Silk Research Articles

Biomimetic bilayer scaffold from Bombyx mori silk materials for small diameter vascular applications in tissue engineering.

Enhancing the biocompatibility and mechanical stability of small diameter vascular scaffolds remain significant challenges. To address this challenge, small-diameter tubular structures were electrospun from silk fibroin (SF) from silk textile industry discarded materials to generate bilayer scaffolds that mimic native blood vessels, but derived from a sustainable natural material resource. The inner layer was obtained by directly dissolving SF in formic acid, while the middle layer (SF-M) was achieved through aqueous concentration of the protein. Structural and biological properties of each layer as well as the bilayer were evaluated. The inner layer exhibited nano-scale fiber diameters and 57.9% crystallinity, and degradation rates comparable with the SF-M layer. The middle layer displayed micrometer-scale fibers diameters with an ultimate extension of about 274%. Both layers presented contact angles suitable for cell growth and cytocompatibility, while the bilayer material displayed an intermediate mechanical response and a reduced enzymatic degradation rate when compared to each individual layer. The bilayer material emulates many of the characteristics of native small-diameter vessels, thereby suggesting further studies towards in vivo opportunities.

Robust and washable silk fiber-based electrochemical biosensor for high-performance sensing of hydrogen peroxide

Wearable electronics, especially fiber-based biosensors, show promise in large-scale production and reusability compared with conventional wafer-based electronics. However, it is challenging to use wearable electronics, with less intensity and non-wash ability, to produce fiber-based biosensors for textiles. Here, a robust and washable Prussian blue (PB)-functionalized silk fiber (PB-SF) flexible electrode is reported. Modified cyanotype is successfully employed to immobilize PB nanoparticles (∼18.32 nm) onto silk fibers for hydrogen peroxide (H2O2) detection. The intrinsic mechanical properties of silk fibers are well maintained with slight increases in stress (∼10%) and strain (∼16%). Furthermore, the PB-SF electrode displays good electrochemical H2O2 sensing performance with sensitivity of 716.54 μA/mM·cm2, a linear range of 0.01∼0.6 mM and a low detection limit of 10 μM (S/N=3). Notably, the hybrid PB-SF electrode adapts to mechanical deformations with a series of angles and the electrical signals are not compromised obviously even after 100 home laundry washing cycles. PB modified silk fibers is simple, easy-operating and cost-effective electrode that is suitable for large-scale production as it can be integrated onto e-textiles through typical textile processing methods.

High-performance magnetic artificial silk fibers produced by a scalable and eco-friendly production method

Flexible magnetic materials have great potential for biomedical and soft robotics applications, but they need to be mechanically robust. An extraordinary material from a mechanical point of view is spider silk. Recently, methods for producing artificial spider silk fibers in a scalable and all-aqueous-based process have been developed. If endowed with magnetic properties, such biomimetic artificial spider silk fibers would be excellent candidates for making magnetic actuators. In this study, we introduce magnetic artificial spider silk fibers, comprising magnetite nanoparticles coated with meso-2,3-dimercaptosuccinic acid. The composite fibers can be produced in large quantities, employing an environmentally friendly wet-spinning process. The nanoparticles were found to be uniformly dispersed in the protein matrix even at high concentrations (up to 20% w/w magnetite), and the fibers were superparamagnetic at room temperature. This enabled external magnetic field control of fiber movement, rendering the material suitable for actuation applications. Notably, the fibers exhibited superior mechanical properties and actuation stresses compared to conventional fiber-based magnetic actuators. Moreover, the fibers developed herein could be used to create macroscopic systems with self-recovery shapes, underscoring their potential in soft robotics applications.

Weaving the past into the future

Silk played a crucial role in driving progress in Europe, particularly along the network of production and market centres along the Western Silk Road. The silk trade not only facilitated the exchange of ideas and innovations but also had a huge impact on the economic, technical, functional, cultural, and symbolic levels. However, silk heritage has become critically endangered, despite the existence of many specialised European museums dedicated to its preservation. These museums often lack the resources and capacity to utilise state-of-the-art digital technology. The objective of this paper is twofold: to introduce SILKNOW, an interdisciplinary project funded by the H2020 Program of the European Union to preserve and promote the heritage of silk textiles, and to present the project results which were possible thanks to digital humanities.

