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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. Self-assembly of silk fibroin under osmotic stress

    Science.gov (United States)

    Sohn, Sungkyun

    The supramolecular self-assembly behavior of silk fibroin was investigated using osmotic stress technique. In Chapter 2, a ternary phase diagram of water-silk-LiBr was constructed based on X-ray results on the osmotically stressed regenerated silk fibroin of Bombyx mori silkworm. Microscopic data indicated that silk I is a hydrated structure and a rough estimate of the number of water molecules lost by the structure upon converting from silk I to silk II has been made, and found to be about 2.2 per [GAGAGS] hexapeptide. In Chapter 3, wet-spinning of osmotically stressed, regenerated silk fibroin was performed, based on the prediction that the enhanced control over structure and phase behavior using osmotic stress method helps improve the physical properties of wet-spun regenerated silk fibroin fibers. The osmotic stress was applied in order to pre-structure the regenerated silk fibroin molecule from its original random coil state to more oriented state, manipulating the phase of the silk solution in the phase diagram before the start of spinning. Monofilament fiber with a diameter of 20 microm was produced. In Chapter 4, we investigated if there is a noticeable synergistic osmotic pressure increase between co-existing polymeric osmolyte and salt when extremely highly concentrated salt molecules are present both at sample subphase and stressing subphase, as is the case of silk fibroin self-assembly. The equilibration method that measures osmotic pressure relative to a reference with known osmotic pressure was introduced. Osmotic pressure of aqueous LiBr solution up to 2.75M was measured and it was found that the synergistic effect was insignificant up to this salt concentration. Solution parameters of stressing solutions and Arrhenius kinetics based on time-temperature relationship for the equilibration process were derived as well. In Chapter 5, self-assembly behavior of natural silk fibroin within the gland of Bombyx mori silkworm was investigated using osmotic stress technique. Microscopic and thermodynamic details of this self-assembly process along the spinline have been assessed. Formation of a needle-shaped molecular lath under appropriate osmotic stress was found. Silk I degree of hydration of silk gland was quantitatively estimated by image analysis of optical micrographs and the numbers varied from 2.2 to 2.7 depending on the region in the gland. Osmotic pressure in the gland was also estimated by equilibration method.

  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. Thermal crystallization mechanism of silk fibroin protein

    Science.gov (United States)

    Hu, Xiao

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

  5. 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...

  6. 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...

  7. Cytocompatibility of a silk fibroin tubular scaffold

    International Nuclear Information System (INIS)

    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

  8. 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.

  9. 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...

  10. 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...

  11. 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...

  12. 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.

  13. 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.

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

    Science.gov (United States)

    Ruan, Qing-Xia; Zhou, Ping

    2008-07-01

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

  15. 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.)

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

    Science.gov (United States)

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

    2009-03-01

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

  17. 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

  18. 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 ...

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

    OpenAIRE

    Prasong Srihanam

    2011-01-01

    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 inv...

  20. 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.

  1. Wet-spinning of osmotically stressed silk fibroin.

    Science.gov (United States)

    Sohn, Sungkyun; Gido, Samuel P

    2009-08-10

    Based on the phase diagram constructed for water-silk fibroin-LiBr using the osmotic stress method, wet-spinning of osmotically stressed, regenerated Bombyx mori silk fibroin was performed, without the necessity of using expensive or toxic organic solvents. The osmotic stress was applied to prestructure the regenerated silk fibroin molecule from its original random coil state to a more oriented state, manipulating the phase of the silk solution in the phase diagram before the start of spinning. Various starting points for spinning were selected from the phase diagram to evaluate the spinning performance and also physical properties of fibers produced. Monofilament fiber with a diameter of 20 microm was produced. It was found that the fibers whose starting point in the phase diagram were around the phase boundary between silk I and silk II, at very low LiBr concentrations, showed the best spinning process stability and physical properties. This underpins the prediction that the enhanced control over structure and phase behavior using the osmotic stress method helps improve the physical properties of wet-spun regenerated silk fibroin fibers. PMID:19572633

  2. 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...

  3. 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...

  4. Study on improving antioxidant and antibacterial activities of silk fibroin by irradiation treatment

    International Nuclear Information System (INIS)

    The silk fibroin solutions were prepared in solvent system of CaCl2. CH3CH2OH. H2O (mole ratio = 1:2:8) followed dialysis against deionized water. The 3% silk fibroin solutions were irradiated under gamma Co-60 source with dose ranging from 0 to 50 kGy at Hanoi Irradiation Centre and bioactivities of the irradiated silk fibroin solutions were investigated with different radiation doses. The results indicated that the antioxidant and antibacterial activities of fibroin were much improved by gamma irradiation. Maximum value of DPPH radical scavenging activity was 70.4% for the solution of silk fibroin irradiated at 10 kGy. Silk fibroin solutions irradiated at doses higher than 10 kGy also exhibited rather high antibacterial activity against 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)

  5. 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)

  6. 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...

  7. 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)

  8. 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

  9. Silk fibroin based antibacterial bionanotextiles as wound dressing materials

    Energy Technology Data Exchange (ETDEWEB)

    Çalamak, Semih [Hacettepe University, Faculty of Pharmacy, Department of Basic Pharmaceutical Sciences, 06100 Ankara (Turkey); Hacettepe University, Department of Nanotechnology and Nanomedicine, 06800 Ankara (Turkey); Erdoğdu, Ceren; Özalp, Meral [Hacettepe University, Faculty of Pharmacy, Department of Pharmaceutical Microbiology, 06100 Ankara (Turkey); Ulubayram, Kezban, E-mail: ukezban@hacettepe.edu.tr [Hacettepe University, Faculty of Pharmacy, Department of Basic Pharmaceutical Sciences, 06100 Ankara (Turkey); Hacettepe University, Department of Nanotechnology and Nanomedicine, 06800 Ankara (Turkey)

    2014-10-01

    New applications for medical biotextiles have been identified with the development of nanotechnological manufacturing technologies. Combination of nanotechnology and biotextile technology has resulted into a new field called bionanotextiles. Bionanotextiles are used in many areas which include wound dressings, bandages and tissue scaffolds. Silk fibroin (SF) from the cocoon of Bombyx mori, is one of the most favorable wound dressing materials due to its unique properties including biocompatibility, permeability, biodegradability, morphologic flexibility, and proper mechanical properties. The modification of antimicrobial properties of SFs can provide a barrier for bacterial penetration as wound dressing materials. In the present study, antibacterial polyethylenimine (PEI) (10, 20 and 30% (w/w)) was blended with SF and bionanotextiles were successfully fabricated by electrospinning. In addition, silk fibroin nanofibers were also functionalized with sulphate group in order to test whether they exhibit an antibacterial activity or not. Fibroin based bionanotextiles were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The cytotoxicity evaluations were carried out by L929 fibroblasts with MTT assay. The indirect cytotoxicity results demonstrate that all fibroin and PEI/fibroin extracts have no cytotoxicity on L929 cancer cell line. PEI/fibroin bionanotextiles showed strong antibacterial activities against gram positive Staphylococcus aureus and gram negative Pseudomonas aeruginosa. - Highlights: • Bionanotextiles are combination of nanotechnology and biotextile technology. • Bionanotextiles have good antibacterial activity against both of S. aureus and P. aeruginosa. • Antibacterial bionanotextiles are applicable to most of the infected wounds. • No cytotoxicity was observed on L929 cell line.

  10. A pilot study of macrophage responses to silk fibroin particles.

    Science.gov (United States)

    Cui, Xidong; Wen, Jianchuan; Zhao, Xia; Chen, Xin; Shao, Zhengzhong; Jiang, Jack J

    2013-05-01

    Silk fibroin (SF) shows promise for tissue engineering and other biomedical applications due to its excellent biocompatibility, unique biomechanical properties, and controllable biodegradability. The particulate form of SF materials may have many potential uses, including the use as a filler for tissue defects or as a controlled-release agent for drug delivery. However, many past in vivo and in vitro studies evaluating the biocompatibility and biodegradability of SF have involved bulk implants. It is essential to evaluate the inflammatory effects of SF particles before further use. In this study, two different sizes of SF particles were evaluated to assess their impact on the release of tumor necrosis factor (TNF)-?, interleukin (IL)-1?, and IL-6, in comparison with lipopolysaccharide positive control stimulation. The inflammatory processes were characterized using real-time reverse transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and light microscopy evaluations. The results indicated that small silk fibroin particles and large silk fibroin particles, in culture with RAW 264.7 murine macrophage cells for 24 h, caused up-regulation of mRNA coding for TNF-?, which indicated that both size of particles have potential inflammatory effects. There was a statistically significant increase in this up-regulation under small silk fibroin stimulation. However, the immunosorbent assay suggested that there was virtually no observed release of IL-1?, IL-6, or TNF-?, relative to the control group. The results suggest that SF particles of the chosen dimensions may have good biocompatibility in culture with RAW 264.7 murine macrophages. PMID:23225634

  11. Preparation and characterization of silk fibroin/HPMC blend film

    Science.gov (United States)

    Shetty, G. Rajesha; Kumar, R. Madhu; Rao, B. Lakshmeesha; Asha, S.; Sangappa

    2015-06-01

    In this work, the structural and mechanical stability of silk fibroin/Hydroxypropylmethyl cellulose (SF-HPMC) blend films were characterized by X-ray diffraction (XRD) and Universal Testing Machine (UTM). The results indicate that with the introduction of HPMC, the interactions between SF and HPMC results in improved crystallite size and increase in mechanical properties. The blend film obtained is more flexible compared to pure SF film.

  12. 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...

  13. 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 (α-form, type II β-turn, while the other treatments produced more silk II (β-form, anti-parallel β-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.

  14. 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.

  15. 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.

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

    Science.gov (United States)

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

    2014-06-01

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

  17. Wound healing effect of electrospun silk fibroin nanomatrix in burn-model.

    Science.gov (United States)

    Ju, Hyung Woo; Lee, Ok Joo; Lee, Jung Min; Moon, Bo Mi; Park, Hyun Jung; Park, Ye Ri; Lee, Min Chae; Kim, Soo Hyeon; Chao, Janet Ren; Ki, Chang Seok; Park, Chan Hum

    2016-04-01

    Silk fibroin has recently become an important biomaterial for tissue engineering application. In this study, silk fibroin nanomatrix was fabricated by electrospinning and evaluated as wound dressing material in a burn rat model. The wound size reduction, histological examination, and the quantification of transforming growth factor TGF-?1 and interleukin IL-1?, 6, and 10 were measured to evaluate the healing effects. The silk fibroin nanomatrix treatment exhibited effective performance in decreasing the wound size and epithelialization. Histological finding also revealed that the deposition of collagen in the dermis was organized by covering the wound area in the silk fibroin nanomatrix treated group. The expression level of pro-inflammatory cytokine (IL-1?) was significantly reduced in the injured skin following the silk fibroin nanomatrix treatment compared to the medical gauze (control) at 7 days after burn. Also, the expression level of TGF-?1 in the wound treated with silk fibroin nanomatrix peaked 21-days post-treatment whereas expression level of TGF-?1 was highest at day 7 in the gauze treated group. In conclusion, this data demonstrates that silk fibroin nanomatrix enhances the burn wound healing, suggesting it is a good candidate for burn wound treatment. PMID:26718866

  18. Silk fibroin-based scaffolds for tissue engineering

    Science.gov (United States)

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

    2013-09-01

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

  19. Novel two-step method to form silk fibroin fibrous hydrogel.

    Science.gov (United States)

    Ming, Jinfa; Li, Mengmeng; Han, Yuhui; Chen, Ying; Li, Han; Zuo, Baoqi; Pan, Fukui

    2016-02-01

    Hydrogels prepared by silk fibroin solution have been studied. However, mimicking the nanofibrous structures of extracellular matrix for fabricating biomaterials remains a challenge. Here, a novel two-step method was applied to prepare fibrous hydrogels using regenerated silk fibroin solution containing nanofibrils in a range of tens to hundreds of nanometers. When the gelation process of silk solution occurred, it showed a top-down type gel within 30min. After gelation, silk fibroin fibrous hydrogels exhibited nanofiber network morphology with ?-sheet structure. Moreover, the compressive stress and modulus of fibrous hydrogels were 31.9±2.6 and 2.8±0.8kPa, respectively, which was formed using 2.0wt.% concentration solutions. In addition, fibrous hydrogels supported BMSCs attachment and proliferation over 12days. This study provides important insight in the in vitro processing of silk fibroin into useful new materials. PMID:26652363

  20. 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

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

    International Nuclear Information System (INIS)

    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 ?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 pKa 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 13C 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 ?-sheet structure.

  2. 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.

  3. 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

  4. Preparation and hemostatic property of low molecular weight silk fibroin.

    Science.gov (United States)

    Lei, Caihong; Zhu, Hailin; Li, Jingjing; Feng, Xinxing; Chen, Jianyong

    2016-04-01

    Effective hemorrhage control becomes increasingly significant in today's military and civilian trauma, while the topical hemostats currently available in market still have various disadvantages. In this study, three low molecular weight silk fibroins (LMSF) were prepared through hydrolysis of silk fibroin in a ternary solvent system of CaCl2/H2O/EtOH solution at different hydrolysis temperatures. Fourier transform infrared spectroscopy analysis showed that the content of ? sheet structure in the LMSF decreased with the increase in hydrolysis temperature. The results of thromboelastographic and activated partial thromboplastin time methods showed that the LMSF hydrolyzed at 50?°C can significantly strengthen the coagulation in blood and activate the intrinsic pathway of coagulation cascade. In the murine hepatic injury model, the LMSF hydrolyzed at 50?°C can promote the blood clotting and decrease the blood loss and bleeding time. Based on these results, it can be suggested that the developed LMSF has the excellent hemostatic effect and may be a promising material in clinical hemostatic application. PMID:26732018

  5. 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

  6. 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.

  7. 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

  8. 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 ...

  9. 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)

  10. Fabrication of silk fibroin film using centrifugal casting technique for corneal tissue engineering.

    Science.gov (United States)

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

    2016-04-01

    Films prepared from silk fibroin have shown potential as biomaterials in tissue engineering applications for the eye. Here, we present a novel process for fabrication of silk fibroin films for corneal application. In this work, fabrication of silk fibroin films was simply achieved by centrifugal force. In contrast to the conventional dry casting method, we carried out the new process in a centrifuge with a rotating speed of 4000 rpm, where centrifugal force was imposed on an aluminum tube containing silk fibroin solution. In the present study, we also compared the surface roughness, mechanical properties, transparency, and cell proliferation between centrifugal and dry casting method. In terms of surface morphology, films fabricated by the centrifugal casting have less surface roughness than those by the dry casting. For elasticity and transparency, silk fibroin films obtained from the centrifugal casting had favorable results compared with those prepared by dry casting. Furthermore, primary human corneal keratocytes grew better in films prepared by the centrifugal casting. Therefore, our results suggest that this new fabrication process for silk fibroin films offers important potential benefits for corneal tissue regeneration. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 508-514, 2016. PMID:25939800

  11. Development and characterization of silk fibroin coated quantum dots

    Science.gov (United States)

    Nathwani, B. B.; Needham, C.; Mathur, A. B.; Meissner, K. E.

    2008-02-01

    Recent progress in the field of semiconductor nanocrystals or Quantum Dots (QDs) has seen them find wider acceptance as a tool in biomedical research labs. As produced, high quality QDs, synthesized by high temperature organometallic synthesis, are coated with a hydrophobic ligand. Therefore, they must be further processed to be soluble in water and to be made biocompatible. To accomplish this, the QDs are generally coated with a synthetic polymer (eg. block copolymers) or the hydrophobic surface ligands exchanged with hydrophilic material (eg. thiols). Advances in this area have enabled the QDs to experience a smooth transition from being simple inorganic fluorophores to being smart sensors, which can identify specific cell marker proteins and help in diagnosis of diseases such as cancer. In order to improve the biocompatibility and utility of the QDs, we report the development of a procedure to coat QDs with silk fibroin, a fibrous crystalline protein extracted from Bombyx Mori silkworm. Following the coating process, we characterize the size, quantum yield and two-photon absorption cross section of the silk coated QDs. Additionally, the results of biocompatibility studies carried out to compare the properties of these QD-silks with conventional QDs are presented. These natural polymer coatings on QDs could enhance the intracellular delivery and enable the use of these nanocrystals as an imaging tool for studying subcellular machinery at the molecular level.

  12. 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...

  13. Research On Degradation Of Silk Fibroin By Combination Of Electron Beam Irradiation And Hydrothermal Processing

    International Nuclear Information System (INIS)

    Silk fibers and silk proteins have been demonstrated to be useful to apply in the textile industry, biomedical, cosmetics, pharmaceuticals. In this study, the effects of electron beam (EB) irradiation combined with hydrothermal processing to the solubility of silk fibroin and generation of soluble silk protein were investigated. The solubility of unirradiated and irradiated fibroin were greater than 80 % when hydrothermal degradation was performed in the sodium hydroxide solution at appropriate concentration of 0.05 M. However, the solubility of irradiated fibroin was greater than that of unirradiated sample. The protein content increased from 0.4617 to 0.6530 mg/mg when irradiation doses increased from 0 to 200 kGy, respectively. The molecular weight of protein was determined by SDS-PAGE method. The characteristics of silk protein were confirmed by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). (author)

  14. 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

  15. Antimicrobial Silk Fibroin Hydrogel Instantaneously Induced by Cationic Surfactant

    Directory of Open Access Journals (Sweden)

    Shan Sun

    2013-01-01

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

  16. 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)

  17. 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 μm 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.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-01

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

  20. Collagen/silk fibroin composite scaffold incorporated with PLGA microsphere for cartilage repair.

    Science.gov (United States)

    Wang, Jianhua; Yang, Qiu; Cheng, Niangmei; Tao, Xiaojun; Zhang, Zhihua; Sun, Xiaomin; Zhang, Qiqing

    2016-04-01

    For cartilage repair, ideal scaffolds should mimic natural extracellular matrix (ECM) exhibiting excellent characteristics, such as biocompatibility, suitable porosity, and good cell affinity. This study aimed to prepare a collagen/silk fibroin composite scaffold incorporated with poly-lactic-co-glycolic acid (PLGA) microsphere that can be applied in repairing cartilage. To obtain optimum conditions for manufacturing a composite scaffold, a scaffold composed of different collagen-to-silk fibroin ratios was evaluated by determining porosity, water absorption, loss rate in hot water, and cell proliferation. Results suggested that the optimal ratio of collagen and silk fibroin composite scaffold was 7:3. The microstructure and morphological characteristics of the obtained scaffold were also examined through scanning electron microscopy and Fourier transform infrared spectroscopy. The results of in vitro fluorescence staining of bone marrow stromal cells revealed that collagen/silk fibroin composite scaffold enhanced cell proliferation without eliciting side effects. The prepared composite scaffold incorporated with PLGA microsphere was implanted in fully thick articular cartilage defects in rabbits. Collagen/silk fibroin composite scaffold with PLGA microspheres could enhance articular cartilage regeneration and integration between the repaired cartilage and the surrounding cartilage. Therefore, this composite will be a promising material for cartilage repair and regeneration. PMID:26838900

  1. Silk Fibroin Aqueous-Based Adhesives Inspired by Mussel Adhesive Proteins.

    Science.gov (United States)

    Burke, Kelly A; Roberts, Dane C; Kaplan, David L

    2016-01-11

    Silk fibroin from the domesticated silkworm Bombyx mori is a naturally occurring biopolymer with charged hydrophilic terminal regions that end-cap a hydrophobic core consisting of repeating sequences of glycine, alanine, and serine residues. Taking inspiration from mussels that produce proteins rich in l-3,4-dihydroxyphenylalanine (DOPA) to adhere to a variety of organic and inorganic surfaces, the silk fibroin was functionalized with catechol groups. Silk fibroin was selected for its high molecular weight, tunable mechanical and degradation properties, aqueous processability, and wide availability. The synthesis of catechol-functionalized silk fibroin polymers containing varying amounts of hydrophilic polyethylene glycol (PEG, 5000 g/mol) side chains was carried out to balance silk hydrophobicity with PEG hydrophilicity. The efficiency of the catechol functionalization reaction did not vary with PEG conjugation over the range studied, although tuning the amount of PEG conjugated was essential for aqueous solubility. Adhesive bonding and cell compatibility of the resulting materials were investigated, where it was found that incorporating as little as 6 wt % PEG prior to catechol functionalization resulted in complete aqueous solubility of the catechol conjugates and increased adhesive strength compared with silk lacking catechol functionalization. Furthermore, PEG-silk fibroin conjugates maintained their ability to form ?-sheet secondary structures, which can be exploited to reduce swelling. Human mesenchymal stem cells (hMSCs) proliferated on the silks, regardless of PEG and catechol conjugation. These materials represent a protein-based approach to catechol-based adhesives, which we envision may find applicability as biodegradable adhesives and sealants. PMID:26674175

  2. Electrospinning of carboxyethyl chitosan/poly(vinyl alcohol)/silk fibroin nanoparticles for wound dressings.

    Science.gov (United States)

    Zhou, Yingshan; Yang, Hongjun; Liu, Xin; Mao, Jun; Gu, Shaojin; Xu, Weilin

    2013-02-01

    Composite nanofibrous membranes of water-soluble N-carboxyethyl chitosan/poly(vinyl alcohol)/silk fibroin nanoparticles were successfully fabricated by electrospinning. The composite nanofibers were subjected to detailed analysis by scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). SEM results investigated that the morphology and diameter of the nanofibers were affected by silk fibroin nanoparticles content. XRD and DSC demonstrated that there was intermolecular hydrogen bonding among the molecules of carboxyethyl chitosan, silk fibroin and PVA. The crystalline microstructure of the electrospun fibers was not well developed. The indirect cytotoxicity assessments of the nanofibers were studied. The result showed the nanofibers had good biocompatibility. This novel electrospun matrix would be used as potential wound dressing for skin regeneration. PMID:23164753

  3. 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.

  4. 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.

  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. 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

  7. 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.

