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Sample records for silk gland fibroin

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

    OpenAIRE

    Liangjun Zhu; Wen He; Sijia Min; Mingying Yang; Yajun Shuai

    2012-01-01

    In order to use a simple and ecofriendly method to prepare porous silk scaffolds, aqueous silk fibroin solution (ASF) was extracted from silk gland of 7-day-old fifth instar larvae of Bombyx mori (B. mori). SDS-page analysis indicated that the obtained fibroin had a molecular weight higher than 200 kDa. The fabrication of porous scaffolds from ASF was achieved by using the freeze-drying method. The pore of porous scaffolds is homogenous and tends to b...

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

    Directory of Open Access Journals (Sweden)

    Liangjun Zhu

    2012-06-01

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

  3. Silk Fibroin Electrogelation Mechanisms

    OpenAIRE

    LU Qiang; Huang, Yongli; Li, Mingzhong; Zuo, Baoqi; Lu, Shenzhou; Wang, Jiannan; Zhu, Hesun; Kaplan, David L.

    2011-01-01

    A silk fibroin gel system (e-gel), formed with weak electric fields has potential utility in medical materials and devices. The mechanism of silk e-gel formation was studied to gain additional insight into the process and control of the material properties. Silk fibroin nanoparticles with sizes of several ten nanometers, composed of metastable conformations, were involved in e-gel formation. Under electric fields, the nanoparticles rapidly assembled into larger nano- or microspheres with size...

  4. A contribution of the core-promoter and its surrounding regions to the preferential transcription of the fibroin gene in posterior silk gland extracts.

    OpenAIRE

    Takiya, S; Hui, C C; Suzuki, Y.

    1990-01-01

    Complementation of a posterior silk gland (psg) extract to a HeLa cell extract specifically enhances the transcription of the Bombyx mori fibroin gene. To map the regions responsible for this enhancement, the fibroin promoter was dissected and the transcriptional function of each region was analyzed. Besides the upstream promoter element 5' to the TATA box, two downstream elements were found to be important for the preferential transcription of the fibroin gene in the complementation system a...

  5. Further evidence for importance of the subunit combination of silk fibroin in its efficient secretion from the posterior silk gland cells

    OpenAIRE

    1987-01-01

    A locus responsible for the Nd-s mutation of the silkworm, Bombyx mori, has been mapped very close to or within the fibroin light (L) chain gene on the 14th chromosome (Takei, F., K. Kimura, S. Mizuno, T. Yamamoto, and K. Shimura, 1984, Jpn. J. Genet., 59:307-313). A strain of B. mori carrying the homozygous Nd-sD mutation (Nd-sD/Nd-sD; Nd-sD is allelic to Nd-s) secretes less than 0.3% of fibroin into the lumen of the posterior silk gland compared with a strain carrying the homozygous wild-ty...

  6. Silk Fibroin Electrogelation Mechanisms

    Science.gov (United States)

    Lu, Qiang; Huang, Yongli; Li, Mingzhong; Zuo, Baoqi; Lu, Shenzhou; Wang, Jiannan; Zhu, Hesun; Kaplan, David L.

    2012-01-01

    A silk fibroin gel system (e-gel), formed with weak electric fields has potential utility in medical materials and devices. The mechanism of silk e-gel formation was studied to gain additional insight into the process and control of the material properties. Silk fibroin nanoparticles with sizes of several ten nanometers, composed of metastable conformations, were involved in e-gel formation. Under electric fields, the nanoparticles rapidly assembled into larger nano- or microspheres with size ranges from tens nanometers to several microns. Repulsive forces from the negative surface charge of the acidic groups on the protein were screened by the local decrease in solution pH in the vicinity of the positive electrode. By controlling the formation and content of silk fibroin nanoparticles e-gel could be formed even from low concentration silk fibroin solutions (1%). When e-gel was reversed to the solution state, the aggregated nano- and microspheres dispersed into solution, a significant observation related to future applications for this process, such as for drug delivery. PMID:21345387

  7. Flexibility regeneration of silk fibroin in vitro

    OpenAIRE

    Zhang, Cencen; Song, Dawei; LU Qiang; Hu, Xiao; Kaplan, David L.; Zhu, Hesun

    2012-01-01

    Although natural silk fibers have excellent strength and flexibility, the regenerated silk materials generally become brittle in the dry state. How to reconstruct the flexibility for silk fibroin has bewildered scientists for many years. In the present study, the flexible regenerated silk fibroin films were achieved by simulating the natural forming and spinning process. Silk fibroin films composed of silk I structure were firstly prepared by slow drying process. Then the silk fibroin films w...

  8. 13C NMR study of silk fibroin synthesis in vitro

    International Nuclear Information System (INIS)

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

  9. Genipin modified silk fibroin nanometric-nets

    OpenAIRE

    Silva, S.S; Maniglio, D.; Motta, A.; J.F. Mano; Reis, R.L; Migliaresi, C.

    2008-01-01

    Nanometric silk-fibroin nets were fabricated by electrospinning from regenerated Bombyx mori silk-fibroin (SF)/formic acid solutions with the addition of genipin (GE), 2, 15 and 24 h after the solution preparation. After spinning, the pure fibroin nanofibers were water soluble and needed a further stabilization process, whereas the reaction of fibroin with genipin resulted in water-insoluble fibroin nets due to conformational changes induced in the fibroin by the genipin. SFGE nanofibers pres...

  10. 13C NMR of Nephila clavipes major ampullate silk gland.

    OpenAIRE

    Hijirida, D H; Do, K G; Michal, C; Wong, S.; Zax, D; Jelinski, L W

    1996-01-01

    The major ampullate glands of the spider Nephila clavipes contain approximately 0.2 microliter each of a highly concentrated (approximately 50%) solution of silk fibroin. Therefore, the reservoir of silk in these glands presents an ideal opportunity to observe prefolded conformations of a protein in its native state. To this end, the structure and conformation of major ampullate gland silk fibroin within the glands of the spider N. clavipes were examined by 13C NMR spectroscopy. These results...

  11. Degradation Mechanism and Control of Silk Fibroin

    OpenAIRE

    LU Qiang; Zhang, Bing; Li, Mingzhong; Zuo, Baoqi; Kaplan, David L.; Huang, Yongli; Zhu, Hesun

    2011-01-01

    Controlling the degradation process of silk is an important and interesting subject in biomaterials field. In the present study, silk fibroin films with different secondary conformations and nanostructures were used to study the degradation behavior. Silk fibroin films with highest ?-sheet content achieved highest degradation rate, different from the previous studies. A new degradation mechanism revealed that degradation behavior of silk fibroin was related to not only crystal content, but al...

  12. Silk Fibroin Based Porous Materials

    OpenAIRE

    Shuqin Yan; Mingzhong Li; Qiang Zhang

    2009-01-01

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

  13. Silk Fibroin Based Porous Materials

    Directory of Open Access Journals (Sweden)

    Shuqin Yan

    2009-12-01

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

  14. Phosphorylated silk fibroin matrix for methotrexate release

    OpenAIRE

    Volkov, Vadim; S??rria, M. P.; Gomes, A. C.; Paulo, Artur Cavaco

    2015-01-01

    Silk-based matrix was produced for delivery of a model anticancer drug, methotrexate (MTX). The calculation of net charge of silk fibroin and MTX was performed to better understand the electrostatic interactions during matrix formation upon casting. Silk fibroin films were cast at pH 7.2 and pH 3.5. Protein kinase A was used to prepare phosphorylated silk fibroin. The phosphorylation content of matrix was controlled by mixing at specific ratios the phosphorylated and unphosphorylated solution...

  15. Silk fibroin scaffolds promote formation of the ex vivo niche for salivary gland epithelial cell growth, matrix formation, and retention of differentiated function.

    Science.gov (United States)

    Zhang, Bin-Xian; Zhang, Zhi-Liang; Lin, Alan L; Wang, Hanzhou; Pilia, Marcello; Ong, Joo L; Dean, David D; Chen, Xiao-Dong; Yeh, Chih-Ko

    2015-05-01

    Salivary gland hypofunction often results from a number of causes, including the use of various medications, radiation for head and neck tumors, autoimmune diseases, diabetes, and aging. Since treatments for this condition are lacking and adult salivary glands have little regenerative capacity, there is a need for cell-based therapies to restore salivary gland function. Development of these treatment strategies requires the establishment of a system that is capable of replicating the salivary gland cell "niche" to support the proliferation and differentiation of salivary gland progenitor cells. In this study, a culture system using three-dimensional silk fibroin scaffolds (SFS) and primary salivary gland epithelial cells (pSGECs) from rat submandibular (SM) gland and parotid gland (PG) was established and characterized. pSGECs grown on SFS, but not tissue culture plastic (TCP), formed aggregates of cells with morphological features resembling secretory acini. High levels of amylase were released into the media by both cell types after extended periods in culture on SFS. Remarkably, cultures of PG-derived cells on SFS, but not SM cells, responded to isoproterenol, a ?-adrenergic receptor agonist, with increased enzyme release. This behavior mimics that of the salivary glands in vivo. Decellularized extracellular matrix (ECM) formed by pSGECs in culture on SFS contained type IV collagen, a major component of the basement membrane. These results demonstrate that pSGECs grown on SFS, but not TCP, retain important functional and structural features of differentiated salivary glands and produce an ECM that mimics the native salivary gland cell niche. These results demonstrate that SFS has potential as a scaffold for creating the salivary gland cell niche in vitro and may provide an approach for inducing multipotent stem cells to provide therapeutically meaningful numbers of salivary gland progenitor cells for regenerating these tissues in patients. PMID:25625623

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

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    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.

  17. Materials Fabrication from Bombyx mori Silk Fibroin

    OpenAIRE

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

    2011-01-01

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

  18. 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.

  19. Isolation of giant silk fibroin polysomes and fibroin mRNP particles using a novel ribonuclease inhibitor, hydroxystilbamidine

    OpenAIRE

    1980-01-01

    Hydroxystilbamidine isethionate, a dye capable of binding to both DNA and RNA, has been found to be a powerful inhibitor of cellular ribonucleases. A procedure has been developed that, with the aid of this compound, permits the preparative isolation of giant silk fibroin polyribosomes from the posterior silk gland of Bombyx mori. The polyribosomes contain approximately 45-112 ribosomal particles, as judged by electron microscopy. Treatment of giant fibroin polyribosomes with EDTA releases a p...

  20. 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...

  1. Control of the gelation process of silk fibroin solution

    Directory of Open Access Journals (Sweden)

    Liu Yu

    2014-01-01

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

  2. The effect of sterilization on silk fibroin biomaterial properties.

    Science.gov (United States)

    Rnjak-Kovacina, Jelena; DesRochers, Teresa M; Burke, Kelly A; Kaplan, David L

    2015-06-01

    The effects of common sterilization techniques on the physical and biological properties of lyophilized silk fibroin sponges are described. Sterile silk fibroin sponges were cast using a pre-sterilized silk fibroin solution under aseptic conditions or post-sterilized via autoclaving, ? radiation, dry heat, exposure to ethylene oxide, or hydrogen peroxide gas plasma. Low average molecular weight and low concentration silk fibroin solutions could be sterilized via autoclaving or filtration without significant loses of protein. However, autoclaving reduced the molecular weight distribution of the silk fibroin protein solution, and silk fibroin sponges cast from autoclaved silk fibroin were significantly stiffer compared to sponges cast from unsterilized or filtered silk fibroin. When silk fibroin sponges were sterilized post-casting, autoclaving increased scaffold stiffness, while decreasing scaffold degradation rate in vitro. In contrast, ? irradiation accelerated scaffold degradation rate. Exposure to ethylene oxide significantly decreased cell proliferation rate on silk fibroin sponges, which was rescued by leaching ethylene oxide into PBS prior to cell seeding. PMID:25761231

  3. Structural analysis and application to biomaterials of the silk fibroins

    International Nuclear Information System (INIS)

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

  4. 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.

  5. 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

  6. ELECTROPHORETIC SEPARATION AND COMPARATIVE ANALYSIS OF SILK GLAND PROTEINS FROM BOMBYX AND PHILOSAMIA

    Directory of Open Access Journals (Sweden)

    Muzafar A Bhat, Punyavathi and Manjunatha H Boregowda*

    2014-07-01

    Full Text Available A comparative analysis of protein extracted from different regions of silk glands in the Bombyx mori L. and Philosamia ricini Hutt was performed employing single-dimensional-electrophoresis technique. Notably, a protein extracted directly from the lumen of the middle silk gland yielded two discrete protein bands with molecular mass of 325 and 26 kDa representing fibroin heavy (H and low (L chains than whole silk gland of B. mori. Contrastingly, such differentiation in protein separation could not be achieved due to undifferentiated regions of silk gland in P. ricini. Interestingly, copious amount of proteins with different molecular weight were noticed in the whole silk gland of B. mori and P. ricini, whose functional properties in the silk gland remain enigmatic. Thus, middle and whole silk glands of B. mori shall be an ideal source for the extraction of fibroin and sericin respectively as potent bio-materials for biotechnological and biomedical applications.

  7. Novel silk fibroin/elastin wound dressings

    OpenAIRE

    Vasconcelos, Andreia; Gomes, Andreia; Paulo, Artur Cavaco

    2012-01-01

    Silk fibroin (SF) and elastin (EL) scaffolds were successfully produced for the first time for the treatment of burn wounds. The self-assembly properties of SF, together with the excellent chemical and mechanical stability and biocompatibility, were combined with elastin protein to produce scaffolds with the ability to mimic the extracellular matrix (ECM). Porous scaffolds were obtained by lyophilization and were further crosslinked with genipin (GE). Genipin crosslinking induces the conforma...

  8. 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...

  9. 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...

  10. Phosphorylation of silk fibroins improves the cytocompatibility of silk fibroin derived materials : a platform for the production of tuneable material

    OpenAIRE

    Volkov, Vadim; Vasconcelos, Andreia; S??rria, M. P.; Gomes, Andreia; Paulo, Artur Cavaco

    2014-01-01

    Silk fibroin demonstrates great biocompatibility and is suitable for many biomedical applications, including tissue engineering and regenerative medicine. Current research focuses on manipulating the physico-chemical properties of fibroin, and examining the effect of this manipulation on firobin's biocompatibility. Regenerated silk fibroin was modified by in vitro enzymatic phosphorylation and cast into films. Films were produced by blending, at several ratios, the phosphorylated and un-phosp...

  11. Sonication-Induced Gelation of Silk Fibroin for Cell Encapsulation

    OpenAIRE

    WANG, XIAOQIN; Kluge, Jon; Leisk, Gary G.; Kaplan, David L.

    2007-01-01

    Purified native silk fibroin forms ?-sheet-rich, physically crosslinked, hydrogels from aqueous solution, in a process influenced by environmental parameters. Previously we reported gelation times of days to weeks for aqueous native silk protein solutions, with high ionic strength and temperature and low pH responsible for increasing gelation kinetics. Here we report a novel method to accelerate the process and control silk fibroin gelation through ultrasonication. Depending on the sonication...

  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. Macro/microporous silk fibroin scaffolds with potential for articular cartilage and meniscus tissue engineering applications

    OpenAIRE

    Yan, Leping; Oliveira, Joaquim M.; Oliveira, Ana Leite; Caridade, S. G.; Mano, J. F.; Reis, R. L.

    2012-01-01

    This study describes the developmental physicochemical properties of silk fibroin scaffolds derived from high concentration aqueous silk fibroin solutions. The silk fibroin scaffolds were prepared with different initial concentrations (8%, 10%, 12% and 16% (wt%)) and obtained by combining the salt-leaching and freeze-drying methodologies. The results indicated that the antiparallel ?-pleated sheet (silk-II) conformation was present in the silk fibroin scaffolds. All the scaffolds possessed m...

  14. Nanofeatured silk fibroin membranes for dermal wound healing applications.

    Science.gov (United States)

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

    2015-01-01

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

  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. The effects of different sterilization methods on silk fibroin

    OpenAIRE

    Xiaosong Gu; Yumin Yang; Fei Ding; Xiaoli Yan; Yahong Zhao

    2011-01-01

    The aim of this study was to investigate the changes in the molecular structure and physiological activities of silk fibroin induced by three different sterilization methods (steam, gamma radiation and ethylene oxide) with different dose or time period of sterilization by means of Fourier transform infrared (FT-IR) spec-troscopy, X-ray diffraction, mechanical properties and assessment of molecular weight. The results showed that the steam sterilization darkened the color of silk fibroin and o...

  17. Exploring the Mechanism of Microarteriogenesis in Porous Silk Fibroin Film

    OpenAIRE

    Xiaoyan Tan; Jianmei Xu; Guangqian Wang; Lun Bai

    2012-01-01

    Purpose. Based on the experiment of the microarteriogenesis that is associated with angiogenesis during tissue repair process in porous silk fibroin films (PSFFs), we investigate the characteristics of micro-arteriogenesis and explore its mechanism. Methods. After the porous silk fibroin materials are implanted into the back hypodermal tissue of SD rats, the arteriole development and the morphogenesis of smooth muscle cell are histologically monitored and the micro-arteriogenesis is quantitat...

  18. In vivo Degradation of Three-Dimensional Silk Fibroin Scaffolds

    OpenAIRE

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

    2008-01-01

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

  19. Effect of ?-irradiation on the crystalline structure of silk fibroin and silk sericin

    International Nuclear Information System (INIS)

    Changes in the crystalline structure of silk sericin and silk fibroin induced by gamma-irradiation in the atmosphere described. The crystalline structure of silk sericin which had been subjected to gamma-irradiation remained unchanged. However the decomposition temperature of the specimen decreased to about 230 deg C, when the total dose of ? rays exceeded 4.6 Mrad. The structure of the silk 1 type crystal of silk fibroin in the solid state, with a low degree of molecular orientation, changed into the silk 2 type crystal, when the total dose of ? rays exceeded 4.6 Mrad. No changes in the crystalline structure were observed in the solid state of the silk 2 type crystal regardless of gamma-irradiation. The decrease in the decomposition temperature of the specimen was attributed to the decrease in the molecular orientation. However, the molecular conformation of silk fibroin with a randomly coiled structure remained unchanged even after gamma-irradiation. (author)

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

    Science.gov (United States)

    Teramoto, Hidetoshi; Kojima, Katsura

    2014-07-14

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

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

    OpenAIRE

    Jin Huanyu; Yin Hua; An Yan

    2013-01-01

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

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

    OpenAIRE

    Renchuan You; Ying Zhang(School of Science, Xi’an Jiaotong University, Xi’an 710049, P.R. China); 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 ...

  3. Amorphous Silk Fibroin Membranes for Separation of CO2

    Science.gov (United States)

    Aberg, Christopher M.; Patel, Anand K.; Gil, Eun Seok; Spontak, Richard J.; Hagg, May-Britt

    2009-01-01

    Amorphous silk fibroin has shown promise as a polymeric material derivable from natural sources for making membranes for use in removing CO2 from mixed-gas streams. For most applications of silk fibroin, for purposes other than gas separation, this material is used in its highly crystalline, nearly natural form because this form has uncommonly high tensile strength. However, the crystalline phase of silk fibroin is impermeable, making it necessary to convert the material to amorphous form to obtain the high permeability needed for gas separation. Accordingly, one aspect of the present development is a process for generating amorphous silk fibroin by treating native silk fibroin in an aqueous methanol/salt solution. The resulting material remains self-standing and can be prepared as thin film suitable for permeation testing. The permeability of this material by pure CO2 has been found to be highly improved, and its mixed-gas permeability has been found to exceed the mixed-gas permeabilities of several ultrahigh-CO2-permeable synthetic polymers. Only one of the synthetic polymers poly(trimethylsilylpropyne) [PTMSP] may be more highly permeable by CO2. PTMSP becomes unstable with time, whereas amorphous silk should not, although at the time of this reporting this has not been conclusively proven.

  4. 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...

  5. Hemocompatibility and cytocompatibility of the hirudin-modified silk fibroin.

    Science.gov (United States)

    Sun, Dan; Hao, Yunxia; Yang, Gaoqiang; Wang, Jiannan

    2015-04-01

    Hirudin (Hir), a thrombin direct inhibitor, was used to modify a polyethylene glycol diglycidyl ether (PEG-DE) crosslinked regenerated silk fibroin (SF) material to improve hemocompatibility. Hemolysis characteristics, platelet adhesion, platelet activity, and plasma recalcification time were investigated using absorption spectrometry, scanning electron microscopy, MTT analysis, and the time counting method. Hirudin could be grafted evenly to the silk fibroin, and the modified material was resistant to hemolysis at ratios of less than 0.5%. Scanning electron microscopy and MTT results showed that platelet adhesion and aggregation activity decreased after modificaton with trace amounts of hirudin, compared with PEG-DE crosslinked and ethanol-treated silk fibroin film. Plasma recalcification of PEG-DE crosslinked silk fibroin film was slower than with ethanol-treated material, and this increased slightly after hirudin modification. Furthermore, L929, HAVSMC, and HUVEC cells adhered to the modified material, grew well, and possessed high proliferation activity on SF/Hir blend films. This study suggests that hirudin could improve the anticoagulation properties of regenerated silk fibroin materials. PMID:24953970

  6. Production of silk sericin/silk fibroin blend nanofibers

    Directory of Open Access Journals (Sweden)

    Zhang Xianhua

    2011-01-01

    Full Text Available 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 of the SS/SF (75/25, 50/50, and 25/75 blend nanofibers were much thicker than that of SS and SF nanofibers. The SS/SF (100/0, 75/25, and 50/50 blend nanofibers were easily dissolved in water, while the SS/SF (25/75 and 0/100 blend nanofibers could not be completely dissolved in water. The SS/SF blend nanofibers could not be completely dissolved in methanol. The SS/SF blend nanofibers were characterized by Fourier transform infrared (FTIR spectroscopy, differential scanning calorimetry, and differential thermal analysis. FTIR showed that the SS/SF blend nanofibers possessed a random coil conformation and ß-sheet structure.

  7. 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...

  8. 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...

  9. 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 a...

  10. 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)

  11. Surface Modification and Characterisation of Silk Fibroin Fabric Produced by the Layer-by-Layer Self-Assembly of Multilayer Alginate/Regenerated Silk Fibroin

    Science.gov (United States)

    Shen, Gaotian; Hu, Xingyou; Guan, Guoping; Wang, Lu

    2015-01-01

    Silk-based medical products have a long history of use as a material for surgical sutures because of their desirable mechanical properties. However, silk fibroin fabric has been reported to be haemolytic when in direct contact with blood. The layer-by-layer self-assembly technique provides a method for surface modification to improve the biocompatibility of silk fibroin fabrics. Regenerated silk fibroin and alginate, which have excellent biocompatibility and low immunogenicity, are outstanding candidates for polyelectrolyte deposition. In this study, silk fabric was degummed and positively charged to create a silk fibroin fabric that could undergo self-assembly. The multilayer self-assembly of the silk fibroin fabric was achieved by alternating the polyelectrolyte deposition of a negatively charged alginate solution (pH = 8) and a positively charged regenerated silk fibroin solution (pH = 2). Finally, the negatively charged regenerated silk fibroin solution (pH = 8) was used to assemble the outermost layer of the fabric so that the surface would be negatively charged. A stable structural transition was induced using 75% ethanol. The thickness and morphology were characterised using atomic force microscopy. The properties of the self-assembled silk fibroin fabric, such as the bursting strength, thermal stability and flushing stability, indicated that the fabric was stable. In addition, the cytocompatibility and haemocompatibility of the self-assembled silk fibroin fabrics were evaluated. The results indicated that the biocompatibility of the self-assembled multilayers was acceptable and that it improved markedly. In particular, after the self-assembly, the fabric was able to prevent platelet adhesion. Furthermore, other non-haemolytic biomaterials can be created through self-assembly of more than 1.5 bilayers, and we propose that self-assembled silk fibroin fabric may be an attractive candidate for anticoagulation applications and for promoting endothelial cell adhesion for vascular prostheses. PMID:25919690

  12. Development of a bilayered scaffold based on silk fibroin and silk fibroin/nano-calcium phosphate for osteochondral regeneration

    OpenAIRE

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

    2012-01-01

    Objectives: Osteochondral defect is a common condtion in clinic. Satisfactory outcomes are rarely achieved by traditional methods. Tissue engineering might be a promising strategy for this hinder. The aim of this study is to mimick the stratified structure of osteochondral tissue, by developing a bilayered scaffold for osteochondral regeneration. The developed bilayered scaffold is composed of a porous silk fibroin scaffold as the cartilage-like layer and a porous silk fibro...

  13. Correlation between fibroin amino acid sequence and physical silk properties.

    Science.gov (United States)

    Fedic, Robert; Zurovec, Michal; Sehnal, Frantisek

    2003-09-12

    The fiber properties of lepidopteran silk depend on the amino acid repeats that interact during H-fibroin polymerization. The aim of our research was to relate repeat composition to insect biology and fiber strength. Representative regions of the H-fibroin genes were sequenced and analyzed in three pyralid species: wax moth (Galleria mellonella), European flour moth (Ephestia kuehniella), and Indian meal moth (Plodia interpunctella). The amino acid repeats are species-specific, evidently a diversification of an ancestral region of 43 residues, and include three types of regularly dispersed motifs: modifications of GSSAASAA sequence, stretches of tripeptides GXZ where X and Z represent bulky residues, and sequences similar to PVIVIEE. No concatenations of GX dipeptide or alanine, which are typical for Bombyx silkworms and Antheraea silk moths, respectively, were found. Despite different repeat structure, the silks of G. mellonella and E. kuehniella exhibit similar tensile strength as the Bombyx and Antheraea silks. We suggest that in these latter two species, variations in the repeat length obstruct repeat alignment, but sufficiently long stretches of iterated residues get superposed to interact. In the pyralid H-fibroins, interactions of the widely separated and diverse motifs depend on the precision of repeat matching; silk is strong in G. mellonella and E. kuehniella, with 2-3 types of long homogeneous repeats, and nearly 10 times weaker in P. interpunctella, with seven types of shorter erratic repeats. The high proportion of large amino acids in the H-fibroin of pyralids has probably evolved in connection with the spinning habit of caterpillars that live in protective silk tubes and spin continuously, enlarging the tubes on one end and partly devouring the other one. The silk serves as a depot of energetically rich and essential amino acids that may be scarce in the diet. PMID:12816957

  14. A novel growth process of calcium carbonate crystals in silk fibroin hydrogel system

    OpenAIRE

    Ma, Yufei; Feng, Qingling; Bourrat, Xavier

    2013-01-01

    We report an interesting finding of calcium carbonate (CaCO3) crystal growth in the silk fibroin (SF) hydrogel with different concentrations by a simple ion diffusion method. The experimental results indicate that the CaCO3 crystals obtained from silk fibroin gels with low and high concentrations are all calcites with unusual morphologies. Time-dependent growth study was carried out to investigate the crystallization process. It is believed that silk fibroin hydrogel plays an important role i...

