WorldWideScience

Sample records for cell surfaces synthesis

  1. Comparison of bacterial cells and amine-functionalized abiotic surfaces as support for Pd nanoparticle synthesis

    DEFF Research Database (Denmark)

    De Corte, Simon; Bechstein, Stefanie; Lokanathan, Arcot R.

    2013-01-01

    An increasing demand for catalytic Pd nanoparticles has motivated the search for sustainable production methods. An innovative approach uses bacterial cells as support material for synthesizing Pd nanoparticles by reduction of Pd(II) with e.g. hydrogen or formate. Nevertheless, drawbacks...... nanoparticles, and that abiotic surfaces could support the Pd particle synthesis as efficiently as bacteria. In this study, we explore the possibility of replacing bacteria with amine-functionalized materials, and we compare different functionalization strategies. Pd nanoparticles formed on the support...... of microbially supported Pd catalysts are the low catalytic activity compared to conventional Pd nanocatalysts and the possible poisoning of the catalyst surface by sulfur originating from bacterial proteins. A recent study showed that amine groups were a key component in surface-supported synthesis of Pd...

  2. Synthesis and application of water-soluble, photoswitchable cyanine dyes for bioorthogonal labeling of cell-surface carbohydrates.

    Science.gov (United States)

    Mertsch, Alexander; Letschert, Sebastian; Memmel, Elisabeth; Sauer, Markus; Seibel, Jürgen

    2016-09-01

    The synthesis of cyanine dyes addressing absorption wavelengths at 550 and 648 nm is reported. Alkyne functionalized dyes were used for bioorthogonal click reactions by labeling of metabolically incorporated sugar-azides on the surface of living neuroblastoma cells, which were applied to direct stochastic optical reconstruction microscopy (dSTORM) for the visualization of cell-surface glycans in the nm-range.

  3. Flow cytometric measurement of RNA synthesis based on bromouridine labelling and combined with measurement of DNA content or cell surface antigen

    DEFF Research Database (Denmark)

    Jensen, P O; Larsen, J; Larsen, J K

    1993-01-01

    that RNA synthesis increased within the first 24 hours of phytohemagglutinin (PHA) stimulation, reaching a maximum at 48 hours, when cells had entered the cell cycle. Using a new method for flow cytometric dual parameter analysis of BrUrd incorporation and a cell surface antigen, spontaneous RNA synthesis...

  4. Synthesis of the Oligosaccharide Fragment of the Surface of TumorCell and Its Analogue

    Institute of Scientific and Technical Information of China (English)

    QinZhihui; ZhangLihe; LiZhongjun

    2001-01-01

    Selectins are a new class of carbohydrate-binding glycoproteins which have been identified on the surface ofspecific cell types, such as leukocytes,platelets and vascular endothelium.It is now known that the selectin-carbohydrate recognition not only play key roles at early stage of the inflammatory reaction,but also are very important for the invasion and metastasis of tumors.

  5. Synthesis of the Oligosaccharide Fragment of the Surface of Tumor Cell and Its Analogue

    Institute of Scientific and Technical Information of China (English)

    Qin Zhihui; Zhang Lihe; Li Zhongjun

    2001-01-01

    @@ Selectins are a new class of carbohydrate-binding glycoproteins which have been identified on the surface of specific cell types, such as leukocytes, platelets and vascular endothelium. It is now known that the selectincarbohydrate recognition not only play key roles at early stage of the inflammatory reaction, but also are very important for the invasion and metastasis of rumors. These results suggested that selectin antagonists can be used as anti-adhesive therapeutics to pathological inflammatory conditions, such as reperfusion injury, storke, etc. and will be helpful to the inhibition of the matastasis of tumor cells.

  6. Design and synthesis of nanomaterials for surface-enhanced Raman scattering, fuel cell technology, and photonics

    Science.gov (United States)

    Camargo, Pedro Henrique Cury

    In the first part of my dissertation, I developed two approaches for selectively probing the SERS activities of individual hot spots, i.e., experimentally detect the SERS signals only for the molecules that are trapped within the hot-spot region in individual Ag nanoparticle dimers. Then, I performed a systematic investigation on the SERS activity of individual dimers composed of two closed spaced Ag nanoparticles. By utilizing Ag nanoparticles displaying a variety of well-defined shapes, sizes and orientations to construct the dimers, I were able to precisely correlate the detected SERS signals to the specific geometry of individual hot spots. In the second part of this dissertation, I performed a systematic investigation on the galvanic replacement reaction between PtCl62- and Pd nanocrystals with well-defined shapes including octahedra, nanocubes, and nanorods. The resultant hollow Pd-Pt bimetallic nanostructures were employed as electrocatalysts for the oxygen reduction reaction (ORR). Our results demonstrated that the nanostructures derived from Pd octahedra displayed the highest ORR activity, being 1.7 times more active based on equivalent Pt mass than the commercial Pt/C. I also conducted a mechanistic study on the galvanic replacement reaction between AuCl4- and Pd nanorods. Differently from the Pd-Pt system, a new type of hybrid nanostructure in the tadpole shape consisting of a Au head and a Pd tail was obtained due to a localized galvanic replacement mechanism. As an extension of my work to develop new electrocatalysts for the ORR, a templateengaged reaction was utilized for the synthesis of RuSe2+delta nanotubes. The RuSe2+delta nanotubes were active towards the ORR and displayed no loss in activity in the presence of methanol, as opposed to commercial Pt/C. Finally, the template-engaged reaction was applied to the synthesis of Se MSe (M = Zn, Cd or Pb) colloidal spheres having similar sizes but different compositions. They were utilized as building

  7. Surface active monomers synthesis, properties, and application

    CERN Document Server

    Borzenkov, Mykola

    2014-01-01

    This brief includes information on the background?of and development of synthesis of various types of surface active monomers. The authors explain the importance of utilization of surface active monomers for creation of surface active polymers? and the various biomedical applications of such compounds . This brief introduces techniques for the synthesis of novel types of surface active monomers, their colloidal and polymerizable properties and application for needs of medicine and biology.

  8. Programming Surface Chemistry with Engineered Cells.

    Science.gov (United States)

    Zhang, Ruihua; Heyde, Keith C; Scott, Felicia Y; Paek, Sung-Ho; Ruder, Warren C

    2016-09-16

    We have developed synthetic gene networks that enable engineered cells to selectively program surface chemistry. E. coli were engineered to upregulate biotin synthase, and therefore biotin synthesis, upon biochemical induction. Additionally, two different functionalized surfaces were developed that utilized binding between biotin and streptavidin to regulate enzyme assembly on programmable surfaces. When combined, the interactions between engineered cells and surfaces demonstrated that synthetic biology can be used to engineer cells that selectively control and modify molecular assembly by exploiting surface chemistry. Our system is highly modular and has the potential to influence fields ranging from tissue engineering to drug development and delivery.

  9. Templated green synthesis of plasmonic silver nanoparticles in onion epidermal cells suitable for surface-enhanced Raman and hyper-Raman scattering

    Directory of Open Access Journals (Sweden)

    Marta Espina Palanco

    2016-06-01

    Full Text Available We report fast and simple green synthesis of plasmonic silver nanoparticles in the epidermal cells of onions after incubation with AgNO3 solution. The biological environment supports the generation of silver nanostructures in two ways. The plant tissue delivers reducing chemicals for the initial formation of small silver clusters and their following conversion to plasmonic particles. Additionally, the natural morphological structures of the onion layers, in particular the extracellular matrix provides a biological template for the growth of plasmonic nanostructures. This is indicated by red glowing images of extracellular spaces in dark field microscopy of onion layers a few hours after AgNO3 exposure due to the formation of silver nanoparticles. Silver nanostructures generated in the extracellular space of onion layers and within the epidermal cell walls can serve as enhancing plasmonic structures for one- and two-photon-excited spectroscopy such as surface enhanced Raman scattering (SERS and surface enhanced hyper-Raman scattering (SEHRS. Our studies demonstrate a templated green preparation of enhancing plasmonic nanoparticles and suggest a new route to deliver silver nanoparticles as basic building blocks of plasmonic nanosensors to plants by the uptake of solutions of metal salts.

  10. Role of lipid raft components and actin cytoskeleton in fibronectin-binding, surface expression, and de novo synthesis of integrin subunits in PGE2- or 8-Br-cAMP-stimulated mastocytoma P-815 cells.

    Science.gov (United States)

    Okada, Yasuyo; Nishikawa, Jyun-ichi; Semma, Masanori; Ichikawa, Atsushi

    2014-04-01

    Integrins are heterodimeric adhesion receptors essential for adhesion of non-adherent cells to extracellular ligands such as extracellular matrix components. The affinity of integrins for ligands is regulated through a process termed integrin activation and de novo synthesis. Integrin activation is regulated by lipid raft components and the actin structure. However, there is little information on the relationship between integrin activation and its de novo synthesis. Cancerous mouse mast cells, mastocytoma P-815 cells (P-815 cells) are known to bind to fibronectin through de novo synthesis of integrin subtypes by prostaglandin (PG) E2 stimulation. The purpose of this study was to clarify the relationship between lipid raft components and the actin cytoskeleton, and PGE2-induced P-815 cells adhesion to fibronectin and the increase in surface expression and mRNA and protein levels of αvβ3 and αIIbβ3 integrins. Cholesterol inhibitor 6-O-α-maltosyl-β cyclodextrin, glycosylphosphatidylinositol-anchored proteins inhibitor phosphatidylinositol-specific phospholipase C and actin inhibitor cytochalasin D inhibited PGE2-induced cell adhesion to fibronectin, but did not regulate the surface expression and mRNA and protein levels of αv and αIIb, and β3 integrin subunits. In addition, inhibitor of integrin modulate protein CD47 had no effect on PGE2- and 8-Br-cAMP-induced cell adhesion. These results suggest that lipid raft components and the actin cytoskeleton are directly involved in increasing of adhesion activity of integrin αIIb, αv and β3 subunits to fibronectin but not in stimulating of de novo synthesis of them in PGE2-stimulated P-815 cells. The modulation of lipid rafts and the actin structure is essential for P-815 cells adhesion to fibronectin.

  11. Synthesis and optimization of fluorescent poly(N-isopropyl acrylamide)-coated surfaces by atom transfer radical polymerization for cell culture and detachment.

    Science.gov (United States)

    Cooperstein, Marta A; Bluestein, Blake M; Canavan, Heather E

    2014-03-16

    Although there are many stimulus-responsive polymers, poly(N-isopropyl acrylamide) (pNIPAM) is of special interest due to the phase change it undergoes in a physiologically relevant temperature range that leads to the release of cells and proteins. The nondestructive release of cells opens up a wide range of applications, including the use of pNIPAM for cell sheet and tissue engineering. In this work, pNIPAM surfaces were generated that can be distinguished from the extracellular matrix. A polymerization technique was adapted that was previously used by Mendez, and the existing protocol was optimized for the culture of mammalian cells. The resulting surfaces were characterized with X-ray photoelectron spectroscopy and goniometry. The developed pNIPAM surfaces were further adapted by incorporation of 5-acrylamidofluorescein to generate fluorescent pNIPAM-coated surfaces. Both types of surfaces (fluorescent and nonfluorescent) sustained cellular attachment and produced cellular detachment of ∼90%, and are therefore suitable for the generation of cell sheets for engineered tissues and other purposes. These surfaces will be useful tools for experiments investigating cellular detachment from pNIPAM and the pNIPAM/cell interface.

  12. Differentiation and cytokine synthesis of human alveolar osteoblasts compared to osteoblast-like cells (MG63) in response to titanium surfaces.

    Science.gov (United States)

    Rausch-fan, Xiaohui; Qu, Zhe; Wieland, Marco; Matejka, Michael; Schedle, Andreas

    2008-01-01

    The aim of this study was to investigate the influence of different implant surface topographies and chemistries on the expression of differentiation/proliferation markers on MG63 cells and primary human alveolar osteoblasts. Hydrophobic acid-etched (A) and hydrophobic coarse-grit-blasted, acid-etched (SLA) surfaces and hydrophilic acid-etched (modA) and hydrophilic coarse-grit-blasted (modSLA) surfaces were produced. Thereby, modA and modSLA surfaces were rinsed under nitrogen protection and stored in a sealed glass tube containing isotonic NaCl solution at pH 4-6. Tissue culture plates without specimens served as controls. The behavior of MG63 cells and primary human alveolar osteoblasts (AOB) grown on all surfaces was compared through determination of alkaline phosphatase (ALP) activity, cell proliferation ((3)H-thymidin incorporation, MTT colorimetric assay) and expression of osteocalcin (OC), osteoprotegerin (OPG), transforming growth factor-beta1 (TGF-beta(1)) and vascular endothelial growth factor (VEGF), detected with commercial available test kits. Proliferation of MG63 and primary cells was highest on controls, followed by A surfaces, modA and SLA surfaces being almost on the same level and lowest on modSLA surfaces. modSLA surfaces exhibited highest ALP and OC production, followed by SLA, modA and A surfaces. Proliferation and OC production were comparable for MG63 cells and AOB. OPG, TGF-beta(1) and VEGF produced on primary cells showed a slightly different rank order on different surfaces compared to MG63 cells. modSLA still showed the highest production of OPG, TGF-beta(1) and VEGF, but was followed by modA, SLA and A. Statistical significance was checked by ANOVA (pmodA surfaces showed enhanced expression of OPG, TGF-beta(1) and VEGF on MG63 cells compared to primary human alveolar osteoblasts. Overall, the lowest proliferation rates and the highest expressions of differentiation markers and growth factor productions were observed on modSLA.

  13. A straightforward route to the synthesis of a surface-enhanced Raman scattering probe for targeting transferrin receptor-overexpressed cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jing; Wang Zhuyuan; Tan Xuebin; Li Jin; Song Chunyuan; Zhang Ruohu; Cui Yiping, E-mail: cyp@seu.edu.cn [Advanced Photonics Center, Southeast University, Nanjing 210096 (China)

    2010-08-27

    A tumor cell targeting surface-enhanced Raman scattering (SERS) probe has been successfully synthesized by using p-mercaptobenzoic acid (pMBA) as both the SERS reporter and the conjugation agent for attaching transferrin molecules, which shows experimentally the targeting ability for transferrin receptor-overexpressed HeLa cells and exhibits strong SERS signals when being incubated inside cells. To prove that the uptake of such a SERS probe is through a Tf-receptor-mediated endocytosis process, two control experiments: (1) HeLa cells being incubated with the probe at 4 deg. C and (2) HeLa cells being pre-blocked with free transferrin at 37 deg. C, were employed. The difference of SERS intensity between the transferrin-overexpressed HeLa cells and transferrin-pre-blocked HeLa cells indicates that the probe has the potential to selectively target tumor cells.

  14. [Cell surface RNA--a possible molecular receptor of adaptogens].

    Science.gov (United States)

    Malenkov, A G; Kolotygina, I M

    1984-01-01

    When RNA of the cell surface is destroyed with RNAase, the effect of adaptogenes is removed. Such effect is produced by introduction of actinomycin D 30 minutes before intake of adaptogene. Destruction of surface RNA stimulates protein synthesis. Comparison of these facts permits a hypothesis to be advanced saying that surface RNA is a receptor of adaptogenes obtained from plants of Aralia family.