  8. 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

  9. Synthesis and characterization of dense membranes of silk fibroin with glycerin

    International Nuclear Information System (INIS)

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

  10. Development of macro/micro porous silk fibroin scaffolds with nano-sized calcium phosphate particles for bone tissue engineering

    OpenAIRE

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

    2012-01-01

    Macro/micro porous silk scaffolds with nano-sized calcium phosphate (CaP) particles were developed for bone tissue engineering. Different amounts of nano-sized CaP particles 4, 8, 16 and 25% (CaP:silk fibroin, wt/wt) were generated into the highly concentrated aqueous silk fibroin solutions via an in-situ approach. Afterwards, the pure silk and silk/nano-CaP porous scaffolds were produced by a combination of salt-leaching/freeze-drying methods. Thermal gravimetric analysi...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-04-15

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

  12. Preparation of silk fibroin–poly(ethylene glycol) conjugate films through click chemistry

    OpenAIRE

    Sampaio, Sandra; Miranda, Teresa; Santos, Jorge Gomes; Soares, Graça M. B.

    2011-01-01

    Azide silk fibroin (azido SF) and alkyne terminal poly(ethylene glycol) (PEG) 2000 (acetylene-terminal PEG 2000) were synthesized. Azido SF was reacted with acetylene-terminal PEG 2000 to produce films via a copper-mediated 1,3-cycloaddition (‘click’ chemistry) generating a triazole linkage as the networking forming reaction. Through click chemistry, novel silk-based films with various weight ratios were prepared and investigated. Fourier transform infrared, X-ray diffraction and differential...

  13. Novel genipin cross-linked chitosan-silk fibroin sponges for cartilage engineering strategies

    OpenAIRE

    Silva, S.S; Motta, A.; Rodrigues, Márcia T.; Pinheiro, A. F. M.; Gomes, Manuela E.; Mano, J. F.; Reis, R.L.; Migliaresi, C.

    2008-01-01

    The positive interaction of materials with tissues is an important step in regenerative medicine strategies. Hydrogels that are obtained from polysaccharides and proteins are expected to mimic the natural cartilage environment and thus provide an optimum milleu for tissue growth and regeneration. In this work, novel hydrogels composed of blends of chitosan and Bombyx mori silk fibroin were cross-linked with genipin (G) and were freeze dried to obtain chitosan/silk (CSG) sponges. C...

  14. 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

  15. 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.

  16. 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.

  17. 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)

  18. 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 ε-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 α-helix form (Silk I) into anti-parallel β-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 β-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

  19. 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.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Kazushi; Tsuboi, Yasuyuki; Itaya, Akira

    2003-09-01

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

  2. 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

  3. Comparative study of silk fibroin porous scaffolds derived from salt/water and sucrose/hexafluoroisopropanol in cartilage formation.

    Science.gov (United States)

    Makaya, Kumiko; Terada, Shinichi; Ohgo, Kosuke; Asakura, Tetsuo

    2009-07-01

    The purpose of this study is to create a new silk fibroin scaffold with sufficient three-dimensional morphology and porous structure for cartilage formation. We have applied sucrose particles sized around 300 to 500 microm as porogens compared to equal-sized salt particles. After the porogen was leached out with water, scaffolds were prepared with fibroin derived from sucrose/hexafluoroisopropanol (Su/H) or salt/water (Sa/W) based composites. A compression test indicated that the Sa/W fibroin was much harder than the Su/H fibroin, but a protease enzyme digested the Sa/W fibroin more quickly than Su/H fibroin. Rabbit ear chondrocytes were seeded onto the scaffolds for 4-8 week in vitro culture and histological analyses were performed. The distribution of cartilage formation in Safranin O staining was more homogenous in Su/H fibroin than that of Sa/W fibroin. The overall amount of cartilage was significantly better in the Su/H fibroin than that in the Sa/W fibroin. However, the inner structure of pore wall in the Sa/W fibroin was rough and microporous with cartilage matrix deposition, while that in the Su/H fibroin was thin and homogenous. Since mature cartilage gradually regenerates to fill the porous space, slowly degradable Su/H fibroin should be a better candidate for cartilage formation. PMID:19577196

  4. 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

  5. Optical spectroscopy to investigate the structure of regenerated Bombyx mori silk fibroin in solution.

    Science.gov (United States)

    Yang, Yuhong; Shao, Zhengzhong; Chen, Xin; Zhou, Ping

    2004-01-01

    Fluorescence and circular dichroism spectroscopy were used to monitor the conformational transition of regenerated Bombyx mori silk fibroin (RSF) in aqueous solutions under different conditions. According to the analysis of fluorescence spectra using anilinonaphthalene-8-sulfonic acid magnesium salt (ANS) as an external probe, the destruction of the hydrophobic core prior to the secondary structure change suggests that this collapse may initiate the conformational transition from random coil to beta-sheet for RSF. The temperature dependence of the structural changes of RSF, detected by both fluorescence spectroscopy and circular dichroism, shows a reversible process upon heating and recooling, with the midpoint around 45 degrees C. The results also indicate that most of the tryptophan (Trp) residues contained in silk fibroin are concentrated on the surface of the unfolded protein. However, they will change their location in the highly ordered structure (e.g., becoming more homogeneous) with the conformational transition of silk fibroin. Moreover, our studies also suggest that the presence of water plays a crucial role during the structure changes of fibroin. PMID:15132660

  6. 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

  7. 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

  8. Tyrosinase-catalyzed modification of Bombyx mori silk fibroin: grafting of chitosan under heterogeneous reaction conditions.

    Science.gov (United States)

    Freddi, Giuliano; Anghileri, Anna; Sampaio, Sandra; Buchert, Johanna; Monti, Patrizia; Taddei, Paola

    2006-09-01

    The capability of mushroom tyrosinase to catalyze the oxidation of tyrosine residues of Bombyx mori silk fibroin was studied under heterogeneous reaction conditions, by using a series of silk substrates differing in surface and bulk morphology and structure, i.e. hydrated and insoluble gels, mechanically generated powder and fibre. Tyrosinase was able to oxidize 10-11% of the tyrosine residues of silk gels. The yield of the reaction was very low for the powder and undetectable for fibres. FT-Raman spectroscopy gave evidence of the oxidation reaction. New bands attributable to vibrations of oxidized tyrosine species (o-quinone) appeared, and the value of the I853/I829 intensity ratio of the tyrosine doublet changed following oxidation of tyrosine. The thermal behaviour of SF substrates was not affected by enzymatic oxidation. o-Quinones formed by tyrosinase onto gels and powder were able to undergo non-enzymatic coupling with chitosan. FT-IR and FT-Raman spectroscopy provided clear evidence of the formation of silk-chitosan bioconjugates under heterogeneous reaction conditions. Chitosan grafting caused a beta-sheet --> random coil conformational transition of silk fibroin and significant changes in the thermal behaviour. Chitosan grafting did not occur, or occurred at an undetectable level on silk fibres. The results reported in this study show the potential of the enzymatically initiated protein-polysaccharide grafting for the production of a new range of bio-based, environmentally friendly polymers. PMID:16621091

  9. Potential of inherent RGD containing silk fibroin-poly (?-caprolactone) nanofibrous matrix for bone tissue engineering.

    Science.gov (United States)

    Bhattacharjee, Promita; Kundu, Banani; Naskar, Deboki; Kim, Hae-Won; Bhattacharya, Debasis; Maiti, T K; Kundu, S C

    2016-02-01

    The current study deals with the fabrication and characterization of blended nanofibrous scaffolds of tropical tasar silk fibroin of Antheraea mylitta and poly (?-caprolactone) to act as an ideal scaffold for bone regeneration. The use of poly (?-caprolactone) in osteogenesis is well-recognized. At the same time, the osteoconductive nature of the non-mulberry tasar fibroin is also established due to its internal integrin binding peptide RGD (Arg-Gly-Asp) sequences, which enhance cellular interaction and proliferation. Considering that the materials have the required and favorable properties, the blends are formed using an equal volume ratio of fibroin (2 and 4 wt%) and poly (?-caprolactone) solution (10 wt%) to fabricate nanofibers. The nanofibers possess an average diameter of 152?±?18 nm (2 % fibroin/PCL) and 175?±?15 nm (4 % fibroin/PCL). The results of Fourier transform infrared spectroscopy substantiates the preservation of the secondary structure of the fibroin in the blends indicating the structural stability of the neo-matrix. With an increase in the fibroin percentage, the hydrophobicity and thermal stability of the matrices as measured from melting temperature Tm (using DSC) decrease, while the mechanical strength is improved. The blended nanofibrous scaffolds are biodegradable, and support the viability and proliferation of human osteoblast-like cells as observed through scanning electron and confocal microscopes. Alkaline phosphatase assay indicates the cell proliferation and the generation of the neo-bone matrix. Taken together, these findings illustrate that the silk-poly (?-caprolactone) blended nanofibrous scaffolds have an excellent prospect as scaffolding material in bone tissue engineering. PMID:26174955

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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)

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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)

  20. 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 ...

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Mechanical property and biological performance of electrospun silk fibroin-polycaprolactone scaffolds with aligned fibers.

    Science.gov (United States)

    Yuan, Han; Shi, Hongfei; Qiu, Xushen; Chen, Yixin

    2016-02-01

    The mechanical strength, biocompatibility, and sterilizability of silk fibroin allow it to be a possible candidate as a natural bone regenerate material. To improve mechanical character and reinforce the cell movement induction, silk fibroin (SF)-polycaprolactone (PCL) alloy was fabricated by electrospinning techniques with a rotating collector to form aligned fibrous scaffolds and random-oriented scaffolds. The scanning electron microscope image of the scaffold and the mechanical properties of the scaffold were investigated by tensile mechanical tests, which were compared to random-oriented scaffolds. Furthermore, mesenchymal stem cells were planted on these scaffolds to investigate the biocompatibility, elongation, and cell movement in situ. Scanning electron microscopy shows that 91% fibers on the aligned fibroin scaffold were distributed between the dominant direction ±10°. With an ideal support for stem cell proliferation in vitro, the aligned fibrous scaffold induces cell elongation at a length of 236.46 ± 82 ?m and distribution along the dominant fiber direction with a cell alignment angle at 6.57° ± 4.45°. Compared with random-oriented scaffolds made by artificial materials, aligned SF-PCL scaffolds could provide a moderate mesenchymal stem cell engraftment interface and speed up early stage cell movement toward the bone defect. PMID:26588014

  6. Expression of the hGM-CSF in the silk glands of germline of gene-targeted silkworm.

    Science.gov (United States)

    Li, Yanmei; Cao, Guangli; Chen, Huimei; Jia, Haifang; Xue, Renyu; Gong, Chengliang

    2010-01-15

    To express human granulocyte-macrophage colony-stimulating factor (hGM-CSF) gene in the silk glands of transformation silkworm (Bombyx mori) based on gene-targeting, two fragments from fibroin heavy chain gene (fib-H) of silkworm were cloned and sequenced. One fragment contains the 1st exon and its downstream 1st intron's partial sequence; and the other fragment contains the 1st intron's partial sequence and the 2nd exon's partial sequence. Then the two fragments, as homologous arm, were inserted into pSK to generate a gene-targeted vector, pSK-HL-A3GFP-FLP-GM-CSF-FLPA-HR in which a gfp gene driven by A3 promoter and an hGM-CSF gene under the control of fibroin light chain (fib-L) promoter were included. The vector was transferred into the silkworm eggs using sperm-mediated gene transfer. After being screened for green fluorescent, the transformation silkworm was obtained, whose genome was verified by PCR and dot hybridization to confirm whether the target genes had been integrated into the silkworm genome. Furthermore, in the posterior silk glands of the G4 generation transformation silkworms, a specific band with the molecular weight of 22kDa could be detected by Western blotting with an antibody against hGM-CSF, and the expression level of the hGM-CSF estimated by ELISA was approximately 1.26ng per gram fresh posterior silk gland. PMID:20026302

  7. Incorporation of Human Recombinant Tropoelastin into Silk Fibroin Membranes with the View to Repairing Bruch’s Membrane

    Directory of Open Access Journals (Sweden)

    Audra M. A. Shadforth

    2015-09-01

    Full Text Available Bombyx mori silk fibroin membranes provide a potential delivery vehicle for both cells and extracellular matrix (ECM components into diseased or injured tissues. We have previously demonstrated the feasibility of growing retinal pigment epithelial cells (RPE on fibroin membranes with the view to repairing the retina of patients afflicted with age-related macular degeneration (AMD. The goal of the present study was to investigate the feasibility of incorporating the ECM component elastin, in the form of human recombinant tropoelastin, into these same membranes. Two basic strategies were explored: (1 membranes prepared from blended solutions of fibroin and tropoelastin; and (2 layered constructs prepared from sequentially cast solutions of fibroin, tropoelastin, and fibroin. Optimal conditions for RPE attachment were achieved using a tropoelastin-fibroin blend ratio of 10 to 90 parts by weight. Retention of tropoelastin within the blend and layered constructs was confirmed by immunolabelling and Fourier-transform infrared spectroscopy (FTIR. In the layered constructs, the bulk of tropoelastin was apparently absorbed into the initially cast fibroin layer. Blend membranes displayed higher elastic modulus, percentage elongation, and tensile strength (p < 0.01 when compared to the layered constructs. RPE cell response to fibroin membranes was not affected by the presence of tropoelastin. These findings support the potential use of fibroin membranes for the co-delivery of RPE cells and tropoelastin.

  8. 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; Mano, J. F.; Oliveira, Joaquim M.; de Oliveira, A. L.; Reis, R.L.

    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...

  9. 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 <80% ethanol-treated fibroin, to which individual cells prefer to attach (and then expand on the surface), rather than to aggregate. We discuss the influence of 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

  10. 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.

  11. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-11-15

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

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

    Science.gov (United States)

    Zhang, Jian-Guang; Mo, Xiu-Mei

    2013-06-01

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

  14. 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.)

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

    OpenAIRE

    Varkey, Aneesia; Venugopal, Elakkiya; Sugumaran, Ponjanani; Janarthanan, Gopinathan; Pillai, Mamatha M; Rajendran, Selvakumar; Bhattacharyya, Amitava

    2015-01-01

    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 s...

  16. 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.

  17. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-15

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-10

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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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.

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

    Science.gov (United States)

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

    2013-11-01

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

  7. Bio-inspired mineralization of hydroxyapatite in 3D silk fibroin hydrogel for bone tissue engineering.

    Science.gov (United States)

    Jin, Yashi; Kundu, Banani; Cai, Yurong; Kundu, Subhas C; Yao, Juming

    2015-10-01

    To fabricate hard tissue implants with bone-like structure using a biomimetic mineralization method is drawing much more attentions in bone tissue engineering. The present work focuses in designing 3D silk fibroin hydrogel to modulate the nucleation and growth of hydroxyapatite crystals via a simple ion diffusion method. The study indicates that Ca(2+) incorporation within the hydrogel provides the nucleation sites for hydroxyapatite crystals and subsequently regulates their oriented growth. The mineralization process is regulated in a Ca(2+) concentration- and minerlization time-dependent way. Further, the compressive strength of the mineralized hydrogels is directly proportional with the mineral content in hydrogel. The orchestrated organic/inorganic composite supports well the viability and proliferation of human osteoblast cells; improved cyto-compatibility with increased mineral content. Together, the present investigation reports a simple and biomimetic process to fabricate 3D bone-like biomaterial with desired efficacy to repair bone defects. PMID:26209967

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-11-15

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

  9. [The surface modification of eguus asinus augment fibroblast adhesion and proliferation on silk fibroin materials].

    Science.gov (United States)

    Lian, Xiaojie; Wang, Song; Zhu, Hesun; Gao, Zhen

    2010-08-01

    Eguus asinus is one of the rare Chinese drugs famous for promoting blood circulation. In this experiment, it was employed to modify the silk fibroin (SF) by physical blending. Mouse embryonic fibroblasts NIH-3T3 were seeded on pure and modified SF surfaces. The morphological changes of cell on SF surfaces were characterized by optical microscope images. The cell adhesion diameter, the attachment force (F) of a single cell and cell proliferation on SF surfaces were measured by micropipette aspiration system and MTT assay. The results indicated that the fibroblasts seeded on modified SF had larger cell adhesion area, stronger initial attachment force and higher cell proliferation than did the pure SF. In conclusion, eguus asinus improved the adhesion and proliferation of fibroblasts on SF. The research promoted the further use of Chinese drug eguus asinus in tissue engineering. PMID:20842849

  10. 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.

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

    International Nuclear Information System (INIS)

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

  12. Patterning and photoluminescence of CdS nanocrystallites on silk fibroin fiber

    International Nuclear Information System (INIS)

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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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...

  18. Effects of silk fibroin fiber incorporation on mechanical properties, endothelial cell colonization and vascularization of PDLLA scaffolds

    OpenAIRE

    Stoppato, M.; Stevens, H. Y.; E. Carletti; Migliaresi, C.; Motta, A; Guldberg, R. E.

    2013-01-01

    Attainment of functional vascularization of engineered constructs is one of the fundamental challenges of tissue engineering. However, the development of an extracellular matrix in most tissues, including bone, is dependent upon the establishment of a well developed vascular supply. In this study a poly-D,L-lactic acid (PDLLA) salt-leached sponge was modified by incorporation of silk fibroin fibers to create a multicomponent scaffold, in an effort to better support endothelial cell colonizati...

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

    OpenAIRE

    Varkey A; Venugopal E; Sugumaran P; Janarthanan G; Pillai MM; Rajendran S; Bhattacharyya A,

    2015-01-01

    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 iso...

  20. 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...

  1. 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

  2. Green electrospun pantothenic acid/silk fibroin composite nanofibers: fabrication, characterization and biological activity.

    Science.gov (United States)

    Fan, Linpeng; Cai, Zengxiao; Zhang, Kuihua; Han, Feng; Li, Jingliang; He, Chuanglong; Mo, Xiumei; Wang, Xungai; Wang, Hongsheng

    2014-05-01

    Silk fibroin (SF) from Bombyx mori has many established excellent properties and has found various applications in the biomedical field. However, some abilities or capacities of SF still need improving to meet the need for using practically. Indeed, diverse SF-based composite biomaterials have been developed. Here we report the feasibility of fabricating pantothenic acid (vitamin B5, VB5)-reinforcing SF nanofibrous matrices for biomedical applications through green electrospinning. Results demonstrated the successful loading of D-pantothenic acid hemicalcium salt (VB5-hs) into resulting composite nanofibers. The introduction of VB5-hs did not alter the smooth ribbon-like morphology and the silk I structure of SF, but significantly decreased the mean width of SF fibers. SF conformation transformed into ?-sheet from random coil when composite nanofibrous matrices were exposed to 75% (v/v) ethanol vapor. Furthermore, nanofibers still remained good morphology after being soaked in water environment for five days. Interestingly, as-prepared composite nanofibrous matrices supported a higher level of cell viability, especially in a long culture period and significantly assisted skin cells to survive under oxidative stress compared with pure SF nanofibrous matrices. These findings provide a basis for further extending the application of SF in the biomedical field, especially in the personal skin-care field. PMID:24632028

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-12-15

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

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

    International Nuclear Information System (INIS)

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

  5. Penicillin impregnation on oxygen plasma surface functionalized chitosan/Antheraea assama silk fibroin: Studies of antibacterial activity and antithrombogenic property.

    Science.gov (United States)

    Choudhury, Arup Jyoti; Gogoi, Dolly; Kandimalla, Raghuram; Kalita, Sanjeeb; Chaudhari, Yogesh B; Khan, Mojibur R; Kotoky, Jibon; Chutia, Joyanti

    2016-03-01

    Low temperature plasma can effectively tailor the surface properties of natural polymeric biomaterials according to the need for various biomedical applications. Non-mulberry silk, Antheraea assama silk fibroin (AASF) is a natural polymer having excellent biocompatibility and mechanical strength yet unlike mulberry silk, Bombyx mori silk fibroin, has drawn less interest in biomedical research. In the quest for developing as potential biomaterial, surface functionalization of plasma induced chitosan (Cs) grafted AASF ((AASF/O2-CS)g/O2) yarn is carried out using oxygen (O2) plasma. The (AASF/O2-CS)g/O2 yarn exhibits enhanced antithrombogenic property as well as antimicrobial activity against Gram positive (Bacillus subtilis) and Gram negative (Escherichia coli) bacteria as compared to AASF yarn. Moreover, impregnation of antibiotic drug (penicillin G sodium salt, PEN) on (AASF/O2-CS)g/O2 yarn further improves the observed properties. In-vitro hemolysis assay reveals that O2 plasma treatment and subsequent impregnation of PEN do not affect the hemocompatibility of AASF yarn. The present research findings demonstrate that plasma induced grafting of Cs followed by penicillin impregnation could significantly improve the potential applicability of AASF in the field of surgical research. PMID:26706554

  6. 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

  7. 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

  8. 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.

  9. 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)

  10. The biocompatibility of silk fibroin and acellular collagen scaffolds for tissue engineering in the ear

    International Nuclear Information System (INIS)

    Recent experimental studies have shown the suitability of silk fibroin scaffold (SFS) and porcine-derived acellular collagen I/III scaffold (ACS) as onlay graft materials for tympanic membrane perforation repair. The aims of this study were to further characterize and evaluate the in vivo biocompatibility of SFS and ACS compared with commonly used materials such as Gelfoam and paper in a rat model. The scaffolds were implanted in subcutaneous (SC) tissue and middle ear (ME) cavity followed by histological and otoscopic evaluation for up to 26 weeks. Our results revealed that SFS and ACS were well tolerated and compatible in rat SC and ME tissues throughout the study. The tissue response adjacent to the implants evaluated by histology and otoscopy showed SFS and ACS to have a milder tissue response with minimal inflammation compared to that of paper. Gelfoam gave similar results to SFS and ACS after SC implantation, but it was found to be associated with pronounced fibrosis and osteoneogenesis after ME implantation. It is concluded that SFS and ACS both were biocompatible and could serve as potential alternative scaffolds for tissue engineering in the ear. (paper)

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

    Science.gov (United States)

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

    2012-06-01

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

  12. 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.

  13. 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.

  14. 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.

