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Sample records for silk gland fibroin

  1. A novel method for dissolution and stabilization of non-mulberry silk gland protein fibroin using anionic surfactant sodium dodecyl sulfate.

    Science.gov (United States)

    Mandal, Biman B; Kundu, S C

    2008-04-15

    The importance of silk protein has increased because of its potential use as a natural biopolymer for tissue engineering and biomedical applications. In this report we show a novel and ecofriendly method for dissolution of gland silk protein fibroin. Non-mulberry silk fibroin from mature fifth instar larvae of Antheraea mylitta was found to be optimally soluble in 1% (w/v) anionic surfactant sodium dodecyl sulfate (SDS). Regenerated fibroin showed distinct bands of approximately 395 and 197 kDa on electrophoresis in non-reducing and reducing conditions, respectively. Enhanced fibroin dissolution via internalization of hydrophobic amino groups inside a hydrophilic amino acid core in the form of micelles was observed. Prolonged storage stability without gelation of SDS-extracted fibroin was seen. Atomic force microscopy showed micellar aggregation with mean micellar aggregation size of 8 nm. Circular dichroism spectroscopy revealed predominantly helical conformation due to surfactant addition with internal protein conformational changes as revealed by fluorescence spectroscopic studies. PMID:17969177

  2. Silk Fibroin Based Porous Materials

    OpenAIRE

    Shuqin Yan; Mingzhong Li; Qiang Zhang

    2009-01-01

    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 perspectiv...

  3. Effect of degumming ph value on electrospining of silk fibroin

    Directory of Open Access Journals (Sweden)

    Lu Shen-Zhou

    2014-01-01

    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.

  4. Surface Immobilization of antibody on silk fibroin through conformational transition

    OpenAIRE

    LU, QIANG; Wang, Xiaoqin; Zhu, Hesun; Kaplan, David L.

    2011-01-01

    In recent studies silk fibroin has been explored as a new material platform for biosensors. Based on these developments a procedure for the immobilization of antibodies on silk fibroin substrates was developed as a route to functionalizing these biosensor systems. By controlling the conformational transition of the silk fibroin, a primary antibody was immobilized and enriched at the surface of silk fibroin substrates under mild reaction conditions to maintain antibody function. Compared to ch...

  5. Ras1CA overexpression in the posterior silk gland improves silk yield

    OpenAIRE

    Ma, Li; Xu, HanFu; Zhu, Jinqi; Ma, SanYuan; Liu, Yan; Jiang, Rong-Jing; Xia, QingYou; Li, Sheng

    2011-01-01

    Sericulture has been greatly advanced by applying hybrid breeding techniques to the domesticated silkworm, Bombyx mori, but has reached a plateau during the last decades. For the first time, we report improved silk yield in a GAL4/UAS transgenic silkworm. Overexpression of the Ras1CA oncogene specifically in the posterior silk gland improved fibroin production and silk yield by 60%, while increasing food consumption by only 20%. Ras activation by Ras1CA overexpression in the posterior silk gl...

  6. Cytocompatibility of a silk fibroin tubular scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiannan, E-mail: wangjn@suda.edu.cn; Wei, Yali; Yi, Honggen; Liu, Zhiwu; Sun, Dan; Zhao, Huanrong

    2014-01-01

    Regenerated silk fibroin (SF) materials are increasingly used for tissue engineering applications. In order to explore the feasibility of a novel biomimetic silk fibroin tubular scaffold (SFTS) crosslinked by poly(ethylene glycol) diglycidyl ether (PEG-DE), biocompatibility with cells was evaluated. The novel biomimetic design of the SFTS consisted of three distinct layers: a regenerated SF intima, a silk braided media and a regenerated SF adventitia. The SFTS exhibited even silk fibroin penetration throughout the braid, forming a porous layered tube with superior mechanical, permeable and cell adhesion properties that are beneficial to vascular regeneration. Cytotoxicity and cell compatibility were tested on L929 cells and human umbilical vein endothelial cells (EA.hy926). DNA content analysis, scanning electron and confocal microscopies and MTT assay showed no inhibitory effects on DNA replication. Cell morphology, viability and proliferation were good for L929 cells, and satisfactory for EA.hy926 cells. Furthermore, the suture retention strength of the SFTS was about 23 N and the Young's modulus was 0.2–0.3 MPa. Collectively, these data demonstrate that PEG-DE crosslinked SFTS possesses the appropriate cytocompatibility and mechanical properties for use as vascular scaffolds as an alternative to vascular autografts. - Highlights: • A PEG-DE cross-linked small caliber porous silk fibroin tubular scaffold (SFTS) • PEG-DE cross-linked SF film had no inhibitory effect on DNA replication of cells. • Cells cultured on the SFTS showed good morphology, cell viability and proliferative activity. • SFTS would be beneficial to endothelialization. • SFTS had good suture retention strength and flexibility.

  7. Production of silk sericin/silk fibroin blend nanofibers

    OpenAIRE

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

    2011-01-01

    Abstract 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 o...

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

    OpenAIRE

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

    2014-01-01

    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...

  9. Controlling silk fibroin particle features for drug delivery

    OpenAIRE

    Lammel, Andreas; Xiao HU; Park, Sang-Hyug; Kaplan, David L.; Scheibel, Thomas

    2010-01-01

    Silk proteins are a promising material for drug delivery due to their aqueous processability, biocompatibility, and biodegradability. A simple aqueous preparation method for silk fibroin particles with controllable size, secondary structure and zeta potential is reported. The particles were produced by salting out a silk fibroin solution with potassium phosphate. The effect of ionic strength and pH of potassium phosphate solution on the yield and morphology of the particles was determined. Se...

  10. Biodegradable materials based on silk fibroin and keratin

    OpenAIRE

    Vasconcelos, Andreia; Freddi, G.; Paulo, Artur Cavaco

    2008-01-01

    Wool and silk were dissolved and used for the preparation of blended films. Two systems are proposed: (1) blend films of silk fibroin and keratin aqueous solutions and (2) silk fibroin and keratin dissolved in formic acid. The FTIR spectra of pure films cast from aqueous solutions indicated that the keratin secondary structure mainly consists of alpha-helix and random coil conformations. The IR spectrum of pure SF is characteristic of films with prevalently amorphous structure (random coil co...

  11. 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.

  12. A novel electrospun silk fibroin/hydroxyapatite hybrid nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Jinfa, E-mail: jinfa.ming@gmail.com [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); Zuo, Baoqi, E-mail: bqzuo@suda.edu.cn [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China)

    2012-11-15

    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 Degree-Sign C, and the degradation peak at 286 Degree-Sign 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: Black-Right-Pointing-Pointer The novel SF/HAp nanofibers were directly prepared by electrospinning method. Black-Right-Pointing-Pointer The nanofiber diameter had significant related to the content of HAp. Black-Right-Pointing-Pointer The crystal structure of silk fibroin was mainly amorphous structure in the hybrid nanofibers. Black-Right-Pointing-Pointer The HAp crystals existing in the hybrid nanofibers were characterized using XRD and FTIR.

  13. 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.)

  14. The degradation behavior of silk fibroin derived from different ionic liquid solvents

    OpenAIRE

    Renchuan You; Ying Zhang; Yu Liu; Guiyang Liu; Mingzhong Li

    2013-01-01

    Establishing an appropriate degradation rate is critical for tissue engineering scaffolds. In this study, the degradation rate of silk fibroin three-dimensional scaffolds was regulated by changing the molecular weight (MW) of the silk fibroin. The solubility of silk fibroin depends primarily on the ionic ability of the slovent to dissolve silk fibroin, therefore, we regulated the MW of the silk fibroin using LiBr, Ca(NO3)2 and CaCl2 to dissolve the silk fibers. SDS-PAGE analysis showed that ...

  15. Nanorheology of regenerated silk fibroin solution

    Indian Academy of Sciences (India)

    A Raghu; Sharath Ananthamurthy

    2008-06-01

    We have investigated the rheological properties of regenerated silk fibroin (RSF), a viscoelastic material at micro and nano length scales, by video microscopy. We describe here the principles and technique of video microscopy as a tool in such investigations. In this work, polystyrene beads were dispersed in the matrix of RSF polymer and the positions of the embedded beads diffusing were tracked using video microscopy. 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. The position information of the beads was used to obtain the time dependant mean squared displacement (MSD) of the beads in the medium and hence to calculate the dynamic moduli of the medium. 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. The technique is complementary to other microrheological techniques to characterize the material, but additionally enables one to characterize local inhomogeneities in the medium, features that get averaged out in bulk characterization procedures.

  16. Microdissection of black widow spider silk-producing glands.

    Science.gov (United States)

    Jeffery, Felicia; La Mattina, Coby; Tuton-Blasingame, Tiffany; Hsia, Yang; Gnesa, Eric; Zhao, Liang; Franz, Andreas; Vierra, Craig

    2011-01-01

    Modern spiders spin high-performance silk fibers with a broad range of biological functions, including locomotion, prey capture and protection of developing offspring. Spiders accomplish these tasks by spinning several distinct fiber types that have diverse mechanical properties. Such specialization of fiber types has occurred through the evolution of different silk-producing glands, which function as small biofactories. These biofactories manufacture and store large quantities of silk proteins for fiber production. Through a complex series of biochemical events, these silk proteins are converted from a liquid into a solid material upon extrusion. Mechanical studies have demonstrated that spider silks are stronger than high-tensile steel. Analyses to understand the relationship between the structure and function of spider silk threads have revealed that spider silk consists largely of proteins, or fibroins, that have block repeats within their protein sequences. Common molecular signatures that contribute to the incredible tensile strength and extensibility of spider silks are being unraveled through the analyses of translated silk cDNAs. Given the extraordinary material properties of spider silks, research labs across the globe are racing to understand and mimic the spinning process to produce synthetic silk fibers for commercial, military and industrial applications. One of the main challenges to spinning artificial spider silk in the research lab involves a complete understanding of the biochemical processes that occur during extrusion of the fibers from the silk-producing glands. Here we present a method for the isolation of the seven different silk-producing glands from the cobweaving black widow spider, which includes the major and minor ampullate glands [manufactures dragline and scaffolding silk], tubuliform [synthesizes egg case silk], flagelliform [unknown function in cob-weavers], aggregate [makes glue silk], aciniform [synthesizes prey wrapping and egg case threads] and pyriform [produces attachment disc silk]. This approach is based upon anesthetizing the spider with carbon dioxide gas, subsequent separation of the cephalothorax from the abdomen, and microdissection of the abdomen to obtain the silk-producing glands. Following the separation of the different silk-producing glands, these tissues can be used to retrieve different macromolecules for distinct biochemical analyses, including quantitative real-time PCR, northern- and western blotting, mass spectrometry (MS or MS/MS) analyses to identify new silk protein sequences, search for proteins that participate in the silk assembly pathway, or use the intact tissue for cell culture or histological experiments. PMID:21248709

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

    OpenAIRE

    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

    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 m...

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

    OpenAIRE

    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

    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 m...

  19. Preparation and characterization of blends containing silk fibroin and chitosan

    International Nuclear Information System (INIS)

    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)

  20. Microrheological Studies of Regenerated Silk Fibroin Solution by Video Microscopy

    OpenAIRE

    A, Raghu; R, Somashekar; Ananthamurthy, Sharath

    2007-01-01

    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 b...

  1. Study On Improving Antioxydant And Antibacterial Activities Of Silk Fibroin By Irradiation Treatment

    International Nuclear Information System (INIS)

    Silk fibroin at dry state and the solution of 3% were irradiated by Co-60 source at dose ranges 0 - 1000 kGy and 0 - 50 kGy respectively. The results showed that irradiation treatment for fibroin solution have higher effectiveness for improvement of some bio-activities of silk fibroin compared with dry state irradiation treatment due to remarkably reducing of irradiation doses. The antioxidant activity of fibroin was significantly increase by irradiation. The maximum value of DPPH radical scavenging activity was 70.4% when fibroin solution was irradiated at dose of 10 kGy. Irradiated fibroin solution also shown antibacterial activity against tested bacteria strains (E. coli, and S. aureus). In order to estimate the applicability of our irradiated fibroin, the silk fibroin solutions were lyophilized to obtain a pure fibroin powder, then their bio-activities were compared with those of commercial silk fibroin (Proteines De Soie/ Zijdeproteine, Bioflore, Canada). Our fibroin powder revealed higher antioxidant and antibacterial activities. The amino acid compositions of our irradiated fibroin were also higher than that of the commercial product. Thus, the irradiated silk fibroin can be used for further application in cosmetic and other related fields. (author)

  2. Silk fibroin aerogels: potential scaffolds for tissue engineering applications.

    Science.gov (United States)

    Mallepally, Rajendar R; Marin, Michael A; Surampudi, Vasudha; Subia, Bano; Rao, Raj R; Kundu, Subhas C; McHugh, Mark A

    2015-06-01

    Silk fibroin (SF) is a natural protein, which is derived from the Bombyx mori silkworm. SF based porous materials are extensively investigated for biomedical applications, due to their biocompatibility and biodegradability. In this work, CO2 assisted acidification is used to synthesize SF hydrogels that are subsequently converted to SF aerogels. The aqueous silk fibroin concentration is used to tune the morphology and textural properties of the SF aerogels. As the aqueous fibroin concentration increases from 2 to 6?wt%, the surface area of the resultant SF aerogels increases from 260 to 308?m(2)?g(-1) and the compressive modulus of the SF aerogels increases from 19.5 to 174?kPa. To elucidate the effect of the freezing rate on the morphological and textural properties, SF cryogels are synthesized in this study. The surface area of the SF aerogels obtained from supercritical CO2 drying is approximately five times larger than the surface area of SF cryogels. SF aerogels exhibit distinct pore morphology compared to the SF cryogels. In vitro cell culture studies with human foreskin fibroblast cells demonstrate the cytocompatibility of the silk fibroin aerogel scaffolds and presence of cells within the aerogel scaffolds. The SF aerogels scaffolds created in this study with tailorable properties have potential for applications in tissue engineering. PMID:25953953

  3. Vortex-Induced Injectable Silk Fibroin Hydrogels

    OpenAIRE

    Yucel, Tuna; Cebe, Peggy; Kaplan, David L.

    2009-01-01

    A novel, to our knowledge, technique was developed to control the rate of ?-sheet formation and resulting hydrogelation kinetics of aqueous, native silk solutions. Circular dichroism spectroscopy indicated that vortexing aqueous solutions of silkworm silk lead to a transition from an overall protein structure that is initially rich in random coil to one that is rich in ?-sheet content. Dynamic oscillatory rheology experiments collected under the same assembly conditions as the circular dichro...

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

    Directory of Open Access Journals (Sweden)

    Zhang Hao

    2012-06-01

    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.

  5. Silk fibroin and sodium alginate blend: Miscibility and physical characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Agostini de Moraes, Mariana; Silva, Mariana Ferreira; Weska, Raquel Farias; Beppu, Marisa Masumi, E-mail: beppu@feq.unicamp.br

    2014-07-01

    Films of silk fibroin (SF) and sodium alginate (SA) blends were prepared by solution casting technique. The miscibility of SF and SA in those blends was evaluated and scanning electron microscopy (SEM) revealed that SF/SA 25/75 wt.% blends underwent microscopic phase separation, resulting in globular structures composed mainly of SF. X-ray diffraction indicated the amorphous nature of these blends, even after a treatment with ethanol that turned them insoluble in water. Thermal analyses of blends showed the peaks of degradation of pristine SF and SA shifted to intermediate temperatures. Water vapor permeability, swelling capacity and tensile strength of SF films could be enhanced by blending with SA. Cell viability remained between 90 and 100%, as indicated by in vitro cytotoxicity test. The SF/SA blend with self-assembled SF globules can be used to modulate structural and mechanical properties of the final material and may be used in designing high performance wound dressing. - Highlights: • Blend films of fibroin and alginate were prepared with microscopic phase separation; • Self-assembled globular microdomains were mainly composed by fibroin; • It was possible to obtain a film with better mechanical and physical properties; • Blend films of fibroin and alginate represent a novel material in biomaterials field.

  6. Silk Fibroin/Starch Blend Films: Preparation and Characterization

    Directory of Open Access Journals (Sweden)

    Prasong Srihanam

    2011-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

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

    Science.gov (United States)

    Werner, Vera; Meinel, Lorenz

    2015-11-01

    The natural process of silk spinning covers a fascinating versatility of aggregate states, ranging from colloidal solutions through hydrogels to solid systems. The transition among these states is controlled by a carefully orchestrated process in vivo. Major players within the natural process include the control of spatial pH throughout passage of the silk dope, the composition and type of ions, and fluid flow mechanics within the duct, respectively. The function of these input parameters on the spinning process is reviewed before detailing their impact on the design and manufacture of silk based drug delivery systems (DDS). Examples are reported including the control of hydrogel formation during storage or significant parameters controlling precipitation in the presence of appropriate salts, respectively. The review details the use of silk fibroin (SF) to develop liquid, semiliquid or solid DDS with a focus on the control of SF crystallization, particle formation, and drug-SF interaction for tailored drug load. PMID:25801494

  9. Silk fibroin/poly(vinyl alcohol) photocrosslinked hydrogels for delivery of macromolecular drugs.

    Science.gov (United States)

    Kundu, Joydip; Poole-Warren, Laura A; Martens, Penny; Kundu, Subhas C

    2012-05-01

    Hydrogels are three-dimensional polymer networks widely used in biomedical applications as drug delivery and tissue engineered scaffolds to effectively repair or replace damaged tissue. In this paper we demonstrate a newly synthesized cytocompatible and drug releasing photo-crosslinked hydrogel based on poly(vinyl alcohol) methacrylate and silk fibroin which possesses tailorable structural and biological properties. The initial silk fibroin content was 0%, 10%, 20%, 30%, 40% and 50% with respect to the weight of poly(vinyl alcohol) methacrylate. The prepared hydrogels were characterized with respect to morphology, crystallinity, stability, swelling, mass loss and cytotoxicity. FITC-dextrans of different molecular weights were chosen as model drugs molecules for release studies from the hydrogels. The hydrogels containing different silk fibroin percentages showed differences in pore size and distribution. X-ray diffraction analysis revealed that amorphous silk fibroin in poly(vinyl alcohol) methacrylate is crystallized to ?-sheet secondary structure upon gelation. The sol fraction increased with increasing fibroin concentration in the co-polymer gel (from 18% to 45%), although the hydrogel extracts were non-cytotoxic. Similarly, the addition of silk fibroin increased water uptake by the gels (from 7% to 21%). FITC-dextran release from the hydrogels was dependent on the silk fibroin content and the molecular weight of encapsulated molecules. The study outlines a newer type of photo-crosslinked interpenetrating polymer network hydrogel that possess immense potential in drug delivery applications. PMID:22285428

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

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Jinfa, E-mail: jinfa.ming@gmail.com [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); Liu, Zhi; Bie, Shiyu [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); Zhang, Feng [Jiangsu Province Key Laboratory of Stem Cell Research, Medical College, Soochow University, Suzhou 215006 (China); Zuo, Baoqi, E-mail: bqzuo@suda.edu.cn [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China)

    2014-04-01

    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 ± 20.4 nm 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 5.0 wt.% 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. - Highlights: • SF fibers were firstly successfully dissolved in FA/HAp solution. • The rheological behavior of SF solution was significantly influenced by HAp contents. • SF nanofibrils were observed in FA/HAp solution with 103.6 ± 20.4 nm in diameter. • SF films prepared by FA/HAp dissolution method had higher mechanical properties.

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

    International Nuclear Information System (INIS)

    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 ± 20.4 nm 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 5.0 wt.% 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. - Highlights: • SF fibers were firstly successfully dissolved in FA/HAp solution. • The rheological behavior of SF solution was significantly influenced by HAp contents. • SF nanofibrils were observed in FA/HAp solution with 103.6 ± 20.4 nm in diameter. • SF films prepared by FA/HAp dissolution method had higher mechanical properties

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

    OpenAIRE

    Baran, E. T.; Tuzlakoglu, K.; J.F. Mano; R. L. Reis

    2012-01-01

    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 ...

  13. Electromechanical response of silk fibroin hydrogel and conductive polycarbazole/silk fibroin hydrogel composites as actuator material.

    Science.gov (United States)

    Srisawasdi, Thanida; Petcharoen, Karat; Sirivat, Anuvat; Jamieson, Alexander M

    2015-11-01

    Pure silk fibroin (SF) hydrogel and polycarbazole/silk fibroin (SF/PCZ) hydrogels were fabricated by solvent casting technique to evaluate electromechanical responses, dielectric properties, and cantilever deflection properties as functions of electric field strength, SF concentration, glutaraldehyde concentration, and PCZ concentration in the blends. Electromechanical properties were characterized in oscillatory shear mode at electric field strengths ranging from 0 to 600V/mm and at a temperature of 27°C. For both the pristine SF and SF/PCZ hydrogels, the storage modulus response (?G') and the storage modulus sensitivity (?G'/G'0) increased dramatically with increasing electric field strength. The pristine hydrogel possessed the highest storage modulus sensitivity value of 5.87, a relatively high value when compared with other previously studied electroactive polymers. With the addition of conductive PCZ in SF hydrogel, the storage modulus sensitivity and the relative dielectric constant decreased; the conductive polymer thus provided the softening effect under electric field. In the deflection response, the dielectrophoresis force and deflection distance increased monotonically with electric field strength, where the pure SF hydrogel showed the highest deflection distance and dielectrophoresis force. PMID:26249559

  14. Will silk fibroin nanofiber scaffolds ever hold a useful place in Translational Regenerative Medicine?

    Science.gov (United States)

    Ubaldo, Armato; Ilaria, Dal Prà; Anna, Chiarini; Giuliano, Freddi

    2011-01-01

    Presently, some view silk fibroin-based biomaterials as obsolete, being outperformed by a host of newly discovered biomaterials. But several lines of evidence support the notion that silk fibroin proteins, especially those from B. mori and spiders and their recombinant forms, particularly in the form of electrospun nanofiber scaffolds, still represent promising tools for human tissue engineering/regeneration. Inevitably, the allure of recently reported biomaterials turns away many scientists and resources from the aim of more deeply elucidating the biological interactions of the various kinds of silk fibroin nanofiber scaffolds in vivo. But, even the biological features of newly reported biomaterials are not investigated in adequate depth. Hence, collaborative efforts among biomaterialists, biomedical experts, and private firms must be undertaken on a much greater scale than hitherto done to assess the real usefulness of silk fibroin proteins, thereby allowing or denying their useful introduction into the fields of Translational Regenerative Medicine. PMID:22928155

  15. Study On Degradation Of Silk Fibroin By Irradiation Treatment For Cosmetic And Pharmaceutical Applications

    International Nuclear Information System (INIS)

    As a kind of protein, silk fibroin is created with silkworm Bombyx mori in products of silk. The fibroin was irradiated using Co-60 gamma source and its degradability and solubility were investigated with various radiation doses to apply in pharmacy and cosmetic. Addition to the morphological changes of irradiated fibroin fibers shows that its mechanical properties were much influenced by the irradiation. Tensile strength and elongation at break of the silk fibroin significantly decreased with increasing of radiation dose up to 1000 kGy. The tensile strength and elongation at break of the irradiated fibroin at 1000 kGy reduced to 71% and 94% respectively in compared with non-irradiated one. The solubility of silk fibroin in both calcium chloride (CaCl2/C2H5OH/H2O=1:2:8) in mole ratio and distilled water were improved by the irradiation. UV spectrometry revealed the structure of silk fibroin was also changed by irradiation. (author)

  16. Microrheological Studies of Regenerated Silk Fibroin Solution by Video Microscopy

    CERN Document Server

    Raghu, A; Somashekar, R; Ananthamurthy, Sharath

    2007-01-01

    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...

  17. Artificial crawler model for texture analysis on silk fibroin scaffolds

    International Nuclear Information System (INIS)

    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. (paper)

  18. Silk fibroin porous scaffolds for nucleus pulposus tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chao; Yang, Qiang [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhu, Meifeng [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Du, Lilong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhang, Jiamin [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Ma, Xinlong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Xu, Baoshan, E-mail: xubaoshan99@126.com [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Wang, Lianyong, E-mail: wly@nankai.edu.cn [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China)

    2014-04-01

    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. - Highlights: • Paraffin microsphere-leaching method is used to fabricate silk fibroin scaffold. • The scaffold has appropriate mechanical property, porosity and pore size • The scaffold supports growth and infiltration of nucleus pulposus cells. • Nucleus pulposus cells can secrete extracellular matrix in the scaffolds. • The scaffold is a potential candidate for tissue engineered nucleus pulposus.

  19. TRANSCRIPTION FACTOR Bmsage PLAYS A CRUCIAL ROLE IN SILK GLAND GENERATION IN SILKWORM, Bombyx mori.

    Science.gov (United States)

    Xin, Hu-Hu; Zhang, Deng-Pan; Chen, Rui-Ting; Cai, Zi-Zheng; Lu, Yan; Liang, Shuang; Miao, Yun-Gen

    2015-10-01

    Salivary gland secretion is altered in Drosophila embryos with loss of function of the sage gene. Saliva has a reduced volume and an increased electron density according to transmission electron microscopy, resulting in regions of tube dilation and constriction with intermittent tube closure. However, the precise functions of Bmsage in silkworm (Bombyx mori) are unknown, although its sequence had been deposited in SilkDB. From this, Bmsage is inferred to be a transcription factor that regulates the synthesis of silk fibroin and interacts with another silk gland-specific transcription factor, namely, silk gland factor-1. In this study, we introduced a germline mutation of Bmsage using the Cas9/sgRNA system, a genome-editing technology, resulting in deletion of Bmsage from the genome of B. mori. Of the 15 tested samples, seven displayed alterations at the target site. The mutagenesis efficiency was about 46.7% and there were no obvious off-target effects. In the screened homozygous mutants, silk glands developed poorly and the middle and posterior silk glands (MSG and PSG) were absent, which was significantly different from the wild type. The offspring of G0 mosaic silkworms had indel mutations causing 2- or 9-bp deletions at the target site, but exhibited the same abnormal silk gland structure. Mutant larvae containing different open-reading frames of Bmsage had the same silk gland phenotype. This illustrated that the mutant phenotype was due to Bmsage knockout. We conclude that Bmsage participates in embryonic development of the silk gland. PMID:25917878

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

    Science.gov (United States)

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

    2010-05-11

    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

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

    Scientific Electronic Library Online (English)

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

    2009-06-01

    Full Text Available 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.

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

    Directory of Open Access Journals (Sweden)

    Raquel Farias Weska

    2009-06-01

    Full Text Available 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.

  3. Controlling silk fibroin microspheres via molecular weight distribution.

    Science.gov (United States)

    Zeng, Dong-Mei; Pan, Jue-Jing; Wang, Qun; Liu, Xin-Fang; Wang, Hui; Zhang, Ke-Qin

    2015-05-01

    Silk fibroin (SF) microspheres were produced by salting out SF solution via the addition of potassium phosphate buffer solution (K2HPO4-KH2PO4). The morphology, size and polydispersity of SF microspheres were adjusted by changing the molecular weight (MW) distribution and concentration of SF, as well as the ionic strength and pH of the buffer solution. Changing the conditions under which the SF fiber dissolved in the Lithium Boride (LiBr) solution resulted in altering the MW distribution of SF solution. Under optimal salting-out conditions (ionic strength>0.7 M and pH>7) and using a smaller and narrower SF MW distribution, SF microspheres with smoother shapes and more uniform sizes were produced. Meanwhile, the size and polydispersity of the microspheres increased when the SF concentration was increased from 0.25 mg/mL to 20 mg/mL. The improved SF microspheres, obtained by altering the distribution of molecular weight, have potential in drug and gene delivery applications. PMID:25746265

  4. Preparation and Characterization of Nanocomposite and Nanoporous Silk Fibroin Films

    Directory of Open Access Journals (Sweden)

    Yaowalak Srisuwan

    2008-01-01

    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.

  5. 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 controlled drug delivery.

  6. Coaxial electrospun aligned tussah silk fibroin nanostructured fiber scaffolds embedded with hydroxyapatite-tussah silk fibroin nanoparticles for bone tissue engineering.

    Science.gov (United States)

    Shao, Weili; He, Jianxin; Sang, Feng; Ding, Bin; Chen, Li; Cui, Shizhong; Li, Kejing; Han, Qiming; Tan, Weilin

    2016-01-01

    The bone is a composite of inorganic and organic materials and possesses a complex hierarchical architecture consisting of mineralized fibrils formed by collagen molecules and coated with oriented hydroxyapatite. To regenerate bone tissue, it is necessary to provide a scaffold that mimics the architecture of the extracellular matrix in native bone. Here, we describe one such scaffold, a nanostructured composite with a core made of a composite of hydroxyapatite and tussah silk fibroin. The core is encased in a shell of tussah silk fibroin. The composite fibers were fabricated by coaxial electrospinning using green water solvent and were characterized using different techniques. In comparison to nanofibers of pure tussah silk, composite notably improved mechanical properties, with 90-fold and 2-fold higher initial modulus and breaking stress, respectively, obtained. Osteoblast-like MG-63 cells were cultivated on the composite to assess its suitability as a scaffold for bone tissue engineering. We found that the fiber scaffold supported cell adhesion and proliferation and functionally promoted alkaline phosphatase and mineral deposition relevant for biomineralization. In addition, the composite were more biocompatible than pure tussah silk fibroin or cover slip. Thus, the nanostructured composite has excellent biomimetic and mechanical properties and is a potential biocompatible scaffold for bone tissue engineering. PMID:26478319

  7. Peptide-Graphene Interactions Enhance the Mechanical Properties of Silk Fibroin.

    Science.gov (United States)

    Cheng, Yuan; Koh, Leng-Duei; Li, Dechang; Ji, Baohua; Zhang, Yingyan; Yeo, Jingjie; Guan, Guijian; Han, Ming-Yong; Zhang, Yong-Wei

    2015-10-01

    Studies reveal that biomolecules can form intriguing molecular structures with fascinating functionalities upon interaction with graphene. Then, interesting questions arise. How does silk fibroin interact with graphene? Does such interaction lead to an enhancement in its mechanical properties? In this study, using large-scale molecular dynamics simulations, we first examine the interaction of graphene with several typical peptide structures of silk fibroin extracted from different domains of silk fibroin, including pure amorphous (P1), pure crystalline (P2), a segment from N-terminal (P3), and a combined amorphous and crystalline segment (P4), aiming to reveal their structural modifications. Our study shows that graphene can have intriguing influences on the structures formed by the peptides with sequences representing different domains of silk fibroin. In general, for protein domains with stable structure and strong intramolecular interaction (e.g., ?-sheets), graphene tends to compete with the intramolecular interactions and thus weaken the interchain interaction and reduce the contents of ?-sheets. For the silk domains with random or less ordered secondary structures and weak intramolecular interactions, graphene tends to enhance the stability of peptide structures; in particular, it increases the contents of helical structures. Thereafter, tensile simulations were further performed on the representative peptides to investigate how such structure modifications affect their mechanical properties. It was found that the strength and resilience of the peptides are enhanced through their interaction with graphene. The present work reveals interesting insights into the interactions between silk peptides and graphene, and contributes in the efforts to enhance the mechanical properties of silk fibroin. PMID:26364925

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  9. 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 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.

  10. Modified silk fibroin scaffolds with collagen/decellularized pulp for bone tissue engineering in cleft palate: Morphological structures and biofunctionalities.

    Science.gov (United States)

    Sangkert, Supaporn; Meesane, Jirut; Kamonmattayakul, Suttatip; Chai, Wen Lin

    2016-01-01

    Cleft palate is a congenital malformation that generates a maxillofacial bone defect around the mouth area. The creation of performance scaffolds for bone tissue engineering in cleft palate is an issue that was proposed in this research. Because of its good biocompatibility, high stability, and non-toxicity, silk fibroin was selected as the scaffold of choice in this research. Silk fibroin scaffolds were prepared by freeze-drying before immerging in a solution of collagen, decellularized pulp, and collagen/decellularized pulp. Then, the immersed scaffolds were freeze-dried. Structural organization in solution was observed by Atomic Force Microscope (AFM). The molecular organization of the solutions and crystal structure of the scaffolds were characterized by Fourier transform infrared (FT-IR) and X-ray diffraction (XRD), respectively. The weight increase of the modified scaffolds and the pore size were determined. The morphology was observed by a scanning electron microscope (SEM). Mechanical properties were tested. Biofunctionalities were considered by seeding osteoblasts in silk fibroin scaffolds before analysis of the cell proliferation, viability, total protein assay, and histological analysis. The results demonstrated that dendrite structure of the fibrils occurred in those solutions. Molecular organization of the components in solution arranged themselves into an irregular structure. The fibrils were deposited in the pores of the modified silk fibroin scaffolds. The modified scaffolds showed a beta-sheet structure. The morphological structure affected the mechanical properties of the silk fibroin scaffolds with and without modification. Following assessment of the biofunctionalities, the modified silk fibroin scaffolds could induce cell proliferation, viability, and total protein particularly in modified silk fibroin with collagen/decellularized pulp. Furthermore, the histological analysis indicated that the cells could adhere in modified silk fibroin scaffolds. Finally, it can be deduced that modified silk fibroin scaffolds with collagen/decellularized pulp had the performance for bone tissue engineering and a promise for cleft palate treatment. PMID:26478414

  11. 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)

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

    International Nuclear Information System (INIS)

    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 ?-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 ?-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 ?-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

  13. 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 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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  15. Proteomic Evidence for Components of Spider Silk Synthesis from Black Widow Silk Glands and Fibers.

    Science.gov (United States)

    Chaw, Ro Crystal; Correa-Garhwal, Sandra M; Clarke, Thomas H; Ayoub, Nadia A; Hayashi, Cheryl Y

    2015-10-01

    Spider silk research has largely focused on spidroins, proteins that are the primary components of spider silk fibers. Although a number of spidroins have been characterized, other types of proteins associated with silk synthesis are virtually unknown. Previous analyses of tissue-specific RNA-seq libraries identified 647 predicted genes that were differentially expressed in silk glands of the Western black widow, Latrodectus hesperus. Only ?5% of these silk-gland specific transcripts (SSTs) encode spidroins; although the remaining predicted genes presumably encode other proteins associated with silk production, this is mostly unverified. Here, we used proteomic analysis of multiple silk glands and dragline silk fiber to investigate the translation of the differentially expressed genes. We find 48 proteins encoded by the differentially expressed transcripts in L. hesperus major ampullate, minor ampullate, and tubuliform silk glands and detect 17 SST encoded proteins in major ampullate silk fibers. The observed proteins include known silk-related proteins, but most are uncharacterized, with no annotation. These unannotated proteins likely include novel silk-associated proteins. Major and minor ampullate glands have the highest overlap of identified proteins, consistent with their shared, distinctive ampullate shape and the overlapping functions of major and minor ampullate silks. Our study substantiates and prioritizes predictions from differential expression analysis of spider silk gland transcriptomes. PMID:26302244

  16. The influence of UV-irradiation on thermal and mechanical properties of chitosan and silk fibroin mixtures.

    Science.gov (United States)

    Sionkowska, Alina; P?anecka, Anna; Lewandowska, Katarzyna; Michalska, Marta

    2014-11-01

    In the present paper the results regarding the influence of UV-irradiation with 254 nm wavelength on the thermal and mechanical properties and the intrinsic viscosity of chitosan/silk fibroin mixtures are presented. The mixture of chitosan and silk fibroin in solution and thin films made of chitosan/silk fibroin mixture obtained by solvent evaporation were submitted to the treatment with UV irradiation (wavelength 254 nm) for different time intervals. Mechanical properties of thin films made of chitosan/silk fibroin blends before and after UV-irradiation have been investigated by mechanical testing machine and compared with mechanical properties of chitosan films. The changes in such mechanical properties as ultimate breaking strength, percentage of elongation at break and Young Modulus have been investigated. The results have shown, that the mechanical properties of the blends were greatly affected by time of exposure to UV irradiation. Ultimate tensile strength and ultimate percentage of elongation decreased after UV irradiation of the blend. Increasing UV irradiation led to the decrease in Young's Modulus of the chitosan/silk fibroin blend. Viscosity of chitosan/silk fibroin mixtures decreased after UV-irradiation. Thermal properties of the mixtures have been only slightly altered by UV-irradiation. PMID:25218587

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

    Science.gov (United States)

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

    2013-12-01

    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

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

    Science.gov (United States)

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

    2007-01-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  20. 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 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.

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

    Directory of Open Access Journals (Sweden)

    Renchuan You

    2014-06-01

    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.

  2. Gamma-ray irradiation synthesis of silk fibroin-coated CdS quantum dots

    International Nuclear Information System (INIS)

    Silk fibroin coated CdS quantum dots (SF-CdS QDs) were successfully synthesized in an aqueous system at room temperature under 60Co ?-ray irradiation. The prepared QDs were characterized by transmission electron microscopy (TEM), energy dispersion spectrometry (EDS), Fourier transform infrared spectrometer(FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis) and photoluminescence (PL) spectrometry. The synthesized QDs were about 5 nm in diameter with excellent water-solubility. The QDs showed strong visible yellow-green luminescence under UV excitation, at an emission peak of around 538 nm. This method could be conveniently extended to fabricate other nanoparticles coated with silk fibroin. (authors)

  3. Modulated Degradation of Transient Electronic Devices through Multilayer Silk Fibroin Pockets.

    Science.gov (United States)

    Brenckle, Mark A; Cheng, Huanyu; Hwang, Sukwon; Tao, Hu; Paquette, Mark; Kaplan, David L; Rogers, John A; Huang, Yonggang; Omenetto, Fiorenzo G

    2015-09-16

    The recent introduction of transient, bioresorbable electronics into the field of electronic device design offers promise for the areas of medical implants and environmental monitors, where programmed loss of function and environmental resorption are advantageous characteristics. Materials challenges remain, however, in protecting the labile device components from degradation at faster than desirable rates. Here we introduce an indirect passivation strategy for transient electronic devices that consists of encapsulation in multiple air pockets fabricated from silk fibroin. This approach is investigated through the properties of silk as a diffusional barrier to water penetration, coupled with the degradation of magnesium-based devices in humid air. Finally, silk pockets are demonstrated to be useful for controlled modulation of device lifetime. This approach may provide additional future opportunities for silk utility due to the low immunogenicity of the material and its ability to stabilize labile biotherapeutic dopants. PMID:26305434

  4. Structural and thermal properties of ? - irradiated Bombyx mori silk fibroin films

    Science.gov (United States)

    Madhukumar, R.; Asha, S.; Sarojini, B. K.; Somashekar, R.; Rao, B. Lakshmeesha; Shivananda, C. S.; Harish, K. V.; Sangappa

    2015-06-01

    The gamma radiation-induced change in structural and thermal properties of Bombyx mori silk fibroin films were investigated and have been correlated with the applied radiation doses. Irradiation of samples were carried out in dry air at room temperature using Co-60 source, and radiation doses are in the range of 0 - 300 kGy. Structural and thermal properties of the irradiated silk films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA) and compared with unirradiated sample. Interesting results are discussed in this report.

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

    OpenAIRE

    Chih-Hao Chen; Jolene Mei-Jun Liu; Chee-Kai Chua; Siaw-Meng Chou; Victor Bong-Hang Shyu; Jyh-Ping Chen

    2014-01-01

    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 wit...

  6. Effect of silk fibroin nanofibers containing silver sulfadiazine on wound healing

    OpenAIRE

    Jeong L; Kim MH; Jung JY; Min BM; Park WH

    2014-01-01

    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...

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

    OpenAIRE

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

    2012-01-01

    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 unifo...

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

    OpenAIRE

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

    2009-01-01

    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 propertie...

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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)

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

    OpenAIRE

    Vishal Gupta; Abraham Aseh; Carmen N Ríos; Aggarwal, Bharat B; et. al.

    2009-01-01

    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 ...

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

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

    Directory of Open Access Journals (Sweden)

    Hong-sheng Wang

    2010-09-01

    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.

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

    Directory of Open Access Journals (Sweden)

    M. Fazley Elahi

    2014-04-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  15. 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 feasible.

  16. Bioactive macro/micro porous silk fibroin/Nano-sized calcium phosphate scaffolds with potential for bone tissue engineering applications

    OpenAIRE

    Yan, Leping; Correia, Joana Silva; Correia, C.; Caridade, S. G.; Fernandes, E. M.; Sousa, R.A; J.F. Mano; Oliveira, Joaquim M.; Oliveira, A. L.; R. L. Reis

    2013-01-01

    Aim: The development of novel silk/nano-sized calcium phosphate (silk/nano-CaP) scaffolds with highly dispersed CaP nanoparticles in the silk fibroin (SF) matrix for bone tissue engineering. Materials & methods: Nano-CaP was incorporated in a concentrated aqueous SF solution (16 wt.%) by using an in situ synthesis method. The silk/nano-CaP scaffolds were then prepared through a combination of salt-leaching/ lyophilization approaches. Results: The CaP particles presented good affin...

  17. Mechanically-reinforced electrospun composite silk fibroin nanofibers containing hydroxyapatite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunryung [School of Mechanical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Che, Lihua; Ha, Yoon [Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 120-749 (Korea, Republic of); Ryu, WonHyoung, E-mail: whryu@yonsei.ac.kr [School of Mechanical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2014-07-01

    Electrospun silk fibroin (SF) scaffolds provide large surface area, high porosity, and interconnection for cell adhesion and proliferation and they may replace collagen for many tissue engineering applications. Despite such advantages, electrospun SF scaffolds are still limited as bone tissue replacement due to their low mechanical strengths. While enhancement of mechanical strengths by incorporating inorganic ceramics into polymers has been demonstrated, electrospinning of a mixture of SF and inorganic ceramics such as hydroxyapatite is challenging and less studied due to the aggregation of ceramic particles within SF. In this study, we aimed to enhance the mechanical properties of electrospun SF scaffolds by uniformly dispersing hydroxyapatite (HAp) nanoparticles within SF nanofibers. HAp nanoaprticles were modified by ?-glycidoxypropyltrimethoxysilane (GPTMS) for uniform dispersion and enhanced interfacial bonding between HAp and SF fibers. Optimal conditions for electrospinning of SF and GPTMS-modified HAp nanoparticles were identified to achieve beadless nanofibers without any aggregation of HAp nanoparticles. The MTT and SEM analysis of the osteoblasts-cultured scaffolds confirmed the biocompatibility of the composite scaffolds. The mechanical properties of the composite scaffolds were analyzed by tensile tests for the scaffolds with varying contents of HAp within SF fibers. The mechanical testing showed the peak strengths at the HAp content of 20 wt.%. The increase of HAp content up to 20 wt.% increased the mechanical properties of the composite scaffolds, while further increase above 20 wt.% disrupted the polymer chain networks within SF nanofibers and weakened the mechanical strengths. - Highlights: • Electrospun composite silk fibroin scaffolds were mechanically-reinforced. • GPTMS enhanced hydroxyapatite distribution in silk fibroin nanofibers. • Mechanical property of composite scaffolds increased up to 20% of hydroxyapatite. • Composite scaffolds showed cell viability comparable to collagen.

  18. Mechanically-reinforced electrospun composite silk fibroin nanofibers containing hydroxyapatite nanoparticles

    International Nuclear Information System (INIS)

    Electrospun silk fibroin (SF) scaffolds provide large surface area, high porosity, and interconnection for cell adhesion and proliferation and they may replace collagen for many tissue engineering applications. Despite such advantages, electrospun SF scaffolds are still limited as bone tissue replacement due to their low mechanical strengths. While enhancement of mechanical strengths by incorporating inorganic ceramics into polymers has been demonstrated, electrospinning of a mixture of SF and inorganic ceramics such as hydroxyapatite is challenging and less studied due to the aggregation of ceramic particles within SF. In this study, we aimed to enhance the mechanical properties of electrospun SF scaffolds by uniformly dispersing hydroxyapatite (HAp) nanoparticles within SF nanofibers. HAp nanoaprticles were modified by ?-glycidoxypropyltrimethoxysilane (GPTMS) for uniform dispersion and enhanced interfacial bonding between HAp and SF fibers. Optimal conditions for electrospinning of SF and GPTMS-modified HAp nanoparticles were identified to achieve beadless nanofibers without any aggregation of HAp nanoparticles. The MTT and SEM analysis of the osteoblasts-cultured scaffolds confirmed the biocompatibility of the composite scaffolds. The mechanical properties of the composite scaffolds were analyzed by tensile tests for the scaffolds with varying contents of HAp within SF fibers. The mechanical testing showed the peak strengths at the HAp content of 20 wt.%. The increase of HAp content up to 20 wt.% increased the mechanical properties of the composite scaffolds, while further increase above 20 wt.% disrupted the polymer chain networks within SF nanofibers and weakened the mechanical strengths. - Highlights: • Electrospun composite silk fibroin scaffolds were mechanically-reinforced. • GPTMS enhanced hydroxyapatite distribution in silk fibroin nanofibers. • Mechanical property of composite scaffolds increased up to 20% of hydroxyapatite. • Composite scaffolds showed cell viability comparable to collagen

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.)

  20. The outermost surface properties of silk fibroin films reflect ethanol-treatment conditions used in biomaterial preparation.

    Science.gov (United States)

    Terada, Dohiko; Yokoyama, Yoshiyuki; Hattori, Shinya; Kobayashi, Hisatoshi; Tamada, Yasushi

    2016-01-01

    Silk fibroin has attracted interest as a biomaterial, given its many excellent properties. Cell attachment to silk substrates is usually weaker than to standard culture dishes, and cells cultured on silk films or hydrogels typically form spheroids and micro-aggregates. However, too little is known about the higher order structures and behavior of fibroin under different conditions to explain the features of silk fibroin as a culture substrate. For instance, different biomaterial surfaces, with distinct effects on cell culture, can be achieved by varying the conditions of crystallization by alcohol immersion. Here, we show that treatment of fibroin film with 90% ethanol has a harder surface than the alcohol concentration on the surface properties, based on surface analysis of the films. The surface analysis involved assessment of static and dynamic contact angles, zeta potential, changes in crystallinity and microscopic morphology of electrospun fibers, and texture changes of the outermost surface at a nanometer-scale captured by a scanning probe microscope. PMID:26478294

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

    Science.gov (United States)

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

    2015-01-01

    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

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

    International Nuclear Information System (INIS)

    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

  3. Antitumor properties of platinum(iv) prodrug-loaded silk fibroin nanoparticles.

    Science.gov (United States)

    Lozano-Pérez, A Abel; Gil, Ana L; Pérez, Sergio A; Cutillas, Natalia; Meyer, Hajo; Pedreño, Mónica; D Aznar-Cervantes, Salvador; Janiak, Christoph; Cenis, Jose Luis; Ruiz, José

    2015-08-14

    Platinum(iv) complexes take advantage of the exclusive conditions that occur within the tumor to carry out their cytotoxic activity. On the other hand, silk fibroin has natural properties which make it very interesting as a biomaterial: high biocompatibility, biodegradability, low immunogenicity, high cellular penetration capacity and high reactive surface. Herein we report the preparation of silk fibroin nanoparticles (SFNs) loaded with the hydrophobic Pt(iv) complex cis,cis,trans-[Pt(NH(3))(2)Cl(2)(O(2)CC(6)H(5))(2)] (PtBz). Only a small fraction of the loaded PtBz is released (less than 10% after 48 h). PtBz-SFNs trigger strong cytotoxic effects against human ovarian carcinoma A2780 cells and their cisplatin-resistant variant A2780cisR cells. Interestingly, PtBz-SFNs are very cytotoxic (nanomolar IC(50) values) toward the triple negative breast tumor cell line MDA-MB-231, and also toward SK-BR-3 and MCF-7, while maintaining an excellent selectivity index. PMID:25799077

  4. Novel eatable silk fibroin gels containing salbutamol sulphate for dysphagic and geriatric patients

    Directory of Open Access Journals (Sweden)

    Dixit Anil Satyanarayana

    2012-01-01

    Full Text Available The purpose of this research work is to prepare novel eatable gel formulations with suitable rheological characteristics, which provide a means of administering salbutamol sulphate to dysphagic and geriatric patients. Gels prepared using a natural polymer silk fibroin of different concentrations was subjected for in vitro characterization. The effect of concentration of the solution on gelation time, viscosity, and drug release was studied. FTIR and DSC spectra reveal that the drug was found compatible with silk fibroin. TGA curves showed weight loss as the temperature increased. Formulations F3, F4, F6, and F9 had thin, nectar like, honey like, and spoon thick viscosity range respectively, which is considered suitable for dysphagia patients as given by National Dysphagia Diet Task Force. Formulations showed shear thinning pseudoplastic behavior. Based on the concentration and viscosity of the polymer, formulation F9 was found to sustain the release of drug up to 90 min (99.4 ± 0.5%, whereas F3 showed release within 5 min (99.2 ± 2.0%. Mechanism of drug release was found to be anomalous transport. All formulations were found stable after 6 months when kept at refrigerated temperature (4°C - 8°C and room temperature. It can be concluded that the salbutamol sulphate gels prepared are suitable as vehicles for dysphagic patients.

  5. 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

  6. Silklike materials constructed from sequences of Bombyx mori silk fibroin, fibronectin, and elastin.

    Science.gov (United States)

    Yang, Mingying; Tanaka, Chikako; Yamauchi, Kazuo; Ohgo, Kosuke; Kurokawa, Masato; Asakura, Tetsuo

    2008-02-01

    Two silklike proteins, [TGRGDSPAGG(GAGAGS)3AS]5 (FS5) and [TGRGDSPA-(GVPGV)2GG(GAGAGS)3AS]8 (FES8) were designed to demonstrate the superior performance as biomaterials of silklike proteins. The former protein consists of the crystalline domain sequence, (GAGAGS)n from Bombyx mori silk fibroin and cell-adhesive sequence TGRGDSPA coming from fibronectin-containing RGD triplet. The additional sequence (GVPGV)n from elastin was included in the latter protein. The considerably higher cell-adhesion activities of these proteins for NHDF and VERO cells were observed by comparing with those of silklike materials without RGD sequences and also the crystalline fraction of B. mori silk fibroin. This tendency was independent of the treatments, 4.5M LiClO4 or formic acid (FA), on silklike proteins. Their activities are also higher than those of commercial Fibronectin F for NHDF cell. Their structural characterization was studied using 13C solid-state NMR. Although the overlapped peaks in usual 13C CP/MAS NMR spectra make the detailed structural analysis difficult, the methyl resonance regions observed using dipolar dephasing NMR were very useful for the analysis. The presence of both random coil and beta-sheet structures was observed in these proteins clearly. The content of beta-sheet structure in both proteins increases after FA treatment when compared with the lyophilized samples. The production of electrospun nanofibers from their hexafluoroacetone solution was also tried. The silklike protein FES8 could prepare nonwoven silk fibers although FS5 could not. PMID:17618489

  7. Modulation of Self-Assembly Process of Fibroin: An Insight for Regulating the Conformation of Silk Biomaterials.

    Science.gov (United States)

    Dubey, Priyanka; Murab, Sumit; Karmakar, Sandip; Chowdhury, Pramit K; Ghosh, Sourabh

    2015-12-14

    Controlling the mechanism of self-assembly in proteins has emerged as a potent tool for various biomedical applications. Silk fibroin self-assembly consists of gradual conformational transition from random coil to ?-sheet structure. In this work we elucidated the intermediate secondary conformation in the presence of Ca(2+) ions during fibroin self-assembly. The interaction of fibroin and calcium ions resulted in a predominantly ?-helical intermediate conformation, which was maintained to certain extent even in the final conformation as illustrated by circular dichroism and attenuated total reflectance-Fourier transform infrared spectroscopy. Further, to elucidate the mechanism behind this interaction molecular modeling of the N-terminal region of fibroin with Ca(2+) ions was performed. Negatively charged glutamate and aspartate amino acids play a key role in the electrostatic interaction with positively charged calcium ions. Therefore, insights about modulation of self-assembly mechanism of fibroin could potentially be utilized to develop silk-based biomaterials consisting of the desired secondary conformation. PMID:26575529

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

    International Nuclear Information System (INIS)

    The Bombyx mori silk fibroin films (SFFs) were modified by a Cecropin B (CB) antimicrobial peptide, (NH2)-NGIVKAGPAIAVLGEAAL-CONH2, 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)

  9. 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

  10. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  12. Preparation and characterization of a bacterial cellulose/silk fibroin sponge scaffold for tissue regeneration.

    Science.gov (United States)

    Oliveira Barud, H G; Barud, Hernane da S; Cavicchioli, Maurício; do Amaral, Thais Silva; de Oliveira Junior, Osmir Batista; Santos, Diego M; Petersen, Antonio Luis de Oliveira Almeida; Celes, Fabiana; Borges, Valéria Matos; de Oliveira, Camila I; de Oliveira, Pollyanna Francielli; Furtado, Ricardo Andrade; Tavares, Denise Crispim; Ribeiro, Sidney J L

    2015-09-01

    Bacterial cellulose (BC) and silk fibroin (SF) are natural biopolymers successfully applied in tissue engineering and biomedical fields. In this work nanocomposites based on BC and SF were prepared and characterized by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). In addition, the investigation of cytocompatibility was done by MTT, XTT and Trypan Blue dye technique. Cellular adhesion and proliferation were detected additionally. The evaluation of genotoxicity was realized by micronucleus assay. In vitro tests showed that the material is non-cytotoxic or genotoxic. SEM images revealed a greater number of cells attached at the BC/SF:50% scaffold surface than the pure BC one, suggesting that the presence of fibroin improved cell attachment. This could be related to the SF amino acid sequence that acts as cell receptors facilitating cell adhesion and growth. Consequently, BC/SF:50% scaffolds configured an excellent option in bioengineering depicting its potential for tissue regeneration and cultivation of cells on nanocomposites. PMID:26005138

  13. Effect of silk fibroin nanofibers containing silver sulfadiazine on wound healing

    Directory of Open Access Journals (Sweden)

    Jeong L

    2014-11-01

    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

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

    Directory of Open Access Journals (Sweden)

    Vishal Gupta

    2009-05-01

    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

  15. In situ depositing silver nanoclusters on silk fibroin fibers supports by a novel biotemplate redox technique at room temperature.

    Science.gov (United States)

    Dong, Qun; Su, Huilan; Zhang, Di

    2005-09-22

    Evolvement of bioinspired approaches for the construction of well-ordered nanostructures is a crucial intersection of branches of materials science and biotechnology. In this paper, floriated clusters of silver nanocrystallites, which consist of polycrystalline grains about 5 nm in diameter, have been successfully prepared on silk fibroin fibers (SFFs) through an in situ biotemplate redox approach at room temperature. The reductive amino acid tyrosine of SFFs mainly provided both reduction and location functions under alkaline conditions and could reduce Ag(I) ions to Ag(0). Finally, stable silver nanoclusters were generated on SFF substrates. The morphologies of silver nanoclusters were mostly attributed to the concentration of silver nitrate solution as well as special configurations and structures of silk fibroin macromolecules. A possible mechanism was explored intensively for tyrosine-residue-based silver nanocrystal formation. PMID:16853228

  16. 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)

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

    OpenAIRE

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

    2012-01-01

    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...

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

    OpenAIRE

    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

    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...