  15. Templated green synthesis of plasmonic silver nanoparticles in onion epidermal cells suitable for surface-enhanced Raman and hyper-Raman scattering

    DEFF Research Database (Denmark)

    Palanco, Marta Espina; Mogensen, Klaus Bo; Guehlke, Marina

    2016-01-01

    We report fast and simple green synthesis of plasmonic silver nanoparticles in the epidermal cells of onions after incubation with AgNO3 solution. The biological environment supports the generation of silver nanostructures in two ways. The plant tissue delivers reducing chemicals for the initial...... formation of small silver clusters and their following conversion to plasmonic particles. Additionally, the natural morphological structures of the onion layers, in particular the extracellular matrix provides a biological template for the growth of plasmonic nanostructures. This is indicated by red glowing...... images of extracellular spaces in dark field microscopy of onion layers a few hours after AgNO3 exposure due to the formation of silver nanoparticles. Silver nanostructures generated in the extracellular space of onion layers and within the epidermal cell walls can serve as enhancing plasmonic structures...

  16. Surface chemical immobilization of parylene C with thermosensitive block copolymer brushes based on N-isopropylacrylamide and N-tert-butylacrylamide: synthesis, characterization, and cell adhesion/detachment.

    Science.gov (United States)

    Zhang, Changhong; Vernier, P Thomas; Wu, Yu-Hsuan; Yang, Wangrong; Thompson, Mark E

    2012-01-01

    Poly(N-isopropylacrylamide) (pNIPAM), poly(N-tert-butylacrylamide) (pNTBAM), and their copolymer brushes were covalently immobilized onto parylene C (PC) surfaces via surface initiated atom transfer radical polymerization (ATRP). Contact angle measurement between 13 and 40°C showed that the hydrophobicity of the modified PC surfaces was thermally sensitive. Among these samples, PC grafted with pNIPAM (PC-NI), PC grafted with pNTBAM (PC-NT) and PC grafted with copolymer brushes containing pNTBAM and pNIPAM (PC-NT-NI) exhibited the lower critical solution temperature (LCST) at 29, 22, and 24°C, respectively. Cytocompatibility study for the modified surfaces was performed by 5 days human skin fibroblast culture at 37°C. Data showed that only a very small amount of cells adhered on the PC and PC-NI surfaces, while a significantly higher amount of cell adhesion and growth was observed on PC-NT and PC-NT-NI surfaces. Furthermore, cell detachment at the temperatures of 24 and 6°C were studied after the substrates were cultured with cells at 37°C for 24 h. The results showed that the cells on PC-NI formed the aggregations and loosely attached on the substrate after 30-min culture at 24°C, while no significant cell detachment was observed for PC-NT and PC-NT-NI samples at this temperature. By continuing the cell culture for additional 100 min at 6°C for PC-NT and PC-NT-NI, about 10 and 35% of the cells were found detached respectively, and the unattached cells aggregated on the substrate. In comparison, cells cultured on the tissue culture petri dish (TCP) exhibited no quantity and morphology changes at the culture temperatures of 37, 24, and 6°C. This study showed that: (1) immobilization of PC with nonthermal sensitive pNTBAM could provide PC surface thermal sensitive hydrophilicity; (2) the chlorines on the polymer brushes of PC-NT could be used to further initiate the ATRP pNIPAM and form block copolymer brushes; (3) the incorporation of pNTBAM into pNIPAM on PC

  17. Stable isotope labeling of oligosaccharide cell surface antigens

    Energy Technology Data Exchange (ETDEWEB)

    Unkefer, C.J.; Silks, L.A. III; Martinez, R.A. [and others

    1998-12-31

    The overall goal of this Laboratory Directed Research and Development (LDRD) project was to develop new methods for synthesis of {sup 13}C-labeled oligosaccharides that are required for nuclear magnetic resonance (NMR) studies of their solution conformation. Oligosaccharides are components of the cell`s outer surface and are involved in important processes such as cell-cell recognition and adhesion. Recently, Danishefsky and coworkers at Slone-Kettering Cancer Center developed a method for the solid-phase chemical synthesis of oligosaccharides. The specific goal of this LDRD project was to prepare uniform {sup 13}C-labeled aldohexose precursors required for the solid-phase synthesis of the Lewis blood-group antigenic determinants. We report the synthesis of {sup 13}C-labeled D-glucal, D-galactal and Fucosyl precursors. We have been collaborating with the Danishefsky group on the synthesis of the Lewis oligosaccharides and the NMR analysis of their solution conformation.

  18. Internalization, lysosomal degradation and new synthesis of surface membrane CD4 in phorbol ester-activated T-lymphocytes and U-937 cells

    DEFF Research Database (Denmark)

    Petersen, C M; Christensen, E I; Andresen, B S

    1992-01-01

    degradation was low in resting cells. Endocytosis and/or degradation of anti-CD4 mAb was suppressed by H7, and by inhibitors of membrane traffic (Monensin) and lysosome function (methylamine, chloroquine). Immunocytochemistry localized CD4 to the surface of unstimulated T-cells. Upon PMA stimulation...... occasional labeling was seen in endosomes but whole cell CD4 decreased dramatically. However, methylamine-treated PMA blasts showed accumulation of CD4 in lysosomes and accordingly, pulse-chase experiments in biolabeled cell cultures suggested a manifest reduction of CD4 half-life in response to PMA. Despite...... in activated cells was further evidenced by metabolic labeling and Northern blot analysis demonstrating unaltered or slightly increased CD4 protein and mRNA levels resulting from PMA. Our findings demonstrate that phorbol esters downregulate the cellular CD4 pool by endocytosis and subsequent lysosomal...

  19. Cell surface engineering of mesenchymal stem cells.

    Science.gov (United States)

    Sarkar, Debanjan; Zhao, Weian; Gupta, Ashish; Loh, Wei Li; Karnik, Rohit; Karp, Jeffrey M

    2011-01-01

    By leveraging the capacity to promote regeneration, stem cell therapies offer enormous hope for solving some of the most tragic illnesses, diseases, and tissue defects world-wide. However, a significant barrier to the effective implementation of cell therapies is the inability to target a large quantity of viable cells with high efficiency to tissues of interest. Systemic infusion is desired as it minimizes the invasiveness of cell therapy, and maximizes practical aspects of repeated doses. However, cell types such as mesenchymal stem cells exhibit a poor homing capability or lose their capacity to home following culture expansion (i.e. FASEB J 21:3197-3207, 2007; Circulation 108:863-868, 2003; Stroke: A Journal of Cerebral Circulation 32:1005-1011; Blood 104:3581-3587, 2004). To address this challenge, we have developed a simple platform technology to chemically attach cell adhesion molecules to the cell surface to improve the homing efficiency to specific tissues. This chemical approach involves a stepwise process including (1) treatment of cells with sulfonated biotinyl-N-hydroxy-succinimide to introduce biotin groups on the cell surface, (2) addition of streptavidin that binds to the biotin on the cell surface and presents unoccupied binding sites, and (3) attachment of biotinylated targeting ligands that promote adhesive interactions with vascular endothelium. Specifically, in our model system, a biotinylated cell rolling ligand, sialyl Lewisx (SLeX), found on the surface of leukocytes (i.e., the active site of the P-selectin glycoprotein ligand (PSGL-1)), is conjugated on MSC surface. The SLeX engineered MSCs exhibit a rolling response on a P-selectin coated substrate under shear stress conditions. This indicates that this approach can be used to potentially target P-selectin expressing endothelium in the more marrow or at sites of inflammation. Importantly, the surface modification has no adverse impact on MSCs' native phenotype including their multilineage

  20. The Plant Cell Surface

    Institute of Scientific and Technical Information of China (English)

    Anne-Mie C.Emons; Kurt V.Fagerstedt

    2010-01-01

    @@ Multicellular organization and tissue construction has evolved along essentially different lines in plants and animals. Since plants do not run away, but are anchored in the soil, their tissues are more or less firm and stiff. This strength stems from the cell walls, which encase the fragile cytoplasm, and protect it.

  1. Reaction mechanisms for on-surface synthesis of covalent nanostructures.

    Science.gov (United States)

    Björk, J

    2016-03-02

    In recent years, on-surface synthesis has become an increasingly popular strategy to form covalent nanostructures. The approach has great prospects for facilitating the manufacture of a range of fascinating materials with atomic precision. However, the on-surface reactions are enigmatic to control, currently restricting its bright perspectives and there is a great need to explore how the reactions are governed. The objective of this topical review is to summarize theoretical work that has focused on comprehending on-surface synthesis protocols through studies of reaction mechanisms.

  2. Regulated Hyaluronan Synthesis by Vascular Cells

    Directory of Open Access Journals (Sweden)

    Manuela Viola

    2015-01-01

    Full Text Available Cellular microenvironment plays a critical role in several pathologies including atherosclerosis. Hyaluronan (HA content often reflects the progression of this disease in promoting vessel thickening and cell migration. HA synthesis is regulated by several factors, including the phosphorylation of HA synthase 2 (HAS2 and other covalent modifications including ubiquitination and O-GlcNAcylation. Substrate availability is important in HA synthesis control. Specific drugs reducing the UDP precursors are able to reduce HA synthesis whereas the hexosamine biosynthetic pathway (HBP increases the concentration of HA precursor UDP-N-acetylglucosamine (UDP-GlcNAc leading to an increase of HA synthesis. The flux through the HBP in the regulation of HA biosynthesis in human aortic vascular smooth muscle cells (VSMCs was reported as a critical aspect. In fact, inhibiting O-GlcNAcylation reduced HA production whereas increased O-GlcNAcylation augmented HA secretion. Additionally, O-GlcNAcylation regulates HAS2 gene expression resulting in accumulation of its mRNA after induction of O-GlcNAcylation with glucosamine treatments. The oxidized LDLs, the most common molecules related to atherosclerosis outcome and progression, are also able to induce a strong HA synthesis when they are in contact with vascular cells. In this review, we present recent described mechanisms involved in HA synthesis regulation and their role in atherosclerosis outcome and development.

  3. Note: Continuous synthesis of uniform vertical graphene on cylindrical surfaces.

    Science.gov (United States)

    Bo, Zheng; Cui, Shumao; Yu, Kehan; Lu, Ganhua; Mao, Shun; Chen, Junhong

    2011-08-01

    This note describes a new reactor design for continuous synthesis of vertically oriented graphene (VG) sheets on cylindrical wire substrates using an atmospheric plasma-enhanced chemical vapor deposition (PECVD) system. Through combining a U-shaped reactor design with "dynamic mode" synthesis featuring simultaneous rotational and axial movements of the metallic wire substrate, the new setup can enable continuous synthesis of VG sheets on the wire surface with remarkable uniformity in both circumferential and axial directions. In contrast, synthesis of VG at "static mode" with a fixed substrate can only lead to non-uniform growth of VG sheets on the wire surface. Potential applications of the resulting uniform-VG-coated metallic wire could include field emitters, field-ionization-based neutral atom detectors, and indoor corona discharges.

  4. Modeling mass transfer in solid oxide fuel cell anode: II. H2/CO co-oxidation and surface diffusion in synthesis-gas operation

    Science.gov (United States)

    Bao, Cheng; Jiang, Zeyi; Zhang, Xinxin

    2016-08-01

    Following the previous work on comparing performance of Fickian, Stefan-Maxwell and dusty-gas model for mass transfer in single fuel system, this article is focused on the electrochemistry and transport in the anode of solid oxide fuel cell using H2sbnd H2Osbnd COsbnd CO2sbnd N2 hybrid fuel. Under the standard framework of the dusty-gas model combined with the Butler-Volmer equation, it carries out a macroscopic area-specific modeling work. More specifically, two variables of hydrogen current fraction and enhancement factor are well defined and solved for the electrochemical co-oxidation of H2 and CO, and the diffusion equivalent circuit model is introduced to describe more comprehensively the resistance of mass transfer including molecular/Knudsen diffusion and surface diffusion. The model has been validated well in full region of Vsbnd I performance of an experimental anode-supported button cell. An approximate analytical solution of the hydrogen current fraction is also presented for explicit computation. Comparison between the results by different approaches for the effective diffusivity shows the importance of right mass-transfer modeling.

  5. Cell surface engineering of yeast for applications in white biotechnology.

    Science.gov (United States)

    Kuroda, Kouichi; Ueda, Mitsuyoshi

    2011-01-01

    Cell surface engineering is a promising strategy for the molecular breeding of whole-cell biocatalysts. By using this strategy, yeasts can be constructed by the cell surface display of functional proteins; these yeasts are referred to as arming yeasts. Because reactions using arming yeasts as whole-cell biocatalysts occur on the cell surface, materials that cannot enter the cell can be used as reaction substrates. Numerous arming yeasts have therefore been constructed for a wide range of uses such as biofuel production, synthesis of valuable chemicals, adsorption or degradation of environmental pollutants, recovery of rare metal ions, and biosensors. Here, we review the science of yeast cell surface modification as well as current applications and future opportunities.

  6. Synthesis and surface modification of semiconductor nanocrystals

    OpenAIRE

    Xie, Renguo

    2006-01-01

    The last decade has witnessed an exponential growth of activities in the field of nanoscience and nanotechnology worldwide, driven both by the excitement of understanding new science and by the potential hope for applications and economic impacts. The largest activity in this field up to date has been in the synthesis and characterization of new materials consisting of particles with dimensions in the order of a few nanometers, so-called nanocrystalline materials. [1-8] Semiconductor nanomate...

  7. Surface borehole synthesis tension deformation fracture time-space rule

    Institute of Scientific and Technical Information of China (English)

    Liu Jianzhong; Sun Haitao; Hu Qianting

    2012-01-01

    In order to release the tension and shear effect of the superjacent rock strata movement during excavation in coal mine,protect the surface borehole case from fracturing fast and make a good use of the surface borehole during goaf methane drawing,a common synthesis tension deformation fracture model was set up based on the synthesis tension effect of the rock strata,and the deformation rule of the surface borehole case with time and space was researched.The results suggest that,to reduce the deformation the surface borehole should be built between the boundary of the stope and the knee of subsidence curve.At the same time,a 3DEC simulation model and an engineering example were carried out to examine the rules of theoretical model.The result suggests that the model and the rules accord to the test and have good building and protection engineering application values to the surface borehole.

  8. Method of Direct Texture Synthesis on Arbitrary Surfaces

    Institute of Scientific and Technical Information of China (English)

    Fu-Li Wu; Chun-Hui Mei; Jiao-Ying Shi

    2004-01-01

    A direct texture synthesis method on arbitrary surfaces is proposed in this paper. The idea is to recursively map triangles on surface to texture space until the surface is completely mapped. First, the surface is simplified and a tangential vector field is created over the simplified mesh. Then, mapping process searches for the most optimal texture coordinates in texture sample for each triangle, and the textures of neighboring triangles are blended on the mesh. All synthesized texture triangles are compressed to an atlas. Finally, the simplified mesh is subdivided to approach the initial surface. The algorithm has several advantages over former methods:it synthesizes texture on surface without local parameterization; it does not need partitioning surface to patches;and it does not need a particular texture sample. The results demonstrate that the new algorithm is applicable to a wide variety of texture samples and any triangulated surfaces.

  9. Synthesis, Characterization, and Surface Initiated Polymerization of Carbazole Functionalized Isocyanides

    NARCIS (Netherlands)

    Schwartz, Erik; Lim, Eunhee; Gowda, Chandrakala M.; Liscio, Andrea; Fenwick, Oliver; Tu, Guoli; Palermo, Vincenzo; Gelder, de Rene; Cornelissen, Jeroen J.L.M.; Eck, van Ernst R.H.; Kentgens, Arno P.M.; Cacialli, Franco; Nolte, Roeland J.M.; Samori, Paolo; Huck, Wilhelm T.S.; Rowan, Alan E.

