{"id":132494,"date":"2023-09-28T07:05:00","date_gmt":"2023-09-28T05:05:00","guid":{"rendered":"https:\/\/renewable-carbon.eu\/news\/?p=132494"},"modified":"2023-09-27T10:33:35","modified_gmt":"2023-09-27T08:33:35","slug":"high-strength-and-ultra-tough-whole-spider-silk-fibers-spun-from-transgenic-silkworms","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/high-strength-and-ultra-tough-whole-spider-silk-fibers-spun-from-transgenic-silkworms\/","title":{"rendered":"High-strength and ultra-tough whole spider silk fibers spun from transgenic silkworms"},"content":{"rendered":"\n\n\n<ul class=\"wp-block-list\" id=\"ulist0010\">\n<li><strong>The minimum basic structure model of silkworm silk (Fib-H<sub>12<\/sub>Fib-L<sub>12<\/sub>P25<sub>2<\/sub>) is proposed<\/strong><\/li>\n\n\n\n<li><strong>The first whole full-length spider silk fiber obtained by transgenic silkworms<\/strong><\/li>\n\n\n\n<li><strong>Bionic spider silk combines high strength (1,299 MPa) and super toughness (319\u00a0MJ\/m<sup>3<\/sup>)<\/strong><\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"secsectitle0025\">Progress and potential<\/h3>\n\n\n\n<p>Lightweight materials with super strength and toughness are highly sought after. Spider silk, a sustainable material, meets these requirements but faces challenges in commercialization due to scientific understanding of its spinning mechanism, technical complexities in the process, and engineering hurdles in low-cost mass production. Here, drawing inspiration from nylon and Kevlar, we propose a theory on the nature of toughness and strength, unveiling the basic structure of silk fibers. Using these theories, we successfully produce the first \u201clocalized\u201d full-length spider silk fiber via transgenic silkworms, showcasing high tensile strength (1,299 MPa) and exceptional toughness (319\u00a0MJ\/m<sup>3<\/sup>). This breakthrough overcomes scientific, technical, and engineering obstacles, paving the way for spider silk\u2019s commercialization as a sustainable substitute for synthetic fibers. Moreover, our theories provide essential guidance for developing super materials.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"secsectitle0010\">Summary<\/h3>\n\n\n\n<p>To advance ecological civilization, developing sustainable, eco-friendly high-strength and ultra-tough alternatives to non-sustainable synthetic fibers, such as nylon, is crucial. This necessitates a deeply scientific understanding of the fundamental determinants of fiber strength and toughness, as well as overcoming engineering challenges for cost-effective, large-scale production of high-performance&nbsp;silk fibers. Inspired by the mechanical properties of polyamide fibers, including nylon and Kevlar, we employed CRISPR-Cas9-mediated gene editing to successfully synthesize whole polyamide spider silk fibers from transgenic silkworms. These fibers exhibited impressive tensile strength (1,299 MPa) and toughness (319&nbsp;MJ\/m<sup>3<\/sup>), surpassing Kevlar\u2019s toughness 6-fold. Thus, they offer promising potential as sustainable alternatives to synthetic commercial fibers. Furthermore, our research provides valuable insights into the fundamental essence of fiber toughness and tensile strength, challenging the conventional notion that these properties are contradictory. These findings have significant implications for guiding the production of synthetic commercial fibers that simultaneously possess high strength and ultra-toughness.<\/p>\n\n\n<div class=\"wp-block-image is-style-default\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/renewable-carbon.eu\/news\/media\/2023\/09\/fx1_lrg.jpg\" alt=\"\" class=\"wp-image-132498\" style=\"width:572px;height:572px\" width=\"572\" height=\"572\" srcset=\"https:\/\/renewable-carbon.eu\/news\/media\/2023\/09\/fx1_lrg.jpg 996w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/09\/fx1_lrg-300x300.jpg 300w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/09\/fx1_lrg-150x150.jpg 150w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/09\/fx1_lrg-768x768.jpg 768w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/09\/fx1_lrg-270x270.jpg 270w\" sizes=\"auto, (max-width: 572px) 100vw, 572px\" \/><figcaption class=\"wp-element-caption\"><strong>\u00a9<\/strong> DOI:<a href=\"https:\/\/doi.org\/10.1016\/j.matt.2023.08.013\">https:\/\/doi.org\/10.1016\/j.matt.2023.08.013<\/a><\/figcaption><\/figure><\/div>\n\n\n<h3 class=\"wp-block-heading\" id=\"secsectitle0045\">Introduction<\/h3>\n\n\n\n<p>Wise investment in superior tools yields fruitful returns over time, underscoring the pivotal role of advanced materials in enhancing productivity and propelling the advancement of human civilization. For instance, the invention and widespread use of commercial synthetic fibers such as nylon and Kevlar have significantly contributed to the development of contemporary civilization.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib1\">1<\/a><\/sup> However, these synthetic fibers, including nylon, have become a double-edged sword, as their increasing usage poses a threat to sustainable development due to the depletion of fossil energy resources and environmental pollution.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib1\">1<\/a><\/sup> Therefore, there is an urgent need to develop green, environmentally friendly, sustainable alternatives with ultra-high strength and toughness to promote ecological civilization without compromising productivity. While significant advancements have been made in recent years in the field of polymer fiber science and technology, the exploration of truly high-strength and ultra-tough advanced fibers remains ongoing. Unfortunately, current theories suggest that the properties of tensile strength and toughness in engineering materials are mutually exclusive,<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib2\">2<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib3\">3<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib4\">4<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib5\">5<\/a><\/sup>\u00a0resulting in compromises in commercial synthetic fibers between the two properties.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib2\">2<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib3\">3<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib4\">4<\/a><\/sup>\u00a0For example, well-known fibers like nylon and Kevlar, both being polyamide fibers, exhibit a trade-off, with nylon possessing higher toughness, while Kevlar demonstrates superior tensile strength.