A New Solvent for Silk

Earland, Christopher; Raven, David J.

doi:10.1038/174461a0

Cited by 23 publications

(12 citation statements)

References 2 publications

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“…These features are attributable to the method used to prepare the nonwovens. In fact, soaking in the FA-CaCl 2 solution caused a partial dissolution of SF fibres (22). A heterogeneous mixture comprising SF fibres immersed into an acidic SF solution with good film-forming ability (23) was thus obtained.…”

Section: Resultsmentioning

confidence: 99%

Novel dermo-epidermal equivalents on silk fibroin-based formic acid-crosslinked three-dimensional nonwoven devices with prospective applications in human tissue engineering/regeneration/repair

Prà

Chiarini²,

Boschi³

et al. 2006

Int J Mol Med

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Biologically well-tolerated materials are at the core of intense research. In this study, we report both the intrinsic features of formic acid (FA)-crosslinked threedimensional (3D) nonwoven scaffolds consisting of sericindeprived, Bombyx mori silk fibroin (SF) in ß-sheet form and the long-term co-culture of adult human epidermal keratinocytes (HEKs) and dermal fibroblasts (HDFs) on them. The results of scanning electron microscopy, differential scanning calorimetry, and thermogravimetric and tensile strength studies showed that such scaffolds are made by a composite material, in which anisotropic SF fibres are enclosed within an isotropic matrix of SF in film form. Both fibres and films are firmly crosslinked by FA treatment and water-insoluble owing to their ß-sheet crystalline structure. Moreover, while a certain strength of the material in the dry state may favour its manufacturing, handling, and shaping, the dramatic loss of hardiness under wet conditions renders the scaffolds softer, mechanically more compliant and, hence, more apt for implantation. Normal HEKs and HDFs could be successfully co-cultured on such nonwovens for up to 75-95 days in vitro, thus forming a novel kind of dermo-epidermal equivalent, in which the cells were metabolically active and performed specific functions (e.g. the de novo production and assembly of collagen fibres), but never released urea nitrogen (an index of protein catabolism) or proinflammatory interleukin-1ß (IL-1ß). In keeping with the results of previous studies in animals (Dal Pra I, et al, Biomaterials 26: 1987-1989, 2005), these findings support the view that 3D SF-based nonwovens may be excellent candidates for beneficial applications in the field of human tissue engineering/regeneration/repair.

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Section: Resultsmentioning

confidence: 99%

Novel dermo-epidermal equivalents on silk fibroin-based formic acid-crosslinked three-dimensional nonwoven devices with prospective applications in human tissue engineering/regeneration/repair

Prà

Chiarini²,

Boschi³

et al. 2006

Int J Mol Med

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show abstract

“…However, if used in other applications, as for example in wound dressings or as a separating measure in order to distinguish different tissue layers in surgery, transparency is of secondary importance. If used as a substitute for corneal tissue, a transmittance of 85% in the visible spectrum ranging from 400 nm to 780 m is required, whereas UV radiation, which is known to be harmful to the eye (approximately 100 nm to 400 nm), is highly undesirable [42]. The membranes produced in this study exhibited highly favorable optical properties, without undergoing further functionalization.…”

Section: Discussionmentioning

confidence: 96%

“…Compared to other dissolution technologies, degummed silk transferred to FA/CaCl 2 was readily soluble at room temperature. The regeneration process described in various other publications involves three steps, including the dissolution in an environment subjected to a high concentration of salts, followed by dialysis with distilled water and subsequent redissolving in alcohol or acidic solution [41,42]. Traditional solvents such as aqueous LiBr or CaCl 2 /ethanol/distilled water require time-consuming steps within the dissolution process and severely degrade the silk fibroin nanofibers [41,43].…”

Section: Discussionmentioning

confidence: 99%

Influence of the Casting Concentration on the Mechanical and Optical Properties of FA/CaCl2-Derived Silk Fibroin Membranes

Kopp¹,

Schunck

Gosau

et al. 2020

IJMS

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In this study, we describe the manufacturing and characterization of silk fibroin membranes derived from the silkworm Bombyx mori. To date, the dissolution process used in this study has only been researched to a limited extent, although it entails various potential advantages, such as reduced expenses and the absence of toxic chemicals in comparison to other conventional techniques. Therefore, the aim of this study was to determine the influence of different fibroin concentrations on the process output and resulting membrane properties. Casted membranes were thus characterized with regard to their mechanical, structural and optical assets via tensile testing, SEM, light microscopy and spectrophotometry. Cytotoxicity was evaluated using BrdU, XTT, and LDH assays, followed by live–dead staining. The formic acid (FA) dissolution method was proven to be suitable for the manufacturing of transparent and mechanically stable membranes. The fibroin concentration affects both thickness and transparency of the membranes. The membranes did not exhibit any signs of cytotoxicity. When compared to other current scientific and technical benchmarks, the manufactured membranes displayed promising potential for various biomedical applications. Further research is nevertheless necessary to improve reproducible manufacturing, including a more uniform thickness, less impurity and physiological pH within the membranes.

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“…Formic acid (FA) can not dissolve native silk at all. However, the adding of a small quantity of inorganic salts into FA makes it an effective solvent for dissolving degummed silk . Unfortunately, the merits of this method have not been realized and developed sufficiently.…”

Section: Introductionmentioning

confidence: 99%

“…However, the adding of a small quantity of inorganic salts into FA makes it an effective solvent for dissolving degummed silk. 17 Unfortunately, the merits of this method have not been realized and developed sufficiently. In this study, we first employed CaCl 2 / Formic acid (CaCl 2 /FA) system to dissolve silk while preserving V C 2014 Wiley Periodicals, Inc.…”

Section: Introductionmentioning

confidence: 99%

Preparation of electrospun silk fibroin nanofibers from solutions containing native silk fibrils

Zhang

Ming

et al. 2014

J of Applied Polymer Sci

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Electrospinning solutions containing native silk fibrils with varied diameter and length were firstly achieved by dissolving silk in CaCl2/Formic acid solvents. The structure of nanofibrils significantly improved the spinnability of electrospinning solution. The diameter of electrospun silk fibroin (SF) nanofibers increased from 40 nm to 1.8 μm, which could be achieved through increasing the solution concentration from 2 to 10%, implying a good size control over a wide range in this process. The structure of SF nanofibers transferred from random coil to beta‐sheet, before and after ethanol treatment, respectively. The mechanical properties of the SF nanofibers were improved significantly with stress and strain at break of 11.15 MPa and 7.66% in dry state, and 3.32 MPa and 174.0% in wet state. The strategy for preparing SF nanofibers with improved mechanical properties and fiber diameter control over a wide range provides benefits for the application of this material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41236.

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A New Solvent for Silk

Cited by 23 publications

References 2 publications

Novel dermo-epidermal equivalents on silk fibroin-based formic acid-crosslinked three-dimensional nonwoven devices with prospective applications in human tissue engineering/regeneration/repair

Novel dermo-epidermal equivalents on silk fibroin-based formic acid-crosslinked three-dimensional nonwoven devices with prospective applications in human tissue engineering/regeneration/repair

Influence of the Casting Concentration on the Mechanical and Optical Properties of FA/CaCl2-Derived Silk Fibroin Membranes

Preparation of electrospun silk fibroin nanofibers from solutions containing native silk fibrils

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