From silk spinning in insects and spiders to advanced silk fibroin drug delivery systems

Werner, Vera; Meinel, Lorenz

doi:10.1016/j.ejpb.2015.03.016

Cited by 17 publications

(7 citation statements)

References 100 publications

(143 reference statements)

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“…Even today, silk remains the preferred material for specialized suture applications (e.g., eye surgery) due to its exquisite handling and toughness. , Recently, silk has been approved for human use in surgical meshes (Allergan Inc., U.S.A.) designed for soft tissue repair and reconstruction . However, silk is also a promising biopolymer for emerging biomedical applications, because of (i) the extensive clinical experience with silk, (ii) the all-aqueous silk processing technology, (iii) the ability of silk to stabilize and protect therapeutic payloads, and (iv) the capacity to reverse engineer silk into films, scaffolds, hydrogels, and micro- and nanoparticles (reviewed in refs − ). Silk nanoparticles can be surface decorated with polyethylene glycol (PEG) to improve colloidal stability in physiological fluids and to allow evasion of immune recognition. , …”

Section: Introductionmentioning

confidence: 99%

Degradation Behavior of Silk Nanoparticles—Enzyme Responsiveness

Wongpinyochit

Johnston

Seib

2018

ACS Biomater. Sci. Eng.

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Silk nanoparticles are viewed as promising vectors for intracellular drug delivery as they can be taken up into cells by endocytosis and trafficked to lysosomes, where lysosomal enzymes and the low pH trigger payload release. However, the subsequent degradation of the silk nanoparticles themselves still requires study. Here, we report the responsiveness of native and PEGylated silk nanoparticles to degradation following exposure to proteolytic enzymes (protease XIV and α-chymotrypsin) and papain, a cysteine protease. Both native and PEGylated silk nanoparticles showed similar degradation behavior over a 20 day exposure period (degradation rate: protease XIV > papain ≫ α-chymotrypsin). Within 1 day, the silk nanoparticles were rapidly degraded by protease XIV, resulting in a ∼50% mass loss, an increase in particle size, and a reduction in the amorphous content of the silk secondary structure. By contrast, 10 days of papain treatment was necessary to observe any significant change in nanoparticle properties, and α-chymotrypsin treatment had no effect on silk nanoparticle characteristics over the 20-day study period. Silk nanoparticles were also exposed ex vivo to mammalian lysosomal enzyme preparations to mimic the complex lysosomal microenvironment. Preliminary results indicated a 45% reduction in the silk nanoparticle size over a 5-day exposure. Overall, the results demonstrate that silk nanoparticles undergo enzymatic degradation, but the extent and kinetics are enzyme-specific.

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Section: Introductionmentioning

confidence: 99%

Degradation Behavior of Silk Nanoparticles—Enzyme Responsiveness

Wongpinyochit

Johnston

Seib

2018

ACS Biomater. Sci. Eng.

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“…The mulberry silkworm, Bombyx mori silk, has been widely used in industry due to its broad domestication, overall quality, and more recently, for use in high tech applications. − However, despite its utility, certain details of the natural spinning process represent a gap in our knowledge. When comparing the natural spinning process to industrial approaches, silk spinning appears to be a type of dry spinning, wherein a protein solution is moved through a silk gland, solidifies into a fiber and is then excreted. , This secreted fiber is used by the silkworm B.…”

Section: Introductionmentioning

confidence: 99%

Sericin Promotes Fibroin Silk I Stabilization Across a Phase-Separation

Kwak

Shin

et al. 2017

Biomacromolecules

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Natural silk spinning offers several advantages over the synthetic fiber spinning, although the underlying mechanisms of this process are yet to be fully elucidated. Silkworm silks, specifically B. mori, comprise two main proteins: fibroin, which forms the fiber, and sericin, a coextruded coating that acts as a matrix in the resulting nonwoven composite cocoon. To date, most studies have focused on fibroin's self-assembly and gelation, with the influence of sericin during spinning receiving little to no attention. This study investigates sericin's effects on the self-assembly of fibroin via their natural phase-separation. Through changes in sample opacity, FTIR, and XRD, we report that increasing sericin concentration retards the time to gelation and β-sheet formation of fibroin, causing it to adopt a Silk I conformation. Such findings have important implications for both the natural silk spinning process and any future industrial applications, suggesting that sericin may be able to induce long-range conformational and stability control in silk fibroin, while being in a separate phase, a factor that would facilitate long-term storage or silk feedstocks.

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“…β-sheets). One potential scenario includes a stabilisation of the silk gel state by pH-induced hydrogen bonding through aggregation of the spherical micelles [20]. The micelles subsequently elongate and align in response to shear forces during the spinning process and the spun silk thread emerges from the head of the silk worm.…”

Section: Bombyx Mori Silkmentioning

confidence: 99%

“…The micelles subsequently elongate and align in response to shear forces during the spinning process and the spun silk thread emerges from the head of the silk worm. During the spinning process, the β-sheet crystals are preferentially aligned parallel to the fibre axis [20]. These β-sheet crystals are distributed within the amorphous silk matrix but are able to interlock because of partial twisting of the nanofibrils.…”

Section: Bombyx Mori Silkmentioning

confidence: 99%

Reverse-engineered Silk Hydrogels for Cell and Drug Delivery

Seib

2018

Ther. Deliv.

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Silk is an important biopolymer for (bio)medical applications because of its unique and highly versatile structure and its robust clinical track record in human medicine. Silk can be processed into many material formats, including physically and chemically crosslinked hydrogels that have almost limitless applications ranging from tissue engineering to biomedical imaging and sensing. This concise review provides a detailed background of silk hydrogels, including silk structure-function relationships, biocompatibility and biodegradation, and it explores recent developments in silk hydrogel utilization, with specific reference to drug and cell delivery. We address common pitfalls and misconceptions while identifying emerging opportunities, including 3D printing.

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From silk spinning in insects and spiders to advanced silk fibroin drug delivery systems

Cited by 17 publications

References 100 publications

Degradation Behavior of Silk Nanoparticles—Enzyme Responsiveness

Degradation Behavior of Silk Nanoparticles—Enzyme Responsiveness

Sericin Promotes Fibroin Silk I Stabilization Across a Phase-Separation

Reverse-engineered Silk Hydrogels for Cell and Drug Delivery

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