WorldWideScience
1

Silk Properties Determined by Gland-Specific Expression of a Spider Fibroin Gene Family  

Science.gov (United States)

Spiders produce a variety of silks that range from Lycra-like elastic fibers to Kevlar-like superfibers. A gene family from the spider Araneus diadematus was found to encode silk-forming proteins (fibroins) with different proportions of amorphous glycine-rich domains and crystal domains built from poly(alanine) and poly(glycine-alanine) repeat motifs. Spiders produce silks of different composition by gland-specific expression of this gene family, which allows for a range of mechanical properties according to the crystal-forming potential of the constituent fibroins. These principles of fiber property control may be important in the development of genetically engineered structural proteins.

Guerette, Paul A.; Ginzinger, David G.; Weber, Bernhard H. F.; Gosline, John M.

1996-04-01

2

Preparation of Porous Scaffolds from Silk Fibroin Extracted from the Silk Gland of Bombyx mori (B. mori  

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Full Text Available In order to use a simple and ecofriendly method to prepare porous silk scaffolds, aqueous silk fibroin solution (ASF was extracted from silk gland of 7-day-old fifth instar larvae of Bombyx mori (B. mori. SDS-page analysis indicated that the obtained fibroin had a molecular weight higher than 200 kDa. The fabrication of porous scaffolds from ASF was achieved by using the freeze-drying method. The pore of porous scaffolds is homogenous and tends to become smaller with an increase in the concentration of ASF. Conversely, the porosity is decreased. The porous scaffolds show impressive compressive strength which can be as high as 6.9 ± 0.4 MPa. Furthermore, ASF has high cell adhesion and growth activity. It also exhibits high ALP activity. This implies that porous scaffolds prepared from ASF have biocompatibility. Therefore, the porous scaffolds prepared in this study have potential application in tissue engineering due to the impressive compressive strength and biocompatibility.

Liangjun Zhu

2012-06-01

3

LIM-homeodomain transcription factor Awh is a key component activating all three fibroin genes, fibH, fibL and fhx, in the silk gland of the silkworm, Bombyx mori.  

Science.gov (United States)

In the silkworm Bombyx mori, three fibroin genes, fibroin-heavy-chain (fibH), fibroin-light-chain (fibL) and fibrohexamerin (fhx), are coexpressed only in the posterior silk gland (PSG) cells, while the sericin genes encoding silk glue proteins are expressed in the middle silk gland (MSG) cells. Silk gland factor-2 (SGF-2) is a PSG-specific activator complex of fibH, composed of a LIM-homeodomain protein, Awh, and its cofactors, Ldb and Lcaf. We investigated whether SGF-2 can activate other fibroin genes using transgenic silkworms. The genes for Ldb and Lcaf were expressed ubiquitously in various tissues, while the gene for Awh was expressed strictly specific in PSG of the wild type silkworms. Misexpression of Awh in transgenic silkworms induced ectopic expression of fibL and fhx as well as fibH in MSG. Coincidently with the induction of fibL and fhx by Awh, binding of SGF-2 to the promoter of fibL and fhx was detected in vitro, and SGF-2 binds directly to the fhx core promoter. Ectopic expression of the fibroin genes was observed at high levels in the middle part of MSG. Moreover, fibL and fhx were induced in the anterior silk gland (ASG) of the transgenic silkworms, but fibH was not. These results indicate that Awh is a key activator of all three fibroin genes, and the activity is probably regulated in conjunction with additional factors. PMID:25449130

Kimoto, Mai; Tsubota, Takuya; Uchino, Keiro; Sezutsu, Hideki; Takiya, Shigeharu

2015-01-01

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Silk Fibroin Based Porous Materials  

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Full Text Available Silk from the Bombyx mori silkworm is a protein-based fiber. Bombyx mori silk fibroin (SF is one of the most important candidates for biomedical porous material based on its superior machinability, biocompatibility, biodegradation, bioresorbability, and so on. In this paper, we have reviewed the key features of SF. Moreover we have focused on the morphous, technical processing, and biocompatibility of SF porous materials, followed by the application research. Finally, we provide a perspective the potential and problems of SF porous materials.

Shuqin Yan

2009-12-01

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Phosphorylated silk fibroin matrix for methotrexate release.  

Science.gov (United States)

Silk-based matrix was produced for delivery of a model anticancer drug, methotrexate (MTX). The calculation of net charge of silk fibroin and MTX was performed to better understand the electrostatic interactions during matrix formation upon casting. Silk fibroin films were cast at pH 7.2 and pH 3.5. Protein kinase A was used to prepare phosphorylated silk fibroin. The phosphorylation content of matrix was controlled by mixing at specific ratios the phosphorylated and unphosphorylated solutions. In vitro release profiling data suggest that the observed interactions are mainly structural and not electrostatical. The release of MTX is facilitated by use of proteolytic enzymes and higher pHs. The elevated ?-sheet content and crystallinity of the acidified-cast fibroin solution seem not to favor drug retention. All the acquired data underline the prevalence of structural interactions over electrostatical interactions between methotrexate and silk fibroin. PMID:25435334

Volkov, Vadim; Sárria, Marisa P; Gomes, Andreia C; Cavaco-Paulo, Artur

2015-01-01

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Effect of degumming ph value on electrospining of silk fibroin  

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Full Text Available Regenerated silk fibroin fibers show properties dependent on the molecular weight of fibroin. The cocoon-degumming approaches had great impact on the degradation of silk fibroin. The effect of degumming pH value to electrospining of fibroin was studied in this paper. The viscosity and molecular weight of regenerated silk fibroin were studied using rheometer and gel electrophoresis. The results showed that the weaker the alkalinity of degumming reagent, there was the milder the effect on silk fibroin molecular. The fibroin fibers can be prepared by electrospining with low concentration of regenerated silk fibroin solution.

Lu Shen-Zhou

2014-01-01

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Materials Fabrication from Bombyx mori Silk Fibroin  

OpenAIRE

Silk fibroin, derived from Bombyx mori cocoons, is a widely used and studied protein polymer for biomaterial applications. Silk fibroin has remarkable mechanical properties when formed into different materials, demonstrates biocompatibility, has controllable degradation rates from hours to years, and it can be chemically modified to alter surface properties or to immobilize growth factors. A variety of aqueous or organic solvent processing methods can be used to generate silk biomaterials for...

Rockwood, Danielle N.; Preda, Rucsanda C.; Yu?cel, Tuna; Wang, Xiaoqin; Lovett, Michael L.; Kaplan, David L.

2011-01-01

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Thermal crystallization mechanism of silk fibroin protein  

Science.gov (United States)

In this thesis, the thermal crystallization mechanism of silk fibroin protein from Bombyx mori silkworm, was treated as a model for the general study of protein based materials, combining theories from both biophysics and polymer physics fields. A systematic and scientific path way to model the dynamic beta-sheet crystallization process of silk fibroin protein was presented in the following sequence: (1) The crystallinity, fractions of secondary structures, and phase compositions in silk fibroin proteins at any transition stage were determined. Two experimental methods, Fourier transform infrared spectroscopy (FTIR) with Fourier self-deconvolution, and specific reversing heat capacity, were used together for the first time for modeling the static structures and phases in the silk fibroin proteins. The protein secondary structure fractions during the crystallization were quantitatively determined. The possibility of existence of a "rigid amorphous phase" in silk protein was also discussed. (2) The function of bound water during the crystallization process of silk fibroin was studied using heat capacity, and used to build a silk-water dynamic crystallization model. The fundamental concepts and thermal properties of silk fibroin with/without bound water were discussed. Results show that intermolecular bound water molecules, acting as a plasticizer, will cause silk to display a water-induced glass transition around 80°C. During heating, water is lost, and the change of the microenvironment in the silk fibroin chains induces a mesophase prior to thermal crystallization. Real time FTIR during heating and isothermal holding above Tg show the tyrosine side chain changes only during the former process, while beta sheet crystallization occurs only during the latter process. Analogy is made between the crystallization of synthetic polymers according to the four-state scheme of Strobl, and the crystallization process of silk fibroin, which includes an intermediate precursor stage before crystallization. (3) The beta-sheet crystallization kinetics in silk fibroin protein were measured using X-ray, FTIR and heat flow, and the structure reveals the formation mechanism of the silk crystal network. Avrami kinetics theories, which were established for studies of synthetic polymer crystal growth, were for the first time extended to investigate protein self-assembly in multiblock silk fibroin samples. The Avrami exponent, n, was close to two for all methods, indicating formation of beta sheet crystals in silk proteins is different from the 3-D spherulitic crystal growth found in most synthetic homopolymers. A microphase separation pattern after chymotrypsin enzyme biodegradation was shown in the protein structures using scanning electron microscopy. A model was then used to explain the crystallization of silk fibroin protein by analogy to block copolymers. (4) The effects of metal ions during the crystallization of silk fibroin was investigated using thermal analysis. Advanced thermal analysis methods were used to analyze the thermal protein-metallic ion interactions in silk fibroin proteins. Results show that K+ and Ca2+ metallic salts play different roles in silk fibroin proteins, which either reduce (K+) or increase (Ca2+ ) the glass transition (Tg) of pure silk protein and affect the thermal stability of this structure.

Hu, Xiao

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sup 13 C NMR study of silk fibroin synthesis in vitro  

Energy Technology Data Exchange (ETDEWEB)

The posterior silkgland of Bombyx mori, silkworm larvae, produces abundant specific silk fibroin at about 80 {mu}g/cell for one day. In this study, the continuous production of silk fibroin in the posterior silk-gland was monitored by circumfusion cultivation using both C-13 NMR and C-13 labeling techniques in order to quantitatively determined the production of silk fibroin in vitro. The experimental setup is shown. The posterior silkglands of four larvae were collected in a 10 mm NMR sample tube under sterile condition. The C-13 NMR spectra were observed in the culture medium. The time-dependence of the C-13 NMR spectra of the culture medium containing the posterior silkglands are shown. The peak intensity for silk fibroin increased with the lapse of time. Also the peak due to the C{alpha} carbon of the serine residue of silk fibroin slightly increased, which indicates that there is a system which converts glycine to serine in the posterior silkglands. In order to discuss this silk production quantitatively, the relative intensity of the C{alpha} peaks for silk fibroin and glycine in the cultivation medium was plotted. The ability of the posterior silk-glands to produce silk protein was still high in vitro when the circumfusion cultivation technique was used. (K.I.).

Asakura, Tetsuo; Sakaguchi, Ryuji; Demura, Makoto (Tokyo Univ. of Agriculture and Technology, Koganei (Japan). Faculty of Technology)

1990-01-01

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Non-equilibrium Silk Fibroin Adhesives  

OpenAIRE

Regenerated silkworm silk solutions formed metastable, soft-solid-like materials (e-gels) under weak electric fields, displaying interesting mechanical characteristics such as dynamic adhesion and strain stiffening. Raman spectroscopy, in situ electric field dynamic oscillatory rheology and polarized optical microscopy indicated that silk fibroin electrogelation involved intermolecular self-assembly of silk molecules into amorphous, micron-scale, micellar structures and the formation of relat...

Yucel, Tuna; Kojic, Nikola; Leisk, Gary G.; Lo, Tim J.; Kaplan, David L.

2009-01-01

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Control of the gelation process of silk fibroin solution  

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Full Text Available In the present study, silk fibroin solution was controlled through a simple shearing to accomplish the steady and rapid gelation process and the conformational transition. Antheraea yamamai silk fibroin was formed into hydrogels quicker than Bombyx mori silk fibroin on the same condition. Comparing with Bombyx mori silk fibroin, the rapid gelation of Antheraea yamamai silk fibroin was concerned with its alternate polyalanine-containing units which are tended to form the ?-helix structures spontaneously. The entropic cost during the conformational transition to ?-sheet is less than that from random coil to ?-sheet.

Liu Yu

2014-01-01

12

Preparation of Ag nanoparticle dispersed silk fibroin compact  

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We prepared a silk fibroin compact in which Ag nanoparticles (Ag NPs) were dispersed, by adding only silver nitrate (AgNO3) to a silk fibroin solution without using any reducing agent. FT-IR and DSC revealed that the formation of Ag NPs distorted the conformation of the silk fibroin. However, the Ag NPs did not affect the thermal stability of the silk fibroin compact. An antimicrobial test against Escherichia coli (E. coli) was performed using the silk fibroin compact in which Ag NPs were dispersed. The compact showed sufficient antimicrobial activity because the average survival of E. coli was 1.6% after 8 h incubation even when the silver content was 0.01 wt%. The addition of Ag NPs into silk fibroin compact can provide color and an antimicrobial function without spoiling the function of the silk fibroin compact.

Yu, Weidong; Kuzuya, Toshihiro; Hirai, Shinji; Tamada, Yasushi; Sawada, Ken; Iwasa, Tatsuo

2012-12-01

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Materials Fabrication from Bombyx mori Silk Fibroin  

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Silk fibroin, derived from Bombyx mori cocoons, is a widely used and studied protein polymer for biomaterial applications. Silk fibroin has remarkable mechanical properties when formed into different materials, demonstrates biocompatibility, has controllable degradation rates from hours to years, and it can be chemically modified to alter surface properties or to immobilize growth factors. A variety of aqueous or organic solvent processing methods can be used to generate silk biomaterials for a range of applications. In this protocol we include methods to extract silk from B. mori cocoons in order to fabricate hydrogels, tubes, sponges, composites, fibers, microspheres and thin films. These materials can be used directly as biomaterials for implants, as scaffolding in tissue engineering and in vitro disease models, and for drug delivery. PMID:21959241

Rockwood, Danielle N.; Preda, Rucsanda C.; Yücel, Tuna; Wang, Xiaoqin; Lovett, Michael L.; Kaplan, David L.

2013-01-01

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Structural analysis and application to biomaterials of the silk fibroins  

International Nuclear Information System (INIS)

Silk fibroin from Bombyx mori silkworm has outstanding mechanical properties despite being spun from aqueous solution. I have clarified two distinct structures in the solid state; silk I and silk II, which mean the structures before and after spinning, by using solid state NMR. Moreover, I have been developing several kinds of biomaterials, such as bone regeneration materials and vascular grafts. In this paper, I present two topics: one is the structural analyses of the silk fibroin in detail, the other is applications of silk fibroins to tissue engineering. In the case of vascular regeneration, I have developed the small diameter vascular grafts made by silk fibroins. The new grafts from silk fibroins have good patency, and these grafts were commonly covered with cells and platelets at 4 weeks after implantation. For bone tissue engineering, I performed structural analyses of a new silk-like peptide, En(AGSGAG)4, in order to consider the molecular design of biomaterials for bone regeneration. (author)

15

Green process to prepare silk fibroin/gelatin biomaterial scaffolds.  

Science.gov (United States)

A new all-aqueous and green process is described to form three-dimensional porous silk fibroin matrices with control of structural and morphological features. Silk-based scaffolds are prepared using lyophilization. Gelatin is added to the aqueous silk fibroin solution to change the silk fibroin conformation and silk fibroin-water interactions through adjusting the hydrophilic interactions in silk fibroin-gelatin-water systems to restrain the formation of separate sheet like structures in the material, resulting in a more homogenous structure. Water annealing is used to generate insolubility in the silk fibroin-gelatin scaffold system, thereby avoiding the use of organic solvents such as methanol to lock in the beta-sheet structure. The adjusting of the concentration of gelatin, as well as the concentration of silk fibroin, leads to control of morphological and functional properties of the scaffolds. The scaffolds were homogeneous in terms of interconnected pores, with pore sizes ranging from 100 to 600 microm, depending on the concentration of silk fibroin used in the process. At the same time, the morphology of the scaffolds changed from lamellar sheets to porous structures based on the increase in gelatin content. Compared with salt-leaching aqueous-derived scaffolds and hexafluoroisopropanol (HFIP)-derived scaffolds, these freeze-dried scaffolds had a lower content of beta-sheet, resulting in more hydrophilic features. Most of gelatin was entrapped in the silk fibroin-gelatin scaffolds, without the burst release in PBS solution. During in vitro cell culture, these silk fibroin-gelatin scaffolds had improved cell-compatibility than salt-leaching silk fibroin scaffolds. This new process provides useful silk fibroin-based scaffold systems for use in tissue engineering. Furthermore, the whole process is green, including all-aqueous, room temperature and pressure, and without the use of toxic chemicals or solvents, offering new ways to load bioactive drugs or growth factors into the process. PMID:19924684

Lu, Qiang; Zhang, Xiaohui; Hu, Xiao; Kaplan, David L

2010-03-10

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In vitro evaluation of bi-layer silk fibroin scaffolds for gastrointestinal tissue engineering  

OpenAIRE

Silk fibroin scaffolds were investigated for their ability to support attachment, proliferation, and differentiation of human gastrointestinal epithelial and smooth muscle cell lines in order to ascertain their potential for tissue engineering. A bi-layer silk fibroin matrix composed of a porous silk fibroin foam annealed to a homogeneous silk fibroin film was evaluated in parallel with small intestinal submucosa scaffolds. AlamarBlue analysis revealed that silk fibroin scaffolds supported si...

Franck, Debra; Chung, Yeun Goo; Coburn, Jeannine; Kaplan, David L.; Estrada, Carlos R.; Mauney, Joshua R.

2014-01-01

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Extreme Diversity, Conservation, and Convergence of Spider Silk Fibroin Sequences  

Science.gov (United States)

Spiders (Araneae) spin high-performance silks from liquid fibroin proteins. Fibroin sequences from basal spider lineages reveal mosaics of amino acid motifs that differ radically from previously described spider silk sequences. The silk fibers of Araneae are constructed from many protein designs. Yet, the repetitive sequences of fibroins from orb-weaving spiders have been maintained, presumably by stabilizing selection, over 125 million years of evolutionary history. The retention of these conserved motifs since the Mesozoic and their convergent evolution in other structural superproteins imply that these sequences are central to understanding the exceptional mechanical properties of orb weaver silks.

Gatesy, John; Hayashi, Cheryl; Motriuk, Dagmara; Woods, Justin; Lewis, Randolph

2001-03-01

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Silk Fibroin Encapsulated Powder Reservoirs for Sustained Release of Adenosine  

OpenAIRE

Due to its unique properties, silk fibroin was studied as a biodegradable polymer vehicle for sustained, local delivery of the anticonvulsant adenosine from encapsulated reservoirs. Silk is a biologically derived protein polymer that is biocompatible, mechanically strong and degrades to non-toxic products in vivo. To achieve local, sustained, controlled adenosine release from fully degradable implants, solid adenosine powder reservoirs were coated with silk fibroin. Material properties of the...

Pritchard, Eleanor M.; Szybala, Cory; Boison, Detlev; Kaplan, David L.

2010-01-01

19

Silk tape nanostructure and silk gland anatomy of trichoptera.  

Science.gov (United States)

Caddisflys (order Trichoptera) construct elaborate protective shelters and food harvesting nets with underwater adhesive silk. The silk fiber resembles a nanostructured tape composed of thousands of nanofibrils (? 120 nm) oriented with the major axis of the fiber, which in turn are composed of spherical subunits. Weaker lateral interactions between nanofibrils allow the fiber to conform to surface topography and increase contact area. Highly phosphorylated (pSX)(4) motifs in H-fibroin blocks of positively charged basic residues are conserved across all three suborders of Trichoptera. Electrostatic interactions between the oppositely charged motifs could drive liquid-liquid phase separation of silk fiber precursors into a complex coacervates mesophase. Accessibility of phosphoserine to an anti-phosphoserine antibody is lower in the lumen of the silk gland storage region compared to the nascent fiber formed in the anterior conducting channel. The phosphorylated motifs may serve as a marker for the structural reorganization of the silk precursor mesophase into strongly refringent fibers. The structural change occurring at the transition into the conducting channel makes this region of special interest. Fiber formation from polyampholytic silk proteins in Trichoptera may suggest a new approach to create synthetic silk analogs from water-soluble precursors. PMID:21953029

Ashton, Nicholas N; Taggart, Daniel S; Stewart, Russell J

2012-06-01

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A novel electrospun silk fibroin/hydroxyapatite hybrid nanofibers  

International Nuclear Information System (INIS)

A novel electrospinning of silk fibroin/hydroxyapatite hybrid nanofibers with different composition ratios was performed with methanoic acid as a spinning solvent. The silk fibroin/hydroxyapatite hybrids containing up to 30% hydroxyapatite nanoparticles could be electrospun into the continuous fibrous structure. The electrospun silk fibroin/hydroxyapatite hybrid nanofibers showed bigger diameter and wider diameter distribution than pure silk fibroin nanofibers, and the average diameter gradually increased from 95 to 582 nm. At the same time, the secondary structure of silk fibroin/hydroxyapatite nanofibers was characterized by X-ray diffraction, Fourier transform infrared analysis, and DSC measurement. Comparing with the pure silk fibroin nanofibers, the crystal structure of silk fibroin was mainly amorphous structure in the hybrid nanofibers. X-ray diffraction results demonstrated the hydroxyapatite crystalline nature remained as evidenced from the diffraction planes (002), (211), (300), and (202) of the hydroxyapatite crystallites, which was also confirmed by Fourier transform infrared analysis. The thermal behavior of hybrid nanofibers exhibited the endothermic peak of moisture evaporation ranging from 86 to 113 °C, and the degradation peak at 286 °C appeared. The SF/HAp nanofibers mats containing 30% HAp nanoparticles showed higher breaking tenacity and extension at break for 1.1688 ± 0.0398 MPa and 6.55 ± 1.95%, respectively. Therefore, the electrospun silk fibroin/hydroxyapatite hybrid nanofibers should be provided potentially useful options for the fabrication of biomaterial scaffolds for bone tissue engineering. -- Highlights: ? The novel SF/HAp nanofibers were directly prepared by electrospinning method. ? The nanofiber diameter had significant related to the content of HAp. ? The crystal structure of silk fibroin was mainly amorphous structure in the hybrid nanofibers. ? The HAp crystals existing in the hybrid nanofibers were characterized using XRD and FTIR.

21

Sodium ion effect on silk fibroin conformation characterized by solid-state NMR and generalized 2D NMR NMR correlation  

Science.gov (United States)

In the present work, we investigated Na + ion effect on the silk fibroin (SF) conformation. Samples are Na +-involved regenerated silk fibroin films. 13C CP-MAS NMR demonstrates that as added [Na +] increases, partial silk fibroin conformation transit from helix-form to ?-form at certain Na + ion concentration which is much higher than that in Bombyx mori silkworm gland. The generalized two-dimensional NMR-NMR correlation analysis reveals that silk fibroin undergoes several intermediate states during its conformation transition process as [Na +] increase. The appearance order of the intermediates is followed as: helix and/or random coil ? helix-like ? ?-sheet-like ? ?-sheet, which is the same as that produced by pH decrease from 6.8 to 4.8 in the resultant regenerated silk fibroin films. The binding sites of Na + to silk fibroin might involve the carbonyl oxygen atom of certain amino acids sequence which could promote the formation of ?-sheet conformation. Since the Na +sbnd O bond is weak, the ability of Na + inducing the secondary structure transition is weaker than those of Ca 2+, Cu 2+ and even K +. It is maybe a reason why the sodium content is much lower than potassium in the silkworm gland.

Ruan, Qing-Xia; Zhou, Ping

2008-07-01

22

Nanofeatured silk fibroin membranes for dermal wound healing applications.  

Science.gov (United States)

As an effort to create the next generation of improved skin graft materials, in this study, we modified the surfaces of a previously investigated material, silk fibroin, using a NaOH alkaline treatment to obtain a biologically inspired nanofeatured surface morphology. Such surfaces were characterized for roughness, energy, and chemistry. In addition, keratinocyte (skin-forming cells) adhesion and proliferation on such nanofeatured silk fibroin wound dressings were studied in an initial attempt to determine the promotion of an epidermal cover on the wound bed to form a new epidermal barrier. Dermal fibroblast adhesion and proliferation were also studied to assess the ability of nanostructured silk fibroin to replace damaged dermal tissue in chronic wounds (i.e., for diabetic foot ulcers). Results demonstrated for the first time that keratinocyte and fibroblast cell density was greater on nanofeatured silk fibroin membranes compared with non-treated silk fibroin surfaces. The enhancement in cellular functions was correlated with an increase in silk surface nanotopography, wettability and change in chemistry after NaOH treatment. Due to the present promising results, the newly developed nanofeatured silk fibroin membranes are exciting alternative skin graft materials which should be further studied for various skin patch and wound dressing applications. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 135-144, 2015. PMID:24616219

Karahalilo?lu, Zeynep; Ercan, Batur; Denkba?, Emir B; Webster, Thomas J

2015-01-01

23

In vivo NMR analysis of incorporation of (2- sup 13 C) glycine into silk fibroin  

Energy Technology Data Exchange (ETDEWEB)

The biosynthetic mechanism of silk fibroin in silkworms, Bombyx mori, is unique because this fibrous protein composed mainly of glycine, alanine and serine is produced very rapidly in large quantity in the posterior silk glands. It is very meaningful to investigate into the biosynthesis of silk protein under nondestructive condition by in vivo NMR and C-13 labeling techniques. The sugar metabolism related to the production of silk fibroin was analyzed by monitoring the change in the C-13 labeled peaks in the NMR spectra for silkworms. In this paper, the monitoring of the 2-(C-13) glycine metabolism in Bombyx mori by the C-13 NMR in vivo is reported. In particular, the in vivo transport of glycine from the midgut to the posterior silk gland was measured, and the rate constants were determined with the course of the peak intensity in the C-13 NMR spectra. It is possible to discuss quantitatively the in vivo production of silk fibroin with these rate constants. The experiment and the results are reported. The in vivo C-13 NMR spectra of a 5 day old, 5th instar larva of Bombyx mori after the oral administration of 2-(C-13) glycine are shown. The significant increase of the peak intensity occurred. (K.I.).

Asakura, Tetsuo; Nagashima, Mariko; Demura, Makoto (Tokyo Univ. of Agriculture and Technology, Koganei (Japan). Faculty of Technology); Osanai, Minoru

1990-01-01

24

In vivo NMR analysis of incorporation of [2-13C] glycine into silk fibroin  

International Nuclear Information System (INIS)

The biosynthetic mechanism of silk fibroin in silkworms, Bombyx mori, is unique because this fibrous protein composed mainly of glycine, alanine and serine is produced very rapidly in large quantity in the posterior silk glands. It is very meaningful to investigate into the biosynthesis of silk protein under nondestructive condition by in vivo NMR and C-13 labeling techniques. The sugar metabolism related to the production of silk fibroin was analyzed by monitoring the change in the C-13 labeled peaks in the NMR spectra for silkworms. In this paper, the monitoring of the 2-(C-13) glycine metabolism in Bombyx mori by the C-13 NMR in vivo is reported. In particular, the in vivo transport of glycine from the midgut to the posterior silk gland was measured, and the rate constants were determined with the course of the peak intensity in the C-13 NMR spectra. It is possible to discuss quantitatively the in vivo production of silk fibroin with these rate constants. The experiment and the results are reported. The in vivo C-13 NMR spectra of a 5 day old, 5th instar larva of Bombyx mori after the oral administration of 2-(C-13) glycine are shown. The significant increase of the peak intensity occurred. (K.I.)

25

Impact of Protein-Metal Ion Interactions on the Crystallization of Silk Fibroin Protein  

Science.gov (United States)

Proteins can easily form bonds with a variety of metal ions, which provides many unique biological functions for the protein structures, and therefore controls the overall structural transformation of proteins. We use advanced thermal analysis methods such as temperature modulated differential scanning calorimetry and quasi-isothermal TMDSC, combined with Fourier transform infrared spectroscopy, and scanning electron microscopy, to investigate the protein-metallic ion interactions in Bombyx mori silk fibroin proteins. Silk samples were mixed with different metal ions (Ca^2+, K^+, Ma^2+, Na^+, Cu^2+, Mn^2+) with different mass ratios, and compared with the physical conditions in the silkworm gland. Results show that all metallic ions can directly affect the crystallization behavior and glass transition of silk fibroin. However, different ions tend to have different structural impact, including their role as plasticizer or anti-plasticizer. Detailed studies reveal important information allowing us better to understand the natural silk spinning and crystallization process.

Hu, Xiao; Lu, Qiang; Kaplan, David; Cebe, Peggy

2009-03-01

26

In vivo Degradation of Three-Dimensional Silk Fibroin Scaffolds  

OpenAIRE

Three-dimensional porous scaffolds prepared from regenerated silk fibroin using either an all aqueous process or a process involving an organic solvent, hexafluoroisopropanol (HFIP) have shown promise in cell culture and tissue engineering applications. However, their biocompatibility and in vivo degradation has not been fully established. The present study was conducted to systematically investigate how processing method (aqueous vs. organic solvent) and processing variables (silk fibroin co...

Wang, Yongzhong; Rudym, Darya D.; Walsh, Ashley; Abrahamsen, Lauren; Kim, Hyeon-joo; Kim, Hyun Suk; Kirker-head, Carl; Kaplan, David L.

2008-01-01

27

Production of Bombyx mori silk fibroin incorporated with unnatural amino acids.  

Science.gov (United States)

Silk fibroin incorporated with unnatural amino acids was produced by in vivo feeding of p-chloro-, p-bromo-, and p-azido-substituted analogues of L-phenylalanine (Phe) to transgenic silkworms (Bombyx mori) that expressed a mutant of phenylalanyl-tRNA synthetase with expanded substrate recognition capabilities in silk glands. Cutting down the content of Phe in the diet was effective for increasing the incorporation of Phe analogues but simultaneously caused a decrease of fibroin production. The azide groups incorporated in fibroin were active as chemical handles for click chemistry in both the solubilized and the solid (fibrous) states. The azides survived degumming in the boiling alkaline solution that is required for complete removal of the sericin layer, demonstrating that AzPhe-incorporated silk fibroin could be a versatile platform to produce "clickable" silk materials in various forms. This study indicates the huge potential of UAA mutagenesis as a novel methodology to alter the characteristics of B. mori silk. PMID:24884258

Teramoto, Hidetoshi; Kojima, Katsura

2014-07-14

28

Silk Fibroin Films Crystallized by Multiwalled Carbon Nanotubes  

Science.gov (United States)

Silk films prepared from regenerated silk fibroin are normally stabilized by ?-sheet formation through the use of solvents (methanol, water etc.). Herein, we report a new method of preparing water-stable films without a ?-sheet conformation from regenerated silk fibroin solutions by incorporating a small amount (0.2 wt%) of multiwalled carbon nanotubes (MWCNTs). To extend the biomaterial utility of silk proteins, forming water-stable silk-based materials with enhanced mechanical properties is essential. Scanning electron microscopy and transmission electron microscopy were used to observe the morphology of the MWCNT-incorporated silk films. The wide-angle X-ray diffraction provided clear evidence of the crystallization of the silk fibroin induced by MWCNT in the composite films without any additional annealing processing. The tensile modulus and strength of the composite films were improved by 108% and 51%, respectively, by the incorporation of 0.2 wt% of MWCNTs, as compared with those of the pure silk films. The method described in this study will provide an alternative means of crystallizing silk fibroin films without using an organic solvent or blending with any other polymers, which may be important in biomedical applications.

Kim, H.-S.; Park, W.-I.; Kim, Y.; Jin, H.-J.

29

The effects of different sterilization methods on silk fibroin  

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Full Text Available The aim of this study was to investigate the changes in the molecular structure and physiological activities of silk fibroin induced by three different sterilization methods (steam, gamma radiation and ethylene oxide with different dose or time period of sterilization by means of Fourier transform infrared (FT-IR spec-troscopy, X-ray diffraction, mechanical properties and assessment of molecular weight. The results showed that the steam sterilization darkened the color of silk fibroin and obviously affected the mechanical property; gamma irradiation slightly degraded the molecular weight of silk fibroin and the speed of degradation increased with increasing irradiation dose; and ethylene oxide almost had no influence on silk fibroin expect for some slight hydrolysis on mo-lecular weight. Because ethylene oxide sterilization had the smallest influence on the quality of silk fi-broin with compared to other sterilization methods, it could be used as an efficient method to make fibroin more suitable for the development of functional foods and cosmetics.

Xiaosong Gu

2011-05-01

30

Protein-protein nanoimprinting of silk fibroin films.  

Science.gov (United States)

Protein-protein imprinting of silk fibroin is introduced as a rapid, high-throughput method for the fabrication of nanoscale structures in silk films, through the application of heat and pressure. Imprinting on conformal surfaces is demonstrated with minor adjustments to the system, at resolutions comparable to other currently available nonplanar nanoimprint lithography techniques. PMID:23483712

Brenckle, Mark A; Tao, Hu; Kim, Sunghwan; Paquette, Mark; Kaplan, David L; Omenetto, Fiorenzo G

2013-05-01

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Acellular Bi-Layer Silk Fibroin Scaffolds Support Tissue Regeneration in a Rabbit Model of Onlay Urethroplasty  

OpenAIRE

Acellular scaffolds derived from Bombyx mori silk fibroin were investigated for their ability to support functional tissue regeneration in a rabbit model of urethra repair. A bi-layer silk fibroin matrix was fabricated by a solvent-casting/salt leaching process in combination with silk fibroin film casting to generate porous foams buttressed by homogeneous silk fibroin films. Ventral onlay urethroplasty was performed with silk fibroin grafts (Group 1, N = 4) (Width×Length, 1×2 cm2) in adult...

Chung, Yeun Goo; Tu, Duong; Franck, Debra; Gil, Eun Seok; Algarrahi, Khalid; Adam, Rosalyn M.; Kaplan, David L.; Estrada Jr, Carlos R.; Mauney, Joshua R.

2014-01-01

32

Silk fibroin-based scaffolds for bone regeneration.  

Science.gov (United States)

Porous scaffolds were prepared using regenerated Bombyx mori silk fibroin dissolved in water or hexafluoroisopropanol (HFIP). The effects of these two preparations on the formation and growth of new bone on implantation into the rabbit femoral epicondyle was examined. The aqueous-based fibroin (A-F) scaffold exhibited significantly greater osteoconductivity as judged by bone volume, bone mineral content, and bone mineral density at the implant site than the HFIP-based fibroin (HFIP-F) scaffold. Micro-CT analyses showed that the morphology of the newly formed bone differed significantly in the two types of silk fibroin scaffold. After 4 weeks of implantation, new trabecular bone was seen inside the pores of the A-F scaffold implant while the HFIP-F scaffold only contained necrotic cells. No trabecular bone was seen within the pores of the latter scaffolds, although the pores of these did contain giant cells and granulation tissue. PMID:23125151

Kuboyama, Noboru; Kiba, Hideo; Arai, Kiyoshi; Uchida, Ryoichiro; Tanimoto, Yasuhiro; Bhawal, Ujjal K; Abiko, Yoshimitsu; Miyamoto, Sayaka; Knight, David; Asakura, Tetsuo; Nishiyama, Norihiro

2013-02-01

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Production of silk sericin/silk fibroin blend nanofibers  

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Silk sericin (SS)/silk fibroin (SF) blend nanofibers have been produced by electrospinning in a binary SS/SF trifluoroacetic acid (TFA) solution system, which was prepared by mixing 20 wt.% SS TFA solution and 10 wt.% SF TFA solution to give different compositions. The diameters of the SS/SF nanofibers ranged from 33 to 837 nm, and they showed a round cross section. The surface of the SS/SF nanofibers was smooth, and the fibers possessed a bead-free structure. The average diameters of the SS/SF (75/25, 50/50, and 25/75) blend nanofibers were much thicker than that of SS and SF nanofibers. The SS/SF (100/0, 75/25, and 50/50) blend nanofibers were easily dissolved in water, while the SS/SF (25/75 and 0/100) blend nanofibers could not be completely dissolved in water. The SS/SF blend nanofibers could not be completely dissolved in methanol. The SS/SF blend nanofibers were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, and differential thermal analysis. FTIR showed that the SS/SF blend nanofibers possessed a random coil conformation and ß-sheet structure.

Zhang, Xianhua; Tsukada, Masuhiro; Morikawa, Hideaki; Aojima, Kazuki; Zhang, Guangyu; Miura, Mikihiko

2011-08-01

34

Conductive Au nanowires regulated by silk fibroin nanofibers  

Science.gov (United States)

Conductive Au-biopolymer composites have promising applications in tissue engineering such as nerve tissue regeneration. In this study, silk fibroin nanofibers were formed in aqueous solution by regulating silk self-assembly process and then used as template for Au nanowire fabrication. We performed the synthesis of Au seeds by repeating the seeding cycles for several times in order to increase the density of Au seeds on the nanofibers. After electroless plating, densely decorated Au seeds grew into irregularly shaped particles following silk nanofiber to fill the gaps between particles and finally form uniform continuous nanowires. The conductive property of the Au-silk fibroin nanowires was studied with current-voltage ( I-V) measurement. A typical ohmic behavior was observed, which highlighted their potential applications in nerve tissue regeneration.

Dong, Bo-Ju; Lu, Qiang

2014-03-01

35

Gelation of Antheraea pernyi Silk Fibroin Accelerated by Shearing  

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Full Text Available The rapid manufacture of silk fibroin gels in mild conditions is an important subject in the field of silk-based biomaterials. In this study, the gelation of Antheraea pernyi silk fibroin (ASF aqueous solution was induced by shearing, without chemical cross-linking agents. Simple shearing controlled and accomplished the steady and rapid conformational transition to ?-sheets with ease. The conformational transformation and rapid gelation mechanisms of ASF induced by shearing were tracked and analyzed by circular dichroism spectrometry, Fourier transform infrared spectroscopy and X-ray diffractometry, then compared with Bombyx mori silk fibroin (BSF. ASF quickly formed hydrogels within 24 - 48 h after shearing under different shearing rates for 30 - 90 min, resulting in sol-gel transformation when the ?-sheet content reached nearly 50%, which is the minimum content needed to maintain a stable hydrogel system in ASF. The gel structures remained stable once formed. The rapid gelation of ASF through shearing compared with BSF was achieved because of ASF’s alternating polyalanine-containing units, which tend to form ?-helix structures spontaneously. Further, the entropic cost during the conformational transition from the ?-helix to the ?-sheet structure is less than the cost of the transition from the random coil structure. This method is a simple, non-chemical cross-linking approach for the promotion of rapid gelation and the protection of the biological properties of ASF, and it may prove useful for application in the field of biomedical materials.

Yu Liu

2013-05-01

36

Determination of multiphoton absorption of silk fibroin using the Z-scan technique.  

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The multiphoton absorption of silk fibroin at 810 nm was determined by open-aperture Z-scan. Three-photon absorption was confirmed at this wavelength and the three-photon cross section of silk fibroin was measured. Silk fibroin of varying molecular weight was tested and the cross section was found to increase exponentially with increasing molecular weight. The confirmation of a relatively large three-photon absorption cross section in silk will help lay the groundwork for future investigation of direct laser writing of three-dimensional structures within a silk matrix. PMID:24514515

Applegate, Matthew B; Marelli, Benedetto; Kaplan, David L; Omenetto, Fiorenzo G

2013-12-01

37

Degradation Behaviors of Thai Bombyx mori Silk Fibroins Exposure to Protease Enzymes  

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Full Text Available The degradation behaviors of Thai Bombyx mori called Samrong and Nanglai silk fibroins exposure to protease enzymes; protease XIV, protease XXIII and ?-chymotrypsin type II were studied in this work. The degradation behaviors were expressed by their weight loss, morphological and secondary structure changes as well as thermal properties. Samrong showed higher percentage of weight loss than Nanglai. SEM micrographs indicated that silk fibroin were de- stroyed and showed many holes on their fiber surfaces. All of silk samples were increasable destroyed when exposure to the protease enzyme for long incubation period. With thermal analysis, both silk fibroin presented the thermal stability in the same profile. The result suggested that the selected silk fibroin should be composed of similar pattern of amino acids and their ratios. However, the protease susceptibility of each silk fibroin slightly varied in case of morphology observation. This might be affected by their genetic variety.

Chuleerat Wongnarat

2013-01-01

38

Preparation and Characterization of Eri (Philosamia ricini Silk Fibroin Powder  

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Full Text Available Eri (Philosamia ricini cocoons were dissolved with 9 M Ca(NO32 and then dialyzed against distilled water for 3 days. The Silk Fibroin (SF solution was used as substrate to prepare SF powder by using freeze-drying method. The secondary structure and thermal behavior of SF powder were determined by FT-IR and TGA analyzer, respectively. The SF powder was arranged in micrometer sizes. FT-IR spectra indicated that the SF powder composed of ?-helix and ?-sheet structures and differed from silk cocoon. Thermal properties were studied by thermogravimetric technique. Difference in thermal properties between Eri silk cocoon and SF powder was found. It is a promising that conformational structure and thermal properties were influenced by changing of silk forms.

S. Yaowalak

2009-01-01

39

Water-ethanol separation by pervaporation through silk fibroin membranes  

Energy Technology Data Exchange (ETDEWEB)

Silk fibroin is a natural polypeptide mainly composed of glycine, alanine and serine, and is a most popular natural fiber. Numerous studies have been made concerning its structure and the properties. In this report, water-ethanol separation was examined by a pervaporation method using a silk-fibroin membrane insolubilized in steam-ethanol. These membranes permeated water selectively, depending on the membrane thickness and the method of insolubilization. In other words, selective permeation of water appeared from 20 micron membrane thickness. Selectivity increased with the thickness, whereas the rate of permeation decreased accordingly. Insolubilization by steaming was effective for enhancing the selectivity. Activation energy for permeation obtained from the Arrhenius plots was between 5 and 8 kcal/mole. Separation factor reduced somewhat on the high temperature side, but it was only little being correlated with the high rate of permeation. (9 figs, 9 refs)

Hirotsu, Toshihiro; Nakajima, Shigeru; Kitamura, Aio; Mizoguchi, Kensaku; Suda, Yoshio

1988-02-10

40

Novel silk fibroin films prepared by formic acid/hydroxyapatite dissolution method.  

Science.gov (United States)

Bombyx mori silk fibroin from the silkworm was firstly found to be soluble in formic acid/hydroxyapatite system. The rheological behavior of silk fibroin solution was significantly influenced by HAp contents in dissolved solution. At the same time, silk fibroin nanofibers were observed in dissolved solution with 103.6±20.4nm in diameter. Moreover, the structure behavior of SF films prepared by formic acid/hydroxyapatite dissolution method was examined. The secondary structure of silk fibroin films was attributed to silk II structure (?-sheet), indicating that the hydroxyapatite contents in dissolved solution were not significantly affected by the structure of silk fibroin. The X-ray diffraction results exhibited obviously hydroxyapatite crystalline nature existing in silk fibroin films; however, when the hydroxyapatite content was 5.0wt.% in dissolved solution, some hydroxyapatite crystals were converted to calcium hydrogen phosphate dehydrate in silk fibroin dissolution process. This result was also confirmed by Fourier transform infrared analysis and DSC measurement. In addition, silk fibroin films prepared by this dissolution method had higher breaking strength and extension at break. Based on these analyses, an understanding of novel SF dissolution method may provide an additional tool for designing and synthesizing advanced materials with more complex structures, which should be helpful in different fields, including biomaterial applications. PMID:24582221

Ming, Jinfa; Liu, Zhi; Bie, Shiyu; Zhang, Feng; Zuo, Baoqi

2014-04-01

41

Preparation and Characterization of Nanocomposite and Nanoporous Silk Fibroin Films  

OpenAIRE

Nanocomposite and nanoporous silk fibroin (SF) films were prepared by film casting of SF solution containing surfactant-free colloidal nanoparticles of methoxy poly (ethylene glycol)-b-poly (D, L-lactide) diblock copolymer (MPEG-b-PDLL). Self-condensation and nanophase separation of the nanoparticles from SF film matrix during film drying process gave nanopore structures. The colloidal nanoparticles were prepared in SF solution by modified-spontaneous emulsification solven...

Yaowalak Srisuwan; Mangkorn Srisa-ard; Chaiyasit Sittiwet; Yodthong Baimark; Nual- Anong Narkkong; Chirapha Butiman

2008-01-01

42

Nanolayer Biomaterial Coatings of Silk Fibroin for Controlled Release  

OpenAIRE

An all-aqueous, stepwise deposition process with silk fibroin protein for the assembly of nanoscale layered controlled release coatings was exploited. Model compounds, Rhodamine B, Even Blue and Azoalbumin, representing small molecule drugs and therapeutically relevant proteins were incorporated in the nanocoating process and their loading and release behavior was quantified. In addition, the structure and morphology of the coatings were characterized. Release studies in vitro showed that con...

Wang, Xianyan; Hu, Xiao; Daley, Andrea; Rabotyagova, Olena; Cebe, Peggy; Kaplan, David L.

2007-01-01

43

In vivo degradation of three-dimensional silk fibroin scaffolds.  

Science.gov (United States)

Three-dimensional porous scaffolds prepared from regenerated silk fibroin using either an all-aqueous process or a process involving an organic solvent, hexafluoroisopropanol (HFIP), have shown promise in cell culture and tissue engineering applications. However, their biocompatibility and in vivo degradation have not been fully established. The present study was conducted to systematically investigate how processing method (aqueous vs. organic solvent) and processing variables (silk fibroin concentration and pore size) affect the short-term (up to 2 months) and long-term (up to 1 year) in vivo behavior of the protein scaffolds in both nude and Lewis rats. The samples were analyzed by histology for scaffold morphological changes and tissue ingrowth, and by real-time RT-PCR and immunohistochemistry for immune responses. Throughout the period of implantation, all scaffolds were well tolerated by the host animals and immune responses to the implants were mild. Most scaffolds prepared from the all-aqueous process degraded to completion between 2 and 6 months, while those prepared from organic solvent (hexafluoroisopropanol (HFIP)) process persisted beyond 1 year. Due to widespread cellular invasion throughout the scaffold, the degradation of aqueous-derived scaffolds appears to be more homogeneous than that of HFIP-derived scaffolds. In general and especially for the HFIP-derived scaffolds, a higher original silk fibroin concentration (e.g. 17%) and smaller pore size (e.g. 100-200microm) resulted in lower levels of tissue ingrowth and slower degradation. These results demonstrate that the in vivo behavior of the three-dimensional silk fibroin scaffolds is related to the morphological and structural features that resulted from different scaffold preparation processes. The insights gained in this study can serve as a guide for processing scenarios to match desired morphological and structural features and degradation time with tissue-specific applications. PMID:18502501

Wang, Yongzhong; Rudym, Darya D; Walsh, Ashley; Abrahamsen, Lauren; Kim, Hyeon-Joo; Kim, Hyun S; Kirker-Head, Carl; Kaplan, David L

2008-01-01

44

Optimization strategies for electrospun silk fibroin tissue engineering scaffolds  

OpenAIRE

As a contribution to the functionality of scaffolds in tissue engineering, here we report on advanced scaffold design through introduction and evaluation of topographical, mechanical and chemical cues. For scaffolding, we used silk fibroin (SF), a well established biomaterial. Biomimetic alignment of fibers was achieved as a function of the rotational speed of the cylindrical target during electrospinning of a SF solution blended with polyethylene oxide. Seeding fibrous SF scaffolds with huma...

Meinel, Anne J.; Kubow, Kristopher E.; Klotzsch, Enrico; Garcia-fuentes, Marcos; Smith, Michael L.; Vogel, Viola; Merkle, Hans P.; Meinel, Lorenz

2009-01-01

45

Effect of plasma-irradiated silk fibroin in bone regeneration.  

Science.gov (United States)

We have recently identified plasma-irradiated silk fibroin (P-AF) as a key regulator of bone matrix properties and composition. Bone matrix properties were tested in 48 femur critical size defects (3.25 mm in diameter) with the expression of osteoblast specific genes at 1 and 2 weeks after surgery. The scaffolds were characterized by various states of techniques; the scanning electronic microcopy revealed the large sized pores in the aqueous-based silk fibroin (A-F) scaffold and showed no alteration into the architecture by the addition of plasma irradiation. The contact angle measurements confirmed the introduction of plasma helped to change the hydrophobic nature into hydrophilic. The histological analyses confirmed the presence of silk fibroin in scaffolds and newly formed bone around the scaffolds. Immunohistochemical examination revealed the increased expression pattern in a set of osteoblast specific genes (TGF-?, TGF-? type III receptor, Runx2, type I collagen and osteocalcin). These data were the first to show that the properties of bone matrix are regulated, specifically through Runx2 pathway in P-AF group. Thus, an employment of P-AF increases several compositional properties of bone, including increased bone matrix, mineral concentration, cortical thickness, and trabecular bone volume. PMID:24680284

Uchida, Ryoichiro; Bhawal, Ujjal K; Kiba, Hideo; Arai, Kiyoshi; Tanimoto, Yasuhiro; Kuboyama, Noboru; Asakura, Tetsuo; Nishiyama, Norihiro

2014-09-01

46

The effect of gamma ray on the thermo-mechanical property of silk fibroin  

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Full Text Available This paper studies the effect of gamma ray on the thermo-mechanical properties of silk fibroin experimentally. The experiment reveals that the gamma ray can accelerate biodegradation of silk fibroin by decreasing its thermo-mechanical property.

Jin Huanyu

2013-01-01

47

Microstructural Parameters in Fibroin and Fiber Forms of Wild-Silks Using Whole Powder Pattern Model  

Science.gov (United States)

The characteristics of wild-silk fibers and their fibroins have been investigated using X-ray scattering technique. The microstructural parameters like lattice strain and crystallite size of these silk fibers and fibroins were determined by the line profile analysis and hence whole powder pattern fitting technique. The changes in the microstructural parameters are interpreted in terms of structural features of fibroins and fiber forms.

Siddaraju, G. N.; Somashekarappa, H.; Roy, Subrata; Somashekar, R.

2011-07-01

48

Preparation and characterization of silk fibroin as a biomaterial with potential for drug delivery  

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Full Text Available Abstract Background Degummed silk fibroin from Bombyx mori (silkworm has potential carrier capabilities for drug delivery in humans; however, the processing methods have yet to be comparatively analyzed to determine the differential effects on the silk protein properties, including crystalline structure and activity. Methods In this study, we treated degummed silk with four kinds of calcium-alcohol solutions, and performed secondary structure measurements and enzyme activity test to distinguish the differences between the regenerated fibroins and degummed silk fibroin. Results Gel electrophoresis analysis revealed that Ca(NO32-methanol, Ca(NO32-ethanol, or CaCl2-methanol treatments produced more lower molecular weights of silk fibroin than CaCl2-ethanol. X-ray diffraction and Fourier-transform infrared spectroscopy showed that CaCl2-ethanol produced a crystalline structure with more silk I (?-form, type II ?-turn, while the other treatments produced more silk II (?-form, anti-parallel ?-pleated sheet. Solid-State 13C cross polarization and magic angle spinning-nuclear magnetic resonance measurements suggested that regenerated fibroins from CaCl2-ethanol were nearly identical to degummed silk fibroin, while the other treatments produced fibroins with significantly different chemical shifts. Finally, enzyme activity test indicated that silk fibroins from CaCl2-ethanol had higher activity when linked to a known chemotherapeutic drug, L-asparaginase, than the fibroins from other treatments. Conclusions Collectively, these results suggest that the CaCl2-ethanol processing method produces silk fibroin with biomaterial properties that are appropriate for drug delivery.

Zhang Hao

2012-06-01

49

A quicker degradation rate is yielded by a novel kind of transgenic silk fibroin consisting of shortened silk fibroin heavy chains fused with matrix metalloproteinase cleavage sites.  

Science.gov (United States)

Degradation performance of silk fibroin is an important property for its medical applications. Herein we constructed a shortened silk fibroin heavy chain protein fused with a matrix metalloproteinase cleavage site (SSFH-MMP) along with a glutathione S-transferase tag ahead. The digestion assay shows it can be cut by matrix metalloproteinase-2 (MMP-2) at its MMP cleavage site. Furthermore, we introduced the SSFH-MMP into silk fibroin by genetic modification of silkworms in order to increase the degradation rate of the silk fibroin. After acquisition of a race of transgenic silkworms with the coding sequence of the MMP cleavage site in their genomic DNA, we tested some properties of their silk fibroin designated TSF-MMP. The results show that the TSF-MMP has MMP cleavage sites and yields a quicker degradation rate during dilution in MMP-2 enzyme buffer or implantation into tumor tissues compared with that of normal silk fibroin. Moreover, the TSF-MMP is in vitro non-toxic to human bone marrow mesenchymal stem cells (hBM-MSCs) indicating that the TSF-MMP may become a biomaterial with a quicker degradation rate for its medical applications. PMID:24801061

Huang, Guoping; Yang, Danfeng; Sun, Chunfeng; Huang, Jianping; Chen, Keping; Zhang, Chunxia; Chen, Huiqing; Yao, Qin

2014-08-01

50

Silk Fibroin/Starch Blend Films: Preparation and Characterization  

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Full Text Available This study was aimed to prepare silk fibroin (SF of Thai silk (Bombyx mori and cassava starch blend films by solvent evaporation method. The SF solution was firstly prepared from the cocoons by dissolving pure silk fibroin with tertiary solvent system of CaCl2: Ethanol: H2O (1:2:8 by mol. Cassava starch solution could be prepared by boiling at high temperature. The mixture of the SF and cassava starch solution was then blended and cast on the polystyrene plates. The obtained films were investigated on their morphology, secondary structures and thermal properties by using SEM, FTIR and thermogravimetry, respectively. The results found that SF blended with starch could be formed the higher ratio of ?-sheet. With cross-section images, the blend films showed homogeneously texture. In addition, the blend film gradually increased its thermal properties when the starch blended ratio was increased. In conclusion, the SF/starch blend films could be adjusted their properties by varying the blend ratio.

Prasong Srihanam

2011-01-01

51

Electrophoretic deposition of tetracycline modified silk fibroin coatings for functionalization of titanium surfaces  

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Electrophoretic deposition has been widely used for the fabrication of functional coatings onto metal implant. A characteristic feature of this process is that positively charged materials migrate toward the cathode and can deposit on it. In this study, silk fibroin was decorated with tetracycline in aqueous solution to impart positive charge, and then deposited on negatively titanium cathode under certain electric field. The characterization of the obtained coatings indicated that the intermolecular hydrogen bonds formed between the backbone of silk fibroin and tetracycline molecular. In vitro biological tests demonstrated that osteoblast-like cells achieved acceptable cell affinity on the tetracycline cross-linked silk fibroin coatings, although greater cell viability was seen on pure silk fibroin coatings. The cationic silk fibroin coatings showed remarkable antibacterial activity against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. Therefore, we concluded that electrophoretic deposition was an effective and efficient technique to prepare cationic silk fibroin coatings on the titanium surface and that cationic silk fibroin coatings with acceptable biocompatibility and antibacterial property were promising candidates for further loading of functional agents.

Zhang, Zhen; Qu, Yinying; Li, Xiaoshuang; Zhang, Sheng; Wei, Qingsong; Shi, Yusheng; Chen, Lili

2014-06-01

52

Preparation, characterization and biocompatibility of electrospinning heparin-modified silk fibroin nanofibers.  

Science.gov (United States)

In this study, the electrospun silk fibroin nanofibrous scaffolds were modified with heparin by grafting after plasma treatment and blending electrospinning. Morphology, microstructure, chemical composition and grafting efficiency of the heparin-modified silk fibroin nanofibrous scaffolds were characterized to evaluate the effect of modification by means of scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectrometer (XPS). The results showed that the heparin was successfully introduced to the silk fibroin nanofibrous scaffolds by both the two kinds of modification, and there was a hydrogen bonding between the silk fibroin and heparin. Moreover, the hydrophilicity, O-containing groups and negative charge density of the heparin-modified scaffolds were enhanced. In vitro coagulation time tests showed that the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) of the heparin-modified scaffolds were much higher than those of the pure silk fibroin scaffolds. L929 fibroblasts and EVCs spread and proliferated better on the heparin-modified scaffolds than on the pure silk fibroin scaffolds. Macrophages, neutrophils and lymphocytes were not observed in the heparin-modified scaffolds, which indicated that the modified scaffolds could induce minor inflammation in vivo. The results indicated that the electrospun heparin-modified silk fibroin nanofibrous scaffolds could be considered as ideal candidates for tissue engineering scaffolds. PMID:21182858

Wang, Shudong; Zhang, Youzhu; Wang, Hongwei; Dong, Zhihui

2011-03-01

53

Silk fibroin-based scaffolds for tissue engineering  

Science.gov (United States)

Silk fibroin (SF) from the Bombyx mori silkworm exhibits attractive potential applications as biomechanical materials, due to its unique mechanical and biological properties. This review outlines the structure and properties of SF, including of its biocompatibility and biodegradability. It highlights recent researches on the fabrication of various SF-based composites scaffolds that are promising for tissue engineering applications, and discusses synthetic methods of various SF-based composites scaffolds and valuable approaches for controlling cell behaviors to promote the tissue repair. The function of extracellular matrices and their interaction with cells are also reviewed here.

Li, Zi-Heng; Ji, Shi-Chen; Wang, Ya-Zhen; Shen, Xing-Can; Liang, Hong

2013-09-01

54

Preparation and characterization of silk fibroin as a biomaterial with potential for drug delivery  

OpenAIRE

Abstract Background Degummed silk fibroin from Bombyx mori (silkworm) has potential carrier capabilities for drug delivery in humans; however, the processing methods have yet to be comparatively analyzed to determine the differential effects on the silk protein properties, including crystalline structure and activity. Methods In this study, we treated degummed silk with four kinds of calcium-alcohol solutions, and performed secondary structure measureme...

Zhang Hao; Li Ling-ling; Dai Fang-yin; Zhang Hao-hao; Ni Bing; Zhou Wei; Yang Xia; Wu Yu-zhang

2012-01-01

55

Preparation and characterization of regenerated fiber from the aqueous solution of Bombyx mori cocoon silk fibroin  

Energy Technology Data Exchange (ETDEWEB)

The regenerated silk fibers with high strength and high biodegradability were prepared from the aqueous solution of Bombyx mori silk fibroin from cocoons with wet spinning method. Although the tensile strength of the regenerated silk fibroin fiber, 210 MPa is still half of the strength of native silk fiber, the diameter of the fiber is about 100 {mu}m which is suitable for monofilament of suture together with high biodegradability. The high concentration (30%, w/v) of the aqueous solution of the silk fibroin which corresponds to the high concentration in the middle silkgland of silkworm was obtained. This was performed by adjusting the pH of the aqueous solution to 10.4 which corresponds to pK{sub a} value of the OH group of Tyr residues in the silk fibroin. The mixed solvent, methanol/acetic acid (7:3 in volume ratio) was used as coagulant solvent for preparing the regenerated fiber. The structural change of silk fibroin fiber by stretching was monitored with both {sup 13}C solid state NMR and X-ray diffraction methods, indicating that the high strength of the fiber is related with the long-range orientation of the silk fibroin chain with {beta}-sheet structure.

Zhu Zhenghua [Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Department of Application Engineering, ZheJiang Vocational College of Economic and Trade, HangZhou, ZheJiang 310018 (China); Imada, Takuzo [Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Asakura, Tetsuo, E-mail: asakura@cc.tuat.ac.jp [Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)

2009-10-15

56

Properties and Biocompatibility of Chitosan and Silk Fibroin Blend Films for Application in Skin Tissue Engineering  

OpenAIRE

Chitosan/silk fibroin (CS/SF) blend films were prepared and evaluated for feasibility of using the films as biomaterial for skin tissue engineering application. Fourier transform infrared spectroscopy and differential scanning calorimetry analysis indicated chemical interaction between chitosan and fibroin. Chitosan enhanced ?-sheet conformation of fibroin and resulted in shifting of thermal degradation of the films. Flexibility, swelling index, and enzyme degradation were also increased by ...

Luangbudnark, Witoo; Viyoch, Jarupa; Laupattarakasem, Wiroon; Surakunprapha, Palakorn; Laupattarakasem, Pisamai

2012-01-01

57

Crystal growth of calcium carbonate in silk fibroin/sodium alginate hydrogel  

Science.gov (United States)

As known, silk fibroin-like protein plays a pivotal role during the formation of calcium carbonate (CaCO3) crystals in the nacre sheets. Here, we have prepared silk fibroin/sodium alginate nanofiber hydrogels to serve as templates for calcium carbonate mineralization. In this experiment, we report an interesting finding of calcium carbonate crystal growth in the silk fibroin/sodium alginate nanofiber hydrogels by the vapor diffusion method. The experimental results indicate calcium carbonate crystals obtained from nanofiber hydrogels with different proportions of silk fibroin/sodium alginate are mixture of calcite and vaterite with unusual morphologies. Time-dependent growth study was carried out to investigate the crystallization process. It is believed that nanofiber hydrogels play an important role in the process of crystallization. This study would help in understanding the function of organic polymers in natural mineralization, and provide a novel pathway in the design and synthesis of new materials related unique morphology and structure.