  15. 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

    2015-01-01

    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

  16. 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)

  17. Separation of thorium from aqueous solution using silk fibroin

    International Nuclear Information System (INIS)

    In this study the basic features of thorium adsorption from aqueous systems by silk fibroin were investigated. The author previous study showed that this bio-polymer has high efficiency for U(VI) adsorption. It is well-known that thorium, which is a tetravalent metal, is a more reactive element than uranium. Thorium(IV) adsorption proves to be very rapid and dependent on pH, temperature, retention time, concentration of ion, amount of fibroin, volume of solution and volume-to-mass ratio. (author)

  18. Gelation of Antheraea pernyi Silk Fibroin Accelerated by Shearing

    Directory of Open Access Journals (Sweden)

    Yu Liu

    2013-05-01

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

  19. Orientational structure formation of silk fibroin with anisotropic properties in solutions

    International Nuclear Information System (INIS)

    Key words:silk fibroin, dissolution, solution's model systems, gelation, orientational crystallization, optical polarization, longitudinal stream, ? - ? transition, structure formation, phase transformations, relaxation, anisotropy of swelling and desorption, thermo- and biodegradation. Subjects of the inquiry: silk fibroin is the main subject of investigation. Fibroin's solutions were obtained on the base of water and organic solvents, containing salts. Comparative investigations were carried out by using biosolution - secretion of silkworm, solutions of silk sericin, cotton cellulose, methylcellulose, polystyrene and (co) polycrylonitrile. Aim of the inquiry: the elucidation of the regularities of silk fibroin anisotropic structures formation in the direct generation of orientational ordering in solutions taking into account of influences of its the molecular structures, configuration information, ? - ? conformational transformations, and development jointly using polarization-optical and hydrodynamic methods to control of structure formation. And also definition of possibility fields for use biopolymers anisotropic structure formation principles. Method of inquiry: birefringence, dispersion optical rotation, circular dichroism, polarization- ultramicroscope, ultracentrifuge, viscosimetry, potentiometry, differential thermal analysis, chromatography, x-ray analysis, spectroscopy. The results achieved and their novelty: the physical regularity amorphous-crystalline fibroin dissolutions in salt-containing solvents based on chains melting, distribution and redistribution were recognized; fibroin statistical parameters, molecular-mass and conformational characteristics were established; It was shown that fibroin molecules turned into fully uncoiled and oriented state with the breakdown decay of ?-spiral chain sections by I type phase transition mechanism, but in oriented state with ?-spiral conservation by II type transition; the presence of longitudinal field on the boundary 'reservoir - withdrawing capillary' of gland, initiating the transition of ?-spiral in ?-structures as well as phase separation of fibroin and sericin in stream were discovered; the phase diagram of liquidus for secret in the framework of polymers orientation crystallization conception were suggested; the mechanism of fibroin orientational crystallization under the longitudinal flow of solutions and gels was conformed experimentally; the scientific principles of oriented-crystallized fibrillar biopolymer materials receipt were established on the base of fibroin model solutions with properties of anisotropy of moisture absorption, swelling, desorption, thermo- and biodegradation; the approach of jointly using polarization-optical and hydrodynamic methods to the investigation of fibrillar biopolymers structure formation and phase transformations in solution was developed. Practical value - the elucidated physical regularities of fibroin solution allow to formulate a new idea on fibrillar biopolymer solutions formation and to get on their late model systems for practical use; the established scientific principles of orientational structure-formation and phase transformation of fibroin will be the base for development of original methods of anisotropic biopolymer materials from solutions of the polarization-optical and developed hydrodynamic methods can be used for the investigation of structure and phase transformations of wide range of fibrillar biopolymer samples. Sphere of usage: physics of anisotropic polymer systems, macromolecular compounds solutions, gels, crystals, biopolymers materials science, optical polarization and hydrodynamics. (author)

  20. Preparation and Characterization of Eri (Philosamia ricini Silk Fibroin Powder

    Directory of Open Access Journals (Sweden)

    S. Yaowalak

    2009-01-01

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

  1. Characteristics of phoxim-exposed gene transcription in the silk gland of silkworms.

    Science.gov (United States)

    Ma, L; Xie, Y; Gu, Z Y; Wang, B B; Li, F C; Xu, K Z; Shen, W D; Li, B

    2013-11-01

    Silkworm (Bombyx mori), a model Lepidoptera insect, is an important economic insect. Its silk gland is the important organ for silk protein synthesis and secretion. Phoxim exposure causes deficient cocooning of silkworm and has become one of the major negative factors for the silk industry. To study the impact of phoxim exposure on silk gland, using gene chip technology, we examined differentially expressed genes in silk gland after silkworms were exposed to phoxim (4.0?g/mL) for 24h. Functional annotation, classification and KEGG signaling pathway analysis were performed. The results showed that out of 3206 genes detected in silk gland after phoxim exposure, 270 were differentially expressed significantly, including 249 up-regulated genes and 21 down-regulated genes. These differentially expressed genes related to apoptosis, detoxification and protein degradation were selected. Using qRT-PCR, the expression levels of 9 genes involved in apoptosis, detoxification and protein degradation were validated. In addition, the expression profiles of three related fibroin synthesis genes (Fib-H, Fib-L and P25) were analyzed. Our results showed that phoxim exposure induced apoptosis of silk gland cells and inhibition of fibroin synthesis. This may be the cause of deficient silkworm cocooning. PMID:24267702

  2. Antimicrobial Silk Fibroin Hydrogel Instantaneously Induced by Cationic Surfactant

    OpenAIRE

    Shan Sun; Fang Zhang; Shanshan Zhang; Tieling Xing; Shenzhou Lu

    2013-01-01

    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 di...

  3. Design, expression and solid-state NMR characterization of silk-like materials constructed from sequences of spider silk, Samia cynthia ricini and Bombyx mori silk fibroins.

    Science.gov (United States)

    Yang, Mingying; Asakura, Tetsuo

    2005-06-01

    Silk has a long history of use in medicine as sutures. To address the requirements of a mechanically robust and biocompatible material, basic research to clarify the role of repeated sequences in silk fibroin in its structures and properties seems important as well as the development of a processing technique suitable for the preparation of fibers with excellent mechanical properties. In this study, three silk-like protein analogs were constructed from two regions selected from among the crystalline region of Bombyx mori silk fibroin, (GAGSGA)(2), the crystalline region of Samia cynthia ricini silk fibroin, (Ala)(12), the crystalline region of spider dragline silk fibroin, (Ala)(6), and the Gly-rich region of spider silk fibroin, (GGA)(4). The silk-like protein analog constructed from the crystalline regions of the spider dragline silk and B. mori silk fibroins, (A(6)SCS)(8), that constructed from the crystalline regions of the S. c.ricini and B. mori silk fibroins, (A(12)SGS)(4), that constructed from and the crystalline region of S. c.ricini silk fibroin and the glycine-rich region of spider dragline silk fibroin, (A(12)SGS)(4),were expressed their molecular weights being about 36.0 kDa, 17.0 kDa and 17.5 kDa, respectively in E. coli by means of genetic engineering technologies. (A(12)SCS)(4) and (A(12)SGS)(4 )undergo a structural transition from alpha-helix to beta-sheet on a change in the solvent treatment from trifluoroacetic acid (TFA) to formic acid (FA). However, (A(6)SCS)(8) takes on the beta-sheet structure predominantly on TFA treatment and FA treatment. Structural analysis was performed on model peptides selected from spider dragline and S. c.ricini silks by means of (13)C CP/MAS NMR. PMID:16002994

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

    Directory of Open Access Journals (Sweden)

    Jin Huanyu

    2013-01-01

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

  5. Processing and characterisation of a novel electropolymerized silk fibroin hydrogel membrane

    OpenAIRE

    Hai-Yan Wang; Yu-Qing Zhang

    2014-01-01

    Silk fibroin can be made into various forms of biocompatible medical materials, including hydrogel due to its excellent properties. Here, we report a novel method for the preparation of electropolymerized silk fibroin hydrogel membrane (ESFHM), which is formed on a nanoporous film as a barrier using a homemade device at a higher DC voltage. Regenerated silk fibroin solution in Tris buffer (pH 6.55–7.55) was added into a reservoir with a negative charge, and the silk molecules migrated toward ...

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

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    Zhang Hao

    2012-06-01

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

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

    International Nuclear Information System (INIS)

    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

  8. Lyophilized Silk Fibroin Hydrogels for the Sustained Local Delivery of Therapeutic Monoclonal Antibodies

    OpenAIRE

    Guziewicz, Nicholas; Best, Annie; Perez-Ramirez, Bernardo; Kaplan, David L.

    2011-01-01

    The development of sustained delivery systems compatible with protein therapeutics continues to be a significant unmet need. A lyophilized silk fibroin hydrogel matrix (lyogel) for the sustained release of pharmaceutically relevant monoclonal antibodies is described. Sonication of silk fibroin prior to antibody incorporation avoids exposing the antibody to the sol-gel transition inducing shear stress. Fourier Transform Infrared (FTIR) analysis showed no change in silk structural composition b...

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

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    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.

  10. 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.

  11. Stimuli-responsive capsules prepared from regenerated silk fibroin microspheres.

    Science.gov (United States)

    Cheng, Cheng; Teasdale, Ian; Brüggemann, Oliver

    2014-06-01

    Microcapsules are synthesized via the self-assembly of silk-fibroin microspheres with polycaprolactone in a colliodosome preparation procedure. The microsphere building blocks with controlled diameter are prepared from the naturally occurring biopolymer, silk fibroin, and then act as stabilizers for oil-in-water (O/W) emulsion and organized themselves on the surface of chloroform droplets to form the capsules. The concentration of the protein-based microspheres and the binding polycacrolactone is used to tailor the size, as well as the permeability of the resultant capsules. Furthermore, microencapsulation of fluorescently labeled macromolecules (20-2000 KDa) is demonstrated. The permeability of the capsules is observed to be stimuli responsive, making it possible to incorporate a pH-triggered payload release from the capsules. The relatively simple preparation of capsules with controlled dimensions and tunable permeability, alongside the biocompatibility and biodegradability of both polymer components makes these promising materials for potential use in smart drug-delivery systems. PMID:24532252

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

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    Renchuan You

    2013-06-01

    Full Text Available 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(NO32 and CaCl2 to dissolve the silk fibers. SDS-PAGE analysis showed that the MW of the CaCl2-derived silk fibroin was lower than the MW produced using LiBr and Ca(NO32. In vitro and in vivo degradation results showed that the scaffolds prepared by low-MW silk fibroin were more rapidly degraded. Furthermore, FTIR and amino acid analysis suggested that the amorphous regions were preferentially degraded by Collagenase IA, while the SDS-PAGE and amino acid analysis indicated that the scaffolds were degraded into polypeptides (mainly at 10-30 kDa and amino acids. Because the CaCl2-derived scaffolds contained abundant low MW polypeptides, inter-intramolecular entanglement and traversing of molecular chains in the crystallites reduced, which resulted in rapid degradation. The in vivo degradation results suggested that the degradation rate of the CaCl2-derived scaffolds was better matched to dermis regeneration, indicating that the degradation rate of silk fibroin can be effectively regulated by changing the MW to achieve a suitable dermal tissue regeneration rate.

  13. 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

  14. Structures of Bombyx mori and Samia cynthia ricini silk fibroins studied with solid-state NMR.

    Science.gov (United States)

    Yao, Juming; Nakazawa, Yasumoto; Asakura, Tetsuo

    2004-01-01

    There are many kinds of silks spun by silkworms and spiders, which are suitable to study the structure-property relationship for molecular design of fibers with high strength and high elasticity. In this review, we mainly focus on the structural determination of two well-known silk fibroin proteins that are from the domesticated silkworm, Bombyx mori, and the wild silkworm, Samia cynthia ricini, respectively. The structures of B. mori silk fibroin before and after spinning were determined by using an appropriate model peptide, (AG)(15), with several solid-state NMR methods; (13)C two-dimensional spin-diffusion solid-state NMR and rotational echo double resonance (REDOR) NMR techniques along with the quantitative use of the conformation-dependent (13)C CP/MAS chemical shifts. The structure of S. c. ricini silk fibroin before spinning was also determined by using a model peptide, GGAGGGYGGDGG(A)(12)GGAGDGYGAG, which is a typical repeated sequence of the silk fibroin, with the solid-state NMR methods. The transition from the structure of B. mori silk fibroin before spinning to the structure after spinning was studied with molecular dynamics calculation by taking into account several external forces applied to the silk fibroin in the silkworm. PMID:15132647

  15. Silk Fibroin Conduits: A Cellular and Functional Assessment of Peripheral Nerve Repair

    OpenAIRE

    Ghaznavi, Amir Mahan; Kokai, Lauren E.; Lovett, Michael L.; Kaplan, David L.; Marra, Kacey G

    2011-01-01

    Novel silk fibroin conduits were designed with appropriate porosity for peripheral nerve repair. The aim of this work was to utilize these conduits to examine cell inflammatory responses and functional recovery in a sciatic nerve defect model.

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

    Directory of Open Access Journals (Sweden)

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

    2012-08-01

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

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

    OpenAIRE

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

    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...

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

    OpenAIRE

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

    2012-01-01

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

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

    OpenAIRE

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

    2011-01-01

    Presently, some view silk fibroin-based biomaterials as obsolete, being outperformed by a host of newly discovered biomaterials. But several lines of evidence support the notion that silk fibroin proteins, especially those from B. mori and spiders and their recombinant forms, particularly in the form of electrospun nanofiber scaffolds, still represent promising tools for human tissue engineering/regeneration. Inevitably, the allure of recently reported biomaterials turns away many scientists ...

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

    OpenAIRE

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

    2010-01-01

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

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

    OpenAIRE

    ZHAO, Jun; ZHANG, ZHIYUAN; Wang, Shaoyi; Sun, Xiaojuan; Zhang, Xiuli; CHEN, JAKE; Kaplan, David L.; Jiang, Xinquan

    2009-01-01

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

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

    OpenAIRE

    Chuleerat Wongnarat; Prasong Srihanam

    2013-01-01

    The degradation behaviors of Thai Bombyx mori called Samrong and Nanglai silk fibroins exposure to protease enzymes; protease XIV, protease XXIII and ?-chymotrypsin type II were studied in this work. The degradation behaviors were expressed by their weight loss, morphological and secondary structure changes as well as thermal properties. Samrong showed higher percentage of weight loss than Nanglai. SEM micrographs indicated that silk fibroin were de- stroyed and showed many holes on their fi...

  3. 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)

  4. 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.

  5. 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...

  6. 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)

  7. Antimicrobial Silk Fibroin Hydrogel Instantaneously Induced by Cationic Surfactant

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    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.

  8. CO2-assisted synthesis of silk fibroin hydrogels and aerogels.

    Science.gov (United States)

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

    2014-10-01

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

  9. Silk Fibroin-Based Nanoparticles for Drug Delivery

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    Zheng Zhao

    2015-03-01

    Full Text Available Silk fibroin (SF is a protein-based biomacromolecule with excellent biocompatibility, biodegradability and low immunogenicity. The development of SF-based nanoparticles for drug delivery have received considerable attention due to high binding capacity for various drugs, controlled drug release properties and mild preparation conditions. By adjusting the particle size, the chemical structure and properties, the modified or recombinant SF-based nanoparticles can be designed to improve the therapeutic efficiency of drugs encapsulated into these nanoparticles. Therefore, they can be used to deliver small molecule drugs (e.g., anti-cancer drugs, protein and growth factor drugs, gene drugs, etc. This paper reviews recent progress on SF-based nanoparticles, including chemical structure, properties, and preparation methods. In addition, the applications of SF-based nanoparticles as carriers for therapeutic drugs are also reviewed.

  10. Silk fibroin-based nanoparticles for drug delivery.

    Science.gov (United States)

    Zhao, Zheng; Li, Yi; Xie, Mao-Bin

    2015-01-01

    Silk fibroin (SF) is a protein-based biomacromolecule with excellent biocompatibility, biodegradability and low immunogenicity. The development of SF-based nanoparticles for drug delivery have received considerable attention due to high binding capacity for various drugs, controlled drug release properties and mild preparation conditions. By adjusting the particle size, the chemical structure and properties, the modified or recombinant SF-based nanoparticles can be designed to improve the therapeutic efficiency of drugs encapsulated into these nanoparticles. Therefore, they can be used to deliver small molecule drugs (e.g., anti-cancer drugs), protein and growth factor drugs, gene drugs, etc. This paper reviews recent progress on SF-based nanoparticles, including chemical structure, properties, and preparation methods. In addition, the applications of SF-based nanoparticles as carriers for therapeutic drugs are also reviewed. PMID:25749470

  11. Silk fibroin nanoparticle as a novel drug delivery system.

    Science.gov (United States)

    Mottaghitalab, Fatemeh; Farokhi, Mehdi; Shokrgozar, Mohammad Ali; Atyabi, Fatemeh; Hosseinkhani, Hossein

    2015-05-28

    Design and synthesis of efficient drug delivery systems are of vital importance for medicine and healthcare. Nanocarrier-based drug delivery systems, in particular nanoparticles, have generated great excitement in the field of drug delivery since they provide new opportunities to overcome the limitations of conventional delivery methods with regards to the drugs. Silk fibroin (SF) is a naturally occurring protein polymer with several unique properties that make it a suitable material for incorporation into a variety of drug delivery vehicles capable of delivering a range of therapeutic agents. SF matrices have been shown to successfully deliver anticancer drugs, small molecules, and biomolecules. This review will provide an in-depth discussion of the development of SF nanoparticle-based drug delivery systems. PMID:25797561

  12. Silk Fibroin Film Loaded Chlorhexidine Diacetate: Interaction and Characteristics

    Directory of Open Access Journals (Sweden)

    N. Noi

    2009-01-01

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

  13. Silk fibroin porous scaffolds for nucleus pulposus tissue engineering

    International Nuclear Information System (INIS)

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

  14. Self-assembly model, hepatocytes attachment and inflammatory response for silk fibroin/chitosan scaffolds

    International Nuclear Information System (INIS)

    Silk fibroin is an attractive natural fibrous protein for biomedical application due to its good biocompatibility and high tensile strength. Silk fibroin is apt to form a sheet-like structure during the freeze-drying process, which is not suitable for the scaffold of tissue engineering. In our former study, the adding of chitosan promoted the self-assembly of silk fibroin/chitosan (SFCS) into a three-dimensional (3D) homogeneous porous structure. In this study, a model of the self-assembly is proposed; furthermore, hepatocytes attachment and inflammatory response for the SFCS scaffold were examined. The rigid chain of chitosan may be used as a template for ?-sheet formation of silk fibroin, and this may break the sheet structure of the silk fibroin scaffold and promote the formation of a 3D porous structure of the SFCS scaffold. Compared with the polylactic glycolic acid scaffold, the SFCS scaffold further facilitates the attachment of hepatocytes. To investigate the inflammatory response, SFCS scaffolds were implanted into the greater omentum of rats. From the results of implantation, we could demonstrate in vivo that the implantation of SFCS scaffolds resulted in only slight inflammation. Keeping the good histocompatibility and combining the advantages of both fibroin and chitosan, the SFCS scaffold could be a prominent candidate for soft tissue engineering, for example, in the liver.

  15. 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.

  16. Silks produced by insect labial glands.

    Czech Academy of Sciences Publication Activity Database

    Sehnal, František; Sutherland, T.

    Austin : Landes Bioscience, 2008 - (Scheibel, T.), s. 106-120 ISBN 978-1-58706-316-9 R&D Projects: GA AV ?R IAA5007402 Institutional research plan: CEZ:AV0Z50070508 Keywords : silks * Insect * labial glands Subject RIV: ED - Physiology

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

    OpenAIRE

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

    2012-01-01

    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 distingu...

  18. Dental pulp tissue engineering with bFGF-incorporated silk fibroin scaffolds.

    Science.gov (United States)

    Yang, Jing-Wen; Zhang, Yu-Feng; Sun, Zhe-Yi; Song, Guang-Tai; Chen, Zhi

    2015-08-01

    The clinical translation of regenerative endodontics demands further development of suitable scaffolds. Here, we assessed the possibility of using silk fibroin scaffold for pulp regeneration with dental pulp stem cells (DPSCs) and basic fibroblast growth factor (bFGF) in ectopic root canal transplantation model. Porous silk fibroin scaffolds were fabricated using freeze-drying technique (with or without bFGF incorporation), and characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. DPSCs were isolated, characterized, seeded onto scaffolds, and inserted into the tooth root fragments. Cell viability and morphology were tested in the 3D model in vitro using CCK8 assay and SEM. Furthermore, the ectopic transplantation model was used to verify the generation of pulp-like tissue in DPSCs seeded silk fibroin scaffold with bFGF, as examined by histological analysis. DPSCs seeded in silk fibroin scaffold survived, exhibited cytoplasmic elongation in scaffolds at least 4 weeks in culture. bFGF promoted DPSCs viability in tooth fragments/scaffolds (TSS) between 7 and 28 days. Pulp-like tissue was generated in the bFGF-incorporated TSS with DPSCs. Histologically, the generated tissue was shown to be with well vascularity, have new matrix deposition and dentin-like tissue formation, and consist of both the transplanted and host-derived cells. Collectively, these data support the use of bFGF-incorporated silk fibroin scaffold as a highly promising scaffold candidate for future treatment concepts in regenerative endodontics to save teeth. PMID:25791684

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Stability and cytocompatibility of silk fibroin-capped gold nanoparticles.

    Science.gov (United States)

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

    2014-10-01

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

  4. Fabrication of silk fibroin nanoparticles for controlled drug delivery

    International Nuclear Information System (INIS)

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

  5. Bioconjugation of silk fibroin nanoparticles with enzyme and Peptide and their characterization.

    Science.gov (United States)

    Wang, Fei; Zhang, Yu-Qing

    2015-01-01

    Bombyx mori silk fibroin is a type of protein-based polymer with unique characteristics that is widely used in the research and development of medical biomaterials. The degummed filament of silk fibroin can be dissolved in a highly concentrated salt solution. After desalination, the regenerated liquid silk fibroin (LSF) solution could be made into various forms of silk biomaterials, such as powder, fiber, film, porous matrix, 3D scaffold, and hydrogel, depending on its application. In this study, we mixed the liquid silk solution with enzymes, including oxidase and hydrolase, and rapidly injected the mixture into an excess of acetone. The enzyme retained most of its enzymatic activity and was also captured in silk fibroin nanoparticles (SFNs), which instantly formed via a configuration transition of the regenerated silk protein from a random coil and ?-helix to a ?-sheet. The resulting enzyme-captured SFNs displayed a fine crystal structure with a high activity recovery and good thermal stability. Moreover, the affinities of these modified enzymes to their substrate did not evidently suffer from the capture. When only the liquid silk solution was rapidly injected into acetone, the resulting globular SFNs with the same crystallinity were also a good carrier that was covalently conjugated to enzymes and insulin. Thus, silk protein nanoparticles are of potential value as an enzyme or peptide delivery system for the research and development of medical biomaterials. In this report, the bioconjugation of SFNs with glucose oxidase, superoxidase, ?-glucosidase, l-asparaginase, neutral protease, and insulin and their characterization are described in detail. PMID:25819282

  6. 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)

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2008-01-01

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

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

    International Nuclear Information System (INIS)

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

  10. 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.

  11. Memory-enhancing effects of silk fibroin-derived peptides in scopolamine-treated mice.

    Science.gov (United States)

    Kang, Yong Koo; Lee, Woojoo; Kang, Byunghoon; Kang, Hannah

    2013-12-01

    Although enzyme-hydrolyzed silk fibroin has been reported to enhance cognitive function before, it has been still unknown which peptides can improve memory. Here we report that amino acid sequences of three novel peptides were identified from fibroin hydrolysate. Fibroin hydrolysate was obtained by hydrolysis with protease after partial hydrolysis with 5M CaCl2. Synthesized peptides derived from these sequences improved scopolamine-induced memory impairments in mice. We confirmed this hydrolysate had effects that improved learning and memory abilities by performing the Rey-Kim test. From this hydrolysate of silk fibroin, amino acid sequences of eight peptides were identified by LC-MS/MS. Three peptides (GAGAGTGSSGFGPY, GAGAGSGAGSGAGAGSGAGAGY, and SGAGSGAGAGSGAGAGSGA) were synthesized to investigate whether they could improve memory. Passive avoidance test and Morris water maze test were performed, and all peptides showed memory-enhancing abilities on scopolamine-induced memory impairments in mice. In this study, we identified three novel peptides that could improve memory, and that silk fibroin hydrolysate was a mixture of various active peptides that could enhance memory. PMID:24043122

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

    OpenAIRE

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

    2010-01-01

    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 (...

  13. 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)

  14. Comprehensive characterization of well-defined silk fibroin surfaces: Toward multitechnique studies of surface modification effects.

    Science.gov (United States)

    Amornsudthiwat, Phakdee; Nitschke, Mirko; Zimmermann, Ralf; Friedrichs, Jens; Grundke, Karina; Pöschel, Kathrin; Damrongsakkul, Siriporn; Werner, Carsten

    2015-01-01

    The study aims at a comprehensive surface characterization of untreated and oxygen plasma-treated silk fibroin with a particular focus on phenomena relevant to biointeraction and cell adhesion. For that purpose, a range of advanced surface diagnostic techniques is employed to thoroughly investigate well-defined and especially clean silk fibroin samples in a comparable setting. This includes surface chemistry and surface charges as factors, which control protein adsorption, but also hydration and swelling of the material as important parameters, which govern the mechanical stiffness at the interface with aqueous media. Oxygen plasma exposure of silk fibroin surfaces reveals that material ablation strongly predominates over the introduction of functional groups even for mild plasma conditions. A substantial increase in mechanical stiffness is identified as the most prominent effect upon this kind of plasma treatment. Regarding the experimental approach and the choice of techniques, the work goes beyond previous studies in this field and paves the way for well-founded investigations of other surface-selective modification procedures that enhance the applicability of silk fibroin in biomedical applications. PMID:25899685

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

    International Nuclear Information System (INIS)

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

  16. 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

  17. Macro/micro porous silk fibroin scaffolds obtained via combined methodologies for articular cartilage and meniscus tissue engineering

    OpenAIRE

    Yan, Leping; Oliveira, Joaquim M.; Oliveira, Ana Leite; Caridade, S. G.; Mano, J. F.; Reis, R. L.

    2011-01-01

    This work has shown that the developed silk fibroin scaffolds can combine adequate mechanical properties with a unique morphology which make them suitable to be used in tissue engineering applications, particularly for cartilage and meniscus regeneration.

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

    OpenAIRE

    M. Fazley Elahi; Guoping Guan; Lu Wang; Martin W. King

    2014-01-01

    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...

  19. Potential of 3-D tissue constructs engineered from bovine chondrocytes / silk fibroin-chitosan for in vitro cartilage tissue engineering

    OpenAIRE

    Bhardwaj, Nandana; Nguyen, Quynhhoa T.; Chen, Albert C; Kaplan, David L.; Sah, Robert L.; Kundu, Subhas C.

    2011-01-01

    The use of cell-scaffold constructs is a promising tissue engineering approach to repair cartilage defects and to study cartilaginous tissue formation. In this study, silk fibroin/chitosan blended scaffolds were fabricated and studied for cartilage tissue engineering. Silk fibroin served as a substrate for cell adhesion and proliferation while chitosan has a structure similar to that of glycosaminoglycans, and shows promise for cartilage repair. We compared the formation of cartilaginous tiss...

  20. Non-mulberry silk fibroin influence osteogenesis and osteoblast-macrophage cross talk on titanium based surface

    OpenAIRE

    Deboki Naskar; Sunita Nayak; Tuli Dey; Kundu, Subhas C.

    2014-01-01

    The titanium and its alloys are used as orthopedic dental implants due to their mechanical and bio-inert properties. The bare metal implants are not the ultimate answer for better osteogenesis and implant integration. Physical and chemical modifications are carried out to achieve the goal of improved adhesion and differentiation of the osteoblast. In this work, the silk fibroins from both mulberry and non-mulberry sources are used for surface modification. Silk fibroins are immobilized on tit...

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

    Science.gov (United States)

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

    2014-01-01

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

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

    International Nuclear Information System (INIS)

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

  3. The organization of silk fibroin in pyralid moths.

    Czech Academy of Sciences Publication Activity Database

    Žurovec, Michal; Fedi?, Robert; Sehnal, František

    Tuscon : University of Arizona, 2002. s. 122. [International symposium on molecular insect science /4./. 28.05.2002-02.06.2002, Tuscon] Institutional research plan: CEZ:AV0Z5007907 Keywords : fibroin Subject RIV: CE - Biochemistry

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

    Directory of Open Access Journals (Sweden)

    2008-12-01

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

  5. 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.

  6. 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.

  7. Drug loading and release on tumor cells using silk fibroin–albumin nanoparticles as carriers

    International Nuclear Information System (INIS)

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

  8. 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)

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

    OpenAIRE

    Tsujimoto, Y; Suzuki, Y.

    1984-01-01

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

  10. Surface modification of silk fibroin fabric using layer-by-layer polyelectrolyte deposition and heparin immobilization for small-diameter vascular prostheses.

