Impact of Temperature on the Stability of Silkworm Cocoon Fibers

Abstract

In this study raw and processed silkworm (Bombyx mori) cocoons were investigated using confocal Raman spectroscopy in conjunction with differential scanning calorimetry (DSC) in order to examine the effect of temperature on the molecular conformation of silk fiber structures. Using DSC, a broad endothermic curve was observed at moderate temperatures, shedding light on the vaporization of both raw and processed cocoons, a phenomenon that could also indicate a strong interaction between silk fibroin and water molecules. Over the temperature range set for this study, Raman spectra of raw and processed cocoons were compared at different excitation radiations after drying both kinds of cocoon in an oven at 80 and 125 ºC for 60 minutes. By correlating the intensity ratios of the deconvoluted Raman bands using the broad bands characteristic of amide I and III, it was possible to evaluate the conformational changes in both materials. At excitation radiation of 532 nm, the deconvoluted Raman spectra for the amide III band indicated that, for both samples, there was a reduction in β-sheet conformation compared to α-helix conformation, and this structural disruption was driven by increased temperature. At radiation of 785 nm, the bands attributed to amino acid residues in the side chains increased in intensity, and by deconvoluting the amide I band, increased temperature was found to induce a transition from β-sheets to β-turns in both materials.

Mechanically Reinforced Silkworm Silk Fiber by Hot Stretching

“…The content of β -sheet increases with increasing stretch ratio, while the content of random coil/ α -helix continuously decreases, which is consistent with the results of WAXS. It should be noted that in a reported work [ 40 ], the content of β -sheet decreased with increased temperature, which is different from this work. We propose that although the heating results in a reduction of β -sheet, the stretching leads to increased β -sheet, and it seems that the effect of stretching is stronger than the effect of heating in our results.…”

Silk: history, obtaining, structure and properties of an old material in the development of new technologies

“…The number of days that are necessary to obtain each shape is counted only after the fibroin solution is prepared. 2 The fibroin crystalline structure, and hence its mechanical properties, can be modified during the preparation of these materials, by altering the fibroin concentration in the solution, the solvent used during treatment (water or alcohols), and the treatment temperature 84 and by adding other components or creating/distributing pores. 2,4,6,12,14,76,85,86 The thickness and degradation time for materials such as films and tubes can be controlled by changing the fibroin concentration in the solution used during the preparation.…”

Structural stability of biofilms produced from silkworm cocoon fibers

“…One such material is the fiber produced and synthesized in the glands of the silkworm, Bombyx mori. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] At the end of the larval stage, the silkworm produces silk fibers to *Corresponding author: hensan@uel.br https://doi.org/10.2298/JSC210611054F; Published 24 July, 2021 O n L i n e F i r s t form a cocoon by a complex spinning process. Most of the cocoon consists of fibroin fibers cemented together by another protein, sericin, that acts as an adhesive.…”