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib6\">6<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib7\">7<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib8\">8<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib9\">9<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib10\">10<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib11\">11<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib12\">12<\/a><\/sup>\u00a0Thus, unraveling the underlying scientific challenge of combining fiber toughness and strength is crucial and unavoidable for the development of super materials that meet the growing industrial demands for high strength and ultra-toughness.<\/p>\n\n\n\n<p>The field of biomimetics, drawing inspiration from nature, has led to the efficient development of advanced materials and tools.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib13\">13<\/a><\/sup>\u00a0Natural polyamide fibers like silkworm silk and spider silk, particularly the latter, have long served as sources of inspiration for materials scientists.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib7\">7<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib13\">13<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib14\">14<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib15\">15<\/a><\/sup>\u00a0In fact, Jeffrey L. Yarger pointed out that nylon itself was inspired by silk fibers, both being polyamide fibers.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib16\">16<\/a><\/sup>\u00a0Spider silk exhibits higher tensile strength than nylon and greater toughness than Kevlar.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib6\">6<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib17\">17<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib18\">18<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib19\">19<\/a><\/sup>\u00a0Therefore, silk fibers from silkworms and spiders, possessing both high strength and exceptional toughness (unlike what is observed in engineering materials, where toughness and strength tend to be mutually exclusive), can serve as excellent research materials for deciphering the essence of toughness and strength.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib20\">20<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib21\">21<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib22\">22<\/a><\/sup>\u00a0Silk mechanical properties are determined by the quaternary structure, which is influenced by both the primary structure and the spinning process. Within silkworm silk fibers, glycine (Gly) and alanine (Ala) amino acids account for over 75% of the protein composition.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib23\">23<\/a><\/sup>\u00a0The repetitive sequence (Gly-Ala-Gly-X)n forms the \u03b2-sheet crystalline regions in silkworm silk fibers. In spider silk, \u03b2-sheet crystalline regions are formed by GGX (X\u00a0= A, Q, or Y), GX (X\u00a0= Q, A, or R), and polyalanine sequences.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib24\">24<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib25\">25<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib26\">26<\/a><\/sup>\u00a0These repetitive sequences in silk fibers, whether derived from silkworms or spiders, play a crucial role in determining their strength and toughness by facilitating the formation of \u03b2-sheet crystalline regions. It is noteworthy that despite relying on weak non-covalent interactions, such as hydrogen bonds,<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib27\">27<\/a><\/sup>\u00a0these \u03b2-sheet crystalline regions contribute significantly to the overall mechanical properties of silk fibers. Moreover, silkworm silk and spider silk align with the principles of sustainability and environmental friendliness, making them outstanding candidates to replace synthetic commercial fibers like nylon, thus promoting ecological civilization. However, achieving low-cost, large-scale production of mechanically robust fibers is crucial for their commercialization. However, silkworm silk, despite being the only animal protein fiber commercially produced on a large scale due to its low production cost, mostly restricts its application to the textile industry due to its limited mechanical performance. Spider silk, one of the strongest fibers, including commercial synthetic fibers, remains challenging to commercialize due to the cannibalistic nature of spiders, making large-scale silk production through rearing difficult. However, advancements in genetic engineering enable the expression of spider silk proteins via heterologous hosts and subsequent extrusion into spider silk\u00a0<em>in\u00a0vitro<\/em>.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib27\">27<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib28\">28<\/a><\/sup>\u00a0The mechanical properties of both silk and spider silk are determined by their protein quaternary structures, which are influenced by both primary protein structure and spinning processes.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib16\">16<\/a><\/sup>\u00a0However, due to an incomplete understanding of the spinning mechanisms<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib17\">17<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib29\">29<\/a><\/sup>\u00a0and the intrinsic nature of silk fiber toughness and strength yet to be unraveled,<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib16\">16<\/a><\/sup>\u00a0even the most advanced microfluidic spinning techniques fail to replicate the physicochemical environment required for natural silkworm silk and spider silk spinning.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib30\">30<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib31\">31<\/a><\/sup>\u00a0Consequently, most synthetic spider silk fibers currently available exhibit inferior mechanical properties in one or more aspects compared with their natural counterparts.