Bioinspired Amyloid Fibril-Based Hydrogel with Engineering Programable Functionalities for Diverse Applications

Natural proteins display organized hierarchical structures and tailored functionalities that cannot be achieved by synthetic approaches, highlighting the increased interest in developing protein-based materials. Protein self-assembly allows fabricating sophisticated supramolecular structures from relatively simple building blocks, a strategy naturally employed by amyloid proteins and intrinsically disordered proteins. However, the design of self-assembled bioinspired materials with multi functionalities is still challenging. Inspired by the natural self-assembly proteins (such as mussel foot proteins and amyloid proteins), a temperature-inducible engineering programable hydrogel-like amyloid nanostructure is developed by using a genetically modular fusion approach. The resulting hydrogel-like assemblies display outstanding adhesive capacity, high stability, and broad substrate universality. The employed SpyCatcher/SpyTag system allows modifying the hydrogel-like assemblies with any functional proteins of interest. Owing to their strong adhesive capacity and functional flexibility, such amyloid fibril-based hydrogel shows advantages in the immobilization of diverse enzymes for highly efficient biocatalysis, fabrication of multi-layered functional coatings, and construction of functionalized 3D scaffold for cell culture. Overall, a modular and straightforward approach is established to obtain a genetically programable nanostructure platform. The novel hydrogel-like assemblies described here may be potentially applied to but not limited to synthetic biology, surface/interface engineering, and tissue engineering.     

Electrosprayed Enzyme Coatings as Bioinspired Alternatives to Bioceramic Coatings for Orthopedic and Oral Implants

The biological performance of orthopedic and oral implants can be significantly improved by functionalizing the non‐physiological metallic implant surface through the application of biologically active coatings. In this paper, a cost‐effective alternative to traditional biomedical coatings for bone substitution through exploitation of the specific advantages of the electrospray deposition technique for the immobilization of the enzyme alkaline phosphatase (ALP) onto the implant surface is presented. Since ALP increases the local inorganic phosphate concentration required for physiological mineralization of hard tissues, ALP coatings will enable enzyme‐mediated mineralization onto titanium surfaces. To evaluate the bone‐bioactive capacity of the ALP‐coated titanium surface, soaking experiments are performed. Although the purely inorganic so‐called simulated body fluid is the standard in vitro procedure for predictive studies on potential bone bonding in vivo, an alternative testing solution is proposed that also contains organic phosphates (cell culture medium supplemented with the organic β‐b;‐glycerophosphate (β‐b;‐GP) and serum proteins), thereby resembling the in vivo conditions more closely. Under these physiological conditions, the electrosprayed ALP coatings accelerated mineralization onto the titanium surface as compared to noncoated implant material by means of enzymatic pathways. Therefore, this novel approach toward implant fixation holds significant promise.     

Biocatalytic Nanoscale Coatings Through Biomimetic Layer‐by‐Layer Mineralization

Recent insight into the molecular mechanisms of biological mineral formation (biomineralization) has enabled biomimetic approaches for the synthesis of functional organic‐inorganic hybrid materials under mild reaction conditions. Here we describe a novel method for enzyme immobilization in thin (nanoscale) conformal mineral coatings using biomimetic layer‐by‐layer (LbL) mineralization. The method utilizes a multifunctional molecule comprised of a naturally‐occurring peptide, protamine (PA), covalently bound to the redox enzyme Glucose oxidase (GOx). PA mimics the mineralizing properties of biomolecules involved in silica biomineralization in diatoms, and its covalent attachment to GOx does not interfere with the catalytic activity. Highly efficient and stable incorporation of this modified enzyme (GOx‐PA) into nanoscale layers (～5–7 nm thickness) of Ti‐O and Si‐O is accomplished during protamine‐enabled LbL mineralization on silica spheres. Depending on the layer location of the enzyme and the type of mineral (silica or titania) within which the enzyme is incorporated, the resulting multilayer biocatalytic hybrid materials exhibit between 20–100% of the activity of the free enzyme in solution. Analyses of kinetic properties (V_max, K_M) of the immobilized enzyme, coupled with characterization of physical properties of the mineral‐bearing layers (thickness, porosity, pore size distribution), indicates that the catalytic activities of the synthesized hybrid nanoscale coatings are largely determined by substrate diffusion rather than enzyme functionality. The GOx‐PA immobilized in these nanoscale layers is substantially stabilized against heat‐induced denaturation and largely protected from proteolytic attack. The method for enzyme immobilization described here enables, for the first time, the high yield immobilization and stabilization of enzymes within continuous, conformal, and nanoscale coatings through biomimetic LbL mineralization. This approach will likely be applicable to a wide variety of surfaces and functional biomolecules. The ability to synthesize thin (nanoscale) conformal enzyme‐loaded layers is of interest for numerous applications, including enzyme‐based biofuel cells and biosensors.     

