“…It was also reported that silk fibroins maintain the raw silk fibroin structure without sericin. 18 Results from the Raman microscopy, XRD, and DSC indicate that RF had an amorphous structure, while both RFG and GF had a crystalline structure; however, RFG and GF had slightly different conditions.…”
Section: Resultsmentioning
confidence: 98%
“…We believe that the structure of the ultrafine nanofibrils, which is similar to that of the raw silk fibroin, leads to heat resistance and excellent mechanical properties as shown in previous research. 18 , 19 Since high mechanical properties such as tensile modulus and strength are important considerations in the development of silk fibroin films and scaffolds for tissue engineering applications, silk fibroin nanofibers with the β-sheet structure obtained in this research have potential applications in scaffolds. In addition, the GF fiber was found to have a nearly β-sheet structure where it was not affected by the methanol treatment.…”
Section: Resultsmentioning
confidence: 99%
“…The aqueous RF solution that was obtained after the dialysis and the gelled regenerated fibroin (RFG: regenerated fibroin gel) solution at room temperature were used as sample solutions in this experiment. The GF was prepared according to the method presented by Okahisa et al 18 The purified fibroin powder was washed with distilled water to prepare a mixture of purified fibroin and water. A 1 wt % fibroin suspension was prepared by passing four times through a grinder (MKCA 6-3, Masuko Sangyo Co., Japan) with a rotating grinding stone (MKGC 6-120, Masuko Sangyo Co., Japan) at 1500 rpm.…”
Section: Methodsmentioning
confidence: 99%
“…Recently, a study has succeeded in producing an aqueous fibroin solution directly from silkworm cocoons by grinding without utilizing any organic solvent. 18 , 19 Hence, it is a physical nanofibrillation method, not a chemical one. The fibroin film, which was prepared using the ground silk fibroin (GF) solution obtained by grinding, had superior mechanical and thermal properties compared with those prepared from RF solutions.…”
Silk
fibroin, a biodegradable component of silk, is increasingly
used for various applications and studied intensively. Recently, a
technique for preparing nanofibers without using chemicals has been
gaining attention from the environmental impact and safety perspectives.
This study focuses on the structure observation of ground silk fibroin
(GF) prepared using a grinding method, which is a physical nanofibrillation
method. The fabricated nanofiber samples were examined in detail using
the X-ray diffraction (XRD), differential scanning calorimetry (DSC),
micro Raman spectroscopy, and atomic force microscopy (AFM) techniques.
The nanofibrillated structures were observed in both GF and regenerated
silk fibroin (RF) samples prepared using the conventional method.
As results, AFM images showed that the nanofibril diameter of GF was
about 1.64 nm and that of RF was about 0.32 nm. Methanol treatment
induced a structural transition from a random coil to a β-sheet
for the RF film, but it had no effect on the GF film. Thus, it is
suggested that the grinding method provides not only ultrafine silk
fibroin nanofibers without using toxic reagents but also resistance
to reagents such as methanol.
“…It was also reported that silk fibroins maintain the raw silk fibroin structure without sericin. 18 Results from the Raman microscopy, XRD, and DSC indicate that RF had an amorphous structure, while both RFG and GF had a crystalline structure; however, RFG and GF had slightly different conditions.…”
Section: Resultsmentioning
confidence: 98%
“…We believe that the structure of the ultrafine nanofibrils, which is similar to that of the raw silk fibroin, leads to heat resistance and excellent mechanical properties as shown in previous research. 18 , 19 Since high mechanical properties such as tensile modulus and strength are important considerations in the development of silk fibroin films and scaffolds for tissue engineering applications, silk fibroin nanofibers with the β-sheet structure obtained in this research have potential applications in scaffolds. In addition, the GF fiber was found to have a nearly β-sheet structure where it was not affected by the methanol treatment.…”
Section: Resultsmentioning
confidence: 99%
“…The aqueous RF solution that was obtained after the dialysis and the gelled regenerated fibroin (RFG: regenerated fibroin gel) solution at room temperature were used as sample solutions in this experiment. The GF was prepared according to the method presented by Okahisa et al 18 The purified fibroin powder was washed with distilled water to prepare a mixture of purified fibroin and water. A 1 wt % fibroin suspension was prepared by passing four times through a grinder (MKCA 6-3, Masuko Sangyo Co., Japan) with a rotating grinding stone (MKGC 6-120, Masuko Sangyo Co., Japan) at 1500 rpm.…”
Section: Methodsmentioning
confidence: 99%
“…Recently, a study has succeeded in producing an aqueous fibroin solution directly from silkworm cocoons by grinding without utilizing any organic solvent. 18 , 19 Hence, it is a physical nanofibrillation method, not a chemical one. The fibroin film, which was prepared using the ground silk fibroin (GF) solution obtained by grinding, had superior mechanical and thermal properties compared with those prepared from RF solutions.…”
Silk
fibroin, a biodegradable component of silk, is increasingly
used for various applications and studied intensively. Recently, a
technique for preparing nanofibers without using chemicals has been
gaining attention from the environmental impact and safety perspectives.
