Spider Silk-Inspired Artificial Fibers

Durability improvement strategies for wettable fog harvesting devices inspired by spider silk fibers: a review

Water scarcity is a persistent challenge, and in this case, the freshwater content in the air and water collection phenomena observed in nature provide ideas for fog harvesting. The fog-harvesting capabilities of natural spider silk have long attracted attention. Thus, researchers have undertaken significant efforts for the preparation of wettable biomimetic knotted fibers. However, the fragility of their chemical coating and the susceptibility of spun fibers to damage often present substantial challenges in the durability of fog harvesting equipment. Herein, from a bioengineering perspective, we review the improvement strategies for enhancing the mechanical properties of wettable biomimetic spider silk fibers based on the dense nanoconfined hydrogen-bond array crystalline regions and uniformly embedded amorphous regions of natural wettable spider silk fibers. These strategies aim to achieve high tensile strength, good fracture toughness, and corrosion resistance. Additionally, by incorporating UV inhibitors during spinning, the effects of sunlight can be mitigated or shielded, thereby greatly enhancing the mechanical durability of fog-harvesting devices under harsh realistic conditions.

Progress in Multiscale Modeling of Silk Materials

As a result of their hierarchical structure and biological processing, silk fibers rank among nature's most remarkable materials. The biocompatibility of silk-based materials and the exceptional mechanical properties of certain fibers has inspired the use of silk in numerous technical and medical applications. In recent years, computational modeling has clarified the relationship between the molecular architecture and emergent properties of silk fibers and has demonstrated predictive power in studies on novel biomaterials. Here, we review advances in modeling the structure and properties of natural and synthetic silk-based materials, from early structural studies of silkworm cocoon fibers to cutting-edge atomistic simulations of spider silk nanofibrils and the recent use of machine learning models. We explore applications of modeling across length scales: from quantum mechanical studies on model peptides, to atomistic and coarse-grained molecular dynamics simulations of silk proteins, to finite element analysis of spider webs. As computational power and algorithmic efficiency continue to advance, we expect multiscale modeling to become an indispensable tool for understanding nature's most impressive fibers and developing bioinspired functional materials.

Spider-silk inspired ultrafast alkali-induced molecular aggregation for 3D printing arbitrary tubular hydrogels

Fabricating tubular hydrogel models with arbitrary structural complexity and controllable diameters using an ultrafast, facile yet universal method is desirable for vascular prototypes yet still a great challenge. Herein, inspired by the denaturing ability of spider silks, a novel strategy to induce complexation via applying highly concentrated alkali into a polyvinyl alcohol/ionic liquid (PVA/IL) solution, i.e., alkali-induced molecular aggregation (AMA), is proposed to achieve such purpose. This strategy enables the rapid and facile fabrication of tubular hydrogel architectures with tunable diameters, controllable thicknesses, and excellent mechanical performance with a tensile strength of up to 1.1 MPa and stretchability exceeding 600%. Importantly, this novel strategy combined with 3D printing facilitates the rapid fabrication of a variety of precise tubular hydrogel models with connected cavity structures which are difficult to achieve using current methods. This ultrafast solidification strategy could also be extended to various alkalis, cations and anions to build different hydrogels, showcasing its versatility and universality. Hence, this strategy can be pioneering to rapidly fabricate complex three-dimensional and hollow enclosed hydrogel models for simulating endovascular interventional therapy.

Continuous Homogeneous Thin Liquid Film on a Single Cross-Shaped Profiled Fiber with High Off-Circularity: Toward Quick-Drying Fabrics

Quick-drying fabrics, renowned for their rapid sweat evaporation, have witnessed various applications in strenuous exercise. Profiled fiber textiles exhibit enhanced quick-drying performance, which is attributed to the excellent wicking effect within fibrous bundles, facilitating the rapid transport of sweat. However, the evaporation process is not solely influenced by macroscopic liquid transport but also by microscopic liquid spreading on the fibers where periodic liquid knots induced by spontaneous fluidic instability significantly reduce the evaporation area. Here, a cross-shaped profiled fiber with high off-circularity, featured as multiple concavities along the fibrous longitude-axis, which enables the formation of a homogeneous thin liquid film on a single fiber without any periodic liquid knots, is developed. The high off-circularity cross-sections help overcoming Plateau-Rayleigh instability by tuning the Laplace pressure difference, further facilitated by capillary flow along the concave surface. The homogeneous thin liquid film on a single fiber is responsible for maximizing the evaporation area, resulting in excellent overall evaporation capacity. Consequently, fabrics made from such fibers exhibit rapid evaporation behavior, with evaporation rates ≈50% higher than those of cylindrical fabrics. It is envisioned that profiled fibers may provide inspiration for the manipulating homogeneous liquid films for applications in fluid coatings and functional textiles.

Bioinspired Photoluminescent "Spider Web" as Ultrafast and Ultrasensitive Airflow-Acoustic Bimodal Sensor for Human-Computer Interaction and Intelligent Recognition

Nature provides massive biomimetic design inspiration for constructing structural materials with desired performances. Spider webs can perceive vibrations generated by airflow and acoustic waves from prey and transfer the corresponding information to spiders. Herein, by mimicking the perception capability and structure of a spider web, an ultrafast and ultrasensitive airflow-acoustic bimodal sensor (HOF-TCPB@SF) is developed based on the postfunctionalization of hydrogen-bonded organic framework (HOF-TCPB) on silk film (SF) through hydrogen bonds. The "spider web-like" HOF-TCPB@SF possesses light weight and high elasticity, endowing this airflow sensor with superior properties including an ultralow detection limit (DL, 0.0076 m s-1), and excellent repeatability (480 cycles). As an acoustic sensor, HOF-TCPB@SF exhibits ultrahigh sensitivity (105140.77 cps Pa-1 cm-2) and ultralow DL (0.2980 dB), with the greatest response frequency of 375 Hz and the ability to identify multiple sounds. Moreover, both airflow and acoustic sensing processes show an ultrafast response speed (40 ms) and multiangle recognition response (0-180°). The perception mechanisms of airflow and acoustic stimuli are analyzed through finite element simulation. This bimodal sensor also achieves real-time airflow monitoring, speech recognition, and airflow-acoustic interoperability based on human-computer interaction, which holds great promise for applications in health care, tunnel engineering, weather forecasting, and intelligent textiles.

