Lessons from silkworm cocoons for future protective materials design

 Evolved over millions of years’ natural selection, very thin and lightweight wild silkworm cocoons can protect silkworms from environmental hazards and physical attacks from predators while supporting their metabolic activity. The knowledge of structure-property-function relationship of multi-layered composite silk cocoon shells gives insight into the design of next-generation protection materials. The mechanical and thermal insulation properties of both domestic (Bombyx mori, or B. moriand Samia. cynthia, or S. cynthia) and wild (Antheraea pernyi and Antheraea mylitta, or A. pernyi and A. mylitta) silkworm cocoons were investigated. The research findings are of relevance to the bio-inspired design of new protective materials and structures.
The 180 degree peel tests and needle penetration tests were used for examining the peel resistance and needle penetration resistance of both domestic and wild silkworm cocoon walls. The temperatures inside and outside of the whole silkworm cocoons under warm, cold and windy conditions were monitored for investigating the cocoon’s thermal insulation function. Computational fluid dynamics (CFD) models were created to simulate the heat transfer through the A. pernyi cocoon wall.
The wild cocoons experienced much higher peeling peak loads than the domestic cocoon. This transfers to a maximum work-of-fracture (WOF) of about 1000 J/m2 from the A. pernyi outer layer, which was 10 times of the B. mori cocoon. The A. pernyi wild cocoon exhibited a maximum penetration force (11 N) that is 70 % higher than a woven aramid fabric. Silk sericin is shown to play a critical role in providing needle penetration resistance of the non-woven composite cocoon structure by restricting the relative motion of fibres, which prevents the sharp tip of the needle from pushing aside fibres and penetrating between them. The wild A. pernyi cocoon exhibits superior thermal buffer over the domestic B. mori cocoon. The unique structure of the A. pernyi cocoon wall with mineral crystals deposited on the cocoon outer surface, can prohibit most of the air from flowing inside of the cocoon structure, which shows strong wind resistance under windy conditions.

Características morfo-anatômicas e bromatológicas de folhas de amoreira em relação às preferências do bicho-da-seda

O objetivo deste trabalho foi avaliar, quantitativamente, as características morfo-anatômicas e bromatológicas das folhas de dez cultivares de amoreira, e estabelecer as relações de preferência do bicho-da-seda, por essas cultivares. Foram coletadas as folhas superior (5ª) e mediana (15ª) da planta, contadas a partir do ápice. As cultivares foram comparadas pelos métodos estatísticos multivariados de análise de agrupamento e análise de componentes principais. As cultivares Korin, Calabresa, IZ 5/2 e IZ 15/7 foram consideradas as mais recomendáveis para a alimentação das lagartas do bicho-da-seda, pois apresentaram valores altos de porcentagem de folha consumida, atribuídos à ocorrência de características desejáveis nas folhas, tais como menor teor de fibra bruta, menor quantidade de idioblastos de cistólito e de mucilagem, menor proporção de epiderme e maior de parênquima, comparativamente, às outras cultivares estudadas. As cultivares IZ 13/6 e IZ 57/2 foram consideradas as menos recomendáveis. As demais cultivares comportaram-se como intermediárias na preferência do bicho-da-seda.

Desenvolvimento e produção de seda do Bombyx mori L. exposto a análogos do hormônio juvenil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Silk Fibroin: a biopolymer platform for innovative pharmaceutical formulation and biomedical devices.

The protein silk fibroin (SF) from the silkworm Bombyx mori is a FDA-approved biomaterial used over centuries as sutures wire. Importantly, several evidences highlighted the potential of silk biomaterials obtained by using so-called regenerated silk fibroin (RSF) in biomedicine, tissue engineering and drug delivery. Indeed, by a water-based protocol, it is possible to obtain protein water-solution, by extraction and purification of fibroin from silk fibres. Notably, RSF can be processed in a variety of biomaterials forms used in biomedical and technological fields, displaying remarkable properties such as biocompatibility, controllable biodegradability, optical transparency, mechanical robustness. Moreover, RSF biomaterials can be doped and/or chemical functionalized with drugs, optically active molecules, growth factors and/or chemicals In this view, activities of my PhD research program were focused to standardize the process of extraction and purification of protein to get the best physical and chemical characteristics. The analysis of the chemo-physical properties of the fibroin involved both the RSF water-solution and the protein processed in film. Chemo-physical properties have been studied through: vibrational (FT-IR and Raman-FT) and optical (absorption and emission UV-VIS) spectroscopy, nuclear magnetic resonance (1H and 13C NMR), thermal analysis and thermo-gravimetric scan (DSC and TGA). In the last year of my PhD, activities were focused to study and define innovative methods of functionalization of the silk fibroin solution and films. Indeed, research program was the application of different methods of manufacturing approaches of the films of fibroin without the use of harsh treatments and organic solvents. New approaches to doping and chemical functionalization of the silk fibroin were studied. Two different methods have been identified: 1) biodoping that consists in the doping of fibroin with optically active molecules through the addition of fluorescent molecules in the standard diet used for the breeding of silkworms; 2) chemical functionalization via silylation.