  15. Biocompatibility and osteoconduction of macroporous silk fibroin implants in cortical defects in sheep.

    Science.gov (United States)

    Uebersax, Lorenz; Apfel, Tanja; Nuss, Katja M R; Vogt, Rainer; Kim, Hyoen Yoo; Meinel, Lorenz; Kaplan, David L; Auer, Joerg A; Merkle, Hans P; von Rechenberg, Brigitte

    2013-09-01

    The goal of the presented study was to compare the biocompatibility and cellular responses to porous silk fibroin (SF) scaffolds produced in a water-based (UPW) or a solvent based process (HFIP) using two different SF sources. For that reason, four different SF scaffolds were implanted (n=6) into drill hole defects in the cancellous bone of the sheep tibia and humerus. The scaffolds were evaluated histologically for biocompatibility, cell-material interaction, and cellular ingrowth. New bone formation was observed macroscopically and histologically at 8 weeks after implantation. For semiquantitative evaluation, the investigated parameters were scored and statistically analyzed (factorial ANOVA). All implants showed good biocompatibility as evident by low infiltration of inflammatory cells and the absent encapsulation of the scaffolds in connective tissue. Multinuclear foreign body giant cells (MFGCs) and macrophages were present in all parts of the scaffold at the material surface and actively degrading the SF material. Cell ingrowth and vascularization were uniform across the scaffold. However, in HFIP scaffolds, local regions of void pores were present throughout the scaffold, probably due to the low pore interconnectivity in this scaffold type in contrast to UPW scaffolds. The amount of newly formed bone was very low in both scaffold types but was more abundant in the periphery than in the center of the scaffolds and for HFIP scaffolds mainly restricted to single pores. PMID:23958322

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

    International Nuclear Information System (INIS)

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

  17. 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.

  18. 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

  19. 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-hexafluoro-2-propanol (HFIP and trifluoroacetic acid (TFA as solvents to biomimic the native ECM via electrospinning. Scanning electronic microscope (SEM showed that relatively uniform nanofibers could be obtained when 12% SF was blended with 6% HBC at the weight ratio of 50:50. Meanwhile, the average nanofibrous 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 β-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.

  20. 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.

  1. Antheraea pernyi silk fibroin for targeted gene delivery of VEGF165-Ang-1 with PEI

    International Nuclear Information System (INIS)

    Vascularization is a crucial challenge in tissue engineering. One solution for this problem is to implant scaffolds that contain functional genes that promote vascularization by providing angiogenic growth factors via a gene delivery carrier. Poly(ethylenimine) (PEI) is a gene delivery carrier with high transfection efficiency but with cytotoxicity. To solve this problem, we utilized Antheraea pernyi silk fibroin (ASF), which has favorable cytocompatibility and biodegradability, RGD sequences and a negative charge, in conjunction with PEI, as the delivery vector for vascular endothelial growth factor (VEGF) 165-angiopoietin-1 (Ang-1) dual gene simultaneous expression plasmid, creating an ASF/PEI/pDNA complex. The results suggested that the zeta potential of the ASF/PEI/pDNA complex was significantly lower than that of the PEI/pDNA complex. Decreased nitrogen and increased oxygen on the surface of the complex demonstrated that the ASF had successfully combined with the surface of the PEI/pDNA. Furthermore, the complexes resisted digestion by nucleic acid enzymes and degradation by serum. L929 cells were cultured and transfected in vitro and improved cytotoxicity was found when the cells were transfected with ASF/PEI/pDNA compared with PEI/pDNA. In addition, the transfection efficiency and VEGF secretion increased. In general, this study provides a novel method for decreasing the cytotoxicity of PEI gene delivery vectors and increasing transfection efficiency of angiogenesis-related genes. (paper)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-09-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-08-01

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

  4. 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.

  5. 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

  6. 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)

  7. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-04-01

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

  9. Radiation degradation of silk

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-03-01

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

  10. 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

  11. 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

  12. 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.

  13. 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.

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

    International Nuclear Information System (INIS)

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

  15. Silk Fibroin/Nano-CaP Bilayered scaffolds for osteochondral tissue engineering

    OpenAIRE

    Yan, Leping; Oliveira, Joaquim M.; de Oliveira, A. L.; Reis, R.L.

    2014-01-01

    In this study, bilayered silk and silk/nano-CaP scaffolds were developed for osteochondral (OC) tissue engineering. Aqueous silk solution (16 wt.%) was used for preparation of the cartilage-like layer and, for generation of the silk/nano-CaP suspension and the bottom layer (CaP/Silk: 16 wt.%). The scaffolds were formed by using salt-leaching/lyophilization approach. The scanning electron microscopy revealed that the both layers presented porous structure and integrated well. Mi...

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

    Directory of Open Access Journals (Sweden)

    Srihanam Prasong

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Traian V. Chirila

    2013-05-01

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

  18. 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.

  19. In vitro and in vivo characterization of a silk fibroin-coated polyester vascular prosthesis.

    Science.gov (United States)

    Huang, Fuhua; Sun, Lizhong; Zheng, Jun

    2008-12-01

    Silk fibroin (SF) is well known to be biocompatible, degradable, and nontoxic. In this study, SF was impregnated into a porous polyester graft (InterVascular external velour, InterVascular, Inc., La Ciotat, France), 8 mm in diameter. The SF-impregnated graft was investigated in vitro and in vivo to evaluate its potential for use as a new vascular graft impervious to blood, while retaining high porosity for tissue ingrowth and biological healing. For in vitro investigation, the water permeability, coating weight, morphology, and mechanical properties of the SF-impregnated grafts were compared with collagen-coated grafts (InterGard grafts, InterVascular, Inc.). The water permeability of the controls (1388 +/- 30.5 mL/cm(2)/min at 120 mm Hg) was reduced >99% by SF impregnation, rendering the graft impervious to blood. The coating weight of the collagen was 117 +/- 22 mg/g of graft, producing a slightly lower value than the InterGard prosthesis (302 +/- 23 mg/g). For the in vivo experiment, six SF-sealed vascular grafts were implanted in the abdominal aorta of dogs for scheduled periods ranging from 4 h to 6 months. Commercial collagen-impregnated grafts (InterGard) and untreated external velour grafts (InterVascular) were also implanted for scheduled periods ranging from 1 to 6 months for comparison. Gross observation of the explanted grafts and histological examination of the representative sections were conducted for two types of grafts using a light microscope after hematoxylin-eosin staining. These SF-impregnated grafts showed less foreign body and inflammation reactions, and the SF layer was almost completely absorbed. The average of the values in each period for the SF grafts was 48% neointima at 1 month, 85% at 3 months, and 97% at 6 months, whereas those of the InterGard prostheses was 34, 46, and 90%, respectively. This study demonstrated that the use of a biodegradable SF as biological sealant can be a feasible approach to prepare impervious textile arterial prostheses. The SF-impregnated graft showed less thrombogenesis and induced host cell migration along the matrix without foreign body or inflammatory reactions. Moreover, it appears to facilitate the development of endothelial-like cells. PMID:19133021

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

    International Nuclear Information System (INIS)

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

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

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

    Directory of Open Access Journals (Sweden)

    S. Prasong

    2009-01-01

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

  8. 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.

  9. 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

  10. 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 ...

  11. Synthesis and cellular compatibility of Co-doped ZnO particles in silk-fibroin peptides.

    Science.gov (United States)

    Zou, Yuanwen; Huang, Zhongbing; Wang, Yan; Liao, Xiaoming; Yin, Guangfu; Gu, Jianwen

    2013-02-01

    Co-doped ZnO particles were successfully prepared via a facile biomineralization process in the template of silk-fibroin (SF) peptides at room temperature, and SF peptides were coated onto the surface of particles. The ratio of Zn/Co in reactive solution could substantially influence the morphology of as-prepared particles, and the rough spherical particles including some nanoparticles of 50 nm diameters could be obtained at 4:1 ratio of Zn/Co. The saturation magnetization of SF-coated Co-ZnO particles was 8.63 emu/g, much larger than that of Co-ZnO without SF. L929 cell test revealed that the Co-doped ZnO particles had a good cellular compatibility at the concentration of less than 0.25 mg/mL due to silk-peptide coating, indicating that the prepared Co-doped ZnO particles have a potential for the biomedical applications. PMID:23010108

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

    Science.gov (United States)

    Varkey, Aneesia; Venugopal, Elakkiya; Sugumaran, Ponjanani; Janarthanan, Gopinathan; Pillai, Mamatha M; Rajendran, Selvakumar; Bhattacharyya, Amitava

    2015-01-01

    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. PMID:26491306

  13. 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

  14. 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.

  15. 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.

  16. Spider Transcriptomes Identify Ancient Large-Scale Gene Duplication Event Potentially Important in Silk Gland Evolution.

    Science.gov (United States)

    Clarke, Thomas H; Garb, Jessica E; Hayashi, Cheryl Y; Arensburger, Peter; Ayoub, Nadia A

    2015-07-01

    The evolution of specialized tissues with novel functions, such as the silk synthesizing glands in spiders, is likely an influential driver of adaptive success. Large-scale gene duplication events and subsequent paralog divergence are thought to be required for generating evolutionary novelty. Such an event has been proposed for spiders, but not tested. We de novo assembled transcriptomes from three cobweb weaving spider species. Based on phylogenetic analyses of gene families with representatives from each of the three species, we found numerous duplication events indicative of a whole genome or segmental duplication. We estimated the age of the gene duplications relative to several speciation events within spiders and arachnids and found that the duplications likely occurred after the divergence of scorpions (order Scorpionida) and spiders (order Araneae), but before the divergence of the spider suborders Mygalomorphae and Araneomorphae, near the evolutionary origin of spider silk glands. Transcripts that are expressed exclusively or primarily within black widow silk glands are more likely to have a paralog descended from the ancient duplication event and have elevated amino acid replacement rates compared with other transcripts. Thus, an ancient large-scale gene duplication event within the spider lineage was likely an important source of molecular novelty during the evolution of silk gland-specific expression. This duplication event may have provided genetic material for subsequent silk gland diversification in the true spiders (Araneomorphae). PMID:26058392

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

    Science.gov (United States)

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

    2013-10-01

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

  18. Enhanced bone formation in electrospun poly(l-lactic-co-glycolic acid)-tussah silk fibroin ultrafine nanofiber scaffolds incorporated with graphene oxide.

    Science.gov (United States)

    Shao, Weili; He, Jianxin; Sang, Feng; Wang, Qian; Chen, Li; Cui, Shizhong; Ding, Bin

    2016-05-01

    To engineer bone tissue, it is necessary to provide a biocompatible, mechanically robust scaffold. In this study, we fabricated an ultrafine nanofiber scaffold by electrospinning a blend of poly(l-lactic-co-glycolic acid), tussah silk fibroin, and graphene oxide (GO) and characterized its morphology, biocompatibility, mechanical properties, and biological activity. The data indicate that incorporation of 10wt.% tussah silk and 1wt.% graphene oxide into poly(l-lactic-co-glycolic acid) nanofibers significantly decreased the fiber diameter from 280 to 130nm. Furthermore, tussah silk and graphene oxide boosted the Young's modulus and tensile strength by nearly 4-fold and 3-fold, respectively, and significantly enhanced adhesion, proliferation in mouse mesenchymal stem cells and functionally promoted biomineralization-relevant alkaline phosphatase (ALP) and mineral deposition. The results indicate that composite nanofibers could be excellent and versatile scaffolds for bone tissue engineering. PMID:26952489

  19. 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

  20. Antimicrobial and antioxidant surface modification toward a new silk-fibroin (SF)-L-Cysteine material for skin disease management

    Science.gov (United States)

    Nogueira, Frederico; Granadeiro, Luíza; Mouro, Claudia; Gouveia, Isabel C.

    2016-02-01

    A novel dressing material - silk fibroin fabric (SF)-L-Cysteine (L-Cys) - is here developed to be used as standard treatment for atopic dermatitis (AD), which combines comfort, thermic, and tensile strength properties of silk materials with antioxidant and antimicrobial effects of L-Cys. A careful understanding about the linking strategies is needed in order not to compromise the bioavailability of L-Cys and deplenish its bioactivity. Durability was also addressed through washing cycles and compared with hospital requirements, according to international Standard EN ISO 105-C06:2010. The present research also analyze the interactions between Staphylococcus aureus and SF-L-Cys under simulating conditions of AD and demonstrated the effectiveness of a double covalent grafting, with the importance of SF tyrosine (Tyr) covalent linkage with L-Cys (SF-g-L-Cys/Tyr-g-L-Cys) even after several washing cycles, twenty five, whereas for a disposable application a single covalent mechanism of grafting L-Cys proved to be sufficient (SF-g-L-Cys). Results showed effective antimicrobial activities exhibiting higher inhibition ratios of 98.65% for SF-g-L-Cys after 5 washing cycles, whereas 97.55% for SF-g-L-Cys/Tyr-g-L-Cys after 25 washing cycles, both at pH 9.5 grafting strategy. Furthermore, it is also reported a non-protumoral effect of L-Cys. A new advance is herein achieved at the world of medical antimicrobial textiles tailored to address wound moisture environment and exudate self-cleaning, which may open novel applications as complementary therapy for AD disease.

  1. Silk fibroin film from golden-yellow Bombyx mori is a biocomposite that contains lutein and promotes axonal growth of primary neurons.

    Science.gov (United States)

    Pistone, Assunta; Sagnella, Anna; Chieco, Camilla; Bertazza, Gianpaolo; Varchi, Greta; Formaggio, Francesco; Posati, Tamara; Saracino, Emanuela; Caprini, Marco; Bonetti, Simone; Toffanin, Stefano; Di Virgilio, Nicola; Muccini, Michele; Rossi, Federica; Ruani, Giampiero; Zamboni, Roberto; Benfenati, Valentina

    2016-05-01

    The use of doped silk fibroin (SF) films and substrates from Bombyx mori cocoons for green nanotechnology and biomedical applications has been recently highlighted. Cocoons from coloured strains of B. mori, such as Golden-Yellow, contain high levels of pigments that could have a huge potential for the fabrication of SF based biomaterials targeted to photonics, optoelectronics and neuroregenerative medicine. However, the features of extracted and regenerated SF from cocoons of B. mori Golden-Yellow strain have never been reported. Here we provide a chemophysical characterization of regenerated silk fibroin (RSF) fibers, solution, and films obtained from cocoons of a Golden-Yellow strain of B. mori, by SEM, (1) H-NMR, HPLC, FT-IR, Raman and UV-Vis spectroscopy. We found that the extracted solution and films from B. mori Golden-Yellow fibroin displayed typical Raman spectroscopic and optical features of carotenoids. HPLC-analyses revealed that lutein was the carotenoid contained in the fiber and RSF biopolymer from yellow cocoons. Notably, primary neurons cultured on yellow SF displayed a threefold higher neurite length than those grown of white SF films. The results we report pave the way to expand the potential use of yellow SF in the field of neuroregenerative medicine and provide green chemistry approaches in biomedicine. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 287-299, 2016. PMID:26756916

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

    International Nuclear Information System (INIS)

    Biomaterials that stimulate cell attachment and proliferation without any surface modification (e.g. RGD coating) provide potent and cost effective scaffold for regenerative medicine. This study assessed the physico-chemical properties and cell supportive potential of a silk fibroin blend scaffold derived from eri (Philosamia ricini) and tasar (Antheraea mylitta) silk (ET) respectively by electrospinning process. The scanning electron microscopy and transmission electron microscopy study found that the fiber diameters are in 200 to 800 nm range with flat morphology. The porosity of ET scaffold is found to be 79 ± 5% with majority of pore diameter between 2.5 to 5 nm. Similarly, Bombyx mori (BM) silk fibroin and gelatin nanofibrous scaffolds were prepared and taken as control. The ultimate tensile strength of the ET and BM scaffold are found to be 1.83 ± 0.13 MPa and 1.47 ± 0.10 MPa respectively. The measured contact angle (a measure of hydrophilicity) for ET (54.7° ± 1.8°) is found to be lower than BM (62° ± 2.3°). The ability to deposit apatite over ET is comparable to that of BM nanofibers. All the scaffolds were seeded with cord blood derived mesenchymal stem cells (hMSCs) and cultured for 14 days in vitro. The immunofluorescence study reveals enhanced cell attachment with higher metabolic activity for MSCs grown over ET than BM and gelatin. The ET scaffold also demonstrated expression of higher amount cell adhesion molecules (CD29/CD44) and higher proliferation rate than BM and gelatin as confirmed by MTT assay, DNA content estimation assay, flow cytometry study and SEM study. Overall, it may be concluded that ET scaffold may have potential in developing bone tissue grafts for clinical applications in the future. - Highlights: • We have fabricated eri–tasar blended electrospun silk fibroin nanofiber with superior surface property. • The hydrophilicity is higher than the silk fibroin nanofiber derived from Bombyx mori (BM). • The nanofibrous scaffold showed improved cell adhesion and proliferation property. • The expression of CD44 and CD29 over the MSC grown over this is substantially higher than BM. • The metabolic activity of MSC grown over this scaffold is greater than those from BM

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

    Energy Technology Data Exchange (ETDEWEB)

    Panda, N.; Bissoyi, A.; Pramanik, K.; Biswas, A., E-mail: amitb79@gmail.com

    2015-03-01

    Biomaterials that stimulate cell attachment and proliferation without any surface modification (e.g. RGD coating) provide potent and cost effective scaffold for regenerative medicine. This study assessed the physico-chemical properties and cell supportive potential of a silk fibroin blend scaffold derived from eri (Philosamia ricini) and tasar (Antheraea mylitta) silk (ET) respectively by electrospinning process. The scanning electron microscopy and transmission electron microscopy study found that the fiber diameters are in 200 to 800 nm range with flat morphology. The porosity of ET scaffold is found to be 79 ± 5% with majority of pore diameter between 2.5 to 5 nm. Similarly, Bombyx mori (BM) silk fibroin and gelatin nanofibrous scaffolds were prepared and taken as control. The ultimate tensile strength of the ET and BM scaffold are found to be 1.83 ± 0.13 MPa and 1.47 ± 0.10 MPa respectively. The measured contact angle (a measure of hydrophilicity) for ET (54.7° ± 1.8°) is found to be lower than BM (62° ± 2.3°). The ability to deposit apatite over ET is comparable to that of BM nanofibers. All the scaffolds were seeded with cord blood derived mesenchymal stem cells (hMSCs) and cultured for 14 days in vitro. The immunofluorescence study reveals enhanced cell attachment with higher metabolic activity for MSCs grown over ET than BM and gelatin. The ET scaffold also demonstrated expression of higher amount cell adhesion molecules (CD29/CD44) and higher proliferation rate than BM and gelatin as confirmed by MTT assay, DNA content estimation assay, flow cytometry study and SEM study. Overall, it may be concluded that ET scaffold may have potential in developing bone tissue grafts for clinical applications in the future. - Highlights: • We have fabricated eri–tasar blended electrospun silk fibroin nanofiber with superior surface property. • The hydrophilicity is higher than the silk fibroin nanofiber derived from Bombyx mori (BM). • The nanofibrous scaffold showed improved cell adhesion and proliferation property. • The expression of CD44 and CD29 over the MSC grown over this is substantially higher than BM. • The metabolic activity of MSC grown over this scaffold is greater than those from BM.

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

    Science.gov (United States)

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

    2002-08-01

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

  5. 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

  6. 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

  7. 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.

  8. Composite biodegradable biopolymer coatings of silk fibroin - Poly(3-hydroxybutyric-acid-co-3-hydroxyvaleric-acid) for biomedical applications

    Science.gov (United States)

    Miroiu, Floralice Marimona; Stefan, Nicolaie; Visan, Anita Ioana; Nita, Cristina; Luculescu, Catalin Romeo; Rasoga, Oana; Socol, Marcela; Zgura, Irina; Cristescu, Rodica; Craciun, Doina; Socol, Gabriel

    2015-11-01

    Composite silk fibroin-poly(3-hydroxybutyric-acid-co-3-hydroxyvaleric-acid) (SF-PHBV) biodegradable coatings were grown by Matrix Assisted Pulsed Laser Evaporation on titanium substrates. Their physico-chemical properties and particularly the degradation behavior in simulated body fluid at 37 °C were studied as first step of applicability in local controlled release for tissue regeneration applications. SF and PHBV, natural biopolymers with excellent biocompatibility, but different biodegradability and tensile strength properties, were combined in a composite to improve their properties as coatings for biomedical uses. FTIR analyses showed the stoichiometric transfer from targets to coatings by the presence in the spectra of the main absorption maxima characteristic of both polymers. XRD investigations confirmed the FTIR results showing differences in crystallization behavior with respect to the SF and PHBV content. Contact angle values obtained through wettability measurements indicated the MAPLE deposited coatings were highly hydrophilic; surfaces turning hydrophobic with the increase of the PHBV component. Degradation assays proved that higher PHBV contents resulted in enhanced resistance and a slower degradation rate of composite coatings in SBF. Distinct drug-release schemes could be obtained by adjusting the SF:PHBV ratio to controllably tuning the coatings degradation rate, from rapid-release formulas, where SF predominates, to prolonged sustained ones, for larger PHBV content.

  9. Fabrication and structure analysis of poly(lactide-co-glycolic acid)/silk fibroin hybrid scaffold for wound dressing applications.

    Science.gov (United States)

    Shahverdi, Sheida; Hajimiri, Mirhamed; Esfandiari, Mohammad Amin; Larijani, Bagher; Atyabi, Fatemeh; Rajabiani, Afsaneh; Dehpour, Ahmad Reza; Gharehaghaji, Ali Akbar; Dinarvand, Rassoul

    2014-10-01

    Silk fibroin (SF) and poly(lactide-co-glycolic acid) (PLGA) have been proved to be invaluable polymers in the field wound healing. This study aims at optimizing the electrospinning process of those polymers to make a hybrid membrane as a chronic wounds dressing. After characterizing the scaffolds, PLGA/SF (2:1), and PLGA scaffolds were selected for further study according to their superior tensile mechanical properties. The attachment and proliferation of mouse fibroblasts (L929) on scaffolds were measured using colorimetric assay and scanning electron microscopy. Furthermore, to evaluate the wound healing effect of the scaffolds in comparison with gauze and Comfeel(®) dressings, an excision wound model was conducted on diabetic rats. On the postoperative days of 3, 6, 9, 12, and 15, residual wound area was calculated using macroscopic data. In vitro results showed that the attachment and proliferation of L929 were significantly increased on PLGA/SF (2:1) hybrid scaffold. Animal study and histopathological evaluation outcomes confirmed the in vitro results as well. On day 15, the residual wound area in PLGA/SF (2:1) hybrid membrane group was significantly smaller than PLGA and control groups. This promising scaffold has the potential to be used for the upcoming development of wound dressings with or without biological drugs. PMID:25051110

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

    International Nuclear Information System (INIS)

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

  11. Tissue performance of bladder following stretched electrospun silk fibroin matrix and bladder acellular matrix implantation in a rabbit model.

