Silkworms with Spider Silklike Fibers Using Synthetic Silkworm Chow Containing Calcium Lignosulfonate, Carbon Nanotubes, and Graphene

Abstract

Silkworm silk has become increasingly relevant for material applications. However, the industry as a whole is retracting because of problems with mass production. One of the key problems is the inconsistent properties of the silk. A means by which to improve the silk material properties is through enhanced sericulture techniques. One possible technique is altering the feed of the silkworms to include single-wall carbon nanotubes (SWNTs) or graphene (GR). Recently published results have demonstrated substantial improvement in fiber mechanical properties. However, the effect of the surfactant used to incorporate those materials into the feed on the fiber mechanical properties in comparison to normal silkworm silk has not been studied or reported. Thus, the total effect of feeding the SWNT and GR in the presence of surfactants on silkworms is not understood. Our study focuses on the surfactant [calcium lignosulfonate (LGS)] and demonstrates that it alone results in appreciable improvement of mechanical properties in comparison to nontreated silkworm silk. Furthermore, our study demonstrates that mixing the LGS, SWNT, and GR directly into the artificial diet of silkworms yields improved mechanical properties without decline below the control silk at high doses of SWNT or GR. Combined, we present evidence that mixing surfactants, in this case LGS, directly with the diet of silkworms creates a high-quality fiber product that can exceed 1 GPa in tensile strength. With the addition of nanocarbons, either SWNT or GR, the improvement is even greater and consistently surpasses control fibers. However, feeding LGS alone is a more economical and practical choice to consistently improve the mechanical properties of silkworm fiber.

Artificial spider silk from ion-doped and twisted core-sheath hydrogel fibres

“…This toughness is comparable to that of natural spider silks, which ranges from 160 to 350 MJ m −3 according to the type of silk 12,30,31 . This unique toughness is superior to those of existing hydrogel materials 32–37 and synthetic fibres including carbon fibre (25 MJ m −3 ) 12,30 , polyethylene (30 MJ m −3 ) 31 , Kevlar 49 (50 MJ m −3 ) 12,30,31 and nylon 6, 6 (80 MJ m −3 ) 12,30 and is close to those of the silk-protein-based fibres (334 MJ m −3 ) 38,39 and silk protein/CNT composite fibres (290 MJ m −3 ) 16,40 (Fig. 2d).…”

Synthesis and Processing of Nanomaterials Mediated by Living Organisms

“…The usual approach is wet impregnation (via spraying or spreading) of their natural food, mulberry leaves (Figure 3 a,b). In some cases, a xenobiotic supplement is added to an artificial chow (made from mulberry leaf powder mixed with other vegetable powders) [44–47] since the blending with additives is simpler and more controllable. There is one noteworthy example in which the silkworms are fed by intravascular injection, [48] claimed as an exact intake and equal amongst all silkworms, without negative effects.…”

“…While graphene nanoplatelets or graphene oxide (GO) lead to modest to poor mechanical improvements (Figure 3 c,d), graphene quantum dots (GQDs) have demonstrated their superiority in silk reinforcement, even at very low doses [48, 53] . Such is the increase in mechanical properties granted by some carbon‐based NMs, that their feeding to silkworms has been regarded as a way to upgrade properties of silkworm silk to that of spider silk [45, 50] . Complementary to the mechanical upgrade, carbon‐based NMs may also provide novel functional properties to the silk, such as electrical conductivity, [50] a better graphitization after pyrolysis, [51, 52] or the emergence of a highly stable fluorescence [46, 48, 55] .…”

Thermochromic Silks for Temperature Management and Dynamic Textile Displays

“…To this end, different approaches have been studied, and feeding silkworm with functional components has been reported as the most direct way [ 6 , 7 ]. Carbon nanotubes [ 8 , 9 ], graphene [ 8 , 10 ], silver nanoparticles [ 11 ], metal oxide nanoparticles [ 12 – 14 ], aggregation-induced emission nanoparticles [ 15 ], and organic dyestuffs [ 16 – 18 ] have been fed to the fifth instar silkworm toward producing silk cocoons with functional nanocomponents. However, the metabolic pathway of the silkworm larva is through the digestive system [ 19 ], which is a more or less straight tube leading from the mouth to the anus.…”