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

    Science.gov (United States)

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

    2014-12-10

    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

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

    Science.gov (United States)

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

    2014-12-01

    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

  1. Silk fibroin hydrolysate exerts an anti-diabetic effect by increasing pancreatic ? cell mass in C57BL/KsJ-db/db mice

    OpenAIRE

    Do, Sun-Gil; Park, Jun-Hong; Nam, Hajin; Kim, Jin-Bong; Lee, Jae-Yong; Oh, Yang-Seok; Suh, Jun-Gyo

    2012-01-01

    Components of silk including silk fibroin have long been used as anti-diabetic remedies in oriental medicine. However, detailed mechanisms underlying these anti-diabetic effects remain unclear. In this study, we examined the anti-diabetic activity of silk fibroin hydrolysate (SFH) in C57BL/KsJ-db/db (db/db) mice, a well-known animal model of non-insulin dependent diabetes mellitus. When the db/db mice were administered SFH in drinking water for 6 weeks, hyperglycemia in the animals gradually ...

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

    OpenAIRE

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

    2014-01-01

    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...

  3. Directing osteogenesis of stem cells with hydroxyapatite precipitated electrospun eri-tasar silk fibroin nanofibrous scaffold.

    Science.gov (United States)

    Panda, N; Bissoyi, A; Pramanik, K; Biswas, A

    2014-01-01

    Stimulating stem cell differentiation without growth factor supplement offers a potent and cost-effective scaffold for tissue regeneration. We hypothesise that surface precipitation of nano-hydroxyapatite (nHAp) over blends of non-mulberry silk fibroin with better hydrophilicity and RGD amino acid sequences can direct the stem cell towards osteogenesis. This report focuses on the fabrication of a blended eri-tasar silk fibroin nanofibrous scaffold (ET) followed by nHAp deposition by a surface precipitation (alternate soaking in calcium and phosphate solution) method. Morphology, hydrophilicity, composition, and the thermal and mechanical properties of ET/nHAp were examined by field emission scanning electron microscopy, TEM, FT-IR, X-ray diffraction, TGA and contact angle measurement and compared with ET. The composite scaffold demonstrated improved thermal stability and surface hydrophilicity with an increase in stiffness and elastic modulus (778?±?2.4?N/m and 13.1?±?0.36?MPa) as compared to ET (160.6?±?1.34?N/m and 8.3?±?0.4?MPa). Mineralisation studies revealed an enhanced and more uniform surface deposition of HAp-like crystals, while significant differences in cellular viability and attachment were observed through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and confocal microscopy study. The cell viability and expression of adhesion molecules (CD 44 and CD 29) are found to be optimum for subsequent stages of growth proliferation and differentiation. The rates of proliferation have been observed to decrease owing to the transition of MSC from a state of proliferation to a state of differentiation. The confirmation of improved osteogenic differentiation was finally verified through the alkaline phosphatase assay, pattern of gene expression related to osteogenic differentiation and morphological observations of differentiated cord blood human mesenchymal stem cells under fluorescence microscope. The results obtained showed the improved physicochemical and biological properties of the ET/nHAp scaffold for osteogenic differentiation without the addition of any growth factors. PMID:25090157

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

    International Nuclear Information System (INIS)

    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. - Highlights: • Electrospinning of PHBV/nHAp composites was first achieved using silk fibroin (SF). • Smooth, uniform, continuous fibres with diameters between 10 and 15 ?m were deposited. • Bioactivity was confirmed by surface apatite formation in Simulated Body Fluid. • Tensile modulus was increased for 2% nHAp and SF relative to 0% and 5% cases. • PHBV/nHAp/SF composites support initial osteoblast attachment and proliferation

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

    Energy Technology Data Exchange (ETDEWEB)

    Pa?cu, Elena I.; Stokes, Joseph; McGuinness, Garrett B., E-mail: garrett.mcguinness@dcu.ie

    2013-12-01

    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. - Highlights: • Electrospinning of PHBV/nHAp composites was first achieved using silk fibroin (SF). • Smooth, uniform, continuous fibres with diameters between 10 and 15 ?m were deposited. • Bioactivity was confirmed by surface apatite formation in Simulated Body Fluid. • Tensile modulus was increased for 2% nHAp and SF relative to 0% and 5% cases. • PHBV/nHAp/SF composites support initial osteoblast attachment and proliferation.

  6. 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)

    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

    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)

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

    Directory of Open Access Journals (Sweden)

    Baimark Yodthong

    2010-01-01

    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.

  8. Effect of shear viscosity on the preparation of sphere-like silk fibroin microparticles by electrospraying.

    Science.gov (United States)

    Kim, Moo Kon; Lee, Jeong Yun; Oh, Hanjin; Song, Dae Woong; Kwak, Hyo Won; Yun, Haesung; Um, In Chul; Park, Young Hwan; Lee, Ki Hoon

    2015-08-01

    Silk fibroin (SF) is known to be a biocompatible material, and different forms of SF are used for various applications. However, the application of SF in particle form is rarely reported, compared to other forms. In this study, SF microparticles with a diameter of approximately 250 ?m were prepared by the electrospray method, using 1 M LiCl/DMSO as a solvent. The dissolution time of SF in the CaCl2/CH3CH2OH/H2O solution and the concentration of the SF dope solution affected the final morphology of the microparticles. A long dissolution time and a low SF concentration led to the formation of irregular microparticles, but a short dissolution time and a high concentration produced sphere-like microparticles. The shear viscosity of the SF dope solution was the main parameter that affected the morphology of the SF microparticles. Regardless of the dissolution time in the CaCl2/CH3CH2OH/H2O solution and the concentration of the SF dope solution, the shear viscosity of the dope solution must be higher than 0.33 Pa s to produce sphere-like microparticles. Finally, cell adhesion experiments demonstrated that these SF microparticles show potential for use as cell carriers. PMID:26027609

  9. Flexible organic light emitting diodes fabricated on biocompatible silk fibroin substrate

    Science.gov (United States)

    Liu, Yuqiang; Xie, Yuemin; Liu, Yuan; Song, Tao; Zhang, Ke-Qin; Liao, Liangsheng; Sun, Baoquan

    2015-10-01

    Flexible and biodegradable electronics are currently under extensive investigation for biocompatible and environmentally-friendly applications. Synthetic plastic foils are widely used as substrates for flexible electronics. But typical plastic substrates such as polyethylene naphthalate (PEN) could not be degraded in a natural bio-environment. A great demand still exists for a next-generation biocompatible and biodegradable substrate for future application. For example, electronic devices can be potentially integrated into the human body. In this work, we demonstrate that the biocompatible and biodegradable natural silk fibroin (SF) films embedded with silver nanowires (AgNWs) mesh could be employed as conductive transparent substrates to fabricate flexible organic light emitting diodes (OLEDs). Compared with commercial PEN substrates coated with indium tin oxide, the AgNWs/SF composite substrates exhibit a similar sheet resistance of 12 ? sq-1, a lower surface roughness, as well as a broader light transmission range. Flexible OLEDs based on AgNWs/SF substrates achieve a current efficiency of 19 cd A-1, demonstrating the potential of the flexible AgNWs/SF films as conductive and transparent substrates for next-generation biodegradable devices.

  10. 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.

  11. Osteoinductive silk fibroin/titanium dioxide/hydroxyapatite hybrid scaffold for bone tissue engineering.

    Science.gov (United States)

    Kim, Jung-Ho; Kim, Dong-Kyu; Lee, Ok Joo; Ju, Hyung Woo; Lee, Jung Min; Moon, Bo Mi; Park, Hyun Jung; Kim, Dong Wook; Lee, Jun Ho; Park, Chan Hum

    2016-01-01

    The present study demonstrated the fabrication that incorporation of titanium isopropoxide (TiO2) and hydroxyapatite (HA) nanoparticles into the silk fibroin (SF) scaffolds. In this process, we prepared TiO2 nanoparticles using sol-gel synthesis and the porous structure was developed by salt-leaching process. Homogeneous distribution of TiO2 and HA nanoparticles were confirmed by images of VP-FE-SEM and those equipped with energy dispersive X-ray spectrometer. Structural characteristics of the porous SF/TiO2/HA hybrid scaffold were also determined using FTIR analysis and X-ray diffractometer. In this study, the porous SF/TiO2/HA hybrid scaffold showed similar porosity, enhanced mechanical property, but decreased water binding abilities, compared with the porous SF scaffold. For evaluation of the osteogenic differentiation of rat bone marrow mesenchymal stem cells, alkaline phosphatase activity and osteogenic gene expression were employed. Our results revealed that the porous SF/TiO2/HA hybrid scaffold had improved osteoinductivity compared with the porous SF scaffold. These results suggest that the osteogenic property as well as mechanical property of the porous SF/TiO2/HA hybrid scaffold could be better than the porous SF scaffold. Therefore, the porous SF/TiO2/HA hybrid scaffold may be a good promising biomaterial for bone tissue engineering application. PMID:26257379

  12. Membrane-reinforced three-dimensional electrospun silk fibroin scaffolds for bone tissue engineering.

    Science.gov (United States)

    Yang, Sung Yeun; Hwang, Tae Heon; Che, Lihua; Oh, Jin Soo; Ha, Yoon; Ryu, WonHyoung

    2015-06-01

    Electrospun silk fibroin (SF) scaffolds have drawn much attention because of their resemblance to natural tissue architecture such as extracellular matrix, and the biocompatibility of SF as a candidate material to replace collagen. However, electrospun scaffolds lack the physical integrity of bone tissue scaffolds, which require resistance to mechanical loadings. In this work, we propose membrane-reinforced electrospun SF scaffolds by a serial process of electrospinning and freeze-drying of SF solutions in two different solvents: formic acid and water, respectively. After wet electrospinning followed by replacement of methanol with water, SF nanofibers dispersed in water were mixed with aqueous SF solution. Freeze-drying of the mixed solution resulted in 3D membrane-connected SF nanofibrous scaffolds (SF scaffolds) with a thickness of a few centimeters. We demonstrated that the SF concentration of aqueous SF solution controlled the degree of membrane reinforcement between nanofibers. It was also shown that both increase in degree of membrane reinforcement and inclusion of hydroxyapatite (HAP) nanoparticles resulted in higher resistance to compressive loadings of the SF scaffolds. Culture of human osteoblasts on collagen, SF, and SF-HAP scaffolds showed that both SF and SF-HAP scaffolds had biocompatibility and cell proliferation superior to that of the collagen scaffolds. SF-HAP scaffolds with and without BMP-2 were used for in vivo studies for 4 and 8?weeks, and they showed enhanced bone tissue formation in rat calvarial defect models. PMID:26106926

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

    Science.gov (United States)

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

    2014-12-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Xiu-Mei Mo

    2011-03-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Chih-Hao Chen

    2014-03-01

    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.

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

    Directory of Open Access Journals (Sweden)

    2010-05-01

    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.

  17. 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 characteristic functionality of hepatocytes growing on RSF–GalCS scaffold in relation to RSF and GalCS scaffolds, and to test its behavior in vivo. (paper)

  18. 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)

    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

    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)

  19. Impact of silk fibroin-based scaffold structures on human osteoblast MG63 cell attachment and proliferation

    Directory of Open Access Journals (Sweden)

    Varkey A

    2015-10-01

    Full Text Available Aneesia Varkey,1,2 Elakkiya Venugopal,2 Ponjanani Sugumaran,2 Gopinathan Janarthanan,1 Mamatha M Pillai,2 Selvakumar Rajendran,2 Amitava Bhattacharyya1 1Advanced Textile and Polymer Research Laboratory, 2Tissue Engineering Laboratory, PSG Institute of Advanced Studies, Coimbatore, Tamil Nadu, India Abstract: The present study was carried out to investigate the impact of various types of silk fibroin (SF scaffolds on human osteoblast-like cell (MG63 attachment and proliferation. SF was isolated from Bombyx mori silk worm cocoons after degumming. Protein concentration in the degummed SF solution was estimated using Bradford method. Aqueous SF solution was used to fabricate three different types of scaffolds, viz, electrospun nanofiber mat, sponge, and porous film. The structures of the prepared scaffolds were characterized using optical micro­scopy and field emission scanning electron microscopy. The changes in the secondary structure of the proteins and the thermal behavior of the scaffolds were determined by Fourier transform infrared spectroscopy and thermo-gravimetric analysis, respectively. The biodegradation rate of scaffolds was determined by incubating the scaffolds in simulated body fluid for 4 weeks. MG63 cells were seeded on the scaffolds and their attachment and proliferation onto the scaffolds were studied. The MTT assay was carried out to deduce the toxicity of the developed scaffolds. All the scaffolds were found to be biocompatible. The amount of collagen produced by the osteoblast-like cells growing on different scaffolds was estimated. Keywords: silk fibroin scaffold, electrospun nanofiber, porous film, sponge, osteoblast

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

    OpenAIRE

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

    2013-01-01

    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 propert...

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

    Science.gov (United States)

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

    2015-07-01

    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 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. PMID:25176408

  2. Preparation and characterization of genipin-cross-linked silk fibroin/chitosan sustained-release microspheres

    Directory of Open Access Journals (Sweden)

    Zeng SG

    2015-05-01

    Full Text Available Shuguang Zeng,1,* Manwen Ye,1,2,* Junqi Qiu,1 Wei Fang,1 Mingdeng Rong,1 Zehong Guo,1 Wenfen Gao11Department of Oral and Maxillofacial Surgery, Guangdong Provincial Stomatological Hospital, Southern Medical University, 2Department of Stomatology, Guangdong Women and Children Hospital, Guangzhou Medical University, Guangzhou, Guangdong, People’s Republic of China*These authors contributed equally to this workAbstract: We report the effects of distinct concentrations of genipin and silk fibroin (SF:chitosan (CS ratios on the formation of SF–CS composite microspheres. We selected microspheres featuring an SF:CS ratio of 1:1, encapsulated various concentrations of bovine serum albumin (BSA, and then compared their encapsulation efficiency and sustained-release rate with those of pure CS microspheres. We determined that the following five groups of microspheres were highly spherical and featured particle sizes ranging from 70 µm to 147 µm: mass ratio of CS:SF =1:0.5, 0.1 g or 0.5 g genipin; CS:SF =1:1, 0.05 g or 1 g genipin; and CS:SF =1:2, 0.5 g genipin. The microspheres prepared using 1:1 CS:SF ratio and 0.05 g genipin in the presence of 10 mg, 20 mg, and 50 mg of BSA exhibited encapsulation efficiencies of 50.16%±4.32%, 56.58%±3.58%, and 42.19%±7.47%, respectively. Fourier-transform infrared spectroscopy (FTIR results showed that SF and CS were cross-linked and that the ?-helices and random coils of SF were converted into ?-sheets. BSA did not chemically react with CS or SF. Moreover, thermal gravimetric analysis (TGA results showed that the melting point of BSA did not change, which confirmed the FTIR results, and X-ray diffraction results showed that BSA was entrapped in microspheres in a noncrystalline form, which further verified the TGA and FTIR data. The sustained-release microspheres prepared in the presence of 10 mg, 20 mg, and 50 mg of BSA burst release 30.79%±3.43%, 34.41%±4.46%, and 41.75%±0.96% of the entrapped BSA on the 1st day and cumulatively released 75.20%±2.52%, 79.16%±4.31%, and 89.04%±4.68% in 21 days, respectively. The pure CS microspheres prepared in the presence of 10 mg of BSA burst release 39.53%±1.76% of BSA on the 1st day and cumulatively released 83.57%±2.33% of the total encapsulated BSA in 21 days. The SF–CS composite microspheres exhibited higher sustained release than did the pure CS microspheres, and thus these composite microspheres might function as a superior drug carrier.Keywords: silk fibroin, chitosan, genipin, microspheres, controlled release

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

    Science.gov (United States)

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

    2014-03-01

    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 < 0.05 was considered to be statistically significant. Adherence and spreading of 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.

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

    Science.gov (United States)

    Kim, Hyun Ju; Um, In Chul

    2014-05-01

    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.

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

    Science.gov (United States)

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

    2012-03-01

    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.

  6. Treatment of Silk Fibroin with Poly(ethylene glycol for the Enhancement of Corneal Epithelial Cell Growth

    Directory of Open Access Journals (Sweden)

    Shuko Suzuki

    2015-05-01

    Full Text Available A silk protein, fibroin, was isolated from the cocoons of the domesticated silkworm (Bombyx mori and cast into membranes to serve as freestanding templates for tissue-engineered corneal cell constructs to be used in ocular surface reconstruction. In this study, we sought to enhance the attachment and proliferation of corneal epithelial cells by increasing the permeability of the fibroin membranes and the topographic roughness of their surface. By mixing the fibroin solution with poly(ethylene glycol (PEG of molecular weight 300 Da, membranes were produced with increased permeability and with topographic patterns generated on their surface. In order to enhance their mechanical stability, some PEG-treated membranes were also crosslinked with genipin. The resulting membranes were thoroughly characterized and compared to the non-treated membranes. The PEG-treated membranes were similar in tensile strength to the non-treated ones, but their elastic modulus was higher and elongation lower, indicating enhanced rigidity. The crosslinking with genipin did not induce a significant improvement in mechanical properties. In cultures of a human-derived corneal epithelial cell line (HCE-T, the PEG treatment of the substratum did not improve the attachment of cells and it enhanced only slightly the cell proliferation in the longer term. Likewise, primary cultures of human limbal epithelial cells grew equally well on both non-treated and PEG-treated membranes, and the stratification of cultures was consistently improved in the presence of an underlying culture of irradiated 3T3 feeder cells, irrespectively of PEG-treatment. Nevertheless, the cultures grown on the PEG-treated membranes in the presence of feeder cells did display a higher nuclear-to-cytoplasmic ratio suggesting a more proliferative phenotype. We concluded that while the treatment with PEG had a significant effect on some structural properties of the B. mori silk fibroin (BMSF membranes, there were minimal gains in the performance of these materials as a substratum for corneal epithelial cell growth. The reduced mechanical stability of freestanding PEG-treated membranes makes them a less viable choice than the non-treated membranes.

  7. Treatment of Silk Fibroin with Poly(ethylene glycol) for the Enhancement of Corneal Epithelial Cell Growth.

    Science.gov (United States)

    Suzuki, Shuko; Dawson, Rebecca A; Chirila, Traian V; Shadforth, Audra M A; Hogerheyde, Thomas A; Edwards, Grant A; Harkin, Damien G

    2015-01-01

    A silk protein, fibroin, was isolated from the cocoons of the domesticated silkworm (Bombyx mori) and cast into membranes to serve as freestanding templates for tissue-engineered corneal cell constructs to be used in ocular surface reconstruction. In this study, we sought to enhance the attachment and proliferation of corneal epithelial cells by increasing the permeability of the fibroin membranes and the topographic roughness of their surface. By mixing the fibroin solution with poly(ethylene glycol) (PEG) of molecular weight 300 Da, membranes were produced with increased permeability and with topographic patterns generated on their surface. In order to enhance their mechanical stability, some PEG-treated membranes were also crosslinked with genipin. The resulting membranes were thoroughly characterized and compared to the non-treated membranes. The PEG-treated membranes were similar in tensile strength to the non-treated ones, but their elastic modulus was higher and elongation lower, indicating enhanced rigidity. The crosslinking with genipin did not induce a significant improvement in mechanical properties. In cultures of a human-derived corneal epithelial cell line (HCE-T), the PEG treatment of the substratum did not improve the attachment of cells and it enhanced only slightly the cell proliferation in the longer term. Likewise, primary cultures of human limbal epithelial cells grew equally well on both non-treated and PEG-treated membranes, and the stratification of cultures was consistently improved in the presence of an underlying culture of irradiated 3T3 feeder cells, irrespectively of PEG-treatment. Nevertheless, the cultures grown on the PEG-treated membranes in the presence of feeder cells did display a higher nuclear-to-cytoplasmic ratio suggesting a more proliferative phenotype. We concluded that while the treatment with PEG had a significant effect on some structural properties of the B. mori silk fibroin (BMSF) membranes, there were minimal gains in the performance of these materials as a substratum for corneal epithelial cell growth. The reduced mechanical stability of freestanding PEG-treated membranes makes them a less viable choice than the non-treated membranes. PMID:26034883

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

    Science.gov (United States)

    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

    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

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

    International Nuclear Information System (INIS)

    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

  10. Semi-interpenetrating polymer networks composed of silk fibroin and poly(ethylene glycol) for wound dressing

    Energy Technology Data Exchange (ETDEWEB)

    Kweon, HaeYong; Yeo, Joo-hong; Lee, Kwang-gill [Applied Sericulture and Apiculture Division, National Institute of Agricultural Science and Technology, Suwon 441100 (Korea, Republic of); Lee, Hyun Chul; Na, Hee Sam [Department of Microbiology and Research Institute of Medical Sciences, Chonnam National University Medical School, Kwangju (Korea, Republic of); Won, Young Ho [Department of Dermatology, Chonnam National University Medical School, Kwangju (Korea, Republic of); Cho, Chong Su [School of Agricultural Biotechnology, Seoul National University, Seoul 151742 (Korea, Republic of)], E-mail: chocs@plaza.snu.ac.kr

    2008-09-01

    Semi-interpenetrating polymer networks (SIPNs) composed of silk fibroin (SF) and poly(ethylene glycol) (PEG) were prepared by photopolymerization of a PEG macromer in the presence of SF to improve the mechanical properties of SF sponge as wound dressing. The morphological structure of the SF/PEG SIPNs was observed to be composed of an interconnected microporous surface and a cross-sectional area. SF/PEG SIPNs showed non-cytotoxicity evaluated by a cell proliferation method using L929 fibroblasts. Wound contraction treated with SF/PEG SIPNs sponges was faster than that of Vaseline gauze as a control. Histological observation confirmed that the deposition of collagen in the dermis was organized by covering the wound area with SF/PEG SIPNs. The above results indicated that SF/PEG SIPNs could be used as wound dressing.

  11. Semi-interpenetrating polymer networks composed of silk fibroin and poly(ethylene glycol) for wound dressing

    International Nuclear Information System (INIS)

    Semi-interpenetrating polymer networks (SIPNs) composed of silk fibroin (SF) and poly(ethylene glycol) (PEG) were prepared by photopolymerization of a PEG macromer in the presence of SF to improve the mechanical properties of SF sponge as wound dressing. The morphological structure of the SF/PEG SIPNs was observed to be composed of an interconnected microporous surface and a cross-sectional area. SF/PEG SIPNs showed non-cytotoxicity evaluated by a cell proliferation method using L929 fibroblasts. Wound contraction treated with SF/PEG SIPNs sponges was faster than that of Vaseline gauze as a control. Histological observation confirmed that the deposition of collagen in the dermis was organized by covering the wound area with SF/PEG SIPNs. The above results indicated that SF/PEG SIPNs could be used as wound dressing

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

    International Nuclear Information System (INIS)

    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

  13. Composite biocompatible hydroxyapatite-silk fibroin coatings for medical implants obtained by Matrix Assisted Pulsed Laser Evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Miroiu, F.M., E-mail: marimona.miroiu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Socol, G.; Visan, A.; Stefan, N.; Craciun, D.; Craciun, V.; Dorcioman, G.; Mihailescu, I.N. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Sima, L.E.; Petrescu, S.M. [Institute of Biochemistry, Romanian Academy, 296 Splaiul Independentei, 060031 Bucharest (Romania); Andronie, A.; Stamatin, I. [3Nano-SAE Alternative Energy Sources-University of Bucharest, Faculty of Physics, 409 Atomistilor Street, RO-77125, Magurele-Ilfov (Romania); Moga, S.; Ducu, C. [University of Pitesti, Targul din Vale Str, no. 1, 110040 Pitesti (Romania)

    2010-05-25

    The aim of this study was to obtain biomimetic inorganic-organic thin films as coatings for metallic medical implants. These contain hydroxyapatite, the inorganic component of the bony tissues, and a natural biopolymer - silk fibroin - added in view to induce the surface functionalization. Hydroxyapatite (HA), silk fibroin (FIB) and composite HA-FIB films were obtained by Matrix Assisted Pulsed Laser Evaporation (MAPLE) in order to compare their physical and biological performances as coatings on metallic prostheses. We used an excimer laser source (KrF*, {lambda} = 248 nm, {tau} = 25 ns) operated at 10 Hz repetition rate. Coatings were deposited on quartz, Si and Ti substrates and then subjected to physical (FTIR, XRD, AFM, SEM) analyses, correlated with the results of the cytocompatibility in vitro tests. The hybrid films were synthesized from frozen targets of aqueous suspensions with 3:2 or 3:4 weight ratio of HA:FIB. An appropriate stoichiometric and functional transfer was obtained for 0.4-0.5 J/cm{sup 2} laser fluence. FTIR spectra of FIB and HA-FIB films exhibited distinctive absorption maxima, in specific positions of FIB random coil form: 1540 cm{sup -1} amide II, 1654 cm{sup -1} amide I, 1243 cm{sup -1} amide III, while the peak from 1027 cm{sup -1} appeared only for HA and composite films. Osteosarcoma SaOs2 cells cultured 72 h on FIB and HA-FIB films showed increased viability, good spreading and normal cell morphology. The well-elongated, flattened cells are a sign of an appropriate interaction with the MAPLE FIB and composite HA-FIB coatings.

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

    Directory of Open Access Journals (Sweden)

    Kim BS

    2015-01-01

    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

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

    OpenAIRE

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

    2010-01-01

    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 ...

  16. Bio-hybrid silk fibroin/calcium phosphate/PLGA nanocomposite scaffold to control the delivery of vascular endothelial growth factor

    International Nuclear Information System (INIS)

    This study investigated the efficacy of bio-hybrid silk fibroin/Calcium phosphate/PLGA nanocomposite scaffold as vascular endothelial growth factor (VEGF) delivery system. The scaffold was fabricated using freeze-drying and electrospinning. Here, we highlight the structural changes of the scaffold using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and differential scanning calorimetry (DSC). The uniform dispersion of calcium phosohate (CaP) powder within silk fibroin (SF) solution was also confirmed using Zeta potential analysis. Moreover, good biocompatibility of osteoblast cells next to the scaffold was approved by cell adhesion, proliferation and alkaline phosphatase production. The release profile of VEGF during 28 days has established the efficacy of the scaffold as a sustained delivery system. The bioactivity of the released VEGF was maintained about 83%. The histology analysis has shown that the new bone tissue formation happened in the defected site after 10 weeks of implantation. Generally, our data showed that the fabricated scaffold could be considered as an effective scaffold for bone tissue engineering applications. - Highlights: • Silk fibroin/calcium phosphate/PLGA scaffold was successfully fabricated using freeze-drying and electrospinning. • The scaffold could control the release of VEGF during 28 days. • The bioactivity of electrospun VEGF was above 80%. • VEGF loaded scaffold could induce bone regeneration after 10 weeks in rabbit

  17. Bio-hybrid silk fibroin/calcium phosphate/PLGA nanocomposite scaffold to control the delivery of vascular endothelial growth factor

    Energy Technology Data Exchange (ETDEWEB)

    Farokhi, Mehdi, E-mail: mehdi13294@yahoo.com [Department of Tissue Engineering, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Mottaghitalab, Fatemeh, E-mail: fatemeh.motaghi@gmail.com [Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University (TMU), Tehran (Iran, Islamic Republic of); Shokrgozar, Mohammad Ali, E-mail: mashokrgozar@pasteur.ac.ir [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran (Iran, Islamic Republic of); Ai, Jafar, E-mail: jafar_ai@tums.ac.ir [Department of Tissue Engineering, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Hadjati, Jamshid; Azami, Mahmoud [Department of Tissue Engineering, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2014-02-01

    This study investigated the efficacy of bio-hybrid silk fibroin/Calcium phosphate/PLGA nanocomposite scaffold as vascular endothelial growth factor (VEGF) delivery system. The scaffold was fabricated using freeze-drying and electrospinning. Here, we highlight the structural changes of the scaffold using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and differential scanning calorimetry (DSC). The uniform dispersion of calcium phosohate (CaP) powder within silk fibroin (SF) solution was also confirmed using Zeta potential analysis. Moreover, good biocompatibility of osteoblast cells next to the scaffold was approved by cell adhesion, proliferation and alkaline phosphatase production. The release profile of VEGF during 28 days has established the efficacy of the scaffold as a sustained delivery system. The bioactivity of the released VEGF was maintained about 83%. The histology analysis has shown that the new bone tissue formation happened in the defected site after 10 weeks of implantation. Generally, our data showed that the fabricated scaffold could be considered as an effective scaffold for bone tissue engineering applications. - Highlights: • Silk fibroin/calcium phosphate/PLGA scaffold was successfully fabricated using freeze-drying and electrospinning. • The scaffold could control the release of VEGF during 28 days. • The bioactivity of electrospun VEGF was above 80%. • VEGF loaded scaffold could induce bone regeneration after 10 weeks in rabbit.

  18. Surface modification of silk fibroin fibers with poly(methyl methacrylate) and poly(tributylsilyl methacrylate) via RAFT polymerization for marine antifouling applications.

    Science.gov (United States)

    Buga, Mihaela-Ramona; Zaharia, C?t?lin; B?lan, Mihai; Bressy, Christine; Ziarelli, Fabio; Margaillan, André

    2015-06-01

    In this study, silk fibroin surface containing hydroxyl and aminogroups was firstly modified using a polymerizable coupling agent 3-(trimethoxysilyl) propyl methacrylate (MPS), in order to induce vinyl groups onto the fiber surface. The reversible addition-fragmentation chain transfer (RAFT)-mediated polymerization of methyl methacrylate (MMA) and tributylsilyl methacrylate (TBSiMA) through the immobilized vinyl bond on the silk fibroin surface in the presence of 2-cyanoprop-2-yl dithiobenzoate (CPDB) as chain-transfer agent and 2,2'-azobis(isobutyronitrile) (AIBN) as initiator was conducted in toluene solution at 70°C for 24h. The structure and properties of the modified fiber were characterized by Fourier Transform Infrared Spectroscopy, (13)C, (29)Si Nuclear Magnetic Resonance (NMR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), confirming the presence of the coupling molecule and the methacrylate groups onto the silk fibroin fiber surface. Molecular weight distributions were assessed by triple detection size exclusion chromatography (TD-SEC) in order to verify the livingness of the polymerization. PMID:25842130

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

    Indian Academy of Sciences (India)

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

    2003-12-01

    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.

  20. Biodegradation of Silk Biomaterials

    OpenAIRE

    Bochu Wang; Yang Cao

    2009-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang Song; Gao Zhen; Chen Xiaomeng; Lian Xiaojie; Zhu Hesun [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Zheng Jun; Sun Lizhong [Department of Cardiac Surgery, Cardiovascular Institute and Fu Wai Hospital, CAMS and PUMC, Beijing 100037 (China)], E-mail: wangsongbit@hotmail.com

    2008-12-15

    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 {beta}-sheet conformation is not disturbed.

  2. 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.

  3. Rapid and repeatable fabrication of high A/R silk fibroin microneedles using thermally-drawn micromolds.

    Science.gov (United States)

    Lee, JiYong; Park, Seung Hyun; Seo, Il Ho; Lee, Kang Ju; Ryu, WonHyoung

    2015-08-01

    Thermal drawing is a versatile rapid prototyping method that can freely form microneedle (MN) structures with ultra-high aspect ratio without relying on any complex and expensive process. However, it is still challenging to repeatedly produce MNs with identical shapes using this thermal drawing due to small fluctuations in processing conditions such as temperatures, drawing speeds, drawing heights, or parallelism in the drawing setup. In addition, thermal drawing is only applicable to thermoplastic materials and most natural biomaterials are incompatible with this method. Thus, we propose use of thermal drawing to fabricate master molds with high aspect ratios and replicate the shape by micromolding. In this work, high A/R MNs with various body profiles were fabricated by thermal drawing and replicated to silk fibroin (SF) MNs multiple times using micromolding. The original MN shape was precisely copied to the SF MNs. Methanol treatment enhanced the mechanical strength of SF MNs up to about 113% more depending on the treatment duration. We also demonstrated that methanol exposure time could effectively control drug release rates from SF MNs. PMID:25936857

  4. Fabrication and characterization of layered chitosan/silk fibroin/nano-hydroxyapatite scaffolds with designed composition and mechanical properties.

    Science.gov (United States)

    Zhou, Ting; Wu, Jingjing; Liu, Jiaoyan; Luo, Ying; Wan, Ying

    2015-08-01

    Chitosan/nano-hydroxyapatite (HA) composites were first prepared and then used together with chitosan and silk fibroin (SF) to produce a type of four-layer porous scaffold that is potentially applicable for articular cartilage repair. The bottom layer of the scaffold was built with the chitosan/HA composite and the other three layers of the scaffold were fabricated using chitosan/SF composites in which the content of the chitosan and SF was altered in a mutually reversed trend. The so-produced chitosan/SF/HA scaffolds were further crosslinked using tripolyphosphate to achieve enhanced mechanical properties. Interconnected porous microstructures throughout the scaffolds were constructed using a temperature gradient processing technique, and the resultant scaffolds were endowed with graded pore-sizes and porosities as well as porous interface zones between contiguous layers without visual clefts. The compressive modulus and stress at 10% strain of the scaffolds in wet state showed a gradient-changed trend which partially mimics the compressive mechanical properties of an articular cartilage matrix. Cell culture on some chitosan/SF/HA scaffolds for a period of time of up to 14?d showed that the scaffolds were able to well support the growth and infiltration of cells, suggesting that the presently developed chitosan/SF/HA scaffolds have promising potential for articular cartilage repair. PMID:26225911

  5. Silk fibroin/gelatin-chondroitin sulfate-hyaluronic acid effectively enhances in vitro chondrogenesis of bone marrow mesenchymal stem cells.

    Science.gov (United States)

    Sawatjui, Nopporn; Damrongrungruang, Teerasak; Leeanansaksiri, Wilairat; Jearanaikoon, Patcharee; Hongeng, Suradej; Limpaiboon, Temduang

    2015-07-01

    Tissue engineering is becoming promising for cartilage repair due to the limited self-repair capacity of cartilage tissue. We previously fabricated and characterized a three-dimensional silk fibroin/gelatin-chondroitin sulfate-hyaluronic acid (SF-GCH) scaffold and showed that it could promote proliferation of human bone marrow mesenchymal stem cells (BM-MSCs). This study aimed to evaluate its biological performance as a new biomimetic material for chondrogenic induction of BM-MSCs in comparison to an SF scaffold and conventional pellet culture. We found that the SF-GCH scaffold significantly enhanced the proliferation and chondrogenic differentiation of BM-MSCs compared to the SF scaffold and pellet culture in which the production of sulfated glycoaminoglycan was increased in concordance with the up-regulation of chondrogenic-specific gene markers. Our findings indicate the significant role of SF-GCH by providing a supportive structure and the mimetic cartilage environment for chondrogenesis which enables cartilage regeneration. Thus, our fabricated SF-GCH scaffold may serve as a potential biomimetic material for cartilage tissue engineering. PMID:25953544

  6. Electrospun and woven silk fibroin/poly(lactic-co-glycolic acid) nerve guidance conduits for repairing peripheral nerve injury

    Science.gov (United States)

    Wang, Ya-ling; Gu, Xiao-mei; Kong, Yan; Feng, Qi-lin; Yang, Yu-min

    2015-01-01

    We have designed a novel nerve guidance conduit (NGC) made from silk fibroin and poly(lactic-co-glycolic acid) through electrospinning and weaving (ESP-NGCs). Several physical and biological properties of the ESP-NGCs were assessed in order to evaluate their biocompatibility. The physical properties, including thickness, tensile stiffness, infrared spectroscopy, porosity, and water absorption were determined in vitro. To assess the biological properties, Schwann cells were cultured in ESP-NGC extracts and were assessed by morphological observation, the MTT assay, and immunohistochemistry. In addition, ESP-NGCs were subcutaneously implanted in the backs of rabbits to evaluate their biocompatibility in vivo. The results showed that ESP-NGCs have high porosity, strong hydrophilicity, and strong tensile stiffness. Schwann cells cultured in the ESP-NGC extract fluids showed no significant differences compared to control cells in their morphology or viability. Histological evaluation of the ESP-NGCs implanted in vivo indicated a mild inflammatory reaction and high biocompatibility. Together, these data suggest that these novel ESP-NGCs are biocompatible, and may thus provide a reliable scaffold for peripheral nerve repair in clinical application.

  7. Function of a TGF-beta inducible nuclear protein in the silk gland in Bombyx mori.

    Science.gov (United States)

    Wang, J-L; Zhang, Y-P; Gu, Y-Y; Wang, J-X; Zhao, X-F

    2009-04-01

    A TGF-beta inducible nuclear protein 1 (BmTINP1) was cloned from silkworm, Bombyx mori. Polyclonal antibodies against BmTINP1 were produced and subsequently used in immunoblotting and immunohistochemistry analyses. The immunoblotting analyses demonstrated that BmTINP1 was specifically expressed in the anterior silk gland (ASG) and the middle silk gland (MSG) but not in the posterior silk gland (PSG). There were two bands that suggested the existence of an isoform of BmTINP1. The expression profiles of BmTINP1 in ASGs and MSGs were similar, and they manifested a high level of expression throughout the period during which silk gland grew exponentially. Immunohistochemistry results revealed that BmTINP1 was translocated from the nucleus into the cytoplasm when larvae developed from the 4th-HCS into the 5th instar. 20-hydroxyecdysone (20E) promotes the translocation, while the methoprene [a juvenile hormone (JH) analog] restrains the process. Our findings indicate that BmTINP1 is involved in silk produce along with the rapid growth of ASGs and MSGs during the last instar larvae, and the process could be regulated by hormones via control of BmTINP1 translocation from the nucleus to the cytoplasm. PMID:19220509

  8. An ectopic study of apatite-coated silk fibroin scaffolds seeded with AdBMP-2 modified canine bMSCs

    OpenAIRE

    Lü, Kaige; Xu, Ling; Xia, Lunguo; Zhang, Yilin; ZHANG, XIULI; Kaplan, David L.; Jiang, Xinquan; Zhang, Fuqiang

    2011-01-01

    The present study was undertaken to evaluate ectopic new bone formation effects of apatite-coated silk fibroin scaffolds (mSS) seeded with adenovirus mediated bone morphogenic protein-2 gene (AdBMP-2) transduced canine bone marrow stromal cells (bMSCs) in nude mice. In this study, bMSCs derived from canine were cultured and transduced with AdBMP-2, adenovirus mediated enhanced green fluorescent protein gene (AdEGFP) in vitro. Osteogenic differentiation of bMSCs was determined by alkaline phos...

  9. ToF-SIMS Characterization of Silk Fibroin and Polypyrrole Composite Actuators

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, Nathan P.; Severt, Sean Y.; Wang, Zhaoying; Fengel, Carly V.; Larson, Jesse D.; Zhu, Zihua; Murphy, Amanda; Leger, Janelle M.

    2015-08-31

    Biocompatible materials capable of controlled actuation under biologically relevant conditions are in high demand for use in a number of biomedical applications. Recently, we demonstrated that a composite material composed of silk biopolymer and the conducting polymer poly(pyrrole) can bend under an applied voltage using a simple bilayer device. Here we present further characterization of these bilayer actuators using time of flight secondary ion mass spectrometry, and provide clarification on the mechanism of actuation and factors affecting device performance and stability. We will discuss the results of this study in the context of strategies for optimization of device performance.

  10. Mechanical properties and permeability of porous chitosan-poly(p-dioxanone)/silk fibroin conduits used for peripheral nerve repair.

    Science.gov (United States)

    Wu, Hua; Zhang, Jun; Luo, Ying; Wan, Ying; Sun, Shaofa

    2015-10-01

    Some poly(p-dioxanone) (PDO) homopolymers were first synthesized and the selected PDO was conjugated onto chitosan using a group-protecting method to produce chitosan-poly(p-dioxanone) (CH-PDO) copolymers with various PDO percentages changing from around 30 to 60wt%. The CH-PDO with the PDO content of around 42wt% was used to blend with prescribed amounts of silk fibroin (SF) to build porous single-lumen conduits that are intended to be used for long-gap peripheral nerve repair. Some genipin-crosslinked CH-PDO/SF conduits were endowed with an average porosity of around 60% in their porous wall, and with changed pore-sizes varying from around 10 to ca. 70?m using optimized processing conditions. After being degraded in a PBS medium containing a certain amount of lysozyme for various periods up to 8 weeks, some optimal CH-PDO/SF conduits were able to retain their compressive load and deformation recovery at around 59N/m and 73% in wet state, respectively. In addition, the achieved CH-PDO/SF conduits allowed the permeation of nutritional molecules with various molecular weights while showing a certain ability to prevent cells from infiltrating through the conduit wall. Cell culture confirmed that the optimized CH-PDO/SF conduits were able well supported the growth of rat glioma C6 cells. These results suggest that presently developed CH-PDO/SF conduits have promising potential for long-gap peripheral nerve repair. PMID:26143352

  11. Silk fibroin/gelatin electrospun nanofibrous dressing functionalized with astragaloside IV induces healing and anti-scar effects on burn wound.

    Science.gov (United States)

    Shan, Ying-Hui; Peng, Li-Hua; Liu, Xin; Chen, Xi; Xiong, Jie; Gao, Jian-Qing

    2015-02-20

    Functional wound dressing has provided new challenges for researchers who focus on burn to improve skin graft quality, reduce scarring, and develop a pluristratified dermal or epidermal construct of a burn wound. This study aimed to investigate the effect of a silk fibroin/gelatin (SF/GT) electrospun nanofibrous dressing loaded with astragaloside IV (AS) on deep partial-thickness burn wound. AS-loaded SF/GT-blended nanofibrous dressing was prepared by electrospinning nanotechnology. The optimal ratio (25:75) of silk fibroin to gelatin was further optimized by evaluating ATR-FTIR characteristics, mechanical properties, porosity, swelling rate, degradation, and release profile of the AS-loaded SF/GT nanofibrous dressing. In contrast to the blank control, the AS-loaded SF/GT nanofibrous dressing promoted cell adhesion and proliferation with good biocompatibility in vitro (p<0.01). This dressing also accelerated wound healing and inhibited scar formation in vivo by stimulating wound closure (p<0.05), increasing angiogenesis, regulating newly formed types of collagen, and improving collagen organization. These results showed that SF/GT nanofibrous dressing is a promising topical drug delivery system. Furthermore, AS-functionalized SF/GT nanofibrous dressing is an excellent topical therapeutic that could be applied to promote healing and elicit anti-scar effects on partial-thickness burn wound. PMID:25556053

  12. 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 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)

  13. The expression patterns of a eukaryotic initiation factor 3 subunit H in the silk glands in Bombyx mori.

    Science.gov (United States)

    Wang, Jia-Lin; Wang, Li-Fu; Wang, Jin-Xing; Zhao, Xiao-Fan

    2010-09-01

    Eukaryotic initiation factor 3 subunit H has been characterized in many organisms, and it has been found to play many roles including help regulate translation initiation. In this work, we studied the tissue distribution and expression profiles of Bombyx mori (B. mori) eIF3 subunit H (BmeIF3h). BmeIF3h was prominently expressed in silk glands, with anterior silk glands (ASGs), middle silk glands (MSGs), and posterior silk glands (PSGs) all expressing BmeIF3h. The expression levels of BmeIF3h in MSGs and PSGs were higher than that in ASGs during 0 d and 2 d of the 5th instar larvae. The expression levels of BmeIF3h in MSGs and PSGs were up-regulated once the silk glands began to synthesize silk protein during the feeding stage of the 4th instar larvae. Immunohistochemistry showed that BmeIF3h was distributed in the cytoplasm of MSGs cells and in both the nucleus and the cytoplasm of PSGs cells. These data suggest that BmeIF3h had different action behaviors in the MSGs and PSGs related to the production of the silk glue proteins and silk fibre proteins, respectively. PMID:20734419

  14. Characterization of Tetracycline-loaded Thai Silk Fibroin/Gelatin Blend Films

    Directory of Open Access Journals (Sweden)

    Srihanam Prasong

    2010-01-01

    Full Text Available This study was aimed to prepare SF/G blend films loaded tetracycline by a solvent evaporation method. Firstly silk cocoons were degummed and then dissolved by CaCl2:Ethanol:H2O (1:2:8 by mole. On another way, Gelatin (G was prepared from gelatin powder. The mixture solution of SF/G ratios with 3:0, 2:1, 1:1, 1:2 and 0:3 were prepared before casting on the 5 cm polystyrene plates. All of films were investigated their morphology, chemical structures, thermal properties and percent transparency by using Scanning Electron Microscope (SEM, Fourier transform infrared (FTIR spectroscopy, Thermogravimetric Analyzer (TA and UV-Vis spectrometer, respectively. The results found that the surfaces of blend films were gradually smooth without phase separation when the SF component decreased. The FTIR results of SF/G films showed strong regions for amide I, amide II and amide III which were the mixture characteristics of SF and G. The blend films rapidly decomposed in maximum rate after 300°C. The rate of weight lost depending on the content G meanwhile rapidly increased of weight lost when the G content was increased. The heat flow curves indicated that the blend films composed of multiple peaks of maximum decomposition temperatures as well as endo/exo-thermic. Finally, tetracycline could be interacted with G in excellent profile affected to the lowest of percent transparency.

  15. Acellular bi-layer silk fibroin scaffolds support functional tissue regeneration in a rat model of onlay esophagoplasty.

    Science.gov (United States)

    Algarrahi, Khalid; Franck, Debra; Ghezzi, Chiara E; Cristofaro, Vivian; Yang, Xuehui; Sullivan, Maryrose P; Chung, Yeun Goo; Affas, Saif; Jennings, Russell; Kaplan, David L; Estrada, Carlos R; Mauney, Joshua R

    2015-06-01

    Surgical management of long-gap esophageal defects with autologous gastrointestinal tissues is frequently associated with adverse complications including organ dysmotility, dysphagia, and donor site morbidity. In order to develop alternative graft options, bi-layer silk fibroin (SF) scaffolds were investigated for their potential to support functional tissue regeneration in a rodent model of esophageal repair. Onlay esophagoplasty was performed with SF matrices (N = 40) in adult rats for up to 2 m of implantation. Parallel groups consisted of animals implanted with small intestinal submucosa (SIS) scaffolds (N = 22) or sham controls receiving esophagotomy alone (N = 20). Sham controls exhibited a 100% survival rate while rats implanted with SF and SIS scaffolds displayed respective survival rates of 93% and 91% prior to scheduled euthanasia. Animals in each experimental group were capable of solid food consumption following a 3 d post-op liquid diet and demonstrated similar degrees of weight gain throughout the study period. End-point ?-computed tomography at 2 m post-op revealed no evidence of contrast extravasation, fistulas, strictures, or diverticula in any of the implant groups. Ex vivo tissue bath studies demonstrated that reconstructed esophageal conduits supported by both SF and SIS scaffolds displayed contractile responses to carbachol, KCl and electrical field stimulation while isoproterenol produced tissue relaxation. Histological (Masson's trichrome and hematoxylin and eosin) and immunohistochemical (IHC) evaluations demonstrated both implant groups produced de novo formation of skeletal and smooth muscle bundles positive for contractile protein expression [fast myosin heavy chain (MY32) and ?-smooth muscle actin (?-SMA)] within the graft site. However, SF matrices promoted a significant 4-fold increase in MY32+ skeletal muscle and a 2-fold gain in ?-SMA+ smooth muscle in comparison to the SIS cohort as determined by histomorphometric analyses. A stratified squamous, keratinized epithelium expressing cytokeratin 5 and involucrin proteins was also present at 2 m post-op in all experimental groups. De novo innervation and vascularization were evident in all regenerated tissues indicated by the presence of synaptophysin (SYP38)+ boutons and vessels lined with CD31 expressing endothelial cells. In respect to SIS, the SF group supported a significant 4-fold increase in the density of SYP38+ boutons within the implant region. Evaluation of host tissue responses revealed that SIS matrices elicited chronic inflammatory reactions and severe fibrosis throughout the neotissues, in contrast to SF scaffolds. The results of this study demonstrate that bi-layer SF scaffolds represent promising biomaterials for onlay esophagoplasty, capable of producing superior regenerative outcomes in comparison to conventional SIS scaffolds. PMID:25890715

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

    Science.gov (United States)

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

    2014-01-01

    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

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

    OpenAIRE

    Ma, SanYuan; Shi, Run; WANG, XIAOGANG; Liu, Yuanyuan; Chang, Jiasong; GAO, JIE; Lu, Wei; Zhang, Jianduo; Ping ZHAO; Xia, QingYou

    2014-01-01

    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 numerou...

  18. 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)

    Liang, Meini; Yao, Jinrong; Chen, Xin; Huang, Lei; Shao, Zhengzhong, E-mail: zzshao@fudan.edu.cn

    2013-04-01

    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.

  19. 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

  20. 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)

    Lozano-Pérez AA

    2014-09-01

    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

  1. Enhancement of osseointegration of polyethylene terephthalate artificial ligament by coating of silk fibroin and depositing of hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Jiang J

    2014-09-01

    Full Text Available Jia Jiang,1,2 Fang Wan,1 Jianjun Yang,1 Wei Hao,3 Yaxian Wang,3 Jinrong Yao,3 Zhengzhong Shao,3 Peng Zhang,1 Jun Chen,1 Liang Zhou,4 Shiyi Chen11Fudan University Sports Medicine Center and Department of Sports Medicine and Arthroscopy Surgery, Huashan Hospital, 2State Key Laboratory of Molecular Engineering of Polymers, 3Laboratory of Advanced Materials, National Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, People’s Republic of China; 4Department of Forest Products, Anhui Agricultural University, Hefei Anhui Province, People’s Republic of ChinaBackground: 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.Keywords: biomineralization, tendon–bone healing, ligament reconstruction

  2. Effect of mechanical deformation on the structure of regenerated Bombyx mori silk fibroin films as revealed using Raman and infrared spectroscopy.

    Science.gov (United States)

    Huot, Alexandrine; Lefèvre, Thierry; Rioux-Dubé, Jean-François; Paquet-Mercier, François; Nault, Anne-Philipe; Auger, Michèle; Pézolet, Michel

    2015-06-01

    To better understand the effect of mechanical stress during the spinning of silk, the protein orientation and conformation of Bombyx mori regenerated silk fibroin (RSF) films have been studied as a function of deformation in a static mode or in real time by tensile-Raman experiments and polarization modulation infrared linear dichroism (PM-IRLD), respectively. The data show that either for step-by-step or continuous stretching, elongation induces the progressive formation of ?-sheets that align along the drawing axis, in particular above a draw ratio of ~2. The formation of ?-sheets begins before their alignment during a continuous drawing. Unordered chains were, however, never found to be oriented, which explains the very low level of orientation of the amorphous phase of the natural fiber. Stress-perturbed unordered chains readily convert into ?-sheets, the strain-induced transformation following a two-state process. The final level of orientation and ?-sheet content are lower than those found in the native fiber, indicating that various parameters have to be optimized in order to implement a spinning process as efficient as the natural one. Finally, during the stress relaxation period in a step-by-step drawing, there is essentially no change of the content and orientation of the ?-sheets, suggesting that only unordered structures tend to reorganize. PMID:25954973

  3. Silk fibers and silk-producing organs of Harpactea rubicunda (C. L. Koch 1838) (Araneae, Dysderidae).

    Science.gov (United States)

    Hajer, Jaromír; Malý, Jan; Reháková, Dana

    2013-01-01

    Scanning electron microscopy and atomic force microscopy were used to study the silk spinning apparatus and silks of Harpactea rubicunda spiders. Three types of silk secretions that are produced by three kinds of silk spinning glands (ampullate, piriform, and pseudaciniform) and released through three types of spigots, were confirmed for both adult and juvenile spiders. Silk secretions for the construction of spider webs for shelter or retreat are produced by the pseudaciniform silk glands. Silk secretions that are released from spigots in the course of web construction are not processed by the legs during the subsequent process of hardening. Pairs of nanofibril bundles seemed to be part of the basic microarchitecture of the web silk fibers as revealed by AFM. These fiber bundles frequently not only overlap one another, but occasionally also interweave. This structural variability may strengthen the spider web. High-resolution AFM scans of individual nanofibrils show a distinctly segmented nanostructure. Each globular segment is ?30-40 nm long along the longitudinal axis of the fiber, and resembles a nanosegment of artificial fibroin described by Perez-Rigueiro et al. (2007). PMID:23034869

  4. 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)

    Lai GJ

    2015-01-01

    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

  5. Bone Tissue Engineering with Premineralized Silk Scaffolds

    OpenAIRE

    Kim, Hyeon Joo; Kim, Ung-Jin; Kim, Hyun Suk; Li, Chunmei; Wada, Masahisa; Leisk, Gary G.; Kaplan, David L.

    2008-01-01

    Silks fibroin biomaterials are being explored as novel protein-based systems for cell and tissue culture. In the present study, biomimetic growth of calcium phosphate on porous silk fibroin polymeric scaffolds was explored to generate organic/inorganic composites as scaffolds for bone tissue engineering. Aqueous-derived silk fibroin scaffolds were prepared with the addition of polyaspartic acid during processing, followed by the controlled deposition of calcium phosphate by exposure to CaCl2 ...

  6. Glucose oxidase prevents programmed cell death of the silkworm anterior silk gland through hydrogen peroxide production.

    Science.gov (United States)

    Matsui, Hiroto; Kakei, Motonori; Iwami, Masafumi; Sakurai, Sho

    2011-03-01

    During pupal metamorphosis, the anterior silk glands (ASGs) of the silkworm Bombyx mori degenerate through programmed cell death (PCD), which is triggered by 20-hydroxyecdysone (20E). 20E triggers the PCD of the ASGs of day 7 fifth instar (V7) larvae but not that of V5 larvae. When V7 ASGs were cocultured with V5 ASGs in the presence of 20E, neither culture of ASGs underwent PCD. The 20E-induced PCD of V7 ASGs was also inhibited when they were incubated in conditioned medium that was prepared by incubating V5 ASGs for 48 h, an indication that V5 ASGs released an inhibitor of 20E-induced PCD during incubation. The inhibitor was purified from conditioned medium and identified as glucose oxidase (GOD). GOD catalyzes the oxidation of glucose to gluconolactone, and generates hydrogen peroxide as a byproduct. We found that hydrogen peroxide is the molecule that directly inhibits the action of 20E and may act to protect the ASGs from early execution of PCD during the feeding stage. GOD was localized in the inner cavity of the gland, and was discharged to the outside of the ASGs with the silk thread at the onset of spinning. Thus, the spinning behavior, occurring at the beginning of the prepupal period, plays an important role in controlling the time at which ASGs undergo PCD in response to 20E. PMID:21205208

  7. Critical electrolyte concentration of silk gland chromatin of the sugarcane borer Diatraea saccharalis, induced using agrochemicals.

    Science.gov (United States)

    Santos, S A; Fermino, F; Moreira, B M T; Araujo, K F; Falco, J R P; Ruvolo-Takasusuki, M C C

    2014-01-01

    The sugarcane borer Diatraea saccharalis is widely known as the main pest of sugarcane crop, causing increased damage to the entire fields. Measures to control this pest involve the use of chemicals and biological control with Cotesia flavipes wasps. In this study, we evaluated the insecticides fipronil (Frontline; 0.0025%), malathion (Malatol Bio Carb; 0.4%), cipermetrina (Galgotrin; 10%), and neem oil (Natuneem; 100%) and the herbicide nicosulfuron (Sanson 40 SC; 100%) in the posterior region silk glands of 3rd- and 5th-instar D. saccharalis by studying the variation in the critical electrolyte concentration (CEC). Observations of 3rd-instar larvae indicated that malathion, cipermetrina, and neem oil induced increased chromatin condensation that may consequently disable genes. Tests with fipronil showed no alteration in chromatin condensation. With the use of nicosulfuron, there was chromatin and probable gene decompaction. In the 5th-instar larvae, the larval CEC values indicated that malathion and neem oil induced increased chromatin condensation. The CEC values for 5th-instar larvae using cipermetrina, fipronil, and nicosulfuron indicated chromatin unpacking. These observations led us to conclude that the quantity of the pesticide does not affect the mortality of these pests, can change the conformation of complexes of DNA, RNA, and protein from the posterior region of silk gland cells of D. saccharalis, activating or repressing the expression of genes related to the defense mechanism of the insect and contributing to the selection and survival of resistant individuals. PMID:25299111

  8. Porous nitrogen-doped carbon derived from silk fibroin protein encapsulating sulfur as a superior cathode material for high-performance lithium-sulfur batteries.