    Science.gov (United States)

    Huang, Jian-Wen; Xu, Yue-Min; Li, Zhao-Bo; Murphy, Sean V; Zhao, Weixin; Liu, Qiang-Qiang; Zhu, Wei-Dong; Fu, Qiang; Zhang, Yao-Peng; Song, Lu-Jie

    2016-01-01

    The goal of this study was to investigate the tissue performance of bladder following stretched electrospun silk fibroin matrix (SESFM) implantation compared with bladder acellular matrix (BAM). We compared SESFM with BAM based on porosity and pore size. Scaffolds were separately transplanted into opposite walls of the bladder of 30 rabbits after stripping the bladder mucosa and smooth muscle (1.5 × 2.0 cm(2) ). Gross anatomical observation, histological analysis and muscle contractility studies were performed at 2, 4, and 8 weeks post-op. SESFM has higher porosity and larger pore size compared with BAM (p??0.05). However, SESFM promoted a higher degree of smooth muscle and vessel regeneration compared to BAM (p?muscle strips supported by SESFM displayed higher contractile responses to carbachol, KCl, and phenylephrine compared with BAM. At 8 weeks, both matrices elicited similar mild acute and chronic inflammatory reactions. Our results demonstrated that SESFM has greater ability to promote bladder tissue regeneration with structural and functional properties compared to BAM, and with similar biocompatibility. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 9-16, 2016. PMID:26148477

  12. 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.

  13. 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.

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

    Directory of Open Access Journals (Sweden)

    Prasong Srihanam

    2011-01-01

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

  15. Slip knots and unfastening topologies enhance toughness without reducing strength of silk fibroin fibres.

    Science.gov (United States)

    Berardo, Alice; Pantano, Maria F; Pugno, Nicola M

    2016-02-01

    The combination of high strength and high toughness is a desirable feature that structural materials should display. However, while in the past, engineers had to compromise on either strength or toughness depending on the requested application, nowadays, new toughening strategies are available to provide strong materials with high toughness. In this paper, we focus on one of such strategy, which requires no chemical treatment, but the implementation of slip knots with optimized shape and size in the involved material, which is silkworm silk in this case. In particular, a variety of slip knot topologies with different unfastening mechanisms are investigated, including even complex knots usually used in the textile industry, and their efficiency in enhancing toughness of silk fibres is discussed. PMID:26855750

  16. 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

  17. 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...

  18. 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)

  19. 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.

  20. Bioactivity of porous biphasic calcium phosphate enhanced by recombinant human bone morphogenetic protein 2/silk fibroin microsphere.

    Science.gov (United States)

    Chen, Liang; Gu, Yong; Feng, Yu; Zhu, Xue-Song; Wang, Chun-Zeng; Liu, Hai-Long; Niu, Hai-Yun; Zhang, Chi; Yang, Hui-Lin

    2014-07-01

    To prepare a bioactive bone substitute, which integrates biphasic calcium phosphate (BCP) and rhBMP-2/silk fibroin (SF) microsphere, and to evaluate its characteristics. Hydroxyapatite and ?-tricalcium phosphate were integrated with a ratio of 60–40%. RhBMP-2/SF (0.5 ?g/1 mg) microsphere was prepared, and its rhBMP-2-release kinetics was assed. After joining pore-forming agent (Sodium chloride, NaCl), porous BCP/rhBMP-2/SF were manufactured, and its characteristics and bioactivity in vitro were evaluated. Mean diameter of rhBMP-2/SF microsphere was 398.7 ± 99.86 nm, with a loading rate of 4.53 ± 0.08%. RhBMP-2 was released in a dual-phase pattern, of which fast-release (nearly half of protein released) focused on the initial 3 days, and slow-release sustained more than 28 days. With the increase in concentration of NaCl, greater was porosity and pore size, but smaller mechanical strength of BCP/rhBMP-2/SF. Material with 150% (w/v) NaCl had an optimal performance, with a porosity of 78.83%, pore size of 293.25 ± 42.77?m and mechanical strength of 31.03 MPa. Proliferation of human placenta-derived mesenchymal stem cells (hPMSCs) on leaching extract medium was similar to the normal medium (P = 0.89), which was better than that on control group (P = 0.03). Activity of alkaline phosphatase on BCP/rhBMP-2/SF surface was higher than on pure BCP at each time point except at 1 day (P agent has excellent porosity, pore size and mechanical strength. The biomaterial induces proliferation and differentiation hPMSCs effectively. PMID:24659100

  1. 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

  2. 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

  3. New application of silk protein

    International Nuclear Information System (INIS)

    Gunma prefecture is famous for sericulture and silk textile industry district in Japan. In Gunma prefecture, some kinds of new generation silk as high performance and high quality silk were developed. These silk are used not only for the new textile materials but also for new industrial materials. New application of silk protein, fibroin and sericin, is considered. (author)

  4. New application of silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Kamiishi, Youichi [Textile Research Institute of Gunma, Kiryu, Gunma (Japan)

    2000-03-01

    Gunma prefecture is famous for sericulture and silk textile industry district in Japan. In Gunma prefecture, some kinds of new generation silk as high performance and high quality silk were developed. These silk are used not only for the new textile materials but also for new industrial materials. New application of silk protein, fibroin and sericin, is considered. (author)

  5. Purification and some properties of G-factor from the silk gland of silkworm

    International Nuclear Information System (INIS)

    Purification of G-factor from the silk gland of silkworms and some of its properties have been studied in comparison with the G-factor from E. coli and rat liver transferase II. In the experiment, GTP-?-32P was prepared from GDP and 32Pi by photophosphorylation with spinach chloroplasts, and purified by Dowex-1 chromatography. The purified G-factor was homogeneous on disc gel electrophoresis. Molecular weight of 80,000 was estimated from a calibrated Sephadex G-200 column. The purified G-factor exhibited uncoupled ribosome-dependent GTPase activity, and was inhibited by fusidic acid, SH inhibitor, and diphtheria toxin plus NAD. The G-factor from E. coli and that from the silk gland were not interchangeable in GTPase reaction. (Yamanoto, Y.)

  6. Reducing blood glucose level in TIDM mice by orally administering the silk glands of transgenic hIGF-I silkworms.

    Science.gov (United States)

    Cong, Liang; Cao, Guangli; Renyu, Xue; Zhonghua, Pan; Xiaojian, Zheng; Zhou, Wenlin; Gong, Chengliang

    2011-07-15

    To realize the secretory expression of human insulin-like growth factor-I (hIGF-I) in the posterior silk glands (PSGs) of transgenic silkworms, the piggyBac transposon vector pigA3GFP-fibHS-hIGF-i.e.-neo containing a neomycin-resistance gene (neo), green fluorescent protein gene (gfp) and human insulin-like growth factor I (hIGF-I) gene controlled by the Bombyxmori fibroin heavy chain gene (fib-H) promoter with its downstream signal peptide sequence, and a helper plasmid containing the piggyBac transposase sequence under the control of the B. mori actin 3 gene (A3) promoter were transferred into silkworm eggs by sperm-mediated gene transfer. Transformed silkworms were obtained after being screened for green fluorescence and by the antibiotic G418. In the PSGs of the transformed silkworms, a specific band representing hIGF-I could be detected by Western blotting, and the content of the hIGF-I estimated by ELISA was approximately 1.84 ?g/gram of cocoon and 19.18 ?g/gram of freeze-dried PSG powder. To further estimate the biological activity of the expressed hIGF-I, streptozotocin-induced TIDM mice were orally administered with the PSG powder of the transgenic silkworms, the results showed the blood glucose levels of mice were significantly reduced, suggesting that the the PSGs powder of transgenic hIGF-I silkworms could possibly be used as a perorally administered medicine. PMID:21672515

  7. Development of novel electrospun nanofibrous scaffold from P. Ricini And A. Mylitta silk fibroin blend with improved surface and biological properties.

    Science.gov (United States)

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

    2015-03-01

    Biomaterials that stimulate cell attachment and proliferation without any surface modification (e.g. RGD coating) provide potent and cost effective scaffold for regenerative medicine. This study assessed the physico-chemical properties and cell supportive potential of a silk fibroin blend scaffold derived from eri (Philosamia ricini) and tasar (Antheraea mylitta) silk (ET) respectively by electrospinning process. The scanning electron microscopy and transmission electron microscopy study found that the fiber diameters are in 200 to 800nm range with flat morphology. The porosity of ET scaffold is found to be 79±5% with majority of pore diameter between 2.5 to 5nm. Similarly, Bombyx mori (BM) silk fibroin and gelatin nanofibrous scaffolds were prepared and taken as control. The ultimate tensile strength of the ET and BM scaffold are found to be 1.83±0.13MPa and 1.47±0.10MPa respectively. The measured contact angle (a measure of hydrophilicity) for ET (54.7°±1.8°) is found to be lower than BM (62°±2.3°). The ability to deposit apatite over ET is comparable to that of BM nanofibers. All the scaffolds were seeded with cord blood derived mesenchymal stem cells (hMSCs) and cultured for 14days in vitro. The immunofluorescence study reveals enhanced cell attachment with higher metabolic activity for MSCs grown over ET than BM and gelatin. The ET scaffold also demonstrated expression of higher amount cell adhesion molecules (CD29/CD44) and higher proliferation rate than BM and gelatin as confirmed by MTT assay, DNA content estimation assay, flow cytometry study and SEM study. Overall, it may be concluded that ET scaffold may have potential in developing bone tissue grafts for clinical applications in the future. PMID:25579953

  8. 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.

  9. In vitro and in vivo studies on the cytotoxicity of irradiated silk fibroin against mouse melanoma tumor cell

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Eui-Baek [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Division of Bioresources and Biosciences, Faculty of Agriculture, Graduate school of Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Sung, Nak-Yun [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Kwon, Sun-Kyu [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Graduate school of Food and Biotechnology, Korea University, Jochiwon 339-800 (Korea, Republic of); Song, Beom-Seok; Kim, Jae-Hun; Choi, Jong-il [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Hwang, Han-Joon [Graduate school of Food and Biotechnology, Korea University, Jochiwon 339-800 (Korea, Republic of); Byun, Myung-Woo [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Lee, Ju-Woon [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)], E-mail: sjwlee@kaeri.re.kr

    2009-07-15

    The physicochemical properties of proteins can be altered by irradiation. But, it is rarely that the researches on the functional properties of irradiated proteins have been reported. Fibroin is a fibrous protein derived from silkworm Bombyx mori and has been suggested as a biomaterial for biomedical application. Therefore, fibroin was selected as a model protein and was examined with the irradiation effects on the cytotoxicity of fibroin on tumor cell. The cytotoxicity of fibroin against mouse melanoma cell (B16BL6) showed a significant increase dependent upon the increase of irradiation dose. And also, the splenocyte proliferation activities of fibroin were increased by gamma irradiation. In addition, the oral administration of irradiated fibroin significantly increased the inhibition rate of tumor growth in tumor-bearing mouse model. The reason might be due to the change of protein structure by gamma irradiation and is being studied. From these result, it could be concluded that the irradiated fibroin might be a potential candidate as a valuable product in food and medical industry.

  10. In vitro and in vivo studies on the cytotoxicity of irradiated silk fibroin against mouse melanoma tumor cell

    Science.gov (United States)

    Byun, Eui-Baek; Sung, Nak-Yun; Kwon, Sun-Kyu; Song, Beom-Seok; Kim, Jae-Hun; Choi, Jong-il; Hwang, Han-Joon; Byun, Myung-Woo; Lee, Ju-Woon

    2009-07-01

    The physicochemical properties of proteins can be altered by irradiation. But, it is rarely that the researches on the functional properties of irradiated proteins have been reported. Fibroin is a fibrous protein derived from silkworm Bombyx mori and has been suggested as a biomaterial for biomedical application. Therefore, fibroin was selected as a model protein and was examined with the irradiation effects on the cytotoxicity of fibroin on tumor cell. The cytotoxicity of fibroin against mouse melanoma cell (B16BL6) showed a significant increase dependent upon the increase of irradiation dose. And also, the splenocyte proliferation activities of fibroin were increased by gamma irradiation. In addition, the oral administration of irradiated fibroin significantly increased the inhibition rate of tumor growth in tumor-bearing mouse model. The reason might be due to the change of protein structure by gamma irradiation and is being studied. From these result, it could be concluded that the irradiated fibroin might be a potential candidate as a valuable product in food and medical industry.

  11. 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

  12. Physico-chemical properties and efficacy of silk fibroin fabric coated with different waxes as wound dressing.

    Science.gov (United States)

    Kanokpanont, Sorada; Damrongsakkul, Siriporn; Ratanavaraporn, Juthamas; Aramwit, Pornanong

    2013-04-01

    Silk fibroin (SF) has been widely used as a wound dressing material due to its suitable physical and biological characteristics. In this study, a non-adhesive wound dressing which applies to cover the wound surface as an absorbent pad that would absorb wound fluid while accelerate wound healing was developed. The modification of SF fabrics by wax coating was purposed to prepare the non-adhesive wound dressing that is required in order to minimize pain and risk of repeated injury. SF woven fabrics were coated with different types of waxes including shellac wax, beeswax, or carnauba wax. Physical and mechanical properties of the wax-coated SF fabrics were characterized. It was clearly observed that all waxes could be successfully coated on the SF fabrics, possibly due to the hydrophobic interactions between hydrophobic domains of SF and waxes. The wax coating improved tensile modulus and percentage of elongation of the SF fabrics due to the denser structure and the thicker fibers coated. The in vitro degradation study demonstrated that all wax-coated SF fabrics remained up to 90% of their original weights after 7 weeks of incubation in lysozyme solution under physiological conditions. The wax coating did not affect the degradation behavior of the SF fabrics. A peel test of the wax-coated SF fabrics was carried out in the partial- and full-thickness wounds of porcine skin in comparison to that of the commercial wound dressing. Any wax-coated SF fabrics were less adhesive than the control, as confirmed by less number of cells attached and less adhesive force. This might be that the wax-coated SF fabrics showed the hydrophobic property, allowing the loosely adherence to the hydrophilic wound surface. In addition, the in vivo biocompatibility test of the wax-coated SF fabrics was performed in Sprague-Dawley rats with subcutaneous model. The irritation scores indicated that the carnauba wax-coated SF fabric was not irritant while the shellac wax or beeswax-coated SF fabrics were slightly irritant, comparing with the commercial wound dressing. Therefore, SF fabrics coated with waxes, particularly carnauba wax, would be promising choices of non-adhesive wound dressing. PMID:23313451

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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 β1 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

  18. 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 ...

  19. 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

  20. 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

  1. DNA Synthesis during Endomitosis Is Stimulated by Insulin via the PI3K/Akt and TOR Signaling Pathways in the Silk Gland Cells of Bombyx mori

    Directory of Open Access Journals (Sweden)

    Yaofeng Li

    2015-03-01

    Full Text Available Silk gland cells undergo multiple endomitotic cell cycles during silkworm larval ontogeny. Our previous study demonstrated that feeding is required for continued endomitosis in the silk gland cells of silkworm larvae. Furthermore, the insulin signaling pathway is closely related to nutritional signals. To investigate whether the insulin signaling pathway is involved in endomitosis in silk gland cells, in this study, we initially analyzed the effects of bovine insulin on DNA synthesis in endomitotic silk gland cells using 5-bromo-2'-deoxyuridine (BrdU labeling technology, and found that bovine insulin can stimulate DNA synthesis. Insulin signal transduction is mainly mediated via phosphoinositide 3-kinase (PI3K/Akt, the target of rapamycin (TOR and the extracellular signal-regulated kinase (ERK pathways in vertebrates. We ascertained that these three pathways are involved in DNA synthesis in endomitotic silk gland cells using specific inhibitors against each pathway. Moreover, we investigated whether these three pathways are involved in insulin-stimulated DNA synthesis in endomitotic silk gland cells, and found that the PI3K/Akt and TOR pathways, but not the ERK pathway, are involved in this process. These results provide an important theoretical foundation for the further investigations of the mechanism underlying efficient endomitosis in silk gland cells.

  2. 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

  3. 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...

  4. 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.

  5. Change in silk protein by radiation

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-03-01

    Silk fibroin fiber irradiated with an accelerated electron beam in the dose range of 250 - 1,000 kGy was pulverized by using a ball mill. As irradiation dose increased, the conversion efficiency from fiber to powder increased, which reached 94% at 1,000 kGy. Silk fibroin powder obtained by this method dissolved 57% into water of ambient temperature. It is a very interesting phenomenon that silk fibroin obtains solubility without chemical treatment. In order to study mechanism of solubilization of silk fibroin powder, amino acid component of soluble part of silk powder was performed. The more irradiation dose up, the more recovery fraction of glycine or alanine decreased, which is, however, reached the minimum about 50%. To consider this result with crystal structure of silk fibroin, it is suggested that irradiation on silk fibroin fiber selectively degrades glycine and alanine in amorphous region, which makes it possible to pulverize and to dissolve for silk fibroin powder. Molecular weight of soluble part was also measured, but it had no serious concern with irradiation dose. Particle size distribution of silk fibroin powder was measured in order to study reduction of irradiation dose needed for pulverization. This measurement exhibited the possibility that lengthening of pulverization time reduces of irradiation dose. In addition, structure of particle was inferred from result of this measurement. (author)

  6. 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

  7. 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

  8. Quantitative analyses of the effect of silk fibroin/nano-hydroxyapatite composites on osteogenic differentiation of MG-63 human osteosarcoma cells.

    Science.gov (United States)

    Lin, Linxue; Hao, Runsong; Xiong, Wei; Zhong, Jian

    2015-05-01

    Silk fibroin (SF)/nano-hydroxyapatite (n-HA) composites are potential biomaterials for bone defect repair. Up to now, the biological evaluation studies of SF/n-HA composites have primarily concentrated on their biocompatibility at cell level such as cell viability and proliferation and tissue level such as material absorption and new bone formation. In this work, SF/n-HA composites were fabricated using a simplified coprecipitation methods and were deposited onto Ti alloy substrates. Then the cell adhesion ability of SF/n-HA composites was observed by SEM and cell proliferation ability of SF/n-HA composites was determined by MTT assay. The ALP activity, BGP contents, and Col I contents of MG-63 human osteosarcoma cells on SF/n-HA composites were quantitatively analyzed. HA nanocrystals were used as controls. These experiments showed that SF/n-HA composites had better cell adhesion and osteogenic differentiation abilities than n-HA materials. This work provides quantitative data to analyze the effect of SF/n-HA composites on cell osteogenic differentiation. PMID:25454062

  9. Amperometric biosensor based on tyrosinase immobilized onto multiwalled carbon nanotubes-cobalt phthalocyanine-silk fibroin film and its application to determine bisphenol A

    International Nuclear Information System (INIS)

    An amperometric bisphenol A (BPA) biosensor was fabricated by immobilizing tyrosinase on multiwalled carbon nanotubes (MWNTs)-cobalt phthalocyanine (CoPc)-silk fibroin (SF) composite modified glassy carbon electrode (GCE). In MWNTs-CoPc-SF composite film, SF provided a biocompatible microenvironment for the tyrosinase to retain its bioactivity, MWNTs possessed excellent inherent conductivity to enhance the electron transfer rate and CoPc showed good electrocatalytic activity to electrooxidation of BPA. The cyclic voltammogram of BPA at this biosensor exhibited a well defined anodic peak at 0.625 V. Compared with bare GCE, the oxidation signal of BPA significantly increased; therefore, this oxidation signal was used to determine BPA. The effect factors were optimized and the electrochemical parameters were calculated. The possible oxidation mechanism was also discussed. Under optimum conditions, the oxidation current was proportional to BPA concentration in the range from 5.0 x 10-8 to 3.0 x 10-6 M with correlation coefficient of 0.9979 and detection limit of 3.0 x 10-8 M (S/N = 3). The proposed method was successfully applied to determine BPA in plastic products and the recovery was in the range from 95.36% to 104.39%.

  10. A Silk Fibroin/Collagen Nerve Scaffold Seeded with a Co-Culture of Schwann Cells and Adipose-Derived Stem Cells for Sciatic Nerve Regeneration

    Science.gov (United States)

    Li, Ruixin; Li, Dong; Feng, Shiqing

    2016-01-01

    As a promising alternative to autologous nerve grafts, tissue-engineered nerve grafts have been extensively studied as a way to bridge peripheral nerve defects and guide nerve regeneration. The main difference between autogenous nerve grafts and tissue-engineered nerve grafts is the regenerative microenvironment formed by the grafts. If an appropriate regenerative microenvironment is provided, the repair of a peripheral nerve is feasible. In this study, to mimic the body’s natural regenerative microenvironment closely, we co-cultured Schwann cells (SCs) and adipose-derived stem cells (ADSCs) as seed cells and introduced them into a silk fibroin (SF)/collagen scaffold to construct a tissue-engineered nerve conduit (TENC). Twelve weeks after the three different grafts (plain SF/collagen scaffold, TENC, and autograft) were transplanted to bridge 1-cm long sciatic nerve defects in rats, a series of electrophysiological examinations and morphological analyses were performed to evaluate the effect of the tissue-engineered nerve grafts on peripheral nerve regeneration. The regenerative outcomes showed that the effect of treatment with TENCs was similar to that with autologous nerve grafts but superior to that with plain SF/collagen scaffolds. Meanwhile, no experimental animals had inflammation around the grafts. Based on this evidence, our findings suggest that the TENC we developed could improve the regenerative microenvironment and accelerate nerve regeneration compared to plain SF/collagen and may serve as a promising strategy for peripheral nerve repair. PMID:26799619

  11. 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.

  12. 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

  13. 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...

  14. 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...

  15. 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

  16. An Australian webspinner species makes the finest known insect silk fibers

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-15

    Aposthonia gurneyi, an Australian webspinner species, is a primitive insect that constructs and lives in a silken tunnel which screens it from the attentions of predators. The insect spins silk threads from many tiny spines on its forelegs to weave a filmy sheet. We found that the webspinner silk fibers have a mean diameter of only 65 nm, an order of magnitude smaller than any previously reported insect silk. The purpose of such fine silk may be to reduce the metabolic cost of building the extensive tunnels. At the molecular level, the A. gurneyi silk has a predominantly beta-sheet protein structure. The most abundant clone in a cDNA library produced from the webspinner silk glands encoded a protein with extensive glycine-serine repeat regions. The GSGSGS repeat motif of the A. gurneyi silk protein is similar to the well-known GAGAGS repeat motif found in the heavy fibroin of silkworm silk, which also has beta-sheet structure. As the webspinner silk gene is unrelated to the silk gene of the phylogenetically distant silkworm, this is a striking example of convergent evolution.

  17. 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

  18. Evaluating degradation of silk's fibroin by attenuated total reflectance infrared spectroscopy: Case study of ancient banners from Polish collections

    Science.gov (United States)

    Koperska, M. A.; ?ojewski, T.; ?ojewska, J.

