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Phase behavior and hydration of silk fibroin.  

Science.gov (United States)

The osmotic stress method was applied to study the thermodynamics of supramolecular self-assembly phenomena in crystallizable segments of Bombyx mori silkworm silk fibroin. By controlling compositions and phases of silk fibroin solution, the method provided a means for the direct investigation of microscopic and thermodynamic details of these intermolecular interactions in aqueous media. It is apparent that as osmotic pressure increases, silk fibroin molecules are crowded together to form silk I structure and then with further increase in osmotic pressure become an antiparallel beta-sheet structure, silk II. A partial ternary phase diagram of water-silk fibroin-LiBr was constructed based on the results. The results provide quantitative evidence that the silk I structure must contain water of hydration. The enhanced control over structure and phase behavior using osmotic stress, as embodied in the phase diagram, could potentially be utilized to design a new route for water-based wet spinning of regenerated silk fibroin. PMID:15132657

Sohn, Sungkyun; Strey, Helmut H; Gido, Samuel P

2004-01-01

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Silk Fibroin Based Porous Materials  

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

Shuqin Yan

2009-12-01

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Thermal crystallization mechanism of silk fibroin protein  

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

Hu, Xiao

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Controlling silk fibroin particle features for drug delivery  

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

Lammel, Andreas; Hu, Xiao; Park, Sang-hyug; Kaplan, David L.; Scheibel, Thomas

2010-01-01

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

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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-phosphorylated fibroin solutions. Fourier transform infra-red spectroscopy was used to determine the specific P-OH vibration peak, confirming the phosphorylation of the regenerated silk fibroin solution. Differential scanning calorimetry showed that phosphorylation altered the intra- and inter-molecular interactions. Further experiments demonstrated that phosphorylation can be used to tailor the hydrophylicity/hydrophobicity ratio as well as the crystalinity of silk fibroin films. Release profiling of a model drug was highly dependent on silk modification level. Cytotoxicity assays showed that exposure to lixiviates of phosphorylated films only slightly affected cellular metabolism and proliferation, although direct contact resulted in a strong direct correlation between phosphorylation level and cell proliferation. This new method for tuning silk biomaterials to obtain specific structural and biochemical features can be adapted for a wide range of applications. Phosphorylation of silk fibroins may be applied to improve the cytocompatibility of any silk-based device that is considered to be in contact with live animals or human tissues. PMID:25087614

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

2014-10-01

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A novel electrospun silk fibroin/hydroxyapatite hybrid nanofibers  

International Nuclear Information System (INIS)

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

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A novel electrospun silk fibroin/hydroxyapatite hybrid nanofibers  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-11-15

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Nanofeatured silk fibroin membranes for dermal wound healing applications.  

Science.gov (United States)

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

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

2015-01-01

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

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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.

Muzafar A Bhat, Punyavathi and Manjunatha H Boregowda*

2014-07-01

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Development stage-specific expression of fibroin in the silk worm Bombyx mori is regulated translationally.  

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The contents of fibroin H RNA as a function of development have been quantitated in the posterior silk glands of Bombyx mori larvae on different days of 4th and 5th instars. The fibroin RNA levels increased during the feeding stages of larvae and the RNA got completely degraded during the interim moult. The patterns of accumulation of fibroin RNA were similar in both the instars. Although there was considerable increase in the fibroin RNA content during the 5th larval instar, the relative abundance of fibroin RNA in the total RNA was fairly constant during the 4th and 5th instars. The increased content of fibroin RNA in 5th instar was the consequence of an overall increase in transcription accompanying the development progress, rather than specific increase only in fibroin transcription. The contents of fibroin protein in the 4th and 5th instars of development have also been quantitated making use of a sensitive radioimmune assay with a purified, antifibroin antibody. There were substantial differences between 4th and 5th instars in the absolute fibroin contents as well as the relative proportion of fibroin in the total proteins. These results implied that although the fibroin gene was transcribed at the same efficiency during the 4th and 5th instars, the translational efficiency was much lower during the 4th instar. The extent of polyadenylation of fibroin RNA was similar in both instars. However, there was a two-fold increase in the polysome association of fibroin RNA in the 5th instar. Over and above this, there was substantial increase during the 5th instar in the contents of those tRNAs. (e.g. Gly, Ala and Ser) which are abundantly represented in fibroin and therefore directly related to the expression of fibroin. The increased polysome association of fibroin mRNA and the adequate supply of cognate tRNAs in the 5th instar, together contributes to the translational regulation of fibroin in a developmental stage-specific manner. Based on these observations, we propose that translational regulation plays a major role in the development stage-specific synthesis of fibroin in Bombyx mori. PMID:1725868

Patel, C V; Gopinathan, K P

1991-01-01

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The effects of different sterilization methods on silk fibroin  

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

Xiaosong Gu

2011-05-01

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Amorphous Silk Fibroin Membranes for Separation of CO2  

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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.

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

2009-01-01

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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)

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Conductive Au nanowires regulated by silk fibroin nanofibers  

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

Dong, Bo-Ju; Lu, Qiang

2014-03-01

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Microdissection of black widow spider silk-producing glands.  

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

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

2011-01-01

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Gelation of Antheraea pernyi Silk Fibroin Accelerated by Shearing  

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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 a...

Yu Liu; Siyong Xiong; Renchuan You; Mingzhong Li

2013-01-01

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Silk fibroin rods for sustained delivery of breast cancer therapeutics.  

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A silk-protein based reservoir rod was developed for zero-order and long-term sustained drug delivery applications. Silk reservoir rod formulations were processed in three steps. First, a regenerated silk fibroin solution, rich in random-coil content was transformed into a tubular silk film with controllable dimensions, uniform film morphology and a structure rich in silk II, ?-sheet content via "film-spinning." Second, the drug powder was loaded into swollen silk tubes followed by tube end clamping. Last, clamped silk tube ends were sealed completely via dip coating. Anastrozole, an FDA approved active ingredient for the treatment of breast cancer, was used as a model drug to investigate viability of the silk reservoir rod technology for sustained drug delivery. The in vitro and in vivo pharmacokinetic data (in a female Sprague-Dawley rat model) analyzed via liquid chromatography-tandem mass spectroscopy indicated zero-order release for 91 days. Both in vitro and in vivo anastrozole release rates could be controlled simply by varying silk rod dimensions. The swelling behavior of silk films and zero-order anastrozole release kinetics indicated practically immediate film hydration and formation of a linear anastrozole concentration gradient along the silk film thickness. The dependence of anastrozole release rate on the overall silk rod dimensions was in good agreement with an essentially diffusion-controlled sustained release from a reservoir cylindrical geometry. In vivo results highlighted a strong in vitro-in vivo pharmacokinetic correlation and a desirable biocompatibility profile of silk reservoir rods. During a 6-month implantation in rats, the apparent silk molecular weight values decreased gradually, while rod dry mass and ?-sheet crystal content values remained essentially constant, providing a suitable timeframe for controlled, long-term sustained delivery applications. Overall, the silk reservoir rod may be a viable candidate for sustained delivery of breast cancer therapeutics. PMID:25009069

Yucel, Tuna; Lovett, Michael L; Giangregorio, Raffaella; Coonahan, Erin; Kaplan, David L

2014-10-01

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

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

Chuleerat Wongnarat

2013-01-01

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Effect of plasma-irradiated silk fibroin in bone regeneration.  

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

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

2014-09-01

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

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

Jin Huanyu

2013-01-01

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

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

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

2014-06-01

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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.

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

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

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

2012-08-01

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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)

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

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

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

2014-11-01

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Development of artificial dermis using 3D electrospun silk fibroin nanofiber matrix.  

Science.gov (United States)

Several auto- or alloplastic dermal substitutes have been used for full thickness skin defects. However, there is no ideal dermal substitute that is biocompatible and offers adequate mechanical properties and sufficient thickness and volume. Silk fibroin can be considered a possible alternative material for the construction of dermal substitutes. Nanofibers fabricated by electrospinning silk fibroin were considered an excellent candidate due to their desirable biocompatibility. However, it is generally difficult for cells to infiltrate the electrospun silk fibroin due to its small pore size. To overcome this challenge, a key parameter is the control of the pore size of silk fibroin electrospun such that cells can easily infiltrate into the nanofibers and proliferate internally. In this work, a novel approach is introduced by dropping two different size NaCl crystals above the rotating collector, which become incorporated into the nanofibers. The structures and properties of the, resulting electrospun silk fibroin were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and its wound healing effect for a full thickness skin defect was compared with Matriderm. Although the dermal regenerative effect of the 3D-SF (3D electrospun silk fibroin nanofiber matrix) was similar to that of Matriderm, the 3D-SF was almost completely degraded and did not induce wound contracture like Matriderm. We suggest that 3D-SF can be applied to the treatment of full thickness skin defects. PMID:24804550

Lee, Ok Joo; Ju, Hyung Woo; Kim, Ji Heui; Lee, Jung Min; Ki, Chang Seok; Kim, Jung-Ho; Moon, Bo Mi; Park, Hyun Jung; Sheikh, Faheem A; Park, Chan Hum

2014-07-01

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

Science.gov (United States)

In this study, the characteristics of silk fibroin films obtained from regenerated aqueous silk fibroin solution of various races were evaluated. Three races based on original sources of silkworms were selected: Nangnoi-Sisaket 1 (NN), Nakhon Ratchasima 1 (K1), and Nakhon Ratchasima 2 (K8). The Tg and Td of silk fibroin films were around 147-156°C and 277-279°C, respectively. FTIR result revealed that all silk fibroin films had beta sheet conformation. K1 and K8 films were found to be more hydrophilic than NN film. From in vitro tests using L929 mouse fibroblast and rat bone marrow-derived stem cells (rMSCs), the cell attachment was slightly greater on K1 film than the other two films. The enhanced cell growth on K1 film might be related to its slightly high hydrophilicity and the higher content of serine. The result of osteogenic differentiation test showed that alkaline phosphatase and deposited mineral of rMSCs were higher on all silk fibroin films than on tissue culture plate. K1 film tended to promote osteogenic differentiation of rMSCs to a higher extent than NN and K8 films. K1 silk fibroin film exhibited a higher potential to support cell attachment, proliferation, and differentiation than other two films. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1639-1647, 2014. PMID:24652683

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

2014-11-01

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Microrheological Studies of Regenerated Silk Fibroin Solution by Video Microscopy  

CERN Document Server

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

Raghu, A; Somashekar, R; Ananthamurthy, Sharath

2007-01-01

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Antimicrobial Silk Fibroin Hydrogel Instantaneously Induced by Cationic Surfactant  

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

Shan Sun

2013-01-01

30

Silk Fibroin Film Loaded Chlorhexidine Diacetate: Interaction and Characteristics  

Directory of Open Access Journals (Sweden)

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

N. Noi

2009-01-01

31

Nucleation of hydroxyapatite on Antheraea pernyi (A. pernyi) silk fibroin film.  

Science.gov (United States)

Antheraea pernyi (A. pernyi) silk fibroin, which is spun from a wild silkworm, has increasingly attracted interest in the field of tissue engineering. The aim of this study was to investigate the nucleation of hydroxyapatite (HAp) on A. pernyi fibroin film. Von Kossa staining proved that A. pernyi fibroin had Ca binding activity. The A. pernyi fibroin film was mineralized with HAp crystals by alternative soaking in calcium and phosphate solutions. Spherical crystals were nucleated on the A. pernyi fibroin film according to scanning electron microscopeimaging results. The FT-IR and X-ray diffraction spectra confirmed that these spherical crystals were HAp. The results of in vitro cell culture using MG-63 cells demonstrated that the mineralized A. pernyi fibroin film showed excellent cytocompatibility and sound improvement of the MG-63 cellviability. PMID:24211958

Yang, Mingying; Shuai, Yajun; Zhou, Guanshan; Mandal, Namita; Zhu, Liangjun

2014-01-01

32

Fabrication and characterization of silk-fibroin-coated quantum dots.  

Science.gov (United States)

We report a novel technique of directly coating colloidal CdSe/ZnS core/shell quantum dots (QDs) with silk fibroin (SF), a protein derived from the Bombyx mori silk worm. The approach results in protein-modified QDs with little or no particle aggregation, and mitigates the issue of biocompatibility. QDs have desirable optical properties, such as narrow-band emission, broadband absorption, high quantum yield, and high resistance to photobleaching. SF is a fibrous protein polymer with a biomimetic peptide sequence, water and oxygen permeability, low inflammatory response, no thrombogenecity, and cellular biocompatibility, which are desirable properties for in vivo delivery. Combining the unique properties of QDs with the biocompatibility profile of SF, the approach produces particles representing a powerful tool for numerous in vivo and in vitro applications. The design and preparation of these protein-modified QDs conjugates is reported along with functional characterization using luminescence, transmission electron microscope (TEM), and atomic force microscope (AFM). Additionally, we report results obtained using the QDs conjugates as a fluorescent label for bioimaging HEYA8 ovarian cancer cells. PMID:19304498

Nathwani, Bhavik B; Jaffari, Mona; Juriani, Ameet R; Mathur, Anshu B; Meissner, Kenith E

2009-03-01

33

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

Science.gov (United States)

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

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

2014-01-13

34

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

Directory of Open Access Journals (Sweden)

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.

Raquel Farias Weska

2009-06-01

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

Scientific Electronic Library Online (English)

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

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

2009-06-01

36

Fabrication of silk fibroin nanoparticles for controlled drug delivery  

International Nuclear Information System (INIS)

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

37

Fabrication of silk fibroin nanoparticles for controlled drug delivery  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-03-15

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Preparation of Silk Fibroin Microspheres and Its Cytocompatibility  

Directory of Open Access Journals (Sweden)

Full Text Available The goal of this proof-of-concept study was the fabrication of porous silk fibroin (SF microspheres which could be used as cell culture carriers under very mild processing conditions. The SF solution was differentiated into droplets which were induced by a syringe needle in the high-voltage electrostatic field. They were collected and frozen in liquid nitrogen and water in droplets formed ice crystals which sublimated during lyophilization and a great quantity of micropores shaped in SF microspheres. Finally, the microspheres were treated in ethanol so as to transfer the molecular conformation into ?-sheet and then they were insoluble in water. SF particles were spherical in shape with diameters in the range of 208.4 ?m to 727.3 ?m, while the pore size on the surface altered from 0.3 ?m to 10.7 ?m. In vitro, the performances of SF microspheres were assessed by culturing L-929 fibroblasts cells. Cells were observed to be tightly adhered and fully extended; also a large number of connections were established between cells. After 5-day culture, it could be observed under a confocal laser scanning microscope that the porous microenvironment offered by SF particles accelerated proliferation of cells significantly. Furthermore, porous SF particles with smaller diameters (200 - 300 ?m might promote cell growth better. These new porous SF microspheres hold a great potential for cell culture carriers and issue engineering scaffolds.

Jing Qu

2013-01-01

39

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)

40

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

Science.gov (United States)

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

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

2014-11-01

 
 
 
 
41

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)

42

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

43

On the strength of ?-sheet crystallites of Bombyx mori silk fibroin.  

Science.gov (United States)

Silk fibroin, a natural multi-domain protein, has attracted great attention due to its superior mechanical properties such as ultra-high strength and stretchability, biocompatibility, as well as its versatile biodegradability and processability. It is mainly composed of ?-sheet crystallites and amorphous domains. Although its strength is well known to be controlled by the dissociation of protein chains from ?-sheet crystallites, the way that water as the solvent affects its strength and the reason that its theoretically predicted strength is several times higher than experimental measurement remain unclear. We perform all-atom molecular dynamics simulations on a ?-sheet crystallite of Bombyx mori silk. We find that water solvent reduces the number and strength of hydrogen bonds between ?-chains, and thus greatly weakens the strength of silk fibroin. By dissociating protein chains at different locations from the crystallite, we also find that the pulling strength for the interior chains is several times higher than that for the surface/corner chains, with the former being consistent with the theoretically predicted value, while the latter on par with the experimental value. It is shown that the weakest rupture strength controls the failure strength of silk fibre. Hence, this work sheds light on the role of water in the strength of silk fibroin and also provides clues on the origin of the strength difference between theory and experiment. PMID:24789564

Cheng, Yuan; Koh, Leng-Duei; Li, Dechang; Ji, Baohua; Han, Ming-Yong; Zhang, Yong-Wei

2014-07-01

44

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

Science.gov (United States)

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

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

2014-01-01

45

Effects of sterilization methods on the physical, chemical, and biological properties of silk fibroin membranes.  

Science.gov (United States)

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 jeopardize the functionality of medical devices. The aim of this study was to analyze the influence of different sterilization methods in the physical, chemical, and biological characteristics of dense and porous silk fibroin membranes. Silk fibroin membranes were treated by several procedures: immersion in 70% ethanol solution, ultraviolet radiation, autoclave, ethylene oxide, and gamma radiation, and were analyzed by scanning electron microscopy, Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction, tensile strength and in vitro cytotoxicity to Chinese hamster ovary cells. The results indicated that the sterilization methods did not cause perceivable morphological changes in the membranes and the membranes were not toxic to cells. The sterilization methods that used organic solvent or an increased humidity and/or temperature (70% ethanol, autoclave, and ethylene oxide) increased the silk II content in the membranes: the dense membranes became more brittle, while the porous membranes showed increased strength at break. Membranes that underwent sterilization by UV and gamma radiation presented properties similar to the nonsterilized membranes, mainly for tensile strength and FTIR results. PMID:24259492

de Moraes, Mariana Agostini; Weska, Raquel Farias; Beppu, Marisa Masumi

2014-05-01

46

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

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

2008-12-01

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

Science.gov (United States)

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 titanium surface to facilitate the initial cell adhesion followed by improved cell spreading and better mineralization in order to achieve enhanced osseointegration. The immunological responses along with the effect of cytokines on osteoblast adhesion and function are investigated. The non-mulberry fibroin performs better in the context of the cell adherence and differentiation, which lead to better mineralization. The results indicate that the silk fibroin from non-mulberry source can be used for better osteogenesis on orthopedic implants. PMID:24752225

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

2014-01-01

48

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

International Nuclear Information System (INIS)

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

49

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

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

Renchuan You

2014-06-01

50

Enhancing the toughness of regenerated silk fibroin film through uniaxial extension.  

Science.gov (United States)

Films of regenerated silk fibroin (RSF) are usually brittle and weak, which prevents its wide application as a structural material. To improve the mechanical properties of RSF film, uniaxial extension under swollen conditions was employed to introduce preferred orientation of molecular chains of silk fibroin. Such a prestretching treatment resulted in the strain at break, ultimate stress, Young's modulus, and energy to break along the predrawn direction of the RSF film increasing from approximate 5%, 90 MPa, 2.7 GPa, and 2.1 kJ/kg to 35%, 169 MPa, 3.5 GPa, and 38.9 kJ/kg, respectively, which is an attractive combination of strength and toughness. The mechanism of these property enhancements was investigated using techniques such as small-angle X-ray scattering, wide-angle X-ray diffraction, atomic force microscopy, and dynamic mechanical analysis. PMID:20879759

Yin, Jianwei; Chen, Erqiang; Porter, David; Shao, Zhengzhong

2010-11-01

51

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)

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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

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-03-01

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

Science.gov (United States)

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

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

2013-11-01

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

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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...

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

2014-01-01

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

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

Hong-sheng Wang

2010-09-01

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Guiding the behaviors of human umbilical vein endothelial cells with patterned silk fibroin films.  

Science.gov (United States)

Silk fibroin is an ideal blood vessel substitute due to its advantageous qualities including variable size, good suture retention, low thrombogenicity, non-toxicity, non-immunogenicity, biocompatibility, and controllable biodegradation. In this study, silk fibroin films with a variety of surface patterns (e.g. square wells, round wells plus square pillars, square pillars, and gratings) were prepared for in vitro characterization of human umbilical vein endothelial cell's (HUVEC) response. The affects of biomimetic length-scale topographic cues on the cell orientation/elongation, proliferation, and cell-substrate interactions have been investigated. The density of cells is significantly decreased in response to the grating patterns (70±3nm depth, 600±8nm pitch) and the square pillars (333±42nm gap). Most notably, we observed the contact guidance response of filopodia of cells cultured on the surface of round wells plus square pillars. Overall, our data demonstrates that the patterned silk fibroin films have an impact on the behaviors of human umbilical vein endothelial cells. PMID:25016547

Du, Xuejiao; Wang, Yanyun; Yuan, Lin; Weng, Yuyan; Chen, Gaojian; Hu, Zhijun

2014-10-01

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

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

M. Fazley Elahi

2014-04-01

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

Science.gov (United States)

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

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

2007-02-01

60

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-06-01

 
 
 
 
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Fabrication of poly(lactic-co-glycolic acid) scaffolds containing silk fibroin scaffolds for tissue engineering applications.  

Science.gov (United States)

The present study deals with the fabrication of poly(lactic-co-glycolic acid) (PLGA) scaffolds modified with silk fibroin for biomedical application. The PLGA solutions were added with salt particles and pressed with high pressures; which were further subjected to salt leaching resulting in the creation of large sized pores in the PLGA scaffolds. To fill up these pores, 2%, 4%, and 8% of silk solutions were added, however, the addition created extra small sized pores. The scaffolds were characterized by various state of techniques; the scanning electronic microscopy revealed the large sized pores in the pristine scaffold can be tailored into smaller architecture by the addition of silk fibroin. The contact angle measurements confirmed the introduction of silk helped to change the hydrophobic nature of PLGA into hydrophilic, which is the main constrain for PLGA. The mechanical properties of scaffold can be easily improved by applying the higher amounts of silk into the scaffolds. The thermal gravimetric analyses and fourier transform infrared spectroscopy confirmed the presence of silk fibroin in scaffolds. The cell viability and cell attachment was checked by culturing the scaffolds with NIH 3T3 fibroblasts and chondrocytes. Furthermore, these results revealed that the introduction of silk had significant impact on the viability of fibroblast also had a good affinity for cell attachment and infiltration of human chondrocytes in scaffolds after culturing the cells for 2 and 5 weeks of time. PMID:24026912

Ju, Hyung Woo; Sheikh, Faheem A; Moon, Bo Mi; Park, Hyun Jung; Lee, Ok Joo; Kim, Jung Ho; Eun, Jang Ji; Khang, Gilson; Park, Chan Hum

2014-08-01

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

Science.gov (United States)

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

Zhang, Jian-Guang; Mo, Xiu-Mei

2013-06-01

63

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

International Nuclear Information System (INIS)

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

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Rheological properties of native silk fibroins from domestic and wild silkworms, and flow analysis in each spinneret by a finite element method.  

Science.gov (United States)

Silkworms can produce strong and tough fibers at room temperature and from an aqueous solution. Therefore, it seems useful to study the mechanism of fiber formation by silkworms for development of synthetic polymers with excellent mechanical properties. The rheological behaviors of native silk dopes stored in the silk glands of Bombyx mori and Samia cynthia ricini were clarified, and flow simulations of the dopes in each spinneret were performed with a Finite Element Method. Dynamic viscoelastic measurements revealed that silk fibroin stored in silk glands forms a transient network at room temperature, and that the molecular weight for the network node corresponds to the molecular weight of a heterodimer of H-chain and L-chain (B. mori) and a homodimer of H-chains (S. c. ricini), respectively. Also, each dope exhibited zero-shear viscosity and then shear thinning like polymer melts. In addition, shear thickening due to flow-induced crystallization was observed. The critical shear rate for crystallization of B. mori dopes was smaller than that of S. c. ricini dopes. From the flow simulation, it is suggested that domestic and wild silkworms are able to crystallize the dopes in the stiff plate region by controlling shear rate using the same magnitude of extrusion pressure despite differences in rheological properties. PMID:19317399

Moriya, Motoaki; Roschzttardtz, Frederico; Nakahara, Yusuke; Saito, Hitoshi; Masubuchi, Yuichi; Asakura, Tetsuo

2009-04-13

65

New silk protein: modification of silk protein by gene engineering for production of biomaterials.  

Science.gov (United States)

The interest in silk fibroin morphology and structure have increased due to its attractiveness for bio-related applications. Silk fibers have been used as sutures for a long time in the surgical field, due to the biocompatibility of silk fibroin fibers with human living tissue. In addition, it has been demonstrated that silk can be used as a substrate for enzyme immobilization in biosensors. A more complete understanding of silk structure would provide the possibility to further exploit silk fibroin for a wide range of new uses, such as the production of oxygen-permeable membranes and biocompatible materials. Silk fibroin-based membranes could be utilized as soft tissue compatible polymers. Baculovirus-mediated transgenesis of the silkworm allows specific alterations in a target sequence. Homologous recombination of a foreign gene downstream from a powerful promoter, such as the fibroin promoter, would allow the constitutive production of a useful protein in the silkworm and the modification of the character of silk protein. A chimeric protein consisted of fibroin and green fluorescent protein was expressed under the control of fibroin in the posterior silk gland and the gene product was spun into the cocoon layer. This technique, gene targeting, will lead to the modification and enhancement of physicochemical properties of silk protein. PMID:11763506

Mori, H; Tsukada, M

2000-08-01

66

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

Science.gov (United States)

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

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

2013-10-14

67

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

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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 ...

Srihanam Prasong

2011-01-01

68

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

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

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

2009-03-01

69

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.

70

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

71

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

Energy Technology Data Exchange (ETDEWEB)

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

Bai Liqiang [Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, College of Materials and Textile, Zhejiang Sci-Tech University, Xiasha Higher Education Park, Hangzhou 310018 (China); Zhu Liangjun; Min Sijia [College of Animal Sciences, Zhejiang University, Hangzhou 310029 (China); Liu Lin; Cai Yurong [Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, College of Materials and Textile, Zhejiang Sci-Tech University, Xiasha Higher Education Park, Hangzhou 310018 (China); Yao Juming [Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, College of Materials and Textile, Zhejiang Sci-Tech University, Xiasha Higher Education Park, Hangzhou 310018 (China)], E-mail: yaoj@zstu.edu.cn

2008-03-15

72

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)

73

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

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

Chirapha Butiman

2012-07-01

74

Preparation and Characterization of Insoluble Silk Fibroin/Chitosan Blend Films  

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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.

Mariana Agostini de Moraes

2010-12-01

75

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

76

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-04-24

77

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.

78

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

Science.gov (United States)

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.

Wang, Song; Gao, Zhen; Li, Erlin; Su, Caoning; Zhu, Hesun

2008-11-01

79

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-11-15

80

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

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

Yodthong Baimark

2009-01-01

 
 
 
 
81

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

Science.gov (United States)

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

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

2013-11-01

82

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

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

Vishal Gupta

2009-05-01

83

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

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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. PMID:21817543

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

2008-01-16

84

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-01-16

85

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)

86

Collagen/silk fibroin bi-template induced biomimetic bone-like substitutes.  

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A novel bi-template induced co-assembly method was employed to fabricate biomimetic bone substitute materials, collagen (COL)-fibroin/hydroxyapatite (COL-SF/HA) composite by using a combination of Type I COL and silk fibroin (SF) molecular templates. As a control, COL/HA and SF/HA composites were also synthesized via single-template assembly technology. The structure and morphology of the resulting assembly composites were investigated by X-ray diffractometer, Fourier transform infrared spectra, transmission electron microscope, and thermogravimetric analysis. Their sizes and size distributions were measured by DLS. The results indicated that the mineral phases in COL-SF/HA, COL-HA, and SF-HA composites were needle-like nano-HA crystals. In comparison to those in COL-HA and SF-HA, the mineral phase in COL-SF/HA displayed smaller size and more narrow distribution. Of all above biomimetic composites, the HA was well assembled with molecular template(s), and the organic content of the composite was about 12%-20%, which was quite similar to the natural bone in composition. CD and SDS-PAGE were used to examine the secondary structure and subunit composition of template proteins. The results revealed that the spatial structure of co-assembly template proteins played a pivotal role in controlling and regulating HA crystal nucleation and growth. Based on the experimental results above, a possible co-assembly mechanism for the HA growing on fibrous bi-template proteins was suggested. PMID:19705470

Wang, Jianglin; Zhou, Wei; Hu, Wei; Zhou, Lei; Wang, Shenqi; Zhang, Shengmin

2011-12-01

87

An investigation into the effect of potassium ions on the folding of silk fibroin studied by generalized two-dimensional NMR-NMR correlation and Raman spectroscopy.  