    Science.gov (United States)

    Zhang, Jiawei; Cai, Yurong; Zhong, Qiwei; Lai, Dongzhi; Yao, Juming

    2015-11-14

    The features of a carbon substrate are crucial for the electrochemical performance of lithium-sulfur (Li-S) batteries. Nitrogen doping of carbon materials is assumed to play an important role in sulfur immobilisation. In this study, natural silk fibroin protein is used as a precursor of nitrogen-rich carbon to fabricate a novel, porous, nitrogen-doped carbon material through facile carbonisation and activation. Porous carbon, with a reversible capacity of 815 mA h g(-1) at 0.2 C after 60 cycles, serves as the cathode material in Li-S batteries. Porous carbon retains a reversible capacity of 567 mA h g(-1), which corresponds to a capacity retention of 98% at 1 C after 200 cycles. The promising electrochemical performance of porous carbon is attributed to its mesoporous structure, high specific surface area and nitrogen doping into the carbon skeleton. This study provides a general strategy to synthesise nitrogen-doped carbons with a high specific surface area, which is crucial to improve the energy density and electrochemical performance of Li-S batteries. PMID:26456870

  9. Electron beam induced water-soluble silk fibroin nanoparticles as a natural antioxidant and reducing agent for a green synthesis of gold nanocolloid

    Science.gov (United States)

    Wongkrongsak, Soraya; Tangthong, Theeranan; Pasanphan, Wanvimol

    2016-01-01

    The research proposes a novel water-soluble silk fibroin nanoparticles (WSSF-NPs) created by electron beam irradiation. In this report, we demonstrate the effects of electron beam irradiation doses ranging from 1 to 30 kGy on the molecular weight (MW), nanostructure formation, antioxidant activity and reducing power of the WSSF-NPs. Electron beam-induced degradation of SF causing MW reduction from 250 to 37 kDa. Chemical characteristic functions of SF still remained after exposing to electron beam. The WSSF-NPs with the MW of 37 kDa exhibited spherical morphology with a nanoscaled size of 40 nm. Antioxidant activities and reducing powers were investigated using 2,2-diphenyl-1-picrylhryl free radical (DPPH•) scavenging activity and ferric reducing antioxidant power (FRAP) assays, respectively. The WSSF-NPs showed greater antioxidant activity and reducing power than non-irradiated SF. By increasing their antioxidant and reducing power efficiencies, WSSF-NPs potentially created gold nanocolloid. WSSF-NPs produced by electron beam irradiation would be a great merit for the uses as a natural antioxidant additive and a green reducing agent in biomedical, cosmetic and food applications.

  10. Composite scaffolds of nano-hydroxyapatite and silk fibroin enhance mesenchymal stem cell-based bone regeneration via the interleukin 1 alpha autocrine/paracrine signaling loop.

    Science.gov (United States)

    Liu, Hua; Xu, Guo Wei; Wang, Ya Fei; Zhao, Hong Shi; Xiong, Si; Wu, Yan; Heng, Boon Chin; An, Cheng Rui; Zhu, Gang Hua; Xie, Ding Hua

    2015-05-01

    Composite scaffolds of nano-hydroxyapatite (nHAp) and silk fibroin (SF) have been reported to promote bone regeneration mainly through signaling pathways associated with cell-biomaterial interaction. However, it is unclear whether soluble factors also play a role in osteoinduction with nHAp-SF. In this study, we confirmed the biocompatibility and superior osteoinductivity of nHAp-SF scaffolds versus SF scaffolds both in vitro and on a calvarial defect model in vivo. This was followed by further analysis with microarray assay. The cDNA microarray results identified 247 differentially expressed genes in bone marrow mesenchymal stem cells (BMSCs) cultured on SF-nHAp scaffolds versus SF scaffolds. The greatest disparity in gene expression levels were observed with Il1? and Ilr2. Real-time PCR assay validated the results. The addition of IL-1? into cultures of BMSCs with SF significantly increased both Bmp2 and Ilr2 expression. However, with BMSCs alone, the Il1r2 expression increased substantially, whereas Bmp2 expression exhibited a decrease rather than increase. These data suggested that nHAp may exert osteoinductive effects on BMSCs via the secretion of IL-1? in an autocrine/paracrine fashion, and IL-1? activity could be regulated through the synthesis of IL1R2 by BMSCs upon interaction with nHAp. These results complemented our understanding of the underlying mechanisms of biomaterial osteoinductivity. PMID:25725559

  11. In vitro evaluation of the biological performance of macro/micro-porous silk fibroin and silk-nano calcium phosphate scaffolds.

    Science.gov (United States)

    Yan, L-P; Oliveira, J M; Oliveira, A L; Reis, R L

    2015-05-01

    This study evaluates the biological performance of salt-leached macro/microporous silk scaffolds (S16) and silk-nano calcium phosphate scaffolds (SC16), both deriving from a 16 wt % aqueous SF solution. Enzymatic degradation results showed that the silk-based scaffolds presented desirable biostability, and the incorporation of calcium phosphate further improved the scaffolds' biostability. Human adipose tissue derived stromal cells (hASCs) were cultured onto the scaffolds in vitro. The Alamar blue assay and DNA content revealed that both scaffolds were non-cytotoxic and can support the viability and proliferation of the hASCs. Scanning electron microscopy observation demonstrated that the microporous structure was beneficial for the cell adhesion while the macroporous structure favored the cell migration and proliferation. The histological analysis displayed abundant extracellular matrix formed inside the scaffolds, leading to the significant increase of scaffolds' modulus. These results revealed that S16 and SC16 could be promising alternatives for cartilage and bone tissue engineering scaffolding applications, respectively. PMID:25164158

  12. Structural Origins of Silk Piezoelectricity

    OpenAIRE

    Yucel, Tuna; Cebe, Peggy; Kaplan, David L.

    2011-01-01

    Uniaxially oriented, piezoelectric silk films were prepared by a two-step method that involved: (1) air drying aqueous, regenerated silk fibroin solutions into films, and (2) drawing the silk films to a desired draw ratio. The utility of two different drawing techniques, zone drawing and water immersion drawing were investigated for processing the silk for piezoelectric studies. Silk films zone drawn to a ratio of ?= 2.7 displayed relatively high dynamic shear piezoelectric coefficients of d1...

  13. MicroRNA of the fifth-instar posterior silk gland of silkworm identified by Solexa sequencing

    Directory of Open Access Journals (Sweden)

    Jisheng Li

    2014-12-01

    Full Text Available No special studies have been focused on the microRNA (miRNA in the fifth-instar posterior silk gland of Bombyx mori. Here, using next-generation sequencing, we acquired 93.2 million processed reads from 10 small RNA libraries. In this paper, we tried to thoroughly describe how our dataset generated from deep sequencing which was recently published in BMC genomics. Results showed that our findings are largely enriched silkworm miRNA depository and may benefit us to reveal the miRNA functions in the process of silk production.

  14. 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)

    Woloszyk, Anna; Holsten Dircksen, Sabrina; Bostanci, Nagihan; Müller, Ralph; Hofmann, Sandra; Mitsiadis, Thimios A

    2014-01-01

    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

  15. Biomaterials Derived from Silk-Tropoelastin Protein Systems

    OpenAIRE

    Hu, Xiao; Wang, Xiuli; Rnjak, Jelena; Weiss, Anthony S; Kaplan, David L.

    2010-01-01

    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...

  16. Silk Nanospheres and Microspheres from Silk/PVA Blend Films for Drug Delivery

    OpenAIRE

    Wang, Xiaoqin; Yucel, Tuna; LU, QIANG; Hu, Xiao; Kaplan, David L.

    2009-01-01

    Silk fibroin protein-based micro- and nanospheres provide new options for drug delivery due to their biocompatibility, biodegradability and their tunable drug loading and release properties. In the present study, we report a new aqueous-based preparation method for silk spheres with controllable sphere size and shape. The preparation was based on phase separation between silk fibroin and polyvinyl alcohol (PVA) at a weight ratio of 1/1 and 1/4. Water-insoluble silk spheres were easily obtaine...

  17. Hormonal regulation of the death commitment in programmed cell death of the silkworm anterior silk glands.

    Science.gov (United States)

    Matsui, Hiroto; Kakei, Motonori; Iwami, Masafumi; Sakurai, Sho

    2012-12-01

    During larval-pupal transformation, the anterior silk glands (ASGs) of the silkworm Bombyx mori undergo programmed cell death (PCD) triggered by 20-hydroxyecdysone (20E). Under standard in vitro culture conditions (0.3 ml of medium with 1 ?M 20E), ASGs of the fourth-instar larvae do not undergo PCD in response to 20E. Similarly, larvae of the fifth instar do not respond to 20E through day 5 of the instar (V5). However, ASGs of V6 die when challenged by 20E, indicating that the glands might be destined to die before V6 but that a death commitment is not yet present. When we increased the volume of culture medium for one gland from 0.3 to 9 ml, V5 ASGs underwent PCD. We examined the response of ASGs to 20E every day by culturing them in 9 ml of medium and found that ASGs on and after V2 were fully responsive to 20E. Because pupal commitment is associated with juvenile hormone (JH), the corpora allata (a JH secretory organ) were removed on day 3 of the fourth larval instar (IV3), and their ASGs on V0 were cultured with 20E. Removal of the corpora allata allowed the V0 larval ASGs to respond to 20E with PCD. In contrast, topical application of a JH analogue inhibited the response to 20E when applied on or before V5. We conclude that the acquisition of responsiveness to 20E precedes the loss of JH sensitivity, and that the death commitment in ASGs occurs between V5 and 6. PMID:23063728

  18. 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)

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

    2007-10-01

    Full Text Available 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.

  19. 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

  20. Presence of membrane ecdysone receptor in the anterior silk gland of the silkworm Bombyx mori.

    Science.gov (United States)

    Elmogy, Mohamed; Iwami, Masafumi; Sakurai, Sho

    2004-08-01

    Nongenomic action of an insect steroid hormone, 20-hydroxyecdysone (20E), has been implicated in several 20E-dependent events including the programmed cell death of Bombyx anterior silk glands (ASGs), but no information is available for the mode of the action. We provide evidence for a putative membrane receptor located in the plasma membrane of the ASGs. Membrane fractions prepared from the ASGs exhibit high binding activity to [3H]ponasterone A (PonA). The membrane fractions did not contain conventional ecdysone receptor as revealed by Western blot analysis using antibody raised against Bombyx ecdysone receptor A (EcR-A). The binding activity was not solubilized with 1 m NaCl or 0.05% (w/v) MEGA-8, indicating that the binding sites were localized in the membrane. Differential solubilization and temperature-induced phase separation in Triton X-114 showed that the binding sites might be integrated membrane proteins. These results indicated that the binding sites are located in plasma membrane proteins, which we putatively referred to as membrane ecdysone receptor (mEcR). The mEcR exhibited saturable binding for [3H]PonA (Kd = 17.3 nm, Bmax = 0.82 pmol.mg(-1) protein). Association and dissociation kinetics revealed that [3H]PonA associated with and dissociated from mEcR within minutes. The combined results support the existence of a plasmalemmal ecdysteroid receptor, which may act in concert with the conventional EcR in various 20E-dependent developmental events. PMID:15265036

  1. Death commitment in the anterior silk gland of the silkworm, Bombyx mori.

    Science.gov (United States)

    Kakei, Motonori; Iwami, Masafumi; Sakurai, Sho

    2005-01-01

    The insect steroid hormone, 20-hydroxyecdysone (20E) triggers the programmed cell death (PCD) of the anterior silk glands (ASGs) of the silkworm, Bombyx mori. We tried to determine the time of commitment to die (death commitment) by examining ASG responses to 20E and juvenile hormone analogue (JHA) in vivo as well as in vitro. The ASGs obtained late on day 6 of the fifth instar completed PCD when cultured with 20E, while the ASGs obtained on day 4 and cultured with 20E did not undergo PCD. The ASGs became competent to respond to 20E at mid-day 5. The ASGs with responsiveness to 20E were not sensitive to JHA, indicating that the ASGs were committed to die before becoming capable of responding to 20E. Topical application of JHA on day 4 suppressed 20E-induced PCD, but that on day 5 failed to do so, indicating that the death commitment might occur between day 4 and 5. We also determined the time of death commitment after allatectomy of the fourth instar larvae, a procedure that induced the precocious PCD. Timed application of JHA and culture of ASGs with 20E in the presence of JHA showed that the ASGs had lost their sensitivity to JHA between 72 and 96 h after allatectomy, i.e. 24-48 h before precocious gut purge in the allatectomized larvae. This result is similar to that obtained in the fifth instar. We conclude that the cellular commitment to die takes place one day before the ASGs become competent to respond to 20E. PMID:15686642

  2. Effects of Titanium Dioxide Nanoparticles on the Synthesis of Fibroin in Silkworm (Bombyx mori).

    Science.gov (United States)

    Ni, Min; Li, FanChi; Tian, JiangHai; Hu, JingSheng; Zhang, Hua; Xu, KaiZun; Wang, BinBin; Li, YangYang; Shen, WeiDe; Li, Bing

    2015-08-01

    Silkworm (Bombyx mori) is an economically important insect, and its silk production capacity largely depends on its ability to synthesize fibroin. While breeding of B. mori varieties has been a key strategy to improve silk production, little improvement of B. mori silk production has been achieved to date. As a result, the development of sericulture economy has not progressed well, pointing to the need of new ways for improvement of B. mori silk production. Titanium dioxide nanoparticles (TiO2 NPs), a food additive widely used for livestock, have been shown to promote animal growth and increase the protein synthesis in animals. However, no studies on effect of TiO2 NPs on fibroin synthesis in B. mori have been available. In this study, the differential expression profiles of genes and proteins in the silk gland of B. mori fed without or with TiO2 NPs (5 ?g ml(-1)) were analyzed and compared using digital gene expression (DGE), reverse transcription quantitative polymerase chain reaction (RT-qPCR), semi-qPCR, and Western blot analysis. The effects of TiO2 NPs feeding on the activity of proteases in the midgut and the synthesis and transportation of amino acids in hemolymph were also investigated. DGE analyses showed that among a total of 4,741 genes detected, 306 genes were differentially expressed after the TiO2 NPs feeding, of which 137 genes were upregulated whereas 169 genes were downregulated. 106 genes were shown to be involved in fibroin synthesis, of which 97 genes, including those encoding cuticular protein glycine-rich 10, serine protease inhibitor 28, aspartate aminotransferase, lysyl-tRNA synthetase, and splicing factor arginine/serine-rich 6, and silk gland factor-1 (SGF-1), were upregulated with the maximum induction of 8.52-folds, whereas nine genes, including those encoding aspartylglucosaminidase, the cathepsin L in Tribolium castaneum, and similar to SPRY domain-containing SOCS box protein 3, were downregulated with the maximum reduction of 8.11-folds. Transcription levels of nine genes were further verified by RT-qPCR, and the results were consistent with those with DGE. Transcription and expression levels of fibroin light chain (Fib-L) gene were increased after TiO2 NPs feeding, indicating that TiO2 NPs improves fibroin synthesis. Compared with that of control, the mean protease activity was increased by 56.67% in the B. mori fed with TiO2 NPs, and the transport of four key amino acids used for fibroin synthesis in hemolymph was also increased. These findings indicated that TiO2 NPs feeding can improve the absorption and utilization of amino acids from the feed and could be a new way to increase the fibroin synthesis in B. mori. PMID:25876086

  3. Synthetic spider silk fibers spun from Pyriform Spidroin 2, a glue silk protein discovered in orb-weaving spider attachment discs.

    Science.gov (United States)

    Geurts, Paul; Zhao, Liang; Hsia, Yang; Gnesa, Eric; Tang, Simon; Jeffery, Felicia; La Mattina, Coby; Franz, Andreas; Larkin, Leah; Vierra, Craig

    2010-12-13

    Spider attachment disc silk fibers are spun into a viscous liquid that rapidly solidifies, gluing dragline silk fibers to substrates for locomotion or web construction. Here we report the identification and artificial spinning of a novel attachment disc glue silk fibroin, Pyriform Spidroin 2 (PySp2), from the golden orb weaver Nephila clavipes . MS studies support PySp2 is a constituent of the pyriform gland that is spun into attachment discs. Analysis of the PySp2 protein architecture reveals sequence divergence relative to the other silk family members, including the cob weaver glue silk fibroin PySp1. PySp2 contains internal block repeats that consist of two subrepeat units: one dominated by Ser, Gln, and Ala and the other Pro-rich. Artificial spinning of recombinant PySp2 truncations shows that the Ser-Gln-Ala-rich subrepeat is sufficient for the assembly of polymeric subunits and subsequent fiber formation. These studies support that both orb- and cob-weaving spiders have evolved highly polar block-repeat sequences with the ability to self-assemble into fibers, suggesting a strategy to allow fiber fabrication in the liquid environment of the attachment discs. PMID:21053953

  4. Solubilization of the ecdysone binding protein from anterior silk gland cell membranes of the silkworm, Bombyx mori.

    Science.gov (United States)

    Elmogy, Mohamed; Iwami, Masafumi; Sakurai, Sho

    2007-10-01

    We previously provided preliminary evidence for the presence of a putative membrane ecdysone receptor (mEcR) anchored in the plasma membranes of anterior silk glands (ASGs) in Bombyx mori. This receptor may act in concert with the conventional EcR in 20E-dependent programmed cell death of these glands. We report here, for the first time, the solubilization of mEcR from ASG membranes using the zwitterionic detergent CHAPS in the presence of NaCl. Our results show by ligand binding assay that mEcR solubilized this way is functionally active and retains 75% of its native binding activity. We also defined experimental conditions that yielded protein/detergent complexes with partial binding activity, which makes it possible to purify the membrane-bound ecdysone binding protein. PMID:18088173

  5. NMR study of the structures of repeated sequences, GAGXGA (X = S, Y, V), in Bombyx mori liquid silk.

    Science.gov (United States)

    Suzuki, Yu; Yamazaki, Toshimasa; Aoki, Akihiro; Shindo, Heisaburo; Asakura, Tetsuo

    2014-01-13

    The silk fibroin stored in the silk gland of the Bombyx mori silkworm, called "liquid silk", is spun out and converted into the silk fiber with extremely high strength and high toughness. Therefore it is important to determine the silk structure before spinning called Silk I at an atomic level to clarify the fiber formation mechanism. We proposed the repeated type II ?-turn structure as Silk I in the solid state with the model peptide (AG)15 and several solid state NMR techniques previously. In this paper, the solution structure of native "liquid silk" was determined with solution NMR, especially for tandem repeated sequences with (GAGXGA)n (X = S, Y, V) and GAASGA motifs in the B. mori silk fibroin. The assignment of the (13)C, (15)N, and (1)H solution NMR spectra for the repetitive sequence motifs was achieved, and the chemical shifts were obtained. The program, TALOS-N, to predict the backbone torsion angles from the chemical shifts of proteins was applied to these motifs with (13)C?, (13)C?, (13)CO, (1)H?, (1)HN, and (15)N chemical shifts. The twenty-five best matches of torsion angles (?, ?) were well populated and mainly fell into the regions for typical type II ?-turn structures in the (?, ?) map for the GAGXGA (X = S, Y, V) motifs. In contrast, (?, ?) plots for motif GAASGA were scattered, indicating that the motif is in a disordered structure. Furthermore, inter-residue HN-H? NOE cross peaks between i-th and (i+2)th residues in GAGXGA (X = S, Y, V) motifs were observed, supporting the repeated type II ?-turn structure. Thus, we could show the presence of the repeated type II ?-turn structure in "liquid silk". PMID:24266784

  6. Assembly mechanism of recombinant spider silk proteins

    OpenAIRE

    Rammensee, S.; Slotta, U.; Scheibel, T.; Bausch, A.R.

    2008-01-01

    Spider silk threads are formed by the irreversible aggregation of silk proteins in a spinning duct with dimensions of only a few micrometers. Here, we present a microfluidic device in which engineered and recombinantly produced spider dragline silk proteins eADF3 (engineered Araneus diadematus fibroin) and eADF4 are assembled into fibers. Our approach allows the direct observation and identification of the essential parameters of dragline silk assembly. Changes in ionic conditions and pH resu...

  7. Fabrication and Biocompatibility of Electrospun Silk Biocomposites

    Directory of Open Access Journals (Sweden)

    Ick-Soo Kim

    2011-10-01

    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.

  8. Dragline silk: a fiber assembled with low-molecular-weight cysteine-rich proteins.

    Science.gov (United States)

    Pham, Thanh; Chuang, Tyler; Lin, Albert; Joo, Hyun; Tsai, Jerry; Crawford, Taylor; Zhao, Liang; Williams, Caroline; Hsia, Yang; Vierra, Craig

    2014-11-10

    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

  9. Ultrastructure of the silk glands in three adult females of sphecid wasps of the genus Microstigmus (Hymenoptera: Pemphredoninae) Ultraestructura de las glándulas de seda en hembras adultas de tres especies de avispas del género Microstigmus (Hymenoptera: Sphecidae: Pemphredoninae)

    OpenAIRE

    JOSÉ EDUARDO SERRÃO

    2005-01-01

    The ultrastructure of silk glands in adult females of sphecid wasps is described. Individual glands are scattered in the more posterior portion of the metasoma being each gland formed by an enlarged secretory unity with one conducting canal. Each secretory unit is a gland cell containing a large lumen and numerous secretory granules, which are delimited by membrane and filled with middle electron dense content of homogeneous aspect, which are exocytosed into the extra cellular lumen. Cell cyt...

  10. Effect of silk protein surfactant on silk degumming and its properties.

    Science.gov (United States)

    Wang, Fei; Cao, Ting-Ting; Zhang, Yu-Qing

    2015-10-01

    The silk protein surfactant (SPS) first used as a silk degumming agent in this study is an amino acid-type anionic surfactant that was synthesized using silk fibroin amino acids and lauroyl chloride. We studied it systematically in comparison with the traditional degumming methods such as sodium carbonate (Na2CO3) and neutral soap (NS). The experimental results showed that the sericin can be completely removed from the silk fibroin fiber after boiling the fibers three times for 30min and using a bath ratio of 1:80 (g/mL) and a concentration of 0.2% SPS in an aqueous solution. The results of the tensile properties, thermal analysis, and SEM all show that SPS is similar to the NS, far superior to Na2CO3. In short, SPS may be used as an environmentally friendly silk degumming/refining agent in the silk textile industry and in the manufacture of silk floss quilts. PMID:26117747

  11. Developmental profile of annexin IX and its possible role in programmed cell death of the Bombyx mori anterior silk gland.

    Science.gov (United States)

    Kaneko, Yu; Takaki, Keiko; Iwami, Masafumi; Sakurai, Sho

    2006-06-01

    During pupal metamorphosis, the anterior silk gland (ASG) of the silkworm, Bombyx mori, undergoes programmed cell death (PCD), which is triggered by 20-hydroxyecdysone (20E). Annexin IX (ANX IX) has been identified as a 20E-inducible gene in dying ASGs, and we show here that its expression is down-regulated in tissues destined to die but not in tissues that survive pupal metamorphosis. ANX IX expression was high in the ASGs during the feeding period, when the ecdysteroid titer was low, and decreased in response to the rising ecdysteroid titer that triggered pupal metamorphosis. Before gut purge, in vitro exposure of the ASGs to 20E levels corresponding to the ecdysteroid concentration present at the time of gut purge caused a decrease in ANX IX messenger RNA levels. Expression profiles of EcR and USP, and the 20E concentration-responses of these genes, indicate the importance of the relative abundance of EcR-A and EcR-B1 isoforms in ANX IX regulation. These results suggest an involvement of ANX IX in the determination of PCD timing by delaying or suppressing the response to the increase in hemolymph ecdysteroid concentration during the prepupal period. PMID:16849841

  12. Bone tissue engineering with premineralized silk scaffolds.

    Science.gov (United States)

    Kim, Hyeon Joo; Kim, Ung-Jin; Kim, Hyun Suk; Li, Chunmei; Wada, Masahisa; Leisk, Gary G; Kaplan, David L

    2008-06-01

    Silk fibroin biomaterials are being explored as novel protein-based systems for cell and tissue culture. In the present study, biomimetic growth of calcium phosphate on porous silk fibroin polymeric scaffolds was explored to generate organic/inorganic composites as scaffolds for bone tissue engineering. Aqueous-derived silk fibroin scaffolds were prepared with the addition of polyaspartic acid during processing, followed by the controlled deposition of calcium phosphate by exposure to CaCl(2) and Na(2)HPO(4). These mineralized protein-composite scaffolds were subsequently seeded with human bone marrow stem cells (hMSC) and cultured in vitro for 6 weeks under osteogenic conditions with or without BMP-2. The extent of osteoconductivity was assessed by cell numbers, alkaline phosphatase and calcium deposition, along with immunohistochemistry for bone-related outcomes. The results suggest increased osteoconductive outcomes with an increase in initial content of apatite and BMP-2 in the silk fibroin porous scaffolds. The premineralization of these highly porous silk fibroin protein scaffolds provided enhanced outcomes for the bone tissue engineering. PMID:18387349

  13. Negative supercoiling of DNA facilitates an interaction between transcription factor IID and the fibroin gene promoter

    Energy Technology Data Exchange (ETDEWEB)

    Mizutani, Mitsuko; Ohta, Tsutomu; Hirose, Susumu (National Inst. of Genetics, Mishima (Japan)); Watanabe, Hajime; Handa, Hiroshi (Univ. of Tokyo (Japan))

    1991-02-01

    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.

  14. Production of scFv-Conjugated Affinity Silk Powder by Transgenic Silkworm Technology

    OpenAIRE

    Sato, Mitsuru; Kojima, Katsura; Sakuma, Chisato; Murakami, Maria; Aratani, Eriko; Takenouchi, Takato; Tamada, Yasushi; Kitani, Hiroshi

    2012-01-01

    Bombyx mori (silkworm) silk proteins are being utilized as unique biomaterials for medical applications. Chemical modification or post-conjugation of bioactive ligands expand the applicability of silk proteins; however, the processes are elaborate and costly. In this study, we used transgenic silkworm technology to develop single-chain variable fragment (scFv)-conjugated silk fibroin. The cocoons of the transgenic silkworm contain fibroin L-chain linked with scFv as a fusion protein. After di...

  15. Characterization of a family of cysteine rich proteins and development of a MaSp1 derived miniature fibroin

    Science.gov (United States)

    Chuang, Tyler Casey

    Spider silk displays a unique balance of high tensile strength and extensibility, making it one of the toughest materials on the planet. Dragline silk, also known as the lifeline of the spider, represents one of the best studied fiber types and many labs are attempting to produce synthetic dragline silk fibers for commercial applications. In these studies, we develop a minifibroin for expression studies in bacteria. Using recombinant DNA methodology and protein expression studies, we develop a natural minifibroin that contains the highly conserved N- and C-terminal domains, along with several internal block repeats of MaSp1. We also characterize a family of small cysteine-rich proteins (CRPs) and demonstrate that these factors are present within the spinning dope of the major ampullate gland using MS analysis. Biochemical studies and characterization of one of the family members, CRP1, demonstrate that this factor can self-polymerize into higher molecular weight complexes under oxidizing conditions, but can be converted into a monomeric species under reducing conditions. Self-polymerization of CRP1 is also shown to be independent of pH and salt concentration, two important chemical cues that help fibroin aggregation. Overall, our data demonstrate that the polymerization state of CRP1 is dependent upon redox state, suggesting that the redox environment during fiber extrusion may help regulate the oligomerization of CRP molecules during dragline silk production.

  16. Coordinate responses of transcription factors to ecdysone during programmed cell death in the anterior silk gland of the silkworm, Bombyx mori.

    Science.gov (United States)

    Sekimoto, T; Iwami, M; Sakurai, S

    2006-06-01

    Programmed cell death (PCD) in Bombyx mori anterior silk glands (ASGs) is triggered by 20-hydroxyecdysone (20E). We examined the expression profiles and effects of 20E on 11 transcription factor genes in the fifth instar to determine whether they demonstrate the hierarchical control seen in Drosophila PCD. Results indicate that EcR-A and usp-2, but not EcR-B1 or usp-1, may be components of the ecdysone receptor complex. Up-regulation of E75A, BHR3, and three BR-C isoforms, but not E75B, appeared to be associated with the induction of PCD. betaFTZ-F1 was not expressed during PCD execution. Thus, gene control in B. mori ASGs differs from that in Drosophila salivary glands, despite both tissues undergoing PCD in response to 20E at pupal metamorphosis. PMID:16756547

  17. Intrinsically Functionalized Silk (Bombyx Mori)

    OpenAIRE

    Åberg, Gabriel

    2013-01-01

    The goal of the thesis is to incorporate materials with either fluorescent or conductive properties in silk fibers, by feeding silkworms with a diet containing these materials. To achieve this, one would have to breed (rear) silkworm from eggs into larvaes, then to feed the silkworms with this special diet containing fluorescent or conductive materials. Samples of silk were then collected either from spun cocoons or via removing the silk producing organs (silk glands) from the silkworms via d...

  18. A novel marine silk

    Science.gov (United States)

    Kronenberger, Katrin; Dicko, Cedric; Vollrath, Fritz

    2012-01-01

    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.

  19. Aqueous multiphoton lithography with multifunctional silk-centred bio-resists

    Science.gov (United States)

    Sun, Yun-Lu; Li, Qi; Sun, Si-Ming; Huang, Jing-Chun; Zheng, Bo-Yuan; Chen, Qi-Dai; Shao, Zheng-Zhong; Sun, Hong-Bo

    2015-10-01

    Silk and silk fibroin, the biomaterial from nature, nowadays are being widely utilized in many cutting-edge micro/nanodevices/systems via advanced micro/nanofabrication techniques. Herein, for the first time to our knowledge, we report aqueous multiphoton lithography of diversiform-regenerated-silk-fibroin-centric inks using noncontact and maskless femtosecond laser direct writing (FsLDW). Initially, silk fibroin was FsLDW-crosslinked into arbitrary two/three-dimensional micro/nanostructures with good elastic properties merely using proper photosensitizers. More interestingly, silk/metal composite micro/nanodevices with multidimension-controllable metal content can be FsLDW-customized through laser-induced simultaneous fibroin oxidation/crosslinking and metal photoreduction using the simplest silk/Ag+ or silk/[AuCl4]- aqueous resists. Noticeably, during FsLDW, fibroin functions as biological reductant and matrix, while metal ions act as the oxidant. A FsLDW-fabricated prototyping silk/Ag microelectrode exhibited 104-?-1 m-1-scale adjustable electric conductivity. This work not only provides a powerful development to silk micro/nanoprocessing techniques but also creates a novel way to fabricate multifunctional metal/biomacromolecule complex micro/nanodevices for applications such as micro/nanoscale mechanical and electrical bioengineering and biosystems.

  20. A rapid increase in cAMP in response to 20-hydroxyecdysone in the anterior silk glands of the silkworm, Bombyx mori.

    Science.gov (United States)

    Elmogy, Mohamed; Terashima, Jun; Iga, Masatoshi; Iwami, Masafumi; Sakurai, Sho

    2006-08-01

    In the anterior silk glands (ASGs) of the silkworm, Bombyx mori, intracellular cAMP increases transiently to a very high level shortly after the hemolymph ecdysteroid peak in the prepupal period. In cultured ASGs obtained on the day of gut-purge, cAMP levels were increased by 20-hydroxyecdysone (20E), and this increase was enhanced by an inhibitor of phosphodiesterase, but was not affected by alpha-amanitin, indicating the 20E action may not be mediated via gene expression. The increase in cAMP occurred within 30 seconds of exposure to a physiological concentration of 20E (1 microM), and also by ponasterone A. Our findings indicate a nongenomic action of ecdysteroids in insects, which may be an additional mechanism by which this steroid hormone induces acute responses in tissues and cells. PMID:16971790

  1. 20-Hydroxyecdysone regulation of two isoforms of the Ets transcription factor E74 gene in programmed cell death in the silkworm anterior silk gland.

    Science.gov (United States)

    Sekimoto, T; Iwami, M; Sakurai, S

    2007-10-01

    Programmed cell death of larval-specific tissues in insects is under the control of 20-hydroxyecdysone (20E). The ecdysteroid-regulated early genes are conserved in the programmed cell death of anterior silk glands (ASGs) in Bombyx mori and salivary glands in Drosophila melanogaster. We identified and characterized two isoforms of the Ets transcription factor E74 gene in B. mori (BmE74). In ASGs of B. mori last instar larvae, the Bm74A mRNA level increased concomitantly with an increase in haemolymph ecdysteroid titre after gut purge. The optimal 20E concentration for stimulation of Bm74A in ASGs was 4 microM, a similar value to the peak haemolymph ecdysteroid concentration after gut purge. In contrast, BmE74B expression peaked on day 5 of the feeding period, after which it did not increase again. These findings suggest that the BmE74 isoforms play different roles in the regulation of programmed cell death in B. mori ASGs. PMID:17894557

  2. Toward spinning artificial spider silk.

    Science.gov (United States)

    Rising, Anna; Johansson, Jan

    2015-05-01

    Spider silk is strong and extensible but still biodegradable and well tolerated when implanted, making it the ultimate biomaterial. Shortcomings that arise in replicating spider silk are due to the use of recombinant spider silk proteins (spidroins) that lack native domains, the use of denaturing conditions under purification and spinning and the fact that the understanding of how spiders control silk formation is incomplete. Recent progress has unraveled the molecular mechanisms of the spidroin N- and C-terminal nonrepetitive domains (NTs and CTs) and revealed the pH and ion gradients in spiders' silk glands, clarifying how spidroin solubility is maintained and how silk is formed in a fraction of a second. Protons and CO2, generated by carbonic anhydrase, affect the stability and structures of the NT and CT in different ways. These insights should allow the design of conditions and devices for the spinning of recombinant spidroins into native-like silk. PMID:25885958

  3. Production of scFv-conjugated affinity silk film and its application to a novel enzyme-linked immunosorbent assay

    OpenAIRE

    Mitsuru Sato; Katsura Kojima; Chisato Sakuma; Maria Murakami; Yasushi Tamada; Hiroshi Kitani

    2014-01-01

    Bombyx mori (silkworm) silk proteins have been utilized as unique biomaterials for various medical applications. To develop a novel affinity silk material, we generated a transgenic silkworm that spins silk protein containing the fibroin L-chain linked with the single-chain variable fragment (scFv) as a fusion protein. Previously, the scFv-conjugated “affinity” silk powder specifically immunoprecipitated its target protein, Wiskott-Aldrich syndrome protein. To expand the applicability of affi...

  4. Intracellular mobilization of Ca2+ by the insect steroid hormone 20-hydroxyecdysone during programmed cell death in silkworm anterior silk glands.

    Science.gov (United States)

    Manaboon, Manaporn; Iga, Masatoshi; Iwami, Masafumi; Sakurai, Sho

    2009-02-01

    20-Hydroxyecdysone (20E) triggers programmed cell death (PCD) and regulates de novo gene expression in the anterior silk glands (ASGs) of the silkworm Bombyx mori. PCD is mediated via a nongenomic pathway that includes Ca2+ as a second messenger and the activation of protein kinase C/caspase-3-like protease; however, the steps leading to a concomitant buildup of intracellular Ca2+ are unknown. We employed pharmacological tools to identify the components of this pathway. ASGs were cultured in the presence of 1 microM 20E and one of the following inhibitors: a G-protein-coupled receptor (GPCR) inhibitor, a phospholipase C (PLC) inhibitor, an inositol 1,4,5-trisphosphate receptor (IP3R) antagonist, and an L- or T-type Ca2+ channel blocker. The T-type Ca2+ channel blocker inhibited 20E-induced nuclear and DNA fragmentation; in contrast, PCD was induced by 20E in Ca2+-free medium, indicating that the source of Ca2+ is an intracellular reservoir. The IP3R antagonist inhibited nuclear and DNA fragmentation, suggesting that the endoplasmic reticulum may be the Ca2+ source. Finally, the GPCR and PLC inhibitors effectively blocked nuclear and DNA fragmentation. Our results indicate that 20E increases the intracellular level of Ca2+ by activating IP3R, and that this effect may be brought about by the serial activation of GPCR, PLC, and IP3. PMID:19041319

  5. Preparation and mechanical properties of layers made of recombinant spider silk proteins and silk from silk worm

    Science.gov (United States)

    Junghans, F.; Morawietz, M.; Conrad, U.; Scheibel, T.; Heilmann, A.; Spohn, U.

    2006-02-01

    Layers of recombinant spider silks and native silks from silk worms were prepared by spin-coating and casting of various solutions. FT-IR spectra were recorded to investigate the influence of the different mechanical stress occurring during the preparation of the silk layers. The solubility of the recombinant spider silk proteins SO1-ELP, C16, AQ24NR3, and of the silk fibroin from Bombyx mori were investigated in hexafluorisopropanol, ionic liquids and concentrated salt solutions. The morphology and thickness of the layers were determined by Atomic Force Microscopy (AFM) or with a profilometer. The mechanical behaviour was investigated by acoustic impedance analysis by using a quartz crystal microbalance (QCMB) as well as by microindentation. The density of silk layers (dsilk layers thicker than 300 nm significant changes of the half-band-half width can be correlated with increasing energy dissipation. Microhardness measurements demonstrate that recombinant spider silk and sericine-free Bombyx mori silk layers achieve higher elastic penetration modules EEP and Martens hardness values HM than those of polyethylenterephthalate (PET) and polyetherimide (PEI) foils.

  6. Silk-mediated synthesis and modification of photoluminescent ZnO nanoparticles

    International Nuclear Information System (INIS)

    In this article, a bio-inspired silk-mediated method was established to produce natural material-modified photoluminescent zinc oxide nanoparticles (nano-ZnO). Silk fibroin fibers were employed as the reactive substrates to synthesize nano-ZnO, and silk fibroins (SF) were taken as the biocompatible stabilizers to modify dispersed nano-ZnO. As-prepared nano-ZnO were mainly hexagonal phase particles with diameter around 13 nm. The resulting nano-ZnO/SF hybrids displayed orange emission and good biocompatibility in aqueous system.

  7. Conservation of essential design features in coiled coil silks.

    Science.gov (United States)

    Sutherland, Tara D; Weisman, Sarah; Trueman, Holly E; Sriskantha, Alagacone; Trueman, John W H; Haritos, Victoria S

    2007-11-01

    Silks are strong protein fibers produced by a broad array of spiders and insects. The vast majority of known silks are large, repetitive proteins assembled into extended beta-sheet structures. Honeybees, however, have found a radically different evolutionary solution to the need for a building material. The 4 fibrous proteins of honeybee silk are small ( approximately 30 kDa each) and nonrepetitive and adopt a coiled coil structure. We examined silks from the 3 superfamilies of the Aculeata (Hymenoptera: Apocrita) by infrared spectroscopy and found coiled coil structure in bees (Apoidea) and in ants (Vespoidea) but not in parasitic wasps of the Chrysidoidea. We subsequently identified and sequenced the silk genes of bumblebees, bulldog ants, and weaver ants and compared these with honeybee silk genes. Each species produced orthologues of the 4 small fibroin proteins identified in honeybee silk. Each fibroin contained a continuous predicted coiled coil region of around 210 residues, flanked by 23-160 residue length N- and C-termini. The cores of the coiled coils were unusually rich in alanine. There was extensive sequence divergence among the bee and ant silk genes (<50% similarity between the alignable regions of bee and ant sequences), consistent with constant and equivalent divergence since the bee/ant split (estimated to be 155 Myr). Despite a high background level of sequence diversity, we have identified conserved design elements that we propose are essential to the assembly and function of coiled coil silks. PMID:17703050

  8. Preparation and characterization of silk/silica hybrid biomaterials by sol-gel crosslinking process

    Energy Technology Data Exchange (ETDEWEB)

    Hou Aiqin, E-mail: aiqinhou@dhu.edu.c [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China); Chen Huawei [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China)

    2010-03-15

    The silk/silica hybrid biomaterials are synthesized by sol-gel crosslinking process. The chemical and morphological structures of silk/silica hybrids are investigated with micro-FT-IR spectra, X-ray diffraction, SEM, AFM, and DSC. The results show that the crosslinking reactions among inorganic nano-particles, fibroin and 2,4,6-tri[(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) take place during sol-gel process. The silk/silica hybrids form new molecular structures containing not only organic fibroin but also inorganic nano-silica particles. The inorganic particles are bounded to the fibroin through covalent bonds. The silk/silica hybrids can form excellent film with very even nanometer particles. The thermal properties of organic/inorganic hybrid are improved.

  9. Preparation and characterization of silk/silica hybrid biomaterials by sol-gel crosslinking process

    International Nuclear Information System (INIS)

    The silk/silica hybrid biomaterials are synthesized by sol-gel crosslinking process. The chemical and morphological structures of silk/silica hybrids are investigated with micro-FT-IR spectra, X-ray diffraction, SEM, AFM, and DSC. The results show that the crosslinking reactions among inorganic nano-particles, fibroin and 2,4,6-tri[(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) take place during sol-gel process. The silk/silica hybrids form new molecular structures containing not only organic fibroin but also inorganic nano-silica particles. The inorganic particles are bounded to the fibroin through covalent bonds. The silk/silica hybrids can form excellent film with very even nanometer particles. The thermal properties of organic/inorganic hybrid are improved.

  10. Physical characterization of functionalized spider silk: electronic and sensing properties

    OpenAIRE

    Eden Steven, Jin Gyu Park, Anant Paravastu, Elsa Branco Lopes, James S Brooks, Ongi Englander, Theo Siegrist, Papatya Kaner and Rufina G Alamo

    2011-01-01

    This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of ?-sheet (crystalline) and amorphous (helical) structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this invest...

  11. The Performance of Silk Scaffolds in a Rat Model of Augmentation Cystoplasty

    OpenAIRE

    Seth, Abhishek; Chung, Yeun Goo; Gil, Eun Seok; Tu, Duong; Franck, Debra; Di Vizio, Dolores; Adam, Rosalyn M; Kaplan, David L.; Estrada, Carlos R.; Mauney, Joshua R.

    2013-01-01

    The diverse processing plasticity of silk-based biomaterials offers a versatile platform for understanding the impact of structural and mechanical matrix properties on bladder regenerative processes. Three distinct groups of 3-D matrices were fabricated from aqueous solutions of Bombyx mori silk fibroin either by a gel spinning technique (GS1 and GS2 groups) or a solvent-casting/salt-leaching method in combination with silk film casting (FF group). SEM analyses revealed that GS1 matrices cons...

  12. Mandibular Repair in Rats with Premineralized Silk Scaffolds and BMP-2-modified bMSCs

    OpenAIRE

    Jiang, Xinquan; Zhao, Jun; Wang, Shaoyi; Sun, XiaoJuan; ZHANG, XIULI; CHEN, JAKE; Kaplan, David L.; Zhang, Zhiyuan

    2009-01-01

    Premineralized silk fibroin protein scaffolds (mSS) were prepared to combine the osteoconductive properties of biological apatite with aqueous-derived silk scaffold (SS) as a composite scaffold for bone regeneration. The aim of present study was to evaluate the effect of premineralized silk scaffolds combined with bone morphogenetic protein-2 (BMP-2) modified bone marrow stromal cells (bMSCs) to repair mandibular bony defects in a rat model. bMSCs were expanded and transduced with adenovirus ...

  13. Silk nanospheres and microspheres from silk/pva blend films for drug delivery.

    Science.gov (United States)

    Wang, Xiaoqin; Yucel, Tuna; Lu, Qiang; Hu, Xiao; Kaplan, David L

    2010-02-01

    Silk fibroin protein-based micro- and nanospheres provide new options for drug delivery due to their biocompatibility, biodegradability and their tunable drug loading and release properties. In the present study, we report a new aqueous-based preparation method for silk spheres with controllable sphere size and shape. The preparation was based on phase separation between silk fibroin and polyvinyl alcohol (PVA) at a weight ratio of 1/1 and 1/4. Water-insoluble silk spheres were easily obtained from the blend in a three step process: (1) air-drying the blend solution into a film, (2) film dissolution in water and (3) removal of residual PVA by subsequent centrifugation. In both cases, the spheres had approximately 30% beta-sheet content and less than 5% residual PVA. Spindle-shaped silk particles, as opposed to the spherical particles formed above, were obtained by stretching the blend films before dissolving in water. Compared to the 1/1 ratio sample, the silk spheres prepared from the 1/4 ratio sample showed a more homogeneous size distribution ranging from 300 nm up to 20 microm. Further studies showed that sphere size and polydispersity could be controlled either by changing the concentration of silk and PVA or by applying ultrasonication on the blend solution. Drug loading was achieved by mixing model drugs in the original silk solution. The distribution and loading efficiency of the drug molecules in silk spheres depended on their hydrophobicity and charge, resulting in different drug release profiles. The entire fabrication procedure could be completed within one day. The only chemical used in the preparation except water was PVA, an FDA-approved ingredient in drug formulations. Silk micro- and nanospheres reported have potential as drug delivery carriers in a variety of biomedical applications. PMID:19945157

  14. Mechanisms and Control of Silk-based Electrospinning

    OpenAIRE

    Zhang, Feng; Zuo, Baoqi; Fan, Zhihai; Xie, Zonggang; LU, QIANG; Zhang, Xueguang; Kaplan, David L.

    2012-01-01

    Silk fibroin (SF) nanofibers, formed through electrospinning, have attractive utility in regenerative medicine due to the biocompatibility, mechanical properties and tailorable degradability. The mechanism of SF electrospun nanofiber formation was studied to gain new insight into the formation and control of nanofibers. SF electrospinning solutions with different nanostructures (nanospheres or nanofilaments) were prepared by controlling the drying process during the preparation of regenerated...

  15. An axial distribution of seeding, proliferation, and osteogenic differentiation of MC3T3-E1 cells and rat bone marrow-derived mesenchymal stem cells across a 3D Thai silk fibroin/gelatin/hydroxyapatite scaffold in a perfusion bioreactor.

    Science.gov (United States)

    Sinlapabodin, Salita; Amornsudthiwat, Phakdee; Damrongsakkul, Siriporn; Kanokpanont, Sorada

    2016-01-01

    In cell culture, a perfusion bioreactor provides effective transportation of nutrients, oxygen, and waste removal to and from the core of the scaffold. In addition, it provides mechanical stimuli for enhancing osteogenic differentiation. In this study, we used an axial distribution of cell numbers, alkaline phosphatase (ALP) enzyme activity, and calcium content across 4 cross-sections of 10mm thick scaffold, made of Thai silk fibroin (SF)/gelatin (G)/hydroxyapatite (HA), as a tool to evaluate the suitable perfusion flow rate. These evaluations cover all cellular developmental phases starting from seeding, to proliferation, and later osteogenic differentiation. Mouse pre-osteoblastic MC3T3-E1 cell lines were used as a cell model during seeding and proliferation. The bioreactor seeded scaffold provided more uniform cell distribution across the scaffold compared to centrifugal and agitation seeding, while the overall number of adhered cells from bioreactor seeding was slightly lower than agitation seeding. The dynamic culture using 1ml/min perfusion flow rate (initial shear stress of 0.1dyn/cm(2)) enabled statistically higher MC3T3-E1 proliferation, ALP activity, and calcium deposition than those observed in the static-culturing condition. However, the perfusion flow rate of 1ml/min seemed not to be enough for enhancing ALP expression across all sections of the scaffold. Rat bone marrow derived stromal cells (rMSC) were used in the detachment test and osteogenic differentiation. It was found that perfusion flow rate of 5ml/min caused statistically higher cell detachment than that of 1 and 3ml/min. The perfusion flow rate of 3ml/min gave the highest rMSC osteogenic differentiation on a SF/G/HA scaffold than other flow rates, as observed from the significantly highest number of ALP enzyme activity and the calcium content without any significant cell growth. In addition, all of these parameters were evenly distributed across all scaffold sections. PMID:26478392

  16. The expression of GFP under the control of fibroin promotor in primary ovarian cells of Antheraea pernyi

    Indian Academy of Sciences (India)

    Wenli Li; Liji Jin; Pengcheng Bu; Lijia An

    2003-12-01

    The fibroin promoter can stably express foreign gene in lepidopteran cells. Total RNA was extracted from the gland of silkworm, Antheraea pernyi and the transcription initiation site of fibroin gene of A. pernyi was identified by RNA ligase mediated rapid amplification of cDNA ends (RLM-RACE). The expression vector (pGFP-N2/Fib) was constructed by use of replacing the CMV promoter with the fibroin promoter. The results of visual screening under a fluorescent inverted microscope and Western blot analysis indicated that the GFP gene was expressed in the primary cells of ovary origins from A. pernyi.

  17. SPIDER SILK

    Directory of Open Access Journals (Sweden)

    PORAV Viorica

    2014-05-01

    Full Text Available The strengthness and toughness of spider fiber and its multifunctional nature is only surpassed in some cases by synthetic high performance fibers. In the world of natural fibers, spider silk has been long time recognized as a wonder fiber for its unique combination of high strength and rupture elongation. Scientists in civil military engineering reveal that the power of biological material (spider silk lies in the geometric configuration of structural protein, and the small cluster of week hydrogen bonds that works together to resist force and dissipate energy. Each spider and each type of silk has a set of mechanical properties optimized for their biological function. Most silks, in particular deagline silk, have exceptional mechanical properties. They exhibit a unique combination of high tensile strength and extensibility (ductility. This enables a silk fiber to absorb a lot of energy before breaking (toughness, the area under a stress- strain curve. A frequent mistake made in the mainstream media is to confuse strength and toughness when comparing silk to other materials. As shown below in detail, weight for weight, silk is stronger than steel, but not as strong as Kevlar. Silk is,however, tougher than both.This paper inform about overview on the today trend in the world of spider silk.

  18. Characterization on Eri (Philosamia ricini) Fibroin Film: Morphology, Structure and Thermal Properties

    OpenAIRE

    Y. Srisuwan; N. Narkkong; P. Srihanam

    2009-01-01

    This study aims to prepare Eri Silk Fibroin (SF) solution and construct of its film. The Eri cocoons were firstly removed of sericin and then dissolved by 6 M Ca(NO3)2. The SF solution was dialyzed before measurement of silk percentage by weight. The solvate protein was then taken to prepare of SF film using 0.5 and 1% weight. The 10 mL of SF solution was cast on the polystyrene plates, left in room temperature for 2 days. The obtained SF films were then observed under Scanning Electron Micro...

  19. Differential Scanning Fluorimetry provides high throughput data on silk protein transitions.

    Science.gov (United States)

    Vollrath, Fritz; Hawkins, Nick; Porter, David; Holland, Chris; Boulet-Audet, Maxime

    2014-07-01

    Here we present a set of measurements using Differential Scanning Fluorimetry (DSF) as an inexpensive, high throughput screening method to investigate the folding of silk protein molecules as they abandon their first native melt conformation, dehydrate and denature into their final solid filament conformation. Our first data and analyses comparing silks from spiders, mulberry and wild silkworms as well as reconstituted `silk' fibroin show that DSF can provide valuable insights into details of silk denaturation processes that might be active during spinning. We conclude that this technique and technology offers a powerful and novel tool to analyse silk protein transitions in detail by allowing many changes to the silk solutions to be tested rapidly with microliter scale sample sizes. Such transition mechanisms will lead to important generic insights into the folding patterns not only of silks but also of other fibrous protein (bio)polymers.

  20. Hierarchical charge distribution controls self-assembly process of silk in vitro

    Science.gov (United States)

    Zhang, Yi; Zhang, Cencen; Liu, Lijie; Kaplan, David L.; Zhu, Hesun; Lu, Qiang

    2015-10-01

    Silk materials with different nanostructures have been developed without the understanding of the inherent transformation mechanism. Here we attempt to reveal the conversion road of the various nanostructures and determine the critical regulating factors. The regulating conversion processes influenced by a hierarchical charge distribution were investigated, showing different transformations between molecules, nanoparticles and nanofibers. Various repulsion and compressive forces existed among silk fibroin molecules and aggregates due to the exterior and interior distribution of charge, which further controlled their aggregating and deaggregating behaviors and finally formed nanofibers with different sizes. Synergistic action derived from molecular mobility and concentrations could also tune the assembly process and final nanostructures. It is suggested that the complicated silk fibroin assembly processes comply a same rule based on charge distribution, offering a promising way to develop silk-based materials with designed nanostructures.

  1. Integration of silk protein in organic and light-emitting transistors

    OpenAIRE

    Capelli, R.; Amsden, J. J.; Generali, G.; Toffanin, S; Benfenati, V.; Muccini, M; Kaplan, D. L.; Omenetto, F. G.; Zamboni, R.

    2011-01-01

    We present the integration of a natural protein into electronic and optoelectronic devices by using silk fibroin as a thin film dielectric in an organic thin film field-effect transistor (OFET) ad an organic light emitting transistor device (OLET) structures. Both n- (perylene) and p-type (thiophene) silk-based OFETs are demonstrated. The measured electrical characteristics are in agreement with high-efficiency standard organic transistors, namely charge mobility of the order of 10-2 cm2/Vs a...

  2. Biopatterning of Silk Proteins for Soft Micro-optics.

    Science.gov (United States)

    Pal, Ramendra K; Kurland, Nicholas E; Wang, Congzhou; Kundu, Subhas C; Yadavalli, Vamsi K

    2015-04-29

    Silk proteins from spiders and silkworms have been proposed as outstanding candidates for soft micro-optic and photonic applications because of their optical transparency, unique biological properties, and mechanical robustness. Here, we present a method to form microstructures of the two constituent silk proteins, fibroin and sericin for use as an optical biomaterial. Using photolithography, chemically modified silk protein photoresists are patterned in 2D arrays of periodic patterns and Fresnel zone plates. Angle-dependent iridescent colors are produced in these periodic micropatterns because of the Bragg diffraction. Silk protein photolithography can used to form patterns on different substrates including flexible sheets with features of any shape with high fidelity and resolution over large areas. Finally, we show that these mechanically stable and transparent iridescent architectures are also completely biodegradable. This versatile and scalable technique can therefore be used to develop biocompatible, soft micro-optic devices that can be degraded in a controlled manner. PMID:25853731

  3. Unravelling the biodiversity of nanoscale signatures of spider silk fibres

    Science.gov (United States)

    Silva, Luciano P.; Rech, Elibio L.

    2013-12-01

    Living organisms are masters at designing outstanding self-assembled nanostructures through a hierarchical organization of modular proteins. Protein-based biopolymers improved and selected by the driving forces of molecular evolution are among the most impressive archetypes of nanomaterials. One of these biomacromolecules is the myriad of compound fibroins of spider silks, which combine surprisingly high tensile strength with great elasticity. However, no consensus on the nano-organization of spider silk fibres has been reached. Here we explore the biodiversity of spider silk fibres, focusing on nanoscale characterization with high-resolution atomic force microscopy. Our results reveal an evolution of the nanoroughness, nanostiffness, nanoviscoelastic, nanotribological and nanoelectric organization of microfibres, even when they share similar sizes and shapes. These features are related to unique aspects of their molecular structures. The results show that combined nanoscale analyses of spider silks may enable the screening of appropriate motifs for bioengineering synthetic fibres from recombinant proteins.