Bioinspired Multifunctional Foam with Self‐Cleaning and Oil/Water Separation

Oil/water separation is a worldwide challenge. Learning from nature provides a promising approach for the construction of functional materials with oil/water separation. In this contribution, inspired by superhydrophobic self‐cleaning lotus leaves and porous biomaterials, a facile method is proposed to fabricate polyurethane foam with simultaneous superhydrophobicity and superoleophilicity. Due to its low density, light weight, and superhydrophobicity, the as‐prepared foam can float easily on water. Furthermore, the foam demonstrates super‐repellency towards corrosive liquids, self‐cleaning, and oil/water separation properties, possessing multifunction integration. We expect that this low‐cost process can be readily and widely adopted for the design of multifunctional foams for large‐area oil‐spill cleanup.     

Functional Coating of Porous Silica Microparticles with Native Biomembranes towards Portable Flow‐Through Biochemical Microreactors

In biological cells, various transmembrane enzymes function as highly effective chemical reactors confined in space with characteristic length scales of tens of nanometers to micrometer. However, it is still challenging to quantitatively confine membranes in compact reactor platforms without losing their biochemical functions. Here, a simple and straightforward strategy towards the fabrication of a new flow‐through reactor by the functional coating of porous silica microparticles with sarcoplasmic reticulum membranes is described. After a short incubation, the membranes achieve the homogeneous, full coverage of the particle surface, spanning across pores with the diameter of about 100 nm. By using the underlying pores as cavity reservoirs, transmembrane enzyme (Ca²⁺‐ATPase) in the membrane retains their capability of ATP hydrolysis. This enables us to confine 1.1 m² of native membranes containing a large amount of Ca²⁺‐ATPase (approx. 10 nmol) in a column‐packaged, flow‐through reactor with merely 1.8 mL volume, which cannot be achieved by the reconstitution of proteins in artificial lipid membranes or condensation of membranes in suspensions. The distinct functional levels corresponding to different reaction buffers can be reproduced even after many buffer exchanges over 14 days, confirming the stability and reproducibility of the membrane‐particle hybrid reactors.     

Unlocking the Latent Antimicrobial Potential of Biomimetically Synthesized Inorganic Materials

Inspired by biomineralization, biomimetic approaches utilize biomolecules and synthetic analogs to produce materials of controlled chemistry, morphology, and function under relatively benign conditions. A common characteristic of biological and biomimetic mineral‐forming processes is the generation of mineral/biomolecule nanocomposites. In this work, it is demonstrated that a facile chemical reaction may be utilized to halogenate the nitrogen‐containing moieties of the organics entrapped within bio‐inorganic composites to yield halamine compounds. This process provides rapid and potent bactericidal activity to biomimetically and biologically produced materials that otherwise lack such functionality. Additionally, bio‐inorganic composites containing the chlorinated peptide protamine are effective in rapidly neutralizing Bacillus spores (≥99.97% reduction in colony forming units within 10 min). The straightforward nature of the described process, and the efficacy of halamine compounds in neutralizing biological and chemical agents, provide new applicability to biogenic and biomimetic materials.     

