Silk Research Articles

Influence of granite micro particles on the mechanical, damping and antimicrobial properties of silk–sisal hybrid composites

This paper focuses on the effect of granite-micro-filler on static mechanical properties, damping behavior, and physical characteristics of silk-sisal hybrid composite. The composites structures are fabricated by using three layers of plain weaves mat with varying weight percentages (2, 4, and 6 wt%) of granite-micro-filler by hand layer process. The effect of granite-micro-filler on silk-sisal is analyzed and results are compared with pure silk-sisal (without granite-Micro-filler) hybrid composite. The results infer that; the tensile strength and flexural strength value of the developed silk-sisal hybrid composites are increased with the increase in wt% of granite-micro-filler content than pure silk–sisal, approximately 5% and 9% improved value in order by adding 6 wt% granite-micro-filler on silk–sisal. The tensile and flexural fracture morphology analysis indicated that composed plain weave of silk–sisal fiber mat with two (longitudinal and transverse) directions possesses higher mechanical properties and also observed that, granite-micro-filler dispersed on silk–sisal fiber mat and resin with closely packed. The improved damping factor is obtained by adding 6 wt% of granite-micro-filler content, which is approximately 75.8% higher than pure silk–sisal. The physical properties of silk–sisal hybrid composite have also been analyzed and well discussed in this paper.

Development of Antimicrobial and Insecticidal Silk Fabrics via Eco-printing with Natural Dyes from Agricultural Wastes

Development of Antimicrobial and Insecticidal Silk Fabrics via Eco-printing with Natural Dyes from Agricultural Wastes

Cleaner isolation and application of sustainable new novel source of natural dye from tallow laureal (Litsea glutinosa) for silk dyeing

AbstractThe utilization of waste plant residues in useful work particularly as the source of green dyes in textiles is now a days welcoming by global community. In this study, brown bollygum chips (Litsea glutinosa) called tallow laurel has been explored for silk dyeing using ecofriendly approaches. Extraction has been done in suitable medium and utilized onto fabric before and after microwave (MW) treatment up to 10 min. Response surface methodology was employed to observe the significant of selected dyeing parameters at which shade development with improved colorfastness was observed. It was found that 2 min radiation to both acidic extract of tallow laureal and silk fabric is the useful condition to get colorfast shade when employed before and after mordanting with iron salt and tannic acid solution as eco‐chemical agent, whereas with walnut bark and pine nut hulls extract as eco bio agents. The highest color strength value of 4.58 was observed using tannic acid as postchemical mordant for silk dyeing. The standard methods for fastness as per ISO to light, washing, and rubbing reveal that using selected shades made under ecofriendly cost time and energy effective conditions, stable colorfast hues were rated good with the value of 4/5. Therefore, it is recommended that MW treatment in addition with statistical approach i.e., central composite design used for exploring new dye yielding plant, then using eco‐mordanting technique will help in getting promising colorfast shades.

De-novo long-read genome assembly and annotation of the luna moth (Actias luna) fully resolves repeat-rich silk genes.

We present the first long-read de-novo -assembly and annotation of the luna moth (Actias luna) and provide the full characterization of heavy chain fibroin (h-fibroin)--, a long and highly repetitive gene (>20 Kbp) essential in silk fiber production. There are more than 160,000 described species of moths and butterflies (Lepidoptera), but only within the last five years have we begun to recover high-quality annotated whole genomes across the order which capture h-fibroin. Using PacBio HiFi reads, we produce the first high-quality long-read reference genome for this species. The assembled genome has a length of 532 Mbp, a contig N50 of 16.8 Mbp, an L50 of 14 contigs, and 99.4% completeness (BUSCO). Our annotation using Bombyx mori protein and A.luna RNAseq evidence captured a total of 20,866 genes at 98.9% completeness with 10,267 functionally annotated proteins and a full-length h-fibroin annotation of 2,679 amino acid residues.