  4. BMP-Silk Composite Matrices Heal Critically Sized Femoral Defects

    OpenAIRE

    Kirker-Head, C; Karageorgiou, V (Vassilis); Hofmann Boss, S (Sandra); Fajardo, R; Betz, O; Merkle, HP; Hilbe, M.; Rechenberg, B (Brigitte) von; McCool, J.; Abrahamsen, L; Nazarian, A.; Cory, E; Curtis, M; Kaplan, DL (David); Meinel, L (Lorenz)

    2007-01-01

    Clinical drawbacks of bone grafting prompt the search for alternative bone augmentation technologies such as use of growth and differentiation factors, gene therapy, and cell therapy. Osteopromotive matrices are frequently employed for the local delivery and controlled release of these augmentation agents. Some matrices also provide an osteoconductive scaffold to support new bone growth. In this study, silkworm-derived silk fibroin was evaluated as an osteoconductive matrix for healing critic...

  5. Crystal networks in silk fibrous materials: from hierarchical structure to ultra performance.

    Science.gov (United States)

    Nguyen, Anh Tuan; Huang, Qiao-Ling; Yang, Zhen; Lin, Naibo; Xu, Gangqin; Liu, Xiang Yang

    2015-03-01

    This review provides a comprehensive survey of the structural characteristics of crystal networks of silk soft fibrous materials in correlation with the macroscopic properties/performance and the network formation mechanisms. The correlation between the hierarchical mesoscopic structures and the mechanical properties of silk soft fibrous materials including silk fibroin hydrogels and naturally spun silk fibers are addressed based on the hierarchical crystal network models. Namely, two types of hierarchical networks are identified: the weak nanofibril-nanofibril interaction case (i.e., silk fibroin hydrogels), and the strong nanofibril-nanofibril interaction case (i.e., silk fibers). The macroscopic properties, i.e., the rheological/mechanical properties, can be controlled in terms of tuning different levels of hierarchical network structures by ultrasonication-induced gelation, introducing the initial nucleation centers, etc. Such controls take effect by different mesoscale assembly pathways, which are found to occur via different routes of the nucleation and growth processes. Furthermore, the hierarchical network model of soft fibrous materials can be applied to explain the superior mechanical properties and the unique strain-hardening behaviors of spider silk fibers within the framework of hierarchical breaking mechanism. Obviously, a knowledge of crystal networks will allow the prediction of the performance and engineering strategy of silk fibrous materials in generals. PMID:25510895

  6. Production of fibroin nanopowder through electrospraying

    International Nuclear Information System (INIS)

    Fibroin is a biomaterial and in the powder form, has found applications such as food and cosmetic additive as well as drug delivery. Various methods have been employed to produce fibroin powder with different particle size range. In this study, a novel and original application of electrospraying technique capable of producing fibroin nanopowder is presented. Our technique is based on electrospraying of dilute fibroin solution in formic acid. Moreover, the effect of variables in electrospraying, namely, concentration of fibroin solution, voltage, feed rate, and needle–collector distance, on average particle size of fibroin nanopowder has been studied. The result of this study showed that electrospraying is capable of producing fibroin nanopowder with average particle size as low as 80 nm. In fact in comparison to other methods reported in the literature, electrospraying alongside with the precipitation method produce fibroin nanopowder with the lowest particle size. However, nanopowder obtained through electrospraying technique enjoys a more uniform spherical shape and size. As far as the variables are concerned, it was ascertained that lower concentrations, lower feed rates and longer needle–collector distances lead to a decrease in the average particle size of fibroin nanopowder. Increasing voltage up to 20 kV decreases the particle size; but with higher voltages the average particle size increases. FT-IR and XRD studies showed that the fibroin nanopowder has a ?-sheets structure, similar to fibroin filaments but with a lower crystallinity index.

  7. Production of fibroin nanopowder through electrospraying

    Energy Technology Data Exchange (ETDEWEB)

    Gholami, A.; Tavanai, H., E-mail: tavanai@cc.iut.ac.ir; Moradi, A. R. [Isfahan University of Technology, Department of Textile Engineering, Center of Excellence for Environmental Nanotechnology (Iran, Islamic Republic of)

    2011-05-15

    Fibroin is a biomaterial and in the powder form, has found applications such as food and cosmetic additive as well as drug delivery. Various methods have been employed to produce fibroin powder with different particle size range. In this study, a novel and original application of electrospraying technique capable of producing fibroin nanopowder is presented. Our technique is based on electrospraying of dilute fibroin solution in formic acid. Moreover, the effect of variables in electrospraying, namely, concentration of fibroin solution, voltage, feed rate, and needle-collector distance, on average particle size of fibroin nanopowder has been studied. The result of this study showed that electrospraying is capable of producing fibroin nanopowder with average particle size as low as 80 nm. In fact in comparison to other methods reported in the literature, electrospraying alongside with the precipitation method produce fibroin nanopowder with the lowest particle size. However, nanopowder obtained through electrospraying technique enjoys a more uniform spherical shape and size. As far as the variables are concerned, it was ascertained that lower concentrations, lower feed rates and longer needle-collector distances lead to a decrease in the average particle size of fibroin nanopowder. Increasing voltage up to 20 kV decreases the particle size; but with higher voltages the average particle size increases. FT-IR and XRD studies showed that the fibroin nanopowder has a {beta}-sheets structure, similar to fibroin filaments but with a lower crystallinity index.

  8. SPIDER SILK

    OpenAIRE

    PORAV Viorica

    2014-01-01

    The strengthness and toughness of spider fiber and its multifunctional nature is only surpassed in some cases by synthetic high performance fibers. In the world of natural fibers, spider silk has been long time recognized as a wonder fiber for its unique combination of high strength and rupture elongation. Scientists in civil military engineering reveal that the power of biological material (spider silk) lies in the geometric configuration of structural protein, and the small cluster of we...

  9. In vivo bioresponses to silk proteins.

    Science.gov (United States)

    Thurber, Amy E; Omenetto, Fiorenzo G; Kaplan, David L

    2015-12-01

    Silks are appealing materials for numerous biomedical applications involving drug delivery, tissue engineering, or implantable devices, because of their tunable mechanical properties and wide range of physical structures. In addition to the functionalities needed for specific clinical applications, a key factor necessary for clinical success for any implanted material is appropriate interactions with the body in vivo. This review summarizes our current understanding of the in vivo biological responses to silks, including degradation, the immune and inflammatory response, and tissue remodeling with particular attention to vascularization. While we focus in this review on silkworm silk fibroin protein due to the large quantity of in vivo data thanks to its widespread use in medical materials and consumer products, spider silk information is also included if available. Silk proteins are degraded in the body on a time course that is dependent on the method of silk fabrication and can range from hours to years. Silk protein typically induces a mild inflammatory response that decreases within a few weeks of implantation. The response involves recruitment and activation of macrophages and may include activation of a mild foreign body response with the formation of multinuclear giant cells, depending on the material format and location of implantation. The number of immune cells present decreases with time and granulation tissue, if formed, is replaced by endogenous, not fibrous, tissue. Importantly, silk materials have not been demonstrated to induce mineralization, except when used in calcified tissues. Due to its ability to be degraded, silk can be remodeled in the body allowing for vascularization and tissue ingrowth with eventual complete replacement by native tissue. The degree of remodeling, tissue ingrowth, or other specific cell behaviors can be modulated with addition of growth or other signaling factors. Silk can also be combined with numerous other materials including proteins, synthetic polymers, and ceramics to enhance its characteristics for a particular function. Overall, the diverse array of silk materials shows excellent bioresponses in vivo with low immunogenicity and the ability to be remodeled and replaced by native tissue making it suitable for numerous clinical applications. PMID:26322725

  10. Reproducing natural spider silks' copolymer behavior in synthetic silk mimics.

    Science.gov (United States)

    An, Bo; Jenkins, Janelle E; Sampath, Sujatha; Holland, Gregory P; Hinman, Mike; Yarger, Jeffery L; Lewis, Randolph

    2012-12-10

    Dragline silk from orb-weaving spiders is a copolymer of two large proteins, major ampullate spidroin 1 (MaSp1) and 2 (MaSp2). The ratio of these proteins is known to have a large variation across different species of orb-weaving spiders. NMR results from gland material of two different species of spiders, N. clavipes and A. aurantia , indicates that MaSp1 proteins are more easily formed into ?-sheet nanostructures, while MaSp2 proteins form random coil and helical structures. To test if this behavior of natural silk proteins could be reproduced by recombinantly produced spider silk mimic protein, recombinant MaSp1/MaSp2 mixed fibers as well as chimeric silk fibers from MaSp1 and MaSp2 sequences in a single protein were produced based on the variable ratio and conserved motifs of MaSp1 and MaSp2 in native silk fiber. Mechanical properties, solid-state NMR, and XRD results of tested synthetic fibers indicate the differing roles of MaSp1 and MaSp2 in the fiber and verify the importance of postspin stretching treatment in helping the fiber to form the proper spatial structure. PMID:23110450

  11. Effect of Sericin on Mechanical Behavior of Composite Material Reinforced by Silk Woven Fabric

    Science.gov (United States)

    Kimura, Teruo; Ino, Haruhiro; Hanada, Koji; Katori, Sigetaka

    Recent, attention has been given to shift from glass fibers and carbon fibers to natural fibers for FRP composites for the goal of protecting the environment. This paper concerned with the application of silk fabric for composite materials. Polypropylene (PP) was used for the matrix material and the silk fabric composites were molded using a compression molding method. Especially, the effect of sericin on mechanical behaviors of composite materials was discussed. Good adhesion between silk and PP was obtained by removing the sericin existing around the fibroin. The tensile modulus of composite decreased with decreasing the sericin because of the flexibility of silk fibers without sericin. In particular, the higher Izod impact value was obtained for the composites containing the silk fibers without sericin.

  12. Formulation of Biologically-Inspired Silk-Based Drug Carriers for Pulmonary Delivery Targeted for Lung Cancer

    Science.gov (United States)

    Kim, Sally Yunsun; Naskar, Deboki; Kundu, Subhas C.; Bishop, David P.; Doble, Philip A.; Boddy, Alan V.; Chan, Hak-Kim; Wall, Ivan B.; Chrzanowski, Wojciech

    2015-01-01

    The benefits of using silk fibroin, a major protein in silk, are widely established in many biomedical applications including tissue regeneration, bioactive coating and in vitro tissue models. The properties of silk such as biocompatibility and controlled degradation are utilized in this study to formulate for the first time as carriers for pulmonary drug delivery. Silk fibroin particles are spray dried or spray-freeze-dried to enable the delivery to the airways via dry powder inhalers. The addition of excipients such as mannitol is optimized for both the stabilization of protein during the spray-freezing process as well as for efficient dispersion using an in vitro aerosolisation impactor. Cisplatin is incorporated into the silk-based formulations with or without cross-linking, which show different release profiles. The particles show high aerosolisation performance through the measurement of in vitro lung deposition, which is at the level of commercially available dry powder inhalers. The silk-based particles are shown to be cytocompatible with A549 human lung epithelial cell line. The cytotoxicity of cisplatin is demonstrated to be enhanced when delivered using the cross-linked silk-based particles. These novel inhalable silk-based drug carriers have the potential to be used as anti-cancer drug delivery systems targeted for the lungs. PMID:26234773

  13. Radiation processing of silk protein (Bilateral research cooperation OAEP and JAERI. December 1998 - December 2002)

    International Nuclear Information System (INIS)

    Thailand's production of silk, about 1,200 ton per year, also gives about 10% of silk waste which is expected to be recycled into new material (non-textile application) and to avoid environmental pollution. For this purpose, cooperative program 'radiation processing of silk protein' was conducted between OAEP (Thailand) and JAERI. Among the results already obtained are: radiation degradation of silk protein (fibroin) with gamma rays at 160 kGy, production of fine silk milled powder (<90 microns) by electron beam irradiation at 250-1000 kGy (dry method) using electron accelerator (1 MeV, 1 mA), use of antioxidant effect of silk protein on lipid peroxidation and antibacterial activity of irradiated silk protein powder, and wound dressing hydrogel mixed with silk protein and use of antibacterial activity of cross-linked silk protein/PVA hydrogel. Other topics of interest are gamma irradiation of anionic natural polymer solution for use as latex protein scavenger and gamma radiation degradation of chitosan for use as plant growth promoter and fungicide. (S. Ohno)

  14. Physical characterization of functionalized spider silk: electronic and sensing properties

    Directory of Open Access Journals (Sweden)

    Eden Steven, Jin Gyu Park, Anant Paravastu, Elsa Branco Lopes, James S Brooks, Ongi Englander, Theo Siegrist, Papatya Kaner and Rufina G Alamo

    2011-01-01

    Full Text Available This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of ?-sheet (crystalline and amorphous (helical structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 °C, has a strong effect on the morphology of silk bundles (increasing their size, on the process of pyrolization (suppressing mass loss rates and on the resulting carbonized fiber structure (that becomes more robust against bending and strain. The effects of iodine doping and other functional parameters (vacuum and thin film coating motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and ?-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR spectroscopy, revealing a partial transformation of ?-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof-of-concept applications of functionalized spider silk are presented for thermoelectric (Seebeck effects and incandescence in iodine-doped pyrolized silk fibers, and metallic conductivity and flexibility of micron-sized gold-sputtered silk fibers. In the latter case, we demonstrate the application of gold-sputtered neat spider silk to make four-terminal, flexible, ohmic contacts to organic superconductor samples.

  15. Reproducing Natural Spider Silks’ Copolymer Behavior in Synthetic Silk Mimics

    OpenAIRE

    An, Bo; Jenkins, Janelle E.; Sampath, Sujatha; Holland, Gregory P.; Hinman, Mike; Yarger, Jeffery L.; Lewis, Randolph

    2012-01-01

    Dragline silk from orb-weaving spiders is a copolymer of two large proteins, major ampullate spidroin 1 (MaSp1) and 2 (MaSp2). The ratio of these proteins is known to have a large variation across different species of orb-weaving spiders. NMR results from gland material of two different species of spiders, N. clavipes and A. aurantia, indicates that MaSp1 proteins are more easily formed into ?-sheet nanostructures, while MaSp2 proteins form random coil and helical structures. To test if this ...

  16. Silks as scaffolds for skin reconstruction.

    Science.gov (United States)

    Reimers, Kerstin; Liebsch, Christina; Radtke, Christine; Kuhbier, Jörn W; Vogt, Peter M

    2015-11-01

    In this short review, we describe the use of high molecular weight proteins produced in the glands of several arthropods-commonly called silks-for the purpose to enhance human skin wound healing. To this end an extensive literature search has been performed, the publications have been categorized concerning silk preparation and application and summarized accordingly: Scaffolds to promote wound healing were prepared by processing the silks in different ways including solubilization of the protein fibers followed by casting or electrospinning. The silk scaffolds were additionally modified by coating or blending with the intention of further functionalization. In several approaches, the scaffolds were also vitalized with skin cells or stem cells. In vitro and in vivo models were implied to test for safety and efficiency. We conclude that silk scaffolds are characterized by an advantageous biocompatibility as well as an impressive versatility rendering them ideally suited for application in wounds. Nevertheless, further investigation is needed to exploit the full capacity of silk in different wound models and to achieve clinical transfer in time. Biotechnol. Bioeng. 2015;112: 2201-2205. © 2015 Wiley Periodicals, Inc. PMID:25995140

  17. Silk-tropoelastin protein films for nerve guidance.

    Science.gov (United States)

    White, James D; Wang, Siran; Weiss, Anthony S; Kaplan, David L

    2015-03-01

    Peripheral nerve regeneration may be enhanced through the use of biodegradable thin film biomaterials as highly tuned inner nerve conduit liners. Dorsal root ganglion neuron and Schwann cell responses were studied on protein films comprising silk fibroin blended with recombinant human tropoelastin protein. Tropoelastin significantly improved neurite extension and enhanced Schwann cell process length and cell area, while the silk provided a robust biomaterial template. Silk-tropoelastin blends afforded a 2.4-fold increase in neurite extension, when compared to silk films coated with poly-d-lysine. When patterned by drying on grooved polydimethylsiloxane (3.5 ?m groove width, 0.5 ?m groove depth), these protein blends induced both neurite and Schwann cell process alignment. Neurons were functional as assessed using patch-clamping, and displayed action potentials similar to those cultured on poly(lysine)-coated glass. Taken together, silk-tropoelastin films offer useful biomaterial interfacial platforms for nerve cell control, which can be considered for neurite guidance, disease models for neuropathies and surgical peripheral nerve repairs. PMID:25481743

  18. Air Filter Devices Including Nonwoven Meshes of Electrospun Recombinant Spider Silk Proteins

    OpenAIRE

    Lang, Gregor; Jokisch, Stephan; Scheibel, Thomas

    2013-01-01

    Based on the natural sequence of Araneus diadematus Fibroin 4 (ADF4), the recombinant spider silk protein eADF4(C16) has been engineered. This highly repetitive protein has a molecular weight of 48kDa and is soluble in different solvents (hexafluoroisopropanol (HFIP), formic acid and aqueous buffers). eADF4(C16) provides a high potential for various technical applications when processed into morphologies such as films, capsules, particles, hydrogels, coatings, fibers and nonwoven meshes. Due ...

  19. Identification and synthesis of novel biomaterials based on spider structural silk fibers

    Science.gov (United States)

    Hsia, Yang; Gnesa, Eric; Tang, Simon; Jeffery, Felicia; Geurts, Paul; Zhao, Liang; Franz, Andreas; Vierra, Craig

    2011-11-01

    The diversity in function and mechanical behavior of spider silks, and the ability to produce these silks recombinantly, have tremendous potential in creating a new class of biomimetic materials. Here we investigate the structural and mechanical properties of pyriform silks from the golden orb-weaver, Nephila clavipes. Nanoscale indentation measurements using atomic force microscopy on natural pyriform silk suggests that this biomaterial has high toughness that may be suitable for dissipating high amounts of mechanical energy. We also observed the occurrence of highly organized nanocrystals within the pyriform silk fibers that may contribute to the remarkable energy dissipation capability of these silks. It has been demonstrated that poly-(Gly-Ala) and poly-Ala stretches within the internal block repeat modules of dragline silk fibroins form nanocrystals, and these nanocrystalline structures may be responsible for the high extensibility of the dragline silks. In contrast, amino acid sequence analysis shows that PySp2 does not contain the same motifs. In the absence of poly-(Gly-Ala) and poly-Ala repeats, we hypothesized that PySp2 contains new protein motifs sufficient to polymerize into functional structures. To investigate the functional contributions of these novel motifs during pyriform fiber formation, we expressed different recombinant PySp2 fibroins with various segments spanning its block repeat units. We demonstrate that PySp2 recombinant proteins with the Pro-rich sub-block domain (PXP motifs, where X= sub-set of the amino acids A, L, or R) and/or the Ser + Gln + Ala-rich sub-block domain (QQSSVAQS motifs) are sufficient for artificial fiber formation. Moreover, we show that recombinant PySp2 proteins that contain a single block repeat unit can self-assemble into foam-like nanostructures. Collectively, our findings support the use of PySp2 recombinant proteins for a wide range of biomimetic materials with morphologies ranging from fibers to porous structures.

  20. Pulsed laser deposition of silk protein: Effect of photosensitized-ablation on the secondary structure in thin deposited films

    International Nuclear Information System (INIS)

    Silk fibroin is a simple protein expected to have functional applications in medicine and bioelectronics. The primary structure of this protein is quite simple, and the main secondary structures are ?-sheet crystals and amorphous random coils. In the present study, we investigated pulsed laser deposition (PLD) of fibroin with the ?-sheet structures as targets. The primary and secondary structures in films deposited were analyzed using infrared spectroscopy. Normal laser deposition at 351 nm using neat fibroin targets produced thin films of fibroin with a random coiled structure. Ablation was triggered by two-photonic excitation of the peptide chains, which resulted in the destruction of ?-sheet structure in PLD. In order to avoid the two-photonic excitation, we adopted a PLD method utilizing anthracene (5 - 0.1 wt%) in a photosensitized reaction involving doped fibroin targets. Laser light (351 or 355 nm) was absorbed only by anthracene, which plays an important role converting photon energy to thermal energy with great ablation efficiency. Thin fibroin films deposited by this method had both random coil and ?-sheet structures. As the dopant concentration and laser fluence decreased, the ratio of ?-sheet domain to random coil increased in thin deposited films. [copyright] 2001 American Institute of Physics

  1. Spider wrapping silk fibre architecture arising from its modular soluble protein precursor

    OpenAIRE

    Tremblay, Marie-Laurence; Lingling XU; Lefèvre, Thierry; Sarker, Muzaddid; Orrell, Kathleen E.; Leclerc, Jérémie; Meng, Qing; Pézolet, Michel; Auger, Michèle; Liu, Xiang-Qin; Rainey, Jan K.

    2015-01-01

    Spiders store spidroins in their silk glands as high concentration aqueous solutions, spinning these dopes into fibres with outstanding mechanical properties. Aciniform (or wrapping) silk is the toughest spider silk and is devoid of the short amino acid sequence motifs characteristic of the other spidroins. Using solution-state NMR spectroscopy, we demonstrate that the 200 amino acid Argiope trifasciata AcSp1 repeat unit contrasts with previously characterized spidroins, adopting a globular 5...

  2. Water-Insoluble Silk Films with Silk I Structure

    OpenAIRE

    LU, QIANG; Xiao HU; Wang, Xiaoqin; Kluge, Jonathan A; Lu, Shenzhou; Cebe, Peggy; Kaplan, David L.

    2009-01-01

    Water-insoluble regenerated silk materials are normally achieved by increasing ?-sheet content (silk II). In the present study, water-insoluble silk films were prepared by controlling very slow drying of B. mori silk solutions, resulting in the formation of stable films with dominating silk I instead of silk II structure. Wide angle x-ray scattering (WAXS) indicated that the silk films stabilized by slow drying were mainly composed of silk I rather than silk II, while water- and methanol-anne...

  3. Silk Hydrogels of Tunable Structure and Viscoelastic Properties Using Different Chronological Orders of Genipin and Physical Cross-Linking.

    Science.gov (United States)

    Elliott, Winston H; Bonani, Walter; Maniglio, Devid; Motta, Antonella; Tan, Wei; Migliaresi, Claudio

    2015-06-10

    Catering the hydrogel manufacturing process toward defined viscoelastic properties for intended biomedical use is important to hydrogel scaffolding function and cell differentiation. Silk fibroin hydrogels may undergo "physical" cross-linking through ?-sheet crystallization during high pressure carbon dioxide treatment, or covalent "chemical" cross-linking by genipin. We demonstrate here that time-dependent mechanical properties are tunable in silk fibroin hydrogels by altering the chronological order of genipin cross-linking with ?-sheet formation. Genipin cross-linking before ?-sheet formation affects gelation mechanics through increased molecular weight, affecting gel morphology, and decreasing stiffness response. Alternately, genipin cross-linking after gelation anchored amorphous regions of the protein chain, and increasing stiffness. These differences are highlighted and validated through large amplitude oscillatory strain near physiologic levels, after incorporation of material characterization at molecular and micron length scales. PMID:25978549

  4. Integration of silk protein in organic and light-emitting transistors.

    Science.gov (United States)

    Capelli, R; Amsden, J J; Generali, G; Toffanin, S; Benfenati, V; Muccini, M; Kaplan, D L; Omenetto, F G; Zamboni, R

    2011-07-01

    We present the integration of a natural protein into electronic and optoelectronic devices by using silk fibroin as a thin film dielectric in an organic thin film field-effect transistor (OFET) ad an organic light emitting transistor device (OLET) structures. Both n- (perylene) and p-type (thiophene) silk-based OFETs are demonstrated. The measured electrical characteristics are in agreement with high-efficiency standard organic transistors, namely charge mobility of the order of 10(-2) cm(2)/Vs and on/off ratio of 10(4). The silk-based optolectronic element is an advanced unipolar n-type OLET that yields a light emission of 100nW. PMID:22899899

  5. Preparation, characterization and biological test of 3D-scaffolds based on chitosan, fibroin and hydroxyapatite for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Paulo Autran Leite; Resende, Cristiane Xavier [Departamento de Ciências de Materiais, Universidade Federal de Sergipe, Av. Marechal Rondon, s/n. Jardim Rosa Elze, São Cristóvão, Sergipe CEP 49000-100 (Brazil); Dulce de Almeida Soares, Glória [Departamento de Ciências de Materiais, Universidade Federal do Rio de Janeiro, Av. Brigadeiro Trompowisk, s/n. Ilha do Fundão, Rio de Janeiro, Rio de Janeiro CEP 21900-000 (Brazil); Anselme, Karine [Institut de Science des Matériaux de Mulhouse (IS2M), CNRS LRC7228, 15, Jean Starcky Street, BP 2488, 68054 Mulhouse cedex (France); Almeida, Luís Eduardo, E-mail: lealmeida2009@gmail.com [Departamento de Ciências de Materiais, Universidade Federal de Sergipe, Av. Marechal Rondon, s/n. Jardim Rosa Elze, São Cristóvão, Sergipe CEP 49000-100 (Brazil)

    2013-08-01

    This work describes the preparation and characterization of porous 3D-scaffolds based on chitosan (CHI), chitosan/silk fibroin (CHI/SF) and chitosan/silk fibroin/hydroxyapatite (CHI/SF/HA) by freeze drying. The biomaterials were characterized by X-ray diffraction, attenuated total reflection Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy and energy dispersive spectroscopy. In addition, studies of porosity, pore size, contact angle and biological response of SaOs-2osteoblastic cells were performed. The CHI scaffolds have a porosity of 94.2 ± 0.9%, which is statistically higher than the one presented by CHI/SF/HA scaffolds, 89.7 ± 2.6%. Although all scaffolds were able to promote adhesion, growth and maintenance of osteogenic differentiation of SaOs-2 cells, the new 3D-scaffold based on CHI/SF/HA showed a significantly higher cell growth at 7 days and 21 days and the level of alkaline phosphatase at 14 and 21 days was statistically superior compared to other tested materials. - Highlights: • Preparation of 3D-scaffolds based on CHI, with or without addition of SF and HA. • Scaffolds exhibited interconnected porous structure (pore size superior to 50 ?m). • The tripolyphosphate did not induce any significant cytotoxic response. • The CHI/SF/HA composite showed a higher cell growth and ALP activity.

  6. Towards Silk Fiber Optics: Refractive Index Characterization, Fiber Spinning, and Spinneret Analysis

    Science.gov (United States)

    Spitzberg, Joshua David

    Of the many biologically derived materials, whose historical record of use by humans underscores an ex-vivo utility, silk is interesting for it's contemporary repurposing from textile to biocompatible substrate. And while even within this category silk is one of several materials studied for novel repurposing, it has the unique character of being evolutionarily developed specifically for fiber spinning in vivo. The work discussed here is inspired by taking what nature has given, to explore the in vitro spinning of silk towards biocompatible fiber optics applications. A common formulation of silk used in biomedical studies for re-forming it into the various structures begins with the silkworm cocoon, which is degummed and dissolved into an aqueous solution of its miscible protein, fibroin, and post-treated to fabricate solid structures. In the first aim, the optical refractive index (RI) of various post-treatment methods is discussed towards determining RI design techniques. The methods considered in this work for re-forming a solid fiber from the reconstituted silk fibroin (RSF) solution borrow from the industrial techniques of gel spinning, and dry-spinning. In the second aim, methods are applied to RSF and quality of the spun fibers discussed. A feature common to spinning techniques is passing the (silk) material through a spinneret of specific shape. In the third aim, fluid flow through a simplified native silkworm spinneret is modeled towards bio-inspired lessons in design. In chapter 1 the history, reconstitution, are discussed towards understanding the fabrication of several optical device examples. Chapter 2 then prefaces the experiments and measurements in fiber optics by reviewing electromagnetic theory of waveguide function, and loss factors, to be considered in actual device fabrication. Chapter 3 presents results and discussion for the first aim, understanding design principles for the refractive index of RSF. From this point, industrial fiber-spinning approaches are reviewed from a theoretical and methodological perspective in chapter 4. Thus, chapter 5 presents results for the second aim, efforts to apply these techniques using RSF. Chapter 6 discusses the third aim, understanding the design of the silkworm spinneret by an idealized model of natural and reconstituted silk fibroin flow. While the ultimate goal of a structurally and optically smooth and uniform fiber remains elusive, this work serves as a guide for future efforts.

  7. Microscopic structural analysis of fractured silk fibers from Bombyx mori and Samia cynthia ricini using 13C CP/MAS NMR with a 1 mm microcoil MAS NMR probehead

    KAUST Repository

    Yamauchi, Kazuo

    2010-07-01

    Conformational changes have been studied in silk fibers from the domestic silkworm Bombyx mori and a wild silkworm Samia cynthia ricini as a result of fractured by stretching. About 300 samples consisting of only the fractured regions of [1-13C]Ala or [1-13C]Gly labeled silk fibers were collected and observed by 13C CP/MAS NMR spectra. The total amount of these fractured fibers is only about 1 mg and therefore we used a home-built 1 mm microcoil MAS NMR probehead. A very small increase in the fraction of random coil was noted for the alanine regions of both silk fibroins and for the glycine region of B. mori silk fibroin. However, there is no difference in the spectra before and after fractured for the glycine region of S. c. ricini silk fibroin. Thus, the influence of fracture occurs exclusively at the Ala region for S. c. ricini. The relationship between sequence, fracture and structure is discussed. © 2010 Elsevier Inc. All rights reserved.

  8. Ultrastructure of the Lyonet's glands in larvae of Diatraea saccharalis Fabricius (Lepidoptera: Pyralidae)

    OpenAIRE

    Eliane Victoriano; Elisa A Gregório

    2004-01-01

    The Lyonet's gland is found in Lepidoptera larvae, close to the excretory duct of the silk gland. The role played by this gland is still uncertain. This work aims to describe the ultrastructure of the Lyonet's gland in Diatraea saccharalis larvae, offering suggestions regarding its possible function. The insects were reared under laboratory-controlled conditions. The glands were conventionally prepared for transmission (TEM) and scanning (SEM) electron microscopy. SEM showed that Lyonet's gla...

  9. Art on Silk Hoops

    Science.gov (United States)

    Padrick, Deborah

    2012-01-01

    Painting on silk has a magic all its own. Versions of painting on silk can be found throughout the world from Japan and Europe to the United States. Themes for the paintings can be most any type of design or imagery. Applying the liquid dyes is exciting, as the vivid liquid colors flow and blend into the fabric. The process captures students'…

  10. Silk Batik using Cochineal Dye

    Science.gov (United States)

    The history of silk, including sericulture (the production of raw silk, which requires the raising of silkworms on their natural diet, mulberry leaves) and silk manufacturing, is rich and extensive. It encompasses several famous “silk roads” (trade routes), various cultures and technologies, ideas,...

  11. A microfluidic cell for studying the formation of regenerated silk by synchrotron radiation small- and wide-angle X-ray scattering

    OpenAIRE

    Martel, Anne; Burghammer, Manfred; Davies, Richard; DiCola, Emanuela; Panine, Pierre; Salmon, Jean-Baptiste; Riekel, Christian

    2008-01-01

    A tube-in-square-pipe microfluidic glass cell has been developed for studying the aggregation and fiber formation from regenerated silk solution by in-situ small-angle X-ray scattering using synchrotron radiation. Acidification-induced aggregation has been observed close to the mixing point of the fibroin and buffer solution. The fibrous, amorphous material is collected in a water bath. Micro-wide-angle X-ray scattering of the dried material confirms its ?-sheet nature.

  12. [Engineered spider silk: the intelligent biomaterial of the future. Part II].

    Science.gov (United States)

    Ka?mierska, Katarzyna; Florczak, Anna; Pieko?, Konrad; Mackiewicz, Andrzej; Dams-Koz?owska, Hanna

    2011-01-01

    The development and progress in engineered spider silk manufacturing has enabled its practical application. Recombinant spider silk can assemble in several morphological forms such as films, hydrogels, fibers, scaffolds, microcapsules, and micro- and nanospheres. The in vitro fiber formation takes place by mimicking the natural spinning process in the spider spinning gland: in the presence of phosphate ions and dragging forces. Films are obtained by evaporation of solvent from the silk solution, while the result of evaporation of the solvent in the presence of porogens is a silk scaffold. Hydrogels are formed by spontaneous polymerization of silk particles in solutions at low pH. The silk film assembled at the interface of two immiscible phases forms microcapsules. The smallest of the described forms--silk spheres--are obtained by salting out the silk protein solution after addition of the phosphate ions. Common properties of the silk biomaterials are biocompatibility and biodegradability, which make them suitable for a number of applications in medicine and pharmacy. Moreover, the strategy of hybrid proteins which provides the desired function to biomaterial will further expand their potential use. PMID:21734323

  13. Silk as a potential candidate for bone tissue engineering.

    Science.gov (United States)

    Mottaghitalab, Fatemeh; Hosseinkhani, Hossein; Shokrgozar, Mohammad Ali; Mao, Chuanbin; Yang, Mingying; Farokhi, Mehdi

    2015-10-10

    Regeneration of large bone defects is challenging in the next few years because the age of the population is growing. Bone grafting as a gold standard of bone repairing is limited as a result of many disadvantages. In recent years, many novel materials and processing methods have been introduced to construct the native bone extracellular matrix (ECM) and restore the functions of degenerated bone. Silk fibroin (SF) as a natural polymer, has established a good reputation for bone tissue engineering applications due to its many unique properties, including exceptional biocompatibility, biodegradability, mechanical behavior, and ease of processability. In this review, recent advances in the design and application of SF-based scaffolds for bone regeneration are discussed. PMID:26254197

  14. Silk and PEG as means to stiffen a parylene probe for insertion in the brain: toward a double time-scale tool for local drug delivery

    Science.gov (United States)

    Lecomte, A.; Castagnola, V.; Descamps, E.; Dahan, L.; Blatché, M. C.; Dinis, T. M.; Leclerc, E.; Egles, C.; Bergaud, C.

    2015-12-01

    The use of soft materials as substrate for neural probes aims at achieving better compliance with the surrounding neurons while maintaining minimal rejection. Many strategies have emerged to enable such probes to penetrate the cortex, among which the use of resorbable polymers. We performed several tests involving two resorbable polymers considered most promising: polyethylene glycol (PEG) and silk fibroin (SF) from Bombyx Mori silkworms. Our coating method provides a repeatable, uniform structure optimized for a stress-reduced insertion of a parylene-C neural probe. Standard compression tests as well as in vitro and in vivo insertion assessments show that both SF and PEG-coated probes are stiff enough to avoid the buckling effect during insertion in the cortex. However, with a buckling force of 300 mN and a mechanical holding in vitro of tens of minutes, we assess silk fibroin to be more reliable for practical handling. In vivo first try-outs in mouse brain showed neither buckling issues of the probe nor undesired alteration of the signal recording. Moreover, we evidenced two distinct time scales in the bioresorption of our polymer coatings: silk fibroin degrades itself in a matter of weeks and PEG dissolves itself within seconds in the presence of water. We then present a hybrid PEG and SF coating that could be used as a drug delivery system with different time scales to reduce both the acute and the chronic body reaction.

  15. Untangling spider silk evolution with spidroin terminal domains

    Directory of Open Access Journals (Sweden)

    Garb Jessica E

    2010-08-01

    Full Text Available Abstract Background Spidroins are a unique family of large, structural proteins that make up the bulk of spider silk fibers. Due to the highly variable nature of their repetitive sequences, spidroin evolutionary relationships have principally been determined from their non-repetitive carboxy (C-terminal domains, though they offer limited character data. The few known spidroin amino (N-terminal domains have been difficult to obtain, but potentially contain critical phylogenetic information for reconstructing the diversification of spider silks. Here we used silk gland expression data (ESTs from highly divergent species to evaluate the functional significance and phylogenetic utility of spidroin N-terminal domains. Results We report 11 additional spidroin N-termini found by sequencing ~1,900 silk gland cDNAs from nine spider species that shared a common ancestor > 240 million years ago. In contrast to their hyper-variable repetitive regions, spidroin N-terminal domains have retained striking similarities in sequence identity, predicted secondary structure, and hydrophobicity. Through separate and combined phylogenetic analyses of N-terminal domains and their corresponding C-termini, we find that combined analysis produces the most resolved trees and that N-termini contribute more support and less conflict than the C-termini. These analyses show that paralogs largely group by silk gland type, except for the major ampullate spidroins. Moreover, spidroin structural motifs associated with superior tensile strength arose early in the history of this gene family, whereas a motif conferring greater extensibility convergently evolved in two distantly related paralogs. Conclusions A non-repetitive N-terminal domain appears to be a universal attribute of spidroin proteins, likely retained from the origin of spider silk production. Since this time, spidroin N-termini have maintained several features, consistent with this domain playing a key role in silk assembly. Phylogenetic analyses of the conserved N- and C-terminal domains illustrate dramatic radiation of the spidroin gene family, involving extensive duplications, shifts in expression patterns and extreme diversification of repetitive structural sequences that endow spider silks with an unparalleled range of mechanical properties.

  16. Bioengineered silk scaffolds in 3D tissue modeling with focus on mammary tissues.

    Science.gov (United States)

    Maghdouri-White, Yas; Bowlin, Gary L; Lemmon, Christopher A; Dréau, Didier

    2016-02-01

    In vitro generation of three-dimensional (3D) biological tissues and organ-like structures is a promising strategy to study and closely model complex aspects of the molecular, cellular, and physiological interactions of tissue. In particular, in vitro 3D tissue modeling holds promises to further our understanding of breast development. Indeed, biologically relevant 3D structures that combine mammary cells and engineered matrices have improved our knowledge of mammary tissue growth, organization, and differentiation. Several polymeric biomaterials have been used as scaffolds to engineer 3D mammary tissues. Among those, silk fibroin-based biomaterials have many biologically relevant properties and have been successfully used in multiple medical applications. Here, we review the recent advances in engineered scaffolds with an emphasis on breast-like tissue generation and the benefits of modified silk-based scaffolds. PMID:26652473

  17. Novel fabrication of fluorescent silk utilized in biotechnological and medical applications.

    Science.gov (United States)

    Kim, Dong Wook; Lee, Ok Joo; Kim, Seong-Wan; Ki, Chang Seok; Chao, Janet Ren; Yoo, Hyojong; Yoon, Sung-Il; Lee, Jeong Eun; Park, Ye Ri; Kweon, HaeYong; Lee, Kwang Gill; Kaplan, David L; Park, Chan Hum

    2015-11-01

    Silk fibroin (SF) is a natural polymer widely used and studied for diverse applications in the biomedical field. Recently, genetically modified silks, particularly fluorescent SF fibers, were reported to have been produced from transgenic silkworms. However, they are currently limited to textile manufacturing. To expand the use of transgenic silkworms for biomedical applications, a solution form of fluorescent SF needed to be developed. Here, we describe a novel method of preparing a fluorescent SF solution and demonstrate long-term fluorescent function up to one year after subcutaneous insertion. We also show that fluorescent SF labeled p53 antibodies clearly identify HeLa cells, indicating the applicability of fluorescent SF to cancer detection and bio-imaging. Furthermore, we demonstrate the intraoperative use of fluorescent SF in an animal model to detect a small esophageal perforation (0.5 mm). This study suggests how fluorescent SF biomaterials can be applied in biotechnology and clinical medicine. PMID:26298522

  18. Protein gradient films of fibroin and gelatine.

    Science.gov (United States)

    Claussen, Kai U; Lintz, Eileen S; Giesa, Reiner; Schmidt, Hans-Werner; Scheibel, Thomas

    2013-10-01

    Gradients are a natural design principle in biological systems that are used to diminish stress concentration where materials of differing mechanical properties connect. An interesting example of a natural gradient material is byssus, which anchors mussels to rocks and other hard substrata. Building upon previous work with synthetic polymers and inspired by byssal threads, protein gradient films are cast using glycerine-plasticized gelatine and fibroin exhibiting a highly reproducible and smooth mechanical gradient, which encompasses a large range of modulus from 160 to 550?MPa. The reproducible production of biocompatible gradient films represents a first step towards medical applications. PMID:23894133

  19. Silk composition in Lepidoptera.

    Czech Academy of Sciences Publication Activity Database

    Sehnal, František; Žurovec, Michal

    Londrina : Embrapa Soja , 2000. s. 864. [International Congress of Entomology /21./. 20.08.2000-26.08.2000, Foz do Iguassu] R&D Projects: GA ?R GA204/00/0019 Institutional research plan: CEZ:AV0Z5007907 Keywords : lepidopteran silk Subject RIV: EB - Genetics ; Molecular Biology

  20. Biotechnologies based on silk.

    Czech Academy of Sciences Publication Activity Database

    Sehnal, František

    Heidelberg : Springer, 2011 - (Vilcinskas, A.), s. 211-224 ISBN 978-90-481-9640-1 R&D Projects: GA ?R GAP502/10/2382 Institutional research plan: CEZ:AV0Z50070508 Keywords : silk Subject RIV: ED - Physiology

  1. Structure, composition and mechanical properties of the silk fibres of the egg case of the Joro spider, Nephila clavata (Araneae, Nephilidae)

    Indian Academy of Sciences (India)

    Ping Jiang; Cong Guo; Taiyong Lv; Yonghong Xiao; Xinjun Liao; Bing Zhou

    2011-12-01

    The silk egg case and orb web of spiders are elaborate structures that are assembled from a number of components. We analysed the structure, the amino acid and fibre compositions, and the tensile properties of the silk fibres of the egg case of Nephila clavata. SEM shows that the outer and inner covers of the egg case consist of thick, medium and thin silk fibres. The silk fibres of the outer cover of the egg case are probably produced by the major and minor ampullate glands. The silk fibres of the inner cover of the egg case from cylindrical glands appears to be distinct from the silk fibres of the major ampullate glands based on their micro-morphology, mole percent amino acid composition and types, and tensile behaviour and properties. Collectively, our investigations show that N. clavata uses silk fibres from relatively few glands in varying combinations to achieve different physical and chemical properties (e.g., color, diameter, morphology and amino acid composition) and functional and mechanical properties in the different layers of the egg case.

  2. Review the role of terminal domains during storage and assembly of spider silk proteins.

    Science.gov (United States)

    Eisoldt, Lukas; Thamm, Christopher; Scheibel, Thomas

    2012-06-01

    Fibrous proteins in nature fulfill a wide variety of functions in different structures ranging from cellular scaffolds to very resilient structures like tendons and even extra-corporal fibers such as silks in spider webs or silkworm cocoons. Despite their different origins and sequence varieties many of these fibrous proteins share a common building principle: they consist of a large repetitive core domain flanked by relatively small non-repetitive terminal domains. Amongst protein fibers, spider dragline silk shows prominent mechanical properties that exceed those of man-made fibers like Kevlar. Spider silk fibers assemble in a spinning process allowing the transformation from an aqueous solution into a solid fiber within milliseconds. Here, we highlight the role of the non-repetitive terminal domains of spider dragline silk proteins during storage in the gland and initiation of the fiber assembly process. PMID:22057429

  3. Chemical assembly of TiO2 and TiO2@Ag nanoparticles on silk fiber to produce multifunctional fabrics.

    Science.gov (United States)

    Li, Guohong; Liu, Hong; Zhao, Hongshi; Gao, Yuqiang; Wang, Jiyang; Jiang, Huaidong; Boughton, R I

    2011-06-01

    A carefully designed surface modification technique for the manufacture of multifunctional silk textile nanocomposite materials is successfully developed by the functionalization of silk with TiO(2) and TiO(2)@Ag nanoparticles (NPs). The NPs are assembled onto a silk substrate through covalent linkages, including enediol ligand-metal oxide bonding, resin dehydration and the acylation of silk. Owing to the strong chemical bonding, silk fibroin fabric (SFF) and the NPs form a stable composite system. The functionalized SFF, especially TiO(2)@Ag NP-functionalized SFF are endowed with remarkable UV protection properties, and an efficient anti-bacterial capability toward Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Furthermore, the nearly total photodegradation of methylene orange (MO) under UV illumination illustrates that functionalized SFF possesses high photocatalytic and self-cleaning capability. This multifunctional silk material satisfies the market demand for natural "smart" products, and is a promising practical material for use in the textile industry, hospital sterilization and environmental cleanup. PMID:21419419

  4. Nutritional value of silk powder from irradiated silk waste

    International Nuclear Information System (INIS)

    Silk waste from Thai reeling factory was developed into purified silk protein. Cleanliness of silk filaments by boiling in water was firstly needed. After air drying, they were irradiated with Gamma ray using Cobalt-60 at doses of 750 and 1,000 kGy, then the irradiated silk filaments were dissolved in calcium chloride-ethanol-water solution. The next steps would be dialysis followed by freezed dried process to obtain irradiated silk powder. Two samples of 750 and 1,000 kGy irradiated silk powder were analyzed for nutritional components compared with non irradiated silk filaments. It was found that, the fat content in two irradiated samples was distinctive lower than the non irradiated one, however the protein content was nearly the same in three samples. In addition the moisture content in two irradiated samples was distinctive higher than the non irradiated one. These results show that irradiation technique is useful for development of valuable silk protein as biomaterial. (author)

  5. Molecular spring: from spider silk to silkworm silk

    CERN Document Server

    Wu, Xiang; Du, Ning; Xu, Gang-Qin; Li, Bao-Wen

    2009-01-01

    In this letter, we adopt a new approach combining theoretical modeling with silk stretching measurements to explore the mystery of the structures between silkworm and spider silks, leading to the differences in mechanical response against stretching. Hereby the typical stress-strain profiles are reproduced by implementing the newly discovered and verified "$\\beta$-sheet splitting" mechanism, which primarily varies the secondary structure of protein macromolecules; our modeling and simulation results show good accordance with the experimental measurements. Hence, it can be concluded that the post-yielding mechanical behaviors of both kinds of silks are resulted from the splitting of crystallines while the high extensibility of spider dragline is attributed to the tiny $\\beta$-sheets solely existed in spider silk fibrils. This research reveals for the first time the structural factors leading to the significant difference between spider and silkworm silks in mechanical response to the stretching force. Addition...

  6. Effect of Pretreatment on Fabrication of Natural FibroinFiber/Apatite Composites Using Alternate Soaking Method

    Directory of Open Access Journals (Sweden)

    LI Zhi-Hong, WU Ji-Min, HUANG Shu-Jie, GUAN Jing, ZHANGXi-Zheng

    2010-07-01

    Full Text Available To develop biomimetic fibroin/apatite composites with bone―like structure byalternate soaking method, the degummed natural fibroin fibers were pretreatedby soaking into CaCl2:EtOH:H2O (<>n(CaCl2):<>n(EtOH):<>n(H2O)=1:2:8) solution for given time and then soaked into calciumsolution and phosphate solution, respectively, to fabricate fibroin/apatite composites. The effects of pretreatment time andthe alternate soaking times on fibroin microstructure and fibroin/apatitecomposites were examined by SEM, FTIR, XRD and TGA techniques. The pretreatmentusing CaCl2:EtOH:H2O(<>n(CaCl2):<>n(EtOH):<>n(H2O)=1:2:8) solution makes fibroin fiber exhibit rougher surface and higher internalporosity, which is beneficial to interaction of calcium ion and residue groupssuch as ―COOH, –OHand ―CONH― from fibroin, and then improvethe deposition of apatite on fibroin fibers. The homogeneous apatites withoriented <>c―axis were formed on the pretreated fibroin fibers. Moreover,there are more than 30wt% apatites deposited on fibroin fibers after alternatesoaking for more than 3 times. The fibroin/apatite composite has potential tobe applied as bone repair materials.

  7. The performance of silk scaffolds in a rat model of augmentation cystoplasty.

    Science.gov (United States)

    Seth, Abhishek; Chung, Yeun Goo; Gil, Eun Seok; Tu, Duong; Franck, Debra; Di Vizio, Dolores; Adam, Rosalyn M; Kaplan, David L; Estrada, Carlos R; Mauney, Joshua R

    2013-07-01

    The diverse processing plasticity of silk-based biomaterials offers a versatile platform for understanding the impact of structural and mechanical matrix properties on bladder regenerative processes. Three distinct groups of 3-D matrices were fabricated from aqueous solutions of Bombyx mori silk fibroin either by a gel spinning technique (GS1 and GS2 groups) or a solvent-casting/salt-leaching method in combination with silk film casting (FF group). SEM analyses revealed that GS1 matrices consisted of smooth, compact multi-laminates of parallel-oriented silk fibers while GS2 scaffolds were composed of porous (pore size range, 5-50 ?m) lamellar-like sheets buttressed by a dense outer layer. Bi-layer FF scaffolds were comprised of porous foams (pore size, ~400 ?m) fused on their external face with a homogenous, nonporous silk film. Silk groups and small intestinal submucosa (SIS) matrices were evaluated in a rat model of augmentation cystoplasty for 10 weeks of implantation and compared to cystotomy controls. Gross tissue evaluations revealed the presence of intra-luminal stones in all experimental groups. The incidence and size of urinary calculi was the highest in animals implanted with gel spun silk matrices and SIS with frequencies ?57% and stone diameters of 3-4 mm. In contrast, rats augmented with FF scaffolds displayed substantially lower rates (20%) and stone size (2 mm), similar to the levels observed in controls (13%, 2 mm). Histological (hematoxylin and eosin, Masson's trichrome) and immunohistochemical (IHC) analyses showed comparable extents of smooth muscle regeneration and contractile protein (?-smooth muscle actin and SM22?) expression within defect sites supported by all matrix groups similar to controls. Parallel evaluations demonstrated the formation of a transitional, multi-layered urothelium with prominent uroplakin and p63 protein expression in all experimental groups. De novo innervation and vascularization processes were evident in all regenerated tissues indicated by Fox3-positive neuronal cells and vessels lined with CD31 expressing endothelial cells. In comparison to other biomaterial groups, cystometric analyses at 10 weeks post-op revealed that animals implanted with the FF matrix configuration displayed superior urodynamic characteristics including compliance, functional capacity, as well as spontaneous non voiding contractions consistent with control levels. Our data demonstrate that variations in scaffold processing techniques can influence the in vivo functional performance of silk matrices in bladder reconstructive procedures. PMID:23545287

  8. Regeneration of Bombyx mori silk nanofibers and nanocomposite fibrils by the electrospinning process

    Science.gov (United States)

    Ayutsede, Jonathan Eyitouyo

    In recent years, there has been significant interest in the utilization of natural materials for novel nanoproducts such as tissue engineered scaffolds. Silkworm silk fibers represent one of the strongest natural fibers known. Silkworm silk, a protein-based natural biopolymer, has received renewed interest in recent years due to its unique properties (strength, toughness) and potential applications such as smart textiles, protective clothing and tissue engineering. The traditional 10--20 mum diameter, triangular-shaped Bombyx mori fibers have remained unchanged over the years. However, in our study, we examine the scientific implication and potential applications of reducing the diameter to the nanoscale, changing the triangular shape of the fiber and adding nanofillers in the form of single wall carbon nanotubes (SWNT) by the electrospinning process. The electrospinning process preserves the natural conformation of the silk (random and beta-sheet). The feasibility of changing the properties of the electrospun nanofibers by post processing treatments (annealing and chemical treatment) was investigated. B. mori silk fibroin solution (formic acid) was successfully electrospun to produce uniform nanofibers (as small as 12 nm). Response Surface Methodology (RSM) was applied for the first time to experimental results of electrospinning, to develop a processing window that can reproduce regenerated silk nanofibers of a predictable size (d < 100nm). SWNT-silk multifunctional nanocomposite fibers were fabricated for the first time with anticipated properties (mechanical, thermal and electrically conductive) that may have scientific applications (nerve regeneration, stimulation of cell-scaffold interaction). In order to realize these applications, the following areas need to be addressed: a systematic investigation of the dispersion of the nanotubes in the silk matrix, a determination of new methodologies for characterizing the nanofiber properties and establishing the nature of the silk-SWNT interactions. A new visualization system was developed to characterize the transport properties of the nanofibrous assemblies. The morphological, chemical, structural and mechanical properties of the nanofibers were determined by field emission environmental scanning microscopy, Fourier transform infrared and Raman spectroscopy, wide angle x-ray diffraction and microtensile tester respectively.

  9. Tailoring the properties and functions of phosphate/silk/Ag/chitosan scaffolds.

    Science.gov (United States)

    Abdel-Fattah, Wafa I; Sallam, Abdel Sattar M; Diab, A M; Ali, Ghareib W

    2015-09-01

    Two novel silk composites of phosphatic phases with nanosilver/chitosan having enhanced biocompatibility were achieved. Hydroxyapatite and octa calcium phosphates were synthesized in situ within silk fibroin/chitosan/nanosilver composites recently studied. Thermo-gravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) verified their thermal behavior. The structural aspects were characterized applying X-ray diffraction analysis (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM) with EDAX. Additionally X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared spectroscopy (FTIR) were applied. Mercury porosimeter was used to verify the pore size distribution. The in vitro degradation was followed in D-MEM for 48 h in a cumulative manner for five successive periods. Biochemical analyses of Ca, P and total protein using relevant chemical kits and atomic absorption for silver were performed. ANOVA statistics was carried out. Phosphatic crystalline phases along with the presence of silk, chitosan and nano-silver were developed. The diameters of hydroxyapatite and octa calcium phosphate particles were ~8-17 nm and 15-22 nm respectively. Comparatively higher degradation of Octa composite possessing higher porosity proved in turn more osteoinduction with in situ apatitic development. PMID:26046279

  10. Recombinant DNA production of spider silk proteins.

    Science.gov (United States)

    Tokareva, Olena; Michalczechen-Lacerda, Valquíria A; Rech, Elíbio L; Kaplan, David L

    2013-11-01

    Spider dragline silk is considered to be the toughest biopolymer on Earth due to an extraordinary combination of strength and elasticity. Moreover, silks are biocompatible and biodegradable protein-based materials. Recent advances in genetic engineering make it possible to produce recombinant silks in heterologous hosts, opening up opportunities for large-scale production of recombinant silks for various biomedical and material science applications. We review the current strategies to produce recombinant spider silks. PMID:24119078

  11. Exploiting spiders’ silk

    Directory of Open Access Journals (Sweden)

    Paula Gould

    2002-12-01

    As today’s film-goers and readers of the original Spiderman comic strip will know, spider silk makes an ideal tool for a modern day super-hero. The fine line can be produced at will, holds our hero’s weight as he swings between tall buildings, and then clumps together to trap dastardly villains in a tangled, sticky mess. Highly useful if your daily job description includes rescuing distressed damsels from improbable locations and preventing a thoroughly nasty goblin from wreaking havoc on your home city.