Mechanical behaviour and formation process of silkworm silk gut

High performance silk fibers were produced directly from the silk glands of silkworms ("Bombyx mori") following an alternative route to natural spinning. This route is based on a traditional procedure that consists of soaking the silk glands in a vinegar solution and stretching them by hand leading to the so called silkworm guts. Here we present, to the authors’ best knowledge, the first comprehensive study on the formation, properties and microstructure of silkworm gut fibers. Comparison of the tensile properties and microstructural organization of the silkworm guts with those of naturally spun fibers allows gain of a deeper insight into the mechanisms that lead to the formation of the fiber, as well as the relationship between the microstructure and properties of these materials. In this regard, it is proved that an acidic environment and subsequent application of tensile stress in the range of 1000 kPa are sufficient conditions for the formation of a silk fiber.

Purification and molecular cloning of an inducible gram-negative bacteria-binding protein from the silkworm, Bombyx mori.

A 50-kDa hemolymph protein, having strong affinity to the cell wall of Gram(-) bacteria, was purified from the hemolymph of the silkworm, Bombyx mori. The cDNA encoding this Gram(-) bacteria-binding protein (GNBP) was isolated from an immunized silkworm fat body cDNA library and sequenced. Comparison of the deduced amino acid sequence with known sequences revealed that GNBP contained a region displaying significant homology to the putative catalytic region of a group of bacterial beta-1,3 glucanases and beta-1,3-1,4 glucanases. Silkworm GNBP was also shown to have amino acid sequence similarity to the vertebrate lipopolysaccharide receptor CD14 and was recognized specifically by a polygonal anti-CD14 antibody. Northern blot analysis showed that GNBP was constitutively expressed in fat body, as well as in cuticular epithelial cells of naive silkworms. Intense transcription was, however, rapidly induced following a cuticular or hemoceolien bacterial challenge. An mRNA that hybridized with GNBP cDNA was also found in the l(2)mbn immunocompetent Drosophila cell line. These observations suggest that GNBP is an inducible acute phase protein implicated in the immune response of the silkworm and perhaps other insects.

Yu zhi geng zhi tu,

Mode of access: Internet.

Annuario.

v.43 out of print.

De l'éducation des vers à soie en Chine /

Mode of access: Internet.

Indian museum notes.

CONTENTS.--vol. I, no. 1. Notes on Indian insect pests. 1889. no. 2. Notes on Indian economic entomology. 1889. no. 3. Silkworms in India. 1890. no. 4. Notes on Indian economic entomology. 1890.--vol. II, no. 1. Economic entomology. 1891. no. 2. The wild silk insects of India. 1891. no. 3. On white insect wax in India. 1891. no. 4. The locusts of Bengal, Madras, Assam, and Bombay. 1891. no. 5. [Economic entomology, etc.] 1891. no. 6. A conspectus of the insects which affect crops in India. 1893.--vol. III, no. 1-3. [Notes on Indian insect pests, etc.] 1893-94. no. 4. An account of the insects and mites which attack the tea plant in India. 1895. no. 5-6. [Entomological notes] 1894-96.--vol. IV-vol. VI, no. 1. [Notes on Indian insect pests] 1896-1903.

Dissertatio academica, de phalæna bombyce ... /

Also published in Linné's Amoenitates academicae, v. 4, ed. 1, 1759 (and 1760); ed. 2, 1788, p. 553-564. Translation: On the silk worm, Brand, Select diss., 1781, p. 437-456. cf. Hulth, Bibl. Linn. (1907) p. 105.

Account of the Tusseh and Arrindy silk-worms of Bengal /

Mode of access: Internet.

The art of rearing silk-worms.

Translation of Dell'arte de governare i bachi da seta.

Deutliche Anweisung, wie mit Säung des Maulbeer-Saamens : Pflanzung und Wartung der Maulbeer-bäume, desgleichen Wartung und Fütterung der Seiden-Würmer, auch Haspelung der feinen Seide ; Zubereitung der Flock-Seide, und dem wahren Gebrauch beider Arten Seide, vernünftig und mit Vertheil zu verfahren sey. Nach vieljähriger Untersuchung und mancherley gemachten Proben, zum Besten des gemeinen Wesens an das Licht gestellet, von einem Liebhaber des Seiden-Baues.

Deutliche Anweisung, wie mit Säung des Maulbeer-Saamens (67 p.)-- Kurze nachricht, von Haspelung der feinen Seide, von Zubereitung der Flock-Seide, und vom Gebrauch bender Arten Seide, 1750 (262, [10] p.)-- Kurze abhandlung von dem seidenbau in Berlin und churmark Brandenburg, 1756 (14 p.).

Woodland Cottage, or, Henry and Emma Acton's conversations to their children, on the animal and vegetable world. /

Publisher's advetisements on back cover.