Identification of Bacteria Producing Red Pigments and Their Application in the Textile Industry

AbstractIn this study, bacterial strains previously isolated and maintained in a culture collection were evaluated for their pigment production capabilities. The pigments produced by the bacteria were using the methanol extraction method and characterized by thin-layer chromatography, UV–Vis, and Fourier transform infrared spectroscopy (FTIR). In addition, the potential use of these pigments as textile dyes in silk fabrics was investigated. Four of the 270 isolates screened (AS-54, AS-55, AS-67, and AS-75) showed superior pigment production. These isolates were further identified using both classical and molecular methods. Based on the analysis of the 16S rRNA gene region, AS-54, AS-55, and AS-67 were identified as Serratia plymuthica and, AS-75 as Serratia marcescens. Characterization results showed that the pigments exhibited a red coloration, indicating prodigiosin. The dyeing of silk fabrics with these pigments resulted in various shades of pink, highlighting their potential as textile dyes. These results suggest that pigments derived from these bacterial isolates hold great promise for applications in the textile industry.

Possibilities of Bombyx mori (B. mori) biotechnological platform for regenerative medicine

Regenerative medicine aims at changing modern medicine practice by eliminating core reasons of diseases and disorders. Regenerative medicine includes gene therapy, cell therapy and products of tissue engineering that are destined for augmentation, regeneration or replacement of organs, tissues, genes and metabolic processes in the organism. Biomaterials are amongst key components of regenerative medicine on which successful strategies are based.The review of biotechnological methods implemented in the USP and DSP stages with the use of B. mori was made. The methods analysed are aimed at improving quality characteristics and obtaining new kinds of biomaterials to meet the needs of regenerative medicine and biomedicine. The diversity of biotechnological solutions that allow to gain a wide spectrum of biomaterials (incl. derivatives of cocoon shell such as fibroin, sericin and their composites; recombinant derivatives; antimicrobial peptides; modified transgenic silk fibres;transgenic fibres that contain growth factors and peptides; etc.) is a unique basis for the bioindustrial platform on the B. mori basis.

Solar-driven salt-free deposition evaporation for simultaneous desalination and electricity generation based on tip-effect and siphon-effect

Solar-driven desalination is a promising way to alleviate the freshwater shortage, while is facing challenges posed by low evaporation rates and severe salt accumulation. Herein, a high-performance two-dimensional (2D) solar absorber with Co3O4 nanoneedle arrays (Co3O4-NN) grown on the surface of reduced graphene oxide-coated pyrolyzed silk cloth (Co3O4-NN/rGO/PSC) was prepared, and a salt-free evaporator system was assembled based on the composite material and siphonage-the flowing water delivery. It is revealed that the evaporation enthalpy of water can be reduced over the 2D solar absorber grown with Co3O4-NN, enabling an evaporation rate of up to 2.35 kg m−2 h−1 in DI water under one solar irradiation. The desalination process can be carried out continuously even with salt concentration up to 20 wt%, due to the timely removal of concentrated brine from the interface with the assistance of directed flowing water. Moreover, the 2D structure and the flowing water also provide an opportunity to convert waste solar heat into electricity in the evaporator based on the seebeck effect, ensuring simultaneous freshwater production and power generation. It is believed that this work provides insights into designing hybrid systems with high evaporation rate, salt resistance, and electricity generation.

Coloration and functionalization of silk fabric based on silver nanoparticles green synthesized from chitosan

This research develops a novel route for the coloration of silk fabric with green synthesized silver nanoparticles (AgNPs) using chitosan as a natural eco-friendly reducing agent. The formation of AgNPs was characterized by the appearance of LSPR absorption peak at 414–448 nm. Based on a TEM image of spherical particles dominated at a particle size between 5 and 10 nm. The zeta potential shows that the AgNPs synthesized from the chitosan are highly stable. The deposition of AgNPs on the silk fabric surface was analyzed with scanning electron microscopy (SEM). The coloration and fastness properties of fabric were found to be significantly improved, a result related to the surface plasmon resonance of AgNPs. The antibacterial properties of the fabric were also found to be excellent, as a more than 87% bacterial reduction was noticed even after 20 washing cycles. Overall, this silk coloration using green nanoparticles can contribute to the low-cost production of multifunctional textiles.