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We used generalized two-dimensional NMR-NMR correlation to examine the effect of potassium ions on the conformation transition in silk fibroin to investigate the possibility that the fairly high K+ ion content found in the distal end of silk-secreting ducts in the silkworms could have a bearing on natural formation of the silk fiber. This has enabled us to propose a detailed mechanism for the transition process. Our evidence indicates that increasing the [K+] from 0 to 3.7 mg.g(-1) in the silk fibroin, as is thought to occur as the silk fibroin moves through the secretory pathway to the spigot, produces a sequence of secondary structural changes: helix and/or random coil-->helix-like-->beta-sheet-like-->beta-sheet. The sequence is the same as that produced in silk fibroin films by decreasing the pH of fibroin from 6.8 to 4.8. In addition, we used Raman spectroscopy to study the effect of K+ ions on the Fermi doublet resonance of the tyrosyl phenolic ring at 850 and 830 cm(-1). The intensity ratio I(850)/I(830) at these wave numbers indicated that the hydrogen bonding formed by the tyrosyl phenolic-OH becomes more stable with an increase in the K+ ion concentration as above. Our investigation on the effect of K+ ions on fibroin may help provide a theoretical basis for understanding the natural silk-spinning process and the conditions required for biomimetic spinning. It may also have relevance to the aggregation of other beta-sheet proteins, including prion proteins, neurofibrillary proteins and amyloid plaques. PMID:18081855

Ruan, Qing-Xia; Zhou, Ping; Hu, Bing-Wen; Ji, Dan

2008-01-01

88

Synthesis of silk fibroin-glycopolypeptide conjugates and their recognition with lectin.  

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Silk fibroin (SF), the natural fibrous protein created by the Bombyx mori silk worm, is being increasingly explored as a biomaterial for tissue engineering due to its excellent mechanical strength, high oxygen/water permeability, and biocompatibility. It is also well known that surface modification of SF with organic ligands such as the extracellular protein binding Arg-Gly-Asp (RGD) peptides help adhesion and proliferation of cells better-a key requirement for it to function as extracellular matrices. In this work, we have conjugated synthetic glycopolypeptides (GPs) that were synthesized by controlled ring-opening polymerization of ?-manno-lys N-carboxyanhydrides (NCAs) onto SF by using Cu catalyzed click reaction to synthesize a new hybrid material (SF-GP), which we believe will have both the mechanical properties of native SF and the molecular recognition property of the carbohydrates in the GP. By controlling the amount of GP grafted onto SF, we have made three SF-GP conjugates that differ in their ability to assemble into films. SF-GP conjugates having a very high content of GP formed completely water-soluble brush-like polymer that displayed very high affinity toward the lectin concanavalin-A (Con-A). Films cast from SF-GP conjugates using lower amounts of grafted GP were more stable in water, and the stability can be modulated by varying the amount of GP grafted. The water-insoluble film SF-GP(25) was also found to bind to fluorescently labeled Con-A, as was seen by confocal microscopy. Such SF-GP hybrid films may be useful as mimics of extracellular matrices for tissue engineering. PMID:22967089

Das, Soumen; Pati, Debasis; Tiwari, Neha; Nisal, Anuya; Sen Gupta, Sayam

2012-11-12

89

Silk fibroin/chondroitin sulfate/hyaluronic acid ternary scaffolds for dermal tissue reconstruction.  

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The fabrication of new dermal substitutes providing mechanical support and cellular cues is urgently needed in dermal reconstruction. Silk fibroin (SF)/chondroitin sulfate (CS)/hyaluronic acid (HA) ternary scaffolds (95-248?m in pore diameter, 88-93% in porosity) were prepared by freeze-drying. By the incorporation of CS and HA with the SF solution, the chemical potential and quantity of free water around ice crystals could be controlled to form smaller pores in the SF/CS/HA ternary scaffold main pores and improve scaffold equilibrium swelling. This feature offers benefits for cell adhesion, survival and proliferation. In vivo SF, SF/HA and SF/CS/HA (80/5/15) scaffolds as dermal equivalents were implanted onto dorsal full-thickness wounds of Sprague-Dawley rats to evaluate wound healing. Compared to SF and SF/HA scaffolds, the SF/CS/HA (80/5/15) scaffolds promoted dermis regeneration, related to improved angiogenesis and collagen deposition. Further, vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) expression in the SF/CS/HA (80/5/15) groups were investigated by immunohistochemistry to assess the mechanisms involved in the stimulation of secretion of VEGF, PDGF and bFGF and accumulation of these growth factors related to accelerated wound process. These new three-dimensional ternary scaffolds offer potential for dermal tissue regeneration. PMID:23419553

Yan, Shuqin; Zhang, Qiang; Wang, Jiannan; Liu, Yu; Lu, Shenzhou; Li, Mingzhong; Kaplan, David L

2013-06-01

90

Genipin-crosslinked silk fibroin/hydroxybutyl chitosan nanofibrous scaffolds for tissue-engineering application.  

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To improve water-resistant ability and mechanical properties of silk fibroin (SF)/hydroxybutyl chitosan (HBC) nanofibrous scaffolds for tissue-engineering applications, genipin, glutaraldehyde (GTA), and ethanol were used to crosslink electrospun nanofibers, respectively. The mechanical properties of nanofibrous scaffolds were obviously improved after 24 h of crosslinking with genipin and were superior to those crosslinked with GTA and ethanol for 24 h. SEM indicated that crosslinked nanofibers with genipin and GTA vapor had good water-resistant ability. Characterization of the microstructure (porosity and pore structure) demonstrated crosslinked nanofibrous scaffolds with genipin and GTA vapor had lager porosities and mean diameters than those with ethanol. Characterization of FTIR-ATR and (13)C NMR clarified both genipin and GTA acted as crosslinking agents for SF and HBC. Furthermore, genipin could induce SF conformation from random coil or ?-helix to ?-sheet. Although GTA could also successfully crosslink SF/HBC nanofibrous scaffolds, in long run, genipin maybe a better method due to lower cytotoxicity than GTA. Cell viability studies and wound-healing test in rats clarified that the genipin-crosslinked SF/HBC nanofibrous scaffolds had a good biocompatibility both in vitro and in vivo. These results suggested that genipin-crosslinked SF/HBC nanofibrous scaffolds might be potential candidates for wound dressing and tissue-engineering scaffolds. PMID:20824649

Zhang, Kuihua; Qian, Yongfang; Wang, Hongsheng; Fan, Linpeng; Huang, Chen; Yin, Anlin; Mo, Xiumei

2010-12-01

91

Integrated trilayered silk fibroin scaffold for osteochondral differentiation of adipose-derived stem cells.  

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Repairing osteochondral defects (OCD) remains a formidable challenge due to the high complexity of native osteochondral tissue and the limited self-repair capability of cartilage. Osteochondral tissue engineering is a promising strategy for the treatment of OCD. In this study, we fabricated a novel integrated trilayered scaffold using silk fibroin and hydroxyapatite by combining paraffin-sphere leaching with a modified temperature gradient-guided thermal-induced phase separation (TIPS) technique. This biomimetic scaffold is characterized by three layers: a chondral layer with a longitudinally oriented microtubular structure, a bony layer with a 3D porous structure and an intermediate layer with a dense structure. Live/dead and CCK-8 tests indicated that this scaffold possesses good biocompatibility for supporting the growth, proliferation, and infiltration of adipose-derived stem cells (ADSCs). Histological and immunohistochemical stainings and real-time polymerase chain reaction (RT-PCR) confirmed that the ADSCs could be induced to differentiate toward chondrocytes or osteoblasts in vitro at chondral and bony layers in the presence of chondrogenic- or osteogenic-induced culture medium, respectively. Moreover, the intermediate layer could play an isolating role for preventing the cells within the chondral and bony layers from mixing with each other. In conclusion, the trilayered and integrated osteochondral scaffolds can effectively support cartilage and bone tissue generation in vitro and are potentially applicable for OC tissue engineering in vivo. PMID:25210952

Ding, Xiaoming; Zhu, Meifeng; Xu, Baoshan; Zhang, Jiamin; Zhao, Yanhong; Ji, Shenglu; Wang, Lina; Wang, Lianyong; Li, Xiulan; Kong, Deling; Ma, Xinlong; Yang, Qiang

2014-10-01

92

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

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

Xiu-Mei Mo

2011-03-01

93

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

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

Chih-Hao Chen

2014-03-01

94

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

Science.gov (United States)

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

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

2012-06-01

95

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.

96

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

Science.gov (United States)

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. PMID:24857500

Kim, Hyunryung; Che, Lihua; Ha, Yoon; Ryu, WonHyoung

2014-07-01

97

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

International Nuclear Information System (INIS)

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

98

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

Science.gov (United States)

Cell-microstructure surface interactions play a significant role in tissue engineering to guide cell spreading and migration. However, the mechanisms underlying cell-topography interactions are complex and remain elusive. To address this topic, microsphere array patterns were prepared on silk fibroin films through polystyrene microsphere self-assembly, followed by culturing rat bone marrow derived mesenchymal stem cells on the films to study cell-substrate interactions. Filopodia sensed and anchored to the microspheres to form initial attachments before spreading. Importantly, the anchored filopodia converted into lamellipodia, and this conversion initiated the directional formation of lamellipodia. Therefore, the conversion of exploratory filopodia into lamellipodia was the main driving force for directional extension of the lamellipodia. Correspondingly, cell spreading, morphology, and migration were modulated by pseudopodial recognition and conversion. This finding demonstrated that filopodia not only act as an antenna to detect microenvironment but also serve as skeleton to guide lamellipodial extension for directing cell motions. The micropatterned films promoted cell adhesion and proliferation due to accelerated lamellipodia formation and cell spreading, with recognition and conversion of filopodia into lamellipodia as a critical role in cell response to surface topography. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 4206-4212, 2014. PMID:24464986

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

2014-12-01

99

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

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

Baimark Yodthong

2010-01-01

100

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

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

Ong-chiari Watcharin

2009-01-01

 
 
 
 
101

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-01

102

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 better bioactivity than the pure SF film. ? The SF/NBG composite films facilitate cell growth and promote cell proliferation and differentiation.

103

Fabrication and characterization of silk fibroin/bioactive glass composite films  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-05-01

104

Tissue engineered bulking agent with adipose-derived stem cells and silk fibroin microspheres for the treatment of intrinsic urethral sphincter deficiency.  

Science.gov (United States)

In this study we developed a tissue engineered bulking agent that consisted of adipose-derived stem cells (ADSCs) and silk fibroin microspheres to treat stress urinary incontinence caused by severe intrinsic sphincter deficiency (ISD). ISD models were established by completely transection of the bilateral pudendal nerve (PNT) and confirmed by the decreased leak-point pressure (LPP) and increased lumen area of urethra. Injection of silk fibroin microspheres could recover LPP and lumen area at 4 weeks but its efficacy disappears at 8, 12 weeks. Moreover, it was exciting to find that tissue engineered bulking agent brought long-term efficacy (at 4, 8, 12 weeks post-injection) on the recovery of LPP and lumen area. Concomitantly with the function, tissue engineered bulking agent treated group also improved the urethral sphincter structure as exhibited by better tissue regeneration. The findings showed that silk fibroin microspheres alone could work effectively in short-term, while tissue engineered bulking agent that combined silk fibroin microspheres with ADSCs exhibited promising long-term efficacy. This study developed a new strategy of tissue engineered bulking agent for future ISD therapy. PMID:24275524

Shi, Li Bing; Cai, Hong Xia; Chen, Long Kun; Wu, Yan; Zhu, Shou An; Gong, Xiao Nan; Xia, Ya Xian; Ouyang, Hong Wei; Zou, Xiao Hui

2014-02-01

105

Structure and ultrastructure of the silk glands and spinneret of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae).  

Science.gov (United States)

This study provides comprehensive documentation of silk production in the pest moth Helicoverpa armigera from gland secretion to extrusion of silk thread. The structure of the silk glands, accessory structures and extrusion apparatus are reported. The general schema of the paired silk glands follows that found for Lepidoptera. Morphology of the duct, silk press, muscle attachments and spigot are presented as a three-dimensional reconstruction and the cuticular crescent-shaped profile of the silk press is demonstrated in both open and closed forms with attendant muscle blocks, allowing advances in our knowledge of how the silk press functions to regulate the extrusion of silk. Growth of the spigot across instars is documented showing a distinctive developmental pattern for this extrusion device. Its shape and structure are related to use and load-bearing activity. PMID:18089054

Sorensen, Gregory S; Cribb, Bronwen W; Merritt, David; Johnson, Marie-Louise; Zalucki, Myron P

2006-03-01

106

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

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

Srihanam Prasong

2011-01-01

107

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  

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

Traian V. Chirila

2013-05-01

108

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

Science.gov (United States)

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

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

2012-03-01

109

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

Science.gov (United States)

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

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

2013-12-01

110

Construction of engineering adipose-like tissue in vivo utilizing human insulin gene-modified umbilical cord mesenchymal stromal cells with silk fibroin 3D scaffolds.  

Science.gov (United States)

We evaluated the use of a combination of human insulin gene-modified umbilical cord mesenchymal stromal cells (hUMSCs) with silk fibroin 3D scaffolds for adipose tissue engineering. In this study hUMSCs were isolated and cultured. HUMSCs infected with Ade-insulin-EGFP were seeded in fibroin 3D scaffolds with uniform 50-60?µm pore size. Silk fibroin scaffolds with untransfected hUMSCs were used as control. They were cultured for 4?days in adipogenic medium and transplanted under the dorsal skins of female Wistar rats after the hUMSCs had been labelled with chloromethylbenzamido-1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (CM-Dil). Macroscopical impression, fluorescence observation, histology and SEM were used for assessment after transplantation at 8 and 12?weeks. Macroscopically, newly formed adipose tissue was observed in the experimental group and control group after 8 and 12?weeks. Fluorescence observation supported that the formed adipose tissue originated from seeded hUMSCs rather than from possible infiltrating perivascular tissue. Oil red O staining of newly formed tissue showed that there was substantially more tissue regeneration in the experimental group than in the control group. SEM showed that experimental group cells had more fat-like cells, whose volume was larger than that of the control group, and degradation of the silk fibroin scaffold was greater under SEM observation. This study provides significant evidence that hUMSCs transfected by adenovirus vector have good compatibility with silk fibroin scaffold, and adenoviral transfection of the human insulin gene can be used for the construction of tissue-engineered adipose. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23509085

Li, Shi-Long; Liu, Yi; Hui, Ling

2013-03-19

111

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

Science.gov (United States)

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

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

2014-03-01

112

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

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

S. Prasong

2009-01-01

113

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

Science.gov (United States)

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

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

2012-01-01

114

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

115

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

116

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, flattened cells are a sign of an appropriate interaction with the MAPLE FIB and composite HA-FIB coatings.

117

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Tissue engineered scaffold is one of the hopeful therapies for the patients with organ or tissue damages. The key element for a tissue engineered scaffold material is high biocompatibility. Herein the poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) film was irradiated by the low temperature atmospheric plasma and then coated by the silk fibroins (SF). After plasma treatment, the surface of PHBHHx film became rougher and more hydrophilic than that of original film. The experiment of PH...

Huaxiao Yang; Min Sun; Ping Zhou,; Luanfeng Pan; Chungen Wu

2010-01-01

118

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

Science.gov (United States)

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

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

2013-02-01

119

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

Science.gov (United States)

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

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

2014-02-01

120

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

Science.gov (United States)

The silk of caterpillars is secreted in the labial glands, stored as a gel in their lumen, and converted into a solid filament during spinning. Heavy chain fibroin (H-fibroin), light chain fibroin (L-fibroin), and P25 protein constitute the filament core in a few species that have been analyzed. Identification of these proteins in Yponomeuta evonymella, a moth from a family which diverged from the rest of Lepidoptera about 150 million years ago, reveals that the mode of filament construction is highly conserved. It is proposed that association of the three proteins is suited for long storage of hydrated silk dope and its rapid conversion to filament. Interactions underlying these processes depend on conserved spacing of critical amino acid residues that are dispersed through the L-fibroin and P25 and assembled in the short ends of the H-fibroin molecule. Strength, elasticity, and other physical properties of the filament are determined by simple amino acid motifs arranged in repetitive modules that build up most of the H-fibroin. H-Fibroin synergy with L-fibroin and P25 does not interfere with motif diversification by which the filament acquires new properties. Several types of motifs in complex repeats occur in the silks used for larval cobwebs and pupal cocoons. Restriction of silk use to cocoon construction in some lepidopteran families has been accompanied by simplification of H-fibroin repeats. An extreme deviation of the silk structure occurs in the Saturniidae silkmoths, which possess modified H-fibroin and lack L-fibroin and P25. PMID:16755355

Yonemura, Naoyuki; Sehnal, Frantisek

2006-07-01

 
 
 
 
121

20-Hydroxyecdysone regulation of H-fibroin gene in the stored grain pest Corcyra cephalonica, during the last instar larval development.  

Science.gov (United States)

20-Hydroxyecdysone (20E) controls molting, metamorphosis and reproduction of insects. It binds to a heterodimeric complex of ecdysone receptor (EcR) and ultraspiracle (USP), and regulates the transcription of genes containing ecdysone response elements (EcREs). However, the 20E regulation of silk fibroin genes is largely unexplored. In most lepidopteran larvae, the silk fibroin primarily consists of a large protein, heavy chain fibroin (H-fibroin) that is associated with two small proteins, L-chain fibroin and P25. In the present study, we demonstrate that 20E regulates the expression of H-fibroin gene in Corcyra cephalonica, in a dose-dependent manner during the last instar larval development. Semi-quantitative and real-time PCR studies reveal that physiological doses of 20E do not alter the normal expression, whereas higher doses cause a significant decline in the expression. Luciferase activity assays and gel shift experiments further confirm the presence of a functional EcRE in the upstream region of H-fibroin which regulates the ecdysteroid dependent transcriptional activity of fibroin gene through EcR. In vitro treatment with 20E mimicking insecticides, RH-5849 and RH-5992 decreases the expression of H-fibroin in isolated salivary glands. Insects fed with similar concentrations of these insecticides, metamorphose abnormally. Differences are also observed in the ultrastructure of the silk fibers of control and insecticide fed insects providing additional insight into the disruptive effects of these non-steroidal ecdysteroid agonists. PMID:21034755

Chaitanya, R K; Sridevi, P; Senthilkumaran, B; Gupta, Aparna Dutta

2011-01-01

122

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

Science.gov (United States)

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

Lozano-Perez, Antonio Abel; Rodriguez-Nogales, Alba; Ortiz-Cullera, Victor; Algieri, Francesca; Garrido-Mesa, Jose; Zorrilla, Pedro; Rodriguez-Cabezas, M Elena; Garrido-Mesa, Natividad; Utrilla, M Pilar; De Matteis, Laura; de la Fuente, Jesus Martinez; Cenis, Jose Luis; Galvez, Julio

2014-01-01

123

Anisotropical electro-polarization effects induced in C2-O bonds present around the ?-helixes of silk fibroin  

Science.gov (United States)

Under the influence of perpendicularly applied positive electro-static field less than ?103V/cm to silk fibron textiles, at the high frequency side of the C2-O bending reflection band (?450˜350 cm-1), effect of step creation and step annihilation of the C2-O pseudo dending bands was induced in three stages at ?600˜450 cm-1 region IR spectroscopically relating to the stepnized statistical transfer of the unbonded 2P2, ? electrons in carbon which present with density of ?4.0×1014/cm2 in the surface mono-layer of silk fibroin from the states formed in (-C1-C2-N-)m spiral chains upto the pseudo-bending states formed in C2-O bondings. Fine ?90 steps measured overlapping on these four types of C2-O reflection bands were analysed as to consist four step series and they were shown as, y = A·Jm + B cm-1 with A=20, B=521, m=0.55 and J=1, 2...18 for the B-series. And with A=39, B=283, m=0.63 and J=1, 2 ...17 for the C-series. y J = A·J + B cm-1 with A=11.42, B=201 and J=1, 2...13, for the D-series. And, stepnized C2-O bending bands including that of permanent oscillators and pseudo-bending oscillators induced by the effect of transfer of the unbonded 2P2 electrons in carbon atoms were shown as, EN=A·N2+B·N+C (eV) with A=-1.50×10-3, B=1.65×10-2 and C=2.4×10-2.

Sato, Kenzo

1986-06-01

124

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

Science.gov (United States)

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

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

2002-08-01

125

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

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Replicating the nanostructured components of extracellular matrix is a target for dermal tissue engineering and regenerative medicine. Electrospinning Bombyx mori silk fibroin (BMSF) allows the production of nano- to microscale fibrous scaffolds. For BMSF electrospun scaffolds to be successful, understanding and optimizing the cellular response to material morphology is essential. Primary human dermal fibroblast response to nine variants of BMSF scaffolds composed of nano- to microscale fibers ranging from ~250 to ~1200 nm was assessed in vitro with regard to cell proliferation, viability, cellular morphology, and gene expression. BMSF support of epithelial migration was then assessed through utilization of a novel ex vivo human skin wound healing model. Scaffolds composed of the smallest diameter fibers, ~250 -300 nm, supported cell proliferation significantly more than fibers with diameters approximately 1 ?m (p nanofibrous architectures enhanced proliferation in comparison to microfibrous scaffolds and provided an effective template for migratory keratinocytes during re-epithelialization. The results may aid in the development of effective BMSF electrospun scaffolds for wound healing applications

Hodgkinson, Tom; Yuan, Xue-Feng

2014-01-01

126

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.

127

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

Science.gov (United States)

In the present study, silk fibroin (SF) was used as a template to prepare nano-hydroxyapatite (nano-HA) via a biomineralization process. We observed that the content of SF affected both the morphology and water dispersibility of nano-HA particles. Scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), zetasizer, and Fourier transform infrared spectroscopy (FTIR) were used to examine nano-HA particle features including the surface morphology, aggregation performance, and crystallization. Rod-like nano-HA particles with desired water dispersibility were achieved when the ratio of SF/HA (calculated) was above 7:3. SEM, TEM, and zeta potential results revealed that nano-HA particles were enclosed by the SF which formed a negative charge layer preventing the aggregation of HA nanoparticles in aqueous solution. Moreover, the nano-HA particles were able to re-disperse in water without precipitation for two weeks at room temperature, 60°C, and 90°C. Our work suggested a facile and effective approach of designing water-dispersible nano-HA particles which may have wide potential application in tissue engineering especially bone regeneration. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1720-1729, 2014. PMID:24678026

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

2014-11-01

128

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

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

Prasong Srihanam

2011-01-01

129

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-12-15

130

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

Science.gov (United States)

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

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

2014-10-01

131

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

132

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-01-13

133

Improved hemocompatibility and endothelialization of vascular grafts by covalent immobilization of sulfated silk fibroin on poly(lactic-co-glycolic acid) scaffolds.  

Science.gov (United States)

Endothelialization of vascular grafts prior to implantation has been investigated widely to enhance biocompatibility and antithrombogenicity. Thrombosis of artificial vessels is typically caused by platelet adhesion and agglomeration following endothelial cells detachment when exposed to the shear stress of blood circulation. The present study thus aimed at preventing platelet adhesion and aggregation onto biomaterials before the endothelial confluence is fully achieved. We report this modification of poly(lactic-co-glycolic acid) (PLGA) scaffolds, both to impart hemocompatibility to prevent platelet adhesion and aggregation before the endothelial confluence is fully achieved and to support EC growth to accelerate endothelialization. The modification was achieved by covalent immobilization of sulfated silk fibroin on PLGA scaffolds using ? irradiation. Using phosphate-buffered saline (PBS) as an aging medium, it was demonstrated that the scaffolds prepared by ? irradiation had a good retention of sulfated silk fibroin. The systematic in vitro hemocompatibility evaluation revealed that sulfated silk fibroin covalently immobilized PLGA (S-PLGA) scaffolds-reduced platelet adhesion and activation, prolonged whole blood clotting time, activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT). To evaluate further in vitro cytocompatibility of the scaffolds, we seeded vascular ECs on the scaffolds and cultured them for 2 weeks. The ECs were seen to attach and proliferate well on S-PLGA scaffolds, forming cell aggregates that gradually increased in size and fused with adjacent cell aggregates to form a monolayer covering the scaffold surface. Moreover, it was demonstrated through the gene transcript levels and the protein expressions of EC-specific markers that the cell functions of ECs on S-PLGA scaffolds were better preserved than those on PLGA scaffolds. Therefore, this study has described the generation of a vascular graft that possesses the unique ability to display excellent hemocompatibility while simultaneously supporting extensive endothelialization. PMID:21714569

Liu, Haifeng; Li, Xiaoming; Niu, Xufeng; Zhou, Gang; Li, Ping; Fan, Yubo

2011-08-01

134

Characterization of low-temperature-plasma treated silk fibroin fabrics by ESCA and the use of the fabrics as an enzyme-immobilization support.  

Science.gov (United States)

Bombyx mori silk fibroin fabrics were treated with low-temperature-plasma using various gases. Alkaline phosphatase was immobilized onto the fabrics using the CNBr method. The enzyme activity was much improved by plasma treatment, especially when both O2 and CF4 were used. Using the ESCA technique it was found that the activities of the immobilized enzyme were strongly correlated with the C1s peak intensities of the atomic group -C-O-CF3. The apparent Michaelis constant for the enzyme decreased with increasing amounts of -C-O-CF3. PMID:1600029

Demura, M; Takekawa, T; Asakura, T; Nishikawa, A

1992-01-01

135

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

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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...

Lu?, Kaige; Xu, Ling; Xia, Lunguo; Zhang, Yilin; Zhang, Xiuli; Kaplan, David L.; Jiang, Xinquan; Zhang, Fuqiang

2012-01-01

136

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

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

Mahesh Kumar Sah

2010-06-01

137

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

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

Huaxiao Yang

2010-12-01

138

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

Science.gov (United States)

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

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

2013-04-01

139

Effect of juvenile hormone analog, methoprene on H-fibroin regulation during the last instar larval development of Corcyra cephalonica.  

Science.gov (United States)

Juvenile hormone (JH) and 20-hydroxyecdysone (20E), co-ordinately orchestrate insect growth and development. The process of silk synthesis and secretion in lepidopteran insects is known to be under hormonal control. However, the role of JH in this process has not been demonstrated hitherto. The present study is aimed to elucidate the role of JH in H-fibroin regulation in Corcyra cephalonica, a serious lepidopteran pest. Reiterated amino acid stretches and the large molecular weight of H-fibroin render its cloning and characterization cumbersome. To address this, a commercially synthesized short amino acid peptide conjugated with a carrier protein was used to generate antibodies against the N-terminal region of H-fibroin. ELISA and immunoblot experiments demonstrated the sensitivity and specificity of antibody. Further, immunohistochemical analyses revealed the antibody's cross-reactivity with H-fibroins of C. cephalonica and Bombyx mori in the silk gland lumen. Quantitative RT-PCR and Western blot analysis demonstrated the tissue-specificity and developmental expression of H-fibroin. Hormonal studies revealed that JH alone does not alter the expression of H-fibroin. However, in the presence 20E, JH reverses the declined expression caused by 20E administration to normal levels. This study provides molecular evidence for the regulation of H-fibroin by the cumulative action of JH and 20E. PMID:22929589

Chaitanya, R K; Sridevi, P; Senthilkumaran, B; Dutta Gupta, Aparna

2013-01-15

140

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

International Nuclear Information System (INIS)

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

 
 
 
 
141

Surface modification of Thai silk fibroin scaffolds with gelatin and chitooligosaccharide for enhanced osteogenic differentiation of bone marrow-derived mesenchymal stem cells.  