A Universal Coating Strategy for Controllable Functionalized Polymer Surfaces

Development of a universal and stable surface coating, irrespective of surface chemistry or material characteristics, is highly desirable but has proved to be extremely challenging. Conventional coating strategies including the commonly used catechol surface coating are limited to either a certain type of substrates or weak and unreliable surface bonding. Here, a simple, robust, and universal surface coating method capable for attaching any stimuli‐responsive glycidyl methacrylate (GMA)‐based copolymer, consisting of one surface‐adhesive moiety of epoxy groups and one stimuli‐responsive moiety, to any type of hydrophobic and hydrophilic surfaces via a one‐step ring‐opening reaction is proposed and demonstrated. The resultant GMA‐based copolymers are not only strongly adhered on different substrates (e.g., silicon, polypropylene, polyvinyl chloride, indium tin oxide, polyethylene terephthalate, aluminum, glass, polydimethylsiloxane, and even polyvinylidene fluoride with low surface energy), but also are possessed distinct thermal‐, pH‐, and salt‐responsive functions of bacterial killing, bacterial releasing, tunable multicolor fluorescence emission, and heavy metal detection. This coating method is also compatible with the directional quaternization of GMA‐based copolymers for further improving surface adhesion and functionality. This study provides a simple yet universal coating method to solve the long‐standing challenge of robust integration of stimuli‐responsive polymers with strong adhesion between various polymers and substrates.     

Stimuli‐Responsive Bioinspired Materials for Controllable Liquid Manipulation: Principles,Fabrication, and Applications

Many emerging interfacial technologies, such as self‐cleaning surfaces, oil/water separation, water collection, and microfluidics, are essentially liquid manipulation processes. In this regard, micro‐nanostructures of the living organisms are highly preferable, by virtue of the evolutionary pressure and the adaptation to the specific environments, to inspire the optimization of man‐made interfaces. With the increasing demands of modern life, research, and industry, intelligent materials with stimuli‐responsive liquid manipulation functions have gained substantial attention from interfacial scientists. This review introduces the recent progress in the development of stimuli‐responsive liquid‐manipulating materials with bioinspired structures and surface chemistry according to two classified manipulation modes: (i) smart manipulation of liquid wetting behaviors, including lyophobic/lyophilic and superlyophobic/superlyophilic, and (ii) smart manipulation of liquid motion behaviors, including coalescence, transportation, rolling/adhesion, and sliding/pinning. At the beginning of the presentation of each classification, the theoretical basis and the sources of inspiration are introduced comprehensively to ensure a better understanding. This review mainly focuses on the mechanisms, fabrication, and applications of the state‐of‐the‐art works related to smart and biomimetic liquid‐manipulating materials. Finally, conclusions and future prospects are provided, and the remaining problems and promising breakthroughs in fabricating large‐scale, cost‐effective, and efficient smart liquid‐manipulating materials are outlined.     

Bioinspired Highly Anisotropic,Ultrastrong and Stiff,and Osteoconductive Mineralized Wood Hydrogel Composites for Bone Repair

