SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Silk

175

The role of predators in food webs extends beyond their ability to kill and consume prey. Such trait-mediated effects occur when signals of the predator influence the behaviour of other animals. Because all spiders are silk-producing carnivores, we hypothesized that silk alone would signal other arthropods and enhance non-lethal effects of spiders. We quantified the herbivory inflicted by two beetle species on green bean plants (Phaseolus vulgaris) in the presence of silkworm silk and spider silk along with no silk controls. Single leaflets were treated and enclosed with herbivores in the laboratory and field. Another set of leaflets were treated and left to experience natural herbivory in the field. Entire plants in the field were treated with silk and enclosed with herbivores or left exposed to herbivory. In all cases, the lowest levels of herbivory occurred with spider silk treatments and, in general, silkworm silk produced intermediate levels of leaf damage. These results suggest that silk may be a mechanism for the trait-mediated impacts of spiders and that it might contribute to integrated pest management programmes.

Concepts: Arachnid, Insect, Bean, Common bean, Silk, Spider, Predation, Animal

162

Issues of surfaces, e.g., inspired from beetle’s back, spider silk, cactus stem, etc., become the active area of research on designing novel materials in need of human beings to acquire fresh water resource from air. However, the design of materials on surface structure is little achieved on controlling of micro-scale drop transport in a long distance. Here, we report the ability of micro-drop transport in a long distance on a bioinspired Fibers with Gradient Spindle-knots (BFGS), which are fabricated by tilt angle dip-coating method. The micro-drop of ~0.25 μL transports in distance of ~5.00 mm, with velocity of 0.10-0.22 m s(-1) on BFGS. It is attributed to the multi-level cooperation of the release energy of drop coalescence along the gradient spindle-knots, in addition to capillary adhesion force and continuous difference of Laplace pressure, accordingly, water drops are driven to move fast directionally in a long distance on BFGS.

Concepts: Silk, Surface, Addition, Spider silk, Transport, Water, Water resources, Human

156

Disperse dyes, which are used for colouring synthetic textile fibres, are well-known contact sensitisers. To investigate the outcome of patch-testing with a textile dye mix (TDM) at 7 dermatology clinics in Sweden, a TDM tested at 2 concentrations was included into the baseline series during one year. The mix consisted of Disperse (D) Blue 35, D Yellow 3, D Orange 1 and 3, D Red 1 and 17, all 1.0%, and D Blue 106 and D Blue 124, each 0.3% in the mix 6.6% and 1.0% each in the mix 8.0%. In 2,122 tested patients, contact allergy to the TDM 8.0% was found in 2.8% and to the TDM 6.6% in 2.5% of the patients. The contact allergy to the TDM could explain or contribute to the dermatitis in about 35% of the patients. Conclusion: contact allergy to the TDM is common and inclusion into the Swedish baseline series should be considered.

Concepts: Hospital, Silk, Hypersensitivity, Synthetic fiber, Aramid, Dermatitis, Contact dermatitis, Eczema

53

Pottery, bone implements, and stone tools are routinely found at Neolithic sites. However, the integrity of textiles or silk is susceptible to degradation, and it is therefore very difficult for such materials to be preserved for 8,000 years. Although previous studies have provided important evidence of the emergence of weaving skills and tools, such as figuline spinning wheels and osseous lamellas with traces of filament winding, there is a lack of direct evidence proving the existence of silk. In this paper, we explored evidence of prehistoric silk fibroin through the analysis of soil samples collected from three tombs at the Neolithic site of Jiahu. Mass spectrometry was employed and integrated with proteomics to characterize the key peptides of silk fibroin. The direct biomolecular evidence reported here showed the existence of prehistoric silk fibroin, which was found in 8,500-year-old tombs. Rough weaving tools and bone needles were also excavated, indicating the possibility that the Jiahu residents may possess the basic weaving and sewing skills in making textile. This finding may advance the study of the history of silk, and the civilization of the Neolithic Age.

Concepts: Mass spectrometry, Evidence law, Silk, Synoptic table of the principal old world prehistoric cultures, Bone, Textile, Stone Age, Neolithic

53

Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations.

Concepts: Spider, Carbon nanotube, Fiber, Materials science, Continuum mechanics, Tensile strength, Spider silk, Silk

37

Sensitive biological compounds, such as vaccines and antibiotics, traditionally require a time-dependent “cold chain” to maximize therapeutic activity. This flawed process results in billions of dollars worth of viable drug loss during shipping and storage, and severely limits distribution to developing nations with limited infrastructure. To address these major limitations, we demonstrate self-standing silk protein biomaterial matrices capable of stabilizing labile vaccines and antibiotics, even at temperatures up to 60 °C over more than 6 months. Initial insight into the mechanistic basis for these findings is provided. Importantly, these findings suggest a transformative approach to the cold chain to revolutionize the way many labile therapeutic drugs are stored and utilized throughout the world.