Science.gov (United States)

In this study, the surface modification of silk fibroin (SF) scaffolds with gelatin/chitooligosaccharide (G/COS) blends using the reaction of glutaraldehyde (GA) was established. The effects of G/COS mixing ratio (100/0, 90/10, 80/20, and 70/30) and GA crosslinking concentration (0.05, 0.10, 0.15, and 0.20 vol %) on the properties of scaffolds were investigated. At 0.10-0.20 vol % GA, all G/COS blends could be successfully conjugated on the SF scaffolds, as confirmed by the percentage of weight increased and the presence of functional groups indicating SF, G, and COS from FTIR spectra. Pore size of SF scaffolds was around 570 ?m with 92% porosity, however, the G/COS-conjugated SF scaffolds showed thickened pore's wall, smaller pore size (?184-275 ?m) and less porosity (?81%), but increased density. This modified structure subsequently improved the compressive modulus of the G/COS-conjugated SF scaffolds. In terms of biological properties, the gelatin-conjugated SF scaffolds promoted the attachment and proliferation of bone marrow-derived mesenchymal stem cells (MSC) rather than the other scaffolds. However, the G/COS-conjugated SF scaffolds, particularly at the ratio of 70/30, promoted the osteogenic differentiation of MSC comparing to the SF scaffold, as confirmed by the production of alkaline phosphatase (ALP) activity and calcium (Ca), and the deposition of calcium phosphate (CaP). It was concluded that the G/COS-conjugated SF scaffolds showed great mechanical properties due to the ?-structure of silk fibroin, as well as the enhanced biological properties due to the G/COS blends. PMID:23015285

Wongputtaraksa, Tanom; Ratanavaraporn, Juthamas; Pichyangkura, Rath; Damrongsakkul, Siriporn

2012-11-01

142

Titanium dioxide nanoparticles relieve silk gland damage and increase cocooning of Bombyx mori under phoxim-induced toxicity.  

Science.gov (United States)

Organophosphate pesticides are applied widely in the world for agricultural purposes, and their exposures often resulted in non-cocooning of Bombyx mori in China. TiO2 nanoparticles have been demonstrated to increase pesticide resistance of Bombyx mori. While the toxicity of phoxim is well-documented, very limited information exists on the mechanisms of TiO2 nanoparticles improving the cocooning function of Bombyx mori following exposure to phoxim. The present study was, therefore, undertaken to determine whether TiO2 nanoparticles attenuate silk gland injury and elevate cocooning of B. mori following exposure to phoxim. The findings suggested that phoxim exposure resulted in severe damages of the silk gland structure and significantly decreased the cocooning in the silk gland of Bombyx mori. Furthermore, phoxim exposure significantly resulted in reductions of total protein concentrations and suppressed expressions of silk protein synthesis-related genes, including Fib-L, Fib-H, P25, Ser-2, and Ser-3, in the silk gland. TiO2 nanoparticle pretreatment, however, could significantly relieve silk gland injury of Bombyx mori. Importantly, TiO2 nanoparticles could remarkably elevate cocooning and total protein contents and promote expressions of Fib-L, Fib-H, P25, Ser-2, and Ser-3 in the silk gland following exposure to phoxim. PMID:24224746

Li, Bing; Yu, Xiaohong; Gui, Suxin; Xie, Yi; Hong, Jie; Zhao, Xiaoyang; Sheng, Lei; Sang, Xuezi; Sun, Qingqing; Wang, Ling; Shen, Weide; Hong, Fashui

2013-12-18

143

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

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Full Text Available Antonio Abel Lozano-Pérez,1 Alba Rodriguez-Nogales,2 Víctor Ortiz-Cullera,1 Francesca Algieri,2 José Garrido-Mesa,2 Pedro Zorrilla,2 M Elena Rodriguez-Cabezas,2 Natividad Garrido-Mesa,2 M Pilar Utrilla,2 Laura De Matteis,3 Jesús Martínez de la Fuente,3 José Luis Cenis,1 Julio Gálvez2 1Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario, Murcia, Spain; 2Centro de Investigaciones Biomédicas en Red – Enfermedades Hepáticas y Digestivas, Department of Pharmacology, ibs Granada, Center for Biomedical Research, University of Granada, Granada, Spain; 3Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain Purpose: We aimed to evaluate the intestinal anti-inflammatory properties of silk fibroin nanoparticles, around 100 nm in size, when loaded with the stilbene compound resveratrol, in an experimental model of rat colitis. Methods: Nanoparticles were loaded with resveratrol by adsorption. The biological effects of the resveratrol-loaded nanoparticles were tested both in vitro, in a cell culture of RAW 264.7 cells (mouse macrophages, and in vivo, in the trinitrobenzenesulfonic acid model of rat colitis, when administered intracolonically.Results: The resveratrol liberation in 1× phosphate-buffered saline (PBS; pH 7.4 was characterized by fast liberation, reaching the solubility limit in 3 hours, which was maintained over a period of 80 hours. The in vitro assays revealed immunomodulatory properties exerted by these resveratrol-loaded nanoparticles since they promoted macrophage activity in basal conditions and inhibited this activity when stimulated with lipopolysaccharide. The in vivo experiments showed that after evaluation of the macroscopic symptoms, inflammatory markers, and intestinal barrier function, the fibroin nanoparticles loaded with resveratrol had a better effect than the single treatments, being similar to that produced by the glucocorticoid dexamethasone. Conclusion: Silk fibroin nanoparticles constitute an attractive strategy for the controlled release of resveratrol, showing immunomodulatory properties and intestinal anti-inflammatory effects. Keywords: immunomodulatory, cytokines, TNBS rat colitis, RAW 264.7 macrophage cells, antioxidant

Lozano-Pérez AA

2014-09-01

144

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

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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

Jiang J

2014-09-01

145

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

Science.gov (United States)

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

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

146

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

Science.gov (United States)

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

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

2014-01-01

147

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

Science.gov (United States)

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

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

2014-01-01

148

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

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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%.

149

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

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

Yin Huanshun [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); College of Resources and Environment, Shandong Agricultural University, Taian 271018, Shandong (China); Zhou Yunlei; Xu Jing [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Ai Shiyun, E-mail: ashy@sdau.edu.cn [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Cui Lin [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Zhu Lusheng, E-mail: lushzhu@sdau.edu.cn [College of Resources and Environment, Shandong Agricultural University, Taian 271018, Shandong (China)

2010-02-05

150

Conformational and orientational transformation of silk proteins in the major ampullate gland of Nephila clavipes spiders.  

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The orientational and conformational transformation of the native liquid silk into a solid fiber in the major ampullate gland of the spider Nephila clavipes has been studied by Raman spectromicroscopy. The spectra show that the conformation of silk proteins in the glandular sac contains several secondary structure elements, which is consistent with intrinsically unfolded proteins. A few alpha-helices are also present and involve some alanine residues located in the polyalanine segments of the spidroin sequence. The conversion of the silk solution in the major ampullate gland appears to be a two-state process without intermediate states. In the first and second limbs of the duct, silk is isotropic and spidroins are generally native-like. beta-Sheets start to develop between the second and the third limb of the duct, suggesting that early beta-sheets are generated by shear forces. However, most of the beta-sheets are formed between the draw down taper and the valve. The early beta-sheets formed upward of the draw down taper might play the role of nucleation sites for the subsequent beta-sheet aggregation. The alignment of the polypeptides chains occurs near the valve, revealing that orientational and conformational changes do not occur simultaneously. Extensional flow seems to be the driving force to produce the orientational order, which in turn is associated with the formation of the major part of the beta-sheets. The slow evolution of the spidroin conformation up to the draw down taper followed by the rapid transformation between the drawn down taper and the valve may be important to achieve the optimal structure of the final fiber. PMID:18702545

Lefèvre, Thierry; Boudreault, Simon; Cloutier, Conrad; Pézolet, Michel

2008-09-01

151

Differential binding of the Bombyx silk gland-specific factor SGFB to its target DNA sequence drives posterior-cell-restricted expression.  

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The gene encoding the silk protein P25 in Bombyx mori is expressed in the posterior silk gland (PSG) cells and repressed in the middle silk gland (MSG) cells. To identify the factors involved in this transcription-dependent spatial restriction, we examined the P25 chromatin in PSG and MSG nuclei by DNase I-aided ligation-mediated PCR and analyzed the expression of various P25-lacZ constructs in biolistically treated silk glands. P25 promoter activation depends on two cis-acting elements. One ...

Horard, B.; Julien, E.; Nony, P.; Garel, A.; Couble, P.

1997-01-01

152

Light chain fibroin and P25 genes of Corcyra cephalonica: Molecular cloning, characterization, tissue-specific expression, synchronous developmental and 20-hydroxyecdysone regulation during the last instar larval development.  

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The biologically active ecdysteroid hormone, 20-hydroxyecdysone (20E), regulates various processes like molting, metamorphosis and reproduction in insects. However, its role in expression of silk genes is obscure. The silk core in insects is generally constituted of a complex of three proteins namely, H-chain fibroin (H-fibroin), L-chain fibroin (L-fibroin) and P25. In the present study, we report full-length cDNA cloning and characterization of L-fibroin and P25 genes from rice moth, Corcyra cephalonica. Northern analyses demonstrated 1.1 and 1kb transcripts of L-fibroin and P25 respectively. The tissue expression pattern shows the presence of these transcripts specifically in the salivary gland. These two genes are developmentally regulated at transcriptional level and their maximum expression is observed during the late-last instar larval stage. Semi-quantitative and real-time PCR studies revealed that 20E regulates the expression of these genes in a dose-dependant manner. This study further shows that physiological dose of 20E does not alter the normal expression of these two genes, whereas treatments with higher doses cause a significant decline in the expression. This study clearly suggests the role of 20E in the regulation of L-fibroin and P25 at molecular level. PMID:20171223

Chaitanya, R K; Dutta-Gupta, Aparna

2010-05-15

153

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)

154

Influence of the Mechanical Environment on the Engineering of Mineralised Tissues Using Human Dental Pulp Stem Cells and Silk Fibroin Scaffolds  

Science.gov (United States)

Teeth constitute a promising source of stem cells that can be used for tissue engineering and regenerative medicine purposes. Bone loss in the craniofacial complex due to pathological conditions and severe injuries could be treated with new materials combined with human dental pulp stem cells (hDPSCs) that have the same embryonic origin as craniofacial bones. Optimising combinations of scaffolds, cells, growth factors and culture conditions still remains a great challenge. In the present study, we evaluate the mineralisation potential of hDPSCs seeded on porous silk fibroin scaffolds in a mechanically dynamic environment provided by spinner flask bioreactors. Cell-seeded scaffolds were cultured in either standard or osteogenic media in both static and dynamic conditions for 47 days. Histological analysis and micro-computed tomography of the samples showed low levels of mineralisation when samples were cultured in static conditions (0.16±0.1 BV/TV%), while their culture in a dynamic environment with osteogenic medium and weekly µCT scans (4.9±1.6 BV/TV%) significantly increased the formation of homogeneously mineralised structures, which was also confirmed by the elevated calcium levels (4.5±1.0 vs. 8.8±1.7 mg/mL). Molecular analysis of the samples showed that the expression of tooth correlated genes such as Dentin Sialophosphoprotein and Nestin were downregulated by a factor of 6.7 and 7.4, respectively, in hDPSCs when cultured in presence of osteogenic medium. This finding indicates that hDPSCs are able to adopt a non-dental identity by changing the culture conditions only. Also an increased expression of Osteocalcin (1.4x) and Collagen type I (1.7x) was found after culture under mechanically dynamic conditions in control medium. In conclusion, the combination of hDPSCs and silk scaffolds cultured under mechanical loading in spinner flask bioreactors could offer a novel and promising approach for bone tissue engineering where appropriate and rapid bone regeneration in mechanically loaded tissues is required. PMID:25354351

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

2014-01-01

155

Antheraea pernyi silk fibroin-coated PEI/DNA complexes for targeted gene delivery in HEK 293 and HCT 116 cells.  

Science.gov (United States)

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. PMID:24776757

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

2014-01-01

156

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

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

Yu Liu

2014-04-01

157

Characterization of dielectrophoresis-aligned nanofibrous silk fibroin-chitosan scaffold and its interactions with endothelial cells for tissue engineering applications.  

Science.gov (United States)

Aligned three-dimensional nanofibrous silk fibroin-chitosan (eSFCS) scaffolds were fabricated using dielectrophoresis (DEP) by investigating the effects of alternating current frequency, the presence of ions, the SF:CS ratio and the post-DEP freezing temperature. Scaffolds were characterized with polarized light microscopy to analyze SF polymer chain alignment, atomic force microscopy (AFM) to measure the apparent elastic modulus, and scanning electron microscopy and AFM to analyze scaffold topography. The interaction of human umbilical vein endothelial cells (HUVECs) with eSFCS scaffolds was assessed using immunostaining to assess cell patterning and AFM to measure the apparent elastic modulus of the cells. The eSFCS (50:50) samples prepared at 10MHz with NaCl had the highest percentage of aligned area as compared to other conditions. As DEP frequency increased from 100kHz to 10MHz, fibril sizes decreased significantly. eSFCS (50:50) scaffolds fabricated at 10MHz in the presence of 5mM NaCl had a fibril size of 77.96±4.69nm and an apparent elastic modulus of 39.9±22.4kPa. HUVECs on eSFCS scaffolds formed aligned and branched capillary-like vascular structures. The elastic modulus of HUVEC cultured on eSFCS was 6.36±2.37kPa. DEP is a potential tool for fabrication of SFCS scaffolds with aligned nanofibrous structures that can guide vasculature in tissue engineering and repair. PMID:24821141

Dunne, Lina W; Iyyanki, Tejaswi; Hubenak, Justin; Mathur, Anshu B

2014-08-01

158

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

Science.gov (United States)

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

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

2014-01-01

159

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

Science.gov (United States)

In this study a part of research where artificially aged model samples were used as a guideline to the mechanism of degradation is presented. In previous work Bombyx Mori silk samples were exposed to various environments such as different oxygen, water vapour and volatile organic products content, all at the temperature of 150 °C [11]. Based on those results gathered with by Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy (ATR-FTIR) the degradation estimators were proposed and classified as follows: (1) Primary functional groups estimators EAmideI/II - intensity ratios of Amide I C=O stretching vibration to Amide II N-H in-plane bending and C-N stretching vibrations A1620/A1514. ECOOH - band 1318 cm(-1) integral to band integral of CH3 bending vibration band located at 1442 cm(-1)P1318/P1442. (2) Secondary conformational estimators EcC=O2 - intensity ratios within Amide I C=O stretching vibration of parallel ?-sheet to antiparallel ?-sheet A1620/A1699. In this work estimators were verified against estimators calculated from spectra of silk samples from 8 museum objects: 3 from 19th, 2 from 18th, 1 from 17th and 2 from 16th century including 3 banners from the storage resources of the Wawel Royal Castle in Cracow, Poland. PMID:25124844

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

2015-01-25

160

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

 
 
 
 
161

Proteomic studies of isoforms of the P25 component of Bombyx mori fibroin.  

Science.gov (United States)

It is recognized that P25 is one of three polypeptide components of the fibroin synthesized in the larval silk gland (SG) of silkworm, having two glycosylated isoforms. In the present study, however, eight P25 isoforms were separated by proteomics, including two-dimensional gel electrophoresis of whole SG proteins, and were identified by the peptide mass fingerprinting method. Four of the eight isoforms were identified as Bombyx mandarina P25s, although the SG of Bombyx mori has never been considered to contain the P25 from B. mandarina. It is suggested that this diversity of P25 isoforms depends on phosphorylation modification in addition to glycosylation. PMID:16306689

Zhang, Pingbo; Yamamoto, Kohji; Aso, Yoichi; Banno, Yutaka; Sakano, Daisuke; Wang, Yongqiang; Fujii, Hiroshi

2005-11-01

162

Molecular mechanisms of phoxim-induced silk gland damage and TiO2 nanoparticle-attenuated damage in Bombyx mori.  

Science.gov (United States)

Phoxim is a useful organophosphate (OP) pesticide used in agriculture in China, however, exposure to this pesticide can result in a significant reduction in cocooning in Bombyx mori (B. mori). Titanium dioxide nanoparticles (TiO2 NPs) have been shown to decrease phoxim-induced toxicity in B. mori; however, very little is known about the molecular mechanisms of silk gland damage due to OP exposure and repair of gland damage by TiO2 NP pretreatment. In the present study, exposure to phoxim resulted in a significant reduction in cocooning rate in addition to silk gland damage, whereas TiO2 NP attenuated phoxim-induced gland damage, increased the antioxidant capacity of the gland, and increased cocooning rate in B. mori. Furthermore, digital gene expression data suggested that phoxim exposure led to significant alterations in the expression of 833 genes. In particular, phoxim exposure caused significant down-regulation of Fib-L, Ser2, Ser3, and P25 genes involved in silk protein synthesis, and up-regulation of SFGH, UCH3, and Salhh genes involved in silk protein hydrolysis. A combination of both phoxim and TiO2 NP treatment resulted in marked changes in the expression of 754 genes, while treatment with TiO2 NPs led to significant alterations in the expression of 308 genes. Importantly, pretreatment with TiO2 NPs increased Fib-L, Ser2, Ser3, and P25 expression, and decreased SFGH, UCH3, and Salhh expression in silk protein in the silk gland under phoxim stress. Therefore, Fib-L, Ser2, Ser3, P25, SFGH, UCH3, and Salhh may be potential biomarkers of silk gland toxicity in B. mori caused by phoxim exposure. PMID:24331035

Li, Bing; Yu, Xiaohong; Gui, Suxin; Xie, Yi; Zhao, Xiaoyang; Hong, Jie; Sun, Qingqing; Sang, Xuezi; Sheng, Lei; Cheng, Zhe; Cheng, Jie; Hu, Rengping; Wang, Ling; Shen, Weide; Hong, Fashui

2014-06-01

163

A highly divergent gene cluster in honey bees encodes a novel silk family.  

Science.gov (United States)

The pupal cocoon of the domesticated silk moth Bombyx mori is the best known and most extensively studied insect silk. It is not widely known that Apis mellifera larvae also produce silk. We have used a combination of genomic and proteomic techniques to identify four honey bee fiber genes (AmelFibroin1-4) and two silk-associated genes (AmelSA1 and 2). The four fiber genes are small, comprise a single exon each, and are clustered on a short genomic region where the open reading frames are GC-rich amid low GC intergenic regions. The genes encode similar proteins that are highly helical and predicted to form unusually tight coiled coils. Despite the similarity in size, structure, and composition of the encoded proteins, the genes have low primary sequence identity. We propose that the four fiber genes have arisen from gene duplication events but have subsequently diverged significantly. The silk-associated genes encode proteins likely to act as a glue (AmelSA1) and involved in silk processing (AmelSA2). Although the silks of honey bees and silkmoths both originate in larval labial glands, the silk proteins are completely different in their primary, secondary, and tertiary structures as well as the genomic arrangement of the genes encoding them. This implies independent evolutionary origins for these functionally related proteins. PMID:17065612

Sutherland, Tara D; Campbell, Peter M; Weisman, Sarah; Trueman, Holly E; Sriskantha, Alagacone; Wanjura, Wolfgang J; Haritos, Victoria S

2006-11-01

164

Silk Coatings on PLGA and Alginate Microspheres for Protein Delivery  

Science.gov (United States)

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 microspheres the coating was ~1 ?m and discontinuous, reflecting the porous surface of these microspheres determined by SEM. In contrast, on alginate microspheres the coating was ~10 ?m thick and continuous. The silk fibroin penetrated into the alginate gel matrix. The silk coating on the PLGA microspheres delayed PLGA degradation. The silk coating on the alginate microspheres survived ethylenediamine tetraacetic acid (EDTA) treatment used to remove the Ca+2-cross-links in the alginate gels to solubilize the alginate. This suggests that alginate microspheres can be used as templates to form silk microcapsules. Horseradish peroxidase (HRP) and tetramethylrhodamine-conjugated bovine serum albumin (BSA) as model protein drugs were encapsulated in the PLGA and alginate microspheres with and without the silk fibroin coatings. Drug release was significantly retarded by the silk coatings when compared to uncoated microsphere controls, and was retarded further by methanol-treated silk coating when compared to silk water-based coatings on alginate microspheres. Silk coatings on PLGA and alginate microspheres provide mechanically stable shells as well as a diffusion barrier to the encapsulated protein drugs. This coating technique has potential for biosensor and drug delivery applications due to the aqueous process employed, the ability to control coating thickness and crystalline content, and the biocompatibility of the silk fibroin protein used in the process. PMID:17583788

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

2009-01-01

165

Fabrication and Biocompatibility of Electrospun Silk Biocomposites  

Directory of Open Access Journals (Sweden)

Full Text Available Silk fibroin has attracted great interest in tissue engineering because of its outstanding biocompatibility, biodegradability and minimal inflammatory reaction. In this study, two kinds of biocomposites based on regenerated silk fibroin are fabricated by electrospinning and post-treatment processes, respectively. Firstly, regenerated silk fibroin/tetramethoxysilane (TMOS hybrid nanofibers with high hydrophilicity are prepared, which is superior for fibroblast attachment. The electrospinning process causes adjacent fibers to ‘weld’ at contact points, which can be proved by scanning electron microscope (SEM. The water contact angle of silk/tetramethoxysilane (TMOS composites shows a sharper decrease than pure regenerated silk fibroin nanofiber, which has a great effect on the early stage of cell attachment behavior. Secondly, a novel tissue engineering scaffold material based on electrospun silk fibroin/nano-hydroxyapatite (nHA biocomposites is prepared by means of an effective calcium and phosphate (Ca–P alternate soaking method. nHA is successfully produced on regenerated silk fibroin nanofiber within several min without any pre-treatments. The osteoblastic activities of this novel nanofibrous biocomposites are also investigated by employing osteoblastic-like MC3T3-E1 cell line. The cell functionality such as alkaline phosphatase (ALP activity is ameliorated on mineralized silk nanofibers. All these results indicate that this silk/nHA biocomposite scaffold material may be a promising biomaterial for bone tissue engineering.

Ick-Soo Kim

2011-10-01

166

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

Science.gov (United States)

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

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

2014-11-10

167

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

168

Expression analysis of inhibitor of apoptosis and related caspases in the midgut and silk gland of the greater wax moth, Galleria mellonella, during metamorphosis and under starvation.  

Science.gov (United States)

We cloned a cDNA encoding inhibitor of apoptosis (IAP) from the greater wax moth, Galleria mellonella. The deduced amino acid sequence showed that GmIAP contains two baculoviral IAP repeat (BIR) motifs, followed by a RING finger. The sequence comparison showed that GmIAP had high homology to lepidopteran IAPs and baculoviral IAPs, as well as dipteran IAPs. GmIAP transcript and its protein appeared in both the midgut and the silk gland during metamorphosis and starvation where cell death was detected by TUNEL test. IAP, and capases-1, -3, -4 and -6 appeared as at least two peaks in the midgut and silk gland during metamorphosis. Caspase-1 transcript appeared at the highest level among caspases, while caspase-3 and caspase-6 seemed to be the most relevant caspases to IAP during metamorphosis suggesting that IAP and caspases may be involved in a core apoptosis pathway in the wax moth as in flies and mosquitoes. PMID:22975212

Khoa, Dao Bach; Takeda, Makio

2012-12-01

169

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)

170

Nongenomic and genomic actions of an insect steroid coordinately regulate programmed cell death of anterior silk glands of Bombyx mori  

Directory of Open Access Journals (Sweden)

Full Text Available The insect steroid hormone 20-hydroxyecdysone (20E induces programmed cell death of larva-specific tissues at pupal metamorphosis. In the silkworm Bombyx mori, the anterior silk gland undergoes cell death in response to the metamorphic peak titer of ecdysteroids in vivo and also to 20E in vitro. Although 20E elicits early gene activation, an additional 20E stimulus is required for completion of cell death. This additional stimulus involves caspase-3-like protease activation, indicating that 20E also acts through a nongenomic mechanism. Studies using various inhibitors, agonists, and antagonists have shown that cell condensation is under the control of 20E genomic action, and that 20E nongenomic action begins with 20E binding to the putative membrane-bound ecdysone receptor, which is probably a G-protein-coupled receptor. This step is followed by a signaling pathway comprising phospholipase C/inositol 3,4,5-triphosphate/Ca2+/protein kinase C/caspase-3-like protease, which induces DNA and nuclear fragmentation. Nuclear condensation is regulated by signaling of calmodulin/calmodulin-dependent protein kinase II (CaMKII, but CaMKII activation is independent of intracellular Ca2+ elevation. In addition, the genomic action of 20E is indispensable for driving its nongenomic action, indicating that crosstalk between genomic and nongenomic action plays a significant role in 20E-induced cell death.

S Sakurai

2008-02-01

171

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

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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.

S. Prasong

2009-01-01

172

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

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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.

Suriana

2011-04-01

173

A new chitinase-related gene, BmChiR1, is induced in the Bombyx mori anterior silk gland at molt and metamorphosis by ecdysteroid.  

Science.gov (United States)

A novel ecdysteroid-inducible gene was isolated from the anterior silk gland of the silkworm by mRNA differential display and named Bombyx mori chitinase-related gene 1 (BmChiR1). cDNA for BmChiR1 is 3.7 kbp encoding 1080 amino acids. Its predicted protein sequence consists of two tandem-repeated sequences, both showing high similarities to arthropod chitinases but lacking the active site glutamate essential for catalytic activity, suggesting that BmChiR1 protein has no chitinolytic activity. BmChiR1 mRNA was expressed simultaneously with chitinase mRNA in the anterior silk gland at the ends of the penultimate and last larval instar. Injection of 20-hydroxyecdysone (20E) into feeding last instar larvae induced accumulation of BmChiR1 mRNA. Topical application of a juvenile hormone analog, fenoxycarb, just after the 20E injection, suppressed this induction. BmChiR1 expression is therefore upregulated by ecdysteroid and downregulated by juvenile hormone. PMID:11755056

Takahashi, Michiyoshi; Kiuchi, Makoto; Kamimura, Manabu

2002-02-01

174

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)

175

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

Science.gov (United States)

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

Kundu, Banani; Kundu, S C

2013-10-01

176

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

Science.gov (United States)

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

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

2006-02-01

177

Silk-mediated synthesis and modification of photoluminescent ZnO nanoparticles  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2012-02-15

178

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

Science.gov (United States)

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

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

2006-09-01

179

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

180

Inkjet printing of silk nest arrays for cell hosting.  

Science.gov (United States)

An inkjet printing approach is presented for the facile fabrication of microscopic arrays of biocompatible silk "nests" capable of hosting live cells for prospective biosensors. The patterning of silk fibroin nests were constructed by the layer-by-layer (LbL) assembly of silk polyelectrolytes chemically modified with poly-(l-lysine) and poly-(l-glutamic acid) side chains. The inkjet-printed silk circular regions with a characteristic "nest" shape had diameters of 70-100 ?m and a thickness several hundred nanometers were stabilized by ionic pairing and by the formation of the silk II crystalline secondary structure. These "locked-in" silk nests remained anchored to the substrate during incubation in cell growth media to provide a biotemplated platform for printing-in, immobilization, encapsulation and growth of cells. The process of inkjet-assisted printing is versatile and can be applied on any type of substrate, including rigid and flexible, with scalability and facile formation. PMID:24605757

Suntivich, Rattanon; Drachuk, Irina; Calabrese, Rossella; Kaplan, David L; Tsukruk, Vladimir V

2014-04-14

 
 
 
 
181

Self-assembly in the major ampullate gland of Nephila clavipes  

CERN Document Server

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.

Braun, F N

2002-01-01

182

Silk ionomers for encapsulation and differentiation of human MSCs.  

Science.gov (United States)

The response of human bone marrow derived human mesenchymal stem cells (hMSCs) encapsulated in silk ionomer hydrogels was studied. Silk aqueous solutions with silk-poly-L-lysine or silk-poly-L-glutamate were formed into hydrogels via ultrasonication in situ with different net charges. hMSCs were encapsulated within the hydrogels and the impact of matrix charge was assessed over weeks in osteogenic, adipogenic and maintenance growth media. These modified silk charged polymers supported cell viability and proliferative potential, and the hMSCs were able to differentiate toward osteogenic or adipogenic lineages in the corresponding differentiation media. The silk/silk-poly-L-lysine hydrogels exhibited a positive effect on selective osteogenesis of hMSCs, inducing differentiation toward an osteogenic lineage even in the absence of osteogenic supplements, while also inhibiting adipogenesis. In contrast, silk/silk fibroin-poly-L-glutamate hydrogels supported both osteogenic and adipogenic differentiation of hMSCs when cultured under induction conditions. The results demonstrate the potential utility of silk-based ionomers in gel formats for hMSCs encapsulation and for directing hMSCs long term functional differentiation toward specific lineages. PMID:22824008

Calabrese, Rossella; Kaplan, David L

2012-10-01

183

Physical characterization of functionalized spider silk: electronic and sensing properties  

International Nuclear Information System (INIS)

. 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.

184

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

Science.gov (United States)

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

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

2014-07-01

185

Physico-chemical characterization and biological evaluation of two fibroin materials.  