    Science.gov (United States)

    Elahi, M Fazley; Guan, Guoping; Wang, Lu; Zhao, Xinzhe; Wang, Fujun; King, Martin W

    2015-03-01

    There is an urgent need to develop a biologically active implantable small-diameter vascular prosthesis with long-term patency. Silk-fibroin-based small-diameter vascular prosthesis is a promising candidate having higher patency rate; however, the surface modification is indeed required to improve its further hemocompatibility. In this study, silk fibroin fabric was modified by a two-stage process. First, the surface of silk fibroin fabric was coated using a layer-by-layer polyelectrolyte deposition technique by stepwise dipping the silk fibroin fabric into a solution of cationic poly(allylamine hydrochloride) (PAH) and anionic poly(acrylic acid) (PAA) solution. The dipping procedure was repeated to obtain the PAH/PAA multilayers deposited on the silk fibroin fabrics. Second, the polyelectrolyte-deposited silk fibroin fabrics were treated in EDC/NHS-activated low-molecular-weight heparin (LMWH) solution at 4 °C for 24 h, resulting in immobilization of LMWH on the silk fibroin fabrics surface. Scanning electron microscopy, atomic force microscopy, and energy-dispersive X-ray data revealed the accomplishment of LMWH immobilization on the polyelectrolyte-deposited silk fibroin fabric surface. The higher the number of PAH/PAA coating layers on the silk fibroin fabric, the more surface hydrophilicity could be obtained, resulting in a higher fetal bovine serum protein and platelets adhesion resistance properties when tested in vitro. In addition, compared with untreated sample, the surface-modified silk fibroin fabrics showed negligible loss of bursting strength and thus reveal the acceptability of polyelectrolytes deposition and heparin immobilization approach for silk-fibroin-based small-diameter vascular prostheses modification. PMID:25671295

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

    International Nuclear Information System (INIS)

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

  12. Incorporation of Methionine Analogues Into Bombyx mori Silk Fibroin for Click Modifications.

    Science.gov (United States)

    Teramoto, Hidetoshi; Kojima, Katsura

    2015-05-01

    Bombyx mori silk fibroin incorporating three methionine (Met) analogues-homopropargylglycine (Hpg), azidohomoalanine (Aha), and homoallylglycine (Hag)-can be produced simply by adding them to the diet of B. mori larvae. The Met analogues are recognized by methionyl-tRNA synthetase, bound to tRNA(Met) , and used for the translation of adenine-uracil-guanine (AUG) codons competitively with Met. In the presence of the standard amount of Met in the diet, incorporation of these analogues remains low. Lowering the amount of Met in the diet drastically improves incorporation efficiencies. Alkyne and azide groups in Hpg and Aha incorporated into silk fibroin can be selectively modified with Cu-catalyzed azide-alkyne cycloaddition reactions (click chemistry). Since Met residues exist only at the N-terminal domain of the fibroin heavy chain and in the fibroin light chain, good access to the reactive sites is expected and domain-selective modifications are possible without perturbing other major domains, including repetitive domains. PMID:25644632

  13. 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)

  14. 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...

  15. Characterization of Silk Fibroin Modified Surface: A Proteomic View of Cellular Response Proteins Induced by Biomaterials

    OpenAIRE

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

    2014-01-01

    The purpose of this study was to develop the pathway of silk fibroin (SF) biopolymer surface induced cell membrane protein activation. Fibroblasts were used as an experimental model to evaluate the responses of cellular proteins induced by biopolymer material using a mass spectrometry-based profiling system. The surface was covered by multiwalled carbon nanotubes (CNTs) and SF to increase the surface area, enhance the adhesion of biopolymer, and promote the rate of cell proliferation. The amo...

  16. 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...

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

    OpenAIRE

    Renchuan You; Xiufang Li; Yamei Xu; Yu Liu; Shenzhou Lu; Mingzhong Li

    2014-01-01

    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 micro...

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

    OpenAIRE

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

    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...

  19. 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.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2007-02-01

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

  2. 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.

  3. Evaluation of the properties of silk fibroin films from the non-mulberry silkworm Samia cynthia ricini for biomaterial design.

    Science.gov (United States)

    Mai-ngam, Katanchalee; Boonkitpattarakul, Kanhokthorn; Jaipaew, Jirayut; Mai-ngam, Bunpot

    2011-01-01

    Silk fibroin from a domesticated mulberry silkworm, Bombyx mori, is the most widely used in biomaterial design. We report for the first time the preparation of a relatively smooth (granule free) film of the nonmulberry Samia cynthia ricini fibroin for comparative evaluation of its cell-supporting properties against those of the B. mori fibroin film. The granule formation on the S. c. ricini fibroin film was successfully prevented by facilitating proper rearrangement of the protein molecules, as monitored by FT-IR, by dialysis through a stepwise decrease in the urea concentration in the dialysis media. The lower contact angle of the S. c. ricini fibroin film, compared to the B. mori fibroin film, corresponds well to its lower hydrophobic/hydrophilic amino-acid ratio and grand average of hydropathicity (GRAVY). L929 murine fibroblast cells on the granule-free S. c. ricini fibroin films exhibited greater proliferation and spreading rates than those on the B. mori fibroin films, possibly attributable to its higher content of hydrophilic and positively charged amino acids. It further suggests that fabrication, modification and/or engineering of S. c. ricini fibroin may provide a better biomaterial scaffold design than the more commonly used B. mori fibroin. PMID:21029516

  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 fas tissue engineering tendon scaffold is feasible.

  5. SILK FIBROIN AS A COMPONENT OF SCAFFOLDS FOR TISSUE ENGINEERING

    OpenAIRE

    MAROTTA, LAURA AMELIA

    2012-01-01

    Since the scaffolds are implantable systems designed to promote the growth of new tissue, they have to maintain their characteristics in the physiologic environment for a relative long period, until the moment the new tissue is completely reconstituted and the scaffold can start to degrade. The scaffold features totally depend from the scaffold material, which must confer to the structure the suitable morphologic and mechanical properties. Natural fibroin is a proteic polymer that possess...

  6. Conservation of Silk Genes in Trichoptera and Lepidoptera

    OpenAIRE

    Yonemura, Naoyuki; Mita, Kazuei; Tamura, Toshiki; Sehnal, František

    2009-01-01

    Larvae of the sister orders Trichoptera and Lepidoptera are characterized by silk secretion from a pair of labial glands. In both orders the silk filament consists of heavy (H)- and light (L)-chain fibroins and in Lepidoptera it also includes a P25 glycoprotein. The L-fibroin and H-fibroin genes of Rhyacophila obliterata and Hydropsyche angustipennis caddisflies have exon/intron structuring (seven exons in L-fibroin and two in H-fibroin) similar to that in their counterparts in Lepidoptera. F...

  7. Unique molecular architecture of silk fibroin in the waxmoth.

    Czech Academy of Sciences Publication Activity Database

    Žurovec, Michal; Sehnal, František

    2002-01-01

    Ro?. 277, ?. 25 (2002), s. 22639-22647. ISSN 0021-9258 R&D Projects: GA ?R GA204/96/1100; GA ?R GA204/00/0019; GA MŠk ME 204 Institutional research plan: CEZ:AV0Z5007907 Keywords : silk Subject RIV: EG - Zoology Impact factor: 6.696, year: 2002

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

    OpenAIRE

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

    2010-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ming-Hui Yang

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-04-01

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

  12. 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

  13. Bioinspired porous octacalcium phosphate/silk fibroin composite coating materials prepared by electrochemical deposition.

    Science.gov (United States)

    Yang, Ya; Wang, Hui; Yan, Feng-Yi; Qi, Yu; Lai, Yue-Kun; Zeng, Dong-Mei; Chen, Guoqiang; Zhang, Ke-Qin

    2015-03-18

    The biomimetic structure and composition of biomaterials are recognized as critical factors that determine their biological performance. A bioinspired nano-micro structured octacalcium phosphate (OCP)/silk fibroin (SF) composite coating on titanium was achieved through a mild electrochemically induced deposition method. Findings indicate that SF plays a critical role in constructing the unique biomimetic hierarchical structure of OCP/SF composite coating layers. In vitro cell culture tests demonstrate that the presence of OCP/SF composite coatings, with highly ordered and hierarchically porous structure, greatly enhance cellular responses. The coatings developed in this study have considerable potential for various hard tissue engineering and applications. PMID:25734421

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  16. Dynamic phase transition of silk fibroin in two-and three-dimensional convergent flows

    International Nuclear Information System (INIS)

    Two-and three-dimensional convergent flows of silk fibroin model systems in 2.5 M LiCl-DMFA and 7.7 M NaCNS-water were modeling. By birefringence and dispersion optical rotation methods the dynamic phase transition processes at the flow in environment solutions and free one are investigated. The solution-gel transition can be realized by I and II kind phase transition mechanisms depending on chain conformation changing. Possibility of band-form film preparation by hardening the gel-band in the two-dimensional convergent flow is showed. (author)

  17. Silk fibroin/hyaluronic acid 3D matrices for cartilage tissue engineering.

    Science.gov (United States)

    Foss, Cristina; Merzari, Enrico; Migliaresi, Claudio; Motta, Antonella

    2013-01-14

    In spite of commercially available products, the complete and sustained repair of damaged articular cartilage still presents various challenges. Among biomaterials proposed for cartilage repair, silk fibroin (SF) has been recently proposed as a material template for porous scaffolds cultured with chondrocytes and investigated in static and dynamic conditions. In addition to fibroin-based constructs, literature has reported that the combination of hyaluronic acid (HA) with other scaffold materials can protect the chondral phenotype and the cells in vitro response to the scaffold. In this study, the effect of the addition of HA on the physical properties of SF sponges, with and without cross-linking with genipin, was investigated. Salt-leached scaffolds were characterized in terms of morphology and structural and physical properties, as well as mechanical performance. Un-cross-linked sponges resulted in the physical separation of highly hydrophilic HA from the SF, while cross-linking prevented this phenomenon, resulting in a homogeneous blend. The presence of HA also influenced fibroin crystallinity and tended to decrease the cross-linking degree of the scaffolds when compared to the pure SF material. PMID:23134349

  18. 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

  19. Fabrication and characterization of silk fibroin-coated liposomes for ocular drug delivery.

    Science.gov (United States)

    Dong, Yixuan; Dong, Pin; Huang, Di; Mei, Liling; Xia, Yaowen; Wang, Zhouhua; Pan, Xin; Li, Ge; Wu, Chuanbin

    2015-04-01

    The unique structure and protective mechanisms of the eye result in low bioavailability of ocular drugs. Using a mucoadhesive material is an efficient solution to improve ocular drug therapeutic efficacy. This study was designed to prepare a liposomal formulation coated by a novel adhesive excipient, silk fibroin (SF), for topical ocular drug delivery. The regenerated silk fibroins (SFs) with different dissolving time were coated onto the ibuprofen-loaded liposomes. The morphology, drug encapsulation efficiency, in vitro release and in vitro corneal permeation of SF-coated liposomes (SLs) were investigated in comparison with the conventional liposome. Cellular adhesion and cytotoxicity assay of SF and SLs were tested using human corneal epithelial cells (HCEC). SLs showed sustained drug release and in vitro corneal permeation of ibuprofen as compared to drug solution and conventional liposome. The cellular fluorescence appeared after 7 min of exposure to SF, and the intensity increased sustainedly up to 12h with no detectable cytotoxicity. Higher fluorescence intensity of Nile red in SLs was observed in a short period of 15 min showing a rapid uptake. These favorable properties make SF-coated liposome be a promising ocular drug delivery system. PMID:25643990

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

    International Nuclear Information System (INIS)

    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 Ca2+ 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: ? Regenerated silk fibroin fibers were prepared by using a dry spinning method. ? Dope compositions affect dope spinnability. ? Spinning parameters affect dope spinnability and fiber properties. ? The breaking stress of the post-treated fiber was up to 359 MPa.

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

    Directory of Open Access Journals (Sweden)

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

    2009-03-01

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

  2. 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

  3. Comparison of Silk Glands of Diapause and Non-Diapause Larval Sitodiplosis mosellana

    OpenAIRE

    Li, Yiping; Wu, Junxiang; Cheng, Weining; Song, Weiwu; Yuan,XiangQun

    2012-01-01

    The wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is one of the most serious pests of wheat worldwide. It overwinters as cocooned larvae in diapause and non-diapause forms. The cocoon is made of silk from the salivary glands. The silk glands, therefore, play an important role in the S. mosellana diapause. In the present study, the ultra-structures of the silk glands between diapause and non-diapause larvae were examined by electro and light-microscopically. The silk g...

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

    International Nuclear Information System (INIS)

    The Bombyx mori silk fibroin films (SFFs) were modified by a Cecropin B (CB) antimicrobial peptide, (NH2)-NGIVKAGPAIAVLGEAAL-CONH2, using the carbodiimide chemistry method. In order to avoid the dissolution of films during the modification procedure, the SFFs were first treated with 60% (v/v) ethanol aqueous solution, resulting a structural transition from unstable silk I to silk II. The investigation of modification conditions showed that the surface-modified SFFs had the satisfied antimicrobial activity and durability when they were activated by EDC.HCl/NHS solution followed by a treatment in CB peptide/PBS buffer (pH 6.5 or 8) solution at ambient temperature for 2 h. Moreover, the surface-modified SFFs showed the smaller contact angle due to the hydrophilic antimicrobial peptides coupled on the film surface, which is essential for the cell adhesion and proliferation. AFM results indicated that the surface roughness of SFFs was considerably increased after the modification by the peptides. The elemental composition analysis results also suggested that the peptides were tightly coupled to the surface of SFFs. This approach may provide a new option to engineer the surface-modified implanted materials preventing the biomaterial-centered infection (BCI)

  5. Silks produced by insect labial glands.

    Czech Academy of Sciences Publication Activity Database

    Sehnal, František; Sutherland, T.

    2008-01-01

    Ro?. 2, ?. 4 (2008), s. 145-153. ISSN 1933-6896 R&D Projects: GA MŠk ME 907 Institutional research plan: CEZ:AV0Z50070508 Keywords : silk * proteinaceous polymers * alfa-helices Subject RIV: ED - Physiology Impact factor: 0.875, year: 2008 http://www.landesbioscience.com/journals/prion/article/7489

  6. Structure and structural changes of the silk fibroin from Samia cynthia ricini using nuclear magnetic resonance spectroscopy.

    Science.gov (United States)

    Asakura, Tetsuo; Nakazawa, Yasumoto

    2004-03-15

    The structure of silk fibroin from a wild silkworm, S. c. ricini, the amino acid sequence of which consists of repeated poly-Ala and Gly-rich regions, was examined by using solution and solid-state NMR methods. The structural transition of the silk fibroin in aqueous solution was monitored by using 13C solution NMR spectroscopy as a function of temperature. The fast exchange with respect to the chemical shift between the helix and coil conformations was observed in the poly-Ala region and the slow conformational change from alpha-helix to random coil was observed for the Gly residue adjacent to the N-terminal Ala residue of the poly-Ala region. The torsion angles of several Ala and Gly residues in the model peptide, GGAGGGYGGDGG(A)12GGA-GDGYGAG, were determined by the conformation-dependent 13C chemical shifts, rotational echo double resonance (REDOR) and 2D spin-diffusion NMR methods. The solid-state NMR analysis leads to the precise silk structure before spinning, where the poly-Ala sequence takes a typical alpha-helix pattern with a tightly winded helical structure at both terminal regions of the poly-Ala sequence. This is expected to stabilize the alpha-helical structure of the poly-Ala region in S. c. ricini silk fibroin from the silkworm. PMID:15468207

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

    Directory of Open Access Journals (Sweden)

    Chirapha Butiman

    2012-07-01

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

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

    Directory of Open Access Journals (Sweden)

    Yodthong Baimark

    2009-01-01

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

  9. Preparation and Characterization of Insoluble Silk Fibroin/Chitosan Blend Films

    Directory of Open Access Journals (Sweden)

    Mariana Agostini de Moraes

    2010-12-01

    Full Text Available The aim of this study was to prepare and characterize membranes of silk fibroin (SF and chitosan (CHI blends. Moreover, a conformation transition of SF to a more stable form induced by the addition of CHI was verified. Blend membranes were prepared, after pH adjustment, in different ratios, and physical integrity, crystallinity, structural conformation and thermal stability were characterized. The results of crystallographic analysis (XRD indicated the tendency to higher structural organization caused by the addition of CHI. Fourier transformed infrared spectroscopy (FTIR showed that SF is present in a more stable form in the presence of a CHI content of only 25 wt%. Thermal analysis indicated that SF is thermally stable and that when its proportion in the blend increases, the temperature at which degradation is initiated also increases.

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

    Directory of Open Access Journals (Sweden)

    M. Srisa-Ard

    2008-01-01

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

  13. 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.

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

    Directory of Open Access Journals (Sweden)

    Lin Niu

    2010-01-01

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

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

    International Nuclear Information System (INIS)

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

  16. 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

  17. 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.

  18. 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; Junior, Osmir Batista de Oliveira; 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

  19. 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

  20. 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

  1. Comparison of silk glands of diapause and non-diapause larval Sitodiplosis mosellana.

    Science.gov (United States)

    Li, Yiping; Wu, Junxiang; Cheng, Weining; Song, Weiwu; Yuan, Xiangqun

    2012-01-01

    The wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is one of the most serious pests of wheat worldwide. It overwinters as cocooned larvae in diapause and non-diapause forms. The cocoon is made of silk from the salivary glands. The silk glands, therefore, play an important role in the S. mosellana diapause. In the present study, the ultra-structures of the silk glands between diapause and non-diapause larvae were examined by electro and light-microscopically. The silk glands consist of 156 cells organized like moniliform particles. Although silk gland cells of both diapause and non-diapause larvae contain developed organelles, including the endoplasmic reticulum, dictyosome, mitochondria, and lipid droplet, the organelles in non-diapause larvae are more developed than those in diapause larvae. These morphological characteristics of the silk glands in the diapause and non-diapause larvae can be used to distinguish the diapause status of the larvae. PMID:23414141

  2. Heterogeneous exchange behavior of Samia cynthia ricini silk fibroin during helix-coil transition studied with (13)C NMR.

    Science.gov (United States)

    Nakazawa, Yasumoto; Asakura, Tetsuo

    2002-10-01

    The structure and structural transition of the glycine residue adjacent to the N-terminal alanine residue of the poly(L-alanine), (Ala)(12-13), region in Samia cynthia ricini silk fibroin was studied using (13)C nuclear magnetic resonance (NMR). Most of the glycine carbonyl peaks in the (13)C solution NMR spectrum of [1-(13)C]glycine-silk fibroin could be assigned to the primary structure from the comparison of the (13)C chemical shifts of seven glycine-containing tripeptides. The slow exchange between helix and coil forms in the NMR time scale was observed with increasing temperature exclusively for the underlined glycine residue in the Gly-Gly-(Ala)(12-13) sequence during fast helix-coil transition of the (Ala)(12-13) region. PMID:12372598

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

    International Nuclear Information System (INIS)

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

  4. 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 alizarin red staining, and elemental analysis of crystalline composites isolated from the scaffolds. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 971-982, 2015. PMID:25176408

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

    International Nuclear Information System (INIS)

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

  6. Biocompatibility study of a silk fibroin-chitosan scaffold with adipose tissue-derived stem cells in vitro

    OpenAIRE

    Ji, Wenchen; Zhang, Yuelin; Hu, Shouye; Zhang, Yongtao

    2013-01-01

    The use of tissue engineering technology in the repair of spinal cord injury (SCI) is a topic of current interest. The success of the repair of the SCI is directly affected by the selection of suitable seed cells and scaffold materials with an acceptable biocompatibility. In this study, adipose tissue-derived stem cells (ADSCs) were incorporated into a silk fibroin-chitosan scaffold (SFCS), which was constructed using a freeze-drying method, in order to assess the biocompatibility of the ADSC...

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

    OpenAIRE

    Stoppato, M.; Stevens, H. Y.; Carletti, E.; 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...

  8. Fibroin and Sericin from Bombyx mori Silk Stimulate Cell Migration through Upregulation and Phosphorylation of c-Jun

    OpenAIRE

    Martínez-Mora, Celia; Mrowiec, Anna; García-Vizcaíno, Eva María; Alcaraz, Antonia; Cenis, José Luis; Nicolás, Francisco José

    2012-01-01

    Wound healing is a biological process directed to the restoration of tissue that has suffered an injury. An important phase of wound healing is the generation of a basal epithelium able to wholly replace the epidermis of the wound. A broad range of products derived from fibroin and sericin from Bombyx mori silk are used to stimulate wound healing. However, so far the molecular mechanism underlying this phenomenon has not been elucidated. The aim of this work was to determine the molecular bas...

  9. 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...

  10. 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

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

    Science.gov (United States)

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

    2013-08-01

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

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

    International Nuclear Information System (INIS)

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

  13. Tightly winding structure of sequential model peptide for repeated helical region in Samia cynthia ricini silk fibroin studied with solid-state NMR

    OpenAIRE

    Nakazawa, Yasumoto; Bamba, Mie; Nishio, Satoko; Asakura, Tetsuo

    2003-01-01

    There are many kinds of silks from silkworms and spiders with different structures and properties, and thus, silks are suitable to study the structure-property relationship of fibrous proteins. Silk fibroin from a wild silkworm, Samia cynthia ricini, mainly consists of the repeated similar sequences by about 100 times where there are alternative appearances of the polyalanine (Ala)12–13 region and the Gly-rich region. In this paper, a sequential model peptide, GGAGGGYGGDGG(A)12GGAGDGYGAG, w...

  14. 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

  15. 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.

  16. Reduced level of secretion and absence of subunit combination for the fibroin synthesized by a mutant silkworm, Nd(2)

    OpenAIRE

    1984-01-01

    Fibroin is normally composed of one H chain (350 kd) and one L chain (25 kd) which are connected by disulfide bond(s). However, the small amount of fibroin secreted into the lumen of the posterior silk gland of the Nd(2) (naked pupa) mutant does not contain L chain, although L chain mRNA is present and L chain is synthesized in the posterior silk gland cells of the mutant. In a hybrid silkworm, Nd(2)/Tamanashikasuri, where Tamanashikasuri is a normal producer of fibroin, L chain from the two ...

  17. Gelatin modified ultrathin silk fibroin films for enhanced proliferation of cells.

    Science.gov (United States)

    Yang, Luyuan; Yaseen, Mohammed; Zhao, Xiubo; Coffey, Paul; Pan, Fang; Wang, Yuming; Xu, Hai; Webster, John; Lu, Jian R

    2015-04-01

    Silk fibroin (SF) films were modified with gelatin (G) to explore if such SF/G films could enhance the surface biocompatibility of silk as cell growth biomaterials. Ultrathin films were coated from aqueous SF solutions pre-mixed with different amounts of G. It was found that the SF/G blended films after methanol treatment were highly stable in physiological conditions. The incorporation of G smoothed the surface morphology of the SF/G films formed. Surface-exposed RGD sequences were successfully identified on the SF/G films through specific recognition of an integrin-mimicking peptide (bearing the sequence of CWDDGWLC). Cell culture experiments with 3T3 fibroblasts demonstrated that SF/G films with 1.2-20% (w/w) G gave clear improvement in promoting cell attachment and proliferation over pure SF films. Films containing 10-20% (w/w) of G showed cell attachment and growth even superior to the pure G films. The differences as observed from this study suggest that due to the lack of mechanical strength associated with its high solubility, G could not work alone as a cell growth scaffold. The enhanced cellular responses from the blended SF/G films must result from improvement in film stability arising from SF and in cytocompatibility arising from G. The results thus indicate the potential of the SF/G blends in tissue engineering and biomedical engineering where physical and biological properties could be manipulated via mixing either as bulk biomaterials or for coating purposes. PMID:25784671

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

    OpenAIRE

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

    2013-01-01

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

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

    International Nuclear Information System (INIS)

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

  20. Morphology and thermal stability of silk fibroin/starch blended microparticles

    Directory of Open Access Journals (Sweden)

    2010-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Xiu-Mei Mo

    2011-03-01

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

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

    Science.gov (United States)

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

    2014-12-24

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

  3. 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.

  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. Silk fibroin/sodium alginate fibrous hydrogels regulated hydroxyapatite crystal growth.

    Science.gov (United States)

    Ming, Jinfa; Jiang, Zhijuan; Wang, Peng; Bie, Shiyu; Zuo, Baoqi

    2015-06-01

    Use of organic templates for controlling the growth of inorganic crystals is one of the research topics in biomimetic field. In particular, oriented growth of hydroxyapatite (HAp) in organic fibrous matrix is provided a new view angle to study biomineralization of bone and its potential biomedical applications. The crystallization of HAp in fibrous hydrogels could mimic such biomineralization. In this paper, we report HAp nanorod crystal synthesized successfully by a biomimetic method using calcium chloride and ammonium dihydrogen phosphate as reagents in the presence of silk fibroin/sodium alginate (SF/SA) fibrous hydrogels. The effects of influence factors such as mineral times, pH, and temperature on controlling HAp nanorod crystals are discussed. The elongated HAp nanorods with rectangular column are grown with the increase of mineral times in biomimetic process. By changing pH, HAp nanorod crystals are obtained at alkaline condition in fibrous hydrogels. Moreover, compared to other temperatures, rod-shaped HAp crystals were formed at 20°C. The results imply this to be an effective method for preparing HAp crystals with controllable morphology for bone repair application. PMID:25842137

  6. 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.

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    K. Nuanchai

    2009-01-01

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

  9. Directional cell elongation through filopodia-steered lamellipodial extension on patterned silk fibroin films.

    Science.gov (United States)

    You, Renchuan; Li, Xiufang; Luo, Zuwei; Qu, Jing; Li, Mingzhong

    2015-03-01

    Micropatterned biomaterials have been used to direct cell alignment for specific tissue engineering applications. However, the understanding of how cells respond to guidance cues remains limited. Plasticity in protrusion formation has been proposed to enable cells to adapt their motility mode to microenvironment. In this study, the authors investigated the key role of protrusion response in cell guidance on patterned silk fibroin films. The results revealed that the ability to transform between filopodia and small lamellipodia played important roles in directional cell guidance. Filopodia did not show directional extension on patterned substrates prior to spreading, but they transduced topographical cues to the cell to trigger the formation of small lamellipodia along the direction of a microgrooved or parallel nanofiber pattern. The polar lamellipodia formation provided not only a path with directionality, but a driving force for directional cell elongation. Moreover, aligned nanofibers coating provided better mechanical support for the traction of filopodia and lamellipodia, promoting cell attachment, spreading, and migration. This study provides new insight into how cells respond to guidance cues and how filopodia and lamellipodia control cell contact guidance on micropatterned biomaterial surfaces. PMID:25743615

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Ong-chiari Watcharin

    2009-01-01

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

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

    International Nuclear Information System (INIS)

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

  13. 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.

  14. 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

  15. 3D electrospun silk fibroin nanofibers for fabrication of artificial skin.

    Science.gov (United States)

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

    2015-04-01

    Tissue-engineered skin substitutes such as nanofibers from traditional electrospinning may offer an effective therapeutic option for the treatment of patients suffering from skin damages such as burns and diabetic ulcers. However, it is generally difficult for cells to infiltrate the nanofibers due to their small pore size and sheets-like appearance. In the present study, a facile and efficient strategy has successfully been introduced that can produce 3D silk fibroin nanofibers, obviating an intrinsic limitation of traditional and salt-leaching electrospinning by introducing cold-plate electrospinning. The cell attachment and infiltration studies indicated the use of 3D nanofiber scaffolds by cold-plate electrospinning as a potential candidate to overcome intrinsic barriers of electrospinning techniques. The 3D nanofiber scaffolds using this technique presented a high porosity with controlled thickness and an easy contouring of facial shape; these properties can contribute to the ideal candidate for artificial skin reconstruction. From the clinical editor: Electrospun nanofibers are considered as promising scaffolds for tissue engineering due to extracellular matrix mimicking factor resulting in a controllable 3D nanofibrous form. The cold-plate electrospinning technique can facilitate the fabrication of these biomaterials to create structures that could resemble the dermis. PMID:25555351

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

    Directory of Open Access Journals (Sweden)

    Derya Aytemiz

    2014-03-01

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

  17. Fabrication and characterization of bioactive silk fibroin/wollastonite composite scaffolds

    International Nuclear Information System (INIS)

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

  18. 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.

  19. 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

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

    International Nuclear Information System (INIS)

    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 ?-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.

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

    OpenAIRE

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

    2013-01-01

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

  2. Radiation degradation of silk

    International Nuclear Information System (INIS)

    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)

  3. Production and characterization of a silk-like hybrid protein, based on the polyalanine region of Samia cynthia ricini silk fibroin and a cell adhesive region derived from fibronectin.