    2015-01-01

    In this study a part of research where artificially aged model samples were used as a guideline to the mechanism of degradation is presented. In previous work Bombyx Mori silk samples were exposed to various environments such as different oxygen, water vapour and volatile organic products content, all at the temperature of 150 °C [11]. Based on those results gathered with by Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy (ATR-FTIR) the degradation estimators were proposed and classified as follows: Primary functional groups estimators EAmideI/II - intensity ratios of Amide I Cdbnd O stretching vibration to Amide II Nsbnd H in-plane bending and Csbnd N stretching vibrations A1620/A1514. ECOOH - band 1318 cm-1 integral to band integral of CH3 bending vibration band located at 1442 cm-1P1318/P1442. Secondary conformational estimators EcCdbndO2 - intensity ratios within Amide I Cdbnd O stretching vibration of parallel ?-sheet to antiparallel ?-sheet A1620/A1699. In this work estimators were verified against estimators calculated from spectra of silk samples from 8 museum objects: 3 from 19th, 2 from 18th, 1 from 17th and 2 from 16th century including 3 banners from the storage resources of the Wawel Royal Castle in Cracow, Poland.

  19. 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

  20. 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

  1. Response of human mesenchymal stem cells to intrafibrillar nanohydroxyapatite content and extrafibrillar nanohydroxyapatite in biomimetic chitosan/silk fibroin/nanohydroxyapatite nanofibrous membrane scaffolds

    Science.gov (United States)

    Lai, Guo-Jyun; Shalumon, KT; Chen, Jyh-Ping

    2015-01-01

    Incorporation of nanohydroxyapatite (nHAP) within a chitosan (CS)/silk fibroin (SF) nanofibrous membrane scaffold (NMS) may provide a favorable microenvironment that more closely mimics the natural bone tissue physiology and facilitates enhanced osteogensis of the implanted cell population. In this study, we prepared pristine CS/SF NMS, composite CS/SF/nHAP NMS containing intrafibrillar nHAP by in situ blending of 10% or 30% nHAP before the electrospinning step, and composite CS/SF/nHAP NMS containing extrafibrillar nHAP by depositing 30% nHAP through alternative soaking surface mineralization. We investigated the effect of the incorporation of HAP nanoparticles on the physicochemical properties of pristine and composite NMS. We confirmed the presence of ~30 nm nHAP in the composite nanofibrous membranes by thermogravimetry analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM), either embedded in or exposed on the nanofiber. Nonetheless, the alternative soaking surface mineralization method drastically influenced the mechanical properties of the NMS with 88% and 94% drop in Young’s modulus and ultimate maximum stress. Using in vitro cell culture experiments, we investigated the effects of nHAP content and location on proliferation and osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs). The proliferation of hMSCs showed no significant difference among pristine and composite NMS. However, the extent of osteogenic differentiation of hMSCs was found to be positively correlated with the content of nHAP in the NMS, while its location within the nanofiber played a less significant role. In vivo experiments were carried out with hMSCs seeded in CS/SF/30%nHAP NMS prepared by in situ blending and subcutaneous implantation in nude mice. Micro-computed tomography images as well as histological and immunohistochemical analysis of the retrieved hMSCs/NMS construct 1 and 2 months postimplantation indicated that NMS had the potential for bone regeneration and can be suggested as a promising scaffold for bone tissue engineering. PMID:25609962

  2. 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

  3. Analyses of the Molecular Mechanisms Associated with Silk Production in Silkworm by iTRAQ-Based Proteomics and RNA-Sequencing-Based Transcriptomics.

    Science.gov (United States)

    Wang, Shaohua; You, Zhengying; Feng, Mao; Che, Jiaqian; Zhang, Yuyu; Qian, Qiujie; Komatsu, Setsuko; Zhong, Boxiong

    2016-01-01

    Silkworm is used as a model organism to analyze two standard complex traits, which are high and low silk yields. To understand the molecular mechanisms of silk production, the posterior silk glands aged to the third day of the fifth instar were analyzed from the ZB strain with low silk production and from the control strain Lan10. Using isobaric tags for relative and absolute quantification (iTRAQ) quantitative shotgun proteomics and RNA-sequencing-based transcriptomics, 139 proteins and 630 transcripts were identified as novel in the ZB strain compared with the Lan10 strain, indicating that these results significantly expand the coverage of proteins and transcripts of the posterior silk glands in the silkworm. Of the 89 differently changed proteins, 23 were increased, and 66 were decreased. Of the 788 transcripts, 779 were upregulated, and 9 were downregulated. These results confirm that decreased energy utilization/protein translation and enhanced protein degradation are the key factors in lower silk production. Moreover, this study provides novel insight into the molecular changes that may result in lower silk production, namely, a combination of impaired transcription activity, missed protein folding/transport, and lowered yields of the main components of fibroin, along with weakened growth/development of the posterior silk gland. PMID:26626507

  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. Molecular mechanisms of silk gland damage caused by phoxim exposure and protection of phoxim-induced damage by cerium chloride in Bombyx mori.

    Science.gov (United States)

    Li, Bing; Sun, Qingqing; Yu, Xiaohong; Xie, Yi; Hong, Jie; Zhao, Xiaoyang; Sang, Xuezi; Shen, Weide; Hong, Fashui

    2015-09-01

    It is known that exposure to organophosphorus pesticides (OP) including phoxim can produce oxidative stress, neurotoxicity, and greatly attenuate cocooning rate in the silkworm, Bombyx mori. Cerium treatment has been demonstrated to relieve phoxim-induced toxicity in B. mori; however, very little is known about the molecular mechanisms of silk gland injury due to OP exposure and protection of gland damage due to cerium pretreatment. The aim of this study was to evaluate silk gland damage and its molecular mechanisms in phoxim-induced silkworm toxicity and the protective mechanisms of cerium following exposure to phoxim. The results showed that phoxim exposure resulted in severe gland damage, reductions in protein synthesis and the cocooning rate of silkworms. Cerium (Ce) attenuated gland damage caused by phoxim, promoted protein synthesis, increased the antioxidant capacity of the gland and increased the cocooning rate of B. mori. Furthermore, digital gene expression data suggested that phoxim exposure led to significant up-regulation of 714 genes and down-regulation of 120 genes. Of these genes, 122 were related to protein metabolism, specifically, the down-regulated Ser2, Ser3, Fib-L, P25, and CYP450. Ce pretreatment resulted in up-regulation of 162 genes, and down-regulation of 141 genes, importantly, Ser2, Ser3, Fib-L, P25, and CYP333B8 were up-regulated. Treatment with CeCl3 + phoxim resulted in higher levels of Fib-L, P25, Ser2, Ser3, CAT, TPx, and CYP333B8 expression in the silk gland of silkworms. These findings indicated that Ce increased cocooning rate via the promotion of silk protein synthesis-related gene expression in the gland under phoxim-induced toxicity. These findings may expand the application of rare earths in sericulture. PMID:24616058

  6. 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

  7. Expression of hIGF-I in the silk glands of transgenic silkworms and in transformed silkworm cells.

    Science.gov (United States)

    Zhao, Yue; Li, Xi; Cao, GuangLi; Xue, RenYu; Gong, ChengLiang

    2009-12-01

    To express human insulin-like growth factor-I (hIGF-I) in transformed Bombyx mori cultured cells and silk glands, the transgenic vector pigA3GFP-hIGF-ie-neo was constructed with a neomycin resistance gene driven by the baculovirus ie-1 promoter, and with the hIGF-I gene under the control of the silkworm sericin promoter Ser-1. The stably transformed BmN cells expressing hIGF-I were selected by using the antibiotic G418 at a final concentration of 700-800 microg/mL after the BmN cells were transfected with the piggyBac vector and the helper plasmid. The specific band of hIGF-I was detected in the transformed cells by Western blot. The expression level of hIGF-I, determined by ELISA, was about 7800 pg in 5x10(5) cells. Analysis of the chromosomal insertion sites by inverse PCR showed that exogenous DNA could be inserted into the cell genome randomly or at TTAA target sequence specifically for piggyBac element transposition. The transgenic vector pigA3GFP-hIGF-ie-neo was transferred into the eggs using sperm-mediated gene transfer. Finally, two transgenic silkworms were obtained after screening for the neo and gfp genes and verified by PCR and dot hybridization. The expression level of hIGF-I determined by ELISA was about 2440 pg/g of silk gland of the transgenic silkworms of the G1 generation. PMID:20016970

  8. 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.

  9. Radiation degradation of silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Pewlong, W.; Sudatis, B. [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

  10. Radiation degradation of silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Wachiraporn Pewlong; Boonya Sudatis [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-09-01

    Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated in the dose range up to 2500 kGy using an electron beam accelerator to apply the radiation degradation technique as a means to solubilize fibroin. The tensile strength of irradiated fibroin fiber decreased with increasing dose and the presence of oxygen in the irradiation atmosphere enhanced the degradation. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: calcium chloride solution (CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O = 1 : 2 : 8 in mole ratio), hydrochloric acid (0.5N) and distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water-soluble protein was extracted by distilled water. (author)

  11. 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...

  12. 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

  13. 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

  14. In vivo analysis of fibroin heavy chain signal peptide of silkworm Bombyx mori using recombinant baculovirus as vector

    International Nuclear Information System (INIS)

    In order to investigate the functional signal peptide of silkworm fibroin heavy chain (FibH) and the effect of N- and C-terminal parts of FibH on the secretion of FibH in vivo, N- and C-terminal segments of fibh gene were fused with enhanced green fluorescent protein (EGFP) gene. The fused gene was then introduced into silkworm larvae and expressed in silk gland using recombinant AcMNPV (Autographa californica multiple nuclear polyhedrosis virus) as vector. The fluorescence of EGFP was observed with fluorescence microscope. FibH-EGFP fusion proteins extracted from silk gland were analyzed by Western blot. Results showed that the two alpha helices within N-terminal 163 amino acid residues and the C-terminal 61 amino acid residues were not necessary for cleavage of signal peptide and secretion of the fusion protein into silk gland. Then the C-terminal 61 amino acid residues were substituted with a His-tag in the fusion protein to facilitate the purification. N-terminal sequencing of the purified protein showed that the signal cleavage site is between position 21 and 22 amino acid residues

  15. 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

  16. 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...

  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. Production of fine powder from silk by radiation

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-09-01

    To produce silk fine powder, silk fibroin fibers were irradiated with an accelerated electron beam. Though unirradiated silk fibers were not pulverized at all, irradiated silk fibers were able to be crushed only by physical means using a ball mill. In the dose range of 250- 1000 kGy, as the dose to silk fibroin increased, the conversion rate from fiber to powder was increased. The electron microscope observation showed that the particle size of silk powder was less than 10 micrometers, and that those particles composed aggregate. Although silk fibroin fiber was not soluble in water, silk powders from fiber irradiated 500 kGy dissolved more than 50 weight %. Amino acid analysis of soluble fraction in silk powder showed that Gly content is lower than in normal silk and other amino acids contents except for Ala are 1.5 times as large as in normal silk. From these results, it is reasonable to suppose that irradiation and pulverization decomposed Gly and Ala. (author)

  19. 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

  20. 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.

  1. Bilayered silk/silk-nanoCaP scaffolds for osteochondral tissue engineering : in vitro and In vivo assessment of biological performance

    OpenAIRE

    Yan, Leping; Correia, Joana Silva; Oliveira, Mariana B.; Vilela, Carlos; Pereira, H.; Sousa, R A; Mano, J. F.; de Oliveira, A. L.; Oliveira, Joaquim M.; Reis, R.L.

    2015-01-01

    Novel porous bilayered scaffolds, fully integrating a silk fibroin (SF) layer and a silk-nano calcium phosphate (Silk-NanoCaP) layer for osteochondral defect (OCD) regeneration were developed. Homogeneous porosity distribution was achieved in the scaffolds, with calcium phosphate phase only retained in the Silk-NanoCaP layer. The scaffold presented compressive moduli of 0.4 MPa in wet state. Rabbit bone marrow mesenchymal stromal cells (RBMSCs) were cultured on the scaffolds, and good adhesio...

  2. 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

  3. 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

  4. Production of fine powder from silk by radiation

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-03-01

    Silk fine power was prepared directly from silk fiber irradiated with an accelerated electron beam(EB). Irradiated silk fiber was well pulverized only by physical crushing using ball mill without any chemical pretreatment. Raw and degummed silk fibers were irradiated at ambient temperature in the dose range of 250-1000 kGy. Although unirradiated silk fibers were not pulverized at all, irradiated fibers were easily pulverized and showed higher conversion from fiber to powder for higher doses. The presence of oxygen in the irradiation atmosphere enhanced pulverization of silk fiber. Raw silk fibers were less pulverized compared to degummed ones. The electron microscope observation showed that the minimum particle size of silk powder obtained from fiber irradiated by 1000 kGy in oxygen was less than 10 microns. It was found that fibroin powder obtained in this work dissolved remarkably into cold water, thought unirradiated fibroin fiber had little solubility even in hot water. A typical soluble fraction was about 60% for fibroin powder obtained from fiber irradiated by 1000 kGy in oxygen. (author)

  5. 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...

  6. Nanofibrous nonmulberry silk/PVA scaffold for osteoinduction and osseointegration.

    Science.gov (United States)

    Bhattacharjee, Promita; Kundu, Banani; Naskar, Deboki; Maiti, Tapas K; Bhattacharya, Debasis; Kundu, Subhas C

    2015-05-01

    Poly-vinyl alcohol and nonmulberry tasar silk fibroin of Antheraea mylitta are blended to fabricate nanofibrous scaffolds for bone regeneration. Nanofibrous matrices are prepared by electrospinning the equal volume ratio blends of silk fibroin (2 and 4 wt%) with poly-vinyl alcohol solution (10 wt%) and designated as 2SF/PVA and 4SF/PVA, respectively with average nanofiber diameters of 177?±?13 nm (2SF/PVA) and 193?±?17 nm (4SF/PVA). Fourier transform infrared spectroscopy confirms retention of the secondary structure of fibroin in blends indicating the structural stability of neo-matrix. Both thermal stability and contact angle of the blends decrease with increasing fibroin percentage. Conversely, fibroin imparts mechanical stability to the blends; greater tensile strength is observed with increasing fibroin concentration. Blended scaffolds are biodegradable and support well the neo-bone matrix synthesis by human osteoblast like cells. The findings indicate the potentiality of nanofibrous scaffolds of nonmulberry fibroin as bone scaffolding material. © 2014 Wiley Periodicals, Inc. Biopolymers 103: 271-284, 2015. PMID:25418966

  7. Bio-inspired fabrication of fibroin cryogels from the muga silkworm Antheraea assamensis for liver tissue engineering

    International Nuclear Information System (INIS)

    Conventional scaffold fabrication techniques result in narrow pore architectures causing a limited interconnectivity and use of porogens, which affects the bio- or cyto-compatibility. To ameliorate this, cryogels are immensely explored due to their macro-porous nature, ease in fabrication, using ice crystals as porogens, the shape property, easy reproducibility and cost-effective fabrication technique. Cryogels in the present study are prepared from nonmulberry Indian muga silk gland protein fibroin of Antheraea assamensis using two different fabrication temperatures (−20 and −80 °C). Anionic surfactant sodium dodecyl sulfate is used to solubilize fibroin, which in turn facilitates gelation by accelerating the ß-sheet formation. Ethanol is employed to stabilize the 3D network and induces bimodal porosity. The gels thus formed demonstrate increased ß-sheet content (FTIR) and a considerable effect of pre-freezing temperatures on 3D micro-architectures. The cryogels are capable of absorbing large amounts of water and withstanding mechanical compression without structure deformation. Further, cell impregnated cryogels well support the viability of human hepatocarcinoma cells (live/dead assay). The formation of cellular aggregates (confocal laser and scanning electron microscope), derivation in metabolic activity and proliferation rate are obtained in constructs fabricated at different temperatures. In summary, the present work reveals promising insights in the development of a biomimetic functional template for biomedical therapeutics and liver tissue engineering. (paper)

  8. Bio-inspired fabrication of fibroin cryogels from the muga silkworm Antheraea assamensis for liver tissue engineering.

    Science.gov (United States)

    Kundu, Banani; Kundu, S C

    2013-10-01

    Conventional scaffold fabrication techniques result in narrow pore architectures causing a limited interconnectivity and use of porogens, which affects the bio- or cyto-compatibility. To ameliorate this, cryogels are immensely explored due to their macro-porous nature, ease in fabrication, using ice crystals as porogens, the shape property, easy reproducibility and cost-effective fabrication technique. Cryogels in the present study are prepared from nonmulberry Indian muga silk gland protein fibroin of Antheraea assamensis using two different fabrication temperatures (-20 and -80 °C). Anionic surfactant sodium dodecyl sulfate is used to solubilize fibroin, which in turn facilitates gelation by accelerating the ß-sheet formation. Ethanol is employed to stabilize the 3D network and induces bimodal porosity. The gels thus formed demonstrate increased ß-sheet content (FTIR) and a considerable effect of pre-freezing temperatures on 3D micro-architectures. The cryogels are capable of absorbing large amounts of water and withstanding mechanical compression without structure deformation. Further, cell impregnated cryogels well support the viability of human hepatocarcinoma cells (live/dead assay). The formation of cellular aggregates (confocal laser and scanning electron microscope), derivation in metabolic activity and proliferation rate are obtained in constructs fabricated at different temperatures. In summary, the present work reveals promising insights in the development of a biomimetic functional template for biomedical therapeutics and liver tissue engineering. PMID:24002731

  9. 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

  10. Solubilization of silk protein by radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sudatis, Boonya; Pongpat, Suchada [Office of Atomic Energy of Peace, Bangkok (Thailand)

    2002-03-01

    Gamma irradiated silk fibroin at doses of 0, 5, 10, 20, 40, 60, 80, 100, 125, 250, 500, 750 and 1000 kGy were soaked in water for 1 hr. Silk fibroin solubilized percentage was investigated from lost weight of sample (dried at 105{sup 0}C), they were 0, 0, 0.7, 0, 0.11, 0.11, 0, 0.73, 0.77, 4.38, 8.32, 10.22 and 18.52 respectively. It showed that at the higher dose up to 250 kGy had direct effect to solubility, and increased with increasing dose. In addition, silk sericin dissolved 77.76, 82.22, 83.55, 84.31, 86.04, 86.67 and 87.37% after gamma irradiation at the doses of 0, 50, 100, 200, 500, 750 and 1000 kGy respectively. It presents that radiation can cause silk protein, fibroin and sericin dissolve because of their degradation. (author)

  11. 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.

  12. Fluid Mechanical Properties of Silkworm Fibroin Solutions

    Science.gov (United States)

    Matsumoto, Akira

    2005-11-01

    The aqueous solution behavior of silk fibroin is of interest due to the assembly and processing of this protein related to the spinning of protein fibers that exhibit remarkable mechanical properties. To gain insight into the origins of this functional feature, it is desired to determine how the protein behaves under a range of solution conditions. Pure fibroin at different concentrations in water was studied for surface tension, as a measure of surfactancy. In addition, shear induced changes on these solutions in terms of structure and morphology was also determined. Fibroin solutions exhibited shear rate-sensitive viscosity changes and precipitated at a critical shear rate where a dramatic increase of 75-150% of the initial value was observed along with a decrease in viscosity. In surface tension measurements, critical micelle concentrations were in the range of 3-4% w/v. The influence of additional factors, such as sericin protein, divalent and monovalent cations, and pH on the solution behavior in relation to structural and morphological features will also be described.

  13. 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...

  14. 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.

  15. 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.

  16. 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

  17. 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; David L. Kaplan; 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...

  18. 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 ...

  19. 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...

  20. Silk film biomaterials for ocular surface repair

    Science.gov (United States)

    Lawrence, Brian David

    Current biomaterial approaches for repairing the cornea's ocular surface upon injury are partially effective due to inherent material limitations. As a result there is a need to expand the biomaterial options available for use in the eye, which in turn will help to expand new clinical innovations and technology development. The studies illustrated here are a collection of work to further characterize silk film biomaterials for use on the ocular surface. Silk films were produced from regenerated fibroin protein solution derived from the Bombyx mori silkworm cocoon. Methods of silk film processing and production were developed to produce consistent biomaterials for in vitro and in vivo evaluation. A wide range of experiments was undertaken that spanned from in vitro silk film material characterization to in vivo evaluation. It was found that a variety of silk film properties could be controlled through a water-annealing process. Silk films were then generated that could be use in vitro to produce stratified corneal epithelial cell sheets comparable to tissue grown on the clinical standard substrate of amniotic membrane. This understanding was translated to produce a silk film design that enhanced corneal healing in vivo on a rabbit injury model. Further work produced silk films with varying surface topographies that were used as a simplified analog to the corneal basement membrane surface in vitro. These studies demonstrated that silk film surface topography is capable of directing corneal epithelial cell attachment, growth, and migration response. Most notably epithelial tissue development was controllably directed by the presence of the silk surface topography through increasing cell sheet migration efficiency at the individual cellular level. Taken together, the presented findings represent a comprehensive characterization of silk film biomaterials for use in ocular surface reconstruction, and indicate their utility as a potential material choice in the development of innovative procedures and technologies for corneal repair.

  1. Expression of the hIGF-I gene driven by the Fhx/P25 promoter in the silk glands of germline silkworm and transformed BmN cells.

    Science.gov (United States)

    Li, Yanmei; Cao, Guangli; Wang, Yang; Xue, Renyu; Zhou, Wenlin; Gong, Chengliang

    2011-03-01

    The expression of the human insulin-like growth factor (hIGF-I) gene driven by the Fhx/P25 promoter in the silk glands of transgenic silkworms (Bombyx mori) and in transformed silkworm cells, was achieved using BmN cells transfected with a piggyBac vector, pigA3GFP-Fhx/P25-hIGF-ie-neo containing a neomycin-resistance gene (neo), a green fluorescent protein gene (gfp), an hIGF-I gene, and a helper plasmid containing the piggyBac transposase sequence under the control of the B. mori actin 3 (A3) promoter. We selected stably transformed BmN cells expressing hIGF-I using the antibiotic G418. The expression level of hIGF-I was about 450 pg in 3 × 10(6) cells, determined by ELISA. The piggyBac vector was transferred into the silkworm eggs using sperm-mediated gene transfer. The expression level of hIGF-I per gram fresh posterior silk glands of G4 transgenic silkworms was approx. 150 ng. PMID:21072564

  2. 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.

