Experimental Methods for Characterizing the Secondary Structure and Thermal Properties of Silk Proteins

McGill, Meghan; Holland, Gregory P.; Kaplan, David L.

doi:10.1002/marc.201800390

Cited by 61 publications

(66 citation statements)

References 120 publications

(259 reference statements)

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“…Conversion of silk I into silk II and quantification of crystallinity can be monitored by FTIR spectroscopy (Figures 4 and 5) [31,32]. HFIP-based Fb-F-aq and FbMA-F-aq films prepared without ethanol treatment exhibit lowered beta-sheet content on comparison to their ethanol-treated counterparts Fb-F-et and FbMA-F-et (Table 2).…”

Section: Secondary Structurementioning

confidence: 99%

The Mechanical Properties, Secondary Structure, and Osteogenic Activity of Photopolymerized Fibroin

et al. 2020

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Previously, we have described the preparation of a novel fibroin methacrylamide (FbMA), a polymer network with improved functionality, capable of photocrosslinking into Fb hydrogels with elevated stiffness. However, it was unclear how this new functionality affects the structure of the material and its beta-sheet-associated crystallinity. Here, we show that the proposed method of Fb methacrylation does not disturb the protein’s ability to self-aggregate into the stable beta-sheet-based crystalline domains. Fourier transform infrared spectroscopy (FTIR) shows that, although the precursor ethanol-untreated Fb films exhibited a slightly higher degree of beta-sheet content than the FbMA films (46.9% for Fb-F-aq and 41.5% for FbMA-F-aq), both materials could equally achieve the highest possible beta-sheet content after ethanol treatment (49.8% for Fb-F-et and 49.0% for FbMA-F-et). The elasticity modulus for the FbMA-F-et films was twofold higher than that of the Fb-F-et as measured by the uniaxial tension (130 ± 1 MPa vs. 64 ± 6 MPa), and 1.4 times higher (51 ± 11 MPa vs. 36 ± 4 MPa) as measured by atomic force microscopy. The culturing of human MG63 osteoblast-like cells on Fb-F-et, FbMA-F-et-w/oUV, and FbMA-F-et substrates revealed that the photocrosslinking-induced increment of stiffness increases the area covered by the cells, rearrangement of actin cytoskeleton, and vinculin distribution in focal contacts, altogether enhancing the osteoinductive activity of the substrate.

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Section: Secondary Structurementioning

confidence: 99%

The Mechanical Properties, Secondary Structure, and Osteogenic Activity of Photopolymerized Fibroin

et al. 2020

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“…The peroxidase cross‐linking reaction resulted in covalent dityrosine bonds through condensation of tyrosine aromatic rings due to the formation of phenolic radicals on tyrosine residues in the presence of HRP and H 2 O 2 . BSA contains 17 disulfide bonds, 583 amino acids, and 20 tyrosine residues.…”

Section: Resultsmentioning

confidence: 99%

“…The peroxidase cross-linking reaction resulted in covalent dityrosine bonds through condensation of tyrosine aromatic rings due to the formation of phenolic radicals on tyrosine residues in the presence of HRP and H 2 O 2 . [10,16] BSA contains 17 disulfide bonds, 583 amino acids, and 20 tyrosine residues. Out of these, 3-6 of the tyrosine restudies are available on the surface of the folded molecule for enzymatic cross-linking; the rest are inaccessible due to steric hindrance.…”

Section: Non-covalent Silk-bsa Interactionsmentioning

confidence: 99%

“…Although biodegradable, silk is resistant to rapid proteolytic degradation and therefore exhibits stable mechanical integrity as found in native tissues. Silk consists of alternating hydrophobic crystalline and hydrophilic amorphous regions, which self‐assemble into semi‐crystalline secondary structures of beta‐sheets, turns, alpha‐helices, and random coils . Further, thermodynamically favorable assembly, particularly with strain, drives micelle to nanofibril assembly .…”

Section: Introductionmentioning

confidence: 99%

“…Silk consists of alternating hydrophobic crystalline and hydrophilic amorphous regions, which self-assemble into semi-crystalline secondary structures of beta-sheets, turns, alpha-helices, and random coils. [10] Further, thermodynamically favorable assembly, particularly with strain, drives micelle to nanofibril assembly. [11] Our previous report on silk hydrogel microfibers fabricated through enzymatic cross-linking showed that the materials exhibited strength, extensibility, and structural rearrangement with strain.…”

Section: Introductionmentioning

confidence: 99%

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Silk Hydrogel Microfibers for Biomimetic Fibrous Material Design

Bradner

McGill

Golding

et al. 2019

Macro Materials & Eng

Self Cite

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Fiber units are conserved design motifs that bestow intrinsic stiffness to biological tissues. Collagen fibrils are the fundamental unit of fibrous tissues with controlled assembly and multiscale structure‐function properties. Characteristic non‐linear tissue response is afforded through energy dissipation at the stiff‐soft interfaces of fibril collagen and extrafibrillar matrix components. The goal of this research is to develop a 3D silk hydrogel microfiber platform with bioinspired toughening mechanisms. Batch fabrication and post‐processing renders fibers that can be handled and with tunable features, as well as loading of components to improve material responses. Matrix loading of a glycoprotein, bovine serum albumin (BSA), adds a primary defense mechanism to material failure in the form of sacrificial bonds. This enables nano‐ to micro‐scale rearrangement with strain and improved fiber toughness compared to silk‐only fibers. Further biomimicry is added via matrix loading of a biosilica precursor peptide, R5, enabling biomineralization in the form of silicification. Inorganic mineral deposition of Silk‐BSA‐R5 hydrogel microfibers provides a fibrous scaffold for applications that require fibril‐mineral interfaces for load transduction. This microfiber platform introduces a methodology for meticulous fibrous scaffold design with biomimetic fibril hierarchy, toughening mechanisms, and loading capabilities for systematic tissue engineering applications.

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Designing Silk Biomaterials toward Better Future Healthcare: The Development and Application of Silk‐Based Implantable Electronic Devices in Clinical Diagnosis and Therapy

Lv,

Li,

Cao

et al. 2024

Advanced Materials

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Implantable medical electronic devices (IMEDs) have attracted great attention and shown versatility for solving clinical problems ranging from real‐time monitoring of physiological/ pathological states to electrical stimulation therapy and from monitoring brain cell activity to deep brain stimulation. The ongoing challenge is to select appropriate materials in target device configuration for biomedical applications. Currently, silk‐based biomaterials have been developed for the design of diagnostic and therapeutic electronic devices due to their excellent properties and abundant active sites in the structure. Herein, the aim is to summarize the structural characteristics, physicochemical properties, and bioactivities of natural silk biomaterials as well as their derived materials, with a particular focus on the silk‐based implantable biomedical electronic devices, such as implantable devices for invasive brain‐computer interfaces, neural recording, and in vivo electrostimulation. In addition, future opportunities and challenges are also envisioned, hoping to spark the interests of researchers in interdisciplinary fields such as biomaterials, clinical medicine, and electronics.

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Experimental Methods for Characterizing the Secondary Structure and Thermal Properties of Silk Proteins

Cited by 61 publications

References 120 publications

The Mechanical Properties, Secondary Structure, and Osteogenic Activity of Photopolymerized Fibroin

The Mechanical Properties, Secondary Structure, and Osteogenic Activity of Photopolymerized Fibroin

Silk Hydrogel Microfibers for Biomimetic Fibrous Material Design

Designing Silk Biomaterials toward Better Future Healthcare: The Development and Application of Silk‐Based Implantable Electronic Devices in Clinical Diagnosis and Therapy

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