Engineered Protein Fibers with Reinforced Mechanical Properties Via β-Sheet High-Order Assembly

Protein fibers are ideal alternatives to synthetic polymers due to their unique mechanical properties, biocompatibility, and sustainability. However, engineering biomimetic protein fibers with high mechanical properties remains challenging, particularly in mimicking the high molecular weight of natural proteins and regulating their complex hierarchical structures. Here, a modular design and multi-scale assembly strategy is developed to manufacture robust protein fibers using low- or medium-molecular-weight proteins. The distinct functional and structural properties of flexible, rigid, and cross-linked domains in modular proteins are skillfully harnessed. By regulating the ratio of rigid to flexible domains, the formation of high-order β-sheet crystals aligned along the fiber axis is promoted, enhancing both strength and toughness. Furthermore, the dynamic imine cross-linking network, formed by the aldehyde-amine condensation reaction of the cross-linked domains, further reinforces the protein fibers. Remarkably, fibers spun from modular proteins significantly smaller than natural spidroin exhibit outstanding mechanical properties, surpassing those of protein fibers with same or even higher molecular weights. This strategy offers a promising pathway for fabricating protein fibers suitable for diverse applications.

Chitin/Chitosan Nanofibers Toward a Sustainable Future: From Hierarchical Structural Regulation to Functionalization Applications

Owing to its multiple fascinating properties of renewability, biodegradability, biocompatibility, and antibacterial activity, chitin is expected to become a green cornerstone of next-generation functional materials. Chitin nanofibers, as building blocks, form multiscale hierarchical structures spanning nano- and macrolevels in living organisms, which pave the way for sophisticated functions. Therefore, from a biomimetic perspective, exploiting chitin nanofibers for use in multifunctional, high-performance materials is a promising approach. Here, we first summarize the latest advances in the multiscale hierarchical structure assembly mode of chitin and its derivative nanofibers, including top-down exfoliation and bottom-up synthesis. Subsequently, we emphasize the environmental impacts of these methods, which are crucial for whether chitin nanofibers can truly contribute to a more eco-friendly era. Furthermore, the latest progress of chitin nanofibers in environmental and medical applications is also discussed. Finally, the potential challenges and tailored solutions of chitin nanofibers are further proposed, covering raw material, structure, function, manufacturing, policies, etc.

Machine Learning-Assisted Gesture Sensor Made with Graphene/Carbon Nanotubes for Sign Language Recognition

Gesture sensors are essential to collect human movements for human-computer interfaces, but their application is normally hampered by the difficulties in achieving high sensitivity and an ultrawide response range simultaneously. In this article, inspired by the spider silk structure in nature, a novel gesture sensor with a core-shell structure is proposed. The sensor offers a high gauge factor of up to 340 and a wide response range of 60%. Moreover, the sensor combining with a deep learning technique creates a system for precise gesture recognition. The system demonstrated an impressive 99% accuracy in single gesture recognition tests. Meanwhile, by using the sliding window technology and large language model, a high performance of 97% accuracy is achieved in continuous sentence recognition. In summary, the proposed high-performance sensor significantly improves the sensitivity and response range of the gesture recognition sensor. Meanwhile, the neural network technology is combined to further improve the way of daily communication by sign language users.

Water-Responsive Self-Contractive Silk-Based Skin Anti-Aging Tensioners with Customizable Biofunctions

Skin anti-aging treatments have become increasingly popular. Currently, the prevalent treatment method involves implanting skin tension regulation threads (skin lifting threads) under the skin, and radiofrequency treatments. In this study, inspired by the natural supercontraction of spider silk, the molecular structure of silk fibroin fibers is modulated into an oriented configuration. This modification endows silk proteins with water-responsive self-contraction capabilities, leading to the development of innovative self-contracting silk-based skin tensioners (SSSTs). To align with clinical requirements, skin tension regulation materials are functionalized by testing for their self-contraction, near-infrared laser heating function, and bacteriostatic properties. The SSSTs exhibited remarkable self-contraction properties, drug-loading and sustained-release capabilities, notable antibacterial effects, controllable degradation, and good biocompatibility. Moreover, the near-infrared light heating function effectively increased subcutaneous temperature, demonstrating its potential for enhancing and prolonging skin lifting effects. Therefore, SSSTs can be applied for skin tension regulation to improve and delay skin aging. The results may pave the way for novel strategies in skin rejuvenation, with broad implications for the field of skin anti-aging.

Disentangling the Web: An Interdisciplinary Review on the Potential and Feasibility of Spider Silk Bioproduction

The remarkable material properties of spider silk, such as its high toughness and tensile strength combined with its low density, make it a highly sought-after material with myriad applications. In addition, the biological nature of spider silk makes it a promising, potentially sustainable alternative to many toxic or petrochemical-derived materials. Therefore, interest in the heterologous production of spider silk proteins has greatly increased over the past few decades, making recombinant spider silk an important frontier in biomanufacturing. This has resulted in a diversity of potential host organisms, a large space for sequence design, and a variety of downstream processing techniques and product applications for spider silk production. Here, we highlight advances in each of these technical aspects as well as white spaces therein, still ripe for further investigation and discovery. Additionally, industry landscaping, patent analyses, and interviews with Key Opinion Leaders help define both the research and industry landscapes. In particular, we found that though textiles dominated the early products proposed by companies, the versatile nature of spider silk has opened up possibilities in other industries, such as high-performance materials in automotive applications or biomedical therapies. While continuing enthusiasm has imbued scientists and investors alike, many technical and business considerations still remain unsolved before spider silk can be democratized as a high-performance product. We provide insights and strategies for overcoming these initial hurdles, and we highlight the importance of collaboration between academia, industry, and policy makers. Linking technical considerations to business and market entry strategies highlights the importance of a holistic approach for the effective scale-up and commercial viability of spider silk bioproduction.

Bio-Inspired Adaptive and Responsive Protein-Based Materials

In nature, the inherent adaptability and responsiveness of proteins play a crucial role in the survival and reproduction of organisms, enabling them to adjust to ever-changing environments. A comprehensive understanding of protein structure and function is essential for unraveling the complex biological adaptive processes, providing new insights for the design of protein-based materials in advanced fields. Recently, materials derived from proteins with specific properties and functions have been engineered. These protein-based materials, distinguished by their engineered adaptability and responsiveness, range from the nanoscale to the macroscale through meticulous control of protein structure. First, the review introduces the natural adaptability and responsiveness of proteins in organisms, encompassing biological adhesion and the responses of organisms to light, magnetic fields, and temperature. Next, it discusses the achievements in protein-engineered adaptability and adhesion through protein assembly and nanotechnology, emphasizing precise control over protein bioactivity. Finally, the review briefly addresses the application of protein engineering techniques and the self-assembly capabilities of proteins to achieve responsiveness in protein-based materials to humidity, light, magnetism, temperature, and other factors. We hope this review will foster a multidimensional understanding of protein adaptability and responsiveness, thereby advancing the interdisciplinary integration of biomedical science, materials science, and biotechnology.