Ming, Jinfa; Zuo, Baoqi

2014-01-01

58

Effect of Silk Fibroin Content on the Bionic Mineralization and In Vitro Cellular Compatibility of Silk Fibroin/Hydroxyapaptite Nanocomposites  

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Full Text Available Silk fibroin and hydroxyapatite nanocomposites (SF/HA with various SF content were prepared. Effect of Silk fibroin content on the bionic mineralization and cellular compatibility in vitro of HA nanocrystals (n-HA was investigated. The results show that SF content has an obvious effect on the nucleation and growth of n-HA. However, though SF content does not show obvious difference on the nucleation and growth of n-HA, it has obvious effect on the n-HA aggregation. When SF content is less than 20wt%, n-HA orderly disperses in SF matrix. While the SF content is more than 20wt%, the n-HA aggregation becomes disordered. The in vitro cellular compatibility experiments demonstrate that the SF/HA composites exhibit better cell affinity than pure n-HA. However, SF content has no obvious effect on the cell affinity of n-SF/HA 20wt% SF/HA and 30wt% SF/HA show better osteoblast proliferation.

ZHU Yun-Rong, CHEN Yu-Yun, XU Guo-Hua, YE Xiao-Jian, ZHONG Jian, HE Dan-Nong

2012-08-01

59

Doxorubicin-loaded magnetic silk fibroin nanoparticles for targeted therapy of multidrug-resistant cancer.  

Science.gov (United States)

A strategy to prepare doxorubicin-loaded magnetic silk fibroin nanoparticles is presented. The nanoparticles serve as a nanometer-scale drug-delivery system in the chemotherapy of multidrug-resistant cancer under the guidance of a magnetic field. The magnetic tumor-targeting ability broadens the range of biomedical applications of silk fibroin, and the nanoparticle-assisted preparation strategy is useful for the advancement of other biomacromolecule-based materials. PMID:25238148

Tian, Ye; Jiang, Xuejiao; Chen, Xin; Shao, Zhengzhong; Yang, Wuli

2014-11-19

60

Cytocompatibility of regenerated silk fibroin film: a medical biomaterial applicable to wound healing*  

OpenAIRE

Objective: To explore the feasibility of using regenerated silk fibroin membrane to construct artificial skin substitutes for wound healing, it is necessary to evaluate its cytocompatibility. Methods: The effects of regenerated silk fibroin film on cytotoxicity, adhesion, cell cycle, and apoptosis of L929 cells, growth and vascular endothelial growth factor (VEGF) expression of ECV304 cells, and VEGF, angiopoietin-1 (Ang-1), platelet-derived growth factor (PDGF) and fibroblast growth factor 2...

Liu, Tie-lian; Miao, Jing-cheng; Sheng, Wei-hua; Xie, Yu-feng; Huang, Quan; Shan, Yun-bo; Yang, Ji-cheng

2010-01-01

61

Apatite-coated Silk Fibroin Scaffolds to Healing Mandibular Border Defects in Canines  

OpenAIRE

Tissue engineering has become a new approach for repairing bony defects. Highly porous osteoconductive scaffolds perform the important role for the success of bone regeneration. By biomimetic strategy, apatite-coated porous biomaterial based on silk fibroin scaffolds (SS) might provide an enhanced osteogenic environment for bone-related outcomes. To assess the effects of apatite-coated silk fibroin (mSS) biomaterials for bone healing as a tissue engineered bony scaffold, we explored a tissue ...

Zhao, Jun; Zhang, Zhiyuan; Wang, Shaoyi; Sun, Xiaojuan; Zhang, Xiuli; Chen, Jake; Kaplan, David L.; Jiang, Xinquan

2009-01-01

62

Physico-chemical properties and in vitro response of silk fibroin from various domestic races.  

Science.gov (United States)

In this study, the characteristics of silk fibroin films obtained from regenerated aqueous silk fibroin solution of various races were evaluated. Three races based on original sources of silkworms were selected: Nangnoi-Sisaket 1 (NN), Nakhon Ratchasima 1 (K1), and Nakhon Ratchasima 2 (K8). The Tg and Td of silk fibroin films were around 147-156°C and 277-279°C, respectively. FTIR result revealed that all silk fibroin films had beta sheet conformation. K1 and K8 films were found to be more hydrophilic than NN film. From in vitro tests using L929 mouse fibroblast and rat bone marrow-derived stem cells (rMSCs), the cell attachment was slightly greater on K1 film than the other two films. The enhanced cell growth on K1 film might be related to its slightly high hydrophilicity and the higher content of serine. The result of osteogenic differentiation test showed that alkaline phosphatase and deposited mineral of rMSCs were higher on all silk fibroin films than on tissue culture plate. K1 film tended to promote osteogenic differentiation of rMSCs to a higher extent than NN and K8 films. K1 silk fibroin film exhibited a higher potential to support cell attachment, proliferation, and differentiation than other two films. PMID:24652683

Kaewprasit, Kanyaluk; Promboon, Amornrat; Kanokpanont, Sorada; Damrongsakkul, Siriporn

2014-11-01

63

Improving the mechanical properties of collagen-based membranes using silk fibroin for corneal tissue engineering.  

Science.gov (United States)

Although collagen with outstanding biocompatibility has promising application in corneal tissue engineering, the mechanical properties of collagen-based scaffolds, especially suture retention strength, must be further improved to satisfy the requirements of clinical applications. This article describes a toughness reinforced collagen-based membrane using silk fibroin. The collagen-silk fibroin membranes based on collagen [silk fibroin (w/w) ratios of 100:5, 100:10, and 100:20] were prepared by using silk fibroin and cross-linking by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. These membranes were analyzed by scanning electron microscopy and their optical property, and NaCl and tryptophan diffusivity had been tested. The water content was found to be dependent on the content of silk fibroin, and CS10 membrane (loading 10 wt % of silk fibroin) performed the optimal mechanical properties. Also the suture experiments have proved CS10 has high suture retention strength, which can be sutured in rabbit eyes integrally. Moreover, the composite membrane proved good biocompatibility for the proliferation of human corneal epithelial cells in vitro. Lamellar keratoplasty shows that CS10 membrane promoted complete epithelialization in 35 ± 5 days, and their transparency is restored quickly in the first month. Corneal rejection reaction, neovascularization, and keratoconus are not observed. The composite films show potential for use in the field of corneal tissue engineering. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1159-1168, 2015. PMID:25044509

Long, Kai; Liu, Yang; Li, Weichang; Wang, Lin; Liu, Sa; Wang, Yingjun; Wang, Zhichong; Ren, Li

2015-03-01

64

A Juvenile Hormone Transcription Factor Bmdimm-Fibroin H Chain Pathway Is Involved in the Synthesis of Silk Protein in Silkworm, Bombyx mori.  

Science.gov (United States)

The genes responsible for silk biosynthesis are switched on and off at particular times in the silk glands of Bombyx mori. This switch appears to be under the control of endogenous and exogenous hormones. However, the molecular mechanisms by which silk protein synthesis is regulated by the juvenile hormone (JH) are largely unknown. Here, we report a basic helix-loop-helix transcription factor, Bmdimm, its silk gland-specific expression, and its direct involvement in the regulation of fibroin H-chain (fib-H) by binding to an E-box (CAAATG) element of the fib-H gene promoter. Far-Western blots, enzyme-linked immunosorbent assays, and co-immunoprecipitation assays revealed that Bmdimm protein interacted with another basic helix-loop-helix transcription factor, Bmsage. Immunostaining revealed that Bmdimm and Bmsage proteins are co-localized in nuclei. Bmdimm expression was induced in larval silk glands in vivo, in silk glands cultured in vitro, and in B. mori cell lines after treatment with a JH analog. The JH effect on Bmdimm was mediated by the JH-Met-Kr-h1 signaling pathway, and Bmdimm expression did not respond to JH by RNA interference with double-stranded BmKr-h1 RNA. These data suggest that the JH regulatory pathway, the transcription factor Bmdimm, and the targeted fib-H gene contribute to the synthesis of fibroin H-chain protein in B. mori. PMID:25371208

Zhao, Xiao-Ming; Liu, Chun; Jiang, Li-Jun; Li, Qiong-Yan; Zhou, Meng-Ting; Cheng, Ting-Cai; Mita, Kazuei; Xia, Qing-You

2015-01-01

65

Microrheological Studies of Regenerated Silk Fibroin Solution by Video Microscopy  

CERN Document Server

We have carried out studies on the rheological properties of regenerated silk fibroin (RSF) solution using video microscopy. The degummed silk from the Bombyx mori silkworm was used to prepare RSF solution by dissolving it in calcium nitrate tetrahydrate-methanol solvent. Measurements were carried out by tracking the position of an embedded micron-sized polystyrene bead within the RSF solution through video imaging. The time dependent mean squared displacement (MSD) of the bead in solution and hence, the complex shear modulus of this solution was calculated from the bead's position information. An optical tweezer was used to transport and locate the bead at any desired site within the micro-volume of the sample, to facilitate the subsequent free-bead video analysis. We present here the results of rheological measurements of the silk polymer network in solution over a frequency range, whose upper limit is the frame capture rate of our camera, at full resolution. By examining the distribution of MSD of beads at...

Raghu, A; Somashekar, R; Ananthamurthy, Sharath

2007-01-01

66

Folding process of silk fibroin induced by ferric and ferrous ions  

Science.gov (United States)

Bombyx mori silk fiber has useful mechanical properties largely due to a high content of ordered ?-sheet crystallites separated by non-crystalline spacers. Metallic ions present in the silk dope in nature could affect the ?-sheet content. In this work, we used solid-state 13C NMR, EPR and Raman spectroscopy to investigate how the ferric/ferrous ions affect the folding process of the silk fibroin. NMR and Raman results indicate that ferric and ferrous ions have different effects on the secondary structure of silk fibroin. Ferric ions can induce a conformation change from helix to ?-sheet form in silk fibroin when their concentration exceeds a critical value, while ferrous ions cannot. EPR results indicate that the ferric ions bound with silk fibroin have a high-spin state ( S = 5/2) with g-value of g1 = 1.950, g2 = 1.990 and g3 = 1.995, zero-field splitting interaction D of 1.2-2 cm -1, and symmetric character of E/ D = 1/3, resulting in an effective g-value of g' = 4.25. The hydrophilic spacer GTGSSGFGPYVAN(H)GGYSGYEYAWSSESDFGT in the heavy chain of silk fibroin is likely to be involved in the binding of ferric ions, and His, Asn and Tyr residues are considered as the potential binding sites.

Ji, Dan; Deng, Yi-Bin; Zhou, Ping

2009-12-01

67

Silk Fibroin Film Loaded Chlorhexidine Diacetate: Interaction and Characteristics  

Directory of Open Access Journals (Sweden)

Full Text Available This study aimed to prepare Silk Fibroin (SF films with different weight (0.5, 1 and 1.5% for loading chlorhexidine diacetate as substrate for study their characteristics including morphology, structure and thermal properties. The morphological observation under scanning electron spectroscopy found that all of films have a smooth surface. With cross-section micrographs, the lowest SF content was smoother texture than other. The secondary structures of various films were determined by Fourier transform infrared (FTIR spectrometer. The results showed that SF film composed of ?-sheet structures in different ratio depending on the SF content. The result suggested that high SF content formed crystalline by interaction between amino acids molecules in higher ratio than other. However, thermal properties of the SF films did not dramatically differ compared between low and high SF content. It was also found that CHX did not affect on the SF characteristics.

N. Noi

2009-01-01

68

Artificial crawler model for texture analysis on silk fibroin scaffolds  

Science.gov (United States)

Texture plays an important role in computer vision tasks. Several methods of texture analysis are available. However, these methods are not capable of extracting rich detail in images. This paper presents a novel approach to image texture classification based on the artificial crawler model. Here, we propose a new rule of movement that moves artificial crawler agents not only toward higher intensities but also toward lower ones. This strategy is able of capturing more detail because the agents explore the peaks as well as the valleys. Thus, compared with the state-of-the-art method, this approach shows an increased discriminatory power. Experiments on the most well known benchmark demonstrate the superior performance of our approach. We also tested our approach on silk fibroin scaffold analysis, and results indicate that our method is consistent and can be applied in real-world situations.

Brandoli Machado, Bruno; Nunes Gonçalves, Wesley; Martinez Bruno, Odemir

2014-01-01

69

Antimicrobial Silk Fibroin Hydrogel Instantaneously Induced by Cationic Surfactant  

Directory of Open Access Journals (Sweden)

Full Text Available Current surgical dressings and woundplast have drawbacks such as poor permeability, airtightness and biocompatibility, thus a new material is obligatory to replace the traditional ones. Due to outstanding biocompatibility of Silk Fibroin (SF and excellent antibacterial properties of Dodecyl Trimethyl Ammonium Bromide (DTAB, a cationic surfactant, the SF/DTAB hydrogel formed instantaneously is recommended. By means of SEM, FTIR and XRD, SF/DTAB hydrogel displayed clustered nanofilaments structure and similar secondary structure and morphology with SF solution mainly consisted of random coils in 1 h, then it tended to be the same as pure SF hydrogel which was composed of porous network structure and primarily contained ?-sheet structure. Excellent elasticity and antibacterial effect were verified by rheological and antibacterial measurements.

Shan Sun

2013-01-01

70

CO2-assisted synthesis of silk fibroin hydrogels and aerogels.  

Science.gov (United States)

Biocompatible and biodegradable porous materials based on silk fibroin (SF), a natural protein derived from the Bombyx mori silkworm, are being extensively investigated for use in biomedical applications including mammalian cell bioprocessing, tissue engineering and drug delivery applications. In this work, low-pressure, gaseous CO2 is used as an acidifying agent to fabricate SF hydrogels. This low-pressure CO2 acidification method is compared to an acidification method using high-pressure CO2 to demonstrate the effect of CO2 mass transfer and pressure on SF sol-gel kinetics. The effect of SF molecular weight on the sol-gel kinetics is determined using the low-pressure CO2 method. The results from these studies demonstrate that low-pressure CO2 processing proves to be a facile method for synthesizing 3-D SF hydrogels. PMID:24954908

Mallepally, Rajendar R; Marin, Michael A; McHugh, Mark A

2014-10-01

71

Innovative multifunctional silk fibroin and hydrotalcite nanocomposites: a synergic effect of the components.  

Science.gov (United States)

Novel hybrid functional materials are formed by combining hydrotalcite-like compounds and silk fibroin (SF-HTlc) via an environmental friendly aqueous process. The nanocomposites can be prepared with different weight ratio of the constituting components and preserve the conformational properties of the silk protein and the lamellar structure of hydrotalcites. Optical microscopy, scanning electron microscopy, and atomic force microscopy analyses show a good dispersion degree of the inorganic nanoparticles into the organic silk matrix. A mutual benefit on the stability of both organic and inorganic components was observed in the nanocomposites. SF-HTlc displayed limited dissolution of hydrotalcite in acidic medium, enhanced mechanical properties, and higher protease resistance of silk protein. The transparency, flexibility, and acidic environment resistance of silk fibroin combined to the protective and reinforcing properties of hydrotalcites generate a hybrid material, which is very attractive for applications in recently reported silk based opto-electronic and photonics technologies. PMID:24313841

Posati, Tamara; Benfenati, Valentina; Sagnella, Anna; Pistone, Assunta; Nocchetti, Morena; Donnadio, Anna; Ruani, Giampiero; Zamboni, Roberto; Muccini, Michele

2014-01-13

72

Optimization of the silk scaffold sericin removal process for retention of silk fibroin protein structure and mechanical properties.  

Science.gov (United States)

In the process of removing sericin (degumming) from a raw silk scaffold, the fibroin structural integrity is often challenged, leading to mechanical depreciation. This study aims to identify the factors and conditions contributing to fibroin degradation during alkaline degumming and to perform an optimization study of the parameters involved to achieve preservation of fibroin structure and properties. The methodology involves degumming knitted silk scaffolds for various durations (5-90 min) and temperatures (60-100 degrees C). Mechanical agitation and use of the refreshed solution during degumming are included to investigate how these factors contribute to degumming efficiency and fibroin preservation. Characterizations of silk fibroin morphology, mechanical properties and protein components are determined by scanning electron microscopy (SEM), single fiber tensile tests and gel electrophoresis (SDS-PAGE), respectively. Sericin removal is ascertained via SEM imaging and a protein fractionation method involving SDS-PAGE. The results show that fibroin fibrillation, leading to reduced mechanical integrity, is mainly caused by prolonged degumming duration. Through a series of optimization, knitted scaffolds are observed to be optimally degummed and experience negligible mechanical and structural degradation when subjected to alkaline degumming with mechanical agitation for 30 min at 100 degrees C. PMID:20460689

Teh, Thomas K H; Toh, Siew-Lok; Goh, James C H

2010-05-11

73

Optimization of the silk scaffold sericin removal process for retention of silk fibroin protein structure and mechanical properties  

International Nuclear Information System (INIS)

In the process of removing sericin (degumming) from a raw silk scaffold, the fibroin structural integrity is often challenged, leading to mechanical depreciation. This study aims to identify the factors and conditions contributing to fibroin degradation during alkaline degumming and to perform an optimization study of the parameters involved to achieve preservation of fibroin structure and properties. The methodology involves degumming knitted silk scaffolds for various durations (5-90 min) and temperatures (60-100 0C). Mechanical agitation and use of the refreshed solution during degumming are included to investigate how these factors contribute to degumming efficiency and fibroin preservation. Characterizations of silk fibroin morphology, mechanical properties and protein components are determined by scanning electron microscopy (SEM), single fiber tensile tests and gel electrophoresis (SDS-PAGE), respectively. Sericin removal is ascertained via SEM imaging and a protein fractionation method involving SDS-PAGE. The results show that fibroin fibrillation, leading to reduced mechanical integrity, is mainly caused by prolonged degumming duration. Through a series of optimization, knitted scaffolds are observed to be optimally degummed and experience negligible mechanical and structural degradation when subjected to alkaline degumming with mechanical agitation for 30 min at 100 0C.

74

Optimization of the silk scaffold sericin removal process for retention of silk fibroin protein structure and mechanical properties  

Energy Technology Data Exchange (ETDEWEB)

In the process of removing sericin (degumming) from a raw silk scaffold, the fibroin structural integrity is often challenged, leading to mechanical depreciation. This study aims to identify the factors and conditions contributing to fibroin degradation during alkaline degumming and to perform an optimization study of the parameters involved to achieve preservation of fibroin structure and properties. The methodology involves degumming knitted silk scaffolds for various durations (5-90 min) and temperatures (60-100 {sup 0}C). Mechanical agitation and use of the refreshed solution during degumming are included to investigate how these factors contribute to degumming efficiency and fibroin preservation. Characterizations of silk fibroin morphology, mechanical properties and protein components are determined by scanning electron microscopy (SEM), single fiber tensile tests and gel electrophoresis (SDS-PAGE), respectively. Sericin removal is ascertained via SEM imaging and a protein fractionation method involving SDS-PAGE. The results show that fibroin fibrillation, leading to reduced mechanical integrity, is mainly caused by prolonged degumming duration. Through a series of optimization, knitted scaffolds are observed to be optimally degummed and experience negligible mechanical and structural degradation when subjected to alkaline degumming with mechanical agitation for 30 min at 100 {sup 0}C.

Teh, Thomas K H; Toh, Siew-Lok; Goh, James C H, E-mail: dosgohj@nus.edu.s, E-mail: dostkh@nus.edu.s, E-mail: bietohsl@nus.edu.s [Division of Bioengineering, National University of Singapore (Singapore)

2010-06-01

75

In vitro evaluation of bi-layer silk fibroin scaffolds for gastrointestinal tissue engineering  

Science.gov (United States)

Silk fibroin scaffolds were investigated for their ability to support attachment, proliferation, and differentiation of human gastrointestinal epithelial and smooth muscle cell lines in order to ascertain their potential for tissue engineering. A bi-layer silk fibroin matrix composed of a porous silk fibroin foam annealed to a homogeneous silk fibroin film was evaluated in parallel with small intestinal submucosa scaffolds. AlamarBlue analysis revealed that silk fibroin scaffolds supported significantly higher levels of small intestinal smooth muscle cell, colon smooth muscle cell, and esophageal smooth muscle cell attachment in comparison to small intestinal submucosa. Following 7?days of culture, relative numbers of each smooth muscle cell population maintained on both scaffold groups were significantly elevated over respective 1-day levels—indicative of cell proliferation. Real-time reverse transcription polymerase chain reaction and immunohistochemical analyses demonstrated that both silk fibroin and small intestinal submucosa scaffolds were permissive for contractile differentiation of small intestinal smooth muscle cell, colon smooth muscle cell, esophageal smooth muscle cell as determined by significant upregulation of ?-smooth muscle actin and SM22? messenger RNA and protein expression levels following transforming growth factor-?1 stimulation. AlamarBlue analysis demonstrated that both matrix groups supported similar degrees of attachment and proliferation of gastrointestinal epithelial cell lines including colonic T84 cells and esophageal epithelial cells. Following 14?days of culture on both matrices, spontaneous differentiation of T84 cells toward an enterocyte lineage was confirmed by expression of brush border enzymes, lactase, and maltase, as determined by real-time reverse transcription polymerase chain reaction and immunohistochemical analyses. In contrast to small intestinal submucosa scaffolds, silk fibroin scaffolds supported spontaneous differentiation of esophageal epithelial cells toward a suprabasal cell lineage as indicated by significant upregulation of cytokeratin 4 and cytokeratin 13 messenger RNA transcript levels. In addition, esophageal epithelial cells maintained on silk fibroin scaffolds also produced significantly higher involucrin messenger RNA transcript levels in comparison to small intestinal submucosa counterparts, indicating an increased propensity for superficial, squamous cell specification. Collectively, these data provide evidence for the potential of silk fibroin scaffolds for gastrointestinal tissue engineering applications. PMID:25396043

Franck, Debra; Chung, Yeun Goo; Coburn, Jeannine; Kaplan, David L; Estrada, Carlos R

2014-01-01

76

In vitro evaluation of bi-layer silk fibroin scaffolds for gastrointestinal tissue engineering.  

Science.gov (United States)

Silk fibroin scaffolds were investigated for their ability to support attachment, proliferation, and differentiation of human gastrointestinal epithelial and smooth muscle cell lines in order to ascertain their potential for tissue engineering. A bi-layer silk fibroin matrix composed of a porous silk fibroin foam annealed to a homogeneous silk fibroin film was evaluated in parallel with small intestinal submucosa scaffolds. AlamarBlue analysis revealed that silk fibroin scaffolds supported significantly higher levels of small intestinal smooth muscle cell, colon smooth muscle cell, and esophageal smooth muscle cell attachment in comparison to small intestinal submucosa. Following 7?days of culture, relative numbers of each smooth muscle cell population maintained on both scaffold groups were significantly elevated over respective 1-day levels-indicative of cell proliferation. Real-time reverse transcription polymerase chain reaction and immunohistochemical analyses demonstrated that both silk fibroin and small intestinal submucosa scaffolds were permissive for contractile differentiation of small intestinal smooth muscle cell, colon smooth muscle cell, esophageal smooth muscle cell as determined by significant upregulation of ?-smooth muscle actin and SM22? messenger RNA and protein expression levels following transforming growth factor-?1 stimulation. AlamarBlue analysis demonstrated that both matrix groups supported similar degrees of attachment and proliferation of gastrointestinal epithelial cell lines including colonic T84 cells and esophageal epithelial cells. Following 14?days of culture on both matrices, spontaneous differentiation of T84 cells toward an enterocyte lineage was confirmed by expression of brush border enzymes, lactase, and maltase, as determined by real-time reverse transcription polymerase chain reaction and immunohistochemical analyses. In contrast to small intestinal submucosa scaffolds, silk fibroin scaffolds supported spontaneous differentiation of esophageal epithelial cells toward a suprabasal cell lineage as indicated by significant upregulation of cytokeratin 4 and cytokeratin 13 messenger RNA transcript levels. In addition, esophageal epithelial cells maintained on silk fibroin scaffolds also produced significantly higher involucrin messenger RNA transcript levels in comparison to small intestinal submucosa counterparts, indicating an increased propensity for superficial, squamous cell specification. Collectively, these data provide evidence for the potential of silk fibroin scaffolds for gastrointestinal tissue engineering applications. PMID:25396043

Franck, Debra; Chung, Yeun Goo; Coburn, Jeannine; Kaplan, David L; Estrada, Carlos R; Mauney, Joshua R

2014-01-01

77

Silk Fibroin as an Organic Polymer for Controlled Drug Delivery  

Energy Technology Data Exchange (ETDEWEB)

The pharmaceutical utility of silk fibroin (SF) materials for drug delivery was investigated. SF films were prepared from aqueous solutions of the fibroin protein polymer and crystallinity was induced and controlled by methanol treatment. Dextrans of different molecular weights, as well as proteins, were physically entrapped into the drug delivery device during processing into films. Drug release kinetics were evaluated as a function of dextran molecular weight, and film crystallinity. Treatment with methanol resulted in an increase in {beta}-sheet structure, an increase in crystallinity and an increase in film surface hydrophobicity determined by FTIR, X-ray and contact angle techniques, respectively. The increase in crystallinity resulted in the sustained release of dextrans of molecular weights ranging from 4 to 40 kDa, whereas for less crystalline films sustained release was confined to the 40 kDa dextran. Protein release from the films was studied with horseradish peroxidase (HRP) and lysozyme (Lys) as model compounds. Enzyme release from the less crystalline films resulted in a biphasic release pattern, characterized by an initial release within the first 36 h, followed by a lag phase and continuous release between days 3 and 11. No initial burst was observed for films with higher crystallinity and subsequent release patterns followed linear kinetics for HRP, or no substantial release for Lys. In conclusion, SF is an interesting polymer for drug delivery of polysaccharides and bioactive proteins due to the controllable level of crystallinity and the ability to process the biomaterial in biocompatible fashion under ambient conditions to avoid damage to labile compounds to be delivered.

Hofmann,S.; Wong Po Foo, C.; Rossetti, F.; Textor, M.; Vunjak-Novakovic, G.; Kaplan, D.; Merkle, H.; Meinel, L.

2006-01-01

78

Effect of freezing methods on the properties of lyophilized porous silk fibroin membranes  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Silk fibroin is a fibrous protein that has been extensively studied for application in the biomedical field, and has been used as a scaffold for bone tissue engineering. Biomaterials made of proteins are prone to physical and chemical degradation during storage; lyophilization, a drying method that [...] consists of freezing and drying steps, is known to promote minimal changes in structure and biological activity of biomaterials. This study evaluates the effect of freezing methods on the properties of lyophilized porous silk fibroin membranes. The membranes were obtained from silk fibroin solution, frozen in liquid nitrogen or ultrafreezer, lyophilized, and then characterized by XRD, FTIR, TGA, DSC and SEM. Although the membranes presented similar physical, chemical and microstructural characteristics, quench freezing with liquid nitrogen, followed by lyophilization, promoted collapse of the membranes, while slow cooling performed by ultrafreezer preserved membrane integrity.

Raquel Farias, Weska; Wellington Carlos, Vieira Jr.; Grínia Michelle, Nogueira; Marisa Masumi, Beppu.

2009-06-01

79

Preparation and evaluation of collagen-silk fibroin/hydroxyapatite nanocomposites for bone tissue engineering.  

Science.gov (United States)

A new in situ precipitation technique was developed to synthesize collagen-silk fibroin/hydroxyapatite nanocomposites. The componential properties and morphological of nanocomposites were investigated. It was revealed that the inorganic phase in the nanocomposite was carbonate-substituted hydroxyapatite with low crystallinity. Morphology studies showed that hydroxyapatite particles with size ranging from 30 to 100 nm were distributed uniformly in the polymer matrix. According to the TEM micrographs, inorganic particles were composed of more fine sub-particles whose diameters were between 2 and 5 nm in size without regular crystallographic orientation. The mechanical properties of the composites were evaluated by measuring their elastic modulus. The data indicated that the elastic modulus of nanocomposites was improved by the addition of silk fibroin. Finally, the cell biocompatibility of the composites was tested in vitro, which showed that they have good biocompatibility. These results suggest that the collagen-silk fibroin/hydroxyapatite nanocomposites are promising biomaterials for bone tissue engineering. PMID:24412151

Chen, Li; Hu, Jingxiao; Ran, Jiabing; Shen, Xinyu; Tong, Hua

2014-04-01

80

Fabrication of a corneal-limbal tissue substitute using silk fibroin.  

Science.gov (United States)

Fibroin extracted from silkworm cocoon silk provides an intriguing and potentially important biomaterial for corneal reconstruction. In this chapter we outline our methods for producing a composite of two fibroin-based materials that support the cocultivation of human limbal epithelial (HLE) cells and human limbal stromal (HLS) cells. The resulting tissue substitute consists of a stratified epithelium overlying a three-dimensional arrangement of extracellular matrix components (principally "degummed" fibroin fibers) and mesenchymal stromal cells. This tissue substitute is currently being evaluated as a tool for reconstructing the corneal limbus and corneal epithelium. PMID:23690012

Bray, Laura J; George, Karina A; Suzuki, Shuko; Chirila, Traian V; Harkin, Damien G

2013-01-01

81

Fabrication of silk fibroin nanoparticles for controlled drug delivery  

International Nuclear Information System (INIS)

A novel solution-enhanced dispersion by supercritical CO2 (SEDS) was employed to prepare silk fibroin (SF) nanoparticles. The resulting SF nanoparticles exhibited a good spherical shape, a smooth surface, and a narrow particle size distribution with a mean particle diameter of about 50 nm. The results of X-ray powder diffraction, thermo gravimetry-differential scanning calorimetry, and Fourier transform infrared spectroscopy analysis of the SF nanoparticles before and after ethanol treatment indicated conformation transition of SF nanoparticles from random coil to ?-sheet form and thus water insolubility. The MTS assay also suggested that the SF nanoparticles after ethanol treatment imposed no toxicity. A non-steroidal anti-inflammatory drug, indomethacin (IDMC), was chosen as the model drug and was encapsulated in SF nanoparticles by the SEDS process. The resulting IDMC–SF nanoparticles, after ethanol treatment, possessed a theoretical average drug load of 20%, an actual drug load of 2.05%, and an encapsulation efficiency of 10.23%. In vitro IDMC release from the IDMC–SF nanoparticles after ethanol treatment showed a significantly sustained release over 2 days. These studies of SF nanoparticles indicated the suitability of the SF nanoparticles prepared by the SEDS process as a biocompatible carrier to deliver drugs and also the feasibility of using the SEDS process to reach the goal of co-precipitation of drug and SF as composite nanoparticles for conSF as composite nanoparticles for controlled drug delivery.

82

Electrospun regenerated silk fibroin mats with enhanced mechanical properties.  

Science.gov (United States)

In this paper, a simple and effective method was applied to enhance regenerated silk fibroin (RSF) mats electrospun from aqueous solution. The mats were first mechanically drawn in 90 vol.% ethanol aqueous solution and then immersed in the same solution for 30 min. The morphology, structure, thermal and mechanical properties of the RSF mats with different draw rates and draw ratios were investigated by scanning electron microscope (SEM), Raman spectroscopy, wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and tensile test. Results revealed that the content of ?-sheet conformation, the crystallinity and the number of fibers aligned to the drawing direction increased evidently with the draw ratio. The breaking strength and breaking energy of the post-treated mats at 1.4× draw ratio and 0.1mm/s draw rate were 8.6 MPa and 172.2 J/kg, respectively. However, those of the as-spun mats were only 1.8 MPa and 93.2 J/kg, respectively. The enhanced RSF mats prepared from entirely aqueous solutions may have extensive applications for tissue engineering. PMID:23403022

Fan, Suna; Zhang, Yaopeng; Shao, Huili; Hu, Xuechao

2013-05-01

83

Silk fibroin porous scaffolds for nucleus pulposus tissue engineering.  

Science.gov (United States)

Intervertebral discs (IVDs) are structurally complex tissue that hold the vertebrae together and provide mobility to spine. The nucleus pulposus (NP) degeneration often results in degenerative IVD disease that is one of the most common causes of back and neck pain. Tissue engineered nucleus pulposus offers an alternative approach to regain the function of the degenerative IVD. The aim of this study is to determine the feasibility of porous silk fibroin (SF) scaffolds fabricated by paraffin-sphere-leaching methods with freeze-drying in the application of nucleus pulposus regeneration. The prepared scaffold possessed high porosity of 92.38±5.12% and pore size of 165.00±8.25?m as well as high pore interconnectivity and appropriate mechanical properties. Rabbit NP cells were seeded and cultured on the SF scaffolds. Scanning electron microscopy, histology, biochemical assays and mechanical tests revealed that the porous scaffolds could provide an appropriate microstructure and environment to support adhesion, proliferation and infiltration of NP cells in vitro as well as the generation of extracellular matrix. The NP cell-scaffold construction could be preliminarily formed after subcutaneously implanted in a nude mice model. In conclusion, The SF porous scaffold offers a potential candidate for tissue engineered NP tissue. PMID:24582244

Zeng, Chao; Yang, Qiang; Zhu, Meifeng; Du, Lilong; Zhang, Jiamin; Ma, Xinlong; Xu, Baoshan; Wang, Lianyong

2014-04-01

84

The Cytocompatibility of Genipin-Crosslinked Silk Fibroin Films  

Directory of Open Access Journals (Sweden)

Full Text Available There is an increasing demand for crosslinking methods of silk fibroin (SF scaffolds in biomedical applications that could maintain the biocompatibility, bioactivity as well as improve the water resistance and mechanical properties of SF materials. In this study, SF was crosslinked effectively with genipin which is a naturally occurring iridoid glucoside and the crosslinking mechanism was investigated through FTIR and amino acid analysis. The results showed that genipin could react with the -NH2 groups on the side chains of SF macromolecules and to form inter- and intra-molecular covalent bonds, and improved the stability of SF materials significantly. In vitro, the performances of genipin-crosslinked SF films were assessed by seeding L929 cells and compared with ethanol-processed SF films, glutaraldehyde and polyethylene glycol diglycidyl ether crosslinked ones. The genipin-crosslinked SF films showed a similar affinity to cells as ethanol-processed ones, and a higher bioactivity in promoting cell growth and proliferation, inhibition of cell apoptosis, and maintenance of normal cell cycle compared with glutaraldehyde and polyethylene glycol diglycidyl ether crosslinked SF films. These features, combined with the decrease of brittleness of SF films crosslinked with chemical methods, substantiated genipin as an effective and biocompatible agent for the manufacturing of bioactive SF materials which used as tissue engineering scaffolds and drug delivery carriers.

Lingshuang Wang

2013-06-01

85

Stability and cytocompatibility of silk fibroin-capped gold nanoparticles.  

Science.gov (United States)

Surface engineering is crucial in the colloidal stability and biocompatibility of nanoparticles (NPs). Protein silk fibroin (SF), which gained interest in biomaterial and regenerative medicine, was used in this study to stabilize gold (Au) NPs. Characterization results from UV-Vis spectroscopy revealed that SF-capped Au NPs (SF-Au NPs) possessed remarkable colloidal stabilities in the pH range of 2 to 11 and salt concentration range of 50mM to 1000 mM. In addition, dried particle samples were resuspended after lyophilization without aggregation. The results indicated that the steric hindrance rather than the electrostatic repulsion of SF-Au NPs was essential for colloidal stability. The SF-Au NPs manifested improved cytocompatibility compared with bare Au NPs, which was attributed to the inherent non-cytotoxicity of SF and the good colloidal stability of the NPs. The proposed method was simpler, more efficient, and more cost effective than the conventional modification strategies for Au NPs; thus, SF-Au NPs can be potentially used in biomedical applications. PMID:25175209

Jia, Lan; Guo, Li; Zhu, Jingxin; Ma, Yanlong

2014-10-01

86

Preparation and Characterization of Nanocomposite and Nanoporous Silk Fibroin Films  

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Full Text Available Nanocomposite and nanoporous silk fibroin (SF films were prepared by film casting of SF solution containing surfactant-free colloidal nanoparticles of methoxy poly (ethylene glycol-b-poly (D, L-lactide diblock copolymer (MPEG-b-PDLL. Self-condensation and nanophase separation of the nanoparticles from SF film matrix during film drying process gave nanopore structures. The colloidal nanoparticles were prepared in SF solution by modified-spontaneous emulsification solvent diffusion method without any surfactant. The interaction between SF and MPEG-b-PDLL in nanocomposite films was studied by Fourier transform infrared spectroscopy and thermogravimetry. The film transparency of SF nanocomposite films decreased as increasing the MPEG-b-PDLL ratio. Scanning Electron Microscopy (SEM results indicated that the nanoparticle sizes in the films were in the range of 50-200 nm with spherical shape. Nanopore structures with pore size of less than 150 nm can be observed from SEM images of the film surface and cross-section. The nanopores are interconnected throughout the nanocomposite films. The number and size of nanoparticles and nanopores increased when the MPEG-b-PDLL ratio was increased.

Yaowalak Srisuwan

2008-01-01

87

Fabrication of silk fibroin nanoparticles for controlled drug delivery  

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A novel solution-enhanced dispersion by supercritical CO{sub 2} (SEDS) was employed to prepare silk fibroin (SF) nanoparticles. The resulting SF nanoparticles exhibited a good spherical shape, a smooth surface, and a narrow particle size distribution with a mean particle diameter of about 50 nm. The results of X-ray powder diffraction, thermo gravimetry-differential scanning calorimetry, and Fourier transform infrared spectroscopy analysis of the SF nanoparticles before and after ethanol treatment indicated conformation transition of SF nanoparticles from random coil to {beta}-sheet form and thus water insolubility. The MTS assay also suggested that the SF nanoparticles after ethanol treatment imposed no toxicity. A non-steroidal anti-inflammatory drug, indomethacin (IDMC), was chosen as the model drug and was encapsulated in SF nanoparticles by the SEDS process. The resulting IDMC-SF nanoparticles, after ethanol treatment, possessed a theoretical average drug load of 20%, an actual drug load of 2.05%, and an encapsulation efficiency of 10.23%. In vitro IDMC release from the IDMC-SF nanoparticles after ethanol treatment showed a significantly sustained release over 2 days. These studies of SF nanoparticles indicated the suitability of the SF nanoparticles prepared by the SEDS process as a biocompatible carrier to deliver drugs and also the feasibility of using the SEDS process to reach the goal of co-precipitation of drug and SF as composite nanoparticles for controlled drug delivery.

Zhao Zheng; Chen Aizheng; Li Yi, E-mail: tcliyi@polyu.edu.hk; Hu Junyan; Liu Xuan; Li Jiashen; Zhang Yu; Li Gang; Zheng Zijian [Hong Kong Polytechnic University, Institute of Textiles and Clothing (Hong Kong)

2012-03-15

88

Synthesis and characterization of dense membranes of silk fibroin with glycerin  

International Nuclear Information System (INIS)

The addition of plasticizers seeks improvements in mechanical properties of dense membranes of silk fibroin with possible interactions by hydrogen bonds. The aim of the present study was to produce and characterize dense membranes of silk fibroin containing glycerin in two different concentrations. The characterization of the membranes was performed from scanning electron microscopy (SEM), mechanical traction tests, infrared spectroscopy (FTIR-ATR) and X-ray diffraction (XRD). The results indicated that the addition of glycerin allowed obtaining homogeneous and more crystalline membranes and improved their properties of elongation. (author)

89

The role of dialysis and freezing on structural conformation, thermal properties and morphology of silk fibroin hydrogels.  

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Silk fibroin has been widely explored for many biomedical applications, due to its biocompatibility and biodegradability. The aim of this work was to study the role of dialysis and freezing on structural conformation, thermal properties and morphology of silk fibroin hydrogels. Hydrogels were prepared after 3 and 7 days of dialysis and the effect of freezing was analyzed. For that purpose, a part of the fibroin hydrogels underwent freezing at -20 °C for 24 h, followed by lyophilization and the rest of the hydrogels were kept at 8 °C for 24 h, with further lyophilization. The fibroin hydrogels were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Measurements by XRD and FTIR indicated that silk I and silk II structures were present in the fibroin hydrogels and that the secondary structure of fibroin is transformed mostly to ?-sheet during the gelation process. Thermal analysis indicated that fibroin hydrogels are thermally stable with the degradation peak at around 330-340 °C. SEM micrographs showed porous structures and the fibroin hydrogels subjected to freezing presented a much larger pore size. Results indicate that the dialysis time and freezing did not alter the material crystallinity, conformation or thermal behavior; however, hydrogel microstructure was strongly affected by dialysis time and freezing, showing controlled pores size. This study provides fundamental knowledge on silk fibroin hydrogels preparation and properties and the studied hydrogels are promising to be used in the biomaterial field. PMID:24646905

Ribeiro, Marta; de Moraes, Mariana A; Beppu, Marisa M; Monteiro, Fernando J; Ferraz, Maria P

2014-01-01

90

Processing and characterisation of a novel electropolymerized silk fibroin hydrogel membrane  

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Silk fibroin can be made into various forms of biocompatible medical materials, including hydrogel due to its excellent properties. Here, we report a novel method for the preparation of electropolymerized silk fibroin hydrogel membrane (ESFHM), which is formed on a nanoporous film as a barrier using a homemade device at a higher DC voltage. Regenerated silk fibroin solution in Tris buffer (pH 6.55–7.55) was added into a reservoir with a negative charge, and the silk molecules migrated toward the positive charge at 80VDC, resulting in the formation of the ESFHM on the barrier film. Barrier film with a MWCO of 10?kDa is favourable to the formation of the ESFHM. Semi-transparent ESFHM with a swelling ratio of 1056.4% predominantly consisted of a mixture of ?-sheets and ?-helix crystalline structures. SEM studies revealed that the ESFHM consisted of a 3D mesh structure woven by a chain of silk fibroin nanoparticles with a size of approximately 30 nanometres, similar to a pearl necklace. In vitro studies indicated that the ESFHM was degradable and was sufficient for cell adhesion and growth. Thus, ESFHM is a promising candidate for loading bioactive protein and appropriate cells, as artificial skin or for use in transplantation. PMID:25154713

Wang, Hai-Yan; Zhang, Yu-Qing

2014-01-01

91

Silk fibroin membranes from solvent-crystallized silk fibroin/gelatin blends: Effects of blend and solvent composition  

International Nuclear Information System (INIS)

Protein membranes have been prepared by mixing gelatin (G) with Bombyx mori silk fibroin (SF) and using aqueous methanol (MeOH) to induce SF crystallization. Amorphous blends of these polymers appear quasi-homogeneous, as discerned from visual observation, electron microscopy and Fourier-transform infrared (FTIR) spectroscopy. Upon subsequent exposure to aqueous MeOH, SF undergoes a conformational change from random-coil to ?-sheet. This transformation occurs in pure SF, as well as in each of the G/SF blends, as discerned from FTIR spectroscopy and thermal calorimetry. The influence of MeOH-induced SF crystallization on structure and property development has been measured as functions of blend and solvent composition. By preserving a support scaffold above the G helix-to-coil transition temperature, the formation of crystalline SF networks in G/SF blends can be used to stabilize G-based hydrogels or generate SF membranes for biomaterial, pharmaceutical and gas-separation purposes. The present study not only examines the properties of G/SF blends before and after SF crystallization, but also establishes the foundation for future research into thermally-responsive G/SF bioconjugates

92

Silk fibroin membranes from solvent-crystallized silk fibroin/gelatin blends: Effects of blend and solvent composition  

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Protein membranes have been prepared by mixing gelatin (G) with Bombyx mori silk fibroin (SF) and using aqueous methanol (MeOH) to induce SF crystallization. Amorphous blends of these polymers appear quasi-homogeneous, as discerned from visual observation, electron microscopy and Fourier-transform infrared (FTIR) spectroscopy. Upon subsequent exposure to aqueous MeOH, SF undergoes a conformational change from random-coil to {beta}-sheet. This transformation occurs in pure SF, as well as in each of the G/SF blends, as discerned from FTIR spectroscopy and thermal calorimetry. The influence of MeOH-induced SF crystallization on structure and property development has been measured as functions of blend and solvent composition. By preserving a support scaffold above the G helix-to-coil transition temperature, the formation of crystalline SF networks in G/SF blends can be used to stabilize G-based hydrogels or generate SF membranes for biomaterial, pharmaceutical and gas-separation purposes. The present study not only examines the properties of G/SF blends before and after SF crystallization, but also establishes the foundation for future research into thermally-responsive G/SF bioconjugates.

Gil, Eun S. [Fiber and Polymer Science Program, North Carolina State University, Raleigh, NC 27695 (United States); Frankowski, David J. [Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Hudson, Samuel M. [Fiber and Polymer Science Program, North Carolina State University, Raleigh, NC 27695 (United States); Spontak, Richard J. [Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695 (United States) and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States)]. E-mail: Rich_Spontak@ncsu.edu

2007-04-15

93

In vitro and in vivo release of basic fibroblast growth factor using a silk fibroin scaffold as delivery carrier.  

Science.gov (United States)

Two different solvents were used to prepare two types of silk fibroin scaffolds via the salt-leaching technique, i.e., hexafluoroisopropanol (HFIP) and water. The in vitro release study suggests that the opposite charge between the silk fibroin and basic fibroblast growth factor (bFGF) at physiological pH rendered them to form a complex, and the difference in the solvents used to produce the silk fibroin scaffold did not affect the affinity of silk fibroin to bFGF. However, a higher degradation rate of the aqueous-derived silk fibroin scaffolds provided faster in vitro release kinetics of the bFGF, as compared to the HFIP-derived scaffolds. From the in vivo studies, the use of silk fibroin scaffolds as the carrier matrix enabled the control of the in vivo release of bFGF in a sustained fashion over two weeks, while the majority of the bFGF disappeared within one day after the injection of the bFGF in soluble form. In addition, the in vivo release of bFGF from the silk fibroin scaffolds was not affected by the mode of processing due to their similar degradation behavior in vivo. PMID:20534193

Wongpanit, Panya; Ueda, Hiroki; Tabata, Yasuhiko; Rujiravanit, Ratana

2010-01-01

94

In Vitro Evaluation of Electrospun Silk fibroin Scaffolds for Vascular Cell Growth  

OpenAIRE

Human aortic endothelial (HAEC) and human coronary artery smooth muscle cell (HCASMC) responses on electrospun silk fibroin scaffolds were studied to evaluate potential for vascular tissue engineering. Cell proliferation studies supported the utility of this biomaterial matrix by both HAECs and HCASMCs. Alignment and elongation of HCASMCs on random nonwoven nanofibrous silk scaffolds was observed within 5 days after seeding based on SEM and confocal microscopy. Short cord-like structures form...

Zhang, Xiaohui; Baughman, Cassandra B.; Kaplan, David L.

2008-01-01

95

A dual-layer silk fibroin scaffold for reconstructing the human corneal limbus.  

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Membranes prepared from Bombyx mori silk fibroin have shown potential as a substrate for human limbal epithelial (L-EC) and stromal cell cultivation. Here we present fibroin as a dual-layer construct containing both an epithelium and underlying stroma for corneolimbal reconstruction. We have compared the growth and phenotype of L-EC on non-porous versus porous fibroin membranes. Furthermore, we have compared the growth of limbal mesenchymal stromal cells (L-MSC) in either serum-supplemented medium or the MesenCult-XF(®) culture system within fibroin fibrous mats. The co-culture of L-EC and L-MSC in fibroin dual-layer constructs was also examined. L-EC on porous membranes displayed a squamous monolayer; in contrast, L-EC on non-porous fibroin appeared cuboidal and stratified. Both constructs maintained evidence of corneal phenotype (cytokeratin 3/12) and distribution of ?Np63(+) progenitor cells. L-MSC cultivated within fibroin fibrous mats in serum-supplemented medium contained less than 64% of cells expressing the characteristic MSC phenotype of CD73(+)CD90(+)CD105(+) after two weeks, compared with over 81% in MesenCult-XF(®) medium. Dual-layer fibroin scaffolds consisting of L-EC and L-MSC maintained a similar phenotype as on the separate layers. These results support the feasibility of a 3D engineered limbus constructed from B. mori silk fibroin, and warrant further studies into the potential benefits it offers to corneolimbal tissue regeneration. PMID:22336295

Bray, Laura J; George, Karina A; Hutmacher, Dietmar W; Chirila, Traian V; Harkin, Damien G

2012-05-01

96

Enzymatic degradation behavior and cytocompatibility of silk fibroin-starch-chitosan conjugate membranes  

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The objective of this study was to investigate the influence of silk fibroin and oxidized starch conjugation on the enzymatic degradation behavior and the cytocompatability of chitosan based biomaterials. The tensile stress of conjugate membranes, which was at 50 Megapascal (MPa) for the lowest fibroin and starch composition (10 weight percent (wt.%)), was decreased significantly with the increased content of fibroin and starch. The weight loss of conjugates in {alpha}-amylase was more notable when the starch concentration was the highest at 30 wt.%. The conjugates were resistant to the degradation by protease and lysozyme except for the conjugates with the lowest starch concentration. After 10 days of cell culture, the proliferation of osteoblast-like cells (SaOS-2) was stimulated significantly by higher fibroin compositions and the DNA synthesis on the conjugate with the highest fibroin (30 wt.%) was about two times more compared to the native chitosan. The light microscopy and the image analysis results showed that the cell area and the lengths were decreased significantly with higher fibroin/chitosan ratio. The study proved that the conjugation of fibroin and starch with the chitosan based biomaterials by the use of non-toxic reductive alkylation crosslinking significantly improved the cytocompatibility and modulated the biodegradation, respectively. - Highlights: Black-Right-Pointing-Pointer Silk fibroin, starch and chitosan conjugates were prepared by reductive alkylation. Black-Right-Pointing-Pointer The enzymatic biodegradation and the cytocompatibility of conjugates were tested. Black-Right-Pointing-Pointer The conjugate with 30% starch composition was degraded by {alpha}-amylase significantly. Black-Right-Pointing-Pointer Higher starch composition in conjugates prevented protease and lysozyme degradation. Black-Right-Pointing-Pointer Fibroin incorporation effectively increased the cell proliferation of conjugates.

Baran, Erkan T., E-mail: erkantur@metu.edu.tr; Tuzlakoglu, Kadriye, E-mail: kadriye@dep.uminho.pt; Mano, Joao F., E-mail: jmano@dep.uminho.pt; Reis, Rui L., E-mail: rgreis@dep.uminho.pt

2012-08-01

97

Enzymatic degradation behavior and cytocompatibility of silk fibroin–starch–chitosan conjugate membranes  

International Nuclear Information System (INIS)

The objective of this study was to investigate the influence of silk fibroin and oxidized starch conjugation on the enzymatic degradation behavior and the cytocompatability of chitosan based biomaterials. The tensile stress of conjugate membranes, which was at 50 Megapascal (MPa) for the lowest fibroin and starch composition (10 weight percent (wt.%)), was decreased significantly with the increased content of fibroin and starch. The weight loss of conjugates in ?-amylase was more notable when the starch concentration was the highest at 30 wt.%. The conjugates were resistant to the degradation by protease and lysozyme except for the conjugates with the lowest starch concentration. After 10 days of cell culture, the proliferation of osteoblast-like cells (SaOS-2) was stimulated significantly by higher fibroin compositions and the DNA synthesis on the conjugate with the highest fibroin (30 wt.%) was about two times more compared to the native chitosan. The light microscopy and the image analysis results showed that the cell area and the lengths were decreased significantly with higher fibroin/chitosan ratio. The study proved that the conjugation of fibroin and starch with the chitosan based biomaterials by the use of non-toxic reductive alkylation crosslinking significantly improved the cytocompatibility and modulated the biodegradation, respectively. - Highlights: ? Silk fibroin, starch and chitosan conjugates were prepared by reductive alkylation. ? The enzymatic eductive alkylation. ? The enzymatic biodegradation and the cytocompatibility of conjugates were tested. ? The conjugate with 30% starch composition was degraded by ?-amylase significantly. ? Higher starch composition in conjugates prevented protease and lysozyme degradation. ? Fibroin incorporation effectively increased the cell proliferation of conjugates.

98

Human corneal epithelial equivalents constructed on Bombyx mori silk fibroin membranes.  

Science.gov (United States)

Membranes prepared from a protein, fibroin, isolated from domesticated silkworm (Bombyx mori) silk, support the cultivation of human limbal epithelial (HLE) cells and thus display significant potential as biomaterials for ocular surface reconstruction. We presently extend this promising avenue of research by directly comparing the attachment, morphology and phenotype of primary HLE cell cultures grown on fibroin to that observed on donor amniotic membrane (AM), the current clinical standard substrate for HLE transplantation. Fibroin membranes measuring 6.3 ± 0.5 ?m (mean ± sd) in thickness and permeable to FITC dextran of a molecular weight up to 70 kDa, were used. Attachment of HLE cells to fibroin was similar to that supported by tissue culture plastic but approximately 6-fold less than that observed on AM. Nevertheless, epithelia constructed from HLE on fibroin maintained evidence of corneal phenotype (K3/K12 expression) and displayed a comparable number and distribution of ?Np63(+) progenitor cells to that seen in cultures grown on AM. These results support the suitability of membranes constructed from Bombyx mori silk fibroin as substrata for HLE cultivation and encourage progression to studies of efficacy in preclinical models. PMID:21501866

Bray, Laura J; George, Karina A; Ainscough, S Louise; Hutmacher, Dietmar W; Chirila, Traian V; Harkin, Damien G

2011-08-01

99

Enhanced cell adhesion on silk fibroin via lectin surface modification.  

Science.gov (United States)

Various tissue engineering (TE) approaches are based on silk fibroin (SF) as scaffold material because of its superior mechanical and biological properties compared to other materials. The translation of one-step TE approaches to clinical application has generally failed so far due to the requirement of a prolonged cell seeding step before implantation. Here, we propose that the plant lectin WGA (wheat germ agglutinin), covalently bound to SF, will mediate cell adhesion in a time frame acceptable to be part of a one-step surgical intervention. After the establishment of a modification protocol utilizing carbodiimide chemistry, we examined the attachment of cells, with a special focus on adipose-derived stromal cells (ASC), on WGA-SF compared to pure native SF. After a limited time frame of 20min the attachment of ASCs to WGA-SF showed an increase of about 17-fold, as compared to pure native SF. The lectin-mediated cell adhesion further showed an enhanced resistance to trypsin (as a protease model) and to applied fluid shear stress (mechanical stability). Moreover, we could demonstrate that the adhesion of ASCs on the WGA-SF does not negatively influence proliferation or differentiation potential into the osteogenic lineage. To test for in vitro immune response, the proliferation of peripheral blood mononuclear cells in contact with the WGA-SF was determined, showing no alterations compared to plain SF. All these findings suggest that the WGA modification of SF offers important benefits for translation of SF scaffolds into clinical applications. PMID:24530561

Teuschl, Andreas H; Neutsch, Lukas; Monforte, Xavier; Rünzler, Dominik; van Griensven, Martijn; Gabor, Franz; Redl, Heinz

2014-06-01

100

Synthesis of silk fibroin micro- and submicron spheres using a co-flow capillary device.  

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A custom-made co-flow capillary device is used to synthesize monodisperse silk fibroin micro- and submicron-spheres with diameters tunable over a wide range of sizes. A model drug release is examined and control of degradation kinetics is obtained by changing sphere diameter. PMID:24339048

Mitropoulos, Alexander N; Perotto, Giovanni; Kim, Sunghwan; Marelli, Benedetto; Kaplan, David L; Omenetto, Fiorenzo G

2014-02-01

101

Silk fibroin nanoparticles prepared by electrospray as controlled release carriers of cisplatin.  

Science.gov (United States)

To maintain the anti-tumor activity of cis-dichlorodiamminoplatinum (CDDP) while avoiding its cytotoxicity and negative influence on normal tissue, CDDP-loaded silk fibroin nanoparticles approximately 59 nm in diameter were successfully prepared by electrospray without using organic solvent. CDDP was incorporated into nanoparticles through metal-polymer coordination bond exchange. In vitro release tests showed that the cisplatin in the nanoparticles could be slowly and sustainably released for more than 15 days. In vitro anti-cancer experiments and intracellular Pt content testing indicated that CDDP-loaded silk fibroin nanoparticles were easily internalized by A549 lung cancer cells, transferring CDDP into cancer cells and then triggering their apoptosis. In contrast, the particles were not easily internalized by L929 mouse fibroblast cells and hence showed weaker cell growth inhibition. The CDDP-loaded silk fibroin nanoparticles showed sustained and efficient killing of tumor cells but weaker inhibition of normal cells. In general, this study provides not only a novel method for preparing CDDP-loaded silk fibroin nanoparticles but also a new carrier system for clinical therapeutic drugs against lung cancers and other tumors. PMID:25280693

Qu, Jing; Liu, Yu; Yu, Yanni; Li, Jing; Luo, Jingwan; Li, Mingzhong

2014-11-01

102

Preparation and water absorption of cross-linked chitosan/silk fibroin blend films  

International Nuclear Information System (INIS)

Natural polymer blend films composed of chitosan and silk fibroin were prepared by varying the ratio of chitosan to silk fibroin, with and without glutaraldehyde as a crosslinking agent. The effects of the ratio of chitosan to silk fibroin and crosslinking agent on swelling behavior of the blend films were studied. For the swelling behavior, the blend films exhibited a dramatic change in the degree of swelling when immersed in acidic solutions. The degree of swelling of the films increased as the chitosan content increased; the blend film with 80% chitosan content had the maximum degree of swelling. It appeared that crosslinking had occurred in the blend films which helped the films to retain their three dimensional structure. In addition, FTIR spectra of the films showed evidence of hydrogen bonding interaction between chitosan and silk fibroin. For the effect of salt type, the films were immersed in various types of aqueous salt solutions, viz NaCl, LiCl, CaCl2, AlCl3, and FeCl3. The films immersed in AlCl3 and FeCl3 aqueous solutions gave the maximum degree of swelling. The effects of AlCl3 and FeCl3 concentrations on swelling behavior were also investigated. It was found that the maximum degree of swelling of the films occurred at 1.0 x 10-2 M of AlCl3 and FeCl3 aqueous solutions. (author)

103

Fabrication of Chitosan/Silk Fibroin Composite Nanofibers for Wound-dressing Applications  

OpenAIRE

Chitosan, a naturally occurring polysaccharide with abundant resources, has been extensively exploited for various biomedical applications, typically as wound dressings owing to its unique biocompatibility, good biodegradability and excellent antibacterial properties. In this work, composite nanofibrous membranes of chitosan (CS) and silk fibroin (SF) were successfully fabricated by electrospinning. The morphology of electrospun blend nanofibers was observed by scanning electron microscopy (...

