarios.