Types Of Silk Research Articles

Characteristics Of Attacus atlas Cocon Collected from Tree of Mahoghony (Swietenia mahagoni) in Kembaran District

Attacus atlas is a wild silk type from the non-mulberry group, representing various fagara silkworms that produce cocoons. The produced cocoons have high economic value when utilized for commercial silk production. The distinctive characteristic of A. atlas silk fibers differs from Bombyx mori (mulberry) silk as the resulting fibers have a natural brown color without dyeing processes. The characteristics of cocoons significantly impact the resulting thread production. This study aims to obtain data on the characteristics and morphometrics of A. atlas cocoons located on mahogany trees providing road shade in Kembaran District. Observed characteristics include the weight of the intact cocoon skin, the weight of cocoon skin without floss, the weight of floss, cocoon diameter, cocoon circumference, cocoon length, and cocoon color. The collected data were then analyzed using descriptive analysis. The research shows that A.atlas cocoon skin characteristics vary greatly, demonstrated by the weight of the intact Cocoon Skin (0.66-2.35 g), the weight of Cocoon Skin without Floss (0.46-1.93 g), the weight of Floss (0.1-0.54 g), Cocoon Length (5.2-8.1 cm), Anterior Diameter (2.10-3.0 cm), Medial Diameter (2.30-3.4 cm), Posterior Diameter (2.20-3.1 cm), Anterior Circumference (6.20-9.50 cm), Medial Circumference (7.70-10.50 cm), Posterior Circumference (6.10-9.10 cm), and cocoon color classification into light (17 cocoons/15.9%), medium (66 cocoons/61.7%), and dark (24 cocoons/22.4%). The temperature, cocooning location, and gender of the cocoon are unknown, resulting in weight and morphometric value variations.

Webs of intrigue: museum genomics elucidate relationships of the marronoid spider clade (Araneae)

Abstract Relationships among spider families that lack support through other lines of evidence (e.g., morphology) have recently been uncovered through molecular phylogenetics. One such group is the “marronoid” clade, which contains about 3,400 described species in 9 families. Marronoids run the gamut of life history strategies, with social species, species producing a variety of silk types, and species occurring in a range of extreme environments. Despite recognition of the ecological variability in the group, there remains uncertainty about family- level relationships, leaving diverse ecologies without an evolutionary context. The phylogenies produced to date have relatively low nodal support, there are few defined morphological synapomorphies, and the internal relationships of many families remain unclear. We use 93 exemplars from all marronoid families and ultraconserved element loci captured in silico from a combination of 48 novel low-coverage whole genomes and genomic data from the Sequence Read Archive (SRA) to produce a 50% occupancy matrix of 1,277 loci from a set of ultraconserved element probes. These loci were used to infer a phylogeny of the marronoid clade and to evaluate the familial relationships within the clade, and were combined with single-locus (Sanger) legacy data to further increase taxonomic sampling. Our results indicate a clearly defined and well-supported marronoid clade and provide evidence for both monophyly and paraphyly within the currently defined families of the clade. We propose taxonomic changes in accordance with the resulting phylogenetic hypothesis, including elevating Cicurinidae (restored status) and Macrobunidae (new rank).

Secretion of dermal glands in freshwater mites (acariformes, parasitengonina, hydrachnidia) and its structural characteristics

Freshwater mites, single possessors of dermal glands in Parasitengonina, demonstrate production of special filamentous substance, which may be characterized as silk. The silk secretion and silk stricture in water mites are described and analyzed in comparison with other arthropods. A single silk thread has the simplest organization among that of other arthropods - it is an infinitely long unbranched uniform hollow tube, the walls of which are composed of fine fibrils crossing at different angles to each other. Although silk in water mites does not form a structural organized web as in spiders, it is highly likely that in mass production it serves for capturing prey - small water arthropods. This kind of silk - is a new discovered type of arthropod silk, and the ability of silk production has elaborated in water mites after their ancestors have invaded and mastered the aquatic environment. This property greatly expands the possibilities in the competition for resources.

Pulling and analyzing silk fibers from aqueous solution using a robotic device

Spiders, silkworms, and many other animals can spin silk with exceptional properties. However, artificially spun fibers often fall short of their natural counterparts partly due sub-optimal production methods. A variety of methods, such as wet-, dry-, and biomimetic spinning have been used. The methods are based on extrusion, whereas natural spinning also involves pulling. Another shortcoming is that there is a lack feedback control during extension. Here we demonstrate a robotic fiber pulling device that enables controlled pulling of silk fibers and in situ measurement of extensional forces during the pulling and tensile testing of the pulled fibers. The pulling device was used to study two types of silk—one recombinant spider silk (a structural variant of ADF3) and one regenerated silk fibroin. Also, dextran—a branched polysaccharide—was used as a reference material for the procedure due to its straightforward preparation and storage. No post-treatments were applied. The pulled regenerated silk fibroin fibers achieved high tensile strength in comparison to similar extrusion-based methods. The mechanical properties of the recombinant spider silk fibers seemed to be affected by the liquid-liquid phase separation of the silk proteins.

The wolf spider Pardosa milvina varies silk deposition in response to self and same‐sex conspecific silk

AbstractSilk is an important communication medium for spiders with roles in species recognition, sex identification, and mating status assessment. Spiders may benefit by discriminating between their own or another same‐sex conspecific's silk. Silk‐mediated self‐recognition could allow spiders to identify areas that they have previously visited, competitively block silk advertisements from sexual rivals or minimize redundant signaling in an area. Silk deposition behavior may also be contingent upon silk cues detected from same‐sex conspecifics. We tested if males and females of the wolf spider Pardosa milvina show different silk deposition patterns when encountering their own silk versus the silk of another spider of the same sex. Using a within‐between‐subjects design, we quantified male and female deposition of three silk types: draglines, cord silk, and attachment disks on substrates containing either their own silk or the silk of an adult same‐sex conspecific (N = 23 males, 28 females). Both males and females significantly increased dragline and cord silk deposition on substrates containing conspecific rather than their own silk with males producing more cord silk than females. Males significantly increased attachment disk deposition on conspecific male silk compared to their own while females showed the opposite response, decreasing attachment disk deposition on conspecific female silk. Both male and female P. milvina can recognize their own silk, but we found significant qualitative and quantitative sex differences in silk deposition suggesting sex‐specific functions for attachment disks compared to cord or dragline silk.

Utilization of Bioactive Silk Protein in the Development of Optical Devices: Recent Advancements and Applications.

Typically, materials used to create optical devices have chemical and physical properties that have been precisely designed for a narrowly defined purpose, allowing for changes in design to account for device variability. There is a growing need for devices built of materials with changeable optical responses, as optical systems are incorporated into platforms with much functionality. Regenerated silk fibroin is described in this article as an enabling gadget with an active optical response as a result of the inherent characteristics of proteins. Silk's capacity for controlled movement, to swell and shrink reversibly, alter conformation and degradation that is customizable, impacts both the shape and the response of the optical structure-representative silk-based gadgets. The diversity of silk material is shown and discussed in this paper, concentrating on architectures that show reconfigurable behavior, an optical waveguide that is physically temporary and provides reversible responses. Finally, innovative research directions for silk-based materials and optical devices are presented in this paper. Since ancient times, silk, a natural biopolymer, has been used as a repair material in medicine. In the past 20 years, it has attracted a lot of interest to be used in several biomedical applications. Various healthcare items with silk as their substrate have been developed thanks to significant advancements in silk biomaterial research. Silk is a fabric created from spider and silkworm cocoons. Hierarchical structures and conventional structural elements are present in them. Different silk types can be produced using certain methods, such as films, fibers, microspheres, sponges, and hydrogels. The structural characteristics of secondary proteins present in silk can also be modified. This paper investigates the use of silk in biomedical and optical applications, and examines the technical trend in electronic fields.

Microbiological Retention on PTFE versus Silk Suture: A Quantitative Pilot Study in Third Molar Surgery

Background: Mandibular third molar (M3M) removal and management of postoperative complications represent a common matter of interest in oral and maxillofacial surgery. This potential quantitative study assessed the ability of two types of surgical sutures, Silk and polytetrafluoroethylene polymer (PTFE), to carry aerobic and anaerobic bacteria on wounds after mandibular third molar surgery, with a collection of the stitches at the suture removal and study in the laboratory on the basis of colony-forming units. Methods: This prospective quantitative study sampled a total of 10 consecutive healthy patients for mandibular third molar surgery at the Oral Surgery School, Dentistry and Dental Prosthodontics, Department of Medical Biotechnologies, University of Siena, Siena, Italy. The mean age of the patients was 31 years (range 25-40 years), seven patients were male and three patients were female. Inclusion criteria were: presence of a partially impacted mandibular third molar. Exclusion criteria were: smoking and diabetes mellitus. Extraction of the mandibular third molar was performed under local anesthesia: after the third molar surgery, two sutures were applied on the surgical site distally to the second mandibular molar: one single 3/0 silk stitch; one single 3/0 PTFE stitch. No sutures were applied on the release incision. Sutures were removed after 7 days and were immediately conserved and sent to the laboratory to be rated on the basis of colony-forming units (CFUs). CFUs were evaluated and reported on GraphPad Prism and transformed into its base 10 logarithm. Data were analyzed with a non-parametric Wilcoxon test, and p-values < 0.05 were evaluated as statistically significant. Results: All the patients attended the suture removal date, and all the sutures were present in the site. None of the surgical sites presented dehiscence. No stitch loss was reported, and no patient reported mouth washing or tooth brushing in the surgery site. All interventions were uneventful and no major complications were reported after M3M surgery. Bacterial retention resulted as statistically greater in silk sutures rather than PTFE sutures, both in Brain Heart Infusion samples (p = 0.003) and Wilkins-Chalgren anaerobe samples (p = 0.002). Conclusions: We found the PTFE suture to be superior to the silk suture in a reduction in the bacterial biofilm in both aerobic and anaerobic evaluations after M3M surgery.

Crystallinity and Stiffness of Spider Silk Govern the Migration of Schwann Cells

Introduction: Nerve guidance conduits are a promising alternative to autologous nerve transplantation and conduits filled with fibrous materials have shown great potential in bridging nerve gaps. The application of spider silk as a filament material has led to results comparable to nerve autograft.1 However, the use of spider silk has been phenomenological so far and the reasons for its success are still not identified. The aim of this study is to elucidate the material properties of spider silk leading to its unique medical performance. This knowledge enables a targeted production of synthetic alternatives such as recombinant silk. Materials and Methods: In this work, various silk types were investigated.2 Schwann cells were seeded on the spider silks and monitored by live cell imaging and immunofluorescent staining. In addition, the silk fibers were inspected with an electron microscopy, Raman spectroscopy wide angle X-ray scattering, and tensile tests to determine morphology, secondary protein structure, crystallinity and stiffness, respectively. Results: It was found that the secondary protein structure and specifically the high content of β-sheets in the direction of silk’s axis gives the fiber its ability to act as a guiding element for Schwann cells. In addition, the results show that the crystallinity of the silk does not affect the proliferation of Schwann cells, while the directed movement of cells is affected by this material property. Conclusion: This direct comparison demonstrated the crucial role of the secondary protein structures and crystallinity of spider silk for the guidance properties of fibers during nerve regeneration. The crystalline structure of silk affects its stiffness, which in turn influences the directed migration of Schwann cells. These results should be considered during the targeted production of synthetic fibrous materials for nerve regeneration. 1. Kornfeld T, Nessler J, Helmer C, et al. Spider silk nerve graft promotes axonal regeneration on long distance nerve defect in a sheep model. Biomaterials 2021;271:120692. 2. Naghilou A, Pöttschacher L, Millesi F, et al. Correlating the secondary protein structure of natural spider silk with its guiding properties for Schwann cells. Mater Sci Eng C. 2020;116:111219.

Structural features, intrinsic disorder, and modularity of a pyriform spidroin 1 core repetitive domain.

Orb-weaving spiders produce up to seven silk types, each with distinct biological roles, protein compositions, and mechanics. Pyriform (or piriform) silk is composed of pyriform spidroin 1 (PySp1) and is the fibrillar component of attachment discs that attach webs to substrates and to each other. Here, we characterize the 234-residue repeat unit (the "Py unit") from the core repetitive domain of Argiope argentata PySp1. Solution-state nuclear magnetic resonance (NMR) spectroscopy-based backbone chemical shift and dynamics analysis demonstrate a structured core flanked by disordered tails, structuring that is maintained in a tandem protein of two connected Py units, indicative of structural modularity of the Py unit in the context of the repetitive domain. Notably, AlphaFold2 predicts the Py unit structure with low confidence, echoing low confidence and poor agreement to the NMR-derived structure for the Argiope trifasciata aciniform spidroin (AcSp1) repeat unit. Rational truncation, validated through NMR spectroscopy, provided a 144-residue construct retaining the Py unit core fold, enabling near-complete backbone and side chain 1H, 13C, and 15N resonance assignment. A six α-helix globular core is inferred, flanked by regions of intrinsic disorder that would link helical bundles in tandem repeat proteins in a beads-on-a-string architecture.

Silk-Based Biomaterials for Designing Bioinspired Microarchitecture for Various Biomedical Applications.

Biomaterial research has led to revolutionary healthcare advances. Natural biological macromolecules can impact high-performance, multipurpose materials. This has prompted the quest for affordable healthcare solutions, with a focus on renewable biomaterials with a wide variety of applications and ecologically friendly techniques. Imitating their chemical compositions and hierarchical structures, bioinspired based materials have elevated rapidly over the past few decades. Bio-inspired strategies entail extracting fundamental components and reassembling them into programmable biomaterials. This method may improve its processability and modifiability, allowing it to meet the biological application criteria. Silk is a desirable biosourced raw material due to its high mechanical properties, flexibility, bioactive component sequestration, controlled biodegradability, remarkable biocompatibility, and inexpensiveness. Silk regulates temporo-spatial, biochemical and biophysical reactions. Extracellular biophysical factors regulate cellular destiny dynamically. This review examines the bioinspired structural and functional properties of silk material based scaffolds. We explored silk types, chemical composition, architecture, mechanical properties, topography, and 3D geometry to unlock the body's innate regenerative potential, keeping in mind the novel biophysical properties of silk in film, fiber, and other potential forms, coupled with facile chemical changes, and its ability to match functional requirements for specific tissues.

Complete gene sequence and mechanical property of the fourth type of major ampullate silk protein.

Spiders spin a great diversity of silk types for daily survival and reproduction. Of the six orb-weaver silk types, the dragline silk forming orb web frame attracts the most attention because of its extremely high tensile strength and toughness. So far, four types of major ampullate silk proteins (MaSp1-4) that make up dragline silk have been identified. These MaSp types have diversified amino acid motifs that underlie the impressive mechanical property of dragline silk by forming particular structures. Existing knowledge of MaSp4 proteins is fragmented, making it difficult to illuminate the structure and function of MaSp4. Here, we report the full-length MaSp4 gene with 11,334 bp from the orb-weaving spider Araneus ventricosus. Removing the only intron, the spliced complete transcript of MaSp4 gene is 6897 bp and encodes 2298 amino acids. Analysis of the primary structure of A. ventricosus MaSp4 protein reveals the repetitive region lacks poly-A and GGX motifs but has the unique GPGPQ motifs. Quantitative real-time PCR analyses show high levels of MaSp4 mRNA were detected in major ampullate gland. Structural characterization using CD- and FTIR sepctroscopy reveals a mainly α-helical solution conformation and a very high β-turn content within fibers. Collectively, our new findings provide complete template for recombinant silk protein with specific properties and support that the GPGPQ motif found in MaSp4 could increase flexibility in dragline silk by packing in more β-turns, expanding the repertoire of sequences known to form β-turn that is available for artificial chimeric silk fibers. STATEMENT OF SIGNIFICANCE: Dragline silk forming orb web frame attracts the most attention because of its extremely high tensile strength and toughness. So far, four types of major ampullate silk proteins (MaSp1-4) that make up dragline silk have been identified. Existing knowledge of MaSp4 proteins is fragmented, making it difficult to illuminate the structure and function of MaSp4. Here, we report the full-length MaSp4 gene from the orb-weaving spider Araneus ventricosus. We further identify the sequence, structure, and mechanical property of MaSp4 protein, providing a new insight into the structure-funtion relationships associated with MaSp4. Collectively, our new findings provide complete template for recombinant silk protein with specific properties and support that the GPGPQ motif found in MaSp4 could increase flexibility in dragline silk by packing in more β-turns, expanding the repertoire of sequences known to form β-turn that is available for artificial chimeric silk fibers.

Physico-chemical properties of functionally adhesive spider silk nanofibres.

Currently, synthetic fibre production focuses primarily on high performance materials. For high performance fibrous materials, such as silks, this involves interpreting the structure-function relationship and downsizing to a smaller scale to then harness those properties within synthetic products. Spiders create an array of fibres that range in size from the micrometre to nanometre scale. At about 20 nm diameter spider cribellate silk, the smallest of these silks, is too small to contain any of the typical secondary protein structures of other spider silks, let alone a hierarchical skin-core-type structure. Here, we performed a multitude of investigations to elucidate the structure of cribellate spider silk. These confirmed our hypothesis that, unlike all other types of spider silk, it has a disordered molecular structure. Alanine and glycine, the two amino acids predominantly found in other spider silks, were much less abundant and did not form the usual α-helices and β-sheet secondary structural arrangements. Correspondingly, we characterized the cribellate silk nanofibre to be very compliant. This characterization matches its function as a dry adhesive within the capture threads of cribellate spiders. Our results imply that at extremely small scales there may be a limit reached below which a silk will lose its structural, but not functional, integrity. Nano-sized fibres, such as cribellate silk, thus offer a new opportunity for inspiring the creation of novel scaled-down functional adhesives and nano meta-materials.

Moth to Cloth: Silk in Africa

Moth to Cloth: Silk in Africa

Silk fibroin bioscaffold from Bombyx mori and Antheraea assamensis elicits a distinct host response and macrophage activation paradigm in vivo and in vitro

Biomaterials composed of silk fibroin from both mulberry and non-mulberry silkworm varieties have been investigated for their utility in tissue engineering and drug delivery, but these studies have largely excluded any evaluation of host immune response. The present study compares the macrophage activation response towards mulberry (Bombyx mori, BM) and non-mulberry (Antheraea assamensis, AA) silk types, individually and as a blend (BA) in a partial thickness rat abdominal wall defect model and in vitro primary murine bone marrow-derived macrophage (BMDM) assay. Biologic materials composed of liver extracellular matrix (LECM) and small intestinal submucosa (SIS) ECM that are recognized for constructive tissue remodeling, and polypropylene mesh that is associated with pro-inflammatory macrophage phenotype activation are used as controls in the animal model. The AA silk graft shows a host response similar to SIS with few foreign body multinucleate giant cells, vascularization, high CD206 expression, and high M2-like: M1-like macrophage phenotype ratio. Exposure to AA silk degradation products in vitro induces a higher arginase: iNOS ratio in both naive BMDM and pro-inflammatory activated BMDM; and higher Fizz1: iNOS ratio in pro-inflammatory activated BMDM. These data suggest that the AA silk supports a pro-remodeling macrophage response with potential therapeutic applications.

Characterization of two full-length tubuliform silk gene sequences from Neoscona theisi reveals intragenic concerted evolution and multiple copies in genome

Orb-web weaving spiders use a variety of silk types for particular tasks, and each silk type is composed of at least two spider silk proteins (spidroins). In the early stage of divergence, however, the molecular evolutionary processes act on spidroin variants are still unclear because of a lack of knowledge for full-length paralogous and orthologous gene sequences among closely related species. Here, we present two complete gene sequences encoding the tubuliform spidroin TuSp1 variants (TuSp1-v2 and TuSp1-v3) from orb-weaving spider Neoscona theisi. Both N. theisi TuSp1-v2 and TuSp1-v3 genes contain a single enormous exon (14,139 bp for TuSp1-v2 and 13,152 bp for TuSp1-v3) and dozens of tandemly arrayed repeats (25 repeats for TuSp1-v2 and 23 repeats for TuSp1-v3) with extreme intragenic homogenization. The pattern of expression for these two spidroins revealed that the level of TuSp1-v3 mRNA is ~3-fold higher than that of TuSp1-v2 in tubuliform gland. Phylogenetic analyses of spidroins not only show the occurrence of a gene duplication event for TuSp1-v2 and TuSp1-v3 in the common ancestor of the Neoscona and Araneus lineage but reinforce the role of concerted evolution for the extreme homogenization of TuSp1 repeats.

Biomedical applications of silk and its role for intervertebral disc repair.

Intervertebral disc (IVD) degeneration (IDD) is the main contributor to chronic low back pain. To date, the present therapies mainly focus on treating the symptoms caused by IDD rather than addressing the problem itself. For this reason, researchers have searched for a suitable biomaterial to repair and/or regenerate the IVD. A promising candidate to fill this gap is silk, which has already been used as a biomaterial for many years. Therefore, this review aims first to elaborate on the different origins from which silk is harvested, the individual composition, and the characteristics of each silk type. Another goal is to enlighten why silk is so suitable as a biomaterial, discuss its functionalization, and how it could be used for tissue engineering purposes. The second part of this review aims to provide an overview of preclinical studies using silk-based biomaterials to repair the inner region of the IVD, the nucleus pulposus (NP), and the IVD's outer area, the annulus fibrosus (AF). Since the NP and the AF differ fundamentally in their structure, different therapeutic approaches are required. Consequently, silk-containing hydrogels have been used mainly to repair the NP, and silk-based scaffolds have been used for the AF. Although most preclinical studies have shown promising results in IVD-related repair and regeneration, their clinical transition is yet to come.

Spider silk as a potential antibiotic substitute

Studies were undertaken on the antibacterial activity of spider silk against bacterial strains, using egg case silk of Parawixia dehaani (Doleschall, 1859) and web silk of Pholcus phalangioides (Fuesslin, 1775). Both silk types inhibited gram negative bacteria more than gram positive bacteria. The egg case silk of P. dehaani showed more antimicrobial activity than the web silk of P. phalangioides. The egg case silk brought about 26.05 per cent inhibition against E. coli, compared to a 22.7 per cent inhibition for B. subtilis. A linear association was found between the volume of silk extract and the percentage of inhibition.The percentage of inhibition against E. coli increased from 5.13 to 26.05 per cent as the volume rose from 20 to 100 µl. in P. dehaani.

Exploration of the protein conformation and mechanical properties of different spider silks

To analyze the protein conformation and mechanical properties of what types of spider silks, web frame silks from spiders of five different families, Parawixia dehaani (P. dehaani), Herennia ornatissima (H. ornatissima), Nephilengys malabarensis (N. malabarensis), Hippasa lycosina (H. lycosina) and Macrothele bannaensis (M. bannaensis), were investigated by tensile testing, Raman spectroscopy and X-ray diffraction. The order of the fracture strength or breaking force (H. ornatissima > N. malabarensis > P. dehaani, H. lycosina > M. bannaensis) is in accordance with the order of the Raman intensity ratios or crystallinity, the order of the extensibility (H. ornatissima < N. malabarensis < P. dehaani) is inversely proportional to the order of the degree of orientation of the β-sheets, which verify the theory that mechanical properties of silk mainly depends on protein conformation. Meanwhile, the Raman spectra of the web frame silks from four Araneidae spiders (Gasteracantha diadesmia, Gasteracantha kuhli, Macracantha arcuata and P. dehaani) and two Tetragnathidae spiders (Leucauge tessellata and H. ornatissima) show that the slight spectral differences might enable preliminary identification and classification of spiders. We believe that researching either the relationship between or individual performance of the mechanical properties and structures of various types of spider silks would benefit the utilization of silks as biomaterials and the classification of spider silks.

The evolutionary history of cribellate orb-weaver capture thread spidroins

BackgroundSpiders have evolved two types of sticky capture threads: one with wet adhesive spun by ecribellate orb-weavers and another with dry adhesive spun by cribellate spiders. The evolutionary history of cribellate capture threads is especially poorly understood. Here, we use genomic approaches to catalog the spider-specific silk gene family (spidroins) for the cribellate orb-weaver Uloborus diversus.ResultsWe show that the cribellar spidroin, which forms the puffy fibrils of cribellate threads, has three distinct repeat units, one of which is conserved across cribellate taxa separated by ~ 250 Mya. We also propose candidates for a new silk type, paracribellar spidroins, which connect the puffy fibrils to pseudoflagelliform support lines. Moreover, we describe the complete repeat architecture for the pseudoflagelliform spidroin (Pflag), which contributes to extensibility of pseudoflagelliform axial fibers.ConclusionsOur finding that Pflag is closely related to Flag, supports homology of the support lines of cribellate and ecribellate capture threads. It further suggests an evolutionary phase following gene duplication, in which both Flag and Pflag were incorporated into the axial lines, with subsequent loss of Flag in uloborids, and increase in expression of Flag in ecribellate orb-weavers, explaining the distinct mechanical properties of the axial lines of these two groups.

QS50. Elucidating the Reasons Behind the Success of Spider Silk In Nerve Regeneration

Purpose: The successful reconstruction of peripheral nerve injuries remains a major clinical challenge. Nerve guidance conduits are a promising alternative to autologous nerve transplantation and conduits filled with fibrous materials have shown great potential in bridging nerve gaps. The application of spider silk as a filament material for nerve guidance conduits has led to results comparable to nerve autograft. However, the use of spider silk has been phenomenological so far and the reasons for its success are still not identified. The aim of this study is to elucidate the material properties of spider silk leading to its unique medical performance. This knowledge enables a targeted production of synthetic alternatives such as recombinant silk. Methods: In this work, various silk types from golden orb weavers and tarantulas were investigated. In vitro experiments were conducted, and Schwann cells were seeded on the spider silks and monitored by live cell imaging. The extent of proliferation was analyzed by immunofluorescent staining and confocal microscopy. In addition, the silk fibers were inspected with an electron microscope for differences in their morphology and with Raman spectroscopy as well as wide angle X-ray scattering to determine their secondary protein structure and crystallinity. Results: It was found that the adhesion of Schwann cells on spider silk is independent of the size and morphology of fibers. However, the secondary protein structure and specifically the high content of β-sheets in the direction of silk’s axis gives the fiber its ability to act as a guiding element for Schwann cells. In addition, the results show that the crystallinity of the silk does not affect the proliferation of Schwann cells, while the directed movement of cells is affected by this material property. Conclusion: This direct comparison demonstrated the crucial role of the secondary protein structures and crystallinity of spider silk for the guidance properties of fibers during nerve regeneration. These results should be considered during the targeted production of synthetic fibrous materials for nerve regeneration.