  12. Electron transport and bulk-like behavior of Wiedemann-Franz law for sub-7 nm-thin iridium films on silkworm silk.

    Science.gov (United States)

    Lin, Huan; Xu, Shen; Zhang, Yu-Qing; Wang, Xinwei

    2014-07-23

    For ultrathin metallic films, either supported or free-standing, the inside nanocrystalline nature significantly reduces the electron and thermal transport. Quantum mechanical reflection of electrons at the grain boundary reduces the electrical conductivity further than the thermal conductivity, leading to a Lorenz number in the order of 7.0 × 10(-8) W ? K(-2), much higher than that of the bulk counterpart. We report on a finding that for ultrathin (0.6-6.3 nm) iridium films coated on degummed silkworm silk fibroin, the electron transport is around 100-200% higher than that of the same film on glass fiber, even though the grain size of Ir film on silkworm silk is smaller than that on glass fiber. At the same time, the thermal conductivity of the Ir film is smaller or close to that of the film on glass fiber. Its Lorenz number is found close to that of bulk crystalline Ir despite the nanocrystalline structure in the Ir films. This is similar to the behavior of metallic glasses. Our study of gold films on silkworm silk reveals the same trend of change as compared to that on glass fiber. Electron hopping and tunneling in silkworm silk is speculated to be responsible for the observed electron transport. The finding points out that silk could provide a better substrate for flexible electronics with significantly faster electron transport. PMID:24988039

  13. Biomineralization of stable and monodisperse vaterite microspheres using silk nanoparticles.

    Science.gov (United States)

    Liu, Lijie; Zhang, Xiuli; Liu, Xi; Liu, Jing; Lu, Guozhong; Kaplan, David L; Zhu, Hesun; Lu, Qiang

    2015-01-28

    The influence of silk fibroin (SF) on calcium carbonate (CaCO3) biomineralization has been investigated; however, the formation of small, uniform SF-regulated vaterite microspheres has not been reported. In this work, spherical CaCO3 was synthesized via coprecipitation in the presence of SF. SF nanostructures were first tuned by self-assembly at 60 °C to provide better control of the nucleation of CaCO3. Subsequently, monodisperse vaterite microspheres about 1.1 ?m were generated by controlling aggregation and growth of CaCO3 under appropriate concentrations of SF and Ca ions. In contrast to unstable vaterite, the microspheres generated in the present study have sufficient stability in aqueous solution for at least 8 days without transformation into calcite, due to the electrostatic interactions between the Ca ions and the preassembled SF nanostructures. The microspheres as drug carriers of doxorubicin (DOX) were assessed and found to have good encapsulation efficiency, sustained drug release without burst release, and pH sensitivity. These new SF/CaCO3 hybrids may provide new options for various biomedical applications. PMID:25578091

  14. TUMORS OF SALIVARY GLANDS

    OpenAIRE

    Gaurav Solanki

    2012-01-01

    The glands are divided into major and minor salivary gland categories. The major salivary glands are the parotid, the submandibular, and the sublingual glands. The minor glands are dispersed throughout the upper aerodigestive submucosa. Salivary gland tumors are abnormal cells growing in the ducts that drain the salivary glands. Salivary glands tumors are uncommon and are subdivided into benign neoplasms, tumor-like conditions, and malignant neoplasms. They can be removed surgically or one ca...

  15. Air filter devices including nonwoven meshes of electrospun recombinant spider silk proteins.

    Science.gov (United States)

    Lang, Gregor; Jokisch, Stephan; Scheibel, Thomas

    2013-01-01

    Based on the natural sequence of Araneus diadematus Fibroin 4 (ADF4), the recombinant spider silk protein eADF4(C16) has been engineered. This highly repetitive protein has a molecular weight of 48kDa and is soluble in different solvents (hexafluoroisopropanol (HFIP), formic acid and aqueous buffers). eADF4(C16) provides a high potential for various technical applications when processed into morphologies such as films, capsules, particles, hydrogels, coatings, fibers and nonwoven meshes. Due to their chemical stability and controlled morphology, the latter can be used to improve filter materials. In this protocol, we present a procedure to enhance the efficiency of different air filter devices, by deposition of nonwoven meshes of electrospun recombinant spider silk proteins. Electrospinning of eADF4(C16) dissolved in HFIP results in smooth fibers. Variation of the protein concentration (5-25% w/v) results in different fiber diameters (80-1,100 nm) and thus pore sizes of the nonwoven mesh. Post-treatment of eADF4(C16) electrospun from HFIP is necessary since the protein displays a predominantly ?-helical secondary structure in freshly spun fibers, and therefore the fibers are water soluble. Subsequent treatment with ethanol vapor induces formation of water resistant, stable ?-sheet structures, preserving the morphology of the silk fibers and meshes. Secondary structure analysis was performed using Fourier transform infrared spectroscopy (FTIR) and subsequent Fourier self-deconvolution (FSD). The primary goal was to improve the filter efficiency of existing filter substrates by adding silk nonwoven layers on top. To evaluate the influence of electrospinning duration and thus nonwoven layer thickness on the filter efficiency, we performed air permeability tests in combination with particle deposition measurements. The experiments were carried out according to standard protocols. PMID:23685883

  16. Recombinant DNA production of spider silk proteins

    OpenAIRE

    Tokareva, Olena; Michalczechen-Lacerda, Valquíria A; Rech, Elíbio L; Kaplan, David L.

    2013-01-01

    Spider dragline silk is considered to be the toughest biopolymer on Earth due to an extraordinary combination of strength and elasticity. Moreover, silks are biocompatible and biodegradable protein-based materials. Recent advances in genetic engineering make it possible to produce recombinant silks in heterologous hosts, opening up opportunities for large-scale production of recombinant silks for various biomedical and material science applications. We review the current strategies to produce...

  17. A novel approach to fabricate silk nanofibers containing hydroxyapatite nanoparticles using a three-way stopcock connector

    Science.gov (United States)

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

    2013-07-01

    Electrospinning technique is commonly used to produce micro- and/or nanofibers, which utilizes electrical forces to produce polymeric fibers with diameters ranging from several micrometers down to few nanometers. Desirably, electrospun materials provide highly porous structure and appropriate pore size for initial cell attachment and proliferation and thereby enable the exchange of nutrients. Composite nanofibers consisting of silk and hydroxyapatite nanoparticles (HAp) (NPs) had been considered as an excellent choice due to their efficient biocompatibility and bone-mimicking properties. To prepare these nanofiber composites, it requires the use of acidic solutions which have serious consequences on the nature of both silk and HAp NPs. It is ideal to create these nanofibers using aqueous solutions in which the physicochemical nature of both materials can be retained. However, to create those nanofibers is often difficult to obtain because of the fact that aqueous solutions of silk and HAp NPs can precipitate before they can be ejected into fibers during the electrospinning process. In this work, we had successfully used a three-way stopcock connector to mix the two different solutions, and very shortly, this solution is ejected out to form nanofibers due to electric fields. Different blend ratios consisting HAp NPs had been electrospun into nanofibers. The physicochemical aspects of fabricated nanofiber had been characterized by different state of techniques like that of FE-SEM, EDS, TEM, TEM-EDS, TGA, FT-IR, and XRD. These characterization techniques revealed that HAp NPs can be easily introduced in silk nanofibers using a stopcock connector, and this method favorably preserves the intact nature of silk fibroin and HAp NPs. Moreover, nanofibers obtained by this strategy were tested for cell toxicity and cell attachment studies using NIH 3 T3 fibroblasts which indicated non-toxic behavior and good attachment of cells upon incubation in the presence of nanofibers.

  18. Fabricating a reactive surface on the fibroin film by a room-temperature plasma jet array for biomolecule immobilization

    International Nuclear Information System (INIS)

    A simple dielectric barrier discharge (DBD) jet array was designed with a liquid electrode and helium gas. The characteristics of the jet array discharge and the preliminary polymerization with acrylic acid (AA) monomer were presented. The plasma reactor can produce a cold jet array with a gas temperature lower than 315 K, using an applied discharge power between 6 W and 30 W (Vdis × Idis). A silk fibroin film (SFF) was modified using the jet array and AA monomer, and the treated SFF samples were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and contact angle (CA). The deposition rate of the poly acrylic acid (PAA) was able to reach 300 nm/min, and the surface roughness and energy increased with the AA flow rate. The FTIR results indicate that the modified SFF had more carboxyl groups (-COOH) than the original SFF. This latter characteristic allowed the modified SFF to immobilize more quantities of antimicrobial peptide (AP, LL-37) which inhibited the Escherichia coli (E. Coli) effectively

  19. Silks as ancient models for modern polymers

    OpenAIRE

    Fritz Vollrath; David Porter

    2009-01-01

    Silks have a great potential as sustainable, ecologically benign commercial polymers. Here we discuss this fascinating bio-material by merging the biologist's with the polymer scientist's views i.e. combine insights into the characterisation and understanding of evolved structure, property and function in natural silk proteins with the broad scope of applied disciplines ranging from molecular modelling to rheology and mechanical testing. We conclude that silk cannot be defined simply by only ...

  20. Egg sac silk of Theridiosoma gemmosum (Araneae: Theridiosomatidae).

    Science.gov (United States)

    Hajer, Jaromír; Malý, Jan; Hrubá, Lenka; Reháková, Dana

    2009-10-01

    Cocoons of Theridiosoma gemmosum consist of two main parts, the egg sac case and the stalk. The inner space of the egg sac case is filled with nonsticky flocculent silk. Measuring 600-800 nm in diameter, the flocculent threads are never made up of bundles of longitudinally oriented nanofibrils. The egg case wall consists of a lower layer of highly ordered threads and an upper layer of cover silk. The lower, permanently white layer consists of threads in a mesh-like arrangement, the thicker threads being 4-6 microm and the thinner threads being 2-3 microm in diameter. Each thread is a bundle of parallel nanofibrils, with a diameter between 150 and 300 nm. The silk secretions of these fibers, emitted from spigots, are processed by legs. The upper layer of the egg case is applied to the threads of the lower layer by direct rubbing against its surface, i.e. without the use of legs. In the lower and middle part of the egg case, the accumulated secretion forms a virtually compact encrustation, whereas in the upper, conically shaped, part of the egg case where it becomes the stalk, this secretion becomes substantially scarcer. The stalk is a continuation of the egg case, its proximal part made of fibers similar to those forming the inner layer of the egg case wall. The distal part of the stalk continues towards the suspension area either as a compact bundle of parallel fibers, or the stalk forks into two bundles of roughly the same thickness, which continue towards the suspension area separately. On the surface of objects onto which cocoons are attached, the secretion of the piriform glands acts as an adhesive sheet. PMID:19459192

  1. Screening of Some Elements in Different Silk Cocoon Varieties

    Directory of Open Access Journals (Sweden)

    S. Wilaiwan

    2010-01-01

    Full Text Available The aim of this study was to screening of some elements in different silk cocoon varieties. The varieties of silk were Thai silk (yellow color; Samrong, Nangtui, Nanglai, Huafai, Nangnoi, Nanglaung, Nangseiw, Surin4, Nongkhai012, Green and Gold colors, wild silk (Eri, Japanese and Chinese silk. The cocoons were collected and subjected for investigation of element composition by using SEM/EDX technique. The results found that the elements were arranged in following order of C>O>Ca>Si>Cl>S>Mg for inner surfaces of silk cocoons. For the outer surfaces, all elements were distributed in all Thai strain which slightly differed for each silk strain. Among them, C and O were found in high percentage in all silk cocoons both inner and outer surfaces. Japanese showed higher element than Chinese, but lower than Thai silk varieties. The result indicated that elements may be involved the silk spinning process of silk fiber to promote ?-sheet structure.

  2. Carbondioxide gating in silk cocoon.

    Science.gov (United States)

    Roy, Manas; Meena, Sunil Kumar; Kusurkar, Tejas Sanjeev; Singh, Sushil Kumar; Sethy, Niroj Kumar; Bhargava, Kalpana; Sarkar, Sabyasachi; Das, Mainak

    2012-12-01

    Silk is the generic name given to the fibrous proteins spun by a number of arthropods. During metamorphosis, the larva of the silk producing arthropods excrete silk-fiber from its mouth and spun it around the body to form a protective structure called cocoon. An adult moth emerges out from the cocoon after the dormant phase (pupal phase) varying from 2 weeks to 9 months. It is intriguing how CO(2)/O(2) and ambient temperature are regulated inside the cocoon during the development of the pupa. Here we show that the cocoon membrane is asymmetric, it allows preferential gating of CO(2) from inside to outside and it regulates a physiological temperature inside the cocoon irrespective of the surrounding environment temperature. We demonstrate that under simulating CO(2) rich external environment, the CO(2) does not diffuse inside the cocoon. Whereas, when CO(2) was injected inside the cocoon, it diffuses out in 20 s, indicating gating of CO(2) from inside to outside the membrane. Removal of the calcium oxalate hydrate crystals which are naturally present on the outer surface of the cocoon affected the complete blockade of CO(2) flow from outside to inside suggesting its role to trap most of the CO(2) as hydrogen bonded bicarbonate on the surface. The weaved silk of the cocoon worked as the second barrier to prevent residual CO(2) passage. Furthermore, we show that under two extreme natural temperature regime of 5 and 50 °C, a temperature of 25 and 34 °C respectively were maintained inside the cocoons. Our results demonstrate, how CO(2) gating and thermoregulation helps in maintaining an ambient atmosphere inside the cocoon for the growth of pupa. Such natural architectural control of gas and temperature regulation could be helpful in developing energy saving structures and gas filters. PMID:22791361

  3. Spider wrapping silk fibre architecture arising from its modular soluble protein precursor

    Science.gov (United States)

    Tremblay, Marie-Laurence; Xu, Lingling; Lefèvre, Thierry; Sarker, Muzaddid; Orrell, Kathleen E.; Leclerc, Jérémie; Meng, Qing; Pézolet, Michel; Auger, Michèle; Liu, Xiang-Qin; Rainey, Jan K.

    2015-06-01

    Spiders store spidroins in their silk glands as high concentration aqueous solutions, spinning these dopes into fibres with outstanding mechanical properties. Aciniform (or wrapping) silk is the toughest spider silk and is devoid of the short amino acid sequence motifs characteristic of the other spidroins. Using solution-state NMR spectroscopy, we demonstrate that the 200 amino acid Argiope trifasciata AcSp1 repeat unit contrasts with previously characterized spidroins, adopting a globular 5-helix bundle flanked by intrinsically disordered N- and C-terminal tails. Split-intein-mediated segmental NMR-active isotope-enrichment allowed unambiguous demonstration of modular and malleable “beads-on-a-string” concatemeric behaviour. Concatemers form fibres upon manual drawing with silk-like morphology and mechanical properties, alongside secondary structuring and orientation consistent with native AcSp1 fibres. AcSp1 structural stability varies locally, with the fifth helix denaturing most readily. The structural transition of aciniform spidroin from a mostly ?-helical dope to a mixed ?-helix/?-sheet-containing fibre can be directly related to spidroin architecture and stability.

  4. Spider wrapping silk fibre architecture arising from its modular soluble protein precursor.

    Science.gov (United States)

    Tremblay, Marie-Laurence; Xu, Lingling; Lefèvre, Thierry; Sarker, Muzaddid; Orrell, Kathleen E; Leclerc, Jérémie; Meng, Qing; Pézolet, Michel; Auger, Michèle; Liu, Xiang-Qin; Rainey, Jan K

    2015-01-01

    Spiders store spidroins in their silk glands as high concentration aqueous solutions, spinning these dopes into fibres with outstanding mechanical properties. Aciniform (or wrapping) silk is the toughest spider silk and is devoid of the short amino acid sequence motifs characteristic of the other spidroins. Using solution-state NMR spectroscopy, we demonstrate that the 200 amino acid Argiope trifasciata AcSp1 repeat unit contrasts with previously characterized spidroins, adopting a globular 5-helix bundle flanked by intrinsically disordered N- and C-terminal tails. Split-intein-mediated segmental NMR-active isotope-enrichment allowed unambiguous demonstration of modular and malleable "beads-on-a-string" concatemeric behaviour. Concatemers form fibres upon manual drawing with silk-like morphology and mechanical properties, alongside secondary structuring and orientation consistent with native AcSp1 fibres. AcSp1 structural stability varies locally, with the fifth helix denaturing most readily. The structural transition of aciniform spidroin from a mostly ?-helical dope to a mixed ?-helix/?-sheet-containing fibre can be directly related to spidroin architecture and stability. PMID:26112753

  5. Trends in World Silk Cocoons and Silk Production and Trade, 2007-2010

    Directory of Open Access Journals (Sweden)

    AGATHA AGATHA POPESCU

    2013-10-01

    Full Text Available The paper aimed to analyze world production and trade for fresh silk cocoons and raw silk using FAO Stat data for  the  period 2007-2010. The use of index, share and comparison methods allowed to identify the major trends in the analyzed period. Silk decline was determined by the increased importance of cotton and artificial fibres in textile and clothing industry. Important changes are taking place on silk cocoons and silk market. While, the European market decreased, the Asian market has mainly developed fresh cocoons and raw silk, while the European market became more interested of clothes. Silk consumption declined because of consumer’s preference for synthetic fibres, except traditional consumers from Asia.  China is the main producer and exporter of fresh and dry cocoons, while raw silk is produced and exported by China, Brazil and Italy and imported by India, Japan and Italy. In Europe, Bulgaria is the top producer of fresh cocoons and raw silk and Italy is the main raw silk importer and the top producer and exporter of textile and fashion clothes. Silk will remain an important raw material for producing high quality and luxury clothes.

  6. Plasticity in Major Ampullate Silk Production in Relation to Spider Phylogeny and Ecology

    OpenAIRE

    Boutry, Cecilia; ?ezá?, Milan; Blackledge, Todd Alan

    2011-01-01

    Spider major ampullate silk is a high-performance biomaterial that has received much attention. However, most studies ignore plasticity in silk properties. A better understanding of silk plasticity could clarify the relative importance of chemical composition versus processing of silk dope for silk properties. It could also provide insight into how control of silk properties relates to spider ecology and silk uses.

  7. Effect of solute concentration on fibroin regulated biomineralization of calcium phosphate

    International Nuclear Information System (INIS)

    In this paper we used UV/Visible method to study the effect of solute concentration on fibroin regulated biomineralization of calcium phosphate. During the reaction process, ultraviolet-visible spectrophotometer was used to track the extinction in the reaction solution. It is found that kinetics of the biomineralization can be strongly affected by the presence of fibroin. Fibroin with higher concentration has more positive effect on the biomineralization process. Under the appropriate reaction conditions, wave crest and wave trough appear in the kinetic curves of fibroin biomineralization. The wave crest and wave trough phenomenon is mainly related with the process of phase separation. X-ray Diffraction (XRD) result shows the calcium phosphate before the wave trough is mainly amorphous calcium phosphate, while after the wave trough crystal of hydroxyapatite (HA) and brushite (DCPD) are the mainly ingredients

  8. Effect of solute concentration on fibroin regulated biomineralization of calcium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Kong Xiangdong [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Institute of Biochemistry, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Sun Xiaodan [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Cui Fuzhai [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)]. E-mail: cuifz@mail.tsinghua.edu.cn; Ma Chen [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2006-05-15

    In this paper we used UV/Visible method to study the effect of solute concentration on fibroin regulated biomineralization of calcium phosphate. During the reaction process, ultraviolet-visible spectrophotometer was used to track the extinction in the reaction solution. It is found that kinetics of the biomineralization can be strongly affected by the presence of fibroin. Fibroin with higher concentration has more positive effect on the biomineralization process. Under the appropriate reaction conditions, wave crest and wave trough appear in the kinetic curves of fibroin biomineralization. The wave crest and wave trough phenomenon is mainly related with the process of phase separation. X-ray Diffraction (XRD) result shows the calcium phosphate before the wave trough is mainly amorphous calcium phosphate, while after the wave trough crystal of hydroxyapatite (HA) and brushite (DCPD) are the mainly ingredients.

  9. Microbial production of spider silk proteins.

    Science.gov (United States)

    Fahnestock, S R; Yao, Z; Bedzyk, L A

    2000-08-01

    The remarkable properties of spider dragline silk and related protein polymers will find many applications if the materials can be produced economically. We have demonstrated the production of high molecular weight spider dragline silk analog proteins encoded by synthetic genes in several microbial systems, including Escherichia coli and Pichia pastoris. In E. coli, proteins of up to 1000 amino acids in length could be produced efficiently, but the yield and homogeneity of higher molecular weight silk proteins were found to be limited by truncated synthesis, probably as a result of ribosome termination errors. No such phenomenon was observed in the yeast P. pastoris, where higher molecular weight silk proteins could be produced without heterogeneity due to truncated synthesis. Spider dragline silk analog proteins could be secreted by P. pastoris when fused to both the signal sequence and N-terminal pro-sequence of the Saccharomyces cerevisiae alpha-mating factor gene. PMID:11763501

  10. Silk hydrogels for sustained ocular delivery of anti-vascular endothelial growth factor (anti-VEGF) therapeutics.

    Science.gov (United States)

    Lovett, Michael L; Wang, Xiaoqin; Yucel, Tuna; York, Lyndsey; Keirstead, Marc; Haggerty, Linda; Kaplan, David L

    2015-09-01

    Silk hydrogels were formulated with anti-vascular endothelial growth factor (anti-VEGF) therapeutics for sustained ocular drug delivery. Using silk fibroin as a vehicle for delivery, bevacizumab-loaded hydrogel formulations demonstrated sustained release of 3months or greater in experiments in vitro as well as in vivo using an intravitreal injection model in Dutch-belted rabbits. Using both standard dose (1.25mg bevacizumab/50?L injection) and high dose (5.0mg bevacizumab/50?L injection) hydrogel formulations, release concentrations were achieved at day 90 that were equivalent or greater than those achieved at day 30 with the positive standard dose control (single injection (50?L) of 1.25mg bevacizumab solution), which is estimated to be the therapeutic threshold based on the current dosage administration schedule of 1 injection/month. These gels also demonstrated signs of biodegradation after 3months, suggesting that repeated injections may be possible (e.g., one injection every 3-6months or longer). Due to its pharmacokinetic and biodegradation profiles, this delivery system may be used to reduce the frequency of dosing for patients currently enduring treatment using bevacizumab or other anti-VEGF therapeutics. PMID:25592326

  11. Thymus Gland Anatomy

    Science.gov (United States)

    ... My Pictures Browse Search Quick Search Image Details Thymus Gland Anatomy Adult View/Download: Small: 720x576 View Download Add to My Pictures Title: Thymus Gland Anatomy Adult Description: Anatomy of the thymus ...

  12. Adrenal Gland Cancer

    Science.gov (United States)

    ... either benign or malignant. Benign tumors aren't cancer. Malignant ones are. Most adrenal gland tumors are ... and may not require treatment. Malignant adrenal gland cancers are uncommon. Types of tumors include Adrenocortical carcinoma - ...

  13. Recombinant Spider Silks—Biopolymers with Potential for Future Applications

    OpenAIRE

    Thomas Scheibel; Martin Humenik; SMITH, ANDREW M.

    2011-01-01

    Nature has evolved a range of materials that compete with man-made materials in physical properties; one of these is spider silk. Silk is a fibrous material that exhibits extremely high strength and toughness with regard to its low density. In this review we discuss the molecular structure of spider silk and how this understanding has allowed the development of recombinant silk proteins that mimic the properties of natural spider silks. Additionally, we will explore the material morphologies ...

  14. Silkworms transformed with chimeric silkworm/spider silk genes spin composite silk fibers with improved mechanical properties.

    Science.gov (United States)

    Teulé, Florence; Miao, Yun-Gen; Sohn, Bong-Hee; Kim, Young-Soo; Hull, J Joe; Fraser, Malcolm J; Lewis, Randolph V; Jarvis, Donald L

    2012-01-17

    The development of a spider silk-manufacturing process is of great interest. However, there are serious problems with natural manufacturing through spider farming, and standard recombinant protein production platforms have provided limited progress due to their inability to assemble spider silk proteins into fibers. Thus, we used piggyBac vectors to create transgenic silkworms encoding chimeric silkworm/spider silk proteins. The silk fibers produced by these animals were composite materials that included chimeric silkworm/spider silk proteins integrated in an extremely stable manner. Furthermore, these composite fibers were, on average, tougher than the parental silkworm silk fibers and as tough as native dragline spider silk fibers. These results demonstrate that silkworms can be engineered to manufacture composite silk fibers containing stably integrated spider silk protein sequences, which significantly improve the overall mechanical properties of the parental silkworm silk fibers. PMID:22215590

  15. Silk Electrogel Based Gastroretentive Drug Delivery System

    Science.gov (United States)

    Wang, Qianrui

    Gastric cancer has become a global pandemic and there is imperative to develop efficient therapies. Oral dosing strategy is the preferred route to deliver drugs for treating the disease. Recent studies suggested silk electro hydrogel, which is pH sensitive and reversible, has potential as a vehicle to deliver the drug in the stomach environment. The aim of this study is to establish in vitro electrogelation e-gel based silk gel as a gastroretentive drug delivery system. We successfully extended the duration of silk e-gel in artificial gastric juice by mixing silk solution with glycerol at different ratios before the electrogelation. Structural analysis indicated the extended duration was due to the change of beta sheet content. The glycerol mixed silk e-gel had good doxorubicin loading capability and could release doxorubicin in a sustained-release profile. Doxorubicin loaded silk e-gels were applied to human gastric cancer cells. Significant cell viability decrease was observed. We believe that with further characterization as well as functional analysis, the silk e-gel system has the potential to become an effective vehicle for gastric drug delivery applications.

  16. Defensive behavior associated with secretions from the prosternal paired glands of the larvae of Heliconius erato phyllis Fabricius (Lepidoptera, Nymphalidae)

    Scientific Electronic Library Online (English)

    Eliane de Oliveira, Borges; Marcelo Eduardo, Borges; Paulo Henrique Gorgatti, Zarbin.

    2014-06-01

    Full Text Available Defensive behavior associated with secretions from the prosternal paired glands of the larvae of Heliconius erato phyllis Fabricius (Lepidoptera, Nymphalidae). Our work presents for the first time, the defensive behavior associated with the release of the product of the prosternal paired glands of t [...] he larva of Heliconius erato phyllis Fabricius, 1775 (Lepidoptera, Nymphalidae, Heliconiinae). The prosternal glands were first described for larvae of H. erato phyllis. They are formed by two types of glandular structures: the impair gland and the paired glands. The prosternal glands are located within the conical integumentary sac, which in turn is situated on the individual's prosternum. The main goal of this study is to analyze the existence of any secretion from the prosternal paired glands, and check the action mode of this secretion. The methodology used for chemical analysis of the glands included the aeration and, analysis in gas chromatography and gas chromatography-mass spectrometry. The results show that the prosternal glands do not produce volatiles. Bioassays were conducted with simulated and natural attacks and revealed that the prosternal paired glands produce secretions of defense together with silk produced by labials glands as a defense strategy, described for the first time, against ants. The strategy consists in wrapping the ant with silk threads, the entire wrapped object moved to the end of the body, with the aid of the legs and prolegs, and possibly fixed in a nearby place. Evidence for the existence of a conical integumentary sac in larvae of other species and families of Lepidoptera allows us to propose the possibility of occurrence of prosternal paired glands with defensive function in these other groups as well.

  17. THE GREAT SILK ROAD AND TURKISH WORLD

    Directory of Open Access Journals (Sweden)

    Mustafa ÖZDEM?R

    2011-04-01

    Full Text Available The expression of the great Silk Road first came from the famouse Chinese traveler Çjan Syan before the BC and is now known as Kervan Road. Later, this expression gained a new meaning between Asia, the Mediterranean and the European countries.An estimated of 20 000 km of total length of the Great Silk Road passed the Turkish peoples settled lands. The Silk Road that was considered as the Jugularvein major trade route that was connecting China and Byzantium was in Turks hands.

  18. The antimicrobial properties of spider silk

    OpenAIRE

    Wright, Simon

    2011-01-01

    The natural world is the source of many therapeutic products. Spider silk was evaluated for its ability to inhibit the growth of bacteria. Additionally tests assessing its potential suitability for use in human medicine were carried out. Silk produced by certain species of spiders has the ability to inhibit the growth of a gram-positive bacterium, B. subtilis. The ability of the silk to inhibit bacteria does not appear to be common to all spiders. Of all the species of spiders examined in...

  19. Spider Silk Fibers Spun from Soluble Recombinant Silk Produced in Mammalian Cells

    Science.gov (United States)

    Lazaris, Anthoula; Arcidiacono, Steven; Huang, Yue; Zhou, Jiang-Feng; Duguay, François; Chretien, Nathalie; Welsh, Elizabeth A.; Soares, Jason W.; Karatzas, Costas N.

    2002-01-01

    Spider silks are protein-based ``biopolymer'' filaments or threads secreted by specialized epithelial cells as concentrated soluble precursors of highly repetitive primary sequences. Spider dragline silk is a flexible, lightweight fiber of extraordinary strength and toughness comparable to that of synthetic high-performance fibers. We sought to ``biomimic'' the process of spider silk production by expressing in mammalian cells the dragline silk genes (ADF-3/MaSpII and MaSpI) of two spider species. We produced soluble recombinant (rc)-dragline silk proteins with molecular masses of 60 to 140 kilodaltons. We demonstrated the wet spinning of silk monofilaments spun from a concentrated aqueous solution of soluble rc-spider silk protein (ADF-3; 60 kilodaltons) under modest shear and coagulation conditions. The spun fibers were water insoluble with a fine diameter (10 to 40 micrometers) and exhibited toughness and modulus values comparable to those of native dragline silks but with lower tenacity. Dope solutions with rc-silk protein concentrations >20% and postspinning draw were necessary to achieve improved mechanical properties of the spun fibers. Fiber properties correlated with finer fiber diameter and increased birefringence.

  20. Silk as an innovative biomaterial for cancer therapy.

    Science.gov (United States)

    Jastrzebska, Katarzyna; Kucharczyk, Kamil; Florczak, Anna; Dondajewska, Ewelina; Mackiewicz, Andrzej; Dams-Kozlowska, Hanna

    2015-01-01

    Silk has been used for centuries in the textile industry and as surgical sutures. In addition to its unique mechanical properties, silk possesses other properties, such as biocompatibility, biodegradability and ability to self-assemble, which make it an interesting material for biomedical applications. Although silk forms only fibers in nature, synthetic techniques can be used to control the processing of silk into different morphologies, such as scaffolds, films, hydrogels, microcapsules, and micro- and nanospheres. Moreover, the biotechnological production of silk proteins broadens the potential applications of silk. Synthetic silk genes have been designed. Genetic engineering enables modification of silk properties or the construction of a hybrid silk. Bioengineered hybrid silks consist of a silk sequence that self-assembles into the desired morphological structure and the sequence of a polypeptide that confers a function to the silk biomaterial. The functional domains can comprise binding sites for receptors, enzymes, drugs, metals or sugars, among others. Here, we review the current status of potential applications of silk biomaterials in the field of oncology with a focus on the generation of implantable, injectable and targeted drug delivery systems and the three-dimensional cancer models based on silk scaffolds for cancer research. However, the systems described could be applied in many biomedical fields. PMID:25859397

  1. Silk epoxy composite crash worthiness performance

    International Nuclear Information System (INIS)

    Over the past several decades, increasing focus has been paid to the impact of structures where energy, during the impact event, needs to be absorbed in a controlled manner. This has led to considerable research being carried out on energy absorbers. These devices are designed to dissipate energy during an impact event and hence protect the structure under consideration. This research focuses on the square tube composite energy absorber. The tested square tubes were featured by 24 layers of natural silk as woven fabric in thermosetting epoxy resin. The fiber orientation angle of woven silk in the over-wrap is 0 and 90 degree to the tube axis. In this research silk/ epoxy tubes were cut at various thickness and they have been subjected to quasi static compression test. Silk/ epoxy square tubes have been analysed according to the compression test and the behaviour of this composite have been explained.(author)

  2. Injectable silk-polyethylene glycol hydrogels.

    Science.gov (United States)

    Wang, Xiaoqin; Partlow, Benjamin; Liu, Jian; Zheng, Zhaozhu; Su, Bo; Wang, Yansong; Kaplan, David L

    2015-01-01

    Silk hydrogels for tissue repair are usually pre-formed via chemical or physical treatments from silk solutions. For many medical applications, it is desirable to utilize injectable silk hydrogels at high concentrations (>8%) to avoid surgical implantation and to achieve slow in vivo degradation of the gel. In the present study, injectable silk solutions that formed hydrogels in situ were generated by mixing silk with low-molecular-weight polyethylene glycol (PEG), especially PEG300 and 400 (molecular weight 300 and 400g mol(-1)). Gelation time was dependent on the concentration and molecular weight of PEG. When the concentration of PEG in the gel reached 40-45%, gelation time was less than 30min, as revealed by measurements of optical density and rheological studies, with kinetics of PEG400 faster than PEG300. Gelation was accompanied by structural changes in silk, leading to the conversion from random coil in solution to crystalline ?-sheets in the gels, based on circular dichroism, attenuated total reflection Fourier transform infrared spectroscopy and X-ray diffraction. The modulus (127.5kPa) and yield strength (11.5kPa) determined were comparable to those of sonication-induced hydrogels at the same concentrations of silk. The time-dependent injectability of 15% PEG-silk hydrogel through 27G needles showed a gradual increase of compression forces from ?10 to 50N within 60min. The growth of human mesenchymal stem cells on the PEG-silk hydrogels was hindered, likely due to the presence of PEG, which grew after a 5 day delay, presumably while the PEG solubilized away from the gel. When 5% PEG-silk hydrogel was subcutaneously injected in rats, significant degradation and tissue in-growth took place after 20 days, as revealed by ultrasound imaging and histological analysis. No significant inflammation around the gel was observed. The features of injectability, slow degradation and low initial cell attachment suggests that these PEG-silk hydrogels are of interest for many biomedical applications, such as anti-fouling and anti-adhesion. PMID:25449912

  3. Seljuk Muqarnas along the Silk Road

    OpenAIRE

    Harmsen, Silvia; Jungblut, Daniel; Krömker, Susanne

    2007-01-01

    The film Seljuk Muqarnas along the Silk Road gives an overview of muqarnas, stalactite vaults, in Seljuk style architecture (1038-1194). The muqarnas are located in portals and niches of caravansaraies, madrassas and mosques. Starting with the Sultan Han near Kayseri we follow the Silk Road westward till Konya and finally show the Arslanhane Camii in Ankara. Video recordings alternate with computer reconstructions and animations, explaining the assembly of a caravansaray and the composition o...

  4. Electrodeposited silk coatings for bone implants.

    Science.gov (United States)

    Elia, Roberto; Michelson, Courtney D; Perera, Austin L; Brunner, Teresa F; Harsono, Masly; Leisk, Gray G; Kugel, Gerard; Kaplan, David L

    2015-11-01

    The aim of this study was to characterize the mechanical properties and drug elution features of silk protein-based electrodeposited dental implant coatings. Silk processing conditions were modified to obtain coatings with a range of mechanical properties on titanium studs. These coatings were assessed for adhesive strength and dissolution, with properties tuned using water vapor annealing or glycerol incorporation to modulate crystalline content. Coating reproducibility was demonstrated over a range of silk concentrations from 1% to 10%. Surface roughness of titanium substrates was altered using industry relevant acid etching and grit blasting, and the effect of surface topography on silk coating adhesion was assessed. Florescent compounds were incorporated into the silk coatings, which were modulated for crystalline content, to achieve four days of sustained release of the compounds. This silk electrogelation technique offers a safe and relatively simple approach to generate mechanically robust, biocompatible, and degradable implant coatings that can also be functionalized with bioactive compounds to modulate the local regenerative tissue environment. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 1602-1609, 2015. PMID:25545462

  5. Silk Roads or Steppe Roads? The Silk Roads in World History.

    Science.gov (United States)

    Christian, David

    2000-01-01

    Explores the prehistory of the Silk Roads, reexamines their structure and history in the classical era, and explores shifts in their geography in the last one thousand years. Explains that a revised understanding of the Silk Roads demonstrates how the Afro-Eurasian land mass has been linked by networks of exchange since the Bronze Age. (CMK)

  6. The mouse adrenal gland

    OpenAIRE

    Bielohuby, Maximilian

    2007-01-01

    The adrenal gland is a complex endocrine organ and its secreted hormones affect a multitude of essential systems, including stress response, immune function, cardio vascular regulation and anabolic or catabolic processes. In order to define age-dependent changes within the adrenal gland in the mouse, a systematic analysis of functional and growth-related parameters was performed by investigating the adrenal glands of male and female mice from weaning to adulthood (weeks 3, 5, 7, 9 and 11) at ...

  7. Ultrastructure of the Lyonet's glands in larvae of Diatraea saccharalis Fabricius (Lepidoptera: Pyralidae)

    Scientific Electronic Library Online (English)

    Eliane, Victoriano; Elisa A., Gregório.

    2004-08-01

    Full Text Available The Lyonet's gland is found in Lepidoptera larvae, close to the excretory duct of the silk gland. The role played by this gland is still uncertain. This work aims to describe the ultrastructure of the Lyonet's gland in Diatraea saccharalis larvae, offering suggestions regarding its possible function [...] . The insects were reared under laboratory-controlled conditions. The glands were conventionally prepared for transmission (TEM) and scanning (SEM) electron microscopy. SEM showed that Lyonet's glands are paired small structures located in the ventral side of the head. They are composed by clustered long cells resembling leaves. Under TEM observations, each cell is surrounded by a thin basal lamina and contains large stellate nucleus. The cytoplasm presents large and empty canaliculi with small microvilli. The basal plasma membrane forms numerous infoldings where numerous and well-developed mitochondria are concentrated. The cytoplasmic membrane system is poorly developed. Our ultrastructural results suggest that the Lyonet's gland in D. saccharalis larvae may be involved in the uptake of small molecules from the hemolymph; no morphological evidences of macromolecules synthesis and secretion were noticed. The detection of nerve fibers in the gland suggest a neural control for the glandular cell function.

  8. Ultrastructure of the Lyonet's glands in larvae of Diatraea saccharalis Fabricius (Lepidoptera: Pyralidae

    Directory of Open Access Journals (Sweden)

    Eliane Victoriano

    2004-08-01

    Full Text Available The Lyonet's gland is found in Lepidoptera larvae, close to the excretory duct of the silk gland. The role played by this gland is still uncertain. This work aims to describe the ultrastructure of the Lyonet's gland in Diatraea saccharalis larvae, offering suggestions regarding its possible function. The insects were reared under laboratory-controlled conditions. The glands were conventionally prepared for transmission (TEM and scanning (SEM electron microscopy. SEM showed that Lyonet's glands are paired small structures located in the ventral side of the head. They are composed by clustered long cells resembling leaves. Under TEM observations, each cell is surrounded by a thin basal lamina and contains large stellate nucleus. The cytoplasm presents large and empty canaliculi with small microvilli. The basal plasma membrane forms numerous infoldings where numerous and well-developed mitochondria are concentrated. The cytoplasmic membrane system is poorly developed. Our ultrastructural results suggest that the Lyonet's gland in D. saccharalis larvae may be involved in the uptake of small molecules from the hemolymph; no morphological evidences of macromolecules synthesis and secretion were noticed. The detection of nerve fibers in the gland suggest a neural control for the glandular cell function.

  9. Post-secretion processing influences spider silk performance.

    Science.gov (United States)

    Blamires, Sean J; Wu, Chung-Lin; Blackledge, Todd A; Tso, I-Min

    2012-10-01

    Phenotypic variation facilitates adaptations to novel environments. Silk is an example of a highly variable biomaterial. The two-spidroin (MaSp) model suggests that spider major ampullate (MA) silk is composed of two proteins-MaSp1 predominately contains alanine and glycine and forms strength enhancing ?-sheet crystals, while MaSp2 contains proline and forms elastic spirals. Nonetheless, mechanical properties can vary in spider silks without congruent amino acid compositional changes. We predicted that post-secretion processing causes variation in the mechanical performance of wild MA silk independent of protein composition or spinning speed across 10 species of spider. We used supercontraction to remove post-secretion effects and compared the mechanics of silk in this 'ground state' with wild native silks. Native silk mechanics varied less among species compared with 'ground state' silks. Variability in the mechanics of 'ground state' silks was associated with proline composition. However, variability in native silks did not. We attribute interspecific similarities in the mechanical properties of native silks, regardless of amino acid compositions, to glandular processes altering molecular alignment of the proteins prior to extrusion. Such post-secretion processing may enable MA silk to maintain functionality across environments, facilitating its function as a component of an insect-catching web. PMID:22628213

  10. Lacrimal gland (image)

    Science.gov (United States)

    The lacrimal gland lies within the orbit on the outer portion of the upper eye. The gland continually secretes tears which moisten, lubricate, and protect the surface of the eye. Excess tears drain into small ducts which empty into the nasal cavity.

  11. Salivary Gland Cancer

    Science.gov (United States)

    ... contains antibodies that can kill germs. Salivary gland cancer is a type of head and neck cancer. It is rare. It may not cause any ... pain in your face Doctors diagnose salivary gland cancer using a physical exam, imaging tests, and a ...

  12. Silkworms transformed with chimeric silkworm/spider silk genes spin composite silk fibers with improved mechanical properties

    OpenAIRE

    Teulé, Florence; Miao, Yun-Gen; Sohn, Bong-Hee; Kim, Young-Soo; Hull, J. Joe; Fraser, Malcolm J; Lewis, Randolph V; Jarvis, Donald L.

    2012-01-01

    The development of a spider silk-manufacturing process is of great interest. However, there are serious problems with natural manufacturing through spider farming, and standard recombinant protein production platforms have provided limited progress due to their inability to assemble spider silk proteins into fibers. Thus, we used piggyBac vectors to create transgenic silkworms encoding chimeric silkworm/spider silk proteins. The silk fibers produced by these animals were composite materials t...

  13. Screening of Some Elements in Different Silk Cocoon Varieties

    OpenAIRE

    S. Wilaiwan; B. Chirapha; S. Yaowalak; S. Prasong

    2010-01-01

    The aim of this study was to screening of some elements in different silk cocoon varieties. The varieties of silk were Thai silk (yellow color; Samrong, Nangtui, Nanglai, Huafai, Nangnoi, Nanglaung, Nangseiw, Surin4, Nongkhai012, Green and Gold colors), wild silk (Eri), Japanese and Chinese silk. The cocoons were collected and subjected for investigation of element composition by using SEM/EDX technique. The results found that the elements were arranged in following order of C>O>Ca>Si>Cl>S>Mg...

  14. Growth, cell cycle progression, and morphology of 3T3 cells following fibroin microsphere ingestion.

    Science.gov (United States)

    Go, Nam Kyung; Lee, Jin Sil; Lee, Joon Ho; Hur, Won

    2015-04-01

    Cellular uptake of microspheres may cause physiological stress and toxicity. In this report, we investigated the effect of cellular uptake of fibroin microspheres on the growth, cell cycle progression, and morphology of 3T3 cells. The microspheres were prepared by physical cross-linking of fibroin molecules without any chemical modification. Fluorescent microspheres are comprised of fluorescein isothiocyanate-dextran core and fibroin shell. More than 90% of cells were determined to be fluorescence-positive following 24-h incubation with fluorescent microspheres (0.17 mg/mL). Microsphere localization in the cytoplasm was demonstrated using confocal and transmission electron microscopy. Cellular uptake of microspheres did not influence cellular viability, but microsphere concentrations above 0.1 mg/mL resulted in decreased cell proliferation. The proliferation inhibition was attributed to G2 /M phase delay in cell cycle progression and S-phase delay at higher microsphere concentrations (0.33 mg/mL). Although flow cytometry light-scattering data raised the possibility of morphological changes, Coulter counter analysis confirmed no significant size differences between cells incubated with and without microspheres. Accordingly, fibroin microspheres can be a potential vehicle for intracytoplasmic delivery of cargos, without affecting cell viability. PMID:25044553

  15. Recombinant Spider Silks—Biopolymers with Potential for Future Applications

    Directory of Open Access Journals (Sweden)

    Thomas Scheibel

    2011-03-01

    Full Text Available Nature has evolved a range of materials that compete with man-made materials in physical properties; one of these is spider silk. Silk is a fibrous material that exhibits extremely high strength and toughness with regard to its low density. In this review we discuss the molecular structure of spider silk and how this understanding has allowed the development of recombinant silk proteins that mimic the properties of natural spider silks. Additionally, we will explore the material morphologies and the applications of these proteins. Finally, we will look at attempts to combine the silk structure with chemical polymers and how the structure of silk has inspired the engineering of novel polymers.

  16. Recombinant spider silk proteins for applications in biomaterials.

    Science.gov (United States)

    Spiess, Kristina; Lammel, Andreas; Scheibel, Thomas

    2010-09-01

    Due to their extraordinary mechanical and biochemical properties, silks have long been in focus of research. In vivo, fibers are formed from silk proteins, in vitro, however, a variety of materials can be produced in addition to fibers including capsules, particles, films, foams, and gels. The versatility of silk proteins, along with their biocompatibility, biodegradability, and potential for processing in aqueous solution under ambient conditions make silk-based materials good candidates for biomedical applications such as drug delivery systems and scaffolds for tissue engineering. Here, we summarize recent progress in research employing recombinantly produced engineered spider silk proteins with a focus on the fundamentals of silk protein processing. We highlight recombinant spider silk films and particles as morphologies that represent model systems with adjustable material properties controlled by process parameters. PMID:20602494

  17. Differential expression of genes in salivary glands of male Rhipicephalus (Boophilusmicroplus in response to infection with Anaplasma marginale

    Directory of Open Access Journals (Sweden)

    Jongejan Frans

    2010-03-01

    Full Text Available Abstract Background Bovine anaplasmosis, caused by the rickettsial tick-borne pathogen Anaplasma marginale (Rickettsiales: Anaplasmataceae, is vectored by Rhipicephalus (Boophilusmicroplus in many tropical and subtropical regions of the world. A. marginale undergoes a complex developmental cycle in ticks which results in infection of salivary glands from where the pathogen is transmitted to cattle. In previous studies, we reported modification of gene expression in Dermacentor variabilis and cultured Ixodes scapularis tick cells in response to infection with A. marginale. In these studies, we extended these findings by use of a functional genomics approach to identify genes differentially expressed in R. microplus male salivary glands in response to A. marginale infection. Additionally, a R. microplus-derived cell line, BME26, was used for the first time to also study tick cell gene expression in response to A. marginale infection. Results Suppression subtractive hybridization libraries were constructed from infected and uninfected ticks and used to identify genes differentially expressed in male R. microplus salivary glands infected with A. marginale. A total of 279 ESTs were identified as candidate differentially expressed genes. Of these, five genes encoding for putative histamine-binding protein (22Hbp, von Willebrand factor (94Will, flagelliform silk protein (100Silk, Kunitz-like protease inhibitor precursor (108Kunz and proline-rich protein BstNI subfamily 3 precursor (7BstNI3 were confirmed by real-time RT-PCR to be down-regulated in tick salivary glands infected with A. marginale. The impact of selected tick genes on A. marginale infections in tick salivary glands and BME26 cells was characterized by RNA interference. Silencing of the gene encoding for putative flagelliform silk protein (100Silk resulted in reduced A. marginale infection in both tick salivary glands and cultured BME26 cells, while silencing of the gene encoding for subolesin (4D8 significantly reduced infection only in cultured BME26 cells. The knockdown of the gene encoding for putative metallothionein (93 Meth, significantly up-regulated in infected cultured BME26 cells, resulted in higher A. marginale infection levels in tick cells. Conclusions Characterization of differential gene expression in salivary glands of R. microplus in response to A. marginale infection expands our understanding of the molecular mechanisms at the tick-pathogen interface. Functional studies suggested that differentially expressed genes encoding for subolesin, putative von Willebrand factor and flagelliform silk protein could play a role in A. marginale infection and multiplication in ticks. These tick genes found to be functionally relevant for tick-pathogen interactions will likely be candidates for development of vaccines designed for control of both ticks and tick-borne pathogens.

  18. Contrastive research on the waterproof and dustproof mechanism of wild silkworm silk and domestic silkworm silk

    Scientific Electronic Library Online (English)

    CHEN, Rou-Xi.

    2014-12-01

    Full Text Available Wild silk has properties of waterproof and dustproof, but its domestic partner has neither. Scanning electron microscopy (SEM) was used to observe and compare their morphology difference so that the possible mechanism can be elucidated. By the contrastive research, this paper concludes that the mech [...] anism of waterproof and dustproof of wild silk is due to selective repulsion, each hierarchical cascade of nanoparticles can repel either water molecules or fine particles in air. The SEM study reveals that the different nanoparticles with hierarchical structure on the silk surface are main factors of the highly selective repulsion. This theory can also explain the waterproof property of lotus leaf. A better understanding of the repulsion mechanism of wild silk could help the further design of bio-mimetic waterproof/dustproof artificial materials.

  19. Thyroid gland removal - discharge

    Science.gov (United States)

    ... surgery to remove part or all of your thyroid gland. This operation is called thyroidectomy . You probably ... in just a few weeks. If you had thyroid cancer, you may need to have radioactive iodine ...

  20. High-pressure gland

    International Nuclear Information System (INIS)

    A high-pressure gland is proposed for nuclear installations, operating at high temperatures. It consists of a stationary case with a stationary nonmetal sealing ring and of a rotary case with a rotary nonmetal sealing ring. The inner functional surfaces of the cases are provided with annular seating surfaces with semicircular grooves. Thus, the force and thermal deformations of the functional parts of the gland are eliminated. The sealing rings are manufactured from materials of identical hardness. (M.S.)

  1. Pediatric salivary gland imaging

    International Nuclear Information System (INIS)

    A variety of lesions occur in the pediatric salivary glands. With modern imaging techniques such as Doppler sonography, helical CT, and MRI, identification of a specific etiology is often possible. Knowledge of clinical information, normal anatomy, and imaging characteristics of salivary gland pathology are essential for appropriate radiologic evaluation. This review illustrates the various congenital, neoplastic, and inflammatory entities that can occur within the parotid, submandibular, and sublingual spaces. (orig.)

  2. Mammary gland stem cells

    DEFF Research Database (Denmark)

    Fridriksdottir, Agla J R; Petersen, Ole W; Rønnov-Jessen, Lone

    2011-01-01

    Distinct subsets of cells, including cells with stem cell-like properties, have been proposed to exist in normal human breast epithelium and breast carcinomas. The cellular origins of epithelial cells contributing to gland development, tissue homeostasis and cancer are, however, still poorly understood. The mouse is a widely used model of mammary gland development, both directly by studying the mouse mammary epithelial cells themselves and indirectly, by studying development, morphogenesis, diff...

  3. Antimicrobial functionalized genetically engineered spider silk.

    Science.gov (United States)

    Gomes, Sílvia C; Leonor, Isabel B; Mano, João F; Reis, Rui L; Kaplan, David L

    2011-06-01

    Genetically engineered fusion proteins offer potential as multifunctional biomaterials for medical use. Fusion or chimeric proteins can be formed using recombinant DNA technology by combining nucleotide sequences encoding different peptides or proteins that are otherwise not found together in nature. In the present study, three new fusion proteins were designed, cloned and expressed and assessed for function, by combining the consensus sequence of dragline spider silk with three different antimicrobial peptides. The human antimicrobial peptides human neutrophil defensin 2 (HNP-2), human neutrophil defensins 4 (HNP-4) and hepcidin were fused to spider silk through bioengineering. The spider silk domain maintained its self-assembly features, a key aspect of these new polymeric protein biomaterials, allowing the formation of ?-sheets to lock in structures via physical interactions without the need for chemical cross-linking. These new functional silk proteins were assessed for antimicrobial activity against Gram - Escherichia coli and Gram + Staphylococcus aureus and microbicidal activity was demonstrated. Dynamic light scattering was used to assess protein aggregation to clarify the antimicrobial patterns observed. Attenuated-total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and circular dichroism (CD) were used to assess the secondary structure of the new recombinant proteins. In vitro cell studies with a human osteosarcoma cell line (SaOs-2) demonstrated the compatibility of these new proteins with mammalian cells. PMID:21458065

  4. The Ancient Art of Silk Painting

    Science.gov (United States)

    Yonker, Kim

    2010-01-01

    In this article, the author describes a silk-painting project with a sea-creature theme for eighth-grade students. Other themes can be used such as geometric quilt designs, tropical rain forest, large flowers, Art Nouveau motifs, portraits and more. (Contains 2 resources.)

  5. Weaving Lao Silk Into Indigo Nights

    Directory of Open Access Journals (Sweden)

    Melody Kemp

    2010-12-01

    Full Text Available The air turned chilly as the sun sighed into the nearby hills. It picked up the smells of dust mixed with metallic and dung flavours. Miss Phaeng watched, holding her breath as the last sliver of red fell out of sight. Casting a quick mantra to the spirits of nature, she swallowed a glass of lao lao to start the evening.Leaning mindfully over her loom, Miss Phaeng raked her nails across the piano strings of silk warp, plucking each to test its tension. A black sheet of pin-straight hair fell over her face, hiding the claret birthmark shaped just like a spider, that crept over her right cheek, one leg disappearing into the fine hairs of her temple.The coarse ivory silk recently spooled from the cocoons gathered in her garden pushed back against her hand.She felt the fizz of anticipation low in her belly as she gathered all the many shuttles holding the weft silk and dumped them into an old blackened basket. Inhaling its heady stink of ash, grass and smoke, she placed the basket next to where she would sit.Melody Kemp offers a close look at the Lao silk industry.

  6. Constructing Knowledge with Silk Road Visuals

    Science.gov (United States)

    Bisland, Beverly Milner

    2008-01-01

    In this study a group of elementary teachers use illustrations, rather than written text, to introduce their students to the peoples and places of the ancient silk routes. The illustrations are from two picture books; "Marco Polo," written by Gian Paolo Cesaerani and illustrated by Piero Ventura (1977), and "We're Riding on a Caravan: An Adventure…

  7. The evolution of sweat glands

    Science.gov (United States)

    Folk, G. Edgar; Semken, A.

    1991-09-01

    Mammals have two kinds of sweat glands, apocrine and eccrine, which provide for thermal cooling. In this paper we describe the distribution and characteristics of these glands in selected mammals, especially primates, and reject the suggested development of the eccrine gland from the apocrine gland during the Tertiary geological period. The evidence strongly suggests that the two glands, depending on the presence or absence of fur, have equal and similar functions among mammals; apocrine glands are not primitive. However, there is a unique and remarkable thermal eccrine system in humans; we suggest that this system evolved in concert with bipedalism and a smooth hairless skin.

  8. Post-secretion processing influences spider silk performance

    OpenAIRE

    Blamires, Sean J.; Wu, Chung-Lin; Blackledge, Todd A; Tso, I-Min

    2012-01-01

    Phenotypic variation facilitates adaptations to novel environments. Silk is an example of a highly variable biomaterial. The two-spidroin (MaSp) model suggests that spider major ampullate (MA) silk is composed of two proteins—MaSp1 predominately contains alanine and glycine and forms strength enhancing ?-sheet crystals, while MaSp2 contains proline and forms elastic spirals. Nonetheless, mechanical properties can vary in spider silks without congruent amino acid compositional changes. We pred...

  9. Structure-Function-Property-Design Interplay in Biopolymers: Spider Silk

    OpenAIRE

    Tokareva, Olena; Jacobsen, Matthew; Buehler, Markus; Wong, Joyce; Kaplan, David L.

    2013-01-01

    Spider silks have been a focus of research for almost two decades due to their outstanding mechanical and biophysical properties. Recent advances in genetic engineering have led to the synthesis of recombinant spider silks, thus helping to unravel a fundamental understanding of structure-function-property relationships. The relationships between molecular composition, secondary structures, and mechanical properties found in different types of spider silks are described, along with a discussio...