Controlled Structural Relaxation of Aramid Nanofibers for Superstretchable Polymer Fibers with High Toughness and Heat Resistance

Polymer fibers that combine high toughness and heat resistance are hard to achieve, which, however, hold tremendous promise in demanding applications such as aerospace and military. This prohibitive design task exists due to the opposing property dependencies on chain dynamics because traditional heat-resistant materials with rigid molecular structures typically lack the mechanism of energy dissipation. Aramid nanofibers have received great attention as high-performance nanoscale building units due to their intriguing mechanical and thermal properties, but their distinct structural features are yet to be fully captured. We show that aramid nanofibers form nanoscale crimps during the removal of water, which primarily resides at the defect planes of pleated sheets, where the folding can occur. The precise control of such a structural relaxation can be realized by exerting axial loadings on hydrogel fibers, which allows the emergence of aramid fibers with varying angles of crimps. These crimped fibers integrate high toughness with heat resistance, thanks to the extensible nature of nanoscale crimps with rigid molecular structures of poly(p-phenylene terephthalamide), promising as a template for stable stretchable electronics. The tensile strength/modulus (392-944 MPa/11-29 GPa), stretchability (25-163%), and toughness (154-445 MJ/cm3) are achieved according to the degree of crimping. Intriguingly, a toughness of around 430 MJ/m3 can be maintained after calcination below the relaxation temperature (259 °C) for 50 h. Even after calcination at 300 °C for 10 h, a toughness of 310 MJ/m3 is kept, outperforming existing polymer materials. Our multiscale design strategy based on water-bearing aramid nanofibers provides a potent pathway for tackling the challenge for achieving conflicting property combinations.

Hybrid Micro-/Nanoprotein Platform Provides Endocrine-like and Extracellular Matrix-like Cell Delivery of Growth Factors

Protein materials are versatile tools in diverse biomedical fields. Among them, artificial secretory granules (SGs), mimicking those from the endocrine system, act as mechanically stable reservoirs for the sustained release of proteins as oligomeric functional nanoparticles. Only validated in oncology, the physicochemical properties of SGs, along with their combined drug-releasing and scaffolding abilities, make them suitable as smart topographies in regenerative medicine for the prolonged delivery of growth factors (GFs). Thus, considering the need for novel, safe, and cost-effective materials to present GFs, in this study, we aimed to biofabricate a protein platform combining both endocrine-like and extracellular matrix fibronectin-derived (ECM-FN) systems. This approach is based on the sustained delivery of a nanostructured histidine-tagged version of human fibroblast growth factor 2. The GF is presented onto polymeric surfaces, interacting with FN to spontaneously generate nanonetworks that absorb and present the GF in the solid state, to modulate mesenchymal stromal cell (MSC) behavior. The results show that SGs-based topographies trigger high rates of MSCs proliferation while preventing differentiation. While this could be useful in cell therapy manufacture demanding large numbers of unspecialized MSCs, it fully validates the hybrid platform as a convenient setup for the design of biologically active hybrid surfaces and in tissue engineering for the controlled manipulation of mammalian cell growth.

Scalable weaving of resilient membranes with on-demand superwettability for high-performance nanoemulsion separations

This study leverages the ancient craft of weaving to prepare membranes that can effectively treat oil/water mixtures, specifically challenging nanoemulsions. Drawing inspiration from the core-shell architecture of spider silk, we have engineered fibers, the fundamental building blocks for weaving membranes, that feature a mechanically robust core for tight weaving, coupled with a CO2-responsive shell that allows for on-demand wettability adjustments. Tightly weaving these fibers produces membranes with ideal pores, achieving over 99.6% separation efficiency for nanoemulsions with droplets as small as 20 nm. They offer high flux rates, on-demand self-cleaning, and can switch between sieving oil and water nanodroplets through simple CO2/N2 stimulation. Moreover, weaving can produce sufficiently large membranes (4800 cm2) to assemble a module that exhibits long-term stability and performance, surpassing state-of-the-art technologies for nanoemulsion separations, thus making industrial application a practical reality.

The venom and telopodal defence systems of the centipede Lithobius forficatus are functionally convergent serial homologues

BACKGROUND

Evolution of novelty is a central theme in evolutionary biology, yet studying the origins of traits with an apparently discontinuous origin remains a major challenge. Venom systems are a well-suited model for the study of this phenomenon because they capture several aspects of novelty across multiple levels of biological complexity. However, while there is some knowledge on the evolution of individual toxins, not much is known about the evolution of venom systems as a whole. One way of shedding light on the evolution of new traits is to investigate less specialised serial homologues, i.e. repeated traits in an organism that share a developmental origin. This approach can be particularly informative in animals with repetitive body segments, such as centipedes.

RESULTS

Here, we investigate morphological and biochemical aspects of the defensive telopodal glandular organs borne on the posterior legs of venomous stone centipedes (Lithobiomorpha), using a multimethod approach, including behavioural observations, comparative morphology, proteomics, comparative transcriptomics and molecular phylogenetics. We show that the anterior venom system and posterior telopodal defence system are functionally convergent serial homologues, where one (telopodal defence) represents a model for the putative early evolutionary state of the other (venom). Venom glands and telopodal glandular organs appear to have evolved from the same type of epidermal gland (four-cell recto-canal type) and while the telopodal defensive secretion shares a great degree of compositional overlap with centipede venoms in general, these similarities arose predominantly through convergent recruitment of distantly related toxin-like components. Both systems are composed of elements predisposed to functional innovation across levels of biological complexity that range from proteins to glands, demonstrating clear parallels between molecular and morphological traits in the properties that facilitate the evolution of novelty.

CONCLUSIONS

The evolution of the lithobiomorph telopodal defence system provides indirect empirical support for the plausibility of the hypothesised evolutionary origin of the centipede venom system, which occurred through functional innovation and gradual specialisation of existing epidermal glands. Our results thus exemplify how continuous transformation and functional innovation can drive the apparent discontinuous emergence of novelties on higher levels of biological complexity.