MOF-818 nanoparticles as radical scavengers to improve the aging resistance of silk fabric

Silk fabrics hold immense historical value as precious legacies left by our ancestors, yet they face significant damage during archaeological excavations, necessitating urgent protective measures. However, The current protective materials can’t effectively prevent the degradation of silk fabrics. Nanotechnology has emerged as a promising avenue for the consolidation and preservation of silk fabrics, offering novel concepts and materials. In this study, we propose an innovative and cost-effective method that uses the MOF-818 with a radical scavenging ability to enhance the protection of silk fabrics. The resulting demonstrates that the MOF-818 was the large surface area and porous properties, which exhibited excellent superoxide dismutase (SOD)-like activity at 10 ug/mL. The silk fabrics treated by MOF-818 displays small color difference, reduced the oxidation of functional group and prevents the degradation of silk fabrics. The successful development of this nanocomposite marks a significant advancement in silk protection, opening new horizons for the preservation of silk cultural relics.

Flat silk cocoons: A candidate material for fabricating lightweight and impact-resistant composites

The utilization of silk cocoons in the production of lightweight and tough composites has been gaining increasing attention. However, the limited applications of normal silk cocoons (NSC) are attributed to their small size and irregular shape. To overcome this deficiency, flat silk cocoons (FSC) with a similar structure and controllable size were prepared. Next, we systematically characterized and compared the microstructures, morphologies, compositions, thermal properties, and mechanical properties of FSC with NSC. Subsequently, FSC was successfully utilized to fabricate a novel silk fibroin fiber reinforced sericin matrix composite (HPFSC) using a hot pressing method, followed by the analysis of its microstructure evolution, mechanical properties, failure modes, and theoretical modeling. This composite has outstanding mechanical properties including hardness, modulus, and strength. HPFSC has a relatively low density of ~1.3 g/cm3, whose absorbed impact energy can reach a maximum value of 11.1 J/mm, exceeding that of most engineering materials, such as aluminum alloy, ceramics, glass, and carbon fiber composites. The exceptional performance of HPFSC can be attributed to the reduced porosity, enhanced bonding between silk fibroin fibers facilitated by sericin, and their structural transformation. This study offers valuable guidance for the fabrication of lightweight and impact-resistant composites using flat silk cocoons.

Fine Structural Analysis of Degummed Fibroin Fibers Reveals Its Superior Mechanical Capabilities.

Bombyx mori silk fibroin fibers constitute a class of protein building blocks capable of functionalization and reprocessing into various material formats. The properties of these fibers are typically affected by the intense thermal treatments needed to remove the sericin gum coating layer. Additionally, their mechanical characteristics are often misinterpreted by assuming the asymmetrical cross-sectional area (CSA) as a perfect circle. The thermal treatments impact not only the mechanics of the degummed fibroin fibers, but also the structural configuration of the resolubilized protein, thereby limiting the performance of the resulting silk-based materials. To mitigate these limitations, we explored varying alkali conditions at low temperatures for surface treatment, effectively removing the sericin gum layer while preserving the molecular structure of the fibroin protein, thus, maintaining the hierarchical integrity of the exposed fibroin microfiber core. The precise determination of the initial CSA of the asymmetrical silk fibers led to a comprehensive analysis of their mechanical properties. Our findings indicate that the alkali surface treatment raised the Young's modulus and tensile strength, by increasing the extent of the fibers' crystallinity, by approximately 40 % and 50 %, respectively, without compromising their strain. Furthermore, we have shown that this treatment facilitated further production of high-purity soluble silk protein with rheological and self-assembly characteristics comparable to those of native silk feedstock, initially stored in the animal's silk gland. The developed approaches benefits both the development of silk-based materials with tailored properties and the proper mechanical characterization of asymmetrical fibrous biological materials made of natural building blocks.

Evaluation of silk industrial heritage value based on IAHP, D-S theory and mixed decision model: the case of Hangzhou-Jiaxing-Huzhou in China

ABSTRACT A comprehensive understanding of the diverse value of industrial heritage is a prerequisite for preservation and reuse. After studying the composition and evaluation methods of the value of world cultural heritage, this paper puts forward a mixed decision model based on the combination of interval analytic hierarchy process, expert clustering ranking weighting method, fuzzy set and D-S theory. Firstly, an evaluation system that can describe the value of modern silk industry heritage in Hangzhou-Jiaxing-Huzhou area is established, which reflects comprehensiveness and particularity. Then, the interval analytic hierarchy process and expert clustering ranking method are proposed to calculate the weight of various indicators in the evaluation system, which can effectively reduce the influence of subjective experience and extreme experts on group decision-making. In addition, the fuzzy set theory and D-S theory are used to calculate the protection grades of several modern silk industrial heritages, and compared with the actual protection grades recognized by the state, which verifies the scientificity and effectiveness of the mixed decision-making model. Finally, the results show that the mixed decision model can accurately calculate the protection level consistent with the reality, demonstrating high feasibility and providing new ideas for the future evaluation of industrial heritage values.