Sustainable production of liquid phenyl using oil extracted from discarded pupae of mulberry silk worms (Bombyx mori)

The mulberry silkworm (Bombyx mori) pupae, typically discarded as waste by the silk industry, are a valuable source of oil. Using the Soxhlet extraction method, 30.4 % oil was recovered from the pulverized dried pupae. This oil exhibited a high iodine value of 120 gI2/100 g and a saponification value of 201 mg KOH/g, which qualified it for soap making in phenyl. Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified five fatty acids in the oil: palmitoleic acid, linoleic acid, oleic acid, stearic acid, and palmitic acid. The composition was 38.80 % saturated fatty acids (SFA), 46.01 % monounsaturated fatty acids (MUFA), and 15.20 % polyunsaturated fatty acids (PUFA). A disinfectant liquid, phenyl, was formulated using this oil, leveraging its high oleic acid content (45.10 %) and favorable physicochemical properties. The antibacterial efficacy of the phenyl was tested against eight harmful bacterial strains. It showed significant activity against all tested bacteria, particularly gram-negative strains, with inhibition zones ranging from 20.25 to 28.0 mm, outperforming the positive control, chloramphenicol, which had inhibition zones of 15.45–19.40 mm. For gram-positive bacteria, the inhibition zones were 14.25–22.50 mm. The phenyl was most effective against Pseudomonas aeruginosa and Escherichia coli, with inhibition zones of 28.0 mm and 23.50 mm, respectively. The minimum inhibitory concentration (MIC) was highest for Pseudomonas aeruginosa and Escherichia coli at 110 μL/mL, and for Staphylococcus aureus at 115 μL/mL. The prepared phenyl disinfectant proved to be efficient against a range of bacteria and can be used to sanitize various surfaces effectively.

Testing relationship of bending rigidity with drape coefficient for silk viscose blended knitted fabrics

Testing relationship of bending rigidity with drape coefficient for silk viscose blended knitted fabrics

Green blend nanocomposites developed from waste sericin, polyvinyl alcohol and boehmite for flexible electronic devices

The present research article demonstrates the dispersion of boehmite (BHM) nanoparticles into sericin (SER) from silk industry waste with polyvinyl alcohol (PVA) to enhance the optical, mechanical, thermal and electrical characteristics of PVA/SER blend nanocomposites prepared by a simple green synthesis. Techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV visible spectroscopy, field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were carried out for the characterization of the prepared composites. XRD revealed the increased crystallinity of the polymer blend by the reinforcement of BHM. The existence of intermolecular interactions in the blend composite was confirmed by FTIR and UV spectroscopy. The optical bandgap energy of the biopolymer blend decreases with the inclusion of BHM. The SEM and HR-TEM confirmed the homogeneous dispersion of BHM in the blend at 5 wt% loading. The glass transition temperature and thermal stability of the blend nanocomposites were significantly improved by the inclusion of BHM was deduced from DSC and TGA. The dielectric constant and AC conductivity were remarkably increased with the reinforcement of nanoparticles. The activation energy obtained from AC conductivity decreased with temperature. The mechanical properties of the blend nanocomposites (hardness, tensile strength and Young's modulus) were greatly increased in presence of BHM. The 5 wt% sample has the highest tensile strength, Young's modulus, dielectric constant, AC conductivity and optical properties, allowing it to be used to make optoelectronic devices with better charge-storing capacity and flexible-type electrochemical gadgets.

