Structure and molecular conformation of tussah silk fibroin films: Effect of methanol

Abstract

Structural changes of tussah (Antheraea pernyi) silk fibroin films treated with different water‐methanol solutions at 20°C were studied as a function of methanol concentration and immersion time. X‐ray diffraction measurements showed that the α‐helix structure, typical of untreated tussah films, did not change for short immersion times (2 min), regardless of methanol concentration. However, crystallization to β‐sheet structure was observed following immersion of tussah films for 30 min in methanol solutions ranging from 20 to 60% (v/v). IR spectra of tussah films untreated and methanol treated for 2 min exhibited strong absorption bands at 1265, 892, and 622 cm−1, typical of the α‐helix conformation. The intensity of the bands assigned to the β‐sheet conformation (1245, 965, and 698 cm−1) increased for the sample treated with 40% methanol for 30 min. Raman spectra of tussah films with α‐helix molecular conformation exhibited strong bands at 1657 (amide I), 1263 (amide III), 1106, 908, 530, and 376 cm−1. Following α → β conformational transition, amide I and III bands shifted to 1668, and to 1241, 1230 cm−1, respectively. The band at 1106 cm−1 disappeared and new bands appeared at 1095 and 1073 cm−1, whereas the intensity of the bands at 530 and 376 cm−1 decreased significantly. ©1995 John Wiley & Sons, Inc.

Structural and conformational changes of regeneratedAntheraea pernyi silk fibroin films treated with methanol solution

“…Considering the conformational structures of a native Antheraea pernyi fibroin film and regenerated fibroin film from lithium thiocyanate solution reported by others, 6,10 it can be concluded that the conformational structure of fibroin film was independent on the dissolution and preparation method and only dependent on the chemical composition of materials.…”

“…The effects of casting conditions on the molecular conformation of native Antheraea pernyi fibroin films were studied 7,8 and the influence of heat and methanol treatment on the molecular conformation was also investigated. 9,10 The aim of the present work is to prepare the regenerated Antheraea pernyi silk fibroin films from calcium nitrate solution and to investigate the structural and conformational changes of these films induced by immersion in methanol solution with different concentration and time. The X-ray diffraction (XRD) and infrared (IR) spectroscopic method were used for the analysis of the crystalline structure and molecular conformation.…”

A novel method to prepare tussah/Bombyx mori silk fibroin-based films

“…27 The pure TSF showed diffraction peaks at 16.5 , 20.5 and 24.5 corresponding to the spacing of 5.37Å, 4.33Å and 3.63Å, attributing to b-sheet. 38 From the IR analysis, we knew that the molecular interaction between BSF and TSF was absent or very weak. Consistent with these results, the diffraction of the blend lms (b-d) exhibited diffraction peaks' characteristic of BSF and TSF simply overlapping in Fig.…”

Structure of silk by raman spectromicroscopy: From the spinning glands to the fibers

“…Different parameters such as methanol, 63 temperature, 64 and pressure 65 were shown to induce the formation of b-sheets in silkworm silk. Other studies performed on B. mori fibroin samples provided useful band assignments of the silk I conformation (the native form found in the spinning dope) and random coil.…”