Science.gov (United States)

Silk fibroin fibres from two different sources, Bombyx mori pure-breed silkworms and polyhybrid cross-bred silkworm cocoons, were treated with formic acid under planar stirring conditions to prepare non-woven nets. The treatment partially dissolved the fibres, which bound together and formed a non-woven micrometric net with fibres coated by a thin layer of low molecular weight fibroin matrix. The starting fibres, net materials and fibroin coating layer were characterized in terms of amino acid composition, molecular weight and calorimetric properties. In vitro cell culture tests with rat fibroblasts were performed to investigate cell proliferation, morphology and spreading. Moreover, host-rat fibroblasts were preseeded on the afore-mentioned nets and implanted in the thorax of rats for histological analysis. In spite of the chemical differences between the two starting fibroins, the response of the said materials in vitro and in vivo were very similar. These results suggest that the outcome is likely correlated with the modification of the processing technique; that during the formation of the net, a thin gel layer of similar amino acid composition was formed on the fibroin fibres. Copyright © 2012 John Wiley & Sons, Ltd. PMID:22972624

Motta, Antonella; Segnana, Paola; Verin, Lucia; Monica, Silvia La; Fumarola, Claudia; Bucci, Giovanna; Gussago, Francesca; Cantoni, Anna Maria; Ampollini, Luca; Migliaresi, Claudio

2014-11-01

186

Spinning an elastic ribbon of spider silk.  

Science.gov (United States)

The Sicarid spider Loxosceles laeta spins broad but very thin ribbons of elastic silk that it uses to form a retreat and to capture prey. A structural investigation into this spider's silk and spinning apparatus shows that these ribbons are spun from a gland homologous to the major ampullate gland of orb web spiders. The Loxosceles gland is constructed from the same basic parts (separate transverse zones in the gland, a duct and spigot) as other spider silk glands but construction details are highly specialized. These differences are thought to relate to different ways of spinning silk in the two groups of spiders. Loxosceles uses conventional die extrusion, feeding a liquid dope (spinning solution) to the slit-like die to form a flat ribbon, while orb web spiders use an extrusion process in which the silk dope is processed in an elongated duct to produce a cylindrical thread. This is achieved by the combination of an initial internal draw down, well inside the duct, and a final draw down, after the silk has left the spigot. The spinning mechanism in Loxosceles may be more ancestral. PMID:11911779

Knight, David P; Vollrath, Fritz

2002-02-28

187

Unravelling the biodiversity of nanoscale signatures of spider silk fibres  

Science.gov (United States)

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

Silva, Luciano P.; Rech, Elibio L.

2013-12-01

188

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.

189

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

Science.gov (United States)

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 affinity silk materials, we processed the scFv-conjugated silk protein into a thin film by dissolving it in lithium bromide, then drying it in the wells of 96-well plates. Enzyme-linked immunosorbent assay demonstrated specific detection of Wiskott-Aldrich syndrome protein, both as a recombinant protein and in its native form extracted from mouse macrophages. These findings suggest that this scFv-conjugated silk film serves as the basis for an alternative immunodetection system. PMID:24518284

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

2014-01-01

190

Silk Microgels Formed by Proteolytic Enzyme Activity  

Science.gov (United States)

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

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

2013-01-01

191

Gumfooted lines in black widow cobwebs and the mechanical properties of spider capture silk.  

Science.gov (United States)

Orb-weaving spiders produce webs using two types of silk that have radically different mechanical properties. The dragline silk used to construct the supporting frame and radii of the web is stiff and as strong as steel, while the capture spiral is much weaker but more than ten times as extensible. This remarkable divergence in mechanical properties has been attributed to the aqueous glue that coats the capture spiral, which is thought to decrease capture spiral stiffness and increase its extensibility. However, discerning the effect of the aqueous glue on fiber performance is complicated because dragline silk and the capture spiral are assembled from different proteins, which may also affect mechanical performance. Here, we use the sticky gumfooted lines of black widow cobwebs to test the effect of the addition of aqueous glue on the mechanical properties of dragline silk. We also surveyed orb-webs spun by a broad range of species for bundles of looped silk. Such bundles, termed windlasses, have been thought to increase capture spiral extensibility by "paying out" additional lengths of silk. Our results suggest that neither plasticization of silk by aqueous glue nor excess silk in windlasses can by themselves account for the remarkable extensibility of orb-weaver capture silk compared to other spider silks. This argues that the unique amino acid motifs of the flagelliform fibroins that constitute the core of the capture spiral play an essential role in capture silk's extreme extensibility. PMID:16351953

Blackledge, Todd A; Summers, Adam P; Hayashi, Cheryl Y

2005-01-01

192

The use of silk-based devices for fracture fixation  

Science.gov (United States)

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.

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

193

Thermally induced increase in energy transport capacity of silkworm silks.  

Science.gov (United States)

This work reports on the first study of thermally induced effect on energy transport in single filaments of silkworm (Bombyx mori) fibroin degummed mild (type 1), moderate (type 2), to strong (type 3). After heat treatment from 140 to 220°C, the thermal diffusivity of silk fibroin type 1, 2, and 3 increases up to 37.9, 20.9, and 21.5%, respectively. Our detailed scanning electron microscopy study confirms that the sample diameter change is almost negligible before and after heat treatment. Raman analysis is performed on the original and heat-treated (at 147°C) samples. After heat treatment at 147°C, the Raman peaks at 1081, 1230, and 1665 cm(-1) become stronger and narrower, indicating structural transformation from amorphous to crystalline. A structure model composed of amorphous, crystalline, and laterally ordered regions is proposed to explain the structural change by heat treatment. Owing to the close packing of more adjacent laterally ordered regions, the number and size of the crystalline regions of Bombyx mori silk fibroin increase by heat treatment. This structure change gives the observed significant thermal diffusivity increase by heat treatment. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1029-1037, 2014. PMID:24723331

Liu, Guoqing; Xu, Shen; Cao, Ting-Ting; Lin, Huan; Tang, Xiaoduan; Zhang, Yu-Qing; Wang, Xinwei

2014-10-01

194

Electrospinning Bombyx mori silk with poly(ethylene oxide).  

Science.gov (United States)

Electrospinning for the formation of nanoscale diameter fibers has been explored for high-performance filters and biomaterial scaffolds for vascular grafts or wound dressings. Fibers with nanoscale diameters provide benefits due to high surface area. In the present study we explore electrospinning for protein-based biomaterials to fabricate scaffolds and membranes from regenerated silkworm silk, Bombyx mori, solutions. To improve processability of the protein solution, poly(ethylene oxide) (PEO) with molecular weight of 900,000 was blended with the silk fibroin. A variety of compositions of the silk/PEO aqueous blends were successfully electrospun. The morphology of the fibers was characterized using high-resolution scanning electron microscopy. Fiber diameters were uniform and less than 800 nm. The composition was estimated by X-ray photoelectron spectroscopy to characterize silk/PEO surface content. Aqueous-based electrospining of silk and silk/PEO blends provides potentially useful options for the fabrication of biomaterial scaffolds based on this unique fibrous protein. PMID:12425660

Jin, Hyoung-Joon; Fridrikh, Sergey V; Rutledge, Gregory C; Kaplan, David L

2002-01-01

195

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

Science.gov (United States)

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

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

2011-11-01

196

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

Science.gov (United States)

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

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

2011-01-01

197

Impact of sterilization on the enzymatic degradation and mechanical properties of silk biomaterials.  

Science.gov (United States)

The effect of some sterilization methods (autoclaving and ethanol treatments) on the degradation rate and mechanical properties of two types of porous silk scaffolds (aqueous- and hexafluoroisopropanol-derived) is evaluated. Changes in secondary structure, crystal size, and supramolecular features of silk fibroin, resulting from sterilization, are tracked to elucidate molecular level effects on protease XIV enzymatic degradation and compressive mechanical properties. The structural features and pore sizes of the silk scaffolds remain intact after both sterilization processes. Autoclave sterilization dramatically reduce the degradation rate of the silk scaffolds in response to protease XIV and significantly increase mechanical properties, in contrast to scaffolds sterilized with 70% ethanol. Higher ?-sheet content and larger crystal size are observed after autoclaving, unlike in response to 70% ethanol sterilization, based on examination of Fourier transform (FT) IR spectroscopy and wide-angle X-ray scattering (WAXS). In addition, thermal analysis finds supramolecular features within silk fibroin amorphous regions, including the glass transition temperature (Tg ), heat capacity of glass transition (?Cp-Tg ), and thermal gravimetric degradability. Such supramolecular level changes are related to the shift in enzymatic degradation and mechanical properties due to autoclaving versus treatment with 70% EtOH. The changes in supramolecular organization in amorphous regions can retard enzyme diffusion through the glassy regions of the silk matrix or/and hinder binding of enzymes, while also stiffening these matrices. PMID:24519787

Gil, Eun Seok; Park, Sang-Hyug; Hu, Xiao; Cebe, Peggy; Kaplan, David L

2014-02-01

198

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)

Full Text Available SciELO Chile | Language: English Abstract in spanish 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

JOSÉ EDUARDO, SERRÃO.

199

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)

200

Tuning chemical and physical cross-links in silk electrogels for morphological analysis and mechanical reinforcement.  

Science.gov (United States)

Electrochemically controlled, reversible assembly of biopolymers into hydrogel structures is a promising technique for on-demand cell or drug encapsulation and release systems. An electrochemically sol-gel transition has been demonstrated in regenerated Bombyx mori silk fibroin, offering a controllable way to generate biocompatible and reversible adhesives and other biomedical materials. Despite the involvement of an electrochemically triggered electrophoretic migration of the silk molecules, the mechanism of the reversible electrogelation remains unclear. It is, however, known that the freshly prepared silk electrogels (e-gels) adopt a predominantly random coil conformation, indicating a lack of cross-linking as well as thermal, mechanical, and morphological stabilities. In the present work, the tuning of covalent and physical ?-sheet cross-links in silk hydrogels was studied for programming the structural properties. Scanning electron microscopy (SEM) revealed delicate morphology, including locally aligned fibrillar structures, in silk e-gels, preserved by combining glutaraldehyde-cross-linking and ethanol dehydration. Fourier transform infrared (FTIR) spectroscopic analysis of either electrogelled, vortex-induced or spontaneously formed silk hydrogels showed that the secondary structure of silk e-gels was tunable between non-?-sheet-dominated and ?-sheet-dominated states. Dynamic oscillatory rheology confirmed the mechanical reinforcement of silk e-gels provided by controlled chemical and physical cross-links. The selective incorporation of either chemical or physical or both cross-links into the electrochemically responsive, originally unstructured silk e-gel should help in the design for electrochemically responsive protein polymers. PMID:23859710

Lin, Yinan; Xia, Xiaoxia; Shang, Ke; Elia, Roberto; Huang, Wenwen; Cebe, Peggy; Leisk, Gary; Omenetto, Fiorenzo; Kaplan, David L

2013-08-12

 
 
 
 
201

Physical characterization of functionalized spider silk: electronic and sensing properties  

Directory of Open Access Journals (Sweden)

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.

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

202

Physical characterization of functionalized spider silk: electronic and sensing properties  

Science.gov (United States)

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.

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

203

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

Science.gov (United States)

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

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

2006-02-01

204

Material quality assessment of silk nanofibers based on swarm intelligence  

Science.gov (United States)

In this paper, we propose a novel approach for texture analysis based on artificial crawler model. Our method assumes that each agent can interact with the environment and each other. The evolution process converges to an equilibrium state according to the set of rules. For each textured image, the feature vector is composed by signatures of the live agents curve at each time. Experimental results revealed that combining the minimum and maximum signatures into one increase the classification rate. In addition, we pioneer the use of autonomous agents for characterizing silk fibroin scaffolds. The results strongly suggest that our approach can be successfully employed for texture analysis.

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

2013-02-01

205

Material quality assessment of silk nanofibers based on swarm intelligence  

International Nuclear Information System (INIS)

In this paper, we propose a novel approach for texture analysis based on artificial crawler model. Our method assumes that each agent can interact with the environment and each other. The evolution process converges to an equilibrium state according to the set of rules. For each textured image, the feature vector is composed by signatures of the live agents curve at each time. Experimental results revealed that combining the minimum and maximum signatures into one increase the classification rate. In addition, we pioneer the use of autonomous agents for characterizing silk fibroin scaffolds. The results strongly suggest that our approach can be successfully employed for texture analysis.

206

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

Science.gov (United States)

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

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

2014-01-01

207

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)

208

Homologues of fibroin L-chain and P25 of Bombyx mori are present in Dendrolimus spectabilis and Papilio xuthus but not detectable in Antheraea yamamai.  

Science.gov (United States)

Low molecular mass protein components of fibroin, whose electrophoretic patterns before and after the reductive cleavage of disulfide bonds were similar to those of L-chain and P25 of Bombyx mori, were identified in fibroin samples of Bombyx mandarina, Dendrolimus spectabilis and Papilio xuthus but not of Antheraea yamamai. Fibroin of A. yamamai is suggested to form a dimer of H-chain. Full length cDNA sequences were cloned for the homologues of L-chain and P25 from B. mandarina, D. spectabilis and P. xuthus. The deduced sequences of L-chain and P25 of B. mandarina are almost identical to those of B. mori, each containing a single amino acid change. Homologues of L-chain and P25 of D. spectabilis and P. xuthus show about 50% overall identity, respectively, with those of B. mori, but essential structural features; i.e. the three Cys residues in an L-chain and the eight Cys residues and one of the potential N-glycosylation sites in P25, are conserved in both species. These results, together with the published results for Galleria mellonella, suggest that the three-components (H-chain, L-chain and P25) complex of fibroin is rather common among Lepidopteran silk-producing insects, in contrast to the H-H dimer type found in the saturnid silkworm. PMID:11267905

Tanaka, K; Mizuno, S

2001-04-27

209

Study of the microstructure of silk artifacts recovered from a historic deep-ocean site  

Science.gov (United States)

A comparative study of the microstructure of three marine silk textiles recovered from the site of the S.S. Central America, reference silk fabric, and three historic silks from the same era as the marine textiles was conducted. The analytical techniques used include optical microscopy, scanning electron microscopy, energy dispersive x-ray spectrometry, x-ray diffraction, infrared microspectroscopy, and differential scanning calorimetry. Results indicate that the physical microstructure of two of the marine silk artifacts has been altered significantly. An increase in fiber diameter was observed in these two marine silks and their gross physical structure was considerably damaged. Crystallinity indices obtained from IR and XRD are lower in all of the marine and two of the historic silks in comparison with reference silk. Specimens vary in the extent to which short- and long-range order have been disturbed as a result of age and/or marine exposure. In all marine silks and two historic silks, the glass transition is suppressed and degradation temperature altered. Crystallite size perpendicular to the intersheet- and interchain-directions, and the unit cell dimensions, have not altered appreciably in any of the specimens. The primary effect of marine exposure appears to be conversion of some of the crystalline phase into an ordered-amorphous structure. Additionally, the amorphous phase is partially dissolved or recrystallized to an ordered-amorphous phase. No qualitative alteration of the chemical microstructure of fibroin was observed. Organic and inorganic surface deposits are observed on the marine silks but these are not as extensive on the historic artifacts. The formation of biofilm is observed on both the historic and marine silk, but to varying extents. Applicability of the analytical tools to analyze rare artifacts is addressed. While basic analytical studies are important in understanding the structure and degradation of rare artifacts, once understood, subsequent work should build on this research and employ techniques which require smaller samples. From a conservator's perspective, the results indicate that the marine silks are more susceptible to degradation than are historic silks. Handling and storage treatments should focus on controlling the environment and on treating the artifacts to minimize subsequent degradation.

Srinivasan, Rekha

210

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)

211

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

Science.gov (United States)

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 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.

Ayutsede, Jonathan Eyitouyo

212

Science Nation: Got Silk?  

Science.gov (United States)

Spider silk fibers are stronger than almost any other man-made fiber and they're also elastic. There are a lot of potential applications for the fiber, but how do you come up with enough raw material? With help from the National Science Foundation (NSF), researchers have figured out a way to put the spider's silk-making genes into goats in a way that they only make the protein in their milk.

213

Adrenal glands  

Science.gov (United States)

The adrenal glands are two triangle-shaped glands, one gland is located on top of each kidney. ... Each adrenal gland is about the size of the thumb. The outer part of the gland is called the cortex. It ...

214

Endocrine glands  

Science.gov (United States)

The endocrine system is primarily composed of glands that produce chemical messengers called hormones. Glands of the endocrine system include the pituitary gland, the thyroid gland, the parathyroid glands, the thymus, ...

215

Untangling spider silk evolution with spidroin terminal domains  

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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.

Garb Jessica E

2010-08-01

216

Novel aquatic silk genes Simulium (Psilozia) vittatum (Zett) Diptera: Simuliidae.  

Science.gov (United States)

The silks of arthropods have an elementary role in the natural history of the organisms that spin them, yet they are coded by rapidly evolving genes leading some authors to speculate that silk proteins are non-homologous proteins co-opted multiple times independently for similar functions. However, some general structural patterns are emerging. In this work we identified three major silk gland proteins using a combined biochemical, proteomic, next-generation sequencing and bioinformatic approach. Biochemical characterization determined that they were phosphorylated with multiple isoforms and potentially differential phosphorylation. Structural characterization showed that their structure was more similar to silk proteins from distantly related aquatic Trichopteran species than more closely related terrestrial or aquatic Diptera. Overall, our approach is easily transferable to any non-model species and if used across a larger number of aquatic species, we will be able to better understand the processes involved in linking the secondary structure of silk proteins with their function between in an organisms and its habitat. PMID:24446544

Papanicolaou, Alexie; Woo, Angelica; Brei, Brianna; Ma, Danjun; Masedunskas, Andrius; Gray, Elmer; Guishan Xiao, Gary; Cho, Soochin; Brockhouse, Charles

2013-12-01

217

Salivary Glands  

Science.gov (United States)

Salivary Glands Salivary Glands Patient Health Information News media interested in covering the latest from AAO-HNS/F can ... at newsroom@entnet.org . Where Are Your Salivary Glands? The glands are found in and around your ...

218

Pituitary gland  

Science.gov (United States)

The pituitary gland is often referred to as the "master gland" of the body, since it regulates many activities of other endocrine glands. Located above the pituitary gland is the hypothalamus. The hypothalamus decides which hormones ...

219

The Effect of Some Additives on the Bioproductive Performances of SilkWorm Bombyx mori L.  

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Full Text Available Nowdays, worldwide in sericulture domain, researches are aimed to find new efficient alternatives for the feeding of mulberry silk worm through the use of some fodder additives which allow the improvement of bioproductive parameters and silk line quality. The present work represents a review of the use of such substances (mineral and vitamin additives and of the experiments carried out to point out their effects on silkworms (Bombyx mori L.. Research conducted worldwide revealed the fact that the use of mineral and vitamin additives in silkworm Bombyx mori L., improve the growth rate of larvae, protein and mineral content of haemolymph, the protein content, DNA and RNA content of the sericigen glands, and the quality parameters of cocoon and silk line. Researches showed that the use of these additives doesn’t affect the quality of the silk.

Mihai Ben?ea

2011-05-01

220

21 CFR 184.1262 - Corn silk and corn silk extract.  

Science.gov (United States)

...Drugs 3 2010-04-01 2009-04-01 true Corn silk and corn silk extract. 184.1262 Section 184.1262 Food...Specific Substances Affirmed as GRAS § 184.1262 Corn silk and corn silk extract. (a) Corn silk is the...

2010-04-01

 
 
 
 
221

Complementary Effects of Two Growth Factors in Multifunctionalized Silk Nanofibers for Nerve Reconstruction  

Science.gov (United States)

With the aim of forming bioactive guides for peripheral nerve regeneration, silk fibroin was electrospun to obtain aligned nanofibers. These fibers were functionalized by incorporating Nerve Growth Factor (NGF) and Ciliary NeuroTrophic Factor (CNTF) during electrospinning. PC12 cells grown on the fibers confirmed the bioavailability and bioactivity of the NGF, which was not significantly released from the fibers. Primary neurons from rat dorsal root ganglia (DRGs) were grown on the nanofibers and anchored to the fibers and grew in a directional fashion based on the fiber orientation, and as confirmed by growth cone morphology. These biofunctionalized nanofibers led to a 3-fold increase in neurite length at their contact, which was likely due to the NGF. Glial cell growth, alignment and migration were stimulated by the CNTF in the functionalized nanofibers. Organotypic culture of rat fetal DRGs confirmed the complementary effect of both growth factors in multifunctionalized nanofibers, which allowed glial cell migration, alignment and parallel axonal growth in structures resembling the ‘bands of Bungner’ found in situ. Graftable multi-channel conduits based on biofunctionalized aligned silk nanofibers were developed as an organized 3D scaffold. Our bioactive silk tubes thus represent new options for a biological and biocompatible nerve guidance conduit. PMID:25313579

Jose, Rodrigo R.; Vigneron, Pascale; Bresson, Damien; Fitzpatrick, Vincent; Marin, Frederic; Kaplan, David L.; Egles, Christophe

2014-01-01

222

Complementary effects of two growth factors in multifunctionalized silk nanofibers for nerve reconstruction.  

Science.gov (United States)

With the aim of forming bioactive guides for peripheral nerve regeneration, silk fibroin was electrospun to obtain aligned nanofibers. These fibers were functionalized by incorporating Nerve Growth Factor (NGF) and Ciliary NeuroTrophic Factor (CNTF) during electrospinning. PC12 cells grown on the fibers confirmed the bioavailability and bioactivity of the NGF, which was not significantly released from the fibers. Primary neurons from rat dorsal root ganglia (DRGs) were grown on the nanofibers and anchored to the fibers and grew in a directional fashion based on the fiber orientation, and as confirmed by growth cone morphology. These biofunctionalized nanofibers led to a 3-fold increase in neurite length at their contact, which was likely due to the NGF. Glial cell growth, alignment and migration were stimulated by the CNTF in the functionalized nanofibers. Organotypic culture of rat fetal DRGs confirmed the complementary effect of both growth factors in multifunctionalized nanofibers, which allowed glial cell migration, alignment and parallel axonal growth in structures resembling the 'bands of Bungner' found in situ. Graftable multi-channel conduits based on biofunctionalized aligned silk nanofibers were developed as an organized 3D scaffold. Our bioactive silk tubes thus represent new options for a biological and biocompatible nerve guidance conduit. PMID:25313579

Dinis, Tony M; Vidal, Guillaume; Jose, Rodrigo R; Vigneron, Pascale; Bresson, Damien; Fitzpatrick, Vincent; Marin, Frédéric; Kaplan, David L; Egles, Christophe

2014-01-01

223

Morphology and histology of Lyonet's gland of the tropical tasar silkworm, Antheraea mylitta.  

Science.gov (United States)

The morphology and histology of Lyonet's gland in the second to fifth instar larvae of Antheraea mylitta Drury (Lepidoptera: Saturniidae) are described. Each of the paired silk glands of this silk worm were associated with a Lyonet's gland. The paired Lyonet's glands were located on the ventrolateral sides of the esophagus, close to the subesophageal ganglion. Whole mount and SEM observations revealed that each Lyonet's gland consisted of a rosette of glandular mass, and a short narrow tubular duct opening into the anterior part of the silk gland (ASG), close to the common excretory duct. In each instar, these glands were unequal in size. The glandular mass was innervated by fine nerves from the subesophageal ganglion, suggesting a neural control for the glandular activity. The glandular mass was made up of clustered long cells wrapped by a thin basal lamina, which was continuous over the non-secretory low columnar cells of the Lyonet's gland duct and ASG. The narrow bases of long cells of each glandular mass led into the lumen of the duct of the gland. Histochemical analysis of fully developed Lyonet's gland showed clustered lipid granules in the gland cells. PMID:23451934

Patra, Sudip; Singh, Ravindra Nath; Raziuddin, Mohammad

2012-01-01

224

Optically probing torsional superelasticity in spider silks  

Science.gov (United States)

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 102-3 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.

Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

2013-11-01

225

Optically probing torsional superelasticity in spider silks  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2013-11-11

226

THE INHERENT ACIDIC CHARACTERISTICS OF SILK, PART II – WEIGHTED SILKS  

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Full Text Available Silk is found in many textiles of cultural and historic significance,but these fibres may deteriorate rapidly underadverse conditions, so are of particular concern to conservatorsand curators. Measurement of pH is common practicewhen assessing condition, as enhanced acidity is oftenascribed to previous processing and treatment, adsorbedpollutants and oxidative deterioration, but recent researchhas demonstrated that the increased acidity of silk is anexpected consequence of ageing, irrespective of the causeof deterioration. The study presented here builds on thisearlier work to assess the role that common silk processingmethods (bleaching and metal salt weighting have onthis phenomenon. Tensile strength was used as a marker ofdeterioration, independent of mechanism, and was comparedwith pH values of saline extracts of various silk samples.These samples included surrogates, prepared usinghistorically accurate methods and subject to acceleratedageing, as well as a range of historic materials. It was seenthat most samples followed the same correlation betweenpH and strength as seen in the previous work. However,silks weighted with tin salts appeared to be buffered (in therange pH 6.75-7.05, irrespective of their mechanicalintegrity.

Paul Garside

2010-01-01

227

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

Science.gov (United States)

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

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

2013-09-10

228

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

229

Silks as ancient models for modern polymers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Vollrath, Fritz; Porter, David

2009-01-01

230

Spidroin N-terminal Domain Promotes a pH-dependent Association of Silk Proteins during Self-assembly*  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Spider silks are spun from concentrated solutions of spidroin proteins. The appropriate timing of spidroin assembly into organized fibers must be highly regulated to avoid premature fiber formation. Chemical and physical signals presented to the silk proteins as they pass from the ampulle and through the tapered duct include changes in ionic environment and pH as well as the introduction of shear forces. Here, we show that the N-terminal domain of spidroins from the major ampullate gland (MaS...

Gaines, William A.; Sehorn, Michael G.; Marcotte, William R.

2010-01-01

231

Antheraea pernyi Silk Fiber: A Potential Resource for Artificially Biospinning Spider Dragline Silk  

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Full Text Available The outstanding properties of spider dragline silk are likely to be determined by a combination of the primary sequences and the secondary structure of the silk proteins. Antheraea pernyi silk has more similar sequences to spider dragline silk than the silk from its domestic counterpart, Bombyx mori. This makes it much potential as a resource for biospinning spider dragline silk. This paper further verified its possibility as the resource from the mechanical properties and the structures of the A. pernyi silks prepared by forcible reeling. It is surprising that the stress-strain curves of the A. pernyi fibers show similar sigmoidal shape to those of spider dragline silk. Under a controlled reeling speed of 95?mm/s, the breaking energy was 1.04×105?J/kg, the tensile strength was 639 MPa and the initial modulus was 9.9 GPa. It should be noted that this breaking energy of the A. pernyi silk approaches that of spider dragline silk. The tensile properties, the optical orientation and the ?-sheet structure contents of the silk fibers are remarkably increased by raising the spinning speeds up to 95?mm/s.

Yaopeng Zhang

2010-01-01

232

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

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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.

AGATHA AGATHA POPESCU

2013-10-01

233

Convergently-evolved structural anomalies in the coiled coil domains of insect silk proteins.  

Science.gov (United States)

The use of coiled coil proteins as the basis of silk materials is an engineering solution that has evolved convergently in at least five insect lineages-the stinging hymenopterans (ants, bees, hornets), argid sawflies, fleas, lacewings, and praying mantises-and persisted throughout large radiations of these insect families. These coiled coil silk proteins share a characteristic distinct from other coiled coil proteins, in that they are fabricated into solid materials after accumulating as highly concentrated solutions within dedicated glands. Here, we relate the amino acid sequences of these proteins to the secondary and tertiary structural information available from biophysical methods such as X-ray scattering, nuclear magnetic resonance and Raman spectroscopy. We investigate conserved and convergently evolved features within these proteins and compare these to the features of classic coiled coil proteins including tropomyosin and leucine zippers. Our analysis finds that the coiled coil domains of insect silk proteins have several common structural anomalies including a high prevalence of alanine residues in core positions. These atypical features of the coiled coil fibrous proteins - which likely produce deviations from canonical coiled-coil structure - likely exist due to selection pressures related to the process of silk fabrication and the final function of the proteins. PMID:24434611

Sutherland, Tara D; Trueman, Holly E; Walker, Andrew A; Weisman, Sarah; Campbell, Peter M; Dong, Zhaoming; Huson, Mickey G; Woodhead, Andrea L; Church, Jeffrey S

2014-06-01

234

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

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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

Sun L

2012-02-01

235

Single honeybee silk protein mimics properties of multi-protein silk.  