Α {Silk@Gallic‐Acid} hybrid material with controllable antioxidant hydrogen‐atom‐transfer activity

AbstractSilk fiber, often acclaimed as the pinnacle of textile materials, finds contemporary applications in the textile industry, health, and cosmetics. Gallic acid (GA) is a well‐established natural antioxidant. In the present study, a novel hybrid material SFd@GA was conceptualized and produced via surface grafting of GA onto degummed silk‐fibers (SFd). Successful covalent‐grafting of gallic acid onto the silk fabric surface was confirmed through Fourier‐transform infrared, Raman, thermogravimetric analysis (TG‐DTA), and scanning electron microscopy (SEM). electron paramagnetic resonance spectroscopy demonstrates that gallic moieties grafted on SFd@GA retain their radical/redox activity. The antioxidant capacity of the hybrid material SFd@GA was validated by quantitative analysis of antioxidant hydrogen‐atom‐transfer (HAT) to DPPH radicals. Our data reveal a 550% increase in antioxidant‐HAT activity of SFd@GA versus natural intact silk fiber, and a 1400% increase in antioxidant‐HAT activity compared to the degummed silk fiber. The paramount discovery of the present work lies in the capacity for repeated utilization of the hybrid material SFd@GA, without any discernible compromise in its antioxidant‐HAT activity. Specifically, we show that SFd@GA can be employed for at least 15 consecutive cycles, retaining >98% of its HAT efficiency, for up to many days of storage under ambient conditions. We discuss this expositional performance via the controllable Hat‐activity process that we propose.

A Study on Cruelty Faced by Silkworms in the Production of Silk

Silk is the fiber that silkworms weave to make their cocoons which are the outer casings that protect them during the pupal stage. But most of the insects used by the silk industry don’t live past this stage, because they are boiled or gassed alive inside their cocoons, which causes the cocoons to begin unraveling so that workers can obtain the silk threads. Some 6,600 silkworms are killed to make just 1 kilogram of silk. The CSB (Amendment) Act, Rules and Regulations have been notified by the Govt. of India to bring quality standards in silkworm seed production. The objective of the research is to create awareness on the cruelty faced by silkworms in the production of silk. The research method used is empirical research and simple random sampling method is used and the sample size is 200 responses and the sample frame is in and around Valluvar kottam. The independent variables are age, gender, education qualifications, occupation and locality. The alternative to this cruel practice is to use another method of obtaining silk called ahimsa silk or wild silk, it is a method of nonviolent silk breeding and harvesting. Wild silk moths are bred, rather than the domestic variety. Roughly 3,000 silkworms are killed to make a single pound of silk. That means that billions, if not trillions, of them are killed for this every year. In order to avoid this practice of killing silkworms we should use an alternative type of fabric or use wild silk

Novel theranostic wounds dressing based on pH responsive alginate hydrogel/graphene oxide/levofloxacin modified silk

Integrating pH sensor with controlled antibiotic release is fabricated on silk to create a theranostic wound dressing. Alginate (ALG) hydrogel and graphene oxide (GO) loaded with levofloxacin (LVX) and a pH indicator are applied to fabricate a pH-responsive theranostic wound dressing. The modified silk color changes from yellow to green in response to elevated skin pH, indicating the skin infection. The semi-quantitative analysis was conducted using ImageJ, revealing significant color changes across the wide range. At elevated pH levels, the ionization of the COOH bonds within ALG induces repulsion among the COO− groups, thereby accelerating the release of the incorporated drug compared to release under lower pH. At an infected pH of 8, ALG hydrogel triggers LVX releasing up to 135.86 ± 0.3 µg, while at a normal pH of 7, theranostic silk releases 123.13 ± 0.26 µg. Incorporating GO onto silk fibers enhances LVX loading and sustains LVX release. Furthermore, these modified silks possess antimicrobial abilities without causing irritation or allergies on the human skin. This theranostic silks represents a major step forward in smart wound care, introducing a versatile platform of smart wound care.