  10. Investigations on natural silks using dynamic mechanical thermal analysis (DMTA)

    OpenAIRE

    Guan, Juan; Vollrath, Fritz; Porter, David

    2013-01-01

    This thesis examines the dynamic mechanical properties of natural silk fibres, mainly from silkworm species Bombyx mori (B. mori) and spider species Nephila edulis, using dynamic mechanical thermal analysis, DMTA. The aim is not only to provide novel data on mechanical properties of silk, but also to relate these properties to the structure and morphology of silk. A systematic approach is adopted to evaluate the effect of the three principal factors of stress, temperature and hydration on the...

  11. Undifferentiated salivary gland carcinomas

    DEFF Research Database (Denmark)

    Herbst, H.; Hamilton-Dutoit, S.

    2004-01-01

    Undifferentiated salivary gland carcinomas may be divided into small cell and large cell types. Among large cell undifferentiated carcinomas, lymphoepithelial carcinomas have to be distinguished, the latter of which are endemic in the Arctic regions and southern China where virtually all cases of these tumors are associated with the Epstein-Barr virus (EBV). Association with EBV may also be observed in sporadic cases, and detection of EBV gene products may aid their diagnosis. Immunohistology may be employed to resolve the differential diagnosis of undifferentiated salivary gland carcinomas, comprising malignant lymphomas, amelanotic melanomas, Merkel cell carcinomas, and adenoid cystic carcinomas, in particular in small biopsy materials. Because of the rarity of undifferentiated salivary gland carcinomas, the differential diagnosis should always include metastases of undifferentiated carcinomas arising at other primary sites, particularly when expressing the thyroid transcription factor-1 (TTF-1) Udgivelsesdato: 2004

  12. Structure-function-property-design interplay in biopolymers: spider silk.

    Science.gov (United States)

    Tokareva, Olena; Jacobsen, Matthew; Buehler, Markus; Wong, Joyce; Kaplan, David L

    2014-04-01

    Spider silks have been a focus of research for almost two decades due to their outstanding mechanical and biophysical properties. Recent advances in genetic engineering have led to the synthesis of recombinant spider silks, thus helping to unravel a fundamental understanding of structure-function-property relationships. The relationships between molecular composition, secondary structures and mechanical properties found in different types of spider silks are described, along with a discussion of artificial spinning of these proteins and their bioapplications, including the role of silks in biomineralization and fabrication of biomaterials with controlled properties. PMID:23962644

  13. Sequential pH-driven dimerization and stabilization of the N-terminal domain enables rapid spider silk formation

    DEFF Research Database (Denmark)

    Kronqvist, Nina; Otikovs, Martins

    2014-01-01

    The mechanisms controlling the conversion of spider silk proteins into insoluble fibres, which happens in a fraction of a second and in a defined region of the silk glands, are still unresolved. The N-terminal domain changes conformation and forms a homodimer when pH is lowered from 7 to 6; however, the molecular details still remain to be determined. Here we investigate site-directed mutants of the N-terminal domain from Euprosthenops australis major ampullate spidroin 1 and find that the charged residues D40, R60 and K65 mediate intersubunit electrostatic interactions. Protonation of E79 and E119 is required for structural conversions of the subunits into a dimer conformation, and subsequent protonation of E84 around pH 5.7 leads to the formation of a fully stable dimer. These residues are highly conserved, indicating that the now proposed three-step mechanism prevents premature aggregation of spidroins and enables fast formation of spider silk fibres in general.

  14. Negative supercoiling of DNA facilitates an interaction between transcription factor IID and the fibroin gene promoter.

    OpenAIRE

    Mizutani, M.; Ohta, T.; Watanabe, H; Handa, H; Hirose, S.

    1991-01-01

    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...

  15. Radioiodine and thyroid gland

    Directory of Open Access Journals (Sweden)

    Takavar A

    1994-05-01

    Full Text Available Administration of a precise amount of activity in thyroid gland radioiodine (¹³¹I therapy is of prime importance. Several methods for this purpose have been suggested and used over many years. In this paper, a method for required ¹³¹I activity calculation for each case has been proposed. Major factors affecting ¹³¹I calculation such as gland volume, integral dose, and prescription index have been described. Using the method, ¹³¹I activity or any other radioisotope activity required for a certain case can be determined with a good estimate.

  16. Recombinant production of spider silk proteins.

    Science.gov (United States)

    Heidebrecht, Aniela; Scheibel, Thomas

    2013-01-01

    Natural spider silk fibers combine extraordinary properties such as stability and flexibility which results in a toughness superseding that of all other fiber materials. As the spider's aggressive territorial behavior renders their farming not feasible, the biotechnological production of spider silk proteins (spidroins) is essential in order to investigate and employ them for applications. In order to accomplish this task, two approaches have been tested: firstly, the expression of partial cDNAs, and secondly, the expression of synthetic genes in several host organisms, including bacteria, yeast, plants, insect cells, mammalian cells, and transgenic animals. The experienced problems include genetic instability, limitations of the translational and transcriptional machinery, and low solubility of the produced proteins. Here, an overview of attempts to recombinantly produce spidroins will be given, and advantages and disadvantages of the different approaches and host organisms will be discussed. PMID:23415154

  17. Structure and pH-induced alterations of recombinant and natural spider silk proteins in solution.

    Science.gov (United States)

    Leclerc, Jérémie; Lefèvre, Thierry; Pottier, Fabien; Morency, Louis-Philippe; Lapointe-Verreault, Camille; Gagné, Stéphane M; Auger, Michèle

    2012-06-01

    The spinning process of spiders can modulate the mechanical properties of their silk fibers. It is therefore of primary importance to understand what are the key elements of the spider spinning process to develop efficient industrial spinning processes. We have exhaustively investigated the native conformation of major ampullate silk (MaS) proteins by comparing the content of the major ampullate gland of Nephila clavipes, solubilized MaS (SolMaS) fibers and the recombinant proteins rMaSpI and rMaSpII using (1) H solution NMR spectroscopy. The results indicate that the protein secondary structure is basically identical for the recombinant protein rMaSpI, SolMaS proteins, and the proteins in the dope, and corresponds to a disordered protein rich in 3(1) -helices. The data also show that glycine proton chemical shifts of rMaSpI and SolMaS are affected by pH, but that this change is not due to a modification of the secondary structure. Using a combination of NMR and dynamic light scattering, we have found that the spectral alteration of glycine is concomitant to a modification of the hydrodynamical diameter of recombinant and solubilized MaS. This led us to suggest new potential roles for the pH acidification in the spinning process of MaS proteins. PMID:21898365

  18. Antioxidant Activities of Iranian Corn Silk

    OpenAIRE

    Ebrahimzadeh, Mohammad Ali; POURMORAD, Fereshteh; HAFEZI, Samira

    2008-01-01

    Traditionally corn silk (CS) has been used as diuretic, antilithiasic, uricosuric, and antiseptic. It is used for the treatment of edema as well as for cystitis, gout, kidney stones, nephritis, and prostatitis. In the present study, the antioxidant properties of ethanol-water extract from CS were estimated by different methods. Also phenol and flavonoid content of the extract were measured by Folin Ciocalteu and AlCl3 assays. CS extract contained a significant amount of phenol and flavonoids....

  19. Antimicrobial functionalized genetically engineered spider silk

    OpenAIRE

    Gomes, Sílvia C.; Leonor, I. B.; Mano, J. F.; Reis, R. L.; Kaplan, David

    2011-01-01

    Genetically engineered fusion proteins offer potential as multifunctional biomaterials for medical use. Fusion or chimeric proteins can be formed using recombinant DNA technology by combining nucleotide sequences encoding different peptides or proteins that are otherwise not found together in nature. In the present study, three new fusion proteins were designed, cloned and expressed and assessed for function, by combining the consensus sequence of dragline spider silk with three different ant...

  20. Recombinant spider silk with antimicrobial properties

    OpenAIRE

    Nilebäck, Linnea

    2013-01-01

    Immobilizing antimicrobial substances onto biocompatible materials is an important approach for the design of novel, functionalized medical devices. By choosing antimicrobial substances from innate immune systems, the risk for development of resistance in pathogenic microbes is lower than if conventional antibiotics are used. Combining natural antimicrobial peptides and bactericidal enzymes with strong and elastic spider silk through recombinant protein technology would enable large-scale pro...

  1. The Consolidation Behavior of Silk Hydrogels

    OpenAIRE

    Kluge, Jonathan A; Rosiello, Nicholas C.; Leisk, Gary G.; Kaplan, David L.; Dorfmann, A. Luis

    2009-01-01

    Hydrogels have mechanical properties and structural features that are similar to load bearing soft tissues including intervertebral disc and articular cartilage, and can be implanted for tissue restoration or for local release of therapeutic factors. To help predict their performance, mechanical characterization and mathematical modeling are available methods for use in tissue engineering and drug delivery settings. In this study, confined compression creep tests were performed on silk hydrog...

  2. Understanding the variability of properties in Antheraea pernyi silk fibres.

    Science.gov (United States)

    Wang, Yu; Guan, Juan; Hawkins, Nick; Porter, David; Shao, Zhengzhong

    2014-09-01

    Variability is a common feature of natural silk fibres, caused by a range of natural processing conditions. Better understanding of variability will not only be favourable for explaining the enviable mechanical properties of animal silks but will provide valuable information for the design of advanced artificial and biomimetic silk-like materials. In this work, we have investigated the origin of variability in forcibly reeled Antheraea pernyi silks from different individuals using dynamic mechanical thermal analysis (DMTA) combined with the effect of polar solvent penetration. Quasi-static tensile curves in different media have been tested to show the considerable variability of tensile properties between samples from different silkworms. The DMTA profiles (as a function of temperature or humidity) through the glass transition region of different silks as well as dynamic mechanical properties after high temperature and water annealing are analysed in detail to identify the origin of silk variability in terms of molecular structures and interactions, which indicate that different hydrogen bonded structures exist in the amorphous regions and they are notably different for silks from different individuals. Solubility parameter effects of solvents are quantitatively correlated with the different glass transitions values. Furthermore, the overall ordered fraction is shown to be a key parameter to quantify the variability in the different silk fibres, which is consistent with DMTA and FTIR observations. PMID:25030083

  3. The failure mode of natural silk epoxy triggered composite tubes

    International Nuclear Information System (INIS)

    In this study the quasi static compression test over natural silk epoxy triggered composite tubes has been carried out, the natural silk epoxy composite tubes consist of 24 layer of woven natural silk as reinforcement and thermoset epoxy resin as matrix which both of them i e natural silk and epoxy have excellent mechanical properties More over the natural silk have better moisture resistance in comparison with other natural reinforcements, the length of tubes are 50, 80 and 120 mm The natural silk epoxy composite tubes are associated with an external trigger which includes 4 steel pieces welded on downside flat plate fixture The hand lay up fabrication method has been used to make the natural silk epoxy composite tubes Instron universal testing machine with 250 KN load capacity has been employed to accomplish this investigation The failure modes of natural silk epoxy triggered composite tubes has been investigated by representative photographs which has been taken by a high resolution camera(12 2 Mp) during the quasi static compression test, from the photographs is observed the failure modes is progressive local buckling

  4. Visual Literacy with Picture Books: The Silk Road

    Science.gov (United States)

    Bisland, Beverly Milner Lee

    2007-01-01

    The ancient Silk Routes connecting China to Europe across the rugged mountains and deserts of central Asia are one of the primary examples of transculturation in world history. Traders on these routes dealt not only in goods such as silk and horses but also made possible the spread of art forms as well as two major religions, Buddhism and Islam. …

  5. Geographic Perspectives with Elementary Students: The Silk Road

    Science.gov (United States)

    Bisland, Beverly Milner

    2006-01-01

    The purpose of this study is to investigate elementary students' explanations of how physical features of the land influence the location of humanly defined structures including trade routes, such as the silk routes. The silk routes were a series of caravan trade routes that extended from Turkey to China and were located as far south as India and…

  6. Biofabrication of cell-loaded 3D spider silk constructs.

    Science.gov (United States)

    Schacht, Kristin; Jüngst, Tomasz; Schweinlin, Matthias; Ewald, Andrea; Groll, Jürgen; Scheibel, Thomas

    2015-02-23

    Biofabrication is an emerging and rapidly expanding field of research in which additive manufacturing techniques in combination with cell printing are exploited to generate hierarchical tissue-like structures. Materials that combine printability with cytocompatibility, so called bioinks, are currently the biggest bottleneck. Since recombinant spider silk proteins are non-immunogenic, cytocompatible, and exhibit physical crosslinking, their potential as a new bioink system was evaluated. Cell-loaded spider silk constructs can be printed by robotic dispensing without the need for crosslinking additives or thickeners for mechanical stabilization. Cells are able to adhere and proliferate with good viability over at least one week in such spider silk scaffolds. Introduction of a cell-binding motif to the spider silk protein further enables fine-tuned control over cell-material interactions. Spider silk hydrogels are thus a highly attractive novel bioink for biofabrication. PMID:25640578

  7. Determination of Metals in Thai Silk by Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Full text: The project aimed to develop the technique of neutron activation analysis (NAA) for determination of metals in silk textile. The developed technique can be used for clarification the quality of the silk material according to the requirement from the foreign customers. The optimum parameters of NAA were found by experiment with standards and silk samples. 21 metals and other trace elements could be determined qualitatively. The technique was then used for quantitative analysis of metals in 51 pieces of silk from Silk Contest, Bangsai Arts and Crafts Centre of H.M. Queen Sirikit of Thailand. The analysis was specified for heavy metals of which information could indicate the quality of the materials, i.e., Ag, As, Au, Cr. Cu, Fe, Hg, K, Sb and Zn. The experiment and results were reported in this paper

  8. Study on silk yellowing induced by gamma-irradiation

    International Nuclear Information System (INIS)

    The changes in the yellow color of silk threads with total dose of irradiation applied were described and studied by a colorimetric method and by monochrome photography. The change into a yellow color of the specimen in the course of irradiation was clearly detected in photographs using filters, 2B and SC 56 under light conditions at the wavelength of 366 nm. The b/L value measured by colorimetry in undegummed and degummed silk fibers sharply increased in the early stage of irradiation. Yellow color indices (b/L) of the specimen subjected to gamma-irradiation continued to increase and the yellow color of the silk threads became more pronounced above a total dose of irradiation of 21 Mrad. The b/L value of the undegummed silk fiber which had deen irradiated was about 2 times that of the degummed silk fiber. (author)

  9. Optical surface profiling of orb-web spider capture silks

    International Nuclear Information System (INIS)

    Much spider silk research to date has focused on its mechanical properties. However, the webs of many orb-web spiders have evolved for over 136 million years to evade visual detection by insect prey. It is therefore a photonic device in addition to being a mechanical device. Herein we use optical surface profiling of capture silks from the webs of adult female St Andrews cross spiders (Argiope keyserlingi) to successfully measure the geometry of adhesive silk droplets and to show a bowing in the aqueous layer on the spider capture silk between adhesive droplets. Optical surface profiling shows geometric features of the capture silk that have not been previously measured and contributes to understanding the links between the physical form and biological function. The research also demonstrates non-standard use of an optical surface profiler to measure the maximum width of a transparent micro-sized droplet (microlens).

  10. 21 CFR 184.1262 - Corn silk and corn silk extract.

    Science.gov (United States)

    2010-04-01

    ... (a) Corn silk is the fresh styles and stigmas of Zea...exceeding 60 °C. (b) The ingredient must be of a purity suitable...184.1(b)(2), the ingredients are used in food only within...Prior sanctions for this ingredient different from the uses...

  11. Solution behavior of synthetic silk peptides and modified recombinant silk proteins

    Science.gov (United States)

    Foo, C. Wong Po; Bini, E.; Huang, J.; Lee, S. Y.; Kaplan, D. L.

    2006-02-01

    Spider dragline silk from Nephila clavipes possesses impressive mechanical properties derived in part from repetitive primary sequence containing polyalanine regions that self-assemble into crystalline ?-sheets. In the present study, we have sought to understand more details of redox responses related to conformational transitions of modified silk peptides and a recombinant protein containing encoded methionine triggers. Regardless of the position of the methionine trigger relative to the polyalanine domain, chemical oxidation was rapid and slight increases in the ?-helical structure and decreases in the ?-sheet and random coil content were observed by CD and FTIR in the assembled silk-like peptides and the recombinant protein. CD results indicated that the decrease in ?-sheet and random coil conformations, coupled with the increase in helical content during oxidation, occurred during the first 30 min of the reaction. No further conformational changes occurred after this time and the response was independent of methionine trigger location relative to the penta-alanine domain. These results were confirmed with fluorescence studies. The design, processing and utility of these modified redox triggered silk-like peptides and proteins suggest a range of potential utility, from biomaterials to engineered surface coatings with chemically alterable secondary structure and, thus, properties.

  12. Gland steam system upgrade

    International Nuclear Information System (INIS)

    Turbine Gland Steam System (GSS) prevents entry of air into or steam leakage from the high and low pressure turbine labyrinth seals by providing sealing steam to the turbine rotor glands (labyrinth seals). The function of the system is to reduce thermal cycle losses. At Virginia Power's North Anna Power Station GSS, a secondary system was envisioned to last (40) years. However, as a result of erosion and Flow Accelerated Corrosion (FAC) phenomena, the system severely deteriorated before its planned life. Past like-for-like piping replacements were considered only short-term ''fixes''. The original construction carbon steel piping has now been replaced with stainless steel to substantially minimize the erosion, FAC caused damage and thermal cycle losses. This paper reports on the replacement project and examines the history of the system, techniques used in analyzing the piping and pipe supports, selection of corrosion resistant material, problems encountered and lessons learned. It covers engineering methodology used and experience gathered during construction

  13. Pituitary gland tumors

    International Nuclear Information System (INIS)

    This article gives an overview of the most common tumors of the pituitary gland and the differential diagnostics with special emphasis on radiological diagnostic criteria. A selective search of the literature in PubMed was carried out. Pituitary adenomas constitute 10-15 % of all intracranial tumors and are the most common tumors of the sellar region. Tumors smaller than 1 cm in diameter are called microadenomas while those larger than 1 cm in diameter are called macroadenomas. Approximately 65 % of pituitary gland adenomas secrete hormones whereby approximately 50 % secrete prolactin, 10 % secrete growth hormone (somatotropin) and 6 % secrete corticotropin. Other tumors located in the sella turcica can also cause endocrinological symptoms, such as an oversecretion of pituitary hormone or pituitary insufficiency by impinging on the pituitary gland or its stalk. When tumors spread into the space cranial to the sella turcica, they can impinge on the optic chiasm and cause visual disorders. A common differential diagnosis of a sellar tumor is a craniopharyngeoma. In children up to 10 % of all intracranial tumors are craniopharyngeomas. Other differential diagnoses for sellar tumors are metastases, meningiomas, epidermoids and in rare cases astrocytomas, germinomas or Rathke cleft cysts As these tumors are located in an anatomically complex region of the skull base and are often very small, a highly focused imaging protocol is required. The currently favored modality is magnetic resonance imaging (MRI) with the administration of a contrast agent. The sellar region should be mapped in thin slices. In cases of suspected microadenoma the imaging protocol should also contain a sequence with dynamic contrast administration in order to assess the specific enhancement characteristics of the tumor and the pituitary gland. (orig.)

  14. The elaborate structure of spider silk: Structure and function of a natural high performance fiber

    OpenAIRE

    Römer, Lin; Scheibel, Thomas

    2008-01-01

    Biomaterials, having evolved over millions of years, often exceed man-made materials in their properties. Spider silk is one outstanding fibrous biomaterial which consists almost entirely of large proteins. Silk fibers have tensile strengths comparable to steel and some silks are nearly as elastic as rubber on a weight to weight basis. In combining these two properties, silks reveal a toughness that is two to three times that of synthetic fibers like Nylon or Kevlar. Spider silk is also antim...

  15. Bioprospecting Finds the Toughest Biological Material: Extraordinary Silk from a Giant Riverine Orb Spider

    OpenAIRE

    Agnarsson, Ingi; Kuntner, Matjaž; Blackledge, Todd A

    2010-01-01

    Background Combining high strength and elasticity, spider silks are exceptionally tough, i.e., able to absorb massive kinetic energy before breaking. Spider silk is therefore a model polymer for development of high performance biomimetic fibers. There are over 41.000 described species of spiders, most spinning multiple types of silk. Thus we have available some 200.000+ unique silks that may cover an amazing breadth of material properties. To date, however, silks from only a few tens of sp...

  16. Electricity from the Silk Cocoon Membrane

    Science.gov (United States)

    Tulachan, Brindan; Meena, Sunil Kumar; Rai, Ratan Kumar; Mallick, Chandrakant; Kusurkar, Tejas Sanjeev; Teotia, Arun Kumar; Sethy, Niroj Kumar; Bhargava, Kalpana; Bhattacharya, Shantanu; Kumar, Ashok; Sharma, Raj Kishore; Sinha, Neeraj; Singh, Sushil Kumar; Das, Mainak

    2014-06-01

    Silk cocoon membrane (SCM) is an insect engineered structure. We studied the electrical properties of mulberry (Bombyx mori) and non-mulberry (Tussar, Antheraea mylitta) SCM. When dry, SCM behaves like an insulator. On absorbing moisture, it generates electrical current, which is modulated by temperature. The current flowing across the SCM is possibly ionic and protonic in nature. We exploited the electrical properties of SCM to develop simple energy harvesting devices, which could operate low power electronic systems. Based on our findings, we propose that the temperature and humidity dependent electrical properties of the SCM could find applications in battery technology, bio-sensor, humidity sensor, steam engines and waste heat management.

  17. Structure properties of spider silk investigated by ATR/FT-IR spectroscopy

    International Nuclear Information System (INIS)

    Complete text of publication follows. Spider silk is one of fibrous proteins, carrying the exceptional mechanical properties. Recently, significant advances have reported in the literature regarding the production of recombinant spider silk protein. However, the molecular mechanism of the spider silk is still not completely understood. In order to analyze the structure properties of natural silk of Japanese spider Nephila clavta, the attenuated total reflectance (ATR) FT-IR spectroscopy was carried out. Polarized ATR measurements showed that most of amide groups in silk protein were oriented to the same direction in the silk fibers. Secondary structure of silk protein was estimated by Fourier self-deconvolution and the curve-fitting procedures. The results suggested that cross beta-sheet structure is predominant in natural dragline silk. Besides, the amide vibrations of the spider silk were significantly changed in the addition of water. Since the remarkable elasticity of spider silk is induced by water adsorption, the particular interaction between silk proteins and water molecules seems to be an indispensable property of spider silk. The structure transition from unordered structure to sheet conformation was identified in air-drying process with silk solution from major ampullate, suggesting that the silk spinning was involved in the molecular formation of silk protein. In order to obtain an insight into the natural spider web, imaging technique with micro FT-IR measurement was also employed. The results will be discussed.

  18. An unlikely silk: the composite material of green lacewing cocoons.

    Science.gov (United States)

    Weisman, Sarah; Trueman, Holly E; Mudie, Stephen T; Church, Jeffrey S; Sutherland, Tara D; Haritos, Victoria S

    2008-11-01

    Spiders routinely produce multiple types of silk; however, common wisdom has held that insect species produce one type of silk each. This work reports that the green lacewing ( Mallada signata, Neuroptera) produces two distinct classes of silk. We identified and sequenced the gene that encodes the major protein component of the larval lacewing cocoon silk and demonstrated that it is unrelated to the adult lacewing egg-stalk silk. The cocoon silk protein is 49 kDa in size and is alanine rich (>40%), and it contains an alpha-helical secondary structure. The final instar lacewing larvae spin protein fibers of approximately 2 microm diameter to construct a loosely woven cocoon. In a second stage of cocoon construction, the insects lay down an inner wall of lipids that uses the fibers as a scaffold. We propose that the silk protein fibers provide the mechanical strength of the composite lacewing cocoon whereas the lipid layer provides a barrier to water loss during pupation. PMID:18828638

  19. An Unlikely Silk: The Composite Material of Green Lacewing Cocoons

    Energy Technology Data Exchange (ETDEWEB)

    Weisman, Sarah; Trueman, Holly E.; Mudie, Stephen T.; Church, Jeffrey S.; Sutherland, Tara D.; Haritos, Victoria S. (CSIRO/MSE); (CSIRO)

    2009-01-15

    Spiders routinely produce multiple types of silk; however, common wisdom has held that insect species produce one type of silk each. This work reports that the green lacewing (Mallada signata, Neuroptera) produces two distinct classes of silk. We identified and sequenced the gene that encodes the major protein component of the larval lacewing cocoon silk and demonstrated that it is unrelated to the adult lacewing egg-stalk silk. The cocoon silk protein is 49 kDa in size and is alanine rich (>40%), and it contains an {alpha}-helical secondary structure. The final instar lacewing larvae spin protein fibers of {approx}2 {mu}m diameter to construct a loosely woven cocoon. In a second stage of cocoon construction, the insects lay down an inner wall of lipids that uses the fibers as a scaffold. We propose that the silk protein fibers provide the mechanical strength of the composite lacewing cocoon whereas the lipid layer provides a barrier to water loss during pupation.

  20. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    International Nuclear Information System (INIS)

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently, artificial spider silk, with mechanical and structural characteristics similar to those of native spider silk, has been produced from recombinant minispidroins. In the present study, supersaturated simulated body fluid was used to deposit calcium phosphate coatings on recombinant spider silk fibres. The mineralization process was followed in time using scanning electron microscopy equipped with an energy dispersive x-ray (EDX) detector and Raman spectroscope. Focused ion beam technology was used to produce a cross section of a coated fibre, which was further analysed by EDX. Preliminary in vitro experiments using a culture of bone marrow-derived human mesenchymal stem cells (hMSCs) on coated fibres were also performed. This study showed that recombinant spider silk fibres were successfully coated with a homogeneous and thick crystalline calcium phosphate layer. In the course of the mineralization process from modified simulated body fluid, sodium chloride crystals were first deposited on the silk surface, followed by the deposition of a calcium phosphate layer. The coated silk fibres supported the attachment and growth of hMSCs.

  1. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    Energy Technology Data Exchange (ETDEWEB)

    Yang Liang; Habibovic, Pamela; Van Blitterswijk, Clemens A [Department of Tissue Regeneration, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Hedhammar, My; Johansson, Jan [Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, the Biomedical Centre, Box 575, 751 23 Uppsala (Sweden); Blom, Tobias; Leifer, Klaus [Department of Engineering Sciences, Uppsala University, Box 534, S-751 21 Uppsala (Sweden)

    2010-08-01

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently, artificial spider silk, with mechanical and structural characteristics similar to those of native spider silk, has been produced from recombinant minispidroins. In the present study, supersaturated simulated body fluid was used to deposit calcium phosphate coatings on recombinant spider silk fibres. The mineralization process was followed in time using scanning electron microscopy equipped with an energy dispersive x-ray (EDX) detector and Raman spectroscope. Focused ion beam technology was used to produce a cross section of a coated fibre, which was further analysed by EDX. Preliminary in vitro experiments using a culture of bone marrow-derived human mesenchymal stem cells (hMSCs) on coated fibres were also performed. This study showed that recombinant spider silk fibres were successfully coated with a homogeneous and thick crystalline calcium phosphate layer. In the course of the mineralization process from modified simulated body fluid, sodium chloride crystals were first deposited on the silk surface, followed by the deposition of a calcium phosphate layer. The coated silk fibres supported the attachment and growth of hMSCs.

  2. The effects of corn silk on glycaemic metabolism

    Directory of Open Access Journals (Sweden)

    Han Linna

    2009-11-01

    Full Text Available Abstract Background Corn silk contains proteins, vitamins, carbohydrates, Ca, K, Mg and Na salts, fixed and volatile oils, steroids such as sitosterol and stigmasterol, alkaloids, saponins, tannins, and flavonoids. Base on folk remedies, corn silk has been used as an oral antidiabetic agent in China for decades. However, the hypoglycemic activity of it has not yet been understood in terms of modern pharmacological concepts. The purpose of this study is to investigate the effects of corn silk on glycaemic metabolism. Methods Alloxan and adrenalin induced hyperglycemic mice were used in the study. The effects of corn silk on blood glucose, glycohemoglobin (HbA1c, insulin secretion, damaged pancreatic ?-cells, hepatic glycogen and gluconeogenesis in hyperglycemic mice were studied respectively. Results After the mice were orally administered with corn silk extract, the blood glucose and the HbA1c were significantly decreased in alloxan-induced hyperglycemic mice (p 0.05. Although corn silk extract increased the level of hepatic glycogen in the alloxan-induced hyperglycemic mice, there was no significant difference between them and that of the control group(p > 0.05. Conclusion Corn silk extract markedly reduced hyperglycemia in alloxan-induced diabetic mice. The action of corn silk extract on glycaemic metabolism is not via increasing glycogen and inhibiting gluconeogenesis but through increasing insulin level as well as recovering the injured ?-cells. The results suggest that corn silk extract may be used as a hypoglycemic food or medicine for hyperglycemic people in terms of this modern pharmacological study.

  3. Nephila clavipes Flagelliform Silk-like GGX Motifs Contribute to Extensibility and Spacer Motifs Contribute to Strength in Synthetic Spider Silk Fibers

    OpenAIRE

    Adrianos, Sherry L.; Teulé, Florence; Hinman, Michael B.; Jones, Justin A.; Weber, Warner S.; Yarger, Jeffery L.; Lewis, Randolph V

    2013-01-01

    Flagelliform spider silk is the most extensible silk fiber produced by orb weaver spiders, though not as strong as the dragline silk of the spider. The motifs found in the core of the Nephila clavipes flagelliform Flag protein are: GGX, spacer, and GPGGX. Flag does not contain the polyalanine motif known to provide the strength of dragline silk. To investigate the source of flagelliform fiber strength, four recombinant proteins were produced containing variations of the three core motifs of t...

  4. Submandibular gland excision

    DEFF Research Database (Denmark)

    Springborg, Line Kanstrup; Møller, Martin Nue

    2013-01-01

    In transcervical resection of the submandibular gland for benign lesions, only a limited risk of damage to neural structures can be accepted and a cosmetically satisfactory result is mandatory. In this retrospective case series, we evaluated 139 patients operated over a 10-year period and completed long-term clinical follow-up of 113 of these patients after a median of 81 months. In all patients, the operation was effective. We found a 4.3 % risk of reoperation for wound infection or postoperati...

  5. Scintigraphy of the adrenal gland

    Energy Technology Data Exchange (ETDEWEB)

    Dabasi, G. (Semmelweis Orvostudomanyi Egyetem, Budapest (Hungary). Radiologiai Klinika)

    1983-01-01

    Scintigraphic examinations of the adrenal gland are reported for the first time in Hungary. It is emphasized that the scintigraphy of the adrenal gland is easy to perform and gives information on the functional state of the adrenal cortex and localizes the pathognostic process.

  6. Controlled hydrogel formation of a recombinant spider silk protein.

    Science.gov (United States)

    Schacht, Kristin; Scheibel, Thomas

    2011-07-11

    Due to their biocompatibility, biodegradability, and low immunogenicity, recombinant spider silk proteins have a high potential for a variety of applications when processed into morphologies such as films, capsules, beads, or hydrogels. Here, hydrogels made of the engineered and recombinantly produced spider silk protein eADF4(C16) were analyzed in detail. It has previously been shown that eADF4(C16) nanofibrils self-assemble by a mechanism of nucleation-aggregation, providing the basis of silk hydrogels. We focused on establishing a reproducible gelation process by employing different protein concentrations, chemical crosslinking, and functionalization of eADF4(C16) with fluorescein. Fluorescein strongly influenced assembly as well as the properties of the hydrogels, such as pore sizes and mechanical behavior, possibly due to its interference with packing of silk nanofibrils during hydrogel formation. PMID:21612299

  7. [Effect of salt on minor ampullate silk spidroin modules].

    Science.gov (United States)

    Wang, Jia; Chen, Gefei; Meng, Qing

    2014-08-01

    To study the effect of physiological conditions on spidroins, we analyzed NTR1SR2CT module secondary structure, aggregation and silk-formation influenced by different salts (in different concentration intervals). According to the full-length Araneus ventricosus MiSp sequence, NTR1SR2CT module was constructed and expressed in Escherichia coli BL21 (DE3), and the recombinant proteins were purified by denaturation method mediated by 8 mol/L urea. Random coil and helix are the main secondary structures of NTR1SR2CT and could be induced into beta-sheet by drying natively and lyophilization, where methanol can be used as a promoter. Furthermore, potassium and phosphate cations can cause significant NTR1SR2CT protein aggregation and silk-formation. The results could be a basis for the determination of silk-formation mechanism, and also useful for industrialized generation of high performance spider silk-like fibers. PMID:25507484

  8. Recent advances in production of recombinant spider silk proteins.

    Science.gov (United States)

    Chung, Hannah; Kim, Tae Yong; Lee, Sang Yup

    2012-12-01

    Spider silk has been drawing much attention as a great biomaterial having many applications in biotechnology and biomedicine owing to its several desired material characteristics such as outstanding strength, toughness, and elasticity as well as biodegradability and biocompatibility. With various applications foreseeable in industry, there has been much effort to produce recombinant spider silk protein in large amounts. However, owing to the difficulties in its production using spiders, alternative host systems and engineering methods have been investigated to develop suitable production systems that can efficiently produce spider silk protein. Here, we review recent advances in production of spider silk proteins in various heterologous host systems with focus given on the development of metabolic and cellular engineering strategies. PMID:22521455

  9. Thermally induced changes in dynamic mechanical properties of native silks.

    Science.gov (United States)

    Guan, Juan; Porter, David; Vollrath, Fritz

    2013-03-11

    Dynamic mechanical thermal analysis (DMTA) on individual native silk fibers demonstrates changes in the dynamic mechanical properties of storage modulus and loss tangent as a function of temperature and temperature history ranging from -100 to 250 °C. These property changes are linked quantitatively to two main types of change in the silk structure. First, the evaporation of water with increasing temperature up to 100 °C increases the storage modulus and removes two characteristic loss tangent peaks at -60 and +60 °C. Second, various discrete loss tangent peaks in the range 150-220 °C are associated with specific disordered silk structures that are removed or converted to a limiting high-temperature relaxed structure by the combination of increasing temperature and static load in the DMTA tests. The results identify important origins of silk filament quality based on the analysis of measurements that can be traced back to differences in production and processing history. PMID:23405856

  10. Effects of the blended fibroin/aloe gel film on wound healing in streptozotocin-induced diabetic rats

    International Nuclear Information System (INIS)

    Delayed healing remains a major clinical problem and here we have sought to develop an improved dressing film comprising 1.95% w/v fibroin and 0.05% w/v aloe gel extract. The tensile strength of dry film was 21.1 ± 0.5 MPa and broke at 1.1 ± 0.2% elongation; corresponding values for wet film were 18.3 ± 1.3 MPa and 1.9 ± 0.1%. The film maintained its shape upon water immersion and the swelling ratio of the dry film was 0.8 ± 0.1 while the water uptake was 43.7 ± 2.6%. After 28 days of incubation in phosphate buffered saline (1 M, pH 7.4, 37 °C), the weight of film was reduced by 6.7 ± 1.1% and the tensile strength and elongation at breaking point (dry state) were 15.4 ± 0.6 MPa and 1.5 ± 0.2%, respectively. Compared to aloe-free fibroin film (2.0% fibroin extract only), the blended film enhanced the attachment and proliferation of skin fibroblasts. The bFGF immunofluorescence of fibroblasts cultured on the blended film appeared greater than those cultured on tissue culture plate or on aloe-free fibroin film while ?-smooth muscle actin was maintained. In streptozotocin-induced diabetic rats, the wounds dressed with the blended film were smaller (p <0.05) by day 7 after wounding, compared to untreated diabetic wounds. Histology of repaired diabetic wounds showed the fibroblast distribution and collagen fiber organization to be similar to wounds in normal rats, and this was matched by enhanced hydroxyproline content. Thus, such accelerated wound healing by the blended fibroin/aloe gel films may find application in treatment of diabetic non-healing skin ulcers. (paper)

  11. The Cultural Exchange between Sino-Western: Silk Trade in Han Dynasty

    OpenAIRE

    Xiaoyan Wang; Jinsuo Zhao

    2012-01-01

    As we all know, the Silk Road, as a famous ancient transportation route, was a trade line cross-Eurasian continent in history. Its name was from the delivery of silk. However, no Chinese ancient documents mentioned the name of “Silk Road”. German F. V. Richthofen (1933-1905) firstly used the term “Silk Road” in his book China, published in 1877. Afterwards, the name of “Silk Road” has been accepted universally and used by the world widely. The Silk Road was an ancient business channel, across...

  12. The Silk Industry Of Assam Its Origin, Growth And Importance In The Economy Of Assam

    Directory of Open Access Journals (Sweden)

    Rekha Kalita

    2013-07-01

    Full Text Available Silk has been recogniged as a textile fibre. Sericulture, on which the silk industry survives, is an agroindustry, the end product of which is silk. It provides jobs and generates income in the rural areas. Assam is the only place where muga silk is produced and is well known for silk textiles both mulberry,muga and endi textiles. The silk weavers possess the very highest skill in their craft and it is probable that under competent and energetic direction with the assistance of capital, the industry could be revived and extended.

  13. Biosynthesis of an amphiphilic silk-like polymer

    OpenAIRE

    Werten, M. W. T.; Moers, A. P. H. A.; Vong, T.H.; Zuilhof, H.; van Hest, J.C.M.; Wolf, F.A. de

    2008-01-01

    An amphiphilic silk-like protein polymer was efficiently produced in the yeast Pichia pastoris. The secreted product was fully intact and was purified by solubilization in formic acid and subsequent precipitation of denatured host proteins upon dilution with water. In aqueous alkaline solution, the negatively charged acidic polymer assumed extended helical (silk III-like) and unordered conformations. Upon subsequent drying, it assumed a conformation rich in ß-turns. In water at low pH, the un...

  14. Characterisation of phenol oxidase and peroxidase from maize silk.

    Science.gov (United States)

    Sukalovi?, V Hadzi-Taskovi?; Veljovi?-Jovanovi?, S; Maksimovi?, J Dragisi?; Maksimovi?, V; Paji?, Z

    2010-05-01

    Silk of some maize genotypes contains a high level of phenolics that undergo enzymatic oxidation to form quinones, which condense among themselves or with proteins to form brown pigments. Two phenolic oxidizing enzymes, peroxidase (POD; EC 1.11.1.7) and polyphenol oxidase (PPO; EC 1.10.3.1), from maize (Zea mays L.) silk were characterised with respect to their preferred substrate, different isoforms and specific effectors. One browning silk sample with high, and two non-browning samples with low phenolic content were investigated. Although POD oxidizes a wide range of phenolic substrates in vitro, its activity rate was independent of silk phenolic content. PPO activity, detected with o-diphenolic substrates, was abundant only in browning silk, and low or absent in non-browning silk. Pollination increased POD but not PPO activity. Isoelectric-focusing (IEF) and specific staining for POD and PPO showed a high degree of polymorphism that varied with silk origin. The IEF pattern of POD revealed a number of anionic and several cationic isoenzymes, with the most pronounced having neutral pI 7 and a basic isoform with pI 10. Detected isoforms of PPO were anionic, except for one neutral form found only in browning silk, and occupied positions different from those of POD. Different inhibitory effects of NaN(3), EDTA, KCN, and L-cysteine, as well as different impacts of a variety of cations on the oxidation of chlorogenic acid, mediated by PPO or POD, were detected. The findings are discussed in terms of a possible roles of these enzymes in defence and pollination. PMID:20522176

  15. Recombinant spider silk particles as drug delivery vehicles.

    Science.gov (United States)

    Lammel, Andreas; Schwab, Martin; Hofer, Markus; Winter, Gerhard; Scheibel, Thomas

    2011-03-01

    Spider silk has been in the focus of research mainly due to the superior mechanical characteristics of silk fibers. However, it has been previously shown that spider silk proteins can also adopt other morphologies such as submicroparticles. This study examines the applicability of such particles as drug carriers. Particle characterization revealed that particles made of the engineered spider silk protein eADF4(C16) are colloidally stable in solution. Here, it is shown that small molecules with positive net-charge can diffuse into the negatively charged spider silk protein matrix driven by electrostatic interactions. The loading efficiencies correlate with the distribution coefficient (logD) of small molecules of weak alkaline nature. Interestingly, constant release rates can be realized for a period of two weeks at physiological conditions in vitro, with accelerated release rates within acidic environments. Enzymatic degradation studies of eADF4(C16) particles indicated that the silk proteins degrade slowly and the particles decrease in size. Along with their all-aqueous and easy preparation, drug loaded eADF4(C16) particles provide a high potential for diverse applications in which controlled release from biodegradable carriers is desired. PMID:21186052

  16. Recombinant spider silk genetically functionalized with affinity domains.

    Science.gov (United States)

    Jansson, Ronnie; Thatikonda, Naresh; Lindberg, Diana; Rising, Anna; Johansson, Jan; Nygren, Per-Åke; Hedhammar, My

    2014-05-12

    Functionalization of biocompatible materials for presentation of active protein domains is an area of growing interest. Herein, we describe a strategy for functionalization of recombinant spider silk via gene fusion to affinity domains of broad biotechnological use. Four affinity domains of different origin and structure; the IgG-binding domains Z and C2, the albumin-binding domain ABD, and the biotin-binding domain M4, were all successfully produced as soluble silk fusion proteins under nondenaturing purification conditions. Silk films and fibers produced from the fusion proteins were demonstrated to be chemically and thermally stable. Still, the bioactive domains are concluded to be folded and accessible, since their respective targets could be selectively captured from complex samples, including rabbit serum and human plasma. Interestingly, materials produced from mixtures of two different silk fusion proteins displayed combined binding properties, suggesting that tailor-made materials with desired stoichiometry and surface distributions of several binding domains can be produced. Further, use of the IgG binding ability as a general mean for presentation of desired biomolecules could be demonstrated for a human vascular endothelial growth factor (hVEGF) model system, via a first capture of anti-VEGF IgG to silk containing the Z-domain, followed by incubation with hVEGF. Taken together, this study demonstrates the potential of recombinant silk, genetically functionalized with affinity domains, for construction of biomaterials capable of presentation of almost any desired biomolecule. PMID:24678858

  17. Silk fabrics in the management of atopic dermatitis.

    Science.gov (United States)

    Ricci, Giampaolo; Neri, Iria; Ricci, Lorenza; Patrizi, Annalisa

    2012-03-01

    Many factors may worsen atopic dermatitis (AD) including sweating, skin infections, food, inhalant allergens, climatic conditions, stress, and chemical or physical irritants. Especially in children, clothing can be an effective barrier against flare-inducing factors and persistent scratching, allowing more rapid improvement of the eczematous lesions. On the contrary, some fabrics used for clothing may exacerbate skin conditions due to their rough fibers, such as wool and nylon. Conventional silk has smooth fibers that are generally woven for textiles in the manufacturing of clothes, but this material is not particularly useful in the management of children with AD since it reduces transpiration and may cause discomfort. Herein, we evaluate the data concerning a special silk fabric (MICROAIR DermaSilk®) shown to be suitable for patients with AD. The unique properties of this knitted silk allow the skin to breathe and lack irritative potential. Moreover, this fabric is treated with a water-resistant antimicrobial finish known as AEGIS AEM 5772/5. This novel knitted silk fabric appears to be useful in managing children with AD due to its non-irritating and antibacterial features. Additionally, a synthetic silk-like fabric (DermaTherapy®) has received US FDA clearance as a Class I medical device and is commercially available as bedding; their use by AD patients has shown interesting results. PMID:22446819

  18. Silk Patterns: Conservation and Development of Traditional Thai silk Production for Added Commercial Value in Khon Kaen Province

    OpenAIRE

    Kasinee Sawasdee; Boonsom Yodmalee; Kosit Phaengsoi

    2014-01-01

    Silk patterns are examples of fine art that show the valuable culture and identity of Thai communities. This is a qualitative research and the researchers used a purposive sampling technique to identify four districts in Khon Kaen province for assessment by means of survey, observation, interview, focus group discussion and workshop. The history and development of silk patterns in Khon Kaen province occurred from a process of pattern making called mudmee. The techniques were passed from gener...

  19. Chapter 13. Adrenal glands

    International Nuclear Information System (INIS)

    The condition of isotopic methods to the functional and morphological exploration of the adrenal glands is shown, with emphasis on the fact that althought the cortico-adrenal responds to these methods the same does not apply to the medullo-adrenal, which expresses its morphological changes by producing deformations on the cortical image. Funtional tests, mainly directed at the cortico-adrenal, are described first: study of exchangeable sodium and potassium; determination of the plasma concentration and metabolic clearance of some steroid hormones (cortisol, corticosterone, aldosterone); evaluation of the renin activity. These tests are based on competitive analysis and radioimmunological methods. Morphological tests are examined next. Adrenal scintigraphy uses a simple technique (intraveinous administration of 131I 19-iodocholesterol with no special preliminary preparation) which gives good images and is only limited now by the need to avoid over exposure of the gonads to ionising radiations

  20. Pituitary gland tumors; Hypophysentumoren

    Energy Technology Data Exchange (ETDEWEB)

    Jesser, J.; Schlamp, K.; Bendszus, M. [Radiologische Klinik, Universitaetsklinikum Heidelberg, Abteilung fuer Neuroradiologie, Heidelberg (Germany)

    2014-10-15

    This article gives an overview of the most common tumors of the pituitary gland and the differential diagnostics with special emphasis on radiological diagnostic criteria. A selective search of the literature in PubMed was carried out. Pituitary adenomas constitute 10-15 % of all intracranial tumors and are the most common tumors of the sellar region. Tumors smaller than 1 cm in diameter are called microadenomas while those larger than 1 cm in diameter are called macroadenomas. Approximately 65 % of pituitary gland adenomas secrete hormones whereby approximately 50 % secrete prolactin, 10 % secrete growth hormone (somatotropin) and 6 % secrete corticotropin. Other tumors located in the sella turcica can also cause endocrinological symptoms, such as an oversecretion of pituitary hormone or pituitary insufficiency by impinging on the pituitary gland or its stalk. When tumors spread into the space cranial to the sella turcica, they can impinge on the optic chiasm and cause visual disorders. A common differential diagnosis of a sellar tumor is a craniopharyngeoma. In children up to 10 % of all intracranial tumors are craniopharyngeomas. Other differential diagnoses for sellar tumors are metastases, meningiomas, epidermoids and in rare cases astrocytomas, germinomas or Rathke cleft cysts As these tumors are located in an anatomically complex region of the skull base and are often very small, a highly focused imaging protocol is required. The currently favored modality is magnetic resonance imaging (MRI) with the administration of a contrast agent. The sellar region should be mapped in thin slices. In cases of suspected microadenoma the imaging protocol should also contain a sequence with dynamic contrast administration in order to assess the specific enhancement characteristics of the tumor and the pituitary gland. (orig.) [German] Diese Arbeit ist eine Uebersicht ueber die haeufigsten Hypophysentumoren und deren Differenzialdiagnosen mit Augenmerk auf die radiologischen Diagnosekriterien. Selektive Literaturrecherche in PubMed. Hypophysenadenome umfassen 10-15 % aller intrakranieller Tumoren und die haeufigsten Tumoren der Hypophysenregion. Sind sie kleiner als 1 cm im Durchmesser, werden sie als Mikroadenome bezeichnet, bei ueber 1 cm im Durchmesser nennt man sie Makroadenome. Hypophysenadenome sind in der Mehrzahl der Faelle, in etwa 65 %, hormonaktiv. Die meisten, das sind fast 50 % aller Hypophysenadenome, sezernieren Prolaktin, seltener mit 10 % Somatotropin und mit 6 % Kortikotropin. Auch andere Tumoren mit Lage in der Sella turcica koennen durch die Verdraengung des Hypophysengewebes oder des Hypophysenstiels eine endokrinologische Symptomatik bedingen. Dies kann eine hypophysaere Hormonueberproduktion oder eine Hypophyseninsuffizienz sein. Breiten sich Tumoren ueber das sellaere Niveau nach kranial aus, kann es durch den Druck auf das Chiasma opticum zu Sehstoerungen kommen. Eine wichtige Differenzialdiagnose eines sellaeren Tumors ist das Kraniopharyngeom. Bei Kindern macht es bis zu 10 % aller intrakranieller Tumoren aus. Weitere Differenzialdiagnosen fuer sellaere Tumoren sind Metastasen, Meningeome, Epidermoide und seltener Astrozytome, Germinome und Rathke-Taschen-Zysten. Die Lage der Tumoren in einer anatomisch komplexen Region an der Schaedelbasis und die haeufig nur sehr kleinen Tumoren erfordern eine gezielte Bildgebung. Die Methode der Wahl ist die MRT mit Kontrastmittel, welche die Hypophysenregion in feiner Schichtung abdeckt. Bei Verdacht auf ein Mikroadenom sollte auch eine dynamische Kontrastmittelanflutung durchgefuehrt werden, um die tumor- und hypophysenspezifischen Anreicherungseigenschaften beurteilen zu koennen. (orig.)

  1. The Potential of Silk and Silk-Like Proteins as Natural Mucoadhesive Biopolymers for Controlled Drug Delivery

    Science.gov (United States)

    Brooks, Amanda E.

    2015-01-01

    Drug delivery across mucus membranes is a particularly effective route of administration due to the large surface area. However, the unique environment present at the mucosa necessitates altered drug formulations designed to (1) deliver sensitive biologic molecules, (2) promote intimate contact between the mucosa and the drug, and (3) prolong the drug's local residence time. Thus, the pharmaceutical industry has an interest in drug delivery systems formulated around the use of mucoadhesive polymers. Mucoadhesive polymers, both synthetic and biological, have a history of use in local drug delivery. Prominently featured in the literature are chitosan, alginate, and cellulose derivatives. More recently, silk and silk-like derivatives have been explored for their potential as mucoadhesive polymers. Both silkworms and spiders produce sticky silk-like glue substances, sericin and aggregate silk respectively, that may prove an effective, natural matrix for drug delivery to the mucosa. This mini review will explore the potential of silk and silk-like derivatives as a biocompatible mucoadhesive polymer matrix for local controlled drug delivery.

  2. Genetic Mystery of Behcet's Disease Unfolds Along the Ancient Silk Road

    Science.gov (United States)

    ... mystery of Behcet’s disease unfolds along the ancient Silk Road NIH researchers identify new gene variants associated with ... found predominantly in people with ancestors along the Silk Road. For nearly 2,000 years, traders used this ...

  3. Mucoepidermoid carcinoma of the thyroid gland.

    OpenAIRE

    Wan Abdul Rahman, Wan Faiziah; Anani Aila MAT ZAIN; Irfan MOHAMAD; Balasubramanian, Anusha; Nur Asyilla CHE JALIL

    2013-01-01

    Mucoepidermoid carcinoma (MEC) of the thyroid gland either primary or metastatic is extremely rare. However, MEC is the most common malignant tumour of the salivary glands with the majority originating from the parotid gland. We report the case of a 54-year-old Malay lady who presented with recurrent MEC affecting the thyroid gland two years after being treated for primary parotid MEC.

  4. Bilateral submandibular gland lymphoma in Sjögren's syndrome.

    OpenAIRE

    Law, N. W.; Leader, M

    1987-01-01

    Salivary gland lymphoma is associated with Sjögren's syndrome. A case of bilateral submandibular gland and sublingual gland lymphoma, arising in Sjögren's syndrome, is presented. A lymphoma involving more than one salivary gland may occur in Sjögren's syndrome, and there is an increased risk of developing an extrasalivary lymphoma.

  5. Synthetic spider silk production on a laboratory scale.

    Science.gov (United States)

    Hsia, Yang; Gnesa, Eric; Pacheco, Ryan; Kohler, Kristin; Jeffery, Felicia; Vierra, Craig

    2012-01-01

    As society progresses and resources become scarcer, it is becoming increasingly important to cultivate new technologies that engineer next generation biomaterials with high performance properties. The development of these new structural materials must be rapid, cost-efficient and involve processing methodologies and products that are environmentally friendly and sustainable. Spiders spin a multitude of different fiber types with diverse mechanical properties, offering a rich source of next generation engineering materials for biomimicry that rival the best manmade and natural materials. Since the collection of large quantities of natural spider silk is impractical, synthetic silk production has the ability to provide scientists with access to an unlimited supply of threads. Therefore, if the spinning process can be streamlined and perfected, artificial spider fibers have the potential use for a broad range of applications ranging from body armor, surgical sutures, ropes and cables, tires, strings for musical instruments, and composites for aviation and aerospace technology. In order to advance the synthetic silk production process and to yield fibers that display low variance in their material properties from spin to spin, we developed a wet-spinning protocol that integrates expression of recombinant spider silk proteins in bacteria, purification and concentration of the proteins, followed by fiber extrusion and a mechanical post-spin treatment. This is the first visual representation that reveals a step-by-step process to spin and analyze artificial silk fibers on a laboratory scale. It also provides details to minimize the introduction of variability among fibers spun from the same spinning dope. Collectively, these methods will propel the process of artificial silk production, leading to higher quality fibers that surpass natural spider silks. PMID:22847722

  6. Recombinant Minimalist Spider Wrapping Silk Proteins Capable of Native-Like Fiber Formation

    OpenAIRE

    Xu, Lingling; Rainey, Jan K.; Meng, Qing; Liu, Xiang-Qin

    2012-01-01

    Spider silks are desirable biomaterials characterized by high tensile strength, elasticity, and biocompatibility. Spiders produce different types of silks for different uses, although dragline silks have been the predominant focus of previous studies. Spider wrapping silk, made of the aciniform protein (AcSp1), has high toughness because of its combination of high elasticity and tensile strength. AcSp1 in Argiope trifasciata contains a 200-aa sequence motif that is repeated at least 14 times....

  7. Spider silks: recombinant synthesis, assembly, spinning, and engineering of synthetic proteins

    OpenAIRE

    Scheibel Thomas

    2004-01-01

    Abstract Since thousands of years humans have utilized insect silks for their own benefit and comfort. The most famous example is the use of reeled silkworm silk from Bombyx mori to produce textiles. In contrast, despite the more promising properties of their silk, spiders have not been domesticated for large-scale or even industrial applications, since farming the spiders is not commercially viable due to their highly territorial and cannibalistic nature. Before spider silks can be copied or...

  8. Blueprint for a High-Performance Biomaterial: Full-Length Spider Dragline Silk Genes

    OpenAIRE

    Ayoub, Nadia A.; Garb, Jessica E; Tinghitella, Robin M.; Collin, Matthew A.; Hayashi, Cheryl Y

    2007-01-01

    Spider dragline (major ampullate) silk outperforms virtually all other natural and manmade materials in terms of tensile strength and toughness. For this reason, the mass-production of artificial spider silks through transgenic technologies has been a major goal of biomimetics research. Although all known arthropod silk proteins are extremely large (>200 kiloDaltons), recombinant spider silks have been designed from short and incomplete cDNAs, the only available sequences. Here we describe th...