Science.gov (United States)

Honeybee silk is composed of four fibrous proteins that, unlike other silks, are readily synthesized at full-length and high yield. The four silk genes have been conserved for over 150 million years in all investigated bee, ant and hornet species, implying a distinct functional role for each protein. However, the amino acid composition and molecular architecture of the proteins are similar, suggesting functional redundancy. In this study we compare materials generated from a single honeybee silk protein to materials containing all four recombinant proteins or to natural honeybee silk. We analyse solution conformation by dynamic light scattering and circular dichroism, solid state structure by Fourier Transform Infrared spectroscopy and Raman spectroscopy, and fiber tensile properties by stress-strain analysis. The results demonstrate that fibers artificially generated from a single recombinant silk protein can reproduce the structural and mechanical properties of the natural silk. The importance of the four protein complex found in natural silk may lie in biological silk storage or hierarchical self-assembly. The finding that the functional properties of the mature material can be achieved with a single protein greatly simplifies the route to production for artificial honeybee silk. PMID:21311767

Sutherland, Tara D; Church, Jeffrey S; Hu, Xiao; Huson, Mickey G; Kaplan, David L; Weisman, Sarah

2011-01-01

236

Designing silk-silk protein alloy materials for biomedical applications.  

Science.gov (United States)

Fibrous proteins display different sequences and structures that have been used for various applications in biomedical fields such as biosensors, nanomedicine, tissue regeneration, and drug delivery. Designing materials based on the molecular-scale interactions between these proteins will help generate new multifunctional protein alloy biomaterials with tunable properties. Such alloy material systems also provide advantages in comparison to traditional synthetic polymers due to the materials biodegradability, biocompatibility, and tenability in the body. This article used the protein blends of wild tussah silk (Antheraea pernyi) and domestic mulberry silk (Bombyx mori) as an example to provide useful protocols regarding these topics, including how to predict protein-protein interactions by computational methods, how to produce protein alloy solutions, how to verify alloy systems by thermal analysis, and how to fabricate variable alloy materials including optical materials with diffraction gratings, electric materials with circuits coatings, and pharmaceutical materials for drug release and delivery. These methods can provide important information for designing the next generation multifunctional biomaterials based on different protein alloys. PMID:25145602

Hu, Xiao; Duki, Solomon; Forys, Joseph; Hettinger, Jeffrey; Buchicchio, Justin; Dobbins, Tabbetha; Yang, Catherine

2014-01-01

237

How to visualize the spider mite silk?  

Science.gov (United States)

Tetranychus urticae (Acari: Tetranychidae) is a phytophagous mite that forms colonies of several thousand individuals. Like spiders, every individual produces abundant silk strands and is able to construct a common web for the entire colony. Despite the importance of this silk for the biology of this worldwide species, only one previous study suggested how to visualize it. To analyze the web structuration, we developed a simple technique to dye T. urticae'silk on both inert and living substrates. Fluorescent brightener 28 (FB) (Sigma F3543) diluted in different solvents at different concentrations regarding the substrate was used to observe single strands of silk. On glass lenses, a 0.5% dimethyl sulfoxide solution was used and on bean leaves, a 0.1% aqueous solution. A difference of silk deposit was observed depending the substrate: rectilinear threads on glass lenses and more sinuous ones on bean leaves. This visualizing technique will help to carry out future studies about the web architecture and silk used by T. urticae. It might also be useful for the study of other silk-spinning arthropods. PMID:19322898

Clotuche, G; Le Goff, G; Mailleux, A-C; Deneubourg, J-L; Detrain, C; Hance, T

2009-09-01

238

Pineal and Pituitary Glands  

Science.gov (United States)

... after updating. Resources Archived Modules Updates Pineal and Pituitary Glands The pineal gland is a small endocrine gland ... of the corpus callosum, and secretes melatonin . The pituitary gland is located at the base of the brain ...

239

TUMORS OF SALIVARY GLANDS  

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

Gaurav Solanki

2012-01-01

240

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

Science.gov (United States)

Spider silk fibers are produced from soluble proteins (spidroins) under ambient conditions in a complex but poorly understood process. Spidroins are highly repetitive in sequence but capped by nonrepetitive N- and C-terminal domains (NT and CT) that are suggested to regulate fiber conversion in similar manners. By using ion selective microelectrodes we found that the pH gradient in the silk gland is much broader than previously known. Surprisingly, the terminal domains respond in opposite ways when pH is decreased from 7 to 5: Urea denaturation and temperature stability assays show that NT dimers get significantly stabilized and then lock the spidroins into multimers, whereas CT on the other hand is destabilized and unfolds into ThT-positive ?-sheet amyloid fibrils, which can trigger fiber formation. There is a high carbon dioxide pressure (pCO2) in distal parts of the gland, and a CO2 analogue interacts with buried regions in CT as determined by nuclear magnetic resonance (NMR) spectroscopy. Activity staining of histological sections and inhibition experiments reveal that the pH gradient is created by carbonic anhydrase. Carbonic anhydrase activity emerges in the same region of the gland as the opposite effects on NT and CT stability occur. These synchronous events suggest a novel CO2 and proton-dependent lock and trigger mechanism of spider silk formation. PMID:25093327

Otikovs, Martins; Landreh, Michael; Nordling, Kerstin; Kronqvist, Nina; Westermark, Per; Jornvall, Hans; Knight, Stefan; Ridderstrale, Yvonne; Holm, Lena; Meng, Qing; Jaudzems, Kristaps; Chesler, Mitchell; Johansson, Jan; Rising, Anna

2014-01-01

 
 
 
 
241

Carbonic anhydrase generates CO2 and H+ that drive spider silk formation via opposite effects on the terminal domains.  

Science.gov (United States)

Spider silk fibers are produced from soluble proteins (spidroins) under ambient conditions in a complex but poorly understood process. Spidroins are highly repetitive in sequence but capped by nonrepetitive N- and C-terminal domains (NT and CT) that are suggested to regulate fiber conversion in similar manners. By using ion selective microelectrodes we found that the pH gradient in the silk gland is much broader than previously known. Surprisingly, the terminal domains respond in opposite ways when pH is decreased from 7 to 5: Urea denaturation and temperature stability assays show that NT dimers get significantly stabilized and then lock the spidroins into multimers, whereas CT on the other hand is destabilized and unfolds into ThT-positive ?-sheet amyloid fibrils, which can trigger fiber formation. There is a high carbon dioxide pressure (pCO2) in distal parts of the gland, and a CO2 analogue interacts with buried regions in CT as determined by nuclear magnetic resonance (NMR) spectroscopy. Activity staining of histological sections and inhibition experiments reveal that the pH gradient is created by carbonic anhydrase. Carbonic anhydrase activity emerges in the same region of the gland as the opposite effects on NT and CT stability occur. These synchronous events suggest a novel CO2 and proton-dependent lock and trigger mechanism of spider silk formation. PMID:25093327

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; Rising, Anna

2014-08-01

242

Salivary Gland Disorders  

Science.gov (United States)

Your salivary glands make saliva - sometimes called spit - and empty it into your mouth through openings called ducts. Saliva makes your ... antibodies that can kill germs. Problems with salivary glands can cause the glands to become irritated and ...

243

Laparoscopic Adrenal Gland Removal  

Science.gov (United States)

... Sponsorship Opportunities Login Patient Information for Laparoscopic Adrenal Gland Removal (Adrenalectomy) from SAGES Download PDF Version Find a SAGES Surgeon WHAT ARE THE ADRENAL GLANDS? The adrenal glands are two small organs, one ...

244

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 ...

245

Spidroin N-terminal Domain Promotes a pH-dependent Association of Silk Proteins during Self-assembly*  

Science.gov (United States)

Spider silks are spun from concentrated solutions of spidroin proteins. The appropriate timing of spidroin assembly into organized fibers must be highly regulated to avoid premature fiber formation. Chemical and physical signals presented to the silk proteins as they pass from the ampulle and through the tapered duct include changes in ionic environment and pH as well as the introduction of shear forces. Here, we show that the N-terminal domain of spidroins from the major ampullate gland (MaSp-NTDs) for both Nephila and Latrodectus spiders associate noncovalently as homodimers. The MaSp-NTDs are highly pH-responsive and undergo a structural transition in the physiological pH range of the spider duct. Tryptophan fluorescence of the MaSp-NTDs reveals a change in conformation when pH is decreased, and the pH at which the transition occurs is determined by the amount and type of salt present. Size exclusion chromatography and pulldown assays both indicate that the lower pH conformation is associated with a significantly increased MaSp-NTD homodimer stability. By transducing the duct pH signal into specific protein-protein interactions, this conserved spidroin domain likely contributes significantly to the silk-spinning process. Based on these results, we propose a model of spider silk assembly dynamics as mediated through the MaSp-NTD. PMID:20959449

Gaines, William A.; Sehorn, Michael G.; Marcotte, William R.

2010-01-01

246

Spidroin N-terminal domain promotes a pH-dependent association of silk proteins during self-assembly.  

Science.gov (United States)

Spider silks are spun from concentrated solutions of spidroin proteins. The appropriate timing of spidroin assembly into organized fibers must be highly regulated to avoid premature fiber formation. Chemical and physical signals presented to the silk proteins as they pass from the ampulle and through the tapered duct include changes in ionic environment and pH as well as the introduction of shear forces. Here, we show that the N-terminal domain of spidroins from the major ampullate gland (MaSp-NTDs) for both Nephila and Latrodectus spiders associate noncovalently as homodimers. The MaSp-NTDs are highly pH-responsive and undergo a structural transition in the physiological pH range of the spider duct. Tryptophan fluorescence of the MaSp-NTDs reveals a change in conformation when pH is decreased, and the pH at which the transition occurs is determined by the amount and type of salt present. Size exclusion chromatography and pulldown assays both indicate that the lower pH conformation is associated with a significantly increased MaSp-NTD homodimer stability. By transducing the duct pH signal into specific protein-protein interactions, this conserved spidroin domain likely contributes significantly to the silk-spinning process. Based on these results, we propose a model of spider silk assembly dynamics as mediated through the MaSp-NTD. PMID:20959449

Gaines, William A; Sehorn, Michael G; Marcotte, William R

2010-12-24

247

Endocrine Glands & Their Hormones  

Science.gov (United States)

... Female Reproductive System Ovaries Genital Tract External Genitalia Female Sexual ... Glands & Their Hormones The endocrine system is made up of the endocrine glands that secrete hormones. Although ...

248

Recombinant Spider Silks—Biopolymers with Potential for Future Applications  

Directory of Open Access Journals (Sweden)

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

Thomas Scheibel

2011-03-01

249

Differential transcription of multiple copies of a silk worm gene encoding tRNA(Gly1).  

Science.gov (United States)

Ten different tRNA(Gly1) genes from the silk worm, Bombyx mori, have been cloned and characterized. These genes were transcribed in vitro in homologous nuclear extracts from the posterior silk gland (PSG) or nuclear extracts derived from the middle silk gland or ovarian tissues. Although the transcription levels were much higher in the PSG nuclear extracts, the transcriptional efficiency of the individual genes followed a similar pattern in all the extracts. Based on the levels of in vitro transcription, the ten tRNA(Gly1) genes could be divided into three groups, viz., those which were transcribed at very high levels (e.g., clone pR8), high to medium levels (e.g., pBmi1, pBmp1, pBmh1, pBmt1) and low to barely detectable levels (e.g., pBms1, pBmj1 and pBmk1). The coding sequences of all these tRNA genes being identical, the differential transcription suggested that the flanking sequences modulate their transcriptional efficiency. The presence of positive and negative regulatory elements in the 5' flanking regions of these genes was confirmed by transcription competition experiments. A positive element was present in the immediate upstream A+T-rich sequences in all the genes, but no consensus sequences correlating to the transcriptional status could be generated. The presence of negative elements on the other hand was indicated only in some of the genes and therefore may have a role in the differential transcription of these tRNA(Gly1) genes in vivo. PMID:8262376

Fournier, A; Taneja, R; Gopalkrishnan, R; Prudhomme, J C; Gopinathan, K P

1993-12-01

250

Structural characterization of nanofiber silk produced by embiopterans (webspinners)†  

Science.gov (United States)

Embiopterans produce silken galleries and sheets using exceptionally fine silk fibers in which they live and breed. In this study, we use electron microscopy (EM), Fourier-transform infrared (FT-IR) spectroscopy, wide angle X-ray diffraction (WAXD) and solid-state nuclear magnetic resonance (ssNMR) techniques to elucidate the molecular level protein structure of webspinner (embiid) silks. Silks from two species Antipaluria urichi and Aposthonia ceylonica are studied in this work. Electron microscopy images show that the fibers are about 90–100 nm in diameter, making webspinner silks among the finest of all known animal silks. Structural studies reveal that the silk protein core is dominated by ?-sheet structures, and that the protein core is coated with a hydrophobic alkane-rich surface coating. FTIR spectra of native embiid silk shows characteristic alkane CH2 stretchings near 2800–2900 cm?1, which decrease approximately 50% after washing the silk with 2 : 1 CHCl3 : MeOH. Furthermore, 13C ssNMR data shows a significant CH2 resonance that is strongly affected by the presence of water, supporting the idea that the silk fibers are coated with a hydrocarbon-rich layer. Such a layer is likely used to protect the colonies from rain. FTIR data also suggests that embiid silks are dominated by ?-sheet secondary structures similar to spider and silkworm silk fibers. NMR data confirms the presence of ?-sheet nanostructures dominated by serine-rich repetitive regions. A deconvolution of the serine C? NMR resonance reveals that approximately 70% of all seryl residues exist in a ?-sheet structure. This is consistent with WAXD results that suggest webspinner silks are 70% crystalline, which is the highest crystalline fraction reported for any animal silks. The work presented here provides a molecular level structural picture of silk fibers produced by webspinners.

Addison, J. Bennett; Popp, Thomas M. Osborn; Weber, Warner S.; Edgerly, Janice S.; Holland, Gregory P.; Yarger, Jeffery L.

2014-01-01

251

The Inherent Acidic Characteristics of Aged Silk  

Directory of Open Access Journals (Sweden)

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.

Paul Wyeth

2008-01-01

252

The Ancient Art of Silk Painting  

Science.gov (United States)

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.)

Yonker, Kim

2010-01-01

253

Lacrimal Gland Tumor  

Science.gov (United States)

... Home > Types of Cancer > Lacrimal Gland Tumor Lacrimal Gland Tumor This is Cancer.Net’s Guide to Lacrimal Gland Tumor. Use the menu below to choose the ... workers, and patient advocates. Cancer.Net Guide Lacrimal Gland Tumor Overview Statistics Risk Factors Symptoms and Signs ...

254

Adrenal Gland Tumor  

Science.gov (United States)

... Home > Types of Cancer > Adrenal Gland Tumor Adrenal Gland Tumor This is Cancer.Net’s Guide to Adrenal Gland Tumor. Use the menu below to choose the ... workers, and patient advocates. Cancer.Net Guide Adrenal Gland Tumor Overview Statistics Risk Factors Symptoms and Signs ...

255

Salivary gland tumors  

Science.gov (United States)

Salivary gland tumors are abnormal cells growing in the tubes (ducts) that drain the salivary glands or the gland itself. ... The salivary glands are located around the mouth. They produce saliva, which moistens food to help with chewing and swallowing. There ...

256

Electrodeposited silk coatings for functionalized implant applications  

Science.gov (United States)

The mechanical and morphological properties of titanium as well as its biocompatibility and osteoinductive characteristics have made it the material of choice for dental implant systems. Although the success rate of titanium implants exceeds 90% in healthy individuals, a large subset of the population has one or more risk factors that inhibit implant integration. Treatments and coatings have been developed to improve clinical outcomes via introduction of appropriate surface topography, texture and roughness or incorporation of bioactive molecules. It is essential that the coatings and associated deposition techniques are controllable and reproducible. Currently, methods of depositing functional coatings are dictated by numerous parameters (temperature, particle size distribution, pH and voltage), which result in variable coating thickness, strength, porosity and weight, and hinder or preclude biomolecule incorporation. Silk is a highly versatile protein with a unique combination of mechanical and physical properties, including tunable degradation, biocompatibility, drug stabilizing capabilities and mechanical properties. Most recently an electrogelation technique was developed which allows for the deposition of gels which dry seamlessly over the contoured topography of the conductive substrate. In this work we examine the potential use of silk electrogels as mechanically robust implant coatings capable of sequestering and releasing therapeutic agents. Electrodeposition of silk electrogels formed in uniform electric fields was characterized with respect to field intensity and deposition time. Gel formation kinetics were used to derive functions which allowed for the prediction of coating deposition over a range of process and solution parameters. Silk electrogel growth orientation was shown to be influenced by the applied electric field. Coatings were reproducible and tunable via intrinsic silk solution properties and extrinsic process parameters. Adhesion was modulated over a 10-fold range and implant insertion into bone mimics demonstrated that the coatings were able to withstand delamination forces experienced during these mock implantations. Antibiotic release from coated implant studs inhibited bacterial growth and dexamethasone release was shown to stimulate calcium deposition in mesenchymal stem cells.

Elia, Roberto

257

SALIVARY GLANDS - AN OVERVIEW  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The glands are divided into major and minor salivary gland categories. The major salivary glands are parotid, submandibular and sublingual glands. The minor glands are dispersed throughout the upper aero-digestive submucosa. Saliva is the watery substance produced in the mouths of humans and other animals. Saliva is a component of oral fluid. Human saliva is composed of 98% water, while the other 2% consists o...

Gaurav Solanki

2012-01-01

258

Nuclear alterations associated to programmed cell death in larval salivary glands of Apis mellifera (Hymenoptera: Apidae).  

Science.gov (United States)

The silk glands of bees are a good model for the study of cell death in insects. With the objective to detect the nuclear features during glandular regression stage, larvae at the last instar and pre-pupae were collected and their silk glands were dissected and processed for ultrastructural analysis and histologically for cytochemical and imunocytochemical analysis. The results showed that the cellular nuclei exhibited characteristics of death by atypical apoptosis as well as autophagic cell death. Among the apoptosis characteristic were: nuclear strangulation with bleb formation in some nuclei, DNA fragmentation in most of the nuclei and nucleolar fragmentation. Centripetal chromatin compaction was observed in many nuclei, forming a perichromatin halo differing from typical apoptotic nuclei. With regards to the characteristics of autophagic-programmed cell death, most relevant was the delay in the collapse of many nuclei. PMID:17251032

Silva-Zacarin, E C M; Taboga, S R; Silva de Moraes, R L M

2008-01-01

259

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)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

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

2014-06-01

260

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)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

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

 
 
 
 
261

Silk-based biomaterials for sustained drug delivery.  

Science.gov (United States)

Silk presents a rare combination of desirable properties for sustained drug delivery, including aqueous-based purification and processing options without chemical cross-linkers, compatibility with common sterilization methods, controllable and surface-mediated biodegradation into non-inflammatory by-products, biocompatibility, utility in drug stabilization, and robust mechanical properties. A versatile silk-based toolkit is currently available for sustained drug delivery formulations of small molecule through macromolecular drugs, with a promise to mitigate several drawbacks associated with other degradable sustained delivery technologies in the market. Silk-based formulations utilize silk's well-defined nano- through microscale structural hierarchy, stimuli-responsive self-assembly pathways and crystal polymorphism, as well as sequence and genetic modification options towards targeted pharmaceutical outcomes. Furthermore, by manipulating the interactions between silk and drug molecules, near-zero order sustained release may be achieved through diffusion- and degradation-based release mechanisms. Because of these desirable properties, there has been increasing industrial interest in silk-based drug delivery systems currently at various stages of the developmental pipeline from pre-clinical to FDA-approved products. Here, we discuss the unique aspects of silk technology as a sustained drug delivery platform and highlight the current state of the art in silk-based drug delivery. We also offer a potential early development pathway for silk-based sustained delivery products. PMID:24910193

Yucel, Tuna; Lovett, Michael L; Kaplan, David L

2014-09-28

262

Electrospun Silk Biomaterial Scaffolds for Regenerative Medicine  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Electrospinning is a versatile technique that enables the development of nanofiber-based biomaterial scaffolds. Scaffolds can be generated that are useful for tissue engineering and regenerative medicine since they mimic the nanoscale properties of certain fibrous components of the native extracellular matrix in tissues. Silk is a natural protein with excellent biocompatibility, remarkable mechanical properties as well as tailorable degradability. Integrating these protein polymer advantages ...

Zhang, Xiaohui; Reagan, Michaela R.; Kaplan, David L.

2009-01-01

263

Enlarged prostate gland  

Science.gov (United States)

The prostate gland is located underneath the bladder and is about the size of a chestnut. In this cut section, you ... of the urethra is encased within the prostate gland. As a man ages, the prostate typically enlarges ...

264

The failure mode of natural silk epoxy triggered composite tubes  

International Nuclear Information System (INIS)

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

265

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)

266

Corn silk induces nitric oxide synthase in murine macrophages.  

Science.gov (United States)

Corn silk has been purified as an anticoagulant previously and the active component is a polysaccharide with a molecular mass of 135 kDa. It activates murine macrophages to induce nitric oxide synthase (NOS) and generate substantial amounts of NO in time and dose-dependent manners. It was detectable first at 15 h after stimulation by corn silk, peaked at 24 h, and undetectable by 48 h. Induction of NOS is inhibited by pyrolidine dithiocarbamate (PDTC) and genistein, an inhibitor of nuclear factor kappa B (NF-kappaB) and tyrosine kinase, respectively, indicating that iNOS stimulated by corn silk is associated with tyrosine kinase and NF-kappaB signaling pathways. IkappaB-alpha degradation was detectible at 10 min, and the level was restored at 120 min after treatment of corn silk. Corn silk induced nuclear translocation of NF-kappaB by phosphorylation and degradation of IkappaB-alpha. PMID:15665587

Kim, Kyung A; Choi, Sang Kyu; Choi, Hye Seon

2004-12-31

267

Stabilization of viruses by encapsulation in silk proteins.  

Science.gov (United States)

Viruses are important for a range of modern day applications. However, their utility is limited by their susceptibility to temperature degradation. In this study, we report a simple system to compare the ability of different dried protein films to stabilize viruses against exposure to elevated temperatures. Films from each of three different silks, silkworm, honeybee silk and hornet silk, stabilized entrapped viruses at 37 °C better than films of albumin from bovine serum (BSA) and all four proteins provided substantially more stabilization than no protein controls. A comparison of the molecular structure of the silks and BSA films showed no correlation between the ability of the proteins to stabilize the virus and the secondary structure of the protein in the films. The mechanism of stabilization is discussed and a hypothesis is suggested to explain the superior performance of the silk proteins. PMID:25229876

Sutherland, Tara D; Sriskantha, Alagacone; Church, Jeffrey S; Strive, Tanja; Trueman, Holly E; Kameda, Tsunenori

2014-10-22

268

Determination of Metals in Thai Silk by Neutron Activation Analysis  

International Nuclear Information System (INIS)

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

269

Spinning gland transcriptomics from two main clades of spiders (order: Araneae)--insights on their molecular, anatomical and behavioral evolution.  

Science.gov (United States)

Characterized by distinctive evolutionary adaptations, spiders provide a comprehensive system for evolutionary and developmental studies of anatomical organs, including silk and venom production. Here we performed cDNA sequencing using massively parallel sequencers (454 GS-FLX Titanium) to generate ?80,000 reads from the spinning gland of Actinopus spp. (infraorder: Mygalomorphae) and Gasteracantha cancriformis (infraorder: Araneomorphae, Orbiculariae clade). Actinopus spp. retains primitive characteristics on web usage and presents a single undifferentiated spinning gland while the orbiculariae spiders have seven differentiated spinning glands and complex patterns of web usage. MIRA, Celera Assembler and CAP3 software were used to cluster NGS reads for each spider. CAP3 unigenes passed through a pipeline for automatic annotation, classification by biological function, and comparative transcriptomics. Genes related to spider silks were manually curated and analyzed. Although a single spidroin gene family was found in Actinopus spp., a vast repertoire of specialized spider silk proteins was encountered in orbiculariae. Astacin-like metalloproteases (meprin subfamily) were shown to be some of the most sampled unigenes and duplicated gene families in G. cancriformis since its evolutionary split from mygalomorphs. Our results confirm that the evolution of the molecular repertoire of silk proteins was accompanied by the (i) anatomical differentiation of spinning glands and (ii) behavioral complexification in the web usage. Finally, a phylogenetic tree was constructed to cluster most of the known spidroins in gene clades. This is the first large-scale, multi-organism transcriptome for spider spinning glands and a first step into a broad understanding of spider web systems biology and evolution. PMID:21738742

Prosdocimi, Francisco; Bittencourt, Daniela; da Silva, Felipe Rodrigues; Kirst, Matias; Motta, Paulo C; Rech, Elibio L

2011-01-01

270

EFFECT OF METHANOLIC EXTRACT OF SWEET CORN SILK ON EXPERIMENTALLY INDUCED HYPERTHYROIDISM IN SWISS ALBINO RATS  

Directory of Open Access Journals (Sweden)

Full Text Available Plant materials have been used as medicine for a wide variety of human ailments due to increase in cost of treatment, side effects of several allopathic drugs and development of resistance to currently used drugs for infectious diseases. In the present study, hyperthyroidism was induced to male Swiss albino rats orally using thyroxine for 14 days. The impact of methanolic extract of sweet corn silk in different concentrations (200, 300 & 400mg/kg for 21 days was assessed in these animals. The serum was analyzed for thyroid hormone level and lipid profile before and during the experiment. Results showed that 400mg/kg concentration of methanolic extract has the highest effectiveness which is equal to that of standard drug to revert the hyperthyroid condition in Swiss albino rats and were confirmed with the histopathological study of the thyroid gland.

Thoudam Bhaigyabati

2012-03-01

271

Electricity from the Silk Cocoon Membrane  

Science.gov (United States)

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.

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

272

Occupational Dermatoses Among The Silk Workers  

Directory of Open Access Journals (Sweden)

Full Text Available Pilot study was conducted among the workers of a silk filature prior to undertaking a study on the efficacy of barrier creams in preventing the dermatoses. Commonest occupational dermatoses noticed were maceration (68%, nicked nails (61%, pitted keratolysis (38%, fissuring (31% and erosion (22.7%. Our findings were consistent with the earlier studies. However, ichthyosis reported earlier was not observed. The study was undertaken during summer and hence we conclude that ichtyosis is possibly due to seasonal variation and may not be related to hereditary factors as was postulated.

Kanthraj G.R

1996-01-01

273

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

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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.

Jongejan Frans

2010-03-01

274

Inhibitory effect of corn silk on skin pigmentation.  

Science.gov (United States)

In this study, the inhibitory effect of corn silk on melanin production was evaluated. This study was performed to investigate the inhibitory effect of corn silk on melanin production in Melan-A cells by measuring melanin production and protein expression. The corn silk extract applied on Melan-A cells at a concentration of 100 ppm decreased melanin production by 37.2% without cytotoxicity. This was a better result than arbutin, a positive whitening agent, which exhibited a 26.8% melanin production inhibitory effect at the same concentration. The corn silk extract did not suppress tyrosinase activity but greatly reduced the expression of tyrosinase in Melan-A cells. In addition, corn silk extract was applied to the human face with hyperpigmentation, and skin color was measured to examine the degree of skin pigment reduction. The application of corn silk extract on faces with hyperpigmentation significantly reduced skin pigmentation without abnormal reactions. Based on the results above, corn silk has good prospects for use as a material for suppressing skin pigmentation. PMID:24595276

Choi, Sang Yoon; Lee, Yeonmi; Kim, Sung Soo; Ju, Hyun Min; Baek, Ji Hwoon; Park, Chul-Soo; Lee, Dong-Hyuk

2014-01-01

275

Adrenal Gland Disorders: Condition Information  

Science.gov (United States)

... Clinical Trials Resources and Publications En Español Adrenal Gland Disorders: Condition Information Skip sharing on social media ... Share this: Page Content What are the adrenal glands? The adrenal glands, located on the top of ...

276

Synthesis and characterization of water-soluble silk peptides and recombinant silk protein containing polyalanine, the integrin binding site, and two glutamic acids at each terminal site as a possible candidate for use in bone repair materials.  