  3. Mechanical behavior comparison of spider and silkworm silks using molecular dynamics at atomic scale.

    Science.gov (United States)

    Lee, Myeongsang; Kwon, Junpyo; Na, Sungsoo

    2016-02-01

    Spider and silkworm silk proteins have received much attention owing to their inherent structural stability, biodegradability, and biocompatibility. These silk protein materials have various mechanical characteristics such as elastic modulus, ultimate strength and fracture toughness. While the considerable mechanical characteristics of the core crystalline regions of spider silk proteins at the atomistic scale have been investigated through several experimental techniques and computational studies, there is a lack of comparison between spider and silkworm fibroins in the atomistic scale. In this study, we investigated the differences between the mechanical characteristics of spider and silkworm fibroin structures by applying molecular dynamics and steered molecular dynamics. We found that serine amino acids in silkworm fibroins not only increased the number of hydrogen bonds, but also altered their structural characteristics and mechanical properties. PMID:26806791

  4. 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

  5. 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.

  6. 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

    2015-12-01

    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.

  7. 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.

  8. Controlled Release from Multilayer Silk Biomaterial Coatings to Modulate Vascular Cell Responses

    OpenAIRE

    Wang, Xianyan; Zhang, Xiaohui; Castellot, John; Herman, Ira; Iafrati, Mark; Kaplan, David L.

    2007-01-01

    A multilayered silk fibroin protein coating system was employed as a drug carrier and delivery system to evaluate vascular cell responses to heparin, paclitaxel, and clopidogrel. The results demonstrated that the silk coating system was an effective system for drug-eluting coatings, such as for stent applications, based on its useful micromechanical properties and biological outcomes. Cell attachment and viability studies with human aortic endothelial cells (HAECs) and human coronary artery s...

  9. 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...

  10. 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

  11. 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...

  12. 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...

  13. 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...

  14. 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

  15. 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.

  16. Silk microgels formed by proteolytic enzyme activity.

    Science.gov (United States)

    Samal, Sangram K; Dash, Mamoni; Chiellini, Federica; Kaplan, David L; Chiellini, Emo

    2013-09-01

    The proteolytic enzyme α-chymotrypsin selectively cleaves the amorphous regions of silk fibroin protein (SFP) and allows the crystalline regions to self-assemble into silk microgels (SMGs) at physiological temperature. These microgels consist of lamellar crystals in the micrometer scale, in contrast to the nanometer-scaled crystals in native silkworm fibers. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zeta potential results demonstrated that α-chymotrypsin utilized only the non-amorphous domains or segments of the heavy chain of SFP to form negatively charged SMGs. The SMGs were characterized in terms of size, charge, structure, morphology, crystallinity, swelling kinetics, water content and thermal properties. The results suggest that the present technique of preparing SMGs by α-chymotrypsin is simple and efficient, and that the prepared SMGs have useful features for studies related to biomaterial and pharmaceutical needs. This process is also an easy way to obtain the amorphous peptide chains for further study. PMID:23756227

  17. 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

    Directory of Open Access Journals (Sweden)

    JOSÉ EDUARDO SERRÃO

    2005-03-01

    Full Text Available 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 cytoplasm is filled with rough endoplasmic reticulum, polyribosomes and Golgi apparatuses profiles. The basal plasma membrane has many short infoldings and is lined by a thin basement membrane. The apical membrane is invaginated to form the boundary of the lumen, containing scattered short microvilli. The cells are mononucleated and the nucleus is pleomorphic containing disperse chromatin. The extracellular lumen is separated of the receiving canal by a convoluted sponge-like wall forming many villi, which in their tip are lined by a thin single layered cuticle. In the basal region of the villi a cuticular covering is lacking. In the conducting canal secretion acquire two different electron densities. A thin cuticle lines the lumen of conducting canal and the cell cytoplasm is scarce and the organelles are represented for few rough endoplasmic reticulum and polyribosomes. These results are discussed in relation to function and origin of silk gland in adult SphecidaeSe describe la ultraestructura de las glándulas de la seda en tres hembras adultas de avispas Sphecidae del género Microstigmus. Las glándulas individualmente se dispersan en la porción más posterior del metasoma, y cada una de ellas está formada por una unidad secretora grande y un canal que conduce la secreción. Cada célula de la unidad secretora contiene un gran lumen y numerosos gránulos secretores, los que están delimitados por una membrana y repletos de un contenido denso a los electrones de aspecto homogéneo, el que es eliminado hacia el lumen. El citoplasma de la célula está repleto de perfiles del retículo endoplasmático granular, de polirribosomas y de aparatos de Golgi. La membrana plasmática basal presenta muchos repliegues cortos hacia el interior y está revestida por una membrana basal fina. La membrana plasmática apical está invaginada para formar el límite del lumen extracelular, lleva microvellosidades cortas y dispersas. Las células son mononucleadas y el núcleo es de forma variada y contiene cromatina dispersa. El lumen está separado del canal de recepción por una pared replegada semejante a una esponja, con muchas vellosidades, las que en su extremidad están delimitadas por una cutícula fina. En la región basal, las vellosidades carecen de cubierta cuticular. El canal que conduce la secreción adquiere dos densidades de electrones diferentes. Una cutícula fina reviste el lumen del canal que conduce la secreción, siendo escaso el citoplasma de la célula y conteniendo poco retículo endoplasmático granular y polirribosomas. Estos resultados se discuten en relación a la función y al origen de la glándula de seda en los adultos de Sphecidae

  18. Processing and characterization of silk sericin from Bombyx mori and its application in biomaterials and biomedicines.

    Science.gov (United States)

    Cao, Ting-Ting; Zhang, Yu-Qing

    2016-04-01

    Bombyx mori silk is composed of 60-80% fibroin, 15-35% sericin and 1-5% non-sericin component including wax, pigments, sugars and other impurities. For two decades, the protein-based silk fibroin was extensively used in the research and development of medical biomaterials and biomedicines. Sericin is frequently ignored and abandoned as a byproduct or waste in the processing of traditional silk fabrics, silk floss or modern silk biomaterials. However, similar to fibroin, sericin is not only a highly useful biological material, but also a lot of biological activity. Moreover, the non-sericin component present with sericin in the cocoon shell also has a strong biological activity. In this review, the extraction and recovery methods of sericin and the non-sericin component from the cocoon layer are reported, and their composition, properties and biological activity are described to produce a comprehensive report on biomedical materials and biological drugs. In addition, related problems or concerns present in the research and development of sericin are discussed, and a potential application of sericin in sustainable development is also presented. PMID:26838924

  19. Novel and simple route to fabricate fully biocompatible plasmonic mushroom arrays adhered on silk biopolymer

    Science.gov (United States)

    Park, Joonhan; Choi, Yunkyoung; Lee, Myungjae; Jeon, Heonsu; Kim, Sunghwan

    2014-12-01

    A fully biocompatible plasmonic quasi-3D nanostructure is demonstrated by a simple and reliable fabrication method using strong adhesion between gold and silk fibroin. The quasi-3D nature gives rise to complex photonic responses in reflectance that are prospectively useful in bio/chemical sensing applications. Laser interference lithography is utilized to fabricate large-area plasmonic nanostructures.A fully biocompatible plasmonic quasi-3D nanostructure is demonstrated by a simple and reliable fabrication method using strong adhesion between gold and silk fibroin. The quasi-3D nature gives rise to complex photonic responses in reflectance that are prospectively useful in bio/chemical sensing applications. Laser interference lithography is utilized to fabricate large-area plasmonic nanostructures. Electronic supplementary information (ESI) available: The incident angle dependence of reflectance spectra and the atomic force microscopy image of the Au nanoparticle array on a silk film after 1 hour of ultrasonication. See DOI: 10.1039/c4nr05172f

  20. 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.

  1. 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

  2. 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)

  3. Role of pH and charge on silk protein assembly in insects and spiders

    Science.gov (United States)

    Foo, C. Wong Po; Bini, E.; Hensman, J.; Knight, D. P.; Lewis, R. V.; Kaplan, D. L.

    2006-02-01

    Silk fibers possess impressive mechanical properties, dependant, in part, on the crystalline ?-sheets silk II conformation. The transition to silk II from soluble silk I-like conformation in silk glands, is thought to originate in the spinning ducts immediately before the silk is drawn down into a fiber. However the assembly process of these silk molecules into fibers, whether in silkworms or spiders, is not well understood. Extensional flow, protein concentration, pH and metal ion concentrations are thought to be most important in in vivo silk processing and in affecting structural conformations. We look at how parameters such as pH, [Ca2+], [K+], and [Cu2+], and water content, interact with the domain structure of silk proteins towards the successful storage and processing of these concentrated hydrophobic silk proteins. Our recent domain mapping studies of all known silk proteins, and 2D Raman spectroscopy, NMR, and DLS studies performed on sections of silkworm gland, suggest that low pH and gradual water removal promote intermolecular over intramolecular hydrogen bonding. This discussion helps to provide the necessary ground rules towards the design of silk protein analogues with specific hydrophobicity and charge profiles to optimize expression, solubility and assembly with implications in structural biology and material science.

  4. 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 β-sheets structure, similar to fibroin filaments but with a lower crystallinity index.

  5. 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.

  6. Decoration of silk fibroin by click chemistry for biomedical application.

    Science.gov (United States)

    Zhao, Hongshi; Heusler, Eva; Jones, Gabriel; Li, Linhao; Werner, Vera; Germershaus, Oliver; Ritzer, Jennifer; Luehmann, Tessa; Meinel, Lorenz

    2014-06-01

    Silkfibroin (SF) has an excellent biocompatibility and its remarkable structure translates into exciting mechanical properties rendering this biomaterial particularly fascinating for biomedical application. To further boost the material's biological/preclinical impact, SF is decorated with biologics, typically by carbodiimide/N-hydroxysuccinimide coupling (EDC/NHS). For biomedical application, this chemistry challenges the product risk profile due to the formation of covalent aggregates, particularly when decoration is with biologics occurring naturally in humans as these aggregates may prime for autoimmunity. Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC; click chemistry) provides the necessary specificity to avoid such intermolecular, covalent aggregates. We present a blueprint outlining the necessary chemistry rendering SF compatible with CuAAC and with a particular focus on structural consequences. For that, the number of SF carboxyl groups (carboxyl-SF; required for EDC/NHS chemistry) or azido groups (azido-SF; required for click chemistry) was tailored by means of diazonium coupling of the SF tyrosine residues. Structural impact on SF and decorated SF was characterized by Fourier transform infrared spectroscopy (FTIR). The click chemistry yielded a better controlled product as compared to the EDC/NHS chemistry with no formation of inter- and intramolecular crosslinks as demonstrated for SF decorated with fluorescent model compounds or a biologic, fibroblast growth factor 2 (FGF2), respectively. In conclusion, SF can readily be translated into a scaffold compatible with click chemistry yielding decorated products with a better risk profile for biomedical application. PMID:24576682

  7. 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.

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

    International Nuclear Information System (INIS)

    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 deg. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Steven, Eden; Brooks, James S [Department of Physics and National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac, Tallahassee, FL 32310 (United States); Park, Jin Gyu [FAMU-FSU Department of Industrial and Manufacturing Engineering, High-Performance Materials Institute, Florida State University, 2005 Levy Ave., Tallahassee, FL 32310 (United States); Paravastu, Anant; Siegrist, Theo; Kaner, Papatya; Alamo, Rufina G [FAMU-FSU Department of Chemical and Biomedical Engineering and National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac, Tallahassee, FL 32310 (United States); Branco Lopes, Elsa [Departamento de Quimica, Instituto Tecnologico e Nuclear/CFMC-UL, P-2686-953 Sacavem (Portugal); Englander, Ongi, E-mail: esteven@magnet.fsu.edu [FAMU-FSU Department of Mechanical Engineering and National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac, Tallahassee, Florida 32310 (United States)

    2011-10-15

    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 {beta}-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 deg. 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 {beta}-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 {beta}-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.

  10. 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

  11. Effect of degumming time on silkworm silk fibre for biodegradable polymer composites

    Science.gov (United States)

    Ho, Mei-po; Wang, Hao; Lau, Kin-tak

    2012-02-01

    Recently, many studies have been conducted on exploitation of natural materials for modern product development and bioengineering applications. Apart from plant-based materials (such as sisal, hemp, jute, bamboo and palm fibre), animal-based fibre is a kind of sustainable natural materials for making novel composites. Silkworm silk fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. However, when producing silk fibre reinforced biodegradable/bioresorbable polymer composites, hydrophilic sericin has been found to cause poor interfacial bonding with most polymers and thus, it results in affecting the resultant properties of the composites. Besides, sericin layers on fibroin surface may also cause an adverse effect towards biocompatibility and hypersensitivity to silk for implant applications. Therefore, a proper pre-treatment should be done for sericin removal. Degumming is a surface modification process which allows a wide control of the silk fibre's properties, making the silk fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, a cleaner and environmentally friendly surface modification technique for tussah silk in polymer based composites is proposed. The effectiveness of different degumming parameters including degumming time and temperature on tussah silk is discussed through the analyses of their mechanical and morphological properties. Based on results obtained, it was found that the mechanical properties of tussah silk are affected by the degumming time due to the change of the fibre structure and fibroin alignment.

  12. Sex differences in cooperative silk-spinning by weaver ant larvae

    OpenAIRE

    Wilson, Edward O.; Hölldobler, Bert

    1980-01-01

    Final-instar larvae of weaver ants (Oecophylla longinoda) use their silk for nest construction rather than for cocoon spinning; this commitment represents a shift from entirely selfish to entirely cooperative behavior that occurred after the emergence of the phylogenetically advanced subfamily Formicinae. Male larvae were found to have smaller silk glands and to contribute substantially less silk to nest construction. The hypothesis of kin selection appears to be the most plausible and parsim...

  13. 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...

  14. Characterization and mechanical performance study of silk/PVA cryogels: towards nucleus pulposus tissue engineering

    International Nuclear Information System (INIS)

    Poly (vinyl) alcohol (PVA) cryogels are reported in the literature for application in nucleus pulposus (NP) replacement strategies. However, these studies are mainly limited to acellular approaches—in part due to the high hydrophilicity of PVA gels that renders cellular adhesion difficult. Silk is a versatile biomaterial with excellent biocompatibility. We hypothesize that the incorporation of silk with PVA will (i) improve the cell-hosting abilities of PVA cryogels and (ii) allow better tailoring of physical properties of the composite cryogels for an NP tissue engineering purpose. 5% (wt/vol) PVA is blended with 5% silk fibroin (wt/vol) to investigate the effect of silk?:?PVA ratios on the cryogels’ physical properties. Results show that the addition of silk results in composite cryogels that are able to swell to more than 10 times its original dry weight and rehydrate to at least 70% of its original wet weight. Adding at least 20% silk significantly improves surface hydrophobicity and is correlated with an improvement in cell-hosting abilities. Cell-seeded cryogels also display an increment in compressive modulus and hoop stress values. In all, adding silk to PVA creates cryogels that can be potentially used as NP replacements. (paper)

  15. 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

  16. Water-insoluble Silk Films with Silk I Structure

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Q.; Hu, X; Wang, X; Kluge, J; Lu, S; Cebe, P; Kaplan, D

    2010-01-01

    Water-insoluble regenerated silk materials are normally produced by increasing the {beta}-sheet content (silk II). In the present study water-insoluble silk films were prepared by controlling the very slow drying of Bombyx mori silk solutions, resulting in the formation of stable films with a predominant silk I instead of silk II structure. Wide angle X-ray scattering indicated that the silk films stabilized by slow drying were mainly composed of silk I rather than silk II, while water- and methanol-annealed silk films had a higher silk II content. The silk films prepared by slow drying had a globule-like structure at the core surrounded by nano-filaments. The core region was composed of silk I and silk II, surrounded by hydrophilic nano-filaments containing random turns and {alpha}-helix secondary structures. The insoluble silk films prepared by slow drying had unique thermal, mechanical and degradative properties. Differential scanning calorimetry results revealed that silk I crystals had stable thermal properties up to 250 C, without crystallization above the T{sub g}, but degraded at lower temperatures than silk II structure. Compared with water- and methanol-annealed films the films prepared by slow drying had better mechanical ductility and were more rapidly enzymatically degraded, reflecting the differences in secondary structure achieved via differences in post processing of the cast silk films. Importantly, the silk I structure, a key intermediate secondary structure for the formation of mechanically robust natural silk fibers, was successfully generated by the present approach of very slow drying, mimicking the natural process. The results also point to a new mode of generating new types of silk biomaterials with enhanced mechanical properties and increased degradation rates, while maintaining water insolubility, along with a low {beta}-sheet content.

  17. Study on spinning process of silkworm by using synchrotron radiation X-ray diffraction

    International Nuclear Information System (INIS)

    The spinning process of a fifth instar Bombyx mori silkworm was studied in situ by synchrotron radiation wide angle X-ray diffraction (SR-WAXD). Silk glands dissected out from the larvae, and degummed cocoon silk were also examined by SR-WAXD. The effects of drying and drawing on the development of ordered structure of silk fibroin in the silk gland were investigated. The results show that ordered structures related to silk I and silk II are formed in the spinning dope near the spinneret of the silkworm head. During drying process of the silk gland, dehydration results in the formation of ordered structure of silk fibroin. Its conformation transforms to anti-parallel ?-sheet which tends to construct perfect lamellar crystalline structure of silk II during drying. In addition, drawing is another important factor to induce the formation of ordered structure of silk fibroin and resultant fiber. (authors)

  18. Natural Silk as a Photonics Component: a Study on Its Light Guiding and Nonlinear Optical Properties

    Science.gov (United States)

    Kujala, Sami; Mannila, Anna; Karvonen, Lasse; Kieu, Khanh; Sun, Zhipei

    2016-01-01

    Silk fibers are expected to become a pathway to biocompatible and bioresorbable waveguides, which could be used to deliver localized optical power for various applications, e.g., optical therapy or imaging inside living tissue. Here, for the first time, the linear and nonlinear optical properties of natural silk fibers have been studied. The waveguiding properties of silk fibroin of largely unprocessed Bombyx mori silkworm silk are assessed using two complementary methods, and found to be on the average 2.8 dB mm−1. The waveguide losses of degummed silk are to a large extent due to scattering from debris on fiber surface and helical twisting of the fiber. Nonlinear optical microscopy reveals both configurational defects such as torsional twisting, and strong symmetry breaking at the center of the fiber, which provides potential for various nonlinear applications. Our results show that nonregenerated B. mori silk can be used for delivering optical power over short distances, when the waveguide needs to be biocompatible and bioresorbable, such as embedding the waveguide inside living tissue. PMID:26926272

  19. 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,...

  20. 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.

  1. 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.

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

    OpenAIRE

    Eliane Victoriano; GREGÓRIO, ELISA A.

    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...

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

    Science.gov (United States)

    Kaźmierska, Katarzyna; Florczak, Anna; Piekoś, Konrad; Mackiewicz, Andrzej; Dams-Kozłowska, 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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)

  15. Nutritional value of silk powder from irradiated silk waste

    Energy Technology Data Exchange (ETDEWEB)

    Bunjob, Malee; Lakshanasomya, Niphaporn [Department of Medical Sciences, Nonthaburi (Thailand); Meesilpa, Prateep [Department of Agriculture, Bangkok (Thailand); Sudatis, Boonya [Office of Atomic Energy for Peace, Bangkok (Thailand)

    2002-03-01

    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)

  16. 21 CFR 184.1262 - Corn silk and corn silk extract.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Corn silk and corn silk extract. 184.1262 Section... SAFE Listing of Specific Substances Affirmed as GRAS § 184.1262 Corn silk and corn silk extract. (a) Corn silk is the fresh styles and stigmas of Zea mays L. collected when the corn is in milk....

  17. 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

  18. Tuning assembly and enzymatic degradation of silk/poly(N-vinylcaprolactam) multilayers via molecular weight and hydrophobicity.

    Science.gov (United States)

    Espinosa-Dzib, Alejandra; Chen, Jun; Zavgorodnya, Oleksandra; Kozlovskaya, Veronika; Liang, Xing; Kharlampieva, Eugenia

    2015-07-01

    We report on enzymatically degradable nanothin coatings obtained by layer-by-layer (LbL) assembly of silk fibroin with poly(N-vinylcaprolactam) (PVCL) via hydrogen bonding and hydrophobic interactions. We found that both silk ?-sheet content, controlled through dipping and spin-assisted LbL, and PVCL molecular weight regulate film thickness, microstructure, pH-stability, and biodegradability with a nanoscale precision. Thickness of (silk/PVCL) films increased with increase in PVCL molecular weight and decrease in deposition pH. The impact of assembly pH on film growth was more dramatic for dipped films. These systems show a significant rise in thickness with increase in PVCL molecular weight at pH independent on polymer chain length at pH ? 5. We also found that spin-assisted films exhibited a greater stability at elevated pH and against enzymatic degradation as compared to their dipped counterparts. For both film types, the pH and enzymatic stability was improved with increasing PVCL length and ?-sheet content, indicating enhanced hydrophobic and hydrogen-bonded interactions between PVCL and silk. Finally, we fabricated spherical and cubical (silk/PVCL) LbL capsules of regulated permeability and enzymatic degradation. Our approach gives a unique opportunity to tune thickness, morphology, structure, and biodegradability rate of silk films and capsules by varying silk secondary structure and PVCL length. Accounting for all-aqueous fabrication and the biocompatibility of both polymers these biodegradable materials provide novel platforms for delivery systems and medical devices. PMID:26041120

  19. 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...