Anisotropic hydrogels mimicking the biological tissues with directional functions play essential roles in damage-tolerance, cell guidance and mass transport. However, conventional synthetic hydrogels often have an isotropic network structure, insufficient mechanical properties and lack of osteoconductivity, which greatly limit their applications for bone repair. Herein, inspired by natural bone and wood, a biomimetic strategy is presented to fabricate highly anisotropic, ultrastrong and stiff, and osteoconductive hydrogel composites via impregnation of biocompatible hydrogels into the delignified wood followed by in situ mineralization of hydroxyapatite (HAp) nanocrystals. The well-aligned cellulose nanofibrils endow the composites with highly anisotropic structural and mechanical properties. The strong intermolecular bonds of the aligned cellulose fibrils and hydrogel/wood interaction, and the reinforcing nanofillers of HAp enable the composites remarkable tensile strength of 67.8 MPa and elastic modulus of 670 MPa, three orders of magnitude higher than those of conventional alginate hydrogels. More importantly, the biocompatible hydrogel together with aligned HAp nanocrystals could effectively promote osteogenic differentiation in vitro and induce bone formation in vivo. The bone ingrowth into the hydrogel composite scaffold also yields good osteointegration. This study provides a low-cost, eco-friendly, feasible, and scalable approach for fabricating anisotropic, strong, stiff, hydrophilic, and osteoconductive hydrogel composites for bone repair.     

Bioinspired Artificial Eyes: Optic Components,Digital Cameras,and Visual Prostheses

The diverse vision systems found in nature can provide interesting design inspiration for imaging devices, ranging from optical subcomponents to digital cameras and visual prostheses, with more desirable optical characteristics compared to conventional imagers. The advantages of natural vision systems include high visual acuity, wide field of view, wavelength‐free imaging, improved aberration correction and depth of field, and high motion sensitivity. Recent advances in soft materials, ultrathin electronics, and deformable optoelectronics have facilitated the realization of novel processes and device designs that mimic biological vision systems. This review highlights recent progress and continued efforts in the research and development of bioinspired artificial eyes. At first, the configuration of two representative eyes found in nature: a single‐chambered eye and a compound eye, is explained. Then, advances in bioinspired optic components and image sensors are discussed in terms of materials, optical/mechanical designs, and integration schemes. Subsequently, novel visual prostheses as representative application examples of bioinspired artificial eyes are described.     

Bioinspired Structural Material Exhibiting Post‐Yield Lateral Expansion and Volumetric Energy Dissipation During Tension

Nature has inspired the design of improved synthetic materials that achieve superior and more efficient mechanical performance. Here microstructures inspired by the inner nacreous layer of seashells are designed and their mechanical properties including stiffness, strength, and energy dissipation are computed using micromechanical analysis. The hierarchical mineral/polymer microstructure can be tailored to achieve not only stiffness and strength, but also lateral plastic expansion during tension providing a volumetric energy dissipation mechanism.     

Bioinspired Tunable Structural Color Film with Janus Wettability and Interfacial Floatability towards Visible Water Quality Monitoring

Superwettability materials from existing natural creatures have been widely studied to enable artificial manufacture. Variable wettability states, especially Janus wettability, have attracted particular interest because of the applications in various intelligent systems. However, to date, most of these existing Janus wettability surfaces lack stimuli-response visualization, which requires the connection of electrical instruments to process and display external stimulus signals. Inspired by the functional performance of lotus leaf and Betta splendens, a multifunctional asymmetric film is designed by using the superhydrophobic/superhydrophilic binary cooperative strategy and tunable structural color feature. Thus, it is demonstrated that the Janus membrane could not only timely report the arrival of the environmental variables via directional migration induced by Marangoni effect, but also quantitively feedback the stimuli through visible structural color variations. These features indicate that the Janus wettability structural color film may open a potential chapter in designing and fabricating the multifunctional robotic environmental detector.     

Black Bioinks from Superstructured Carbonized Lignin Particles

A renewable source of carbon black is introduced by the processing of lignin from agro-forestry residues. Lignin side streams are converted into spherical particles by direct aerosolization followed by carbonization. The obtained submicron black carbon is combined with cellulose nanofibers, which act as a binder and rheology modifier, resulting in a new type of colloidal bioink. The bioinks are tested in handwriting and direct ink writing. After consolidation, the black bioinks display total light reflectance (%R) at least three times lower than commercial black inks (reduction from 12 to 4%R). A loading of up to 20% of nanofibers positively affects the cohesion of the dried bioink (1 to 16 MPa), with no significant reduction in light reflectance. This is a result of the superstructuring of the ink components, which disrupts particle packing, intensifies colloidal interactions, introduces light absorption, and non-reflective multiple scattering.     