Science.gov (United States)

The recombinant proteins [EE(A)12EETGRGDSPAAS]n (n = 5,10) were prepared as a potential scaffold material for bone repair. The construct was based on Antheraea perni silk fibroin to which cells adhere well and combined poly(alanine), the integrin binding site TGRGDSPA, and a pair of glutamic acids (E2) at both the N- and C-terminal sites to render the construct water-soluble and with the hope that it might enhance mineralization with hydroxyapatite. Initially, two peptides E2(A)nE2TGRGDSPAE2(A)nE2 (n = 6, 12) were prepared by solid state synthesis to examine the effect of size on conformation and on cell binding. The larger peptide bound osteoblasts more readily and had a higher helix content than the smaller one. Titration of the side chain COO(-) to COOH of the E2 and D units in the peptide was monitored by solution NMR. On the basis of these results, we produced the related recombinant His tagged protein [EE(A)12EETGRGDSPAAS]n (n = 5,10) by expression in Escherichia coli . The solution NMR spectra of the recombinant protein indicated that the poly(alanine) regions are helical, and one E2 unit is helical and the other is a random coil. A molecular dynamics simulation of the protein supports these conclusions from NMR. We showed that the recombinant protein, especially, [EE(A)12EETGRGDSPAAS]10 has some of the properties required for bone tissue engineering scaffold including insolubility, and evidence of enhanced cell binding through focal adhesions, and enhanced osteogenic expression of osteoblast-like cells bound to it, and has potential for use as a bone repair material. PMID:24004453

Asakura, Tetsuo; Suzuki, Yu; Nagano, Aya; Knight, David; Kamiya, Masakatsu; Demura, Makoto

2013-10-14

277

Ptychographic X-ray Tomography of Silk Fiber Hydration  

DEFF Research Database (Denmark)

Studying noninvasively the internal nanoporous structure of a single Tussah silk fiber under different humidity conditions, we demonstrate for the first time the feasibility of in-situ ptychographic tomography. The resulting 3D images of the silk fiber interior, obtained at both dry and humid conditions, yield quantitative information about the spatial density variations in the form of detailed maps of the size, shape, and orientation distributions of the nanopores inside the silk fiber, revealing that the fiber swells anisotropically in humid conditions, with the expansion taking place solely normal to the fiber axis. Exploiting quantitative information on the fiber’s electron density, hydration was found to proceed through interaction with the silk protein rather than filling of pores.

Andreasen, Jens Wenzel

2013-01-01

278

Thermally induced changes in dynamic mechanical properties of native silks.  

Science.gov (United States)

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

Guan, Juan; Porter, David; Vollrath, Fritz

2013-03-11

279

Hierarchical Chain Model of Spider Capture Silk Elasticity  

CERN Document Server

Spider capture silk is a biomaterial with both high strength and high elasticity, but the structural design principle underlying these remarkable properties is still unknown. It was revealed recently by atomic force microscopy that, an exponential force--extension relationship holds both for capture silk mesostructures and for intact capture silk fibers [N. Becker et al., Nature Materials 2, 278 (2003)]. In this Letter a simple hierarchical chain model was proposed to understand and reproduce this striking observation. In the hierarchical chain model, a polymer is composed of many structural motifs which organize into structural modules and supra-modules in a hierarchical manner. Each module in this hierarchy has its own characteristic force. The repetitive patterns in the amino acid sequence of the major flagelliform protein of spider capture silk is in support of this model.

Zhou, H; Zhou, Haijun; Zhang, Yang

2005-01-01

280

Dynamic behaviour of silks: Nature’s precision nanocomposites  

Directory of Open Access Journals (Sweden)

Full Text Available Silk is often cited as a material worth imitating, due to its high strength and toughness. In order to produce a synthetic analogue, or enhanced natural version, the microstructural basis of these properties must be understood. Current understanding is that silk deforms through the detachment of nano-scale crystallites, in the manner of a damaged composite. This picture forms the basis for constitutive models, but validation data is limited to low strain-rates. Here we present a programme of research in which high-rate behaviour is studied through ballistic impact experiments. These have been applied to the silk of the Bombyx mori moth, as harvested from cocoons, and to the major ampullate thread of the golden orb weaver spider Nephila edulis. Longitudinal wave-speeds, and air drag coefficients, have been calculated for selected cases. Differences between the response of various silks and a similar synthetic fibre, nylon, are discussed, and future plans are presented.

Siviour C.R.

2012-08-01

 
 
 
 
281

Thyroid gland biopsy (image)  

Science.gov (United States)

The thyroid is a gland located in the neck. It is a part of the endocrine (hormone) system, and plays a major role in regulating ... sample of cells is needed from the thyroid gland a fine needle biopsy can be performed. During ...

282

The Algorithm to Detect Color Gradation on Silk  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The process of silk dyeing with natural dye extracts will produce a certain color. Using extracts of wood, leaf and their combinations will give some color gradations. This paper aims to create a new algorithm which can help one, whose intention is to formulate the combination of coloring process to achieve the desired color through combining coloring materials on silk fabric. This algorithm will be expected to be able to formulate the combination of colors with more than 75 percent of accura...

Suyoto; Widyastuti; Leonardo Ardhinugroho Dasuki; Raymundus Galih Prasetya

2012-01-01

283

Thermodynamics Study of Lac Dyeing of Silk Yarn Coated with Chitosan  

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Full Text Available A thermodynamic study of lac dyeing of silk pretreated with chitosan at pH 3.0 was investigated in a batch system. It was found that the adsorption of lac dye on silk pretreated with chitosan could be described by the Langmuir isotherm. The results showed that the pretreatment of silk with chitosan provided an enhancement of dye uptake on silk and also decreased the dye desorption from silk yarn compared with the results in the absence of chitosan. The negative value of the enthalpy change (DHº for the adsorption of lac dye on silk pretreated with chitosan indicated that the adsorption process was an exothermic one.

Montra CHAIRAT

2009-01-01

284

Electricity from the silk cocoon membrane.  

Science.gov (United States)

Silk cocoon membrane (SCM) is an insect engineered structure. We studied the electrical properties of mulberry (Bombyx mori) and non-mulberry (Tussar, Antheraea mylitta) SCM. When dry, SCM behaves like an insulator. On absorbing moisture, it generates electrical current, which is modulated by temperature. The current flowing across the SCM is possibly ionic and protonic in nature. We exploited the electrical properties of SCM to develop simple energy harvesting devices, which could operate low power electronic systems. Based on our findings, we propose that the temperature and humidity dependent electrical properties of the SCM could find applications in battery technology, bio-sensor, humidity sensor, steam engines and waste heat management. PMID:24961354

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

2014-01-01

285

Electricity from the Silk Cocoon Membrane  

Science.gov (United States)

Silk cocoon membrane (SCM) is an insect engineered structure. We studied the electrical properties of mulberry (Bombyx mori) and non-mulberry (Tussar, Antheraea mylitta) SCM. When dry, SCM behaves like an insulator. On absorbing moisture, it generates electrical current, which is modulated by temperature. The current flowing across the SCM is possibly ionic and protonic in nature. We exploited the electrical properties of SCM to develop simple energy harvesting devices, which could operate low power electronic systems. Based on our findings, we propose that the temperature and humidity dependent electrical properties of the SCM could find applications in battery technology, bio-sensor, humidity sensor, steam engines and waste heat management. PMID:24961354

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

2014-01-01

286

Recombinant spider silk genetically functionalized with affinity domains.  

Science.gov (United States)

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

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

2014-05-12

287

Multifunctional Silk Nerve Guides for Axon Outgrowth  

Science.gov (United States)

Peripheral nerve regeneration is a critical issue as 2.8% of trauma patients present with this type of injury, estimating a total of 200,000 nerve repair procedures yearly in the United States. While the peripheral nervous system exhibits slow regeneration, at a rate of 0.5 mm -- 9 mm/day following trauma, this regenerative ability is only possible under certain conditions. Clinical repairs have changed slightly in the last 30 years and standard methods of treatment include suturing damaged nerve ends, allografting, and autografting, with the autograft the gold standard of these approaches. Unfortunately, the use of autografts requires a second surgery and there is a shortage of nerves available for grafting. Allografts are a second option however allografts have lower success rates and are accompanied by the need of immunosuppressant drugs. Recently there has been a focus on developing nerve guides as an "off the shelf" approach. Although some natural and synthetic guidance channels have been approved by the FDA, these nerve guides are unfunctionalized and repair only short gaps, less than 3 cm in length. The goal of this project was to identify strategies for functionalizing peripheral nerve conduits for the outgrowth of neuron axons in vitro . To accomplish this, two strategies (bioelectrical and biophysical) were indentified for increasing axon outgrowth and promoting axon guidance. Bioelectrical strategies exploited electrical stimulation for increasing neurite outgrowth. Biophysical strategies tested a range of surface topographies for axon guidance. Novel methods were developed for integrating electrical and biophysical strategies into silk films in 2D. Finally, a functionalized nerve conduit system was developed that integrated all strategies for the purpose of attaching, elongating, and guiding nervous tissue in vitro. Future directions of this work include silk conduit translation into a rat sciatic nerve model in vivo for the purpose of repairing long (> 3 cm) peripheral nerve gaps.

Tupaj, Marie C.

288

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

International Nuclear Information System (INIS)

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

289

Male accessory gland infection.  

Science.gov (United States)

Male accessory gland infection (MAGI) is a consequence of canalicular spreading of agents via urethra, prostate gland, seminal vesicles, deferent duct, epididymis and testis. Haematogenous infections are rare. The main infectious agents are Neisseria gonorrhoeae and Chlamydia trachomatis, and also enterobacteriae at a lesser frequency. Characteristic symptoms of MAGI are leukocytospermia, enhanced concentration of cytokines and reactive oxygen species. As complications, obstruction of the ductus epididymidis and/or another duct section, impairment of spermatogenesis in orchitis, impairment of sperm function, and dysfunctions of the male accessory glands may occur. Reduction of male fertility is a rare consequence. The treatment has to consider specific antibiotics. PMID:18336461

Krause, W

2008-04-01

290

Biosynthesis and characterization of typical fibroin crystalline polypeptides of silkworm Bombyx mori  

International Nuclear Information System (INIS)

We aimed to investigate the self-organization/self-assembly mechanisms of silkworm fibroin-based material. In the present study, for the first time, we designed and multimerized four DNA 'monomer' sequences from structurally simple fibroin crystalline peptides or analog, [GAGAGX] (X = A, S, Y and V) to encode polypeptides [GAGAGX]16 (eGA, eGS, eGY and eGV) using a 'head-to-tail' construction strategy. Multimers were cloned into pGEX-KG and fusion proteins GST-[GAGAGX]16 (KGA, KGS, KGY and KGV) were efficiently expressed in Escherichia coli. These fusion proteins were isolated and purified by GST affinity chromatography and confirmed by SDS-PAGE and Western blot analysis using antibody reactive to GST. The polypeptides were cleavaged from GST fusion proteins by digesting with thrombin enzyme. The composition of the four polypeptides was confirmed by composition analysis of amino acids, and their abilities to form ?-sheet structure were determined by ThT fluorescence spectral analysis. The content of ?-sheet among the four polypeptides followed the order: eGS > eGV > eGY > eGA.

291

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

International Nuclear Information System (INIS)

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

292

Protein and amino acid composition of silks from the cob weaver, Latrodectus hesperus (black widow).  

Science.gov (United States)

The silks from the cob weaving spider, Latrodectus hesperus (black widow), have been examined with the goal of expanding our understanding of the relationship between the protein structure and mechanical performance of these unique biomaterials. The scaffolding, dragline and inner egg case silks each appear to be distinct fibers based on mole percent amino acid composition and polypeptide composition. Further, we find that the amino acid composition of dragline and egg case silk are similar to the analogous silks produced by orb weaving spiders, while scaffolding silk may represent a novel silk. The black widow silks are comprised of multiple high molecular weight polypeptides, however, the egg case and scaffolding silks also contain some smaller polypeptides. PMID:10342753

Casem, M L; Turner, D; Houchin, K

1999-01-01

293

Reversible assembly of ?-sheet nanocrystals within caddisfly silk.  

Science.gov (United States)

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 dimensions of 5.9 Å × 23.2 Å × 17.3 Å. These nanocrystalline domains depend on multivalent cations, which can be removed through chelation with ethylenediaminetetraacetic acid (EDTA). A comparison of wide angle X-ray diffraction data before and after EDTA treatment reveals that the integrated peak area of reflections corresponding to the nanocrystalline regions decreases by 15-25% while that of the amorphous background reflections increases by 20%, indicating a partial loss of crystallinity. (31)P solid-state NMR data on native caddisfly silk also show that the phosphorylated serine-rich motifs transform from a rigid environment to one that is highly mobile and water-solvated after treatment with EDTA. The removal of divalent cations through exchange and chelation has therefore caused a collapse of the ?-sheet structure. However, NMR results show that the rigid phosphorus environment is mostly recovered after the silk is re-treated with calcium. The (31)P spin-lattice (T1) relaxation times were measured at 7.6 ± 3.1 and 1 ± 0.5 s for this calcium-recovered sample and the native silk sample, respectively. The shorter (31)P T1 relaxation times measured for the native silk sample are attributed to the presence of paramagnetic iron that is stripped away during EDTA chelation treatment and replaced with diamagnetic calcium. PMID:24576204

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

2014-04-14

294

Pituitary Gland Disorders Overview  

Science.gov (United States)

... Resource Find an Endocrinologist Search Featured Resource Educational Infographics View Overview The pituitary gland is a tiny ... Healthy Living Living Your Best Life with Diabetes Infographics Myth vs Fact Patient Alerts Scientific Statements Social ...

295

Bengali raw silk, the East India Company and the European global market, 1770-1833  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In 1769, the East India Company decided to transform the Bengali silk industry, and introduced Piedmontese reeling technologies and spatially concentrated working practices into the area. Although Bengali raw silk reeled with the new methods never reached the standards of Piedmontese silks, the Company was able to produce huge quantities of low-quality raw silks, and to gain market share in London from the 1770s to the 1830s. By investigating the reasons behind this partial success, this arti...

Davini, Roberto

2009-01-01

296

Pediatric salivary gland imaging  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-15

297

Radionuclide salivary gland imaging  

Energy Technology Data Exchange (ETDEWEB)

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

Mishkin, F.S.

1981-10-01

298

Radionuclide salivary gland imaging  

International Nuclear Information System (INIS)

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

299

Effects of Japanese beetle (Coleoptera: Scarabaeidae) and silk clipping in field corn.  

Science.gov (United States)

Japanese beetle (Popillia japonica Newman) is an emerging silk-feeding insect found in fields in the lower Corn Belt and Midsouthern United States. Studies were conducted in 2010 and 2011 to evaluate how silk clipping in corn affects pollination and yield parameters. Manually clipping silks once daily had modest effects on yield parameters. Sustained clipping by either manually clipping silks three times per day or by caging Japanese beetles onto ears affected total kernel weight if it occurred during early silking (R1 growth stage). Manually clipping silks three times per day for the first 5 d of silking affected the number of kernels per ear, total kernel weight, and the weight of individual kernels. Caged beetles fed on silks and, depending on the number of beetles caged per ear, reduced the number of kernels per ear. Caging eight beetles per ear significantly reduced total kernel weight compared with noninfested ears. Drought stress before anthesis appeared to magnify the impact of silk clipping by Japanese beetles. There was evidence of some compensation for reduced pollination by increasing the size of pollinated kernels within the ear. Our results showed that it requires sustained silk clipping during the first week of silking to have substantial impacts on pollination and yield parameters, at least under good growing conditions. Some states recommend treating for Japanese beetle when three Japanese beetles per ear are found, silks are clipped to < 13 mm, and pollination is < 50% complete, and that recommendation appears to be adequate. PMID:24224246

Steckel, Sandy; Stewart, S D; Tindall, K V

2013-10-01

300

SilkDB: a knowledgebase for silkworm biology and genomics.  

DEFF Research Database (Denmark)

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

Wang, Jing; Xia, Qingyou

2005-01-01

 
 
 
 
301

SilkDB: a knowledgebase for silkworm biology and genomics.  

Science.gov (United States)

The Silkworm Knowledgebase (SilkDB) is a web-based repository for the curation, integration and study of silkworm genetic and genomic data. With the recent accomplishment of a approximately 6X draft genome sequence of the domestic silkworm (Bombyx mori), SilkDB provides an integrated representation of the large-scale, genome-wide sequence assembly, cDNAs, clusters of expressed sequence tags (ESTs), transposable elements (TEs), mutants, single nucleotide polymorphisms (SNPs) and functional annotations of genes with assignments to InterPro domains and Gene Ontology (GO) terms. SilkDB also hosts a set of ESTs from Bombyx mandarina, a wild progenitor of B.mori, and a collection of genes from other Lepidoptera. Comparative analysis results between the domestic and wild silkworm, between B.mori and other Lepidoptera, and between B.mori and the two sequenced insects, fruitfly and mosquito, are displayed by using B.mori genome sequence as a reference framework. Designed as a basic platform, SilkDB strives to provide a comprehensive knowledgebase about the silkworm and present the silkworm genome and related information in systematic and graphical ways for the convenience of in-depth comparative studies. SilkDB is publicly accessible at http://silkworm.genomics.org.cn. PMID:15608225

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

2005-01-01

302

The Algorithm to Detect Color Gradation on Silk  

Directory of Open Access Journals (Sweden)

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

Suyoto

2012-03-01

303

[Study on the chemical constituents of flavones from corn silk].  

Science.gov (United States)

The three flavones were isolated from water extracts of corn silk by chromatography on macroporous resin, polyamide, ODS and Sephadex LH-20. Three compounds were identified as formononetin (7-hydroxy-4'-methoxyisoflavone) ( I ) ,2"-O-alpha-L-rham-nosyl-6-C-( 3-deoxyglucosyl) -3 '-methoxyluteolin( II ) ,2"-O-alpha-L-rhamnosyl-6-C-( 6-deoxy-ax-5-methyl-xylo-hexos-4-ulosyl) -3'-methoxyluteolin( II ). Compounds ( I ) and ( II ) were isolated from the corn silk for the first time. PMID:17571762

Zhang, Hui-en; Xu, De-ping

2007-02-01

304

Corn silk induced cyclooxygenase-2 in murine macrophages.  

Science.gov (United States)

Stimulation of murine macrophages with corn silk induced cyclooxygenase (COX)-2 with secretion of PGE2. Expression of COX-2 was inhibited by pyrolidine dithiocarbamate (PDTC), and increased DNA binding by nuclear factor kappa B (NF-kappaB), indicating that COX-2 induction proceeds also via the NF-kappaB signaling pathway. A specific inhibitor of COX-2 decreased the expression level of inducible nitric oxide synthase (iNOS) stimulated by corn silk. PGE2 elevated the expression level of iNOS, probably via EP2 and EP4 receptors on the surface of the macrophages. PMID:16244433

Kim, Kyung A; Shin, Hyun-Hee; Choi, Sang Kyu; Choi, Hye-Seon

2005-10-01

305

Structure and Properties of Nephila Clavipes Dragline Silk Polymer  

Science.gov (United States)

Silk, spun from an aqueous state at room temperature by a variety of organisms, is the most commonly spun extracellular fibrous protein. It comprises polypeptide chains with regions which can crystallize and regions which are predominantly amorphous. The polymer chains in the crystalline regions form anti-parallel pleated sheet structures with an orthorhombic unit cell. Dragline silk is a structural material produced by a variety of spiders. It has been genetically tailored to meet a specific purpose. Dragline silk exhibits high extensibility and tensile strength approaching that of high-strength synthetic fibers. The specific energy to break it can exceed some steels and synthetic fibers. Samples of Nephila clavipes (golden orb-weaver) dragline silk were extracted from live specimens and examined with a series of experimental techniques including optical, scanning electron, and atomic force microscopy, wide and small angle X-ray diffraction and birefringence compensation. Computer modeling of the mechanical properties of the crystallite was also performed. An assortment of features at a variety of length scales was observed by microscopy. These occur on both the as-spun and abraded silk surfaces. The silk was observed to undergo large deformations without evidence of failure, suggesting the absence of a microfibrillar structure. There was no conclusive evidence for either a microfibrillar or a skin core structure. Meridional and equatorial SAXD peaks were observed at Bragg spacings of 79 AA and 250 AA, respectively. Analysis of the WAXD patterns indicated that the silk belongs in Warwicker's category 3b and that the minimum dimensions of the crystals are approximately 38 AA in the molecular direction and 16 x 23 AA in the transverse directions. The crystal modulus was determined with WAXD to be 16.7 GPa, applying the assumption of uniform stress. This is lower than the 200 GPa modulus calculated with molecular modeling. These results and other factors indicate the inapplicability of the widely used assumption of uniform stress. The X-ray data show increased alignment of the crystals along the fiber axis with stress. The birefringence of the silk fibers increases monotonically to failure which indicates increasing molecular alignment. The change in birefringence appears to be governed by the amorphous contribution.

Mahoney, David Vincent

306

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

International Nuclear Information System (INIS)

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

307

An experimental confirmation of thermal transitions in native and regenerated spider silks.  

Science.gov (United States)

Biological structures such as spider silks are formed by proteins. The physical properties of such proteins are determined by environmental conditions such as temperature and humidity. In this paper, we confirm the thermal transitions that take place in spider silks using differential scanning calorimetry and study how the interaction of spider silk proteins with water affects the onset temperatures for these thermal processes. Native fibres and regenerated films of dragline silk and egg sac silk from Argiope argentata spiders were used to study thermal transitions of protein based structures. For the first time, differential scanning calorimetry (DSC) tests were carried out with spider silk samples of relatively large mass (10mg). Previous attempts of DSC tests applied to spider silk samples failed to detect thermal transitions in a conclusive way. The tests reported here, however, show thermal transitions on both natural and regenerated samples that are in agreement with results from dynamic mechanical analysis (DMA) tests reported in the literature. The water content on spider silks seems to lower the temperatures at which such thermal transitions take place. The results also confirm that the amorphous regions of native and regenerated spider silk and silk worm silk give rise to similar thermal transitions. PMID:23827592

Torres, Fernando G; Troncoso, Omar P; Torres, Carlos; Cabrejos, Wilson

2013-04-01

308

Engineering aqueous fiber assembly into silk-elastin-like protein polymers.  

Science.gov (United States)

Self-assembled peptide/protein nanofibers are valuable 1D building blocks for creating complex structures with designed properties and functions. It is reported that the self-assembly of silk-elastin-like protein polymers into nanofibers or globular aggregates in aqueous solutions can be modulated by tuning the temperature of the protein solutions, the size of the silk blocks, and the charge of the elastin blocks. A core-sheath model is proposed for nanofiber formation, with the silk blocks in the cores and the hydrated elastin blocks in the sheaths. The folding of the silk blocks into stable cores--affected by the size of the silk blocks and the charge of the elastin blocks--plays a critical role in the assembly of silk-elastin nanofibers. Furthermore, enhanced hydrophobic interactions between the elastin blocks at elevated temperatures greatly influence the nanoscale features of silk-elastin nanofibers. PMID:24798978

Zeng, Like; Jiang, Linan; Teng, Weibing; Cappello, Joseph; Zohar, Yitshak; Wu, Xiaoyi

2014-07-01

309

Salivary gland disorders.  

Science.gov (United States)

Salivary gland disorders include inflammatory, bacterial, viral, and neoplastic etiologies. The presentation can be acute, recurrent, or chronic. Acute suppurative sialadenitis presents as rapid-onset pain and swelling and is treated with antibiotics, salivary massage, hydration, and sialagogues such as lemon drops or vitamin C lozenges. Viral etiologies include mumps and human immunodeficiency virus, and treatment is directed at the underlying disease. Recurrent or chronic sialadenitis is more likely to be inflammatory than infectious; examples include recurrent parotitis of childhood and sialolithiasis. Inflammation is commonly caused by an obstruction such as a stone or duct stricture. Management is directed at relieving the obstruction. Benign and malignant tumors can occur in the salivary glands and usually present as a painless solitary neck mass. Diagnosis is made by imaging (e.g., ultrasonography, computed tomography, magnetic resonance imaging) and biopsy (initially with fine-needle aspiration). Overall, most salivary gland tumors are benign and can be treated with surgical excision. PMID:25077394

Wilson, Kevin F; Meier, Jeremy D; Ward, P Daniel

2014-06-01

310

Undifferentiated salivary gland carcinomas  

DEFF Research Database (Denmark)

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

Herbst, H.; Hamilton-Dutoit, S.

2004-01-01

311

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

312

Pictorial essay: Salivary gland imaging.  

Science.gov (United States)

Salivary glands are the first organs of digestion secreting their digestive juices into the oral cavity. Parotid, submandibular, and sublingual glands are the major paired salivary glands in the decreasing order of their size. In addition, multiple small minor salivary glands are noted randomly distributed in the upper aerodigestive tract, including paranasal sinuses and parapharyngeal spaces. The imaging is directed to the major salivary glands. Commonly used imaging methods include plain radiography and conventional sialography. Recently, high-resolution ultrasonography (HRUS) is being increasingly used for targeted salivary gland imaging. However, the advent of cross-sectional imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) have revolutionized the imaging of salivary glands. This article illustrates the role of imaging in evaluating the variegated disease pattern of the major salivary glands. PMID:23833425

Rastogi, Rajul; Bhargava, Sumeet; Mallarajapatna, Govindarajan Janardan; Singh, Sudhir Kumar

2012-10-01

313

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

314

Directly obtaining pristine magnetic silk fibers from silkworm.  

Science.gov (United States)

By feeding the silkworms with the nano Fe3O4 powder together with mulberry leaves, we directly obtained silkworm spun pristine magnetic silk fiber, MSF. To compare with the normal SF found that this MSF not only has expected magnetic properties, but also has enhanced thermal stability and mechanical properties, e.g. stress and strain. PMID:24269584

Wang, Jun-Ting; Li, Lu-Lu; Feng, Lei; Li, Jin-Fan; Jiang, Lin-Hai; Shen, Qing

2014-02-01

315

Silk cocoon drying in forced convection type solar dryer  

International Nuclear Information System (INIS)

The thin layer silk cocoon drying was studied in a forced convection type solar dryer. The drying chamber was provided with several trays on which the cocoons loaded in thin layer. The hot air generated in the solar air heater was forced into drying chamber to avoid the direct exposure of sunlight and UV radiation on cocoons. The drying air temperature varied from 50 to 75 oC. The cocoon was dried from the initial moisture content of about 60-12% (wb). The drying data was fitted to thin layer drying models. Drying behaviour of the silk cocoon was best fitted with the Wang and Singh drying model. Good agreement was obtained between predicted and experimental values. Quality of the cocoons dried in the solar dryer was at par with the cocoons dried in the conventional electrical oven dryer in term of the silk yield and strength of the silk. Saving of electrical energy was about 0.75 kWh/kg cocoons dried. Economic analysis indicated that the NPV of the solar dryer was higher and more stable (against escalation rate of electricity) as compare to the same for electrical oven dryer. Due to simplicity in design and construction and significant saving of operational electrical energy, solar cocoon dryer seems to be a viable option.

316

Influence of Hybridization on the Traits of Silk Production and Filament Denier in Indian Tropical Tasar Silk Insect, Antheraea mylitta Drury  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of the present study is to explore hybridization influence to achieve the potential of silk yield and quality in commercial tasarculture, as against the current status of applying only a few wild and semi-domesticated ecoraces of Antheraea mylitta D to produce raw silk during commercial crop rearing season (September-December. The four F1 hybrid combinations generated using Daba, Jata and Raily tasar ecoraces of seed crop rearing season (July-August were evaluated during commercial crop season of 2007 and 2008 for the influence of hybridization as positive heterosis in the traits of economically important silk productivity and filament denier. The F1 hybrid, Daba x Jata has recorded positive heterosis in single shell weight (+25.6%, total silk yield (+79.0% and silk filament length (+68.1%, but for silk filament of high denier (11.98 d followed by its reciprocal hybrid, JataxDaba in shell weight (+18.8%, silk yield (+68.1%, filament length (+63.8% and filament of highest denier (12.32 d. Though, the RailyxDaba hybrid could show highest heterosis in shell weight (2.47 g with filament of least denier (10.86 d, the improvement in filament length was marginal (+44.7% and heterosis in silk yield was negative (-47.0%, while the performance of DabaxRaily hybrid was least among the hybrids. The study infers hybridization influence on silk related traits at F1 level as positive heterosis and the application feasibility of DabaxJata and JataxDaba hybrids during commercial crop rearing season for higher silk productivity with silk filament denier at least better than one of the parents of F1 hybrid combination.