  20. Secondary Structure Transition and Critical Stress for a Model of Spider Silk Assembly.

    Science.gov (United States)

    Giesa, Tristan; Perry, Carole C; Buehler, Markus J

    2016-02-01

    Spiders spin their silk from an aqueous solution to a solid fiber in ambient conditions. However, to date, the assembly mechanism in the spider silk gland has not been satisfactorily explained. In this paper, we use molecular dynamics simulations to model Nephila clavipes MaSp1 dragline silk formation under shear flow and determine the secondary structure transitions leading to the experimentally observed fiber structures. While no experiments are performed on the silk fiber itself, insights from this polypeptide model can be transferred to the fiber scale. The novelty of this study lies in the calculation of the shear stress (300-700 MPa) required for fiber formation and identification of the amino acid residues involved in the transition. This is the first time that the shear stress has been quantified in connection with a secondary structure transition. By study of molecules containing varying numbers of contiguous MaSp1 repeats, we determine that the smallest molecule size giving rise to a "silk-like" structure contains six polyalanine repeats. Through a probability analysis of the secondary structure, we identify specific amino acids that transition from ?-helix to ?-sheet. In addition to portions of the polyalanine section, these amino acids include glycine, leucine, and glutamine. The stability of ?-sheet structures appears to arise from a close proximity in space of helices in the initial spidroin state. Our results are in agreement with the forces exerted by spiders in the silking process and the experimentally determined global secondary structure of spidroin and pulled MaSp1 silk. Our study emphasizes the role of shear in the assembly process of silk and can guide the design of microfluidic devices that attempt to mimic the natural spinning process and predict molecular requirements for the next generation of silk-based functional materials. PMID:26669270

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. Determination of the torsion angles of alanine and glycine residues of model compounds of spider silk (AGG){sub 10} using solid-state NMR methods

    Energy Technology Data Exchange (ETDEWEB)

    Ashida, Jun; Ohgo, Kosuke; Komatsu, Kohei; Kubota, Ayumi; Asakura, Tetsuo [Tokyo University of Agriculture and Technology, Department of Biotechnology (Japan)], E-mail: asakura@cc.tuat.ac.jp

    2003-02-15

    Spiders synthesize several kinds of silk fibers. In the primary structure of spider silk, one of the major ampullate (dragline, frame) silks, spidroin 1, and flagelliform silk (core fibers of adhesive spiral), there are common repeated X-Gly-Gly (X = Ala, Leu, Pro, Tyr, Glu, and Arg) sequences, which are considered to be related to the elastic character of these fibers. In this paper, two dimensional spin diffusion solid-state NMR under off magic angle spinning (OMAS), {sup 13}C chemical shift contour plots, and Rotational Echo DOuble Resonance (REDOR) were applied to determine the torsion angles of one Ala and two kinds of Gly residues in the Ala-Gly-Gly sequence of {sup 13}C=O isotope-labeled (Ala-Gly-Gly){sub 10}. The torsion angles were determined to be ({phi}, {psi}) = (-90 deg., 150 deg.) within an experimental error of {+-}10 deg. for each residue. This conformation is characterized as 3{sub 1} helix which is in agreement with the structure proposed from the X-ray powder diffraction pattern of poly(Ala-Gly-Gly). The 3{sub 1} helix of (Ala-Gly-Gly){sub 10} does not change by formic acid treatment although (Ala-Gly){sub 15} easily changes from the silk I conformation (the structure of Bombyx mori silk fibroin before spinning in the solid state) to silk II conformation (the structure of the silk fiber after spinning) by such treatment. Thus, the 3{sub 1} helix conformation of (Ala-Gly-Gly){sub 10} is considered very stable. Furthermore, the torsion angles of the 16th Leu residue of (Leu-Gly-Gly){sub 10} were also determined as ({phi}, {psi}) = (-90 deg., 150 deg.) and this peptide is also considered to take 3{sub 1} helix conformation.

  7. A new route for silk

    Science.gov (United States)

    Omenetto, Fiorenzo G.; Kaplan, David L.

    2008-11-01

    Famous for its use in clothing since early times, silk is now finding a new application as a useful biocompatible material in photonic devices. Thin films, diffraction gratings and organic photonic crystals are just a few of the exciting possibilities.

  8. 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

  9. Clinical Application of a Silk Fibroin Protein Biologic Scaffold for Abdominal Wall Fascial Reinforcement

    Directory of Open Access Journals (Sweden)

    Mark W. Clemens, MD

    2014-11-01

    Conclusions: Postoperative complication rates after 18 months were low, and most surgical complications were managed nonoperatively on an outpatient basis without mesh removal. To our knowledge, this is the only series to report on a long-lasting, transitory SBS for abdominal wall repair and reinforcement. Procedure-specific outcome studies are warranted to delineate optimal patient selection and define potential device characteristic advantages.

  10. Incorporation of elastase inhibitor in silk fibroin nanoparticles for transdermal delivery

    OpenAIRE

    Ferreira, Ana Vanessa Fernandes

    2013-01-01

    Elastase de Neutrófilos Humana, como resposta inflamatória, possui a capacidade de degradar os componentes da matriz extracelular, nomeadamente colagénio e elastina, estando envolvida na formação de rugas causadas pela radiação ultravioleta. De forma a desenvolver uma emulsão cosmética antirrugas, decidiu-se incorporar um potente inibidor sintético de elastase, sivelestat (IC50 = 44 nM, Ki = 0,2 ?M), em nanopartículas biopoliméricas formadas por métodos de emulsificação de elev...

  11. Optically probing torsional superelasticity in spider silks

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P. [Department of Physical Sciences, IISER Mohali, Sector 81, Manauli, Mohali 140306 (India)

    2013-11-11

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2?3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

  12. 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

  13. Silk coating as a novel delivery system and reversible adhesive for stiffening and shaping flexible probes

    Directory of Open Access Journals (Sweden)

    Cinzia Metallo

    2015-02-01

    Full Text Available The performance of any implantable electrode depends not only on its recording or stimulation capabilities but also on its position in relation to the target site. Electrode displacement during or after implantation represents a major issue as it might result in tissue damage or incorrect recording or stimulation location, complicating the interpretation of experimental data. Although thin-film electrode arrays have overcome some of the main limitations of more traditional, stiffer probes, their intrinsic flexibility and unilateral contacts represent a new challenge: they tend to bend during insertion and are difficult to implant simultaneously while maintaining a specific relative position. Here, we present a method that addresses all these issues using a coating of silk fibroin, a versatile protein derived from silkworm cocoons. The method is demonstrated by acquiring electromyographic (EMG recordings in Manduca sexta, a soft-bodied animal that exemplifies the issues of electrode insertion and placement in delicate and deformable tissues.

  14. 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

  15. 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.

  16. 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.

  17. Evidence from Multiple Species that Spider Silk Glue Component ASG2 is a Spidroin

    OpenAIRE

    Matthew A. Collin; Clarke, Thomas H; Ayoub, Nadia A.; Hayashi, Cheryl Y.

    2016-01-01

    Spiders in the superfamily Araneoidea produce viscous glue from aggregate silk glands. Aggregate glue coats prey-capture threads and hampers the escape of prey from webs, thereby increasing the foraging success of spiders. cDNAs for Aggregate Spider Glue 1 (ASG1) and 2 (ASG2) have been previously described from the golden orb-weaver, Nephila clavipes, and Western black widow, Latrodectus hesperus. To further investigate aggregate glues, we assembled ASG1 and ASG2 from genomic target capture l...

  18. PEGylated Silk Nanoparticles for Anticancer Drug Delivery

    DEFF Research Database (Denmark)

    Wongpinyochit, Thidarat; Uhlmann, Petra; Urquhart, Andrew; Seib, F. Philipp

    2015-01-01

    Silk has a robust clinical track record and is emerging as a promising biopolymer for drug delivery, including its use as nanomedicine. However, silk-based nanomedicines still require further refinements for full exploitation of their potential; the application of “stealth” design principals is...... especially necessary to support their evolution. The aim of this study was to develop and examine the potential of PEGylated silk nanoparticles as an anticancer drug delivery system. We first generated B. mori derived silk nanoparticles by driving β-sheet assembly (size 104 ± 1.7 nm, zeta potential −56 ± 5.......6 mV) using nanoprecipitation. We then surface grafted polyethylene glycol (PEG) to the fabricated silk nanoparticles and verified the aqueous stability and morphology of the resulting PEGylated silk nanoparticles. We assessed the drug loading and release behavior of these nanoparticles using...

  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. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. Endocrine Glands & Their Hormones

    Science.gov (United States)

    ... Modules Resources Archived Modules Updates Endocrine Glands & Their Hormones The endocrine system is made up of the endocrine glands that secrete hormones. Although there are eight major endocrine glands scattered ...

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

    Science.gov (United States)

    Chen, Guang-Liang; Zheng, Xu; Lü, Guo-Hua; Zhang, Zhao-Xia; Sylvain, Massey; Wilson, Smith; Michael, Tatoulian; Yang, Si-Ze

    2012-10-01

    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.

  8. 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

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

    Science.gov (United States)

    The development of a spider silk manufacturing process is of great interest. piggyBac vectors were used 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 prote...

  11. Unraveled mechanism in silk engineering: Fast reeling induced silk toughening

    Science.gov (United States)

    Wu, Xiang; Liu, Xiang-Yang; Du, Ning; Xu, Gangqin; Li, Baowen

    2009-08-01

    We theoretically and experimentally study the mechanical response of silkworm and spider silks against stretching and the relationship with the underlying structural factors. It is found that the typical stress-strain profiles are predicted in good agreement with experimental measurements by implementing the "?-sheet splitting" mechanism we discovered and verified, primarily varying the secondary structure of protein macromolecules. The functions of experimentally observed structural factors responding to the external stress have been clearly addressed, and optimization of the microscopic structures to enhance the mechanical strength will be pointed out, beneficial to their biomedical and textile applications.

  12. 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

  13. 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.

  14. 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.

  15. 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...

  16. 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

  17. 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

  18. 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)

  19. 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

  20. Multiscale modeling of spider dragline silk

    OpenAIRE

    Patil, Sandeep Parasharam

    2015-01-01

    Spider dragline silk features an unusual combination of high strength, extensibility and stiffness, which outperforms some of the best materials known in terms of its mechanical performance. It is as strong as high-carbon steel, has a higher extensibility than the best commercial nylon filaments, and is tougher than Kevlar. For these reasons, dragline silk serves as a benchmark of modern polymer fiber technology, and the mass-production of a biomimetic material is of high interest. Developing...

  1. 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...

  2. 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

  3. 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)

  4. 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 - ...

  5. Salivary gland tumors

    Science.gov (United States)

    Tumor - salivary duct ... at various places in the mouth. Salivary gland tumors are rare, especially in children. Swelling of the ... syndrome The most common type of salivary gland tumor is a slow-growing noncancerous (benign) tumor of ...

  6. 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 ...

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

    Directory of Open Access Journals (Sweden)

    Eliane de Oliveira Borges

    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 the 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.

  8. 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.

  9. Doxorubicin loaded nanodiamond-silk spheres for fluorescence tracking and controlled drug release

    Science.gov (United States)

    Khalid, Asma; Mitropoulos, Alexander N.; Marelli, Benedetto; Tomljenovic-Hanic, Snjezana; Omenetto, Fiorenzo G.

    2015-01-01

    Nanoparticle (NP) based technologies have proved to be considerably beneficial for advances in biomedicine especially in the areas of disease detection, drug delivery and bioimaging. Over the last few decades, NPs have garnered interest for their exemplary impacts on the detection, treatment, and prevention of cancer. The full potential of these technologies are yet to be employed for clinical use. The ongoing research and development in this field demands single multifunctional composite materials that can be employed simultaneously for drug delivery and biomedical imaging. In this manuscript, a unique combination of silk fibroin (SF) and nanodiamonds (NDs) in the form of nanospheres are fabricated and investigated. The spheres were loaded with the anthracyline Doxorubicin (DoX) and the drug release kinetics for these ND-SF-DoX (NDSX) spheres were studied. NDs provided the fluorescence modality for imaging while the degradable SF spheres stabilized and released the drug in a controlled manner. The emission and structural properties of the spheres were characterized during drug release. The degradability of SF and the subsequent release of DoX from the spheres were monitored through fluorescence of NDs inside the spheres. This research demonstrates the enormous potential of the ND-SF nanocomposite platforms for diagnostic and therapeutic purposes, which are both important for pharmaceutical research and clinical settings.

  10. Characterization of polymer, DNA-based, and silk thin film resistivities and of DNA-based films prepared for enhanced electrical conductivity

    Science.gov (United States)

    Yaney, Perry P.; Ouchen, Fahima; Grote, James G.

    2009-08-01

    DC resistivity studies were carried out on biopolymer films of DNA-CTMA and silk fibroin, and on selected traditional polymer films, including PMMA and APC. Films of DNA-CTMA versus molecular weight and with conductive dopants PCBM, BAYTRON P and ammonium tetrachloroplatinate are reported. The films were spin coated on glass slides configured for measurements of volume dc resistance. The measurements used the alternating polarity method to record the applied voltage-dependent current independent of charging and background currents. The Arrhenius equation plus a constant was fitted to the conductivity versus temperature data of the polymers and the non-doped DNA-based biopolymers with activation energies ranging from 0.8 to 1.4 eV.

  11. 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

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

    OpenAIRE

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

    2015-01-01

    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 morpholog...

  14. N-Acetyl cysteine (NAC)-mediated reinforcement of alpha-tricalcium phosphate/silk fibroin (?-TCP/SF) cement.

    Science.gov (United States)

    Feng, Tao; Pi, Bin; Li, Bin; Jiang, Lei; Wang, Yi-Meng; Zhu, Xue-Song; Yang, Hui-Lin

    2015-12-01

    Calcium phosphate cements (CPCs) are popular bone filling materials and drug carriers. However poor mechanical properties and lack of osteoinduction restrict their clinical applications. Recent studies suggested the osteogenic properties of NAC. In our study, we incorporated NAC with ?-TCP/SF. We found that the compressive strength of ?-TCP/SF-NAC composites increased with increase in NAC concentration, possibly due to complex three-dimensional networks of SF induced by NAC, which was large and chemically heterogeneous and induced compact oriented growth of HA crystals. However the setting time increased slightly with the addition of NAC, due to the ruptured disulfide bonds in SF. The ?-TCP/SF-NAC composites also showed decent biocompatibility in vitro. As a result, these composites hold great potential as bone filling materials for clinical applications, including minimally invasive surgeries. PMID:26547317

  15. 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

  16. 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.

  17. 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...

  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. 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.

  20. Thyroid gland removal - discharge

    Science.gov (United States)

    Total thyroidectomy - discharge; Partial thyroidectomy - discharge; Thyroidectomy - discharge; Subtotal thyroidectomy - discharge ... of your thyroid gland. This operation is called thyroidectomy . You probably spent 1 to 3 days in ...

  1. 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.)

  2. 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.

  3. 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…

  4. 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 ...

  5. 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.

  6. 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.

  7. Salt-leached silk scaffolds with tunable mechanical properties

    OpenAIRE

    Yao, Danyu; Dong, Sen; Lu, Qiang; Hu, Xiao; Kaplan, David L.; Zhang, Bingbo; Zhu, Hesun

    2012-01-01

    Substrate mechanical properties have remarkable influences on cell behavior and tissue regeneration. Although salt-leached silk scaffolds have been used in tissue engineering, applications in softer tissue regeneration can be encumbered with excessive stiffness. In the present study, silk-bound water interactions were regulated by controlling processing to allow the preparation of salt-leached porous scaffolds with tunable mechanical properties. Increasing silk-bound water interactions result...

  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. 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...

  10. 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.

  11. White-Light-Induced Collective Heating of Gold Nanocomposite/Bombyx mori Silk Thin Films with Ultrahigh Broadband Absorbance.

    Science.gov (United States)

    Tsao, Shao Hsuan; Wan, Dehui; Lai, Yu-Sheng; Chang, Ho-Ming; Yu, Chen-Chieh; Lin, Keng-Te; Chen, Hsuen-Li

    2015-12-22

    This paper describes a systematic investigation of the phenomenon of white-light-induced heating in silk fibroin films embedded with gold nanoparticles (Au NPs). The Au NPs functioned to develop an ultrahigh broadband absorber, allowing white light to be used as a source for photothermal generation. With an increase of the Au content in the composite films, the absorbance was enhanced significantly around the localized surface plasmon resonance (LSPR) wavelength, while non-LSPR wavelengths were also increased dramatically. The greater amount of absorbed light increased the rate of photoheating. The optimized composite film exhibited ultrahigh absorbances of approximately 95% over the spectral range from 350 to 750 nm, with moderate absorbances (>60%) at longer wavelengths (750-1000 nm). As a result, the composite film absorbed almost all of the incident light and, accordingly, converted this optical energy to local heat. Therefore, significant temperature increases (ca. 100 °C) were readily obtained when we irradiated the composite film under a light-emitting diode or halogen lamp. Moreover, such composite films displayed linear light-to-heat responses with respect to the light intensity, as well as great photothermal stability. A broadband absorptive film coated on a simple Al/Si Schottky diode displayed a linear, significant, stable photo-thermo-electronic effect in response to varying the light intensity. PMID:26552041

  12. Electricity from the Silk Cocoon Membrane

    OpenAIRE

    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

    2014-01-01

    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...

  13. Silk hydrogel for cartilage tissue engineering

    OpenAIRE

    Chao, Pen-hsiu Grace; Yodmuang, Supansa; Wang, Xiaoqin,; Lin SUN; Kaplan, David L; Vunjak-Novakovic, Gordana

    2010-01-01

    Cartilage tissue engineering based on cultivation of immature chondrocytes in agarose hydrogel can yield tissue constructs with biomechanical properties comparable to native cartilage. However, agarose is immunogenic and non-degradable, and our capability to modify the structure, composition, and mechanical properties of this material is rather limited. In contrast, silk hydrogel is biocompatible and biodegradable, and it can be produced using a water-based method without organic solvents tha...

  14. Mammary gland stem cells

    DEFF Research Database (Denmark)

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

    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, differentiation and carcinogenesis of xenotransplanted human breast epithelium in vivo. While in early...... differences between mouse and human gland development with particular emphasis on the identity and localization of stem cells, and the influence of the surrounding microenvironment. It is concluded that while recent advances in the field have contributed immense insight into how the normal mammary gland...

  15. Salivary Gland Cancer Treatment

    Science.gov (United States)

    ... lung cancer. The following stages are used for major salivary gland cancers: Enlarge Pea, peanut, walnut, and ... Cancer has spread to the skin, jawbone, ear canal, and/or facial nerve , and may have spread ...

  16. 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.)

  17. Pediatric salivary gland imaging

    Energy Technology Data Exchange (ETDEWEB)

    Boyd, Zachary T. [University of Missouri-Kansas City School of Medicine, Kansas City, MO (United States); Goud, Asha R. [University of California Irvine Medical Center, Department of Radiology, Orange, CA (United States); Lowe, Lisa H. [Children' s Mercy Hospitals and Clinics and the University of Missouri-Kansas City, Department of Radiology, Kansas City, MO (United States); Shao, Lei [Children' s Mercy Hospitals and Clinics and the University of Missouri-Kansas City, Department of Pathology, Kansas City, MO (United States)

    2009-07-15

    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.)

  18. 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.)

  19. 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...

  20. Radionuclide salivary gland imaging

    International Nuclear Information System (INIS)

    Salivary gland imaging with 99mTc as pertechnetate provides functional information concerning trapping and excretion of the parotid and submandibular glands. Anatomic information gained often adds little to clinical evaluation. On the other hand, functional information may detect subclinical involvement, which correlates well with biopsy of the minor labial salivary glands. Salivary gland abnormalities in systemic disease such as sarcoidosis, rheumatoid arthritis, lupus erythematosus, and other collagenvascular disorders may be detected before they result in the clinical manifestaions of Sjoegren's syndrome. Such glands, after initially demonstrating increased trapping in the acute phase, tend to have decreased trapping and failure to discharge pertechnetate in response to an appropriate physiologic stimulus. Increased uptake of gallium-67 citrate often accompanies these findings. Inflammatory parotitis can be suspected when increased perfusion is evident on radionuclide angiography with any agent. The ability of the salivary gland image to detect and categorize mass lesions, which result in focal areas of diminished activity such as tumors, cysts, and most other masses, is disappointing, while its ability to detect and categorize Warthin's tumor, which concentrates pertechnetate, is much more valuable, although not specific

  1. 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. …

  2. 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…

  3. Ptychographic X-ray Tomography of Silk Fiber Hydration

    DEFF Research Database (Denmark)

    Esmaeili, Morteza; Fløystad, Jostein B.; Diaz, Ana; Høydalsvik, Kristin; Guizar-Sicairos, Manuel; Andreasen, Jens Wenzel; Breiby, Dag W.

    2013-01-01

    Studying noninvasively the internal nanoporous structure of a single Tussah silk fiber under different humidity conditions, we demonstrate for the first time the feasibility of in-situ ptychographic tomography. The resulting 3D images of the silk fiber interior, obtained at both dry and humid con...

  4. 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

  5. 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

  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. 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)

  8. 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).

  9. 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

  10. Increased molecular mobility in humid silk fibers under tensile stress

    Science.gov (United States)

    Seydel, Tilo; Knoll, Wiebke; Greving, Imke; Dicko, Cedric; Koza, Michael M.; Krasnov, Igor; Müller, Martin

    2011-01-01

    Silk fibers are semicrystalline nanocomposite protein fibers with an extraordinary mechanical toughness that changes with humidity. Diffusive or overdamped motion on a molecular level is absent in dry silkworm silk, but present in humid silk at ambient temperature. This microscopic diffusion distinctly depends on the externally applied macroscopic tensile force. Quasielastic and inelastic neutron-scattering data as a function of humidity and of tensile strain on humid silk fibers support the model that both the adsorbed water and parts of the amorphous polymers participate in diffusive motion and are affected by the tensile force. It is notable that the quasielastic linewidth of humid silk at 100% relative humidity increases significantly with the applied force. The effect of the tensile force is discussed in terms of an increasing alignment of the polymer chains in the amorphous fraction with increasing tensile stress which changes the geometrical restrictions of the diffusive motions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kane, D M; Joyce, A M; Staib, G R [Department of Physics, Macquarie University, Sydney, NSW 2109 (Australia); Herberstein, M E, E-mail: deb.kane@mq.edu.a [Department of Biological Sciences, Macquarie University, Sydney, NSW 2109 (Australia)

    2010-09-15

    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).

  12. The development project of electron irradiated silk material used for restoration of historical silk-mounted painting

    Energy Technology Data Exchange (ETDEWEB)

    Sano, Chie [Independent Administrative Inst. National Research Inst. for cultural properties, Tokyo (Japan); Masuda, Katsuhiko

    2001-04-01

    Many pictures have been painted on the silk materials in Japan. To repair the historical painting, the repairing materials were developed by new silk fibers with electron beam irradiation. Total exposure was about 2 MGy (170 to 230 Mrad). In order to be clear the degradation mechanism of the irradiated silk materials, the samples were irradiated by 254 nm and 365nm UV light and electron beam. The tensile strength of samples decreased with increasing exposure energy. The electron irradiated silk materials showed random clacking and small molecular weight. However, aromatic amino acid of the long wavelength UV light irradiated silk and peptide linkage of the short wavelength UV light irradiated silk were cracked. The historical silk-mounted painting in the Edo era showed decrease of aromatic amino acid peak and that in the Kamakura era not observable peak. Accordingly, the degradation process of historical silk-mounted painting seemed to be the same as the process depend on the long wavelength UV light. (S.Y.)