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib16\">16<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib32\">32<\/a><\/sup>\u00a0Moreover, due to the inherent challenge of replicating the protective \u201ccuticle layer\u201d found in natural silk<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib33\">33<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib34\">34<\/a><\/sup> and spider silk,<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib17\">17<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib35\">35<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib36\">36<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib37\">37<\/a><\/sup>\u00a0the maintenance duration of the mechanical properties in artificial spider silk and regenerated silk fibers is significantly shorter compared with their natural counterparts. In fact, in our laboratory, wet-spun spider silk experiences a significant decline in mechanical properties within a few weeks. This is another critical factor that impedes the commercialization of artificial spider silk, a factor that is often overlooked by researchers. Therefore, addressing the aforementioned scientific and engineering challenges is essential for realizing silkworm silk or spider silk as alternatives to advanced commercial fibers like nylon and fostering the development of ecological civilization.<\/p>\n\n\n\n<p>The silk glands of domestic silkworms and spider silk glands exhibit remarkably similar physicochemical environments.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib38\">38<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib39\">39<\/a><\/sup>\u00a0Therefore, by leveraging the high-density cultivation of domestic silkworms for spider silk production, we can overcome the scientific challenges associated with the yet-to-be-fully-deciphered spinning mechanism of spider silk and the technical hurdles in developing spinning processes. This approach also enables us to address the engineering obstacles involved in achieving low-cost, large-scale production of spider silk.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib40\">40<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib41\">41<\/a><\/sup>\u00a0Moreover, spider silk produced by domestic silkworms retains the cuticle layer, allowing it to maintain its mechanical properties over an extended period,<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib33\">33<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib34\">34<\/a><\/sup>\u00a0thereby facilitating the commercialization of spider silk fibers. However, even with the use of genetically modified domestic silkworms for spider silk production, the fundamental scientific question regarding the strength and toughness of silk fibers cannot be circumvented. This fundamental question has been a significant factor preventing previous studies utilizing genetically modified silkworms from surpassing the comprehensive mechanical performance of natural spider silk.<sup><a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib40\">40<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib41\">41<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib42\">42<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib43\">43<\/a>,<a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6#bib44\">44<\/a><\/sup>\u00a0Only by unraveling the essence of strength and toughness and using it as guidance, through the \u201clocalization\u201d of spider silk proteins within silkworm silk glands, can we enable the spider silk proteins to adapt to the silkworm glands. This approach will allow us to produce high-performance spider silk using domestic silkworms and achieve true commercialization with low-cost, large-scale production, leveraging genetically modified silkworms.<\/p>\n\n\n\n<p>Here, drawing inspiration from the contrasting mechanical properties of nylon and Kevlar, both of which are polyamide fibers, we propose a theoretical framework that elucidates the fundamental factors determining fiber toughness and strength. Subsequently, employing a homology modeling approach, we introduce a novel minimal structural model for silk. This model is applicable for explaining and predicting the mechanical performance differences between silkworm silk and spider silk, both of which are polyamide fibers. Additionally, it guides the localization of spider silk proteins within domestic silkworm silk glands. Subsequently, we employed CRISPR-Cas9-mediated silk spinning in silkworms to successfully generate complete full-length spider silk fibers. This achievement serves as confirmation of our theory and yields spider silk fibers with both high strength and ultra-toughness. Scientific theories should not only possess testability but should also offer falsifiable predictions. Consequently, we confirm the validity of our theory by demonstrating its accurate predictions through the verification of phenomena from two distinct perspectives. This work resolves the scientific, technical, and engineering challenges that hinder the commercialization of high-performance spider silk. It holds the potential to replace commercial synthetic fibers such as nylon with spider silk, thereby promoting sustainable and environmentally friendly development within the realm of ecological civilization.<\/p>\n\n\n\n<p>The whole article you may read under <a href=\"https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/www.cell.com\/matter\/fulltext\/S2590-2385(23)00421-6<\/a><\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Progress and potential Lightweight materials with super strength and toughness are highly sought after. Spider silk, a sustainable material, meets these requirements but faces challenges in commercialization due to scientific understanding of its spinning mechanism, technical complexities in the process, and engineering hurdles in low-cost mass production. Here, drawing inspiration from nylon and Kevlar, we [&#8230;]<\/p>\n","protected":false},"author":105,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","nova_meta_subtitle":"Unraveled the fundamental factors governing material toughness and strength","footnotes":""},"categories":[5572],"tags":[11786,12810,10630,13481,13831],"supplier":[22813,9720,22814],"class_list":["post-132494","post","type-post","status-publish","format-standard","hentry","category-bio-based","tag-biofibres","tag-fibers","tag-hydrogen","tag-polyamide","tag-spidersilk","supplier-cellpress-journal-matter","supplier-donghua-university","supplier-southwest-university-in-chongqing"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/132494","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/105"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=132494"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/132494\/revisions"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=132494"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=132494"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=132494"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=132494"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}