    2010-01-01

    We describe the design and synthesis of carbazole functionalized isocyanides and the detailed investigation of their properties. Characterization by solid state NMR, CD, and IR spectroscopic techniques reveals that the polymer has a well-defined helical architecture. Surface-initiated polymerization

  10. CZTSSe thin film solar cells: Surface treatments

    Science.gov (United States)

    Joglekar, Chinmay Sunil

    Chalcopyrite semiconducting materials, specifically CZTS, are a promising alternative to traditional silicon solar cell technology. Because of the high absorption coefficient; films of the order of 1 micrometer thickness are sufficient for the fabrication of solar cells. Liquid based synthesis methods are advantageous because they are easily scalable using the roll to roll manufacturing techniques. Various treatments are explored in this study to enhance the performance of the selenized CZTS film based solar cells. Thiourea can be used as a sulfur source and can be used to tune band gap of CZTSSe. Bromine etching can be used to manipulate the thickness of sintered CZTSSe film. The etching treatment creates recombination centers which lead to poor device performance. Various after treatments were used to improve the performance of the devices. It was observed that the performance of the solar cell devices could not be improved by any of the after treatment steps. Other surface treatment processes are explored including KCN etching and gaseous H2S treatments. Hybrid solar cells which included use of CIGS nanoparticles at the interface between CZTSSe and CdS are also explored.

  11. New Synthesis of Pt-Ru Nanoparticles on Surface Modified Carbon Vulcane XC-72 as an Effective Catalyst for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Ahmad; Nozad; Golikand; Sajjad; Sadaghat; Sharehjini; Mohammad; Yari

    2007-01-01

    1 Results Pt-Ru nanoparticles are synthesised on the surface oxidized carbon Vulcane XC-72 as catalyst support by chemically anchoring Pt and Ru onto the surface of modified carbon vulcane XC-72 (by refluxing in 70% HNO3 at 120 ℃ for 12 h to introduce surface functional groups) .The nanoparticles of Pt and Ru are synthesized by reduction of H2PtCl6 and K4Ru(CN)6 with sodium borohydride in a 5.5 buffer solution of sodium citrate,the complexation of citrate with metal ions is beneficial to the formati...

  12. Synthesis and surface properties of fluorinated polyurethanes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H.J. [Kongju National University, Kongju (Korea)

    2001-01-01

    Fluorinated polyurethane elastomers were synthesized by two step polyaddition of a perfluorinated polyether diol (trade name of Fomblin ZDOL{sup R}) and diisocyanates such as 4,4' -diphenyl methane diisocyanate (MDI) and toluene 2,4-diisocyanate (TDI). In order to control the Fomblin moiety of the soft segment in the synthesized elastomers to 10{approx}50%, polyether type polyols such as polypropylene glycol (PPG) and polytetramethylene glycol (PTMG) were mixed during the Polymerization reaction. Ethylene diamine or 1,4-butane diol was used as chain extenders. The structure and average molecular weight of the produced polyurethanes were confirmed by using FT-IR, 'H-NMR, DSC, and GPC. The surface properties were analyzed by using X-ray photoelectron spectroscopy (XPS) and contact angle meter. From the results of the surface analysis it was concluded that the fluorine groups were localized on the surface rather than the inside of the polyurethane films. (author). 10 refs., 5 tabs., 8 figs.

  13. Haematopoietic stem cells require a highly regulated protein synthesis rate.

    Science.gov (United States)

    Signer, Robert A J; Magee, Jeffrey A; Salic, Adrian; Morrison, Sean J

    2014-05-01

    Many aspects of cellular physiology remain unstudied in somatic stem cells, for example, there are almost no data on protein synthesis in any somatic stem cell. Here we set out to compare protein synthesis in haematopoietic stem cells (HSCs) and restricted haematopoietic progenitors. We found that the amount of protein synthesized per hour in HSCs in vivo was lower than in most other haematopoietic cells, even if we controlled for differences in cell cycle status or forced HSCs to undergo self-renewing divisions. Reduced ribosome function in Rpl24(Bst/+) mice further reduced protein synthesis in HSCs and impaired HSC function. Pten deletion increased protein synthesis in HSCs but also reduced HSC function. Rpl24(Bst/+) cell-autonomously rescued the effects of Pten deletion in HSCs; blocking the increase in protein synthesis, restoring HSC function, and delaying leukaemogenesis. Pten deficiency thus depletes HSCs and promotes leukaemia partly by increasing protein synthesis. Either increased or decreased protein synthesis impairs HSC function.

  14. Ammonia synthesis on Au modified Fe(111) and Ag and Cu modified Fe(100) surfaces

    DEFF Research Database (Denmark)

    Lytken, Ole; Waltenburg, Hanne Neergaard; Chorkendorff, Ib

    2003-01-01

    In order to investigate any influence of steps and possible positive effects of making surface alloys the ammonia synthesis has been investigated over Au modified Fe(111) and Ag and Cu modified Fe(100) single crystals in the temperature range 603-773 K, using a system combining ultra-high vacuum...... and a high-pressure cell. Ammonia was synthesized from a stoichiometric (N-2:3H(2)) gas mixture at a pressure of 2 bar. By deposition of small amounts of An, the ammonia production activity of the Fe(1 1 1) surface can be enhanced. More important, for the gold modified surface, the reaction order in ammonia...

  15. Straightforward and robust synthesis of monodisperse surface-functionalized gold nanoclusters

    Directory of Open Access Journals (Sweden)

    Silvia Varela-Aramburu

    2016-09-01

    Full Text Available Gold nanoclusters are small (1–3 nm nanoparticles with a high surface area that are useful for biomedical studies and drug delivery. The synthesis of small, surface-functionalized gold nanoclusters is greatly dependent on the reaction conditions. Here, we describe a straightforward, efficient and robust room temperature one-pot synthesis of 2 nm gold nanoclusters using thioglucose as a reducing and stabilizing agent, which was discovered by serendipity. The resultant monodisperse gold nanoclusters are more stable than those generated using some other common methods. The carboxylic acid contained in the stabilizing agent on the cluster surface serves as anchor for nanocluster functionalization. Alternatively, the addition of thiols serves to functionalize the nanoclusters. The resulting non-cytotoxic nanoclusters are taken up by cells and constitute a tuneable platform for biomedical applications including drug delivery.

  16. Straightforward and robust synthesis of monodisperse surface-functionalized gold nanoclusters

    Science.gov (United States)

    Varela-Aramburu, Silvia; Wirth, Richard; Lai, Chian-Hui; Orts-Gil, Guillermo

    2016-01-01

    Summary Gold nanoclusters are small (1–3 nm) nanoparticles with a high surface area that are useful for biomedical studies and drug delivery. The synthesis of small, surface-functionalized gold nanoclusters is greatly dependent on the reaction conditions. Here, we describe a straightforward, efficient and robust room temperature one-pot synthesis of 2 nm gold nanoclusters using thioglucose as a reducing and stabilizing agent, which was discovered by serendipity. The resultant monodisperse gold nanoclusters are more stable than those generated using some other common methods. The carboxylic acid contained in the stabilizing agent on the cluster surface serves as anchor for nanocluster functionalization. Alternatively, the addition of thiols serves to functionalize the nanoclusters. The resulting non-cytotoxic nanoclusters are taken up by cells and constitute a tuneable platform for biomedical applications including drug delivery. PMID:27826501

  17. Analysis of cell surface antigens by Surface Plasmon Resonance imaging

    NARCIS (Netherlands)

    Stojanovic, I.; Schasfoort, R.B.M.; Terstappen, L.W.M.M.

    2013-01-01

    Surface Plasmon Resonance (SPR) is most commonly used to measure bio-molecular interactions. SPR is used significantly less frequent for measuring whole cell interactions. Here we introduce a method to measure whole cells label free using the specific binding of cell surface antigens expressed on th

  18. Analysis of cell surface antigens by Surface Plasmon Resonance imaging

    NARCIS (Netherlands)

    Stojanovic, Ivan; Schasfoort, Richardus B.M.; Terstappen, Leonardus Wendelinus Mathias Marie

    2013-01-01

    Surface Plasmon Resonance (SPR) is most commonly used to measure bio-molecular interactions. SPR is used significantly less frequent for measuring whole cell interactions. Here we introduce a method to measure whole cells label free using the specific binding of cell surface antigens expressed on th

  19. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    Directory of Open Access Journals (Sweden)

    He Quanguo

    2008-01-01

    Full Text Available Abstract Surface functionalized magnetic iron oxide nanoparticles (NPs are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed.

  20. Gold-Organic Hybrids: On-Surface Synthesis and Perspectives.

    Science.gov (United States)

    Zhang, Haiming; Chi, Lifeng

    2016-12-01

    Gold-organic hybrids can be prepared on gold substrates by on-surface dehalogenation of molecular precursors with multiple halogen substituents. Various contact geometries of covalent arylAu bonds are achieved by changing the halogen substituents in the bay or peri regions. Scanning tunneling microscopy/spectroscopy (STM/STS) investigations allow a better understanding of the structure/property relationships in various gold-aryl contacts. Recent progress on the synthesis, large-scale alignment, and STS measurement of gold-organic hybrids is described, ending with an emphasis on potential future applications, e.g., as precursors (intermediates) for the synthesis of graphene nanoribbons (GNRs) on insulating surfaces, and as a model system to investigate the role of covalent arylAu bonds in electron transport through gold-GNR contacts. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Synthesis and Electrochemical Studies on LiCoVO_4 Surface Modified with La_2O_3 for Lithium-ion Cells

    Institute of Scientific and Technical Information of China (English)

    George; Ting-Kuo; FEY; P.Muralidharan; Yung-da; CHO

    2007-01-01

    1 Results An inverse spinel LiCoVO4 cathode material was synthesized by a citric acid-urea polymeric method, calcined at 773 K for 5 h. The synthesized LiCoVO4 sample was surface modified with various wt.% of La2O3 by a polymeric process, calcined at 873 K for 2 h. The samples were characterized by XRD, FTIR, SEM, and TEM techniques. XRD patterns exposed that single-phase crystallinity occurred when they were heated at 773 K for 5 h in air. For the La2O3 coated samples, there was no evident signal corre...

  2. Surfaces, scales, and synthesis: Scientific reasoning at the nanoscale

    Science.gov (United States)

    Bursten, Julia R.

    Philosophers interested in scientific methodology have focused largely on physics, biology, and cognitive science. They have paid considerably less attention to sciences such as chemistry and nanoscience, where not only are the subjects distinct, but the very aims differ: chemistry and nanoscience center around synthesis. Methods associated with synthesis do not fit well with description, explanation, and prediction that so dominate aims in philosophers paradigm sciences. In order to synthesize a substance or material, scientists need different kinds of information than they need to predict, explain, or describe. Consequently, they need different kinds of models and theories. Specifically, chemists need additional models of how reactions will proceed. In practice, this means chemists must model surface structure and behavior, because reactions occur on the surfaces of materials. Physics, and by extension much of philosophy of science, ignores the structure and behavior of surfaces, modeling surfaces only as boundary conditions with virtually no influence on material behavior. Such boundary conditions are not seen as part of the physical laws that govern material behavior, so little consideration has been given to their roles in improving scientists understanding of materials and aiding synthesis. But especially for theories that are used in synthesis, such neglect can lead to catastrophic modeling failures. In fact, as one moves down toward the nanoscale, the very concept of a material surface changes, with the consequence that nanomaterials behave differently than macroscopic materials made up of the same ele-ments. They conduct electricity differently, they appear differently colored, and they can play different roles in chemical reactions. This dissertation develops new philosophical tools to deal with these changes and give an account of theory and model use in the synthetic sciences. Particularly, it addresses the question of how models of materials at the

  3. High Surface Area Ceria Nanoparticles via Hydrothermal Synthesis Experiment Design

    Directory of Open Access Journals (Sweden)

    Stanislav Kurajica

    2016-01-01

    Full Text Available Hydrothermal synthesis of CeO2 was optimized on two reactant concentrations and synthesis temperature and duration, in order to achieve material having the greatest specific surface area (SSA. Taguchi method of experimental design was employed in evaluation of the relative importance of synthesis parameters. CeO2 nanoparticles were characterized using X-ray diffraction, nitrogen adsorption-desorption isotherms, and scanning electron microscopy. Optimum conditions for obtaining particles with greater SSA were calculated according to Taguchi’s model “the-higher-the-better.” Synthesis temperature was found to be the only parameter significant for enabling nanoparticles with greater SSA. Mesoporous nanocrystalline ceria with SSA as great as 226 m2 g−1 was achieved, which is unprecedented for the hydrothermally synthesized ceria. The reason for this achievement was found in temperature dependence of the diffusion coefficient which, when low, favors nucleation yielding with fine particles, while when high it favors crystal growth and formation of one-dimensional structures. The occurrence of 1D-structure in sample exhibiting the smallest SSA was confirmed. Very fine crystallites with crystallite size as low as 5.9 nm have been obtained being roughly inverse proportional to SSA. Selected samples were tested as catalyst for soot oxidation. Catalyst morphology turned out to be decisive factor for catalytic activity.

  4. Recent Insights into Cell Surface Heparan Sulphate Proteoglycans and Cancer

    DEFF Research Database (Denmark)

    Couchman, John R; Multhaupt, Hinke; Sanderson, Ralph D

    2016-01-01

    behaviour. Here, we review some recent advances, emphasising that many tumour-related functions of proteoglycans are revealed only after their modification in processes subsequent to synthesis and export to the cell surface. These include enzymes that modify heparan sulphate structure, recycling of whole...... or fragmented proteoglycans into exosomes that can be paracrine effectors or biomarkers, and lateral interactions between some proteoglycans and calcium channels that impact the actin cytoskeleton....

  5. Nanometer polymer surface features: the influence on surface energy, protein adsorption and endothelial cell adhesion

    Science.gov (United States)

    Carpenter, Joseph; Khang, Dongwoo; Webster, Thomas J.

    2008-12-01

    Current small diameter (require an eight-week in vitro culture period prior to implantation—too long for immediate clinical bedside applications. Previous in vitro studies have shown that nanostructured poly(lactic-co-glycolic acid) (PLGA) surfaces elevated endothelial cell adhesion, proliferation, and extracellular matrix synthesis when compared to nanosmooth surfaces. Nonetheless, these studies failed to address the importance of lateral and vertical surface feature dimensionality coupled with surface free energy; nor did such studies elicit an optimum specific surface feature size for promoting endothelial cell adhesion. In this study, a series of highly ordered nanometer to submicron structured PLGA surfaces of identical chemistry were created using a technique employing polystyrene nanobeads and poly(dimethylsiloxane) (PDMS) molds. Results demonstrated increased endothelial cell adhesion on PLGA surfaces with vertical surface features of size less than 18.87 nm but greater than 0 nm due to increased surface energy and subsequently protein (fibronectin and collagen type IV) adsorption. Furthermore, this study provided evidence that the vertical dimension of nanometer surface features, rather than the lateral dimension, is largely responsible for these increases. In this manner, this study provides key design parameters that may promote vascular graft efficacy.

  6. Cell surface carbohydrates as prognostic markers in human carcinomas

    DEFF Research Database (Denmark)

    Dabelsteen, Erik

    1996-01-01

    Tumour development is usually associated with changes in cell surface carbohydrates. These are often divided into changes related to terminal carbohydrate structures, which include incomplete synthesis and modification of normally existing carbohydrates, and changes in the carbohydrate core...... structure. The latter includes chain elongation of both glycolipids and proteins, increased branching of carbohydrates in N-linked glycoproteins, and blocked synthesis of carbohydrates in O-linked mucin-like glycoproteins. In mature organisms, expression of distinct carbohydrates is restricted to specific...... cell types; within a given tissue, variation in expression may be related to cell maturation. Tumour-associated carbohydrate structures often reflect a certain stage of cellular development; most of these moieties are structures normally found in other adult or embryonic tissues. There is no unique...