Concepts: Developing country, Silk, Drug, Storage, Stabilizer, Therapy, Phage therapy, Medicine

35

Naturally spun silks generate fibres with unique properties, including strength, elasticity and biocompatibility. Here we describe a microfluidics-based strategy to spin liquid native silk, obtained directly from the silk gland of Bombyx mori silkworms, into micron-scale capsules with controllable geometry and variable levels of intermolecular β-sheet content in their protein shells. We demonstrate that such micrococoons can store internally the otherwise highly unstable liquid native silk for several months and without apparent effect on its functionality. We further demonstrate that these native silk micrococoons enable the effective encapsulation, storage and release of other aggregation-prone proteins, such as functional antibodies. These results show that native silk micrococoons are capable of preserving the full activity of sensitive cargo proteins that can aggregate and lose function under conditions of bulk storage, and thus represent an attractive class of materials for the storage and release of active biomolecules.

Concepts: History of silk, Sericulture, Bombyx mandarina, Bombycidae, Bombyx, Molecular biology, Bombyx mori, Silk

35

Silkworm silk is gaining significant attention from both the textile industry and research society because of its outstanding mechanical properties and lustrous appearance. The possibility of creating tougher silks attracts particular research interest. Carbon nanotubes and graphene are widely studied for their use as reinforcement. In this work, we report mechanically enhanced silk directly collected by feeding Bombyx mori larval silkworms with single-walled carbon nanotubes (SWNTs) and graphene. We found that parts of the fed carbon nanomaterials were incorporated into the as-spun silk fibers, whereas the others went into the excrement of silkworms. Spectroscopy study indicated that nanocarbon additions hindered the conformation transition of silk fibroin from random coil/α-helix to β-sheet, which may contribute to increased breaking elongation and toughness modules. We further investigated the pyrolysis of modified silk, and a highly developed graphitic structure with obviously enhanced electrical conductivity was obtained through the introduction SWNTs and graphene. The successful generation of these SWNT- or graphene- embedded silks by in vivo feeding is expected to open up possibilities for the large-scale production of high strength silk fibers.

Concepts: Bombyx, Graphite, Bombycidae, Graphene, Carbon, Bombyx mori, Carbon nanotube, Silk

34

Silks are remarkable materials with desirable mechanical properties, yet the fine details of natural production remain elusive and subsequently inaccessible to biomimetic strategies. Improved knowledge of the natural processes could therefore unlock development of a host of bio inspired fibre spinning systems. Here, we use the Chinese silkworm Bombyx mori to review the pressure requirements for natural spinning and discuss the limits of a biological extrusion domain. This provides a target for finite element analysis of the flow of silk proteins, with the aim of bringing the simulated and natural domains into closer alignment. Supported by two parallel routes of experimental validation, our results indicate that natural spinning is achieved, not by extruding the feedstock, but by the pulling of nascent silk fibres. This helps unravel the oft-debated question of whether silk is pushed or pulled from the animal, and provides impetus to the development of pultrusion-based biomimetic spinning devices.The natural production of silks remains elusive and subsequently inaccessible to biomimetic strategies. Here the authors show that silks cannot be spun by pushing alone, and that natural spinning is dominated by pultrusion, which provides design guidelines for future biomimetic spinning systems.

Concepts: Sericulture, Bombyx mandarina, Bombyx, Bombycidae, Finite element method, Engineering, Silk, Bombyx mori

34

Natural materials are renowned for exquisite designs that optimize function, as illustrated by the elasticity of blood vessels, the toughness of bone and the protection offered by nacre. Particularly intriguing are spider silks, with studies having explored properties ranging from their protein sequence to the geometry of a web. This material system, highly adapted to meet a spider’s many needs, has superior mechanical properties. In spite of much research into the molecular design underpinning the outstanding performance of silk fibres, and into the mechanical characteristics of web-like structures, it remains unknown how the mechanical characteristics of spider silk contribute to the integrity and performance of a spider web. Here we report web deformation experiments and simulations that identify the nonlinear response of silk threads to stress–involving softening at a yield point and substantial stiffening at large strain until failure–as being crucial to localize load-induced deformation and resulting in mechanically robust spider webs. Control simulations confirmed that a nonlinear stress response results in superior resistance to structural defects in the web compared to linear elastic or elastic-plastic (softening) material behaviour. We also show that under distributed loads, such as those exerted by wind, the stiff behaviour of silk under small deformation, before the yield point, is essential in maintaining the web’s structural integrity. The superior performance of silk in webs is therefore not due merely to its exceptional ultimate strength and strain, but arises from the nonlinear response of silk threads to strain and their geometrical arrangement in a web.

Concepts: Spider web, Spinneret, Elasticity, Spider, Silk, Linear elasticity, Tensile strength, Spider silk