Synthetic Silk Research Articles

High‐resolution NMR characterization of a spider‐silk mimetic composed of 15 tandem repeats and a CRGD motif

Multidimensional solution NMR spectroscopic techniques have been used to obtain atomic level information about a recombinant spider silk construct in hexafluoro-isopropanol (HFIP). The synthetic 49 kDa silk-like protein mimics authentic silk from Nephila clavipes, with the inclusion of an extracellular matrix recognition motif. 2D (1)H-(15)N HSQC NMR spectroscopy reveals 33 cross peaks, which were assigned to amino acid residues in the semicrystalline repeat units. Signals from the amorphous segments in the primary sequence were weak and broad, suggesting that this region is highly dynamic and undergoing conformational exchange. An analysis of the deviations of the (13)C(alpha), (13)C(beta), and (13)CO chemical shifts relative to the expected random coil values reveals two highly alpha-helical regions from amino acid 12-19 and 26-32, which comprise the polyalanine track and a GGLGSQ sequence. This finding is further supported by phi-value analysis and sequential and medium-range NOE interactions. Pulsed field gradient NMR measurements indicate that the topology of the silk mimetic in HFIP is nonglobular. Moreover, the 3D (15)N-NOESY HSQC spectrum exhibits few long-range NOEs. Similar spectral features have been observed for repeat modules in other polypeptides and are characteristic of an elongated conformation. The results provide a residue-specific description of a silk sequence in nonaqueous solution and may be insightful for understanding the fold and topology of highly concentrated, stable silk before spinning. Additionally, the insights obtained may find application in future design and large-scale production and storage of synthetic silks in organic solvents.

A novel methodology to explore the viscoelasticity of spider major ampullate silk.

Even before material science was a recognized discipline, the amazing mechanical properties of spider silk were documented and became the object of much study. In addition to the exceptional material properties of spider silk and the reported low immunogenicity, its concatenated amino acid motif arrangement facilitates a distinct possibility of manipulating the silk to create a designer biomaterial for medical applications. Crystalline protein regions imbedded in a mobile protein matrix give it a distinct set of viscoelastic abilities. Consequently, elasticity cannot be simply quantified by only measuring extensibility. To understand how the sequence of the major ampullate proteins affects elasticity, the hysteresis of single fibers from two different species, Argiope aurantia and Nephila clavipes, were examined using cyclic loading and unloading. The yield point that discriminates a transition from elastic extension to a plastic extension was analyzed by examining three different properties: Young's modulus, energy recovery and slack in the fiber after recovery. Young's modulus remained relatively constant regardless of the cycle. However, the energy recovered decreased as the slack and cycle number increased. Large standard deviations masked any quantitative differences between species and substantiated the necessity of developing synthetic silk to harness the amazing mechanical properties of spider silk.

Investigation on the seam's quality by sewing of light fabrics

PurposeThis paper aims to define the dominating factors having influence on the quality of the seam by sewing of fine fabrics and their optimum values.Design/methodology/approachTen factors defining a seam's quality are chosen on the base of literary research. There was a check for concurrence of specialists' opinions, as the Spearman's coefficient of concordance was determined. A designed experiment with variation of the first three of the arranged factors was made. Mathematical models for the tensile and the aesthetical properties of the seam were devised, and also optimization made.FindingsA classification of the properties, defining seam's quality, is made. A cause‐effect diagram of Ishikawa with aiming parameter – quality of the seam – has been developed. On the basis of a survey the factors that have a great deal of influence on it are presented. Mathematical models for seam's strength, elongation and smoothness are produced by changing the following factors: straining of the upper thread, size of the needle and load on the pressing foot are worked out. Received models are optimized.Research limitations/implicationsThe research was conducted using a sewing‐machine class 301. Received results and conclusions refer to seams made from base material – fabric from PES and sewing thread from 100 percent PE.Practical implicationsOptimum values have been established for the straining of the upper thread, the size of the needle and the load on the pressing foot by sewing of fabric from synthetic silk with mass applicable machines, needles, and sewing threads.Originality/valueThe research has been done in several directions: systemizing the seam's properties for evaluation of its quality and the factors defining it, inquiry into the significance of the different factors and implementation of a designed experiment. Consultations were made with a broad circle of specialists and these results are given in visual systems (schemes and graphs).