  7. On-Surface Synthesis of Sandwich Molecular Nanowires on Graphene.

    Science.gov (United States)

    Huttmann, Felix; Schleheck, Nicolas; Atodiresei, Nicolae; Michely, Thomas

    2017-07-26

    We demonstrate a new synthesis route for the growth of organometallic sandwich molecular nanowires, taking the example of Eu-cyclooctatetraene (EuCot), a predicted ferromagnetic semiconductor. We employ simultaneous exposure of Cot molecules and Eu vapor in ultrahigh vacuum to an inert substrate, such as graphene. Using a Cot excess under temperature conditions of a finite residence time of the molecule, the reactand diffusion confined to two dimensions results in a clean product of ultralong wires. In situ scanning tunneling microscopy reveals not only their molecular structure but also a rich and intriguing growth morphology. The new on-surface synthesis permits experimental access to a largely unexplored class of one-dimensional organometallic systems with potential for exciting electronic and magnetic properties.

  8. Metastasis-associated cell surface oncoproteomics

    Directory of Open Access Journals (Sweden)

    Piia-Riitta eKarhemo

    2012-11-01

    Full Text Available Oncoproteomics aims to the discovery of molecular markers, drug targets and pathways by studying cancer specific protein expression, localization, modification and interaction. Cell surface proteins play a central role in several pathological conditions, including cancer and its metastatic spread. However, cell surface proteins are underrepresented in proteomics analyses performed from the whole cell extracts due to their hydrophobicity and low abundance. Different methods have been developed to enrich and isolate the cell surface proteins to reduce sample complexity. Despite the method selected, the primary difficulty encountered is the solubilization of the hydrophobic transmembrane proteins from the lipid bilayer. This review focuses on proteomic analyses of metastasis-associated proteins identified using the cell surface biotinylation method. Interestingly, also certain intracellular proteins were identified from the cell surface samples. The function of these proteins at the cell surface might well differ from their function inside the cell.

  9. Synthesis, characterization, and application of surface-functionalized ordered mesoporous nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Po-Wen [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    The dissertation begins with Chapter 1, which is a general introduction of the fundamental synthesis of mesoporous silica materials, the selective functionlization of mesoporous silica materials, and the synthesis of nanostructured porous materials via nanocasting. In Chapter 2, the thermo-responsive polymer coated mesoporous silica nanoparticles (MSN) was synthesized via surface-initated polymerization and exhibited unique partition activities in a biphasic solution with the thermally induced change. In Chapter 3, the monodispersed spherical MSN with different mesoporous structure (MCM-48) was developed and employed as a template for the synthesis of mesoporous carbon nanoparticles (MCN) via nanocasting. MCN was demonstrated for the delivery of membrane impermeable chemical agents inside the cells. The cellular uptake efficiency and biocompabtibility of MCN with human cervical cancer cells were also investigated. In addition to the biocompabtibility of MCN, MCN was demonstrated to support Rh-Mn nanoparticles for catalytic reaction in Chapter 4. Owing to the unique mesoporosity, Rh-Mn nanoparticles can be well distributed inside the mesoporous structure and exhibited interesting catalytic performance on CO hydrogenation. In Chapter 5, the synthesis route of the aforementioned MCM-48 MSN was discussed and investigated in details and other metal oxide nanoparticles were also developed via nanocasting by using MCM-48 MSN as a template. At last, there is a general conclusion summarized in Chapter 6.

  10. Reduced trisialoganglioside synthesis in chemically but not mos-transformed mouse epidermal cells

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, L.; Colburn, N.H.

    1984-04-01

    A specific decrease in the net de novo synthesis ((1-14C)-glucosamine incorporation) of cell surface trisialoganglioside (GT) occurs in preneoplastic mouse JB6 epidermal cells in response to tumor-promoting phorbol esters, mezerein, or epidermal growth factor, all of which promote neoplastic transformation in JB6 cells, but not in response to the bladder promoter sodium cyclamate, a nonpromoter in JB6 cells. The ganglioside showing elevated synthesis after mezerein or epidermal growth factor exposure is monosialoganglioside 1, whereas disialoganglioside 1b synthesis is elevated after phorbol ester exposure. Primary mouse epidermal cells and putatively initiated epidermal cell lines selected for their resistance to induction of terminal differentiation by high calcium are resistant to promotion of anchorage-independent transformation by 2-week exposure to 12-O-tetradecanoylphorbol-13-acetate. In both cell types, little or no decrease in GT synthesis occurs in response to short-term 12-O-tetradecanoylphorbol-13-acetate exposure, thus extending further our previous observation that this GT response is restricted to promotable cells. A decreased synthesis of GT also occurs consistently in cell lines transformed by 12-O-tetradecanoylphorbol-13-acetate or N-methyl-N-nitro-nitrosoguanidine as compared with their nontransformed counterparts but not in cell lines transformed by a cloned integrated murine sarcoma provirus containing the oncogenic sequence v-mos. Thus, reduced cell surface GT synthesis may be important both in the induction and in the maintenance of the chemically transformed but not viral oncogene mos-transformed phenotype in mouse epidermal cells.

  11. Microbial cell surfaces and secretion systems

    NARCIS (Netherlands)

    Tommassen, J.P.M.; Wosten, H.A.B.

    2015-01-01

    Microbial cell surfaces, surface-exposed organelles, and secreted proteins are important for the interaction with the environment, including adhesion to hosts, protection against host defense mechanisms, nutrient acquisition, and intermicrobial competition. Here, we describe the structures of the ce

  12. Cell-surface hydrophobicity of Staphylococcus saprophyticus.

    Science.gov (United States)

    Schneider, P. F.; Riley, T. V.

    1991-01-01

    The cell-surface hydrophobicity of 100 urinary isolates of Staphylococcus saprophyticus, cultured from symptomatic females in the general population, was assessed using a two-phase aqueous:hydrocarbon system. Relatively strong cell-surface hydrophobicity was exhibited by 79 isolates using the criteria employed, while only 2 of the remaining 21 isolates failed to demonstrate any detectable hydrophobicity. Cell-surface hydrophobicity may be a virulence factor of S. saprophyticus, important in adherence of the organism to uroepithelia. Additionally, the data support the concept that cell-surface hydrophobicity may be a useful predictor of clinical significance of coagulase-negative staphylococci isolated from clinical sources. PMID:1993454

  13. Cell attachment on ion implanted titanium surface

    Directory of Open Access Journals (Sweden)

    P.S. Sreejith

    2008-12-01

    Full Text Available Purpose: Of outmost importance for the successful use of an implant is a good adhesion of the surrounding tissue to the biomaterial. In addition to the surface composition of the implant, the surface topography also influences the properties of the adherent cells. In the present investigation, ion implanted and untreated surfaces were compared for cell adhesion and spreading.Design/methodology/approach: The surface topography of the surfaces were analyzed using AFM and the cell studies with SEM.Findings: The results of our present investigation is indicative of the fact that ion implanted titanium surface offer better cell binding affinity compared to untreated/polished surface.Practical implications: Success of non-biodegradable implants will first and foremost depend on biocompatibility, followed by the capacity of the surface topography of the implants to evince desired cell matrix, surface cell matrix interactions. In the present study, the cell growth on ion implanted Ti material is analyzed and discussed.Originality/value: In this paper, we have utilized ion implantation technique, which will produce nano-texturing of the surface without producing any detrimental effects to both the dimensions and properties of the implants.

  14. Phospholipid Synthesis in Sindbis Virus-Infected Cells

    Science.gov (United States)

    Waite, Marilynn R. F.; Pfefferkorn, E. R.

    1970-01-01

    We investigated the metabolic requirements for the decrease in phospholipid synthesis previously observed by Pfefferkorn and Hunter in primary cultures of chick embryo fibroblasts infected with Sindbis virus. The incorporation of 32PO4 into all classes of phospholipids was found to decline at the same rate and to the same extent; thus, incorporation of 14C-choline into acid-precipitable form provided a convenient measure of phospholipid synthesis that was used in subsequent experiments. Experiments with temperature-sensitive mutants suggested that some viral ribonucleic acid (RNA) synthesis was essential for the inhibition of choline incorporation, but that functional viral structural proteins were not required. The reduction in phospholipid synthesis was probably a secondary effect of infection resulting from viral inhibition of the cellular RNA and protein synthesis. All three inhibitory effects required about the same amount of viral RNA synthesis; the inhibition of host RNA and protein synthesis began sooner than the decline in phospholipid synthesis; and both actinomycin D and cycloheximide inhibited 14C-choline incorporation in uninfected cells. In contrast, incorporation of 14C-choline into BHK-21 cells was not decreased by 10 hr of exposure to actinomycin D and declined only slowly after cycloheximide treatment. Growth of Sindbis virus in BHK cells did not cause the marked stimulation of phospholipid synthesis seen in picornavirus infections of other mammalian cells; however, inhibition was seen only late in infection. PMID:5530011

  15. Magnetization of individual yeast cells by in situ formation of iron oxide on cell surfaces

    Science.gov (United States)

    Choi, Jinsu; Lee, Hojae; Choi, Insung S.; Yang, Sung Ho

    2017-09-01

    Magnetic functionalization of living cells has intensively been investigated with the aim of various bioapplications such as selective separation, targeting, and localization of the cells by using an external magnetic field. However, the magnetism has not been introduced to individual living cells through the in situ chemical reactions because of harsh conditions required for synthesis of magnetic materials. In this work, magnetic iron oxide was formed on the surface of living cells by optimizing reactions conditions to be mild sufficiently enough to sustain cell viability. Specifically, the reactive LbL strategy led to formation of magnetically responsive yeast cells with iron oxide shells. This facile and direct post-magnetization method would be a useful tool for remote manipulation of living cells with magnetic interactions, which is an important technique for the integration of cell-based circuits and the isolation of cell in microfluidic devices.

  16. Yeast cell surface display for lipase whole cell catalyst and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yun; Zhang, Rui; Lian, Zhongshuai; Wang, Shihui; Wright, Aaron T.

    2014-08-01

    The cell surface display technique allows for the expression of target proteins or peptides on the microbial cell surface by fusing an appropriate protein as an anchoring motif. Yeast display systems, such as Pichia pastoris, Yarowia lipolytica and Saccharomyces cerevisiae, are ideal, alternative and extensive display systems with the advantage of simple genetic manipulation and post-translational modification of expressed heterologous proteins. Engineered yeasts show high performance characteristics and variant utilizations. Herein, we comprehensively summarize the variant factors affecting lipase whole cell catalyst activity and display efficiency, including the structure and size of target proteins, screening anchor proteins, type and chain length of linkers, and the appropriate matching rules among the above-mentioned display units. Furthermore, we also address novel approaches to enhance stability and activity of recombinant lipases, such as VHb gene co-expression, multi-enzyme co-display technique, and the micro-environmental interference and self-assembly techniques. Finally, we represent the variety of applications of whole cell surface displayed lipases on yeast cells in non-aqueous phases, including synthesis of esters, PUFA enrichment, resolution of chiral drugs, organic synthesis and biofuels. We demonstrate that the lipase surface display technique is a powerful tool for functionalizing yeasts to serve as whole cell catalysts, and increasing interest is providing an impetus for broad application of this technique.

  17. Towards synthesis of a minimal cell.

    Science.gov (United States)

    Forster, Anthony C; Church, George M

    2006-01-01

    Construction of a chemical system capable of replication and evolution, fed only by small molecule nutrients, is now conceivable. This could be achieved by stepwise integration of decades of work on the reconstitution of DNA, RNA and protein syntheses from pure components. Such a minimal cell project would initially define the components sufficient for each subsystem, allow detailed kinetic analyses and lead to improved in vitro methods for synthesis of biopolymers, therapeutics and biosensors. Completion would yield a functionally and structurally understood self-replicating biosystem. Safety concerns for synthetic life will be alleviated by extreme dependence on elaborate laboratory reagents and conditions for viability. Our proposed minimal genome is 113 kbp long and contains 151 genes. We detail building blocks already in place and major hurdles to overcome for completion.

  18. Functions of proteoglycans at the cell surface

    DEFF Research Database (Denmark)

    Höök, M; Woods, A; Johansson, S;

    1986-01-01

    Proteoglycans (primarily heparan sulphate proteoglycans) are found at the surface of most adherent eukaryotic cells. Earlier studies suggest that these molecules can be associated with the cell surface principally by two different mechanisms. Proteoglycans may occur as membrane......-intercalated glycoproteins, where the core protein of the proteoglycan is anchored in the lipid interior of the plasma membrane, or they may be bound via the polysaccharide components of the molecule to specific anchoring proteins present at the cell surface. A number of functions have been proposed for cell surface......-associated proteoglycans, including: regulation of cell-substrate adhesion; regulation of cell proliferation; participation in the binding and uptake of extracellular components; and participation in the regulation of extracellular matrix formation. Evidence is discussed suggesting that the cell-associated heparan...

  19. Controlled surface chemistries and quantitative cell response

    Science.gov (United States)

    Plant, Anne L.

    2002-03-01

    Living cells experience a large number of signaling cues from their extracellular matrix. As a result of these inputs, a variety of intracellular signaling pathways are apparently initiated simultaneously. The vast array of alternative responses that result from the integration of these inputs suggests that it may be reasonable to look for cellular response not as an 'on' or 'off' condition but as a distribution of responses. A difficult challenge is to determine whether variations in responses from individual cells arise from the complexity of intracellular signals or are due to variations in the cell culture environment. By controlling surface chemistry so that every cell 'sees' the same chemical and physical environment, we can begin to assess how the distribution of cell response is affected strictly by changes in the chemistry of the cell culture surface. Using the gene for green fluorescent protein linked to the gene for the promoter of the extracellular matrix protein, tenascin, we can easily probe the end product in a signaling pathway that is purported to be linked to surface protein chemistry and to cell shape. Cell response to well-controlled, well-characterized, and highly reproducible surfaces prepared using soft lithography techniques are compared with more conventional ways of preparing extracellular matrix proteins for cell culture. Using fluorescence microscopy and image analysis of populations of cells on these surfaces, we probe quantitatively the relationship between surface chemistry, cell shape and variations in gene expression endpoint.

  20. The cell surface of Trypanosoma cruzi

    Directory of Open Access Journals (Sweden)

    Wanderley de Souza

    1984-01-01

    Full Text Available The cell surface of trypanosomatids is formed by the plasma membrane and a layer of sub-pellicular microtubules which are connected to the plasma membrane. The plasma membrane is composed by proteins, lipids and carbohydrates which form the glycocalix. In this paper we will review briefly aspects related to the organization of the cell surface of Trypanosoma cruzi.

  1. Facile synthesis of high surface area molybdenum nitride and carbide

    Science.gov (United States)

    Roy, Aaron; Serov, Alexey; Artyushkova, Kateryna; Brosha, Eric L.; Atanassov, Plamen; Ward, Tim L.

    2015-08-01

    The synthesis of high surface area γ-Mo2N and α-Mo2C is reported (116 and 120 m2/g) without the temperature programmed reduction of MoO3. γ-Mo2N was prepared in an NH3-free synthesis using forming gas (7 at% H2, N2-balance) as the reactive atmosphere. Three precursors were studied ((NH4)6Mo7O24·4H2O, (NH4)2 Mg(MoO4)2, and MgMoO4) along with the sacrificial support method (SSM) as a means of reducing the particle size of Mo2N and Mo2C. In situ X-ray diffraction (XRD) studies were carried out to identify reaction intermediates, the temperature at which various intermediates form, and the average domain size of the Mo2N products. Materials were synthesized in bulk and further characterized by XRD, HRTEM, XPS, and BET.