Hong-sheng Wang; Chuang-long He; An-lin Yin; Kui-hua Zhang; Lin-peng Fan; Zeng-xiao Cai; Xiu-mei Mo

2010-01-01

104

Formation of silk fibroin nanoparticles in water-miscible organic solvent and their characterization  

International Nuclear Information System (INIS)

When Silk fibre derived from Bombyx mori, a native biopolymer, was dissolved in highly concentrated neutral salts such as CaCl2, the regenerated liquid silk, a gradually degraded peptide mixture of silk fibroin, could be obtained. The silk fibroin nanoparticles were prepared rapidly from the liquid silk by using water-miscible protonic and polar aprotonic organic solvents. The nanoparticles are insoluble but well dispersed and stable in aqueous solution and are globular particles with a range of 35-125 nm in diameter by means of TEM, SEM, AFM and laser sizer. Over one half of the ?-amino groups exist around the protein nanoparticles by using a trinitrobenzenesulfonic acid (TNBS) method. Raman spectra shows the tyrosine residues on the surface of the globules are more exposed than those on native silk fibers. The crystalline polymorph and conformation transition of the silk nanoparticles from random-coil and ?-helix form (Silk I) into anti-parallel ?-sheet form (Silk II) are investigated in detail by using infrared, fluorescence and Raman spectroscopy, DSC, 13C CP-MAS NMR and electron diffraction. X-ray diffraction of the silk nanoparticles shows that the nanoparticles crystallinity is about four fifths of the native fiber. Our results indicate that the degraded peptide chains of the regenerated silk is gathered homogeneously or heterogeneously to form a looser globular structure in aqueous solution. When introduced into excessive organic solveintroduced into excessive organic solvent, the looser globules of the liquid silk are rapidly dispersed and simultaneously dehydrated internally and externally, resulting in the further chain-chain contact, arrangement of those hydrophobic domains inside the globules and final formation of crystalline silk nanoparticles with ?-sheet configuration. The morphology and size of the nanoparticles are relative to the kinds, properties and even molecular structures of organic solvents, and more significantly to the looser globular substructure of the degraded silk fibroin in aqueous solution. It is possible that the silk protein nanoparticles are potentially useful in biomaterials such as cosmetics, anti-UV skincare products, industrial materials and surface improving materials, especially in enzyme/drug delivery system as vehicle

105

Formation of silk fibroin nanoparticles in water-miscible organic solvent and their characterization  

Energy Technology Data Exchange (ETDEWEB)

When Silk fibre derived from Bombyx mori, a native biopolymer, was dissolved in highly concentrated neutral salts such as CaCl{sub 2}, the regenerated liquid silk, a gradually degraded peptide mixture of silk fibroin, could be obtained. The silk fibroin nanoparticles were prepared rapidly from the liquid silk by using water-miscible protonic and polar aprotonic organic solvents. The nanoparticles are insoluble but well dispersed and stable in aqueous solution and are globular particles with a range of 35-125 nm in diameter by means of TEM, SEM, AFM and laser sizer. Over one half of the {epsilon}-amino groups exist around the protein nanoparticles by using a trinitrobenzenesulfonic acid (TNBS) method. Raman spectra shows the tyrosine residues on the surface of the globules are more exposed than those on native silk fibers. The crystalline polymorph and conformation transition of the silk nanoparticles from random-coil and {alpha}-helix form (Silk I) into anti-parallel {beta}-sheet form (Silk II) are investigated in detail by using infrared, fluorescence and Raman spectroscopy, DSC, {sup 13}C CP-MAS NMR and electron diffraction. X-ray diffraction of the silk nanoparticles shows that the nanoparticles crystallinity is about four fifths of the native fiber. Our results indicate that the degraded peptide chains of the regenerated silk is gathered homogeneously or heterogeneously to form a looser globular structure in aqueous solution. When introduced into excessive organic solvent, the looser globules of the liquid silk are rapidly dispersed and simultaneously dehydrated internally and externally, resulting in the further chain-chain contact, arrangement of those hydrophobic domains inside the globules and final formation of crystalline silk nanoparticles with {beta}-sheet configuration. The morphology and size of the nanoparticles are relative to the kinds, properties and even molecular structures of organic solvents, and more significantly to the looser globular substructure of the degraded silk fibroin in aqueous solution. It is possible that the silk protein nanoparticles are potentially useful in biomaterials such as cosmetics, anti-UV skincare products, industrial materials and surface improving materials, especially in enzyme/drug delivery system as vehicle.

Zhang Yuqing, E-mail: yqzhang@public1.sz.js.cn; Shen Weide; Xiang Ruli [Soochow University, Silk Biotechnol. Lab., School of Life Science (China); Zhuge Lanjian; Gao Weijian; Wang Wenbao [Soochow University, Analytical Center (China)

2007-10-15

106

AFM observation of silk fibroin on mica substrates: morphologies reflecting the secondary structures  

Energy Technology Data Exchange (ETDEWEB)

Bombyx mori silk fibroin was fixed on mica substrates by cast of aqueous fibroin solutions, and the microscopic morphologies of the samples were revealed by means of atomic force microscopy. By adjusting the method used to prepare the solution, we succeeded in forming quasi-2-dimensional thin films in which a network of fibroin molecules developed over the substrate. The film network consisted of fibroin in a random coil structure. The morphology of the network changed after thermal or methanol treatments, which are known to convert the secondary structure of fibroin from the random coil to the {beta}-sheet type. In both of these cases, the network morphology disappeared and characteristic island-like morphologies appeared. On the other hand, temporally evolving gelation occurred in a fibroin solution due to the formation of {beta}-sheet crystals. Such islands were also observable in a specimen prepared by the cast of the gel-containing solution. Based on these results, it was concluded that the islands consist of {beta}-sheet crystals. Of particular interest is the observation that all of the islands had a common thickness value of 1.3 nm. These morphologies are discussed in terms of the secondary structure of fibroin.

Yamada, Kazushi; Tsuboi, Yasuyuki; Itaya, Akira

2003-09-01

107

Silk fibroin/chitosan-hyaluronic acid versus silk fibroin scaffolds for tissue engineering: promoting cell proliferations in vitro.  

Science.gov (United States)

The feasibility of silk fibroin protein (SF) scaffolds for tissue engineering applications to promote cell proliferation has been demonstrated, as well as the ability to mimic natural extra-cellular matrix (ECM), SF/chitosan (CS), a polysaccharide, scaffolds for tissue engineering. However, the response of cells to SF/CS-hyaluronic acid (SF/CS-HA) scaffolds has not been examined, which this study attempts to do and then compares those results with those of SF scaffolds. SF/CS-HA microparticles were fabricated to produce scaffolds in order to examine the proliferations of human dermal fibroblasts (HDF) in the scaffolds. Positive zeta potentials and ATR-FTIR spectra confirmed the co-existence of SF and CS-HA in SF/CS-HA microparticles. HDF proliferated well and migrated into SF/CS-HA scaffolds for around 160 mum in depth, as well as those in SF scaffolds after 7 days of cultivation, as observed using confocal microscopy. Interestingly, HDF grown in SF/CS-HA scaffolds had a markedly higher cell density than that in SF ones. Additionally, MTT assay revealed that the growth rates of HDF in SF/CS-HA scaffolds significantly exceeded (P < 0.01, n = 5) those in scaffolds of SF and SF/CS. The daily glucose consumptions and lactate formations, metabolic parameters, of HDF grown in SF/CS-HA and SF/CS scaffolds were significantly higher (P < 0.01, n = 3) than those in SF ones in most culturing days. Results of this study suggest that SF/CS-HA scaffolds have better cell responses for tissue engineering applications than SF ones. PMID:20135206

Chung, Tze-Wen; Chang, Yu-Lin

2010-04-01

108

Organotypic culture to assess cell adhesion, growth and alignment of different organs on silk fibroin.  

Science.gov (United States)

Glass sheets covered with aligned electrospun silk fibroin (Bombyx mori) were compared to tissue culture-treated Thermanox® coverslips, using an organotypic culture method. Different chick embryo organ behaviours were analysed in terms of circularity, cell growth and cell adhesion after being cultivated in contact with these two materials. The circularity (cell layer shape corresponding to the trend of the biomaterials to induce a specific directionality) depends on the organ used when in contact with silk fibroin. This biomaterial induced higher cell adhesion (kidney) or lower cell adhesion (spine) compared to Thermanox. Cell growth, represented by the cell layer area (mm(2) ), was also drastically reduced (gonad) or increased (blood vessel) on the silk fibroin. Organotypic culture is a rapid, cost effective and relatively simple method to evaluate different parameters, allowing prescreening of morphology and cytocompatibility to select the appropriate applications for new biomaterials. In the present study we compared the morphology of different organotypic cultures on orientated silk and Thermanox as growth supports to rapidly evaluate the benefit of a silk-based biomaterial for tissue engineering. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24889557

Duval, Jean-Luc; Dinis, Tony; Vidal, Guillaume; Vigneron, Pascale; Kaplan, David L; Egles, Christophe

2014-06-01

109

Diverse formulas for spider dragline fibers demonstrated by molecular and mechanical characterization of spitting spider silk.  

Science.gov (United States)

Spider silks have outstanding mechanical properties. Most research has focused on dragline silk proteins (major ampullate spidroins, MaSps) from orb-weaving spiders. Using silk gland expression libraries from the haplogyne spider Scytodes thoracica, we discovered two novel spidroins (S. thoracica fibroin 1 and 2). The amino acid composition of S. thoracica silk glands and dragline fibers suggest that fibroin 1 is the major component of S. thoracica dragline silk. Fibroin 1 is dominated by glycine-alanine motifs, and lacks sequence motifs associated with orb-weaver MaSps. We hypothesize fibroin 2 is a piriform or aciniform silk protein, based on amino acid composition, spigot morphology, and phylogenetic analyses. S. thoracica's dragline silk is less tough than previously reported, but is still comparable to other dragline silks. Our analyses suggest that dragline silk proteins evolved multiple times. This demonstrates that spider dragline silk is more diverse than previously understood, providing alternative high performance silk designs. PMID:25340514

Correa-Garhwal, Sandra M; Garb, Jessica E

2014-12-01

110

Acellular bi-layer silk fibroin scaffolds support tissue regeneration in a rabbit model of onlay urethroplasty.  

Science.gov (United States)

Acellular scaffolds derived from Bombyx mori silk fibroin were investigated for their ability to support functional tissue regeneration in a rabbit model of urethra repair. A bi-layer silk fibroin matrix was fabricated by a solvent-casting/salt leaching process in combination with silk fibroin film casting to generate porous foams buttressed by homogeneous silk fibroin films. Ventral onlay urethroplasty was performed with silk fibroin grafts (Group 1, N = 4) (Width × Length, 1 × 2 cm(2)) in adult male rabbits for 3 m of implantation. Parallel control groups consisted of animals receiving small intestinal submucosa (SIS) implants (Group 2, N = 4) or urethrotomy alone (Group 3, N = 3). Animals in all groups exhibited 100% survival prior to scheduled euthanasia and achieved voluntary voiding following 7 d of initial catheterization. Retrograde urethrography of each implant group at 3 m post-op revealed wide urethral calibers and preservation of organ continuity similar to pre-operative and urethrotomy controls with no evidence of contrast extravasation, strictures, fistulas, or stone formation. Histological (hematoxylin and eosin and Masson's trichrome), immunohistochemical, and histomorphometric analyses demonstrated that both silk fibroin and SIS scaffolds promoted similar extents of smooth muscle and epithelial tissue regeneration throughout the original defect sites with prominent contractile protein (?-smooth muscle actin and SM22?) and cytokeratin expression, respectively. De novo innervation and vascularization were also evident in all regenerated tissues indicated by synaptophysin-positive neuronal cells and vessels lined with CD31 expressing endothelial cells. Following 3 m post-op, minimal acute inflammatory reactions were elicited by silk fibroin scaffolds characterized by the presence of eosinophil granulocytes while SIS matrices promoted chronic inflammatory responses indicated by mobilization of mononuclear cell infiltrates. The results of this study demonstrate that bi-layer silk fibroin scaffolds represent promising biomaterials for onlay urethroplasty, capable of promoting similar degrees of tissue regeneration in comparison to conventional SIS scaffolds, but with reduced immunogenicity. PMID:24632740

Chung, Yeun Goo; Tu, Duong; Franck, Debra; Gil, Eun Seok; Algarrahi, Khalid; Adam, Rosalyn M; Kaplan, David L; Estrada, Carlos R; Mauney, Joshua R

2014-01-01

111

The effect of gamma irradiation on some morphological and quantitative changes of Bombyx mori L. silk gland  

International Nuclear Information System (INIS)

A study to determine the effect of gamma irradiation of silkworm eggs at doses of 1.00; 2.00 and 3.00 on silk gland weight, length and width is performed. It was found that gamma irradiation of eggs in the stage of embryo most intensive growth in length (B2) at doses 2.00 and 3.00 Gy stimulates increasing of silk glands weight in silkworms on the fifth day instar by 12-25 mg, as well as the silk worm width - by 7-33 ?m, which is of significant importance for the synthesis and secretion of silk proteins (fibroin and sericin). A breed specificity was also observed

112

Effect of the sterilization method on the properties of Bombyx mori silk fibroin films  

International Nuclear Information System (INIS)

We have compared the effects of different sterilization techniques on the properties of Bombyx mori silk fibroin thin films with the view to subsequent use for corneal tissue engineering. The transparency, tensile properties, corneal epithelial cell attachment and degradation of the films were used to evaluate the suitability of certain sterilization techniques including gamma-irradiation (in air or nitrogen), steam treatment and immersion in aqueous ethanol. The investigations showed that gamma-irradiation, performed either in air or in a nitrogen atmosphere, did not significantly alter the properties of films. The films sterilized by gamma-irradiation or by immersion in ethanol had a transparency greater than 98% and tensile properties comparable to human cornea and amniotic membrane, the materials of choice in the reconstruction of ocular surface. Although steam-sterilization produced stronger, stiffer films, they were less transparent, and cell attachment was affected by the variable topography of these films. It was concluded that gamma-irradiation should be considered to be the most suitable method for the sterilization of silk fibroin films, however, the treatment with ethanol is also an acceptable method. - Highlights: ? The effects of four methods of sterilization on the properties of silk fibroin films were investigated. ? Steam treatment leads to stiffer films but to lower transparency and variable surface topography. ? Degradation of fibroin is enhany. ? Degradation of fibroin is enhanced in the films that were gamma-irradiated. ? The effects on mechanical properties are explained through changes in both primary and secondary structure of fibroin. ? Gamma-irradiation and immersion in aqueous ethanol are suggested as preferred methods of sterilization.

113

Green synthesis of silk fibroin-silver nanoparticle composites with effective antibacterial and biofilm-disrupting properties.  

Science.gov (United States)

Natural polymer Bombyx mori silk fibroin is used as a biotemplate to produce silver nanoparticles in situ under light (both incandescent light and sunlight) at room temperature. Silk fibroin provides multiple functions in the whole reaction system, serving as the reducing agent of silver, and the dispersing and stabilizing agent of the resulted silver nanoparticles. As the reaction needs not any other chemicals and only uses light as power source, the synthetic route of silver nanoparticles reported here is rather environment-friendly and energy-saving. The silk fibroin-silver nanoparticle composite prepared by this method can be stably stored in a usual environment (room temperature, exposure to light, and so forth) for at least one month. Such a silk fibroin-silver nanoparticle composite shows an effective antibacterial activity against the methicillin-resistant Staphylococcus aureus (S. aureus) and subsequently inhibits the biofilm formation caused by the same bacterium. Moreover, a maturely formed biofilm created by methicillin-resistant S. aureus can be destroyed by the silk fibroin-silver nanoparticle composite, which meets the demand of clinical application. Therefore, the silk fibroin-silver nanoparticle composite prepared by this clean and facile method is expected to be an effective and economical antimicrobial material in biomedical fields. PMID:24171643

Fei, Xiang; Jia, Minghui; Du, Xin; Yang, Yuhong; Zhang, Ren; Shao, Zhengzhong; Zhao, Xia; Chen, Xin

2013-12-01

114

Histochemical and ultrastructural evidence of lipid secretion by the silk gland of the sugarcane borer Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae).  

Science.gov (United States)

The silk gland in Lepidoptera larvae is responsible for the silk production used for shelter or cocoon construction. The secretion of fibroin and sericin by the different silk gland regions are well established. There are few attempts to detect lipid components in the insect silk secretion, although the presence of such element may contribute to the resistance of the shelter to wet environment. This study characterizes the glandular region and detects the presence of lipid components in the secretion of the silk gland of Diatraea saccharalis(Fabricius). The silk gland was submitted to histochemical procedure for lipid detection or conventionally prepared for ultrastructural analyses. Lipid droplets were histochemically detected in both the apical cytoplasm of cell of the anterior region and in the lumen among the microvilli. Ultrastructural analyses of the anterior region showed lipid material, visualized as myelin-like structures within the vesicular Golgi complex and in the apical secretory globules, mixed up with the sericin; similar material was observed into the lumen, adjacent to the microvilli. Lipids were not detected in the cells neither in the lumen of the posterior region. Our results suggest that the silk produced by D. saccharalis has a minor lipid content that is secreted by the anterior region together with the sericin. PMID:18060296

Victoriano, Eliane; Pinheiro, Daniela O; Gregório, Elisa A

2007-01-01

115

Silk fibroin microparticles as carriers for delivery of human recombinant BMPs : physical characterization and drug release  

OpenAIRE

Bone morphogenetic proteins (BMPs) are cytokines with strong ability to promote new bone formation. Herein, we report the use of silk fibroin microparticles as carriers for the delivery of BMP-2, BMP-9 or BMP-14. BMP-containing fibroin microparticles were prepared by a mild methodology using dropwise addition of ethanol, exhibiting mean diameters of 2.7 ± 0.3 ?m. Encapsulation efficiencies varied between 67.9 ± 6.1 % and 97.7 ± 2.0 % depending on the type and the amount of ...

Bessa, Paulo C.; Balmayor, Elizabeth Rosado; Azevedo, Helena S.; Nu?rnberger, Sylvia; Casal, Margarida; Griensven, M.; Reis, R. L.; Redl, Heinz

2010-01-01

116

Preparation and characterization of regenerated Bombyx mori silk fibroin fiber with high strength  

Directory of Open Access Journals (Sweden)

Full Text Available Regenerated Bombyx mori silk fibers were spun from hexafluoro-iso- propanol solution of silk fibroin sponge in methanol used as a coagulant solvent and then elongated in water. The stress-strain curves of the regenerated fibers changed dramatically depending on the draw ratio and the structure was studied by 13C CP/MAS NMR and X-ray diffraction methods. The patterns of 13C CP/MAS NMR spectra of two regenerated fibers with different draw ratios (1× and 3× and native silk fiber are all ?-sheet structure although the fraction of random coil/distorted ?-turn decreases in the order of 1×, 3× and native fiber gradually. On the other hand, azimuthal scans of their X-ray fiber patterns changed remarkably with increasing the draw ratio. This indicates that long-range orientation of the fibroin chain changes remarkably during the drawing process, but the short-range local structure does not change significantly. Regenerated silk fiber with a draw ratio of 3× is a fiber with high strength which is comparable with that of natural silk fiber. The regenerated fiber is also more degradable than natural silk fiber in enzyme solution in vitro.

2008-12-01

117

Effect of the sterilization method on the properties of Bombyx mori silk fibroin films  

Energy Technology Data Exchange (ETDEWEB)

We have compared the effects of different sterilization techniques on the properties of Bombyx mori silk fibroin thin films with the view to subsequent use for corneal tissue engineering. The transparency, tensile properties, corneal epithelial cell attachment and degradation of the films were used to evaluate the suitability of certain sterilization techniques including gamma-irradiation (in air or nitrogen), steam treatment and immersion in aqueous ethanol. The investigations showed that gamma-irradiation, performed either in air or in a nitrogen atmosphere, did not significantly alter the properties of films. The films sterilized by gamma-irradiation or by immersion in ethanol had a transparency greater than 98% and tensile properties comparable to human cornea and amniotic membrane, the materials of choice in the reconstruction of ocular surface. Although steam-sterilization produced stronger, stiffer films, they were less transparent, and cell attachment was affected by the variable topography of these films. It was concluded that gamma-irradiation should be considered to be the most suitable method for the sterilization of silk fibroin films, however, the treatment with ethanol is also an acceptable method. - Highlights: Black-Right-Pointing-Pointer The effects of four methods of sterilization on the properties of silk fibroin films were investigated. Black-Right-Pointing-Pointer Steam treatment leads to stiffer films but to lower transparency and variable surface topography. Black-Right-Pointing-Pointer Degradation of fibroin is enhanced in the films that were gamma-irradiated. Black-Right-Pointing-Pointer The effects on mechanical properties are explained through changes in both primary and secondary structure of fibroin. Black-Right-Pointing-Pointer Gamma-irradiation and immersion in aqueous ethanol are suggested as preferred methods of sterilization.

George, Karina A. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland 4059 (Australia); Shadforth, Audra M.A. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Chirila, Traian V., E-mail: traian.chirila@qei.org.au [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Australian Institute of Bioengineering and Nanotechnology, University of Queensland, St Lucia, 4072 (Australia); Faculty of Health Sciences, University of Queensland, Herston, Queensland 4006 (Australia); Faculty of Science and Engineering, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Laurent, Matthieu J. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Ecole Superieure d' Ingenieurs de Luminy (ESIL), Universite de la Mediterranee Aix-Marseille II, Luminy case 925 13288, Marseille, Cedex 09 (France); Stephenson, Sally-Anne [Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland 4059 (Australia); Faculty of Health, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Edwards, Grant A. [Australian Institute of Bioengineering and Nanotechnology, University of Queensland, St Lucia, 4072 (Australia); Madden, Peter W. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Faculty of Health Sciences, University of Queensland, Herston, Queensland 4006 (Australia); and others

2013-03-01

118

Natural fibroin genes purified without using cloning procedures from fibroin-producing and -nonproducing tissues reveal indistinguishable structure and function.  

OpenAIRE

Natural fibroin genes were purified from total DNA extracted from the fibroin-producer cells (posterior silk gland) and -nonproducer cells (middle silk gland or pupa) by two cycles of CsCl/actinomycin D centrifugation followed by sucrose density gradient centrifugation. Purity of the final samples was greater than 14%. DNA sequences of these natural genes between positions -171 and +104 were identical and showed no sign of base modification as assayed by the method of Maxam and Gilbert. The d...

Tsujimoto, Y.; Suzuki, Y.

1984-01-01

119

Drug loading and release on tumor cells using silk fibroin-albumin nanoparticles as carriers  

Science.gov (United States)

Polymeric and biodegradable nanoparticles are frequently used in drug delivery systems. In this study silk fibroin-albumin blended nanoparticles were prepared using the desolvation method without any surfactant. These nanoparticles are easily internalized by the cells, reside within perinuclear spaces and act as carriers for delivery of the model drug methotrexate. Methotrexate loaded nanoparticles have better encapsulation efficiency, drug loading ability and less toxicity. The in vitro release behavior of methotrexate from the nanoparticles suggests that about 85% of the drug gets released after 12 days. The encapsulation and loading of a drug would depend on factors such as size, charge and hydrophobicity, which affect drug release. MTT assay and conjugation of particles with FITC demonstrate that the silk fibroin-albumin nanoparticles do not affect the viability and biocompatibility of cells. This blended nanoparticle, therefore, could be a promising nanocarrier for the delivery of drugs and other bioactive molecules.

Subia, B.; Kundu, S. C.

2013-01-01

120

The Micropillar Structure on Silk Fibroin Film Influence Intercellular Connection Mediated by Nanotubular Structures  

Directory of Open Access Journals (Sweden)

Full Text Available Tunneling nanotubes are important membrane channels for cell-to-cell communication. In this study, we investigated the effect of the microenvironment on nanotubular structures by preparing a three-dimensional silk fibroin micropillar structure. In previous reports, tunneling nanotubes were described as stretched membrane channels between interconnected cells at their nearest distance. They hover freely in the cell culture medium and do not contact with the substratum. Interestingly, the micropillars could provide supporting points for nanotubular connection on silk fibroin films, where nanotubular structure formed a stable anchor at contact points. Consequently, the extension direction of nanotubular structure was affected by the micropillar topography. This result suggests that the hovering tunneling nanotubes in the culture medium will come into contact with the raised roadblock on the substrates during long-distance extension. These findings imply that the surface microtopography of biomaterials have an important influence on cell communication mediated by tunneling nanotubes.

Renchuan You

2014-06-01

121

Low-threshold blue lasing from silk fibroin thin films  

Science.gov (United States)

Silk is a natural biocompatible material that can be integrated in a variety of photonic systems and optoelectronic devices. The silk replication of patterned substrates with features down to tens of nanometers is exploited to realize highly transparent, mechanically stable, and free-standing structures with optical wavelength size. We demonstrate organic lasing from a blue-emitting stilbene-doped silk film spin-coated onto a one-dimensional distributed feedback grating (DFB). The lasing threshold is lower than that of organic DFB lasers based on the same active dye. These findings pave the way to the development of an optically active biocompatible technological platform based on silk.

Toffanin, Stefano; Kim, Sunghwan; Cavallini, Susanna; Natali, Marco; Benfenati, Valentina; Amsden, Jason J.; Kaplan, David L.; Zamboni, Roberto; Muccini, Michele; Omenetto, Fiorenzo G.

2012-08-01

122

Fabrication of Antibacterial Wound Dressings from Silk Fibroin and Silver Nano particles  

International Nuclear Information System (INIS)

Full text: Patients with burn wounds that cover large body surface area are susceptible to infection which can lead to fatality. Wound dressings or skin grafts are needed to cover the wound during the regeneration of new skin tissue. The aim of this research is to fabricate antibacterial wound dressings from silk fibroin derived from the natural silk cocoon and silver nanoparticles (AgNPs) prepared by gamma irradiation. Fibroin mats composed of nonwoven fibers with diameter of 670± 11.5 nm were fabricated by electro spinning. Using gamma irradiation, the starting silver nitrate solution was reduced to colloidal AgNPs. The fibroin mats were coated with AgNPs at various AgNP concentration and then evaluated for their antibacterial property by disc diffusion test. The concentration of colloidal AgNP solution ? 1 mM was found to be as sufficient in inhibiting the growth of Pseudomonas aeruginosa and Staphylococcus aureus as commercial wound dressings embedded with silver ions. These results demonstrate that electro spun fibroin mats coated with AgNPs exhibite antibacterial property and can be further developed for the treatment of burn wounds

123

Preparation and water absorption of cross-linked chitosan/silk fibroin blend films  

Energy Technology Data Exchange (ETDEWEB)

Natural polymer blend films composed of chitosan and silk fibroin were prepared by varying the ratio of chitosan to silk fibroin, with and without glutaraldehyde as a crosslinking agent. The effects of the ratio of chitosan to silk fibroin and crosslinking agent on swelling behavior of the blend films were studied. For the swelling behavior, the blend films exhibited a dramatic change in the degree of swelling when immersed in acidic solutions. The degree of swelling of the films increased as the chitosan content increased; the blend film with 80% chitosan content had the maximum degree of swelling. It appeared that crosslinking had occurred in the blend films which helped the films to retain their three dimensional structure. In addition, FTIR spectra of the films showed evidence of hydrogen bonding interaction between chitosan and silk fibroin. For the effect of salt type, the films were immersed in various types of aqueous salt solutions, viz NaCl, LiCl, CaCl{sub 2}, AlCl{sub 3}, and FeCl{sub 3}. The films immersed in AlCl{sub 3} and FeCl{sub 3} aqueous solutions gave the maximum degree of swelling. The effects of AlCl{sub 3} and FeCl{sub 3} concentrations on swelling behavior were also investigated. It was found that the maximum degree of swelling of the films occurred at 1.0 x 10{sup -2} M of AlCl{sub 3} and FeCl{sub 3} aqueous solutions. (author)

Suesat, Jantip; Rujiravanit, Ratana [Chulalongkorn University, The Petroleum and Petrochemical College, Bangkok (Thailand); Jamieson, Alexander M. [Case Western Reserve Univ., Department of Macromolecular Science, Cleveland (United States); Tokura, Seiichi [Kansai Univ., Faculty of Engineering, Osaka (Japan)

2001-03-01

124

Effect of silk fibroin nanofibers containing silver sulfadiazine on wound healing  

OpenAIRE

Lim Jeong,1 Min Hee Kim,1 Ju-Young Jung,2 Byung Moo Min,3 Won Ho Park1 1Department of Advanced Organic Materials and Textile System Engineering, 2College of Veterinary Medicine, Chungnam National University, Daejeon, 3Department of Oral Biochemistry, School of Dentistry, Seoul National University, Seoul, South Korea Background: One of the promising applications of silk fibroin (SF) in biomedical engineering is its use as a scaffolding material for skin regeneration. The purpose of this study...

Jeong L; Mh, Kim; Jy, Jung; Bm, Min; Wh, Park

2014-01-01

125

Improvement of early cell adhesion on Thai silk fibroin surface by low energy plasma.  

Science.gov (United States)

Low energy plasma has been introduced to treat the surface of Thai silk fibroin which should be enhanced for cell adhesion due to its native hydrophobic surface. Plasma surface treatment could introduce desirable hydrophilic functionalities on the surface without using any chemicals. In this work, nitrogen glow discharge plasma was generated by a low energy AC50Hz power supply system. The plasma operating conditions were optimized to reach the highest nitrogen active species by using optical emission spectroscopy. X-ray photoelectron spectroscopy (XPS) revealed that amine, hydroxyl, ether, and carboxyl groups were induced on Thai silk fibroin surface after plasma treatment. The results on Fourier transform infrared attenuated total reflection (FTIR-ATR) spectroscopy confirmed that the plasma treated effects were only on the outermost layer since there was no change in the bulk chemistry. The surface topography was insignificantly changed from the detection with atomic force microscopy (AFM). The plasma-treated effects were the improved surface wettability and cell adhesion. After a 90-s treatment, the water contact angle was at 20°, while the untreated surface was at 70°. The early cell adhesion of L929 mouse fibroblast was accelerated. L929 cells only took 3h to reach 100% cell adhesion on 90 s N2 plasma-treated surface, while there was less than 50% cell adhesion on the untreated Thai silk fibroin surface after 6h of culture. The cell adhesion results were in agreement with the cytoskeleton development. L929 F-actin was more evident on 90 s N2 plasma-treated surface than others. It could be concluded that a lower energy AC50Hz plasma system enhanced early L929 mouse fibroblast adhesion on Thai silk fibroin surface without any significant change in surface topography and bulk chemistry. PMID:23893032

Amornsudthiwat, Phakdee; Mongkolnavin, Rattachat; Kanokpanont, Sorada; Panpranot, Joongjai; Wong, Chiow San; Damrongsakkul, Siriporn

2013-11-01

126

Effect of Methanol Treatment on Regenerated Silk Fibroin Microparticles Prepared by the Emulsification-Diffusion Technique  

OpenAIRE

Silk Fibroin (SF) microparticles containing hollow structure were prepared by a water-in-oil emulsion solvent diffusion method without any surfactants. Aqueous SF solution and ethyl acetate were used as water and oil phases, respectively. Influences of SF concentration and post methanol treatment on microparticle characteristics were investigated. All microparticles contained open hollow structures. Microparticle sizes increased with the SF concentration. Conformation of SF microparticles det...

Yodthong Baimark; Prasong Srihanam

2009-01-01

127

Fabrication and Intermolecular Interactions of Silk Fibroin/Hydroxybutyl Chitosan Blended Nanofibers  

OpenAIRE

The native extracellular matrix (ECM) is composed of a cross-linked porous network of multifibril collagens and glycosaminoglycans. Nanofibrous scaffolds of silk fibroin (SF) and hydroxybutyl chitosan (HBC) blends were fabricated using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and trifluoroacetic acid (TFA) as solvents to biomimic the native ECM via electrospinning. Scanning electronic microscope (SEM) showed that relatively uniform nanofibers could be obtained when 12% SF was blended with 6% ...

Xiu-Mei Mo; Kui-Hua Zhang; Qiao-Zhen Yu

2011-01-01

128

Fabrication of Chitosan/Silk Fibroin Composite Nanofibers for Wound-dressing Applications  

Directory of Open Access Journals (Sweden)

Full Text Available Chitosan, a naturally occurring polysaccharide with abundant resources, has been extensively exploited for various biomedical applications, typically as wound dressings owing to its unique biocompatibility, good biodegradability and excellent antibacterial properties. In this work, composite nanofibrous membranes of chitosan (CS and silk fibroin (SF were successfully fabricated by electrospinning. The morphology of electrospun blend nanofibers was observed by scanning electron microscopy (SEM and the fiber diameters decreased with the increasing percentage of chitosan. Further, the mechanical test illustrated that the addition of silk fibroin enhanced the mechanical properties of CS/SF nanofibers. The antibacterial activities against Escherichia coli (Gram negative and Staphylococcus aureus (Gram positive were evaluated by the turbidity measurement method; and results suggest that the antibacterial effect of composite nanofibers varied on the type of bacteria. Furthermore, the biocompatibility of murine fibroblast on as-prepared nanofibrous membranes was investigated by hematoxylin and eosin (H&E staining and MTT assays in vitro, and the membranes were found to promote the cell attachment and proliferation. These results suggest that as-prepared chitosan/silk fibroin (CS/SF composite nanofibrous membranes could be a promising candidate for wound healing applications.

Hong-sheng Wang

2010-09-01

129

Optimization of nanofibrous silk fibroin scaffolds as a delivery system for bone marrow adherent cells.  

Science.gov (United States)

Electrospun silk fibroin nanofibrous scaffolds (ESFNSs) were successfully prepared by electrospinning of various Bombyx mori silk fibroin concentrations (10, 12 and 14% in formic acid). After characterizing the purified silk fibroin, the morphology, porosity, fibers' diameter and uniformity of the prepared scaffolds were examined in detail. In addition, biological responses such as effects on bone marrow cell viability, cytotoxicity and cell adhesion were evaluated in vitro. Biocompatibility and bioactivity properties of the ESFNSs were evaluated in vitro and in vivo by cell culturing and subcutaneous implantation in rat models for 7 and 28 days, respectively. According to the obtained results, no beaded fibers were seen in any of the prepared scaffolds, while ESFNS-10% provided more uniformity and porosity with nano-scaled fibers (90 ± 0.021 nm). Furthermore, the scaffolds also showed good cell adhesion and spreading (68.7 ± 11.8 and 7.6 ± 3.3 total length and width, respectively) with no detectable effect on cell viability and cytotoxicity. The in vivo biocompatibility evaluation indicated that the scaffolds did not stimulate detectable cellular inflammatory response (lymphocytes), and increased the total cell number (cellularity) in the implantation area. Furthermore, the results suggest the potential use of the prepared ESFNS-10%-bone marrow cells constructs in direct implantation for tissue engineering applications. This article is protected by copyright. All rights reserved. PMID:25471678

Gholipourmalekabadi, Mazaher; Mozafari, Masoud; Bandehpour, Mojgan; Salehi, Mohammad; Sameni, Marzieh; Caicedo, Hector Hugo; Mehdipour, Ahmad; Ghasemi, Hatef; Samadikuchaksaraei, Ali; Ghanbarian, Hossein

2014-12-01

130

Facile fabrication of the porous three-dimensional regenerated silk fibroin scaffolds  

Energy Technology Data Exchange (ETDEWEB)

In the present work, we report a new facile method to fabricate porous three-dimensional regenerated silk fibroin (RSF) scaffolds through n-butanol- and freezing-induced conformation transition and phase separation. The effects of RSF concentration, freezing temperature and n-butanol addition on the microstructure, the secondary structures of silk fibroin and apparent mechanical properties of the RSF scaffolds were investigated by SEM, {sup 13}C CP-MAS NMR spectra and mechanical testing, respectively. By adjusting the RSF concentration and n-butanol addition, the pore size of the scaffold could be controlled in the range from of 10 ?m to 350 ?m with 84%–98% of porosity. The tensile strength of the wet scaffold reached the maximum of 755.2 ± 33.6 kPa when the concentration of RSF solution was increased to 15% w/w. Moreover, post-treatment with ethanol further induced conformation transition of RSF from random coil or helix to ?-sheet. The porous scaffolds prepared by this facile and energy-saving method with good biocompatibility will have great potential for application in tissue engineering. Highlights: • A new facile and energy-saving method to fabricate porous silk fibroin scaffolds; • Freeze-drying step (a typical high energy consuming process) is unnecessary; • Morphology and mechanical properties of scaffolds were easily controlled; • Ethanol post-treatment can be used to tune the degradation behavior.

Cao, Zhengbing; Wen, Jianchuan [State Key Laboratory of Molecular Engineering of Polymers, Advanced Materials Laboratory, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Yao, Jinrong, E-mail: yaoyaojr@fudan.edu.cn [State Key Laboratory of Molecular Engineering of Polymers, Advanced Materials Laboratory, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Chen, Xin [State Key Laboratory of Molecular Engineering of Polymers, Advanced Materials Laboratory, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Ni, Yusu [Otology and Skull Base Surgery Department, Eye and ENT Hospital of Fudan University, Shanghai 200031 (China); Shao, Zhengzhong [State Key Laboratory of Molecular Engineering of Polymers, Advanced Materials Laboratory, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China)

2013-08-01

131

Facile fabrication of the porous three-dimensional regenerated silk fibroin scaffolds  

International Nuclear Information System (INIS)

In the present work, we report a new facile method to fabricate porous three-dimensional regenerated silk fibroin (RSF) scaffolds through n-butanol- and freezing-induced conformation transition and phase separation. The effects of RSF concentration, freezing temperature and n-butanol addition on the microstructure, the secondary structures of silk fibroin and apparent mechanical properties of the RSF scaffolds were investigated by SEM, 13C CP-MAS NMR spectra and mechanical testing, respectively. By adjusting the RSF concentration and n-butanol addition, the pore size of the scaffold could be controlled in the range from of 10 ?m to 350 ?m with 84%–98% of porosity. The tensile strength of the wet scaffold reached the maximum of 755.2 ± 33.6 kPa when the concentration of RSF solution was increased to 15% w/w. Moreover, post-treatment with ethanol further induced conformation transition of RSF from random coil or helix to ?-sheet. The porous scaffolds prepared by this facile and energy-saving method with good biocompatibility will have great potential for application in tissue engineering. Highlights: • A new facile and energy-saving method to fabricate porous silk fibroin scaffolds; • Freeze-drying step (a typical high energy consuming process) is unnecessary; • Morphology and mechanical properties of scaffolds were easily controlled; • Ethanol post-treatment can be used to tune the degradation behavior

132

Influence of Layer-by-Layer Polyelectrolyte Deposition and EDC/NHS Activated Heparin Immobilization onto Silk Fibroin Fabric  

Directory of Open Access Journals (Sweden)

Full Text Available To enhance the hemocompatibility of silk fibroin fabric as biomedical material, polyelectrolytes architectures have been assembled through the layer-by-layer (LbL technique on silk fibroin fabric (SFF. In particular, 1.5 and 2.5 bilayer of oppositely charged polyelectrolytes were assembled onto SFF using poly(allylamine hydrochloride (PAH as polycationic polymer and poly(acrylic acid (PAA as polyanionic polymer with PAH topmost. Low molecular weight heparin (LMWH activated with 1-ethyl-3-(dimethylaminopropyl carbodiimide hydrochloride (EDC and N-hydroxysuccinimide (NHS was then immobilized on its surface. Alcian Blue staining, toluidine blue assay and X-ray photoelectron spectroscopy (XPS confirmed the presence of heparin on modified SFF surfaces. The surface morphology of the modified silk fibroin fabric surfaces was characterized by scanning electron microscopy (SEM and atomic force microscopy (AFM, and obtained increased roughness. Negligible hemolytic effect and a higher concentration of free hemoglobin by a kinetic clotting time test ensured the improved biological performance of the modified fibroin fabric. Overall, the deposition of 2.5 bilayer was found effective in terms of biological and surface properties of the modified fibroin fabric compared to 1.5 bilayer self-assembly technique. Therefore, this novel approach to surface modification may demonstrate long term patency in future in vivo animal trials of small diameter silk fibroin vascular grafts.

M. Fazley Elahi

2014-04-01

133

Intrinsic fluorescence changes associated with the conformational state of silk fibroin in biomaterial matrices  

Science.gov (United States)

Silk fibroin is emerging as an important biomaterial for tissue engineering applications. The ability to monitor non-invasively the structural conformation of silk matrices prior to and following cell seeding could provide important insights with regards to matrix remodeling and cell-matrix interactions that are critical for the functional development of silk-based engineered tissues. Thus, we examined the potential of intrinsic fluorescence as a tool for assessing the structural conformation of silk proteins. Specifically, we characterized the intrinsic fluorescence spectra of silk in solution, gel and scaffold configurations for excitation in the 250 to 335 nm range and emission from 265 to 600 nm. We have identified spectral components that are attributed to tyrosine, tryptophan and crosslinks based on their excitation-emission profiles. We have discovered significant spectral shifts in the emission profiles and relative contributions of these components among the silk solution, gel and scaffold samples that represent enhancements in the levels of crosslinking, hydrophobic and intermolecular interactions that are consistent with an increase in the levels of ß-sheet formation and stacking. This information can be easily utilized for the development of simple, non-invasive, ratiometric methods to assess and monitor the structural conformation of silk in engineered tissues.

Georgakoudi, Irene; Tsai, Irene; Greiner, Cherry; Wong, Cheryl; Defelice, Jordy; Kaplan, David

2007-02-01

134

In vitro and in vivo research on using Antheraea pernyi silk fibroin as tissue engineering tendon scaffolds  

Energy Technology Data Exchange (ETDEWEB)

In this paper, the feasibility of using Antheraea pernyi silk fibroin as tissue engineering tendon scaffold was investigated in vitro and in vivo, respectively, utilizing tenocytes and animal model. The animal model used here was an adult New Zealand White rabbit with a 15-mm gap defect in both sides of the Achilles tendon. The Achilles tendon defects in one side of hind legs were repaired using the braided A. pernyi silk fibroin scaffold in experimental group (n = 24), while the other side left untreated as negative group (n = 24). The recovery of the defect tendons were evaluated postoperatively at the 2nd, 6th, 12th, and 16th week using macroscopic, histological, immunohistochemical, scanning electron micrograph and biomechanical test techniques. In vitro results examined by scanning electron micrograph showed that A. pernyi silk fibroin promote the adhesion and propagation of the tenocytes. In vivo, at 16 weeks after implantation, morphological results showed that neo-tendons were formed, and bundles of collagen fibers in the neo-tendons were uniform and well oriented. Immunohistochemical results showed that collagen type in the regenerated tendons was predominantly type I. The maximum load of regenerated tendon at 16 weeks reached 55.46% of the normal tendon values. Preliminary, we concluded that A. pernyi silk fibroin promoted the recovery of Achilles tendon defect of rabbit and the application of A. pernyi silk fibroin as tissue engineering tendon scaffold is feasible.

Fang Qian [College of Life Sciences, Fujian Normal University, Fuzhou, Fujian350108 (China); Chen Denglong [College of Chemistry and Materials Sciences, Fujian Normal University, Fuzhou, Fujian350108 (China); Yang Zhiming [Division of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041 (China); Li Min, E-mail: mli@fjnu.edu.cn [College of Life Sciences, Fujian Normal University, Fuzhou, Fujian350108 (China)

2009-06-01

135

In vitro and in vivo research on using Antheraea pernyi silk fibroin as tissue engineering tendon scaffolds  

International Nuclear Information System (INIS)

In this paper, the feasibility of using Antheraea pernyi silk fibroin as tissue engineering tendon scaffold was investigated in vitro and in vivo, respectively, utilizing tenocytes and animal model. The animal model used here was an adult New Zealand White rabbit with a 15-mm gap defect in both sides of the Achilles tendon. The Achilles tendon defects in one side of hind legs were repaired using the braided A. pernyi silk fibroin scaffold in experimental group (n = 24), while the other side left untreated as negative group (n = 24). The recovery of the defect tendons were evaluated postoperatively at the 2nd, 6th, 12th, and 16th week using macroscopic, histological, immunohistochemical, scanning electron micrograph and biomechanical test techniques. In vitro results examined by scanning electron micrograph showed that A. pernyi silk fibroin promote the adhesion and propagation of the tenocytes. In vivo, at 16 weeks after implantation, morphological results showed that neo-tendons were formed, and bundles of collagen fibers in the neo-tendons were uniform and well oriented. Immunohistochemical results showed that collagen type in the regenerated tendons was predominantly type I. The maximum load of regenerated tendon at 16 weeks reached 55.46% of the normal tendon values. Preliminary, we concluded that A. pernyi silk fibroin promoted the recovery of Achilles tendon defect of rabbit and the application of A. pernyi silk fibroin as tissue engineering tendon scaffold is fas tissue engineering tendon scaffold is feasible.

136

Microphase Separation Controlled Beta Sheet Crystallization Kinetics in Silk Fibroin Protein.  

Science.gov (United States)

We investigate the mechanism of isothermal crystallization kinetics of beta-sheet crystals in silk multiblock fibrous proteins. The Avrami analysis kinetic theory, for studies of synthetic polymer crystal growth, is for the first time extended to investigate protein self-assembly in beta-sheet rich Bombyx mori silk fibroin samples, using time-resolved Fourier transform infrared spectroscopy, differential scanning calorimetry and synchrotron real-time wide-angle X-ray scattering. Results indicate formation of beta sheet crystals in silk proteins is different from the 3-D spherulitic crystal growth found in synthetic homopolymers. Observations by scanning electron microscopy support the view that the protein structures vary during the different stages of crystal growth, and show a microphase separation pattern after chymotrypsin enzyme biodegradation. We present a model to explain the crystallization of the multiblock silk fibroin protein, by analogy to synthetic block copolymers. This model could be widely applicable in other proteins with multiblock (i.e., crystallizable and non-crystallizable) domains.

Hu, Xiao; Lu, Qiang; Kaplan, David; Cebe, Peggy

2009-03-01

137

Rheology of reconstituted silk fibroin protein gels: the epitome of extreme mechanics.  

Science.gov (United States)

In nature, silk fibroin proteins assemble into hierarchical structures with dramatic mechanical properties. With the hope of creating new classes of on demand silk-based biomaterials, Bombyx mori silk is reconstituted back into stable aqueous solutions that can be reassembled into functionalized materials; one strategy for reassembly is electrogelation. Electrogels (e-gels) are particularly versatile and can be produced using electrolysis with small DC electric fields. We characterize the linear and nonlinear rheological behavior of e-gels to provide fundamental insights into these distinct protein-based materials. We observe that e-gels form robust biopolymer networks that exhibit distinctive strain hardening and are recoverable from strains as large as ? = 27, i.e. 2700%. We propose a simple microscopic model that is consistent with local restructuring of single proteins within the e-gel network. PMID:25489795

Tabatabai, A Pasha; Kaplan, David L; Blair, Daniel L

2015-01-28

138

Multifunctional adhesive silk fibroin with blending of RGD-bioconjugated mussel adhesive protein.  

Science.gov (United States)

Silk has recently been exploited in various fields due to its superior mechanical properties. However, this material's lack of biological functions and relatively poor biodegradation have hindered its wide use in applications related to cells and tissues. Here, we improved the overall characteristics of silkworm silk fibroin (SF) by introduction of RGD peptide-fused recombinant mussel adhesive protein (MAP-RGD). Simple blending of MAP-RGD provided not only bulk-scale adhesive ability but also microscale adhesiveness to cells and various biomolecules. MAP-RGD-blended SF fibers supported enhanced adhesion, proliferation, and spreading of mammalian cells as well as the efficient attachment of biomolecules, including carbohydrate and protein. In addition, the hydrophilicity, swelling, and biodegradability of the MAP-RGD-blended SF material were improved without notable hampering of the original mechanical properties of SF. Therefore, the adhesive silk fibrous scaffold could be successfully used in diverse biomedical engineering applications. PMID:24601579

Yang, Yun Jung; Kwon, Yunkyeoung; Choi, Bong-Hyuk; Jung, Dooyup; Seo, Jeong Hyun; Lee, Ki Hoon; Cha, Hyung Joon

2014-04-14

139

Tubuliform silk protein: A protein with unique molecular characteristics and mechanical properties in the spider silk fibroin family  

Science.gov (United States)

Orb-web weavers can produce up to six different types of silk and a glue for various functions. Tubuliform silk is unique among them due to its distinct amino acid composition, specific time of production, and atypical mechanical properties. To study the protein composing this silk, tubuliform gland cDNA libraries were constructed from three orb-weaving spiders Argiope aurantia, Araneus gemmoides, and Nephila clavipes. Amino acid composition comparison between the predicted tubuliform silk protein sequence (TuSp1) and the corresponding gland protein confirms that TuSp1 is the major component in tubuliform gland in three spiders. Sequence analysis suggests that TuSp1 shares no significant similarity with its paralogues, while it has conserved sequence motifs with the most primitive spider, Euagrus chisoseus silk protein. The presence of large side-chain amino acids in TuSp1 sequence is consistent with the frustrated ?-sheet crystalline structure of tubuliform silk observed in transmission electron microscopy. Repeat unit comparison within species as well as among three spiders exhibits high sequence conservation. Parsimony analysis based on carboxy terminal sequence shows that Argiope and Araneus are more closely related than either is to Nephila which is consistent with phylogenetic analysis based on morphological evidence.

Tian, M.; Lewis, R. V.

2006-02-01

140

Silk fibroin microparticles as carriers for delivery of human recombinant BMPs. Physical characterization and drug release.  

Science.gov (United States)

Bone morphogenetic proteins (BMPs) are cytokines with strong ability to promote new bone formation. Herein, we report the use of silk fibroin microparticles as carriers for the delivery of BMP-2, BMP-9 or BMP-14. BMP-containing fibroin microparticles were prepared by a mild methodology using dropwise addition of ethanol, exhibiting mean diameters of 2.7 +/- 0.3 microm. Encapsulation efficiencies varied between 67.9 +/- 6.1 % and 97.7 +/- 2.0 % depending on the type and the amount of BMP loaded. Release kinetics showed that BMP-2, BMP-9 and BMP-14 were released in two phases profile, with a burst release in the first two days followed by a slower release, for a period of 14 days. The release data were best explained by Korsmeyer's model and the Fickian model of drug diffusion. Silk fibroin microparticles can offer a promising approach for the sustained delivery of different BMPs in tissue engineering applications. PMID:20058243

Bessa, P C; Balmayor, E R; Azevedo, H S; Nürnberger, S; Casal, M; van Griensven, M; Reis, R L; Redl, H

2010-07-01

141

Factors Controlling the Deposition of Silk Fibroin Nanofibrils during Layer-by-Layer Assembly.  

Science.gov (United States)

The layer-by-layer technique has been used as a powerful method to produce multilayer thin films with tunable properties. When natural polymers are employed, complicated phenomena such as self-aggregation and fibrilogenesis can occur, making it more difficult to obtain and characterize high-quality films. The weak acid and base character of such materials provides multilayer systems that may differ from those found with synthetic polymers due to strong self-organization effects. Specifically, LbL films prepared with chitosan and silk fibroin (SF) often involve the deposition of fibroin fibrils, which can influence the assembly process, surface properties, and overall film functionality. In this case, one has the intriguing possibility of realizing multilayer thin films with aligned nanofibers. In this article, we propose a strategy to control fibroin fibril formation by adjusting the assembly partner. Aligned fibroin fibrils were formed when chitosan was used as the counterpart, whereas no fibrils were observed when poly(allylamine hydrochloride) (PAH) was used. Charge density, which is higher in PAH, apparently stabilizes SF aggregates on the nanometer scale, thereby preventing their organization into fibrils. The drying step between the deposition of each layer was also crucial for film formation, as it stabilizes the SF molecules. Preliminary cell studies with optimized multilayers indicated that cell viability of NIH-3T3 fibroblasts remained between 90 and 100% after surface seeding, showing the potential application of the films in the biomedical field, as coatings and functional surfaces. PMID:25469860

de Moraes, Mariana Agostini; Crouzier, Thomas; Rubner, Michael; Beppu, Marisa Masumi

2015-01-12

142

Silk fibroin microparticles as carriers for delivery of human recombinant bone morphogenetic protein-2 : in vitro and in vivo bioactivity  

OpenAIRE

The in vitro and in vivo efficiency of fibroin microparticles as a delivery carrier for bone morphogenetic protein-2 (BMP-2) was evaluated. BMP-2 was encapsulated in silk fibroin particles that were produced by a simple and very mild processing method. The dose-response of BMP-2-loaded fibroin particles was examined in C2C12 cells, after 5 days of culture. The BMP-2 retained most of its activity as observed by the increase in alkaline phosphatase activity, which was much higher when BMP-2 was...

Bessa, Paulo C.; Balmayor, Elizabeth Rosado; Hartinger, Joachim; Zanoni, Gerald; Dopler, Daniela; Meinl, Alexandra; Banerjee, Asmita; Casal, Margarida; Redl, Heinz; Reis, R. L.; Griensven, Martijn

2010-01-01

143

Activation of the Ubiquitin Proteasome Pathway by Silk Fibroin Modified Chitosan Nanoparticles in Hepatic Cancer Cells  

Science.gov (United States)

Silk fibroin (SF) is a protein with bulky hydrophobic domains and can be easily purified as sericin-free silk-based biomaterial. Silk fibroin modified chitosan nanoparticle (SF-CSNP), a biocompatible material, has been widely used as a potential drug delivery system. Our current investigation studied the bio-effects of the SF-CSNP uptake by liver cells. In this experiment, the characterizations of SF-CSNPs were measured by particle size analysis and protein assay. The average size of the SF-CSNP was 311.9 ± 10.7 nm, and the average zeta potential was +13.33 ± 0.3 mV. The SF coating on the SF-CSNP was 6.27 ± 0.17 ?g/mL. Moreover, using proteomic approaches, several proteins involved in the ubiquitin proteasome pathway were identified by analysis of differential protein expressions of HepG2 cell uptake the SF-CSNP. Our experimental results have demonstrated that the SF-CSNP may be involved in liver cancer cell survival and proliferation. PMID:25588218

Yang, Ming-Hui; Chung, Tze-Wen; Lu, Yi-Shan; Chen, Yi-Ling; Tsai, Wan-Chi; Jong, Shiang-Bin; Yuan, Shyng-Shiou; Liao, Pao-Chi; Lin, Po-Chiao; Tyan, Yu-Chang

2015-01-01

144

Activation of the Ubiquitin Proteasome Pathway by Silk Fibroin Modified Chitosan Nanoparticles in Hepatic Cancer Cells  

Directory of Open Access Journals (Sweden)

Full Text Available Silk fibroin (SF is a protein with bulky hydrophobic domains and can be easily purified as sericin-free silk-based biomaterial. Silk fibroin modified chitosan nanoparticle (SF-CSNP, a biocompatible material, has been widely used as a potential drug delivery system. Our current investigation studied the bio-effects of the SF-CSNP uptake by liver cells. In this experiment, the characterizations of SF-CSNPs were measured by particle size analysis and protein assay. The average size of the SF-CSNP was 311.9 ± 10.7 nm, and the average zeta potential was +13.33 ± 0.3 mV. The SF coating on the SF-CSNP was 6.27 ± 0.17 ?g/mL. Moreover, using proteomic approaches, several proteins involved in the ubiquitin proteasome pathway were identified by analysis of differential protein expressions of HepG2 cell uptake the SF-CSNP. Our experimental results have demonstrated that the SF-CSNP may be involved in liver cancer cell survival and proliferation.

Ming-Hui Yang

2015-01-01

145

Activation of the ubiquitin proteasome pathway by silk fibroin modified chitosan nanoparticles in hepatic cancer cells.  

Science.gov (United States)

Silk fibroin (SF) is a protein with bulky hydrophobic domains and can be easily purified as sericin-free silk-based biomaterial. Silk fibroin modified chitosan nanoparticle (SF-CSNP), a biocompatible material, has been widely used as a potential drug delivery system. Our current investigation studied the bio-effects of the SF-CSNP uptake by liver cells. In this experiment, the characterizations of SF-CSNPs were measured by particle size analysis and protein assay. The average size of the SF-CSNP was 311.9 ± 10.7 nm, and the average zeta potential was +13.33 ± 0.3 mV. The SF coating on the SF-CSNP was 6.27 ± 0.17 ?g/mL. Moreover, using proteomic approaches, several proteins involved in the ubiquitin proteasome pathway were identified by analysis of differential protein expressions of HepG2 cell uptake the SF-CSNP. Our experimental results have demonstrated that the SF-CSNP may be involved in liver cancer cell survival and proliferation. PMID:25588218

Yang, Ming-Hui; Chung, Tze-Wen; Lu, Yi-Shan; Chen, Yi-Ling; Tsai, Wan-Chi; Jong, Shiang-Bin; Yuan, Shyng-Shiou; Liao, Pao-Chi; Lin, Po-Chiao; Tyan, Yu-Chang

2014-01-01

146

Preparing silk fibroin nanofibers through electrospinning: further heparin immobilization toward hemocompatibility improvement.  

Science.gov (United States)

Sodium heparin (HS) was immobilized on the surface of the silk fibroin nanofibers (FS) prepared by electrospinning with the objective of improving the hemocompatibility of the fibers for application as scaffolds in tissue engineering. The nanofiber mats of silk fibroin without (MF-FS) and with (MF-FS/HS) immobilized heparin were characterized through scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), thermogravimetric analyses (TGA), energy dispersive spectroscopy (EDS), contact angle, chemical analysis, and biological tests. The formation of hydrogen bonds between the silk fibroin and heparin was discussed based on FTIR-ATR spectra. The amount of immobilized heparin was quantified through papain/N-acetyl-l-cysteine digestion followed by dimethylmethylene blue complexation. Furthermore, the samples with immobilized HS showed higher hydrophilic capability compared to samples without HS due to lower contact angles. It was possible to verify that the capillary end-to-collector distance of 8.5 cm and flow rate of 0.35 mL h(-1) used in the electrospinning process at 20 kV are good conditions for obtaining a small average fiber diameter maintaining the amount of immobilized heparin on MF-FS/HS in ca. 4% w/w. Biological analysis showed that no hemolysis is provoked by MF-FS and MF-FS/HS mat fragments and those such mats are not toxic to Vero cells. However, the MF-FS/HS showed higher cell growth and proliferation than MF-FS, indicating an improvement in the hemocompatibility of the material due to heparin immobilization. PMID:24724905

Cestari, Marília; Muller, Vinícius; Rodrigues, Jean Henrique da Silva; Nakamura, Celso V; Rubira, Adley F; Muniz, Edvani C

2014-05-12

147

Development of a sutureless dural substitute from Bombyx mori silk fibroin.  

Science.gov (United States)

Silk solvent casting, electrospinning, and electrogelation techniques were used to create a biodegradable, biocompatible silk fibroin dural substitute. The all-silk system was designed and produced to improve on currently available materials, grafts and tissue sealants used for dural closure in neurosurgery. The silk biomaterial was successfully fabricated as a dual layer adhesive system designed to seal durotomies while also functioning as a dural regeneration scaffold. The mechanical characteristics, biocompatibility, biodegradability, and hydrodynamic sealing capability of the material were evaluated. Results showed that the biomaterial was biocompatible with neural cells and fibroblasts, had mechanical properties mimicking the natural dura, was biodegradable with controllable degradation, and was able to seal against a hydrodynamic pressure of 205 mmHg, which greatly exceeds the maximum cerebrospinal fluid pressure seen in both cranial and spinal dural closures of 50 mmHg. Based on its design and experimental results, the adhesive silk dual layer composite biomaterial shows potential as a sutureless dural repair system that would improve on current dural closure techniques. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014. PMID:24919581

Flanagan, Kelly E; Tien, Lee W; Elia, Roberto; Wu, Julian; Kaplan, David

2014-06-12

148

Current research on electrospinning of silk fibroin and its blends with natural and synthetic biodegradable polymers  

Science.gov (United States)

Silk fibroin (SF) is a kind of natural polymers with a great potential in biomedical application. Due to its good biocompatibility, biodegradability and minimal inflammatory reaction, SF is an excellent candidate for generating tissue engineering scaffolds. Electrospinning is a simple and effective method to fabricate nanofibers, which has several amazing characteristics such as very large surface area to volume ratio, flexibility in surface functionalities, and superior mechanical performance. The electrospun nanofibers from SF and its blends have been used for varied tissue engineering. This paper will give a brief review about the structure, properties and applications of SF and blend nanofibers via electrospinning.

Zhang, Jian-Guang; Mo, Xiu-Mei

2013-06-01

149

In situ deposition of flower-like ZnO on silk fibroin fibers  

Energy Technology Data Exchange (ETDEWEB)

In this paper, a convenient biomineralization technique has been developed to form and assemble flower-like zinc oxide (ZnO) on silk fibroin fiber (SFF). Therein, SFF functions as supporting substrate and reactive sites for the in situ generation of ZnO particles. The photoluminescence (PL) of the resulting nanocomposite ZnO/SFF is investigated extensively. The PL peaks are mainly in the visible region (red), which is different from the usual ZnO region (green and violet). As-prepared ZnO/SFF nanocomposites could be useful in the medical field, photoelectron transfer devices, biomolecular detection, and antibacterial agents. (orig.)