  9. Silk material modification and microfabrication strategies for applications in biosensors and drug delivery

    Science.gov (United States)

    Tsioris, Konstantinos

    Silk has proven to be a promising biomaterial for the development of a novel generation of biomedical devices due to the material's intrinsic properties of biocompatibility and biodegradability. To further the development of silk-based devices, augmented functionality can be provided to silk by means of microfabrication and material functionalization. In this dissertation, we set out to explore possibilities of silk-based biomedical device development with particular attention to different fabrication strategies that can be leveraged for this purpose, taking inspiration from conventional lithography, contact imprinting and chemical modification of the silk biomaterial. In particular, we have produced a novel silk-based drug delivery device, in the form of microneedles. For this purpose we have developed micromolding strategies which allow the fabrication of high aspect ratio silk structures. Furthermore, we have produced a THz split ring resonator based sensor device on silk films. To realize this device, we have developed a convenient fabrication method, allowing transfer of previously microfabricated metal and oxide microstructures to the silk film surface. This method has proven useful for hard masking and patterning silk films with reactive ion etching. Moreover, we have explored patterning semiconductor and glass substrates with silk films. For this purpose we have modified a standard microfabrication method -lift off- to be amendable to silk. Furthermore, combining silk based fabrication and material functionalization has lead to microfluidics pH sensing applications. Finally we have explored the possibility of utilizing silk for injectable and biodegradable glucose sensors. For this purpose, we have doped silk hydrogels with a fluorescence based protein biosensor. The advanced silk fabrication and material synthesis strategies and the resulting novel devices presented here could potentially lead to a new class of biomedical applications.

  10. Characterization, phase behavior and processing of silk proteins for controlled drug delivery

    OpenAIRE

    Lammel, Andreas Stephan

    2010-01-01

    Due to their extraordinary mechanical properties along with its biocompatibility and biodegradability silk based materials have a high potential for biomedical applications. The thesis reports on the characterization, phase behavior and processing of recombinantly produced engineered spider silk proteins and regenerated mulberry silkworm silk for the development of colloidal drug carriers The results illustrate that silk particle properties as well as their release behavior can be controlled ...

  11. Salivary Gland Cancer: Risk Factors

    Science.gov (United States)

    ... Request Permissions Print to PDF Salivary Gland Cancer: Risk Factors Approved by the Cancer.Net Editorial Board , 08/ ... menu on the side of your screen. A risk factor is anything that increases a person’s chance of ...

  12. The Effects of Silk Protein Solution on Quality of Mangosteen

    International Nuclear Information System (INIS)

    Full text: Sericin silk protein solution prepared from irradiated silk waste was applied as a wax coating on mangosteen fruits but was found not appropriate. Nonetheless, when the solution was sprayed onto fruits from the setting stage till maturity, it enhanced the fruit quality. Fruits showed a bigger stalk and greener, thicker and larger-angled calyx than untreated ones. They were edible after being kept at 25C for 3 to 4 weeks. Fruits sprayed with the silk protein solution and untreated fruits were separately harvested and packed for export. A half of them were irradiated with gamma radiation for insect eradication and then kept at 10C with 80 percents relative humidity. The unirradiated half was stored similarly. Results showed that rind color of irradiated fruits changed slower than unirradiated ones. However, silk protein solution spraying and irradiation did not affect fruit firmness and total soluble solids of mangosteen flesh. For sensory evaluation, it was found that sprayed and irradiated fruits showed no differences from the untreated ones in their physical properties, color, taste and odor. Fruits sprayed with the silk protein solution without irradiation had the longest shelf life of 6 weeks

  13. Extracted sericin from silk waste for film formation

    Directory of Open Access Journals (Sweden)

    Rungsinee Sothornvit

    2010-03-01

    Full Text Available Sericin is the second main component in cocoons, which are removed in the silk reeling process of the raw silk industry and in the silk waste degumming of the spun silk industry. The main amino acid of sericin, serine, exhibits a skin moisturing and antiwrinkle action, which is interesting to use for film formation in this study. The extraction conditions of sericin from two silk wastes, pieced cocoon and inferior knubbs were studied to find the optimum extraction conditions. Boiling water extraction was considered based on the response surface methodology (RSM in order to identify the important factors for the sericin extraction. The two factors considered were time and temperature. Both factors were needed to be independent parameters in the predicted equation in order to improve the model fit with R2 = 0.84. The components ofextracted sericin were 18.24% serine, 9.83% aspatate, and 5.51% glycine with a molecular weight of 132 kDa. Film formationfrom extracted sericin was carried out to find the optimum conditions. Extracted sericin could not form a stand-alonefilm. Therefore, polysaccharide polymers, such as glucomannan, were incorporated with glycerol to form a flexible film.Sericin-based films were characterized for its properties in terms of solubility and permeability before application. It wasfound that sericin-based films showed a film flexibility and solubility without an increasing film water vapor permeability.

  14. SilkDB: a knowledgebase for silkworm biology and genomics.

    DEFF Research Database (Denmark)

    Wang, Jing; Xia, Qingyou

    2005-01-01

    The Silkworm Knowledgebase (SilkDB) is a web-based repository for the curation, integration and study of silkworm genetic and genomic data. With the recent accomplishment of a approximately 6X draft genome sequence of the domestic silkworm (Bombyx mori), SilkDB provides an integrated representation of the large-scale, genome-wide sequence assembly, cDNAs, clusters of expressed sequence tags (ESTs), transposable elements (TEs), mutants, single nucleotide polymorphisms (SNPs) and functional annotations of genes with assignments to InterPro domains and Gene Ontology (GO) terms. SilkDB also hosts a set of ESTs from Bombyx mandarina, a wild progenitor of B.mori, and a collection of genes from other Lepidoptera. Comparative analysis results between the domestic and wild silkworm, between B.mori and other Lepidoptera, and between B.mori and the two sequenced insects, fruitfly and mosquito, are displayed by using B.mori genome sequence as a reference framework. Designed as a basic platform, SilkDB strives to provide a comprehensive knowledgebase about the silkworm and present the silkworm genome and related information in systematic and graphical ways for the convenience of in-depth comparative studies. SilkDB is publicly accessible at http://silkworm.genomics.org.cn. Udgivelsesdato: 2005-Jan-1

  15. Surgical Removal of the Thyroid Gland

    Medline Plus

    Full Text Available ... off any possibility of thyroid cancer down the road. We’re about three-quarters of the way ... re permanent? No, these are permanent, these are silk, and they will stay there. Uh- huh. And ...

  16. [Disinfection of surgical silk with decamethoxin, antibiotics and their combinations].

    Science.gov (United States)

    Pali?, G K; Iukhimel, A D; Onofre?chuk, I F

    1978-07-01

    The disinfecting effect of decametoxin, antibiotics, such as bensylpenicillin, streptomycin, monomycin and their combinations was studied on surgical threads of various thickness previously infected with Staph. aureus, Pr. vulgaris, Bac. anthracis, E. coli, Ps. aeruginosa and Bac. subtilis. It was shown that disinfection of the surgical silk with 0.1% solution of decametoxin for 15 minutes followed by its treatment with an antibiotic solution for 105 minutes provided absolute sterility. Treatment of the surgical silk with decametoxin and antibiotic combinations alone did not provide absolute destruction of the above test-microbes. It was found that treatment of the silk with 0.1% decametoxin solution for 24 hours did not decrease its strength. PMID:677853

  17. Nanomaterial building blocks based on spider silk-oligonucleotide conjugates.

    Science.gov (United States)

    Humenik, Martin; Scheibel, Thomas

    2014-02-25

    Self-assembling protein nanofibrils are promising structures for the "bottom-up" fabrication of bionanomaterials. Here, the recombinant protein eADF4(C16), a variant of Araneus diadematus dragline silk ADF4, which self-assembles into nanofibrils, and short oligonucleotides were modified for site-specific azide-alkyne coupling. Corresponding oligonuleotide-eADF4(C16) "click" conjugates were hybridized in linear or branched fashion according to the designed complementarities of the DNA moieties. Self-assembly properties of higher ordered structures of the spider silk-DNA conjugates were dominated by the silk component. Assembled ?-sheet rich conjugate fibrils were similar in appearance to fibrils of unmodified eADF4(C16) but enabled the specific attachment of neutravidin-modified gold nanoparticles on their surface directed by complementary biotin-oligonucleotides, providing the basis for functionalization of such conjugates. PMID:24405063

  18. Rapid nano impact printing of silk biopolymer thin films

    International Nuclear Information System (INIS)

    In this paper, nano impact printing of silk biopolymer films is described. An indenter is rapidly accelerated and transfers the nanopattern from a silicon master into the silk film during an impact event that occurs in less than 1 ms. Contact stresses of greater than 100 MPa can be achieved during the short impact period with low power and inexpensive hardware. Ring shaped features with a diameter of 2 µm and a ring width of 100–200 nm were successfully transferred into untreated silk films using this method at room temperature. Mechanical modeling was carried out to determine the contact stress distribution, and demonstrates that imprinting can occur for contact stresses of less than 2 MPa. Thermal characterization at the impact location shows that raising the temperature to 70 °C has only a limited effect on pattern transfer. Contact stresses of greater than approximately 100 MPa result in excessive deformation of the film and poor pattern transfer.

  19. Production of synthetic spider dragline silk protein in Pichia pastoris.

    Science.gov (United States)

    Fahnestock, S R; Bedzyk, L A

    1997-01-01

    The methylotrophic yeast Pichia pastoris was tested as a host for the production of long, repetitive protein polymers. Synthetic genes for a designed analog of a spider dragline silk protein were readily expressed at high levels under control of the methanol-inducible AOX1 promoter. Transformants containing multiple gene copies produced elevated levels of silk protein, but of a variety of altered sizes as a result of gene rearrangements at the time of transformation. Genes up to 3000 codons in length or longer could be expressed with no evidence of the prevalent truncated synthesis observed for similar genes in Escherichia coli, though genes longer than 1600 codons were expressed less efficiently than shorter genes. Silk-producing P. pastoris strains were stable without selection for at least 100 doublings. PMID:9035408

  20. Presence of phosphorus in Nephila clavipes dragline silk.

    OpenAIRE

    Michal, C A; Simmons, A H; Chew, B G; Zax, D B; Jelinski, L W

    1996-01-01

    Solid-state 31P-NMR of Nephila clavipes dragline silk indicates the presence of phosphorus in at least two chemically distinct environments. Amino acid analyses of acid-hydrolyzed silk confirm the presence of phosphotyrosine as one of the phosphorus-containing components. The unusual chemical shift (18.9 ppm downfield from 85% H3PO4), proton chemical shift, and acid lability of a second component suggest that it is part of a strained five-membered cyclic phosphate that might be found on a bet...

  1. The Algorithm to Detect Color Gradation on Silk

    Directory of Open Access Journals (Sweden)

    Suyoto

    2012-03-01

    Full Text Available The process of silk dyeing with natural dye extracts will produce a certain color. Using extracts of wood, leaf and their combinations will give some color gradations. This paper aims to create a new algorithm which can help one, whose intention is to formulate the combination of coloring process to achieve the desired color through combining coloring materials on silk fabric. This algorithm will be expected to be able to formulate the combination of colors with more than 75 percent of accuracy. The natural dyes used were Ceriops candolleana arn wood for the red, Cudraina javanensis wood for the yellow, and indigofera leaf for the blue base color.

  2. Restoring the Asian Silk Route: Toward an integrated Asia

    OpenAIRE

    Bhattacharyay, Biswa N.; De, Prabir

    2009-01-01

    Until the 13th century, the ancient Silk Route of Asia was the world's most important cross-border artery, at a time when Asia was a major trade and economic center of the world. The Silk Road refers to an extensive pan-Asia interconnected network of trade routes across the Asian continent connecting Eastern, Southern, Central, and Western Asia with the Mediterranean, including North Africa and Europe. Over the past decades of globalization, Asia has re-emerged as one of the major economic po...

  3. Silk reinforced with graphene or carbon nanotubes spun by spiders

    OpenAIRE

    Lepore, Emiliano; Bonaccorso, Francesco; Bruna, Matteo; Bosia, Federico; Taioli, Simone; Garberoglio, Giovanni; Ferrari, Andrea C.; Pugno, Nicola Maria

    2015-01-01

    Here, we report the production of silk incorporating graphene and carbon nanotubes directly by spider spinning, after spraying spiders with the corresponding aqueous dispersions. We observe a significant increment of the mechanical properties with respect to the pristine silk, in terms of fracture strength, Young's and toughness moduli. We measure a fracture strength up to 5.4 GPa, a Young's modulus up to 47.8 GPa and a toughness modulus up to 2.1 GPa, or 1567 J/g, which, to...

  4. Neural control of shark rectal gland.

    Science.gov (United States)

    Stoff, J S; Silva, P; Lechan, R; Solomon, R; Epstein, F H

    1988-08-01

    Veratrum alkaloids stimulated salt secretion by the isolated perfused rectal gland of Squalus acanthias. Stimulation by veratrine was prevented by the nerve channel blockers tetrodotoxin and procaine and was not evident in a preparation of dispersed rectal gland cells. Vasoactive intestinal peptide (VIP)-like immunoreactivity was detected by histological techniques in neuronal tissue within the rectal gland. Veratrine stimulation caused the release of immunoreactive VIP into the venous effluent of perfused glands. The stimulatory action of veratrine was inhibited by somatostatin, another neuropeptide known to be present in nerves of Squalus rectal gland. These findings suggest the likelihood of neural modulation of rectal gland function. PMID:2900607

  5. Selective Cryolysis of Sebaceous Glands.

    Science.gov (United States)

    Jalian, H Ray; Tam, Joshua; Vuong, Linh N; Fisher, Jeremy; Garibyan, Lilit; Mihm, Martin C; Zurakowski, David; Evans, Conor L; Anderson, R Rox

    2015-09-01

    Acne vulgaris is a nearly universal cutaneous inflammatory disease. Excess sebum production is an integral part of disease pathogenesis. Medical therapies that reduce sebum excretion result in clinical improvement of acne. Given the preferential susceptibility of lipid-containing cells to cold, we investigated the hypothesis that controlled local skin cooling causes preferential injury to sebaceous glands, in murine and swine models using a range of temperatures as low as -10?°C, and then on the backs of human subjects. In mouse ears, peak histologic damage occurred 72 hours after treatment; eosinophilic necrotic plugs formed within sebaceous glands, and the number of glands was significantly reduced up to 1 week post treatment. Cooling disrupted sebocyte cell membranes, alkaline phosphatase activity, and significantly reduced sebocyte lipid content. In human volunteers, cooling damaged sebaceous glands and reduced sebum output for 2 weeks, with minimal injury to surrounding tissues. Selective cryolysis of sebaceous glands is achievable through brief, non-invasive skin cooling, suggesting that controlled cooling could be developed as an effective treatment for acne vulgaris. PMID:25860384

  6. Sequential origin in the high performance properties of orb spider dragline silk

    Science.gov (United States)

    Blackledge, Todd A.; Pérez-Rigueiro, José; Plaza, Gustavo R.; Perea, Belén; Navarro, Andrés; Guinea, Gustavo V.; Elices, Manuel

    2012-01-01

    Major ampullate (MA) dragline silk supports spider orb webs, combining strength and extensibility in the toughest biomaterial. MA silk evolved ~376?MYA and identifying how evolutionary changes in proteins influenced silk mechanics is crucial for biomimetics, but is hindered by high spinning plasticity. We use supercontraction to remove that variation and characterize MA silk across the spider phylogeny. We show that mechanical performance is conserved within, but divergent among, major lineages, evolving in correlation with discrete changes in proteins. Early MA silk tensile strength improved rapidly with the origin of GGX amino acid motifs and increased repetitiveness. Tensile strength then maximized in basal entelegyne spiders, ~230?MYA. Toughness subsequently improved through increased extensibility within orb spiders, coupled with the origin of a novel protein (MaSp2). Key changes in MA silk proteins therefore correlate with the sequential evolution high performance orb spider silk and could aid design of biomimetic fibers. PMID:23110251

  7. More than one way to spin a crystallite: multiple trajectories through liquid crystallinity to solid silk.

    Science.gov (United States)

    Walker, Andrew A; Holland, Chris; Sutherland, Tara D

    2015-06-22

    Arthropods face several key challenges in processing concentrated feedstocks of proteins (silk dope) into solid, semi-crystalline silk fibres. Strikingly, independently evolved lineages of silk-producing organisms have converged on the use of liquid crystal intermediates (mesophases) to reduce the viscosity of silk dope and assist the formation of supramolecular structure. However, the exact nature of the liquid-crystal-forming-units (mesogens) in silk dope, and the relationship between liquid crystallinity, protein structure and silk processing is yet to be fully elucidated. In this review, we focus on emerging differences in this area between the canonical silks containing extended-?-sheets made by silkworms and spiders, and 'non-canonical' silks made by other insect taxa in which the final crystallites are coiled-coils, collagen helices or cross-?-sheets. We compared the amino acid sequences and processing of natural, regenerated and recombinant silk proteins, finding that canonical and non-canonical silk proteins show marked differences in length, architecture, amino acid content and protein folding. Canonical silk proteins are long, flexible in solution and amphipathic; these features allow them both to form large, micelle-like mesogens in solution, and to transition to a crystallite-containing form due to mechanical deformation near the liquid-solid transition. By contrast, non-canonical silk proteins are short and have rod or lath-like structures that are well suited to act both as mesogens and as crystallites without a major intervening phase transition. Given many non-canonical silk proteins can be produced at high yield in E. coli, and that mesophase formation is a versatile way to direct numerous kinds of supramolecular structure, further elucidation of the natural processing of non-canonical silk proteins may to lead to new developments in the production of advanced protein materials. PMID:26041350

  8. Osteoinductive-nanoscaled silk/HA composite scaffolds for bone tissue engineering application.

    Science.gov (United States)

    Huang, Xiaowei; Bai, Shumeng; Lu, Qiang; Liu, Xi; Liu, Shanshan; Zhu, Hesun

    2015-10-01

    Osteoinductive silk/hydroxyapatite (HA) composite scaffolds for bone regeneration were prepared by combining silk with HA/silk core-shell nanoparticles. The HA/silk nanoparticles were directly dispersed in silk solution to form uniform silk/HA blend and then composite scaffolds after a freeze-drying process. The HA/silk nanoparticles uniformly distributed in silk scaffolds at nanometer scale at varying HA content up to 40%, and substantially improved the compressive strength of the scaffolds produced. Rat bone mesenchymal stem cells (rBMSCs) were cultured in these scaffolds and cell proliferation was analyzed by confocal microscopy and DNA assay. Gene expression and biochemical assays were employed to study the influence of increasing HA/silk nanoparticles on in vitro osteogenic differentiation of rBMSCs. Increasing HA/silk nanoparticles inside silk scaffolds improved the growth and osteogenic capability of rBMSCs in the absence of osteogenic growth factors, and also significantly increased the calcium and collagen I deposition. In addition, compared to silk/HA composite scaffolds containing HA aggregates, the scaffolds loaded with HA/silk nanoparticles showed remarkably higher stiffness and better osteogenic property at same HA content, implying a preferable microenvironment for rBMSCs. These results suggest that the osteogenic property as well as mechanical property of silk/HA scaffolds could be further improved through fabricating their structure and topography at nanometer scale, providing more suitable systems for bone regeneration. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 1402-1414, 2015. PMID:25399838

  9. Structure to function: Spider silk and human collagen

    Science.gov (United States)

    Rabotyagova, Olena S.

    Nature has the ability to assemble a variety of simple molecules into complex functional structures with diverse properties. Collagens, silks and muscles fibers are some examples of fibrous proteins with self-assembling properties. One of the great challenges facing Science is to mimic these designs in Nature to find a way to construct molecules that are capable of organizing into functional supra-structures by self-assembly. In order to do so, a construction kit consisting of molecular building blocks along with a complete understanding on how to form functional materials is required. In this current research, the focus is on spider silk and collagen as fibrous protein-based biopolymers that can shed light on how to generate nanostructures through the complex process of self-assembly. Spider silk in fiber form offers a unique combination of high elasticity, toughness, and mechanical strength, along with biological compatibility and biodegrability. Spider silk is an example of a natural block copolymer, in which hydrophobic and hydrophilic blocks are linked together generating polymers that organize into functional materials with extraordinary properties. Since silks resemble synthetic block copolymer systems, we adopted the principles of block copolymer design from the synthetic polymer literature to build block copolymers based on spider silk sequences. Moreover, we consider spider silk to be an important model with which to study the relationships between structure and properties in our system. Thus, the first part of this work was dedicated to a novel family of spider silk block copolymers, where we generated a new family of functional spider silk-like block copolymers through recombinant DNA technology. To provide fundamental insight into relationships between peptide primary sequence, block composition, and block length and observed morphological and structural features, we used these bioengineered spider silk block copolymers to study secondary structure, morphological features and assembly. Aside from fundamental perspectives, we anticipate that these results will provide a blueprint for the design of precise materials for a range of potential applications such as controlled release devices, functional coatings, components of tissue regeneration materials and environmentally friendly polymers in future studies. In the second part of this work, human collagen type I was studied as another representative of the family of fibrous proteins. Collagen type I is the most abundant extracellular matrix protein in the human body, providing the basis for tissue structure and directing cellular functions. Collagen has a complex structural hierarchy, organized at different length scales, including the characteristic triple helical feature. In the present study we assessed the relationship between collagen structure (native vs. denatured) and sensitivity to UV radiation with a focus on changes in the primary structure, conformation, microstructure and material properties. Free radical reactions are involved in collagen degradation and a mechanism for UV-induced collagen degradation related to structure was proposed. The results from this study demonstrated the role of collagen supramolecular organization (triple helix) in the context of the effects of electromagnetic radiation on extracellular matrices. Owing to the fact that both silks and collagens are proteins that have found widespread interest for biomaterial related needs, we anticipate that the current studies will serve as a foundation for future biomaterial designs with controlled properties. Furthermore, fundamental insight into self-assembly and environmentally-2mediated degradation, will build a foundation for fundamental understanding of the remodeling and functions of these types of fibrous proteins in vivo and in vitro. This type of insight is essential for many areas of scientific inquiry, from drug delivery, to scaffolds for tissue engineering, and to the stability of materials in space.

  10. Salivary gland development and disease.

    Science.gov (United States)

    Mattingly, Aaron; Finley, Jennifer K; Knox, Sarah M

    2015-11-01

    Mammalian salivary glands synthesize and secrete saliva via a vast interconnected network of epithelial tubes attached to secretory end units. The extensive morphogenesis required to establish this organ is dependent on interactions between multiple cell types (epithelial, mesenchymal, endothelial, and neuronal) and the engagement of a wide range of signaling pathways. Here we describe critical regulators of salivary gland development and discuss how mutations in these impact human organogenesis. In particular, we explore the genetic contribution of growth factor pathways, nerve-derived factors and extracellular matrix molecules to salivary gland formation in mice and humans. WIREs Dev Biol 2015, 4:573-590. doi: 10.1002/wdev.194 For further resources related to this article, please visit the WIREs website. PMID:25970268

  11. Enhancing analysis of cells and proteins by fluorescence imaging on silk-based biomaterials: modulating the autofluorescence of silk.

    Science.gov (United States)

    Neo, Puay Yong; Tan, Daryl Jian-An; Shi, Pujiang; Toh, Siew Lok; Goh, James Cho-Hong

    2015-02-01

    Silk is a versatile and established biomaterial for various tissue engineering purposes. However, it also exhibits strong autofluorescence signals-thereby hindering fluorescence imaging analysis of cells and proteins on silk-derived biomaterials. Sudan Black B (SB) is a lysochrome dye commonly used to stain lipids in histology. It has also been reported to be able to quench autofluorescence of tissues in histology and has been tested on artificial biomedical polymers in recent years. It was hypothesized that SB would exert similar quenching effects on silk, modulating the autofluorescence signals, and thereby enabling improved imaging analysis of cells and molecules of interests. The quenching effect of SB on the intrinsic fluorescence properties of silk and on commercial fluorescent dyes were first investigated in this study. SB was then incorporated into typical fluorescence-based staining protocols to study its effectiveness in improving fluorescence-based imaging of the cells and proteins residing with the silk-based biomaterials. Silk processed into various forms of biomaterials (e.g., films, sponges, fibers, and electrospun mats) was seeded with cells and cultured in vitro. At sacrificial time points, specimens were harvested, fixed, and prepared for fluorescence staining. SB, available commercially as a powder, was dissolved in 70% ethanol (0.3% [w/v]) to form staining solutions. SB treatment was introduced at the last step of typical immunofluorescence staining protocols for 15-120?min. For actin staining protocols by phalloidin toxin, SB staining solutions were added before and after permeabilization with Triton-X for 15-30?min. Results showed that ideal SB treatment duration is about 15?min. Apart from being able to suppress the autofluorescence of silk, this treatment duration was also not too long to adversely affect the fluorescent labeling probes used. The relative improvement brought about by SB treatment was most evident in the blue and green emission wavelengths compared with the red emission wavelength. This study has showed that the use of SB is a cost and time effective approach to enhance fluorescence-based imaging analyses of cell-seeded silk biomaterials, which otherwise would have been hindered by the unmodulated autofluorescence signals. PMID:25050876

  12. Meibomian Gland Dysfunction and Treatment (Posterior Blepharitis)

    Science.gov (United States)

    ... evaporation. In a patient with Meibomian gland dysfunction (MGD), vision is affected because there is too much ... the tear film. What is Meibomian Gland Dysfunction? MGD, also termed posterior blepharitis, is the most common ...

  13. Interactions between developing nerves and salivary glands

    OpenAIRE

    Ferreira, João N; Hoffman, Matthew P.

    2013-01-01

    Our aim is to provide a summary of the field of salivary gland development and regeneration from the perspective of what is known about the function of nerves during these processes. The primary function of adult salivary glands is to produce and secrete saliva. Neuronal control of adult salivary gland function has been a focus of research ever since Pavlov’s seminal experiments on salivation in dogs. Less is known about salivary gland innervation during development and how the developing ner...

  14. Homeobox Genes in the Rodent Pineal Gland

    DEFF Research Database (Denmark)

    Rath, Martin Fredensborg; Rohde, Kristian; Klein, David C; Møller, Morten

    2013-01-01

    The pineal gland is a neuroendocrine gland responsible for nocturnal synthesis of melatonin. During early development of the rodent pineal gland from the roof of the diencephalon, homeobox genes of the orthodenticle homeobox (Otx)- and paired box (Pax)-families are expressed and are essential for normal pineal development consistent with the well-established role that homeobox genes play in developmental processes. However, the pineal gland appears to be unusual because strong homeobox gene expr...

  15. Nutrient deprivation induces property variations in spider gluey silk.

    Science.gov (United States)

    Blamires, Sean J; Sahni, Vasav; Dhinojwala, Ali; Blackledge, Todd A; Tso, I-Min

    2014-01-01

    Understanding the mechanisms facilitating property variability in biological adhesives may promote biomimetic innovations. Spider gluey silks such as the spiral threads in orb webs and the gumfoot threads in cobwebs, both of which comprise of an axial thread coated by glue, are biological adhesives that have variable physical and chemical properties. Studies show that the physical and chemical properties of orb web gluey threads change when spiders are deprived of food. It is, however, unknown whether gumfoot threads undergo similar property variations when under nutritional stress. Here we tested whether protein deprivation induces similar variations in spiral and gumfoot thread morphology and stickiness. We manipulated protein intake for the orb web spider Nephila clavipes and the cobweb spider Latrodectus hesperus and measured the diameter, glue droplet volume, number of droplets per mm, axial thread width, thread stickiness and adhesive energy of their gluey silks. We found that the gluey silks of both species were stickier when the spiders were deprived of protein than when the spiders were fed protein. In N. clavipes a concomitant increase in glue droplet volume was found. Load-extension curves showed that protein deprivation induced glue property variations independent of the axial thread extensions in both species. We predicted that changes in salt composition of the glues were primarily responsible for the changes in stickiness of the silks, although changes in axial thread properties might also contribute. We, additionally, showed that N. clavipes' glue changes color under protein deprivation, probably as a consequence of changes to its biochemical composition. PMID:24523902

  16. Antibiotic-Releasing Silk Biomaterials for Infection Prevention and Treatment

    OpenAIRE

    Eleanor M. Pritchard; Valentin, Thomas; Panilaitis, Bruce; Omenetto, Fiorenzo; Kaplan, David L.

    2012-01-01

    Effective treatment of infections in avascular and necrotic tissues can be challenging due to limited penetration into the target tissue and systemic toxicities. Controlled release polymer implants have the potential to achieve the high local concentrations needed while also minimizing systemic exposure. Silk biomaterials possess unique characteristics for antibiotic delivery including biocompatibility, tunable biodegradation, stabilizing effects, water-based processing and diverse material f...

  17. Silk cocoon drying in forced convection type solar dryer

    International Nuclear Information System (INIS)

    The thin layer silk cocoon drying was studied in a forced convection type solar dryer. The drying chamber was provided with several trays on which the cocoons loaded in thin layer. The hot air generated in the solar air heater was forced into drying chamber to avoid the direct exposure of sunlight and UV radiation on cocoons. The drying air temperature varied from 50 to 75 oC. The cocoon was dried from the initial moisture content of about 60-12% (wb). The drying data was fitted to thin layer drying models. Drying behaviour of the silk cocoon was best fitted with the Wang and Singh drying model. Good agreement was obtained between predicted and experimental values. Quality of the cocoons dried in the solar dryer was at par with the cocoons dried in the conventional electrical oven dryer in term of the silk yield and strength of the silk. Saving of electrical energy was about 0.75 kWh/kg cocoons dried. Economic analysis indicated that the NPV of the solar dryer was higher and more stable (against escalation rate of electricity) as compare to the same for electrical oven dryer. Due to simplicity in design and construction and significant saving of operational electrical energy, solar cocoon dryer seems to be a viable option.

  18. Teaching the Silk Road: A Journey of Pedagogical Discovery.

    Science.gov (United States)

    Andrea, A. J.; Mierse, William

    2002-01-01

    Describes a course for first-year college students that focuses on the Silk Road. Discusses the problems that occurs in such a course, types of resources used, basic strategies and tactics taken, and the focus on mapmaking in the beginning of the course. Includes an annotated bibliography. (CMK)

  19. Influence of Hybridization on the Traits of Silk Production and Filament Denier in Indian Tropical Tasar Silk Insect, Antheraea mylitta Drury

    Directory of Open Access Journals (Sweden)

    A.K. Srivastava

    2010-01-01

    Full Text Available The aim of the present study is to explore hybridization influence to achieve the potential of silk yield and quality in commercial tasarculture, as against the current status of applying only a few wild and semi-domesticated ecoraces of Antheraea mylitta D to produce raw silk during commercial crop rearing season (September-December. The four F1 hybrid combinations generated using Daba, Jata and Raily tasar ecoraces of seed crop rearing season (July-August were evaluated during commercial crop season of 2007 and 2008 for the influence of hybridization as positive heterosis in the traits of economically important silk productivity and filament denier. The F1 hybrid, Daba x Jata has recorded positive heterosis in single shell weight (+25.6%, total silk yield (+79.0% and silk filament length (+68.1%, but for silk filament of high denier (11.98 d followed by its reciprocal hybrid, JataxDaba in shell weight (+18.8%, silk yield (+68.1%, filament length (+63.8% and filament of highest denier (12.32 d. Though, the RailyxDaba hybrid could show highest heterosis in shell weight (2.47 g with filament of least denier (10.86 d, the improvement in filament length was marginal (+44.7% and heterosis in silk yield was negative (-47.0%, while the performance of DabaxRaily hybrid was least among the hybrids. The study infers hybridization influence on silk related traits at F1 level as positive heterosis and the application feasibility of DabaxJata and JataxDaba hybrids during commercial crop rearing season for higher silk productivity with silk filament denier at least better than one of the parents of F1 hybrid combination.

  20. Primary sebaceous gland carcinoma of pinna

    Directory of Open Access Journals (Sweden)

    Agarwal Akhilesh

    2009-01-01

    Full Text Available Sebaceous gland carcinoma is a rare cancer most commonly seen in the meibomian glands of the eyelid. It has predilection for periocular region and is rarely found in extra ocular sites. A case of sebaceous gland carcinoma over back of left pinna is reported.

  1. Spider silks: recombinant synthesis, assembly, spinning, and engineering of synthetic proteins

    Directory of Open Access Journals (Sweden)

    Scheibel Thomas

    2004-11-01

    Full Text Available Abstract Since thousands of years humans have utilized insect silks for their own benefit and comfort. The most famous example is the use of reeled silkworm silk from Bombyx mori to produce textiles. In contrast, despite the more promising properties of their silk, spiders have not been domesticated for large-scale or even industrial applications, since farming the spiders is not commercially viable due to their highly territorial and cannibalistic nature. Before spider silks can be copied or mimicked, not only the sequence of the underlying proteins but also their functions have to be resolved. Several attempts to recombinantly produce spider silks or spider silk mimics in various expression hosts have been reported previously. A new protein engineering approach, which combines synthetic repetitive silk sequences with authentic silk domains, reveals proteins that closely resemble silk proteins and that can be produced at high yields, which provides a basis for cost-efficient large scale production of spider silk-like proteins.

  2. Ultrasonography in salivary gland disease

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Eun Young; Cha, Soon Joo; Cha, Sang Hoon; Seol, Hae Young; Chung, Kyoo Byung; Suh, Won Hyuck [Korea University College of Medicine, Seoul (Korea, Republic of)

    1984-12-15

    Recently, CT scan, CT sialogram, radionuclide imaging and ultrasonogram are widely applicated in conjunction with conventional studies such as plain film, sialogram and arteriogram for the diagnosis of sailvary gland disease. Among them, ultrasonogram provides safe, noninvasive, and reliable way to diagnosis salivary gland disease. Authors evaluated ultrasonographic and sialographic findings of patients with suspected salivary gland disease in 16 cases at Korea University Hospital for 8 months. (from Dec. 1983 to Aug. 1984). The following results are observed. 1. final diagnosis of 16 cases were 2 cases of stone, 1 case of pleomorphic adenoma, 2 cases of neurilemmoma, 3 cases of chronic sialademitis, 1 case of abscess, 2 cases of Retention cyst, 1 case of pseudocyst, 1 case of tuberculous lymphadenopathy, and 3 cases of normal finding. 2. Diagnosis ultrasonogram provides accurate information of the size, location and character of the lesion, and differentiates intraglandular lesion from extraglandular ones. 3. Ultrasonogram is one of convenient, reliable and initial modality for the diagnosis of salivary gland disease.

  3. Ultrasonography in salivary gland disease

    International Nuclear Information System (INIS)

    Recently, CT scan, CT sialogram, radionuclide imaging and ultrasonogram are widely applicated in conjunction with conventional studies such as plain film, sialogram and arteriogram for the diagnosis of sailvary gland disease. Among them, ultrasonogram provides safe, noninvasive, and reliable way to diagnosis salivary gland disease. Authors evaluated ultrasonographic and sialographic findings of patients with suspected salivary gland disease in 16 cases at Korea University Hospital for 8 months. (from Dec. 1983 to Aug. 1984). The following results are observed. 1. final diagnosis of 16 cases were 2 cases of stone, 1 case of pleomorphic adenoma, 2 cases of neurilemmoma, 3 cases of chronic sialademitis, 1 case of abscess, 2 cases of Retention cyst, 1 case of pseudocyst, 1 case of tuberculous lymphadenopathy, and 3 cases of normal finding. 2. Diagnosis ultrasonogram provides accurate information of the size, location and character of the lesion, and differentiates intraglandular lesion from extraglandular ones. 3. Ultrasonogram is one of convenient, reliable and initial modality for the diagnosis of salivary gland disease.

  4. UTILIZATION OF ALOE VERA (L HERBAL TONIC FOR TREATING MULBERRY LEAVES BEFORE FEEDING THE FIFTH INSTAR LARVAE OF SILK WORM, BOMBYX MORI L. (RACE: PM X CSR2.

    Directory of Open Access Journals (Sweden)

    Rajkumar Bapurao Deshmukh, Vitthalrao B Khyade

    2013-01-01

    Full Text Available The influence of the dietary supplementation of Aloe vera (L herbal formulation  (containing principally the extract Aloe vera on the larval growth and the cocoon (economic parameteres of the mulberry silkworm Bombyx mori L. commercial cross breed race: PM x CSR2 during its fifth instars was experimented. Treating the mulberry leaves with the aqueous solution of Aloe herbal formulation and feeding the fifth instar larvae, in general, elicited better response of the growth and the cocoon characteristics of this silkworm. Specifically, the Aloe vera L. at 2.0 % concentration resulted higher larval growth and increased the weight of cocoon. The mean larval weight, relative growth rate, effective rearing rate, larval consumption index of the final instar larvae of silk worm, Bombyx mori L. increased with the supplementation of Aloe vera tonic. The average pupal weight and mother moth weight also increased as a result of this supplementation. Maximum shell weight and shell ratio were noted in the group of larvae fed with Aloe treated mulberry leaves. The fibroin content of the cocoon shell produced by this silkworm in response to the dietary supplementation of Aloe vera tonic treatment also showed significant increase over control. The overall performance of Bombyx mori in response to the Aloe vera herbal treatment observed in the present study and the evaluation index values worked out showed that the growth and the cocoon parameters could be improved with the supplementation of A. vera herbal formulation. Aloe tonic may serve to orchestrate the progression of larval growth through the fortification of digestion capabilities in the fifth instar larvae of silkworm, Bombyx  mori (L (Race : PM x CSR2.   

  5. Mechanical performance of spider silk is robust to nutrient-mediated changes in protein composition.

    Science.gov (United States)

    Blamires, Sean J; Liao, Chen-Pan; Chang, Chung-Kai; Chuang, Yu-Chun; Wu, Chung-Lin; Blackledge, Todd A; Sheu, Hwo-Shuenn; Tso, I-Min

    2015-04-13

    Spider major ampullate (MA) silk is sought after as a biomimetic because of its high strength and extensibility. While the secondary structures of MA silk proteins (spidroins) influences silk mechanics, structural variations induced by spinning processes have additional effects. Silk properties may be induced by spiders feeding on diets that vary in certain nutrients, thus providing researchers an opportunity to assess the interplay between spidroin chemistry and spinning processes on the performance of MA silk. Here, we determined the relative influence of spidroin expression and spinning processes on MA silk mechanics when Nephila pilipes were fed solutions with or without protein. We found that spidroin expression differed across treatments but that its influence on mechanics was minimal. Mechanical tests of supercontracted fibers and X-ray diffraction analyses revealed that increased alignment in the amorphous region and to a lesser extent in the crystalline region led to increased fiber strength and extensibility in spiders on protein rich diets. PMID:25764227

  6. Spider silk: understanding the structure-function relationship of a natural fiber.

    Science.gov (United States)

    Humenik, Martin; Scheibel, Thomas; Smith, Andrew

    2011-01-01

    Spider silk is of great interest because of its extraordinary physical properties, such as strength and toughness. Here we discuss how these physical properties relate to the way in which spiders have utilized this material in prey capture, forcing its evolution to a high-performance fiber. Female spiders can produce up to seven different types of silk, and all these have different physical properties, which relate to their various functions. The variation in properties are due to underlying differences in the proteins making up these silks. As our understanding of spider silk has increased in the recent years, it has been possible to produce recombinant versions of the respective proteins. Recombinant proteins open up the potential to produce synthetic silk fibers with properties similar to those of the natural spider silk threads. PMID:21999996

  7. Spider silks from plants - a challenge to create native-sized spidroins.

    Science.gov (United States)

    Hauptmann, Valeska; Weichert, Nicola; Rakhimova, Marziya; Conrad, Udo

    2013-10-01

    Silk threads from spiders exhibit extraordinary mechanical properties, such as superior toughness and elasticity. Spider silks consist of several different large repetitive proteins that act as the basic materials responsible for these outstanding features. The production of spider silk protein variants in plants opens up new horizons in the production and functional investigation that enable the use of spider silks in innovative material development, nanotechnology and biomedicine in the future. This review summarizes and discusses production of spider silk protein variants in plants, especially with regards to plant expression systems, purification strategies, and characteristics of spider silk variants. Furthermore, the challenge of producing native-sized recombinant spidroins in planta is outlined, presenting three different strategies for achieving these high repetitive proteins with the help of non-repetitive C-terminal domains, crosslinking transglutaminase, and self-linking inteins. The potential of these fascinating proteins in medicine is also highlighted. PMID:24092675

  8. Protective effect of silk lutein on ultraviolet B-irradiated human keratinocytes

    Scientific Electronic Library Online (English)

    Sutatip, Pongcharoen; Prateep, Warnnissorn; Ongart, Lertkajornsin; Nanteetip, Limpeanchob; Manote, Sutheerawattananonda.

    Full Text Available Carotenoids are efficient antioxidants that are of great importance for human health. Lutein and zeaxanthin are carotinoids present in high concentrations in the human retina which are involved in the photoprotection of the human eye. Lutein may also protect the skin from ultraviolet (UV)-induced da [...] mage. The present study investigated the protective effect of lutein extracted from yellow silk cocoons of Bombyx mori on human keratinocytes against UVB irradiation. A human keratinocyte cell line and primary human keratinocytes were used to investigate the UVB protection effects of silk lutein and plant lutein. Silk lutein showed no cytotoxicity to keratinocytes. Treatment with silk lutein prior to UVB irradiation enhanced cell viability and cell proliferation, and reduced cell apoptosis. The protective effects of silk lutein may be superior to those of plant lutein. Silk lutein may have a benefit for protection of keratinocytes against UVB-irradiation.

  9. Why and how is silk spun? : integrating rheology with advanced spectroscopic techniques

    OpenAIRE

    Boulet-Audet, Maxime; Vollrath, Fritz; Chris, Hollland; Ann, Terry

    2013-01-01

    This thesis investigates the mechanisms behind natural silk spinning by integrating rheology, spectroscopy and small angle scattering to better understand this process and to guide our efforts towards mimicking Nature’s ways of producing high performance fibres. As a result of natural selection, arthropods such as spiders and moths have evolved the ability to excrete silk proteins in a highly controlled manner. Spun from liquid feedstocks, silk fibr...

  10. A modified method for inducing periodontitis in dogs using a silk-wire twisted ligature

    OpenAIRE

    Kim, Se Eun; Lee, Eui Ri; Lee, Yesran; Jeong, Manbok; Park, Young Woo; Ahn, Jae Sang; Ahn, Jeong Taek; Seo, Kangmoon

    2012-01-01

    This study was designed to assess the effectiveness of a modified silk ligature twisted with wire for inducing advanced periodontitis. Periodontitis was induced in five premolars and one molar of 20 healthy dogs over a 60-day period. The dogs were divided into four groups according to the ligature-inducing materials used: soft moistened food only, wire ligature (WL), silk ligature (SL) and twisted ligature with silk and wire (SWL). Periodontal indices were recorded, and dental radiographs wer...

  11. Elasticity of Spider dragline Silks Viewed as Nematics: Yielding Induced by Isotropic-Nematic Phase Transition

    CERN Document Server

    Cui, Lin-ying; Liu, Fei

    2008-01-01

    Spider dragline silk is an intriguing biomaterial of practical use, and it has long been suggested to be a liquid crystalline material. We model the dragline silk as nematics by using continuum liquid crystal theory. The overall stress-strain curve and the yield point can be evaluated quantitatively and agree with experiment data well. Additionally, our model can account for the drop of stress in wet spider dragline, i.e. in supercontracted dragline silk.

  12. Graphene oxide from silk cocoon: a novel magnetic fluorophore for multi-photon imaging

    OpenAIRE

    Roy, Manas; Kusurkar, Tejas Sanjeev; Maurya, Sandeep Kumar; Meena, Sunil Kumar; Singh, Sushil Kumar; Sethy, Niroj; Bhargava, Kalpana; Sharma, Raj Kishore; Goswami, Debabrata; Sarkar, Sabyasachi; Das, Mainak

    2013-01-01

    In this work, we synthesized graphene oxide from silk cocoon embarking its new dimension as a magnetic fluorophore when compared with its present technical status, which at best is for extracting silk as a biomaterial for tissue engineering applications. We produced graphene oxide by pyrolysing the silk cocoon in an inert atmosphere. The collected raw carbon is oxidized by nitric acid that readily produces multilayer graphene oxide with nano carbon particulates. Structural properties of the g...

  13. A protocol for the production of recombinant spider silk-like proteins for artificial fiber spinning

    OpenAIRE

    Teulé, Florence; Cooper, Alyssa R; Furin, William A; Bittencourt, Daniela; Rech, Elibio L; Brooks, Amanda; Lewis, Randolph V

    2009-01-01

    The extreme strength and elasticity of spider silks originate from the modular nature of their repetitive proteins. To exploit such materials and mimic spider silks, comprehensive strategies to produce and spin recombinant fibrous proteins are necessary. This protocol describes silk gene design and cloning, protein expression in bacteria, recombinant protein purification and fiber formation. With an improved gene construction and cloning scheme, this technique is adaptable for the production ...

  14. Purification and cytotoxcicity of tag-free bioengineered spider silk proteins3

    OpenAIRE

    Dams-Kozlowska, Hanna; Majer, Agnieszka; Tomasiewicz, Paulina; Lozinska, Jolanta; Kaplan, David L.; Mackiewicz, Andrzej

    2012-01-01

    Bioengineered spider silk-like proteins can serve as biomaterials for various biomedical applications. These proteins can be assembled in several morphological forms such as films, microcapsules, spheres, fibers, gels and scaffolds. However, crucial points for recombinant spider silks for human use are toxicity and immunogenicity. To assess this issue two bioengineered spider silk proteins composed of different numbers of repetitive motifs of the consensus repeats from spidroin-1 from Nephila...

  15. Multilingual Lexical Network from the Archives of the Digital Silk Road

    OpenAIRE

    Daoud, Mohammad; Kageura, Kyo; Boitet, Christian; Kitamoto, Asanobu; Mangeot, Mathieu

    2010-01-01

    We are describing the construction process of a specialized multilingual lexical resource dedicated for the ar- chive of the Digital Silk Road DSR. The DSR project creates digital archives of cultural heritage along the historical Silk Road; more than 116 of basic references on Silk Road have been digitized and made available online. These books are written in various languages and attract people from different linguistic back- ground, therefore, we are trying to build a multilingual reposito...

  16. Discussion on Development of Silk Weaving Trademark Process in Shang Dynasty of China

    OpenAIRE

    Xingmei Guo; Yiping Qiu

    2013-01-01

    In the period of Shang dynasty, agriculture achieved great development; accompanied by a certain scale of mulberry silkworm industry as silk production had a relatively high technological level and complicated loom and weaving skills emerged. The governor of the Shang dynasty attached great importance to the economic status of mulberry silkworm. Though with a limited quantity of silk fabrics in Shang dynasty found in archaeology, figured silk has emerged, indicating that the weaving technolog...

  17. Mechanical Response of Silk Crystalline Units from Force-Distribution Analysis

    OpenAIRE

    Xiao, Senbo; Stacklies, Wolfram; Cetinkaya, Murat; Markert, Bernd; Gräter, Frauke

    2009-01-01

    The outstanding mechanical toughness of silk fibers is thought to be caused by embedded crystalline units acting as cross links of silk proteins in the fiber. Here, we examine the robustness of these highly ordered ?-sheet structures by molecular dynamics simulations and finite element analysis. Structural parameters and stress-strain relationships of four different models, from spider and Bombyx mori silk peptides, in antiparallel and parallel arrangement, were determined and found to be in ...

  18. Traveling the Silk Road: A measurement analysis of a large anonymous online marketplace

    OpenAIRE

    Christin, Nicolas

    2012-01-01

    We perform a comprehensive measurement analysis of Silk Road, an anonymous, international online marketplace that operates as a Tor hidden service and uses Bitcoin as its exchange currency. We gather and analyze data over eight months between the end of 2011 and 2012, including daily crawls of the marketplace for nearly six months in 2012. We obtain a detailed picture of the type of goods being sold on Silk Road, and of the revenues made both by sellers and Silk Road operato...

  19. Scrutinizing the datasets obtained from nanoscale features of spider silk fibres

    OpenAIRE

    Silva, Luciano P; Rech, Elibio L.

    2014-01-01

    Spider silk fibres share unprecedented structural and mechanical properties which span from the macroscale to nanoscale and beyond. This is possible due to the molecular features of modular proteins termed spidroins. Thus, the investigation of the organizational scaffolds observed for spidroins in spider silk fibres is of paramount importance for reverse bioengineering. This dataset consists in describing a rational screening procedure to identify the nanoscale features of spider silk fibres....

  20. The role of Men1 in pituitary gland tumourigenesis

    OpenAIRE

    Gredsted, Lars

    2004-01-01

    Summary The pituitary gland is a key regulator of growth, metabolism and sexual development. The pituitary gland integrates signals from the hypothalamus and from peripheral endocrine glands and responds to changing physiological needs by secreting a series of hormones that regulate the activity of various endocrine glands as well as acting directly on many tissues. Tumours of the pituitary gland are relatively frequent possibly due to the plasticity of the gland. Pituitary gland tumours occu...

  1. Dissolution of Philosamia ricini Silk Film: Properties and Functions in Different Solutions

    Directory of Open Access Journals (Sweden)

    Y. Srisuwan

    2009-01-01

    Full Text Available In this study, dissolution of Eri (Philosamia ricini cocoons in different solutions was investigated and compared with Nang-Lai variety (Bombyx mori cocoons. The Lithium Bromide (LiBr, calcium nitrate (Ca(NO32, Zinc chloride (ZnCl2, Lithium thiocyanate (LiSCN·xH2O, 85% phosphate and mixture (calcium chloride (CaCl2/Ethanol/H2O; 1:2:8 solution systems were used. Efficiency of the dissolving solution was examined by measuring the percentage of dissolved silk. It was found that the Nang-Lai silk was completely dissolved in all solutions, whereas, Eri silk was slightly dissolved, except for 85% phosphate solution. The Fourier transform infrared spectroscopy (FTIR spectra of the Eri silk film composed of β-sheet form than Nang Lai silk film. With thermogravimetric analysis, the Eri silk film showed two stages of thermal decompositions while the Nang-Lai silk was a single stage. In conclusion, thermal stability of the Eri silk was higher than the Nang-Lai silk.

  2. E-Commerce in silk industry of Assam: A critical study

    OpenAIRE

    Mithun Chandra Roy

    2013-01-01

    In today’s over changing market, it is very difficult for the business to survive without proper marketing facility and the influence have clearly shown in the silk industry of Assam which is flourished but the over changing modern technology affect in silk industry of Assam. Now a days most of the business sectors adopting modern technology and flourish on the contrary the silk industry of Assam which is now centered in Sualkuchi known as the Asia’s largest silk village have fallen on bad...

  3. Discussion on Development of Silk Weaving Trademark Process in Shang Dynasty of China

    Directory of Open Access Journals (Sweden)

    Xingmei Guo

    2013-09-01

    Full Text Available In the period of Shang dynasty, agriculture achieved great development; accompanied by a certain scale of mulberry silkworm industry as silk production had a relatively high technological level and complicated loom and weaving skills emerged. The governor of the Shang dynasty attached great importance to the economic status of mulberry silkworm. Though with a limited quantity of silk fabrics in Shang dynasty found in archaeology, figured silk has emerged, indicating that the weaving technology at that time has reached a certain level. Therefore, under the background at that time, people had no sense on cultivation and development of branded goods. At the earliest, only the emperor could use silk fabrics. However, the rapid development of silk industry made silk culture constantly integrate into the Chinese culture in terms of geography and society; moreover, the flourish and use of silk allowed it to shine in clothing, economy, art and culture and became an indispensable high-end article of Chinese merchants in foreign trade. Meanwhile, in the period of Shang and Zhou dynasties, the Silk Road has formed and external exchange has been enhanced. All this has laid a foundation for the prosperity of silk industry in the period of Han and Tang dynasties.

  4. The elaborate structure of spider silk: structure and function of a natural high performance fiber.

    Science.gov (United States)

    Römer, Lin; Scheibel, Thomas

    2008-01-01

    Biomaterials, having evolved over millions of years, often exceed man-made materials in their properties. Spider silk is one outstanding fibrous biomaterial which consists almost entirely of large proteins. Silk fibers have tensile strengths comparable to steel and some silks are nearly as elastic as rubber on a weight to weight basis. In combining these two properties, silks reveal a toughness that is two to three times that of synthetic fibers like Nylon or Kevlar. Spider silk is also antimicrobial, hypoallergenic and completely biodegradable. This article focuses on the structure-function relationship of the characterized highly repetitive spider silk spidroins and their conformational conversion from solution into fibers. Such knowedge is of crucial importance to understanding the intrinsic properties of spider silk and to get insight into the sophisticated assembly processes of silk proteins. This review further outlines recent progress in recombinant production of spider silk proteins and their assembly into distinct polymer materials as a basis for novel products. PMID:19221522

  5. Biobased silver nanocolloid coating on silk fibers for prevention of post-surgical wound infections

    Directory of Open Access Journals (Sweden)

    Dhas SP

    2015-10-01

    Full Text Available Sindhu Priya Dhas, Suruthi Anbarasan, Amitava Mukherjee, Natarajan Chandrasekaran Center for Nanobiotechnology, VIT University, Vellore, India Abstract: Bombyx mori silk fibers are an important biomaterial and are used in surgical sutures due to their remarkable biocompatibility. The major drawback to the application of biomaterials is the risk of bacterial invasion, leading to clinical complications. We have developed an easy and cost-effective method for fabrication of antibacterial silk fibers loaded with silver nanoparticles (AgNPs by an in situ and ex situ process using an aqueous extract of Rhizophora apiculata leaf. Scanning electron microscopy revealed that well dispersed nanoparticles impregnated the silk fibers both in situ and ex situ. The crystalline nature of the AgNPs in the silk fibers was demonstrated by X-ray diffraction. The thermal and mechanical properties of the silk fibers were enhanced after they were impregnated with AgNPs. The silver-coated silk fibers fabricated by the in situ and ex situ method exhibited more than 90% inhibition against Pseudomonas aeruginosa and Staphylococcus aureus. Silk fibers doped with AgNPs were found to be biocompatible with 3T3 fibroblasts. The results obtained represent an important advance towards the clinical application of biocompatible AgNP-loaded silk fibers for prevention of surgical wound infections. Keywords: silk fibers, silver nanoparticles, antibacterial activity, wound infections, cytotoxicity, 3T3 fibroblast cells

  6. Molecular Architecture and Evolution of a Modular Spider Silk Protein Gene

    Science.gov (United States)

    Hayashi, Cheryl Y.; Lewis, Randolph V.

    2000-02-01

    Spider flagelliform silk is one of the most elastic natural materials known. Extensive sequencing of spider silk genes has shown that the exons and introns of the flagelliform gene underwent intragenic concerted evolution. The intron sequences are more homogenized within a species than are the exons. This pattern can be explained by extreme mutation and recombination pressures on the internally repetitive exons. The iterated sequences within exons encode protein structures that are critical to the function of silks. Therefore, attributes that make silks exceptional biomaterials may also hinder the fixation of optimally adapted protein sequences.

  7. Proteomic Analysis of Silk Viability in Maize Inbred Lines and Their Corresponding Hybrids

    Science.gov (United States)

    Wang, Yafei; Zhao, Xiaofeng; Zhang, Fangfang; Tang, Jihua; Fu, Zhiyuan

    2015-01-01

    A long period of silk viability is critical for a good seed setting rate in maize (Zea mays L.), especially for inbred lines and hybrids with a long interval between anthesis and silking. To explore the molecular mechanism of silk viability and its heterosis, three inbred lines with different silk viability characteristics (Xun928, Lx9801, and Zong3) and their two hybrids (Xun928×Zong3 and Lx9801×Zong3) were analyzed at different developmental stages by a proteomic method. The differentially accumulated proteins were identified by mass spectrometry and classified into metabolism, protein biosynthesis and folding, signal transduction and hormone homeostasis, stress and defense responses, and cellular processes. Proteins involved in nutrient (methionine) and energy (ATP) supply, which support the pollen tube growth in the silk, were important for silk viability and its heterosis. The additive and dominant effects at a single locus, as well as complex epistatic interactions at two or more loci in metabolic pathways, were the primary contributors for mid-parent heterosis of silk viability. Additionally, the proteins involved in the metabolism of anthocyanins, which indirectly negatively regulate local hormone accumulation, were also important for the mid-parent heterosis of silk viability. These results also might imply the developmental dependence of heterosis, because many of the differentially accumulated proteins made distinct contributions to the heterosis of silk viability at specific developmental stages. PMID:26630375

  8. Immune enhancement activities of silk lutein extract from Bombyx mori cocoons

    Scientific Electronic Library Online (English)

    Porkaew, Promphet; Sirirat, Bunarsa; Manote, Sutheerawattananonda; Duangkamol, Kunthalert.