  2. Regulation of cholesterol synthesis in four colonic adenocarcinoma cell lines.

    Science.gov (United States)

    Cerda, S R; Wilkinson, J; Broitman, S A

    1995-12-01

    Colon tumor cells, unlike normal human fibroblasts, exhibited an uncoupling of low density lipoprotein (LDL)-derived cholesterol from cellular growth, when endogenous cholesterol synthesis was inhibited by mevinolin, a hydroxymethylglutaryl-CoA reductase (HMG-CoAR) competitive inhibitor [Fabricant, M., and Broitman, S.A. (1990) Cancer Res. 50, 632-636]. Further evaluation of cholesterol metabolism was conducted in two undifferentiated (SW480, SW1417) and two differentiated (HT29, CACO2) colonic adenocarcinoma (adeno-CA) cell lines and an untransformed human fibroblast, AG1519A. Cells grown in monolayer culture to near subconfluency were used to assess endogenous cholesterol synthesis by 14C-acetate incorporation, in response to the following treatments in lipoprotein-deficient serum (LPDS)-supplemented minimum essential medium (MEM): LPDS alone, LDL, mevinolin, mevinolin with LDL, and 25-hydroxy-cholesterol (25-OH-CH). Complete fetal bovine serum (FBS)-supplemented MEM was used as control. All colon tumor lines exhibited similarly high endogenous cholesterol synthesis in both FBS and LPDS relative to the fibroblasts which demonstrated low basal levels in FBS and maximal synthesis in LPDS. LDL treatment did not inhibit cholesterol synthesis in colon tumor cells, but suppressed that in the fibroblast by 70%. Sterol repression of cholesterol synthesis mediated by 25-OH-CH occurred in all cells. Mevinolin caused a reduction in cholesterol synthesis in the colonic cancer cell lines, which was not further decreased by concurrent addition of LDL. In contrast, in mevinolin-treated fibroblasts, LDL further inhibited cholesterol synthesis. When the effect of cell density on cholesterol synthesis regulation was evaluated under conditions of sparse density in SW480 and SW147, results indicated that (i) basal rates of cholesterol synthesis were higher, (ii) LDL inhibited cholesterol synthesis more effectively, and (iii) mevinolin or 25-OH-CH had a more pronounced effect than in

  3. Effect of Surface Attachment on Synthesis of Bacterial Cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Barbara R [ORNL; O' Neill, Hugh Michael [ORNL

    2005-01-01

    Gluconacetobacter spp. synthesize a pure form of hydrophilic cellulose that has several industrial specialty applications. Literature reports have concentrated on intensive investigation of static and agitated culture in liquid media containing high nutrient concentrations optimized for maximal cellulose production rates. The behavior of these bacteria on semisolid and solid surfaces has not been specifically addressed. The species Gluconacetobacter hansenii was examined for cellulose synthesis and colony morphology on a range of solid supports, including cotton linters, and on media thickened with agar, methyl cellulose, or gellan. The concentration and chemical structure of the thickening agent were found to be directly related to the formation of contiguous cellulose pellicules. Viability of the bacteria following freezer storage was improved when the bacteria were frozen in their cellulose pellicules.

  4. Facile and rapid synthesis of Pd nanodendrites for electrocatalysis and surface-enhanced Raman scattering applications

    Science.gov (United States)

    Kannan, Palanisamy; Dolinska, Joanna; Maiyalagan, Thandavarayan; Opallo, Marcin

    2014-09-01

    Numerous properties from metal nanostructures can be tuned by controlling both their size and shape. In particular, the latter is extremely important because the type of crystalline surface affects the surface electronic density. This paper describes a simple approach to the synthesis of highly-structured, anisotropic palladium nanostructured dendrites. They were obtained using an eco-friendly biomolecule 5-hydroxytryptophan, which acts as both a reducing and stabilizing agent. The growth mechanism is proposed for the evolution of dendrites morphology. It was found that the concentration of 5-hydroxytryptophan played a vital role on the morphology of the nanostructured Pd dendrites. This nanomaterial shows enhanced electrocatalytic performance towards the oxidation of formic acid, and it exhibits surface-enhanced Raman scattering properties towards the prostate specific antigen. These properties may be explored in fuel cells and biosensors, respectively.Numerous properties from metal nanostructures can be tuned by controlling both their size and shape. In particular, the latter is extremely important because the type of crystalline surface affects the surface electronic density. This paper describes a simple approach to the synthesis of highly-structured, anisotropic palladium nanostructured dendrites. They were obtained using an eco-friendly biomolecule 5-hydroxytryptophan, which acts as both a reducing and stabilizing agent. The growth mechanism is proposed for the evolution of dendrites morphology. It was found that the concentration of 5-hydroxytryptophan played a vital role on the morphology of the nanostructured Pd dendrites. This nanomaterial shows enhanced electrocatalytic performance towards the oxidation of formic acid, and it exhibits surface-enhanced Raman scattering properties towards the prostate specific antigen. These properties may be explored in fuel cells and biosensors, respectively. Electronic supplementary information (ESI) available. See DOI

  5. Cell-specific monitoring of protein synthesis in vivo.

    Directory of Open Access Journals (Sweden)

    Nikos Kourtis

    Full Text Available Analysis of general and specific protein synthesis provides important information, relevant to cellular physiology and function. However, existing methodologies, involving metabolic labelling by incorporation of radioactive amino acids into nascent polypeptides, cannot be applied to monitor protein synthesis in specific cells or tissues, in live specimens. We have developed a novel approach for monitoring protein synthesis in specific cells or tissues, in vivo. Fluorescent reporter proteins such as GFP are expressed in specific cells and tissues of interest or throughout animals using appropriate promoters. Protein synthesis rates are assessed by following fluorescence recovery after partial photobleaching of the fluorophore at targeted sites. We evaluate the method by examining protein synthesis rates in diverse cell types of live, wild type or mRNA translation-defective Caenorhabditis elegans animals. Because it is non-invasive, our approach allows monitoring of protein synthesis in single cells or tissues with intrinsically different protein synthesis rates. Furthermore, it can be readily implemented in other organisms or cell culture systems.

  6. Cell-surface remodelling during mammalian erythropoiesis.

    Science.gov (United States)

    Wraith, D C; Chesterton, C J

    1982-10-15

    Current evidence suggests that the major cell-surface modification occurring during mammalian erythropoiesis could be generated by two separate mechanisms: either selective loss of membrane proteins during enucleation or endocytosis at the subsequent reticulocyte and erythrocyte stages. The former idea was tested by collecting developing rabbit erythroid cells before and after the enucleation step and comparing their cell-surface protein composition via radiolabelling and electrophoresis. Few changes were observed. Our data thus lend support to the endocytosis mechanism.

  7. Cell behaviour on chemically microstructured surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Magnani, Agnese; Priamo, Alfredo; Pasqui, Daniela; Barbucci, Rolando

    2003-03-03

    Micropatterned surfaces with different chemical topographies were synthesised in order to investigate the influence of surface chemistry and topography on cell behaviour. The microstructured materials were synthesised by photoimmobilising natural Hyaluronan (Hyal) and its sulphated derivative (HyalS), both adequately functionalised with a photorective moiety, on glass substrates. Four different grating patterns (10, 25, 50 and 100 {mu}m) were used to pattern the hyaluronan. The micropatterned samples were analysed by Secondary Ions Mass Spectrometry, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy to investigate the chemistry and the topography of the surfaces. The spectroscopic and microscopic analysis of the microstructured surfaces revealed that the photoimmobilisation process was successful, demonstrating that the photomask patterns were well reproduced on the sample surface. The influence of chemical topographies on the cell behaviour was then analysed. Human and 3T3 fibroblasts, bovine aortic and human (HGTFN line) endothelial cells were used and their behaviour on the micropatterned surfaces was analysed in terms of adhesion, proliferation, locomotion and orientation. Both chemical and topographical controls were found to be important for cell guidance. By decreasing the stripe dimensions, a more fusiform shape of cell was observed. At the same time, the cell locomotion and orientation parallel to the structure increased. However, differences in cell behaviour were detected according to both cell type and micropattern dimensions.

  8. Ammonia synthesis over a Ru(0001) surface studied by density functional calculations

    DEFF Research Database (Denmark)

    Logadottir, Ashildur; Nørskov, Jens Kehlet

    2003-01-01

    In this paper we present DFT studies of all the elementary steps in the synthesis of ammonia from gaseous hydrogen and nitrogen over a ruthenium crystal. The stability and configurations of intermediates in the ammonia synthesis over a Ru(0001) surface have been investigated, both over a flat...... surface and over a stepped surface. The calculations show that the step sites on the surface are much more reactive than the terrace sites. The DFT results are then used to study the mechanism of promotion by alkalies over the Ru(0001) and to determine the rate-determining step in the synthesis of ammonia...

  9. Dynamic metabolic flux analysis of plant cell wall synthesis.

    Science.gov (United States)

    Chen, Xuewen; Alonso, Ana P; Shachar-Hill, Yair

    2013-07-01

    The regulation of plant cell wall synthesis pathways remains poorly understood. This has become a bottleneck in designing bioenergy crops. The goal of this study was to analyze the regulation of plant cell wall precursor metabolism using metabolic flux analysis based on dynamic labeling experiments. Arabidopsis T87 cells were cultured heterotrophically with (13)C labeled sucrose. The time course of ¹³C labeling patterns in cell wall precursors and related sugar phosphates was monitored using liquid chromatography tandem mass spectrometry until steady state labeling was reached. A kinetic model based on mass action reaction mechanisms was developed to simulate the carbon flow in the cell wall synthesis network. The kinetic parameters of the model were determined by fitting the model to the labeling time course data, cell wall composition, and synthesis rates. A metabolic control analysis was performed to predict metabolic regulations that may improve plant biomass composition for biofuel production. Our results describe the routes and rates of carbon flow from sucrose to cell wall precursors. We found that sucrose invertase is responsible for the entry of sucrose into metabolism and UDP-glucose-4-epimerase plays a dominant role in UDP-Gal synthesis in heterotrophic Aradidopsis cells under aerobic conditions. We also predicted reactions that exert strong regulatory influence over carbon flow to cell wall synthesis and its composition.

  10. Nanostructuring of Solar Cell Surfaces

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk

    Solar energy is by far the most abundant renewable energy source available, but the levelized cost of solar energy is still not competitive with that of fossil fuels. Therefore there is a need to improve the power conversion effciency of solar cells without adding to the production cost. The main...... objective of this PhD thesis is to develop nanostructured silicon (Si) solar cells with higher power conversion efficiency using only scalable and cost-efficient production methods. The nanostructures, known as 'black silicon', are fabricated by single-step, maskless reactive ion etching and used as front...

  11. Nanoparticle Properties and Synthesis Effects on Surface-Enhanced Raman Scattering Enhancement Factor: An Introduction

    Directory of Open Access Journals (Sweden)

    Nathan D. Israelsen

    2015-01-01

    Full Text Available Raman spectroscopy has enabled researchers to map the specific chemical makeup of surfaces, solutions, and even cells. However, the inherent insensitivity of the technique makes it difficult to use and statistically complicated. When Raman active molecules are near gold or silver nanoparticles, the Raman intensity is significantly amplified. This phenomenon is referred to as surface-enhanced Raman spectroscopy (SERS. The extent of SERS enhancement is due to a variety of factors such as nanoparticle size, shape, material, and configuration. The choice of Raman reporters and protective coatings will also influence SERS enhancement. This review provides an introduction to how these factors influence signal enhancement and how to optimize them during synthesis of SERS nanoparticles.

  12. Synthesis and surface modification of magnetic particles for application in biotechnology and biomedicine

    Institute of Scientific and Technical Information of China (English)

    Zhiya; Ma; Huizhou; Liu

    2007-01-01

    Magnetic particles have numerous applications in biotechnology and biomedicine. In this paper we reviewed the synthesis, surface modification and some applications of magnetic particles with focus on their synthesis and surface modification. Various methods have been developed for the production of magnetic particles (magnetic nanoparticles and magnetic composite particles). For future application magnetic particles must be modified to obtain stability and surface functional groups. Finally, the application of magnetic particles in magnetic separation, drug delivery,hyperthermia, and magnetic resonance imaging are discussed.

  13. Amiloride, protein synthesis, and activation of quiescent cells.

    Science.gov (United States)

    Lubin, M; Cahn, F; Coutermarsh, B A

    1982-11-01

    Amiloride is known to inhibit both influx of sodium ions and activation of quiescent cells by growth factors. The coincidence of these effects has been cited to support the proposal that influx of sodium ions acts as a mitogenic signal. Although it was noted that amiloride inhibited protein synthesis, this was attributed to an action on transport of amino acids, particularly those coupled to sodium fluxes. We find, however, that amiloride directly inhibits polypeptide synthesis in a reticulocyte lysate. In Swiss 3T3 cells, concentrations of amiloride and of cycloheximide that are nearly matched in their degree of inhibition of protein synthesis, produce about the same degree of inhibition of transit of cells from G0 to S. Inhibition of protein synthesis is sufficient to explain the effect of amiloride on mitogenesis; the drug, therefore, is not suitable for testing the hypothesis that sodium influx is a mitogenic signal.

  14. Structure and functions of fungal cell surfaces

    Science.gov (United States)

    Nozawa, Y.

    1984-01-01

    A review with 24 references on the biochemistry, molecular structure, and function of cell surfaces of fungi, especially dermatophytes: the chemistry and structure of the cell wall, the effect of polyene antibiotics on the morphology and function of cytoplasmic membranes, and the chemical structure and function of pigments produced by various fungi are discussed.

  15. Probes for anionic cell surface detection

    Science.gov (United States)

    Smith, Bradley D.

    2013-03-05

    Embodiments of the present invention are generally directed to compositions comprising a class of molecular probes for detecting the presence of anionic cell surfaces. Embodiments include compositions that are enriched for these compositions and preparations, particularly preparations suitable for use as laboratory/clinical reagents and diagnostic indicators, either alone or as part of a kit. An embodiment of the invention provides for a highly selective agent useful in the discernment and identification of dead or dying cells, such as apoptotic cells, in a relatively calcium-free environment. An embodiment of the invention provides a selective agent for the identification of bacteria in a mixed population of bacterial cells and nonbacterial cells.

  16. Nanotomography of Cell Surfaces with Evanescent Fields

    Directory of Open Access Journals (Sweden)

    Michael Wagner

    2008-01-01

    Full Text Available The technique of variable-angle total internal reflection fluorescence microscopy (TIRFM and its application to nanotomography of cell surfaces are described. Present applications include (1 3D imaging of chromosomes in their metaphase to demonstrate axial resolution in the nanometre range, (2 measurements of cell-substrate topology, which upon cholesterol depletion shows some loosening of cell-substrate contacts, and (3 measurements of cell topology upon photodynamic therapy (PDT, which demonstrate cell swelling and maintenance of focal contacts. The potential of the method for in vitro diagnostics, but also some requirements and limitations are discussed.

  17. Surface structure characterization of Aspergillus fumigatus conidia mutated in the melanin synthesis pathway and their human cellular immune response.