    Science.gov (United States)

    Asakura, Tetsuo; Tanaka, Chikako; Yang, Mingying; Yao, Juming; Kurokawa, Masato

    2004-02-01

    There are a variety of silkworms and silk fibroins produced by them. Silks have many inherent suitable properties for biomaterials. In this paper, a novel silk-like hybrid protein, [DGG(A)(12)GGAASTGRGDSPAAS](5), which consists of polyalanine region of silk fibroin from a wild silkworm, Samia cynthia ricini, and cell adhesive region including Arg-Gly-Asp (RGD) sequence, derived from fibronectin, was designed and produced. The genes encoding the hybrid protein were constructed and expressed in Escherichia coli. The main conformation of the polyalanine region, that is, either alpha-helix or beta-sheet, could be easily controlled by treatment with different acidic solvents, trifluoroacetic acid or formic acid, respectively. This structural change was monitored with 13C CP/MAS NMR. Higher cell adhesive and growth activities of the hybrid protein compared with those of collagen were obtained. PMID:14607499

  4. 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

  5. Small diameter electrospun silk fibroin vascular grafts: Mechanical properties, in vitro biodegradability, and in vivo biocompatibility.

    Science.gov (United States)

    Catto, Valentina; Farè, Silvia; Cattaneo, Irene; Figliuzzi, Marina; Alessandrino, Antonio; Freddi, Giuliano; Remuzzi, Andrea; Tanzi, Maria Cristina

    2015-09-01

    To overcome the drawbacks of autologous grafts currently used in clinical practice, vascular tissue engineering represents an alternative approach for the replacement of small diameter blood vessels. In the present work, the production and characterization of small diameter tubular matrices (inner diameter (ID)=4.5 and 1.5mm), obtained by electrospinning (ES) of Bombyx mori silk fibroin (SF), have been considered. ES-SF tubular scaffolds with ID=1.5mm are original, and can be used as vascular grafts in pediatrics or in hand microsurgery. Axial and circumferential tensile tests on ES-SF tubes showed appropriate properties for the specific application. The burst pressure and the compliance of ES-SF tubes were estimated using the Laplace's law. Specifically, the estimated burst pressure was higher than the physiological pressures and the estimated compliance was similar or higher than that of native rat aorta and Goretex® prosthesis. Enzymatic in vitro degradation tests demonstrated a decrease of order and crystallinity of the SF outer surface as a consequence of the enzyme activity. The in vitro cytocompatibility of the ES-SF tubes was confirmed by the adhesion and growth of primary porcine smooth muscle cells. The in vivo subcutaneous implant into the rat dorsal tissue indicated that ES-SF matrices caused a mild host reaction. Thus, the results of this investigation, in which comprehensive morphological and mechanical aspects, in vitro degradation and in vitro and in vivo biocompatibility were considered, indicate the potential suitability of these ES-SF tubular matrices as scaffolds for the regeneration of small diameter blood vessels. PMID:26046273

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-01

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

  7. Fabrication and characterization of silk fibroin/bioactive glass composite films

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2014-03-01

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

  9. Enzymatic phosphorylation of silk fibroins : a platform for the production of biocompatible, cell-static, materials

    OpenAIRE

    Volkov, Vadim; Vasconcelos, Andreia; S??rria, M. P.; Gomes, A. C.; Paulo, Artur Cavaco

    2014-01-01

    Silks are natural protein polymers produced by insects. Silk heavy chain of B.mori is primarily composed of hydrophobic, ???(???Ala???Gly???)n??? -sheet crystalline domains. Based on silk biocompatibility, biodegradability and strength, different materials were developed. Silk offers a stabilizing environment for incorporated proteins and molecules. Silk properties can be controlled via structure manipulation, by coupling molecules of biological significance; its Tyr and Ser residues can ...

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

    OpenAIRE

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

    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...

  11. 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.

  12. Tissue-specific transcription enhancement of the fibroin gene characterized by cell-free systems.

    OpenAIRE

    Suzuki, Y.; Tsuda, M; Takiya, S; Hirose, S.; Suzuki, E.; Kameda, M; Ninaki, O

    1986-01-01

    Six cell-free extracts have been used to characterize the nature of DNA signals and trans-acting factors responsible for the transcription enhancement of the Bombyx mori fibroin gene. The upstream element of the fibroin gene involved in the enhancement can be divided into two regions. The proximal region, -72 to -32, is recognized as a common enhancing signal by all B. mori extracts from the posterior silk gland, the middle silk gland, the ovarian tissue, and an embryonic cell line. It is wea...

  13. 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.

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

    Science.gov (United States)

    Zeng, Shuguang; Ye, Manwen; Qiu, Junqi; Fang, Wei; Rong, Mingdeng; Guo, Zehong; Gao, Wenfen

    2015-01-01

    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 ?m to 147 ?m: 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. PMID:25999693

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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

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

    International Nuclear Information System (INIS)

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

  2. 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.

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

    Science.gov (United States)

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

    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 compositions. SF-based films, spray-dried microparticles, and matrixes loaded with naproxen were prepared. Both FTIR spectra and in vitro dissolution data demonstrated that SF ?-sheet conformation regulates the release profile of naproxen. The controlled release characteristics of the SF-containing compositions were evaluated as a function of SF concentration, temperature, and exposure to dehydrating solvents. The results suggest that SF may be an attractive polymer for use in controlled drug delivery systems. PMID:22506122

  4. 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

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

    International Nuclear Information System (INIS)

    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*, ? = 248 nm, ? = 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/cm2 laser fluence. FTIR spectra of FIB and HA-FIB films exhibited distinctive absorption maxima, in specific positions of FIB random coil form: 1540 cm-1 amide II, 1654 cm-1 amide I, 1243 cm-1 amide III, while the peak from 1027 cm-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,mal cell morphology. The well-elongated, flattened cells are a sign of an appropriate interaction with the MAPLE FIB and composite HA-FIB coatings.

  6. Comparative analysis of the development of the mandibular salivary glands and the labial silk glands in the mulberry silkworm, Bombyx mori.

    Science.gov (United States)

    Parthasarathy, R; Gopinathan, Karumathil P

    2005-02-01

    The mulberry silkworm, Bombyx mori has a pair of salivary glands arising from the mandibular segment, in addition to the labial silk glands which are generally considered as modified salivary glands. Here we report the characterization of salivary glands and the comparative gene expression profiling of the silk and salivary glands. The two independent salivary glands made up by 330 cells, grow about 1000 fold during larval development. These individual glands extend up to the T(1) thoracic segment unlike silk glands with fused anterior ends and extending up to the caudal region. The salivary glands also undergo endomitosis resembling the silk glands. The B. mori homologue of the homeotic gene Deformed (BmDfd) was expressed in the mandibular and maxillary segments in stage 17 embryo and got localized to the centre of the mandibular segment at stage 18 to form the salivary gland placodes. The expression was also seen in the distal ends of the leg appendages after blastokinesis (stage 22). Only low variations in BmDfd expression ranging from 1.6 to 2.1 fold were apparent during embryonic development. BmDfd expression was observed in the salivary glands all through the larval instars but not in the silk glands. The transcription factor, Forkhead and the segment polarity gene, Wingless were expressed throughout the salivary glands, the latter confirming the absence of physiological compartmentation within these glands unlike the silk glands. The expression of Amylase and Fibrohexamerin was restricted to the salivary and silk glands, respectively and therefore, served as molecular markers for these tissues. PMID:15661638

  7. 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 ...

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

    Science.gov (United States)

    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 through lyophilization. Water annealing was used to generate insolubility in the silk based scaffolds, thereby avoiding the use of organic solvents. The nano-fibrils formed in the silk-collagen scaffolds had diameters of 20-100 nanometers, similar with native collagen in ECM. The silk-collagen scaffolds dissolved slowly in PBS solution, with about a 28% mass lost after 4 weeks. Following the dissolution or degradation, the nanofibrous structure inside the macropore walls emerged and interacted with cells directly. During in vitro cell culture, the nanofibrous silk-collagen scaffolds containing 7.4% collagen demonstrated significantly improved cell-compatibility when compared with salt-leached silk scaffolds and silk-collagen scaffolds containing 20% collagen that emerged less nano-fibrils. Therefore, this new process provides useful scaffolds for tissue engineering applications. Furthermore, the process involves all-aqueous, room temperature and pressure processing without the use of toxic chemicals or solvents, offering new green chemistry approaches, as well as options to load bioactive drugs or growth factors into process. PMID:20970185

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

    Science.gov (United States)

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

    2015-01-01

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

  10. Effect of incubation temperature on the self-assembly of regenerated silk fibroin: a study using AFM.

    Science.gov (United States)

    Zhong, Jian; Liu, Xunwei; Wei, Daixu; Yan, Juan; Wang, Ping; Sun, Gang; He, Dannong

    2015-05-01

    Understanding effect of temperature on the molecular self-assembly process will be helpful to unravel the structure-function relationship of biomolecule and to provide important information for the bottom-up approach to nanotechnology. In this work, the effect of incubation temperature on the secondary structures and morphological structures of regenerated silk fibroin (RSF) was systematically studied using atomic force microscopy and Fourier Transform infrared spectroscopy. The effect of incubation temperature on RSF self-assembly was dependent on RSF concentration. For the RSF solution with relatively low concentrations (15 ?g/mL and 60 ?g/mL), the increase of the incubation temperature mainly accelerated the formation and aggregation of antiparallel ?-sheet protofibrils and decreased the formation of random coil protofilaments/globule-like molecules. For the RSF solution with relatively high concentrations (300 ?g/mL and 1.5mg/mL), the increase of the incubation temperature mainly accelerated the formation and aggregation of antiparallel ?-sheet RSF features (protofibrils and globule-like features) and decreased the formation of random coil bead-like features. This work implies that the morphology and conformation of biomacromolecules could be tuned by controlling the incubation temperature. Further, it will be beneficial to basic understanding of the nanoscale structure formation in different silk-based biomaterials. PMID:25748848

  11. Gamma-radiation synthesis of silk fibroin coated CdSe quantum dots and their biocompatibility and photostability in living cells.

    Science.gov (United States)

    Chang, Shu-Quan; Dai, Yao-Dong; Kang, Bin; Han, Wei; Chen, Da

    2009-10-01

    Silk fibroin coated CdSe quantum dots (SF-CdSe QDs) were successfully synthesized via a one-step gamma-radiation route in an aqueous system at room temperature. The as prepared products were characterized by transmission electron microscope (TEM), energy dispersion spectrum (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis) and photoluminescence spectrum (PL). The SF-CdSe QDs were about 5 nm in diameter and exhibited excellent water-solubility and photoluminescence properties. The cellular distribution, photostability and cytotoxicity of SF-CdSe QDs with different amount of SF coatings were also investigated by laser scanning confocal microscope (LSCM) and MTT assays in human pancreatic carcinoma (PANC-1) cells. All the results reveal that these QDs could be easily internalized by cells and localized in cytoplasm around nuclei. Moreover, SF-CdSe QDs were proved to be low cytotoxicity (the concentration of QDs < 5 microg mL(-1)) and high photostability (the illumination energy density < 2 x 10(-5) W microm(-2)) within PANC-1 cells, which was mainly due to the biocompatible silk fibroin. The resulted SF-CdSe QDs might have many potential applications in tumor imaging and therapy. And the synthesis strategy could be easily extended to fabrication of other nanoparticles coated with silk fibroin. PMID:19908440

  12. 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.

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

    Science.gov (United States)

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

    2015-06-01

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

  14. 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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2014-02-01

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

  17. Biodegradation of Silk Biomaterials

    Directory of Open Access Journals (Sweden)

    Bochu Wang

    2009-03-01

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

  18. Biodegradation of Silk Biomaterials

    OpenAIRE

    Bochu Wang; Yang Cao

    2009-01-01

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

  19. Participation of the upstream region of the fibroin gene in the formation of transcription complex in vitro.

    OpenAIRE

    Tsuda, M; Hirose, S.; Suzuki, Y.

    1986-01-01

    The addition of exogenous histones has an inhibitory effect on fibroin gene transcription in posterior silk gland extracts. The histones probably disturb a process in complex formation, because when transcription complexes were constructed by preincubation of the templates with the extracts, the inhibitory effect of histones was greatly reduced. Transcription of a fibroin gene construct, pFb5' delta-238, having the upstream region beyond the TATA box was relatively less inhibited than that of...

  20. 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

  1. Influence of the protocol used for fibroin extraction on the mechanical properties and fiber sizes of electrospun silk mats.

    Science.gov (United States)

    Aznar-Cervantes, Salvador D; Vicente-Cervantes, Daniel; Meseguer-Olmo, Luis; Cenis, José L; Lozano-Pérez, A Abel

    2013-05-01

    Silk fibroin (SF) was regenerated using three of the most common protocols described in the bibliography for the dissolution of raw SF (LiBr 9.3M, CaCl2 50 wt.% or CaCl2:EtOH:H2O 1:2:8 in molar ratio). The integrity of regenerated SF in aqueous solution was analyzed by SDS-PAGE and different profiles of degradation were observed depending on the protocol used. This fact was found to affect also the aqueous solubility of the freeze dried protein. These different SFs were used to produce electrospun mats using SF solutions of SF 17 wt.% in 1,1,1,1',1',1'-hexafluoro-2-propanol (HFIP) and significant differences in fiber sizes, elongation and ultimate strength values were found. This work provides a global overview of the manner that different methods of SF extraction can affect the properties of electrospun SF-mats and consequently it should be considered depending on the use they are going to be made for. PMID:23498216

  2. 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

  3. Nano-composite of silk fibroin-chitosan/Nano ZrO2 for tissue engineering applications: Fabrication and morphology.

    Science.gov (United States)

    Teimouri, Abbas; Ebrahimi, Raheleh; Emadi, Rahmatollah; Beni, Batool Hashemi; Chermahini, Alireza Najafi

    2015-05-01

    A scaffold possessing certain desired features such as biodegradation, biocompatibility, and porous structure could serve as a template for tissue engineering. In the present study, silk fibroin (SF), chitosan (CS) and zirconia (Nano ZrO2) were all combined using the freeze drying technique to fabricate a bio-composite scaffold. The composite scaffold (SF/CS/Nano ZrO2) was characterized by SEM, XRD, TGA, BET and FT-IR studies. The scaffold was found to possess a porous nature with pore dimensions suitable for cell infiltration and colonization. The presence of zirconia in the SF/CS/Nano ZrO2 scaffold led to an increase in compressive strength and water uptake capacity while at the same time decreasing the porosity. Cytocompatibility of the SF/CS/Nano ZrO2 scaffold, assessed by MTT assay, revealed non-toxicity to the Human Gingival Fibroblast (HGF, NCBI: C-131). Thus, we suggest that SF/CS/Nano ZrO2 composite scaffold is a potential candidate to be used for tissue engineering. PMID:25709014

  4. Preparation and properties of calcium sulfate bone cement incorporated with silk fibroin and Sema3A-loaded chitosan microspheres

    Science.gov (United States)

    Wang, Peng; Pi, Bin; Wang, Jin-Ning; Zhu, Xue-Song; Yang, Hui-Lin

    2015-03-01

    To search for new bioactive materials which can be used as the substitute of bone repairing and drug carriers, Sema3A-loaded chitosan microspheres (SLCM) and silk fibroin (SF) were mixed with calcium sulfate cement (CSC). SEM, particle size analysis and swelling rate determination were performed to study properties of the microspheres. The drug loading, encapsulation efficiency and drug release rate were determined by ELISA. Microspheres with different SLCM weight contents (0.5%, 1% and 5%) were prepared to determine which one has the strongest mechanical properties and the appropriate setting time. It was revealed that CSC/SF/0.5SLCM has satisfactory mechanical properties, and its in vitro biocompatibility was assessed by MTS. Chitosan microspheres (5-18 ?m) were globular, the surface was smooth, and the swelling rate is (77.02 ± 5.57)%. With this formula, the setting time was increased with the addition of SLCM in CSC/SF, and the cumulative drug release rate is 44.62% in 28 d. XRD results demonstrate that the main component is calcium sulfate. Also it was found that CSC/SF/0.5SLCM supports the growth of MC3T3 cells. Thus the preparation of CSC/SF/0.5SLCM was reliable, and the products had good structures, physical properties and biocompatibility, appearing to be a promising bone substitute material.

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

    Science.gov (United States)

    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 morphology of the silk fibroin (SF)/poly(?-caprolactone) (PCL) nano/microfibrous composite scaffolds was investigated with field-emission scanning electron microscopy, while the mechanical and pore properties were assessed by measurement of tensile strength and mercury porosimetry. To assay cell proliferation, cell viability, and infiltration ability, human mesenchymal stem cells were seeded on the SF/PCL nano/microfibrous composite scaffolds. From in vivo tests, it was found that the bone-regenerating ability of SF/PCL nano/microfibrous composite scaffolds was closely associated with the nanofiber content in the composite scaffolds. In conclusion, this approach of controlling the nanofiber content in SF/PCL nano/microfibrous composite scaffolds could be useful in the design of novel scaffolds for tissue engineering. PMID:25624762

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

    International Nuclear Information System (INIS)

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

  7. 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.

  8. 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.

  9. A 13C NMR study on the structural change of silk fibroin from Samia cynthia ricini

    Science.gov (United States)

    Nakazawa, Yasumoto; Nakai, Toshihito; Kameda, Tsunenori; Asakura, Tetsuo

    1999-10-01

    The structural change of the liquid silk of Samia cynthia ricini was studied by 13C NMR spectroscopy. An unexpected emergence and disappearance of the resonance lines were observed, suggesting a gradual and monotonic slowdown of the overall molecular motions leading to molecular aggregation.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Lu?, 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...

  13. Tightly winding structure of sequential model peptide for repeated helical region in Samia cynthia ricini silk fibroin studied with solid-state NMR.

    Science.gov (United States)

    Nakazawa, Yasumoto; Bamba, Mie; Nishio, Satoko; Asakura, Tetsuo

    2003-04-01

    There are many kinds of silks from silkworms and spiders with different structures and properties, and thus, silks are suitable to study the structure-property relationship of fibrous proteins. Silk fibroin from a wild silkworm, Samia cynthia ricini, mainly consists of the repeated similar sequences by about 100 times where there are alternative appearances of the polyalanine (Ala)(12-13) region and the Gly-rich region. In this paper, a sequential model peptide, GGAGGGYGGDGG(A)(12)GGAGDGYGAG, which is a typical sequence of the silk fibroin, was synthesized, and the atomic-level conformations of Gly residues at the N- and C-terminal ends of the polyalanine region were determined as well as that of the central Ala residue using (13)C 2D spin diffusion solid-state nuclear magnetic resonance (NMR) under off-magic angle spinning. In the model peptide with alpha-helical conformation, the torsion angle of the central Ala residue, the 19th Ala, was determined to be (phi, psi) = (-60 degrees, -50 degrees ), which was a typical alpha-helical structure, but the torsion angles of two Gly residues, the 12th and 25th Gly residues, which are located at the N- and C-terminal ends of the polyalanine region, were determined to be (phi, psi) = (-70 degrees, -30 degrees ) and (phi, psi) = (-70 degrees, -20 degrees ), respectively. Thus, it was observed that the turns at both ends of polyalanine with alpha-helix conformation in the model peptide are tightly wound. PMID:12649423

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

    Directory of Open Access Journals (Sweden)

    Mahesh Kumar Sah

    2010-06-01

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

  15. Osteogenic differentiation of bone marrow mesenchymal stem cells on the collagen/silk fibroin bi-template-induced biomimetic bone substitutes.

    Science.gov (United States)

    Wang, Jianglin; Yang, Qin; Mao, Chuanbin; Zhang, Shengmin

    2012-11-01

    Biomimetic bone substitutes of collagen-silk fibroin/hydroxyapatite (COL-SF/HA) were synthesized via a bi-template-induced coassembly strategy. Collagen-hydroxyapatite (COL-HA) and silk fibroin-hydroxyapatite (SF-HA) served as controls were prepared with similar method. The osteogenic differentiation ability of bone marrow mesenchymal stem cells (BMSCs) seeded onto the resulting materials was evaluated both in vitro and in vivo. The results suggested that the bi-template-induced biomimetic substitutes were able to support the growth and proliferation of BMSCs. We further demonstrated that BMSCs were stimulated to differentiate into the osteoblast cell lineage by evaluating several specific osteogenic markers including staining of alkaline phosphate (ALP) and calcium nodular and expression of osteogenic genes of osteocalcin (OCN) and osteonectin (ONN). The rat femoral defect model was used to assess the aforementioned biomimetic bone substitutes combined with BMSCs in vivo. Histological analysis indicated that the bi-template material exhibited good biocompatibility and strong ability of the new bone formation in comparison with the control of single-template material in vivo. PMID:22700033

  16. 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)

  17. 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.

  18. Silk Coatings on PLGA and Alginate Microspheres for Protein Delivery

    OpenAIRE

    Wang, Xiaoqin; Wenk, Esther; Hu, Xiao; Castro, Guillermo R.; Meinel, Lorenz; Wang, Xianyan; Li, Chunmei; Merkle, Hans; Kaplan, David L.

    2007-01-01

    Bombyx mori silk fibroin self-assembles on surfaces to form ultrathin nanoscale coatings based on our prior studies using layer-by-layer deposition techniques driven by hydrophobic interactions between silk fibroin protein molecules. In the present study, polylactic-co-glycolic acid (PLGA) and alginate microspheres were used as substrates and coated with silk fibroin. The coatings were visualized by confocal laser scanning microscopy using fluorescein-labeled silk fibroin. On PLGA microsphere...

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

    International Nuclear Information System (INIS)

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

  20. 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

  1. Fabrication and Biocompatibility of Electrospun Silk Biocomposites

    OpenAIRE

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

    2011-01-01

    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 ...

  2. Peculiar salivary glands in a silk-producing mite Bakericheyla chanayi (Cheyletidae).

    Science.gov (United States)

    Filimonova, Svetlana A; Amosova, Ludmila I

    2015-07-01

    This is the first ultrastructural investigation of salivary glands in the family Cheyletidae. In both sexes of Bakericheyla chanayi, paired acinous salivary glands and tubular coxal glands were shown to be united into the common podocephalic system. The secretory portion of the salivary gland includes medial and lateral lobes composed of the five and two cells, respectively, with clearly distinct ultrastructure. The cytoplasm of the cells is occupied by the secretory granules containing fine fibrous material. The fine structure of both cell types suggest a proteinaceous nature of their secretions. A single central process extending from the apical face of each secretory cell passes through the common acinar cavity to enter the conducting duct. A pair of intercalary cells at the base of the conducting duct links it with the secretory portion of the gland. Extending towards the acinar cavity, protrusions of intercalary cells alternate the apical regions of the secretory cells and form with them highly-specialized contacts characterized by the apical network of microtubules and microfilaments. Two possible ways of secretion are suggested: 1) exocytosis into the acinar cavity and 2) direct passage via the central processes. The detection of axon profiles in the gland body suggests a neural control for the glandular cell function. In tritonymphs, neither secretion nor large lateral lobe cells were observed up to the pharate stage when the lateral lobe undergoes rapid differentiation. The arrangement of the acinous gland is compared to that of other arthropods. Its composition appears to be close to the class three of insect glands. The involvement of the lateral lobe cells in silk production is discussed. J. Morphol. 276:772-786, 2015. © 2015 Wiley Periodicals, Inc. PMID:25704005

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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

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

    Directory of Open Access Journals (Sweden)

    Jiang J

    2014-09-01

    Full Text Available Jia Jiang,1,2 Fang Wan,1 Jianjun Yang,1 Wei Hao,3 Yaxian Wang,3 Jinrong Yao,3 Zhengzhong Shao,3 Peng Zhang,1 Jun Chen,1 Liang Zhou,4 Shiyi Chen11Fudan University Sports Medicine Center and Department of Sports Medicine and Arthroscopy Surgery, Huashan Hospital, 2State Key Laboratory of Molecular Engineering of Polymers, 3Laboratory of Advanced Materials, National Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, People’s Republic of China; 4Department of Forest Products, Anhui Agricultural University, Hefei Anhui Province, People’s Republic of ChinaBackground: Application of artificial ligament in anterior cruciate ligament reconstruction is one of the research focuses of sports medicine but the biological tendon–bone healing still remains a problem. The preliminary study of hydroxyapatite (HAP coating on the polyethylene terephthalate (PET surface could effectively induce the osteoblast differentiation, but the tendon–bone healing was still not stable. As a green synthesis process, the biomimetic mineralization can simulate the natural bone growth in vitro and in vivo.Methods: HAP crystals were grown under the guide of silk fibroin (SF PET surface by biomimetic route. Several techniques including scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy were utilized for proving the introduction of both SF and HAP. The viability and osseointegration of bone marrow stromal cells on the surface of three kinds of ligament, including PET group (non-coating group, PET+SF group (SF-coating group, and PET+SF+HAP group (combined HAP- and SF-coating group, were analyzed by CCK-8 assays and alkaline phosphatase (ALP detection. Seventy-two mature male New Zealand rabbits were randomly divided into three groups. Among them, 36 rabbits were sacrificed for mechanical testing, and histological examination for the others. Results: The SF and SF+HAP were successfully coated on the surface of PET fiber. The CCK-8 assay showed that the cell proliferation on PET+SF+HAP group was better than the other two groups from 24 to 120 hours. After 14 days of culture, the cells in the PET+SF+HAP group delivered higher levels of ALP than the other two groups. After 3 days of culture, the expression level of integrin ?1 in the PET+SF+HAP group and PET+SF group were higher than in the PET group. The mean load to failure and the stiffness value of the PET+SF+HAP group were both higher than the other two groups. Hematoxylin and eosin staining showed that new bone tissue formation was only found in the PET+SF+HAP group 8 weeks postoperatively. Masson staining showed that in the PET+SF+HAP group 8 weeks postoperatively, the PET fibers were almost completely encircled by collagen. Histomorphometric analysis showed that the width of the graft–bone interface in the PET+SF+HAP group was narrower than that in the other two groups 4 and 8 weeks postoperatively. The mRNA level of BMP-7 in the PET+SF+HAP groups was significantly higher than those in the other two groups 4 and 8 weeks postoperatively.Conclusion: The study showed that the combined SF and HAP coating by biomimetic route on the surface of PET artificial ligament could induce graft osseointegration in the bone tunnel, providing theoretical and experimental foundation for manufacturing novel artificial ligaments meeting the clinical needs.Keywords: biomineralization, tendon–bone healing, ligament reconstruction

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

    Science.gov (United States)

    Jiang, Jia; Wan, Fang; Yang, Jianjun; Hao, Wei; Wang, Yaxian; Yao, Jinrong; Shao, Zhengzhong; Zhang, Peng; Chen, Jun; Zhou, Liang; Chen, Shiyi

    2014-01-01

    Background Application of artificial ligament in anterior cruciate ligament reconstruction is one of the research focuses of sports medicine but the biological tendon–bone healing still remains a problem. The preliminary study of hydroxyapatite (HAP) coating on the polyethylene terephthalate (PET) surface could effectively induce the osteoblast differentiation, but the tendon–bone healing was still not stable. As a green synthesis process, the biomimetic mineralization can simulate the natural bone growth in vitro and in vivo. Methods HAP crystals were grown under the guide of silk fibroin (SF) PET surface by biomimetic route. Several techniques including scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy were utilized for proving the introduction of both SF and HAP. The viability and osseointegration of bone marrow stromal cells on the surface of three kinds of ligament, including PET group (non-coating group), PET+SF group (SF-coating group), and PET+SF+HAP group (combined HAP- and SF-coating group), were analyzed by CCK-8 assays and alkaline phosphatase (ALP) detection. Seventy-two mature male New Zealand rabbits were randomly divided into three groups. Among them, 36 rabbits were sacrificed for mechanical testing, and histological examination for the others. Results The SF and SF+HAP were successfully coated on the surface of PET fiber. The CCK-8 assay showed that the cell proliferation on PET+SF+HAP group was better than the other two groups from 24 to 120 hours. After 14 days of culture, the cells in the PET+SF+HAP group delivered higher levels of ALP than the other two groups. After 3 days of culture, the expression level of integrin ?1 in the PET+SF+HAP group and PET+SF group were higher than in the PET group. The mean load to failure and the stiffness value of the PET+SF+HAP group were both higher than the other two groups. Hematoxylin and eosin staining showed that new bone tissue formation was only found in the PET+SF+HAP group 8 weeks postoperatively. Masson staining showed that in the PET+SF+HAP group 8 weeks postoperatively, the PET fibers were almost completely encircled by collagen. Histomorphometric analysis showed that the width of the graft–bone interface in the PET+SF+HAP group was narrower than that in the other two groups 4 and 8 weeks postoperatively. The mRNA level of BMP-7 in the PET+SF+HAP groups was significantly higher than those in the other two groups 4 and 8 weeks postoperatively. Conclusion The study showed that the combined SF and HAP coating by biomimetic route on the surface of PET artificial ligament could induce graft osseointegration in the bone tunnel, providing theoretical and experimental foundation for manufacturing novel artificial ligaments meeting the clinical needs. PMID:25302023

  10. Effect of Mechanical Deformation on the Structure of Regenerated Bombyx mori Silk Fibroin Films as Revealed Using Raman and Infrared Spectroscopy.

