Regeneration of high-quality silk fibroin fiber by wet spinning from CaCl 2 –formic acid solvent

Zhang, Feng; Lü, Qiang; Yue, Xiaoxiao; Zuo, Baoqi; Qin, Mingde; Li, Fang; Kaplan, David L.; Zhang, Xueguang

doi:10.1016/j.actbio.2014.09.045

Cited by 104 publications

(80 citation statements)

References 47 publications

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“…The concentrations of silk and ions were tested to make sure the viscoelastic properties of the material were suitable to avoid clogging the tip of the syringe needle and to maintain a relatively stable form on the substrate surface after printing. Specifically, the degummed silk fibers were dissolved in CaCl 2 /FA solvent 22 with the concentration at 30 wt% without aggregation or gelling (Fig. 1a, see experimental section for detailed formula).…”

Section: Resultsmentioning

confidence: 99%

Printing of stretchable silk membranes for strain measurements

et al. 2016

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Quantifying the deformation of biological tissues under mechanical loading is crucial to understand its biomechanical response in physiological conditions and important for designing materials and treatments for biomedical applications. However, strain measurements for biological tissues subjected to large deformations and humid environments are challenging for conventional methods due to several limitations such as strain range, boundary conditions, surface bonding and biocompatibility. Here we propose the use of silk solutions and printing to synthesize prototype strain gauges for large strain measurements in biological tissues. The study shows that silk-based strain gauges can be stretched up to 1300% without failure, which is more than two orders of magnitude larger than conventional strain gauges, and the mechanics can be tuned by adjusting ion content. We demonstrate that the printing approach can accurately provide well bonded florescent features on the silk membranes using designs which can accurately measure strain in the membrane. The results show that these new strain gauges measure large deformations in the materials by eliminating the effects of sliding from the boundaries, making the measurements more accurate than direct outputs from tensile machines.

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Section: Resultsmentioning

confidence: 99%

Printing of stretchable silk membranes for strain measurements

et al. 2016

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“…A recent study by Zhang et al produced silk fibers via wet spinning with mechanical properties that matched those of the native silk fiber. This can be attributed to their approach, with regenerated fibroin produced under milder conditions - maintaining some of the hierarchical structure of native silk fibers, and the use of water as a coagulant (Zhang et al, 2015). The elucidation of the underlying mechanisms behind the hierarchical assembly and structural transitions observed in silk fiber formation is important information to guide biomimetic silk processing.…”

Section: Discussionmentioning

confidence: 99%

Carbonic anhydrase generates a pH gradient in Bombyx mori silk glands

Domigan

Andersson

Alberti

et al. 2015

Insect Biochemistry and Molecular Biology

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Silk is a protein of interest to both biological and industrial sciences. The silkworm, Bombyx mori, forms this protein into strong threads starting from soluble silk proteins using a number of biochemical and physical cues to allow the transition from liquid to fibrous silk. A pH gradient has been measured along the gland, but the methodology employed was not able to precisely determine the pH at specific regions of interest in the silk gland. Furthermore, the physiological mechanisms responsible for the generation of this pH gradient are unknown. In this study, concentric ion selective microelectrodes were used to determine the luminal pH of Bombyx mori silk glands. A gradient from pH 8.2 to 7.2 was measured in the posterior silk gland, with a pH 7 throughout the middle silk gland, and a gradient from pH 6.8 to 6.2 in the beginning of the anterior silk gland where silk processing into fibers occurs. The small diameter of the most anterior region of the anterior silk gland prevented microelectrode access in this region. Using a histochemical method, the presence of active carbonic anhydrase was identified in the funnel and anterior silk gland of fifth instar larvae. The observed pH gradient collapsed upon addition of the carbonic anhydrase inhibitor methazolamide, confirming an essential role for this enzyme in pH regulation in the Bombyx mori silk gland. Plastic embedding of whole silk glands allowed clear visualization of the morphology, including the identification of four distinct epithelial cell types in the gland and allowed correlations between silk gland morphology and silk stages of assembly related to the pH gradient. Bombyx mori silk glands have four different epithelial cell types, one of which produces carbonic anhydrase. Carbonic anhydrase is necessary for the mechanism that generates an intraluminal pH gradient, which likely regulates the assembly of silk proteins and then the formation of fibers from soluble silk proteins. These new insights into native silk formation may lead to a more efficient production of artificial or regenerated silkworm silk fibers.

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“…However, this traditional dissolution method takes time-consuming, temperature sensitive and complex processes. Zhang et al developed a direct dissolution method using CaCl 2 -formic acid mixture to form SF film [7] and fiber [8] which exhibited simpler and faster processes. Currently, there is no study regarding the fabrication of porous SF scaffold using CaCl 2 -formic acid direct dissolution.…”

Section: Introductionmentioning

confidence: 99%

Development of Salt Leached Silk Fibroin Scaffold using Direct Dissolution Techniques for Cartilage Tissue Engineering

Wibowo¹,

Judawisastra²,

Barlian³

et al. 2019

Int. J. Adv. Sci. Eng. Inf. Technol.

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Autologous transplantations, the gold standard, did not meet sufficient health tissue coverage area for cartilage damage treatments. The field of tissue engineering offers a promising alternative to fulfill this limitation by growing patient own cells on biomaterials through tissue culture, reconstructed into new cartilage tissue, and the implanted to the injury area. To support tissue regeneration, biocompatible, biodegradable, and high strength silk fibroin (SF) was proposed in this study as scaffold materials. In this research, direct dissolution in CaCl 2 /formic acid, a faster and simpler process than traditional dissolution techniques, combined with salt leaching technique. SF contents on the scaffold were varied from 2 w/v% to 12 w/v% and NaCl size as porogen was fixed in diameter of 250±58 µm. Evaluation of the SF scaffold's morphology, hydrophilicity, biodegradability, and biocompatibility were conducted. The results showed porous silk fibroin scaffold had been successfully developed. The SF scaffolds have pore size 261-293 µm with highly interconnected pores. FTIR and XRD analysis of the scaffolds showed the characteristics of silk fibroin, which reveals the α-helix amorphous and β-sheet crystalline structure and comparable to the silk fibers. The scaffold showed good hydrophilicity and high water uptakes, which essential properties for cell survival. The scaffold degraded under Protease XIV, indicate biodegradable properties. Observation of cell attachment confirms the scaffold has good biocompatibility to adipose-derived stem cells and are suitable to be used in cartilage tissue engineering.

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Regeneration of high-quality silk fibroin fiber by wet spinning from CaCl 2 –formic acid solvent

Cited by 104 publications

References 47 publications

Printing of stretchable silk membranes for strain measurements

Printing of stretchable silk membranes for strain measurements

Carbonic anhydrase generates a pH gradient in Bombyx mori silk glands

Development of Salt Leached Silk Fibroin Scaffold using Direct Dissolution Techniques for Cartilage Tissue Engineering

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