  13. The development project of electron irradiated silk material used for restoration of historical silk-mounted painting

    International Nuclear Information System (INIS)

    Many pictures have been painted on the silk materials in Japan. To repair the historical painting, the repairing materials were developed by new silk fibers with electron beam irradiation. Total exposure was about 2 MGy (170 to 230 Mrad). In order to be clear the degradation mechanism of the irradiated silk materials, the samples were irradiated by 254 nm and 365nm UV light and electron beam. The tensile strength of samples decreased with increasing exposure energy. The electron irradiated silk materials showed random clacking and small molecular weight. However, aromatic amino acid of the long wavelength UV light irradiated silk and peptide linkage of the short wavelength UV light irradiated silk were cracked. The historical silk-mounted painting in the Edo era showed decrease of aromatic amino acid peak and that in the Kamakura era not observable peak. Accordingly, the degradation process of historical silk-mounted painting seemed to be the same as the process depend on the long wavelength UV light. (S.Y.)

  14. 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...

  15. 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...

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

    OpenAIRE

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

    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...

  17. In-vitro Characterization of Silk Sericin as an Anti-aging Agent

    OpenAIRE

    Thitinan Kitisin; Pannamas Maneekan; Natthanej Luplertlop

    2013-01-01

    Silk sericin is a natural macromolecular protein derived from the silkworm, Bombyx mori. It is also a by-product of silk-making. From previous reports, many cosmeceuticals and other cosmetic products have been developed with silk sericin. This study aimed to investigate an anti-aging property of silk sericin by in-vitro characterization using fibroblast cell culture model. The results showed that silk sericin can stimulate collagen type I synthesis, suppress the regulation of nitrite, which ...

  18. 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.

  19. 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.

  20. Malignant salivary gland tumours

    International Nuclear Information System (INIS)

    The most frequent malignant salivary gland tumours are the mucoepidermoid tumour, adenoid cystic carcinoma and adenocarcinoma. The major salivary glands and the minor glands of the mouth and upper respiratory tract may potentially develop any of these malignant lesions. Malignant lesions most frequently present as a palpable mass and tend to enlarge more rapidly than benign neoplasms. Pain, paresthesia, muscle paralysis and fixation to surrounding tissue are all ominous signs and symptoms. The only reliable means of differential diagnosis of these lesions is biopsy and histologic analysis. Therapy involves surgery or a combination of surgery and radiation therapy. The ultimate prognosis is governed by the intrinsic biologic behaviour of the neoplasms, the extent of disease and adequate clinical therapy

  1. Malignant salivary gland tumours

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, S.H. (University of the Witwatersrand, Johannesburg (South Africa). Dept. of Oral Pathology)

    1982-08-01

    The most frequent malignant salivary gland tumours are the mucoepidermoid tumour, adenoid cystic carcinoma and adenocarcinoma. The major salivary glands and the minor glands of the mouth and upper respiratory tract may potentially develop any of these malignant lesions. Malignant lesions most frequently present as a palpable mass and tend to enlarge more rapidly than benign neoplasms. Pain, paresthesia, muscle paralysis and fixation to surrounding tissue are all ominous signs and symptoms. The only reliable means of differential diagnosis of these lesions is biopsy and histologic analysis. Therapy involves surgery or a combination of surgery and radiation therapy. The ultimate prognosis is governed by the intrinsic biologic behaviour of the neoplasms, the extent of disease and adequate clinical therapy.

  2. Submandibular gland excision

    Directory of Open Access Journals (Sweden)

    Alexandre Sanfurgo de Carvalho

    2015-02-01

    Full Text Available OBJECTIVE: to analyze the value of fine needle aspiration and the rates of postoperative complications in patients undergoing resection of the submandibular gland. METHODS: we analyzed the records of patients treated with resection of the gland from January 1995 to December 2008. The data collected included age, gender, findings on clinical history, surgical procedure, results of fine needle aspiration (FNA, pathological diagnosis and complications. RESULTS: 117 patients were studied, aged 12-89 years (mean 48, 70 women and 47 men. Thirty-nine patients (33.3% were affected by inflammatory diseases (28 patients with lithiasis, 70 had benign tumors, and malignant tumors, eight. Regarding FNA, the sensitivity and specificity were 85.7% and 100%, respectively. Nine patients (7.7% had temporary paralysis of the marginal mandibular nerve and one had permanent paralysis. CONCLUSION: resection of the submandibular gland is a safe procedure, with low complication rates.

  3. 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

  4. Undifferentiated salivary gland carcinomas

    DEFF Research Database (Denmark)

    Herbst, H.; Hamilton-Dutoit, S.; Jakel, K.T.; Niedobitek, G.

    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......, 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...... 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...

  5. 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.

  6. 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.

  7. Inhibitory Effect of Corn Silk on Skin Pigmentation

    Directory of Open Access Journals (Sweden)

    Sang Yoon Choi

    2014-03-01

    Full Text Available In this study, the inhibitory effect of corn silk on melanin production was evaluated. This study was performed to investigate the inhibitory effect of corn silk on melanin production in Melan-A cells by measuring melanin production and protein expression. The corn silk extract applied on Melan-A cells at a concentration of 100 ppm decreased melanin production by 37.2% without cytotoxicity. This was a better result than arbutin, a positive whitening agent, which exhibited a 26.8% melanin production inhibitory effect at the same concentration. The corn silk extract did not suppress tyrosinase activity but greatly reduced the expression of tyrosinase in Melan-A cells. In addition, corn silk extract was applied to the human face with hyperpigmentation, and skin color was measured to examine the degree of skin pigment reduction. The application of corn silk extract on faces with hyperpigmentation significantly reduced skin pigmentation without abnormal reactions. Based on the results above, corn silk has good prospects for use as a material for suppressing skin pigmentation.

  8. 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.

  9. 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.

  10. Canine mammary gland tumors.

    Science.gov (United States)

    Sorenmo, Karin

    2003-05-01

    The National Consensus Group recommends that all women with tumors larger than 1 cm be offered chemotherapy regardless of tumor histology of lymph node status. This recommendation is to ensure that everyone at risk for failing, even though the risk may be low in women with relatively small tumors and favorable histology, has a choice and receives the benefit of adjuvant chemotherapy. This type of treatment recommendation may also be made in dogs based on recognized, well-accepted prognostic factors such as tumor size, stage, type, and histologic differentiation. Based on the limited clinical information available in veterinary medicine, the drugs that are effective in human breast cancer, such as cyclophosphamide, 5-fluorouracil, and doxorubicin, may also have a role in the treatment of malignant mammary gland tumors in dogs. Randomized prospective studies are needed, however, to evaluate the efficacy of chemotherapy in dogs with high-risk mammary gland tumors and to determine which drugs and protocols are the most efficacious. Until such studies are performed, the treatment of canine mammary gland tumors will be based on the individual oncologist's understanding of tumor biology, experience, interpretation of the available studies, and a little bit of gut-feeling. Table 2 is a proposal for treatment guidelines for malignant canine mammary gland tumors according to established prognostic factors, results from published veterinary studies, and current recommendations for breast cancer treatment in women. PMID:12852237

  11. 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.

  12. 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...

  13. 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

  14. SilkDB: a knowledgebase for silkworm biology and genomics

    OpenAIRE

    Wang, Jing; Xia, Qingyou; He, Ximiao; Dai, Mingtao; Ruan, Jue; Chen, Jie; Yu, Guo; Yuan, Haifeng; Hu, Yafeng; LI, RUIQIANG; Feng, Tao; Ye, Chen; Lu, Cheng; WANG, JUN; Li, Songgang

    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 ?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 g...

  15. Sebaceous gland lipids

    OpenAIRE

    Picardo, Mauro; Ottaviani, Monica; Camera, Emanuela; Mastrofrancesco, Arianna

    2009-01-01

    The principal activity of mature sebaceous glands is producing and secreting sebum, which is a complex mixture of lipids. Sebum composition is different among species and this difference is probably due to the function that sebum has to absolve. In human sebum there are unique lipids, such as squalene and wax esters not found anywhere else in the body nor among the epidermal surface lipids. Moreover, they correspond to major components supplying the skin with protection. However, the ultimate...

  16. Coiling and maturation of a high-performance fibre in hagfish slime gland thread cells.

    Science.gov (United States)

    Winegard, Timothy; Herr, Julia; Mena, Carlos; Lee, Betty; Dinov, Ivo; Bird, Deborah; Bernards, Mark; Hobel, Sam; Van Valkenburgh, Blaire; Toga, Arthur; Fudge, Douglas

    2014-01-01

    The defensive slime of hagfishes contains thousands of intermediate filament protein threads that are manufactured within specialized gland thread cells. The material properties of these threads rival those of spider dragline silks, which makes them an ideal model for biomimetic efforts to produce sustainable protein materials, yet how the thread is produced and organized within the cell is not well understood. Here we show how changes in nuclear morphology, size and position can explain the three-dimensional pattern of thread coiling in gland thread cells, and how the ultrastructure of the thread changes as very young thread cells develop into large cells with fully mature coiled threads. Our model provides an explanation for the complex process of thread assembly and organization that has fascinated and perplexed biologists for over a century, and provides valuable insights for the quest to manufacture high-performance biomimetic protein materials. PMID:24698953

  17. Preparation, structure and properties of multi-functional silk via ATRP method

    International Nuclear Information System (INIS)

    In order to develop multi-functional silk materials, silk was grafted using the first flame retardant monomer, dimethyl methacryloyloxyethyl phosphate (DMMEP), and the second antibacterial monomer, dimethylaminoethyl methacrylate (DMAEMA), via atom transfer radical polymerization (ATRP) method. The result of attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR) indicated that two monomers were successfully grafted onto silk surface. X-ray diffraction (XRD) curves showed that grafting mainly occurred at the amorphous region of silk fibers. Thermal gravimetric analysis (TGA) and flame retardance measurements indicated that the Silk-grafted-poly(DMMEP) (Silk-g-PDMMEP) and Silk-grafted-poly(DMMEP)-blocked-poly(DMAEMA) (Silk-g-PDMMEP-b-PDMAEMA) both had good flame retardance. The LOI value could reach 31.2% and the char length was less than 6 cm for the Silk-g-PDMMEP sample with 22.21% of grafting percentage, and the LOI value was still over 28% after 50 times of washing. And the second grafts of DMAEMA monomer had no distinct effect on the flame retardance of Silk-g-PDMMEP. The inhibition rates of quaternized grafted silk to Staphylococcus aureu and Escherichia coli were both over 88%, and had excellent washing fastness. Multi-functional silk fabric with good flame retardance and anti-bacterial property could be obtained by properly controlling the grafting percentage, which had little effect on the intrinsic properties of silk fabric.

  18. 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

    2014-01-01

    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. PMID:24961354

  19. 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...

  20. 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.

  1. 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 ...

  2. 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.

  3. 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

  4. The Speed of Sound in Silk: Linking Material Performance to Biological Function

    OpenAIRE

    Mortimer, Beth; Gordon, Shira D; Holland, Chris; Siviour, Clive R.; Vollrath, Fritz; Windmill, James F C

    2014-01-01

    Sonic properties of spider silks are measured independent of the web using laser vibrometry and ballistic impact providing insights into Nature's design of functionalized high-performance materials. Through comparison to cocoon silk and other industrial fibers, we find that major ampullate silk has the largest wavespeed range of any known material.

  5. A response to Dolliver's "Evaluating drug trafficking on the Tor Network: Silk Road 2, the sequel"

    OpenAIRE

    Judith Aldridge, David Decary-Hetu

    2015-01-01

    The leading aim of Dolliver's (2015) paper “Evaluating drug trafficking on the Tor Network: Silk Road 2, the sequel” is to document changes in the size and structure of cryptomarkets following the demise of SILK ROAD 1 (SR1) using data she collected from SILK ROAD 2 (SR2), which she casts as successor to its namesake.

  6. 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...

  7. Imaging of salivary gland tumours

    International Nuclear Information System (INIS)

    Salivary gland neoplasms account for <3% of all tumors. Most of them are benign and parotid gland is the commonest site. As a general rule, the smaller the involved salivary gland, the higher is the possibility of the tumor being malignant. The role of imaging in assessment of salivary gland tumour is to define intra-glandular vs. extra-glandular location, detect malignant features, assess local extension and invasion, detect nodal metastases and systemic involvement. Image guided fine needle aspiration cytology provides a safe means to obtain cytological confirmation. For lesions in the superficial parotid and submandibular gland, ultrasound is an ideal tool for initial assessment. These are superficial structures accessible by high resolution ultrasound and FNAC which provides excellent resolution and tissue characterization without a radiation hazard. Nodal involvement can also be assessed. If deep tissue extension is suspected or malignancy confirmed on cytology, an MRI or CT is mandatory to evaluate tumour extent, local invasion and perineural spread. For all tumours in the sublingual gland, MRI should be performed as the risk of malignancy is high. For lesions of the deep lobe of parotid gland and the minor salivary glands, MRI and CT are the modalities of choice. Ultrasound has limited visualization of the deep lobe of parotid gland which is obscured by the mandible. Minor salivary gland lesions in the mucosa of oral cavity, pharynx and tracheo-bronchial tree, are also not accessible by conventional ultrasound. Recent study suggests that MR spectroscopy may differentiate malignant and benign salivary gland tumours as well as distinguishing Warthin's tumor from pleomorphic adenoma. However, its role in clinical practice is not well established. Similarly, the role of nuclear medicine and PET scan, in imaging of parotid masses is limited. Sialography is used to delineate the salivary ductal system and has limited role in assessment of tumour extent

  8. 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.

  9. 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

  10. 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.

  11. SilkDB: a knowledgebase for silkworm biology and genomics

    DEFF Research Database (Denmark)

    Wang, Jing; Xia, Qingyou; He, Ximiao; Dai, Mingtao; Ruan, Jue; Chen, Jie; Yu, Guo; Yuan, Haifeng; Hu, Yafeng; Li, Ruiqiang; Feng, Tao; Ye, Chen; Lu, Cheng; Wang, Jun; Li, Songgang; Wong, Gane Ka-Shu; Yang, Huanming; Wang, Jian; Xiang, Zhonghuai; Zhou, Zeyang; Yu, Jun

    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...... 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...

  12. 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

  13. Silk moths in Madagascar: Biology, uses and challenges related to Borocera cajani (Boisduval, 1833) (Lepidoptera – Lasiocampidae)

    OpenAIRE

    Razafimanantsoa, Tsiresy; Rajoelison, Gabrielle; Ramamonjisoa, Bruno; Raminosoa, Noromalala; Poncelet, Marc; Bogaert, Jan; Haubruge, Eric; Verheggen, François

    2012-01-01

    Borocera cajani (Lepidoptera, Lasiocampidae), also named Landibe, is main wild silk moth currently used to produce silk textiles in Madagascar. Silk production involve many member of the local population, from the wild silk harvesters, to the spinners, traders, dyers, weavers and the artisans who transform the silk into clothing, accessories and decorative items. Uapaca bojeri (Tapia) forests are the last remnants of highland primary forest, which are threatened by human destruction through b...

  14. Environmentally friendly surface modification of silk fiber: Chitosan grafting and dyeing

    International Nuclear Information System (INIS)

    In this paper, the surface modification of silk fiber using anhydrides to graft the polysaccharide chitosan and dyeing ability of the grafted silk were studied. Silk fiber was degummed and acylated with two anhydrides, succinic anhydride (SA) and phthalic anhydride (PA), in different solvents (dimethyl sulfoxide (DMSO) and N,N-dimethyl formamide (DMF)). The effects of anhydrides, solvents, anhydride concentration, liquor ratio (L:R) and reaction time on acylation of silk were studied. The polysaccharide chitosan was grafted to the acylated silk fiber and dyed by acid dye (Acid Black NB.B). The effects of pH, chitosan concentration, and reaction time on chitosan grafting of acylated silk were investigated. The physical properties show sensible changes regardless of weight gain. Scanning electron microscopy (SEM) analysis showed the presence of foreign materials firmly attached to the surface of silk. FTIR spectroscopy provided evidence that chitosan was grafted onto the acylated silk through the formation of new covalent bonds. The dyeing of the chitosan grafted-acylated silk fiber indicated the higher dye ability in comparison to the acylated and degummed silk samples. The mechanism of chitosan grafting over degummed silk through anhydride linkage was proposed. The findings of this research support the potential production of new environmentally friendly textile fibers. It is worthwhile to mention that the grafted samples have antibacterial potential due to the antibacterial property of chitosan molecules.

  15. Environmentally friendly surface modification of silk fiber: Chitosan grafting and dyeing

    Science.gov (United States)

    Davarpanah, Saideh; Mahmoodi, Niyaz Mohammad; Arami, Mokhtar; Bahrami, Hajir; Mazaheri, Firoozmehr

    2009-01-01

    In this paper, the surface modification of silk fiber using anhydrides to graft the polysaccharide chitosan and dyeing ability of the grafted silk were studied. Silk fiber was degummed and acylated with two anhydrides, succinic anhydride (SA) and phthalic anhydride (PA), in different solvents (dimethyl sulfoxide (DMSO) and N, N-dimethyl formamide (DMF)). The effects of anhydrides, solvents, anhydride concentration, liquor ratio (L:R) and reaction time on acylation of silk were studied. The polysaccharide chitosan was grafted to the acylated silk fiber and dyed by acid dye (Acid Black NB.B). The effects of pH, chitosan concentration, and reaction time on chitosan grafting of acylated silk were investigated. The physical properties show sensible changes regardless of weight gain. Scanning electron microscopy (SEM) analysis showed the presence of foreign materials firmly attached to the surface of silk. FTIR spectroscopy provided evidence that chitosan was grafted onto the acylated silk through the formation of new covalent bonds. The dyeing of the chitosan grafted-acylated silk fiber indicated the higher dye ability in comparison to the acylated and degummed silk samples. The mechanism of chitosan grafting over degummed silk through anhydride linkage was proposed. The findings of this research support the potential production of new environmentally friendly textile fibers. It is worthwhile to mention that the grafted samples have antibacterial potential due to the antibacterial property of chitosan molecules.

  16. Environmentally friendly surface modification of silk fiber: Chitosan grafting and dyeing

    Energy Technology Data Exchange (ETDEWEB)

    Davarpanah, Saideh [Textile Engineering Department, Amirkabir University of Technology, Hafez St., Tehran (Iran, Islamic Republic of); Mahmoodi, Niyaz Mohammad [Textile Engineering Department, Amirkabir University of Technology, Hafez St., Tehran (Iran, Islamic Republic of); Department of Environmental Research, Institute for Colorants, Paint and Coatings, Tehran (Iran, Islamic Republic of)], E-mail: mahmoodi@icrc.ac.ir; Arami, Mokhtar [Textile Engineering Department, Amirkabir University of Technology, Hafez St., Tehran (Iran, Islamic Republic of)], E-mail: arami@aut.ac.ir; Bahrami, Hajir; Mazaheri, Firoozmehr [Textile Engineering Department, Amirkabir University of Technology, Hafez St., Tehran (Iran, Islamic Republic of)

    2009-01-15

    In this paper, the surface modification of silk fiber using anhydrides to graft the polysaccharide chitosan and dyeing ability of the grafted silk were studied. Silk fiber was degummed and acylated with two anhydrides, succinic anhydride (SA) and phthalic anhydride (PA), in different solvents (dimethyl sulfoxide (DMSO) and N,N-dimethyl formamide (DMF)). The effects of anhydrides, solvents, anhydride concentration, liquor ratio (L:R) and reaction time on acylation of silk were studied. The polysaccharide chitosan was grafted to the acylated silk fiber and dyed by acid dye (Acid Black NB.B). The effects of pH, chitosan concentration, and reaction time on chitosan grafting of acylated silk were investigated. The physical properties show sensible changes regardless of weight gain. Scanning electron microscopy (SEM) analysis showed the presence of foreign materials firmly attached to the surface of silk. FTIR spectroscopy provided evidence that chitosan was grafted onto the acylated silk through the formation of new covalent bonds. The dyeing of the chitosan grafted-acylated silk fiber indicated the higher dye ability in comparison to the acylated and degummed silk samples. The mechanism of chitosan grafting over degummed silk through anhydride linkage was proposed. The findings of this research support the potential production of new environmentally friendly textile fibers. It is worthwhile to mention that the grafted samples have antibacterial potential due to the antibacterial property of chitosan molecules.

  17. Design and Optimization of Resorbable Silk Internal Fixation Devices

    Science.gov (United States)

    Haas, Dylan S.

    Limitations of current material options for internal fracture fixation devices have resulted in a large gap between user needs and hardware function. Metal systems offer robust mechanical strength and ease of implantation but require secondary surgery for removal and/or result in long-term complications (infection, palpability, sensitivity, etc.). Current resorbable devices eliminate the need for second surgery and long-term complications but are still associated with negative host response as well as limited functionality and more difficult implantation. There is a definitive need for orthopedic hardware that is mechanically capable of immediate fracture stabilization and fracture fixation during healing, can safely biodegrade while allowing complete bone remodeling, can be resterilized for reuse, and is easily implantable (self-tapping). Previous work investigated the use of silk protein to produce resorbable orthopedic hardware for non- load bearing fracture fixation. In this study, silk orthopedic hardware was further investigated and optimized in order to better understand the ability of silk as a fracture fixation system and more closely meet the unfulfilled market needs. Solvent-based and aqueous-based silk processing formulations were cross-linked with methanol to induce beta sheet structure, dried, autoclaved and then machined to the desired device/geometry. Silk hardware was evaluated for dry, hydrated and fatigued (cyclic) mechanical properties, in vitro degradation, resterilization, functionalization with osteoinductive molecules and implantation technique for fracture fixation. Mechanical strength showed minor improvements from previous results, but remains comparable to current resorbable fixation systems with the advantages of self-tapping ability for ease of implantation, full degradation in 10 months, ability to be resterilized and reused, and ability to release molecules for osteoinudction. In vivo assessment confirmed biocompatibility, showed improved bone deposition and remodeling with functionalization and showed promising feasibility of fracture fixations with minor adjustments to geometry. The proposed silk orthopedic hardware exhibits high potential as a resorbable fixation system that can bridge the gap between the current materials for internal fixation devices.

  18. 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

  19. 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.)

  20. 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