title: Physical properties and structure of aquatic silk fiber from Stenopsyche marmorata.
abstract: To study the properties and structure of aquatic silk, nest-spinning hydropsychid caddisfly (Stenopsyche marmorata) larva were collected from a Japanese river and the silk glands were removed from the larva by dissecting and dried on the glass plate at room temperature. The silk fibers were obtained by removing fibrous materials, which the aquatic insects spun at the bottom of glass container and the microstructure and physical properties of aquatic silk protein fibres and their solid silk protein gland were evaluated. Silk fiber produced by the caddisfly larvae is composed of two filament embedded in a layer of glue. The results of Fourier transform infrared spectroscopy and X-ray diffraction measurements suggested the existence of binary structure containing random coil conformation and additional minor beta-molecular structure. Differential scanning calorimetry results are characterized by two broad endothermic transitions, at 230 degrees C and 320 degrees C, which corresponds to the decomposition of silk glue and silk fiber from caddis fly, respectively. The storage modulus (E') remained almost unchanged and nearly constant at above 60 degrees C until about 214 degrees C, where it began to show a sharp drop. A prominent relaxation peak appeared in the imaginary part of the modulus (loss peak at 230 degrees C), in response to the strong motional transitions exhibited by the silk fiber at this temperature. There was significant difference of tensile strength of single solid silk protein gland in dry and wet state. The results obtained are quite promising as a basis for possible future biotechnological and adhesive applications of aquatic silk.
authors.affiliation: Faculty of Textile Science and Technology, Shinshu University, Tokida 3-15-1, Ueda, Nagano 386-856, Japan. tsukada@shinshu-u.ac.jp
authors.forename: Masuhiro
authors.initials: M
authors.lastname: Tsukada
authors.forename: Md Majibur Rahman
authors.initials: MM
authors.lastname: Khan
authors.forename: Eiso
authors.initials: E
authors.lastname: Inoue
authors.forename: Goro
authors.initials: G
authors.lastname: Kimura
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Hun
authors.forename: Mitsuharu
authors.initials: M
authors.lastname: Mishima
authors.forename: Kimio
authors.initials: K
authors.lastname: Hirabayashi
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D018360:Crystallography, X-Ray; D004548:Elasticity; D007313:Insecta / Q000737:chemistry*; D007814:Larva; D055585:Physical Phenomena; D047011:Silk / Q000737:chemistry* / Q000648:ultrastructure; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D047011:Silk