Bioinspired Mechanically Robust and Recyclable Hydrogel Microfibers Based on Hydrogen-Bond Nanoclusters

Mechanically robust hydrogel fibers have demonstrated great potential in energy dissipation and shock-absorbing applications. However, developing such materials that are recyclable, energy-efficient, and environmentally friendly remains an enormous challenge. Herein, inspired by spider silk, a continuous and scalable method is introduced for spinning a polyacrylamide hydrogel microfiber with a hierarchical sheath-core structure under ambient conditions. Applying pre-stretch and twist in the as-spun hydrogel microfibers results in a tensile strength of 525 MPa, a toughness of 385 MJ m-3, and a damping capacity of 99%, which is attributed to the reinforcement of hydrogen-bond nanoclusters within the microfiber matrix. Moreover, it maintains both structural and mechanical stability for several days, and can be directly dissolved in water, providing a sustainable spinning dope for re-spinning into new microfibers. This work provides a new strategy for the spinning of robust and recyclable hydrogel-based fibrous materials.

Structuring and Shaping of Mechanically Robust and Functional Hydrogels toward Wearable and Implantable Applications

Hydrogels possess unique features such as softness, wetness, responsiveness, and biocompatibility, making them highly suitable for biointegrated applications that have close interactions with living organisms. However, conventional man-made hydrogels are usually soft and brittle, making them inferior to the mechanically robust biological hydrogels. To ensure reliable and durable operation of biointegrated wearable and implantable devices, mechanical matching and shape adaptivity of hydrogels to tissues and organs are essential. Recent advances in polymer science and processing technologies have enabled mechanical engineering and shaping of hydrogels for various biointegrated applications. In this review, polymer network structuring strategies at micro/nanoscales for toughening hydrogels are summarized, and representative mechanical functionalities that exist in biological materials but are not easily achieved in synthetic hydrogels are further discussed. Three categories of processing technologies, namely, 3D printing, spinning, and coating for fabrication of tough hydrogel constructs with complex shapes are reviewed, and the corresponding hydrogel toughening strategies are also highlighted. These developments enable adaptive fabrication of mechanically robust and functional hydrogel devices, and promote application of hydrogels in the fields of biomedical engineering, bioelectronics, and soft robotics.

Spider-silk-inspired strong and tough hydrogel fibers with anti-freezing and water retention properties

Ideal hydrogel fibers with high toughness and environmental tolerance are indispensable for their long-term application in flexible electronics as actuating and sensing elements. However, current hydrogel fibers exhibit poor mechanical properties and environmental instability due to their intrinsically weak molecular (chain) interactions. Inspired by the multilevel adjustment of spider silk network structure by ions, bionic hydrogel fibers with elaborated ionic crosslinking and crystalline domains are constructed. Bionic hydrogel fibers show a toughness of 162.25 ± 21.99 megajoules per cubic meter, comparable to that of spider silks. The demonstrated bionic structural engineering strategy can be generalized to other polymers and inorganic salts for fabricating hydrogel fibers with broadly tunable mechanical properties. In addition, the introduction of inorganic salt/glycerol/water ternary solvent during constructing bionic structures endows hydrogel fibers with anti-freezing, water retention, and self-regeneration properties. This work provides ideas to fabricate hydrogel fibers with high mechanical properties and stability for flexible electronics.

Bacteria inhabiting spider webs enhance host silk extensibility

Spider silk is a promising material with great potential in biomedical applications due to its incredible mechanical properties and resistance to degradation of commercially available bacterial strains. However, little is known about the bacterial communities that may inhabit spider webs and how these microorganisms interact with spider silk. In this study, we exposed two exopolysaccharide-secreting bacteria, isolated from webs of an orb spider, to major ampullate (MA) silk from host spiders. The naturally occurring lipid and glycoprotein surface layers of MA silk were experimentally removed to further probe the interaction between bacteria and silk. Extensibility of major ampullate silk produced by Triconephila clavata that was exposed to either Microbacterium sp. or Novosphigobium sp. was significantly higher than that of silk that was not exposed to bacteria (differed by 58.7%). This strain-enhancing effect was not observed when the lipid and glycoprotein surface layers of MA silks were removed. The presence of exopolysaccharides was detected through NMR from MA silks exposed to these two bacteria but not from those without exposure. Here we report for the first time that exopolysaccharide-secreting bacteria inhabiting spider webs can enhance extensibility of host MA silks and silk surface layers play a vital role in mediating such effects.

In vitro and in vivo investigation of Argiope bruennichi spider silk-based novel biomaterial for medical use

As a natural and biocompatible material with high strength and flexibility, spider silk is frequently used in biomedical studies. In this study, the availability of Argiope bruennichi spider silk as a surgical suture material was investigated. The effects of spider silk-based and commercial sutures, with and without Aloe vera coating, on wound healing were evaluated by a rat dorsal skin flap model, postoperatively (7th and 14th days). Biochemical, hematological, histological, immunohistochemical, small angle x-ray scattering (SAXS) analyses and mechanical tests were performed. A. bruennichi silk did not show any cytotoxic effect on the L929 cell line according to MTT and LDH assays, in vitro. The silk materials did not cause any allergic reaction, infection, or systemic effect in rats according to hematological and biochemical analyses. A. bruennichi spider silk group showed a similar healing response to commercial sutures. SAXS analysis showed that the 14th-day applications of A. bruennichi spider silk and A. vera coated commercial suture groups have comparable structural results with control group. In conclusion, A. bruennichi spider silk is biocompatible in line with the parameters examined and shows a healing response similar to the commercial sutures commonly used in the skin.

Establishing superfine nanofibrils for robust polyelectrolyte artificial spider silk and powerful artificial muscles

Spider silk exhibits an excellent combination of high strength and toughness, which originates from the hierarchical self-assembled structure of spidroin during fiber spinning. In this work, superfine nanofibrils are established in polyelectrolyte artificial spider silk by optimizing the flexibility of polymer chains, which exhibits combination of breaking strength and toughness ranging from 1.83 GPa and 238 MJ m-3 to 0.53 GPa and 700 MJ m-3, respectively. This is achieved by introducing ions to control the dissociation of polymer chains and evaporation-induced self-assembly under external stress. In addition, the artificial spider silk possesses thermally-driven supercontraction ability. This work provides inspiration for the design of high-performance fiber materials.

