Elucidating silk structure using solid-state NMR

Asakura, Tetsuo; Suzuki, Yuichi; Nakazawa, Yasumoto; Holland, Gregory P.; Yarger, Jeffery L.

doi:10.1039/c3sm52187g

Cited by 71 publications

(87 citation statements)

References 99 publications

(154 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a consequence of these stimuli-responsive self assembly mechanisms, the silk fibroin heavy chain displays crystalline polymorphism with predominantly three crystal forms, silk I , II and III [53, 62]. Silk I is the meta-stable, pre-spinning crystal form of silk fibroin in the middle region of the silk gland, primarily consisting of intra- and intermolecular bonding of a repeated type II, β-turn structure [62], and possibly helical structural elements forming a less extended chain confirmation than silk II [63].…”

Section: Desirable Properties Of Silk For Sustained Drug Deliverymentioning

confidence: 99%

“…Silk I is the meta-stable, pre-spinning crystal form of silk fibroin in the middle region of the silk gland, primarily consisting of intra- and intermolecular bonding of a repeated type II, β-turn structure [62], and possibly helical structural elements forming a less extended chain confirmation than silk II [63]. Silk II is the crystal form of the spun silk fibroin fiber, mainly consisting of antiparallel β-sheets [53] with distorted β-sheets and distorted β-turns [62], while silk III is a 3-fold extended helix that forms at air-water interfaces [64]. High-order conformation of aqueous regenerated fibroin solutions and fibroin material formats relevant to sustained drug delivery generally contain a mixture of β-sheets, β-turns, helices and random coils.…”

Section: Desirable Properties Of Silk For Sustained Drug Deliverymentioning

confidence: 99%

See 1 more Smart Citation

Silk-based biomaterials for sustained drug delivery

Yücel

Lovett

Kaplan

2014

Journal of Controlled Release

302

216

View full text Add to dashboard Cite

Silk presents a rare combination of desirable properties for sustained drug delivery, including aqueous-based purification and processing options without chemical cross-linkers, compatibility with common sterilization methods, controllable and surface-mediated biodegradation into non-inflammatory by-products, biocompatibility, utility in drug stabilization, and robust mechanical properties. A versatile silk-based toolkit is currently available for sustained drug delivery formulations of small molecule through macromolecular drugs, with a promise to mitigate several drawbacks associated with other degradable sustained delivery technologies in the market. Silk-based formulations utilize silk’s well-defined nano- through microscale structural hierarchy, stimuli-responsive self-assembly pathways and crystal polymorphism, as well as sequence and genetic modification options towards targeted pharmaceutical outcomes. Furthermore, by manipulating the interactions between silk and drug molecules, near-zero order sustained release may be achieved through diffusion- and degradation-based release mechanisms. Because of these desirable properties, there has been increasing industrial interest in silk-based drug delivery systems currently at various stages of the developmental pipeline from pre-clinical to FDA-approved products. Here, we discuss the unique aspects of silk technology as a sustained drug delivery platform and highlight the current state of the art in silk-based drug delivery. We also offer a potential early development pathway for silk-based sustained delivery products.

show abstract

Section: Desirable Properties Of Silk For Sustained Drug Deliverymentioning

confidence: 99%

Section: Desirable Properties Of Silk For Sustained Drug Deliverymentioning

confidence: 99%

Silk-based biomaterials for sustained drug delivery

Yücel

Lovett

Kaplan

2014

Journal of Controlled Release

302

216

View full text Add to dashboard Cite

show abstract

“…Hence, the next step is to determine the molecular secondary structure and dynamics of these sequenced proteins in spider dragline silk. Protein structural elucidation experimental tools such as nuclear magnetic resonance (NMR) spectroscopy and X-ray Diffraction (XRD) have been extensively used to probe the secondary structures of the proteins that make-up spider dragline silk [7,8,9,10,11,12,13,14,15]. They have provided many insights into the molecular structure and organization of the silk proteins.…”

Section: Introductionmentioning

confidence: 99%

Secondary Structure Adopted by the Gly-Gly-X Repetitive Regions of Dragline Spider Silk

Gray

Vaart

Guo

et al. 2016

IJMS

View full text Add to dashboard Cite

Solid-state NMR and molecular dynamics (MD) simulations are presented to help elucidate the molecular secondary structure of poly(Gly-Gly-X), which is one of the most common structural repetitive motifs found in orb-weaving dragline spider silk proteins. The combination of NMR and computational experiments provides insight into the molecular secondary structure of poly(Gly-Gly-X) segments and provides further support that these regions are disordered and primarily non-β-sheet. Furthermore, the combination of NMR and MD simulations illustrate the possibility for several secondary structural elements in the poly(Gly-Gly-X) regions of dragline silks, including β-turns, 310-helicies, and coil structures with a negligible population of α-helix observed.

show abstract

“…The three common crystalline structures of fibroin are silk I, II, and III [131,132]. The metastable and hydrophilic structures of B. mori SF, known as α-silk or silk I, can be easily converted to hydrophobic silk II through changes in temperature, physical spinning, and solvent effects, such as exposure to methanol and potassium chloride [132][133][134].…”

Section: The Structural Crystalline Mechanical and Degradation Promentioning

confidence: 99%

“…The metastable and hydrophilic structures of B. mori SF, known as α-silk or silk I, can be easily converted to hydrophobic silk II through changes in temperature, physical spinning, and solvent effects, such as exposure to methanol and potassium chloride [132][133][134]. Silk II refers to the arrangement of fibroin molecules into β-sheets that have greater strength, which is responsible for the crystallinity of fibroin; thus, no further crosslinking procedures are required [131,132]. Silk III has a helical structure that assemble at air-water interfaces [135].…”

Section: The Structural Crystalline Mechanical and Degradation Promentioning

confidence: 99%