    Science.gov (United States)

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

    2015-06-01

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

  11. 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.

  12. 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 ...

  13. Effect of Processing on Silk-Based Biomaterials: Reproducibility and Biocompatibility

    OpenAIRE

    Wray, Lindsay S.; Hu, Xiao; Gallego, Jabier; Georgakoudi, Irene; Omenetto, Fiorenzo G; Schmidt, Daniel; Kaplan, David L.

    2011-01-01

    Silk fibroin has been successfully used as a biomaterial for tissue regeneration. In order to prepare silk fibroin biomaterials for human implantation a series of processing steps are required to purify the protein. Degumming to remove inflammatory sericin is a crucial step related to biocompatibility and variability in the material. Detailed characterization of silk fibroin degumming is reported. The degumming conditions significantly affected cell viability on the silk fibroin material and ...

  14. Analysis of Transcripts Expressed in One-Day-Old Larvae and Fifth Instar Silk Glands of Tasar Silkworm, Antheraea mylitta

    OpenAIRE

    Ghosh, Ananta K.; Swati Bhattacharyya; Aravind Venugopalan; Suvankar Ghorai; Sobhan Roy; Goel, Sagar I.; Samita Maity

    2010-01-01

    Antheraea mylitta is one of the wild nonmulberry silkworms, which produces tasar silk. An EST project has been undertaken to understand the gene expression profile of A. mylitta silk gland. Two cDNA libraries, one from the whole bodies of one-day-old larvae and the other from the silkglands of fifth instar larvae, were constructed and sequenced. A total of 2476 good-quality ESTs (1239 clones) were obtained and grouped into 648 clusters containing 390 contigs and 258 singletons to represent 4...

  15. 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

  16. Silk fibroin/sodium alginate composite nano-fibrous scaffold prepared through thermally induced phase-separation (TIPS) method for biomedical applications.

    Science.gov (United States)

    Zhang, Haiping; Liu, Xiaotian; Yang, Mingying; Zhu, Liangjun

    2015-10-01

    To mimic the natural fibrous structure of the tissue extracellular matrix, a nano-fibrous silk fibroin (SF)/sodium alginate (SA) composite scaffold was fabricated by a thermally-induced phase-separation method. The effects of SF/SA ratio on the structure and the porosity of the composite scaffolds were examined. Scanning electron microscopy and porosity results showed that the 5SF/1SA and 3SF/1SA scaffolds possessed an excellent nano-fibrous structure and a porosity of more than 90%. Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry results indicated the physical interaction between SF and SA molecules and their good compatibility in the 5SF/1SA and 3SF/1SA scaffolds, whereas they showed less compatibility in the 1SF/1SA scaffold. Cell culture results showed that MG-63 cells can attach and grow well on the surface of the SF/SA scaffolds. The nano-fibrous SF/SA scaffold can be potentially used in tissue engineering. PMID:26117733

  17. 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%.

  18. Removal of copper ions from aqueous solution by adsorption onto novel polyelectrolyte film-coated nanofibrous silk fibroin non-wovens

    Science.gov (United States)

    Zhou, Weitao; Huang, Haitao; Du, Shan; Huo, Yingdong; He, Jianxin; Cui, Shizhong

    2015-08-01

    In this approach, polyelectrolyte film-coated nanofibrous silk fibroin (SF) nonwovens were prepared from the alternate deposition of positively charged polyethylenimine (PEI) and negatively charged SF using electrostatic layer-by-layer (LBL) self-assembled technology. The composite membranes were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectrometer. The SF-PEI multilayer-assembled nanofibers (less than five layers) were fine and uniform with the fiber diameter from 400 nm to 600 nm, and had very large surface area and high porosity (more than 70%). The amino groups of PEI were proved to be deposited onto SF nonwovens, which granted the coated nonwovens with potential applicability for copper ions adsorption. The PEI films coated SF substrate showed much higher copper ions adsorption capacity than that of ethanol treated SF nanofibers. Adding the number of PEI coated could enhance the Cu2+ adsorption capacity significantly. The maximum milligrams per gram of copper ions adsorbed reached 59.7 mg/g when the SF substrate was coated with 5 bilayers of SF-PEI. However, the copper ions adsorption capacity had no obvious change as the number of PEI continued to increase. These results suggest potential for PEL film-coated nanofibrous nonwovens as a new adsorbent for metal ions.

  19. 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

  20. 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

  1. Change in silk protein by radiation

    International Nuclear Information System (INIS)

    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)

  2. 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

  3. The secretion process of liquid silk with nanopillar structures from Stenopsyche marmorata (Trichoptera: Stenopsychidae).

    Science.gov (United States)

    Hatano, Tomohiro; Nagashima, Takayuki

    2015-01-01

    Stenopsyche marmorata larvae spin underwater adhesive silk for constructing nests and capture nets. The silk can be divided into fiber and adhesive regions, according to their function. The silk fiber region has a two-layer structure: a core layer situated at the center of the fiber and S. marmorata fibroin, the major component of the silk. In the anterior part of the anterior silk gland, the morphological characteristics suggest that the silk insolubilization leading to fibrillation occurs by luminal pH neutralization. The adhesive region is composed of three layers: the outermost (OM), B, and C layers. On the B layer, coated with the OM layer, numerous nano-order pillar structures (nanopillar structures) are located at regular intervals. A nanopillar structure is approximately 40?nm in diameter and 125?nm in length. The precursor materials of the nanopillar structure are electron-dense globules of approximately 25?nm in diameter that are located in the A layer of the lumen of the middle silk gland. The precursor globules autonomously connect to one another on the B layer when the liquid silk is transported to the lumen of the bulbous region. The nanopillar structures probably contribute to the strong underwater adhesion of S. marmorata silk. PMID:25783626

  4. Change of share of crystal parts of fibroin under action of antioxidant

    International Nuclear Information System (INIS)

    In the work it is established, that at introduction of antioxidant N((-3.5-di-tributyl-4-hydroxyphenyl) salicyl, fibroin mechanical durability structure of increases and natural silk fibroin stability to external influences raises

  5. Histochemical and ultrastructural evidence of lipid secretion by the silk gland of the sugarcane borer Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) / Evidências histoquímicas e ultra-estruturais de secreção sipídica pela glândula da seda da broca da cana-de-açúcar, Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae)

    Scientific Electronic Library Online (English)

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

    2007-10-01

    Full Text Available A glândula da seda de larvas de Lepidoptera é responsável pela produção da seda usada na construção do casulo ou do abrigo. A secreção de fibroína e sericina pelas diferentes regiões da glândula da seda está bem estabelecida. Existem poucos trabalhos tentando identificar componentes lipídicos na sec [...] reção de seda de insetos, embora a presença desse componente contribua para a resistência da seda a ambiente úmidos. Este estudo teve como objetivo identificar a presença de componente lipídico na secreção da glândula da seda de larvas de Diatraea saccharalis (Fabricius), bem como caracterizar a região glandular responsável pela secreção. A glândula da seda foi submetida a procedimentos histoquímicos para detecção de lipídeos e convencionalmente preparada para análise ultra-estrutural. Gotas lipídicas foram histoquimicamente detectadas no citoplasma apical de células da região anterior e no lúmen, entre os microvilos. A análise ultra-estrutural da região anterior mostrou material lipídico, visualizado como figuras do tipo mielina dentro do complexo de Golgi vesicular e nos glóbulos secretores apicais, misturados com sericina; material semelhante foi observado dentro do lúmen, adjacente aos microvilos. Nenhum componente secretor lipídico foi detectado nas células ou no lúmen da região posterior. Os resultados sugerem que a seda produzida pela D. saccharalis tem, pelo menos, um discreto componente lipídico, que é secretado pela região anterior, junto com a sericina. Abstract in english The silk gland in Lepidoptera larvae is responsible for the silk production used for shelter or cocoon construction. The secretion of fibroin and sericin by the different silk gland regions are well established. There are few attempts to detect lipid components in the insect silk secretion, although [...] the presence of such element may contribute to the resistance of the shelter to wet environment. This study characterizes the glandular region and detects the presence of lipid components in the secretion of the silk gland of Diatraea saccharalis(Fabricius). The silk gland was submitted to histochemical procedure for lipid detection or conventionally prepared for ultrastructural analyses. Lipid droplets were histochemically detected in both the apical cytoplasm of cell of the anterior region and in the lumen among the microvilli. Ultrastructural analyses of the anterior region showed lipid material, visualized as myelin-like structures within the vesicular Golgi complex and in the apical secretory globules, mixed up with the sericin; similar material was observed into the lumen, adjacent to the microvilli. Lipids were not detected in the cells neither in the lumen of the posterior region. Our results suggest that the silk produced by D. saccharalis has a minor lipid content that is secreted by the anterior region together with the sericin.

  6. 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...

  7. Three-layered scaffolds for artificial esophagus using poly(?-caprolactone) nanofibers and silk fibroin: An experimental study in a rat model.

    Science.gov (United States)

    Chung, Eun-Jae; Ju, Hyung Woo; Park, Hyun Jung; Park, Chan Hum

    2015-06-01

    The purpose of this study was to determine the feasibility of an artificial esophagus using a three-layered poly(?-caprolactone) (PCL)-silk fibroin (SF) scaffold in a rat model. The artificial esophagus was a three-layered, hybrid-type prosthesis composed of an outer and inner layer of PCL with a middle layer of SF. After depositing the inner layer of the PCL scaffold by electrospinning, the lyophilized middle SF layer was created. The outer layer of PCL was produced following the same procedure used to make the inner PCL layer. Eleven rats were anesthetized using inhaled anesthesia. Circumferential defects of the cervical esophagus (n=11) were created and reconstructed. Groups of rats were sacrificed after the 1st and 2nd weeks. Three rats died of an esophageal fistula and wound infection. No gross evidence of a fistula, perforation, abscess formation, seroma accumulation, or surrounding soft-tissue necrosis was observed in the other rats sacrificed after the 1st and 2nd weeks. The artificial esophagus constructs produced complete healing of the circumferential defects by the 2nd week. The composition of the three-layered artificial esophagus was confirmed histologically to have an outer and inner layer of PCL and a middle layer of SF. The fusion of the PCL-SF scaffold and the regenerative tissue remained intact. Our study proposes a more practical experimental model for studying a three-layered PCL-SF scaffold in the esophagus. However, further studies on circumferential defect reconstruction in a rat model are still required. PMID:25294581

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

    Directory of Open Access Journals (Sweden)

    Yu Liu

    2014-04-01

    Full Text Available Polyethylenimine (PEI has attracted much attention as a DNA condenser, but its toxicity and non-specific targeting limit its potential. To overcome these limitations, Antheraea pernyi silk fibroin (ASF, a natural protein rich in arginyl-glycyl-aspartic acid (RGD peptides that contains negative surface charges in a neutral aqueous solution, was used to coat PEI/DNA complexes to form ASF/PEI/DNA ternary complexes. Coating these complexes with ASF caused fewer surface charges and greater size compared with the PEI/DNA complexes alone. In vitro transfection studies revealed that incorporation of ASF led to greater transfection efficiencies in both HEK (human embryonic kidney 293 and HCT (human colorectal carcinoma 116 cells, albeit with less electrostatic binding affinity for the cells. Moreover, the transfection efficiency in the HCT 116 cells was higher than that in the HEK 293 cells under the same conditions, which may be due to the target bonding affinity of the RGD peptides in ASF for integrins on the HCT 116 cell surface. This result indicated that the RGD binding affinity in ASF for integrins can enhance the specific targeting affinity to compensate for the reduction in electrostatic binding between ASF-coated PEI carriers and cells. Cell viability measurements showed higher cell viability after transfection of ASF/PEI/DNA ternary complexes than after transfection of PEI/DNA binary complexes alone. Lactate dehydrogenase (LDH release studies further confirmed the improvement in the targeting effect of ASF/PEI/DNA ternary complexes to cells. These results suggest that ASF-coated PEI is a preferred transfection reagent and useful for improving both the transfection efficiency and cell viability of PEI-based nonviral vectors.

  9. 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.

  10. A vascular patch prepared from Thai silk fibroin and gelatin hydrogel incorporating simvastatin-micelles to recruit endothelial progenitor cells.

    Science.gov (United States)

    Thitiwuthikiat, Piyanuch; Ii, Masaaki; Saito, Takashi; Asahi, Michio; Kanokpanont, Sorada; Tabata, Yasuhiko

    2015-04-01

    Delayed re-endothelialization is one of the major disadvantages in synthetic vascular grafts, especially in small-diameter grafts (inner diameter fibroin/gelatin with gelatin hydrogel incorporating simvastatin-micelles (SM) for sustained release of simvastatin to recruit circulation EPCs. To enhance simvastatin solubility, simvastatin was entrapped in micelles of l-lactic acid oligomer-grafted gelatin. The drug loading efficiency was at 4.1 ± 0.5??g/mg micelles. SM had a chemoattractive effect on EPCs comparable to nonmodified simvastatin. Gelatin hydrogel incorporating SM at 100??M of simvastatin (GSM100) could enhance in vitro EPC activities of adhesion and proliferation. In vitro results showed the initial cell adhesion of 86%, specific growth rate of 15.33×10(-3) h(-1), and population doubling time of 46.21?h. In vivo implantation of the patches incorporating SM significantly increased the recruitment of circulating EPCs. From the results of immunofluorescence staining, they demonstrated the complete re-endothelialization on the implanted patches containing SM at 2 weeks after implantation in rat carotid arteries. The gelatin hydrogel incorporating SM could be an effective inner layer of multifunctional vascular grafts to accelerate re-endothelialization in vascular tissue engineering. PMID:25517108

  11. 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, K T; 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

  12. 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

  13. 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

  14. Structure determination of a peptide model of the repeated helical domain in Samia cynthia ricini silk fibroin before spinning by a combination of advanced solid-state NMR methods.

    Science.gov (United States)

    Nakazawa, Yasumoto; Asakura, Tetsuo

    2003-06-18

    Fibrous proteins unlike globular proteins, contain repetitive amino acid sequences, giving rise to very regular secondary protein structures. Silk fibroin from a wild silkworm, Samia cynthia ricini, consists of about 100 repeats of alternating polyalanine (poly-Ala) regions of 12-13 residues in length and Gly-rich regions. In this paper, the precise structure of the model peptide, GGAGGGYGGDGG(A)(12)GGAGDGYGAG, which is a typical repeated sequence of the silk fibroin, was determined using a combination of three kinds of solid-state NMR studies; a quantitative use of (13)C CP/MAS NMR chemical shift with conformation-dependent (13)C chemical shift contour plots, 2D spin diffusion (13)C solid-state NMR under off magic angle spinning and rotational echo double resonance. The structure of the model peptide corresponding to the silk fibroin structure before spinning was determined. The torsion angles of the central Ala residue, Ala(19), in the poly-Ala region were determined to be (phi, psi) = (-59 degrees, -48 degrees ) which are values typically associated with alpha-helical structures. However, the torsion angles of the Gly(25) residue adjacent to the C-terminal side of the poly-Ala chain were determined to be (phi, psi) = (-66 degrees, -22 degrees ) and those of Gly(12) and Ala(13) residues at the N-terminal of the poly-Ala chain to be (phi, psi) = (-70 degrees, -30 degrees ). In addition, REDOR experiments indicate that the torsion angles of the two C-terminal Ala residues, Ala(23) and Ala(24), are (phi, psi) = (-66 degrees, -22 degrees ) and those of N-terminal two Ala residues, Ala(13) and Ala(14) are (phi, psi) = (-70 degrees, -30 degrees ). Thus, the local structure of N-terminal and C-terminal residues, and also the neighboring residues of alpha-helical poly-Ala chain in the model peptide is a more strongly wound structure than found in typical alpha-helix structures. PMID:12797796

  15. Influence factors analysis on the formation of silk I structure.

    Science.gov (United States)

    Ming, Jinfa; Pan, Fukui; Zuo, Baoqi

    2015-04-01

    Regenerated silk fibroin aqueous solution was used to study the crystalline structure of Bombyx mori silk fibroin in vitro. By controlling environmental conditions and concentration of silk fibroin solution, it provided a means for the direct preparing silk I structure and understanding the details of silk fibroin molecules interactions in formation process. In this study, silk fibroin molecules were assembled to form random coil at low concentration of solution and then, as the concentration increases, were converted to silk I at 55% relative humidity (RH). At the same time, the structure of silk fibroin forming below 45 °C was mostly in silk I. A partial ternary phase diagram of temperature-humidity-concentration was constructed based on the results. The results showed silk I structure could be controlled by adjusting the external environmental conditions. The enhanced control over silk I structure, as embodied in phase diagram, could potentially be utilized to understand the molecular chain conformation of silk I in further research work. PMID:25677178

  16. How is a silk fiber made?.

    Czech Academy of Sciences Publication Activity Database

    Sehnal, František; Žurovec, Michal; Yonemura, N.

    Khon Kaen : International Society for Wild Silkmoths, 2004. s. 24-25. [International Workshop on Wild Silkmoths and Silks "Current Advances and Development in Wild Silkmoths and Tropical Bombyx Silks". 11.10.2004-14.10.2004, Khon Kaen] Keywords : H- fibroin * silk Subject RIV: ED - Physiology

  17. 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

  18. Silk structure and degradation.

    Science.gov (United States)

    Liu, Bin; Song, Yu-Wei; Jin, Li; Wang, Zhi-Jian; Pu, De-Yong; Lin, Shao-Qiang; Zhou, Chan; You, Hua-Jian; Ma, Yan; Li, Jin-Min; Yang, Li; Sung, K L Paul; Zhang, Yao-Guang

    2015-07-01

    To investigate the structure of silk and its degradation properties, we have monitored the structure of silk using scanning electron microscopy and frozen sections. Raw silk and degummed raw silk were immersed in four types of degradation solutions for 156 d to observe their degradation properties. The subcutaneous implants in rats were removed after 7, 14, 56, 84, 129, and 145 d for frozen sectioning and subsequent staining with hematoxylin and eosin (H.E.), DAPI, Beta-actin and Collagen I immunofluorescence staining. The in vitro weight loss ratio of raw silk and degummed raw silk in water, PBS, DMEM and DMEM containing 10% FBS (F-DMEM) were, respectively, 14%/11%, 12.5%/12.9%, 11.1%/14.3%, 8.8%/11.6%. Silk began to degrade after 7 d subcutaneous implantation and after 145 d non-degraded silk was still observed. These findings suggest the immunogenicity of fibroin and sericin had no essential difference. In the process of in vitro degradation of silk, the role of the enzyme is not significant. The in vivo degradation of silk is related to phagocytotic activity and fibroblasts may be involved in this process to secrete collagen. This study also shows the developing process of cocoons and raw silk. PMID:25982316

  19. 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...

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

    Science.gov (United States)

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

    2014-11-10

    Dragline silk has been proposed to contain two main protein constituents, MaSp1 and MaSp2. However, the mechanical properties of synthetic spider silks spun from recombinant MaSp1 and MaSp2 proteins have yet to approach natural fibers, implying the natural spinning dope is missing critical factors. Here we report the discovery of novel molecular constituents within the spinning dope that are extruded into dragline silk. Protein studies of the liquid spinning dope from the major ampullate gland, coupled with the analysis of dragline silk fibers using mass spectrometry, demonstrate the presence of a new family of low-molecular-weight cysteine-rich proteins (CRPs) that colocalize with the MA fibroins. Expression of the CRP family members is linked to dragline silk production, specifically MaSp1 and MaSp2 mRNA synthesis. Biochemical data support that CRP molecules are secreted into the spinning dope and assembled into macromolecular complexes via disulfide bond linkages. Sequence analysis supports that CRP molecules share similarities to members that belong to the cystine slipknot superfamily, suggesting that these factors may have evolved to increase fiber toughness by serving as molecular hubs that dissipate large amounts of energy under stress. Collectively, our findings provide molecular details about the components of dragline silk, providing new insight that will advance materials development of synthetic spider silk for industrial applications. PMID:25259849

  1. 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.

  2. Silk scaffolds with tunable mechanical capability for cell differentiation.

    Science.gov (United States)

    Bai, Shumeng; Han, Hongyan; Huang, Xiaowei; Xu, Weian; Kaplan, David L; Zhu, Hesun; Lu, Qiang

    2015-07-01

    Bombyx mori silk fibroin is a promising biomaterial for tissue regeneration and is usually considered an "inert" material with respect to actively regulating cell differentiation due to few specific cell signaling peptide domains in the primary sequence and the generally stiffer mechanical properties due to crystalline content formed in processing. In the present study, silk fibroin porous 3D scaffolds with nanostructures and tunable stiffness were generated via a silk fibroin nanofiber-assisted lyophilization process. The silk fibroin nanofibers with high ?-sheet content were added into the silk fibroin solutions to modulate the self-assembly, and to directly induce water-insoluble scaffold formation after lyophilization. Unlike previously reported silk fibroin scaffold formation processes, these new scaffolds had lower overall ?-sheet content and softer mechanical properties for improved cell compatibility. The scaffold stiffness could be further tuned to match soft tissue mechanical properties, which resulted in different differentiation outcomes with rat bone marrow-derived mesenchymal stem cells toward myogenic and endothelial cells, respectively. Therefore, these silk fibroin scaffolds regulate cell differentiation outcomes due to their mechanical features. PMID:25858557

  3. Radiation degradation of silk protein

    International Nuclear Information System (INIS)

    Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl2/C2H5OH/H2O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

  4. Radiation degradation of silk protein

    International Nuclear Information System (INIS)

    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 (CaCl2/C2H5OH/H2O = 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)

  5. 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

  6. Development of an enzyme-linked-immunosorbent-assay technique for accurate identification of poorly preserved silks unearthed in ancient tombs.

    Science.gov (United States)

    Zheng, Qin; Wu, Xiaofeng; Zheng, Hailing; Zhou, Yang

    2015-05-01

    We report the preparation of a specific fibroin antibody and its use for the identification of unearthed ancient silk relics. Based on the 12-amino-acid repeat sequence "GAGAGSGAGAGS", which is found in fibroin of the silkworm Bombyx mori, a specific antibody against fibroin was prepared in rabbits through peptide synthesis and carrier-protein coupling. This antibody was highly specific for fibroin found in silk. Using this antibody we have successfully identified four silk samples from different time periods. Our results reveal, for the first time, a method capable of detecting silk from a few milligrams of archaeological fabric that has been buried for thousands of years, confirming that the ancient practice of wearing silk products while praying for rebirth dated back to at least 400 BCE. This method also complements current approaches in silk detection, especially for the characterization of poorly preserved silks, promoting the investigation of silk origins and of ancient clothing cultures. PMID:25804731

  7. Chitosan silk-based three-dimensional scaffolds containing gentamicin-encapsulated calcium alginate beads for drug administration and blood compatibility.

    Science.gov (United States)

    Mehta, Abijeet Singh; Singh, Brijesh K; Singh, Nandita; Archana, D; Snigdha, Kirti; Harniman, Robert; Rahatekar, Sameer S; Tewari, R P; Dutta, P K

    2015-04-01

    In the present study gentamicin was encapsulated within calcium alginate beads and incorporated into porous chitosan, gelatin, double-hybrid silk fibroin, chitosan/gelatin and double-hybrid silk fibroin/chitosan scaffolds. Physiochemical, morphological and biological properties of fabricated amenable model systems were evaluated, revealing hemocompatible nature of double-hybrid silk fibroin/chitosan and double-hybrid silk fibroin scaffolds of hemolysis %85%. Fourier transform infrared results confirmed the blend formation and scanning electron microscope images showed good interconnectivity. Double-hybrid silk fibroin/chitosan-blended scaffold shows higher compressive strength and compressive modulus than other fabricated scaffolds. A comparative drug release profile of fabricated scaffolds revealed that double-hybrid silk fibroin/chitosan scaffold is a pertinent model system because of its prolonged drug release, optimal hemocompatability and high compressive modulus. PMID:25492055

  8. 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

  9. Silk inverse opals

    Science.gov (United States)

    Kim, Sunghwan; Mitropoulos, Alexander N.; Spitzberg, Joshua D.; Tao, Hu; Kaplan, David L.; Omenetto, Fiorenzo G.

    2012-12-01

    Periodic nanostructures provide the facility to control and manipulate the flow of light through their lattices. Three-dimensional photonic crystals enable the controlled design of structural colour, which can be varied by infiltrating the structure with different (typically liquid) fillers. Here, we report three-dimensional photonic crystals composed entirely of a purified natural protein (silk fibroin). The biocompatibility of this protein, as well as its favourable material properties and ease of biological functionalization, present opportunities for otherwise unattainable device applications such as bioresorbable integration of structural colour within living tissue or lattice functionalization by means of organic and inorganic material doping. We present a silk inverse opal that demonstrates a pseudo-photonic bandgap in the visible spectrum and show its associated structural colour beneath biological tissue. We also leverage silk's facile dopability to manufacture a gold nanoparticle silk inverse opal and demonstrate patterned heating mediated by enhancement of nanoparticle absorption at the band-edge frequency of the photonic crystal.

  10. Biomimetic magnetic silk scaffolds.

    Science.gov (United States)

    Samal, Sangram K; Dash, Mamoni; Shelyakova, Tatiana; Declercq, Heidi A; Uhlarz, Marc; Bañobre-López, Manuel; Dubruel, Peter; Cornelissen, Maria; Herrmannsdörfer, Thomas; Rivas, Jose; Padeletti, Giuseppina; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L; Dediu, V Alek

    2015-03-25

    Magnetic silk fibroin protein (SFP) scaffolds integrating magnetic materials and featuring magnetic gradients were prepared for potential utility in magnetic-field assisted tissue engineering. Magnetic nanoparticles (MNPs) were introduced into SFP scaffolds via dip-coating methods, resulting in magnetic SFP scaffolds with different strengths of magnetization. Magnetic SFP scaffolds showed excellent hyperthermia properties achieving temperature increases up to 8 °C in about 100 s. The scaffolds were not toxic to osteogenic cells and improved cell adhesion and proliferation. These findings suggest that tailored magnetized silk-based biomaterials can be engineered with interesting features for biomaterials and tissue-engineering applications. PMID:25734962

  11. Intrinsically Functionalized Silk (Bombyx Mori)

    OpenAIRE

    A?berg, 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...

  12. Microrheology of non mulberry silk varieties by optical tweezer and video microscopy based techniques

    OpenAIRE

    Yogesha; A, Raghu; N, Siddaraju G; G. Subramanya; R, Somashekar; Ananthamurthy, Sharath

    2011-01-01

    We have carried out a comparative study of the microrheological properties of silk fibroin solutions formed from a variety of silks indigenous to the Indian subcontinent. We present the measured viscoelastic moduli of Tasar silk fibroin solution using both a single and dual optical tweezer at 0.16% and 0.25% (w/v). The bandwidth of the measurements carried out using optical tweezers is extended down to the lower frequency regime by a video microscopy measurement. Further, we...

  13. Production of fine powder from silk by radiation

    International Nuclear Information System (INIS)

    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)

  14. Characteristics of Silk Fiber with and without Sericin Component: A Comparison between Bombyx mori and Philosamia ricini Silks

    Directory of Open Access Journals (Sweden)

    S. Prasong

    2009-01-01

    Full Text Available The study aimed to investigate and compare some characteristics of Bombyx mori and Eri (Philosamia ricini silks in different forms; with and without sericin. The protein contents were measured and find out the composition of the silk fibroin and sericin proteins by Lowry method. The secondary structure and thermal behavior of all kind of silk were determined by FT-IR and TA instrument, respectively. The B. mori composed of more amount of sericin content than that of Eri silk. FT-IR spectra indicated that the Eri silk was similar profile of silk with and without sericin, whereas B. mori silk showed dramatically differed. With sericin, B. mori composed of higher ratio random coil and ?-helix structures than ?-structure. With thermogravimetric analysis, both B. mori and Eri silk fibers without sericin showed higher stability than that silk fiber with sericin. This is due to the crystalline region of hydrophobic amino acid composed in the fibroin core protein. The differential scanning calorimetry thermogram of B. mori was differed from Eri silk fiber. It is a promising that characteristics of the silk were influenced by both silk components and silk varieties.