Regenerated Fiber's Ideal Target: Comparable to Natural Fiber

The toughness of silk naturally obtained from spiders and silkworms exceeds that of all other natural and man-made fibers. These insects transform aqueous protein feedstocks into mechanically specialized materials, which represents an engineering phenomenon that has developed over millions of years of natural evolution. Silkworms have become a new research hotspot due to the difficulties in collecting spider silk and other challenges. According to continuous research on the natural spinning process of the silkworm, it is possible to divide the main aspects of bionic spinning into two main segments: the solvent and behavior. This work focuses on the various methods currently used for the spinning of artificial silk fibers to replicate natural silk fibers, providing new insights based on changes in the fiber properties and production processes over time.

High-strength and ultra-tough supramolecular polyamide spider silk fibers assembled via specific covalent and reversible hydrogen bonds

Achieving ultra-high tensile strength and exceptional toughness is a longstanding goal for structural materials. However, previous attempts using covalent and non-covalent bonds have failed, leading to the belief that these two properties are mutually exclusive. Consequently, commercial fibers have been forced to compromise between tensile strength and toughness, as seen in the differences between nylon and Kevlar. To address this challenge, we drew inspiration from the disparate tensile strength and toughness of nylon and Kevlar, both of which are polyamide fibers, and developed an innovative approach that combines specific intermolecular disulfide bonds and reversible hydrogen bonds to create ultra-strong and ultra-tough polyamide spider silk fibers. Our resulting Supramolecular polyamide spider silk, which has a maximum molecular weight of 1084 kDa, exhibits high tensile strength (1180 MPa) and extraordinary toughness (433 MJ/m3), surpassing Kevlar's toughness 8-fold. This breakthrough presents a new opportunity for the sustainable development of spider silk as an environmentally friendly alternative to synthetic commercial fibers, as spider silk is composed of amino acids. Future research could explore the use of these techniques and fundamental knowledge to develop other super materials in various mechanical fields, with the potential to improve people's lives in many ways. STATEMENT OF SIGNIFICANCE: • By emulating synthetic commercial fibers such as nylon and polyethylene, we have successfully produced supramolecular-weight polyamide spider silk fibers with a molecular weight of 1084 kDa through a unique covalent bond-mediated linear polymerization reaction of spider silk protein molecules. This greatly surpasses the previous record of a maximum molecular weight of 556 kDa. • We obtained supramolecular polyamide spider silk fibers with both high-tensile strength and toughness. The stress at break is 1180 MPa, and the toughness is 8 times that of kevlar, reaching 433 MJ/m3. • Our results challenge the notion that it is impossible to manufacture fibers with both ultra-high tensile strength and ultra-toughness, and provide theoretical guidance for developing environmentally friendly and sustainable structural materials that meet industrial needs.

Artificial structural proteins: Synthesis, assembly and material applications

Structural proteins have evolved over billions of years and offer outstanding mechanical properties, such as resilience, toughness and stiffness. Advances in modular protein engineering, polypeptide modification, and synthetic biology have led to the development of novel biomimetic structural proteins to perform in biomedical and military fields. However, the development of customized structural proteins and assemblies with superior performance remains a major challenge, due to the inherent limitations of biosynthesis, difficulty in mimicking the complexed macroscale assembly, etc. This review summarizes the approaches for the design and production of biomimetic structural proteins, and their chemical modifications for multiscale assembly. Furthermore, we discuss the function tailoring and current applications of biomimetic structural protein assemblies. A perspective of future research is to reveal how the mechanical properties are encoded in the sequences and conformations. This review, therefore, provides an important reference for the development of structural proteins-mimetics from replication of nature to even outperforming nature.

Dynamics of Nanocomposite Hydrogel Alignment during 3D Printing to Develop Tissue Engineering Technology

Taking inspiration from spider silk protein spinning, we developed a method to produce tough filaments using extrusion-based 3D bioprinting and salting-out of the protein. To enhance both stiffness and ductility, we have designed a blend of partially crystalline, thermally sensitive natural polymer gelatin and viscoelastic G-polymer networks, mimicking the components of spider silk. Additionally, we have incorporated inorganic nanoparticles as a rheological modifier to fine-tune the 3D printing properties. This self-healing nanocomposite hydrogel exhibits exceptional mechanical properties, biocompatibility, shear thinning behavior, and a well-controlled gelation mechanism for 3D printing.

Spider-Silk-like Fiber Mat-Covered Polypropylene Warp-Knitted Hernia Mesh for Inhibition of Fibrosis under Dynamic Environment

Hernia surgery is a widely performed procedure, and the use of a polypropylene mesh is considered the standard approach. However, the mesh often leads to complications, including the development of scar tissue that wraps around the mesh and causes it to shrink. Consequently, there is a need to investigate the relationship between the mesh and scar formation as well as to develop a hernia mesh that can prevent fibrosis. In this study, three different commercial polypropylene hernia meshes were examined to explore the connection between the fabric structure and mechanical properties. In vitro dynamic culture was used to investigate the mechanism by which the mechanical properties of the mesh in a dynamic environment affect cell differentiation. Additionally, electrospinning was employed to create polycaprolactone spider-silk-like fiber mats to achieve mechanical energy dissipation in dynamic conditions. These fiber mats were then combined with the preferred hernia mesh. The results demonstrated that the composite mesh could reduce the activation of fibroblast mechanical signaling pathways and inhibit its differentiation into myofibroblasts in dynamic environments.

Polymer Brushes and Surface Nanostructures: Molecular Design, Precise Synthesis, and Self-Assembly

For over two decades, polymer brushes have found wide applications in industry and scientific research. Now, polymer brush research has been a significant research focus in the community of polymer science. In this review paper, we give an introduction to the synthesis, self-assembly, and applications of one-dimensional (1D) polymer brushes on polymer backbones, two-dimensional (2D) polymer brushes on flat surfaces, and three-dimensional (3D) polymer brushes on spherical particles. Examples of the synthesis of polymer brushes on different substrates are provided. Studies on the formation of the surface nanostructures on solid surfaces are also reviewed in this article. Multicomponent polymer brushes on solid surfaces are able to self-assemble into surface micelles (s-micelles). If the s-micelles are linked to the substrates through cleavable linkages, the s-micelles can be cleaved from the substrates, and the cleaved s-micelles are able to self-assemble into hierarchical structures. The formation of the surface nanostructures by coassembly of polymer brushes and "free" polymer chains (coassembly approach) or polymerization-induced surface self-assembly approach, is discussed. The applications of the polymer brushes in colloid and biomedical science are summarized. Finally, perspectives on the development of polymer brushes are offered in this article.