    Science.gov (United States)

    Bayry, Jagadeesh; Beaussart, Audrey; Dufrêne, Yves F; Sharma, Meenu; Bansal, Kushagra; Kniemeyer, Olaf; Aimanianda, Vishukumar; Brakhage, Axel A; Kaveri, Srini V; Kwon-Chung, Kyung J; Latgé, Jean-Paul; Beauvais, Anne

    2014-08-01

    In Aspergillus fumigatus, the conidial surface contains dihydroxynaphthalene (DHN)-melanin. Six-clustered gene products have been identified that mediate sequential catalysis of DHN-melanin biosynthesis. Melanin thus produced is known to be a virulence factor, protecting the fungus from the host defense mechanisms. In the present study, individual deletion of the genes involved in the initial three steps of melanin biosynthesis resulted in an altered conidial surface with masked surface rodlet layer, leaky cell wall allowing the deposition of proteins on the cell surface and exposing the otherwise-masked cell wall polysaccharides at the surface. Melanin as such was immunologically inert; however, deletion mutant conidia with modified surfaces could activate human dendritic cells and the subsequent cytokine production in contrast to the wild-type conidia. Cell surface defects were rectified in the conidia mutated in downstream melanin biosynthetic pathway, and maximum immune inertness was observed upon synthesis of vermelone onward. These observations suggest that although melanin as such is an immunologically inert material, it confers virulence by facilitating proper formation of the A. fumigatus conidial surface.

  18. Ovarian carcinoma cells synthesize both chondroitin sulfate and heparan sulfate cell surface proteoglycans that mediate cell adhesion to interstitial matrix.

    Science.gov (United States)

    Kokenyesi, R

    Metastatic ovarian carcinoma metastasizes by intra-peritoneal, non-hematogenous dissemination. The adhesion of the ovarian carcinoma cells to extracellular matrix components, such as types I and III collagen and cellular fibronectin, is essential for intra-peritoneal dissemination. The purpose of this study was to determine whether cell surface proteoglycans (a class of matrix receptors) are produced by ovarian carcinoma cells, and whether these proteoglycans have a role in the adhesion of ovarian carcinoma cells to types I and III collagen and fibronectin. Proteoglycans were metabolically labeled for biochemical studies. Both phosphatidylinositol-anchored and integral membrane-type cell surface proteoglycans were found to be present on the SK-OV-3 and NIH:OVCAR-3 cell lines. Three proteoglycan populations of differing hydrodynamic size were detected in both SK-OV-3 and NIH:OVCAR-3 cells. Digestions with heparitinase and chondroitinase ABC showed that cell surface proteoglycans of SK-OV-3 cells had higher proportion of chondroitin sulfate proteoglycans (75:25 of chondroitin sulfate:heparan sulfate ratio), while NIH:OVCAR-3 cells had higher proportion of heparan sulfate proteoglycans (10:90 of chondroitin sulfate:heparan sulfate ratio). RT-PCR indicated the synthesis of a unique assortment of syndecans, glypicans, and CD44 by the two cell lines. In adhesion assays performed on matrix-coated titer plates both cell lines adhered to types I and III collagen and cellular fibronectin, and cell adhesion was inhibited by preincubation of the matrix with heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate, or chondroitin glycosaminoglycans. Treatment of the cells with heparitinase, chondroitinase ABC, or methylumbelliferyl xyloside also interfered with adhesion confirming the role of both heparan sulfate and chondroitin sulfate cell surface proteoglycans as matrix receptors on ovarian carcinoma cells.

  19. Cell-Free, De Nova Synthesis of Poliovirus

    Science.gov (United States)

    Molla, Akhteruzzaman; Paul, Aniko V.; Wimmer, Eckard

    1991-12-01

    Cell-free translation of poliovirus RNA in an extract of uninfected human (HeLa) cells yielded viral proteins through proteolysis of the polyprotein. In the extract, newly synthesized proteins catalyzed poliovirus-specific RNA synthesis, and formed infectious poliovirus de novo. Newly formed virions were neutralized by type-specific antiserum, and infection of human cells with them was prevented by poliovirus receptor-specific antibodies. Poliovirus synthesis was increased nearly 70-fold when nucleoside triphosphates were added, but it was abolished in the presence of inhibitors of translation or viral genome replication. The ability to conduct cell-free synthesis of poliovirus will aid in the study of picornavirus proliferation and in the search for the control of picornaviral disease.

  20. In vivo protein synthesis determinations in human immune cells

    OpenAIRE

    Januszkiewicz, Anna

    2005-01-01

    Intact immune responses are essential for defeating severe infections in individual patients. Insufficient function of the immune system contributes to a poor prognosis in these patients, in particular the ICU patients. Nevertheless, the immune system function is not easily monitored and evaluated. The ongoing metabolic activity of immune competent cells is reflected by their in vivo protein synthesis rate. The aim of this thesis was to apply in vivo protein synthesis measur...

  1. Surface cell immobilization within perfluoroalkoxy microchannels

    Science.gov (United States)

    Stojkovič, Gorazd; Krivec, Matic; Vesel, Alenka; Marinšek, Marjan; Žnidaršič-Plazl, Polona

    2014-11-01

    Perfluoroalkoxy (PFA) is one of the most promising materials for the fabrication of cheap, solvent resistant and reusable microfluidic chips, which have been recently recognized as effective tools for biocatalytic process development. The application of biocatalysts significantly depends on efficient immobilization of enzymes or cells within the reactor enabling long-term biocatalyst use. Functionalization of PFA microchannels by 3-aminopropyltriethoxysilane (ATPES) and glutaraldehyde was used for rapid preparation of microbioreactors with surface-immobilized cells. X-ray photoelectron spectroscopy and scanning electron microscopy were used to accurately monitor individual treatment steps and to select conditions for cell immobilization. The optimized protocol for Saccharomyces cerevisiae immobilization on PFA microchannel walls comprised ethanol surface pretreatment, 4 h contacting with 10% APTES aqueous solution, 10 min treatment with 1% glutaraldehyde and 20 min contacting with cells in deionized water. The same protocol enabled also immobilization of Escherichia coli, Pseudomonas putida and Bacillus subtilis cells on PFA surface in high densities. Furthermore, the developed procedure has been proved to be very efficient also for surface immobilization of tested cells on other materials that are used for microreactor fabrication, including glass, polystyrene, poly (methyl methacrylate), polycarbonate, and two olefin-based polymers, namely Zeonor® and Topas®.

  2. Novel meta-surface design synthesis via nature-inspired optimization algorithms

    Science.gov (United States)

    Bayraktar, Zikri

    Heuristic numerical optimization algorithms have been gaining interest over the years as the computational power of the digital computers increases at an unprecedented level every year. While mature techniques such as the Genetic Algorithm increase their application areas, researchers also try to come up with new algorithms by simply observing the highly tuned processes provided by the nature. In this dissertation, the well-known Genetic Algorithm (GA) will be utilized to tackle various novel electromagnetic optimization problems, along with parallel implementation of the Clonal Selection Algorithm (CLONALG) and newly introduced the Wind Driven Optimization (WDO) technique. The utility of the CLONALG parallelization and the efficiency of the WDO will be illustrated by applying them to multi-dimensional and multi-modal electromagnetics problems such as antenna design and metamaterial surface synthesis. One of the metamaterial application areas is the design synthesis of 90 degrees rotationally symmetric ultra-small unit cell artificial magnetic conducting (AMC) surfaces. AMCs are composite metallo-dielectric structures designed to behave as perfect magnetic conductors (PMC) over a certain frequency range, those exhibit a reflection coefficient magnitude of unity with an phase angle of zero degrees at the center of the band. The proposed designs consist of ultra small sized frequency selective surface (FSS) unit cells that are tightly packed and highly intertwined, yet achieve remarkable AMC band performance and field of view when compared to current state-of-the-art AMCs. In addition, planar double-sided AMC (DSAMC) structures are introduced and optimized as AMC ground planes for low profile antennas in composite platforms and separator slabs for vertical antenna applications. The proposed designs do not possess complete metallic ground planes, which makes them ideal for composite and multi-antenna systems. The versatility of the DSAMC slabs is also illustrated

  3. Boric Acid Disturbs Cell Wall Synthesis in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Martin Schmidt

    2010-01-01

    Full Text Available Boric acid (BA has broad antimicrobial activity that makes it a popular treatment for yeast vaginitis in complementary and alternative medicine. In the model yeast S. cerevisiae, BA disturbs the cytoskeleton at the bud neck and impairs the assembly of the septation apparatus. BA treatment causes cells to form irregular septa and leads to the synthesis of irregular cell wall protuberances that extend far into the cytoplasm. The thick, chitin-rich septa that are formed during BA exposure prevent separation of cells after abscission and cause the formation of cell chains and clumps. As a response to the BA insult, cells signal cell wall stress through the Slt2p pathway and increase chitin synthesis, presumably to repair cell wall damage.

  4. Synthesis of Sphingolipids Impacts Survival of Porphyromonas gingivalis and the Presentation of Surface Polysaccharides

    Science.gov (United States)

    Moye, Zachary D.; Valiuskyte, Kornelija; Dewhirst, Floyd E.; Nichols, Frank C.; Davey, Mary E.

    2016-01-01

    Bacteria alter the biophysical properties of their membrane lipids in response to environmental cues, such as shifts in pH or temperature. In essence, lipid composition determines membrane structure, which in turn influences many basic functions, such as transport, secretion, and signaling. Like other members of the phylum Bacteroidetes, the oral anaerobe Porphyromonas gingivalis possesses the ability to synthesize a variety of novel membrane lipids, including species of dihydroceramides that are distinct, yet similar in structure to sphingolipids produced by the human host. The role of dihydroceramides in the physiology and pathogenic potential of the human microbiota is only beginning to be explored; yet there is increasing data indicating that these lipids play a role in human diseases, such as periodontitis and multiple sclerosis. Here, we report on the identification of a gene (PG1780) in the chromosome of P. gingivalis strain W83 encoding a putative serine palmitoyltransferase, the enzyme that catalyzes the first step in sphingolipid biosynthesis. While we were able to detect dihydroceramides in whole lipid extracts of P. gingivalis cells as well as crude preparations of outer membrane vesicles, sphingolipids were absent in the PG1780 mutant strain. Moreover, we show that the synthesis of sphingolipids plays an essential role in the long-term survival of the organism as well as its resistance to oxidative stress. Further, a PG1780 mutant displayed much lower activity of cell-associated arginine and lysine gingipains, yet slightly higher activity in the corresponding culture supernates, which we hypothesize is due to altered membrane properties and anchoring of these proteases to the cell surface. In addition, we determined that sphingolipid production is critical to the presentation of surface polysaccharides, with the mutant strain displaying less K-antigen capsule and more anionic polysaccharide (APS). Overall, we have discovered that, in addition to their

  5. Surface cell immobilization within perfluoroalkoxy microchannels

    Energy Technology Data Exchange (ETDEWEB)

    Stojkovič, Gorazd; Krivec, Matic [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia); Vesel, Alenka [Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); Marinšek, Marjan [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia); Žnidaršič-Plazl, Polona, E-mail: polona.znidarsic@fkkt.uni-lj.si [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia)

    2014-11-30

    Graphical abstract: - Highlights: • A very efficient approach for immobilization of cells into microreactors is presented. • It is applicable to various materials, including PFA and cyclic olefin (co)polymers. • It was used to immobilize different prokaryotic and eukaryotic microbes. • Cells were immobilized on the surface in high density and showed good stability. • Mechanisms of APTES interactions with target materials are proposed. - Abstract: Perfluoroalkoxy (PFA) is one of the most promising materials for the fabrication of cheap, solvent resistant and reusable microfluidic chips, which have been recently recognized as effective tools for biocatalytic process development. The application of biocatalysts significantly depends on efficient immobilization of enzymes or cells within the reactor enabling long-term biocatalyst use. Functionalization of PFA microchannels by 3-aminopropyltriethoxysilane (ATPES) and glutaraldehyde was used for rapid preparation of microbioreactors with surface-immobilized cells. X-ray photoelectron spectroscopy and scanning electron microscopy were used to accurately monitor individual treatment steps and to select conditions for cell immobilization. The optimized protocol for Saccharomyces cerevisiae immobilization on PFA microchannel walls comprised ethanol surface pretreatment, 4 h contacting with 10% APTES aqueous solution, 10 min treatment with 1% glutaraldehyde and 20 min contacting with cells in deionized water. The same protocol enabled also immobilization of Escherichia coli, Pseudomonas putida and Bacillus subtilis cells on PFA surface in high densities. Furthermore, the developed procedure has been proved to be very efficient also for surface immobilization of tested cells on other materials that are used for microreactor fabrication, including glass, polystyrene, poly (methyl methacrylate), polycarbonate, and two olefin-based polymers, namely Zeonor{sup ®} and Topas{sup ®}.

  6. On-Surface Synthesis by Click Chemistry Investigated by STM and XPS

    DEFF Research Database (Denmark)

    Vadapoo, Sundar Raja

    2014-01-01

    such as molecular electronics and surface functionalization. In this thesis, a well-defined click chemistry approach is followed, with the study of azide-alkyne cycloaddition on Cu(111) surface in UHV environment. A successful achievement of the click reaction product via on-surface synthesis has been shown, which...

  7. Characterization and use of crystalline bacterial cell surface layers

    Science.gov (United States)

    Sleytr, Uwe B.; Sára, Margit; Pum, Dietmar; Schuster, Bernhard

    2001-10-01

    Crystalline bacterial cell surface layers (S-layers) are one of the most common outermost cell envelope components of prokaryotic organisms (archaea and bacteria). S-layers are monomolecular arrays composed of a single protein or glycoprotein species and represent the simplest biological membranes developed during evolution. S-layers as the most abundant of prokaryotic cellular proteins are appealing model systems for studying the structure, synthesis, genetics, assembly and function of proteinaceous supramolecular structures. The wealth of information existing on the general principle of S-layers have revealed a broad application potential. The most relevant features exploited in applied S-layer research are: (i) pores passing through S-layers show identical size and morphology and are in the range of ultrafiltration membranes; (ii) functional groups on the surface and in the pores are aligned in well-defined positions and orientations and accessible for chemical modifications and binding functional molecules in very precise fashion; (iii) isolated S-layer subunits from a variety of organisms are capable of recrystallizing as closed monolayers onto solid supports (e.g., metals, polymers, silicon wafers) at the air-water interface, on lipid films or onto the surface of liposomes; (iv) functional domains can be incorporated in S-layer proteins by genetic engineering. Thus, S-layer technologies particularly provide new approaches for biotechnology, biomimetics, molecular nanotechnology, nanopatterning of surfaces and formation of ordered arrays of metal clusters or nanoparticles as required for nanoelectronics.

  8. Nitrate Uptake Affects Cell Wall Synthesis and Modeling

    Directory of Open Access Journals (Sweden)

    Simone Landi

    2017-08-01

    Full Text Available Nowadays, the relationship(s about N assimilation and cell wall remodeling in plants remains generally unclear. Enzymes involved in cell wall synthesis/modification, and nitrogen transporters play a critical role in plant growth, differentiation, and response to external stimuli. In this review, a co-expression analysis of nitrate and ammonium transporters of Arabidopsis thaliana was performed in order to explore the functional connection of these proteins with cell-wall related enzymes. This approach highlighted a strict relationship between inorganic nitrogen transporters and cell wall formation, identifying a number of co-expressed remodeling enzymes. The enzymes involved in pectin and xyloglucan synthesis resulted particularly co-regulated together with nitrate carriers, suggesting a connection between nitrate assimilation and cell wall growth regulation. Major Facilitator Carriers, and one chloride channel, are similarly co-expressed with pectin lyase, pectinacetylesterase, and cellulose synthase. Contrarily, ammonium transporters show little or no connection with those genes involved in cell wall synthesis. Different aspects related to plant development, embryogenesis, and abiotic stress response will be discussed, given the importance in plant growth of cell wall synthesis and nitrate uptake. Intriguingly, the improvement of abiotic stress tolerance in crops concerns both these processes indicating the importance in sensing the environmental constraints and mediating a response. These evaluations could help to identify candidate genes for breeding purposes.