  15. Biomedical Applications of Mulberry Silk and its Proteins: A Review

    Science.gov (United States)

    Nivedita, S.; Sivaprasad, V.

    2014-04-01

    Silk is a natural fibre used mainly for aesthetic purposes. It has also been used for making surgical sutures for centuries. The recent rediscovery of silk's biological properties have led to new areas of research and utilization in cosmetic, health and medical fields. The silk proteins, fibroin and sericin are processed into biomaterials because of bio-compatibility, bio-degradability, excellent mechanical properties, thermo tolerance and UV protective properties. Silk proteins could be obtained as pure liquids and regenerated in different forms suitable for tissue engineering applications. This paper presents some of the biomedical products and biomaterials made from native, degraded and regenerated silk and their fabrication techniques.

  16. Characterization of Partial Coding Region Fibroin Gene on Wild Silkmoth Cricula trifenestrata Helfer (Lepidoptera: Saturniidae

    Directory of Open Access Journals (Sweden)

    Suriana

    2011-04-01

    Full Text Available The study was conducted to characterize coding region of wild silkmoth C. trifenestrata partial fibroin gene, and detect these gene potential as molecular marker. A total of six larvae C. trifenestrata were collected from Bogor, Purwakarta and Bantul Regency. Genomic DNA was extracted from silk gland individual larvae, then amplified by PCR method and sequenced. DNA sequenced result was 986 nucleotide partial fibroin gene of C. trifenestrata, which are comprising complete coding region of first exon (42 nucleotide, an intron (113 nucleotide, and partial of second was exon (831 nucleotide. Only coding region was characterized. Results showed that first exon very conserved in C. trifenestrata. These gene consisted of 31%, thymine, 28% guanine, 21% cytosine, and 19% adenine. Cytosine and thymine (sites of 25th and 35th respectively were marker for C. trifenestrata species. The first exon encoding 14 amino acids. Valine amino acid (12th site was marker to the species C. trifenestrata. The partial second exon consisted of guanine (32.7%, alanine (26.5%, thymine (21% and cytosine (19.7%. These region encoded 277 amino acids, which were dominated by the alanine (27.8% and glycine (21.66%. Alanine formed polyalanine sequence with different motifs namely: AAAAAAASS, AAAAAAAAAAAGSSG, AAAAAAAAAAAAGSGTGFGGYDS, AAAAAAAAAAGSSGRGGYDGVDGGYGSGSS, and AAAAAAAAAAAAGSSGRGLGGYDGWVDDGYGSGSGS.

  17. Silk is more than traditional textile fiber.

    Czech Academy of Sciences Publication Activity Database

    Sehnal, František; Žurovec, Michal

    ?eské Bud?jovice : Institute of Entomology, 2002. s. 25. [Czech Republic - Taiwan New Entomological Techniques Cooperation and Development Symposium. 25.11.2002-28.11.2002, ?eské Bud?jovice] R&D Projects: GA ?R GA204/00/0019 Keywords : silk * H-fibroin Subject RIV: ED - Physiology

  18. Production of fine powder from silk by radiation

    International Nuclear Information System (INIS)

    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)

  19. Carbonic Anhydrase Generates CO2 and H+ That Drive Spider Silk Formation Via Opposite Effects on the Terminal Domains

    OpenAIRE

    Andersson, Marlene; Chen, Gefei; Otikovs, Martins; Landreh, Michael; Nordling, Kerstin; Kronqvist, Nina; Westermark, Per; Jörnvall, Hans; Knight, Stefan; Ridderstråle, Yvonne; Holm, Lena; Meng, Qing; Jaudzems, Kristaps; Chesler, Mitchell; Johansson, Jan

    2014-01-01

    Mapping the conditions of spider silk proteins along the silk gland, and combining with molecular studies, reveals a pH controlled switch between lock and trigger forms, providing insights into spider silk formation.

  20. Vibrational spectroscopic study of sulphated silk proteins

    Science.gov (United States)

    Monti, P.; Freddi, G.; Arosio, C.; Tsukada, M.; Arai, T.; Taddei, P.

    2007-05-01

    Degummed Bombyx mori ( B. m.) silk fibroin fabric and mutant naked pupa cocoons (Nd-s) consisting of almost pure silk sericin were treated with chlorosulphonic acid in pyridine and investigated by FT-IR and FT-Raman spectroscopies. Untreated silk fibroin and sericin displayed typical spectral features due to characteristic amino acid composition and molecular conformation (prevailing ?-sheet with a less ordered structure in sericin). Upon sulphation, the degree of molecular disorder increased in both proteins and new bands appeared. The IR bands at 1049 and 1014 cm -1 were attributed to vibrations of sulphate salts and that at 1385 cm -1 to the ?asSO 2 mode of organic covalent sulphates. In the 1300-1180 cm -1 range various contributions of alkyl and aryl sulphate salts, sulphonamides, sulphoamines and organic covalent sulphates, fell. Fibroin covalently bound sulphate groups through the hydroxyl groups of tyrosine and serine, while sericin through the hydroxyl groups of serine, since the ?OH vibrations at 1399 cm -1 in IR and at 1408 cm -1 in Raman disappeared almost completely. Finally, the increase of the I850/ I830 intensity ratio of Raman tyrosine doublet in fibroin suggested a change towards a more exposed state of tyrosine residues, in good agreement with the more disordered conformation taken upon sulphation.

  1. Promoter sequence of fibroin gene assigned by in vitro transcription system.

    OpenAIRE

    Tsujimoto, Y; Hirose, S.; Tsuda, M; Suzuki, Y.

    1981-01-01

    We have shown that the silk fibroin gene from Bombyx mori is faithfully transcribed in an in vitro transcription system of the HeLa cell extract prepared by the method of Manley et al. [Manley, J. L., Fire, A., Cano, A., Sharp, P. A. & Gefter, M. L. (1980) Proc. Natl. Acad. Sci. USA 77, 3855-3859]. Using this system and a series of deletion mutants of fibroin gene, we have assigned the promoter sequence of fibroin gene. The 5' boundary of the promoter is around nucleotide position -29, indica...

  2. 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 deveeals promising insights in the development of a biomimetic functional template for biomedical therapeutics and liver tissue engineering. (paper)

  3. 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

  4. 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 ...

  5. Solubilization of silk protein by radiation

    International Nuclear Information System (INIS)

    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 1050C), 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)

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

    International Nuclear Information System (INIS)

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

  7. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-03-15

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

  9. Characterization by Raman microspectroscopy of the strain-induced conformational transition in fibroin fibers from the silkworm Samia cynthia ricini.

    Science.gov (United States)

    Rousseau, Marie-Eve; Beaulieu, Lilyane; Lefèvre, Thierry; Paradis, Joanie; Asakura, Tetsuo; Pézolet, Michel

    2006-09-01

    Raman microspectroscopy has been used to quantitatively study the effect of a mechanical deformation on the conformation and orientation of Samia cynthia ricini (S. c. ricini) silk fibroin. Samples were obtained from the aqueous solution stored in the silk gland and stretched at draw ratios (lambda) ranging from 0 to 11. Using an appropriate band decomposition procedure, polarized and orientation-insensitive spectra have been analyzed to determine order parameters and the content of secondary structures, respectively. The data unambiguously show that, in response to mechanical deformation, S. c. ricini fibroin undergoes a cooperative alpha-helix to beta-sheet conformational transition above a critical draw ratio of 4. The alpha-helix content decreases from 33 to 13% when lambda increases from 0 to 11, while the amount of beta-sheets increases from 15 to 37%. In comparison, cocoon silk is devoid of alpha-helical structure and always contains a larger amount of beta-sheets. Although the presence of isosbestic points in different spectral regions reveals that the conformational change induced by mechanical deformation is a two-state process, our results suggest that part of the glycine residues might be incorporated into beta-poly(alanine) structures. The beta-sheets are initially isotropically distributed and orient along the fiber axis as lambda increases, but do not reach the high level of orientation found in the cocoon fiber. The increase in the orientation level of the beta-sheets is found to be concomitant with the alpha --> beta conformational conversion, whereas alpha-helices do not orient under the applied strain but are rather readily converted into beta-sheets. The components assigned to turns exhibit a small orientation perpendicular to the fiber axis in stretched samples, showing that, overall, the polypeptide chains are aligned along the stretching direction. Our results suggest that, in nature, factors other than stretching contribute to the optimization of the amount of beta-sheets and the high degree of orientation found in natural cocoon silk. PMID:16961312

  10. Self-assembly in the major ampullate gland of Nephila clavipes

    CERN Document Server

    Braun, F N

    2002-01-01

    We present a tentative interpretation of the origin of nematic liquid crystalline order exhibited by dragline silk fibroin solutions collected from the spider Nephila clavipes. Liquid crystallinity is thought to confer certain rheological properties on the fibroin solution which are exploited during the dragline spinning process. We show that the feasibility of liquid crystallinity under physiological conditions depends critically on parameters characterising the amino-acid sequence of the fibroin molecules.

  11. Stabilization of Enzymes in Silk Films

    OpenAIRE

    Lu, Shenzhou; WANG, XIAOQIN; Lv, Qiang; Hu, Xiao; Uppal, Neha; Omenetto, Fiorenzo; Kaplan, David L.

    2009-01-01

    Material systems are needed that promote stabilization of entrained molecules, such as enzymes or therapeutic proteins, without destroying their activity. We demonstrate that the unique structure of silk fibroin protein, when assembled into the solid state, establishes an environment that is conducive to the stabilization of entrained proteins. Enzymes (glucose oxidase, lipase and horseradish peroxidase) entrapped in these films over ten months retained significant activity, even when stored ...

  12. 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.

  13. 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.

  14. Minor ampullate silks from Nephila and Argiope spiders: tensile properties and microstructural characterization

    OpenAIRE

    Guinea Tortuero, Gustavo V.; Elices Calafat, Manuel; Plaza Baonza, Gustavo Ramo?n; Perea Abarca, Gracia Bele?n; Daza Garcia, Rafael; Riekel, Christian; Agullo?-rueda, Fernando; Hayashi, C.; Zhao, Y.; Pe?rez Rigueiro, Jose?

    2012-01-01

    The mechanical behavior and microstructure of minor ampullate gland silk (miS) of two orb-web spinning species, Argiope trifasciata and Nephila inaurata, were extensively characterized, enabling detailed comparison with other silks. The similarities and differences exhibited by miS when compared with the intensively studied major ampullate gland silk (MAS) and silkworm (Bombyx mori) silk offer a genuine opportunity for testing some of the hypotheses proposed to correlate microstructure and...

  15. Molecular Evolution of Lepidopteran Silk Proteins: Insights from the Ghost Moth, Hepialus californicus

    OpenAIRE

    Collin, Matthew A.; Mita, Kazuei; Sehnal, Frantisek; Hayashi, Cheryl Y

    2010-01-01

    Silk production has independently evolved in numerous arthropod lineages, such as Lepidoptera, the moths and butterflies. Lepidopteran larvae (caterpillars) synthesize silk proteins in modified salivary glands and spin silk fibers into protective tunnels, escape lines, and pupation cocoons. Molecular sequence data for these proteins are necessary to determine critical features of their function and evolution. To this end, we constructed an expression library from the silk glands of the ghost ...

  16. The influence of cocon treatment on the electric properties of the natural silk fibron

    International Nuclear Information System (INIS)

    Full Text: The influence of thermal treatment and treatment by the liquid nitrogen of cocons, on electric properties of the natural silk fibroin has been studied. It has been established that the polarization (?) and tangent of angle of dielectric losses (tangent ?) increase with the growth of amorphous sectors, that corresponds to the sample received from cocons, treated by the liquid nitrogen. Moreover the dielectric constant tangent of the loss angle and the electroconductivity of the fibroin, received from cocons treated by the liquid nitrogen are on 10% more in comparison with the fibroin received from cocons treated by the heated air and ultrahigh frequency (UHF) field

  17. Light can transform the secondary structure of silk protein

    Science.gov (United States)

    Tsuboi, Y.; Ikejiri, T.; Shiga, S.; Yamada, K.; Itaya, A.

    Fibroin is the main component of silk and is expected to be used as a novel functional material in medicine and bioelectronics. The main secondary structures of this protein are of the random-coil and the ?-sheet types. In this study, we carried out laser-induced transformation of the secondary structure, from the random-coil type to the ?-sheettype, in solid fibroin films. We prepared two types of fibroin films with the random-coil structure. One is a fibroin film doped with a dye as a photosensitizer with a small amount (1 wt%), and the other is a neat fibroin film. The former was excited at 532 nm and the latter was excited at 266 nm. Irradiations were carried out with fluences much lower than each ablation threshold. The excitation of the dye at 532 nm did not affect the secondary structure of the random-coil type. By contrast, 266-nm laser irradiation, which excites tryptophan (an amino-acid residue) involved in fibroin, created the ?-sheetdomain in the film. The structural transformation was revealed by infrared absorption spectroscopy and atomic force microscopy.

  18. Spider silk gut: development and characterization of a novel strong spider silk fiber.

    Science.gov (United States)

    Jiang, Ping; Marí-Buyé, Núria; Madurga, Rodrigo; Arroyo-Hernández, María; Solanas, Concepción; Gañán, Alfonso; Daza, Rafael; Plaza, Gustavo R; Guinea, Gustavo V; Elices, Manuel; Cenis, José Luis; Pérez-Rigueiro, José

    2014-01-01

    Spider silk fibers were produced through an alternative processing route that differs widely from natural spinning. The process follows a procedure traditionally used to obtain fibers directly from the glands of silkworms and requires exposure to an acid environment and subsequent stretching. The microstructure and mechanical behavior of the so-called spider silk gut fibers can be tailored to concur with those observed in naturally spun spider silk, except for effects related with the much larger cross-sectional area of the former. In particular spider silk gut has a proper ground state to which the material can revert independently from its previous loading history by supercontraction. A larger cross-sectional area implies that spider silk gut outperforms the natural material in terms of the loads that the fiber can sustain. This property suggests that it could substitute conventional spider silk fibers in some intended uses, such as sutures and scaffolds in tissue engineering. PMID:25475975

  19. Silk-elastinlike protein polymers for matrix-mediated cancer gene therapy.

    Science.gov (United States)

    Gustafson, Joshua A; Ghandehari, Hamidreza

    2010-12-30

    Silk-elastinlike protein polymers (SELPs) are recombinant polymers designed from silk fibroin and mammalian elastin amino acid repeats. These are versatile materials that have been examined as controlled release systems for intratumoral gene delivery. SELP hydrogels comprise monodisperse and tunable polymers that have the capability to control and localize the release and expression of plasmid DNA and viruses. This article reviews recent developments in the synthesis and characterization of SELP hydrogels and their use for matrix-mediated gene delivery. PMID:20430059

  20. 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...

  1. ?-Sheet Nanocrystalline Domains Formed from Phosphorylated Serine-Rich Motifs in Caddisfly Larval Silk: A Solid State NMR and XRD Study

    OpenAIRE

    Addison, J. Bennett; Ashton, Nicholas N.; Weber, Warner S.; Stewart, Russell J.; Holland, Gregory P.; Yarger, Jeffery L.

    2013-01-01

    Adhesive silks spun by aquatic caddisfly (order Trichoptera) larvae are used to build both intricate protective shelters and food harvesting nets underwater. In this study, we use 13C and 31P solid-state Nuclear Magnetic Resonance (NMR) and Wide Angle X-ray Diffraction (WAXD) as tools to elucidate molecular protein structure of caddisfly larval silk from the species Hesperophylax consimilis. Caddisfly larval silk is a fibroin protein based biopolymer containing mostly repetitive amino acid mo...

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

    Science.gov (United States)

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

    2015-04-29

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

  3. 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)

    Scientific Electronic Library Online (English)

    JOSÉ EDUARDO, SERRÃO.

    2005-03-01

    Full Text Available Se 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 conduc [...] e 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 Abstract in english 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 lum [...] en 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 Sphecidae

  4. TOWARDS A ROUTINE METHODOLOGY FOR ASSESSING THE CONDITION OF HISTORIC SILK

    Directory of Open Access Journals (Sweden)

    Jeongjin Kim

    2009-01-01

    Full Text Available To ensure continued access and long-term preser vation itis essential to understand the condition of an artefact, andthe behaviour of its component materials, in order to setlimits on display and handling. In support of curators andconservators of collections with historic textiles, we aredeveloping rapid and routine technology, involving nearinfrared spectroscopy coupled with multivariate analysis,which, when applied non-invasively on-site, will allow theestimation of the state of deterioration of silk fabrics.Pursuing this aim, we have now carried out further analyticalstudies on silks artificially aged under different regimesfor up to 20 days: dry thermal, high heat and humidity, andsunlight equivalent irradiation. The tensile strengths, yellownessindices, apparent molecular weights of fibroin, andnear infrared spectral sorbed moisture parameters for theaged silks were determined. The mechanical performanceof silk diminished exponentially over each ageing timecourse. For the various silks, the increases in yellownessindices and decreases in fibroin molecular weights andmoisture contents showed similar kinetics to the mechanicalchanges. While each parameter was correlated with thetensile strength, silks exposed to the different acceleratedageing factors exhibited diverse correlations. It is concludedthat, when formulating a general model for characterisingthe condition of silk using chemometrics, the referenceset should include examples of silks which have beenexposed to the full variety of ageing factors.

  5. Self-assembly in the major ampullate gland of Nephila clavipes

    OpenAIRE

    Braun, F N; Viney, C.

    2002-01-01

    We present a tentative interpretation of the origin of nematic liquid crystalline order exhibited by dragline silk fibroin solutions collected from the spider Nephila clavipes. Liquid crystallinity is thought to confer certain rheological properties on the fibroin solution which are exploited during the dragline spinning process. We show that the feasibility of liquid crystallinity under physiological conditions depends critically on parameters characterising the amino-acid ...

  6. Development of silk-based scaffolds for tissue engineering of bone from human adipose derived stem cells

    OpenAIRE

    Correia, Cristina; BHUMIRATANA, SARINDR; Yan, Leping; Oliveira, A. L.; GIMBLE, JEFFREY M.; Rockwood, Danielle; Kaplan, David; Sousa, R.A; R. L. Reis; VUNJAK-NOVAKOVIC, GORDANA

    2012-01-01

    Silk fibroin is a potent alternative to other biodegradable biopolymers for bone tissue engineering (TE), because of its tunable architecture and mechanical properties, and its demonstrated ability to support bone formation both in vitro and in vivo. In this study, we investigated a range of silk scaffolds for bone TE using human adipose-derived stem cells (hASCs), an attractive cell source for engineering autologous bone grafts. Our goal was to understand the effects of scaffold architecture...

  7. The use of silk-based devices for fracture fixation

    Science.gov (United States)

    Perrone, Gabriel S.; Leisk, Gary G.; Lo, Tim J.; Moreau, Jodie E.; Haas, Dylan S.; Papenburg, Bernke J.; Golden, Ethan B.; Partlow, Benjamin P.; Fox, Sharon E.; Ibrahim, Ahmed M. S.; Lin, Samuel J.; Kaplan, David L.

    2014-03-01

    Metallic fixation systems are currently the gold standard for fracture fixation but have problems including stress shielding, palpability and temperature sensitivity. Recently, resorbable systems have gained interest because they avoid removal and may improve bone remodelling due to the lack of stress shielding. However, their use is limited to paediatric craniofacial procedures mainly due to the laborious implantation requirements. Here we prepare and characterize a new family of resorbable screws prepared from silk fibroin for craniofacial fracture repair. In vivo assessment in rat femurs shows the screws to be self-tapping, remain fixed in the bone for 4 and 8 weeks, exhibit biocompatibility and promote bone remodelling. The silk-based devices compare favourably with current poly-lactic-co-glycolic acid fixation systems, however, silk-based devices offer numerous advantages including ease of implantation, conformal fit to the repair site, sterilization by autoclaving and minimal inflammatory response.

  8. 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 ed that the fibroin nanopowder has a ?-sheets structure, similar to fibroin filaments but with a lower crystallinity index.

  9. The design of silk fiber composition in moths has been conserved for more than 150 million years.

    Czech Academy of Sciences Publication Activity Database

    Yonemura, N.; Sehnal, František

    2006-01-01

    Ro?. 63, ?. 1 (2006), s. 42-53. ISSN 0022-2844 R&D Projects: GA AV ?R(CZ) IAA5007402 Institutional research plan: CEZ:AV0Z50070508 Keywords : silk * fibroin * Lepidoptera Subject RIV: CE - Biochemistry Impact factor: 2.767, year: 2006

  10. Effect of ?-sheet crystalline content on mass transfer in silk films

    Science.gov (United States)

    Karve, Kiran A.; Gil, Eun Seok; McCarthy, Stephen P.; Kaplan, David L.

    2011-01-01

    The material properties of silk are favorable for drug delivery due to the ability to control material structure and morphology under ambient, aqueous processing conditions. Mass transport of compounds with varying physical-chemical characteristics was studied in silk fibroin films with control of ?-sheet crystalline content. Two compounds, vitamin B12 and fluorescein isothiocynate (FITC) labeled lysozyme were studied in a diffusion apparatus to determine transport through silk films. The films exhibited size exclusion phenomenon with permeability coefficients with contrasting trends with increases in ?-sheet crystallinity. The size exclusion phenomenon observed with the two model compounds was characterized by contrasting trends in permeability coefficients of the films as a function of ?-sheet crystallinity. The diffusivity of the compounds was examined in the context of free volume theory. Apart from the ?-sheet crystallinity, size of the compound and its interactions with silk influenced mass transfer. Diffusivity of vitamin B12 was modeled to define a power law relationship with ?-sheet crystallinity. The results of the study demonstrate that diffusion of therapeutic agents though silk fibroin films can be directed to match a desired rate by modulating secondary structure of the silk proteins. PMID:22135474

  11. 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)

  12. 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.

  13. Correlation between fibroin amino acid sequence and physical silk properties.

    Czech Academy of Sciences Publication Activity Database

    Fedi?, Robert; Žurovec, Michal; Sehnal, František

    2003-01-01

    Ro?. 278, ?. 37 (2003), s. 35255-35264. ISSN 0021-9258 R&D Projects: GA ?R GA204/00/0019 Institutional research plan: CEZ:AV0Z5007907 Keywords : Bombyx-mori * antheraea-pernyi * messenger-RNA Subject RIV: CE - Biochemistry Impact factor: 6.482, year: 2003

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

    Directory of Open Access Journals (Sweden)

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

    2011-01-01

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

  15. 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 i. 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.

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

    Science.gov (United States)

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

    2011-10-01

    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 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.

  17. Stabilization of Enzymes in Silk Films

    Science.gov (United States)

    Lu, Shenzhou; Wang, Xiaoqin; Lv, Qiang; Hu, Xiao; Uppal, Neha; Omenetto, Fiorenzo

    2009-01-01

    Material systems are needed that promote stabilization of entrained molecules, such as enzymes or therapeutic proteins, without destroying their activity. We demonstrate that the unique structure of silk fibroin protein, when assembled into the solid state, establishes an environment that is conducive to the stabilization of entrained proteins. Enzymes (glucose oxidase, lipase and horseradish peroxidase) entrapped in these films over ten months retained significant activity, even when stored at 37°C, and in the case of glucose oxidase did not lose any activity. Further, the mode of processing of the silk protein into the films could be correlated to the stability of the enzymes. The relationship between processing and stability offers a large suite of conditions within which to optimize such stabilization processes. Overall, the techniques reported here result in materials that stabilize enzymes to a remarkable extent, without the need for cryoprotectants, emulsifiers, covalent immobilization or other treatments. Further, these systems are amenable to optical characterization, environmental distribution without refrigeration, are ingestible, and offer potential use in vivo, since silk materials are biocompatible and FDA approved, degradable with proteases and currently used in biomedical devices. PMID:19323497

  18. Silk electrogel coatings for titanium dental implants.

    Science.gov (United States)

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

    2015-04-01

    The aim of this study was to develop biocompatible, biodegradable dental implant coatings capable of withstanding the mechanical stresses imparted during implant placement. Two techniques were developed to deposit uniform silk fibroin protein coatings onto dental implants. Two novel coating techniques were implemented to coat titanium shims, studs, and implants. One technique involved electrodeposition of the silk directly onto the titanium substrates. The second technique consisted of melting electrogels and dispensing the melted gels onto the titanium to form the coatings. Both techniques were tested for coating reproducibility using a stylus profilometer and a dial thickness gauge. The mechanical strength of adhered titanium studs was assessed using a universal mechanical testing machine. Uniform, controllable coatings were obtained from both the electrodeposition and melted electrogel coating techniques, tunable from 35 to 1654?µm thick under the conditions studied, and able to withstand delamination during implantation into implant socket mimics. Mechanical testing revealed that the adhesive strength of electrogel coatings, 0.369?±?0.09?MPa, rivaled other biologically derived coating systems such as collagen, hydroxyapatite, and chitosan (0.07-4.83?MPa). These novel silk-based techniques offer a unique approach to the deposition of safe, simple, mechanically robust, biocompatible, and degradable implant coatings. PMID:25425563

  19. Structural organization of the P25 gene of Bombyx mori and comparative analysis of its 5' flanking DNA with that of the fibroin gene.

    OpenAIRE

    Couble, P.; Chevillard, M; Moine, A; Ravel-Chapuis, P; Prudhomme, J C

    1985-01-01

    We have cloned a large portion of the P25 gene of Bombyx mori encoding the 25,000 dalton polypeptide which associates with fibroin to constitute the major silk protein. Its structure has been investigated by restriction mapping R-loop analysis, S1 nuclease protection experiments and nucleotide sequencing of the region spanning the 5' end of the gene and its flanking DNA. This has permitted a comparative sequence analysis of the DNA from the P25 and fibroin genes. The genes demonstrate no rela...

  20. Identification and dynamics of polyglycine II nanocrystals in Argiope trifasciata flagelliform silk

    OpenAIRE

    Perea, G. B.; Riekel, C.; Guinea, G. V.; Madurga, R.; Daza, R.; Burghammer, M.; Hayashi, C.; Elices, M.; Plaza, G. R.; Pe?rez-rigueiro, J.

    2013-01-01

    Spider silks combine a significant number of desirable characteristics in one material, including large tensile strength and strain at breaking, biocompatibility, and the possibility of tailoring their properties. Major ampullate gland silk (MAS) is the most studied silk and their properties are explained by a double lattice of hydrogen bonds and elastomeric protein chains linked to polyalanine ?-nanocrystals. However, many basic details regarding the relationship between composition, micros...

  1. 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...

  2. 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

  3. Processing and characterization of powdered silk micro- and nanofibers by ultrasonication.

    Science.gov (United States)

    Wang, Hai-Yan; Chen, Yun-Yun; Zhang, Yu-Qing

    2015-03-01

    Silk derived from Bombyx mori silkworm cocoons was degummed in an aqueous sodium carbonate solution, and the resulting silk fibroin fibers were placed in an acidic aqueous solution and were treated with ultrasonication to obtain powdered micro- and nanofibers. The morphologies and spectral characteristics of these powdered silk fibers were investigated in detail. The shape, surface and structural features of the powdered fibers were affected by the ultrasonic power and media. Increasing the acidity of the ultrasonic solution and increasing the ultrasonic power increased the fiber breakage speed, resulting in shorter fiber lengths. Powdered microfibers could not be obtained in a formic acid solution, while powdered nanofibers whose diameter below 1?m were obtained in a combined formic acid and hydrochloric acid ultrasonication solution. Observation via SEM and optical microscopy revealed that the microfiber diameters were approximately 5-10?m, and those of the nanofibers were approximately 30-120nm. The analysis of laser sizer showed that the microfiber sizes ranged mainly from 20 to 100?m. FT-IR and XRD spectra demonstrated that the relative amount of ?-sheets increased after the ultrasonic treatment. The ?-amino group content on the surface of the micro- and nanofibers increased significantly. These studies provide reliable methods for the preparation of nano-scale silk fibroin fibers by ultrasonication and open new avenues for the development of powdered silk fibers as advanced functional biomaterials. PMID:25579945

  4. Water-Insoluble Silk Films with Silk I Structure

    OpenAIRE

    LU Qiang; Hu, Xiao; WANG, XIAOQIN; Kluge, Jonathan A.; Lu, Shenzhou; Cebe, Peggy; Kaplan, David L.