Silk Bioconjugates: From Chemistry and Concept to Application

Medical silks have captured global interest. While silk sutures have a long track record in humans, silk bioconjugates are still in preclinical development. This perspective examines key advances in silk bioconjugation, including the fabrication of silk-protein conjugates, bioconjugated silk particles, and bioconjugated substrates to enhance cell-material interactions in two and three dimensions. Many of these systems rely on chemical modification of the silk biopolymer, often using carbodiimide and reactive ester chemistries. However, recent progress in enzyme-mediated and click chemistries has expanded the molecular toolbox to enable biorthogonal, site-specific conjugation in a single step when combined with recombinant silk fibroin tagged with noncanonical amino acids. This perspective outlines key strategies available for chemical modification, compares the resulting silk conjugates to clinical benchmarks, and outlines open questions and areas that require more work. Overall, this assessment highlights a domain of new sunrise capabilities and development opportunities for silk bioconjugates that may ultimately offer new ways of delivering improved healthcare.

Bioinspired nanoplatforms for human-machine interfaces: Recent progress in materials and device applications

The panoramic characteristics of human-machine interfaces (HMIs) have prompted the needs to update the biotechnology community with the recent trends, developments, and future research direction toward next-generation bioelectronics. Bioinspired materials are promising for integrating various bioelectronic devices to realize HMIs. With the advancement of scientific biotechnology, state-of-the-art bioelectronic applications have been extensively investigated to improve the quality of life by developing and integrating bioinspired nanoplatforms in HMIs. This review highlights recent trends and developments in the field of biotechnology based on bioinspired nanoplatforms by demonstrating recently explored materials and cutting-edge device applications. Section 1 introduces the recent trends and developments of bioinspired nanomaterials for HMIs. Section 2 reviews various flexible, wearable, biocompatible, and biodegradable nanoplatforms for bioinspired applications. Section 3 furnishes recently explored substrates as carriers for advanced nanomaterials in developing HMIs. Section 4 addresses recently invented biomimetic neuroelectronic, nanointerfaces, biointerfaces, and nano/microfluidic wearable bioelectronic devices for various HMI applications, such as healthcare, biopotential monitoring, and body fluid monitoring. Section 5 outlines designing and engineering of bioinspired sensors for HMIs. Finally, the challenges and opportunities for next-generation bioinspired nanoplatforms in extending the potential on HMIs are discussed for a near-future scenario. We believe this review can stimulate the integration of bioinspired nanoplatforms into the HMIs in addition to wearable electronic skin and health-monitoring devices while addressing prevailing and future healthcare and material-related problems in biotechnologies.

Spidroins under the Influence of Alcohol: Effect of Ethanol on Secondary Structure and Molecular Level Solvation of Silk-Like Proteins

Future sustainable materials based on designer biomolecules require control of the solution assembly, but also interfacial interactions. Alcohol treatments of protein materials are an accessible means to this, making understanding of the process at the molecular level of seminal importance. We focus here on the influence of ethanol on spidroins, the main proteins of silk. By large-scale atomistically detailed molecular dynamics (MD) simulations and interconnected experiments, we characterize the protein aggregation, secondary structure changes, molecular level origins of them, and solvation environment changes for the proteins, as induced by ethanol as a solvation additive. The MD and circular dichoroism (CD) findings jointly show that ethanol promotes ordered structure in the protein molecules, leading to an increase of helix content and turns but also increased aggregation, as revealed by dynamic light scattering (DLS) and light microscopy. The structural changes correlate at the molecular level with increased intramolecular hydrogen bonding. The simulations reveal that polar amino acids, such as glutamine and serine, are most influenced by ethanol, whereas glycine residues are most prone to be involved in the ethanol-induced secondary structure changes. Furthermore, ethanol engages in interactions with the hydrophobic alanine-rich regions of the spidroin, significantly decreasing the hydrophobic interactions of the protein with itself and its surroundings. The protein solutes also change the microstructure of water/ethanol mixtures, essentially decreasing the level of larger local clustering. Overall, the work presents a systematic characterization of ethanol effects on a widely used, common protein type, spidroins, and generalizes the findings to other intrinsically disordered proteins by pinpointing the general features of the response. The results can aid in designing effective alcohol treatments for proteins, but also enable design and tuning of protein material properties by a relatively controllable solvation handle, the addition of ethanol.

Spider Silk-Inspired Binder Design for Flexible Lithium-Ion Battery with High Durability

The development of flexible lithium-ion batteries (LIBs) imposes demands on energy density and high mechanical durability simultaneously. Due to the limited deformability of electrodes, as well as the flat and smooth surface of the metal current collectors, stable/durable/reliable contact between electrode materials and the current collectors remains a challenge, in particular, for electrodes with high loading mass and heavily deformed batteries. Binders play an essential role in binding particles of electrode materials and adhering them to current collectors. Herein, inspired by spider silk, a binder for flexible LIBs is developed, which equips a cross-linked supramolecular poly(urethane-urea) to the polyacrylic acid. The binder imparts super high elastic restorability originating from the meticulously engineered hydrogen-bonding segments as well as extraordinary adhesion. The developed binder provides excellent flexibility and intact electrode morphologies without disintegration even when the electrode is largely deformed, enabling a stable cycling and voltage output even when the batteries are put under tough dynamic deformation tests. The flexible LIBs exhibit a high energy density of 420 Wh L-1 , which is remarkably higher than reported numbers. The unique binder design is greatly promising and offers a valuable material solution for LIBs with high-loading mass and flexible designs.

Bioinspired "cage traps" for closed-loop lead management of perovskite solar cells under real-world contamination assessment

Despite the remarkable progress made in perovskite solar cells, great concerns regarding potential Pb contamination risk and environmental vulnerability risks associated with perovskite solar cells pose a significant obstacle to their real-world commercialization. In this study, we took inspiration from the ensnaring prey behavior of spiders and chemical components in spider web to strategically implant a multifunctional mesoporous amino-grafted-carbon net into perovskite solar cells, creating a biomimetic cage traps that could effectively mitigate Pb leakage and shield the external invasion under extreme weather conditions. The synergistic Pb capturing mechanism in terms of chemical chelation and physical adsorption is in-depth explored. Additionally, the Pb contamination assessment of end-of-life perovskite solar cells in the real-world ecosystem, including Yellow River water and soil, is proposed. The sustainable closed-loop Pb management process is also successfully established involving four critical steps: Pb precipitation, Pb adsorption, Pb desorption, and Pb recycling. Our findings provide inspiring insights for promoting green and sustainable industrialization of perovskite solar cells.