  9. Cell surface engineering with edible protein nanoshells.

    Science.gov (United States)

    Drachuk, Irina; Shchepelina, Olga; Harbaugh, Svetlana; Kelley-Loughnane, Nancy; Stone, Morley; Tsukruk, Vladimir V

    2013-09-23

    Natural protein (silk fibroin) nanoshells are assembled on the surface of Saccharomyces cerevisiae yeast cells without compromising their viability. The nanoshells facilitate initial protection of the cells and allow them to function in encapsulated state for some time period, afterwards being completely biodegraded and consumed by the cells. In contrast to a traditional methanol treatment, the gentle ionic treatment suggested here stabilizes the shell silk fibroin structure but does not compromise the viability of the cells, as indicated by the fast response of the encapsulated cells, with an immediate activation by the inducer molecules. Extremely high viability rates (up to 97%) and preserved activity of encapsulated cells are facilitated by cytocompatibility of the natural proteins and the formation of highly porous shells in contrast to traditional polyelectrolyte-based materials. Moreover, in a high contrast to traditional synthetic shells, the silk proteins are biodegradable and can be consumed by cells at a later stage of growth, thus releasing the cells from their temporary protective capsules. These on-demand encapsulated cells can be considered a valuable platform for biocompatible and biodegradable cell encapsulation, controlled cell protection in a synthetic environment, transfer to a device environment, and cell implantation followed by biodegradation and consumption of protective protein shells.

  10. The cell surface proteome of Entamoeba histolytica.

    Science.gov (United States)

    Biller, Laura; Matthiesen, Jenny; Kühne, Vera; Lotter, Hannelore; Handal, Ghassan; Nozaki, Tomoyoshi; Saito-Nakano, Yumiko; Schümann, Michael; Roeder, Thomas; Tannich, Egbert; Krause, Eberhard; Bruchhaus, Iris

    2014-01-01

    Surface molecules are of major importance for host-parasite interactions. During Entamoeba histolytica infections, these interactions are predicted to be of prime importance for tissue invasion, induction of colitis and liver abscess formation. To date, however, little is known about the molecules involved in these processes, with only about 20 proteins or protein families found exposed on the E. histolytica surface. We have therefore analyzed the complete surface proteome of E. histolytica. Using cell surface biotinylation and mass spectrometry, 693 putative surface-associated proteins were identified. In silico analysis predicted that ∼26% of these proteins are membrane-associated, as they contain transmembrane domains and/or signal sequences, as well as sites of palmitoylation, myristoylation, or prenylation. An additional 25% of the identified proteins likely represent nonclassical secreted proteins. Surprisingly, no membrane-association sites could be predicted for the remaining 49% of the identified proteins. To verify surface localization, 23 proteins were randomly selected and analyzed by immunofluorescence microscopy. Of these 23 proteins, 20 (87%) showed definite surface localization. These findings indicate that a far greater number of E. histolytica proteins than previously supposed are surface-associated, a phenomenon that may be based on the high membrane turnover of E. histolytica.

  11. Femtosecond fabricated surfaces for cell biology

    Science.gov (United States)

    Day, Daniel; Gu, Min

    2010-08-01

    Microfabrication using femtosecond pulse lasers is enabling access to a range of structures, surfaces and materials that was not previously available for scientific and engineering applications. The ability to produce micrometre sized features directly in polymer and metal substrates is demonstrated with applications in cell biology. The size, shape and aspect ratio of the etched features can be precisely controlled through the manipulation of the fluence of the laser etching process with respect to the properties of the target material. Femtosecond laser etching of poly(methyl methacrylate) and aluminium substrates has enabled the production of micrometre resolution moulds that can be accurately replicated using soft lithography. The moulded surfaces are used in the imaging of T cells and demonstrate the improved ability to observe biological events over time periods greater than 10 h. These results indicate the great potential femtosecond pulse lasers may have in the future manufacturing of microstructured surfaces and devices.

  12. Genes Required for Bacillus anthracis Secondary Cell Wall Polysaccharide Synthesis

    Science.gov (United States)

    Oh, So-Young; Lunderberg, J. Mark; Chateau, Alice; Schneewind, Olaf

    2016-01-01

    ABSTRACT The secondary cell wall polysaccharide (SCWP) is thought to be essential for vegetative growth and surface (S)-layer assembly in Bacillus anthracis; however, the genetic determinants for the assembly of its trisaccharide repeat structure are not known. Here, we report that WpaA (BAS0847) and WpaB (BAS5274) share features with membrane proteins involved in the assembly of O-antigen lipopolysaccharide in Gram-negative bacteria and propose that WpaA and WpaB contribute to the assembly of the SCWP in B. anthracis. Vegetative forms of the B. anthracis wpaA mutant displayed increased lengths of cell chains, a cell separation defect that was attributed to mislocalization of the S-layer-associated murein hydrolases BslO, BslS, and BslT. The wpaB mutant was defective in vegetative replication during early logarithmic growth and formed smaller colonies. Deletion of both genes, wpaA and wpaB, did not yield viable bacilli, and when depleted of both wpaA and wpaB, B. anthracis could not maintain cell shape, support vegetative growth, or assemble SCWP. We propose that WpaA and WpaB fulfill overlapping glycosyltransferase functions of either polymerizing repeat units or transferring SCWP polymers to linkage units prior to LCP-mediated anchoring of the polysaccharide to peptidoglycan. IMPORTANCE The secondary cell wall polysaccharide (SCWP) is essential for Bacillus anthracis growth, cell shape, and division. SCWP is comprised of trisaccharide repeats (→4)-β-ManNAc-(1→4)-β-GlcNAc-(1→6)-α-GlcNAc-(1→) with α-Gal and β-Gal substitutions; however, the genetic determinants and enzymes for SCWP synthesis are not known. Here, we identify WpaA and WpaB and report that depletion of these factors affects vegetative growth, cell shape, and S-layer assembly. We hypothesize that WpaA and WpaB are involved in the assembly of SCWP prior to transfer of this polymer onto peptidoglycan. PMID:27795328

  13. Ketone isosteres of 2-N-acetamidosugars as substrates for metabolic cell surface engineering

    Energy Technology Data Exchange (ETDEWEB)

    Hang, Howard C.; Bertozzi, Carolyn R.

    2000-08-22

    Novel chemical reactivity can be engendered on cell surfaces by the metabolic incorporation of unnatural sugars into cell surface glycoconjuagtes. 2-N-Acetamido sugars such as GalNAc and GlcNAc are abundant components of cell surface glycoconjugates, and hence attractive targets for metabolic cell surface engineering. Here we report (1) the synthesis of isosteric analogs bearing a ketone group in place of the N-acetamido group, and (2) evaluation of their metabolic incorporation into mammalian cell surface glycans. A ketone isostere of GalNAc was metabolized by CHO cells through the salvage pathway and delivered to O-linked glycoproteins on the cell surface. Its residence at the core position of O-linked glycans is suggested by studies with a-benzyl GalNAc, an inhibitor of O-linked oligosaccharide extension. A mutant CHO cell line lacking endogenous UDP-GalNAc demonstrated enhanced metabolism of the GalNAc analog, suggesting that competition with native intermediates might limits enzymatic transformation in mammalian cells. A ketone isostere of GlcNAc could not be detected on CHO or human cell surfaces after incubation. Thus, the enzymes in the GlcNAc salvage pathway might be less permissive of unnatural substrates than those comprising the GalNAc salvage pathway. Alternatively, high levels of endogenous GlcNAc derivatives might compete with the ketone isostere and prevent its incorporation into oligosaccharides.

  14. Effect of doxazosin on cholesterol synthesis in cell culture

    Energy Technology Data Exchange (ETDEWEB)

    D' Eletto, R.D.; Javitt, N.B.

    1989-01-01

    The effect of doxazosin on cholesterol synthesis was determined by measuring the content of deuterium-enriched cholesterol in rabbit fibroblasts with and without receptors for low-density lipoproteins (LDL) and in hepatoma (Hep G2 cells). Doxazosin, at concentrations of 5-20 mumol/L, increased LDL binding to hepatic cells in a dose-related manner. Also, in these hepatic cells, doxazosin produced dose-related decreases in both newly synthesized cholesterol and cholesterol ester. In rabbit fibroblasts that were LDL receptor negative, de novo cholesterol synthesis was markedly reduced by increasing concentrations of doxazosin. Taken together, these results suggest that doxazosin may have a direct inhibitory effect on cholesterol synthesis independent of the LDL receptor. The inhibition of cholesterol synthesis by doxazosin may cause cells to compensate by upregulating the LDL receptor, thereby increasing the importation of lipoprotein cholesterol and reducing LDL cholesterol in the medium. This hypothesis supports findings in the clinical setting whereby doxazosin has a beneficial effect on the lipid profile, and suggests a useful additional property for this antihypertensive agent.

  15. Engineering novel cell surface chemistry for selective tumor cell targeting

    Energy Technology Data Exchange (ETDEWEB)

    Bertozzi, C.R. [Univ. of California, Berkeley, CA (United States)]|[Lawrence Berkeley National Lab., CA (United States)

    1997-12-31

    A common feature of many different cancers is the high expression level of the two monosaccharides sialic acid and fucose within the context of cell-surface associated glycoconjugates. A correlation has been made between hypersialylation and/or hyperfucosylation and the highly metastatic phenotype. Thus, a targeting strategy based on sialic acid or fucose expression would be a powerful tool for the development of new cancer cell-selective therapies and diagnostic agents. We have discovered that ketone groups can be incorporated metabolically into cell-surface associated sialic acids. The ketone is can be covalently ligated with hydrazide functionalized proteins or small molecules under physiological conditions. Thus, we have discovered a mechanism to selectively target hydrazide conjugates to highly sialylated cells such as cancer cells. Applications of this technology to the generation of novel cancer cell-selective toxins and MRI contrast reagents will be discussed, in addition to progress towards the use of cell surface fucose residues as vehicles for ketone expression.

  16. Differential localization of LTA synthesis proteins and their interaction with the cell division machinery in Staphylococcus aureus.

    Science.gov (United States)

    Reichmann, Nathalie T; Piçarra Cassona, Carolina; Monteiro, João M; Bottomley, Amy L; Corrigan, Rebecca M; Foster, Simon J; Pinho, Mariana G; Gründling, Angelika

    2014-04-01

    Lipoteichoic acid (LTA) is an important cell wall component of Gram-positive bacteria. In Staphylococcus aureus it consists of a polyglycerolphosphate-chain that is retained within the membrane via a glycolipid. Using an immunofluorescence approach, we show here that the LTA polymer is not surface exposed in S. aureus, as it can only be detected after digestion of the peptidoglycan layer. S. aureus mutants lacking LTA are enlarged and show aberrant positioning of septa, suggesting a link between LTA synthesis and the cell division process. Using a bacterial two-hybrid approach, we show that the three key LTA synthesis proteins, YpfP and LtaA, involved in glycolipid production, and LtaS, required for LTA backbone synthesis, interact with one another. All three proteins also interacted with numerous cell division and peptidoglycan synthesis proteins, suggesting the formation of a multi-enzyme complex and providing further evidence for the co-ordination of these processes. When assessed by fluorescence microscopy, YpfP and LtaA fluorescent protein fusions localized to the membrane while the LtaS enzyme accumulated at the cell division site. These data support a model whereby LTA backbone synthesis proceeds in S. aureus at the division site in co-ordination with cell division, while glycolipid synthesis takes place throughout the membrane. © 2014 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

  17. Bacterial cell surface structures in Yersinia enterocolitica.

    Science.gov (United States)

    Białas, Nataniel; Kasperkiewicz, Katarzyna; Radziejewska-Lebrecht, Joanna; Skurnik, Mikael

    2012-06-01

    Yersinia enterocolitica is a widespread member of the family of Enterobacteriaceae that contains both non-virulent and virulent isolates. Pathogenic Y. enterocolitica strains, especially belonging to serotypes O:3, O:5,27, O:8 and O:9 are etiologic agents of yersiniosis in animals and humans. Y. enterocolitica cell surface structures that play a significant role in virulence have been subject to many investigations. These include outer membrane (OM) glycolipids such as lipopolysaccharide (LPS) and enterobacterial common antigen (ECA) and several cell surface adhesion proteins present only in virulent Y. enterocolitica, i.e., Inv, YadA and Ail. While the yadA gene is located on the Yersinia virulence plasmid the Ail, Inv, LPS and ECA are chromosomally encoded. These structures ensure the correct architecture of the OM, provide adhesive properties as well as resistance to antimicrobial peptides and to host innate immune response mechanisms.

  18. Basal lamina inhibition suppresses synthesis of calcium-dependent proteins associated with mammary epithelial cell spreading.

    Science.gov (United States)

    Rocha, V; Hom, Y K; Marinkovich, M P

    1986-08-01

    Spreading of mouse mammary epithelial cells on collagen gels is closely correlated with the synthesis of a group of putative calcium-binding proteins (CBP) (Braslau et al., Exp cell res 155 (1984) 213). Collagen synthesis was shown to occur during cell spreading, while omission of serum prevented cell spreading and the synthesis of collagen. The proline analogues cis-hydroxyproline and L-azetidine-2-carboxylic acid were shown to inhibit epithelial cell spreading and to suppress the collagen synthesis that occurs during serum-supported cell spreading. Inhibition of collagen synthesis resulted in the inhibition of CBP synthesis associated with cell spreading. In contrast, the collagen cross-linking inhibitor B-aminopropionitrile did not inhibit cell spreading nor did it suppress collagen synthesis; CBP synthesis was also normal during treatment with this inhibitor. Thus, mammary epithelial cell spreading on collagen gels and CBP synthesis can both be suppressed by inhibition of collagen synthesis indicating that they may be integrated in some manner. It is suggested that inhibition of cell spreading during inhibition of collagen synthesis results from failure to assemble a normal basal lamina; this may in turn signal suppression of CBP synthesis.

  19. Solid-supported synthesis: From pharmacologically relevant heterocycles to biologically active surfaces

    DEFF Research Database (Denmark)

    Komnatnyy, Vitaly V.

    The present PhD thesis consists of an introduction part and two separate parts covering selected research projects during the PhD study. The introduction part describes the concept of solid-supported synthesis and combinatorial chemistry. The chapter covers recent achievements in materials...... versatile amine -containing reagents. Subsequent applications in antimicrobial peptide synthesis, metal -catalysis, release from the surface, and polymer grafti ng, are also presented....

  20. Regulation of protein synthesis and autophagy in activated dendritic cells: implications for antigen processing and presentation.

    Science.gov (United States)

    Argüello, Rafael J; Reverendo, Marisa; Gatti, Evelina; Pierre, Philippe

    2016-07-01

    Antigenic peptides presented in the context of major histocompatibility complex (MHC) molecules originate from the degradation of both self and non-self proteins. T cells can therefore recognize at the surface of surveyed cells, the self-peptidome produced by the cell itself (mostly inducing tolerance) or immunogenic peptides derived from exogenous origins. The initiation of adaptive immune responses by dendritic cells (DCs), through the antigenic priming of naïve T cells, is associated to microbial pattern recognition receptors engagement. Activation of DCs by microbial product or inflammatory cytokines initiates multiple processes that maximize DC capacity to present exogenous antigens and stimulate T cells by affecting major metabolic and membrane traffic pathways. These include the modulation of protein synthesis, the regulation of MHC and co-stimulatory molecules transport, as well as the regulation of autophagy, that, all together promote exogenous antigen presentation while limiting the display of self-antigens by MHC molecules.