Xu, Jia; Su, Huilan; Han, Jie; Chen, Ying; Song, Weiqiang; Gu, Yu.; Zhang, Di [Shanghai Jiao Tong University, State Key Lab of Metal Matrix Composites, Shanghai (China); Moon, Won-Jin [Korea Basic Science Institute, Gwangju (Korea, Republic of)

2012-07-15

150

In situ deposition of flower-like ZnO on silk fibroin fibers  

Science.gov (United States)

In this paper, a convenient biomineralization technique has been developed to form and assemble flower-like zinc oxide (ZnO) on silk fibroin fiber (SFF). Therein, SFF functions as supporting substrate and reactive sites for the in situ generation of ZnO particles. The photoluminescence (PL) of the resulting nanocomposite ZnO/SFF is investigated extensively. The PL peaks are mainly in the visible region (red), which is different from the usual ZnO region (green and violet). As-prepared ZnO/SFF nanocomposites could be useful in the medical field, photoelectron transfer devices, biomolecular detection, and antibacterial agents.

Xu, Jia; Su, Huilan; Han, Jie; Chen, Ying; Song, Weiqiang; Gu, Yu; Moon, Won-Jin; Zhang, Di

2012-07-01

151

The application with tetramethyl pyrazine for antithrombogenicity improvement on silk fibroin surface  

Energy Technology Data Exchange (ETDEWEB)

Chuanxiongqin (tetramethyl pyrazine, TMPZ) is an active ingredient of the Chinese herb and was used to improve the anticoagulant activity of silk fibroin (SF). The side methyl of TMPZ was oxidized, and then linked to polyacrylic acid (PAA) via an ester bond. The prepared conjugate was further mixed with SF solutions at different ratios to make blend films. The resulting products were characterized by FTIR, UV spectrometer and X-ray photoelectron spectroscopy (XPS). The in vitro antithrombogenicity were evaluated by the activated partial thromboplastin time (APTT) and the prothrombin time (PT). It was shown that blend films had longer coagulation time than the pure SF film.

Lian Xiaojie [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Wang Song [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)], E-mail: wangsongbit@126.com; Xu Guoliang; Lin Nini; Li Qian; Zhu Hesun [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

2008-11-15

152

Study on the preparation of collagen-modified silk fibroin films and their properties  

Energy Technology Data Exchange (ETDEWEB)

Blended films were prepared from a silk fibroin (SF) solution by adding a small amount of type I collagen (<5%). The mechanical properties of the wet films modified by collagen were improved obviously. The elongation at break reached 42%, and the smaller contact angles revealed that modified films had better hydrophilicity. 1% heparin was also added to modify the SF films to further improve the in vitro antithrombogenecity. The internal structure of the modified SF films was investigated with scanning electron microscopy, x-ray diffraction and Fourier transform infrared attenuated total reflection spectroscopy. The result indicates that the addition of a small amount of collagen and heparin did not change their conformation.

Tang Yin; Cao Chuanbao; Ma Xilan; Chen Chen; Zhu Hesun [Research Center of Material Science, Beijing Institute of Technology, Bejing 100081 (China)

2006-12-01

153

A Novel Nanocomposite Particle of Hydroxyapatite and Silk Fibroin: Biomimetic Synthesis and Its Biocompatibility  

OpenAIRE

A novel bone-like biomaterial of hydroxyapatite (HAP) and silk fibroin (SF) composite was developed by biomimetic synthesis. The composite was precipitated from drops of Ca(OH)2 suspension and H3PO4 solution with SF. With this method, the HAP nanocrystals were obtained by self-assembling on a SF surface whose c-axis was aligned with the long-axis direction of SF in microstructures; this shares the same misconstrues of collagen and HAP with that in the natural bone. The HAP/SF composite then d...

Lin Niu; Rui Zou; Qida Liu; Quanli Li; Xinmin Chen; Zhiqing Chen

2010-01-01

154

The application with tetramethyl pyrazine for antithrombogenicity improvement on silk fibroin surface  

International Nuclear Information System (INIS)

Chuanxiongqin (tetramethyl pyrazine, TMPZ) is an active ingredient of the Chinese herb and was used to improve the anticoagulant activity of silk fibroin (SF). The side methyl of TMPZ was oxidized, and then linked to polyacrylic acid (PAA) via an ester bond. The prepared conjugate was further mixed with SF solutions at different ratios to make blend films. The resulting products were characterized by FTIR, UV spectrometer and X-ray photoelectron spectroscopy (XPS). The in vitro antithrombogenicity were evaluated by the activated partial thromboplastin time (APTT) and the prothrombin time (PT). It was shown that blend films had longer coagulation time than the pure SF film

155

Preparation of wound dressing of polyvinyl alcohol/silk fibroin hydrogels by gamma radiation  

International Nuclear Information System (INIS)

Poly vinylalcohol/silk fibroin (PVA/SF) hydrogels were prepared by ?-radiation. The preparation conditions such as absorbed doses and PVA/SF concentrations were investigated. When exposed to ? -radiation, PVA/SF was crosslinked to yield high water absorption materials with water content of 100 - 1000% of their dried weight depending on the preparation conditions. The crosslinked density seems to be the main factor governing the swelling of these gels. The swelling behaviors in NaCl aqueous solutions were also investigated. The swelling of PVA/SF hydrogels decreases when exposed to electrolyte solution. With an increase of absorbed dose, the gel fraction of PVA/SF increases

156

Dielectric breakdown strength of regenerated silk fibroin films as a function of protein conformation.  

Science.gov (United States)

Derived from Bombyx mori cocoons, regenerated silk fibroin (RSF) exhibits excellent biocompatibility, high toughness, and tailorable biodegradability. Additionally, RSF materials are flexible, optically clear, easily patterned with nanoscale features, and may be doped with a variety bioactive species. This unique combination of properties has led to increased interest in the use of RSF in sustainable and biocompatible electronic devices. In order to explore the applicability of this biopolymer to the development of future bioelectronics, the dielectric breakdown strength (Ebd) of RSF thin films was quantified as a function of protein conformation. The application of processing conditions that increased ?-sheet content (as determined by FTIR analysis) and produced films in the silk II structure resulted in RSF materials with improved Ebd with values reaching up to 400 V/?m. PMID:23987229

Dickerson, Matthew B; Fillery, Scott P; Koerner, Hilmar; Singh, Kristi M; Martinick, Katie; Drummy, Lawrence F; Durstock, Michael F; Vaia, Richard A; Omenetto, Fiorenzo G; Kaplan, David L; Naik, Rajesh R

2013-10-14

157

Dissolvable films of silk fibroin for ultrathin conformal bio-integrated electronics  

Science.gov (United States)

Electronics that are capable of intimate, non-invasive integration with the soft, curvilinear surfaces of biological tissues offer important opportunities for diagnosing and treating disease and for improving brain/machine interfaces. This article describes a material strategy for a type of bio-interfaced system that relies on ultrathin electronics supported by bioresorbable substrates of silk fibroin. Mounting such devices on tissue and then allowing the silk to dissolve and resorb initiates a spontaneous, conformal wrapping process driven by capillary forces at the biotic/abiotic interface. Specialized mesh designs and ultrathin forms for the electronics ensure minimal stresses on the tissue and highly conformal coverage, even for complex curvilinear surfaces, as confirmed by experimental and theoretical studies. In vivo, neural mapping experiments on feline animal models illustrate one mode of use for this class of technology. These concepts provide new capabilities for implantable and surgical devices.

Kim, Dae-Hyeong; Viventi, Jonathan; Amsden, Jason J.; Xiao, Jianliang; Vigeland, Leif; Kim, Yun-Soung; Blanco, Justin A.; Panilaitis, Bruce; Frechette, Eric S.; Contreras, Diego; Kaplan, David L.; Omenetto, Fiorenzo G.; Huang, Yonggang; Hwang, Keh-Chih; Zakin, Mitchell R.; Litt, Brian; Rogers, John A.

2010-06-01

158

Robust microcapsules with controlled permeability from silk fibroin reinforced with graphene oxide.  

Science.gov (United States)

Robust and stable microcapsules are assembled from poly-amino acid-modified silk fibroin reinforced with graphene oxide flakes using layer-by-layer (LbL) assembly, based on biocompatible natural protein and carbon nanosheets. The composite microcapsules are extremely stable in acidic (pH 2.0) and basic (pH 11.5) conditions, accompanied with pH-triggered permeability, which facilitates the controllable encapsulation and release of macromolecules. Furthermore, the graphene oxide incorporated into ultrathin LbL shells induces greatly reinforced mechanical properties, with an elastic modulus which is two orders of magnitude higher than the typical values of original silk LbL shells and shows a significant, three-fold reduction in pore size. Such strong nanocomposite microcapsules can provide solid protection of encapsulated cargo under harsh conditions, indicating a promising candidate with controllable loading/unloading for drug delivery, reinforcement, and bioengineering applications. PMID:25104349

Ye, Chunhong; Combs, Zachary A; Calabrese, Rossella; Dai, Hongqi; Kaplan, David L; Tsukruk, Vladimir V

2014-12-29

159

Variation of the effect of calcium phosphate enhancement of implanted silk fibroin ligament bone integration.  

Science.gov (United States)

In this article, low crystallinity hydroxyapatite (LHA) is developed and utilized to modify silk fibroin scaffolds which are applied to repair bone/ligament defects successfully. It can promote osteogenesis which is authenticated through in vitro and in vivo tests. The scaffold is an efficient carrier, supporting cell proliferation and differentiation. Meanwhile, cytocompatibility and osteoblastic gene expressions (RUNX2 and osteocalcin, for example) of rabbit's bone marrow derived mesenchymal stem cells (MSCs) are significantly boosted on LHA/silk scaffold. Further, for animal trial, almost 60% of bone volume and 80% of original mechanical strength are recovered after 4 months' bone/ligament regeneration in bone tunnel of rabbit model, where significant amount of bone tissue regeneration is also confirmed by data of histological evaluation and micro computed tomography (?-CT). Hence, the invented scaffold is applicable for ligament/bone regeneration in future lager animal and clinical trials. PMID:23680366

Shi, Pujiang; Teh, Thomas K H; Toh, Siew L; Goh, James C H

2013-08-01

160

Silk fibroin and 4-hexylresorcinol incorporation membrane for guided bone regeneration.  

Science.gov (United States)

The objective of this study was to demonstrate that a silk fibroin (SF) and 4-hexylresorcinol (4-HR) incorporation membrane could be used for a guided bone regeneration technique. Fourier transform infrared measurements were obtained to determine change of physical property of SF membrane by 4-HR incorporation. Two peri-implant defects, 3.0 × 5.0 mm (width × length), were prepared on the lateral side of the implant hole in the tibia of New Zealand white rabbits (n = 8). The peri-implant defect was left unfilled in the control group. Silk fibroin + 4-HR membrane was applied to the peri-implant defect in the experimental group. The 8 animals were killed at 8 weeks after implantation. Subsequently, removal torque test and histomorphometric evaluation were done. Fourier transform infrared spectroscopy showed no specific chemical interaction between 4-HR and SF. In the histomorphometric analysis, the mean bone regeneration was 18.3 ± 1.9 mm(2) in the experimental group and 9.3 ± 0.9 mm(2) in the control group (P = 0.004). In conclusion, the SF and 4-HR incorporation membrane successfully regenerated bone in the rabbit tibia peri-implant bone defect model. PMID:24220375

Lee, Sang-Woon; Kim, Seong-Gon; Song, Ji-Young; Kweon, Haeyong; Jo, You-Young; Lee, Kwang-Gill; Kang, Seok-Woo; Yang, Byoung-Eun

2013-11-01

161

Study on Preparation of n-HA and Silk Fibroin Bio-mineral Material  

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Full Text Available A new hydroxyapatite (n-HAª²Silk fibroin (SF bio-mineral material was prepared by using a biomimetic method, with Ca(NO32 and Na3PO4 used as the starting reagent to synthesize the inorganic phase. In details, SF was dissolved in Ca(NO32 solution without desalting procedure, the compound solution was directly dropped into Na3PO4 solution. In this way, HA was synthesized at 37¡?y controlling Ca/P ratio, meanwhile the minerialized HA interacted with SF to form biomineral material. The morphology and structure of this n-HA-SF biomineral material were characterized by XRD, FTIR, XPS and SEM. The results show that there are strong chemical interaction between n-HA and SF. Moreover, in the biomineral material, the inorganic phase is calciumª²deficient hydroxyapatite, containing a small amount of carbonated HA with an average crystal size of 37.6nm. In addition, The particle size of biomineral materials range from 50nm to 200nm.It can be deduced that silk fibroin chain can regulate the growth and morphology of HA crystals. The compressive strength of the biomineral material is 32.21MPa£¬ which is a good potential material for bone tissue engineering and unloadedª²bearing bone defects repairing.

WANG Jiang,ZUO Yi,YANG Wei-Hu,ZHOU Gang,ZHANG Li,LI Yu-Bao

2009-03-01

162

Bio-inspired capillary dry spinning of regenerated silk fibroin aqueous solution  

Energy Technology Data Exchange (ETDEWEB)

To biomimic the spinning process of silkworm or spider, a capillary spinning equipment was applied to spin regenerated silk fibroin (RSF) fibers from RSF aqueous solutions in air. This equipment exhibits a wide processing window for various RSF aqueous solutions. The effects of pH, metal ions, RSF concentration and spinning parameters on the spinnability of the spinning dope and the mechanical properties of the obtained fibers were investigated. As a result, spinning dopes with a pH from 5.2 to 6.9 have good spinnability, especially for the dope with a pH of 6.0 and a Ca{sup 2+} concentration of 0.3 M. The RSF concentration of this dope ranges from 44% to 48%. Under optimized conditions of our dry spinning experiments (L/D, 133; take-up speed, 30 mm/s), the obtained as-spun fiber has a breaking strength of 46 MPa, which can be improved up to 359 MPa after a preliminary post-drawing in 80 vol.% ethanol aqueous solution. Highlights: {yields} Regenerated silk fibroin fibers were prepared by using a dry spinning method. {yields} Dope compositions affect dope spinnability. {yields} Spinning parameters affect dope spinnability and fiber properties. {yields} The breaking stress of the post-treated fiber was up to 359 MPa.

Wei Wei; Zhang Yaopeng, E-mail: zyp@dhu.edu.cn; Zhao Yingmei; Luo Jie; Shao Huili; Hu Xuechao

2011-10-10

163

High-affinity integration of hydroxyapatite nanoparticles with chemically modified silk fibroin  

Energy Technology Data Exchange (ETDEWEB)

Hydroxyapatite (HA)-based nanocomposites were prepared by a co-precipitation method with silk fibroin (SF) serving as organic matrix. Silk fibroin was chemically modified with an alkali solution or an enzyme attempting to improve the interface between the mineral and the organic matrix. The influences of the alkali and enzyme pretreatments on microstructure and physicochemical properties of HA-SF composite were examined and compared. The results reveal that both the two kinds of pretreatments facilitate the formation of highly ordered three-dimensional porous network throughout the composites, increase the microhardness of the composite, and promote the preferential growth of HA crystallites along c-axis. Among all the as-prepared samples, the composite containing the enzyme pretreated SF shows desirable hierarchical microstructure with higher degree of organization and more uniform pore size distribution. Due to the enzyme pretreatment, HA crystallites undergo obvious changes in morphology from rod-like to whisker-like and in crystal growth towards more apparent epitaxy along c-axis. The alkali pretreatment induces the stronger chemical interactions between HA and SF and thus to strengthen the inorganic-organic interfacial adhesion. The newly developed HA-SF composites are expected to be attractive biomedical materials for bone repair and remodeling.

Wang Li; Li Chunzhong [East China University of Science and Technology, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering (China)], E-mail: czli@ecust.edu.cn; Senna, Mamoru [Keio University, Department of Applied Chemistry, Faculty of Science and Technology (Japan)

2007-10-15

164

Silk fibroin-keratin based 3D scaffolds as a dermal substitute for skin tissue engineering.  

Science.gov (United States)

Development of highly vascular dermal tissue-engineered skin substitutes with appropriate mechanical properties and cellular cues is in need for significant advancement in the field of dermal reconstruction. Limitations have been imposed on natural biomaterials despite their superb biocompatibility hence, studies in biomaterial blending have been ongoing. Herein, we investigated blends of silk fibroin and human hair-derived keratin as wound-healing substrates that promote enhanced fibroblast cell adhesion and proliferation. Three-dimensional (3D) blended scaffolds were fabricated by freeze-drying, and their physico-chemical, mechanical and degradable properties were extensively characterized. Cytocompatibility tests observing cell adhesion and cell proliferation have shown significant enhancements in blended scaffolds. Also, its structural composition with high porosity (>85%) and interconnected pores in the range of 100-120 microns further confirms the superiority of the complex compared to its counterparts. FTIR studies identified the enhanced stability within its structure and were followed-up with sequential experiments to demonstrate improved thermal, degradation, and mechanical properties. Furthermore, immunohistochemical staining revealed greater expression of collagen type I in the cultured cells, indicating functional fibroblast proliferation and, hence, the exciting potential of this construct for dermal applications. Taken together, this study demonstrates the promising attributes from blended biomaterials and specifically present silk fibroin and human hair keratin blended scaffolds as a promising dermal substitute for skin tissue engineering. PMID:25372050

Bhardwaj, Nandana; Sow, Wan Ting; Devi, Dipali; Ng, Kee Woei; Mandal, Biman B; Cho, Nam-Joon

2014-12-22

165

Contribution to the ultrastructural study of silk-excretion cells and autoradiographic analysis of intracellular fibroin transport in Bombyx mori L  

International Nuclear Information System (INIS)

It is much easier to study the mechanisms involved in the synthesis and exportation of extracellular proteins in the biological material chosen is highly differentiated. The silk-excretion gland of the silkworm is ideal in this respect because during the larva period, especially at the end of the 5th and last stage, the cells at the rear (excreting tube) synthesize and export massive quantities of a single protein: fibroin. These phenomena were explored by a cytological study carried out mainly by electron microscopy and autoradiography. The results obtained are given. They relate first of all to the morphological development of the secretion tube cells from the end of the 4th larva stage to the spinning of the cocoon, and contribute new information on the cell changes during the 4th slough and the end of the 5th age. They also concern intracellular fibroin transport which is proved to take place through the Golgi apparatus, and finally the possible role of the microtubules and microfilaments in fibroin transport and secretion. On this last point the results so far constitute only, a preliminary approach which justifie no final conclusions; they merely suggest that the microfilaments of the apical region are involved in the secretion process

166

Surface modification and properties of Bombyx mori silk fibroin films by antimicrobial peptide  

Science.gov (United States)

The Bombyx mori silk fibroin films (SFFs) were modified by a Cecropin B ( CB) antimicrobial peptide, (NH 2)-NGIVKAGPAIAVLGEAAL-CONH 2, using the carbodiimide chemistry method. In order to avoid the dissolution of films during the modification procedure, the SFFs were first treated with 60% (v/v) ethanol aqueous solution, resulting a structural transition from unstable silk I to silk II. The investigation of modification conditions showed that the surface-modified SFFs had the satisfied antimicrobial activity and durability when they were activated by EDC·HCl/NHS solution followed by a treatment in CB peptide/PBS buffer (pH 6.5 or 8) solution at ambient temperature for 2 h. Moreover, the surface-modified SFFs showed the smaller contact angle due to the hydrophilic antimicrobial peptides coupled on the film surface, which is essential for the cell adhesion and proliferation. AFM results indicated that the surface roughness of SFFs was considerably increased after the modification by the peptides. The elemental composition analysis results also suggested that the peptides were tightly coupled to the surface of SFFs. This approach may provide a new option to engineer the surface-modified implanted materials preventing the biomaterial-centered infection (BCI).

Bai, Liqiang; Zhu, Liangjun; Min, Sijia; Liu, Lin; Cai, Yurong; Yao, Juming

2008-03-01

167

Shear-induced rigidity in spider silk glands  

Science.gov (United States)

We measure the elastic stiffnesses of the concentrated viscous protein solution of the dehydrated Nephila clavipes major ampullate gland with Brillouin light scattering. The glandular material shows no rigidity but possesses a tensile stiffness similar to that of spider silk. We show, however, that with application of a simple static shear, the mechanical properties of the spider gland protein mixture can be altered irreversibly, lowering symmetry and enabling shear waves to be supported, thus, giving rise to rigidity and yielding elastic properties similar to those of the naturally spun (i.e., dynamically sheared) silk.

Koski, Kristie J.; McKiernan, Keri; Akhenblit, Paul; Yarger, Jeffery L.

2012-09-01

168

Preparation of Eri silk fibroin and gelatin blend film loaded chlorhexidine using as model for hydrophilic drug release  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this research was to prepare Eri silk fibroin solution for preparing silk film loaded chlorhexidine drug as model for hydrophilic drug release. The Eri silk cocoons were boiled in 0.5%NaCO3 solution at 90?, and then left in air dried at room temperature. The fibroin was dissolved in 9M (Ca(NO32 with ethanol (2 by mole and heated at 70?. The silk fibroin (SF solution was then dialyzed to exclude salt in phosphate buffer. The SF and gelatin (G solutions were mixed for preparation of films in both with and without chlorhexidine. The films were observed their morphology under scanning electron microscope. The results found that all of films were rough of their surfaces, homogeneous texture without phase separation. The native SF film composed of pores throughout the film area but did not observe in native G film. The results also showed that the SF and G can be good interacted to form hydrogen bonds. These were indicated from FTIR spectra and thermal analysis. The chlorhexidine drug has not affect on the changes of film properties. However, the releasing pattern of chlorhexidine from each film was varied. The highest rate of drug releasing was found in the native SF film while the native G film was the lowest. It might be suggested that the drug releasing rate was depended on polarity of each polymer components.

Chirapha Butiman

2012-07-01

169

Microstructural, thermal and antibacterial properties of electron beam irradiated Bombyx mori silk fibroin films  

Energy Technology Data Exchange (ETDEWEB)

The Bombyx mori silk fibroin (SF) films were prepared by solution casting method and the effects of electron beam on structural, thermal and antibacterial responses of the prepared films were studied. The electron irradiation for different doses was carried out using 8 MeV Microtron facility at Mangalore University. The changes in microstructural parameters and thermal stability of the films were investigated using Wide Angle X-ray Scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Both microstructuralline parameters (crystallite size and lattice strain (g in %)) and thermal stability of the irradiated films have increased with radiation dosage. Agar diffusion method demonstrated the antibacterial activity of SF film which was increased after irradiation on both Gram-positive and Gram-negative species.

Asha, S.; Sanjeev, Ganesh, E-mail: ganeshsanjeev@rediffmail.com [Microtron Center, Department of Studies in Physics, Mangalore University, Mangalagangotri - 574199 (India); Sangappa [Department of Studies in Physics, Mangalore University, Mangalagangotri - 574199 (India); Naik, Prashantha; Chandra, K. Sharat [Department of Biosciences, Mangalore University, Mangalagangotri - 574199 (India)

2014-04-24

170

Effect of Methanol Treatment on Regenerated Silk Fibroin Microparticles Prepared by the Emulsification-Diffusion Technique  

Directory of Open Access Journals (Sweden)

Full Text Available Silk Fibroin (SF microparticles containing hollow structure were prepared by a water-in-oil emulsion solvent diffusion method without any surfactants. Aqueous SF solution and ethyl acetate were used as water and oil phases, respectively. Influences of SF concentration and post methanol treatment on microparticle characteristics were investigated. All microparticles contained open hollow structures. Microparticle sizes increased with the SF concentration. Conformation of SF microparticles determined from FTIR spectra changed from predominantly random coil to ?-sheet form after methanol treatment. Particle surfaces of methanol-treated SF microparticles were rougher than those of non-treated. The SF concentrations and methanol treatment did not affect open hollow structure of the SF microparticles. Major advantages of this method are the elimination of surfactants and extractable pore templates. These hollow SF microparticles are expected to be potential used as biodegradable microcarriers of cell and protein drug, because their hollow structures should permit cell attachment and enzyme immobilization.

Yodthong Baimark

2009-01-01

171

Microstructural, thermal and antibacterial properties of electron beam irradiated Bombyx mori silk fibroin films  

International Nuclear Information System (INIS)

The Bombyx mori silk fibroin (SF) films were prepared by solution casting method and the effects of electron beam on structural, thermal and antibacterial responses of the prepared films were studied. The electron irradiation for different doses was carried out using 8 MeV Microtron facility at Mangalore University. The changes in microstructural parameters and thermal stability of the films were investigated using Wide Angle X-ray Scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Both microstructuralline parameters (crystallite size and lattice strain (g in %)) and thermal stability of the irradiated films have increased with radiation dosage. Agar diffusion method demonstrated the antibacterial activity of SF film which was increased after irradiation on both Gram-positive and Gram-negative species

172

The application with protocatechualdehyde to improve anticoagulant activity and cell affinity of silk fibroin  

International Nuclear Information System (INIS)

Protocatechualdehyde (PCA) is one of the effective ingredients extracted from Danshen (Radix Salviae Miltiorrhizae) and was employed to modify the silk fibroin (SF) by graft polymerization and surface adsorption. The surface composition of modified SF was characterized by attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and UV spectrophotometer. The anticoagulant activity of modified SF was assessed by in vitro coagulation test and platelet adhesion measurement. The endothelial cell affinity was evaluated by a parallel plate flow chamber. The test results indicated that with the introduction of PCA into SF, the anticoagulant activity has been improved obviously. And the SF surface composition altered by PCA, but did not disturb its ?-sheet conformation. Moreover, the adsorbed PCA on SF surface can enhance the endothelial cell affinity

173

A Novel Nano composite Particle of Hydroxyapatite and Silk Fibroin: Biomimetic Synthesis and Its Biocompatibility  

International Nuclear Information System (INIS)

A novel bone-like bio material of hydroxyapatite (HAP) and silk fibroin (SF) composite was developed by biomimetic synthesis. The composite was precipitated from drops of Ca(OH)2 suspension and H3PO4 solution with SF. With this method, the HAP nano crystals were obtained by self-assembling on a SF surface whose c-axis was aligned with the long-axis direction of SF in microstructures; this shares the same misconstrues of collagen and HAP with that in the natural bone. The HAP/SF composite then demonstrated that it could promote osteoblast proliferation in vitro and new bone formation in vivo. The novel bio material is a promising material for bone replacement and regeneration.

174

Silk fibroin/gelatin blend films crosslinked with enzymes for biomedical applications.  

Science.gov (United States)

Microbial transglutaminase (mTG) and mushroom tyrosinase (MT) are used to crosslink B. mori silk fibroin/gelatin (SF/G) films. Crosslinked and uncrosslinked SF/G films show no phase separation. The thermal behavior and the conformational structure of SF/G films are strongly affected by blending and enzymatic treatment. Formation of high thermally stable crosslinked macromolecular species is observed, suggesting the occurrence of strong intermolecular interactions between the two polymers as confirmed by FT-Raman spectroscopy. Preliminary in vitro tests show that MT-crosslinked blends with G amounts ?40% and mTG-crosslinked SF/G 60/40 films support C2C12 cardiomyocyte adhesion and proliferation. PMID:23956190

Taddei, Paola; Chiono, Valeria; Anghileri, Anna; Vozzi, Giovanni; Freddi, Giuliano; Ciardelli, Gianluca

2013-11-01

175

In situ bioinspired synthesis of silver chloride nanocrystals on silk fibroin fibers  

Science.gov (United States)

Silver chloride (AgCl) nanocrystals were formed and grown on silk fibroin fibers (SFFs) by a room-temperature process. Practically, the degummed SFFs were immersed into silver nitrate solution and sodium chloride solution in turn. The amino acids on the SFF surface were negatively charged in alkaline impregnant, providing locations to immobilize silver ions and form silver chloride seeds. AgCl nanocrystals can further grow into cubic AgCl nanocrystals with an edge of about 100 nm. The morphologies of the AgCl nanocrystals were mostly influenced by the concentration of sodium chloride solution and the special configurations of the SFFs. The target AgCl/SFF nanocomposites constructed by AgCl nanocrystals and substrate SFFs could be used as photocatalysts in water splitting and antibacterial agents. This work provides an important example in the introduction of natural biofibers to the synthesis of functional hybrid nanocomposites by a green and mild technique.

Su, Huilan; Han, Jie; Dong, Qun; Xu, Jia; Chen, Ying; Gu, Yu; Song, Weiqiang; Zhang, Di

2011-02-01

176

Conformation Transition and Thermal Properties Study of Silk Fibroin and Poly (?-Caprolactone Blends  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, influence of intermolecular interactions between Silk Fibroin (SF and Poly (?-Caprolactone (PCL in homogeneous blend form on SF conformation changes and thermal properties of the blends was investigated and discussed. The SF/PCL blends were prepared by solution blending and precipitating method, respectively. Dimethylsulfoxide and isopropanol were used as a solvent and a non-solvent, respectively. The blends were characterized by Fourier Transform Infrared Spectroscopy (FTIR, Differential Scanning Calorimetry (DSC, Thermo Gravimetry (TG and Scanning Electron Microscopy (SEM. Conformation transition of SF component from ?-sheet to random coil forms can be induced by blending with PCL. Melting temperature and heat of melting of the PCL decreased as increasing the SF ratio. Thermal stability of the SF can be enhanced by blending with PCL. FTIR, DSC and TG results suggested that intermolecular hydrogen bonds were formed between SF and PCL molecules in the blends. Homogeneous morphology of blends was illustrated by SEM micrographs.

M. Srisa-Ard

2008-01-01

177

Preferential Alignment of Hydroxyapatite Crystallites in Nanocomposites with Chemically Disintegrated Silk Fibroin  

Energy Technology Data Exchange (ETDEWEB)

Hydroxyapatite (HAp) nanocrystals were prepared at room temperature by a coprecipitation method from Ca(OH){sub 2} and H{sub 3}PO{sub 4}, in the presence of chemically disintegrated silk fibroin (SF). Adsorbed amounts of cations on SF and crystallinity of HAp in the composite were increased by the chemical disintegration of SF higher order structure. Preferential alignment of c-axis of HAp crystallites along the longitudinal direction of ca. 150nm SF fibril was observed. These changes due to disintegration of SF were discussed in terms of the chemical interaction between HAp and SF. The resulted composite with preferential alignment of HAp nanocrystals is a good candidate as a starting material for bone substitutes.

Nemoto, Rei; Wang Li [Keio University, Department of Applied Chemistry, Faculty of Science and Technology (Japan); Ikoma, Toshiyuki; Tanaka, Junzo [National Institute for Materials Science (NIMS) (Japan); Senna, Mamoru [Keio University, Department of Applied Chemistry, Faculty of Science and Technology (Japan)], E-mail: senna@applc.keio.ac.jp

2004-06-15

178

Controlling the Release of bFGF from Silk Fibroin Membrane.  

Science.gov (United States)

Since neurotrophic factor is easy to degrade and aggregate, it usually has a short half-life in vitro. To overcome this shortage, neurotrophic factor has been combined with the silk fibroin (SF) membrane to realize less degradation, optimal loading efficiency, sustained release, and good adsorption. By optimizing its binding conditions, main parameters were investigated and its optimal loading efficiency was obtained. bFGF was combined to SF membrane by layer by layer (LbL) static adsorption technique. The natural and nontoxic chondroitin sulfate (CS) was used as a crosslinking agent. Optimization was carried out in three aspects: the concentration of bFGF, the concentration of CS, and the reaction time. This experiment provides a better environment for the growth of cells and offers a new kind material of absorbing neurotrophic factor to meet increasing demand for biological materials. PMID:25484015

Ji, Ya Wei; Kong, Yan; Zhao, Ya Hong; Wang, Ya Ling; Zhao, Jing; Zhang, Lu Zhong; Yang, Yu Min

2014-12-01

179

The application with protocatechualdehyde to improve anticoagulant activity and cell affinity of silk fibroin  

Energy Technology Data Exchange (ETDEWEB)

Protocatechualdehyde (PCA) is one of the effective ingredients extracted from Danshen (Radix Salviae Miltiorrhizae) and was employed to modify the silk fibroin (SF) by graft polymerization and surface adsorption. The surface composition of modified SF was characterized by attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and UV spectrophotometer. The anticoagulant activity of modified SF was assessed by in vitro coagulation test and platelet adhesion measurement. The endothelial cell affinity was evaluated by a parallel plate flow chamber. The test results indicated that with the introduction of PCA into SF, the anticoagulant activity has been improved obviously. And the SF surface composition altered by PCA, but did not disturb its {beta}-sheet conformation. Moreover, the adsorbed PCA on SF surface can enhance the endothelial cell affinity.

Wang Song [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)], E-mail: wangsongbit@126.com; Gao Zhen; Li Erlin; Su Caoning; Zhu Hesun [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

2008-11-15

180

Patterning and photoluminescence of CdS nanocrystallites on silk fibroin fiber  

Energy Technology Data Exchange (ETDEWEB)

CdS nanocrystallites could be formed and assembled into nanoparticle strings and hexagons on natural silk fibroin fiber (SFF) through a room-temperature bio-inspired process. Herein, the biomaterial SFF served as reactive substrate, not only provides the in situ formation sites for CdS nanocrystallites, but also directs the arrangement of nanocrystalline CdS simultaneously. The photoluminescence (PL) of the resulting nanocomposites CdS/SFF is investigated extensively. The PL peaks observed from CdS nanoparticle strings are similar to those of separate CdS nanoparticles, corresponding to the band-edge emission of their individual building blocks (QD-CdS). Moreover, CdS nanoparticle hexagons perform a red-shifted and broadened emission peak.

Han Jie; Su Huilan, E-mail: hlsu@sjtu.edu.cn; Dong Qun; Zhang Di, E-mail: zhangdi@sjtu.edu.cn; Ma Xiaoxiao [Shanghai Jiaotong University, State Key Laboratory of Metal Matrix Composites (China); Zhang Chunfu [Shanghai Jiaotong University, Med-X Research Institute (China)

2010-01-15

181

Characterization of silk fibroin modified surface: a proteomic view of cellular response proteins induced by biomaterials.  

Science.gov (United States)

The purpose of this study was to develop the pathway of silk fibroin (SF) biopolymer surface induced cell membrane protein activation. Fibroblasts were used as an experimental model to evaluate the responses of cellular proteins induced by biopolymer material using a mass spectrometry-based profiling system. The surface was covered by multiwalled carbon nanotubes (CNTs) and SF to increase the surface area, enhance the adhesion of biopolymer, and promote the rate of cell proliferation. The amount of adhered fibroblasts on CNTs/SF electrodes of quartz crystal microbalance (QCM) greatly exceeded those on other surfaces. Moreover, analyzing differential protein expressions of adhered fibroblasts on the biopolymer surface by proteomic approaches indicated that CD44 may be a key protein. Through this study, utilization of mass spectrometry-based proteomics in evaluation of cell adhesion on biopolymer was proposed. PMID:24818131

Yang, Ming-Hui; Yuan, Shyng-Shiou; Chung, Tze-Wen; Jong, Shiang-Bin; Lu, Chi-Yu; Tsai, Wan-Chi; Chen, Wen-Cheng; Lin, Po-Chiao; Chiang, Pei-Wen; Tyan, Yu-Chang

2014-01-01

182

Patterning and photoluminescence of CdS nanocrystallites on silk fibroin fiber  

International Nuclear Information System (INIS)

CdS nanocrystallites could be formed and assembled into nanoparticle strings and hexagons on natural silk fibroin fiber (SFF) through a room-temperature bio-inspired process. Herein, the biomaterial SFF served as reactive substrate, not only provides the in situ formation sites for CdS nanocrystallites, but also directs the arrangement of nanocrystalline CdS simultaneously. The photoluminescence (PL) of the resulting nanocomposites CdS/SFF is investigated extensively. The PL peaks observed from CdS nanoparticle strings are similar to those of separate CdS nanoparticles, corresponding to the band-edge emission of their individual building blocks (QD-CdS). Moreover, CdS nanoparticle hexagons perform a red-shifted and broadened emission peak.

183

Microstructural, thermal and antibacterial properties of electron beam irradiated Bombyx mori silk fibroin films  

Science.gov (United States)

The Bombyx mori silk fibroin (SF) films were prepared by solution casting method and the effects of electron beam on structural, thermal and antibacterial responses of the prepared films were studied. The electron irradiation for different doses was carried out using 8 MeV Microtron facility at Mangalore University. The changes in microstructural parameters and thermal stability of the films were investigated using Wide Angle X-ray Scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Both microstructuralline parameters (crystallite size and lattice strain (g in %)) and thermal stability of the irradiated films have increased with radiation dosage. Agar diffusion method demonstrated the antibacterial activity of SF film which was increased after irradiation on both Gram-positive and Gram-negative species.

Asha, S.; Sangappa, Naik, Prashantha; Chandra, K. Sharat; Sanjeev, Ganesh

2014-04-01

184

A Novel Nanocomposite Particle of Hydroxyapatite and Silk Fibroin: Biomimetic Synthesis and Its Biocompatibility  

Directory of Open Access Journals (Sweden)

Full Text Available A novel bone-like biomaterial of hydroxyapatite (HAP and silk fibroin (SF composite was developed by biomimetic synthesis. The composite was precipitated from drops of Ca(OH2 suspension and H3PO4 solution with SF. With this method, the HAP nanocrystals were obtained by self-assembling on a SF surface whose c-axis was aligned with the long-axis direction of SF in microstructures; this shares the same misconstrues of collagen and HAP with that in the natural bone. The HAP/SF composite then demonstrated that it could promote osteoblast proliferation in vitro and new bone formation in vivo. The novel biomaterial is a promising material for bone replacement and regeneration.

Lin Niu

2010-01-01

185

Preferential Alignment of Hydroxyapatite Crystallites in Nanocomposites with Chemically Disintegrated Silk Fibroin  

International Nuclear Information System (INIS)

Hydroxyapatite (HAp) nanocrystals were prepared at room temperature by a coprecipitation method from Ca(OH)2 and H3PO4, in the presence of chemically disintegrated silk fibroin (SF). Adsorbed amounts of cations on SF and crystallinity of HAp in the composite were increased by the chemical disintegration of SF higher order structure. Preferential alignment of c-axis of HAp crystallites along the longitudinal direction of ca. 150nm SF fibril was observed. These changes due to disintegration of SF were discussed in terms of the chemical interaction between HAp and SF. The resulted composite with preferential alignment of HAp nanocrystals is a good candidate as a starting material for bone substitutes

186

Effect of silk fibroin nanofibers containing silver sulfadiazine on wound healing  

Directory of Open Access Journals (Sweden)

Full Text Available Lim Jeong,1 Min Hee Kim,1 Ju-Young Jung,2 Byung Moo Min,3 Won Ho Park1 1Department of Advanced Organic Materials and Textile System Engineering, 2College of Veterinary Medicine, Chungnam National University, Daejeon, 3Department of Oral Biochemistry, School of Dentistry, Seoul National University, Seoul, South Korea Background: One of the promising applications of silk fibroin (SF in biomedical engineering is its use as a scaffolding material for skin regeneration. The purpose of this study was to determine the wound healing effect of SF nanofibrous matrices containing silver sulfadiazine (SSD wound dressings.Methods: An SF nanofibrous matrix containing SSD was prepared by electrospinning. The cell attachment and spreading of normal human epidermal keratinocytes (NHEK and normal human epidermal fibroblasts (NHEF to SF nanofibers containing three different concentrations of SSD contents (0.1, 0.5, and 1.0 wt% were determined. In addition, a rat wound model was used in this study to determine the wound healing effect of SF nanofibers containing SSD compared with that of Acticoat™, a commercially available wound dressing.Results: The number of NHEK and NHEF attached to SF nanofibers containing SSD decreased when the concentration of SSD increased. The number of attached NHEF cells was lower than that of attached NHEK cells. The SF matrix with 1.0 wt% SSD produced faster wound healing than Acticoat, although 1.0 wt% SSD inhibited the attachment of epidermal cells to SF nanofibers in vitro.Conclusion: The cytotoxic effects of SF nanofibers with SSD should be considered in the development of silver-release dressings for wound healing through its antimicrobial activity. It is challenging to design wound dressings that maximize antimicrobial activity and minimize cellular toxicity. Keywords: silk fibroin, silver sulfadiazine, nanofibrous matrix, wound healing

Jeong L

2014-11-01

187

Strong composite films with layered structures prepared by casting silk fibroin-graphene oxide hydrogels  

Science.gov (United States)

Composite films of graphene oxide (GO) sheets and silk fibroin (SF) with layered structures have been prepared by facile solution casting of SF-GO hydrogels. The as-prepared composite film containing 15% (by weight, wt%) of SF shows a high tensile strength of 221 +/- 16 MPa and a failure strain of 1.8 +/- 0.4%, which partially surpass those of natural nacre. Particularly, this composite film also has a high modulus of 17.2 +/- 1.9 GPa. The high mechanical properties of this composite film can be attributed to its high content of GO (85 wt%), compact layered structure and the strong hydrogen bonding interaction between SF chains and GO sheets.Composite films of graphene oxide (GO) sheets and silk fibroin (SF) with layered structures have been prepared by facile solution casting of SF-GO hydrogels. The as-prepared composite film containing 15% (by weight, wt%) of SF shows a high tensile strength of 221 +/- 16 MPa and a failure strain of 1.8 +/- 0.4%, which partially surpass those of natural nacre. Particularly, this composite film also has a high modulus of 17.2 +/- 1.9 GPa. The high mechanical properties of this composite film can be attributed to its high content of GO (85 wt%), compact layered structure and the strong hydrogen bonding interaction between SF chains and GO sheets. Electronic supplementary information (ESI) available: XPS spectrum of the SF-GO hybrid film, SEM images of lyophilized GO dispersion and the failure surface of GO film. See DOI: 10.1039/c3nr00196b

Huang, Liang; Li, Chun; Yuan, Wenjing; Shi, Gaoquan

2013-04-01

188

Fabrication and characterization of silk fibroin-derived curcumin nanoparticles for cancer therapy  

Directory of Open Access Journals (Sweden)

Full Text Available Vishal Gupta1, Abraham Aseh1,3, Carmen N Ríos1, Bharat B Aggarwal2, Anshu B Mathur11Department of Plastic Surgery; 2Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA; 3School of Pharmacy, Texas Southern University, Houston, TX, USAAbstract: Biologically derived nanoparticles (<100 nm were fabricated for local and sustained therapeutic curcumin delivery to cancer cells. Silk fibroin (SF and chitosan (CS polymers were blended noncovalently to encapsulate curcumin in various proportions of SF and CS (75:25, 50:50, and 25:75 SF:CS or pure SF at two concentrations (0.1% w/v and 10% w/v using the devised capillary-microdot technique. Curcumin-polymer conjugates were frozen, lyophilized, crystallized, suspended in phosphate-buffered saline for characterization, and tested for efficacy against breast cancer cells. All nanoparticle formulations except 0.1% w/v 50:50 SFCS were less than 100 nm in size as determined with the transmission electron microscopy. The entrapment and release of curcumin over eight days was highest for SF-derived nanoparticles as compared to all SFCS blends. The uptake and efficacy of SF-coated curcumin was significantly higher (p < 0.001 than SFCS-coated curcumin in both low and high Her2/neu expressing breast cancer cells. Interestingly, the uptake of curcumin was highest for the high Her2/neu expressing breast cancer cells when delivered with a 10% w/v SF coating as compared to other formulations. In conclusion, SF-derived curcumin nanoparticles show higher efficacy against breast cancer cells and have the potential to treat in vivo breast tumors by local, sustained, and long-term therapeutic delivery as a biodegradable system.Keywords: biodegradable, nanoparticles, curcumin, silk fibroin, breast cancer cells

Vishal Gupta

2009-05-01

189

In situ synthesis and photoluminescence of QD-CdS on silk fibroin fibers at room temperature  

International Nuclear Information System (INIS)

A convenient room-temperature bioinspired technique has been developed to synthesize hybrid nanocomposites consisting of well-dispersed CdS quantum dots (QD) and the substrate silk fibroin fibers (SFF). The biomaterial SFF provides both a supporting substrate and functional sites for the in situ generation of QD-CdS, which is supported by FTIR and PL measurements. The solid QD-CdS/SFF nanocomposites could be useful in photocatalyst, novel luminescence and photoelectron transfer devices. The QD-CdS/silk fibroin (SF) colloid, in which SF acts as both an inherent biocompatibilizer and an efficient passivator of trap sites on the QD-CdS surface, is also available for some potential applications in the biological fields. The bioinspired method and relevant ideas could extend to fabricating other functional hybrid materials

190

In situ synthesis and photoluminescence of QD-CdS on silk fibroin fibers at room temperature  

Energy Technology Data Exchange (ETDEWEB)

A convenient room-temperature bioinspired technique has been developed to synthesize hybrid nanocomposites consisting of well-dispersed CdS quantum dots (QD) and the substrate silk fibroin fibers (SFF). The biomaterial SFF provides both a supporting substrate and functional sites for the in situ generation of QD-CdS, which is supported by FTIR and PL measurements. The solid QD-CdS/SFF nanocomposites could be useful in photocatalyst, novel luminescence and photoelectron transfer devices. The QD-CdS/silk fibroin (SF) colloid, in which SF acts as both an inherent biocompatibilizer and an efficient passivator of trap sites on the QD-CdS surface, is also available for some potential applications in the biological fields. The bioinspired method and relevant ideas could extend to fabricating other functional hybrid materials.

Su Huilan [State Key Lab of Metal Matrix Composites, Shanghai Jiaotong University, Shanghai 200030 (China); Han Jie [State Key Lab of Metal Matrix Composites, Shanghai Jiaotong University, Shanghai 200030 (China); Dong Qun [State Key Lab of Metal Matrix Composites, Shanghai Jiaotong University, Shanghai 200030 (China); Zhang Di [State Key Lab of Metal Matrix Composites, Shanghai Jiaotong University, Shanghai 200030 (China); Guo Qixin [Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502 (Japan)

2008-01-16

191

In situ synthesis and photoluminescence of QD-CdS on silk fibroin fibers at room temperature  

Science.gov (United States)

A convenient room-temperature bioinspired technique has been developed to synthesize hybrid nanocomposites consisting of well-dispersed CdS quantum dots (QD) and the substrate silk fibroin fibers (SFF). The biomaterial SFF provides both a supporting substrate and functional sites for the in situ generation of QD-CdS, which is supported by FTIR and PL measurements. The solid QD-CdS/SFF nanocomposites could be useful in photocatalyst, novel luminescence and photoelectron transfer devices. The QD-CdS/silk fibroin (SF) colloid, in which SF acts as both an inherent biocompatibilizer and an efficient passivator of trap sites on the QD-CdS surface, is also available for some potential applications in the biological fields. The bioinspired method and relevant ideas could extend to fabricating other functional hybrid materials.

Su, Huilan; Han, Jie; Dong, Qun; Zhang, Di; Guo, Qixin

2008-01-01

192

Heat Capacity of B. Mori Silk Fibroin Based on the Vibrational-Motion of Poly(amino acid)s.  

Science.gov (United States)

Bombyx mori silk fibroin heat capacities with and without water have been determined based on the vibrational motions of poly(amino acid)s and water, using the Advanced Thermal Analysis System (ATHAS) Data Bank. The heat capacities, Cp, of dry silk and silk-water were linked to their vibrational spectra based on the group and skeletal vibration contributions. For dry silk, the experimental and calculated Cp agree to better than ±3% between 200 K and 435 K. The heat capacity of the solid silk-water system, below the glass transition, was estimated from a sum of linear combinations of the molar fractions of the vibrational heat capacities of dry silk and glassy water. Calculations are compared to experimental data obtained from calorimetric methods, using hermetic and non-hermetic pans. The approach presented allows one to predict the low temperature vibrational heat capacity for dry silk and for the silk-water system down to zero kelvin, and, together with an extension to higher temperatures, above the glass transition. This can be used as a reference baseline for quantitative thermal analysis of this biomaterial..

Pyda, Marek; Hu, Xiao; Cebe, Peggy

2009-03-01

193

Study of the effects of different sterilization methods on the properties of dense and porous silk fibroin membranes  

International Nuclear Information System (INIS)

Silk fibroin has been widely explored for many biomedical applications, due to its biocompatibility and biodegradability. Sterilization is a fundamental step in biomaterials processing, and it must not alter in a negative way the functionality of medical devices. The aim of this study was to analyze the influence of different sterilization methods in the physical and chemical characteristics of dense silk fibroin membranes. Dense fibroin membranes were sterilized by ultraviolet radiation, 70% ethanol, autoclave, ethylene oxide and gamma radiation, and were analyzed by SEM, FTIR-ATR and XRD. The results for sterilization indicated that the methods didn't cause degradation of the membranes, but the methods that used organic solvent, or increase of humidity and/or temperature (70% ethanol, autoclave and ethylene oxide) altered the molecular conformation of fibroin, increasing the proportion of ?-sheet structure, what indicates an increase of crystallinity. This effect may be positive when a slower degradation of the membranes is desired, depending on the application as a bio material. (author)

194

Delivery of chondroitinase ABC and glial cell line-derived neurotrophic factor from silk fibroin conduits enhances peripheral nerve regeneration.  

Science.gov (United States)

Nerve conduits are a proven strategy for guiding axon regrowth following injury. This study compares degradable silk-trehalose films containing chondroitinase ABC (ChABC) and/or glial cell line-derived neurotrophic factor (GDNF) loaded within a silk fibroin-based nerve conduit in a rat sciatic nerve defect model. Four groups of silk conduits were prepared, with the following silk-trehalose films inserted into the conduit: (a) empty; (b) 1?µg GDNF; (3) 2 U ChABC; and (4) 1?µg GDNF/2 U ChABC. Drug release studies demonstrated 20% recovery of GDNF and ChABC at 6?weeks and 24?h, respectively. Six conduits of each type were implanted into 15?mm sciatic nerve defects in Lewis rats; conduits were explanted for histological analysis at 6?weeks. Tissues stained with Schwann cell S-100 antibody demonstrated an increased density of cells in both GDNF- and ChABC-treated groups compared to empty control conduits (p?Silk fibroin-based nerve conduits possess favourable mechanical and degradative properties and are further enhanced when loaded with ChABC and GDNF. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25424415

Sivak, Wesley N; White, James D; Bliley, Jacqueline M; Tien, Lee W; Liao, Han Tsung; Kaplan, David L; Marra, Kacey G

2014-11-25

195

Non-invasive characterization of structure and morphology of silk fibroin biomaterials using non-linear microscopy  

OpenAIRE

Designing biomaterial scaffolds remains a major challenge in tissue engineering. Key to this challenge is improved understanding of the relationships between the scaffold properties and its degradation kinetics, as well as the cell interactions and the promotion of new matrix deposition. Here we present the use of non-linear spectroscopic imaging as a non-invasive method to characterize not only morphological, but also structural aspects of silkworm silk fibroin-based biomaterials, relying en...

Rice, William L.; Firdous, Shamaraz; Gupta, Sharad; Hunter, Martin; Foo, Cheryl Wong Po; Wang, Yongzhong; Kim, Hyeon Joo; Kaplan, David L.; Georgakoudi, Irene

2008-01-01

196

Effect of initial cell seeding density on 3D-engineered silk fibroin scaffolds for articular cartilage tissue engineering  

OpenAIRE

The repair of articular cartilage defects poses a continuing challenge. Cartilage tissue engineering through the culture of chondrocytes seeded in 3D porous scaffolds has the potential for generating constructs that repair successfully. It also provides a platform to study scaffold-cell and cell-cell interactions. The scaffold affects the growth and morphology of cells growing on it, and concomitantly, cells affect the properties of the resultant tissue construct. Silk fibroin protein from An...

Talukdar, Sarmistha; Nguyen, Quynhhoa T.; Chen, Albert C.; Sah, Robert L.; Kundu, Subhas C.

2011-01-01

197

Composite Scaffolds Containing Silk Fibroin, Gelatin, and Hydroxyapatite for Bone Tissue Regeneration and 3D Cell Culturing  

OpenAIRE

Three-dimensional (3D) silk fibroin scaffolds were modified with one of the major bone tissue derivatives (nano-hydroxyapatite) and/or a collagen derivative (gelatin). Adhesion and proliferation of mouse embryonic fibroblasts (MEF) within the scaffold were increased after modification with either nano-hydroxyapatite or gelatin. However, a significant increase in MEF adhesion and proliferation was observed when both additives were introduced into the scaffold. Such modified c...

Moisenovich, M. M.; Arkhipova, A. Yu; Orlova, A. A.; Drutskaya, M. S.; Volkova, S. V.; Zacharov, S. E.; Agapov, I. I.; Kirpichnikov, M. P.

2014-01-01

198

Relationship between gelatin concentrations in silk fibroin-based composite scaffolds and adhesion and proliferation of mouse embryo fibroblasts.  

Science.gov (United States)

Porous scaffolds of silk fibroin and composite porous scaffolds with 10, 20, 30, 40, and 50% gelatin were made by the freezing-thawing method. The relationship between adhesion and proliferation rate mouse embryo fibroblast and the scaffold composition was studied by laser confocal scanning microscopy. Addition of gelatin to the scaffold structure stimulated adhesion and proliferation of mouse embryo fibroblasts; the optimal content of gelatin was 30%. PMID:25403405

Orlova, A A; Kotlyarova, M S; Lavrenov, V S; Volkova, S V; Arkhipova, A Yu

2014-11-01

199

Modification of Silk Fibroin Using Diazonium Coupling Chemistry and the Effects on hMSC Proliferation and Differentiation  

OpenAIRE

A simple chemical modification method using diazonium coupling chemistry was developed to tailor the structure and hydrophilicity of silk fibroin protein. The extent of modification using several aniline derivatives was characterized using UV/vis and 1H NMR spectroscopy, and the resulting protein structure was analyzed with ATR-FTIR spectroscopy. Introduction of hydrophobic functional groups facilitated rapid conversion of the protein from a random coil to a ?-sheet structure, while addition...

Murphy, Amanda R.; John, Peter St; Kaplan, David L.

2008-01-01

200

Design and Characterization of a Silk-Fibroin-Based Drug Delivery Platform Using Naproxen as a Model Drug  

OpenAIRE

The objective of this proof-of-concept study was to develop a platform for controlled drug delivery based on silk fibroin (SF) and to explore the feasibility of using SF in oral drug delivery. The SF-containing matrixes were prepared via spray-drying and film casting, and the release profile of the model drug naproxen sodium was evaluated. Attenuated total reflectance Fourier transform infrared spectroscopy (FTIR) has been used to observe conformational changes in SF- and drug-containing comp...

Tatyana Dyakonov; Chue Hue Yang; Derek Bush; Saujanya Gosangari; Shingai Majuru; Aqeel Fatmi

2012-01-01

201

Self-assembly of regenerated silk fibroin from random coil nanostructures to antiparallel ?-sheet nanostructures.  

Science.gov (United States)

In this work, we studied the effects of incubation concentration and time on the self-assembly behaviors of regenerated silk fibroin (RSF). Our results showed the assembly ways of RSF were concentration-dependent and there were four self-assembly ways of RSF: (i) At relatively low concentration (?0.015%), RSF molecules assembled into protofilaments (random coil), and then the thickness decreased and the secondary conformation changed to antiparallel ?-sheet; (ii) at the concentration of 0.015%, RSF molecules assembled into protofilaments (random coil), and then assembled into protofibrils (antiparallel ?-sheet). The protofibrils experienced the appearance and disappearance of phase periodic intervals in turn; (iii) at the concentration of 0.03%, RSF molecules assembled into bead-like oligomers (random coil), and then assembled into protofibrils (antiparallel ?-sheet), and finally the height and phase periodic intervals of RSF protofibrils disappeared in turn; and (iv) at the relatively high concentration (?0.15%), RSF molecules assembled into protofilaments (random coil), then aggregated into blurry cuboid-like micelles (random coil), and finally self-arranged to form smooth and clear cuboid-like micelles (antiparallel ?-sheet). These results provide useful insights into the process by which the RSF molecules self-assemble into protofilaments, protofibrils and micelles. Furthermore, our work will be beneficial to basic understanding of the nanoscale structure formations in different silk-based biomaterials. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1181-1192, 2014. PMID:25088327

Zhong, Jian; Ma, Mengjia; Li, Wenying; Zhou, Juan; Yan, Zhiqiang; He, Dannong

2014-12-01

202

Highly flexible and lightweight organic solar cells on biocompatible silk fibroin.  

Science.gov (United States)

Organic electronics have gained widespread attention due to their flexibility, lightness, and low-cost potential. It is attractive due to the possibility of large-scale roll-to-roll processing. However, organic electronics require additional development before they can be made commercially available and fully integrated into everyday life. To achieve feasibility for commercial use, these devices must be biocompatible and flexible while maintaining high performance. In this study, biocompatible silk fibroin (SF) was integrated with a mesh of silver nanowires (AgNWs) to build up flexible organic solar cells with maximum power conversion efficiency of up to 6.62%. The AgNW/SF substrate exhibits a conductivity of ?11.0 ?/sq and transmittance of ?80% in the visible light range. These substrates retained their conductivity, even after being bent and unbent 200 times; this surprising ability was attributed to its embedded structure and the properties of the specific SF materials used. To contrast, indium tin oxide on synthetic plastic substrate lost its conductivity after the much less rigid bending. These lightweight and silk-based organic solar cells pave the way for future biocompatible interfaces between wearable electronics and human skin. PMID:25405590

Liu, Yuqiang; Qi, Ning; Song, Tao; Jia, Mingliang; Xia, Zhouhui; Yuan, Zhongcheng; Yuan, Wei; Zhang, Ke-Qin; Sun, Baoquan

2014-12-10

203

Attachment and growth of human bone marrow derived mesenchymal stem cells on regenerated antheraea pernyi silk fibroin films  

Energy Technology Data Exchange (ETDEWEB)

Silk fibroin of the silkworm Bombyx mori has been studied extensively, while the research on Antheraea pernyi silk fibroin (A. pernyi SF) in biomaterials is only at an early stage. In this study, the attachment, morphology, growth and phenotype of human bone marrow derived mesenchymal stem cells (hBMSCs) cultured on the regenerated A. pernyi SF films were studied in vitro. The results indicated that the attachment of hBMSCs on the regenerated A. pernyi SF films was almost the same as that on the collagen films. MTT and cell counting analyses demonstrated that the growth of hBMSCs on the regenerated A. pernyi SF films was better than that on controls. Moreover, electron scanning microscopy and fluorescence-activated cell sorting assays showed that the regenerated A. pernyi SF supported hBMSCs growth and functional maintenance compared with the controls. These data suggest that the regenerated A. pernyi SF, like Bombyx mori silk fibroin (B. mori SF) and collagen, can support hBMSCs attachment, growth and phenotypic maintenance, and has better biocompatibilities for hBMSCs in vitro culture.

Luan Xiying [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Wang Yong [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Duan Xiang [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Duan Qiaoyan [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Li Mingzhong [School of Materials Engineering, Suzhou University, Suzhou 215006 (China); Lu Shenzhou [School of Materials Engineering, Suzhou University, Suzhou 215006 (China); Zhang Huanxiang [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China); Zhang Xueguang [Institute of Medical Biotechnology, Jiangsu Province Key Laboratory of Stem Cell, Suzhou University, Suzhou 215007 (China)

2006-12-15

204

Attachment and growth of human bone marrow derived mesenchymal stem cells on regenerated antheraea pernyi silk fibroin films  

International Nuclear Information System (INIS)

Silk fibroin of the silkworm Bombyx mori has been studied extensively, while the research on Antheraea pernyi silk fibroin (A. pernyi SF) in biomaterials is only at an early stage. In this study, the attachment, morphology, growth and phenotype of human bone marrow derived mesenchymal stem cells (hBMSCs) cultured on the regenerated A. pernyi SF films were studied in vitro. The results indicated that the attachment of hBMSCs on the regenerated A. pernyi SF films was almost the same as that on the collagen films. MTT and cell counting analyses demonstrated that the growth of hBMSCs on the regenerated A. pernyi SF films was better than that on controls. Moreover, electron scanning microscopy and fluorescence-activated cell sorting assays showed that the regenerated A. pernyi SF supported hBMSCs growth and functional maintenance compared with the controls. These data suggest that the regenerated A. pernyi SF, like Bombyx mori silk fibroin (B. mori SF) and collagen, can support hBMSCs attachment, growth and phenotypic maintenance, and has better biocompatibilities for hBMSCs in vitro culture

205

Immobilized Lentivirus Vector on Chondroitin Sulfate-Hyaluronate Acid-Silk Fibroin Hybrid Scaffold for Tissue-Engineered Ligament-Bone Junction  

OpenAIRE

The lack of a fibrocartilage layer between graft and bone remains the leading cause of graft failure after anterior cruciate ligament (ACL) reconstruction. The objective of this study was to develop a gene-modified silk cable-reinforced chondroitin sulfate-hyaluronate acid-silk fibroin (CHS) hybrid scaffold for reconstructing the fibrocartilage layer. The scaffold was fabricated by lyophilizing the CHS mixture with braided silk cables. The scanning electronic microscopy (SEM) showed that micr...

Liguo Sun; Hongguo Li; Ling Qu; Rui Zhu; Xiangli Fan; Yingsen Xue; Zhenghong Xie; Hongbin Fan

2014-01-01

206

An emerging functional natural silk biomaterial from the only domesticated non-mulberry silkworm Samia ricini.  

Science.gov (United States)

Mulberry silk fibroin is a widely used biomaterial and recent work on non-mulberry silk fibroin also suggests it may have similar uses. We expect silk fibroin from the only domesticated non-mulberry eri silkworm, Samia ricini, to possess useful properties as a biomaterial. Eri silk gland fibroin is a heterodimeric protein of approximately 450?kDa. Cytocompatibility evaluation with fibroblasts and osteoblast-like cells shows good cell attachment, viability and proliferation. The matrices, which have high thermal stability and good swellability, are also haemocompatible. Eri silk production is cost effective as no agronomic practices are required for their host plant cultivation. This fibroin provide new opportunities as an alternative natural functional biomaterial in various biomedical applications. PMID:23733347

Pal, Shilpa; Kundu, Joydip; Talukdar, Sarmistha; Thomas, Tintu; Kundu, Subhas C

2013-08-01

207

Comparison of the in vitro and in vivo degradations of silk fibroin scaffolds from mulberry and nonmulberry silkworms.  

Science.gov (United States)

Degradation behavior is very important in the field of silk-based biomaterials. Mulberry and nonmulberry silk fibroins are structurally and functionally distinguishable; however, no studies have examined the differences in the degradation behaviors of silk materials from various silkworm species. In this study, Ca(NO3)2 was used as a uniform solvent to obtain regenerated mulberry and nonmulberry (Antheraea pernyi and Antheraea yamamai) silk fibroin (SF) solutions, and the degradation behaviors of various SF scaffolds were examined. In vitro and in vivo results demonstrated that regenerated mulberry SF scaffolds exhibited significantly higher mass loss and free amino acid content release than did nonmulberry SF scaffolds. The differences in the primary structures and condensed structures between mulberry and nonmulberry SF contributed to the significant difference in degradation rates, in which the characteristic (-Ala-)n repeats, compact crystal structure and high ?-helix and ?-sheet contents make nonmulberry SF more resistant than mulberry SF to enzymatic degradation. Moreover, the Antheraea pernyi and Antheraea yamamai SFs possess similar primary structures and condensed structures, although a slight difference in degradation was observed; this difference might depend on the differences in molecular weight following the regeneration process. The results indicate that the original sources of SF significantly influence the degradation rates of SF-based materials; therefore, the original sources of SF should be fully considered for preparing tissue engineering scaffolds with matched degradation rates. PMID:25532470

You, Renchuan; Xu, Yamei; Liu, Yi; Li, Xiufang; Li, Mingzhong

2015-02-01

208

Incorporation of Exogenous RGD Peptide and Inter-Species Blending as Strategies for Enhancing Human Corneal Limbal Epithelial Cell Growth on Bombyx mori Silk Fibroin Membranes  

OpenAIRE

While fibroin isolated from the cocoons of domesticated silkworm Bombyx mori supports growth of human corneal limbal epithelial (HLE) cells, the mechanism of cell attachment remains unclear. In the present study we sought to enhance the attachment of HLE cells to membranes of Bombyx mori silk fibroin (BMSF) through surface functionalization with an arginine-glycine-aspartic acid (RGD)-containing peptide. Moreover, we have examined the response of HLE cells to BMSF when blended with the fibroi...

Chirila, Traian V.; Bray, Laura J.; Shuko Suzuki; Harkin, Damien G.

2013-01-01

209

Preparation and characterization of blends containing silk fibroin and chitosan;Obtencao e caracterizacao de blendas de fibroina de seda e quitosana  

Energy Technology Data Exchange (ETDEWEB)

The aim of this study was to prepare and characterize blend membranes of silk fibroin and chitosan. Moreover, a conformation of fibroin to a more stable form induced by the addition of chitosan was verified. Blend membranes of fibroin/chitosan were prepared in different proportions and had their crystallinity, structural conformation and thermal stability characterized. The results of crystallographic analysis (XRD) indicated the tendency to higher structural organization caused by the addition of chitosan. FTIR showed that, mainly in a content of chitosan of only 25%, fibroin is present in a more stable form. Thermal analyzes indicate that fibroin is thermally stable and that when its proportion in the blend increases, the temperature in which the degradation is initiated also does so. (author)

Moraes, Mariana A. de; Nogueira, Grinia M.; Weska, Raquel F.; Beppu, Marisa M., E-mail: beppu@feq.unicamp.b [Universidade Estadual de Campinas (FEQ/UNICAMP), SP (Brazil). Faculdade de Engenharia Quimica

2009-07-01

210

Silk fibroin microparticles as carriers for delivery of human recombinant bone morphogenetic protein-2: in vitro and in vivo bioactivity.  

Science.gov (United States)

The in vitro and in vivo efficiency of fibroin microparticles as a delivery carrier for bone morphogenetic protein-2 (BMP-2) was evaluated. BMP-2 was encapsulated in silk fibroin particles that were produced by a simple and very mild processing method. The dose-response of BMP-2-loaded fibroin particles was examined in C2C12 cells, after 5 days of culture. The BMP-2 retained most of its activity as observed by the increase in alkaline phosphatase activity, which was much higher when BMP-2 was encapsulated into the particles rather than just surface-adsorbed. After 2 weeks of culture, increased mineralization was observed with BMP-2-loaded particles in comparison to soluble added growth factor. No significant cytotoxicity was detected. When implanted in a rat ectopic model, bone formation was observed by in vivo micro-computed tomography after 2 and 4 weeks postimplantation, with particles loaded with 5 or 12.5?microg BMP-2. An increase in bone density was observed over time. Histology revealed further evidence of ectopic bone formation, observed by strong alizarin red staining and osteocalcin immunostaining. Our findings show that fibroin microparticles may present an interesting option for future clinical applications in the bone tissue engineering field, and therefore, further studies have been planned. PMID:19958078

Bessa, Paulo César; Balmayor, Elizabeth R; Hartinger, Joachim; Zanoni, Gerald; Dopler, Daniela; Meinl, Alexandra; Banerjee, Asmita; Casal, Margarida; Redl, Heinz; Reis, Rui L; van Griensven, Martijn

2010-10-01

211

The cultivation of human retinal pigment epithelial cells on Bombyx mori silk fibroin.  

Science.gov (United States)

We have presently evaluated membranes prepared from Bombyx mori silk fibroin (BMSF), for their potential use as a prosthetic Bruch's membrane and carrier substrate for human retinal pigment epithelial (RPE) cell transplantation. Porous BMSF membranes measuring 3 ?m in thickness were prepared from aqueous solutions (3% w/v) containing poly(ethylene oxide) (0.09%). The permeability coefficient for membranes was between 3 and 9 × 10(-5) cm/s by using Allura red or 70 kDa FITC-dextran respectively. Average pore size (±sd) was 4.9 ± 2.3 ?m and 2.9 ± 1.5 ?m for upper and lower membrane surfaces respectively. Optimal attachment of ARPE-19 cells to BMSF membrane was achieved by pre-coating with vitronectin (1 ?g/mL). ARPE-19 cultures maintained in low serum on BMSF membranes for approximately 8 weeks, developed a cobble-stoned morphology accompanied by a cortical distribution of F-actin and ZO-1. Similar results were obtained using primary cultures of human RPE cells, but cultures took noticeably longer to establish on BMSF compared with tissue culture plastic. These findings encourage further studies of BMSF as a substrate for RPE cell transplantation. PMID:22406408

Shadforth, Audra M A; George, Karina A; Kwan, Anthony S; Chirila, Traian V; Harkin, Damien G

2012-06-01

212

Response of filopodia and lamellipodia to surface topography on micropatterned silk fibroin films.  

Science.gov (United States)

Cell-microstructure surface interactions play a significant role in tissue engineering to guide cell spreading and migration. However, the mechanisms underlying cell-topography interactions are complex and remain elusive. To address this topic, microsphere array patterns were prepared on silk fibroin films through polystyrene microsphere self-assembly, followed by culturing rat bone marrow derived mesenchymal stem cells on the films to study cell-substrate interactions. Filopodia sensed and anchored to the microspheres to form initial attachments before spreading. Importantly, the anchored filopodia converted into lamellipodia, and this conversion initiated the directional formation of lamellipodia. Therefore, the conversion of exploratory filopodia into lamellipodia was the main driving force for directional extension of the lamellipodia. Correspondingly, cell spreading, morphology, and migration were modulated by pseudopodial recognition and conversion. This finding demonstrated that filopodia not only act as an antenna to detect microenvironment but also serve as skeleton to guide lamellipodial extension for directing cell motions. The micropatterned films promoted cell adhesion and proliferation due to accelerated lamellipodia formation and cell spreading, with recognition and conversion of filopodia into lamellipodia as a critical role in cell response to surface topography. PMID:24464986

You, Renchuan; Li, Xiufang; Liu, Yu; Liu, Guiyang; Lu, Shenzhou; Li, Mingzhong

2014-12-01

213

Morphology and thermal stability of silk fibroin/starch blended microparticles  

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Full Text Available In the present study biodegradable microparticles of silk fibroin (SF/starch blends were prepared by a simple water-in-oil emulsion solvent diffusion technique. SF/starch blended solution and ethyl acetate were used as water and oil phases, respectively. The influence of SF/starch ratios on characteristics of the blended microparticles was investigated. The SF conformation of microparticle matrices from FTIR analysis was changed from random coil to ?-sheet form by blending with starch. The blended microparticles had lower dissolution in water than those of SF and starch microparticles. The 1/3 (w/w SF/starch blended microparticles exhibited the lowest dissolution. The SF and starch microparticles showed irregular and deflated shapes, respectively. The blended microparticles were nearly spherical in shapes and smaller sizes. Thermal stability of the blended microparticles slightly increased with the starch blended ratio. The results suggested that SF conformational transition, thermal stability, morphology and dissolution of the blended microparticles can be adjusted by varying the blended ratio.

2010-12-01

214

Silk fibroin based biomimetic artificial extracellular matrix for hepatic tissue engineering applications  

International Nuclear Information System (INIS)

Hepatic tissue engineering, which aims to construct artificial liver tissues, requires a suitable extracellular matrix (ECM) for growth and proliferation of metabolically active hepatocytes. The current paper describes the development of a biomimetic artificial ECM, for hepatic tissue engineering applications, by mimicking the architectural features and biochemical composition of native ECM. Electrospinning was chosen as the fabrication technique of choice, while regenerated silk fibroin (RSF) and galactosylated chitosan (GalCS) were chosen as materials of choice. Poly(ethylene oxide) was used as a processing aid. Methodical optimization studies were performed to obtain smooth and continuous nanofibers with homogenous size distribution. Extensive characterization studies were performed to determine its morphological, physical, chemical/structural, thermal and cytotoxicity properties. Subsequently, detailed in vitro hepatocyte compatibility studies were performed using HepG2 cell line. Remarkably, the studies revealed that the growth, viability, metabolic activity and proliferation of hepatocytes were relatively superior on RSF–GalCS scaffold than on pure RSF and pure GalCS. In summary, the electrospun nanofibrous RSF–GalCS scaffold tries to mimic both architectural and biochemical features of native ECM, and hence could be an appropriate scaffold for in vitro engineering of hepatic tissue. However, additional experiments are needed to confirm the superiority in cheeded to confirm the superiority in characteristic functionality of hepatocytes growing on RSF–GalCS scaffold in relation to RSF and GalCS scaffolds, and to test its behavior in vivo. (paper)

215

Elimination of large particulate units from silk fibroin PLD films by post-treatments  

International Nuclear Information System (INIS)

After depositing silk fibroin (SF) thin films by pulsed IR-laser deposition, extraordinarily large particulate units up to several micrometers were observed. They include debris from the target and severely agglomerated protein units. Occurrence of those large particles was found to be minimum on the vertical substrate. We tried to eliminate large particulate units by two post-treatment operations, i.e. dry gaseous blow-off (GBO) and rinsing in water under simultaneous ultrasonication (WSU). Change in the surface structure by these post-treatments was observed by optical and electron microscopes with varying area from 1mm square down to 1?m square. GBO turned out to be suitable to eliminate the lightly attached particulates of 1-10?m, mostly those pulled out from the target while preserving morphological and chemical properties of smallest units underneath. WSU, on the other hand, pelt off more strongly attached surface irregularities. However, morphological change with an increase in the surface roughness in the range of 1nm was also observed after WSU. The latter might be associated with possible sonochemical effects

216

Electrospun scaffolds of silk fibroin and poly(lactide-co-glycolide) for endothelial cell growth.  

Science.gov (United States)

Electrospun scaffolds of silk fibroin (SF) and poly(lactide-co-glycolide) (PLGA) were prepared to mimic the morphology and chemistry of the extracellular matrix. The SF/PLGA scaffolds were treated with ethanol to improve their usability. After ethanol treatment the scaffolds exhibited a smooth surface and uniform fibers. SF transformed from random coil conformation to ?-sheet structure after ethanol treatment, so that the SF/PLGA scaffolds showed low hydrophilicity and dissolving rate in water. The mechanical properties and the hydrophilicity of the blended fibrous scaffolds were affected by the weight ratio of SF and PLGA. During degradation of ethanol-treated SF/PLGA scaffolds in vitro, the fibers became thin along with the degradation time. Human umbilical vein endothelial cells (HUVECs) were seeded onto the ethanol-treated nanofibrous scaffolds for cell viability, attachment and morphogenesis studies. These SF/PLGA scaffolds could enhance the viability, spreading and attachment of HUVECs. Based on these results, these ethanol-treated scaffolds are proposed to be a good candidate for endothelial cell growth. PMID:25601671

Zhou, Wei; Feng, Yakai; Yang, Jing; Fan, Jiaxu; Lv, Juan; Zhang, Li; Guo, Jintang; Ren, Xiangkui; Zhang, Wencheng

2015-01-01

217

In vitro Degradation Behavior of Bombyx mori Silk Fibroin Films Exposure to Protease XXIII  

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Full Text Available Proteolytic activity of protease XXIII on Silk Fibroin (SF films was studied. The films were prepared from the SF solution by casting on the polystyrene plates and used as substrate for enzymatic degradation. The SF films were incubated with 1.0 mg mL-1 protease XXIII at 37°C up to 21 days. After incubation, those of secondary structure and thermal behavior of the SF films were investigated. FT-IR spectra indicated that the SF films predominantly ?-structure. There was found that secondary structure of the films did not change even at 21 days of incubation times. However, slightly decreased of FTIR spectra were also observed by shoulder absorption peaks. The result suggested that some crystalline regions might be digested by the enzyme. This related to the thermal stability from thermogravimetric analysis since the SF films gradually decreased their thermal stability followed the increasing of time exposure to protease XXIII. It is a promising that protease XXIII could be digested SF and will be used this enzyme as a model system for enzymatic study on SF.

K. Nuanchai

2009-01-01

218

Elimination of large particulate units from silk fibroin PLD films by post-treatments  

Energy Technology Data Exchange (ETDEWEB)

After depositing silk fibroin (SF) thin films by pulsed IR-laser deposition, extraordinarily large particulate units up to several micrometers were observed. They include debris from the target and severely agglomerated protein units. Occurrence of those large particles was found to be minimum on the vertical substrate. We tried to eliminate large particulate units by two post-treatment operations, i.e. dry gaseous blow-off (GBO) and rinsing in water under simultaneous ultrasonication (WSU). Change in the surface structure by these post-treatments was observed by optical and electron microscopes with varying area from 1mm square down to 1{mu}m square. GBO turned out to be suitable to eliminate the lightly attached particulates of 1-10{mu}m, mostly those pulled out from the target while preserving morphological and chemical properties of smallest units underneath. WSU, on the other hand, pelt off more strongly attached surface irregularities. However, morphological change with an increase in the surface roughness in the range of 1nm was also observed after WSU. The latter might be associated with possible sonochemical effects.

Nakayama, S [Technofarm Axesz Co., Ltd., 4-4-27-703 Aobadai, Meguro, Tokyo 153-0042 (Japan); Senna, M [Technofarm Axesz Co., Ltd., 4-4-27-703 Aobadai, Meguro, Tokyo 153-0042 (Japan)

2007-04-15

219

A Moldable Putty Containing Silk Fibroin Yolk Shell Particles for Improved Hemostasis and Bone Repair.  

Science.gov (United States)

During minimally invasive orthopedic surgeries, surgical intervention is required at two stages; to attain hemostasis and subsequently to implant the bone graft or its substitute. There is an apparent need for a material which can simultaneously control bone bleeding and provide support for bone repair. In this work, a moldable putty, which can be applied to bone defects (usually irregular in shape), was developed to address this need. It comprises of a hemostatic factor thrombin, osteoinductive "yolk-shell" particles containing bone growth factor (BMP-2), and an osteoconductive component hydroxyapatite. The yolk shell particles allowed controlled release of BMP-2 and showed significantly enhanced osteogenic differentiation of C2C12 (mouse myoblast) cells as demonstrated by increased alkaline phosphatase (ALP) activity and relative gene expressions of osteogenic differentiation markers. These particles were assembled into a moldable putty by mixing them with hydroxyapatite and silk fibroin solution (binding agent) supplemented with thrombin. The putty showed non-cytotoxicity, hemostatic ability, sustained release of BMP-2 and induced increased mineralization in C2C12 cells. This putty, if applied to bone defects during surgeries, may help attain hemostasis and may enhance bone repair by providing sustained release of bone growth factors. PMID:25296961

Saran, Kushagra; Shi, Pujiang; Ranjan, Shashi; Goh, James C H; Zhang, Yong

2014-10-01

220

Effect of polyaspartic acid on hydroxyapatite deposition in silk fibroin blend films  

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Full Text Available Polyaspartic acid/silk fibroin/hydroxyapatite (PASP/SF-HA composites have been synthesized by biomimetic processing. SF solution was mixed with different contents of PASP to prepare the PASP/SF blend membranes. After ethanol treatment and premineralization process, the blend membranes were immersed into 1.5 simulated body fluid (1.5 SBF for 24 h to induce apatite deposition at 37±0.5°C. Fourier transform infrared spectroscopy (FTIR and X-ray diffraction (XRD results revealed that a conformation transition of SF occurred after the addition of PASP and ethanol treatment. The FTIR and XRD results also confirmed that the main component of apatite deposition was HA. Scanning electron microscopy (SEM showed that the content of HA increased with increasing PASP concentration .Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP results revealed that the Ca/P molar ratio could reach 1.45, which was close to the Ca/P ratio of apatite. It was appropriate to conclude that the increasing content of PASP had a distinct effect on HA deposition in the blend films.

2010-05-01

221

Effect of silk fibroin nanofibers containing silver sulfadiazine on wound healing  

Science.gov (United States)

Background One of the promising applications of silk fibroin (SF) in biomedical engineering is its use as a scaffolding material for skin regeneration. The purpose of this study was to determine the wound healing effect of SF nanofibrous matrices containing silver sulfadiazine (SSD) wound dressings. Methods An SF nanofibrous matrix containing SSD was prepared by electrospinning. The cell attachment and spreading of normal human epidermal keratinocytes (NHEK) and normal human epidermal fibroblasts (NHEF) to SF nanofibers containing three different concentrations of SSD contents (0.1, 0.5, and 1.0 wt%) were determined. In addition, a rat wound model was used in this study to determine the wound healing effect of SF nanofibers containing SSD compared with that of Acticoat™, a commercially available wound dressing. Results The number of NHEK and NHEF attached to SF nanofibers containing SSD decreased when the concentration of SSD increased. The number of attached NHEF cells was lower than that of attached NHEK cells. The SF matrix with 1.0 wt% SSD produced faster wound healing than Acticoat, although 1.0 wt% SSD inhibited the attachment of epidermal cells to SF nanofibers in vitro. Conclusion The cytotoxic effects of SF nanofibers with SSD should be considered in the development of silver-release dressings for wound healing through its antimicrobial activity. It is challenging to design wound dressings that maximize antimicrobial activity and minimize cellular toxicity. PMID:25484581

Jeong, Lim; Kim, Min Hee; Jung, Ju-Young; Min, Byung Moo; Park, Won Ho

2014-01-01

222

Silk Fibroin/Gelatin Hybrid Films for Medical Applications: Study on Chlorhexidine Diacetate  

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Full Text Available This study aimed to prepare silk fibroin (SF/gelatin (G hybrid films by a solvent evaporation method for loading chlorhexidine diacetate (CHX. The SF and G solution in different ratios were mixed with CHX and placed on the 5 cm polystyrene plates before drying to obtain hybrid films. The films were determined their secondary structures and thermal properties by using Fourier transform infrared (FT-IR spectrometer and thermogravimetric analysis (TGA, respectively. The results found that all of film composed of ?-helix and ?-sheet structures. However, differences of the ?-helix and ?-sheet structures were differed according to each component. The hybrid films showed soft texture and decreased of brittle compared to SF film only when the G content increased. Thermal properties of the films indicated that decomposition temperature profiles of all films did not differ dramatically, however, combination of characteristics both SF and G were appeared in hybrid films. The releasing rate of CHX-loaded in the films was found that the CHX has released from the SF film in higher rate than hybrid and G films, respectively. It is a promising that polarity, flexibility as well as component ratio of each polymer play important role on the releasing of CHX.

Baimark Yodthong

2010-01-01

223

Functional recovery guided by an electrospun silk fibroin conduit after sciatic nerve injury in rats.  

Science.gov (United States)

The aim of this study was to evaluate the regenerative capacity of a newly developed nerve guidance conduit using electrospun silk fibroin (SFNC) implanted in a 10-mm defect of the sciatic nerve in rats. After evaluating the physical properties and cytocompatibility of SFNC in vitro, rats were randomly allocated into three groups: defect only, autograft and SFNC. To compare motor function and abnormal sensation among groups, ankle stance angle (ASA) and severity of autotomy were observed for 10?weeks after injury. Immunostaining with axonal neurofilament (NF) and myelin basic protein (MBP) antibodies were performed to investigate regenerated nerve fibres inside SFNC. ASA increased significantly in the SFNC group at 1, 7 and 10?weeks after injury compared to the defect only group (p?

Park, Sook Young; Ki, Chang Seok; Park, Young Hwan; Lee, Kwang Gill; Kang, Seok Woo; Kweon, Hae Yong; Kim, Hyun Jeong

2015-01-01

224

Tip-induced micropatterning of silk fibroin protein using in situ solution atomic force microscopy.  

Science.gov (United States)

Silk fibroin (SF) is a promising candidate for a variety of application in the fields of tissue engineering, drug delivery, and biomedical optics. Recent research has already begun to explore the construction of nano- and micropatterned SF films under ambient environment. The structure and biocompatibility of SF are dependent on SF state (solution or solid) and the method of drying the SF solution to prepare various biomaterials such as films, sponges, and fibers. Therefore, it is important to explore the construction of SF nano- and micropatterns under aqueous solution. This paper reports a novel application of atomic force microscopy (AFM) under liquid for direct deposition of the relatively hydrophobic protein SF onto hydrophilic mica. We demonstrate that the AFM tip, in either the contact or the tapping mode, can fabricate SF micropatterns on mica with controlled surface topography. We show that the deposition process requires a mechanical force-induced SF sol-gel transition followed by a transfer to the mica surface at the tip-surface contact, and the efficiency of this process depends on not only AFM operation mode but also the SF bulk concentration, the SF amount on mica, and the AFM tip spring constant. PMID:23276203

Zhong, Jian; Ma, Mengjia; Zhou, Juan; Wei, Daixu; Yan, Zhiqiang; He, Dannong

2013-02-01

225

Fabrication and characterization of curcumin-loaded silk fibroin/P(LLA-CL) nanofibrous scaffold  

Science.gov (United States)

Curcumin exhibited excellent properties including antioxidant, antiinflammatory, antiviral, antibacterial, antifungal, anticancer, and anticoagulant activities. In this study, curcumin was incorporated into silk fibroin (SF)/poly(L-lactic acid- co-e-caprolactone) (P(LLA-CL)) nanofibrous scaffolds via electrospinning, and changes brought about by raising the curcumin content were observed: SEM images showed that the average nanofibrous diameter decreased at the beginning and then increased, and the nanofibers became uniform; FTIR showed that the conformation of SF transforming from random coil form to ?-sheet structure had not been induced, while SF conformation converted to ?-sheet after being treated with 75% ethanol vapor; XRD results confirmed that the crystal structure of (P(LLA-CL)) had been destroyed; The mechanical test illustrated that nanofibrous scaffolds still maintained good mechanical properties. Further, curcumin-loaded nanofibrous scaffolds were evaluated for drug release, antioxidant and antimicrobial activities in vitro. The results showed that curcumin presented a sustained release behavior from nanofibrous scaffolds and maintained its free radical scavenging ability, and such scaffolds could effectively inhibit S. aureus growth (> 95%). Thus, curcumin-loaded SF/P(LLA-CL) nanofibrous scaffolds might be potential candidates for wound dressing and tissue engineering scaffolds.

Lian, Yuan; Zhan, Jian-Chao; Zhang, Kui-Hua; Mo, Xiu-Mei

2014-12-01

226

Effect of fetal bovine serum on mineralization in silk fibroin scaffolds.  

Science.gov (United States)

Fetal bovine serum (FBS) is a common media supplement used in tissue engineering (TE) cultures. The chemical composition of FBS is known to be highly variable between different brands, types or batches and can have a significant impact on cell function. This study investigated the influence of four different FBS types in osteogenic or control medium on mineralization of acellular and cell-seeded silk fibroin (SF) scaffolds. In bone TE, mineralized tissue is considered as the final product of a successful cell culture. Calcium assays and micro-computed tomography scans revealed spontaneous mineralization on SF scaffolds with certain FBS types, even without cells present. In contrast, cell-mediated mineralization was found under osteogenic conditions only. Fourier transform infrared spectroscopy analysis demonstrated a similar ion composition of the mineralization present in scaffolds, whether cell-mediated or spontaneous. These results were confirmed by scanning electron microscopy. This study shows clear evidence for the influence of FBS type on mineralization on SF scaffolds. The suitability of FBS medium supplementation in TE studies is highly questionable with regard to reproducibility of studies and comparability of obtained results. For future TE studies, alternatives to conventional FBS such as defined FBS or serum-free media should be considered, as suggested decades ago. PMID:25463486

Vetsch, Jolanda R; Paulsen, Samantha J; Müller, Ralph; Hofmann, Sandra

2015-02-01

227

Direct electrochemistry and electrocatalysis of heme-proteins in regenerated silk fibroin film  

International Nuclear Information System (INIS)

A biocompatible silk fibroin (SF) film provided a feasible microenvironment for heme-proteins to direct electron transfer on graphite electrodes (GE). Myoglobin (Mb), hemoglobin (Hb), horseradish peroxidase (HRP), and catalase (Cat) incorporated in SF films exhibited a pair of well-defined, nearly reversible cyclic voltammetric peaks, corresponding to the reaction of hemeFe (III) + e ? hemeFe (II). The formal potential (E 0), the apparent coverage (?) and the electron transfer rate constant (k s) of four proteins in SF films were evaluated by analyzing the cyclic voltammograms (CVs) of heme-proteins. The formal potential was pH dependent, suggesting that proton ion was involved in the reaction. Ultraviolet visible (UV-vis) spectra and reflectance absorbance infrared (RAIR) spectra indicated that heme-proteins in SF films were not grossly denatured. The structure of heme-proteins-SF films was investigated using scanning electron microscopy (SEM) and RAIR. It indicated that there existed intermolecular interaction between heme-proteins and SF and this governed their different morphology in SF films. Hydrogen peroxide and nitric oxide were catalytically reduced by the heme-proteins in SF films, showing the potential applicability of the heme-proteins-SF films as the new type of biosensors based on the protein film voltammetry

228

Direct electrochemistry and electrocatalysis of heme-proteins in regenerated silk fibroin film  

Energy Technology Data Exchange (ETDEWEB)

A biocompatible silk fibroin (SF) film provided a feasible microenvironment for heme-proteins to direct electron transfer on graphite electrodes (GE). Myoglobin (Mb), hemoglobin (Hb), horseradish peroxidase (HRP), and catalase (Cat) incorporated in SF films exhibited a pair of well-defined, nearly reversible cyclic voltammetric peaks, corresponding to the reaction of hemeFe (III) + e {sup {yields}} hemeFe (II). The formal potential (E {sup 0}), the apparent coverage ({gamma}) and the electron transfer rate constant (k {sub s}) of four proteins in SF films were evaluated by analyzing the cyclic voltammograms (CVs) of heme-proteins. The formal potential was pH dependent, suggesting that proton ion was involved in the reaction. Ultraviolet visible (UV-vis) spectra and reflectance absorbance infrared (RAIR) spectra indicated that heme-proteins in SF films were not grossly denatured. The structure of heme-proteins-SF films was investigated using scanning electron microscopy (SEM) and RAIR. It indicated that there existed intermolecular interaction between heme-proteins and SF and this governed their different morphology in SF films. Hydrogen peroxide and nitric oxide were catalytically reduced by the heme-proteins in SF films, showing the potential applicability of the heme-proteins-SF films as the new type of biosensors based on the protein film voltammetry.

Wu Yunhua [Department of Chemistry, Wuhan University, Wuhan 430072 (China); State Key Laboratories of Transducer Technology, Chinese Academy of Sciences, Beijing 100080 (China); Shen Qiuchan [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Hu Shengshui [Department of Chemistry, Wuhan University, Wuhan 430072 (China) and State Key Laboratories of Transducer Technology, Chinese Academy of Sciences, Beijing 100080 (China)]. E-mail: sshu@whu.edu.cn

2006-02-03

229

Fabrication and neuron cytocompatibility of iron oxide nanoparticles coated with silk-fibroin peptides.  

Science.gov (United States)

Neuro-cytotoxicity of iron oxide nanoparticles (NPs) need to be considered. In this paper, magnetic Fe3O4 NPs are synthesized via a bio-mineralization process using silk fibroin (SF) as template. The prepared NPs with SF (SF-NPs) have more uniform grain size, better stability in weakly alkaline solution and higher saturation magnetization (about 82 emu/g) than pure NPs. After exposure to different concentration of SF-NPs (6.25-100 ?g/mL), the reactive oxygen species generation in PC12 cells reduced compared with pure NPs. 1-5d treatment with SF-NPs did not destroy cell membrane and cyto-skeleton, and could improve the neurites extension in a dose-dependent manner at lower concentration (6.25-50 ?g/mL), because SF peptide coating could delay the release of iron ions and the increase of surface crystal defects of NPs. Intact mitochondria in a neurite indicate the extension activity of neurites of cells treated with SF-NPs. Their high magnetic property and good neural-cytocompatibility provide the possibility of SF-NPs to be used as the contrast agents in brain MRI or the carrier of neural therapeutic drugs. PMID:24552663

Deng, Min; Huang, Zhongbing; Zou, Yuanwen; Yin, Guangfu; Liu, Juan; Gu, Jianwen

2014-04-01

230

Study of synthesis of nano-hydroxyapatite using a silk fibroin template  

International Nuclear Information System (INIS)

Nano-hydroxyapatite (HA) was directly synthesized on a silk fibroin (SF) template using the property of SF being soluable in a concentrated CaCl2 solution as a HA source of calcium at pH 7.4 and room temperature. The microstructure and bonding state were investigated by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry-thermogravimetry analysis (DSC-TG) and transmission electron microscopy (TEM). The results indicated that the HA crystals were poorly crystallized with a rod-like shape of 20-60 nm length and 10-20 nm diameter. Strong molecular interactions and chemical bonds might be present between SF and HA. There were other nucleation sites such as carbonyl (-C-O) and amine (-N-H-) groups on SF molecules besides the carboxyl (-COOH) and hydroxyl (-OH) groups previously reported. During the formation of HA, the coordination action between specific functional groups on SF and calcium ions (Ca2+) played an important role. The crystallinity of HA was improved and had an orientation growth along (0 0 2) at the presence of SF, resulting in a structure similar to natural bone. It was concluded that SF could regulate the structure and morphology of HA effectively. (communication)

231

Electrospun silk fibroin nanofibers in different diameters support neurite outgrowth and promote astrocyte migration.  

Science.gov (United States)

Nerve tissue engineering has been one of the promising strategies for regenerative treatment in patients suffering from neural tissue loss, but considerable challenges remain before it is able to progress toward clinical application. It has been demonstrated that transplantation of cells in combination with physically or chemically modified biomaterials provides better environments for neurite outgrowth and further promotes axonal regeneration in animal models of spinal cord injury. In this study, neurons and astrocytes were incorporated into 400-nm, 800-nm, and 1200-nm electrospun Bombyx mori silk fibroin (SF) materials to investigate the effects of scaffold-diameter in regulating and directing cell behaviors. ?-III-tubulin immunofluorescence analyses reveal that SF nanofibers with smaller diameters are more favorable to the development and maturation of subventricular zone-derived neurons than 1200-nm SF scaffolds. In addition, astrocytes exhibited well-arranged glial fibrillary acidic protein (GFAP) expression on SF scaffolds, and a significant increase in cell-spreading area was observed on 400-nm but not 1200-nm SF scaffolds. Moreover, a significantly enhanced migration efficiency of astrocytes grown on SF scaffolds was verified, which highlights the guiding roles of SF nanofibers to the migratory cells. Overall, our results may provide valuable information to develop effective tissue remodeling substrates and to optimize existing biomaterials for neural tissue engineering applications. PMID:23427060

Qu, Jing; Wang, Dan; Wang, Huihui; Dong, Yunhai; Zhang, Feng; Zuo, Baoqi; Zhang, Huanxiang

2013-09-01

232

Fabrication and characterization of bioactive silk fibroin/wollastonite composite scaffolds  

Energy Technology Data Exchange (ETDEWEB)

Composite scaffolds of silk fibroin (SF) with bioactive wollastonite were prepared by freeze-drying. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy analysis showed that random coil and {beta}-sheet structure co-existed in the SF scaffold. The mechanical performance, surface hydrophilicity and water-uptake capacity of the composite scaffolds were improved compared with those of pure SF scaffold. The bioactivity of the composite scaffold was evaluated by soaking in a simulated body fluid (SBF), and formation of a hydroxycarbonate apatite (HCA) layer was determined by FT-IR and XRD. The results showed that the SF/wollastonite composite scaffold was bioactive as it induced the formation of HCA on the surface of the composite scaffold after soaking in SBF for 5 days. In vitro cell attachment and proliferation tests showed that the composite scaffold was a good matrix for the growth of L929 mouse fibroblast cells. Consequently, the incorporation of wollastonite into the SF scaffold can enhance both the mechanical strength and bioactivity of the scaffold, which suggests that the SF/wollastonite composite scaffold may be a potential biomaterial for tissue engineering.

Zhu Hailin [Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Xiasha Higher Education Zone, Zhejiang Sci-Tech University, Hangzhou, 310018 (China); Department of Chemistry, Xiasha Higher Education Zone, Zhejiang Sci-Tech University, Hangzhou, 310018 (China); Shen Jinyu; Feng Xinxing; Zhang Huapeng; Guo Yuhai [Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Xiasha Higher Education Zone, Zhejiang Sci-Tech University, Hangzhou, 310018 (China); Chen Jianyong, E-mail: cjy@zstu.edu.cn [Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Xiasha Higher Education Zone, Zhejiang Sci-Tech University, Hangzhou, 310018 (China)

2010-01-01

233

Preparation of electrospun silk fibroin fiber mats as bone scaffolds: a preliminary study  

International Nuclear Information System (INIS)

In the present contribution, electrospinning (e-spinning) was used to fabricate ultra-fine fibers of silk fibroin (SF) from cocoons of indigenous Thai silkworms (Nang-Lai) and Chinese/Japanese hybrid silkworms (DOAE-7). The effects of solution concentration (i.e., 10-40% (w/v) in 85% (v/v) formic acid) and applied electrostatic field strength (EFS; 10, 15 and 20 kV/10 cm) on morphology and size of the electrospun (e-spun) SF products were investigated by scanning electron microscopy. The average diameter of the resulting e-spun SF fibers was found to increase with an increase in both the solution concentration and the EFS value. Specifically, the average diameter of the e-spun SF fibers from Nang-Lai SF solutions ranged between 217 and 610 nm, while that of the fibers from DOAE-7 SF solutions ranged between 183 and 810 nm. The potential for use of the e-spun SF fiber mats as bone scaffolds was assessed with mouse osteoblast-like cells (MC3T3-E1) in which the cells appeared to adhere and proliferate well on their surface

234

Study of synthesis of nano-hydroxyapatite using a silk fibroin template  

Energy Technology Data Exchange (ETDEWEB)

Nano-hydroxyapatite (HA) was directly synthesized on a silk fibroin (SF) template using the property of SF being soluable in a concentrated CaCl{sub 2} solution as a HA source of calcium at pH 7.4 and room temperature. The microstructure and bonding state were investigated by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry-thermogravimetry analysis (DSC-TG) and transmission electron microscopy (TEM). The results indicated that the HA crystals were poorly crystallized with a rod-like shape of 20-60 nm length and 10-20 nm diameter. Strong molecular interactions and chemical bonds might be present between SF and HA. There were other nucleation sites such as carbonyl (-C-O) and amine (-N-H-) groups on SF molecules besides the carboxyl (-COOH) and hydroxyl (-OH) groups previously reported. During the formation of HA, the coordination action between specific functional groups on SF and calcium ions (Ca{sup 2+}) played an important role. The crystallinity of HA was improved and had an orientation growth along (0 0 2) at the presence of SF, resulting in a structure similar to natural bone. It was concluded that SF could regulate the structure and morphology of HA effectively. (communication)

Wang Jing; Yu Feng; Qu Lijie; Meng Xiangcai [Provincial Key Laboratory of Biomaterials, Jiamusi University, Jiamusi 154007 (China); Wen, G [School of Materials Science and Engineering, Harbin Institute of Technology, Heilongjiang Province 150001 (China)

2010-08-01

235

Preparation of electrospun silk fibroin fiber mats as bone scaffolds: a preliminary study  

Energy Technology Data Exchange (ETDEWEB)

In the present contribution, electrospinning (e-spinning) was used to fabricate ultra-fine fibers of silk fibroin (SF) from cocoons of indigenous Thai silkworms (Nang-Lai) and Chinese/Japanese hybrid silkworms (DOAE-7). The effects of solution concentration (i.e., 10-40% (w/v) in 85% (v/v) formic acid) and applied electrostatic field strength (EFS; 10, 15 and 20 kV/10 cm) on morphology and size of the electrospun (e-spun) SF products were investigated by scanning electron microscopy. The average diameter of the resulting e-spun SF fibers was found to increase with an increase in both the solution concentration and the EFS value. Specifically, the average diameter of the e-spun SF fibers from Nang-Lai SF solutions ranged between 217 and 610 nm, while that of the fibers from DOAE-7 SF solutions ranged between 183 and 810 nm. The potential for use of the e-spun SF fiber mats as bone scaffolds was assessed with mouse osteoblast-like cells (MC3T3-E1) in which the cells appeared to adhere and proliferate well on their surface.

Meechaisue, Chidchanok [Department of Materials Technology, Faculty of Science, Ramkhamhaeng University, Bangkok 10240 (Thailand); Wutticharoenmongkol, Patcharaporn [Technological Center for Electrospun Fibers and The Petroleum and Petrochemical College, Chulalongkorn University, Bangkok 10330 (Thailand); Waraput, Rujira [Department of Materials Technology, Faculty of Science, Ramkhamhaeng University, Bangkok 10240 (Thailand); Huangjing, Thanapol [Department of Materials Technology, Faculty of Science, Ramkhamhaeng University, Bangkok 10240 (Thailand); Ketbumrung, Nantana [Department of Materials Technology, Faculty of Science, Ramkhamhaeng University, Bangkok 10240 (Thailand); Pavasant, Prasit [Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok 10330 (Thailand); Supaphol, Pitt [Technological Center for Electrospun Fibers and The Petroleum and Petrochemical College, Chulalongkorn University, Bangkok 10330 (Thailand)

2007-09-15

236

Regenerated silk fibroin films with controllable nanostructure size and secondary structure for drug delivery.  

Science.gov (United States)

The ability of drug release from SF materials was governed largely by their secondary structure. It is known that the breakage degree of the peptide chain during the silk fibroin (SF) dissolution can affect the structure, property, and applications of SF materials. To deeply understand this effect, we designed a reaction system based on CaCl2/H2O/C2H5OH ternary solvent with different ethanol content to obtain the regenerated SF films with different morphologies and secondary structures. The results showed that the globule-like nanostructure was observed in all regenerated SF films, and their size decreased significantly with reducing the ethanol content in the solvent. Correspondingly, the ?-sheet structure content of the SF films increased. In addition, the contact angle and the elongation ratio increased, and water absorption decreased significantly with decreasing the ethanol content in the solvent. The accumulated release percents of doxorubicin from these SF films were significantly different with increasing the time. With smaller nanostructure size and more ?-sheet content, the SF films had a slower drug release at the beginning. This study indicated the importance of the ethanol content in the solvent in controlling the structure and properties of the regenerated SF films, which would improve the application of SF in drug delivery. PMID:25536875

Zhou, Juan; Zhang, Bin; Shi, Lijun; Zhong, Jian; Zhu, Jun; Yan, Juan; Wang, Ping; Cao, Chuanbao; He, Dannong

2014-12-24

237

Immobilization of acetylcholinesterase via biocompatible interface of silk fibroin for detection of organophosphate and carbamate pesticides  

International Nuclear Information System (INIS)

An amperometric biosensor for the detection of organophosphate and carbamate pesticides was developed based on the immobilization of acetylcholinesterase (AChE) on regenerated silk fibroin (SF) matrix by non-covalent adsorption. SF and AChE were coated sequentially on the surface of the glassy carbon electrode (GCE) which was modified with multiwall carbon nanotube (MWNTs). The obtained biosensor was denoted as AChE-SF/MWNTs/GCE. The atomic force microscopy images showed that the SF matrix provided a more homogeneous interface for the AChE immobilization. The aggregation of immobilizing AChE was therefore avoided. The cyclic voltammogram of thiocholine at this biosensor exhibited a well defined oxidation peak at 0.667 V (vs. SCE). The inhibition rate of methyl parathion to the immobilized AChE was proportional to the logarithm of the concentration of methyl parathion over the range of the concentration of methyl parathion from 3.5 × 10-6 to 2.0 × 10-3 M with a detection limit of 5.0 × 10-7 M. Similarly, the linearly response range of carbaryl was from 1.0 × 10-7 to 3.0 × 10-5 M with a detection limit of 6.0 × 10-8 M. The experimental results indicate that AChE not only can be immobilized steadily on the SF matrix, but also the bioactivity of immobilizing AChE can be preserved effectively.

238

Immobilization of acetylcholinesterase via biocompatible interface of silk fibroin for detection of organophosphate and carbamate pesticides  

Science.gov (United States)

An amperometric biosensor for the detection of organophosphate and carbamate pesticides was developed based on the immobilization of acetylcholinesterase (AChE) on regenerated silk fibroin (SF) matrix by non-covalent adsorption. SF and AChE were coated sequentially on the surface of the glassy carbon electrode (GCE) which was modified with multiwall carbon nanotube (MWNTs). The obtained biosensor was denoted as AChE-SF/MWNTs/GCE. The atomic force microscopy images showed that the SF matrix provided a more homogeneous interface for the AChE immobilization. The aggregation of immobilizing AChE was therefore avoided. The cyclic voltammogram of thiocholine at this biosensor exhibited a well defined oxidation peak at 0.667 V (vs. SCE). The inhibition rate of methyl parathion to the immobilized AChE was proportional to the logarithm of the concentration of methyl parathion over the range of the concentration of methyl parathion from 3.5 × 10-6 to 2.0 × 10-3 M with a detection limit of 5.0 × 10-7 M. Similarly, the linearly response range of carbaryl was from 1.0 × 10-7 to 3.0 × 10-5 M with a detection limit of 6.0 × 10-8 M. The experimental results indicate that AChE not only can be immobilized steadily on the SF matrix, but also the bioactivity of immobilizing AChE can be preserved effectively.

Xue, Rui; Kang, Tian-Fang; Lu, Li-Ping; Cheng, Shui-Yuan

2012-06-01

239

Preparation and characterisation of vancomycin-impregnated gelatin microspheres/silk fibroin scaffold.  

Science.gov (United States)

A type of antibacterial silk fibroin (SF) scaffold was developed and characterised as a potential functional wound dressing for acute trauma treatment. To achieve this, SF solution was mixed with previously fabricated vancomycin (Vm)-loaded gelatin (G) microspheres, followed by a freeze-drying step. Some physical and antimicrobial properties of the prepared Vm/G/SF scaffolds were investigated and the results demonstrated that the average pore size and porosity of the composite scaffold were 60-80 ?m and 75%, respectively. The compressive stress and compressive modulus of Vm/G/SF scaffold were 140 and 468 KPa, respectively. Compared with Vm/G microspheres and Vm/SF scaffold, the Vm/G/SF scaffold has slower release rate of Vm. In addition, the Vm release rate of Vm/G/SF scaffold matched well with the degradation rate of SF scaffold. With respect to the antimicrobial effect, the results showed that the Vm/G/SF scaffold had good antimicrobial activity against Staphylococcus aureus (gram-positive), which is a gram-positive bacteria commonly found in infected wounds. PMID:24053472

Lan, Yong; Li, Weichang; Guo, Rui; Zhang, Yi; Xue, Wei; Zhang, Yuanming

2014-01-01

240

Cartilage Tissue Engineering with Silk Fibroin Scaffolds Fabricated by Indirect Additive Manufacturing Technology  

Directory of Open Access Journals (Sweden)

Full Text Available Advanced tissue engineering (TE technology based on additive manufacturing (AM can fabricate scaffolds with a three-dimensional (3D environment suitable for cartilage regeneration. Specifically, AM technology may allow the incorporation of complex architectural features. The present study involves the fabrication of 3D TE scaffolds by an indirect AM approach using silk fibroin (SF. From scanning electron microscopic observations, the presence of micro-pores and interconnected channels within the scaffold could be verified, resulting in a TE scaffold with both micro- and macro-structural features. The intrinsic properties, such as the chemical structure and thermal characteristics of SF, were preserved after the indirect AM manufacturing process. In vitro cell culture within the SF scaffold using porcine articular chondrocytes showed a steady increase in cell numbers up to Day 14. The specific production (per cell basis of the cartilage-specific extracellular matrix component (collagen Type II was enhanced with culture time up to 12 weeks, indicating the re-differentiation of chondrocytes within the scaffold. Subcutaneous implantation of the scaffold-chondrocyte constructs in nude mice also confirmed the formation of ectopic cartilage by histological examination and immunostaining.

Chih-Hao Chen

2014-03-01

241

Fabrication and Intermolecular Interactions of Silk Fibroin/Hydroxybutyl Chitosan Blended Nanofibers  

Directory of Open Access Journals (Sweden)

Full Text Available The native extracellular matrix (ECM is composed of a cross-linked porous network of multifibril collagens and glycosaminoglycans. Nanofibrous scaffolds of silk fibroin (SF and hydroxybutyl chitosan (HBC blends were fabricated using 1,1,1,3,3,3-hexa?uoro-2-propanol (HFIP and trifluoroacetic acid (TFA as solvents to biomimic the native ECM via electrospinning. Scanning electronic microscope (SEM showed that relatively uniform nanofibers could be obtained when 12% SF was blended with 6% HBC at the weight ratio of 50:50. Meanwhile, the average nano?brous diameter increased when the content of HBC in SF/HBC blends was raised from 20% to 100%. Fourier transform infrared spectra (FTIR and 13C nuclear magnetic resonance (NMR showed SF and HBC molecules existed in hydrogen bonding interactions but HBC did not induce conformation of SF transforming from random coil form to ?-sheet structure. X-ray diffraction (XRD confirmed the different structure of SF/HBC blended nanofibers from both SF and HBC. Thermogravimetry-Differential thermogravimetry (TG-DTG results demonstrated that the thermal stability of SF/HBC blend nanofibrous scaffolds was improved. The results indicated that the rearrangement of HBC and SF molecular chain formed a new structure due to stronger hydrogen bonding between SF and HBC. These electrospun SF/HBC blended nanofibers may provide an ideal tissue engineering scaffold and wound dressing.

Xiu-Mei Mo

2011-03-01

242

In vitro biocompatibility evaluation of silk-fibroin/polyurethane membrane with cultivation of HUVECs  

Science.gov (United States)

In order to investigate the in vitro biocompatibility of a novel polyurethane (PU) membrane modified by incorporation of superfine silk-fibroin powder (SFP), which was prepared for small-diameter vascular grafts, with the cultivation of human umbilical vein endothelial cells (HUVECs), PU and SFP were mixed with the ratios of 9:1, 7:3, 5:5, 3:7 (PU:SFP) to make four composite materials. Unmodified PU and polytetrafluoroethylene (PTFE) were added as control groups. CCK-8 assay was used to evaluate the cytotoxicity of these biomaterials. Data were processed using SPSS, and P HUVECs on the surface of specimens was observed using direct contact cultivation. The toxicity ratings of the novel composites were grade 0-1, which is in the acceptable range. In all the experimental groups except control, SFP/PU with ratio of 1:9 had the least cytotoxicity property, and more content of SFP in the composite showed no improvement of the biocompatibility. HUVECs strongly attached to and grew on the surface of the biomaterials, and proliferated rapidly. The proliferation ability increased with increased proportion of SFP; however the cell quantity on the surface of the materials decreased when the proportion of SFP was equal to or larger than that of PU in the composite. It is concluded that this novel material has excellent cellular affinity with no cytotoxicity to HUVECs. Adding SFP gives PU better biocompatibility, while further research on optimum blend ratios is still needed.

Zhou, Mei; Wang, Wei-Ci; Liao, Yong-Gui; Liu, Wen-Qi; Yu, Miao; Ouyang, Chen-Xi

2014-03-01

243

Morphology, Secondary Structure and Thermal Properties of Silk Fibroin/Gelatin Blend Film  

Directory of Open Access Journals (Sweden)

Full Text Available This study aimed to prepare Silk Fibroin (SF and Gelatin (G blend film and study its morphology, secondary structure and thermal properties compared to native SF and G films. The films were prepared from the SF solution by casting on the polystyrene plates. They were investigated their secondary structure by fourier transform-infrared (FTIR spectroscopy, morphology using Scanning Electron Microscope (SEM. In addition, Thermogravimetric Analysis (TG and Differential TG (DTG were used for thermal properties investigation. The results found that the SF/G blend film composed of both ?-helix and ?-sheet structures which were similar characteristics of the native SF and G. This result was similar to the TG and DTG analysis according to blending between SF and G is not enhancing thermal stability of the film. However, changes in some absorption bands and temperatures were also observed from the blend film. The result suggested that chemical interaction and hydrogen bonding between SF and G could be formed. The formation could be affected to the uniform of the surface throughout the film under SEM.

Ong-chiari Watcharin

2009-01-01

244

In vitro and in vivo Evaluation of Hemocompatibility of Silk Fibroin Based Artificial Vascular Grafts  

Directory of Open Access Journals (Sweden)

Full Text Available Artificial vascular grafts with low thrombogenicity are generally required to avoid blood platelet adhesion and to minimize intimal hyperplasia, thus retaining vascular patency. In this study, we aimed to determine the acute and subacute hemocompatibility of silk fibroin (SF grafts by in vitro and in vivo evaluation. Blood contact reaction with SF grafts was examined by thrombin-anti-thrombin III complex (TAT formation, platelet activation level by beta-thromboglobulin (beta-TG, complement system response (C3a and SC5b-9, platelet and fibrin deposition and compared with commercially available polyethylene terephthalate (PET artificial grafts in vitro. The biocompatibility and coagulation-inducing effect of coating materials were evaluated by in vivo implantation in rats. Two weeks after implantation, SF grafts showed low subacute coagulation. All blood parameters evaluated for animals implanted with SF-coated grafts showed almost the same values as those for sham-operated animals. Our results support the suggestion that SF will be a suitable material for vascular regeneration in future.

Derya Aytemiz

2014-03-01

245

Microporous silk fibroin scaffolds embedding PLGA microparticles for controlled growth factor delivery in tissue engineering.  

Science.gov (United States)

The development of prototype scaffolds for either direct implantation or tissue engineering purposes and featuring spatiotemporal control of growth factor release is highly desirable. Silk fibroin (SF) scaffolds with interconnective pores, carrying embedded microparticles that were loaded with insulin-like growth factor I (IGF-I), were prepared by a porogen leaching protocol. Treatments with methanol or water vapor induced water insolubility of SF based on an increase in beta-sheet content as analyzed by FTIR. Pore interconnectivity was demonstrated by SEM. Porosities were in the range of 70-90%, depending on the treatment applied, and were better preserved when methanol or water vapor treatments were prior to porogen leaching. IGF-I was encapsulated into two different types of poly(lactide-co-glycolide) microparticles (PLGA MP) using uncapped PLGA (50:50) with molecular weights of either 14 or 35 kDa to control IGF-I release kinetics from the SF scaffold. Embedded PLGA MP were located in the walls or intersections of the SF scaffold. Embedment of the PLGA MP into the scaffolds led to more sustained release rates as compared to the free PLGA MP, whereas the hydrolytic degradation of the two PLGA MP types was not affected. The PLGA types used had distinct effects on IGF-I release kinetics. Particularly the supernatants of the lower molecular weight PLGA formulations turned out to release bioactive IGF-I. Our studies justify future investigations of the developed constructs for tissue engineering applications. PMID:19157533

Wenk, Esther; Meinel, Anne J; Wildy, Sarah; Merkle, Hans P; Meinel, Lorenz

2009-05-01

246

Synthesis and characterization of dense membranes of silk fibroin with glycerin;Sintese e caracterizacao de membranas densas de fibroina de seda com glicerina  

Energy Technology Data Exchange (ETDEWEB)

The addition of plasticizers seeks improvements in mechanical properties of dense membranes of silk fibroin with possible interactions by hydrogen bonds. The aim of the present study was to produce and characterize dense membranes of silk fibroin containing glycerin in two different concentrations. The characterization of the membranes was performed from scanning electron microscopy (SEM), mechanical traction tests, infrared spectroscopy (FTIR-ATR) and X-ray diffraction (XRD). The results indicated that the addition of glycerin allowed obtaining homogeneous and more crystalline membranes and improved their properties of elongation. (author)

Silva, Mariana F.; Moraes, Mariana A. de; Weska, Raquel F.; Nogueira, Grinia M.; Beppu, Marisa M., E-mail: beppu@feq.unicamp.b [Universidade Estadual de Campinas (FEQ/UNICAMP), SP (Brazil). Faculdade de Engenharia Quimica

2009-07-01

247

Effect of Strongly Alkaline Electrolyzed Water on Silk Degumming and the Physical Properties of the Fibroin Fiber.  

Science.gov (United States)

Strongly alkaline electrolyzed water (SAEW) was prepared by electrolysis of tap water in a laboratory-made water electrolyzer. The pH of stored SAEW was stable for more than one month. The hardness of the electrolyzed water was 30% lower and the Na(+) concentration was 18% higher than those of the tap water. Silkworm cocoon shells were boiled in pH 11.50 SAEW at a ratio of 1?40?80 (W/V) for 20 min and the sericin layers around the silk fibroin fibers were removed completely. The tensile properties and thermal decomposition temperature of a single filament of silk fibroin obtained by the SAEW method were almost the same as those for the fiber obtained by the neutral soap, and much higher than those for the fiber obtained by Na2CO3 degumming. The results demonstrate that SAEW is an environmentally friendly and pollution-free silk degumming agent that allows highly efficient, low cost recovery of sericin. PMID:23824061

Cao, Ting-Ting; Wang, Yuan-Jing; Zhang, Yu-Qing

2013-01-01

248

Enhanced osteogenic potential of human mesenchymal stem cells on electrospun nanofibrous scaffolds prepared from eri-tasar silk fibroin.  

Science.gov (United States)

This study evaluated the mechanical properties and osteogenic potential of a silk fibroin scaffold prepared from a 70:30 blend of Eri (Philosamia ricini) and Tasar (Antheraea mylitta) silk, respectively (ET scaffolds). An electrospinning process was used to prepare uniformly blended, fibrous scaffolds of nanoscale dimensions, as confirmed by scanning and transmission electron microscopy (fiber diameter gelatin and Bombyx mori (BM) silk fibroin were used as controls. Mechanical testing and atomic force microscopy showed that the ET scaffolds had significantly higher tensile strength (1.83?±?0.13 MPa) and surface roughness (0.44 ?m) compared with BM (1.47?±?0.10 MPa; 0.37 ?m) and gelatin scaffolds (0.6?±?0.07 MPa; 0.28 ?m). All scaffolds were exposed to mesenchymal stem cells isolated to human chord blood (hMSCs) for up to 28 days in vitro. Alamar blue and alkaline phosphatase assay showed greater attachment and proliferation for both ET and BM scaffolds compared with gelatin. The ET scaffolds also promoted greater differentiation of the attached hMSCs as evidenced by higher expression of RunX2, osteocalcin, and CD29/CD44 expression. ET scaffolds also showed significantly higher mineralization, as evidenced by glycosaminoglycan assay, alizarin red staining, and elemental analysis of crystalline composites isolated from the scaffolds. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014. PMID:25176408

Panda, Niladri Nath; Biswas, Amit; Pramanik, Krishna; Jonnalagadda, Sriramakamal

2014-08-30

249

Structural evolution of regenerated silk fibroin under shear: Combined wide- and small-angle x-ray scattering experiments using synchrotron radiation  

Energy Technology Data Exchange (ETDEWEB)

The structural evolution of regenerated Bombyx mori silk fibroin during shearing with a Couette cell has been studied in situ by synchrotron radiation small- and wide-angle x-ray scattering techniques. An elongation of fibroin molecules was observed with increasing shear rate, followed by an aggregation phase. The aggregates were found to be amorphous with {beta}-conformation according to infrared spectroscopy. Scanning x-ray microdiffraction with a 5 {micro}m beam on aggregated material, which had solidified in air, showed silk II reflections and a material with equatorial reflections close to the silk I structure reflections, but with strong differences in reflection intensities. This silk I type material shows up to two low-angle peaks suggesting the presence of water molecules that might be intercalated between hydrogen-bonded sheets.

Rossle, Manfred [European Molecular Biology Laboratory (EMBL), France; Panine, Pierre [European Synchrotron Radiation Facility (ESRF); Urban, Volker S [ORNL; Riekel, Christine [European Synchrotron Radiation Facility (ESRF)

2004-04-01

250

Effect of Strongly Alkaline Electrolyzed Water on Silk Degumming and the Physical Properties of the Fibroin Fiber  

OpenAIRE

Strongly alkaline electrolyzed water (SAEW) was prepared by electrolysis of tap water in a laboratory-made water electrolyzer. The pH of stored SAEW was stable for more than one month. The hardness of the electrolyzed water was 30% lower and the Na+ concentration was 18% higher than those of the tap water. Silkworm cocoon shells were boiled in pH 11.50 SAEW at a ratio of 1?40?80 (W/V) for 20 min and the sericin layers around the silk fibroin fibers were removed completely. The tensile pro...

Cao, Ting-ting; Wang, Yuan-jing; Zhang, Yu-qing

2013-01-01

251

Outgrowth endothelial cells isolated and expanded from human peripheral blood progenitor cells as a potential source of autologous cells for endothelialization of silk fibroin biomaterials.  

Science.gov (United States)

One challenge of particular importance in tissue engineering is to improve vascularization of larger size defects, which would then facilitate a sufficient supply with oxygen and nutrients to the central regions of a larger tissue-engineered construct or in highly vascularized tissues. In this study, we show that outgrowth endothelial cells (OECs) derived from human peripheral blood can serve as a source of human autologous endothelial cells and can be used in combination with fibroin silk fiber meshes for applications in tissue engineering. OEC reveal a highly differentiated endothelial phenotype as well as a high phenotypic stability during their expansion. Furthermore, OEC showed very promising results in the endothelialization of fibroin silk fiber meshes, maintaining their endothelial characteristics and functions. On the fibroin fiber meshes OECs formed differentiated endothelial cell layers covering the single fibers as shown by data from scanning electron microscopy, immunofluorescence, and gene expression analysis. After embedding in a wound-healing matrix, mimicked by fibrin gels, OEC migrated from the fibroin scaffolds into the fibrin and formed a microvessel-like network. Thus, we conclude that OEC could serve as a valuable source of autologous endothelial cells, supporting pro-angiogenic therapies in combination with silk fibroin-based scaffolding materials in the field of tissue engineering and regenerative medicine. PMID:16837042

Fuchs, Sabine; Motta, Antonella; Migliaresi, Claudio; Kirkpatrick, Charles James

2006-11-01

252

Radiation degradation of silk  

Energy Technology Data Exchange (ETDEWEB)

Silk fibroin powder was prepared from irradiated silk fibroin fiber by means of only physical treatment. Silk fibroin fiber irradiated with an accelerated electron beam in the dose range of 250 - 1000 kGy was pulverized by using a ball mill. Unirradiated silk fibroin fiber was not pulverized at all. But the more irradiation was increased, the more the conversion efficiency from fiber to powder was increased. The conversion efficiency of silk fibroin fiber irradiated 1000 kGy in oxygen was 94%. Silk fibroin powder shows remarkable solubility, which dissolved 57% into water of ambient temperature. It is a very interesting phenomenon that silk fibroin which did not treat with chemicals gets solubility only being pulverized. In order to study mechanism of solubilization of silk fibroin powder, amino acid component of soluble part of silk fibroin powder was analyzed. The more irradiation dose up, the more glycine or alanine degraded, but degradation fraction reached bounds about 50%. Other amino acids were degraded only 20% even at the maximum. To consider crystal construction of silk fibroin, it is suggested that irradiation on silk fibroin fiber selectively degrades glycine and alanine in amorphous region, which makes it possible to pulverize and to dissolve silk fibroin powder. (author)

Ishida, Kazushige; Kamiishi, Youichi [Textile Research Institute of Gunma, Kiryu, Gunma (Japan); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2001-03-01

253

Endothelialization of a non-woven silk fibroin net for use in tissue engineering: growth and gene regulation of human endothelial cells.  

Science.gov (United States)

We have previously shown that a biomaterial consisting of a non-woven fibroin net produced from silk (Bombyx mori) cocoons is an excellent scaffolding material for a wide variety of human cells of different tissue types. Endothelialization must take place for a biomaterial to be successful after implantation. Therefore, primary human endothelial cells and the human endothelial cell lines, HPMEC-ST1.6R and ISO-HAS-1, were examined for adherence and growth patterns on the fibroin nets by confocal laser scanning microscopy after vital staining of the cells and by electron microscopy. Endothelial cells adhered and spread along individual fibers of the nets and did not fill the gaps between individual fibers. Higher attachment and growth coverage was obtained if nets were first coated with gelatin, fibronectin or collagen type I. Proinflammatory markers of endothelial cells on the fibers exhibited a non-activated state and LPS-stimulated cells exhibited activation of these markers. Furthermore, a typical PECAM-1 localization at cell-cell contacts was observed. Scanning electron microscopic examination of fibroin nets after removal of cells did not demonstrate any changes to the fibroin structure. HUVEC and HDMEC on fibroin nets embedded in collagen type I gels formed microvessel-like structures. Thus, silk fibroin nets are a highly endothelial cell-compatible scaffolding material that support the growth, normal and inducible cell functions and angiogenesis potential of human endothelial cells in vitro similar to that observed in vivo. PMID:15109837

Unger, R E; Peters, K; Wolf, M; Motta, A; Migliaresi, C; Kirkpatrick, C J

2004-09-01

254

Immobilization of acetylcholinesterase via biocompatible interface of silk fibroin for detection of organophosphate and carbamate pesticides  

Energy Technology Data Exchange (ETDEWEB)

An amperometric biosensor for the detection of organophosphate and carbamate pesticides was developed based on the immobilization of acetylcholinesterase (AChE) on regenerated silk fibroin (SF) matrix by non-covalent adsorption. SF and AChE were coated sequentially on the surface of the glassy carbon electrode (GCE) which was modified with multiwall carbon nanotube (MWNTs). The obtained biosensor was denoted as AChE-SF/MWNTs/GCE. The atomic force microscopy images showed that the SF matrix provided a more homogeneous interface for the AChE immobilization. The aggregation of immobilizing AChE was therefore avoided. The cyclic voltammogram of thiocholine at this biosensor exhibited a well defined oxidation peak at 0.667 V (vs. SCE). The inhibition rate of methyl parathion to the immobilized AChE was proportional to the logarithm of the concentration of methyl parathion over the range of the concentration of methyl parathion from 3.5 Multiplication-Sign 10{sup -6} to 2.0 Multiplication-Sign 10{sup -3} M with a detection limit of 5.0 Multiplication-Sign 10{sup -7} M. Similarly, the linearly response range of carbaryl was from 1.0 Multiplication-Sign 10{sup -7} to 3.0 Multiplication-Sign 10{sup -5} M with a detection limit of 6.0 Multiplication-Sign 10{sup -8} M. The experimental results indicate that AChE not only can be immobilized steadily on the SF matrix, but also the bioactivity of immobilizing AChE can be preserved effectively.

Xue Rui [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Kang Tianfang, E-mail: kangtf@yahoo.cn [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Lu Liping; Cheng Shuiyuan [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China)

2012-06-01

255

Fabrication and characterization of silk fibroin/bioactive glass composite films  

Energy Technology Data Exchange (ETDEWEB)

Composite films of silk fibroin (SF) with nano bioactive glass (NBG) were prepared by the solvent casting method, and the structures and properties of the composite films were characterized. Fourier transform infrared (FT-IR) spectroscopy analysis shows that the random coil and {beta}-sheet structure co-exist in the SF films. Results of field emission scanning electron microscope (FESEM) indicate that the NBG particles are uniformly dispersed in the SF films. The measurements of the water contact angles suggest that the incorporation of NBG into SF can improve the hydrophilicity of the composites. The bioactivity of the composite films was evaluated by soaking in 1.5 times simulated body fluid (1.5 Multiplication-Sign SBF), and formation of a hydroxycarbonate apatite (HCA) layer was determined by XRD and FESEM. The results show that the SF/NBG composite film is bioactive as it induces the formation of HCA on the surface of the composite film after soaking in 1.5 Multiplication-Sign SBF for 7 days. In vitro osteoblasts attachment and proliferation tests show that the composite film is a good matrix for the growth of osteoblasts. Consequently, the incorporation of NBG into the SF film can enhance both the bioactivity and biocompatibility of the film, which suggests that the SF/NBG composite film may be a potential biomaterial for bone tissue engineering. - Highlights: Black-Right-Pointing-Pointer The incorporation of NBG into SF can improve the hydrophilicity of the SF/NBG composite films. Black-Right-Pointing-Pointer The SF/NBG composite films show the better bioactivity than the pure SF film. Black-Right-Pointing-Pointer The SF/NBG composite films facilitate cell growth and promote cell proliferation and differentiation.

Zhu Hailin [Engineering Research Center for Eco-Dyeing and Finishing of Textiles, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, 310018 (China); Department of Chemistry, Xiasha Higher Education Zone, Zhejiang Sci-Tech University, Hangzhou, 310018 (China); Liu Na; Feng Xinxing [Engineering Research Center for Eco-Dyeing and Finishing of Textiles, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, 310018 (China); Chen Jianyong, E-mail: cjy@zstu.edu.cn [Engineering Research Center for Eco-Dyeing and Finishing of Textiles, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, 310018 (China)

2012-05-01

256

Rheology and electrospinning of regenerated bombyx mori silk fibroin aqueous solutions.  

Science.gov (United States)

Bombyx mori silk fibroin (BMSF) has received considerable research interest as a potential biomaterial owing to its excellent mechanical properties and benign, versatile material fabrication options, including electrospinning. Despite this, characterizations of regenerated BMSF aqueous solutions and electrospun materials resulting from them are still very limited in the literature. This report details the rheological characterization of regenerated aqueous BMSF solutions under shear and elongational deformation. Well-characterized regenerated BMSF solutions were then systematically electrospun over a range of concentrations and process parameters to determine their effects on electrospinning processing windows and fiber morphology. BMSF solutions could not be electrospun successfully if BMSF concentration was below 20 wt % or the relaxation time measured using the CaBER rheometer was below 0.001 s. Electrospun BMSF fiber diameter was found to increase with solution concentration when stable electrospinning was achieved. An upper threshold of 30 wt % BMSF solution was identified for the formation of fibers with a circular cross section. Adding small amount of high molecular weight poly(ethylene oxide) was an effective rheological modifier that greatly improved the electrospinnability of BMSF solutions. Electrospinning BMSF-PEO solutions over a range of parameters significantly altered the fiber products. Increasing voltage from 0.5 to 1 kV/cm was found to decrease fiber diameter by approximately 50% (p < 0.001). Flow rate was found to have a significant effect on fiber diameter, which decreased with spinneret height. The results presented here provide valuable guidance in the production of BMSF electrospun materials with specific properties for tissue engineering and regenerative medicine. PMID:24661009

Hodgkinson, Tom; Chen, Ying; Bayat, Ardeshir; Yuan, Xue-Feng

2014-04-14

257

Fabrication and characterization of silk fibroin/bioactive glass composite films  

International Nuclear Information System (INIS)

Composite films of silk fibroin (SF) with nano bioactive glass (NBG) were prepared by the solvent casting method, and the structures and properties of the composite films were characterized. Fourier transform infrared (FT-IR) spectroscopy analysis shows that the random coil and ?-sheet structure co-exist in the SF films. Results of field emission scanning electron microscope (FESEM) indicate that the NBG particles are uniformly dispersed in the SF films. The measurements of the water contact angles suggest that the incorporation of NBG into SF can improve the hydrophilicity of the composites. The bioactivity of the composite films was evaluated by soaking in 1.5 times simulated body fluid (1.5 × SBF), and formation of a hydroxycarbonate apatite (HCA) layer was determined by XRD and FESEM. The results show that the SF/NBG composite film is bioactive as it induces the formation of HCA on the surface of the composite film after soaking in 1.5 × SBF for 7 days. In vitro osteoblasts attachment and proliferation tests show that the composite film is a good matrix for the growth of osteoblasts. Consequently, the incorporation of NBG into the SF film can enhance both the bioactivity and biocompatibility of the film, which suggests that the SF/NBG composite film may be a potential biomaterial for bone tissue engineering. - Highlights: ? The incorporation of NBG into SF can improve the hydrophilicity of the SF/NBG composite films. ? The SF/NBG composite films show the be SF/NBG composite films show the better bioactivity than the pure SF film. ? The SF/NBG composite films facilitate cell growth and promote cell proliferation and differentiation.

258

Assessment of freestanding membranes prepared from Antheraea pernyi silk fibroin as a potential vehicle for corneal epithelial cell transplantation.  

Science.gov (United States)

Freestanding membranes created from Bombyx mori silk fibroin (BMSF) offer a potential vehicle for corneal cell transplantation since they are transparent and support the growth of human corneal epithelial (HCE) cells. Fibroin derived from the wild silkworm Antheraea pernyi (APSF) might provide a superior material by virtue of containing putative cell-attachment sites that are absent from BMSF. Thus we have investigated the feasibility of producing transparent, freestanding membranes from APSF and have analysed the behaviour of HCE cells on this material. No significant differences in cell numbers or phenotype were observed in short term HCE cell cultures established on either fibroin. Production of transparent freestanding APSF membranes, however, proved to be problematic as cast solutions of APSF were more prone to becoming opaque, displayed significantly lower permeability and were more brittle than BMSF-membranes. Cultures of HCE cells established on either membrane developed a normal stratified morphology with cytokeratin pair 3/12 being immuno-localized to the superficial layers. We conclude that while it is feasible to produce transparent freestanding membranes from APSF, the technical difficulties associated with this biomaterial, along with an absence of enhanced cell growth, currently favour the continued development of BMSF as a preferred vehicle for corneal cell transplantation. Nevertheless, it remains possible that refinement of techniques for processing APSF might yet lead to improvements in the handling properties and performance of this material. PMID:24565906

Hogerheyde, Thomas A; Suzuki, Shuko; Stephenson, Sally A; Richardson, Neil A; Chirila, Traian V; Harkin, Damien G; Bray, Laura J

2014-04-01

259

Relationship between rheology and electro-spinning performance of regenerated silk fibroin prepared using different degumming methods  

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Electro-spun silk fibroin (SF) has been studied for biomedical applications because of its good biocompatibility, cyto-compatibility, and simple fabrication method. SF is obtained by a degumming process and the degumming method can affect the degree of molecular degradation of SF during the degumming process. In the present study, the effect of the degumming method on the rheology and electro-spinning performance of a silk solution was examined. In addition, the relationship between the rheology and electrospinnability was investigated. Regardless of the degumming method, all silk formic acid solutions exhibited almost Newtonian fluid behavior. The order of the viscosity of the silk solution was as follows: HTHP method > acid method > soap/soda method. An analysis of the correlation between the viscosity and electrospun morphology showed that the viscosity played a key role in determining the electro-spun morphology, and the critical viscosity for good fiber formation without beads in electro-spinning exists between 0.13 and 0.20 Pa·s. The viscosity also determines the maximum electro-spinning rate of the SF formic acid solution. The morphology and diameter of the electro-spun fiber were almost unaffected by the electro-spinning rate of the SF solution.

Kim, Hyun Ju; Um, In Chul

2014-05-01

260

[Preparation and immunogenicity of silk fibroin/chitosan microspheres for DNA vaccine delivery against infectious bursal disease virus].  

Science.gov (United States)

To evaluate the immunities of biodegradable microsphere as a release delivery system for DNA vaccine against Infectious Bursal Disease Virus, in our study, silk fibroin/chitosan microsphere adjuvant was prepared with a precipitation/coacervation method. Both glutaraldehyde and Na2SO4 solution were used in cross-linking. No immune chicken were intramuscularly inoculated at 14 day-old and boosted 2 weeks later. The results show that glutaraldehyde destroyed the DNA activity of the vaccine whereas Na2SO4 solution did not. Factors of the chitosan concentration 0.5% (pH 5.0), silk fibroin concentration 0.6%, plasmid DNA (500 microg/mL) dissolved in 2% Na2SO4 solution were optimized to produce microsphere, with a loading capacity of 89.14%. The average particle size of SF-CS/pCI-VP2/4/3 microsphere is 1.98 microm, and it can protect the loading DNA vaccine from DNase I digestion. Data from anti IBDV ELISA antibodies in the serum show that immunization activity of the microsphere groups were generally higher than plasmid vaccine group (P < 0.05), and the SF/CS compound microspheres group was better than that of sole CS microsphere group. The developed SF/CS microspheres are a very promising vaccine delivery system. PMID:25007575

Liu, Yan; Lv, Zhiqiang; Zhang, Cun; Zhu, Xingrong; Shi, Tuanyuan; Zhong, Shi; Meng, Zhiqi

2014-03-01

261

Fabrication of silk fibroin coated ZnSe : Mn 2+ quantum dots under ?-radiation and their magnetic properties  

Science.gov (United States)

Silk fibroin coated Mn 2+-doped ZnSe quantum dots (SF-ZnSe:Mn 2+ QDs) were successfully synthesized via a one-step ?-radiation route in an aqueous system at room temperature. The prepared QDs were characterized by transmission electron microscopy (TEM) images, energy dispersion spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, photoluminescence (PL) spectroscopy and superconducting quantum interference device (SQUID) magnetometry. The synthesized QDs were about 5 nm in diameter and had excellent water solubility. These QDs showed strong visible orange luminescence under UV excitation and were shown to have a strong emission peak at around 586 nm and a weak emission peak at around 425 nm. Moreover, the products exhibited excellent superparamagnetic behavior when the temperature was above 10 K. These QDs might afford many potential applications in biomedical and other areas. This method could be conveniently extended to fabricate other nanoparticles coated with silk fibroin.

Chang, Shuquan; Dai, Yaodong; Kang, Bin; Han, Wei; Chen, Da

2009-08-01

262

3D silk fibroin scaffold incorporating titanium dioxide (TiO2) nanoparticle (NPs) for tissue engineering.  

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The present study deals with fabrication of scaffolds composing of silk fibroin and TiO2 NPs fabricated using a salt-leaching process. At first instance, the TiO2 NPs were prepared by using sol-gel synthesis, affording to have average diameter of 77±21?m. Furthermore, the aqueous solutions of silk fibroin were mixed with 0.2%, 2.0% and 4.0% of TiO2 NPs and salt-leaching process was introduced which resulted in creation of porous scaffolds modified with TiO2 NPs. The presence of TiO2 NPs in scaffolds was confirmed by VP-FE-SEM-EDS, TGA and XRD. The presence of TiO2 NPs influenced in decrease in pore size and swelling behavior of composite scaffolds. The resultant mechanical property of scaffolds was improved upon the introduction of TiO2 NPs. Moreover, cell cytotoxicity results for 1, 3 and 7 days; revealed no toxic behavior to osteoblasts. However, a mild toxicity to NIH 3T3 fibroblasts was observed with the scaffolds containing 4.0% TiO2 NPs. The cell fixation results from 1 and 7 days of incubation indicated the attachment, spreading and subsequent proliferation of fibroblasts. However, these findings were independent to the amount of TiO2 NPs in scaffolds. PMID:24794196

Kim, Jung-Ho; Sheikh, Faheem A; Ju, Hyung Woo; Park, Hyun Jung; Moon, Bo Mi; Lee, Ok Joo; Park, Chan Hum

2014-07-01

263

Target Specific Delivery of Anticancer Drug in Silk Fibroin Based 3D Distribution Model of Bone-Breast Cancer Cells.  

Science.gov (United States)

To avoid the indiscriminating action of anticancer drugs, the cancer cell specific targeting of drug molecule becomes a preferred choice for the treatment. The successful screening of the drug molecules in 2D culture system requires further validation. The failure of target specific drug in animal model raises the issue of creating a platform in between the in vitro (2D) and in vivo animal testing. The metastatic breast cancer cells migrate and settle at different sites such as bone tissue. This work evaluates the in vitro 3D model of the breast cancer and bone cells to understand the cellular interactions in the presence of a targeted anticancer drug delivery system. The silk fibroin based cytocompatible 3D scaffold is used as in vitro 3D distribution model. Human breast adenocarcinoma and osteoblast like cells are cocultured to evaluate the efficiency of doxorubicin loaded folic acid conjugated silk fibroin nanoparticle as drug delivery system. Decreasing population of the cancer cells, which lower the levels of vascular endothelial growth factors, glucose consumption, and lactate production are observed in the drug treated coculture constructs. The drug treated constructs do not show any major impact on bone mineralization. The diminished expression of osteogenic markers such as osteocalcein and alkaline phosphatase are recorded. The result indicates that this type of silk based 3D in vitro coculture model may be utilized as a bridge between the traditional 2D and animal model system to evaluate the new drug molecule (s) or to reassay the known drug molecules or to develop target specific drug in cancer research. PMID:25557227

Subia, Bano; Dey, Tuli; Sharma, Shaily; Kundu, Subhas C

2015-02-01

264

Silk Fibroin/Chitosan Blend Films Loaded Methylene Blue as a Model for Polar Molecular Releasing: Comparison between Thai Silk Varieties  

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Full Text Available The aims of this study were to prepare Silk Fibroin (SF/Chitosan (CS blend films loaded Methylene Blue (MB and characterize their related properties. The SF was obtained from various Thai silk varieties locally called Nang Lai, Mo and Kaki. The blend films were prepared by mixing the SF, CS and MB solutions before pouring on polystyrene plates. They were then taken to an oven at 40C for 3 days to obtain the films. In addition, each native SF silk variety and CS films were also prepared as control. SEM micrographs showed that native Nang Lai film appeared the bead like particles while other film types were smooth. Comparison between the blend films, Mo variety film has smooth surfaces while Nang Lai and Kaki films composed of flat particles covered their surfaces. FTIR results indicated that all of native SF has similar absorption bands at amide regions which coexisted of a-helix and -sheet structures. Moreover, SF blended with CS showed strong bands at amide II, exhibit -sheet structure. The blend film of Mo variety rapidly decomposed whereas Nang Lai was the lowest. In vitro releasing study indicated that MB released more quickly at the initial 30 min which Mo variety was the slowest.

Srihanam Prasong

2011-01-01

265

Incorporation of Exogenous RGD Peptide and Inter-Species Blending as Strategies for Enhancing Human Corneal Limbal Epithelial Cell Growth on Bombyx mori Silk Fibroin Membranes.  

Science.gov (United States)

While fibroin isolated from the cocoons of domesticated silkworm Bombyx mori supports growth of human corneal limbal epithelial (HLE) cells, the mechanism of cell attachment remains unclear. In the present study we sought to enhance the attachment of HLE cells to membranes of Bombyx mori silk fibroin (BMSF) through surface functionalization with an arginine-glycine-aspartic acid (RGD)-containing peptide. Moreover, we have examined the response of HLE cells to BMSF when blended with the fibroin produced by a wild silkworm, Antheraea pernyi, which is known to contain RGD sequences within its primary structure. A procedure to isolate A. pernyi silk fibroin (APSF) from the cocoons was established, and blends of the two fibroins were prepared at five different BMSF/APSF ratios. In another experiment, BMSF surface was modified by binding chemically the GRGDSPC peptide using a water-soluble carbodiimide. Primary HLE were grown in the absence of serum on membranes made of BMSF, APSF, and their blends, as well as on RGD-modified BMSF. There was no statistically significant enhancing effect on the cell attachment due to the RGD presence. This suggests that the adhesion through RGD ligands may have a complex mechanism, and the investigated strategies are of limited value unless the factors contributing to this mechanism become better known. PMID:24955953

Bray, Laura J; Suzuki, Shuko; Harkin, Damien G; Chirila, Traian V

2013-01-01

266

Incorporation of Exogenous RGD Peptide and Inter-Species Blending as Strategies for Enhancing Human Corneal Limbal Epithelial Cell Growth on Bombyx mori Silk Fibroin Membranes  

Directory of Open Access Journals (Sweden)

Full Text Available While fibroin isolated from the cocoons of domesticated silkworm Bombyx mori supports growth of human corneal limbal epithelial (HLE cells, the mechanism of cell attachment remains unclear. In the present study we sought to enhance the attachment of HLE cells to membranes of Bombyx mori silk fibroin (BMSF through surface functionalization with an arginine-glycine-aspartic acid (RGD-containing peptide. Moreover, we have examined the response of HLE cells to BMSF when blended with the fibroin produced by a wild silkworm, Antheraea pernyi, which is known to contain RGD sequences within its primary structure. A procedure to isolate A. pernyi silk fibroin (APSF from the cocoons was established, and blends of the two fibroins were prepared at five different BMSF/APSF ratios. In another experiment, BMSF surface was modified by binding chemically the GRGDSPC peptide using a water-soluble carbodiimide. Primary HLE were grown in the absence of serum on membranes made of BMSF, APSF, and their blends, as well as on RGD-modified BMSF. There was no statistically significant enhancing effect on the cell attachment due to the RGD presence. This suggests that the adhesion through RGD ligands may have a complex mechanism, and the investigated strategies are of limited value unless the factors contributing to this mechanism become better known.

Traian V. Chirila

2013-05-01

267

Preparation and characterization of biomimetic silk fibroin/chitosan composite nanofibers by electrospinning for osteoblasts culture  

Science.gov (United States)

In this study, we have successfully fabricated electrospun bead-free silk fibroin [SF]/chitosan [CS] composite nanofibers [NFs] covering the whole range of CS content (0%, 25%, 50%, 75%, and 100%). SF/CS spinning solutions were prepared in a mixed solvent system of trifluoroacetic acid [TFA] and dichloromethane. The morphology of the NFs was observed by scanning electron microscope, and the average fiber diameter ranges from 215 to 478 nm. Confocal laser scanning microscopy confirms the uniform distribution of SF and CS within the composite NFs. To increase biocompatibility and preserve nanostructure when seeded with cells in culture medium, NFs were treated with an ethanol/ammonia aqueous solution to remove residual TFA and to change SF protein conformation. After the chemical treatment, SF/CS NFs could maintain the original structure for up to 54 days in culture medium. Properties of pristine and chemically treated SF/CS NFs were investigated by Fourier transform infrared spectroscopy [FT-IR], X-ray diffraction [XRD], and thermogravimetry/differential scanning calorimetry [TG/DSC]. Shift of absorption peaks in FT-IR spectra confirms the conformation change of SF from random coil to ?-sheet by the action of ethanol, which is also consistent with the SF crystalline diffraction patterns measured by XRD. From TG/DSC analysis, the decomposition temperature peaks due to salt formation from TFA and protonated amines disappeared after chemical treatment, indicating complete removal of TFA by binding with ammonium ions during the treatment. This was also confirmed with the disappearance of F1s peak in X-ray photoelectron spectroscopy spectra and disappearance of TFA salt peaks in FT-IR spectra. The composite NFs could support the growth and osteogenic differentiation of human fetal osteoblastic [hFOB] cells, but each component in the composite NF shows distinct effect on cell behavior. SF promotes hFOB proliferation while CS enhances hFOB differentiation. The composite SF/CS NFs will be suitable for bone tissue engineering applications by choosing a suitable blend composition. PACS: 87.85.jf; 87.85.Rs; 68.37.Hk.

Chen, Jyh-Ping; Chen, Shih-Hsien; Lai, Guo-Jyun

2012-03-01

268

Electrospun composites of PHBV, silk fibroin and nano-hydroxyapatite for bone tissue engineering.  

Science.gov (United States)

Electrospinning of fibrous scaffolds containing nano-hydroxyapatite (nHAp) embedded in a matrix of functional biomacromolecules offers an attractive route to mimicking the natural bone tissue architecture. Functional fibrous substrates will support cell attachment, proliferation and differentiation, while the role of HAp is to induce cells to secrete extracellular matrix (ECM) for mineralization to form bone. Electrospinning of biomaterials composed of polyhydroxybutyrate-co-(3-hydroxyvalerate) with 2% valerate fraction (PHBV), nano-hydroxyapatite (nHAp), and Bombyx mori silk fibroin essence (SF), Mw=90KDa, has been achieved for nHAp and SF solution concentrations of 2 (w/vol) % each and 5 (w/vol) % each. The structure and properties of the nanocomposite fibrous membranes were investigated by means of Scanning Electron Microscopy in combination with Energy Dispersive X-Ray Analysis (SEM/EDX), Fourier Transformed Infrared Spectroscopy (FT-IR), uniaxial tensile and compressive mechanical testing, degradation tests and in vitro bioactivity tests. SEM images showed smooth, uniform and continuous fibre deposition with no bead formation, and fibre diameters of between 10 and 15 ?m. EDX and FT-IR confirmed the presence of nHAp and SF. After one month in deionised water, tests showed less than 2% weight loss with the samples retaining their fibrous morphology, confirming that this material biodegrades slowly. After 28 days of immersion in Simulated Body Fluid (SBF) an apatite layer was visible on the surface of the fibres, proving their bioactivity. Preliminary in vitro biological assessment showed that after 1 and 3 days in culture, cells were attached to the fibres, retaining their morphology while presenting a flattened appearance and elongated shape on the surface of fibres. Young's modulus was found to increase from 0.7 kPa (±0.33 kPa) for electrospun samples of PHBV only to 1.4 kPa (±0.54 kPa) for samples with 2 (w/vol) % each of nHAp and SF. Samples prepared with 5 (w/vol) % each of nHAp and SF did not show a similar improvement. PMID:24094204

Pa?cu, Elena I; Stokes, Joseph; McGuinness, Garrett B

2013-12-01

269

Electrospinning-aligned and random polydioxanone-polycaprolactone-silk fibroin-blended scaffolds: geometry for a vascular matrix  

Energy Technology Data Exchange (ETDEWEB)

Extracellular matrices are arranged with a specific geometry based on tissue type and mechanical stimulus. For blood vessels in the body, preferential alignment of fibers is in the direction of repetitive force. Electrospinning is a controllable process which can result in fiber alignment and randomization depending on the parameters utilized. In this study, arterial grafts composed of polycaprolactone (PCL), polydioxanone (PDO) and silk fibroin in blends of 100:0 and 50:50 for both PCL:silk and PDO:silk were investigated to determine if fibers could be controllably aligned using a mandrel rotational speed ranging from 500 to 8000 revolutions per minute (RPM). Results revealed that large- and small-diameter mandrels produced different degrees of fiber alignment based on a fast Fourier transform of scanning electron microscope images. Uniaxial tensile testing further demonstrated scaffold anisotropy through changes in peak stress, modulus and strain at break at mandrel rotational speeds of 500 and 8000 RPM, causing peak stress and modulus for PCL to increase 5- and 4.5-fold, respectively, as rotational speed increased. Additional mechanical testing was performed on grafts using dynamic compliance, burst strength and longitudinal strength displaying that grafts electrospun at higher rotational rates produced stiffer conduits which had lower compliance and higher burst strength compared to the lower mandrel rotational rate. Scaffold properties were found to depend on several parameters in the electrospinning process: mandrel rotational rate, polymer type, and mandrel size. Vascular scaffold design under anisotropic conditions provided interesting insights and warrants further investigation.

McClure, M J; Sell, S A; Bowlin, G L [Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284 (United States); Ayres, C E; Simpson, D G, E-mail: glbowlin@vcu.ed [Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA 23298 (United States)

2009-10-15

270

Composite chitosan/silk fibroin nanofibers for modulation of osteogenic differentiation and proliferation of human mesenchymal stem cells.  

Science.gov (United States)

Nanofibrous membrane scaffolds of chitosan (CS), silk fibroin (SF) and CS/SF blend were prepared by electrospinning and studied for growth and osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs). The morphology and physico-chemical properties of all membrane scaffolds were compared. The influence of CS and SF on cell proliferation was assessed by the MTS assay, whereas osteogenic differentiation was determined from the Alizarin Red staining, alkaline phosphatase activity and expression of osteogenic marker genes. The osteogenic differentiation and proliferation of hMSCs were enhanced by CS and SF nanofibers, respectively. Blending CS with SF retained the osteogenesis nature of CS without negatively influencing the cell proliferative effect of SF. By taking advantage of the differentiation/proliferation cues from individual components, the electrospun CS/SF composite nanofibrous membrane scaffold is suitable for bone tissue engineering. PMID:25037354

Lai, Guo-Jyun; Shalumon, K T; Chen, Shih-Hsien; Chen, Jyh-Ping

2014-10-13

271

Three-Dimensional Porous Network Structure Developed in Hydroxyapatite-Based Nanocomposites Containing Enzyme Pretreated Silk Fibroin  

Energy Technology Data Exchange (ETDEWEB)

Chemically modified silk fibroin (SF) with an enzyme, Proteinase K, has been incorporated into hydroxyapatite (HAp)-based nanocomposite attempting to strengthen the interfacial bonding between the mineral phase and the organic matrix. Particular emphasis is laid on the microstructure and microhardness of the composite along with the crystallographic properties of HAp. The whisker-like HAp crystallites of nanometer size show the preferential self-assembly and anisotropic crystal growth along c-axis. There appears porous microstructure with 70% of open porosity and pore size distribution of 10-115 um in the composite. Attributed to the enzyme modification, the crosslinkage between HAp clusters and SF matrix is improved to form an enhanced three-dimensional network extending throughout the composites and an increase of 35% in microhardness of the composite is achieved as well.

Wang Li; Nemoto, Rei; Senna, Mamoru [Keio University, Department of Applied Chemistry, Faculty of Science and Technology (Japan)], E-mail: senna@applc.keio.ac.jp

2004-02-15

272

High performance pentacene organic field-effect transistors consisting of biocompatible PMMA/silk fibroin bilayer dielectric  

Science.gov (United States)

Pentacene organic field-effect transistors (OFETs) based on single- or double-layer biocompatible dielectrics of poly(methyl methacrylate) (PMMA) and/or silk fibroin (SF) are fabricated. Compared with those devices based on single PMMA or SF dielectric or SF/PMMA bilayer dielectric, the OFETs with biocompatible PMMA/SF bilayer dielectric exhibit optimal performance with a high field-effect mobility of 0.21 cm2/Vs and a current on/off ratio of 1.5×104. By investigating the surface morphology of the pentacene active layer through atom force microscopy and analyzing the electrical properties, the performance enhancement is mainly attributed to the crystallization improvement of the pentacene and the smaller interface trap density at the dielectric/organic interface. Meanwhile, a low contact resistance also indicates that a good electrode/organic contact is formed, thereby assisting the performance improvement of the OFET.

Li, Hai-Qiang; Yu, Jun-Sheng; Huang, Wei; Shi, Wei; Huang, Jiang

2014-03-01

273

Influence of Philosamia ricini Silk Fibroin Components on Morphology, Secondary Structure and Thermal Properties of Chitosan Biopolymer Film  

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Full Text Available This study aimed to prepare Eri (Philosamia ricini Silk Fibroin (SF/chitosan (CS blend films by a solvent evaporation method and to compare the blend films with both native SF and CS films. Influence of SF ratios on the morphology, secondary structure and thermal decomposition of the CS blend films were investigated. The native SF and CS films were uniform and homogeneous without phase separation. For the blend films, the uniform can be found less than 60% of SF composition. All of SF/CS blend films showed both SF and CS characteristics. FT-IR results showed that the blend films composed of both random coil and ?-sheet with predominant of ?-sheet form. Interaction of intermolecular between SF and CS have occurred which were measured by thermogravimetric thermograms. Increasing of SF contents was leading to the increase of ?-sheet structures which were enhanced the thermal stability of the CS blend films.

S. Prasong

2009-01-01

274

Microstructure and Chemical States of Hydroxyapatite/silk Fibroin Nanocomposites Synthesized via A Wet-mechanochemical Route  

Energy Technology Data Exchange (ETDEWEB)

Hydroxyapaptite (HAp)/silk fibroin (SF) nanocomposites were prepared via a wet-mechanochemical route at room temperature. The results reveal that the inorganic phase in the composites is carbonate-substituted HAp containing 2.9-3.1 wt% of carbonate ions. The primary HAp crystals are rod-like in shape with a typical size of 20-30 nm in length and 8-10 nm in width, and lattice parameters a = 9.423 A, c = 6.888 A. The self-assembled HAp crystals along their c-axes aggregate into bundles, which are connected with SF fibrils. Consequently, a three-dimensional porous network is formed in the composite, which is beneficial to inducing new bone formation in practical implantation.

Wang Li; Nemoto, Rei; Senna, Mamoru [Keio University, Department of Applied Chemistry, Faculty of Science and Technology (Japan)], E-mail: senna@applc.keio.ac.jp

2002-12-15

275

Composite Scaffolds Containing Silk Fibroin, Gelatin, and Hydroxyapatite for Bone Tissue Regeneration and 3D Cell Culturing.  

Science.gov (United States)

Three-dimensional (3D) silk fibroin scaffolds were modified with one of the major bone tissue derivatives (nano-hydroxyapatite) and/or a collagen derivative (gelatin). Adhesion and proliferation of mouse embryonic fibroblasts (MEF) within the scaffold were increased after modification with either nano-hydroxyapatite or gelatin. However, a significant increase in MEF adhesion and proliferation was observed when both additives were introduced into the scaffold. Such modified composite scaffolds provide a new and better platform to study wound healing, bone and other tissue regeneration, as well as artificial organ bioengineering. This system can further be applied to establish experimental models to study cell-substrate interactions, cell migration and other complex processes, which may be difficult to address using the conventional two-dimensional culture systems. PMID:24772332

Moisenovich, M M; Arkhipova, A Yu; Orlova, A A; Drutskaya, M S; Volkova, S V; Zacharov, S E; Agapov, I I; Kirpichnikov, M P

2014-01-01

276

Design and characterization of a silk-fibroin-based drug delivery platform using naproxen as a model drug.  

Science.gov (United States)

The objective of this proof-of-concept study was to develop a platform for controlled drug delivery based on silk fibroin (SF) and to explore the feasibility of using SF in oral drug delivery. The SF-containing matrixes were prepared via spray-drying and film casting, and the release profile of the model drug naproxen sodium was evaluated. Attenuated total reflectance Fourier transform infrared spectroscopy (FTIR) has been used to observe conformational changes in SF- and drug-containing compositions. SF-based films, spray-dried microparticles, and matrixes loaded with naproxen were prepared. Both FTIR spectra and in vitro dissolution data demonstrated that SF ?-sheet conformation regulates the release profile of naproxen. The controlled release characteristics of the SF-containing compositions were evaluated as a function of SF concentration, temperature, and exposure to dehydrating solvents. The results suggest that SF may be an attractive polymer for use in controlled drug delivery systems. PMID:22506122

Dyakonov, Tatyana; Yang, Chue Hue; Bush, Derek; Gosangari, Saujanya; Majuru, Shingai; Fatmi, Aqeel

2012-01-01

277

Effect of nanofiber content on bone regeneration of silk fibroin/poly(?-caprolactone nano/microfibrous composite scaffolds  

Directory of Open Access Journals (Sweden)

Full Text Available Beom Su Kim,1,2,* Ko Eun Park,3,4,* Min Hee Kim,3 Hyung Keun You,5 Jun Lee,1 Won Ho Park3 1Wonkwang Bone Regeneration Institute, Wonkwang University, Iksan, South Korea; 2Bone Cell Biotech, Daejeon, South Korea; 3Department of Advanced Organic Materials and Textile System Engineering, Chungnam National University, Daejeon, South Korea; 4Central Research Institute, Humedix, Anyang, South Korea; 5Department of Periodontology, School of Dentistry, Wonkwang University, Iksan, South Korea *These two authors contributed equally to this work Abstract: The broad application of electrospun nanofibrous scaffolds in tissue engineering is limited by their small pore size, which has a negative influence on cell migration. This disadvantage could be significantly improved through the combination of nano- and microfibrous structure. To accomplish this, different nano/microfibrous scaffolds were produced by hybrid electrospinning, combining solution electrospinning with melt electrospinning, while varying the content of the nanofiber. The morphology of the silk fibroin (SF/poly(?-caprolactone (PCL nano/microfibrous composite scaffolds was investigated with field-emission scanning electron microscopy, while the mechanical and pore properties were assessed by measurement of tensile strength and mercury porosimetry. To assay cell proliferation, cell viability, and infiltration ability, human mesenchymal stem cells were seeded on the SF/PCL nano/microfibrous composite scaffolds. From in vivo tests, it was found that the bone-regenerating ability of SF/PCL nano/microfibrous composite scaffolds was closely associated with the nanofiber content in the composite scaffolds. In conclusion, this approach of controlling the nanofiber content in SF/PCL nano/microfibrous composite scaffolds could be useful in the design of novel scaffolds for tissue engineering. Keywords: silk fibroin (SF, poly(?-caprolactone (PCL, nanofibers, microfibers, composite scaffolds, bone regeneration

Kim BS

2015-01-01

278

Solution-based silk fibroin dielectric in n-type C60 organic field-effect transistors: Mobility enhancement by the pentacene interlayer  

Science.gov (United States)

A pentacene interlayer of 2 nm thick is inserted between fullerene (C60) and the solution-based silk fibroin dielectric in C60 organic field-effect transistors (OFETs). The pentacene interlayer assists to improve crystal quality of the C60 layer, leading to the increase of field-effect mobility (?FE) from 0.014 to 1 cm2 V-1 s-1 in vacuum. The ?FE value of the C60 OFET is further enhanced to 10 cm2 V-1 s-1 when the OFET is exposed to air in a relative humidity of 55%. Generation of mobile and immobile charged ions in solution-based silk fibroin in air ambient is proposed.

Tsai, Li-Shiuan; Hwang, Jenn-Chang; Lee, Chun-Yi; Lin, Yi-Ting; Tsai, Cheng-Lun; Chang, Ting-Hao; Chueh, Yu-Lun; Meng, Hsin-Fei

2013-12-01

279

Nanofibrous architecture of silk fibroin scaffolds prepared with a mild self-assembly process  

OpenAIRE

Besides excellent biocompatibility and biodegradability, a useful tissue engineering scaffold should provide suitable macropores and nanofibrous structure, similar to extracellular matrix (ECM), to induce desired cellular activities and to guide tissue regeneration. In the present study, a mild process to prepare porous and nanofibrous silk based scaffolds from aqueous solution is described. Using collagen to control the self-assembly of silk, nanofibrous silk scaffolds were firstly achieved ...

Lu, Qiang; Wang, Xiuli; Lu, Shenzhou; Li, Mingzhong; Kaplan, David L.; Zhu, Hesun

2011-01-01

280

Bioprintable, cell-laden silk fibroin-gelatin hydrogel supporting multilineage differentiation of stem cells for fabrication of three-dimensional tissue constructs.  

Science.gov (United States)

Bioprinting has exciting prospects for printing three-dimensional (3-D) tissue constructs by delivering living cells with appropriate matrix materials. However, progress in this field is currently extremely slow due to limited choices of bioink for cell encapsulation and cytocompatible gelation mechanisms. Here we report the development of clinically relevant sized tissue analogs by 3-D bioprinting, delivering human nasal inferior turbinate tissue-derived mesenchymal progenitor cells encapsulated in silk fibroin-gelatin (SF-G) bioink. Gelation in this bioink was induced via in situ cytocompatible gelation mechanisms, namely enzymatic crosslinking by mushroom tyrosinase and physical crosslinking via sonication. Mechanistically, tyrosinases oxidize the accessible tyrosine residues of silk and/or gelatin into reactive o-quinone moieties that can either condense with each other or undergo nonenzymatic reactions with available amines of both silk and gelatin. Sonication alters the hydrophobic interaction and accelerates self-assembly of silk fibroin macromolecules to form ?-sheet crystals, which physically crosslink the hydrogel. However, sonication has no effect on the conformation of gelatin. The effect of optimized rheology, secondary conformations of silk-gelatin bioink, temporally controllable gelation strategies and printing parameters were assessed to achieve maximum cell viability and multilineage differentiation of the encapsulated human nasal inferior turbinate tissue-derived mesenchymal progenitor cells. This strategy offers a unique path forward in the direction of direct printing of spatially customized anatomical architecture in a patient-specific manner. PMID:25242654

Das, Sanskrita; Pati, Falguni; Choi, Yeong-Jin; Rijal, Girdhari; Shim, Jin-Hyung; Kim, Sung Won; Ray, Alok R; Cho, Dong-Woo; Ghosh, Sourabh

2015-01-01

281

Antheraea pernyi Silk Fibroin-Coated PEI/DNA Complexes for Targeted Gene Delivery in HEK 293 and HCT 116 Cells  

OpenAIRE

Polyethylenimine (PEI) has attracted much attention as a DNA condenser, but its toxicity and non-specific targeting limit its potential. To overcome these limitations, Antheraea pernyi silk fibroin (ASF), a natural protein rich in arginyl-glycyl-aspartic acid (RGD) peptides that contains negative surface charges in a neutral aqueous solution, was used to coat PEI/DNA complexes to form ASF/PEI/DNA ternary complexes. Coating these complexes with ASF caused fewer surface charges and greater size...

Yu Liu; Renchuan You; Guiyang Liu; Xiufang Li; Weihua Sheng; Jicheng Yang; Mingzhong Li

2014-01-01

282

Enhanced differentiation of mesenchymal stem cells co-cultured with ligament fibroblasts on gelatin/silk fibroin hybrid scaffold.  

Science.gov (United States)

The differentiation of mesenchymal stem cells (MSCs) towards fibroblasts is a crucial issue in ligament tissue engineering. This study aims to investigate the feasibility of using co-culture system to induce the differentiation of MSCs for constructing the tissue-engineered ligament in vitro. A kind of silk cable-reinforced gelatin/silk fibroin hybrid scaffold was used to provide three-dimensional (3-D) culture environments for MSCs. The 3-D co-culture system was set up by culturing MSCs/scaffold and ligament fibroblasts in the transwell insert and lower chamber, respectively. The regulatory effects of fibroblasts on MSCs were determined. After 2 weeks of co-culture the MSCs showed faster proliferation and higher DNA content compared with MSCs non-co-cultured. The MSCs were distributed uniformly throughout the scaffold and showed good viability. The collagen production also increased significantly with culture time. The MSCs in co-culture system were proved to differentiate into ligament fibroblasts by expressing ligament extra-cellular matrix (ECM)-specific genes including collagen I, collagen III, and tenascin-C in mRNA and protein level. The immunohistochemistry staining also confirmed the synthesis of key ligament ECM components. This study reveals that specific regulatory signals released from fibroblasts in 3-D co-culture system can enhance the differentiation of MSCs for ligament tissue engineering. PMID:18023476

Fan, Hongbin; Liu, Haifeng; Toh, Siew Lok; Goh, James C H

2008-03-01

283

Size exclusion chromatography for analyses of fibroin in silk: optimization of sampling and separation conditions  

Science.gov (United States)

A direct goal of this paper was to improve the methods of sample preparation and separation for analyses of fibroin polypeptide with the use of size exclusion chromatography (SEC). The motivation for the study arises from our interest in natural polymers included in historic textile and paper artifacts, and is a logical response to the urgent need for developing rationale-based methods for materials conservation. The first step is to develop a reliable analytical tool which would give insight into fibroin structure and its changes caused by both natural and artificial ageing. To investigate the influence of preparation conditions, two sets of artificially aged samples were prepared (with and without NaCl in sample solution) and measured by the means of SEC with multi angle laser light scattering detector. It was shown that dialysis of fibroin dissolved in LiBr solution allows removal of the salt which destroys stacks chromatographic columns and prevents reproducible analyses. Salt rich (NaCl) water solutions of fibroin improved the quality of chromatograms.

Pawcenis, Dominika; Koperska, Monika A.; Milczarek, Jakub M.; ?ojewski, Tomasz; ?ojewska, Joanna

2014-02-01

284

Dissolution and regeneration of Bombyx mori silk fibroin using ionic liquids.  

Science.gov (United States)

In this work, the suitability of imidazolium-based ionic liquid solvents is investigated for the dissolution and regeneration of silkworm (Bombyx mori) silk. Within an ionic liquid the anion plays a larger role in dictating the ultimate solubility of the silk. The dissolution of the silk in the ionic liquid is confirmed using wide-angle X-ray scattering. The dissolved silk is also processed into 100 mum-thick, two-dimensional films, and the structure of these films is examined. The rinse solvent, acetonitrile or methanol, has a profound impact on both the topography of the films and the secondary structure of the silk protein. The image depicts a silkworm cocoon dissolved in 1-butyl-3-methylimidazolium chloride and then regenerated as a film with birefringence. PMID:15521743

Phillips, David M; Drummy, Lawrence F; Conrady, Deborah G; Fox, Douglas M; Naik, Rajesh R; Stone, Morley O; Trulove, Paul C; De Long, Hugh C; Mantz, Robert A

2004-11-10

285

Electrospinning-aligned and random polydioxanone-polycaprolactone-silk fibroin-blended scaffolds: geometry for a vascular matrix  

International Nuclear Information System (INIS)

Extracellular matrices are arranged with a specific geometry based on tissue type and mechanical stimulus. For blood vessels in the body, preferential alignment of fibers is in the direction of repetitive force. Electrospinning is a controllable process which can result in fiber alignment and randomization depending on the parameters utilized. In this study, arterial grafts composed of polycaprolactone (PCL), polydioxanone (PDO) and silk fibroin in blends of 100:0 and 50:50 for both PCL:silk and PDO:silk were investigated to determine if fibers could be controllably aligned using a mandrel rotational speed ranging from 500 to 8000 revolutions per minute (RPM). Results revealed that large- and small-diameter mandrels produced different degrees of fiber alignment based on a fast Fourier transform of scanning electron microscope images. Uniaxial tensile testing further demonstrated scaffold anisotropy through changes in peak stress, modulus and strain at break at mandrel rotational speeds of 500 and 8000 RPM, causing peak stress and modulus for PCL to increase 5- and 4.5-fold, respectively, as rotational speed increased. Additional mechanical testing was performed on grafts using dynamic compliance, burst strength and longitudinal strength displaying that grafts electrospun at higher rotational rates produced stiffer conduits which had lower compliance and higher burst strength compared to the lower mandrel rotational rate. Scaffold properties were found to depend on sevold properties were found to depend on several parameters in the electrospinning process: mandrel rotational rate, polymer type, and mandrel size. Vascular scaffold design under anisotropic conditions provided interesting insights and warrants further investigation.

286

An optimized sericin-1 expression system for mass-producing recombinant proteins in the middle silk glands of transgenic silkworms.  

Science.gov (United States)

The middle silk gland (MSG) of silkworm is thought to be a potential host for mass-producing valuable recombinant proteins. Transgenic MSG expression systems based on the usage of promoter of sericin1 gene (sericin-1 expression system) have been established to produce various recombinant proteins in MSG. However, further modifying the activity of the sericin-1 expression system to yield higher amounts of recombinant proteins is still necessary. In this study, we provide an alternative modification strategy to construct an efficient sericin-1 expression system by using the hr3 enhancer (hr3 CQ) from a Chongqing strain of the Bombyx mori nuclear polyhedrosis virus (BmNPV) and the 3'UTRs of the fibroin heavy chain (Fib-HPA), the fibroin light chain (Fib-LPA), and Sericin1 (Ser1PA) genes. We first analyzed the effects of these DNA elements on expression of luciferase, and found that the combination of hr3 CQ and Ser1PA was most effective to increase the activity of luciferase. Then, hr3 CQ and Ser1PA were used to modify the sericin1 expression system. Transgenic silkworms bearing these modified sericin1 expression vectors were generated by a piggyBac transposon mediated genetic transformation method. Our results showed that mRNA level of DsRed reporter gene in transgenic silkworms containing hr3 CQ and Ser1PA significantly increased by 9 fold to approximately 83 % of that of endogenous sericin1. As the results of that, the production of recombinant RFP increased by 16 fold to 9.5 % (w/w) of cocoon shell weight. We conclude that this modified sericin-1 expression system is efficient and will contribute to the MSG as host to mass produce valuable recombinant proteins. PMID:23435751

Wang, Feng; Xu, Hanfu; Yuan, Lin; Ma, Sanyuan; Wang, Yuancheng; Duan, Xiaoli; Duan, Jianping; Xiang, Zhonghuai; Xia, Qingyou

2013-10-01

287

Silk formation mechanisms in the larval salivary glands of Apis mellifera (Hymenoptera: Apidae).  

Science.gov (United States)

The mechanism of silk formation in Apis mellifera salivary glands, during the 5th instar, was studied. Larval salivary glands were dissected and prepared for light and polarized light microscopy, as well as for scanning and transmission electron microscopy. The results showed that silk formation starts at the middle of the 5th instar and finishes at the end of the same instar. This process begins in the distal secretory portion of the gland, going towards the proximal secretory portion; and from the periphery to the center of the gland lumen. The silk proteins are released from the secretory cells as a homogeneous substance that polymerizes in the lumen to form compact birefringent tactoids. Secondly, the water absorption from the lumen secretion, carried out by secretory and duct cells, promotes aggregation of the tactoids that form a spiral-shape filament with a zigzag pattern. This pattern is also the results of the silk compression in the gland lumen and represents a high concentration of macromolecularly well-oriented silk proteins. PMID:14660875

Silva-Zacarin, Elaine C M; Silva De Moraes, Regina L M; Taboga, S R

2003-12-01

288

Transgenic protein production in silkworm silk glands requires cathepsin and chitinase of Autographa californica multicapsid nucleopolyhedrovirus.  

Science.gov (United States)

The silkworm Bombyx mori represents an established in vivo system for the production of recombinant proteins. Baculoviruses have been extensively investigated and optimised for the expression of high protein levels inside the haemolymph of larvae and pupae of this lepidopteran insect. Current technology includes deletion of genes responsible for the activity of virus-borne proteases, which in wild-type viruses, cause liquefaction of the host insect and enhance horizontal transmission of newly synthesised virus particles. Besides the haemolymph, the silk gland of B. mori provides an additional expression system for recombinant proteins. In this paper, we investigated how silk gland can be efficiently infected by a Autographa californica multicapsid nuclear polyhedrosis virus (AcMNPV). We demonstrated that the viral chitinase and the cysteine protease cathepsin are necessary to permit viral entry into the silk gland cells of intrahaemocoelically infected B. mori larvae. Moreover, for the first time, we showed AcMNPV crossing the basal lamina of silk glands in B. mori larvae, and we assessed a new path of infection of silk gland cells that can be exploited for protein production. PMID:24477386

Wöltje, Michael; Böbel, Melanie; Rheinnecker, Michael; Tettamanti, Gianluca; Franzetti, Eleonora; Saviane, Alessio; Cappellozza, Silvia

2014-05-01

289

Biodegradation of Silk Biomaterials  

OpenAIRE

Silk fibroin from the silkworm, Bombyx mori, has excellent properties such as biocompatibility, biodegradation, non-toxicity, adsorption properties, etc. As a kind of ideal biomaterial, silk fibroin has been widely used since it was first utilized for sutures a long time ago. The degradation behavior of silk biomaterials is obviously important for medical applications. This article will focus on silk-based biomaterials and review the degradation behaviors of silk materials.

Bochu Wang; Yang Cao

2009-01-01

290

Biodegradation of Silk Biomaterials  

Directory of Open Access Journals (Sweden)

Full Text Available Silk fibroin from the silkworm, Bombyx mori, has excellent properties such as biocompatibility, biodegradation, non-toxicity, adsorption properties, etc. As a kind of ideal biomaterial, silk fibroin has been widely used since it was first utilized for sutures a long time ago. The degradation behavior of silk biomaterials is obviously important for medical applications. This article will focus on silk-based biomaterials and review the degradation behaviors of silk materials.

Bochu Wang

2009-03-01

291

Silk fibroin nanoparticles constitute a vector for controlled release of resveratrol in an experimental model of inflammatory bowel disease in rats  

Science.gov (United States)

Purpose We aimed to evaluate the intestinal anti-inflammatory properties of silk fibroin nanoparticles, around 100 nm in size, when loaded with the stilbene compound resveratrol, in an experimental model of rat colitis. Methods Nanoparticles were loaded with resveratrol by adsorption. The biological effects of the resveratrol-loaded nanoparticles were tested both in vitro, in a cell culture of RAW 264.7 cells (mouse macrophages), and in vivo, in the trinitrobenzenesulfonic acid model of rat colitis, when administered intracolonically. Results The resveratrol liberation in 1× phosphate-buffered saline (PBS; pH 7.4) was characterized by fast liberation, reaching the solubility limit in 3 hours, which was maintained over a period of 80 hours. The in vitro assays revealed immunomodulatory properties exerted by these resveratrol-loaded nanoparticles since they promoted macrophage activity in basal conditions and inhibited this activity when stimulated with lipopolysaccharide. The in vivo experiments showed that after evaluation of the macroscopic symptoms, inflammatory markers, and intestinal barrier function, the fibroin nanoparticles loaded with resveratrol had a better effect than the single treatments, being similar to that produced by the glucocorticoid dexamethasone. Conclusion Silk fibroin nanoparticles constitute an attractive strategy for the controlled release of resveratrol, showing immunomodulatory properties and intestinal anti-inflammatory effects. PMID:25285004

Lozano-Pérez, Antonio Abel; Rodriguez-Nogales, Alba; Ortiz-Cullera, Víctor; Algieri, Francesca; Garrido-Mesa, José; Zorrilla, Pedro; Rodriguez-Cabezas, M Elena; Garrido-Mesa, Natividad; Utrilla, M Pilar; De Matteis, Laura; de la Fuente, Jesús Martínez; Cenis, José Luis; Gálvez, Julio

2014-01-01

292

Macromolecular array patterns of silk gland secretion in social Hymenoptera larvae.  

Science.gov (United States)

The cocoon, produced by most holometabolous insects, is built with silk that is usually produced by the larval salivary gland. Although this silk has been widely studied in the Lepidoptera, its composition and macromolecular arrangement remains unknown in the Hymenoptera. The macromolecular array patterns of the silk in the larval salivary gland of some meliponids, wasps, and ants were analyzed with polarized-light microscopy, and they were compared with those of Bombyx mori (Lepidoptera). There is a birefringent secretion in the glandular lumen of all larvae, due to filamentous structural proteins that display anisotropy. The silk in the distal, middle and proximal regions of the secretory portion of Formicidae and Vespidae glands presented a lattice optical pattern. We found a different pattern in the middle secretory portion of the Meliponini, with a zigzag rather than a lattice pattern. This indicates that the biopolymer fibers begin their macromolecular reorganization at this glandular region, different from the Formicidae and the Vespidae, in which the zigzag optical pattern was only found at the lateral duct. Probably, the mechanism of silk production in the Hymenoptera is a characteristic inherited from a common ancestor of Vespoidea and Sphecoidea; the alterations in the pattern observed in the Meliponini could be a derived characteristic in the Hymenoptera. We found no similarity in the macromolecular reorganization patterns of the silk between the Hymenoptera species and the silkworm. PMID:15614724

Gomes, Guilherme; Silva-Zacarin, Elaine C M; Zara, Fernando J; Silva de Moraes, Regina L M; Caetano, Flávio H

2004-01-01

293

The ESR signals in silk fibroin and wool keratin under both the effect of UV-irradiation and without any external effects and the formation of free radicals.  

Science.gov (United States)

ESR studies have been done on natural and UV-irradiated silk fibroins and wool keratins at the temperature range of -196 degrees C to 20 C. The intensities of ESR signals obtained from the irradiated samples at -196 C remarkably increase with respect to those of natural samples. While the signals mainly consist of triplet peaks at -196 C. a doublet arises around the room temperatures. For the first time, at room temperature without any external effect the complicated ESR spectra of fibrous proteins (wool keratin and silk fibroin) whose components are as follows have been observed: (1) (for white wool keratin) a central doublet with deltaHm = 1.1 mT and g = 2.0075; deltaHm = 5mT and g = 2.1911; (2) a wide peak with deltaHm approximately 66 mT and g approximately 2.1575; (3) the 'sulfur' peak given in the literature with deltaHm = 2.2 mT and g = 2.0218; (4) the signal with deltaHm = 0.6 mT and g = 2.0065, and for silk fibroin, (a) a very wide signal with deltaHm approximately 70 mT and g approximately 2.084; (b) a very sharp signal with deltaHm approximately 1.1 mT and g approximately 2.01; and (c) relatively narrower signal with deltaHm approximately 5 mT and g approximately 2.336. It has been shown by recombination kinetic method that 30-50% of the free radicals formed by UV-irradiation do not undergo recombination up to 220 degrees C and 15 degrees C for silk libroin and wool keratin, respectively, even they keep their concentration constant for long period of time (weeks, months, even longer). In this article, considering above-mentioned results, the mechanism of signals observed in natural wool keratin and silk fibroin without any external effects is examined. We can briefly explain the role of the subject of the article, by considering fibrous proteins and some applications of the reactions by free radical occurring in these proteins tinder the effects of different factors in medicine and biology and the important role of oxidation and the other kinds of degradations on these processes. as well as the significant applications of ESR investigations on comprehending the processes by free radical. PMID:12099283

Mamedov, Sh V; Aktas, B; Cantürk, M; Aksakal, B; Alekperov, V; Bülbül, F; Yilgin, R; Aslanov, R B

2002-08-01

294

The anticoagulant ability of ferulic acid and its applications for improving the blood compatibility of silk fibroin  

International Nuclear Information System (INIS)

The hemocompatibility of silk fibroin (SF) was improved with ferulic acid (FA) by graft polymerization. Ferulic acid is an active ingredient of many Chinese herbal medicines, such as Chuanxiong (Rhizoma ligustici wallichii), Danggui (Angelica sinensis) and Awei (Asafoetida giantfennel), which have been used to treat cardiovascular diseases by Chinese physicians for thousands of years. The inhibitory functions of FA on blood coagulation and erythrocyte agglutination were first characterized by a Lee-White test tube method and a micropipette technique, respectively. Then, FA was immobilized on SF by graft polymerization and the surface composition of modified SF was characterized by attenuated total reflectance Fourier-transform infrared (ATR-FTIR), x-ray photoelectron spectroscopy (XPS) and optical microscopy. The anticoagulant activity of modified SF was assessed, respectively, by in vitro clotting time measurements on a photo-optical clot detection instrument and with the Lee-White test tube method. The test results indicated that in comparison to untreated SF, the anticoagulant activity of modified SF has been improved significantly. Moreover, the SF surface composition is altered by FA but its ?-sheet conformation is not disturbed.