    Full Text Available BACKGROUND: Declining immune function poses an important clinical challenge worldwide and supplementation with natural products that possessing immune enhancing properties is a promising approach for preventing or delaying immune function decline. Cocoons from yellow silkworms are a significant sour [...] ce of lutein, and this unexplored silk extract could be a viable alternative source for dietary lutein. This study assessed immunomodulatory activities of the silk lutein extract. Female BALB/c mice orally received lutein, either as silk or marigold extracts (10 or 20 mg/kg daily), or vehicle only (1% tween 80 in PBS pH 7.4) for 4 weeks. Natural killer (NK) cell activity, specific antibody production, lymphocyte subpopulations, mitogen-induced lymphocyte proliferation, and cytokine production were examined. RESULTS: Silk lutein extract increased NK cell activity, and the effect was dose-related whereas marigold lutein extract was ineffective. Silk lutein extract dose-dependently enhanced antibody production in pre-immunized mice but marigold lutein extract had no effect. Feeding with silk lutein extract increased the populations of CD3+ and CD4?+?CD3?+?cells. Silk lutein extract also stimulated concanavalin A- and lipopolysaccharide-induced proliferations of T and B lymphocytes, respectively. Moreover, silk lutein extract increased IL-2 and IFN-? production while the effect of marigold lutein extract was undetectable. CONCLUSIONS: Together, silk lutein extract enhanced both innate and adaptive immune functions. This preparation may prove to be an effective supplement for strengthened immunity.

  9. Preparation of hexagonal GeO? particles with particle size and crystallinity controlled by peptides, silk and silk-peptide chimeras.

    Science.gov (United States)

    Boix, Estefania; Puddu, Valeria; Perry, Carole C

    2014-11-28

    We demonstrate the use of silk based proteins to control the particle/crystallite size during GeO2 formation, using a bio-mimetic approach at circumneutral pH and ambient temperature. Multicrystalline GeO2 was prepared from germanium tetraethoxide (TEOG) in the presence of different silk-based proteins: Bombyx mori silk (native silk) and two chimeric proteins prepared by linking a germania binding peptide (Ge28: HATGTHGLSLSH) with Bombyx mori silk via chemical coupling at different peptide loadings (silk-Ge28 10% and silk-Ge28 50%). The mineralisation activity of the silk-based proteins was compared with that of peptide Ge28 as a control system. GeO2 mineralisation was investigated in water and in citric acid/bis-tris propane buffer at pH 6. Morphology, particle size, crystallinity, water and organic content of the materials obtained were analysed to study the effect of added biomolecules and mineralisation environment on material properties. In the presence of silk additives well-defined cube-shape hybrid materials composed of hexagonal germania and up to ca. 5 wt% organic content were obtained. The cubic particles ranged from 0.4 to 1.4 ?m in size and were composed of crystalline domains in the range 35-106 nm depending on the additive used and synthesis conditions. The organic material incorporated in the mineral did not appear to affect the unit cell dimensions. The silk and chimeric proteins in water promote material formation and crystal growth, possibly via an effective ion-channelling mechanism, however further studies are needed to assert to what extent the presence of the silk impacts on nucleation and growth stages. The germania binding peptide alone did not have any significant effect on reaction rate, yield or the material's properties compared to the blank. Interestingly, the peptide content in the silk chimeras tested did not affect mineralisation. The presence of buffer inhibited mineral condensation rate and yield. The use of silk-based biomolecules allows control of crystallite/particle size of hybrid materials opening up opportunities for bio-inspired approaches to be applied for the synthesis of functional germania based devices and materials. PMID:25300352

  10. MR imaging of the lacrimal gland

    International Nuclear Information System (INIS)

    The lacrimal gland consists of the proper lacrimal gland and accessory lacrimal glands. The anterior portion of the proper lacrimal gland is divided into two lobes, an orbital and a palpebral lobes by the aponeurosis of the levator muscle. The study evaluated MRI of 86 normal lacrimal glands, 43 normal volunteers (22 male, 21 female, age: 0-81 years old, mean age: 43.5 years), and 21 lacrimal gland masses (5 malignant lymphomas, 7 pseudolymphomas, 3 pseudotumors, 5 benign mixed tumors, 1 malignant mixed tumor) and correlated with histopathological findings. MRI was performed with a 1.5T unit for all normal subjects and 2 lacrimal gland masses, and with 0.5T unit for 19 masses. The signal intensity of both lobes of lacrimal glands is grossly same as the cerebral gray matter. The intensity within the gland was different slightly according to fat component, which was confirmed histologically. This intensity difference has disappeared on chemical shift fat suppression images. The mean thickness of orbital lobe of lacrimal gland was 2.57 mm, palpebral lobe, 1.74 mm and glandular bridge, 4.49 mm. The thickness of the posterior bridge in older people age over 60 was significantly decreased, and that of orbital lobe of the lacrimal gland in female was thicker than male. The malignant lymphomas inclined to involve the palpebral lobe of the lacrimal gland, and benign mixed tumors did the orbital lobe and glandular bridge of the lacrimal gland. The benign mixed tumor was round and well-definded, while others was molded and infiltrative. The signal intensity was homogeneous in malignant lymphomas, pseudolymphomas and a case of pseudotumors with homogeneous enhancement, while heterogeneous in benign and malignant mixed tumors and 2 cases of pseudotumors. High intensity components on T2-weighted images are characteristic for benign and malignant mixed tumors. (author)

  11. Recombinant Dragline Silk-Like Proteins-Expression and Purification.

    Science.gov (United States)

    Gaines, William A; Marcotte, William R

    2011-03-01

    Spider dragline silk is a proteinaceous fiber with impressive physical characteristics making it attractive for use in advanced materials. The fiber is composed of two proteins (spidroins MaSp1 and MaSp2), each of which contains a large central repeat array flanked by non-repetitive N- and C-terminal domains. The repeat arrays appear to be largely responsible for the tensile properties of the fiber, suggesting that the N- and C-terminal domains may be involved in self-assembly. We recently isolated the MaSp1 and MaSp2 N-terminal domains from Nephila clavipes and have incorporated these into mini-silk genes for expression in transgenic systems. Current efforts involve the development of expression vectors that will allow purification using a removable affinity tag for scalable protein purification. PMID:23914141

  12. Sialolipoma of the parotid gland: Case report with literature review comparing major and minor salivary gland sialolipomas

    OpenAIRE

    Qayyum, Sohail; Meacham, Ryan; Sebelik, Merry; Zafar, Nadeem

    2013-01-01

    Sialolipoma is a rare tumor found within both major and minor salivary glands. Here we discuss sialolipoma of the parotid gland and briefly review the English literature. Including our case, a total of 35 sialolipomas have been reported, 18 within major salivary glands and 17 within minor salivary glands. Major gland sialolipomas most often are presented in the parotid gland (77%) and those from minor glands were most often seen in the palate (41%). All lesions were well circumscribed and con...

  13. Hydrodynamical properties of recombinant spider silk proteins: Effects of pH, salts and shear, and implications for the spinning process.

    Science.gov (United States)

    Leclerc, Jérémie; Lefèvre, Thierry; Gauthier, Martin; Gagné, Stéphane M; Auger, Michèle

    2013-09-01

    We have investigated the effect of pH, salts and shear on the hydrodynamical diameter of recombinant major ampullate (MA) rMaSpI silk proteins in solution as a function of time using (1) H solution NMR spectroscopy. The results indicate that the silk proteins in solution are composed of two diffusing populations, a high proportion of "native" solubilized proteins and a small amount of high molecular weight oligomers. Similar results are observed with the MA gland content. Salts help maintaining the proteins in a compact form in solution over time and inhibit aggregation, the absence of salts triggering protein assembly leading to a gel state. Moreover, the aggregation kinetics of rMaSpI at low salt concentration accelerates as the pH is close to the isoelectric point of the proteins, suggesting that the pH decrease tends to slow down aggregation. The data also support the strong impact of shear on the spinning process and suggest that the assembly is driven by a nucleation conformational conversion mechanism. Thus, the adjustment of the physicochemical conditions in the ampulla seems to promote a stable, long term storage. In addition, the optimization of protein conformation as well as their unfolding and aggregation propensity in the duct leads to a specifically organized structure. © 2013 Wiley Periodicals, Inc. Biopolymers 99: 582-593, 2013. PMID:23794371

  14. Conductive Polymer Combined Silk Fiber Bundle for Bioelectrical Signal Recording

    OpenAIRE

    Tsukada, Shingo; Nakashima, Hiroshi; Torimitsu, Keiichi

    2012-01-01

    Electrode materials for recording biomedical signals, such as electrocardiography (ECG), electroencephalography (EEG) and evoked potentials data, are expected to be soft, hydrophilic and electroconductive to minimize the stress imposed on living tissue, especially during long-term monitoring. We have developed and characterized string-shaped electrodes made from conductive polymer with silk fiber bundles (thread), which offer a new biocompatible stress free interface with living tissue in bot...

  15. Engineered disulfides improve mechanical properties of recombinant spider silk

    OpenAIRE

    Grip, S; Johansson, J.; Hedhammar, M

    2009-01-01

    Nature's high-performance polymer, spider silk, is composed of specific proteins, spidroins, which form solid fibers. So far, fibers made from recombinant spidroins have failed in replicating the extraordinary mechanical properties of the native material. A recombinant miniature spidroin consisting of four poly-Ala/Gly-rich tandem repeats and a nonrepetitive C-terminal domain (4RepCT) can be isolated in physiological buffers and undergoes self assembly into macrofibers. Herein, we have made a...

  16. Study on antibacterial activity of hydrogel from irradiated silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Bunnak, J.; Chaisupakitsin, M. [King Mongkut' s Institute of Technology Lardkrabang, Bangkok (Thailand)

    2001-03-01

    Hydrogels for biomedical application were prepared from solution blends of 3% silk protein and 3%, 10% poly (vinyl alcohol) (PVA) and followed with irradiation. Mixture of hydrogels were gamma irradiated at 10, 20, 30, 40 and 50 kGy under N{sub 2} atmosphere. To clarify anti-bacterial activity of hydrogels, modified of the Agar disk diffusion method and American Association of Textile Chemists and Colorists, AATCC Test Method 90-1977, were carried out. The four kinds of bacteria such as Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis, were used. It was found that a 1:3 volume ratio of 3% silk protein and 3% PVA respectively, at 50 kGy irradiation, is suitable conditions for preparation hydrogels and trend to indicate the highest of an antibacterial activity against E. coli, B. subtilis and S. aureus. However the antibacterial activity of hydrogels against S. epidermidis was not clearly. These results are very useful to expand the application of hydrogel from irradiated silk protein to the medical products. (author)

  17. Enhanced cellular uptake of engineered spider silk particles.

    Science.gov (United States)

    Elsner, Martina B; Herold, Heike M; Müller-Herrmann, Susanne; Bargel, Hendrik; Scheibel, Thomas

    2015-03-01

    Drug delivery systems allow tissue/cell specific targeting of drugs in order to reduce total drug amounts administered to an organism and potential side effects upon systemic drug delivery. Most drug delivery systems are polymer-based, but the number of possible materials is limited since many commercially available polymers induce allergic or inflammatory responses or lack either biodegradability or the necessary stability in vivo. Spider silk proteins represent a new class of (bio)polymers that can be used as drug depots or drug delivery systems. The recombinant spider silk protein eADF4(C16), which can be processed into different morphologies such as particles, films, or hydrogels, has been shown to fulfil most criteria necessary for its use as biomaterial. Further, eADF4(C16) particles have been shown to be well-suited for drug delivery. Here, a new method was established for particle production to reduce particle size and size distribution. Importantly, cellular uptake of these particles was shown to be poor in HeLa cells. Therefore, variants of eADF4(C16) with inversed net charge or incorporated cell penetrating peptides and receptor interacting motifs were tested, showing much better cellular uptake. Interestingly, uptake of all silk variant particles was mainly achieved by clathrin-mediated endocytosis. PMID:26222296

  18. Study on antibacterial activity of hydrogel from irradiated silk protein

    International Nuclear Information System (INIS)

    Hydrogels for biomedical application were prepared from solution blends of 3% silk protein and 3%, 10% poly (vinyl alcohol) (PVA) and followed with irradiation. Mixture of hydrogels were gamma irradiated at 10, 20, 30, 40 and 50 kGy under N2 atmosphere. To clarify anti-bacterial activity of hydrogels, modified of the Agar disk diffusion method and American Association of Textile Chemists and Colorists, AATCC Test Method 90-1977, were carried out. The four kinds of bacteria such as Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis, were used. It was found that a 1:3 volume ratio of 3% silk protein and 3% PVA respectively, at 50 kGy irradiation, is suitable conditions for preparation hydrogels and trend to indicate the highest of an antibacterial activity against E. coli, B. subtilis and S. aureus. However the antibacterial activity of hydrogels against S. epidermidis was not clearly. These results are very useful to expand the application of hydrogel from irradiated silk protein to the medical products. (author)

  19. Protein composition correlates with the mechanical properties of spider ( Argiope trifasciata ) dragline silk.

    Science.gov (United States)

    Marhabaie, Mohammad; Leeper, Thomas C; Blackledge, Todd A

    2014-01-13

    We investigated the natural variation in silk composition and mechanical performance of the orb-weaving spider Argiope trifasciata at multiple spatial and temporal scales in order to assess how protein composition contributes to the remarkable material properties of spider dragline silk. Major ampullate silk in orb-weaving spiders consists predominantly of two proteins (MaSp1 and MaSp2) with divergent amino acid compositions and functionally different microstructures. Adjusting the expression of these two proteins therefore provides spiders with a simple mechanism to alter the material properties of their silk. We first assessed the reliability and precision of the Waters AccQ-Tag amino acid composition analysis kit for determining the amino acid composition of small quantities of spider silk. We then tested how protein composition varied within single draglines, across draglines spun by the same spider on different days, and finally between spiders. Then, we correlated chemical composition with the material properties of dragline silk. Overall, we found that the chemical composition of major ampullate silk was in general homogeneous among individuals of the same population. Variation in chemical composition was not detectable within silk spun by a single spider on a single day. However, we found that variation within a single spider's silk across different days could, in rare instances, be greater than variation among individual spiders. Most of the variation in silk composition in our investigation resulted from a small number of outliers (three out of sixteen individuals) with a recent history of stress, suggesting stress affects silk production process in orb web spiders. Based on reported sequences for MaSp genes, we developed a gene expression model showing the covariation of the most abundant amino acids in major ampullate silk. Our gene expression model supports that dragline silk composition was mostly determined by the relative abundance of MaSp1 and MaSp2. Finally, we showed that silk composition (especially proline content) strongly correlated with some measures of mechanical performance, particularly how much fibers shrunk during supercontraction as well as their breaking strains. Our findings suggest that spiders are able to change the relative expression rates of different MaSp genes to produce silk fibers with different chemical compositions, and hence, different material properties. PMID:24313814

  20. Anatomy, biogenesis, and regeneration of salivary glands

    OpenAIRE

    Holmberg, Kyle V.; Hoffman, Matthew P.

    2014-01-01

    An overview of the anatomy and biogenesis of salivary glands is important in order to understand the physiology, functions and disorders associated with saliva. A major disorder of salivary glands is salivary hypofunction and resulting xerostomia, or dry mouth, which affects hundreds of thousands of patients per year who suffer from salivary gland diseases or undergo head and neck cancer treatment. There is currently no curative therapy for these patients. To improve these patients’ quality o...

  1. Computed tomography of the lacrimal gland

    International Nuclear Information System (INIS)

    The CT scan image of the normal lacrimal gland was examined in 15 cases. Eleven were analyzed at 4--5 mm collimation, and the normal lacrimal gland could be recognized in the CT image in 6 of these. The image of the lacrimal gland showed higher density than the other tissues in the orbit, and the contrast enhancement was noticeable. The normal lacrimal gland could be easily recognized in all the other 4 cases, when they were analyzed by CT scanner at 1.5 mm collimation. (author)

  2. Spider Silks-Biomimetics Beyond Silk Fibers: Hydrogels, films & Adhesives from Aqueous Recombinant Spider Silk dopes: A Synchrotron X-Ray Nano-Structural Study

    Science.gov (United States)

    Sampath, Sujatha; Jones, Justin; Harris, Thomas; Lewis, Randolph

    2015-03-01

    With a combination of high strength and extensibility, spider silk's (SS) mechanical properties surpass those of any man made fiber. The superior properties are due to the primary protein composition and the complex hierarchical structural organization from nanoscale to macroscopic length scales. Considerable progress has been made to synthetically mimic the production of fibers based on SS proteins. We present synchrotron x-ray micro diffraction (SyXRD) results on new fibers and gels (hydrogels, lyogels) from recombinant SS protein water-soluble dopes. Novelty in these materials is two-fold: water based rather than widely used HFIP acid synthesis, makes them safe in medical applications (replacement for tendons & ligaments). Secondly, hydrogels morphology render them as excellent carriers for targeted drug delivery biomedical applications. SyXRD results reveal semi-crystalline structure with ordered beta-sheets and relatively high degree of axial orientation in the fibers, making them the closest yet to natural spider silks. SyXRD on the gels elucidate the structural transformations during the self-recovery process through mechanical removal and addition of water. Studies correlating the observed structural changes to mechanical properties are underway.

  3. Biobased silver nanocolloid coating on silk fibers for prevention of post-surgical wound infections

    Science.gov (United States)

    Dhas, Sindhu Priya; Anbarasan, Suruthi; Mukherjee, Amitava; Chandrasekaran, Natarajan

    2015-01-01

    Bombyx mori silk fibers are an important biomaterial and are used in surgical sutures due to their remarkable biocompatibility. The major drawback to the application of biomaterials is the risk of bacterial invasion, leading to clinical complications. We have developed an easy and cost-effective method for fabrication of antibacterial silk fibers loaded with silver nanoparticles (AgNPs) by an in situ and ex situ process using an aqueous extract of Rhizophora apiculata leaf. Scanning electron microscopy revealed that well dispersed nanoparticles impregnated the silk fibers both in situ and ex situ. The crystalline nature of the AgNPs in the silk fibers was demonstrated by X-ray diffraction. The thermal and mechanical properties of the silk fibers were enhanced after they were impregnated with AgNPs. The silver-coated silk fibers fabricated by the in situ and ex situ method exhibited more than 90% inhibition against Pseudomonas aeruginosa and Staphylococcus aureus. Silk fibers doped with AgNPs were found to be biocompatible with 3T3 fibroblasts. The results obtained represent an important advance towards the clinical application of biocompatible AgNP-loaded silk fibers for prevention of surgical wound infections. PMID:26491317

  4. Focal therapy of neuroblastoma using silk films to deliver kinase and chemotherapeutic agents in vivo.

    Science.gov (United States)

    Seib, F Philipp; Coburn, Jeannine; Konrad, Ilona; Klebanov, Nikolai; Jones, Gregory T; Blackwood, Brian; Charest, Alain; Kaplan, David L; Chiu, Bill

    2015-07-01

    Current methods for treatment of high-risk neuroblastoma patients include surgical intervention, in addition to systemic chemotherapy. However, only limited therapeutic tools are available to pediatric surgeons involved in neuroblastoma care, so the development of intraoperative treatment modalities is highly desirable. This study presents a silk film library generated for focal therapy of neuroblastoma; these films were loaded with either the chemotherapeutic agent doxorubicin or the targeted drug crizotinib. Drug release kinetics from the silk films were fine-tuned by changing the amount and physical crosslinking of silk; doxorubicin loaded films were further refined by applying a gold nanocoating. Doxorubicin-loaded, physically crosslinked silk films showed the best in vitro activity and superior in vivo activity in orthotopic neuroblastoma studies when compared to the doxorubicin-equivalent dose administered intravenously. Silk films were also suitable for delivery of the targeted drug crizotinib, as crizotinib-loaded silk films showed an extended release profile and an improved response both in vitro and in vivo when compared to freely diffusible crizotinib. These findings, when combined with prior in vivo data on silk, support a viable future for silk-based anticancer drug delivery systems. PMID:25861948

  5. Purification and cytotoxicity of tag-free bioengineered spider silk proteins.

    Science.gov (United States)

    Dams-Kozlowska, Hanna; Majer, Agnieszka; Tomasiewicz, Paulina; Lozinska, Jolanta; Kaplan, David L; Mackiewicz, Andrzej

    2013-02-01

    Bioengineered spider silk-like proteins can serve as biomaterials for various biomedical applications. These proteins can be assembled in several morphological forms such as films, microcapsules, spheres, fibers, gels, and scaffolds. However, crucial points for recombinant spider silks for human use are toxicity and immunogenicity. To assess this issue, two bioengineered spider silk proteins composed of different numbers of repetitive motifs of the consensus repeats from spidroin-1 from Nephila clavipes (15X and 6X) were cloned and expressed in Escherichia coli. The proteins were free of tag sequence and were purified using two methods based on (1) thermal and (2) organic acid resistance of the spider silks. The soluble spider silk proteins were not cytotoxic and did not activate macrophages over a wide range of concentrations, except when present at the highest concentration. Films made of the different silk variants supported the growth of the cells. Based on these data, and as the biodegradation rate of silk is very slow, the bioengineered spider silks are presumed safe biomaterials for biomedical applications. PMID:22865581

  6. The study on radiation-induced graft copolymerization of meth-acrylamide onto silk fabric

    International Nuclear Information System (INIS)

    The radiation-induced graft copolymerization of Meth-acrylamide onto silk fabric has been studied using electron beam and ?-irradiation. The processing monomer infusion conditions and radiation processing were studied in order to improve the properties of natural silk fabric

  7. Nanoconfinement of spider silk fibrils begets superior strength, extensibility, and toughness.

    Science.gov (United States)

    Giesa, Tristan; Arslan, Melis; Pugno, Nicola M; Buehler, Markus J

    2011-11-01

    Silk is an exceptionally strong, extensible, and tough material made from simple protein building blocks. The molecular structure of dragline spider silk repeat units consists of semiamorphous and nanocrystalline ?-sheet protein domains. Here we show by a series of computational experiments how the nanoscale properties of silk repeat units are scaled up to create macroscopic silk fibers with outstanding mechanical properties despite the presence of cavities, tears, and cracks. We demonstrate that the geometric confinement of silk fibrils to diameters of 50 ± 30 nm is critical to facilitate a powerful mechanism by which hundreds of thousands of protein domains synergistically resist deformation and failure to provide enhanced strength, extensibility, and toughness at the macroscale, closely matching experimentally measured mechanical properties. Through this mechanism silk fibers exploit the full potential of the nanoscale building blocks, regardless of the details of microscopic loading conditions and despite the presence of large defects. Experimental results confirm that silk fibers are composed of silk fibril bundles with diameters in the range of 20-150 nm, in agreement with our predicted length scale. Our study reveals a general mechanism to map nanoscale properties to the macroscale and provides a potent design strategy toward novel fiber and bulk nanomaterials through hierarchical structures. PMID:21967633

  8. Persistence and variation in microstructural design during the evolution of spider silk

    Science.gov (United States)

    Madurga, R.; Blackledge, T. A.; Perea, B.; Plaza, G. R.; Riekel, C.; Burghammer, M.; Elices, M.; Guinea, G.; Pérez-Rigueiro, J.

    2015-10-01

    The extraordinary mechanical performance of spider dragline silk is explained by its highly ordered microstructure and results from the sequences of its constituent proteins. This optimized microstructural organization simultaneously achieves high tensile strength and strain at breaking by taking advantage of weak molecular interactions. However, elucidating how the original design evolved over the 400 million year history of spider silk, and identifying the basic relationships between microstructural details and performance have proven difficult tasks. Here we show that the analysis of maximum supercontracted single spider silk fibers using X ray diffraction shows a complex picture of silk evolution where some key microstructural features are conserved phylogenetically while others show substantial variation even among closely related species. This new understanding helps elucidate which microstructural features need to be copied in order to produce the next generation of biomimetic silk fibers.

  9. E-Commerce in silk industry of Assam: A critical study

    Directory of Open Access Journals (Sweden)

    Mithun Chandra Roy

    2013-04-01

    Full Text Available In today’s over changing market, it is very difficult for the business to survive without proper marketing facility and the influence have clearly shown in the silk industry of Assam which is flourished but the over changing modern technology affect in silk industry of Assam. Now a days most of the business sectors adopting modern technology and flourish on the contrary the silk industry of Assam which is now centered in Sualkuchi known as the Asia’s largest silk village have fallen on bad days and unable to face competition from modern technology with the fast growing modern weaving techniques and more of that unable to compete the powerloom products. The produce of Sualkuchi depending on age-old and traditional method of weaving started to see its downfall. This article comprising about the benefits of E-Commerce in an organisation and an overview of silk industry of Assam.

  10. Persistence and variation in microstructural design during the evolution of spider silk.

    Science.gov (United States)

    Madurga, R; Blackledge, T A; Perea, B; Plaza, G R; Riekel, C; Burghammer, M; Elices, M; Guinea, G; Pérez-Rigueiro, J

    2015-01-01

    The extraordinary mechanical performance of spider dragline silk is explained by its highly ordered microstructure and results from the sequences of its constituent proteins. This optimized microstructural organization simultaneously achieves high tensile strength and strain at breaking by taking advantage of weak molecular interactions. However, elucidating how the original design evolved over the 400 million year history of spider silk, and identifying the basic relationships between microstructural details and performance have proven difficult tasks. Here we show that the analysis of maximum supercontracted single spider silk fibers using X ray diffraction shows a complex picture of silk evolution where some key microstructural features are conserved phylogenetically while others show substantial variation even among closely related species. This new understanding helps elucidate which microstructural features need to be copied in order to produce the next generation of biomimetic silk fibers. PMID:26438975

  11. Nanoparticle self-assembly by a highly stable recombinant spider wrapping silk protein subunit.

    Science.gov (United States)

    Xu, Lingling; Tremblay, Marie-Laurence; Orrell, Kathleen E; Leclerc, Jérémie; Meng, Qing; Liu, Xiang-Qin; Rainey, Jan K

    2013-10-01

    Artificial spider silk proteins may form fibers with exceptional strength and elasticity. Wrapping silk, or aciniform silk, is the toughest of the spider silks, and has a very different protein composition than other spider silks. Here, we present the characterization of an aciniform protein (AcSp1) subunit named W1, consisting of one AcSp1 199 residue repeat unit from Argiope trifasciata. The structural integrity of recombinant W1 is demonstrated in a variety of buffer conditions and time points. Furthermore, we show that W1 has a high thermal stability with reversible denaturation at ?71°C and forms self-assembled nanoparticle in near-physiological conditions. W1 therefore represents a highly stable and structurally robust module for protein-based nanoparticle formation. PMID:23994530

  12. Controlled hierarchical assembly of spider silk-DNA chimeras into ribbons and raft-like morphologies.

    Science.gov (United States)

    Humenik, Martin; Drechsler, Markus; Scheibel, Thomas

    2014-07-01

    Spider silk-DNA conjugates comprising the recombinant spider silk protein eADF4(C16) and short oligonucleotides were arranged in a linear antiparallel and parallel as well as in a branched manner via designed complementarity of the DNA moieties. After cross-? fibril self-assembly, temperature-induced annealing of the DNA moieties triggered fibril association into ribbons, composed of aligned nanofibrils, and rafts composed of ribbons ordered into sharply bordered, squared fibrous microstructures. The formation of the superstructures was clearly dependent on the individual silk-DNA conjugate. A combination of 5'-conjugated silk moieties via complementary nucleic acids enhanced fibril association, whereas mixing complementary 5'- and 3'-silk conjugates inhibited the formation of higher-order structures. PMID:24924514

  13. Schwannoma of the adrenal gland

    Directory of Open Access Journals (Sweden)

    Anunayi Jeshtadi

    2014-07-01

    Full Text Available Visceral schwannomas are extremely rare and are usually discov-ered incidentally on USG/CT-Scan. Primary schwannomas of the adrenal gland are extremely uncommon. It has been theorized that they originate from Schwann cells that insulate the nerve fi-bers innervating the adrenal medulla. Histopathological examina-tion coupled with immunohistochemistry provides the definitive diagnosis. A 55 year old normotensive female presented with pain in the right loin since 5 months. Her renal parameters were normal. Contrast enhanced computed tomography of abdomen showed a well delineated 6.5 x 5cms mass at upper pole of her right kidney. 24-hour urinary metanephrine was slightly elevated (3.07mg/24hrs. A decline in Serum cortisol levels was observed following a dexamethasone suppression test (18.89nmol/l. Histopathological examination revealed a spindle cell tumor. Immunohistochemistry showed strong and diffuse positive staining for S-100 with negative expression for CD-117, desmin, CD-34, HMB-45, synaptophysin, chromogranin, cytokeratin, and SMA. Ki-67 index was 2%.A diagnosis of cellular schwannoma of adrenal gland was confirmed.

  14. Sialolipoma of the parotid gland: Case report with literature review comparing major and minor salivary gland sialolipomas.

    Science.gov (United States)

    Qayyum, Sohail; Meacham, Ryan; Sebelik, Merry; Zafar, Nadeem

    2013-01-01

    Sialolipoma is a rare tumor found within both major and minor salivary glands. Here we discuss sialolipoma of the parotid gland and briefly review the English literature. Including our case, a total of 35 sialolipomas have been reported, 18 within major salivary glands and 17 within minor salivary glands. Major gland sialolipomas most often are presented in the parotid gland (77%) and those from minor glands were most often seen in the palate (41%). All lesions were well circumscribed and contained mature adipose tissue intimately admixed with benign salivary gland components. Ductal dilatation was found in 100% of minor salivary gland sialolipomas but in only 28% of major salivary gland tumors. Nerve entrapment has also rarely been noted in major salivary glands (14%) whereas myxoid degeneration has been identified in rare minor salivary glands tumors (13%). Treatment is surgical excision and is curative with no reports of recurrence. PMID:23798838

  15. Sialolipoma of the parotid gland: Case report with literature review comparing major and minor salivary gland sialolipomas

    Directory of Open Access Journals (Sweden)

    Sohail Qayyum

    2013-01-01

    Full Text Available Sialolipoma is a rare tumor found within both major and minor salivary glands. Here we discuss sialolipoma of the parotid gland and briefly review the English literature. Including our case, a total of 35 sialolipomas have been reported, 18 within major salivary glands and 17 within minor salivary glands. Major gland sialolipomas most often are presented in the parotid gland (77% and those from minor glands were most often seen in the palate (41%. All lesions were well circumscribed and contained mature adipose tissue intimately admixed with benign salivary gland components. Ductal dilatation was found in 100% of minor salivary gland sialolipomas but in only 28% of major salivary gland tumors. Nerve entrapment has also rarely been noted in major salivary glands (14% whereas myxoid degeneration has been identified in rare minor salivary glands tumors (13%. Treatment is surgical excision and is curative with no reports of recurrence.

  16. Treatment Options for Recurrent Salivary Gland Cancer

    Science.gov (United States)

    ... than half of all salivary gland tumors are benign (not cancerous ) and do not spread to other tissues . Salivary gland cancer is a type of head and neck cancer . Being exposed to certain types of radiation may increase the risk of salivary cancer. Anything ...

  17. Pleomorphic lipoma of the parotid gland.

    Science.gov (United States)

    Graham, C T; Roberts, A H; Padel, A F

    1998-02-01

    Lipomata are rare tumours of the parotid gland. The pleomorphic lipoma represents an unusual histological variant of the benign lipoma. We report a case of a pleomorphic lipoma arising in the parotid gland. Only one case of a similar nature has previously been recorded. This tumour is benign, was fully excised and recurrence is not expected. PMID:9578889

  18. Methods of microlymphography of the thyroid gland

    Energy Technology Data Exchange (ETDEWEB)

    Spuzyak, M.I.; Karachentsev, Yu.I.; Gorbenko, V.N. (Khar' kovskij Inst. Usovershenstvovaniya Vrachej (Ukrainian SSR))

    Methods of microlymphography application for study of lymphatic system and thyroid gland are described. It is shown that microlymphography can promote to outline new ways and directions in experimental and clinic lymphology. Microthyrolymphography must contribute to more correct and detailed interpretation of lifetime lymphograms of thyroid gland.

  19. Glucosamine loaded injectable silk-in-silk integrated system modulate mechanical properties in bovine ex-vivo degenerated intervertebral disc model.

    Science.gov (United States)

    Murab, Sumit; Samal, Juhi; Shrivastava, Akshay; Ray, Alok Ranjan; Pandit, Abhay; Ghosh, Sourabh

    2015-07-01

    Injectable hydrogels offer a tremendous potential for treatment of degenerated intervertebral disc due to their ability to withstand complex loading, conforming precisely to the defect spaces and eliminating the need for invasive surgical procedures. We have developed an injectable hydrogel platform of N-acetyl-glucosamine (GlcNAc) loaded silk hollow spheres embedded in silk hydrogel for in situ therapeutic release and enhanced mechanical strength. The assembled silk hydrogel provided adequate structural support to the ex vivo degenerated disc model in a cyclic compression test at par with the native tissue. Spatiotemporal release of GlcNAc in a controlled manner from the silk hollow microspheres trigger enhanced proteoglycan production from ADSCs embedded in the composite system. Role of MAPK and SMAD pathways in increasing proteoglycan production have been explored by immunohistological analysis as a result of the action of GlcNAc on the cells, elucidating the potential of injectable silk microsphere-in-silk hydrogel for the regeneration of degenerated disc tissue. PMID:25934453

  20. ANF in the Parotid Gland in Rabbits

    Directory of Open Access Journals (Sweden)

    S. Ferrara

    2012-01-01

    Full Text Available It is well known that the presence of a particular type of granule population has been discovered in the atrial cardiocytes which represent the major site of synthesis of atrial natriuretic factor. The ANF has potent natriuretic, diuretic and vasoactive functions. However, ANF evidence occurs in extracardiac tissues such as the brain, intestine, lymphoid organs and in various glands involved in water and salt regulation adrenals, pancreas, lacrimal and salivar glands with respect to salivary glands the literature reportes that ANF presence was found in the acinar cells and on the contrary in the ductal cells. In order to eliminatethese discordances researchers conducted a previous study on rabbit parotid gland. The observations evidenced that the acinar cells were immunonegative while the ductal intraparenchymal cells were immunopositive in the present research we have extended the study on the main excretory duct of rabbit parotid gland.

  1. Osteopontin expression in salivary gland carcinomas

    DEFF Research Database (Denmark)

    BjØrndal, Kristine; Larsen, Stine R

    2011-01-01

    J Oral Pathol Med (2010) Background:? In several cancer types, osteopontin (OPN) expression has been correlated with tumor progression and prognosis. Two earlier studies have examined OPN expression in salivary gland carcinomas with contradictory results. Methods:? One hundred and seventy-five patients with a primary salivary gland carcinoma diagnosed from January 1, 1990 to December 31, 2005 were identified in the local pathology register, Odense University Hospital. Criteria as documented by Allred et al. were used to assess OPN immunostaining that was performed on surgical specimens. Results:? Osteopontin was expressed in all salivary gland carcinomas. Adenoid cystic carcinomas had the highest mean sum score (7.3) and a significantly higher proportion of carcinomas with high OPN sum score than both mucoepidermoid carcinoma and acinic cell carcinoma. Correlation of OPN expression with known prognostic factors in salivary gland carcinomas was insignificant. Conclusions:? Salivary gland carcinomas express OPN. The expression does not correlate with known prognostic factors.

  2. Recombinant Dragline Silk-Like Proteins—Expression and Purification

    OpenAIRE

    Gaines, William A.; Marcotte, William R.

    2011-01-01

    Spider dragline silk is a proteinaceous fiber with impressive physical characteristics making it attractive for use in advanced materials. The fiber is composed of two proteins (spidroins MaSp1 and MaSp2), each of which contains a large central repeat array flanked by non-repetitive N- and C-terminal domains. The repeat arrays appear to be largely responsible for the tensile properties of the fiber, suggesting that the N- and C-terminal domains may be involved in self-assembly. We recently is...

  3. Redoable Tie-Over Dressing Using Multiple Loop Silk Threads

    OpenAIRE

    Hyeon Jong Jo; Jun Sik Kim; Nam Gyun Kim; Kyung Suk Lee; Jae Hoon Choi

    2013-01-01

    After skin grafting, to prevent hematoma or seroma collection at the graft site, a tie-over dressing has been commonly used. However, although the conventional tie-over dressing by suture is a useful method for securing a graft site, refixation is difficult when repeated tie-over dressing is needed. Therefore, we recommend a redoable tie-over dressing technique with multiple loops threads and connecting silk threads. After the raw surface of each of our cases was covered with a skin graft, mu...

  4. Measuring crystallinity of laser-cleaned silk by X-ray diffraction

    Directory of Open Access Journals (Sweden)

    Karin von Lerber

    2005-12-01

    Full Text Available We present an effective and sensitive method of analyzing the condition of silk following laser cleaning. New silk samples were analysed; two sets were soiled with carbon black before laser cleaning and two sets were left unsoiled. Samples were exposed to laser cleaning at a wavelength of 532 nm and a fluence of 1.5 J/cm2 for 4, 16 and 64 pulses. Two sample sets were also treated at fluence levels of 0.5, 1.0 and 4.2 J/cm2 to assess the effects of fluence on the silk structure. Wide angle X-ray diffraction was carried out using the NanoSTAR facility at Cardiff University. Using the main equatorial reflections from silk the crystallinity of the samples was calculated. Upon laser cleaning at 1.5 J/cm2, the silk displayed a reduced level of crystallinity as the number of pulses increased, with soiled silks displaying a greater crystallinity loss than unsoiled silks. Coupled with this, the crystal size, as analysed using the Scherrer formula, was shown to increase as the crystallinity reduced. The effects of fluence on the sample crystallinity was less obvious: samples treated at 0.5 J/cm2 displayed an intrinsically higher crystallinity than all other samples, but there was no progressive loss of crystallinity with increasing fluence level as may have been anticipated.

  5. Bioengineered Lacrimal Gland Organ Regeneration in Vivo

    Science.gov (United States)

    Hirayama, Masatoshi; Tsubota, Kazuo; Tsuji, Takashi

    2015-01-01

    The lacrimal gland plays an important role in maintaining a homeostatic environment for healthy ocular surfaces via tear secretion. Dry eye disease, which is caused by lacrimal gland dysfunction, is one of the most prevalent eye disorders and causes ocular discomfort, significant visual disturbances, and a reduced quality of life. Current therapies for dry eye disease, including artificial tear eye drops, are transient and palliative. The lacrimal gland, which consists of acini, ducts, and myoepithelial cells, develops from its organ germ via reciprocal epithelial-mesenchymal interactions during embryogenesis. Lacrimal tissue stem cells have been identified for use in regenerative therapeutic approaches aimed at restoring lacrimal gland functions. Fully functional organ replacement, such as for tooth and hair follicles, has also been developed via a novel three-dimensional stem cell manipulation, designated the Organ Germ Method, as a next-generation regenerative medicine. Recently, we successfully developed fully functional bioengineered lacrimal gland replacements after transplanting a bioengineered organ germ using this method. This study represented a significant advance in potential lacrimal gland organ replacement as a novel regenerative therapy for dry eye disease. In this review, we will summarize recent progress in lacrimal regeneration research and the development of bioengineered lacrimal gland organ replacement therapy. PMID:26264034

  6. Dysfunctional ectopic thyroid gland: A case report

    Directory of Open Access Journals (Sweden)

    Stoki? Edita

    2014-01-01

    Full Text Available Introduction. Lingual thyroid gland is a rare anomaly of thyroid gland development, occurring more frequently in females. If it causes local symptomatology such as dysphagia, dysphonia or dyspnea it is diagnosed in childhood, however, if it is asymptomatic it is usually diagnosed in adulthood. Case Outline. We present a 23-year-old female patient in whom we diagnosed lingual thyroid gland coincidentally during diagnostic procedures of a concomitant disease. The application of 131I scintigraphy showed an oval field of intensive accumulation of radio markers in the zone of medial face line, around tongue base, with the absence of thyroid gland in its physiological position. Functional testing proved primary hypothyroidism and we started the application of substitution therapy. The application of levothyroxine resulted in reaching euthyroid state and the reduction of thyroid gland size. Conclusion. We present a very rare anomaly of the thyroid gland, and so far there have been no clear attitudes about further treatment. The general condition of the patient, age, the size of ectopic thyroid gland and the existence of local symptomatology or complications represent the factors that have influence on the choice of treatment method.

  7. Primary parotid gland lymphoma: a case report

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    Paraskevas Katsaronis

    2011-08-01

    Full Text Available Abstract Introduction Mucosa associated lymphoid tissue lymphomas are the most common lymphomas of the salivary glands. The benign lymphoepithelial lesion is also a lymphoproliferative disease that develops in the parotid gland. In the present case report, we describe one case of benign lymphoepithelial lesion with a subsequent low transformation to grade mucosa associated lymphoid tissue lymphoma appearing as a cystic mass in the parotid gland. Case presentation A 78-year-old Caucasian female smoker was referred to our clinic with a non-tender left facial swelling that had been present for approximately three years. The patient underwent resection of the left parotid gland with preservation of the left facial nerve through a preauricular incision. The pathology report was consistent with a low-grade marginal-zone B-cell non-Hodgkin lymphoma (mucosa associated lymphoid tissue lymphoma following benign lymphoepithelial lesion of the gland. Conclusions Salivary gland mucosa associated lymphoid tissue lymphoma should be considered in the differential diagnosis of cystic or bilateral salivary gland lesions. Parotidectomy is recommended in order to treat the tumor and to ensure histological diagnosis for further follow-up planning. Radiotherapy and chemotherapy should be considered in association with surgery in disseminated forms or after removal.

  8. Consequences of Ultra-Violet Irradiation on the Mechanical Properties of Spider Silk

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    Wee Loong Lai

    2015-09-01

    Full Text Available The outstanding combination of high tensile strength and extensibility of spider silk is believed to contribute to the material’s toughness. Thus, there is great interest in engineering silk for biomedical products such as suture or implants. Additionally, over the years, many studies have also sought to enhance the mechanical properties of spider silk for wider applicability, e.g., by irradiating the material using ultra-violet radiation. However, the limitations surrounding the use of ultra-violet radiation for enhancing the mechanical properties of spider silk are not well-understood. Here, we have analyzed the mechanical properties of spider silk at short ultra-violet irradiation duration. Specimens of spider silk were subjected to ultra-violet irradiation (254-nm wavelength, i.e. UVC for 10, 20, and 30 min, respectively, followed by tensile test to rupture to determine the strength (maximum stress, extensibility (rupture strain, and toughness (strain energy density to rupture. Controls, i.e., specimens that did not received UVC, were also subjected to tensile test to rupture to determine the respective mechanical properties. One-way analysis of variance reveals that these properties decrease significantly (p < 0.05 with increasing irradiation duration. Among the three mechanical parameters, the strength of the spider silk degrades most rapidly; the extensibility of the spider silk degrades the slowest. Overall, these changes correspond to the observed surface modifications as well as the bond rupture between the peptide chains of the treated silk. Altogether, this simple but comprehensive study provides some key insights into the dependence of the mechanical properties on ultra-violet irradiation duration.

  9. Thyroid Gland in Patients with Rheumatoid Arthritis

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    B T Turumhambetova

    2009-09-01

    Full Text Available The purpose of our study was to investigate the main parameters of thyroid status in patients with rheumatoid arthritis (RA, as well as particularities of course of this disease depending on of thyroid gland function disorder. Materials and methods. 52 women with RA were examined. The first group consisted of 11 women with subclinical and manifestive hypothyroidism the second one 41 women without thyroid gland function disorder. The group comparison was conducted on main indexes of thyroid gland condition the hormon level, AT-TPO, ultrasonic data, as well as clinical and laboratory RA data. Results. In women with hypothyroidism the systemic manifestations of RA were more often truely diagnosed; DAS28 indexes, ESR, the number ot swollen joints were higher. The high level ot AT-TPO was diagnosed in 54,55% – I group and in 31,7% – II group TTG level was really less in patients receiving synthetic glycocorticoids. Small thyroid gland volume was diagnosed in 23,07% of examined patients. The thyroid gland status indexes in them did not differ from patients with normal thyroid gland volume. Reliable increasing of the peripheral resistance index was revealed in lower thyroid artery according to the ultrasonic study data under the reduced thyroid gland size. Conclusions. High incidence of hypothyroidism and AT-TPO carriage in RA was revealed. Hypothyroidism development is accompanied by high clinic-laboratory RA activity. The reduction of the thyroid gland volumes in RA is possibly stipulated not only by autoimmunal pathology, but also chronic ischemia of the organ in the conditions of immune-complex vasculitis and early atherosclerosis. The TTG level in patients with RA is defined not only by pathology of the thyroid gland, but glycocorticoid therapy as well.

  10. Uncovering head gland diversity in neotropical Polistinae wasps (Hymenoptera, Vespidae): Comparative analysis and description of new glands.

    Science.gov (United States)

    Penagos-Arévalo, Andrea C; Billen, Johan; Sarmiento, Carlos E

    2015-09-01

    Exocrine glands are involved in several wasp colony activities; however, the number of known glands in the Vespidae is rather low when compared to other social insect groups. The aim of this study is to survey the head of Neotropical social wasps and to provide a detailed comparative study of the glands found in the Polistinae. A total of 33 species distributed over 13 genera were studied with serial histological sections of the head, excluding the labiomaxillary complex. Additionally, the exoskeleton was explored using scanning electron microscopy looking for associated modifications. A total of eleven exocrine glands were observed, five are structures recorded for the first time for the Hymenoptera, three are new records for the Polistinae and three are previously known organs. The glands studied are: ocellar gland I, ocellar gland II, periocular gland, subantennal gland, hypopharyngeal gland, clypeal gland, posterobasal genal gland, ectal mandibular gland, mesal mandibular gland, intramandibular gland I, and intramandibular gland II. The widespread distribution of most of these glands suggests an origin prior to the evolution of the Polistinae. Our results highlight the importance of detailed morphological studies to unveil the significance of chemical communication in one of the most characteristic groups of social animals. PMID:26113431

  11. Biocompatible Silk-Poly(Pyrrole) Composite Trilayer Electromechanical Actuators

    Science.gov (United States)

    Klemke, Carly; Bradshaw, Nathan; Larson, Jesse; Severt, Sean; Ostrovsky-Snider, Nicholas; Murphy, Amanda; Leger, Janelle

    2015-03-01

    Biocompatible materials capable of controlled actuation are in high demand for use in biomedical applications such as dynamic tissue scaffolding, valves, and steerable surgical tools. Conducting polymers (CPs) have some desirable traits for use as an actuator, such as the ability to operate in biologically relevant fluids and responsiveness to low voltages. However CPs alone are limited due to their brittle nature and poor solubility. Recently we have shown that a composite material of silk and the CP poly(pyrrole) (PPy) shows promising characteristics as an actuator; it is mechanically robust as well as fully biocompatible. Initial proof-of-concept experiments demonstrated that these composites bend under an applied voltage (or current) using a simple bilayer device. Here we present the development of a trilayer device, composed of two conductive layers separated by an insulating silk layer. This configuration has twice the active surface area as a bilayer, potentially increasing the amount of mechanical motion per volt applied. We will discuss the fabrication and characterization of these devices, as well as their performance and future applications of this technology.

  12. Review - Trade and Society along the Ancient Silk Road

    Directory of Open Access Journals (Sweden)

    Bina Sengar

    2013-12-01

    Full Text Available Review of: Jacqueline H Fewkes. 2011. Trade and Contemporary Society Along the Silk Road: An Ethno-History of Ladakh. London: Routledge. xiii+196pp; list of plates, Ladakh in the twenty-first century is well known as a religious and touristic destination as well as an Indian border territory with Kargil and Siachin - significant military posts. In contrast, the commercial role of Ladakh in trade within the Himalayan region and along the Silk Route is less explored In this well-researched book, Fewkes presents various components of Ladakh's ethno-history of trade. She focuses on Ladakh since the eighteenth century and its status as a trade center in pre-independence India and thereafter. Its lost legacy of trade and commerce and associated facets of its culture, history, and future challenges are presented compactly in less than 200 pages. The book features an introduction and seven chapters, and is divided into three parts. Part I: Settings, has two chapters: "Beyond the Roof of the World", and "Recognising the Terrain: An Historical Background". Part II: Historical Trade, consists of "The Family Business: Community, Kinship, and Identity"; "Social Strategies for Profit"; "Living in a Material World: Cosmopolitan Elites"; and "The Demise of Trade: Coping with Borders". Part III: The Modern...

  13. Gender inequality and entrepreneurship: the Indian silk industry.

    Science.gov (United States)

    Mayoux, L

    1993-12-01

    The production of raw silk yarns from cocoons (reeling) is a crucial middle stage in the silk industry. The author reviews the experience of attempts to encourage women's entrepreneurship in this industry in Karnataka, South India. Reeling is a potentially lucrative field with possibilities for upward mobility from small-scale to large-scale production if credit is readily available. The industry in India employs large numbers of skilled female workers from all communities and is one of few in which a sectoral gender policy is being implemented. While these factors may be thought to be conducive to the development of women entrepreneurs, none were in the areas studied at the time of research. No women were involved in marketing through the official marketing system and no women's co-operatives were operating. While women were listed among registered reelers, men controlled the businesses. Men simply used women to obtain supplementary bank loans or funds through other avenues otherwise open to only women. Policies for women in reeling have therefore proved to be overwhelmingly unsuccessful. The author considers gender inequality and gender policy at length in this context and concludes that the problem is systemic and structural in nature. Policy implications are considered. PMID:12318601

  14. Recombinant spider silk matrices for neural stem cell cultures.

    Science.gov (United States)

    Lewicka, Michalina; Hermanson, Ola; Rising, Anna U

    2012-11-01

    Neural stem cells (NSCs) have the capacity to differentiate into neurons, astrocytes, and oligodendrocytes. Accordingly, NSCs hold great promise in drug screening and treatment of several common diseases. However, a major obstacle in applied stem cell research is the limitation of synthetic matrices for culturing stem cells. The objective of this study was to evaluate the suitability of recombinant spider silk (4RepCT) matrices for growth of NSCs. NSCs isolated from the cerebral cortices of mid-gestation rat embryos were cultured on either 4RepCT matrices or conventional poly-L-ornithine and fibronectin (P + F) coated polystyrene plates. From 48 h of culture, no significant differences in cell proliferation or viability were detected in NSC cultures on 4RepCT compared to control matrices (polystyrene plates coated with P + F). The NSCs retained an undifferentiated state, displaying low or no staining for markers of differentiated cells. Upon stimulation NSCs grown on 4RepCT differentiated efficiently into neuronal and astrocytic cells to virtually the same degree as control cultures, but a slightly less efficient oligodendrocyte differentiation was noted. We suggest that recombinant spider silk matrices provide a functional microenvironment and represent a useful tool for the development of new strategies in neural stem cell research. PMID:22863380

  15. Lymphoma type MALT of the parotid gland

    International Nuclear Information System (INIS)

    The lymphomas type MALT or the mucosa-associated lymphoid tissue, are the most recent variety of non-Hodgkin lymphomas present mainly in the gastric mucosa associated with Helycobacter pylori infection and in the thyroid gland in relation to Hashimoto's thyroiditis. Frequently the origin of this lesion can't be determined only by cytology study, thus it is necessary the histopathology analysis for a definitive diagnosis in most cases. Present paper includes the case of male patient with bilateral volume increase of both parotid glands and a diagnosis cytopathological of a benign lymphoepithelial process and the development of a type MALT lymphoma in relation to the right parotid gland. (author)

  16. Mammary gland tumors in captive African hedgehogs.

    Science.gov (United States)

    Raymond, J T; Gerner, M

    2000-04-01

    From December 1995 to July 1999, eight mammary gland tumors were diagnosed in eight adult captive female African hedgehogs (Atelerix albiventris). The tumors presented as single or multiple subcutaneous masses along the cranial or caudal abdomen that varied in size for each hedgehog. Histologically, seven of eight (88%) mammary gland tumors were malignant. Tumors were classified as solid (4 cases), tubular (2 cases), and papillary (2 cases). Seven tumors had infiltrated into the surrounding stroma and three tumors had histologic evidence of neoplastic vascular invasion. Three hedgehogs had concurrent neoplasms. These are believed to be the first reported cases of mammary gland tumors in African hedgehogs. PMID:10813628

  17. [The influence of formaldehyde, ethylene oxide, high pressure on the tension of silk sutures].

    Science.gov (United States)

    Lin, Y L; Cai, J H

    1997-05-01

    120 pieces of silk suture (1# & 4#) were sterilized with formaldehyde at different time period. Group II and III each had 20 pieces and was disinfected with ethylene oxide or high pressure respectively. The tension of each silk suture was measured with tensomether. The result showed that there was no significant difference compared with the control groups (P > 0.05). This suggests that silk suture maintains the same tension in the experiments after repeated sterilization with formaldehyde, with ethylene oxide, or with highpressure sterilization once. PMID:9304983

  18. Processing of recombinant spider silk proteins into tailor-made materials for biomaterials applications.

    Science.gov (United States)

    Schacht, Kristin; Scheibel, Thomas

    2014-10-01

    Spider silk has extraordinary mechanical properties, is biocompatible and biodegradable, and therefore an ideal material for biomedical applications. However, a drawback for any application is the inhomogeneity of spider silk, as seen for other natural materials, as well as the low availability due to the cannibalism of most spiders. Recently, developed recombinant spider silk proteins ensure constant material properties, as well as scalable production, and further the processing into morphologies other than fibres. Biotechnology enables genetic modification, broadening the range of applications, such as implant coatings, scaffolds for tissue engineering, wound dressing devices as well as drug delivery systems. PMID:24657706

  19. Mating behavior of Theridiosoma gemmosum (araneae: Theridiosomatidae: The unusual role of the male dragline silk

    Directory of Open Access Journals (Sweden)

    Hajer J.

    2011-01-01

    Full Text Available The mating of Theridiosoma gemmosum consists of a series of successive copulations. In the interval between two consecutive copulations, the females unwind the silken threads released by the male spinning organs; these threads are known as draglines or lifelines. The silk thus obtained is rolled up by the females into bundles, which they ingest prior to the next copulation. In other words, the mating of T. gemmosum involves the transfer of nutrients from the male to the female via silk. The silk provided by the male during copulation and eaten by the female, can be considered a nuptial gift.

  20. Sarcoidosis with salivary gland involvement: biochemical studies on parotid saliva.

    Science.gov (United States)

    Beeley, J A; Chisholm, D M

    1976-08-01

    Parotid saliva from a patient suffering from sarcoidosis with salivary gland involvement has been shown to have a decreased level of alpha-amylase but increased levels of albumin and lysozyme. These observations suggest that in addition to impaired gland function, gland damage as a result of inflammation had occurred which permitted increased passage of constituents from serum into the gland secretion. PMID:956685