    2009-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Neo, Puay Yong; Shi, Pujiang; Goh, James Cho-Hong; Toh, Siew Lok

    2014-12-01

    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. PMID:25329452

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

    Science.gov (United States)

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

    2015-06-10

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

  8. 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)

  9. Water-Insoluble Silk Films with Silk I Structure

    Science.gov (United States)

    Lu, Qiang; Hu, Xiao; Wang, Xiaoqin; Kluge, Jonathan A.; Lu, Shenzhou; Cebe, Peggy; Kaplan, David L.

    2009-01-01

    Water-insoluble regenerated silk materials are normally achieved by increasing ?-sheet content (silk II). In the present study, water-insoluble silk films were prepared by controlling very slow drying of B. mori silk solutions, resulting in the formation of stable films with dominating silk I instead of silk II structure. Wide angle x-ray scattering (WAXS) indicated that the silk films stabilized by slow drying were mainly composed of silk I rather than silk II, while water- and methanol-annealed silk films had a higher silk II content. The silk films prepared through slow drying had a globule-like structure in the core with nano-filaments. The core region was composed of silk I and silk II, and these regions are surrounded by hydrophilic nano-filaments containing random, turns, and ?-helix secondary structures. The insoluble silk films prepared by slow drying had unique thermal, mechanical and degradative properties. DSC results revealed that silk I crystals had stable thermal properties up to 250°C, without crystallization above the Tg, but degraded in lower temperature than silk II structure. Compared with water- and methanol-annealed films, the films prepared through slow drying achieved better mechanical ductility and more rapid enzymatic degradation, reflective of 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 in the present approach of very slow drying, mimicking the natural process. The results also point to a new mode to generate new types of silk biomaterials, where mechanical properties can be enhanced, and degradation rates increased, yet water insolubility is maintained along with low beta sheet content. PMID:19874919

  10. PLGA nanofiber-coated silk microfibrous scaffold for connective tissue engineering.

    Science.gov (United States)

    Sahoo, Sambit; Toh, Siew Lok; Goh, James Cho Hong

    2010-10-01

    A modified degumming technique, involving boiling in 0.25% Na2CO3 with addition of 1% sodium dodecyl sulphate and intermittent ultrasonic agitation, was developed for knitted silk scaffolds. Sericin was efficiently removed, while mechanical and structural properties of native silk fibroin were preserved. Biocompatible and mechanically robust hybrid nano-microscaffolds were fabricated by coating these degummed silk scaffolds with an intervening adhesive layer of silk solution followed by electrospun poly-lactic-co-glycolic acid (PLGA) nanofibers. Cell proliferation on the hybrid silk scaffolds was improved by seeding cells on both surfaces of the flat scaffolds. Rolling up and continued culture of the cell-seeded hybrid scaffolds yielded cylindrical constructs that permitted cell proliferation, extracellular matrix deposition, and generated ligament/tendon graft analogs. Although PLGA-based hybrid scaffolds have earlier been proposed for dense connective tissue engineering, rapid biodegradation of PLGA was a drawback. In contrast, the underlying strong and slowly-degrading microfibrous silk scaffold used in this study ensured that the hybrid scaffold maintained adequate mechanical properties for longer periods, which is vital for continued support to the injured ligament/tendon throughout its healing period. PMID:20665681

  11. Silk Road Seattle

    Science.gov (United States)

    Silk Road Seattle is a "collaborative public education project using the 'Silk Road' theme to explore cultural interaction across Eurasia from the beginning of the Common Era (A.D.) to the Sixteenth Century." The Silk Road is a term understood to have been the overland trade route from China to the Mediterranean, opened first in the 2nd century and coming to an end between the 15th and 17th centuries. Traditional discussions of the Silk Road, however, recognize that there were branches that went into South Asia, or extended from Central Asia north of the Caspian Sea to the Black Sea. Sponsored primarily by the Simpson Center for the Humanities at the University of Washington and directed by Professors Daniel C. Waugh, Joel Walker, and Cynthea Bogel, this Web site contains a vast range of Silk Road materials. These materials include a list of texts that may be used in teaching and learning about the Silk Road, a section on cities and architecture along the Silk Road, information on traditional culture in Central Asia, a page of teaching and learning guides that list and annotate Silk Road materials, and a virtual art exhibit. This site is still in a constructive stage; therefore, every link is not yet accessible. In short, this site may be of value for a range of audiences, including school children, teachers, college and graduate students, and independent adult learners.

  12. Art on Silk Hoops

    Science.gov (United States)

    Padrick, Deborah

    2012-01-01

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

  13. Heavy-chain fibroin of Antheraea yamamai.

    Czech Academy of Sciences Publication Activity Database

    Fedi?, Robert; Žurovec, Michal; Sehnal, František

    ?eské Bud?jovice : Institute of entomology CAS, 1998 - (Brunnhofer, V.; Soldán, T.). s. 142 [European congress of entomology /6./. 23.08.1998-29.08.1998, ?eské Bud?jovice] Keywords : Antheraea yamamai * fibroin Subject RIV: EG - Zoology

  14. 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,...

  15. Pituitary gland

    Science.gov (United States)

    ... endocrine glands. Located above the pituitary gland is the hypothalamus. The hypothalamus decides which hormones the pituitary should release by ... electrical messages. In response to hormonal messages from the hypothalamus, the pituitary gland releases the following hormones: GH ( ...

  16. 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.

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

    Science.gov (United States)

    Yamauchi, Kazuo; Yamasaki, Shizuo; Takahashi, Rui; Asakura, Tetsuo

    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 1mg and therefore we used a home-built 1mm 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. PMID:20579856

  18. Solid-state NMR determination of the secondary structure of Samia cynthia ricini silk.

    Science.gov (United States)

    van Beek, J D; Beaulieu, L; Schäfer, H; Demura, M; Asakura, T; Meier, B H

    2000-06-29

    Silks are fibrous proteins that form heterogeneous, semi-crystalline solids. Silk proteins have a variety of physical properties reflecting their range of functions. Spider dragline silk, for example, has high tensile strength and elasticity, whereas other silks are better suited to making housing, egg sacs or the capture spiral of spiders' webs. The differing physical properties arise from variation in the protein's primary and secondary structure, and their packing in the solid phase. The high mechanical performance of spider dragline silk, for example, is probably due to a beta-sheet conformation of poly-alanine domains, embedded as small crystallites within the fibre. Only limited structural information can be obtained from diffraction of silks, so further characterization requires spectroscopic studies such as NMR. However, the classical approach to NMR structure determination fails because the high molecular weight, repetitive primary structure and structural heterogeneity of solid silk means that signals from individual amino-acid residues cannot be resolved. Here we adapt a recently developed solid-state NMR technique to determine torsion angle pairs (phi, psi) in the protein backbone, and we study the distribution of conformations in silk from the Eri silkworm, Samia cynthia ricini. Although the most probable conformation in native fibres is an anti-parallel beta-sheet, film produced from liquid directly extracted from the silk glands appears to be primarily alpha-helical. PMID:10890452

  19. Identification and dynamics of polyglycine II nanocrystals in Argiope trifasciata flagelliform silk.

    Science.gov (United States)

    Perea, G B; Riekel, C; Guinea, G V; Madurga, R; Daza, R; Burghammer, M; Hayashi, C; Elices, M; Plaza, G R; Pérez-Rigueiro, J

    2013-01-01

    Spider silks combine a significant number of desirable characteristics in one material, including large tensile strength and strain at breaking, biocompatibility, and the possibility of tailoring their properties. Major ampullate gland silk (MAS) is the most studied silk and their properties are explained by a double lattice of hydrogen bonds and elastomeric protein chains linked to polyalanine ?-nanocrystals. However, many basic details regarding the relationship between composition, microstructure and properties in silks are still lacking. Here we show that this relationship can be traced in flagelliform silk (Flag) spun by Argiope trifasciata spiders after identifying a phase consisting of polyglycine II nanocrystals. The presence of this phase is consistent with the dominant presence of the -GGX- and -GPG- motifs in its sequence. In contrast to the passive role assigned to polyalanine nanocrystals in MAS, polyglycine II nanocrystals can undergo growing/collapse processes that contribute to increase toughness and justify the ability of Flag to supercontract. PMID:24162473

  20. 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.

  1. Transparent and flexible resistive switching memory devices with a very high ON/OFF ratio using gold nanoparticles embedded in a silk protein matrix

    International Nuclear Information System (INIS)

    The growing demand for biomaterials for electrical and optical devices is motivated by the need to make building blocks for the next generation of printable bio-electronic devices. In this study, transparent and flexible resistive memory devices with a very high ON/OFF ratio incorporating gold nanoparticles into the Bombyx mori silk protein fibroin biopolymer are demonstrated. The novel electronic memory effect is based on filamentary switching, which leads to the occurrence of bistable states with an ON/OFF ratio larger than six orders of magnitude. The mechanism of this process is attributed to the formation of conductive filaments through silk fibroin and gold nanoparticles in the nanocomposite. The proposed hybrid bio-inorganic devices show promise for use in future flexible and transparent nanoelectronic systems. (paper)

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

    International Nuclear Information System (INIS)

    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

  3. 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.

  4. Endocrine glands

    Science.gov (United States)

    ... systems are referred to as the neuroendocrine system. The hypothalamus is known as the master switchboard because it’s ... gland, which hangs by a thin stalk from the hypothalamus, is called the master gland of the body ...

  5. Mechano growth factor (MGF) and transforming growth factor (TGF)-?3 functionalized silk scaffolds enhance articular hyaline cartilage regeneration in rabbit model.

    Science.gov (United States)

    Luo, Ziwei; Jiang, Li; Xu, Yan; Li, Haibin; Xu, Wei; Wu, Shuangchi; Wang, Yuanliang; Tang, Zhenyu; Lv, Yonggang; Yang, Li

    2015-06-01

    Damaged cartilage has poor self-healing ability and usually progresses to scar or fibrocartilaginous tissue, and finally degenerates to osteoarthritis (OA). Here we demonstrated that one of alternative isoforms of IGF-1, mechano growth factor (MGF) acted synergistically with transforming growth factor ?3 (TGF-?3) embedded in silk fibroin scaffolds to induce chemotactic homing and chondrogenic differentiation of mesenchymal stem cells (MSCs). Combination of MGF and TGF-?3 significantly increased cell recruitment up to 1.8 times and 2 times higher than TGF-?3 did in vitro and in vivo. Moreover, MGF increased Collagen II and aggrecan secretion of TGF-?3 induced hMSCs chondrogenesis, but decreased Collagen I in vitro. Silk fibroin (SF) scaffolds have been widely used for tissue engineering, and we showed that methanol treated pured SF scaffolds were porous, similar to compressive module of native cartilage, slow degradation rate and excellent drug released curves. At 7days after subcutaneous implantation, TGF-?3 and MGF functionalized silk fibroin scaffolds (STM) recruited more CD29+/CD44 + cells (P cell recruitment and facilitated in situ articular cartilage regeneration, thus providing a novel strategy for cartilage repair. PMID:25818452

  6. 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

  7. 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

  8. Optically switchable natural silk

    Science.gov (United States)

    Krasnov, Igor; Krekiehn, Nicolai R.; Krywka, Christina; Jung, Ulrich; Zillohu, Ahnaf U.; Strunskus, Thomas; Elbahri, Mady; Magnussen, Olaf M.; Müller, Martin

    2015-03-01

    An optically active bio-material is created by blending natural silk fibers with photoisomerizable chromophore molecules—azobenzenebromide (AzBr). The material converts the energy of unpolarized light directly into mechanical work with a well-defined direction of action. The feasibility of the idea to produce optically driven microsized actuators on the basis of bio-material (silk) is proven. The switching behavior of the embedded AzBr molecules was studied in terms of UV/Vis spectroscopy. To test the opto-mechanical properties of the modified fibers and the structural changes they undergo upon optically induced switching, single fiber X-ray diffraction with a micron-sized synchrotron radiation beam was combined in situ with optical switching as well as with mechanical testing and monitoring. The crystalline regions of silk are not modified by the presence of the guest molecules, hence occupy only the amorphous part of the fibers. It is shown that chromophore molecules embedded into fibers can be reversibly switched between the trans and cis conformation by illumination with light of defined wavelengths. The host fibers respond to this switching with a variation of the internal stress. The amplitude of the mechanical response is independent of the applied external stress and its characteristic time is shorter than the relaxation time of the usual mechanical response of silk.

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

    Directory of Open Access Journals (Sweden)

    Y. Srisuwan

    2009-01-01

    Full Text Available 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(NO32. 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 Microscope (SEM and Fourier transform infrared spectroscopy (FTIR for morphological and conformational studies, respectively. The results found that Eri SF films were rougher surfaces than Bombyx mori (B. mori SF film. In addition, the film of 0.5% weight SF solution was also rougher surfaces than 1% weight. It contained the ?-helix structure in higher ratio than 1% weight film since the 1% weight SF solution film composed in higher ?-sheet structure. However, the later conformation could affect the SF film to be more hard and brittle than low percent weight content.

  10. Oxygen-reduction activity of silk-derived carbons

    Energy Technology Data Exchange (ETDEWEB)

    Iwazaki, Tomoya [Department of Fine Materials Engineering, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567 (Japan); Shinano Kenshi Co., Ltd., 1078 Kamimaruko, Ueda, Nagano 386-0498 (Japan); Yang, Hongsheng; Obinata, Ryoujin; Sugimoto, Wataru; Takasu, Yoshio [Department of Fine Materials Engineering, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567 (Japan)

    2010-09-15

    Carbonized silk fibroin (CS), which is free of metallic elements, showed high catalytic activity for oxygen-reduction reaction (ORR). The catalytic activity of CS for ORR was greatly enhanced by steam activation forming silk-derived activated carbon (CS-AC). The surface morphology, surface area, pore structure and remaining nitrogen species of the CSs were compared with those of the CS-ACs. The open-circuit potential and the power density of a polymer electrolyte fuel cell using a CS900-AC, which was heat-treated at 900 C prior to the steam activation, and a platinum/C (C: carbon black) anode under pure oxygen and hydrogen gases, respectively, both at 0.2 MPa, were 0.92 V and 142 mW cm{sup -2} at 80 C. The ORR on the activated carbon, CS900-AC, proceeded with a 3.5-electron reaction at 0.6 V (vs. RHE); however, this was improved to a 3.9-electron reaction with the addition of zirconium oxide at 20 wt% to CS900-AC. (author)

  11. Self-tensioning aquatic caddisfly silk: Ca2+-dependent structure, strength, and load cycle hysteresis.

    Science.gov (United States)

    Ashton, Nicholas N; Roe, Daniel R; Weiss, Robert B; Cheatham, Thomas E; Stewart, Russell J

    2013-10-14

    Caddisflies are aquatic relatives of silk-spinning terrestrial moths and butterflies. Casemaker larvae spin adhesive silk fibers for underwater construction of protective composite cases. The central region of Hesperophylax sp. H-fibroin contains a repeating pattern of three conserved subrepeats, all of which contain one or more (SX)n motifs with extensively phosphorylated serines. Native silk fibers were highly extensible and displayed a distinct yield point, force plateau, and load cycle hysteresis. FTIR spectroscopy of native silk showed a conformational mix of random coil, ?-sheet, and turns. Exchanging multivalent ions with Na(+) EDTA disrupted fiber mechanics, shifted the secondary structure ratios from antiparallel ?-sheet toward random coil and turns, and caused the fibers to shorten, swell in diameter, and disrupted fiber birefringence. The EDTA effects were reversed by restoring Ca(2+). Molecular dynamic simulations provided theoretical support for a hypothetical structure in which the (pSX)n motifs may assemble into two- and three-stranded, Ca(2+)-stabilized ?-sheets. PMID:24050221

  12. Endocrine Glands & Their Hormones

    Science.gov (United States)

    ... Characteristics of Hormones Endocrine Glands & Their Hormones Pituitary & Pineal Glands Thyroid & Parathyroid Glands Adrenal Gland Pancreas Gonads ... hormone secretion. « Previous (Characteristics of Hormones) Next (Pituitary & Pineal Glands) » Contact Us | Privacy Policy | Accessibility | FOIA | ...

  13. 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)

  14. 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...

  15. 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

    2015-06-17

    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 < 5 but become 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

  16. 21 CFR 878.5030 - Natural nonabsorbable silk surgical suture.

    Science.gov (United States)

    2010-04-01

    ... Natural nonabsorbable silk surgical suture. 878.5030 Section 878... Natural nonabsorbable silk surgical suture. (a) Identification. Natural nonabsorbable silk surgical suture is a nonabsorbable,...

  17. 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.

  18. Minor ampullate silks from Nephila and Argiope spiders: tensile properties and microstructural characterization.

    Science.gov (United States)

    Guinea, G V; Elices, M; Plaza, G R; Perea, G B; Daza, R; Riekel, C; Agulló-Rueda, F; Hayashi, C; Zhao, Y; Pérez-Rigueiro, J

    2012-07-01

    The mechanical behavior and microstructure of minor ampullate gland silk (miS) of two orb-web spinning species, Argiope trifasciata and Nephila inaurata, were extensively characterized, enabling detailed comparison with other silks. The similarities and differences exhibited by miS when compared with the intensively studied major ampullate gland silk (MAS) and silkworm (Bombyx mori) silk offer a genuine opportunity for testing some of the hypotheses proposed to correlate microstructure and tensile properties in silk. In this work, we show that miSs of different species show similar properties, even when fibers spun by spiders that diverged over 100 million years are compared. The tensile properties of miS are comparable to those of MAS when tested in air, significantly in terms of work to fracture, but differ considerably when tested in water. In particular, miS does not show a supercontraction effect and an associated ground state. In this regard, the behavior of miS in water is similar to that of B. mori silk, and it is shown that the initial elastic modulus of both fibers can be explained using a common model. Intriguingly, the microstructural parameters measured in miS are comparable to those of MAS and considerably different from those found in B. mori. This fact suggests that some critical microstructural information is still missing in our description of silks, and our results suggest that the hydrophilicity of the lateral groups or the large scale organization of the sequences might be routes worth exploring. PMID:22668322

  19. 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.

  20. Immobilization of thorium over fibroin by polyacrylonitrile (PAN)

    International Nuclear Information System (INIS)

    This report describes a process for immobilization of thorium over fibroin, which was used as a bio-adsorbant, by polyacrylonitrile. The amounts of thorium in aqueous solutions which may be leached in various aqueous ambients were detected by a spectrophotometer. The results show that polyacrylonitrile processes are feasible to immobilize spent fibroins. The leachability of the materials immobilized with polyacrylonitrile can meet the requirements of storage and final disposal. The leachability of thorium ions from immobilized spent fibroin was rather low for 8 months

  1. 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 48h 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 ~8-17nm and 15-22nm respectively. Comparatively higher degradation of Octa composite possessing higher porosity proved in turn more osteoinduction with in situ apatitic development. PMID:26046279

  2. Molecular spring: from spider silk to silkworm silk

    OpenAIRE

    Wu, Xiang; Liu, Xiang-yang; 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 modeli...

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

    International Nuclear Information System (INIS)

    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), 13C 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 13C=O isotope-labeled (Ala-Gly-Gly)10. The torsion angles were determined to be (?, ?) = (-90 deg., 150 deg.) within an experimental error of ±10 deg. for each residue. This conformation is characterized as 31 helix which is in agreement with the structure proposed from the X-ray powder diffraction pattern of poly(Ala-Gly-Gly). The 31 helix of (Ala-Gly-Gly)10 does not change by formic acid treatment although (Ala-Gly)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 31 helix conformation of (Ala-Gly-Gly)10 is considered very stable. Fur10 is considered very stable. Furthermore, the torsion angles of the 16th Leu residue of (Leu-Gly-Gly)10 were also determined as (?, ?) = (-90 deg., 150 deg.) and this peptide is also considered to take 31 helix conformation

  4. Adrenal Gland Disorders

    Science.gov (United States)

    The adrenal glands are small glands located on top of each kidney. They produce hormones that you can't live ... stress and has many other important functions. With adrenal gland disorders, your glands make too much or not ...

  5. Anterior Cruciate Ligament Reconstruction in a Rabbit Model Using Silk-Collagen Scaffold and Comparison with Autograft

    Science.gov (United States)

    Bi, Fanggang; Shi, Zhongli; Liu, An; Guo, Peng; Yan, Shigui

    2015-01-01

    The objective of the present study was to perform an in vivo assessment of a novel silk-collagen scaffold for anterior cruciate ligament (ACL) reconstruction. First, a silk-collagen scaffold was fabricated by combining sericin-extracted knitted silk fibroin mesh and type I collagen to mimic the components of the ligament. Scaffolds were electron-beam sterilized and rolled up to replace the ACL in 20 rabbits in the scaffold group, and autologous semitendinosus tendons were used to reconstruct the ACL in the autograft control group. At 4 and 16 weeks after surgery, grafts were retrieved and analyzed for neoligament regeneration and tendon-bone healing. To evaluate neoligament regeneration, H&E and immunohistochemical staining was performed, and to assess tendon-bone healing, micro-CT, biomechanical test, H&E and Russell-Movat pentachrome staining were performed. Cell infiltration increased over time in the scaffold group, and abundant fibroblast-like cells were found in the core of the scaffold graft at 16 weeks postoperatively. Tenascin-C was strongly positive in newly regenerated tissue at 4 and 16 weeks postoperatively in the scaffold group, similar to observations in the autograft group. Compared with the autograft group, tendon-bone healing was better in the scaffold group with trabecular bone growth into the scaffold. The results indicate that the silk-collagen scaffold has considerable potential for clinical application. PMID:25938408

  6. Cell culture's spider silk road.

    Science.gov (United States)

    Perkel, Jeffrey

    2014-06-01

    A number of synthetic and natural materials have been tried in cell culture and tissue engineering applications in recent years. Now Jeffrey Perkel takes a look at one new culture component that might surprise you-spider silk. PMID:24924388

  7. 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

  8. 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.

  9. 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.

  10. Recombinant DNA production of spider silk proteins

    OpenAIRE

    Tokareva, Olena; Michalczechen-lacerda, Valqui?ria A.; Rech, Eli?bio L.; Kaplan, David L.

    2013-01-01

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

  11. Discrimination of cultivated silk and wild silk by conventional instrumental analyses.

    Science.gov (United States)

    Matsuyama, Yuji; Nagatani, Yoshiaki; Goto, Toshiyuki; Suzuki, Shinichi

    2013-09-10

    In Japan, recent trends have seen wild silk preferred over cultivated silk because of its texture. Some cases of fraud have occurred where cultivated silk garments are sold as wild silk. Samples from these cases, morphological observation using light microscope and polarized microscope have been conducted in forensic science laboratories. Sometimes scanning electron microscopy was also carried out. However, the morphology of silk shows quite wide variation, which makes it difficult to discriminate wild and cultivated silks by this method. In this report, silk discrimination was investigated using conventional instrumental analyses commonly available in forensic laboratories, such as Fourier-transfer infrared spectrometry (FT-IR), pyrolysis-gas chromatography/mass spectrometry (pyr-GC/MS) and differential thermal analysis (DTA). By FT-IR, cultivated and wild silk gave similar infrared spectra, but wild silk had a characteristic peak at 965 cm(-1) from the deformation vibration of the carbon-carbon double bond of the indole ring. Comparison of the pyrograms of cultivated and wild silk showed that wild silk had large indole and skatole peaks that cultivated silk did not, and these peaks might arise from tryptophan. The results of thermogravimetry/DTA showed that the endothermic peak was about 40 °C higher for wild silk than for cultivated silk. Using a combination of these results, cultivated and wild silk could be discriminated by common forensic instrumental techniques. PMID:23742990

  12. Self-recovering caddisfly silk: energy dissipating, Ca(2+)-dependent, double dynamic network fibers.

    Science.gov (United States)

    Ashton, Nicholas N; Stewart, Russell J

    2015-03-01

    Single fibers of the sticky underwater larval silk of the casemaker caddisfly (H. occidentalis) are viscoelastic, display large strain cycle hysteresis, and self-recover 99% of their initial stiffness and strength within 120 min. Mechanical response to cyclical strains suggested viscoelasticity is due to two independent, self-recovering Ca(2+)-crosslinked networks. The networks display distinct pH dependence. The first network is attributed to Ca(2+)-stabilized phosphoserine motifs in H-fibroin, the second to Ca(2+) complexed carboxylate groups in the N-terminus of H-fibroin and a PEVK-like protein. These assignments were corroborated by IR spectroscopy. The results are consolidated into a multi-network model in which reversible rupture of the Ca(2+)-crosslinked domains at a critical stress results in pseudo-plastic deformation. Slow refolding of the domains results in nearly full recovery of fiber length, stiffness, and strength. The fiber toughening, energy dissipation, and recovery mechanisms, are highly adaptive for the high energy aquatic environment of caddisfly larvae. PMID:25525713

  13. Differential expression of genes in salivary glands of male Rhipicephalus (Boophilus) microplus in response to infection with Anaplasma marginale

    OpenAIRE

    Zivkovic, Zorica; Esteves, Eliane; Almaza?n, Consuelo; Daffre, Sirlei; Nijhof, Ard M.; Kocan, Katherine M.; Jongejan, Frans; Fuente Garci?a, Jose? La

    2010-01-01

    [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 (...

  14. 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.

  15. In vitro evaluation of a novel non-mulberry silk scaffold for use in tendon regeneration.

    Science.gov (United States)

    Musson, David S; Naot, Dorit; Chhana, Ashika; Matthews, Brya G; McIntosh, Julie D; Lin, Sandy T C; Choi, Ally J; Callon, Karen E; Dunbar, P Rod; Lesage, Stephanie; Coleman, Brendan; Cornish, Jillian

    2015-05-01

    Tearing of the rotator cuff tendon in the shoulder is a significant clinical problem, with large/full-thickness tears present in ?22% of the general population and recurrent tear rates postarthroscopic repair being quoted as high as 94%. Tissue-engineered biomaterials are increasingly being investigated as a means to augment rotator cuff repairs, with the aim of inducing host cell responses to increase tendon tissue regeneration. Silk-derived materials are of particular interest due to the high availability, mechanical strength, and biocompatibility of silks. In this study, Spidrex(®), a novel knitted, non-mulberry silk fibroin scaffold was evaluated in vitro for its potential to improve tendon regeneration. Spidrex was compared with a knitted Bombyx mori silk scaffold, a 3D collagen gel and Fiberwire(®) suture material. Primary human and rat tenocytes successfully adhered to Spidrex and significantly increased in number over a 14 day period (p<0.05), as demonstrated by fluorescent calcein-AM staining and alamarBlue(®) assays. A similar growth pattern was observed with human tenocytes cultured on the B. mori scaffold. Morphologically, human tenocytes elongated along the silk fibers of Spidrex, assuming a tenocytic cell shape, and were less circular with a higher aspect ratio compared with human tenocytes cultured on the B. mori silk scaffold and within the collagen gel (p<0.05). Gene expression analysis by real-time PCR showed that rat tenocytes cultured on Spidrex had increased expression of tenocyte-related genes such as fibromodullin, scleraxis, and tenomodulin (p<0.05). Expression of genes that indicate transdifferentiation toward a chondrocytic or osteoblastic lineage were significantly lower in tenocytes cultured on Spidrex in comparison to the collagen gel (p<0.05). Immunogenicity assessment by the maturation of and cytokine release from primary human dendritic cells demonstrated that Spidrex enhanced dendritic cell maturation in a similar manner to the clinically used suture material Fiberwire, and significantly upregulated the release of proinflammatory cytokines (p<0.05). This suggests that Spidrex may induce an early immune response postimplantation. While further work is required to determine what effect this immune response has on the tendon healing process, our in vitro data suggests that Spidrex may have the cytocompatibility and bioactivity required to support tendon regeneration in vivo. PMID:25604072

  16. Thymus Gland Anatomy

    Science.gov (United States)

    ... 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 gland; illustration ...