A.K. Srivastava

2010-01-01

317

Functionalized spider silk spheres as drug carriers for targeted cancer therapy.  

Science.gov (United States)

Bioengineered spider silk is a biomaterial that combines the properties of self-assembly, biocompatibility and biodegradability with reasonable accessibility and a simple purification procedure. Moreover, genetic engineering enables the functionalization of silk by adding the peptide coding sequences of the desired attribute. Hybrids composed of Her2 binding peptides (H2.1 or H2.2) and bioengineered silk MS1 (based on the MaSp1 sequence from N. clavipes) were designed. Bioengineered silks were expressed in a bacterial system and purified using a tag-free thermal method. The hybrid silks with N-terminal functionalization were bound more efficiently to cells that were overexpressing Her2 than those with the C-terminal fusion. Moreover, the functionalization did not impede the self-assembly property of bioengineered silk, enabling the processing of silk proteins into spheres. The binding domains were exposed on the surface of the spheres, because the functionalized particles specifically bound and internalized into Her2-overexpressing cells. The binding of the functionalized spheres to Her2-positive cells was significantly higher compared with the control sphere and Her2-negative cell binding. Silk spheres were loaded with doxorubicin and showed pH-dependent drug release. The silk spheres were not cytotoxic, unless they were loaded with the drug doxorubicin. This study indicates the ability of drug-loaded functionalized spider silk spheres to serve as a carrier for targeted cancer therapy. PMID:24963985

Florczak, Anna; Mackiewicz, Andrzej; Dams-Kozlowska, Hanna

2014-08-11

318

UTILIZATION OF ALOE VERA (L HERBAL TONIC FOR TREATING MULBERRY LEAVES BEFORE FEEDING THE FIFTH INSTAR LARVAE OF SILK WORM, BOMBYX MORI L. (RACE: PM X CSR2.  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of the dietary supplementation of Aloe vera (L herbal formulation  (containing principally the extract Aloe vera on the larval growth and the cocoon (economic parameteres of the mulberry silkworm Bombyx mori L. commercial cross breed race: PM x CSR2 during its fifth instars was experimented. Treating the mulberry leaves with the aqueous solution of Aloe herbal formulation and feeding the fifth instar larvae, in general, elicited better response of the growth and the cocoon characteristics of this silkworm. Specifically, the Aloe vera L. at 2.0 % concentration resulted higher larval growth and increased the weight of cocoon. The mean larval weight, relative growth rate, effective rearing rate, larval consumption index of the final instar larvae of silk worm, Bombyx mori L. increased with the supplementation of Aloe vera tonic. The average pupal weight and mother moth weight also increased as a result of this supplementation. Maximum shell weight and shell ratio were noted in the group of larvae fed with Aloe treated mulberry leaves. The fibroin content of the cocoon shell produced by this silkworm in response to the dietary supplementation of Aloe vera tonic treatment also showed significant increase over control. The overall performance of Bombyx mori in response to the Aloe vera herbal treatment observed in the present study and the evaluation index values worked out showed that the growth and the cocoon parameters could be improved with the supplementation of A. vera herbal formulation. Aloe tonic may serve to orchestrate the progression of larval growth through the fortification of digestion capabilities in the fifth instar larvae of silkworm, Bombyx  mori (L (Race : PM x CSR2.   

Rajkumar Bapurao Deshmukh, Vitthalrao B Khyade

2013-01-01

319

Spider genomes provide insight into composition and evolution of venom and silk  

DEFF Research Database (Denmark)

Spiders are ecologically important predators with complex venom and extraordinarily tough silk that enables capture of large prey. Here we present the assembled genome of the social velvet spider and a draft assembly of the tarantula genome that represent two major taxonomic groups of spiders. The spider genomes are large with short exons and long introns, reminiscent of mammalian genomes. Phylogenetic analyses place spiders and ticks as sister groups supporting polyphyly of the Acari. Complex sets of venom and silk genes/proteins are identified. We find that venom genes evolved by sequential duplication, and that the toxic effect of venom is most likely activated by proteases present in the venom. The set of silk genes reveals a highly dynamic gene evolution, new types of silk genes and proteins, and a novel use of aciniform silk. These insights create new opportunities for pharmacological applications of venom and biomaterial applications of silk.

Sanggaard, Kristian W; Bechsgaard, Jesper S

2014-01-01

320

Orientational order of Australian spider silks as determined by solid-state NMR.  

Science.gov (United States)

A simple solid-state NMR method was used to study the structure of (13)C- and (15)N-enriched silk from two Australian orb-web spider species, Nephila edulis and Argiope keyserlingi. Carbon-13 and (15)N spectra from alanine- or glycine-labeled oriented dragline silks were acquired with the fiber axis aligned parallel or perpendicular to the magnetic field. The fraction of oriented component was determined from each amino acid, alanine and glycine, using each nucleus independently, and attributed to the ordered crystalline domains in the silk. The relative fraction of ordered alanine was found to be higher than the fraction of ordered glycine, akin to the observation of alanine-rich domains in silk-worm (Bombyx mori) silk. A higher degree of crystallinity was observed in the dragline silk of N. edulis compared with A. keyserlingi, which correlates with the superior mechanical properties of the former. PMID:16463360

Bonev, B; Grieve, S; Herberstein, M E; Kishore, A I; Watts, A; Separovic, F

2006-06-01

 
 
 
 
321

Fabrication of CeO2 nanoparticle-modified silk for UV protection and antibacterial applications.  

Science.gov (United States)

To endow silk with UV-shielding ability and antibacterial activity, CeO2 nanoparticles were immobilized on silk surface via a dip-coating approach without changing silk structure. Surface density of the nanoparticles could be easily adjusted by controlling the number of dip-coating cycle. Enhanced thermal stability of the modified silk is exhibited in thermogravimetric analysis (TGA) and derivative thermogravimetric analysis (DTG). The excellent UV-protection ability and antibacterial property of the CeO2 nanoparticle-coated silk are demonstrated in UV-vis diffuse reflectance spectroscopy and colony-forming capability test, respectively. Based on the data, it can be concluded that CeO2 nanoparticles could be used as a very promising coating material to modify silk for UV-protection and antibacterial applications. PMID:25203972

Lu, Zhisong; Mao, Cuiping; Meng, Mei; Liu, Sangui; Tian, Yunli; Yu, Ling; Sun, Bai; Li, Chang Ming

2014-12-01

322

Protective effect of silk lutein on ultraviolet B-irradiated human keratinocytes  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Carotenoids are efficient antioxidants that are of great importance for human health. Lutein and zeaxanthin are carotinoids present in high concentrations in the human retina which are involved in the photoprotection of the human eye. Lutein may also protect the skin from ultraviolet (UV)-induced da [...] mage. The present study investigated the protective effect of lutein extracted from yellow silk cocoons of Bombyx mori on human keratinocytes against UVB irradiation. A human keratinocyte cell line and primary human keratinocytes were used to investigate the UVB protection effects of silk lutein and plant lutein. Silk lutein showed no cytotoxicity to keratinocytes. Treatment with silk lutein prior to UVB irradiation enhanced cell viability and cell proliferation, and reduced cell apoptosis. The protective effects of silk lutein may be superior to those of plant lutein. Silk lutein may have a benefit for protection of keratinocytes against UVB-irradiation.

Sutatip, Pongcharoen; Prateep, Warnnissorn; Ongart, Lertkajornsin; Nanteetip, Limpeanchob; Manote, Sutheerawattananonda.

323

Elasticity of Spider dragline Silks Viewed as Nematics: Yielding Induced by Isotropic-Nematic Phase Transition  

CERN Document Server

Spider dragline silk is an intriguing biomaterial of practical use, and it has long been suggested to be a liquid crystalline material. We model the dragline silk as nematics by using continuum liquid crystal theory. The overall stress-strain curve and the yield point can be evaluated quantitatively and agree with experiment data well. Additionally, our model can account for the drop of stress in wet spider dragline, i.e. in supercontracted dragline silk.

Cui, Lin-ying; Liu, Fei

2008-01-01

324

Changes in growth and cell wall extensibility of maize silks following pollination  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In response to pollination maize silks undergo an accelerated process of senescence which involves an inhibition of elongation. To gain insight into the mechanism underlying this growth response, the relationships among silk elongation kinetics, cell wall biophysical properties, pollen tube growth, and expansin protein abundance were investigated. The inhibition of silk elongation became apparent beyond 12?h after pollination. Pollinated walls were less responsive in assays of extension ind...

Sella Kapu, Nuwan U.; Cosgrove, Daniel J.

2010-01-01

325

Hypotheses that correlate the sequence, structure, and mechanical properties of spider silk proteins.  

Science.gov (United States)

Several types of silks and silk protein coding genes have been characterized from orb-web weaving spiders. When the protein sequences of major ampullate, minor ampullate, and flagelliform silks from Nephila clavipes are compared, they can be summarized as sets of shared amino acid motifs. Four of these motifs and their likely secondary structures are described. Each structural element, termed a module, is then associated with its impact on the mechanical properties of a silk fiber. In particular, correlations are drawn between an alanine-rich 'crystalline module' and tensile strength and between a proline-containing 'elasticity module' and extensibility. PMID:10342774

Hayashi, C Y; Shipley, N H; Lewis, R V

1999-01-01

326

Immune enhancement activities of silk lutein extract from Bombyx mori cocoons  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english BACKGROUND: Declining immune function poses an important clinical challenge worldwide and supplementation with natural products that possessing immune enhancing properties is a promising approach for preventing or delaying immune function decline. Cocoons from yellow silkworms are a significant sour [...] ce of lutein, and this unexplored silk extract could be a viable alternative source for dietary lutein. This study assessed immunomodulatory activities of the silk lutein extract. Female BALB/c mice orally received lutein, either as silk or marigold extracts (10 or 20 mg/kg daily), or vehicle only (1% tween 80 in PBS pH 7.4) for 4 weeks. Natural killer (NK) cell activity, specific antibody production, lymphocyte subpopulations, mitogen-induced lymphocyte proliferation, and cytokine production were examined. RESULTS: Silk lutein extract increased NK cell activity, and the effect was dose-related whereas marigold lutein extract was ineffective. Silk lutein extract dose-dependently enhanced antibody production in pre-immunized mice but marigold lutein extract had no effect. Feeding with silk lutein extract increased the populations of CD3+ and CD4?+?CD3?+?cells. Silk lutein extract also stimulated concanavalin A- and lipopolysaccharide-induced proliferations of T and B lymphocytes, respectively. Moreover, silk lutein extract increased IL-2 and IFN-? production while the effect of marigold lutein extract was undetectable. CONCLUSIONS: Together, silk lutein extract enhanced both innate and adaptive immune functions. This preparation may prove to be an effective supplement for strengthened immunity.

Porkaew, Promphet; Sirirat, Bunarsa; Manote, Sutheerawattananonda; Duangkamol, Kunthalert.

327

Dissolution of Philosamia ricini Silk Film: Properties and Functions in Different Solutions  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, dissolution of Eri (Philosamia ricini cocoons in different solutions was investigated and compared with Nang-Lai variety (Bombyx mori cocoons. The Lithium Bromide (LiBr, calcium nitrate (Ca(NO32, Zinc chloride (ZnCl2, Lithium thiocyanate (LiSCN·xH2O, 85% phosphate and mixture (calcium chloride (CaCl2/Ethanol/H2O; 1:2:8 solution systems were used. Efficiency of the dissolving solution was examined by measuring the percentage of dissolved silk. It was found that the Nang-Lai silk was completely dissolved in all solutions, whereas, Eri silk was slightly dissolved, except for 85% phosphate solution. The Fourier transform infrared spectroscopy (FTIR spectra of the Eri silk film composed of β-sheet form than Nang Lai silk film. With thermogravimetric analysis, the Eri silk film showed two stages of thermal decompositions while the Nang-Lai silk was a single stage. In conclusion, thermal stability of the Eri silk was higher than the Nang-Lai silk.

Y. Srisuwan

2009-01-01

328

Preparation of hexagonal GeO2 particles with particle size and crystallinity controlled by peptides, silk and silk-peptide chimeras.  

Science.gov (United States)

We demonstrate the use of silk based proteins to control the particle/crystallite size during GeO2 formation, using a bio-mimetic approach at circumneutral pH and ambient temperature. Multicrystalline GeO2 was prepared from germanium tetraethoxide (TEOG) in the presence of different silk-based proteins: Bombyx mori silk (native silk) and two chimeric proteins prepared by linking a germania binding peptide (Ge28: HATGTHGLSLSH) with Bombyx mori silk via chemical coupling at different peptide loadings (silk-Ge28 10% and silk-Ge28 50%). The mineralisation activity of the silk-based proteins was compared with that of peptide Ge28 as a control system. GeO2 mineralisation was investigated in water and in citric acid/bis-tris propane buffer at pH 6. Morphology, particle size, crystallinity, water and organic content of the materials obtained were analysed to study the effect of added biomolecules and mineralisation environment on material properties. In the presence of silk additives well-defined cube-shape hybrid materials composed of hexagonal germania and up to ca. 5 wt% organic content were obtained. The cubic particles ranged from 0.4 to 1.4 ?m in size and were composed of crystalline domains in the range 35-106 nm depending on the additive used and synthesis conditions. The organic material incorporated in the mineral did not appear to affect the unit cell dimensions. The silk and chimeric proteins in water promote material formation and crystal growth, possibly via an effective ion-channelling mechanism, however further studies are needed to assert to what extent the presence of the silk impacts on nucleation and growth stages. The germania binding peptide alone did not have any significant effect on reaction rate, yield or the material's properties compared to the blank. Interestingly, the peptide content in the silk chimeras tested did not affect mineralisation. The presence of buffer inhibited mineral condensation rate and yield. The use of silk-based biomolecules allows control of crystallite/particle size of hybrid materials opening up opportunities for bio-inspired approaches to be applied for the synthesis of functional germania based devices and materials. PMID:25300352

Boix, Estefania; Puddu, Valeria; Perry, Carole C

2014-10-22

329

Ordering recombinant silk-elastin-like nanofibers on the microscale  

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Self-assembled peptide/polypeptide nanofibers are appealing building blocks for creating complex three-dimensional structures. However, ordering assembled peptide/polypeptide nanofibers into three-dimensional structures on the microscale remains challenging and often requires the employment of top-down approaches. We report that silk-elastin-like protein polymers self-assemble into nanofibers in physiologically relevant conditions, the assembled nanofibers further form fiber clusters on the microscale, and the nanofiber clusters eventually coalesce into three-dimensional structures with distinct nanoscale and microscale features. It is believed that the interplay between fiber growth and molecular diffusion leads to the ordering of the assembled silk-elastin-like nanofibers at the microscale.

Zeng, Like; Teng, Weibing; Jiang, Linan; Cappello, Joseph; Wu, Xiaoyi

2014-01-01

330

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

331

Overcoming dormancy in seeds of cotton-silk tree  

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Cotton-silk tree Ceiba glaziovii (kuntze) k. Schu belongs to family Bombacaceas and is locally known as barriguda. It is widely used in landscaping and reforestation, neverdeless seed dormancy affects reproduction in this species. The objective of this study was to evaluate the effectiveness of different methods to overcome dormancy in the germination process. Treatments included mechanical scarification with 85-grit sandpaper, chemical scarification with concentrated sulfuric acid for 5, 10,...

Irinaldo Lima do Nascimento

2012-01-01

332

Spray drying as a method of producing silk sericin powders  

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Purpose: The purpose of paper is to analyse Spray drying as a method of producing silk sericin powders.Design/methodology/approach: Aqueous sericin solutions were used as raw material for the production of dry powders using a lab-scale spray dryer. A linear regression analysis of agglomeration was employed, in addition to experimental designs at two levels with three factors for the analysis of three responses: moisture content, particle type and agglomeration degree. The process factors were...

Genc?, G.; Narin, G.; Bayraktar, O.

2009-01-01

333

CT of the adrenal gland  

International Nuclear Information System (INIS)

In the past 11 years it has become clear that CT is the best single imaging method with which to diagnose or exclude a mass lesion of any type within the adrenal gland. In most radiology practices, CT is currently the primary method of examination in patients suspected of having adrenal gland pathology, based on symptoms, chemical studies, or suspicious findings on other imaging procedures. The presentation reviews normal anatomy of the adrenal glands and examines the various pathologic processes that are expected to occur in the adrenal glands. Study of CT results in the adrenal gland has been practically rewarding because it has given radiologists the opportunity to compare CT findings with the pathologic specimens which are removed in to and which can be compared with the image seen on the CT scan. Such an opportunity for CT-gross pathology correlation has not been possible in the assessment of other organs (such as pancreas) or other diseases (such as lymphoma). Problems associated with accurate interpretation of CT scans of the adrenal gland are discussed. Technical aspects of performance of adequate adrenal gland examinations are reviewed. Common and uncommon examples of adrenal gland pathology are reviewed, and certain aspects of adrenal gland biopsy and the management of patients with asymptomatic adrenal tumors are discussed. Finally, CT results are correlated with results of other imaging techniques, such as radionuclide scanning and MR imaginglide scanning and MR imaging

334

Uncovering spider silk nanocrystalline variations that facilitate wind-induced mechanical property changes.  

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Spider major ampullate (MA) silk varies in mechanical properties when spun in different environments. Amino acid compositional changes induced by variations in MaSp1 and MaSp2 expression, and various biochemical and physiological glandular processes induce silk property variability. Quantifying the contributions of these mechanisms on silk variability may facilitate the development of silk biomimetics. Wind is a medium that induces variations in MA silk mechanics. We exposed the spider Cyclosa mulmeinensis to wind and measured the amino acid composition, tensile mechanics, and crystalline structure of its MA silk using HPLC, tensile tests, and X-ray diffraction. We found the mechanical properties of MA silks from spiders exposed to wind to differ from unexposed spiders. The amino acid compositions did not differ, but X-ray diffraction found a lower crystal density and greater ?-sheet alignment relative to the fiber axis in the silks of spiders exposed to wind. We found no evidence that the mechanical property variations were a product of profound changes to the alignment of the protein within the amorphous region. We conclude that variations in the density and alignment of the crystalline ?-sheets, probably accompanied by some alignment change in the amorphous region as a result of "stretching" during spinning of the silk, probably explains the mechanical property variations that we found across treatment subgroups. As C. mulmeinensis MA silk increases both in strength and elasticity when the spiders are exposed to wind, bioengineers may consider it as a model for the development of high-performance silk biomimetics. PMID:23947397

Blamires, Sean J; Wu, Chao-Chia; Wu, Chung-Lin; Sheu, Hwo-Shuenn; Tso, I-Min

2013-10-14

335

Reversible hydrogel-solution system of silk with high beta-sheet content.  

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Silkworm silk has been widely used as a textile fiber, as biomaterials and in optically functional materials due to its extraordinary properties. The ?-sheet-rich natural nanofiber units of about 10-50 nm in diameter are often considered the origin of these properties, yet it remains unclear how silk self-assembles into these hierarchical structures. A new system composed of ?-sheet-rich silk nanofibers about 10-20 nm in diameter is reported here, where these nanofibers formed into "flowing hydrogels" at 0.5-2% solutions and could be transformed back into the solution state at lower concentrations, even with a high ?-sheet content. This is in contrast with other silk processed materials, where significant ?-sheet content negates reversibility between solution and solid states. These fibers are formed by regulating the self-assembly process of silk in aqueous solution, which changes the distribution of negative charges while still supporting ?-sheet formation in the structures. Mechanistically, there appears to be a shift toward negative charges along the outside of the silk nanofibers in our present study, resulting in a higher zeta potential (above -50 mV) than previous silk materials which tend to be below -30 mV. The higher negative charge on silk nanofibers resulted in electrostatic repulsion strong enough to negate further assembly of the nanofibers. Changing silk concentration changed the balance between hydrophobic interactions and electrostatic repulsion of ?-sheet-rich silk nanofibers, resulting in reversible hydrogel-solution transitions. Furthermore, the silk nanofibers could be disassembled into shorter fibers and even nanoparticles upon ultrasonic treatment following the transition from hydrogel to solution due to the increased dispersion of hydrophobic smaller particles, without the loss of ?-sheet content, and with retention of the ability to transition between hydrogel and solution states through reversion to longer nanofibers during self-assembly. These reversible solution-hydrogel transitions were tunable with ultrasonic intensity, time, or temperature. PMID:25056606

Bai, Shumeng; Zhang, Xiuli; Lu, Qiang; Sheng, Weiqin; Liu, Lijie; Dong, Boju; Kaplan, David L; Zhu, Hesun

2014-08-11

336

Preadipocytes stimulate ductal morphogenesis and functional differentiation of human mammary epithelial cells on 3D silk scaffolds.  

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Epithelial-mesenchymal interactions play an important role in regulating normal tissue development as well as tumor development for the mammary gland, but much is yet to uncover to reach a full understanding of their complexity. To address this issue, the establishment of relevant, surrogate, three-dimensional (3D) human tissue culture models is essential. In the present study, a novel 3D coculture system was developed to study the interactions between human mammary epithelial cells (MCF10A) and adipocytes, a prominent stromal cell type in native breast tissue. The MCF10A cells were cultured within a mixture of Matrigel and collagen in 3D porous silk scaffolds with or without predifferentiated human adipose-derived stem cells (hASCs). The presence of hASCs inhibited MCF10A cell proliferation, induced both alveolar and ductal morphogenesis, and enhanced their functional differentiation as evidenced by histology and functional analysis. The alveolar structures formed by cocultures exhibited proper, immature polarity when compared with native breast tissue. In contrast, only alveolar structures with reverted polarity were observed in the MCF10A monocultures. The effect of ductal morphogenesis in cocultures may correlate to hepatocyte growth factor secreted by the predifferentiated hASCs, based on results from a cytokine blocking assay. Taken together, this in vitro coculture model on silk scaffolds effectively reconstitutes a physiologically relevant 3D microenvironment for epithelial cells and stromal cells and provides a useful system to study tissue organization and epithelial morphogenesis in normal or diseased breast development. PMID:19338449

Wang, Xiuli; Zhang, Xiaohui; Sun, Lin; Subramanian, Balajikarthick; Maffini, Maricel V; Soto, Ana; Sonnenschein, Carlos; Kaplan, David L

2009-10-01

337

Imaging of salivary gland tumours  

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

Lee, Y.Y.P.; Wong, K.T.; King, A.D. [Department of Diagnostic Radiology and Organ Imaging, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin NT, Hong Kong (Hong Kong); Ahuja, A.T. [Department of Diagnostic Radiology and Organ Imaging, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin NT, Hong Kong (Hong Kong)], E-mail: aniltahuja@cuhk.edu.hk

2008-06-15

338

Scintigraphy of the adrenal gland  

International Nuclear Information System (INIS)

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

339

Actinomycosis of the parotid gland.  

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- Actinomycosis is a slowly progressive infection caused by anaerobic bacteria with relatively decreasing incidence now-a-days. The Parotid gland is a quite rere site to be involved in cervico-facial actinomycosis as compared to the other sites in the face & neck region. We report a successfully managed case of Actinomycosis involving the parotid gland. PMID:23120106

Dubey, Abhilash; Murthy, J G; Banerjee, P K

2004-10-01

340

Physical Characterization of Functionalized Silk Material for Electronic Application and Devices  

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Naturally harvested spider silk fibers are investigated for their physical properties under ambient, humidified, iodine-doped, pyrolized, sputtered gold and carbon nanotube coated conditions. The functional properties include: humidity activated conductivity; enhanced flexibility and carbon yield of pyrolized iodized silk fibers; full metallic conductivity and flexibility of micron-sized gold-sputtered silk fibers; and high strain sensitivity of carbon nanotube coated silk fibers. Magic angle spinning nuclear magnetic resonance (MAS-NMR) and Fourier transform infrared spectroscopy (FTIR) are used to explore the nature of ambient and functionalized spider silk fiber, and significant changes in amino acid-protein backbone signature are correlated with gold sputtering, and iodine-doped conditions. The application of gold-sputtered neat spider silk fibers for making four terminal flexible, clean, ohmic contacts to organic superconductor samples and carbon nanotube coated silk fibers for heart pulse monitoring sensor are demonstrated. The role of silk thin film in organic thin film transistor will be briefly discussed.

Steven, Eden; Jobiliong, Eric; Park, Jin Gyu; Paravastu, Anant; Davidson, Michael; Baird, Michelle; Alamo, Rufina; Kaner, Papatya; Brooks, James; Siegrist, Theo

2012-02-01

 
 
 
 
341

All-water-based electron-beam lithography using silk as a resist  

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Traditional nanofabrication techniques often require complex lithographic steps and the use of toxic chemicals. To move from the laboratory scale to large scales, nanofabrication should be carried out using alternative procedures that are simple, inexpensive and use non-toxic solvents. Recent efforts have focused on nanoimprinting and the use of organic resists (such as quantum dot-polymer hybrids, DNA and poly(ethylene glycol)), which still require, for the most part, noxious chemicals for processing. Significant advances have been achieved using `green' resists that can be developed with water, but so far these approaches have suffered from low electron sensitivity, line edge roughness and scalability constraints. Here, we present the use of silk as a natural and biofunctional resist for electron-beam lithography. The process is entirely water-based, starting with the silk aqueous solution and ending with simple development of the exposed silk film in water. Because of its polymorphic crystalline structure, silk can be used either as a positive or negative resist through interactions with an electron beam. Moreover, silk can be easily modified, thereby enabling a variety of `functional resists', including biologically active versions. As a proof of principle of the viability of all-water-based silk electron-beam lithography (EBL), we fabricate nanoscale photonic lattices using both neat silk and silk doped with quantum dots, green fluorescent proteins (GFPs) or horseradish peroxidase (HRP).

Kim, Sunghwan; Marelli, Benedetto; Brenckle, Mark A.; Mitropoulos, Alexander N.; Gil, Eun-Seok; Tsioris, Konstantinos; Tao, Hu; Kaplan, David L.; Omenetto, Fiorenzo G.

2014-04-01

342

The study on radiation-induced graft copolymerization of meth-acrylamide onto silk fabric  

International Nuclear Information System (INIS)

The radiation-induced graft copolymerization of Meth-acrylamide onto silk fabric has been studied using electron beam and ?-irradiation. The processing monomer infusion conditions and radiation processing were studied in order to improve the properties of natural silk fabric

343

Socio-Economic Profile of Silk Weavers: A MicroLevel Study of Srinagar City  

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Full Text Available Kashmiri silk weavers and silk products are of international repute. Though the Kashmiri silk products are enjoying a ready market both at home and abroad, there are grey areas demanding immediate attention to sustain and further improve this traditional craft and to help the Kashmiri silk weavers to achieve new heights. In the present study, we have analysed the socio-economic profile and the problems of silk weavers in Srinagar city, trying to offer possible recommendations to address the grey areas. This study is based on both primary and secondary data sources. A primary survey was conducted in Srinagar City during the year 2012, consisting of 100 respondents chosen randomly. The study results revealed that the situation of the weavers was worrying: they were feeble due to illiteracy, financial constraints, health problems, meagre remuneration and poor Government support.

TAWHEED YOUSUF

2013-06-01

344

E-Commerce in silk industry of Assam: A critical study  

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Full Text Available In today’s over changing market, it is very difficult for the business to survive without proper marketing facility and the influence have clearly shown in the silk industry of Assam which is flourished but the over changing modern technology affect in silk industry of Assam. Now a days most of the business sectors adopting modern technology and flourish on the contrary the silk industry of Assam which is now centered in Sualkuchi known as the Asia’s largest silk village have fallen on bad days and unable to face competition from modern technology with the fast growing modern weaving techniques and more of that unable to compete the powerloom products. The produce of Sualkuchi depending on age-old and traditional method of weaving started to see its downfall. This article comprising about the benefits of E-Commerce in an organisation and an overview of silk industry of Assam.

Mithun Chandra Roy

2013-04-01

345

In Situ Raman Spectroscopic Study of Al-Infiltrated Spider Dragline Silk under Tensile Deformation.  