Functionally‐Graded Serrated Fangs Allow Spiders to Mechanically Cut Silk, Carbon and Kevlar Fibers

Functionally‐Graded Serrated Fangs Allow Spiders to Mechanically Cut Silk, Carbon and Kevlar Fibers

Functionalization of silk with actinomycins from Streptomyces anulatus BV365 for biomedical applications.

Silk, traditionally acclaimed as the "queen of fiber," has been widely used thanks to its brilliant performance such as gentleness, smoothness and comfortableness. Owing to its mechanical characteristics and biocompatibility silk has a definitive role in biomedical applications, both as fibroin and fabric. In this work, the simultaneous dyeing and functionalization of silk fabric with pigments from Streptomyces anulatus BV365 were investigated. This strain produced high amounts of orange extracellular pigments on mannitol-soy flour agar, identified as actinomycin D, C2 and C3. The application of purified actinomycins in the dyeing of multifiber fabric was assessed. Actinomycins exhibited a high affinity towards protein fibers (silk and wool), but washing durability was maintained only with silk. Acidic condition (pH5) and high temperature (65°C) facilitated the silk dyeing. The morphologies and chemical components of the treated silk fabrics were analyzed using scanning electron microscopy and Fourier transform infrared spectroscopy. The results showed the pigments bind to the silk through interaction with the carbonyl group in silk fibroin rendering the functionalized, yet surface that does not cause skin irritation. The treated silk exhibited a remarkable antibacterial effect, while the biocompatibility test performed with 3D-reconstructed human epidermis model indicated safe biological properties, paving the way for future application of this material in medicine.

Electrospun Silk-ICG Composite Fibers and the Application toward Hemorrhage Control.

In trauma and surgery, efficient hemorrhage control is crucial to avert fatal blood loss and increase the likelihood of survival. There is a significant demand for novel biomaterials capable of promptly and effectively managing bleeding. This study aimed to develop flexible biocomposite fibrous scaffolds with an electrospinning technique using silk fibroin (SF) and indocyanine green (ICG). The FDA-approved ICG dye has unique photothermal properties. The water permeability, degradability, and biocompatibility of Bombyx mori cocoon-derived SF make it promising for biomedical applications. While as-spun SF-ICG fibers were dissolvable in water, ethanol vapor treatment (EVT) effectively induced secondary structural changes to promote β-sheet formation. This resulted in significantly improved aqueous stability and mechanical strength of the fibers, thereby increasing their fluid uptake capability. The enhanced SF-ICG interaction effectively prevented ICG leaching from the composite fibers, enabling them to generate heat under NIR irradiation due to ICG's photothermal properties. Our results showed that an SF-ICG 0.4% fibrous matrix can uptake 473% water. When water was replaced by bovine blood, a 25 s NIR irradiation induced complete blood coagulation. However, pure silk did not have the same effect. Additionally, NIR irradiation of the SF-ICG fibers successfully stopped the flow of blood in an in vitro model that mimicked a damaged blood vessel. This novel breakthrough offers a biotextile platform poised to enhance patient outcomes across various medical scenarios, representing a significant milestone in functional biomaterials.

From Ancient Threads to Colonial Commerce: The Evolution of West Bengals Silk Industry from Mythical Origins to Independence

Silk production, or sericulture, has a rich history that is frequently eclipsed by its modern applications. Sericulture began in ancient China approximately 3000 BC and this was a well held secret until it spread to Korea, India and eventually the West through a variety of causes, including royal intrigue and missionary endeavours. By the Han Dynasty, silk had evolved from a luxury item to a valuable economic asset, impacting trade and culture throughout Asia and Europe. India's silk industry, as documented in ancient scriptures, progressed from early wild silk production in the Himalayan foothills to sophisticated mulberry sericulture by the 2nd century BCE. The Mughal dynasty improved Indian silk traditions by incorporating several weaving techniques and nurturing a thriving business in Kashmir and Bengal. From 1612 to 1858, the East India Company capitalised on Bengal's silk potential by building trading centres and using Piedmontese reeling technology to improve quality. Despite initial hurdles, Bengal silk became a major export commodity, but colonial policies and technological shifts eventually led to its demise. Silk output fell dramatically after independence due to a variety of economic and geopolitical issues. This article investigates the growth of India's silk industry, focussing on Bengal's key role and examines the effects of colonial control, technological advancements and the sector's trajectory up to Independence.

Sustainable Assessment of Bio-Colorant from Bakain Bark (Melia azedarach L.) for Dyeing of Cellulosic and Proteinous Fabric.