Hydrogel fibers for wearable sensors and soft actuators

Owing to superior softness, wetness, responsiveness, and biocompatibility, bulk hydrogels are being intensively investigated for versatile functions in devices and machines including sensors, actuators, optics, and coatings. The one-dimensional (1D) hydrogel fibers possess the metrics from both the hydrogel materials and structural topology, endowing them with extraordinary mechanical, sensing, breathable and weavable properties. As no comprehensive review has been reported for this nascent field, this article aims to provide an overview of hydrogel fibers for soft electronics and actuators. We first introduce the basic properties and measurement methods of hydrogel fibers, including mechanical, electrical, adhesive, and biocompatible properties. Then, typical manufacturing methods for 1D hydrogel fibers and fibrous films are discussed. Next, the recent progress of wearable sensors (e.g., strain, temperature, pH, and humidity) and actuators made from hydrogel fibers is discussed. We conclude with future perspectives on next-generation hydrogel fibers and the remaining challenges. The development of hydrogel fibers will not only provide an unparalleled one-dimensional characteristic, but also translate fundamental understanding of hydrogels into new application boundaries.

Stimuli-responsive silk fibroin for on-demand drug delivery

Stimuli-responsive "smart" hydrogel biomaterials have attracted great attention in the biomedical field, especially in designing novel on-demand drug delivery systems. As a handful natural biomaterial approved by US Food and Drug Administration, silk fibroin (SF) has unique high temperature resistance as well as tunable structural composition. These properties make it one of the most ideal candidates for on-demand drug delivery. Meanwhile, recent advances in polymer modification and nanomaterials have fostered the development of various stimuli-responsive delivery systems. Here, we first review the recent advance in designing responsive SF-based delivery systems in different stimulus sources. These systems are able to release mediators in a desired manner in response to specific stimuli in active or passive manners. We then describe applications of these specially designed responsive delivery systems in wound healing, tumor therapy, as well as immunomodulation. We also discuss the future challenges and prospects of stimuli-responsive SF-based delivery systems.

Self-Healing of Recombinant Spider Silk Gel and Coating

Self-healing properties, originating from the natural healing process, are highly desirable for the fitness-enhancing functionality of biomimetic materials. Herein, we fabricated the biomimetic recombinant spider silk by genetic engineering, in which Escherichia coli (E. coli) was employed as a heterologous expression host. The self-assembled recombinant spider silk hydrogel was obtained through the dialysis process (purity > 85%). The recombinant spider silk hydrogel with a storage modulus of ~250 Pa demonstrated autonomous self-healing and high strain-sensitive properties (critical strain ~50%) at 25 °C. The in situ small-angle X-ray scattering (in situ SAXS) analyses revealed that the self-healing mechanism was associated with the stick-slip behavior of the β-sheet nanocrystals (each of ~2-4 nm) based on the slope variation (i.e., ~-0.4 at 100%/200% strains, and ~-0.9 at 1% strain) of SAXS curves in the high q-range. The self-healing phenomenon may occur through the rupture and reformation of the reversible hydrogen bonding within the β-sheet nanocrystals. Furthermore, the recombinant spider silk as a dry coating material demonstrated self-healing under humidity as well as cell affinity. The electrical conductivity of the dry silk coating was ~0.4 mS/m. Neural stem cells (NSCs) proliferated on the coated surface and showed a 2.3-fold number expansion after 3 days of culture. The biomimetic self-healing recombinant spider silk gel and thinly coated surface may have good potential in biomedical applications.

Aqueous spinning of robust, self-healable, and crack-resistant hydrogel microfibers enabled by hydrogen bond nanoconfinement

Robust damage-tolerant hydrogel fibers with high strength, crack resistance, and self-healing properties are indispensable for their long-term uses in soft machines and robots as load-bearing and actuating elements. However, current hydrogel fibers with inherent homogeneous structure are generally vulnerable to defects and cracks and thus local mechanical failure readily occurs across fiber normal. Here, inspired by spider spinning, we introduce a facile, energy-efficient aqueous pultrusion spinning process to continuously produce stiff yet extensible hydrogel microfibers at ambient conditions. The resulting microfibers are not only crack-insensitive but also rapidly heal the cracks in 30 s by moisture, owing to their structural nanoconfinement with hydrogen bond clusters embedded in an ionically complexed hygroscopic matrix. Moreover, the nanoconfined structure is highly energy-dissipating, moisture-sensitive but stable in water, leading to excellent damping and supercontraction properties. This work creates opportunities for the sustainable spinning of robust hydrogel-based fibrous materials towards diverse intelligent applications.

Biological Materials Processing: Time-Tested Tricks for Sustainable Fiber Fabrication

There is an urgent need to improve the sustainability of the materials we produce and use. Here, we explore what humans can learn from nature about how to sustainably fabricate polymeric fibers with excellent material properties by reviewing the physical and chemical aspects of materials processing distilled from diverse model systems, including spider silk, mussel byssus, velvet worm slime, hagfish slime, and mistletoe viscin. We identify common and divergent strategies, highlighting the potential for bioinspired design and technology transfer. Despite the diversity of the biopolymeric fibers surveyed, we identify several common strategies across multiple systems, including: (1) use of stimuli-responsive biomolecular building blocks, (2) use of concentrated fluid precursor phases (e.g., coacervates and liquid crystals) stored under controlled chemical conditions, and (3) use of chemical (pH, salt concentration, redox chemistry) and physical (mechanical shear, extensional flow) stimuli to trigger the transition from fluid precursor to solid material. Importantly, because these materials largely form and function outside of the body of the organisms, these principles can more easily be transferred for bioinspired design in synthetic systems. We end the review by discussing ongoing efforts and challenges to mimic biological model systems, with a particular focus on artificial spider silks and mussel-inspired materials.