Science.gov (United States)

Natural materials consisting of protein structures impregnated with a tiny amount of metals often exhibit impressive mechanical behavior, which represents a new design paradigm for the development of biomimetic materials. Here, we produced Al-infiltrated silks by applying a modified Al2O3 atomic layer deposition process to the dragline silk of the Nephila pilipes spider, which showed unusual mechanical properties. The deformation behavior of the molecular structure of the Al-infiltrated silk was investigated by performing in situ Raman spectroscopy, where Raman shifts were measured concurrently with macroscopic mechanical deformations. For identifying the role of the infiltrated Al atoms, the study was performed in parallel with untreated silk, and the results were compared. Our experimental results revealed that superior mechanical properties of the Al-infiltrated silk are likely to be caused by the alterations of the sizes of the ?-sheet crystals and their distribution. PMID:25203848

Lee, Seung-Mo; Pippel, Eckhard; Moutanabbir, Oussama; Kim, Jae-Hyun; Lee, Hak-Joo; Knez, Mato

2014-10-01

346

Novel and simple synthesis of hollow porous silica fibers with hierarchical structure using silk as template  

International Nuclear Information System (INIS)

A novel and simple approach to synthesize the hollow porous silica fibers with hierarchical structure had been proposed, in which natural silk fiber was used as template with the aid of supercritical CO2. Supercritical CO2 can be used to proceed with coating, during which silica precursor (TEOS) dissolved in supercritical CO2 and the supercritical CO2 was in contact with the silk templates. After removal of silk templates by calcinations, the final silica fiber materials replicate not only macroscopic alignment structure along the silk direction, but also microscopic porous structure on the surface of silk. We have shown that it is possible to tune the diameter, wall thickness, and the porous structure of the tube-like silica fibers by varying the pressure and temperature of the supercritical CO2

347

Thai Silk Pattern: Conservation and Manufacturing Development to Create Added Value in the Province of Khon Kaen  

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Full Text Available Silk patterns are works of art that resembles the valuable and unique ethnic culture that is most important to the community. The history and development of silk patterns in the province of Khon Kaen can be divided into 2 periods, before and after the year 1976. During these periods there were many changes in the manufacturing of silk textiles. The origin of classical silk patterns came from direct modeling of plants, animals and nature. Contemporary silk patterns are modeled after mediums such as television, multimedia, publications and from client requests. The manufacturing tools have also been greatly improved from wooden tools to tools made from metals and tools reinforce with steel. Electric motors have also been utilized in increasing the efficiency in the transformation of silk such as in process of dyeing and spooling silk threads. Traditional materials in silk textile production utilized traditional home grown and produced silk threads while in modern times, the silk comes from factories and purchased in spools. Locally produced silk threads are still produced but in lesser quantity because natural pigments and threads are limited in color. Modern silk threads produced from factories come in many colors and sizes to choose from. Traditional designs and patterns of silk textiles had to be memorized and were passed down orally while contemporary patterns can be massed produced through patterns embedded in graph paper and computer graphic designs. The patterns of silk textiles have greatly improved after 1976 where many efforts were implemented to develop added value and broader market for silk textile products.

Kesini Sawatdi

2013-09-01

348

Chapter 13. Adrenal glands  

International Nuclear Information System (INIS)

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

349

Bioengineered silk gene delivery system for nuclear targeting.  

Science.gov (United States)

Gene delivery research has gained momentum with the use of lipophilic vectors that mimic viral systems to increase transfection efficiency. Maintaining cell viability with these systems remains a major challenge. Therefore, biocompatible biopolymers that are designed by combining non-immunological viral mimicking components with suitable carrier are explored to address these limitations. In the present study, dragline silk recombinant proteins are modified with DNA condensing units and the proton sponge endosomal escape pathway is utilized for enhanced delivery. Transfection efficiency in a COS-7 cell line is enhanced compared to lipofectamine and polyethyleneimine (PEI), as is cell viability. PMID:24889658

Yigit, Sezin; Tokareva, Olena; Varone, Antonio; Georgakoudi, Irene; Kaplan, D L

2014-09-01

350

Silk protein based hybrid photonic-plasmonic crystal.  

Science.gov (United States)

We propose a biocompatible hybrid photonic platform incorporating a 3D silk inverse opal (SIO) crystal and a 2D plasmonic crystal formed on the top surface of the SIO. This hybrid photonic-plasmonic crystal (HPPC) structure simultaneously exhibits both an extraordinary transmission and a pseudo-photonic band-gap in its transmission spectrum. We demonstrate the use of the HPPC as a refractive index (RI) sensor. By performing a multispectral analysis to analyze the RI value, a sensitivity of 200,000 nm·?%T/RIU (refractive index unit) is achieved. PMID:23571980

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

2013-04-01

351

Electroresponsive aqueous silk protein as "smart" mechanical damping fluid.  

Science.gov (United States)

Here we demonstrate the effectiveness of an electroresponsive aqueous silk protein polymer as a smart mechanical damping fluid. The aqueous polymer solution is liquid under ambient conditions, but is reversibly converted into a gel once subjected to an electric current, thereby increasing or decreasing in viscosity. This nontoxic, biodegradable, reversible, edible fluid also bonds to device surfaces and is demonstrated to reduce friction and provide striking wear protection. The friction and mechanical damping coefficients are shown to modulate with electric field exposure time and/or intensity. Damping coefficient can be modulated electrically, and then preserved without continued power for longer time scales than conventional "smart" fluid dampers. PMID:24750065

Jose, Rod R; Elia, Roberto; Tien, Lee W; Kaplan, David L

2014-05-14

352

Silk-based conformal, adhesive, edible food sensors.  

Science.gov (United States)

An array of passive metamaterial antennas fabricated on all protein-based silk substrates were conformally transferred and adhered to the surface of an apple. This process allows the opportunity for intimate contact of micro- and nanostructures that can probe, and accordingly monitor changes in, their surrounding environment. This provides in situ monitoring of food quality. It is to be noted that this type of sensor consists of all edible and biodegradable components, holding utility and potential relevance for healthcare and food/consumer products and markets. PMID:22266768

Tao, Hu; Brenckle, Mark A; Yang, Miaomiao; Zhang, Jingdi; Liu, Mengkun; Siebert, Sean M; Averitt, Richard D; Mannoor, Manu S; McAlpine, Michael C; Rogers, John A; Kaplan, David L; Omenetto, Fiorenzo G

2012-02-21

353

PHYTOCHEMICAL INVESTIGATION OF THE SILK COCOONS OF BOMBYX MORI L.  

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Full Text Available Silk cocoons, produced by Bombyx mori L. (Bombicidae are useful as hypotensive, expectorant, bronchodilator and attenuant drug in traditional medicine. Phytochemical investigation of the ethanolic extract of the cocoons led to the isolation of new phenolic constituents identified as n-butyl-3,4-dihydroxybenzoate (1, 3?,8?,9?-trigeranilanyl-3,4-dihydroxybenzoate (2, 3?,7?-dimethyl-3?-hydroxy-octanyl gallate (3, 3,4-dihydroxyphenyl-n-pentanyl ether (4 and 2,3,4-trihydoxypenyl-n-pentanyl ether (5 on the basis of spectral data analysis.

Kaskoos Raad A.

2012-05-01

354

Rate-dependent behavior of the amorphous phase of spider dragline silk.  

Science.gov (United States)

The time-dependent stress-strain behavior of spider dragline silk was already observed decades ago, and has been attributed to the disordered sequences in silk proteins, which compose the soft amorphous matrix. However, the actual molecular origin and magnitude of internal friction within the amorphous matrix has remained inaccessible, because experimentally decomposing the mechanical response of the amorphous matrix from the embedded crystalline units is challenging. Here, we used atomistic molecular dynamics simulations to obtain friction forces for the relative sliding of peptide chains of Araneus diadematus spider silk within bundles of these chains as a representative unit of the amorphous matrix in silk fibers. We computed the friction coefficient and coefficient of viscosity of the amorphous phase to be in the order of 10(-6) Ns/m and 10(4) Ns/m(2), respectively, by extrapolating our simulation data to the viscous limit. Finally, we used a finite element method for the amorphous phase, solely based on parameters derived from molecular dynamics simulations including the newly determined coefficient of viscosity. With this model the time scales of stress relaxation, creep, and hysteresis were assessed, and found to be in line with the macroscopic time-dependent response of silk fibers. Our results suggest the amorphous phase to be the primary source of viscosity in silk and open up the avenue for finite element method studies of silk fiber mechanics including viscous effects. PMID:24896131

Patil, Sandeep P; Markert, Bernd; Gräter, Frauke

2014-06-01

355

Comparison of methods for the repair of acute tympanic membrane perforations: Silk patch vs. paper patch.  

Science.gov (United States)

We investigated the effects of repairing large tympanic membrane (TM) perforations in rats with a thin silk patch compared with the commonly used paper patch. We performed bilateral myringotomies of 1.8 mm in diameter on 50 adult Sprague-Dawley rats with intact TMs. The perforations in the right ears of 40 rats were treated with a silk patch, and the perforations in the left ears of the same rats were treated with a paper patch. Ten rats acted as controls. The mean healing times of the TM perforations on the silk-patch-treated ears and the paper-patch-treated ears were 7.2+/-1.48 and 9.1+/-1.11 days, respectively (control 10.38+/-1.70 days). The difference between silk-patch- and paper-patch-treated ears was statistically significant, with a mean difference of 1.9 days (0.6-4.5 days). The mean perforation closure times were significantly shorter in silk-patch- and paper-patch-treated ears than in the control animals. The endoscopic and histological findings of this study provide evidence that silk-patch treatment accelerates wound healing and shortens TM perforation closure time. We suggest that the silk patch may prove to be an effective material for repairing TM perforations in human patients in an outpatient clinical setting. PMID:20082686

Kim, Jin; Kim, Chun Hoi; Park, Chan Hum; Seo, Jae-Nam; Kweon, Haeyong; Kang, Seok Woo; Lee, Kwang Gill

2010-01-01

356

Salivary Gland Cancer: Risk Factors  

Science.gov (United States)

... Factors Request Permissions Download PDF Salivary Gland Cancer: Risk Factors This section has been reviewed and approved by ... menu on the side of your screen. A risk factor is anything that increases a person’s chance of ...

357

Hodgkin Lymphoma in Adrenal Gland  

Directory of Open Access Journals (Sweden)

Full Text Available Primary adrenal lymphoma and lymphomas involving the adrenal glands are rare. Involvement of the adrenal gland with Hodgkin lymphoma is rarely reported in the literature. Here we report a 69-year-old male who was operated due to a mass lesion in his left adrenal region with a clinical diagnosis of surrenal carcinoma. Histopathological examination revealed a Hodgkin lymphoma of nodular sclerosing type.

Serdar BALCI

2010-01-01

358

Crystal Structure of a Model Spider Silk Peptide  

Science.gov (United States)

Crystallization study on a novel model silk peptide has been carried out using optical microscopy, AFM, TEM and electron diffraction. The sequence of the peptide, (E)5(GDVGGAGATGGS)2(E)5, is based on the GXYGGZ motif in the less repetitive amorphous blocks of Nephila clavipes spider dragline silk. When the peptide was crystallized out of aqueous solution, spherulites as well as dendritic crystals on the order of several to tens of microns in diameter were observed under polarizing optical microscope, depending on drying speed, volume of the droplet and concentration. The same crystals were collected and sonicated in methanol, a non-solvent, to yield individual crystals that were later examined in the electron microscope. Regular-shaped lamellar crystals of micron size were observed in the TEM. The lamellar thickness as determined by Pt/Pd shadowing and AFM is 50 Å. Selected area electron diffraction showed single crystal diffraction patterns indicating a possible orthorhombic unit cell of 9.91 x 5.57 x 20.40 Å.

Chen, Shujun; Gido, Samuel; Valluzzi, Regina; Kaplan, David

2001-03-01

359

Scent glands in legume flowers.  

Science.gov (United States)

Scent glands, or osmophores, are predominantly floral secretory structures that secrete volatile substances during anthesis, and therefore act in interactions with pollinators. The Leguminosae family, despite being the third largest angiosperm family, with a wide geographical distribution and diversity of habits, morphology and pollinators, has been ignored with respect to these glands. Thus, we localised and characterised the sites of fragrance production and release in flowers of legumes, in which scent plays an important role in pollination, and also tested whether there are relationships between the structure of the scent gland and the pollinator habit: diurnal or nocturnal. Flowers in pre-anthesis and anthesis of 12 legume species were collected and analysed using immersion in neutral red, olfactory tests and anatomical studies (light and scanning electron microscopy). The main production site of floral scent is the perianth, especially the petals. The scent glands are distributed in a restricted way in Caesalpinia pulcherrima, Anadenanthera peregrina, Inga edulis and Parkia pendula, constituting mesophilic osmophores, and in a diffuse way in Bauhinia rufa, Hymenaea courbaril, Erythrostemon gilliesii, Poincianella pluviosa, Pterodon pubescens, Platycyamus regnellii, Mucuna urens and Tipuana tipu. The glands are comprised of cells of the epidermis and mesophyll that secrete mainly terpenes, nitrogen compounds and phenols. Relationships between the presence of osmophores and type of anthesis (diurnal and nocturnal) and the pollinator were not found. Our data on scent glands in Leguminosae are original and detail the type of diffuse release, which has been very poorly studied. PMID:23574349

Marinho, C R; Souza, C D; Barros, T C; Teixeira, S P

2013-04-10

360

Autophagy in the endocrine glands.  

Science.gov (United States)

Autophagy is an important cellular process involving the degradation of intracellular components. Its regulation is complex and while there are many methods available, there is currently no single effective way of detecting and monitoring autophagy. It has several cellular functions that are conserved throughout the body, as well as a variety of different physiological roles depending on the context of its occurrence in the body. Autophagy is also involved in the pathology of a wide range of diseases. Within the endocrine system, autophagy has both its traditional conserved functions and specific functions. In the endocrine glands, autophagy plays a critical role in controlling intracellular hormone levels. In peptide-secreting cells of glands such as the pituitary gland, crinophagy, a specific form of autophagy, targets the secretory granules to control the levels of stored hormone. In steroid-secreting cells of glands such as the testes and adrenal gland, autophagy targets the steroid-producing organelles. The dysregulation of autophagy in the endocrine glands leads to several different endocrine diseases such as diabetes and infertility. This review aims to clarify the known roles of autophagy in the physiology of the endocrine system, as well as in various endocrine diseases. PMID:24565917

Weckman, Andrea; Di Ieva, Antonio; Rotondo, Fabio; Syro, Luis V; Ortiz, Leon D; Kovacs, Kalman; Cusimano, Michael D

2014-04-01

 
 
 
 
361

MRI of salivary gland tumors  

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MRI findings of 13 patients with proven salivary gland tumors, including 7 cases of parotid gland tumors, 2 cases of submandibular gland tumors, and 4 cases of minor salivary gland tumors, were reviewed. All examinations were carried out on a 1.5-T MRI system (General Electric, SIGNA Performance plus and SIMAZU, SMT-150X) with spin echo sequence. T1 and T2 weighted images and Gd-DTPA enhanced T1 weighted images were obtained. The results were as follows: All tumors demonstrated low to intermediate signal intensity on T1 weighted images and intermediate to high signal intensity on T2 weighted images. The differences between malignant and benign tumors were not detected by means of the signal intensity of the tumors. Tumor margins were clear except for 2 cases, including inflamed pleomorphic adenoma of the submandibular gland and adenoid cystic carcinoma of the parotid gland. Except for the case of adenolymphoma, internal structures of the tumor are inhomogenous, especially on T2 weighted images. Although the intraparotid facial nerve is not detected directly, whether the tumor is located on superficial or deep lobe could be detected by drawing a line between the lateral surface of the posterior belly of the digastric muscle and the lateral posterior border of the mandible except for one case and using the retromandibular vein except for two cases. (author).

Ariyoshi, Yasunori; Shimahara, Masashi; Senda, Jyunko; Sakinaka, Isao [Osaka Medical Coll., Takatsuki (Japan); Nakano, Yoshinobu

1996-04-01

362

MRI of salivary gland tumors  

International Nuclear Information System (INIS)

MRI findings of 13 patients with proven salivary gland tumors, including 7 cases of parotid gland tumors, 2 cases of submandibular gland tumors, and 4 cases of minor salivary gland tumors, were reviewed. All examinations were carried out on a 1.5-T MRI system (General Electric, SIGNA Performance plus and SIMAZU, SMT-150X) with spin echo sequence. T1 and T2 weighted images and Gd-DTPA enhanced T1 weighted images were obtained. The results were as follows: All tumors demonstrated low to intermediate signal intensity on T1 weighted images and intermediate to high signal intensity on T2 weighted images. The differences between malignant and benign tumors were not detected by means of the signal intensity of the tumors. Tumor margins were clear except for 2 cases, including inflamed pleomorphic adenoma of the submandibular gland and adenoid cystic carcinoma of the parotid gland. Except for the case of adenolymphoma, internal structures of the tumor are inhomogenous, especially on T2 weighted images. Although the intraparotid facial nerve is not detected directly, whether the tumor is located on superficial or deep lobe could be detected by drawing a line between the lateral surface of the posterior belly of the digastric muscle and the lateral posterior border of the mandible except for one case and using the retromandibular vein except for two cases. (author)

363

Mating behavior of Theridiosoma gemmosum (araneae: Theridiosomatidae: The unusual role of the male dragline silk  

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Full Text Available The mating of Theridiosoma gemmosum consists of a series of successive copulations. In the interval between two consecutive copulations, the females unwind the silken threads released by the male spinning organs; these threads are known as draglines or lifelines. The silk thus obtained is rolled up by the females into bundles, which they ingest prior to the next copulation. In other words, the mating of T. gemmosum involves the transfer of nutrients from the male to the female via silk. The silk provided by the male during copulation and eaten by the female, can be considered a nuptial gift.

Hajer J.

2011-01-01

364

Streaming submandibular gland  

International Nuclear Information System (INIS)

Twenty female young adult rats were injected with tritiated thymidine (3HTdR). The animals were then killed in groups of five, at the following times: 1 hour, and 4, 16, and 23 days. Autoradiograms of sections through the submandibular gland were prepared, and the location of labelled cells in relationship to tubuli and acini was recorded. The different tubular and acinar cross sections could be distinguished by their cell number. Narrow tubuli had fewer nuclei than the wider ones. The nuclear number of a cross section was defined as its class and the location of a labelled epithelial cell was expressed in relationship to the class where it was found. The location of a labelled stromal cell was determined by the class of its neighboring tubular or acinar cross sections. The mean cell numbers of intercalated, granular, and striated duct cross sections were, respectively, 4.7, 10.5, and 10.2, while the average cell content of acini was 4.7 cells. One hour after labelling most labelled tubular epithelial and stromal cells were found in tubular cross sections (or low tubular classes), while in the acini, labelled epithelial and stromal cells were found mainly in wider cross sections (or higher acinar classes). Within the next 23 days labelled tubular cells and stroma proceeded into higher classes, while labelled acinar epithelium and stroma cells were displaced into narrower cross sections (or lower classes). The displaced tubular epithelium and stroma covered daily 0.26 classes. At this velocity the cell will reach the highest tubular class in 62 days and the estimated maximal tubular cell life span is 62 days

365

Characterization of a novel glycine-rich protein from the cell wall of maize silk tissues.  

Science.gov (United States)

The isolation, characterization and regulation of expression of a maize silk-specific gene is described. zmgrp5 (Zea mays glycine-rich protein 5) encodes a 187 amino acid glycine-rich protein that displays developmentally regulated silk-specific expression. Northern, Western, in situ mRNA hybridization and transient gene expression analyses indicate that zmgrp5 is expressed in silk hair and in cells of the vascular bundle and pollen tube transmitting tissue elements. The protein is secreted into the extracellular matrix and is localized in the cell wall fraction mainly through interactions mediated by covalent disulphide bridges. Taken together, these results suggest that the protein may play a role in maintaining silk structure during development. This is the first documented isolation of a stigma-specific gene from maize, an important agronomic member of the Poaceae family. PMID:16528565

Tao, T Y; Ouellet, T; Dadej, K; Miller, S S; Johnson, D A; Singh, J

2006-08-01

366

Similarities in the structural organization of major and minor ampullate spider silk.  

Science.gov (United States)

Minor and major ampullate spider silks are studied under varying mechanical stress by static and time-resolved FT-IR spectroscopy. This enables one to trace the external mechanical excitation on a microscopic level and to determine for the different moieties the time dependence of the molecular order parameters and corresponding band shifts. It is concluded that the hierarchical nanostructure of both types of silk is similar, being composed of highly oriented nanocrystals, which are interconnected by amorphous chains that obey the worm-like chain model and have a Gaussian distribution of pre-strain. By that it is possible to describe the mechanical properties of both silks by two adjustable parameters only, the center and width of the distribution. For major ampullate silk, the observed variability is small in pronounced contrast to the findings for minor ampullate. PMID:21706668

Papadopoulos, Periklis; Ene, Roxana; Weidner, Immanuel; Kremer, Friedrich

2009-05-19

367

Silk-based nanocomplexes with tumor-homing peptides for tumor-specific gene delivery.  

Science.gov (United States)

Nanoscale complexes of recombinant silk molecules containing THPs with DNA are designed as less cytotoxic and highly target-specific gene carriers. Genetically engineered silk proteins containing poly(L-lysine) domains to interact with pDNA and the THP to bind to specific tumorigenic cells for target-specific pDNA delivery are prepared, followed by in vitro transfection into MDA-MB-435 melanoma cells, highly metastatic human breast tumor MDA-MB-231?cells, and non-tumorigenic MCF-10A breast epithelial cells. The silk/poly(L-lysine) block copolymer containing Lyp1 (ML-Lyp1) shows significant differences from silk/poly(L-lysine) block copolymer containing F3 (ML-F3) in cytotoxicity to MCF10A cells. ML-F3 is the most promising candidate for target delivery into tumorigenic cells. PMID:22052706

Numata, Keiji; Mieszawska-Czajkowska, Aneta J; Kvenvold, Laura A; Kaplan, David L

2012-01-01

368

Spider-silk-like shape memory polymer fiber for vibration damping  

Science.gov (United States)

In this study, the static and dynamic properties of shape memory polyurethane (SMPU) fiber are reported and compared to those of spider dragline silk. Although the polymeric fiber has a lower strength compared to spider dragline silks (0.2–0.3 GPa versus 1.1 GPa), it possesses much higher toughness (276–289 MJ m?3 versus 160 MJ m?3), due to its excellent extensibility. The dynamic mechanical tests reveal that SMPU fiber has a high damping capacity (tan ? = 0.10–0.35) which is comparable to or even higher than that of spider silks (tan ? = 0.15). In addition, we found that, different programming methods change the shape memory and damping properties of the fiber in different ways and cold-drawing programming is more advocated in structural applications. These results suggest that the SMPU fiber has similar vibration damping and mechanical properties as spider silk, and may find applications in lightweight engineering structures.

Yang, Qianxi; Li, Guoqiang

2014-10-01

369

[Research on the silk aging with x-ray diffraction spectra].  

Science.gov (United States)

The present paper did some researches on the deterioration mechanism and the changes in crystallinity of silk fabrics by means of the X-ray diffraction analysis. The samples artificially aged and excavated from Hubei, Innermongolia, Shaanxi and Qinghai provinces were analyzed. The artificial aging was done by simulating three main natural aging factors: light, heat and hydrolysis. The analytical results show that X-ray diffraction analysis could reveal the aging process and characteristic of silk, as well as the changes in crystallinity during silk aging. The X-ray diffraction analysis is of practical value for the conservation state and aging mechanism studies of ancient silk. In addition, X-ray diffraction analysis could also provide important information on ancient technology of textile and apparel. PMID:20302128

Zhang, Xiao-mei; Yuan, Si-xun

2010-01-01

370

Silk-Cloth Weaving Development of the Mon-Khmer Ethnic Group in Lower-Isan  

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Full Text Available Problem statement: Silk cloth weaving culture of the Mon-Khmer ethnic group in Lower-Isan has a specific identity which should be handed down to future generation. The purposes of this research were to examine: (1 the body knowledge concerning silk clothes of the Mon-Khmer ethnic group in Lower-Isan region, (2 the process of production or silk-cloth weaving of the Mon-Khmer ethnic group in Lower-Isan region and (3 development of silk-cloth weaving of the Mon-Khmer ethnic group in Lower-Isan region. Approach: The research data was gathered from documents concerned and research fields. A sample was 156 people living at 7 villages and those involving silk-cloth production or weaving. The data was analyzed according to the research purposes and presented by means of a descriptive analysis. Results: Silk-cloth weaving has been a cultural heritage transferred from ancestors. In 1215 Chow Tang Kwan stated that the Siamese people came there, grew mulberries, raised silkworms and wove silk clothes from that time through learning from generation to generation. The cloth-identity and patterns have been party influenced by their ethnic group together with the way of life in each period. In the past, the main purpose of silk-cloth weaving was for household use. Some of the silk clothes were kept for being supplement to various rituals and Buddhist ceremonies. Thus, it was not necessary for them to have commercial production. Household-labor was still an important-productive factor of sufficient economy and reliant society. For the production process, it has been found that at present the economic and social structures have changed from household-use production to commercial production. There are complete production processes in the type of forming groups and the management system by increasing production competency to obtain both quantity and quality as well as standard prices. There are transmutations into a variety of other products and promotion of domestic and foreign marketing. However, what is firmly retained to the community is the traditional silk-cloth weaving. For silk-cloth weaving development, it shows that the appropriate model of silk-cloth weaving development of the Mon-Khmer ethnic group in Lower-Isan region consists of economic and social changes which can affect silk-cloth weaving culture of the Mon-Khmer ethnic group in Lower-Isan region. Conclusion/Recommendations: Silk-cloth weaving is a very important cultural heritage of Mon-Khmer ethnic group. It accumulated and adhered from ancestors and transacting through social recognition in each period. All of production processes of each period are scrupulous such as growing mulberries, raising silkworms, producing fibers and dyeing fibers. The development of identity, patterns, weaving technique, production equipment, transmutation equipment and marketing cause a sequence of changes and development of the process of silk-cloth production or weaving from weaving for household use to commercial production. At present, there are many forming groups which produce for a commercial purpose. However, what is firmly retained to the community is the traditional of silk-cloth weaving by hand-loom.

Wira Phansuwan

2010-01-01

371

Micromolar biosensing of nitric oxide using myoglobin immobilized in a synthetic silk film.  

Science.gov (United States)

In this work we investigate the use of coiled-coil silk proteins, produced in recombinant Escherichia coli, as a new material for immobilizing biosensors. Myoglobin was embedded in transparent honeybee silk protein films. Immobilized myoglobin maintained a high affinity for nitric oxide (KD NO=52 µM) and good sensitivity with a limit of detection of 5 µM. The immobilized myoglobin-silk protein film was stable and could be stored as a dry film at room temperature for at least 60 days. The effect of immobilization on the structure of myoglobin was fully investigated using UV/visible, Fourier Transform Infrared and Raman spectroscopy, which indicated a weakening in the strength of the iron-histidine bond. This study demonstrates that recombinant coiled-coil silk proteins provide a safe and environmentally friendly alternative to sol-gels for stabilizing heme proteins for use as optical biosensors. PMID:25014754

Rapson, Trevor D; Church, Jeffrey S; Trueman, Holly E; Dacres, Helen; Sutherland, Tara D; Trowell, Stephen C

2014-12-15

372

Influence of variety and harvest maturity on phytochemical content in corn silk.  

Science.gov (United States)

Corn silk has been used as a traditional herb in Asia. The objective of this study was to evaluate variability in phytochemicals in corn varieties at three maturity stages of corn silk. Ten vegetable corn varieties were evaluated in a completely randomized design with three replications. Data were recorded for total phenolic (TPC), total flavonoids (TFC), total anthocyanin (TAC) and antioxidant activity (AA) by DPPH free-radical-scavenging assays. Differences among corn varieties were observed for all parameters at all maturity stages, and the interactions between maturity stage and corn variety were significant. TPC and TAC were highest at the milky stage, whereas TFC and AA were highest at the silking stage. TPC, TFC and AA were highest in super sweet corn and white corn at the silking stage. PWC5 variety of purple waxy corn at the milky stage had the highest values for all parameters, and it is useful for further development of functional food products. PMID:25236247

Sarepoua, Eakrin; Tangwongchai, Ratchada; Suriharn, Bhalang; Lertrat, Kamol

2015-02-15

373