Structural and thermal properties of silk fibroin films obtained from cocoon and waste silk fibers as raw materials

Jaramillo‐Quiceno, Natalia; Álvarez‐López, Catalina; Restrepo‐Osorio, Adriana

doi:10.1016/j.proeng.2017.07.054

Cited by 58 publications

(32 citation statements)

References 12 publications

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“…As verified at both wavelengths (532 and 785 nm), the intensity ratios drop as the temperature is increased. Therefore, as reported by Jaramillo-Quiceno et al, 26 it is likely that heat treating silk fibers at moderate temperatures results in a disruption of molecular alignment concentrated in the amorphous regions, also affecting the crystalline structures of the β-sheet, which are gradually converted into random structures.…”

Section: Resultsmentioning

confidence: 83%

Impact of Temperature on the Stability of Silkworm Cocoon Fibers

Sacco

Santana

2019

Quím. Nova

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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.

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Section: Resultsmentioning

confidence: 83%

Impact of Temperature on the Stability of Silkworm Cocoon Fibers

Sacco

Santana

2019

Quím. Nova

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“…The silk fibrous wastes were extracted following the procedures previously published [19,31]. Briefly, the fibrous wastes were degummed in an aqueous solution of 0.5% (w/v) Na 2 CO 3 at boiling for 30 min.…”

Section: Extraction Of Sf and Preparation Of Sf Filmsmentioning

confidence: 99%

“…DSC curves for the samples were drafted using a Q2000 TA Instruments unit, USA, to study the thermal behavior of the samples. There were heated in aluminum crucibles in nitrogen atmosphere at flow rate of 50 mL/min, at temperature range of 30-320 °C, with constant heating rate of 10 °C/min [19].…”

Section: Differential Scanning Calorimetrymentioning

confidence: 99%

“…The structural conformation or the relative content of secondary structures of these silk protein-based materials can be controlled during processing or with the application of post-treatments. Hence, it is possible to engineer silk biomaterials with tunable degradation rates, mechanical and other specific properties [9,18,19]. Due to its versatile properties and biological activity, silk protein materials have been extensively used in the research and development of biomaterials for diverse applications: wound healing [20][21][22][23], bone tissue regeneration [24] and vascular grafting [25].…”

Section: Introductionmentioning

confidence: 99%

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Influence of ethanol post-treatments on the properties of silk protein materials

et al. 2019

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The use of silk proteins sericin (SS) and fibroin (SF) has been increased for biomedical applications. In order to improve their behavior inside of biological environment, silk biomaterials must be treated after their manufacturing by means of diverse methods. These include ethanol post-treatments to increase their crystallinity, mechanical properties and water stability. In this study, the effect of ethanol post-treatments on the properties of silk protein materials was evaluated. Defective cocoons and silk fibrous waste (SW) were used to obtain silk sericin sponges (S-SS) and silk fibroin films (F-SF), respectively. Two ethanol treatments were evaluated in SS and SF: immersion (I) and solvent vapor annealing (SVA). Morphological modifications induced by ethanol post-treatments were studied by scanning electron microscopy (SEM). Conformational structure of the samples was analyzed by attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR), and the thermal properties were evaluated by differential scanning calorimetry (DSC) measurements. SEM images revealed that ethanol process induces changes in treated F-SF and S-SS, the material surfaces are more roughness, and these effects were more pronounced in samples treated by I than that subjected to SVA. As a result of the ethanol treatments, the ATR-FTIR and DSC results showed an increment in relative content of β-sheet structures in both silk protein materials. The results suggest that ethanol post-treatments induce conformational transitions and morphological modifications in S-SS and F-SF that should be considered to select the post-treatment conditions according to the biomedical application requirements.

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“…Thus, differences have been analysed and detected for diverse degumming protocols 19–23 , raw silk dissolution methodologies 20,21,24 or different refrigeration and ageing times in fibroin dissolutions 25,26 . Other authors have even studied the structural and thermal properties of SF films obtained from different sources (cocoon and waste silk fibres) as raw materials 27 . However, to our knowledge, the effects of the different heat treatments applied to silk cocoons, before long term storage, have not been previously studied in the field of biomaterials.…”

Section: Introductionmentioning

confidence: 99%

Effect of different cocoon stifling methods on the properties of silk fibroin biomaterials

Aznar-Cervantes

Pagán

Santesteban

et al. 2019

Sci Rep

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Stifling treatments are applied to silk cocoons in order to kill the pupae, preventing the emergence of moths and allowing to preserve the silk during long periods of time. All of them involve the application of aggressive steps, such as sun exposure, hot steam from boiling water or hot air, during hours or even days. None of the scientific articles related to silk fibroin biomaterials has previously taken into account this fact in its section of materials and methods. In this work, the consequences of the stifling treatments most commonly used by the silk producing countries and companies are explored in depth, using fibroin films as biomaterial model. The protein degradation (visualised by SDS-PAGE) was dramatically increased in all the fibroin dissolutions produced from stifled cocoons; heavy and light chains of fibroin were specially degraded, reducing their presence along the lanes of the gel compared to the negative control (untreated fresh cocoons). Structural changes are also described for annealed silk fibroin films. The β-sheet content, analysed by means of infrared spectroscopy, was significantly higher when stifling was performed at higher temperature (70 °C and 85 °C). It is also exposed the impact of the stifling on the mechanical properties of the materials. Tensile strength and strain at break values were detected as significantly lower when this procedure was carried out by means of dry heat (85 °C) and sun exposure. On the other hand, and contrary to expectations, the proliferation of fibroblasts growing on the materials was improved by all the different stifling methods, compared to negative control, being this improvement, especially accentuated, on the films produced with fibroin purified from cocoons treated with dry heat.

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Structural and thermal properties of silk fibroin films obtained from cocoon and waste silk fibers as raw materials

Cited by 58 publications

References 12 publications

Impact of Temperature on the Stability of Silkworm Cocoon Fibers

Impact of Temperature on the Stability of Silkworm Cocoon Fibers

Influence of ethanol post-treatments on the properties of silk protein materials

Effect of different cocoon stifling methods on the properties of silk fibroin biomaterials

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