How Everyday Products Make People Sick: Toxins at Home and in the Workplace

By Paul D. Blanc Berkeley: University of California Press, 2007. 374 pp. ISBN: 0-520-24882-1, $19.95 Most individuals who are concerned with public health, specifically occupational and environmental health, have some awareness that the field did not begin with Rachel Carson, the London Fog, Irving Selikoff, or fevers from welding galvanized steel. In seven compelling chapters on the development, recognition, and unfortunately re-recognition of occupational and environmental disease, Paul Blanc, treats readers to a marvelous distillation of the side effects and misadventures of industrial development over the last 300 years, arguing that workers and consumers would be healthier if we learned from our past. Although the exact prescriptive balance between innovation and regulation is not, and probably could not be, explicitly presented, the book triumphs in its thorough explication of how so many modern technologies and their accompanying maladies developed, evolved, and redeveloped. Blanc deftly presents uncommon histories about common environmental agents, and weaves connections at the medical and industrial levels that provide glue for the bare facts. The chapter “Good Glue, Better Glue, Superglue” teaches us traditional glue making from animal collagen, and then detours to the development of magenta and other dyes from coal tar distillation, producing unwanted benzene. Blanc then describes the use of benzene as a solvent for rubber cement and its attendant effects on the bone marrow, and polymer sealants such as nitrocellulose dissolved in tetrachloroethane when benzene was diverted to munitions manufacture during World War I. Subsequently he describes the development and medical consequences of celluloid, plastic polymers such as Bakelite, polyvinyl chloride manufacture, toluene, hexane, acetontrile and artificial fingernails, and finally isocyanate adhesives. Along the way, the inadequacy of health regulation is discussed, as the Consumer Products Safety Commission receives particular attention for failing to act. And this is only the “glue” chapter. Other intriguing chapters detail the 18th-century origins of chlorine bleaching and chlorine’s use in industry and as a war gas, as well as carbon disulfide’s use in making synthetic silk (rayon) and vulcanizing rubber. “Job Fever” examines how the recognition of mill fevers in 18th-century England led to the recognition of byssinosis, now attributed to endotoxin exposure. From there Blanc makes the pathophysiologic (cytokine-mediated systemic inflammation) link to metal fume fevers, going back to ancient China for the origins of brass founding. “Emerging Toxins” discusses recently recognized causes of bronchiolitis obliterans (nylon flock, popcorn flavoring) and the effects of various wood treatments (mercuric chloride, creosote, chlorinated hydrocarbons, and copper–chromium arsenate). This chapter also discusses the gasoline additive organic lead and the currently contentious use of the organic manganese compound methylcyclopentadienyl manganese tricarbonyl as its replacement, despite concern for an association of manganese with Parkinson and other neurologic diseases. Briefer treatment is given to misadventures such as the manganese-based laundry bleach developed in Europe for cold-water washing that ate through clothes when used in predominantly hot-water U.S. washing machines. However, this book keeps its eye on human health effects, which are clearly presented for a nonmedical audience, the subtleties of organ dysfunction not being the focus of this extensively footnoted history. Readers are treated to contextual anecdotes about the players in many of these dramas, ranging from those who developed the technologies (e.g., Michael Faraday for mercuric chloride), to those who studied the conditions (e.g., Jean-Martin Charcot for carbon disulfide neurotoxicity), to multiple pitiable descriptions of the victims of industrial progress (e.g., Clara, the benzol worker). This book is highly recommended to occupational/industrial toxicologists, academic toxicologists, occupational physicians, environmental health scientists, and especially to those responsible for regulation in these fields at local, state, federal, or international levels. It will prove invaluable for those who seek to contextualize, illustrate, and personalize lectures to public health, toxicology, and other students. It also provides illuminating background information on the evolution of modern life. Unfortunately for its publisher, although the book may provide bon mots for dinner table conversation and the like, it may not gain as much traction for the domestic audience as its title suggests it was aimed to attract. This is not a prescriptive manual for how to make our homes safer. However, it does make a strong case that we need to improve our occupational, consumer, and environmental regulation, so that new technologies and new applications of older technologies are less often developed at the expense of health.