  17. Judaism and the Silk Route.

    Science.gov (United States)

    Foltz, Richard

    1998-01-01

    Demonstrates that the Judeans traveled along the Ancient Silk Route. Discusses the Iranian influence on the formation of Jewish religious ideas. Considers the development of Jewish trade networks, focusing on the Radanites (Jewish traders), the Jewish presence in the Far East, and the survival of Judaism in central Asia. (CMK)

  18. A model for the stretch-mediated enzymatic degradation of silk fibers.

    Science.gov (United States)

    Kluge, Jonathan A; Thurber, Amy; Leisk, Gary G; Kaplan, David L; Dorfmann, A Luis

    2010-10-01

    To restore physiological function through regenerative medicine, biomaterials introduced into the body must degrade at a rate that matches new tissue formation. For effective therapies, it is essential that we understand the interaction between physiological factors, such as routine mechanical loading specific to sites of implantation, and the resultant rate of material degradation. These relationships are poorly characterized at this time. We hypothesize that mechanical forces alter the rates of remodeling of biomaterials, and this impact is modulated by the concentration of enzymes and the duration of the mechanical loads encountered in situ. To test this hypothesis we subjected silk fibroin fibers to repeated cyclic loading in the presence of enzymatic degradation (either alpha-chymotrypsin or Protease XIV) and recorded the stress-strain response. Data were collected daily for a duration of 2 weeks and compared to the control cases of stretched fibers in the presence of phosphate buffered saline or non-stretched samples in the presence of enzyme alone. We observed that incubation with proteases in the absence of mechanical loads causes a reduction of the ultimate tensile strength but no change in stiffness. However, cyclic loading caused the accumulation of residual strain and softening in the material's properties. We utilize these data to formulate a mathematical model to account for residual strain and reduction of mechanical properties during silk fiber degradation. Numerical predictions are in fair agreement with experimental data. The improved understanding of the degradation phenomenon will be significant in many clinical repair cases and may be synergistic to decrease silk's mechanical properties after in vivo implantation. PMID:20696419

  19. 3D multi-channel bi-functionalized silk electrospun conduits for peripheral nerve regeneration.

    Science.gov (United States)

    Dinis, T M; Elia, R; Vidal, G; Dermigny, Q; Denoeud, C; Kaplan, D L; Egles, C; Marin, F

    2015-01-01

    Despite technological advances over the past 25 years, a complete recovery from peripheral nerve injuries remains unsatisfactory today. The autograft is still considered the "gold standard" in clinical practice; however, postoperative complications and limited availability of nerve tissue have motivated the development of alternative approaches. Among them, the development of biomimetic nerve graft substitutes is one of the most promising strategies. In this study, multichanneled silk electrospun conduits bi-functionalized with Nerve Growth Factor (NGF) and Ciliary Neurotropic Factor (CNTF) were fabricated to enhance peripheral nerve regeneration. These bioactive guides consisting of longitudinally oriented channels and aligned nanofibers were designed in order to mimic the fascicular architecture and fibrous extracellular matrix found in native nerve. The simple use of the electrospinning technique followed by a manual manipulation to manufacture these conduits provides tailoring of channel number and diameter size to create perineurium-like structures. Functionalization of the silk fibroin nanofiber did not affect its secondary structure and chemical property. ELISA assays showed the absence of growth factors passive release from the functionalized fibers avoiding the topical accumulation of proteins. In addition, our biomimetic multichanneled functionalized nerve guides displayed a mechanical behavior comparable to that of rat sciatic nerve with an ultimate peak stress of 4.0 ± 0.6 MPa and a corresponding elongation at failure of 156.8 ± 46.7%. Taken together, our results demonstrate for the first time our ability to design and characterize a bi-functionalized nerve conduit consisting of electrospun nanofibers with multichannel oriented and nanofibers aligned for peripheral regeneration. Our bioactive silk tubes thus represent a new and promising technique towards the creation of a biocompatible nerve guidance conduit. PMID:25460402

  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. Secrets of the Silk Road

    Science.gov (United States)

    Secrets of the Silk Road is another worthy addition to the growing body of Web-based information about the Silk Road (see, for example, The International Dunhuang Project, founded in 1998 and mentioned in several Scout Reports), launched by the Bowers Museum of Santa Ana, California and presented by University of Pennsylvania Museum of Archaeology and Anthropology. This site includes artifacts documenting the history of the Silk Road in the vast Tarim Basin in the Far Western Xinjiang Uyghur Autonomous Region of China. Three well-preserved mummies from the Tarim Basin have been brought to the United States for the exhibition, along with lavish grave goods. Visitors to the website can view images of "The Beauty of Xiaohe," a female mummy from 1800-1500 BCE and other treasures ranging from a Chrysanthemum Shaped Dessert from the 5th-3rd century BCE, to gold objects such as mask from 5th-6th century CE or the Gold Plaque with Lion Design, 5th-3rd Century BCE.

  2. 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.

  3. 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

  4. 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.

  5. 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 - ...

  6. MALIGNANT SALIVARY GLAND TUMORS

    Directory of Open Access Journals (Sweden)

    Violeta Trandafir

    2010-05-01

    Full Text Available Malignant salivary gland tumors make up 6% of all head and neck tumors. Several types of cancer can develop in these glands. Only malignant tumors of the salivary glands are discussed in this paper. The diagnosis and treatment of salivary gland malignancies remain complex, with challenging problems for maxillo-facial surgeon. Scientists have found few risk factors that make a person more likely to develop salivary gland cancer. Salivary gland cancer is uncommon, and there is no widely recommended screening schedule for this cancer. CT scanning or MRI is useful for determining the extent of large tumors, for evaluating extraglandular extension, for determining the actual depth of parotid tumors, and for discovering other tumors in one gland or in the controlateral gland. Fine-needle aspiration biopsy (FNAB is a valuable diagnostic adjunct in evaluation of head and neck masses but its role in evaluation of salivary gland tumors is controversial. There are also discussed some histologic findings about mucoepidermoid carcinoma, adenoid cystic carcinoma, acinic cell carcinoma, carcinoma ex-pleomorphic adenoma, squamous cell carcinoma and adenocarcinoma developed in salivary glands. Carefully planned and executed surgical excision is the primary treatment for all malignant tumors of the salivary glands. The principles of surgery vary with the site of origin. The extent of surgery is based on the size of the tumor, local extension and neck metastases. Staging of malignant salivary gland tumors is important for predicting prognosis and for accurate comparison of treatment results.

  7. 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.

  8. Silk and collagen scaffolds for tendon reconstruction.

    Science.gov (United States)

    Kwon, Soon-Yong; Chung, Jin-Wha; Park, Hee-Jung; Jiang, Yuan-Yuan; Park, Jung-Keug; Seo, Young-Kwon

    2014-04-01

    In this study, silk thread (Bombyx mori) was braided to a tube-like shape and sericin was removed from the silk tube. Thereafter, collagen/chondroitin-6-sulfate solution was poured into the silk tube, and the lyophilization process was performed. To assess the inflammatory response in vivo, raw silk and sericin-free silk tubes were implanted in the subcutaneous layer of mice. After 10 days of in vivo implantation, mild inflammatory responses were observed around the sericin-free silk tubes, and severe inflammation with the presence of neutrophils and macrophages was observed around the raw silk tubes. At 24 weeks post implantation, the regenerated tendon had a thick, cylindrical, grayish fibrous structure and a shiny white appearance, similar to that of the native tendon in the rabbit model of tendon defect. The average tensile strength of the native tendons was 220 ± 20 N, whereas the average tensile strength of the regenerated tendons was 167 ± 30 N and the diameter of the regenerated tendon (3 ± 0.2 mm) was similar to that of the native tendons (4 ± 0.3 mm). Histologically, the regenerated tendon resembled the native tendon, and all the regenerated tissues showed organized bundles of crimped fibers. Masson trichrome staining was performed for detecting collagen synthesis, and it showed that the artificial tendon was replaced by new collagen fibers and extracellular matrix. However, the regenerated tendon showed fibrosis to a certain degree. In conclusion, the artificial tendon, comprising a braided silk tube and lyophilized collagen sponge, was optimal for tendon reconstruction. Thus, this study showed an improved regeneration of neo-tendon tissues, which have the structure and tensile strength of the native tendon, with the use of the combination of collagen and silk scaffold. PMID:24705339

  9. 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.

  10. 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

  11. 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

  12. The Inherent Acidic Characteristics of Aged Silk

    OpenAIRE

    Paul Wyeth; Xiaomei Zhang; Jeongjin Kim

    2008-01-01

    Silks are frequently a cause of concern for conservatorsand curators. Amongst other critical challenges, textileacidity is considered to pose a risk. Consequently, it iscommon practice to carry out pH measurements whenassessing condition. Enhanced acidity is usually ascribedto previous processing treatments, adsorbed pollutants,and oxidative deterioration. However, the results of thedetailed study reported in this paper suggest thatincreased acidity of silk is an expected consequence ofageing...

  13. Conformational transitions in model silk peptides.

    OpenAIRE

    Wilson, D.; Valluzzi, R.; Kaplan, D.

    2000-01-01

    Protein structural transitions and beta-sheet formation are a common problem both in vivo and in vitro and are of critical relevance in disparate areas such as protein processing and beta-amyloid and prion behavior. Silks provide a "databank" of well-characterized polymorphic sequences, acting as a window onto structural transitions. Peptides with conformationally polymorphic silk-like sequences, expected to exhibit an intractable beta-sheet form, were characterized using Fourier transform in...

  14. 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...

  15. 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)

  16. 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.

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

    Scientific Electronic Library Online (English)

    Eliane, Victoriano; Elisa A., Gregório.

    2004-08-01

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

  18. A self-assembling peptide RADA16-I integrated with spider fibroin uncrystalline motifs

    Directory of Open Access Journals (Sweden)

    Sun L

    2012-02-01

    Full Text Available Lijuan Sun1,2, Xiaojun Zhao1,31West China Hospital Laboratory of Nanomedicine and Institute for Nanobiomedical Technology and Membrane Biology, Sichuan University, Chengdu 610041, Sichuan, China; 2Dept of Oral and Maxillofacial Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, Guangdong, China; 3Center for Biomedical Engineering NE47-378, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USAAbstract: Mechanical strength of nanofiber scaffolds formed by the self-assembling peptide RADA16-I or its derivatives is not very good and limits their application. To address this problem, we inserted spidroin uncrystalline motifs, which confer incomparable elasticity and hydrophobicity to spider silk GGAGGS or GPGGY, into the C-terminus of RADA16-I to newly design two peptides: R3 (n-RADARADARADARADA-GGAGGS-c and R4 (n-RADARADARADARADA-GPGGY-c, and then observed the effect of these motifs on biophysical properties of the peptide. Atomic force microscopy, transmitting electron microscopy, and circular dichroism spectroscopy confirm that R3 and R4 display ß-sheet structure and self-assemble into long nanofibers. Compared with R3, the ß-sheet structure and nanofibers formed by R4 are more stable; they change to random coil and unordered aggregation at higher temperature. Rheology measurements indicate that novel peptides form hydrogel when induced by DMEM, and the storage modulus of R3 and R4 hydrogel is 0.5 times and 3 times higher than that of RADA16-I, respectively. Furthermore, R4 hydrogel remarkably promotes growth of liver cell L02 and liver cancer cell SMCC7721 compared with 2D culture, determined by MTT assay. Novel peptides still have potential as hydrophobic drug carriers; they can stabilize pyrene microcrystals in aqueous solution and deliver this into a lipophilic environment, identified by fluorescence emission spectra. Altogether, the spider fibroin motif GPGGY most effectively enhances mechanical strength and hydrophobicity of the peptide. This study provides a new method in the design of nanobiomaterials and helps us to understand the role of the amino acid sequence in nanofiber formation.Keywords: uncrystalline motif, self-assembling peptide, ß-sheet, nanofiber, mechanical strength, hydrophobic compound carrier

  19. Tarantulas and social spiders : a tale of sex and silk

    OpenAIRE

    Bull, Jonathan

    2012-01-01

    Studies of spider silks indicate that they may outperform virtually all synthetic fibres in terms of strength, elasticity and toughness. To date, most silks studied come from only a select few species and likely underrepresent the immense diversity of the clades. Here, protein and mRNA sequence analyses were used to study silk from two types of spider. The first approach used ESI tandem mass spectrometry to sequence peptide fragments of a silk from a tarantula (Mygalomorphae, Theraphosidae), ...

  20. 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 ...

  1. 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

  2. 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.

  3. 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.

  4. Salivary glands neoplasms

    OpenAIRE

    Heshiki, Rosana Emiko; Navarro, Paulo Lima; Ogawa, Allex Itar; Takemoto, Lucio Eidy

    2008-01-01

    Introduction: Salivary glands neoplasms represent a rare and diverse group of tumors with different characteristics. To avoid complications and unnecessary procedures, the treatment depends on an accurate diagnosis. Objective: Review the literature emphasizing the latest advances in diagnosis and treatment. Method: An electronic research was performed on MEDLINE, OVID, PubMed and SciELO databases articles in a period between 1997 and 2007. Conclusion: The proper diagnosis of salivary glands n...

  5. 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.)

  6. The Inherent Acidic Characteristics of Aged Silk

    Directory of Open Access Journals (Sweden)

    Paul Wyeth

    2008-01-01

    Full Text Available Silks are frequently a cause of concern for conservatorsand curators. Amongst other critical challenges, textileacidity is considered to pose a risk. Consequently, it iscommon practice to carry out pH measurements whenassessing condition. Enhanced acidity is usually ascribedto previous processing treatments, adsorbed pollutants,and oxidative deterioration. However, the results of thedetailed study reported in this paper suggest thatincreased acidity of silk is an expected consequence ofageing, irrespective of the effector of deterioration.Degummed Bombyx mori silk fabric was subjected to artificialageing by light, heat and heat plus high humidity, in air.The tensile strength of the fabric gradually decreasedunder each of the ageing regimes, seeming to follow firstorder decay. The pH values of saline extracts of the silkssimilarly decreased. There was a correlation between thetensile strength and the apparent acidity of the aged silks,which was independent of the ageing factor, at least to a50% drop in performance. While the tensile strength of silkwas compromised to a similar degree by high temperatureplus high humidity ageing in nitrogen, anoxic conditionsgenerated a five-fold lower increase in apparent acidity.

  7. 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.

  8. 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…

  9. 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.

  10. 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

  11. Undifferentiated salivary gland carcinomas

    DEFF Research Database (Denmark)

    Herbst, H.; Hamilton-Dutoit, S.

    2004-01-01

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

  12. Reversible Assembly of ?-Sheet Nanocrystals within Caddisfly Silk

    OpenAIRE

    Addison, J. Bennett; Weber, Warner S.; Mou, Qiushi; Ashton, Nicholas N.; Stewart, Russell J.; Holland, Gregory P.; yarger, Jeffery L.

    2014-01-01

    Nuclear magnetic resonance (NMR) and X-ray diffraction (XRD) experiments reveal the structural importance of divalent cation–phosphate complexes in the formation of ?-sheet nanocrystals from phosphorylated serine-rich regions within aquatic silk from caddisfly larvae of the species Hesperophyla consimilis. Wide angle XRD data on native caddisfly silk show that the silk contains a significant crystalline component with a repetitive orthorhombic unit cell aligned along the fiber axis with dimen...

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

    DEFF Research Database (Denmark)

    Kronqvist, Nina; Otikovs, Martins

    2014-01-01

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

  14. Silk hydrogel for cartilage tissue engineering

    OpenAIRE

    Chao, Pen-hsiu Grace; Yodmuang, Supansa; Wang, Xiaoqin; Sun, Lin; 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...

  15. The Consolidation Behavior of Silk Hydrogels

    OpenAIRE

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

    2009-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Kasinee Sawasdee

    2014-09-01

    Full Text Available 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 generation to generation, copying plant and animal patterns in nature. Silk patterns developed in three ways: 1 using mudmee patterns as a model; 2 imitating television, fashion magazines and other media; 3 following specific commission specifications of customers. Production processes are mudmee (silk blending and tammee (silk marking, which require original wooden equipment reinforced with steel for strength and electrical motors for speed. Both simple silk fibres and factory silk fibres are used and patterns are created based on traditional designs. In order to develop silk pattern production for added commercial value, original patterns with contemporary character must be chosen and expanded as bigger and more varied products, such as handbags. New silk patterns sold in local and regional markets will boost the income of people in Khon Kaen Province.

  17. Major salivary glands

    International Nuclear Information System (INIS)

    This chapter deals with two important features of treatment of malignant tumors of the parotid and submandibular gland: the lack of a satisfactory means of staging these lesions, and the all-important treatment considerations relative to the facial nerve in parotid gland malignancies. The imaging physician and the clinician should also consider that many suspected parotid mass lesions turn out to arise from structures extrinsic to the gland. The authors discuss in detail the sources of such mass lesions as well as how CT can be used to differentiate these from intrinsic lesions in the parotid and submandibular glands. Computed tomography and, perhaps in the near future, magnetic resonance imaging (MRI) will provide us with a means to diagnose these tumors earlier. This is especially true when studies are used in situations such as unexplained peripheral seventh nerve paralysis or in the early screening of patients with parotid or periparotid masses. Unfortunately, it is usually patient delay that leads to late diagnosis of palpable mass lesions in this region, and there is little that any imaging study can do to reduce this factor

  18. Fabrication of 3D porous silk scaffolds by particulate (salt/sucrose) leaching for bone tissue reconstruction.

    Science.gov (United States)

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

    2015-07-01

    Silk fibroin is a biomaterial being actively studied in the field of bone tissue engineering. In this study, we aimed to select the best strategy for bone reconstruction on scaffolds by changing various conditions. We compared the characteristics of each scaffold via structural analysis using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), the swelling ratio, water uptake, porosity, compressive strength, cell infiltration and cell viability (CCK-8). The scaffolds had high porosity with good inter pore connectivity and showed high compressive strength and modulus. In addition, to confirm bone reconstruction, animal studies were conducted in which samples were implanted in rat calvaria and investigated by micro-CT scans. In conclusion, the presented study indicates that using sucrose produces scaffolds showing better pore interconnectivity and cell infiltration than scaffolds made by using a salt process. In addition, in vivo experiments showed that hydroxyapatite accelerates bone reconstruction on implanted scaffolds. Accordingly, our scaffold will be expected to have a useful application in bone reconstruction. PMID:25849999

  19. First investigation of spider silk as a braided microsurgical suture.

    Science.gov (United States)

    Kuhbier, Joern W; Reimers, Kerstin; Kasper, Cornelia; Allmeling, Christina; Hillmer, Anja; Menger, Björn; Vogt, Peter M; Radtke, Christine

    2011-05-01

    Inhibition of axonal outgrowth accompanied by neuroma formation appears in microsurgical nerve repair as reaction to common microsuture materials like silk, nylon, or polyglycolic acid. In contrast, recent findings revealed advantages of spider silk fibers in guiding Schwann cells in nerve regeneration. Here, we asked if we could braid microsutures from native spider silk fibers. Microsutures braided of native spider dragline silk were manufactured, containing either 2 × 15 or 3 × 10 single fibres strands. Morphologic appearance was studied and tensile strength and stress-strain ratio (SSR) were calculated. The constructed spider silk sutures showed a median thickness of 25 ?m, matching the USP definition of 10-0. Maximum load and tensile strength for both spider silk microsutures were significantly more than 2-fold higher than for nylon suture; SSR was 1.5-fold higher. All values except elasticity were higher in 3 × 10 strand sutures compared to 2 × 15 strand sutures, but not significantly. In this pilot study, we demonstrate the successful manufacture of microsutures from spider silk. With regards to the mechanical properties, these sutures were superior to nylon sutures. As spider silk displays high biocompatibility in nerve regeneration, its usage in microsurgical nerve repair should be considered. PMID:21432995

  20. 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. …

  1. 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…

  2. 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)

  3. 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

  4. Ultrasound of thyroid gland

    International Nuclear Information System (INIS)

    Full text: A thyroid and parathyroid ultrasound (US) is an imaging test to check the thyroid gland and parathyroid glands and is done to: check for nodules in the thyroid gland, find out whether the thyroid gland is enlarged, to keep track of the size of the thyroid gland during treatment, look for enlarged parathyroid glands caused by disease, guide the placement of the needle during a thyroid biopsy. The thyroid gland is formed by two lobes joined by an isthmus and, in a significant percentage of individuals, the 'pyramidal lobe', a vestige of the thyroglossal duct extending upward from the isthmus. A fibrous capsule surrounds the gland and connects with intrathyroidal fibrous septa forming 'lobules' that become grossly evident in pathologic conditions. Each lobule is supplied by a single artery and contains 20 to 40 'follicles' that average 200 nm in size and contain 'colloid'. Follicles are lined by a monolayer of low-cuboidal 'follicular' cells surrounded by a basement membrane. In fine needle aspiration biopsy (FNAB) specimens, normal follicular cells are typically arranged in follicles, and monolayered sheets arranged in a honeycomb pattern with well-defined borders and nuclei which maintain polarity. Thyroid nodules are extremely common with an estimated prevalence on the basis of palpation that ranges from 3% to 7%. It has been estimated that there is a 5 to 10% lifetime risk of developing a palpable thyroid nodule, most of these nodules are benign, and cliniost of these nodules are benign, and clinicians should be as selective as possible in recommending surgical removal. Although thyroid nodules are a common incidental finding, US should not be performed as a screening test. Moreover, 20% to 48% of patients with one palpable thyroid nodule are found to have additional nodules on US investigation. Thyroid nodules are more common in elderly persons, in women, in those with iodine deficiency, and in those with a history of radiation exposure. Patients with benign thyroid nodules should undergo clinical and US follow-up. Symptomatic goiters, whether euthyroid or hyperthyroid, may be treated surgically or with radioiodine. Malignant or suspicious nodules should be treated surgically after preoperative evaluation with US and FNAB. An ultrasound can reveal which thyroid nodules are larger than 1-1.5 centimeters, requiring further evaluation for cancer. In addition to size, other nodule characteristics that can be noted on a thyroid ultrasound include the following: number of nodules, location of nodules, distinctness of borders, fluid versus solid contents, other nodule contents, such as calcium deposits, or the amount of blood flow (certain newer ultrasound machines can assess blood flow to the thyroid and its nodules). Thyroid lesions discovered on computed tomography (CT) or magnetic resonance imaging (MRI) performed for other reasons have an uncertain risk of malignancy and should undergo US evaluation before considering evaluation with FNA biopsy. Nodules are also detected infrequently by 18F-fluorodeoxyglucose positron emission tomography,but when found they are considered to have higher risk of malignancy. The annual incidence of thyroid malignancies in different parts of the world varies from 0.5 to 10 per 100,000 individuals. Despite its infrequency, it is important to remember that thyroid carcinoma is as prevalent as multiple myeloma, twice as common as Hodgkin's disease, and as frequent as cancers of the esophagus, larynx, mouth, and uterine cervix. Furthermore, thyroid cancer is the most common malignant endocrine tumor, responsible for 64% of deaths attributable to malignant endocrine neoplasms, more than all other endocrine cancers combined. Nevertheless, treatment of thyroid cancer is very successful

  5. Pituitary gland tumors

    International Nuclear Information System (INIS)

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

  6. 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.)

  7. 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.)

  8. On the Silk Production of Amasya (1750-1900

    Directory of Open Access Journals (Sweden)

    Hüsnü Yücekaya

    2013-12-01

    Full Text Available Amasya is one of the most important cities in the chain of Ottoman silk manufacture. From the standpoint of Ottoman silk production, the early role of the city was in the way of being the entrepot of Iranian silk. In later periods, it is reflected in documents that silkworm-breeding and branches of work and production depending on silk reached very important dimensions. It is observed that from the last quarter of the 18th century onward, tax records regarding silk production are mentioned more than the records concerning the tax of mizan-? harir. It is also observed that at an accelerating rate within the 18th century, records about mulberry fields and wormhouses are intensely mentioned. In line with what has been stated, it is thought that the dependency on Iranian silk decreased in time. Negative effects of the silkworm disease that was effective in the second half of the 19th century were felt in Amasya too. To the degree that it is reflected in the archival material, it is understood that government officials attended perhaps most sensitively to the Amasya silk- production. When examined under the light of the documents and the information, it is thought that there was an Amasya silk production comparable to that of Bursa. Although the city of Bursa played a dominant role in Ottoman silk production, the total production of a few cities such as Amasya was able to nearly balance the Bursa silk production or perhaps provide a production level above that of Bursa.

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

    Science.gov (United States)

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

    2015-04-01

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

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

    OpenAIRE

    Agnarsson, Ingi; Kuntner, Matjaz?; Blackledge, Todd A.

    2010-01-01

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

  11. [Cysts of the hepatoid glands].

    Science.gov (United States)

    Shabadash, S A; Zelikina, T I

    1995-01-01

    Cysts are specific rounded closed structures characteristic of some hepatoid glands. They never occur in other cutaneous glands of mammals. The cysts of the circumanal hepatoid glands of the dog and polar fox, the violet gland of the polar and common red fox, and the groin pouches of three species of gazelles were studied. The cyst is enclosed in a cellular wall saturated with glycogen. The amorphous content of the cyst is rich in hydrophobic lipids and it also contains protein. The cysts of the dog and gazelle contain also carboxylated mucopolysaccharides. The amorphous masses of the cyst are surrounded by concentric fibers rich in sulfated mucopolysaccharides. It was shown, using the circumanal glands of adult male dogs, that cysts are permanently formed from single secretory cells capable of synthesizing hydrophobic lipids before their destruction. During the involution of the hepatoid cysts (circumanal glands of an old female dog), whole acini and glandular lobes transform into cysts. PMID:7894314

  12. 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.

  13. Diagnostics of salivary gland disorders

    International Nuclear Information System (INIS)

    In this article several diagnostic techniques are described for the diagnosis of the salivary glands. Sialography can be used for chronic inflammations and obstructions. Scintiscanning is useful in the determination of function disorders and the simultaneous diagnosis of all big salivary glands. With echography it is possible to distinguish solid and cystoid tumors. Computer tomography locates space occupying processes. Still the clinical investigations and anamneses are the most important diagnostic means for disorders of the salivary glands. 34 refs.; 6 figs.; 1 table

  14. 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

  15. 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

    2014-04-01

    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.

  16. Evidence for antimicrobial activity associated with common house spider silk

    Directory of Open Access Journals (Sweden)

    Wright Simon

    2012-06-01

    Full Text Available Abstract Background Spider silk is one of the most versatile materials in nature with great strength and flexibility. Native and synthetically produced silk has been used in a wide range of applications including the construction of artificial tendons and as substrates for human cell growth. In the literature there are anecdotal reports that suggest that native spider silk may also have antimicrobial properties. Findings In this study we compared the growth of a Gram positive and a Gram negative bacterium in the presence and absence of silk produced by the common house spider Tegenaria domestica. We demonstrate that native web silk of Tegenaria domestica can inhibit the growth of the Gram positive bacterium, Bacillus subtilis. No significant inhibition of growth was detected against the Gram negative bacterium, Escherichia coli. The antimicrobial effect against B. subtilis appears to be short lived thus the active agent potentially acts in a bacteriostatic rather than bactericidal manner. Treatment of the silk with Proteinase K appears to reduce the ability to inhibit bacterial growth. This is consistent with the active agent including a protein element that is denatured or cleaved by treatment. Tegenaria silk does not appear to inhibit the growth of mammalian cells in vitro thus there is the potential for therapeutic applications.

  17. 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.

  18. Evidence for an immune function of lepidopteran silk proteins.

    Science.gov (United States)

    Korayem, Ahmed M; Hauling, Thomas; Lesch, Christine; Fabbri, Marco; Lindgren, Malin; Loseva, Olga; Schmidt, Otto; Dushay, Mitchell S; Theopold, Ulrich

    2007-01-12

    Hemolymph coagulation stops bleeding and protects against infection. Clotting factors include both proteins that are conserved during evolution as well as more divergent proteins in different species. Here we show that several silk proteins also appear in the clot of the greater wax moth Galleria mellonella. RT-PCR analysis reveals that silk proteins are expressed in immune tissues and induced upon wounding in both Galleria and Ephestia kuehniella, a second pyralid moth. Our results support the idea that silk proteins were co-opted for immunity and coagulation during evolution. PMID:17126296

  19. Chitin in the Silk Gland Ducts of the Spider Nephila edulis and the Silkworm Bombyx mori

    OpenAIRE

    Davies, Gwilym J. G.; Knight, David P.; Vollrath, Fritz

    2013-01-01

    Here we report the detection and localisation of chitin in the cuticle of the spinning ducts of both the spider Nephila edulis and the silkworm Bombyx mori. Our observations demonstrate that the duct walls of both animals contain chitin notwithstanding totally independent evolutionary pathways of the systems. We conclude that chitin may well be an essential component for the construction of spinning ducts; we further conclude that in both species chitin may indicate the evolutionary origin of...

  20. Meibomian Gland Dysfunction and Treatment (Posterior Blepharitis)

    Science.gov (United States)

    ... J AAPOS American Association for Pediatric Ophthalmology and Strabismus Eye Terms Conditions Frequently Asked Questions Español Condiciones Chinese Conditions Meibomian Gland Dysfunction and Treatment What are Meibomian (Oil) Glands? Meibomian glands are ...