Fe-reinforced silkworm silk with superstrong mechanical properties for mass production

Silk is a versatile material known for its outstanding properties, including good mechanical performance, luster, and biocompatibility in various fields. However, the growing demand for silk in diverse applications necessitates further improvements in its performance. Traditional methods for improving silk performance face challenges such as low strength, toughness, and limited mass production. Here, we report a novel approach that combines genetic engineering and ion reinforcement to produce silk fibers with exceptional strength and stiffness. By overexpressing iron ion-related protein genes in the anterior silk gland of silkworms, this study successfully increased the iron ion content in the resulting silk. Furthermore, when applied to the large-scale production of hybrid silkworm varieties, the mechanical properties of silk were significantly enhanced, thus facilitating mass production. The resulting silk exhibited remarkable mechanical properties, including a high fracture strength (790.3 MPa), fracture energy (123.2 MJm−3), stretchability (∼21.41 % strain) and Young’s modulus (15.41 GPa). Comprehensive analysis involving dynamic simulation, synchrotron radiation infrared spectroscopy, X-ray diffraction, fluorescence spectroscopy, and circular dichroism analysis confirmed the specific interaction between iron ions and tyrosine within the silk protein. This interaction promoted the formation of increased the β-sheet and crystal contents in the silk fibers, contributing to their improved mechanical properties. Importantly, this concept can be extended to other metal ions, offering a promising method for enhancing silk structure and mechanical properties without changing the silk protein sequence.

Overview and Evolution of Insect Fibroin Heavy Chain (FibH).

The FibH gene, crucial for silk spinning in insects, encodes a protein that significantly influences silk fiber mechanics. Due to its large size and repetitive sequences, limited known sequences of insect FibH impede comprehensive understanding. Here, we analyzed 114 complete FibH gene sequences from Lepidoptera (71 moths, 24 butterflies) and 13 Trichoptera, revealing single-copy FibH in most species, with 2-3 copies in Hesperinae and Heteropterinae (subfamily of skippers). All FibH genes are structured with two exons and one intron (39-45 bp), with the second exon being notably longer. Moths exhibit higher GC content in FibH compared to butterflies and Trichoptera. The FibH composition varies among species, with moths and butterflies favoring Ala, Gly, Ser, Pro, Gln, and Asn, while Trichoptera FibH is enriched in Gly, Ser, and Arg, and has less Ala. Unique to Trichoptera FibH are Tyr, Val, Arg, and Trp, whereas Lepidoptera FibH is marked by polyAla (polyalanine), polySer (polyserine), and the hexapeptide GAGSGA. A phylogenetic analysis suggests that Lepidoptera FibH evolved from Trichoptera, with skipper FibH evolving from Papilionoidea. This study substantially expands the FibH repertoire, providing a foundation for the development of artificial silk.

The production of soluble regenerated silk fibroin powder with high molecular weight and silk protein-based materials

The aqueous solution of regenerated silk fibroin (RSF) is considered as the raw material to produce various silk protein-based materials, including hydrogel, film, rod and fiber, etc. with significant mechanical properties. However, the aqueous solution of RSF is usually unstable within a few days or even hours in terms of its essential properties, because the conformation of the RSF chain would spontaneously transfer from random coil to β-sheet in water. In this work, we developed a way to harvest the RSF powder through an optimized spray drying method via rapid drying at a relatively low temperature. It was demonstrated that no severe degradation and conformational transition of the RSF chain occurred during powder preparation, and the RSF powder exhibited remarkable solubility in water and long stability at room temperature. Importantly, there are no obvious differences in the mechanical properties of the silk protein-based materials made from the aqueous solution from the spray-dried RSF powder (Sp-RSF) and from fresh RSF solution. Indeed, such amorphous Sp-RSF powder, in which the protein chain was dominated by random coil conformation, not only promised as the raw material for large-scale silk protein-based products in various applications but also provided the basis for fabricating bulk silk protein materials via the untraditional processing of silk fibroin, such as molding with the help of heat and moisture.