The current study proceeded to reduce the environmental hazards spreading worldwide due to synthetic dyes. To overcome these problems, eco-friendly natural dyes are introduced as alternative sources of synthetic dyes. The present study was focused on exploring the bio-colorant of the aqueous and acidic extract of the bark of Melia azedarach L. for the dyeing of both silk and cotton samples. The results of the extraction medium specified that the aqueous extract gave maximum colorant solubility and upon fabric dyeing produced higher color strength in contrast to the acidic medium. The optimization experimentation data showed that excellent color strength of silk fabric was found at 45 min dyeing time duration, in 35:1 mL dye extract, and using 2% salt (NaCl) as an exhausting agent, whereas cotton fabric showed the maximum K/S value at 60 min dyeing time, in a 45:1 mL liquor ratio, and with the use of 2% salt. Bio-mordants produce different shades on both fabrics. Bio-mordanting experiments on silk revealed that pre-mordanting with 2% turmeric and 3% pomegranate, and post-mordanting using 3% turmeric and 2% pomegranate produced a darker shade. In the case of cotton, the pre-mordanted samples with 2% turmeric and 3% pomegranate and the post-mordanted samples with 4% turmeric and 4% pomegranate gave the highest color strengths. All the mordanted samples gave excellent fastness ratings. Overall, it has been found that Bakain bark proved to be an excellent source of tannin. The result of this study showed that it could be a cost-effective and eco-friendly dye source for textile progress.

Silk Fabric Functionalized by Nanosilver Enabling the Wearable Sensing for Biomechanics and Biomolecules.

Integrating biomechanical and biomolecular sensing mechanisms into wearable devices is a formidable challenge and key to acquiring personalized health management. To address this, we have developed an innovative multifunctional sensor enabled by plasma functionalized silk fabric, which possesses multimodal sensing capabilities for biomechanics and biomolecules. A seed-mediated in situ growth method was employed to coat silver nanoparticles (AgNPs) onto silk fibers, resulting in silk fibers functionalized with AgNPs (SFs@Ag) that exhibit both piezoresistive response and localized surface plasmon resonance effects. The SFs@Ag membrane enables accurate detection of mechanical pressure and specific biomolecules during wearable sensing, offering a versatile solution for comprehensive personalized health monitoring. Additionally, a machine learning algorithm has been established to specifically recognize muscle strain signals, potentially extending to the diagnosis and monitoring of neuromuscular disorders such as amyotrophic lateral sclerosis (ALS). Unlike electromyography, which detects large muscles in clinical medicine, sensing data for tiny muscles enhance our understanding of muscle coordination using the SFs@Ag sensor. This detection model provides feasibility for the early detection and prevention of neuromuscular diseases. Beyond muscle stress and strain sensing, biomolecular detection is a critical addition to achieving effective health management. In this study, we developed highly sensitive surface-enhanced Raman scattering (SERS) detection for wearable health monitoring. Finite-difference time-domain numerical simulations ware utilized to analyze the efficacy of the SFs@Ag sensor for wearable SERS sensing of biomolecules. Based on the specific SERS spectra, automatic extraction of signals of sweat molecules was also achieved. In summary, the SFs@Ag sensor bridges the gap between biomechanical and biomolecular sensing in wearable applications, providing significant value for personalized health management.

Molecular dynamics modelling of the stress–strain response of [formula omitted]-sheet nanocrystals

Molecular dynamics simulations were conducted on two model antiparallel β-sheet crystallites [GA]n and [GAS]n to study deformation in chain, sheet stacking, and hydrogen bonding directions under uniaxial loading. In chain direction, both models were mechanically stable, even beyond the 570 K amorphousation temperature of silk fiber; however, [GA]n model displayed higher yield strain, stress, elastic modulus, and resilience than [GAS]n. In transverse directions, they had similar stress–strain behavior and demonstrated significant anisotropic mechanical behavior. Hence, inclusion of an amino acid with a rich side chain group extending between β-sheets reduces the stiffness of crystallite in chain direction. Serine and alanine residues maintained existing H-bonds and established new ones during stretching in chain direction and shrinking in transverse directions which affected the mechanical response near the yield point. Comparison between β-sheet crystallite and PPTA (Kevlar) showed that the mechanical performance of these crystal polymers were very similar in chain direction, but contrarily β-sheet crystallite had higher stiffness in H-bonding and sheet stacking directions than PPTA. This study may provide a guideline in designing of polyaminoacid based biocompatible materials with superior mechanical performance.