A Bioinspired Polymer-Based Composite Displaying Both Strong Adhesion and Anisotropic Thermal Conductivity

The integration and functionality of high-power electronic architectures or devices require a high strength and good heat flow at the interface. However, simultaneously improving the interfacial bonding and phonon transport of polymers is challenging because of the tradeoff between the cross-linked flexible chains and high-quality crystalline structure. Here, a copolymer, poly(dopamine methacrylate-co-hydroxyethyl methacrylate [P(DMA-HEMA)] is designed and synthesized, inspired by the snail and mussel adhesion. The copolymer achievs a high surface adhesion up to 6.38 MPa owing to the synergistic effects of hydrogen bonds and mechanical interlocking. When the copolymer is introduced into vertically aligned carbon nanotubes (VACNTs), the catechol groups in P(DMA-HEMA) formed strong bonding with the nanotubes through π-π interactions at the interface. As a result, the P(DMA-HEMA)/VACNTs composite shows a high through-plane thermal conductivity (21.46 W m⁻¹ K⁻¹), an in-plane thermal conductivity that is 3.5 times higher than that of pristine VACNTs, and an extremely low thermal contact resistance (20.27 K mm² W⁻¹). Furthermore, the composite forms weld-free high-strength connections between two pieces of various metals to bridge directional thermal pathways. It also exhibits excellent interfacial heat transfer capability and high reliability even under zero-pressure conditions.     

Porous Polymer Films with Gradient‐Refractive‐Index Structure for Broadband and Omnidirectional Antireflection Coatings

Porous polymer films that can be employed for broadband and omnidirectional antireflection coatings are successfully shown. These films form a gradient‐refractive‐index structure and are achieved by spin‐coating the solution of a polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA)/PMMA blend onto an octadecyltrichlorosilane (OTS)‐modified glass substrate. Thus, a gradient distribution of PMMA domains in the vertical direction of the entire microphase‐separated film is obtained. After those PMMA domains are removed, a PS porous structure with an excellent gradient porosity ratio in the vertical direction of the film is formed. Glass substrates coated with such porous polymer film exhibit both broadband and omnidirectional antireflection properties because the refractive index increases gradually from the top to the bottom of the film. An excellent transmittance of >97% for both visible and near‐infrared (NIR) light is achieved in these gradient‐refractive‐index structures. When the incident angle is increased, the total transmittance for three different incident angles is improved dramatically. Meanwhile, the film possesses a color reproduction character in the visible light range.     

A Structure Self-Healing Li-Rich Cathode Achieved by Lithium Supplement of Li-Rich LLZO Coating

Lithium-rich manganese-based cathode materials (LLMO) are considered as the promising candidates for realizing high energy density lithium-ion batteries. However, the severe structure deterioration and capacity fading hinder their large-scale application. Herein, an innovative electrochemical lithium supplement strategy is put forward to inhibit the structure collapse and enhance the cycling stability of Lithium-rich manganese-based cathodes. Besides, combining with the superior Li-ion conductor Li_6.25La₃Zr₂Al_0.25O₁₂ (LLZAO), remarkable rate capability is achieved. As a result, a capacity retention of 95.7% after 300 cycles at 1.0 C (1.0 C = 200 mA g⁻¹), as well as a stable cycling at 5.0 C with discharge capacity of 136.9 mAh g⁻¹, are harvested. Moreover, the excess lithium ions in LLZAO mitigate the spinel-like phase transformation via inserting into the lithium layer and stabilizing the cathode structure. In addition, the lithium ions migration behavior in the elaborated cathode is thoroughly expounded and the correlation between diffusion kinetics and LLZAO is revealed. These findings boost the updating of LLMO and pave a new pathway for stabilizing LLMO structures.