This study focuses on the structure observation of ground silk fibroin
(GF) prepared using a grinding method, which is a physical nanofibrillation
method. The fabricated nanofiber samples were examined in detail using
the X-ray diffraction (XRD), differential scanning calorimetry (DSC),
micro Raman spectroscopy, and atomic force microscopy (AFM) techniques.
The nanofibrillated structures were observed in both GF and regenerated
silk fibroin (RF) samples prepared using the conventional method.
As results, AFM images showed that the nanofibril diameter of GF was
about 1.64 nm and that of RF was about 0.32 nm. Methanol treatment
induced a structural transition from a random coil to a β-sheet
for the RF film, but it had no effect on the GF film. Thus, it is
suggested that the grinding method provides not only ultrafine silk
fibroin nanofibers without using toxic reagents but also resistance
to reagents such as methanol.
“…SFNFs have often been prepared based on the electrospinning of silk fibroin solutions obtained by dissolution through the decomposition of the β-sheet structure of silk fibroin that contributes to the mechanical robustness of native silk fibers [ [22] , [23] , [24] ]. However, obtaining SFNFs by mechanical disintegration of degummed silk fibers is simpler and less energy- and time-consuming than preparation of SFNFs by electrospinning [ 25 ]. Fig.…”
Here, we investigated the usefulness of silk fibroin nanofibers obtained via mechanical grinding of degummed silkworm silk fibers as an additive in bioinks for extrusion three-dimensional (3D) bioprinting of cell-laden constructs. The nanofibers could be sterilized by autoclaving, and addition of the nanofibers improved the shear thinning of polymeric aqueous solutions, independent of electric charge and the content of cross-linkable moieties in the polymers. The addition of nanofibers to bioinks resulted in the fabrication of hydrogel constructs with higher fidelity to blueprints. Mammalian cells in the constructs showed >85% viability independent of the presence of nanofibers. The nanofibers did not affect the morphologies of enclosed cells. These results demonstrate the great potential of silk fibroin nanofibers obtained via mechanical grinding of degummed silkworm silk fibers as an additive in bioinks for extrusion 3D bioprinting.
The high crystallinity and sophisticated hierarchical architecture of native animal silk endow it with comprehensive mechanical properties that are superior to those of most synthetic fibers. However, these features also make the direct exfoliation of silk nanofibrils (SNFs) highly challenging. On the other hand, silk‐based materials prepared by conventional method (i.e., through silk fibroin aqueous solution) are usually weak, so the preparation methods based on SNFs have attracted much attention in recent years. Herein, a facile and environmentally friendly route is developed to directly exfoliate SNFs from natural Bombyx mori silkworm silk via ammonium persulfate oxidation followed by ultrasonication. The obtained SNFs have a high yield (nearly 40%) and are well dispersed in water in a wide pH range, so they can act as a good starting material to prepare subsequent silk‐based materials. The main application of the SNFs demonstrated in this article is a curcumin (Cur)/SNFs hydrogel as wound dressing. In vivo experimental results show that the Cur/SNFs hydrogel significantly enhanced the healing rate of wounds on diabetic mice. Therefore, the preparation method developed in this study provides an efficient way to produce SNFs, which have great potential for a wide range of applications, including as wound dressings for diabetics.
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