Tasar silk fiber waste reinforced polylactic acid composite: Physical, mechanical, and sliding wear characterization

Incorporating natural industrial waste as a reinforcement for the development of sustainable composite is now being extensively practiced to eliminate harmful synthetic fiber. This study exhaustively evaluated the potential of tasar silk fiber waste (TSFW) as a reinforcing agent in a polylactic acid (PLA) matrix to optimize the physical, mechanical, and wear properties. Therefore, PLA-based biocomposites with varying TSFW proportions (0, 2, 4, 6, 8, and 10 by weight) are manufactured and then evaluated for physical (density, voids, water absorption), mechanical (tensile, flexural, impact, and hardness), and sliding wear properties. Results suggested that water uptake of PLA composites increases with the addition of TSFW and becomes saturated after nine days of immersion. The TSFW reinforcement at 8 wt% in PLA yields 32 % and 22 % improvement in tensile strength (66.2 MPa) and flexural strength (103.2 MPa), respectively. A remarkable improvement was observed in the impact strength at similar reinforcement (8 wt%) of TSFW with the observed value of 27.90 kJ/m2. A continuous increase in hardness was obtained by including TSFW in PLA, with the highest value of 86 Shore D recorded for 10 wt% TSFW added biocomposite. The specific wear rate of all samples increased, but the incorporation of TSFW significantly reduced the same. Microscopic examination suggests that microploughing, microcutting and groove formations were the main mechanism of material removal. After examining the results, it is recommended that TSFW be used in bidirectional mat form for further enhancement of mechanical properties and improved bonding between fiber and matrix.

Study on dyeability of silk fabric with anthocyanin extracted from butterfly pea flowers

Study on dyeability of silk fabric with anthocyanin extracted from butterfly pea flowers

The renewed tin-weighting treatment as sustainable and durable flame-retardant approach for protein silk fabric

The facile development of a sustainable and durable flame-retardant approach for protein silk is of interest. Inspired by silk tin-weighting technology, this study developed a novel and sustainable in-situ deposition strategy based on biomass phytic acid to impart durable flame-retardant performance to silk fabrics. The chemical structure of insoluble chelating precipitation, and the surface morphology, thermal stability, combustion behavior, flame-retardant capacity, laundering resistance, and flame-retardant mode of action of the tin-weighting silk samples, were explored. The Sn-, P-, Si-containing insoluble chelating precipitation formed within the fiber interior and combined with silk fibers through electrostatic attraction and metal salt chelation. As a result, the tin-weighting silk displayed excellent self-extinguishing capacity, with the damaged length reduced to 9.2 cm and the LOI increased to 31.6 %; it also achieved self-extinguishing after 30 washing cycles, demonstrating high flame-retardant efficacy and laundering resistance. Moreover, the tin-weighting silk also showed the obvious suppression in smoke and heat generation by 55.6 % and 35.7 %, respectively. The synergistic charring action of phosphate groups, tin metal salts, and silicates was beneficial for enhancing the fire safety of silk. The tin-weighting treatment also displayed a minor impact on mechanical performance of silk fabrics.

Characterization and comparative analysis of sericin protein 150 in Bombyx mori

Lepidopteran silk is a complex mixture of proteins, consisting mainly of fibroins and sericins. Sericins are a small family of highly divergent proteins that serve as adhesives and coatings for silk fibers. So far, five genes encoding sericin proteins have been identified in Bombyx mori. Having previously identified sericin protein 150 (SP150) as a major sericin-like protein in the cocoons of the pyralid moths Galleria mellonella and Ephestia kuehniella, we describe the identification of its homolog in B. mori. Our refined gene model shows that it consists of four exons and a long open reading frame with a conserved motif, CXCXCX, at the C-terminus, reminiscent of the structure observed in a class of mucin proteins. Notably, despite a similar expression pattern, both mRNA and protein levels of B. mori SP150 were significantly lower than those of its pyralid counterpart. We also discuss the synteny of homologous genes on corresponding chromosomes in different moth species and the possible phylogenetic relationships between SP150 and certain mucin-like proteins. Our results improve our understanding of silk structure and the evolutionary relationships between adhesion proteins in the silk of different lepidopteran species.

The effect of weighting on the color appearance of dyed silk fabric

The weighting process may change the color appearance of silk. The objective of the present study is to evaluate the effect of weighting with methyl methacrylate (MMA) on the color appearance of silk fabric using the response surface method. For this purpose, a CCD design was used to investigate the effect of methyl methacrylate monomer concentration and dye concentration on color appearance and percentage of weight gain of silk fabric. Analysis of variance, response surface, and contour plots of the colorimetric characteristics of the weighted silk fabric show that the methyl methacrylate concentration has a significant effect on color parameters such as L*, a*, b*, C*, and hue angle of the weighted silk fabric. The results indicate that the weighting process changes the color of silk fabric.