295

Effect of nanofiber content on bone regeneration of silk fibroin/poly(?-caprolactone) nano/microfibrous composite scaffolds.  

Science.gov (United States)

The broad application of electrospun nanofibrous scaffolds in tissue engineering is limited by their small pore size, which has a negative influence on cell migration. This disadvantage could be significantly improved through the combination of nano- and microfibrous structure. To accomplish this, different nano/microfibrous scaffolds were produced by hybrid electrospinning, combining solution electrospinning with melt electrospinning, while varying the content of the nanofiber. The morphology of the silk fibroin (SF)/poly(?-caprolactone) (PCL) nano/microfibrous composite scaffolds was investigated with field-emission scanning electron microscopy, while the mechanical and pore properties were assessed by measurement of tensile strength and mercury porosimetry. To assay cell proliferation, cell viability, and infiltration ability, human mesenchymal stem cells were seeded on the SF/PCL nano/microfibrous composite scaffolds. From in vivo tests, it was found that the bone-regenerating ability of SF/PCL nano/microfibrous composite scaffolds was closely associated with the nanofiber content in the composite scaffolds. In conclusion, this approach of controlling the nanofiber content in SF/PCL nano/microfibrous composite scaffolds could be useful in the design of novel scaffolds for tissue engineering. PMID:25624762

Kim, Beom Su; Park, Ko Eun; Kim, Min Hee; You, Hyung Keun; Lee, Jun; Park, Won Ho

2015-01-01

296

The Effect of Temperatures and Incubation Times on Some Properties of Silk Fibroin/Chitosan Blend Films  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this work was to study the effect of temperatures and incubation times on Silk Fibroin (SF/Chitosan (CS blend films properties. The films were firstly prepared by mixing the SF and CS solution in homogeneously blended, then cast on the polystyrene culture plates before taking into the oven at 40C for 3 days. The obtained SF/CS blend films were treated at 90 and 120C, each for 30, 60 and 90 min, respectively. All of films were characterized for their morphology and secondary structures by using SEM and FTIR, respectively. The results showed that SF/CS films have homogeneous texture without phase separation. However, they also appeared some particles dispersed and embedded on their surfaces. The surfaces of the films slightly increased smooth texture when increased both temperatures and incubation times. The results were also noted that the characteristics were varied by those different temperatures. FTIR spectra indicated that the absorption bands at amide regions (I, II and III of the SF were similar profile. Moreover, treatment the blended films with temperatures resulted to changed the secondary structures of the films. This means the ratio of -sheet were increased. It can be expected that water evaporation by increasing temperature resulted to make the molecules of SF and CS close up and help to form H-bonds between them.

Prasong Srihanam

2011-01-01

297

Development of micro-structural units in the silk fibroin thin films prepared by near-infrared pulsed laser deposition  

Energy Technology Data Exchange (ETDEWEB)

Development of micro-structural units in a silk fibroin (SF) thin film deposited on Si (100) by using 1064 nm pulsed laser beam was examined. The smallest units ranging ca 10-20 nm were always observed in more or less uniformly dispersed states, which we coined as smallest protein units. At the same time, we frequently observed much larger chunks. Formation of such chunks was suppressed by choosing smaller fluence, shorter deposition time or by sputtering intermittently. When the laser fluence does not appreciably exceed the empirically determined threshold of 1.7 J/cm{sup 2}, the basic secondary structure of SF, i.e. anti-parallel {beta}-sheet, was well preserved, as confirmed by Fourier transform infrared spectroscopy. Since the target material exhibits only very small extent of absorption of 1064 nm beam, we suspected that formation of radicals and free electrons and subsequent optical breakdown are mainly responsible for the deposition process, although a number of mechanistic questions remain open. The present near-infrared pulsed laser deposition technique seems attractive since it is free from appreciable damage of the protein secondary structure and solubility of the protein species, and a compact, relatively inexpensive laser source suffices.

Nakayama, S. [Technofarm Axesz Co., Ltd., 4-4-27-703 Aobadai, Meguro, Tokyo 153-0042 (Japan) and Nara Machinery Co., Ltd., 2-5-7, Jounan-jima, Tokyo 143-0002 (Japan)]. E-mail: nakayama@nara-m.co.jp; Nagare, S. [Technofarm Axesz Co., Ltd., 4-4-27-703 Aobadai, Meguro, Tokyo 153-0042 (Japan); Nara Machinery Co., Ltd., 2-5-7, Jounan-jima, Tokyo 143-0002 (Japan); Senna, M. [Technofarm Axesz Co., Ltd., 4-4-27-703 Aobadai, Meguro, Tokyo 153-0042 (Japan); Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Yokohama 223-8522 (Japan)

2006-12-05

298

Development of micro-structural units in the silk fibroin thin films prepared by near-infrared pulsed laser deposition  

International Nuclear Information System (INIS)

Development of micro-structural units in a silk fibroin (SF) thin film deposited on Si (100) by using 1064 nm pulsed laser beam was examined. The smallest units ranging ca 10-20 nm were always observed in more or less uniformly dispersed states, which we coined as smallest protein units. At the same time, we frequently observed much larger chunks. Formation of such chunks was suppressed by choosing smaller fluence, shorter deposition time or by sputtering intermittently. When the laser fluence does not appreciably exceed the empirically determined threshold of 1.7 J/cm2, the basic secondary structure of SF, i.e. anti-parallel ?-sheet, was well preserved, as confirmed by Fourier transform infrared spectroscopy. Since the target material exhibits only very small extent of absorption of 1064 nm beam, we suspected that formation of radicals and free electrons and subsequent optical breakdown are mainly responsible for the deposition process, although a number of mechanistic questions remain open. The present near-infrared pulsed laser deposition technique seems attractive since it is free from appreciable damage of the protein secondary structure and solubility of the protein species, and a compact, relatively inexpensive laser source suffices

299

In vivo biodegradation of porous silk fibroin films implanted beneath the skin and muscle of the rat.  

Science.gov (United States)

Since the bioresorption process has a strong impact not only on the mechanical properties of the biomaterial but also on the extent of tissue regeneration, in vivo biodegradation of absorbable porous biomaterials plays a key role in tissue repair and wound healing. In the present work, porous silk fibroin films (PSFFs) were prepared by a freeze-drying method and then implanted beneath the dorsal skin and the femoral skeletal muscle of the rat. The objective was to study the rate of biodegradation of the PSFFs in different tissues, each with its distinct metabolic rate. In addition we examined the relationship between the biodegradation rate and tissue-regeneration rate semi-quantitatively by incorporating histology, microscopy and image analysis methods. Furthermore, based on our previous findings, we also explored the relationship between in vitro and in vivo rates of biodegradation. The results suggest that the PSFFs experience a similar biodegradation process regardless of the type of tissue in which they are implanted, in spite of the higher metabolic rate of the skeletal muscle. In addition, the in vitro biodegradation rate of the PSFFs was comparable to that of both skin and skeletal muscle, suggesting that an in vitro biodegradation test could be used to predict in vivo performance. PMID:24211965

Guan, Guoping; Wang, Lu; Li, Mingzhong; Bai, Lun

2014-01-01

300

Biomineralization regulation by nano-sized features in silk fibroin proteins: synthesis of water-dispersible nano-hydroxyapatite.  

Science.gov (United States)

In the present study, silk fibroin (SF) was used as a template to prepare nano-hydroxyapatite (nano-HA) via a biomineralization process. We observed that the content of SF affected both the morphology and water dispersibility of nano-HA particles. Scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), zetasizer, and Fourier transform infrared spectroscopy (FTIR) were used to examine nano-HA particle features including the surface morphology, aggregation performance, and crystallization. Rod-like nano-HA particles with desired water dispersibility were achieved when the ratio of SF/HA (calculated) was above 7:3. SEM, TEM, and zeta potential results revealed that nano-HA particles were enclosed by the SF which formed a negative charge layer preventing the aggregation of HA nanoparticles in aqueous solution. Moreover, the nano-HA particles were able to re-disperse in water without precipitation for two weeks at room temperature, 60°C, and 90°C. Our work suggested a facile and effective approach of designing water-dispersible nano-HA particles which may have wide potential application in tissue engineering especially bone regeneration. PMID:24678026

Huang, Xiaowei; Liu, Xi; Liu, Shanshan; Zhang, Aili; Lu, Qiang; Kaplan, David L; Zhu, Hesun

2014-11-01

301

Therapeutic efficacy of antibiotic-loaded gelatin microsphere/silk fibroin scaffolds in infected full-thickness burns.  

Science.gov (United States)

Despite advances in burn treatment, burn infection remains a major cause of morbidity and mortality. In this study, an antibacterial silk fibroin (SF) scaffold for burn treatment was designed; gelatin microspheres (GMs) were impregnated with the antibiotic gentamycin sulfate (GS), and the GS-impregnated GMs were then embedded in a SF matrix to fabricate GS/GM/SF scaffolds. The developed GS/GM/SF scaffolds could serve as a dermal regeneration template in full-thickness burns. The average pore size and porosity of the GS/GM/SF scaffolds were 40-80 ?m and 85%, respectively. Furthermore, the drug release rate of the scaffolds was significantly slower than that of either GS/GM or GS/SF scaffolds. And the composite scaffold exhibited stronger antimicrobial activities against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Hence, we evaluated the wound-healing effects and antibacterial properties of the GS/GM/SF scaffolds in a rat full-thickness burn infection model. Over 21 days, the GS/GM/SF scaffolds not only significantly reduced burn infection by P. aeruginosa but also accelerated the regeneration of the dermis and exhibited higher epithelialization rates than did GS/SF and SF scaffolds. Thus, GS/GM/SF scaffolds are potentially effective for treatment of full-thickness infected burns, and GS/GM/SF scaffolds are a promising therapeutic tool for severely burned patients. PMID:24704698

Lan, Yong; Li, Weichang; Jiao, Yanpeng; Guo, Rui; Zhang, Yi; Xue, Wei; Zhang, Yuanming

2014-07-01

302

Nano-scaled hydroxyapatite/silk fibroin sheets support osteogenic differentiation of rat bone marrow mesenchymal cells  

International Nuclear Information System (INIS)

A novel biomaterial that was composed of nano-scaled sintered hydroxyapatite (HAp) and silk fibroin (SF) was fabricated. We cultured rat marrow mesenchymal cells (MMCs) on this biomaterial (nano-HAp/SF sheet), on bare SF sheets, and on tissue culture polystyrene (TCPS) dishes as controls, then evaluated cell adhesion, proliferation, and differentiation of the MMCs. After 1 h of culture, a large number of viable cells were observed on the nano-HAp/SF sheets in comparison to the controls. In addition, after 3 h of culture, the morphology of the cells on the nano-HAp/SF sheets was quite different from that on the SF sheets. MMCs extrude their cytoplasmic processes to nano-HAp particles and are well attached to the sheets. After 14 days of culture, under osteogenic conditions, the alkaline phosphatase (ALP) activity and bone-specific osteocalcin secretion of the cells on nano-HAp/SF sheets were higher than were those on the controls. These results indicated that the surface of the nano-HAp/SF sheets is covered with appropriate HAp crystal for MMC adhesion/proliferation and that the sheets effectively support the osteogenic differentiation of MMCs. Therefore, the nano-HAp/SF sheet is an effective biomaterial that is applicable in bone reconstruction surgery

303

Nano-scaled hydroxyapatite/silk fibroin sheets support osteogenic differentiation of rat bone marrow mesenchymal cells  

Energy Technology Data Exchange (ETDEWEB)

A novel biomaterial that was composed of nano-scaled sintered hydroxyapatite (HAp) and silk fibroin (SF) was fabricated. We cultured rat marrow mesenchymal cells (MMCs) on this biomaterial (nano-HAp/SF sheet), on bare SF sheets, and on tissue culture polystyrene (TCPS) dishes as controls, then evaluated cell adhesion, proliferation, and differentiation of the MMCs. After 1 h of culture, a large number of viable cells were observed on the nano-HAp/SF sheets in comparison to the controls. In addition, after 3 h of culture, the morphology of the cells on the nano-HAp/SF sheets was quite different from that on the SF sheets. MMCs extrude their cytoplasmic processes to nano-HAp particles and are well attached to the sheets. After 14 days of culture, under osteogenic conditions, the alkaline phosphatase (ALP) activity and bone-specific osteocalcin secretion of the cells on nano-HAp/SF sheets were higher than were those on the controls. These results indicated that the surface of the nano-HAp/SF sheets is covered with appropriate HAp crystal for MMC adhesion/proliferation and that the sheets effectively support the osteogenic differentiation of MMCs. Therefore, the nano-HAp/SF sheet is an effective biomaterial that is applicable in bone reconstruction surgery.

Tanaka, Toshimitsu [Research Institute for Cell Engineering (RICE), National Institute of Advanced Industrial Science and Technology (AIST) 3-11-46 Nakoji, Amagasaki, Hyogo 661-0974 (Japan); First Department of Oral and Maxillofacial Surgery, Tsurumi University School of Dental Medicine, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama, Kanagawa 230-0063 (Japan); Hirose, Motohiro [Research Institute for Cell Engineering (RICE), National Institute of Advanced Industrial Science and Technology (AIST), 3-11-46 Nakoji, Amagasaki, Hyogo 661-0974 (Japan)]. E-mail: motohiro-hirose@aist.go.jp; Kotobuki, Noriko [Research Institute for Cell Engineering (RICE), National Institute of Advanced Industrial Science and Technology (AIST), 3-11-46 Nakoji, Amagasaki, Hyogo 661-0974 (Japan); Ohgushi, Hajime [Research Institute for Cell Engineering (RICE), National Institute of Advanced Industrial Science and Technology (AIST), 3-11-46 Nakoji, Amagasaki, Hyogo 661-0974 (Japan); Furuzono, Tsutomu [Department of Biomedical Engineering, National Cardiovascular Center Research Institute, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565 (Japan); Innovation Plaza Osaka, Japan Science and Technology Agency (JST), 3-1-10 Techno-stage, Izumi, Osaka 594-1144 (Japan); Sato, Junichi [First Department of Oral and Maxillofacial Surgery, Tsurumi University School of Dental Medicine, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama, Kanagawa 230-0063 (Japan)

2007-05-16

304

Effect of nanofiber content on bone regeneration of silk fibroin/poly(?-caprolactone) nano/microfibrous composite scaffolds  

Science.gov (United States)

The broad application of electrospun nanofibrous scaffolds in tissue engineering is limited by their small pore size, which has a negative influence on cell migration. This disadvantage could be significantly improved through the combination of nano- and microfibrous structure. To accomplish this, different nano/microfibrous scaffolds were produced by hybrid electrospinning, combining solution electrospinning with melt electrospinning, while varying the content of the nanofiber. The morphology of the silk fibroin (SF)/poly(?-caprolactone) (PCL) nano/microfibrous composite scaffolds was investigated with field-emission scanning electron microscopy, while the mechanical and pore properties were assessed by measurement of tensile strength and mercury porosimetry. To assay cell proliferation, cell viability, and infiltration ability, human mesenchymal stem cells were seeded on the SF/PCL nano/microfibrous composite scaffolds. From in vivo tests, it was found that the bone-regenerating ability of SF/PCL nano/microfibrous composite scaffolds was closely associated with the nanofiber content in the composite scaffolds. In conclusion, this approach of controlling the nanofiber content in SF/PCL nano/microfibrous composite scaffolds could be useful in the design of novel scaffolds for tissue engineering. PMID:25624762

Kim, Beom Su; Park, Ko Eun; Kim, Min Hee; You, Hyung Keun; Lee, Jun; Park, Won Ho

2015-01-01

305

Creation of macropores in electrospun silk fibroin scaffolds using sacrificial PEO-microparticles to enhance cellular infiltration.  

Science.gov (United States)

Electrospun scaffolds are widely used in tissue engineering; however, a common problem is the poor cell infiltration because of the small pore size and tightly packed structure of these fibrous scaffolds. To address this issue, a novel technique was developed to fabricate electrospun silk fibroin (SF) scaffolds with rather macropores and high porosity using electrospraying-generated PEO microparticles as porogen. The morphology and pore size of MPES scaffolds were evaluated by scanning electron microscopy. It was revealed that MPES scaffold had a relatively loose structure with an increase of mean pore size (i.e., approx. 30 ?m of MPES vs. approx. 5 ?m of traditional electrospun scaffolds (TES) and porosity (i.e., 95% vs. 84% of TES). Culture of mouse 3T3 fibroblast in TES and MPES scaffold revealed that both scaffolds could support cell attachment, spread and proliferation. Yet, cell inflitration in vitro under the static culture condition only occurred in the MPES scaffold. Subcutaneous implantation of scaffolds in rats further confirmed that the tissue ingrowth was more efficient in the MPES scaffold compared to TES scaffold. Thus, the use of PEO microparticles as porogen was a feasible and effective method for creating macroporous electrospun SF scaffold, which provided an alternative to address the limitation of cell infiltration associated with electrospun fibrous scaffold. PMID:23606405

Wang, Kai; Xu, Meng; Zhu, Meifeng; Su, Hong; Wang, Hongjun; Kong, Deling; Wang, Lianyong

2013-12-01

306

New insight into the mechanism underlying fibroin secretion in silkworm, Bombyx mori.  

Science.gov (United States)

In order to investigate the role of different parts of the fibroin heavy chain (H-chain) in the secretion of fibroin in the silk gland of the silkworm (Bombyx mori) in vivo, two enhanced green fluorescent protein (EGFP)/H-chain fusion genes with deduced protein sequences containing an identical N-terminal region and different C-terminal regions of the H-chain were introduced into the B. mori genome using a piggyBac-mediated germline transformation. EGFP fluorescence and molecular analysis showed the products of two different EGFP/H-chain fusion proteins were secreted into the posterior silk gland lumen and aggregated in the middle silk gland and spun into cocoons. The results revealed that only the non-repetitive N terminus of the H-chain is essential for secretion of the H-chain into the posterior silk gland lumen. In addition, our results also indicated that the most likely post-translational modification of the H-chain is at the C-terminal domain. Here, our results not only provide a theoretical basis for the genetic modification of silk fiber as a functional biomaterial but also are of great significance to establishing a new silk gland bioreactor to mass-produce exogenous proteins in an active form. PMID:25302556

Long, Dingpei; Lu, Weijian; Zhang, Yang; Guo, Qing; Xiang, Zhonghuai; Zhao, Aichun

2015-01-01

307

High-performance, low-operating voltage, and solution-processable organic field-effect transistor with silk fibroin as the gate dielectric  

Science.gov (United States)

We report the use of silk fibroin as the gate dielectric material in solution-processed organic field-effect transistors (OFETs) with poly(3-hexylthiophene) (P3HT) as the semiconducting layer. Such OFETs exhibit a low threshold of -0.77 V and a low-operating voltage (0 to -3 V) compatible with the voltage level commonly-used in current electronic industry. The carrier mobility of such OFETs is as high as 0.21 cm2 V-1 s-1 in the saturation regime, comparable to the best value of P3HT-based OFETs with dielectric layer that is not solution-processed. The high-performance of this kind of OFET is related with the high content of ? strands in fibroin dielectric which leads to an array of fibers in a highly ordered structure, thus reducing the trapping sites at the semiconductor/dielectric interface.

Shi, Leilei; Xu, Xinjun; Ma, Mingchao; Li, Lidong

2014-01-01

308

High-performance, low-operating voltage, and solution-processable organic field-effect transistor with silk fibroin as the gate dielectric  

International Nuclear Information System (INIS)

We report the use of silk fibroin as the gate dielectric material in solution-processed organic field-effect transistors (OFETs) with poly(3-hexylthiophene) (P3HT) as the semiconducting layer. Such OFETs exhibit a low threshold of ?0.77?V and a low-operating voltage (0 to ?3 V) compatible with the voltage level commonly-used in current electronic industry. The carrier mobility of such OFETs is as high as 0.21 cm2 V?1 s?1 in the saturation regime, comparable to the best value of P3HT-based OFETs with dielectric layer that is not solution-processed. The high-performance of this kind of OFET is related with the high content of ? strands in fibroin dielectric which leads to an array of fibers in a highly ordered structure, thus reducing the trapping sites at the semiconductor/dielectric interface

309

High-performance, low-operating voltage, and solution-processable organic field-effect transistor with silk fibroin as the gate dielectric  

Energy Technology Data Exchange (ETDEWEB)

We report the use of silk fibroin as the gate dielectric material in solution-processed organic field-effect transistors (OFETs) with poly(3-hexylthiophene) (P3HT) as the semiconducting layer. Such OFETs exhibit a low threshold of ?0.77?V and a low-operating voltage (0 to ?3 V) compatible with the voltage level commonly-used in current electronic industry. The carrier mobility of such OFETs is as high as 0.21 cm{sup 2} V{sup ?1} s{sup ?1} in the saturation regime, comparable to the best value of P3HT-based OFETs with dielectric layer that is not solution-processed. The high-performance of this kind of OFET is related with the high content of ? strands in fibroin dielectric which leads to an array of fibers in a highly ordered structure, thus reducing the trapping sites at the semiconductor/dielectric interface.

Shi, Leilei; Xu, Xinjun, E-mail: xuxj@mater.ustb.edu.cn, E-mail: lidong@mater.ustb.edu.cn; Ma, Mingchao; Li, Lidong, E-mail: xuxj@mater.ustb.edu.cn, E-mail: lidong@mater.ustb.edu.cn [State Key Lab for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

2014-01-13

310

Fabrication and Biocompatibility of Electrospun Silk Biocomposites  

OpenAIRE

Silk fibroin has attracted great interest in tissue engineering because of its outstanding biocompatibility, biodegradability and minimal inflammatory reaction. In this study, two kinds of biocomposites based on regenerated silk fibroin are fabricated by electrospinning and post-treatment processes, respectively. Firstly, regenerated silk fibroin/tetramethoxysilane (TMOS) hybrid nanofibers with high hydrophilicity are prepared, which is superior for fibroblast attachment. The electrospinning ...

Ick-Soo Kim; Byoung-Suhk Kim; Kai Wei

2011-01-01

311

Immobilized lentivirus vector on chondroitin sulfate-hyaluronate acid-silk fibroin hybrid scaffold for tissue-engineered ligament-bone junction.  

Science.gov (United States)

The lack of a fibrocartilage layer between graft and bone remains the leading cause of graft failure after anterior cruciate ligament (ACL) reconstruction. The objective of this study was to develop a gene-modified silk cable-reinforced chondroitin sulfate-hyaluronate acid-silk fibroin (CHS) hybrid scaffold for reconstructing the fibrocartilage layer. The scaffold was fabricated by lyophilizing the CHS mixture with braided silk cables. The scanning electronic microscopy (SEM) showed that microporous CHS sponges were formed around silk cables. Each end of scaffold was modified with lentiviral-mediated transforming growth factor- ? 3 (TGF- ? 3) gene. The cells on scaffold were transfected by bonded lentivirus. In vitro culture demonstrated that mesenchymal stem cells (MSCs) on scaffolds proliferated vigorously and produced abundant collagen. The transcription levels of cartilage-specific genes also increased with culture time. After 2 weeks, the MSCs were distributed uniformly throughout scaffold. Deposited collagen was also found to increase. The chondral differentiation of MSCs was verified by expressions of collagen II and TGF- ? 3 genes in mRNA and protein level. Histology also confirmed the production of cartilage extracellular matrix (ECM) components. The results demonstrated that gene-modified silk cable-reinforced CHS scaffold was capable of supporting cell proliferation and differentiation to reconstruct the cartilage layer of interface. PMID:25019087

Sun, Liguo; Li, Hongguo; Qu, Ling; Zhu, Rui; Fan, Xiangli; Xue, Yingsen; Xie, Zhenghong; Fan, Hongbin

2014-01-01

312

Effects of composite films of silk fibroin and graphene oxide on the proliferation, cell viability and mesenchymal phenotype of periodontal ligament stem cells.  

Science.gov (United States)

In regenerative dentistry, stem cell-based therapy often requires a scaffold to deliver cells and/or growth factors to the injured site. Graphene oxide (GO) and silk fibroin (SF) are promising biomaterials for tissue engineering as they are both non toxic and promote cell proliferation. On the other hand, periodontal ligament stem cells (PDLSCs) are mesenchymal stem cells readily accessible with a promising use in cell therapy. The purpose of this study was to investigate the effects of composite films of GO, SF and GO combined with fibroin in the mesenchymal phenotype, viability, adhesion and proliferation rate of PDLSCs. PDLSCs obtained from healthy extracted teeth were cultured on GO, SF or combination of GO and SF films up to 10 days. Adhesion level of PDSCs on the different biomaterials were evaluated after 12 h of culture, whereas proliferation rate of cells was assessed using the MTT assay. Level of apoptosis was determined using Annexin-V and 7-AAD and mesenchymal markers expression of PDLSCs were analyzed by flow cytometry. At day 7 of culture, MTT experiments showed a high rate of proliferation of PDLSCs growing on GO films compared to the other tested biomaterials, although it was slightly lower than in plastic (control). However PDLSCs growing in fibroin or GO plus fibroin films showed a discrete proliferation. Importantly, at day 10 of culture it was observed a significant increase in PDLSCs proliferation rate in GO films compared to plastic (P cell viability in GO even better than obtained in plastic. Our findings suggest that the combination of human dental stem cells/fibroin/GO based-bioengineered constructs have strong potential for their therapeutic use in regenerative dentistry. PMID:25081645

Rodríguez-Lozano, F J; García-Bernal, D; Aznar-Cervantes, S; Ros-Roca, M A; Algueró, M C; Atucha, N M; Lozano-García, A A; Moraleda, J M; Cenis, J L

2014-12-01

313

Comparable efficacy of silk fibroin with the collagen membranes for guided bone regeneration in rat calvarial defects  

Science.gov (United States)

PURPOSE Silk fibroin (SF) is a new degradable barrier membrane for guided bone regeneration (GBR) that can reduce the risk of pathogen transmission and the high costs associated with the use of collagen membranes. This study compared the efficacy of SF membranes on GBR with collagen membranes (Bio-Gide®) using a rat calvarial defect model. MATERIALS AND METHODS Thirty-six male Sprague Dawley rats with two 5 mm-sized circular defects in the calvarial bone were prepared (n=72). The study groups were divided into a control group (no membrane) and two experimental groups (SF membrane and Bio-Gide®). Each group of 24 samples was subdivided at 2, 4, and 8 weeks after implantation. New bone formation was evaluated using microcomputerized tomography and histological examination. RESULTS Bone regeneration was observed in the SF and Bio-Gide®-treated groups to a greater extent than in the control group (mean volume of new bone was 5.49 ± 1.48 mm3 at 8 weeks). There were different patterns of bone regeneration between the SF membrane and the Bio-Gide® samples. However, the absolute volume of new bone in the SF membrane-treated group was not significantly different from that in the collagen membrane-treated group at 8 weeks (8.75 ± 0.80 vs. 8.47 ± 0.75 mm3, respectively, P=.592). CONCLUSION SF membranes successfully enhanced comparable volumes of bone regeneration in calvarial bone defects compared with collagen membranes. Considering the lower cost and lesser risk of infectious transmission from animal tissue, SF membranes are a viable alternative to collagen membranes for GBR. PMID:25551015

Kim, Jwa-Young; Yang, Byoung-Eun; Ahn, Jin-Hee; Park, Sang O

2014-01-01

314

Electrospun silk fibroin fiber diameter influences in vitro dermal fibroblast behavior and promotes healing of ex vivo wound models  

Science.gov (United States)

Replicating the nanostructured components of extracellular matrix is a target for dermal tissue engineering and regenerative medicine. Electrospinning Bombyx mori silk fibroin (BMSF) allows the production of nano- to microscale fibrous scaffolds. For BMSF electrospun scaffolds to be successful, understanding and optimizing the cellular response to material morphology is essential. Primary human dermal fibroblast response to nine variants of BMSF scaffolds composed of nano- to microscale fibers ranging from ~250 to ~1200 nm was assessed in vitro with regard to cell proliferation, viability, cellular morphology, and gene expression. BMSF support of epithelial migration was then assessed through utilization of a novel ex vivo human skin wound healing model. Scaffolds composed of the smallest diameter fibers, ~250 -300 nm, supported cell proliferation significantly more than fibers with diameters approximately 1 ?m (p < 0.001). Cell morphology was observed to depart from a stellate morphology with numerous cell -fiber interactions to an elongated, fiber-aligned morphology with interaction predominately with single fibers. The expressions of extracellular matrix genes, collagen types I and III (p < 0.001), and proliferation markers, proliferating cell nuclear antigen (p < 0.001), increased with decreasing fiber diameter. The re-epithelialization of ex vivo wound models was significantly improved with the addition of BMSF electrospun scaffolds, with migratory keratinocytes incorporated into scaffolds. BMSF scaffolds with nanofibrous architectures enhanced proliferation in comparison to microfibrous scaffolds and provided an effective template for migratory keratinocytes during re-epithelialization. The results may aid in the development of effective BMSF electrospun scaffolds for wound healing applications PMID:25383171

Hodgkinson, Tom; Yuan, Xue-Feng

2014-01-01

315

The development of injectable gelatin/silk fibroin microspheres for the dual delivery of curcumin and piperine.  

Science.gov (United States)

The objective of this study was to develop the microspheres from gelatin (G) and silk fibroin (SF) aimed to be applied for the controlled release of curcumin and piperine. The glutaraldehyde-crosslinked G/SF microspheres at various weight blending ratios (100/0, 70/30, 50/50, and 30/70) were successfully fabricated by water in oil emulsion technique. The microspheres prepared from all compositions were in a round shape with homogeneous size distribution both in the dried (194-217 ?m) and swollen states (297-367 ?m). When subjected in collagenase solution at physiological condition, the G microspheres gradually degraded within 14 days while the blended G/SF microspheres, particularly at 50/50 and 30/70, were not degraded. For the release application, the microspheres were loaded with curcumin and/or piperine. It was found that the microspheres composed of SF tended to entrap curcumin and piperine with the high entrapment and loading efficiencies, possibly due to their hydrophobic interactions. The G/SF microspheres, particularly at the ratios of 50/50 and 30/70, released curcumin and piperine in a sustained manner both for the single and dual release systems. The controlled dual release of curcumin and piperine from the G/SF microspheres would prolong their half-life, provide the optimal concentrations for therapeutic effects at a target site, and improve the bioavailability of curcumin. These novel injectable microspheres dually releasing curcumin and piperine would be introduced for the treatment of diseases without the need of operation. PMID:24186150

Ratanavaraporn, Juthamas; Kanokpanont, Sorada; Damrongsakkul, Siriporn

2014-02-01

316

DNA Synthesis in the Giant Nuclei of Insects - Control Machinery and Structures Observed in the Silk-Producing Gland of Bombyx Mori  

International Nuclear Information System (INIS)

The existence in many insect organs of giant nuclei without visible chromosomes raises the question of possible homologies between the chromatin structures of these nuclei and those of polytene nuclei or common euploid cells. Studies have been made of the nuclei in the silk-producing gland of Bombyx mori. The DNA synthesis is cyclic. During the third stage there are three successive synthesis cycles, which appear to be relatively autonomous in the individual nuclei. For more than 24 hours after moulting, however, synthesis is greatly reduced; moulting factors thus cause synchronization of all the nuclei. This leads to the conclusion that the triggering of a synthesis cycle is controlled by general factors external to the cell. At the end of larval development, DNA synthesis is suspended at the moment when large-scale secretion of silk begins. Evaluation of the pool of endogenic precursors of DNA shows that it is considerably reduced at the end of the DNA synthesis period. The hypothesis proposed is that large-scale synthesis of fibroin requires polarization of the metabolism, hence the depletion of the nucleotide pool and the end of DNA synthesis. DNA synthesis within a single nucleus is to some extent asynchronic. In particular, a well-defined, delayed-synthesis structure visible only in the female seems to be a possible homologue of a sex chromosome. Other asynchronisms are also apparent, though less clearly. Functional studies thus allow the supposition that in theies thus allow the supposition that in the giant nucleus replication units retain an individuality comparable to that of a polytene chromosome. These observations together lead to the conclusion that a nucleus in the silk-producing gland has physiological and structural characteristics similar to those of a polytene nucleus, differing from it essentially in the lesser degree of condensation of its structures. (author)

317

The extraction of fibroin protein from Bombyx mori silk cocoon: Optimization of process parameters  

Directory of Open Access Journals (Sweden)

Full Text Available Optimization of protein extraction using silk cocoon was carried out by the design of experiment(DOE to obtain the response surface methodology ( RSM . Box-Behnken rotatable design was used tocreate an experimental program to provide data to model the effects of various factors on protein extractionefficiency. The variables chosen were sodium carbonate concentration ( 1 X , Lithum bromide concentration( 2 X and temperature ( 3 X . The mathematical relationship between protein extraction efficiency and threesignificant independent variables can be approximated by a second order quadratic model. RSM wasused to describe the individual and interactive effects of three variables at three levels, combined accordingto a Box-Behnken Design. The coefficient of determination (2 R for the model is 0.9761. Probability value( P < 0.0001 demonstrates a very high significance for the regression model indicating that Box-BehnkenDesign can be applied to the protein extraction from silk cocoon, and it is an economical way of obtainingthe maximum amount of information with the fewest experiments.

Mahesh Kumar Sah

2010-06-01

318

Hox transcription factor Antp regulates sericin-1 gene expression in the terminal differentiated silk gland of Bombyx mori.  

Science.gov (United States)

Hox genes are well-known master regulators in developmental morphogenesis along the anteroposterior axis of animals. However, the molecular mechanisms by which Hox proteins regulate their target genes and determine cell fates are not fully understood. The silk gland of Bombyx mori is a tubular tissue divided into several subparts along the anteroposterior axis, and the silk genes are expressed with specific patterns. The sericin-1 gene (ser1) is expressed in the middle silk gland (MSG) with sublocal specificity. Here we show that the Hox protein Antp is a component of the middle silk gland-specific complex, MIC (MSG-intermolt-specific complex), binds to the essential promoter element of ser1, and activates its expression. Ectopic expression of Antp in transgenic silkworms induced the expression of ser1 in the posterior silk gland (PSG), but not in the anterior part of MSG (MSG-A). Correspondingly, a MIC-like complex was formed by the addition of recombinant Antp in extracts from PSG with its cofactors Exd and Hth, but not in extracts from MSG-A. Splicing patterns of ser1 mRNA induced by the ectopic expression of Antp in PSG were almost the same as those in MSG at the fifth instar and altered depending on the induction timing of Antp. Other Hox genes were expressed with sublocal specificity in the silk gland. The Bombyx silk gland might provide a useful system for understanding how Hox proteins select and regulate their target genes. PMID:24333180

Kimoto, Mai; Tsubota, Takuya; Uchino, Keiro; Sezutsu, Hideki; Takiya, Shigeharu

2014-02-01

319

Silk fibroins modify the atmospheric low temperature plasma-treated poly (3-hydroxybutyrate-co-3-hydroxyhexanoate film for the application of cardiovascular tissue engineering  

Directory of Open Access Journals (Sweden)

Full Text Available Tissue engineered scaffold is one of the hopeful therapies for the patients with organ or tissue damages. The key element for a tissue engineered scaffold material is high biocompatibility. Herein the poly (3-hydroxybutyrate-co-3-hydroxyhexanoate (PHBHHx film was irradiated by the low temperature atmospheric plasma and then coated by the silk fibroins (SF. After plasma treatment, the surface of PHBHHx film became rougher and more hydrophilic than that of original film. The experiment of PHBHHx flushed by phosphate buffer solution (PBS proves that the coated SF shows stronger immobilization on the plasma-treated film than that on the untreated film. The cell viability assay demonstrates that SF-coated PHBHHx films treated by the plasma significantly supports the proliferation and growth of the human smooth muscle cells (HSMCs. Furthermore, the scanning electron microscopy and hemotoylin and eosin (HE staining show that HSMCs formed a cell sub-monolayer and secreted a large amount of extracellular matrix (ECM on the films after one week's culture. The silk fibroins modify the plasma-treated PHBHHx film, providing a material potentially applicable in the cardiovascular tissue engi-neering.

Huaxiao Yang

2010-12-01

320

Morphology and composition of the spider major ampullate gland and dragline silk.  

Science.gov (United States)

Spider silk is made of unique proteins-spidroins-secreted and stored as a protein solution (dope) in specialized glands. The major ampullate gland, source of the dragline silk, is composed of a tail, a sac and an elongated duct. For this gland, several different types of epithelial cells and granules have been described, but it is largely unknown how they correlate with spidroin production. It is also not settled what parts of the large spidroins end up in the final silk, and it has been suggested that the N-terminal domain (NT) is lacking. Here we show that NT is present in the dope and throughout dragline silk fibers, including the skin layer, and that the major ampullate tail and sac consist of three different and sharply demarcated zones (A-C), each with a distinct epithelial cell type. Finally, we show that spidroins are produced in the A and B zone epithelia, while the C zone granules lack spidroins. PMID:23837699

Andersson, Marlene; Holm, Lena; Ridderstråle, Yvonne; Johansson, Jan; Rising, Anna

2013-08-12

321

GC/MS-based metabolomic studies reveal key roles of glycine in regulating silk synthesis in silkworm, Bombyx mori.  

Science.gov (United States)

Metabolic profiling of silkworm, especially the factors that affect silk synthesis at the metabolic level, is little known. Herein, metabolomic method based on gas chromatography-mass spectrometry was applied to identify key metabolic changes in silk synthesis deficient silkworms. Forty-six differential metabolites were identified in Nd group with the defect of silk synthesis. Significant changes in the levels of glycine and uric acid (up-regulation), carbohydrates and free fatty acids (down-regulation) were observed. The further metabolomics of silk synthesis deficient silkworms by decreasing silk proteins synthesis using knocking out fibroin heavy chain gene or extirpating silk glands operation showed that the changes of the metabolites were almost consistent with those of the Nd group. Furthermore, the increased silk yields by supplying more glycine or its related metabolite confirmed that glycine is a key metabolite to regulate silk synthesis. These findings provide important insights into the regulation between metabolic profiling and silk synthesis. PMID:25533535

Chen, Quanmei; Liu, Xinyu; Zhao, Ping; Sun, Yanhui; Zhao, Xinjie; Xiong, Ying; Xu, Guowang; Xia, Qingyou

2015-02-01

322

Genome editing of BmFib-H gene provides an empty Bombyx mori silk gland for a highly efficient bioreactor.  

Science.gov (United States)

Evolution has produced some remarkable creatures, of which silk gland is a fascinating organ that exists in a variety of insects and almost half of the 34,000 spider species. The impressive ability to secrete huge amount of pure silk protein, and to store proteins at an extremely high concentration (up to 25%) make the silk gland of Bombyx mori hold great promise to be a cost-effective platform for production of recombinant proteins. However, the extremely low production yields of the numerous reported expression systems greatly hindered the exploration and application of silk gland bioreactors. Using customized zinc finger nucleases (ZFN), we successfully performed genome editing of Bmfib-H gene, which encodes the largest and most abundant silk protein, in B. mori with efficiency higher than any previously reported. The resulted Bmfib-H knocked-out B. mori showed a smaller and empty silk gland, abnormally developed posterior silk gland cells, an extremely thin cocoon that contain only sericin proteins, and a slightly heavier pupae. We also showed that removal of endogenous Bmfib-H protein could significantly increase the expression level of exogenous protein. Furthermore, we demonstrated that the bioreactor is suitable for large scale production of protein-based materials. PMID:25359576

Ma, Sanyuan; Shi, Run; Wang, Xiaogang; Liu, Yuanyuan; Chang, Jiasong; Gao, Jie; Lu, Wei; Zhang, Jianduo; Zhao, Ping; Xia, Qingyou

2014-01-01

323

Development of novel electrospun nanofibrous scaffold from P. ricini and A. mylitta silk fibroin blend with improved surface and biological properties.  

Science.gov (United States)

Biomaterials that stimulate cell attachment and proliferation without any surface modification (e.g. RGD coating) provide potent and cost effective scaffold for regenerative medicine. This study assessed the physico-chemical properties and cell supportive potential of a silk fibroin blend scaffold derived from eri (Philosamia ricini) and tasar (Antheraea mylitta) silk (ET) respectively by electrospinning process. The scanning electron microscopy and transmission electron microscopy study found that the fiber diameters are in 200 to 800nm range with flat morphology. The porosity of ET scaffold is found to be 79±5% with majority of pore diameter between 2.5 to 5nm. Similarly, Bombyx mori (BM) silk fibroin and gelatin nanofibrous scaffolds were prepared and taken as control. The ultimate tensile strength of the ET and BM scaffold are found to be 1.83±0.13MPa and 1.47±0.10MPa respectively. The measured contact angle (a measure of hydrophilicity) for ET (54.7°±1.8°) is found to be lower than BM (62°±2.3°). The ability to deposit apatite over ET is comparable to that of BM nanofibers. All the scaffolds were seeded with cord blood derived mesenchymal stem cells (hMSCs) and cultured for 14days in vitro. The immunofluorescence study reveals enhanced cell attachment with higher metabolic activity for MSCs grown over ET than BM and gelatin. The ET scaffold also demonstrated expression of higher amount cell adhesion molecules (CD29/CD44) and higher proliferation rate than BM and gelatin as confirmed by MTT assay, DNA content estimation assay, flow cytometry study and SEM study. Overall, it may be concluded that ET scaffold may have potential in developing bone tissue grafts for clinical applications in the future. PMID:25579953

Panda, N; Bissoyi, A; Pramanik, K; Biswas, A

2015-03-01

324

In vitro and in vivo studies on the cytotoxicity of irradiated silk fibroin against mouse melanoma tumor cell  

Energy Technology Data Exchange (ETDEWEB)

The physicochemical properties of proteins can be altered by irradiation. But, it is rarely that the researches on the functional properties of irradiated proteins have been reported. Fibroin is a fibrous protein derived from silkworm Bombyx mori and has been suggested as a biomaterial for biomedical application. Therefore, fibroin was selected as a model protein and was examined with the irradiation effects on the cytotoxicity of fibroin on tumor cell. The cytotoxicity of fibroin against mouse melanoma cell (B16BL6) showed a significant increase dependent upon the increase of irradiation dose. And also, the splenocyte proliferation activities of fibroin were increased by gamma irradiation. In addition, the oral administration of irradiated fibroin significantly increased the inhibition rate of tumor growth in tumor-bearing mouse model. The reason might be due to the change of protein structure by gamma irradiation and is being studied. From these result, it could be concluded that the irradiated fibroin might be a potential candidate as a valuable product in food and medical industry.

Byun, Eui-Baek [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Division of Bioresources and Biosciences, Faculty of Agriculture, Graduate school of Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Sung, Nak-Yun [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Kwon, Sun-Kyu [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Graduate school of Food and Biotechnology, Korea University, Jochiwon 339-800 (Korea, Republic of); Song, Beom-Seok; Kim, Jae-Hun; Choi, Jong-il [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Hwang, Han-Joon [Graduate school of Food and Biotechnology, Korea University, Jochiwon 339-800 (Korea, Republic of); Byun, Myung-Woo [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Lee, Ju-Woon [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)], E-mail: sjwlee@kaeri.re.kr

2009-07-15

325

In vitro and in vivo studies on the cytotoxicity of irradiated silk fibroin against mouse melanoma tumor cell  

International Nuclear Information System (INIS)

The physicochemical properties of proteins can be altered by irradiation. But, it is rarely that the researches on the functional properties of irradiated proteins have been reported. Fibroin is a fibrous protein derived from silkworm Bombyx mori and has been suggested as a biomaterial for biomedical application. Therefore, fibroin was selected as a model protein and was examined with the irradiation effects on the cytotoxicity of fibroin on tumor cell. The cytotoxicity of fibroin against mouse melanoma cell (B16BL6) showed a significant increase dependent upon the increase of irradiation dose. And also, the splenocyte proliferation activities of fibroin were increased by gamma irradiation. In addition, the oral administration of irradiated fibroin significantly increased the inhibition rate of tumor growth in tumor-bearing mouse model. The reason might be due to the change of protein structure by gamma irradiation and is being studied. From these result, it could be concluded that the irradiated fibroin might be a potential candidate as a valuable product in food and medical industry.

326

New application of silk protein  

International Nuclear Information System (INIS)

Gunma prefecture is famous for sericulture and silk textile industry district in Japan. In Gunma prefecture, some kinds of new generation silk as high performance and high quality silk were developed. These silk are used not only for the new textile materials but also for new industrial materials. New application of silk protein, fibroin and sericin, is considered. (author)

327

New application of silk protein  

Energy Technology Data Exchange (ETDEWEB)

Gunma prefecture is famous for sericulture and silk textile industry district in Japan. In Gunma prefecture, some kinds of new generation silk as high performance and high quality silk were developed. These silk are used not only for the new textile materials but also for new industrial materials. New application of silk protein, fibroin and sericin, is considered. (author)

Kamiishi, Youichi [Textile Research Institute of Gunma, Kiryu, Gunma (Japan)

2000-03-01

328

Purification and some properties of G-factor from the silk gland of silkworm  

International Nuclear Information System (INIS)

Purification of G-factor from the silk gland of silkworms and some of its properties have been studied in comparison with the G-factor from E. coli and rat liver transferase II. In the experiment, GTP-?-32P was prepared from GDP and 32Pi by photophosphorylation with spinach chloroplasts, and purified by Dowex-1 chromatography. The purified G-factor was homogeneous on disc gel electrophoresis. Molecular weight of 80,000 was estimated from a calibrated Sephadex G-200 column. The purified G-factor exhibited uncoupled ribosome-dependent GTPase activity, and was inhibited by fusidic acid, SH inhibitor, and diphtheria toxin plus NAD. The G-factor from E. coli and that from the silk gland were not interchangeable in GTPase reaction. (Yamanoto, Y.)

329

Regeneration of high-quality silk fibroin fiber by wet spinning from CaCl2-formic acid solvent.  

Science.gov (United States)

Silks spun by silkworms and spiders feature outstanding mechanical properties despite being spun under benign conditions. The superior physical properties of silk are closely related to its complicated hierarchical structures constructed from nanoscale building blocks, such as nanocrystals and nanofibrils. Here, we report a novel silk dissolution behavior, which preserved nanofibrils in CaCl2-formic acid solution, that enables spinning of high-quality fibers with a hierarchical structure. This process is characterized by simplicity, high efficiency, low cost, environmental compatibility and large-scale industrialization potential, as well as having utility and potential for the recycling of silk waste and the production of silk-based functional materials. PMID:25281787

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

2015-01-15

330

Functional analysis of 30K proteins during silk gland degeneration by a caspase-dependent pathway in Bombyx.  

Science.gov (United States)

The 30K proteins are involved with important functions in the growth and development of Bombyx mori. In this study, the synthesis and regulation of 30K proteins were examined during the degeneration of Bombyx silk glands. On day 3 of the fifth instar, the protein level of 30Kc19 was low, whereas the silk proteins were rapidly synthesized. However, synthesis and accumulation of the 30Kc19 protein significantly increased at the prepupal stage and on day 1 of the pupal stage. At this stage, the silk gland cells were filled with 30Kc19 and genomic DNA. Moreover, the transcript levels of the 30K-encoding genes, including 30Kc6, 30Kc12, 30Kc19 and 30Kc23 were up-regulated during the degeneration of the Bombyx silk glands. During the time that the levels of the 30Kc19 protein were significantly up-regulated, it is notable that the transcript levels of the BmAtg8, BmAtg6 and BmDronc genes dramatically increased to regulate the programmed cell death of this gland. On day 1 of the pupal stage, intense fragmentation of genomic DNA occurred in the silk gland cells, and the putative active form of caspase was detected in the cytoplasm, showing the complete degradation of the silk glands in one day. In conclusion, the 30K proteins are synthesized in high concentrations, while proteolysis mediates silk gland degeneration in Bombyx by a caspase-dependent pathway. We propose that the 30K proteins may be nutrients and energy vectors to be absorbed by the developing tissues of pupae or moths. PMID:23496335

Ji, M-M; Liu, A-Q; Gan, L-P; Xing, R; Wang, H; Sima, Y-H; Xu, S-Q

2013-06-01

331

Silk fibroin immobilization on poly(ethylene terephthalate) films: Comparison of two surface modification methods and their effect on mesenchymal stem cells culture  

International Nuclear Information System (INIS)

Silk fibroin (SF) has played a curial role for the surface modification of conventional materials to improve the biocompatibility, and SF modified poly(ethylene terephthalate) (PET) materials have potential applications on tissue engineering such as artificial ligament, artificial vessel, artificial heart valve sewing cuffs dacron and surgical mesh engineering. In this work, SF was immobilized onto PET film via two different methods: 1) plasma pretreatment followed by SF dip coating (PET-SF) and 2) plasma-induce acrylic acid graft polymerization and subsequent covalent immobilization of SF on PET film (PET-PAA-SF). It could be found that plasma treatment provided higher surface roughness which was suitable for further SF dip coating, while grafted poly(acrylic acid) (PAA) promised the covalent bonding between SF and PAA. ATR-FTIR adsorption band at 3284 cm?1, 1623 cm?1 and 1520 cm?1 suggested the successful introduction of SF onto PET surface, while the amount of immobilized SF of PET-SF was higher than PET-PAA-SF according to XPS investigation (0.29 vs 0.23 for N/C ratio). Surface modified PET film was used as substrate for mesenchymal stem cells (MSCs) culture, the cells on PET-SF surface exhibited optimum density compared to PET-PAA-SF according to CCK-8 assays, which indicated that plasma pretreatment followed by SF dip coating was a simple and effective way to prepare biocompatible PET surface. Highlights: ? Silk fibroins were immobilized onto PET films with or without the linker of PAA. ? Various techniques were performed to characterize the modified surfaces ? Plasma treatment followed by SF dip coating introduced more SF onto PET films. ? Compare to PET-PAA-SF, PET-SF has better biocompatibility base on MSCs culture

332

Silk fibroin immobilization on poly(ethylene terephthalate) films: Comparison of two surface modification methods and their effect on mesenchymal stem cells culture  

Energy Technology Data Exchange (ETDEWEB)

Silk fibroin (SF) has played a curial role for the surface modification of conventional materials to improve the biocompatibility, and SF modified poly(ethylene terephthalate) (PET) materials have potential applications on tissue engineering such as artificial ligament, artificial vessel, artificial heart valve sewing cuffs dacron and surgical mesh engineering. In this work, SF was immobilized onto PET film via two different methods: 1) plasma pretreatment followed by SF dip coating (PET-SF) and 2) plasma-induce acrylic acid graft polymerization and subsequent covalent immobilization of SF on PET film (PET-PAA-SF). It could be found that plasma treatment provided higher surface roughness which was suitable for further SF dip coating, while grafted poly(acrylic acid) (PAA) promised the covalent bonding between SF and PAA. ATR-FTIR adsorption band at 3284 cm{sup ?1}, 1623 cm{sup ?1} and 1520 cm{sup ?1} suggested the successful introduction of SF onto PET surface, while the amount of immobilized SF of PET-SF was higher than PET-PAA-SF according to XPS investigation (0.29 vs 0.23 for N/C ratio). Surface modified PET film was used as substrate for mesenchymal stem cells (MSCs) culture, the cells on PET-SF surface exhibited optimum density compared to PET-PAA-SF according to CCK-8 assays, which indicated that plasma pretreatment followed by SF dip coating was a simple and effective way to prepare biocompatible PET surface. Highlights: ? Silk fibroins were immobilized onto PET films with or without the linker of PAA. ? Various techniques were performed to characterize the modified surfaces ? Plasma treatment followed by SF dip coating introduced more SF onto PET films. ? Compare to PET-PAA-SF, PET-SF has better biocompatibility base on MSCs culture.

Liang, Meini; Yao, Jinrong; Chen, Xin; Huang, Lei; Shao, Zhengzhong, E-mail: zzshao@fudan.edu.cn

2013-04-01

333

Mechanism of silk processing in insects and spiders  

Science.gov (United States)

Silk spinning by insects and spiders leads to the formation of fibres that exhibit high strength and toughness. The lack of understanding of the protein processing in silk glands has prevented the recapitulation of these properties in vitro from reconstituted or genetically engineered silks. Here we report the identification of emulsion formation and micellar structures from aqueous solutions of reconstituted silkworm silk fibroin as a first step in the process to control water and protein-protein interactions. The sizes (100-200nm diameter) of these structures could be predicted from hydrophobicity plots of silk protein primary sequence. These micelles subsequently aggregated into larger `globules' and gel-like states as the concentration of silk fibroin increased, while maintaining solubility owing to the hydrophilic regions of the protein interspersed among the larger hydrophobic regions. Upon physical shearing or stretching structural transitions, increased birefringence and morphological alignment were demonstrated, indicating that this process mimics the behaviour of similar native silk proteins in vivo. Final morphological features of these silk materials are similar to those observed in native silkworm fibres.

Jin, Hyoung-Joon; Kaplan, David L.

2003-08-01

334

Silk fibroin nanoparticles constitute a vector for controlled release of resveratrol in an experimental model of inflammatory bowel disease in rats  

Directory of Open Access Journals (Sweden)

Full Text Available Antonio Abel Lozano-Pérez,1 Alba Rodriguez-Nogales,2 Víctor Ortiz-Cullera,1 Francesca Algieri,2 José Garrido-Mesa,2 Pedro Zorrilla,2 M Elena Rodriguez-Cabezas,2 Natividad Garrido-Mesa,2 M Pilar Utrilla,2 Laura De Matteis,3 Jesús Martínez de la Fuente,3 José Luis Cenis,1 Julio Gálvez2 1Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario, Murcia, Spain; 2Centro de Investigaciones Biomédicas en Red – Enfermedades Hepáticas y Digestivas, Department of Pharmacology, ibs Granada, Center for Biomedical Research, University of Granada, Granada, Spain; 3Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain Purpose: We aimed to evaluate the intestinal anti-inflammatory properties of silk fibroin nanoparticles, around 100 nm in size, when loaded with the stilbene compound resveratrol, in an experimental model of rat colitis. Methods: Nanoparticles were loaded with resveratrol by adsorption. The biological effects of the resveratrol-loaded nanoparticles were tested both in vitro, in a cell culture of RAW 264.7 cells (mouse macrophages, and in vivo, in the trinitrobenzenesulfonic acid model of rat colitis, when administered intracolonically.Results: The resveratrol liberation in 1× phosphate-buffered saline (PBS; pH 7.4 was characterized by fast liberation, reaching the solubility limit in 3 hours, which was maintained over a period of 80 hours. The in vitro assays revealed immunomodulatory properties exerted by these resveratrol-loaded nanoparticles since they promoted macrophage activity in basal conditions and inhibited this activity when stimulated with lipopolysaccharide. The in vivo experiments showed that after evaluation of the macroscopic symptoms, inflammatory markers, and intestinal barrier function, the fibroin nanoparticles loaded with resveratrol had a better effect than the single treatments, being similar to that produced by the glucocorticoid dexamethasone. Conclusion: Silk fibroin nanoparticles constitute an attractive strategy for the controlled release of resveratrol, showing immunomodulatory properties and intestinal anti-inflammatory effects. Keywords: immunomodulatory, cytokines, TNBS rat colitis, RAW 264.7 macrophage cells, antioxidant

Lozano-Pérez AA

2014-09-01

335

Enhancement of osseointegration of polyethylene terephthalate artificial ligament by coating of silk fibroin and depositing of hydroxyapatite  

Science.gov (United States)

Background Application of artificial ligament in anterior cruciate ligament reconstruction is one of the research focuses of sports medicine but the biological tendon–bone healing still remains a problem. The preliminary study of hydroxyapatite (HAP) coating on the polyethylene terephthalate (PET) surface could effectively induce the osteoblast differentiation, but the tendon–bone healing was still not stable. As a green synthesis process, the biomimetic mineralization can simulate the natural bone growth in vitro and in vivo. Methods HAP crystals were grown under the guide of silk fibroin (SF) PET surface by biomimetic route. Several techniques including scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy were utilized for proving the introduction of both SF and HAP. The viability and osseointegration of bone marrow stromal cells on the surface of three kinds of ligament, including PET group (non-coating group), PET+SF group (SF-coating group), and PET+SF+HAP group (combined HAP- and SF-coating group), were analyzed by CCK-8 assays and alkaline phosphatase (ALP) detection. Seventy-two mature male New Zealand rabbits were randomly divided into three groups. Among them, 36 rabbits were sacrificed for mechanical testing, and histological examination for the others. Results The SF and SF+HAP were successfully coated on the surface of PET fiber. The CCK-8 assay showed that the cell proliferation on PET+SF+HAP group was better than the other two groups from 24 to 120 hours. After 14 days of culture, the cells in the PET+SF+HAP group delivered higher levels of ALP than the other two groups. After 3 days of culture, the expression level of integrin ?1 in the PET+SF+HAP group and PET+SF group were higher than in the PET group. The mean load to failure and the stiffness value of the PET+SF+HAP group were both higher than the other two groups. Hematoxylin and eosin staining showed that new bone tissue formation was only found in the PET+SF+HAP group 8 weeks postoperatively. Masson staining showed that in the PET+SF+HAP group 8 weeks postoperatively, the PET fibers were almost completely encircled by collagen. Histomorphometric analysis showed that the width of the graft–bone interface in the PET+SF+HAP group was narrower than that in the other two groups 4 and 8 weeks postoperatively. The mRNA level of BMP-7 in the PET+SF+HAP groups was significantly higher than those in the other two groups 4 and 8 weeks postoperatively. Conclusion The study showed that the combined SF and HAP coating by biomimetic route on the surface of PET artificial ligament could induce graft osseointegration in the bone tunnel, providing theoretical and experimental foundation for manufacturing novel artificial ligaments meeting the clinical needs. PMID:25302023

Jiang, Jia; Wan, Fang; Yang, Jianjun; Hao, Wei; Wang, Yaxian; Yao, Jinrong; Shao, Zhengzhong; Zhang, Peng; Chen, Jun; Zhou, Liang; Chen, Shiyi

2014-01-01

336

The cardiomyogenic differentiation of rat mesenchymal stem cells on silk fibroin-polysaccharide cardiac patches in vitro.  