Polymer Complex Fiber: Property, Functionality, and Applications

Polymer complex fibers (PCFs) are a novel kind of fiber material processed from polymer complexes that are assembled through noncovalent interactions. These can realize the synergy of functional components and miscibility on the molecular level. The dynamic character of noncovalent interactions endows PCFs with remarkable properties, such as reversibility, stimuli responsiveness, self-healing, and recyclability, enabling them to be applied in multidisciplinary fields. The objective of this article is to provide a review of recent progress in the field of PCFs. The classification based on chain interactions will be first introduced followed by highlights of the fabrication technologies and properties of PCFs. The effects of composition and preparation method on fiber properties are also discussed, with some emphasis on utilizing these for rational design. Finally, we carefully summarize recent advanced applications of PCFs in the fields of energy storage and sensors, water treatment, biomedical materials, artificial actuators, and biomimetic platforms. This review is expected to deepen the comprehension of PCF materials and open new avenues for developing PCFs with tailor-made properties for advanced application.

A molecular atlas reveals the tri-sectional spinning mechanism of spider dragline silk

The process of natural silk production in the spider major ampullate (Ma) gland endows dragline silk with extraordinary mechanical properties and the potential for biomimetic applications. However, the precise genetic roles of the Ma gland during this process remain unknown. Here, we performed a systematic molecular atlas of dragline silk production through a high-quality genome assembly for the golden orb-weaving spider Trichonephila clavata and a multiomics approach to defining the Ma gland tri-sectional architecture: Tail, Sac, and Duct. We uncovered a hierarchical biosynthesis of spidroins, organic acids, lipids, and chitin in the sectionalized Ma gland dedicated to fine silk constitution. The ordered secretion of spidroins was achieved by the synergetic regulation of epigenetic and ceRNA signatures for genomic group-distributed spidroin genes. Single-cellular and spatial RNA profiling identified ten cell types with partitioned functional division determining the tri-sectional organization of the Ma gland. Convergence analysis and genetic manipulation further validated that this tri-sectional architecture of the silk gland was analogous across Arthropoda and inextricably linked with silk formation. Collectively, our study provides multidimensional data that significantly expand the knowledge of spider dragline silk generation and ultimately benefit innovation in spider-inspired fibers.

Patterned Duplex Fabric Based on Genetically Modified Spidroin for Smart Wound Management

The treatment of diabetic wounds remains a great challenge for the medical community. Here, a smart patterned DNA double helix (duplex)-like fabric based on genetically modified spider silk protein (PDF-S) which is inspired by soft plant tendrils, is proposed for diabetic wound treatment. Benefiting from spider silk protein (spidroin); PDF-S is equipped with high strength; high toughness, and excellent biocompatibility. Notably, the fabric crimped through the biomimetic DNA double-helix-like structure can effectively adapt to tensile impact and the maximum stretch rate reaches 1500%. A pattern-based microfluidic channel of PDF-S allowed wound secretion to flow spontaneously through the channel. Meanwhile; due to the optical properties of the introduced photonic crystal structure; PDF-S is equipped with fluorescence enhancement properties; enabling PDF-S to display color-sensitive behavior suitable for wound monitoring and guiding clinical treatment. In addition, to enable sensitive motion monitoring, microelectronic circuits are integrated on the surface of the PDF-S. These unique material features suggest that this study will lead to a new generation of biomimetic artificial spider silk materials for design and application in the biomedical field.

Molecularly Engineered Protein Glues with Superior Adhesion Performance

Naturally inspired proteins are investigated for the development of bioglues that combine adhesion performance and biocompatibility for biomedical applications. However, engineering such adhesives by rational design of the proteins at the molecular level is rarely reported. Herein, it is shown that a new generation of protein-based glues is generated by supramolecular assembly through de novo designed structural proteins in which arginine triggers robust liquid-liquid phase separation. The encoded arginine moieties significantly strengthen multiple molecular interactions in the complex, leading to ultrastrong adhesion on various surfaces, outperforming many chemically reacted and biomimetic glues. Such adhesive materials enable quick visceral hemostasis in 10 s and outstanding tissue regeneration due to their robust adhesion, good biocompatibility, and superior antibacterial capacity. Remarkably, their minimum inhibitory concentrations are orders of magnitude lower than clinical antibiotics. These advances offer insights into molecular engineering of de novo designed protein glues and outline a general strategy to fabricate mechanically strong protein-based materials for surgical applications.

Bio-Inspired 4D Printing of Dynamic Spider Silks

Spider silks exhibit excellent mechanical properties and have promising application prospects in engineering fields. Because natural spider silk fibers cannot be manufactured on a large scale, researchers have attempted to fabricate bio-inspired spider silks. However, the fabrication of bio-inspired spider silks with dynamically tunable mechanical properties and stimulation–response characteristics remains a challenge. Herein, the 4D printing of shape memory polyurethane is employed to produce dynamic bio-inspired spider silks. The bio-inspired spider silks have two types of energy-absorbing units that can be adjusted, one by means of 4D printing with predefined nodes, and the other through different stimulation methods to make the bio-inspired spider silks contract and undergo spiral deformation. The shape morphing behaviors of bio-inspired spider silks are programmed via pre-stress assemblies enabled by 4D printing. The energy-absorbing units of bio-inspired spider silks can be dynamically adjusted owing to stress release generated with the stimuli of temperature or humidity. Therefore, the mechanical properties of bio-inspired spider silks can be controlled to change dynamically. This can further help in developing applications of bio-inspired spider silks in engineering fields with dynamic changes of environment.

Complexity of Spider Dragline Silk

The tiny spider makes dragline silk fibers with unbeatable toughness, all under the most innocuous conditions. Scientists have persistently tried to emulate its natural silk spinning process using recombinant proteins with a view toward creating a new wave of smart materials, yet most efforts have fallen short of attaining the native fiber’s excellent mechanical properties. One reason for these shortcomings may be that artificial spider silk systems tend to be overly simplified and may not sufficiently take into account the true complexity of the underlying protein sequences and of the multidimensional aspects of the natural self-assembly process that give rise to the hierarchically structured fibers. Here, we discuss recent findings regarding the material constituents of spider dragline silk, including novel spidroin subtypes, nonspidroin proteins, and possible involvement of post-translational modifications, which together suggest a complexity that transcends the two-component MaSp1/MaSp2 system. We subsequently consider insights into the spidroin domain functions, structures, and overall mechanisms for the rapid transition from disordered soluble protein into a highly organized fiber, including the possibility of viewing spider silk self-assembly through a framework relevant to biomolecular condensates. Finally, we consider the concept of “biomimetics” as it applies to artificial spider silk production with a focus on key practical aspects of design and evaluation that may hopefully inform efforts to more closely reproduce the remarkable structure and function of the native silk fiber using artificial methods.