Solution behavior of synthetic silk peptides and modified recombinant silk proteins

Spider dragline silk from Nephila clavipes possesses impressive mechanical properties derived in part from repetitive primary sequence containing polyalanine regions that self-assemble into crystalline β-sheets. In the present study, we have sought to understand more details of redox responses related to conformational transitions of modified silk peptides and a recombinant protein containing encoded methionine triggers. Regardless of the position of the methionine trigger relative to the polyalanine domain, chemical oxidation was rapid and slight increases in the α-helical structure and decreases in the β-sheet and random coil content were observed by CD and FTIR in the assembled silk-like peptides and the recombinant protein. CD results indicated that the decrease in β-sheet and random coil conformations, coupled with the increase in helical content during oxidation, occurred during the first 30 min of the reaction. No further conformational changes occurred after this time and the response was independent of methionine trigger location relative to the penta-alanine domain. These results were confirmed with fluorescence studies. The design, processing and utility of these modified redox triggered silk-like peptides and proteins suggest a range of potential utility, from biomaterials to engineered surface coatings with chemically alterable secondary structure and, thus, properties.

Stability of neuropathic pain symptoms in partial sciatic nerve ligation in rats is affected by suture material

Many factors affect the development of neuropathic pain behavior in animal models. In this letter, we describe the differences in the development of neuropathic pain behavior observed when the partial sciatic nerve ligation (PNL) is performed with either a synthetic silk or chromic catgut ligation. To characterize nociceptive changes over time after surgery, neutral plate, hot plate, Von Frey, pinprick, acetone spray and cold plate testing was performed. The results indicated that a chromic catgut ligature caused cold allodynia, chemical hyperreactivity, mechanical hyperalgesia and hypersensitivity that remained present for the entire 56 days post-surgical observation period. With the synthetic silk ligature, comparable functional deficits were present in the initial phase after surgery, but several of these deficits diminished over time 21–28 days post-surgery. In conclusion, performing the PNL using chromic catgut suture thread gives rise to more robust sensory deficits than when synthetic silk is used. Therefore, the material that is used for the ligature in the partial sciatic ligation model has an effect on the outcome of the observed sensory abnormalities.

Spinning a good yarn

Making synthetic silk is more than a matter of creating the raw ingredients, as a new study reveals. You have to be a skilful spinner too.

Fashionable Ladies, Dada Dandies

In Berlin, as in Paris, London, and New York, skirts got shorter in the 1920s, exposing legs swathed in shiny, synthetic silk stockings. “Legs have emerged after centuries of shrouding, and adult woman at last frankly admits herself to be a biped … her ankles, calves, and knees (all the more dazzling in their suddenly revealed beauty after their long sojourn in the dark) [are] her chief erotic weapons,”1 wrote the psychoanalyst J. C. Flugel in his 1930 study, The Psychology of Clothes. After the First World War, Flugel argues, men's fashion did not keep pace with the modernization of women's wear. Tailors failed to answer demands for increased comfort, convenience, and cleanliness, and many men succumbed to cowardice and clubby conform-ism in refusing to give up their stuffy suits. Flugel's account of the attention to the limbs that characterized women's fashions of the 1920s was written al a moment when reactionary dressmakers and authorities on haute couture had already regrouped to launch a campaign aimed at lowering hemlines, and his text speaks in the name of the sartorial emancipation of both women and men.

Innovation in Polyester Fibers: From Silk-Like to New Polyester

In the past several years, "Shingosen," or new synthetic fibers have been developed in Japan. Polyester fibers and fabrics have attained a new status among other synthetic and natural fibers and textiles, and the Japanese have begun to recognize that recent polyester products are comparable to natural fibers such as silk. Shingosen is used typically in synthetic silk applications. The progress and relating key technologies for Shingosen production, which are focused on new silky textiles, are reviewed in this paper.

Multi-task machines for the manufacture of synthetic silk. Part II. Modification of monofilaments during their formation with multi-task machines

Multi-task machines for the manufacture of synthetic silk. Part II. Modification of monofilaments during their formation with multi-task machines

Multi-task machines for the manufacture of synthetic silk. Part 1. Recent advances in the integration of the manufacturing machines

Multi-task machines for the manufacture of synthetic silk. Part 1. Recent advances in the integration of the manufacturing machines

Synthetic Silk

Synthetic Silk