Science.gov (United States)

Polysaccharides and proteins profoundly impact the development and growth of tissues in the natural extra-cellular matrix (ECM). To mimic a natural ECM, polysaccharides were incorporated to/or co-sprayed with silk fibroin (SF) to produce SF/chitosan (CS) or SF/CS-hyaluronic acid (SF/CS-HA) microparticles that were further processed by mechanical pressing and genipin cross-linking to produce hybrid cardiac patches. The ATR-FTIR spectra confirm the co-existence of CS or CS-HA and SF in microparticles and patches. For evaluating the cellular responses of rMSCs to the SF/CS and SF/CS-HA cardiac patches, the growth of rMSCs and cardiomyogenic differentiation of 5-aza inducing rMSCs cultured on patches was examined. First, the isolated rMSCs were identified with various positive and negative surface markers such as CD 44 and CD 31 by a flow cytometric technique, respectively. For examining the growth of rMSCs on the patches, MTT viability assay was performed, and the results demonstrated that the growth of rMSCs on SF and SF-hybrid patches significantly exceeded (P<0.001) that on culture wells after seven days of cultivation. Additionally, the relative growth rates of rMSCs on SF/CS and SF/CS-HA hybrid patches were significantly better (P<0.01) than that on SF patches that were also observed by using vimentin stain to the cells. For instance, the relative cell growth rates (%) in cell culture wells, SF, SF/CS and SF/CS-HA patches were 100%, 282.9+/-6.5%, 337.0+/-8.0% and 332.6+/-6.6% (n=6, for all), respectively. For investigating the effects of the hybrid patches on cardiomyogenic differentiation of 5-aza inducing rMSCs, the expressions of specific cardiac genes of cells such as Gata4 and Nkx2.5 were examined by real-time quantitative polymerase chain reaction (real-time PCR) analysis. The results of cardiomyogenic differentiation of induced rMSCs on SF/CS and SF/CS-HA hybrid patches significantly improved the expressions of cardiac genes of Gata4, Nkx2.5, Tnnt2 and Actc1 genes (all, P<0.01 or better, n=3) than those on SF patches and culture wells. Interestingly, the results of cardiac gene expressions of the cells on the SF/CS-HA hybrid patches were the most pronounced in promoting cardiomyogenic differentiations in this investigation. Furthermore, immunofluorescence staining of cardiac proteins such as cardiotin and connexin 43 for induced rMSCs cultured on SF/CS and SF/CS-HA hybrid patches were much pronounced compared with SF patches, indicating the improvements of cardiomyogenic differentiation on the hybrid patches. The results of this study demonstrate that the SF/CS and SF/CS-HA hybrid patches may be promising biomaterials for regenerating infarcted cardiac tissues. PMID:19410289

Yang, Ming-Chia; Wang, Shoei-Shen; Chou, Nai-Kuan; Chi, Nai-Hsin; Huang, Yi-You; Chang, Yu-Lin; Shieh, Ming-Jium; Chung, Tze-Wen

2009-08-01

337

Study of the effects of different sterilization methods on the properties of dense and porous silk fibroin membranes;Estudo dos efeitos de diferentes metodos de esterilizacao nas propriedades de membranas densas de fibroina de seda  

Energy Technology Data Exchange (ETDEWEB)

Silk fibroin has been widely explored for many biomedical applications, due to its biocompatibility and biodegradability. Sterilization is a fundamental step in biomaterials processing, and it must not alter in a negative way the functionality of medical devices. The aim of this study was to analyze the influence of different sterilization methods in the physical and chemical characteristics of dense silk fibroin membranes. Dense fibroin membranes were sterilized by ultraviolet radiation, 70% ethanol, autoclave, ethylene oxide and gamma radiation, and were analyzed by SEM, FTIR-ATR and XRD. The results for sterilization indicated that the methods didn't cause degradation of the membranes, but the methods that used organic solvent, or increase of humidity and/or temperature (70% ethanol, autoclave and ethylene oxide) altered the molecular conformation of fibroin, increasing the proportion of beta-sheet structure, what indicates an increase of crystallinity. This effect may be positive when a slower degradation of the membranes is desired, depending on the application as a bio material. (author)

Weska, Raquel F.; Moraes, Mariana A. de; Beppu, Marisa M., E-mail: raquelweska@terra.com.b [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Quimica

2009-07-01

338

Designing silk fibroin-based matrices with ionic liquids for tissue engineering strategies using human adipose stem cells  

OpenAIRE

Silk (SF) is an attractive biomaterial to be used in tissue engineering applications because of its excellent mechanical properties and biocompatibility [1, 2]. In this work, the cellular response of silk hydrogels produced through dissolution of this protein in ionic liquids (ILs) was investigated. For that, degummed fibers obtained from the cocoons of mulberry silkworm (Bombyx mori) were dissolved in an IL and the solution was gelified in ethanol, followed by IL removal from gels using soxh...

Silva, S. S.; Popa, Elena G.; Gomes, Manuela E.; Oliveira, M. B.; Mano, J. F.; Reis, R. L.

2012-01-01

339

Effect of Processing on Silk-Based Biomaterials: Reproducibility and Biocompatibility  

OpenAIRE

Silk fibroin has been successfully used as a biomaterial for tissue regeneration. In order to prepare silk fibroin biomaterials for human implantation a series of processing steps are required to purify the protein. Degumming to remove inflammatory sericin is a crucial step related to biocompatibility and variability in the material. Detailed characterization of silk fibroin degumming is reported. The degumming conditions significantly affected cell viability on the silk fibroin material and ...

Wray, Lindsay S.; Hu, Xiao; Gallego, Jabier; Georgakoudi, Irene; Omenetto, Fiorenzo G.; Schmidt, Daniel; Kaplan, David L.

2011-01-01

340

Response of human mesenchymal stem cells to intrafibrillar nanohydroxyapatite content and extrafibrillar nanohydroxyapatite in biomimetic chitosan/silk fibroin/nanohydroxyapatite nanofibrous membrane scaffolds  

Directory of Open Access Journals (Sweden)

Full Text Available Guo-Jyun Lai,1,* KT Shalumon,1,* Jyh-Ping Chen1,2 1Department of Chemical and Materials Engineering, 2Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan, Republic of China *These authors contributed equally to this work Abstract: Incorporation of nanohydroxyapatite (nHAP within a chitosan (CS/silk fibroin (SF nanofibrous membrane scaffold (NMS may provide a favorable microenvironment that more closely mimics the natural bone tissue physiology and facilitates enhanced osteogensis of the implanted cell population. In this study, we prepared pristine CS/SF NMS, composite CS/SF/nHAP NMS containing intrafibrillar nHAP by in situ blending of 10% or 30% nHAP before the electrospinning step, and composite CS/SF/nHAP NMS containing extrafibrillar nHAP by depositing 30% nHAP through alternative soaking surface mineralization. We investigated the effect of the incorporation of HAP nanoparticles on the physicochemical properties of pristine and composite NMS. We confirmed the presence of ~30 nm nHAP in the composite nanofibrous membranes by thermogravimetry analysis (TGA, X-ray diffraction (XRD, and scanning electron microscopy (SEM, either embedded in or exposed on the nanofiber. Nonetheless, the alternative soaking surface mineralization method drastically influenced the mechanical properties of the NMS with 88% and 94% drop in Young’s modulus and ultimate maximum stress. Using in vitro cell culture experiments, we investigated the effects of nHAP content and location on proliferation and osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs. The proliferation of hMSCs showed no significant difference among pristine and composite NMS. However, the extent of osteogenic differentiation of hMSCs was found to be positively correlated with the content of nHAP in the NMS, while its location within the nanofiber played a less significant role. In vivo experiments were carried out with hMSCs seeded in CS/SF/30%nHAP NMS prepared by in situ blending and subcutaneous implantation in nude mice. Micro-computed tomography images as well as histological and immunohistochemical analysis of the retrieved hMSCs/NMS construct 1 and 2 months postimplantation indicated that NMS had the potential for bone regeneration and can be suggested as a promising scaffold for bone tissue engineering. Keywords: chitosan, silk fibroin, hydroxyapatite, electrospinning, nanofibers, human bone marrow stem cells, bone tissue engineering

Lai GJ

2015-01-01

341

Amperometric biosensor based on tyrosinase immobilized onto multiwalled carbon nanotubes-cobalt phthalocyanine-silk fibroin film and its application to determine bisphenol A  

Energy Technology Data Exchange (ETDEWEB)

An amperometric bisphenol A (BPA) biosensor was fabricated by immobilizing tyrosinase on multiwalled carbon nanotubes (MWNTs)-cobalt phthalocyanine (CoPc)-silk fibroin (SF) composite modified glassy carbon electrode (GCE). In MWNTs-CoPc-SF composite film, SF provided a biocompatible microenvironment for the tyrosinase to retain its bioactivity, MWNTs possessed excellent inherent conductivity to enhance the electron transfer rate and CoPc showed good electrocatalytic activity to electrooxidation of BPA. The cyclic voltammogram of BPA at this biosensor exhibited a well defined anodic peak at 0.625 V. Compared with bare GCE, the oxidation signal of BPA significantly increased; therefore, this oxidation signal was used to determine BPA. The effect factors were optimized and the electrochemical parameters were calculated. The possible oxidation mechanism was also discussed. Under optimum conditions, the oxidation current was proportional to BPA concentration in the range from 5.0 x 10{sup -8} to 3.0 x 10{sup -6} M with correlation coefficient of 0.9979 and detection limit of 3.0 x 10{sup -8} M (S/N = 3). The proposed method was successfully applied to determine BPA in plastic products and the recovery was in the range from 95.36% to 104.39%.

Yin Huanshun [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); College of Resources and Environment, Shandong Agricultural University, Taian 271018, Shandong (China); Zhou Yunlei; Xu Jing [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Ai Shiyun, E-mail: ashy@sdau.edu.cn [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Cui Lin [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Zhu Lusheng, E-mail: lushzhu@sdau.edu.cn [College of Resources and Environment, Shandong Agricultural University, Taian 271018, Shandong (China)

2010-02-05

342

Quantitative analyses of the effect of silk fibroin/nano-hydroxyapatite composites on osteogenic differentiation of MG-63 human osteosarcoma cells.  

Science.gov (United States)

Silk fibroin (SF)/nano-hydroxyapatite (n-HA) composites are potential biomaterials for bone defect repair. Up to now, the biological evaluation studies of SF/n-HA composites have primarily concentrated on their biocompatibility at cell level such as cell viability and proliferation and tissue level such as material absorption and new bone formation. In this work, SF/n-HA composites were fabricated using a simplified coprecipitation methods and were deposited onto Ti alloy substrates. Then the cell adhesion ability of SF/n-HA composites was observed by SEM and cell proliferation ability of SF/n-HA composites was determined by MTT assay. The ALP activity, BGP contents, and Col I contents of MG-63 human osteosarcoma cells on SF/n-HA composites were quantitatively analyzed. HA nanocrystals were used as controls. These experiments showed that SF/n-HA composites had better cell adhesion and osteogenic differentiation abilities than n-HA materials. This work provides quantitative data to analyze the effect of SF/n-HA composites on cell osteogenic differentiation. PMID:25454062

Lin, Linxue; Hao, Runsong; Xiong, Wei; Zhong, Jian

2014-11-01

343

Preferential expansion of umbilical cord blood-derived CD34-positive cells on human leukemia inhibitory factor transgenic feeder cells cultured on regenerated silk fibroin film.  

Science.gov (United States)

In vitro expansion of transplantable hematopoietic stem cells (HSCs) is a very promising approach for different clinical applications. We have recently developed a new culture system that facilitates in vitro expansion of transplantable cord blood HSCs. In our study, we constructed a recombinant adenovirus Ad-GFP/human leukemia inhibitory factor (hLIF) expressing hLIF. The hLIF gene was delivered into human embryo lung fibroblast cell line WI-38 via infection with Ad-GFP/hLIF. Then, the transgenic cells were cultured on regenerated silk fibroin (SF) films as feeder layer cells for expansion of cord blood CD34(+) cells. Our results showed that the hLIF transgenic WI-38 cells cultured on SF could express hematopoiesis-related cytokines at higher levels compared with control groups. The hLIF-expressing feeder layer cells cultured on SF in combination with cytokines more efficiently expanded CD34(+) cells and CD34(+) CD38(-) cells. The percentages of adhesion molecules on the expanded CD34(+) cells in transgenic feeder layer cells cultured on SF were higher than those of control groups. Interestingly, the migration rate assessed by transwell assay was also significantly higher than those of control groups, which suggests that transgenic feeder layer cells cultured on SF has powerful ability to maintain the homing capacity of expanded CD34(+) cells. PMID:23559317

Yu, Xin; Miao, Jingcheng; Xia, Wei; Gu, Zong-jiang

2013-08-01

344

Chitosan/silk fibroin-based, Schwann cell-derived extracellular matrix-modified scaffolds for bridging rat sciatic nerve gaps.  

Science.gov (United States)

Extracellular matrix (ECM) plays a prominent role in establishing and maintaining an ideal microenvironment for tissue regeneration, and ECM scaffolds are used as a feasible alternative to cellular and molecular therapy in the fields of tissue engineering. Because of their advantages over tissue-derived ECM scaffolds, cultured cell-derived ECM scaffolds are beginning to attract attention, but they have been scarcely studied for peripheral nerve repair. Here we aimed to develop a tissue engineered nerve scaffold by reconstituting nerve cell-derived ECM with natural biomaterials. A protocol was adopted to prepare and characterize the cultured Schwann cell (SC)-derived ECM. A chitosan conduit and silk fibroin (SF) fibers were prepared, cultured with SCs for ECM deposition, and subjected to decellularization, followed by assembly into a chitosan/SF-based, SC-derived ECM-modified scaffold, which was used to bridge a 10 mm rat sciatic nerve gap. The results from morphological analysis as well as electrophysiological examination indicated that regenerative outcomes achieved by our developed scaffold were similar to those by an acellular nerve graft (namely a nerve tissue-derived ECM scaffold), but superior to those by a plain chitosan/SF scaffold. Moreover, blood and histopathological parameters confirmed the safety of scaffold modification by SC-derived ECM. Therefore, a hybrid scaffold based on joint use of acellular and classical biomaterials represents a promising approach to nerve tissue engineering. PMID:24360577

Gu, Yun; Zhu, Jianbin; Xue, Chengbin; Li, Zhenmeiyu; Ding, Fei; Yang, Yumin; Gu, Xiaosong

2014-02-01

345

Amperometric biosensor based on tyrosinase immobilized onto multiwalled carbon nanotubes-cobalt phthalocyanine-silk fibroin film and its application to determine bisphenol A.  

Science.gov (United States)

An amperometric bisphenol A (BPA) biosensor was fabricated by immobilizing tyrosinase on multiwalled carbon nanotubes (MWNTs)-cobalt phthalocyanine (CoPc)-silk fibroin (SF) composite modified glassy carbon electrode (GCE). In MWNTs-CoPc-SF composite film, SF provided a biocompatible microenvironment for the tyrosinase to retain its bioactivity, MWNTs possessed excellent inherent conductivity to enhance the electron transfer rate and CoPc showed good electrocatalytic activity to electrooxidation of BPA. The cyclic voltammogram of BPA at this biosensor exhibited a well defined anodic peak at 0.625 V. Compared with bare GCE, the oxidation signal of BPA significantly increased; therefore, this oxidation signal was used to determine BPA. The effect factors were optimized and the electrochemical parameters were calculated. The possible oxidation mechanism was also discussed. Under optimum conditions, the oxidation current was proportional to BPA concentration in the range from 5.0 x 10(-8) to 3.0 x 10(-6) M with correlation coefficient of 0.9979 and detection limit of 3.0 x 10(-8) M (S/N=3). The proposed method was successfully applied to determine BPA in plastic products and the recovery was in the range from 95.36% to 104.39%. PMID:20103117

Yin, Huanshun; Zhou, Yunlei; Xu, Jing; Ai, Shiyun; Cui, Lin; Zhu, Lusheng

2010-02-01

346

Amperometric biosensor based on tyrosinase immobilized onto multiwalled carbon nanotubes-cobalt phthalocyanine-silk fibroin film and its application to determine bisphenol A  

International Nuclear Information System (INIS)

An amperometric bisphenol A (BPA) biosensor was fabricated by immobilizing tyrosinase on multiwalled carbon nanotubes (MWNTs)-cobalt phthalocyanine (CoPc)-silk fibroin (SF) composite modified glassy carbon electrode (GCE). In MWNTs-CoPc-SF composite film, SF provided a biocompatible microenvironment for the tyrosinase to retain its bioactivity, MWNTs possessed excellent inherent conductivity to enhance the electron transfer rate and CoPc showed good electrocatalytic activity to electrooxidation of BPA. The cyclic voltammogram of BPA at this biosensor exhibited a well defined anodic peak at 0.625 V. Compared with bare GCE, the oxidation signal of BPA significantly increased; therefore, this oxidation signal was used to determine BPA. The effect factors were optimized and the electrochemical parameters were calculated. The possible oxidation mechanism was also discussed. Under optimum conditions, the oxidation current was proportional to BPA concentration in the range from 5.0 x 10-8 to 3.0 x 10-6 M with correlation coefficient of 0.9979 and detection limit of 3.0 x 10-8 M (S/N = 3). The proposed method was successfully applied to determine BPA in plastic products and the recovery was in the range from 95.36% to 104.39%.

347

Change in silk protein by radiation  

Energy Technology Data Exchange (ETDEWEB)

Silk fibroin fiber irradiated with an accelerated electron beam in the dose range of 250 - 1,000 kGy was pulverized by using a ball mill. As irradiation dose increased, the conversion efficiency from fiber to powder increased, which reached 94% at 1,000 kGy. Silk fibroin powder obtained by this method dissolved 57% into water of ambient temperature. It is a very interesting phenomenon that silk fibroin obtains solubility without chemical treatment. In order to study mechanism of solubilization of silk fibroin powder, amino acid component of soluble part of silk powder was performed. The more irradiation dose up, the more recovery fraction of glycine or alanine decreased, which is, however, reached the minimum about 50%. To consider this result with crystal structure of silk fibroin, it is suggested that irradiation on silk fibroin fiber selectively degrades glycine and alanine in amorphous region, which makes it possible to pulverize and to dissolve for silk fibroin powder. Molecular weight of soluble part was also measured, but it had no serious concern with irradiation dose. Particle size distribution of silk fibroin powder was measured in order to study reduction of irradiation dose needed for pulverization. This measurement exhibited the possibility that lengthening of pulverization time reduces of irradiation dose. In addition, structure of particle was inferred from result of this measurement. (author)

Ishida, Kazushige; Kamiishi, Youichi [Textile Research Institute of Gunma, Kiryu, Gunma (Japan); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2002-03-01

348

Biomaterials Derived from Silk-Tropoelastin Protein Systems  

OpenAIRE

A structural protein blend system based on silkworm silk fibroin and recombinant human tropoelastin is described. Silk fibroin, a semicrystalline fibrous protein with beta-sheet crystals provides mechanical strength and controllable biodegradation, while tropoelastin, a noncrystallizable elastic protein provides elasticity. Differential scanning calorimetry (DSC) and temperature modulated DSC (TMDSC) indicated that silk becomes miscible with tropoelastin at different blend ratios, without mac...

Hu, Xiao; Wang, Xiuli; Rnjak, Jelena; Weiss, Anthony S.; Kaplan, David L.

2010-01-01

349

Ingrowth of Human Mesenchymal Stem Cells into Porous Silk Particle Reinforced Silk Composite Scaffolds: An In Vitro Study  

OpenAIRE

Silk fibroin protein is biodegradable and biocompatible, exhibiting excellent mechanical properties for various biomedical applications. However, porous 3D silk fibroin scaffolds, or silk sponges, usually fall short in matching the initial mechanical requirements for bone tissue engineering. In the present study, silk sponge matrices were reinforced with silk microparticles to generate protein-protein composite scaffolds with desirable mechanical properties for in vitro osteogenic tissue form...

Rockwood, Danielle N.; Gil, Eun Seok; Park, Sang-hyug; Kluge, Jonathan A.; Grayson, Warren; Bhumiratana, Sarindr; Rajkhowa, Rangam; Wang, Xungai; Kim, Sung Jun; Vunjak-novakovic, Gordana; Kaplan, David L.

2010-01-01

350

Influence of the Mechanical Environment on the Engineering of Mineralised Tissues Using Human Dental Pulp Stem Cells and Silk Fibroin Scaffolds  

Science.gov (United States)

Teeth constitute a promising source of stem cells that can be used for tissue engineering and regenerative medicine purposes. Bone loss in the craniofacial complex due to pathological conditions and severe injuries could be treated with new materials combined with human dental pulp stem cells (hDPSCs) that have the same embryonic origin as craniofacial bones. Optimising combinations of scaffolds, cells, growth factors and culture conditions still remains a great challenge. In the present study, we evaluate the mineralisation potential of hDPSCs seeded on porous silk fibroin scaffolds in a mechanically dynamic environment provided by spinner flask bioreactors. Cell-seeded scaffolds were cultured in either standard or osteogenic media in both static and dynamic conditions for 47 days. Histological analysis and micro-computed tomography of the samples showed low levels of mineralisation when samples were cultured in static conditions (0.16±0.1 BV/TV%), while their culture in a dynamic environment with osteogenic medium and weekly µCT scans (4.9±1.6 BV/TV%) significantly increased the formation of homogeneously mineralised structures, which was also confirmed by the elevated calcium levels (4.5±1.0 vs. 8.8±1.7 mg/mL). Molecular analysis of the samples showed that the expression of tooth correlated genes such as Dentin Sialophosphoprotein and Nestin were downregulated by a factor of 6.7 and 7.4, respectively, in hDPSCs when cultured in presence of osteogenic medium. This finding indicates that hDPSCs are able to adopt a non-dental identity by changing the culture conditions only. Also an increased expression of Osteocalcin (1.4x) and Collagen type I (1.7x) was found after culture under mechanically dynamic conditions in control medium. In conclusion, the combination of hDPSCs and silk scaffolds cultured under mechanical loading in spinner flask bioreactors could offer a novel and promising approach for bone tissue engineering where appropriate and rapid bone regeneration in mechanically loaded tissues is required. PMID:25354351

Woloszyk, Anna; Holsten Dircksen, Sabrina; Bostanci, Nagihan; Müller, Ralph; Hofmann, Sandra; Mitsiadis, Thimios A.

2014-01-01

351

Antheraea pernyi Silk Fibroin-Coated PEI/DNA Complexes for Targeted Gene Delivery in HEK 293 and HCT 116 Cells  

Directory of Open Access Journals (Sweden)

Full Text Available Polyethylenimine (PEI has attracted much attention as a DNA condenser, but its toxicity and non-specific targeting limit its potential. To overcome these limitations, Antheraea pernyi silk fibroin (ASF, a natural protein rich in arginyl-glycyl-aspartic acid (RGD peptides that contains negative surface charges in a neutral aqueous solution, was used to coat PEI/DNA complexes to form ASF/PEI/DNA ternary complexes. Coating these complexes with ASF caused fewer surface charges and greater size compared with the PEI/DNA complexes alone. In vitro transfection studies revealed that incorporation of ASF led to greater transfection efficiencies in both HEK (human embryonic kidney 293 and HCT (human colorectal carcinoma 116 cells, albeit with less electrostatic binding affinity for the cells. Moreover, the transfection efficiency in the HCT 116 cells was higher than that in the HEK 293 cells under the same conditions, which may be due to the target bonding affinity of the RGD peptides in ASF for integrins on the HCT 116 cell surface. This result indicated that the RGD binding affinity in ASF for integrins can enhance the specific targeting affinity to compensate for the reduction in electrostatic binding between ASF-coated PEI carriers and cells. Cell viability measurements showed higher cell viability after transfection of ASF/PEI/DNA ternary complexes than after transfection of PEI/DNA binary complexes alone. Lactate dehydrogenase (LDH release studies further confirmed the improvement in the targeting effect of ASF/PEI/DNA ternary complexes to cells. These results suggest that ASF-coated PEI is a preferred transfection reagent and useful for improving both the transfection efficiency and cell viability of PEI-based nonviral vectors.

Yu Liu

2014-04-01

352

Three-layered scaffolds for artificial esophagus using poly(?-caprolactone) nanofibers and silk fibroin: An experimental study in a rat model.  

Science.gov (United States)

The purpose of this study was to determine the feasibility of an artificial esophagus using a three-layered poly(?-caprolactone) (PCL)-silk fibroin (SF) scaffold in a rat model. The artificial esophagus was a three-layered, hybrid-type prosthesis composed of an outer and inner layer of PCL with a middle layer of SF. After depositing the inner layer of the PCL scaffold by electrospinning, the lyophilized middle SF layer was created. The outer layer of PCL was produced following the same procedure used to make the inner PCL layer. Eleven rats were anesthetized using inhaled anesthesia. Circumferential defects of the cervical esophagus (n?=?11) were created and reconstructed. Groups of rats were sacrificed after the 1st and 2nd weeks. Three rats died of an esophageal fistula and wound infection. No gross evidence of a fistula, perforation, abscess formation, seroma accumulation, or surrounding soft-tissue necrosis was observed in the other rats sacrificed after the 1st and 2nd weeks. The artificial esophagus constructs produced complete healing of the circumferential defects by the 2nd week. The composition of the three-layered artificial esophagus was confirmed histologically to have an outer and inner layer of PCL and a middle layer of SF. The fusion of the PCL-SF scaffold and the regenerative tissue remained intact. Our study proposes a more practical experimental model for studying a three-layered PCL-SF scaffold in the esophagus. However, further studies on circumferential defect reconstruction in a rat model are still required. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2014. PMID:25294581

Chung, Eun-Jae; Ju, Hyung Woo; Park, Hyun Jung; Park, Chan Hum

2014-10-01

353

Transplantation of human placenta-derived mesenchymal stem cells in a silk fibroin/hydroxyapatite scaffold improves bone repair in rabbits.  

Science.gov (United States)

The main requirements for successful tissue engineering of the bone are non-immunogenic cells with osteogenic potential and a porous biodegradable scaffold. The purpose of this study is to evaluate the potential of a silk fibroin/hydroxyapatite (SF/HA) porous material as a delivery vehicle for human placenta-derived mesenchymal stem cells (PMSCs) in a rabbit radius defect model. In this study, we randomly assigned 16 healthy adult New Zealand rabbits into two groups, subjected to transplantation with either SF/HA and PMSCs (experimental group) or SF/HA alone (control group). To evaluate fracture healing, we assessed the extent of graft absorption, the quantity of newly formed bone, and re-canalization of the cavitas medullaris using radiographic and histological tools. We performed flow cytometric analysis to characterize PMSCs, and found that while they express CD90, CD105 and CD73, they stain negative for HLA-DR and the hematopoietic cell surface markers CD34 and CD45. When PMSCs were exposed to osteogenic induction medium, they secreted calcium crystals that were identified by von Kossa staining. Furthermore, when seeded on the surface of SF/HA scaffold, they actively secreted extracellular matrix components. Here, we show, through radiographic and histological analyses, that fracture healing in the experimental group is significantly improved over the control group. This strongly suggests that transplantation of human PMSCs grown in an SF/HA scaffold into injured radius segmental bone in rabbits, can markedly enhance tissue repair. Our finding provides evidence supporting the utility of human placenta as a potential source of stem cells for bone tissue engineering. PMID:24894683

Jin, Jun; Wang, Jun; Huang, Jian; Huang, Fang; Fu, Jianhong; Yang, Xinjing; Miao, Zongning

2014-11-01

354

Evaluating degradation of silk's fibroin by attenuated total reflectance infrared spectroscopy: Case study of ancient banners from Polish collections  

Science.gov (United States)

In this study a part of research where artificially aged model samples were used as a guideline to the mechanism of degradation is presented. In previous work Bombyx Mori silk samples were exposed to various environments such as different oxygen, water vapour and volatile organic products content, all at the temperature of 150 °C [11]. Based on those results gathered with by Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy (ATR-FTIR) the degradation estimators were proposed and classified as follows:plane bending and Csbnd N stretching vibrations A1620/A1514. ECOOH - band 1318 cm-1 integral to band integral of CH3 bending vibration band located at 1442 cm-1P1318/P1442.silk samples from 8 museum objects: 3 from 19th, 2 from 18th, 1 from 17th and 2 from 16th century including 3 banners from the storage resources of the Wawel Royal Castle in Cracow, Poland.

Koperska, M. A.; ?ojewski, T.; ?ojewska, J.

2015-01-01

355

Evaluating degradation of silk's fibroin by attenuated total reflectance infrared spectroscopy: case study of ancient banners from Polish collections.  

Science.gov (United States)

In this study a part of research where artificially aged model samples were used as a guideline to the mechanism of degradation is presented. In previous work Bombyx Mori silk samples were exposed to various environments such as different oxygen, water vapour and volatile organic products content, all at the temperature of 150 °C [11]. Based on those results gathered with by Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy (ATR-FTIR) the degradation estimators were proposed and classified as follows: (1) Primary functional groups estimators EAmideI/II - intensity ratios of Amide I C=O stretching vibration to Amide II N-H in-plane bending and C-N stretching vibrations A1620/A1514. ECOOH - band 1318 cm(-1) integral to band integral of CH3 bending vibration band located at 1442 cm(-1)P1318/P1442. (2) Secondary conformational estimators EcC=O2 - intensity ratios within Amide I C=O stretching vibration of parallel ?-sheet to antiparallel ?-sheet A1620/A1699. In this work estimators were verified against estimators calculated from spectra of silk samples from 8 museum objects: 3 from 19th, 2 from 18th, 1 from 17th and 2 from 16th century including 3 banners from the storage resources of the Wawel Royal Castle in Cracow, Poland. PMID:25124844

Koperska, M A; ?ojewski, T; ?ojewska, J

2015-01-25

356

Histochemical and ultrastructural evidence of lipid secretion by the silk gland of the sugarcane borer Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) / Evidências histoquímicas e ultra-estruturais de secreção sipídica pela glândula da seda da broca da cana-de-açúcar, Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A glândula da seda de larvas de Lepidoptera é responsável pela produção da seda usada na construção do casulo ou do abrigo. A secreção de fibroína e sericina pelas diferentes regiões da glândula da seda está bem estabelecida. Existem poucos trabalhos tentando identificar componentes lipídicos na sec [...] reção de seda de insetos, embora a presença desse componente contribua para a resistência da seda a ambiente úmidos. Este estudo teve como objetivo identificar a presença de componente lipídico na secreção da glândula da seda de larvas de Diatraea saccharalis (Fabricius), bem como caracterizar a região glandular responsável pela secreção. A glândula da seda foi submetida a procedimentos histoquímicos para detecção de lipídeos e convencionalmente preparada para análise ultra-estrutural. Gotas lipídicas foram histoquimicamente detectadas no citoplasma apical de células da região anterior e no lúmen, entre os microvilos. A análise ultra-estrutural da região anterior mostrou material lipídico, visualizado como figuras do tipo mielina dentro do complexo de Golgi vesicular e nos glóbulos secretores apicais, misturados com sericina; material semelhante foi observado dentro do lúmen, adjacente aos microvilos. Nenhum componente secretor lipídico foi detectado nas células ou no lúmen da região posterior. Os resultados sugerem que a seda produzida pela D. saccharalis tem, pelo menos, um discreto componente lipídico, que é secretado pela região anterior, junto com a sericina. Abstract in english The silk gland in Lepidoptera larvae is responsible for the silk production used for shelter or cocoon construction. The secretion of fibroin and sericin by the different silk gland regions are well established. There are few attempts to detect lipid components in the insect silk secretion, although [...] the presence of such element may contribute to the resistance of the shelter to wet environment. This study characterizes the glandular region and detects the presence of lipid components in the secretion of the silk gland of Diatraea saccharalis(Fabricius). The silk gland was submitted to histochemical procedure for lipid detection or conventionally prepared for ultrastructural analyses. Lipid droplets were histochemically detected in both the apical cytoplasm of cell of the anterior region and in the lumen among the microvilli. Ultrastructural analyses of the anterior region showed lipid material, visualized as myelin-like structures within the vesicular Golgi complex and in the apical secretory globules, mixed up with the sericin; similar material was observed into the lumen, adjacent to the microvilli. Lipids were not detected in the cells neither in the lumen of the posterior region. Our results suggest that the silk produced by D. saccharalis has a minor lipid content that is secreted by the anterior region together with the sericin.

Eliane, Victoriano; Daniela O., Pinheiro; Elisa A., Gregório.

2007-10-01

357

An Australian webspinner species makes the finest known insect silk fibers  

Energy Technology Data Exchange (ETDEWEB)

Aposthonia gurneyi, an Australian webspinner species, is a primitive insect that constructs and lives in a silken tunnel which screens it from the attentions of predators. The insect spins silk threads from many tiny spines on its forelegs to weave a filmy sheet. We found that the webspinner silk fibers have a mean diameter of only 65 nm, an order of magnitude smaller than any previously reported insect silk. The purpose of such fine silk may be to reduce the metabolic cost of building the extensive tunnels. At the molecular level, the A. gurneyi silk has a predominantly beta-sheet protein structure. The most abundant clone in a cDNA library produced from the webspinner silk glands encoded a protein with extensive glycine-serine repeat regions. The GSGSGS repeat motif of the A. gurneyi silk protein is similar to the well-known GAGAGS repeat motif found in the heavy fibroin of silkworm silk, which also has beta-sheet structure. As the webspinner silk gene is unrelated to the silk gene of the phylogenetically distant silkworm, this is a striking example of convergent evolution.

Okada, Shoko; Weisman, Sarah; Trueman, Holly E.; Mudie, Stephen T.; Haritos, Victoria S.; Sutherland, Tara D. (CSIRO/MSE); (CSIRO)

2009-01-15

358

Effect of Silk Protein Processing on Drug Delivery from Silk Films  

OpenAIRE

Sericin removal from the core fibroin protein of silkworm silk is a critical first step in the use of silk for biomaterial-related applications, but degumming can affect silk biomaterial properties, including molecular weight, viscosity, diffusivity and degradation behavior. Increasing the degumming time (10, 30, 60 and 90 min) decreases the average molecular weight of silk protein in solution, silk solution viscosity, and silk film glass transition temperature, and increases the rate of degr...

Pritchard, Eleanor M.; Hu, Xiao; Finley, Violet; Kuo, Catherine K.; Kaplan, David L.

2013-01-01

359

Production of an active feline interferon in the cocoon of transgenic silkworms using the fibroin H-chain expression system  

International Nuclear Information System (INIS)

We constructed the fibroin H-chain expression system to produce recombinant proteins in the cocoon of transgenic silkworms. Feline interferon (FeIFN) was used for production and to assess the quality of the product. Two types of FeIFN fusion protein, each with N- and C-terminal sequences of the fibroin H-chain, were designed to be secreted into the lumen of the posterior silk glands. The expression of the FeIFN/H-chain fusion gene was regulated by the fibroin H-chain promoter domain. The transgenic silkworms introduced these constructs with the piggyBac transposon-derived vector, which produced the normal sized cocoons containing each FeIFN/H-chain fusion protein. Although the native-protein produced by transgenic silkworms have almost no antiviral activity, the proteins after the treatment with PreScission protease to eliminate fibroin H-chain derived N- and C-terminal sequences from the products, had very high antiviral activity. This H-chain expression system, using transgenic silkworms, could be an alternative method to produce an active recombinant protein and silk-based biomaterials

360

Response of human mesenchymal stem cells to intrafibrillar nanohydroxyapatite content and extrafibrillar nanohydroxyapatite in biomimetic chitosan/silk fibroin/nanohydroxyapatite nanofibrous membrane scaffolds  

Science.gov (United States)

Incorporation of nanohydroxyapatite (nHAP) within a chitosan (CS)/silk fibroin (SF) nanofibrous membrane scaffold (NMS) may provide a favorable microenvironment that more closely mimics the natural bone tissue physiology and facilitates enhanced osteogensis of the implanted cell population. In this study, we prepared pristine CS/SF NMS, composite CS/SF/nHAP NMS containing intrafibrillar nHAP by in situ blending of 10% or 30% nHAP before the electrospinning step, and composite CS/SF/nHAP NMS containing extrafibrillar nHAP by depositing 30% nHAP through alternative soaking surface mineralization. We investigated the effect of the incorporation of HAP nanoparticles on the physicochemical properties of pristine and composite NMS. We confirmed the presence of ~30 nm nHAP in the composite nanofibrous membranes by thermogravimetry analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM), either embedded in or exposed on the nanofiber. Nonetheless, the alternative soaking surface mineralization method drastically influenced the mechanical properties of the NMS with 88% and 94% drop in Young’s modulus and ultimate maximum stress. Using in vitro cell culture experiments, we investigated the effects of nHAP content and location on proliferation and osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs). The proliferation of hMSCs showed no significant difference among pristine and composite NMS. However, the extent of osteogenic differentiation of hMSCs was found to be positively correlated with the content of nHAP in the NMS, while its location within the nanofiber played a less significant role. In vivo experiments were carried out with hMSCs seeded in CS/SF/30%nHAP NMS prepared by in situ blending and subcutaneous implantation in nude mice. Micro-computed tomography images as well as histological and immunohistochemical analysis of the retrieved hMSCs/NMS construct 1 and 2 months postimplantation indicated that NMS had the potential for bone regeneration and can be suggested as a promising scaffold for bone tissue engineering.

Lai, Guo-Jyun; Shalumon, KT; Chen, Jyh-Ping

2015-01-01

361

Response of human mesenchymal stem cells to intrafibrillar nanohydroxyapatite content and extrafibrillar nanohydroxyapatite in biomimetic chitosan/silk fibroin/nanohydroxyapatite nanofibrous membrane scaffolds.  

Science.gov (United States)

Incorporation of nanohydroxyapatite (nHAP) within a chitosan (CS)/silk fibroin (SF) nanofibrous membrane scaffold (NMS) may provide a favorable microenvironment that more closely mimics the natural bone tissue physiology and facilitates enhanced osteogensis of the implanted cell population. In this study, we prepared pristine CS/SF NMS, composite CS/SF/nHAP NMS containing intrafibrillar nHAP by in situ blending of 10% or 30% nHAP before the electrospinning step, and composite CS/SF/nHAP NMS containing extrafibrillar nHAP by depositing 30% nHAP through alternative soaking surface mineralization. We investigated the effect of the incorporation of HAP nanoparticles on the physicochemical properties of pristine and composite NMS. We confirmed the presence of ~30 nm nHAP in the composite nanofibrous membranes by thermogravimetry analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM), either embedded in or exposed on the nanofiber. Nonetheless, the alternative soaking surface mineralization method drastically influenced the mechanical properties of the NMS with 88% and 94% drop in Young's modulus and ultimate maximum stress. Using in vitro cell culture experiments, we investigated the effects of nHAP content and location on proliferation and osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs). The proliferation of hMSCs showed no significant difference among pristine and composite NMS. However, the extent of osteogenic differentiation of hMSCs was found to be positively correlated with the content of nHAP in the NMS, while its location within the nanofiber played a less significant role. In vivo experiments were carried out with hMSCs seeded in CS/SF/30%nHAP NMS prepared by in situ blending and subcutaneous implantation in nude mice. Micro-computed tomography images as well as histological and immunohistochemical analysis of the retrieved hMSCs/NMS construct 1 and 2 months postimplantation indicated that NMS had the potential for bone regeneration and can be suggested as a promising scaffold for bone tissue engineering. PMID:25609962

Lai, Guo-Jyun; Shalumon, Kt; Chen, Jyh-Ping

2015-01-01

362

Response of human mesenchymal stem cells to intrafibrillar nanohydroxyapatite content and extrafibrillar nanohydroxyapatite in biomimetic chitosan/silk fibroin/nanohydroxyapatite nanofibrous membrane scaffolds  

Science.gov (United States)

Incorporation of nanohydroxyapatite (nHAP) within a chitosan (CS)/silk fibroin (SF) nanofibrous membrane scaffold (NMS) may provide a favorable microenvironment that more closely mimics the natural bone tissue physiology and facilitates enhanced osteogensis of the implanted cell population. In this study, we prepared pristine CS/SF NMS, composite CS/SF/nHAP NMS containing intrafibrillar nHAP by in situ blending of 10% or 30% nHAP before the electrospinning step, and composite CS/SF/nHAP NMS containing extrafibrillar nHAP by depositing 30% nHAP through alternative soaking surface mineralization. We investigated the effect of the incorporation of HAP nanoparticles on the physicochemical properties of pristine and composite NMS. We confirmed the presence of ~30 nm nHAP in the composite nanofibrous membranes by thermogravimetry analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM), either embedded in or exposed on the nanofiber. Nonetheless, the alternative soaking surface mineralization method drastically influenced the mechanical properties of the NMS with 88% and 94% drop in Young’s modulus and ultimate maximum stress. Using in vitro cell culture experiments, we investigated the effects of nHAP content and location on proliferation and osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs). The proliferation of hMSCs showed no significant difference among pristine and composite NMS. However, the extent of osteogenic differentiation of hMSCs was found to be positively correlated with the content of nHAP in the NMS, while its location within the nanofiber played a less significant role. In vivo experiments were carried out with hMSCs seeded in CS/SF/30%nHAP NMS prepared by in situ blending and subcutaneous implantation in nude mice. Micro-computed tomography images as well as histological and immunohistochemical analysis of the retrieved hMSCs/NMS construct 1 and 2 months postimplantation indicated that NMS had the potential for bone regeneration and can be suggested as a promising scaffold for bone tissue engineering. PMID:25609962

Lai, Guo-Jyun; Shalumon, KT; Chen, Jyh-Ping

2015-01-01

363

Piriform Silk Production  

OpenAIRE

Spider silk produced by Nephila clavipes has been shown to have surprisingly marketable properties. The silk has been experimentally proven to have twice the extensibility of nylon and a higher toughness than Kevlar. One form of spider silk that has remained relatively unstudied is Piriform silk, which originates from a small gland near the spinneret of the spider. Piriform silk is used by Nephila Clavipes as an adhesive to bind other fibers to an array of surfaces during web construction. Tw...

Ballam, Jordan

2014-01-01

364

Development of a silk protein based wound dressing and its effect on wound healing in rats  

OpenAIRE

Silk has been used in textile production for centuries and in medicine, as sutures for decades. Sericin and fibroin are the two primary silk proteins. Silk has been shown to improve wound healing. Copper ions have also been documented to have healing properties. The novel silk protein based wound dressing donated by Southern Formulations (Pty) Ltd. for evaluation contains sericin, fibroin and copper ions. The aim of this study was to investigate the effect of silk proteins and copper ions com...

Olivier, Jeane

2012-01-01

365

Development of a silk protein based wound dressing and its effect on wound healing in rats  

OpenAIRE

Silk has been used in textile production for centuries and in medicine, as sutures for decades. Sericin and fibroin are the two primary silk proteins. Silk has been shown to improve wound healing. Copper ions have also been documented to have healing properties. The novel silk protein based wound dressing donated by Southern Formulations (Pty) Ltd. for evaluation contains sericin, fibroin and copper ions. The aim of this study was to investigate the effect of silk proteins and copper ions com...

Olivier, Jeane

2011-01-01

366

Ion Electrodiffusion Governs Silk Electrogelation  

OpenAIRE

Silk electrogelation involves the transition of an aqueous silk fibroin solution to a gel state (E-gel) in the presence of an electric current. The process is based on local pH changes as a result of water electrolysis – generating H+ and OH? ions at the (+) and (?) electrodes, respectively. Silk fibroin has a pI=4.2 and when local pH

Kojic, Nikola; Panzer, Matthew J.; Leisk, Gary G.; Raja, Waseem K.; Kojic, Milos; Kaplan, David L.

2012-01-01

367

Construction of transgenic silkworm spinning antibacterial silk with fluorescence.  

Science.gov (United States)

A targeting vector consisting of a fusion gene of the green fluorescent protein (GFP) gene gfp and the antimicrobial peptide cecropin gene cec flanked by pieces of the 5' and 3' sequences of the fibroin L chain gene fib-L of the silkworm (Bombyx mori) and a negative selection DsRed marker gene driven by the baculovirus immediate early gene 1 (i.e.-1) promoter, was used to target the silkworm genome in order to explore the possibility of improving the performance of silk. A transgenic silkworm with a green fluorescent cocoon was obtained and PCR analysis of its genome confirmed that the target genes had been integrated into the silkworm genome correctly. Furthermore, in the posterior silk glands of the G6 generation transformation silkworm, a band representing the fusion protein Fib-L-GFP-Cec with a molecular mass of 68.7 kDa was detected by western blotting with an antibody against GFP. An investigation of the number of bacteria attached to a cocoon showed the transgenic silkworm cocoon possessed antibacterial properties. These results suggested the performance of silk can be improved by modifying the fibroin gene. PMID:25223857

Li, Zhen; Jiang, Yue; Cao, Guangli; Li, Jingzhi; Xue, Renyu; Gong, Chengliang

2015-01-01

368

Ultrastructure of the excretory duct in the silk gland of the sugarcane borer Diatraea saccharalis (Lepidoptera: Pyralidae).  

Science.gov (United States)

The excretory duct in the silk gland of the sugarcane borer Diatraea saccharalis consists of two morphologically distinct regions, recognized by scanning and transmission electron microscopy. The thin posterior region, adjacent to the glandular region, presents a regular surface. Secretory vesicles containing either electron-dense or fibrillar cuticular-like materials are observed in their apical cytoplasm; the same cuticular materials were detected as extracellular deposits among the microvilli. The short anterior region, near the common duct, exhibits surface protrusions; there are no secretory vesicles in their apical cytoplasm. These results show that only the duct cells at the posterior region are involved in the secretion of the cuticular intima elements. Desmosome-like structures were visualized linking together adjacent microvillar membranes only in the cells of anterior duct region, with unknown function. The transition between the duct and the glandular region is abrupt; the cells of the glandular and posterior duct regions present large amounts of microtubules. Nerve fibers can be observed between the duct cells in their two regions, suggesting that control of silk secretion may occur in the excretory duct via neurotransmitter liberation. PMID:18088967

Victoriano, Eliane; Gregório, Elisa A

2002-09-01

369

Dragline silk: a fiber assembled with low-molecular-weight cysteine-rich proteins.  

Science.gov (United States)

Dragline silk has been proposed to contain two main protein constituents, MaSp1 and MaSp2. However, the mechanical properties of synthetic spider silks spun from recombinant MaSp1 and MaSp2 proteins have yet to approach natural fibers, implying the natural spinning dope is missing critical factors. Here we report the discovery of novel molecular constituents within the spinning dope that are extruded into dragline silk. Protein studies of the liquid spinning dope from the major ampullate gland, coupled with the analysis of dragline silk fibers using mass spectrometry, demonstrate the presence of a new family of low-molecular-weight cysteine-rich proteins (CRPs) that colocalize with the MA fibroins. Expression of the CRP family members is linked to dragline silk production, specifically MaSp1 and MaSp2 mRNA synthesis. Biochemical data support that CRP molecules are secreted into the spinning dope and assembled into macromolecular complexes via disulfide bond linkages. Sequence analysis supports that CRP molecules share similarities to members that belong to the cystine slipknot superfamily, suggesting that these factors may have evolved to increase fiber toughness by serving as molecular hubs that dissipate large amounts of energy under stress. Collectively, our findings provide molecular details about the components of dragline silk, providing new insight that will advance materials development of synthetic spider silk for industrial applications. PMID:25259849

Pham, Thanh; Chuang, Tyler; Lin, Albert; Joo, Hyun; Tsai, Jerry; Crawford, Taylor; Zhao, Liang; Williams, Caroline; Hsia, Yang; Vierra, Craig

2014-11-10

370

Fabrication and Biocompatibility of Electrospun Silk Biocomposites  

Directory of Open Access Journals (Sweden)

Full Text Available Silk fibroin has attracted great interest in tissue engineering because of its outstanding biocompatibility, biodegradability and minimal inflammatory reaction. In this study, two kinds of biocomposites based on regenerated silk fibroin are fabricated by electrospinning and post-treatment processes, respectively. Firstly, regenerated silk fibroin/tetramethoxysilane (TMOS hybrid nanofibers with high hydrophilicity are prepared, which is superior for fibroblast attachment. The electrospinning process causes adjacent fibers to ‘weld’ at contact points, which can be proved by scanning electron microscope (SEM. The water contact angle of silk/tetramethoxysilane (TMOS composites shows a sharper decrease than pure regenerated silk fibroin nanofiber, which has a great effect on the early stage of cell attachment behavior. Secondly, a novel tissue engineering scaffold material based on electrospun silk fibroin/nano-hydroxyapatite (nHA biocomposites is prepared by means of an effective calcium and phosphate (Ca–P alternate soaking method. nHA is successfully produced on regenerated silk fibroin nanofiber within several min without any pre-treatments. The osteoblastic activities of this novel nanofibrous biocomposites are also investigated by employing osteoblastic-like MC3T3-E1 cell line. The cell functionality such as alkaline phosphatase (ALP activity is ameliorated on mineralized silk nanofibers. All these results indicate that this silk/nHA biocomposite scaffold material may be a promising biomaterial for bone tissue engineering.

Ick-Soo Kim

2011-10-01

371

A novel marine silk.  

OpenAIRE

The discovery of a novel silk production system in a marine amphipod provides insights into the wider potential of natural silks. The tube-building corophioid amphipod Crassicorophium bonellii produces from its legs fibrous, adhesive underwater threads that combine barnacle cement biology with aspects of spider silk thread extrusion spinning. We characterised the filamentous silk as a mixture of mucopolysaccharides and protein deriving from glands representing two distinct types. The carbohyd...

Kronenberger, K.; Dicko, C.; Vollrath, F.

2012-01-01

372

Templating effect of silk fibers in the oriented deposition of aragonite.  

Science.gov (United States)

Controlled deposition of calcium carbonate crystals can be obtained on degummed Bombyx mori silk fibers through the use of a silk fibroin solution; aragonite crystallites are found on the surface of the fiber with consistent orientation along the longitudinal axis; the results indicate that the combination of the ordered surface structure on the silk fiber and the directing-effect of silk fibroin solution are the key factors in the orientative deposition process of the mineral. PMID:18997935

Cheng, Cheng; Yang, Yuhong; Chen, Xin; Shao, Zhengzhong

2008-11-21

373

Radiation degradation of silk protein  

International Nuclear Information System (INIS)

Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl2/C2H5OH/H2O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

374

Radiation degradation of silk protein  

Energy Technology Data Exchange (ETDEWEB)

Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated in the dose range up to 2500 kGy using an electron beam accelerator to apply the radiation degradation technique as a means to solubilize fibroin. The tensile strength of irradiated fibroin fiber decreased with increasing dose and the presence of oxygen in the irradiation atmosphere enhanced the degradation. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: calcium chloride solution (CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O = 1 : 2 : 8 in mole ratio), hydrochloric acid (0.5N) and distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water-soluble protein was extracted by distilled water. (author)

Wachiraporn Pewlong; Boonya Sudatis [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2000-09-01

375

Radiation degradation of silk protein  

Energy Technology Data Exchange (ETDEWEB)

Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

Pewlong, W.; Sudatis, B. [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2000-03-01

376

Selection of silk-binding peptides by phage display  

OpenAIRE

Peptides that bind to silkworm-derived silk fibroin fiber were selected from a phage-displayed random peptide library. The selected silk-binding peptides contained a consensus sequence QSWS which is important for silk-binding as confirmed by binding assays using phage and synthetic peptides. With further optimization, we anticipate that the silk-binding peptides will be useful for functionalization of silk for biomaterial applications.

Nomura, Yoko; Sharma, Vandana; Yamamura, Asami; Yokobayashi, Yohei

2011-01-01

377

Chitosan silk-based three-dimensional scaffolds containing gentamicin-encapsulated calcium alginate beads for drug administration and blood compatibility.  

Science.gov (United States)

In the present study gentamicin was encapsulated within calcium alginate beads and incorporated into porous chitosan, gelatin, double-hybrid silk fibroin, chitosan/gelatin and double-hybrid silk fibroin/chitosan scaffolds. Physiochemical, morphological and biological properties of fabricated amenable model systems were evaluated, revealing hemocompatible nature of double-hybrid silk fibroin/chitosan and double-hybrid silk fibroin scaffolds of hemolysis %porosity >85%. Fourier transform infrared results confirmed the blend formation and scanning electron microscope images showed good interconnectivity. Double-hybrid silk fibroin/chitosan-blended scaffold shows higher compressive strength and compressive modulus than other fabricated scaffolds. A comparative drug release profile of fabricated scaffolds revealed that double-hybrid silk fibroin/chitosan scaffold is a pertinent model system because of its prolonged drug release, optimal hemocompatability and high compressive modulus. PMID:25492055

Mehta, Abijeet Singh; Singh, Brijesh K; Singh, Nandita; Archana, D; Snigdha, Kirti; Harniman, Robert; Rahatekar, Sameer S; Tewari, Rp; Dutta, Pk

2014-12-01

378

In vivo analysis of fibroin heavy chain signal peptide of silkworm Bombyx mori using recombinant baculovirus as vector  

International Nuclear Information System (INIS)

In order to investigate the functional signal peptide of silkworm fibroin heavy chain (FibH) and the effect of N- and C-terminal parts of FibH on the secretion of FibH in vivo, N- and C-terminal segments of fibh gene were fused with enhanced green fluorescent protein (EGFP) gene. The fused gene was then introduced into silkworm larvae and expressed in silk gland using recombinant AcMNPV (Autographa californica multiple nuclear polyhedrosis virus) as vector. The fluorescence of EGFP was observed with fluorescence microscope. FibH-EGFP fusion proteins extracted from silk gland were analyzed by Western blot. Results showed that the two alpha helices within N-terminal 163 amino acid residues and the C-terminal 61 amino acid residues were not necessary for cleavage of signal peptide and secretion of the fusion protein into silk gland. Then the C-terminal 61 amino acid residues were substituted with a His-tag in the fusion protein to facilitate the purification. N-terminal sequencing of the purified protein showed that the signal cleavage site is between position 21 and 22 amino acid residues

379

Hierarchical biomineralization of calcium carbonate regulated by silk microspheres.  

Science.gov (United States)

As an analog of the main protein contained in nacre regenerated Bombyx mori silk fibroin has a significant influence on the morphology and polymorphic nature of CaCO3 in the biomineralization process. A number of studies have implied that the self-assembling aggregate structure of silk fibroin is a key factor in controlling CaCO3 aggregation. Further insight into this role is necessary with a particular need to prepare silk fibroin aggregates with homogeneous structures to serve as templates for the mineralization process. Here we have prepared homogeneous silk microspheres to serve as templates for CaCO3 mineralization in order to provide an experimental insight into silk-regulated crystallization processes. CaCO3 particles with different nano- and microstructures, and their polymorphs, were successfully formed by controlling the mineralization process. The key function of silk aggregation in controlling the morphology and polymorphic nature of CaCO3 particles was confirmed. A regulating effect of silk on the spatial features was also observed. A two-step process for silk fibroin-regulated biomineralization was found, with different levels of heterogeneous nucleation and aggregation. A full understanding of silk fibroin-regulated biomineralization mechanisms would help in understanding the function of organic polymers in natural biomineralization, and provide a way forward in the design and synthesis of new materials in which organic-inorganic interfaces are the keys to function, biological interfaces and many related material features. PMID:23518477

Zhang, Xiuli; Fan, Zhihai; Lu, Qiang; Huang, Yongli; Kaplan, David L; Zhu, Hesun

2013-06-01

380

Engineering Adipose-like Tissue in vitro and in vivo Utilizing Human Bone Marrow and Adipose-derived Mesenchymal Stem Cells with Silk Fibroin 3D Scaffolds  

OpenAIRE

Biomaterials derived from silk fibrion prepared by aqueous (AB) and organic (HFIP) solvent based processes, along with collagen (COL) and poly-lactic acid (PLA) based scaffolds were studied in vitro and in vivo for their utility in adipose tissue engineering strategies. For in vitro studies, human bone marrow and adipose-derived mesenchymal stem cells (hMSCs and hASCs) were seeded on the various biomaterials and cultured for 21 days in the presence of adipogenic stimulants (AD) or maintained ...

Mauney, Joshua R.; Nguyen, Trang; Gillen, Kelly; Kirker-head, Carl; Gimble, Jeffrey M.; Kaplan, David L.

2007-01-01

381

Nanocomposite gold-silk nanofibers  

OpenAIRE

Cell-biomaterial interactions can be controlled by modifying the surface chemistry or nanotopography of the material, to induce cell proliferation and differentiation if desired. Here we combine both approaches in forming silk nanofibers (SNFs) containing gold nanoparticles (AuNPs) and subsequently chemically modifying the fibers. Silk fibroin mixed with gold seed nanoparticles was electrospun to form SNFs doped with gold seed nanoparticles (SNFseed). Following gold reduction, there was a two...

Cohen-karni, Tzahi; Jeong, Kyung Jae; Tsui, Jonathan H.; Reznor, Gally; Mustata, Mirela; Wanunu, Meni; Graham, Adam; Marks, Carolyn; Bell, David C.; Langer, Robert S.; Kohane, Daniel S.

2012-01-01

382

Clay-Enriched Silk Biomaterials for Bone Formation  

OpenAIRE

The formation of silk protein/clay composite biomaterials for bone tissue formation is described. Silk fibroin serves as an organic scaffolding material offering mechanical stability suitable for bone specific uses. Clay montmorillonite (Cloisite ® Na+) and sodium silicate are sources of osteoinductive silica-rich inorganic species, analogous to bioactive bioglass-like bone repair biomaterial systems. Different clay particle-silk composite biomaterial films were compared to silk films doped ...

Mieszawska, Aneta J.; Llamas, Jabier Gallego; Vaiana, Christopher A.; Kadakia, Madhavi P.; Naik, Rajesh R.; Kaplan, David L.

2011-01-01

383

Negative supercoiling of DNA facilitates an interaction between transcription factor IID and the fibroin gene promoter  

Energy Technology Data Exchange (ETDEWEB)

Transcription of the fibroin gene can be reconstituted with partially purified components from HeLa cells. Transcription factors IIB, IID, and IIE and RNA polymerase II are required for accurate initiation of transcription. Linear and relaxed closed circular DNA show a similar level of template activity. However, transcription of closed circular DNA is stimulated when negative supercoils are introduced by the addition of DNA topoisomerase II and supercoiling factor purified from the posterior silk gland of Bombyx mori. Dissection of transcription into pre- and postinitiation steps by the use of Sarkosyl reveals that DNA supercoiling promotes formation of a preinitiation complex. Furthermore, order of addition experiements suggest that DNA supercoiling facilitates a functional binding of transcription factor IID to the promoter.

Mizutani, Mitsuko; Ohta, Tsutomu; Hirose, Susumu (National Inst. of Genetics, Mishima (Japan)); Watanabe, Hajime; Handa, Hiroshi (Univ. of Tokyo (Japan))

1991-02-01

384

Mechanical and biological performances of new scaffolds made of collagen hydrogels and fibroin microfibers for vascular tissue engineering.  

Science.gov (United States)

A microstructured composite material made of collagen hydrogel (matrix) and silk fibroin microfibers (randomly oriented reinforcing fibers) is investigated in order to conjugate the mechanical resistance of fibroin with the suitable biological performance of collagen to design new scaffolds for vascular tissue engineering. Results show that fibroin microfibers and collagen fibrils have suitable interfacial adhesion, and the scaffold exhibits improved mechanical properties if compared with a pure collagen hydrogel. Furthermore, the overall biological performance is improved. PMID:22847779

de Moraes, Mariana Agostini; Paternotte, Estelle; Mantovani, Diego; Beppu, Marisa Masumi

2012-09-01

385

Production of fine powder from silk by radiation  

Energy Technology Data Exchange (ETDEWEB)

To produce silk fine powder, silk fibroin fibers were irradiated with an accelerated electron beam. Though unirradiated silk fibers were not pulverized at all, irradiated silk fibers were able to be crushed only by physical means using a ball mill. In the dose range of 250- 1000 kGy, as the dose to silk fibroin increased, the conversion rate from fiber to powder was increased. The electron microscope observation showed that the particle size of silk powder was less than 10 micrometers, and that those particles composed aggregate. Although silk fibroin fiber was not soluble in water, silk powders from fiber irradiated 500 kGy dissolved more than 50 weight %. Amino acid analysis of soluble fraction in silk powder showed that Gly content is lower than in normal silk and other amino acids contents except for Ala are 1.5 times as large as in normal silk. From these results, it is reasonable to suppose that irradiation and pulverization decomposed Gly and Ala. (author)

Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Ishida, Kazushige; Kamiishi, Youichi [Textile Research Inst. of Gunma, Kiryu, Gunma (Japan)

2000-09-01

386

A novel marine silk  

Science.gov (United States)

The discovery of a novel silk production system in a marine amphipod provides insights into the wider potential of natural silks. The tube-building corophioid amphipod Crassicorophium bonellii produces from its legs fibrous, adhesive underwater threads that combine barnacle cement biology with aspects of spider silk thread extrusion spinning. We characterised the filamentous silk as a mixture of mucopolysaccharides and protein deriving from glands representing two distinct types. The carbohydrate and protein silk secretion is dominated by complex ?-sheet structures and a high content of charged amino acid residues. The filamentous secretion product exits the gland through a pore near the tip of the secretory leg after having moved through a duct, which subdivides into several small ductules all terminating in a spindle-shaped chamber. This chamber communicates with the exterior and may be considered the silk reservoir and processing/mixing space, in which the silk is mechanically and potentially chemically altered and becomes fibrous. We assert that further study of this probably independently evolved, marine arthropod silk processing and secretion system can provide not only important insights into the more complex arachnid and insect silks but also into crustacean adhesion cements.

Kronenberger, Katrin; Dicko, Cedric; Vollrath, Fritz

2012-01-01