A study of forecasting the Nephila clavipes silk fiber's ultimate tensile strength using machine learning strategies

Recent advancements in biomaterial research conduct artificial intelligence for predicting diverse material properties. However, research predicting the mechanical properties of biomaterial based on amino acid sequences have been notably absent. This research pioneers the use of classification models to predict ultimate tensile strength from silk fiber amino acid sequences, employing logistic regression, support vector machines with various kernels, and a deep neural network (DNN). Remarkably, the model demonstrates a high accuracy of 0.83 during the generalization test. The study introduces an innovative approach to predicting biomaterial mechanical properties beyond traditional experimental methods. Recognizing the limitations of conventional linear prediction models, the research emphasizes the future trajectory toward DNNs that can adeptly capture non-linear relationships with high precision. Moreover, through comprehensive performance comparisons among diverse prediction models, the study offers insights into the effectiveness of specific models for predicting the mechanical properties of certain materials. In conclusion, this study serves as a pioneering contribution, laying the groundwork for future endeavors and advocating for the seamless integration of AI methodologies into materials research.

Effect of Phosphate on the Molecular Properties, Interactions, and Assembly of Engineered Spider Silk Proteins.

Phosphate plays a vital role in spider silk spinning and has been utilized in numerous artificial silk spinning attempts to replicate the remarkable mechanical properties of natural silk fiber. Its application in artificial processes has, however, yielded varying outcomes. It is thus necessary to investigate the origins and mechanisms behind these differences. By using recombinant silk protein SC-ADF3 derived from the garden spider Araneus diadematus, here, we describe its conformational changes under various conditions, elucidating the effect of phosphate on SC-ADF3 silk protein properties and interactions. Our results demonstrate that elevated phosphate levels induce the irreversible conformational conversion of SC-ADF3 from random coils to β-sheet structures, leading to decreased protein solubility over time. Furthermore, exposure of SC-ADF3 to phosphate stiffens already formed structures and reduces the ability to form new interactions. Our findings offer insights into the underlying mechanism through which phosphate-induced β-sheet structures in ADF3-related silk proteins impede fiber formation in the subsequent phases. From a broader perspective, our studies emphasize the significance of silk protein conformation for functional material formation, highlighting that the formation of β-sheet structures at the initial stages of protein assembly will affect the outcome of material forming processes.

Effect of natural silk fibers and synthetic fiber-reinforced composites on the cytotoxicity of fibroblast cell lines.

Synthetic fibers have many benefits in clinical practice; however, they cause microplastic pollution, and their unaffordable price increases treatment costs. Natural silk fibers require biocompatibility assessment. This study investigated the effects of natural and synthetic fiber-reinforced composites (FRCs) on the cytotoxicity of fibroblast cell lines. Three commercial synthetic fibers (polyethylene, quartz, and E-glass) and two silk fibers from Bombyx mori and Samia ricini cocoons were employed. These fibers were made into FRC samples (n=6) by impregnation in flowable composite using a brass mold (25×2×2 mm). NIH/3T3 mouse fibroblasts were cultured in Dulbecco's modified eagle medium, supplemented, and seeded in 2×104 cells/mL. They were stored at 37 °C under 5% CO2 for 24 hours. The FRC samples were made into powder, eluted in dimethylsulfoxide, continued with PBS, supplemented with Dulbecco's modified eagle medium (DMEM), and exposed to cells for 24 hours. Blank (medium only) and control (cells and medium) samples were included. Subsequently, MTT was added for 4 h and read by enzyme-linked immunosorbent assay (λ=570 nm). Cell viability (%) was calculated and analyzed using one-way ANOVA (α=0.05). All groups of FRCs showed>80% cell viability. One-way ANOVA showed no significant difference between FRC groups regarding the viability of fibroblast cell lines (P>0.05). Both natural silk and synthetic fibers exhibit low cytotoxicity to fibroblast cell lines. B. mori and S. ricini silk fibers showed the potential to be used as alternative synthetic fibers.