  1. Content of intrinsic disorder influences the outcome of cell-free protein synthesis.

    Science.gov (United States)

    Tokmakov, Alexander A; Kurotani, Atsushi; Ikeda, Mariko; Terazawa, Yumiko; Shirouzu, Mikako; Stefanov, Vasily; Sakurai, Tetsuya; Yokoyama, Shigeyuki

    2015-09-11

    Cell-free protein synthesis is used to produce proteins with various structural traits. Recent bioinformatics analyses indicate that more than half of eukaryotic proteins possess long intrinsically disordered regions. However, no systematic study concerning the connection between intrinsic disorder and expression success of cell-free protein synthesis has been presented until now. To address this issue, we examined correlations of the experimentally observed cell-free protein expression yields with the contents of intrinsic disorder bioinformatically predicted in the expressed sequences. This analysis revealed strong relationships between intrinsic disorder and protein amenability to heterologous cell-free expression. On the one hand, elevated disorder content was associated with the increased ratio of soluble expression. On the other hand, overall propensity for detectable protein expression decreased with disorder content. We further demonstrated that these tendencies are rooted in some distinct features of intrinsically disordered regions, such as low hydrophobicity, elevated surface accessibility and high abundance of sequence motifs for proteolytic degradation, including sites of ubiquitination and PEST sequences. Our findings suggest that identification of intrinsically disordered regions in the expressed amino acid sequences can be of practical use for predicting expression success and optimizing cell-free protein synthesis.

  2. Iron Reverses Impermeable Chelator Inhibition of DNA Synthesis in CCl39 Cells

    Science.gov (United States)

    Alcain, Francisco J.; Low, Hans; Crane, Frederick L.

    1994-08-01

    Treatment of Chinese hamster lung fibro-blasts (CCl 39 cells) with the impermeable iron(II) chelator bathophenanthroline disulfonate (BPS) inhibits DNA synthesis when cell growth is initiated with growth factors including epidermal growth factor plus insulin, thrombin, or ceruloplasmin, but not with 10% fetal calf serum. The BPS treatment inhibits transplasma membrane electron transport. The treatment leads to release of iron from the cells as determined by BPS iron(II) complex formation over 90 min. Growth factor stimulation of DNA synthesis and electron transport are restored by addition of di- or trivalent iron to the cells in the form of ferric ammonium citrate, ferrous ammonium sulfate, or diferric transferrin. The effect with BPS differs from the inhibition of growth by hydroxyurea, which acts on the ribonucleotide reductase, or diethylenetriaminepentaacetic acid, which is another impermeable chelating agent, in that these agents inhibit growth in 10% fetal calf serum. The BPS effect is consistent with removal of iron from a site on the cell surface that controls DNA synthesis.

  3. Synthesis of reduced-size gold nanostars and internalization in SH-SY5Y cells

    KAUST Repository

    Dacarro, Giacomo

    2017-07-01

    The synthesis of large pentatwinned five-branched gold nanostars (GNS) has been modified so to obtain overall dimensions shrunk to 60% and a lower branches aspect ratio, leading to a dramatic blue shift of their two near-infrared (NIR) localized surface plasmon resonances (LSPR) absorptions but still maintaining one LSPR in the biotransparent NIR range. The interactions of polyethylene glycol (PEG) coated large and shrunk GNS with SH-SY5Y cells revealed that the large ones (DCI - diameter of the circumference in which GNS can be inscribed = 76 nm) are internalized more efficiently than the shrunk ones (DCI = 46 nm), correlating with a decreased cells surving fraction.

  4. Creating a completely "cell-free" system for protein synthesis.

    Science.gov (United States)

    Smith, Mark Thomas; Bennett, Anthony M; Hunt, Jeremy M; Bundy, Bradley C

    2015-01-01

    Cell-free protein synthesis is a promising tool to take biotechnology outside of the cell. A cell-free approach provides distinct advantages over in vivo systems including open access to the reaction environment and direct control over all chemical components for facile optimization and synthetic biology integration. Promising applications of cell-free systems include portable diagnostics, biotherapeutics expression, rational protein engineering, and biocatalyst production. The highest yielding and most economical cell-free systems use an extract composed of the soluble component of lysed Escherichia coli. Although E. coli lysis can be highly efficient (>99.999%), one persistent challenge is that the extract remains contaminated with up to millions of cells per mL. In this work, we examine the potential of multiple decontamination strategies to further reduce or eliminate bacteria in cell-free systems. Two strategies, sterile filtration and lyophilization, effectively eliminate contaminating cells while maintaining the systems' protein synthesis capabilities. Lyophilization provides the additional benefit of long-term stability at storage above freezing. Technologies for personalized, portable medicine and diagnostics can be expanded based on these foundational sterilized and completely "cell-free" systems.

  5. Improved cell-free RNA and protein synthesis system.

    Directory of Open Access Journals (Sweden)

    Jun Li

    Full Text Available Cell-free RNA and protein synthesis (CFPS is becoming increasingly used for protein production as yields increase and costs decrease. Advances in reconstituted CFPS systems such as the Protein synthesis Using Recombinant Elements (PURE system offer new opportunities to tailor the reactions for specialized applications including in vitro protein evolution, protein microarrays, isotopic labeling, and incorporating unnatural amino acids. In this study, using firefly luciferase synthesis as a reporter system, we improved PURE system productivity up to 5 fold by adding or adjusting a variety of factors that affect transcription and translation, including Elongation factors (EF-Ts, EF-Tu, EF-G, and EF4, ribosome recycling factor (RRF, release factors (RF1, RF2, RF3, chaperones (GroEL/ES, BSA and tRNAs. The work provides a more efficient defined in vitro transcription and translation system and a deeper understanding of the factors that limit the whole system efficiency.

  6. Induction of maturation of human B-cell lymphomas in vitro. Morphologic changes in relation to immunoglobulin and DNA synthesis.

    Science.gov (United States)

    Beiske, K.; Ruud, E.; Drack, A.; Marton, P. F.; Godal, T.

    1984-01-01

    In vitro stimulation of cells from 8 non-Hodgkin's lymphomas comprising several histologic types with a tumor promotor (TPA) and with or without anti-immunoglobulins directed against the surface immunoglobulin of the tumor cells is reported. Morphologic transformation to immunoblastic and plasmablastic cells, but not to plasma cells, and induction of Ig and DNA synthesis were observed. A comparative analysis, including flow cytofluorometry, light microscopy combined with immunocytochemistry, and electron microscopy, suggests that the three events may not always be associated phenomena at the single-cell level even in monoclonal cell populations. Images Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 PMID:6375389

  7. Disodium cromoglycate inhibits S mu-->S epsilon deletional switch recombination and IgE synthesis in human B cells

    Science.gov (United States)

    1994-01-01

    IgE synthesis requires interleukin 4 (IL-4) and a T-B cell interaction that involves the B cell antigen CD40 and its ligand expressed on activated T cells. IL-4 induces epsilon germline transcription whereas ligation of CD40 results in deletional S mu-->S epsilon switch recombination, expression of mature epsilon transcripts, and IgE synthesis and secretion. We demonstrate that disodium cromoglycate (DSCG), a drug commonly used for the prophylactic treatment of allergic disease, inhibits T cell-driven IgE synthesis by human B cells at concentrations readily achievable in the course of inhaled therapy for asthma. Inhibition of IgE synthesis by DSCG was not the result of drug toxicity because DSCG did not affect the viability of T and B cells or their proliferation to mitogens. DSCG did not interfere with CD40 ligand expression by T cells but clearly targeted the B cells because it inhibited IgE synthesis induced by anti-CD40 and IL-4 in populations of highly purified B cells. DSCG had no effect on the induction of epsilon germline transcripts by IL-4 but strongly inhibited CD40 mediated S mu-->S epsilon deletional switch recombination in IL-4- treated B cells as assayed by nested primer PCR. The effect of DSCG was not specific for CD40-mediated induction of IgE isotype switching because DSCG inhibited IgE synthesis as well as S mu-->S epsilon deletional switch recombination induced by hydrocortisone and IL-4 in B cells. Moreover, the effect of DSCG was not specific for IgE isotype switching because DSCG inhibited the synthesis of IgG4 by B cells sorted for lack of surface expression of IgG4 and stimulated with anti- CD40 and IL-4. DSCG caused only minimal inhibition (< 15%) of spontaneous IgE synthesis by lymphocytes from patients with the hyper- IgE syndrome and did not affect pokeweed mitogen-induced IgG and IgA synthesis by lymphocytes suggesting that it has little effect on B cells that have already undergone isotype switching. These results indicate that DSCG

  8. Synthesis of anisotropic swirling surface acoustic waves by inverse filter, towards integrated generators of acoustical vortices

    CERN Document Server

    Riaud, Antoine; Charron, Eric; Bussonnière, Adrien; Matar, Olivier Bou

    2015-01-01

    From radio-electronics signal analysis to biological samples actuation, surface acoustic waves (SAW) are involved in a multitude of modern devices. Despite this versatility, SAW transducers developed up to date only authorize the synthesis of the most simple standing or progressive waves such as plane and focused waves. In particular, acoustical integrated sources able to generate acoustical vortices (the analogue of optical vortices) are missing. In this work, we propose a flexible tool based on inverse filter technique and arrays of SAW transducers enabling the synthesis of prescribed complex wave patterns at the surface of anisotropic media. The potential of this setup is illustrated by the synthesis of a 2D analog of 3D acoustical vortices, namely "swirling surface acoustic waves". Similarly to their 3D counterpart, they appear as concentric structures of bright rings with a phase singularity in their center resulting in a central dark spot. Swirling SAW can be useful in fragile sensors whose neighborhood...

  9. Protein synthesis persists during necrotic cell death.

    NARCIS (Netherlands)

    Saelens, X.; Festjens, N.; Parthoens, E.; Overberghe, I. van; Kalai, M.; Kuppeveld, F.J.M. van; Vandenabeele, P.

    2005-01-01

    Cell death is an intrinsic part of metazoan development and mammalian immune regulation. Whereas the molecular events orchestrating apoptosis have been characterized extensively, little is known about the biochemistry of necrotic cell death. Here, we show that, in contrast to apoptosis, the inductio

  10. Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

    Science.gov (United States)

    Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

    2016-10-01

    Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION.

  11. ZnO Tetrapods: Synthesis and Applications in Solar Cells

    Directory of Open Access Journals (Sweden)

    Luting Yan

    2015-06-01

    Full Text Available Zinc oxide (ZnO tetrapods have received much interest due to their unique morphology, that is, four arms con‐ nected to one centre. Tetrapod networks possess the excellent electronic properties of the ZnO semiconductor, which is attractive for photoelectrode materials in energy- conversion devices because of their advantages in electron extraction and transportation. In this review, we have discussed recent advancements in the field of ZnO tetrapod synthesis, including vapour transport synthesis and the wet chemical method, together with their advantages and disadvantages in terms of morphology control and yield regulation. The developments and improvements in the applications of ZnO nanotetrapods in photovoltaics, including dye-sensitized solar cells and polymer solar cells, are also described. Our aim is to give readers a compre‐ hensive and critical overview of this unique morphology of ZnO, including synthesis control and growth mechanism, and to understand the role of this particular morphology in the development of solar cells. The future research directions in ZnO tetrapods-based solar cell are also discussed.

  12. Synthesis of Gold Nanoparticles Using Whole Cells of Geotrichum candidum

    Directory of Open Access Journals (Sweden)

    Amit Kumar Mittal

    2013-01-01

    Full Text Available The synthesis of nanoparticles with desired size and shape is an important area of research in nanotechnology. Use of biological system is an alternative approach to chemical and physical procedures for the synthesis of metal nanoparticles. An efficient environment-friendly approach for the biosynthesis of rapid and stable Gold nanoparticles (AuNPs using whole cells of Geotrichum candidum is discussed in this paper. The enzymes/proteins present in the microorganism might be responsible for the reduction of metal salts to nanoparticles. Various reaction parameters such as culture age, temperature, pH, metal salt, and cell mass concentrations were optimized. The AuNPs were characterized by UV-visible spectroscopy, dynamic light scattering (DLS, energy dispersive spectroscopy (EDS, scanning electron microscope (SEM, and Fourier transform infrared spectroscopy (FTIR. Nanoparticles were isolated by sonicating the whole cells after treatment with Tween 80. The whole cell mediated process showed the simplistic, feasible, easy to scale up, and low-cost approach for the synthesis of AuNPs.

  13. Synthesis, Structure and Reactivity of Molecules Attached to Electrode Surfaces.

    Science.gov (United States)

    2014-09-26

    Structure and Reactivity of Molecules Attached to Electrode Surfaces", AFOSR #81-0149 III. REPORTING PERIOD: April 15, 1981 through April 14, 1985 IV...Adsorption .... ............... 17 9. Effect of Surface Roughness on Adsorbate Orientation and Reactivity . 20 10. Ordered/ Disordered Packing in Chemisorbed... reactivity only when present in the edge-pendant orientation. Clearly, molecular orientation (i.e., mode of +. .4 o,, -12- attachment to the surface) is a

  14. Frequency Selective Surfaces with Nanoparticles Unit Cell

    Directory of Open Access Journals (Sweden)

    Nga Hung Poon

    2015-09-01

    Full Text Available The frequency selective surface (FSS is a periodic structure with filtering performance for optical and microwave signals. The general periodic arrays made with patterned metallic elements can act as an aperture or patch on a substrate. In this work, two kinds of materials were used to produce unit cells with various patterns. Gold nanoparticles of 25 nm diameter were used to form periodic monolayer arrays by a confined photocatalytic oxidation-based surface modification method. As the other material, silver gel was used to create multiple layers of silver. Due to the ultra-thin nature of the self-assembled gold nanoparticle monolayer, it is very easy to penetrate the FSS with terahertz radiation. However, the isolated silver islands made from silver gel form thicker multiple layers and contribute to much higher reflectance. This work demonstrated that multiple silver layers are more suitable than gold nanoparticles for use in the fabrication of FSS structures.

  15. MreB: pilot or passenger of cell wall synthesis?

    Science.gov (United States)

    White, Courtney L; Gober, James W

    2012-02-01

    The discovery that the bacterial cell shape determinant MreB is related to actin spurred new insights into bacterial morphogenesis and development. The trafficking and mechanical roles of the eukaryotic cytoskeleton were hypothesized to have a functional ancestor in MreB based on evidence implicating MreB as an organizer of cell wall synthesis. Genetic, biochemical and cytological studies implicate MreB as a coordinator of a large multi-protein peptidoglycan (PG) synthesizing holoenzyme. Recent advances in microscopy and new biochemical evidence, however, suggest that MreB may function differently than previously envisioned. This review summarizes our evolving knowledge of MreB and attempts to refine the generalized model of the proteins organizing PG synthesis in bacteria. This is generally thought to be conserved among eubacteria and the majority of the discussion will focus on studies from a few well-studied model organisms.

  16. One pot electrochemical synthesis of polymer/CNT/metal nanoparticles for fuel cell applications

    Science.gov (United States)

    Ventrapragada, Lakshman; Zhu, Jingyi; Karakaya, Mehmet; Podila, Ramakrishna; Rao, Apparao; Clemson Nanomaterials center Team

    Carbon nanotubes (CNTs) have become a key player in the design of materials for energy applications. They gained their popularity in industrial and scientific research due to their unique properties like excellent conductivity, high surface area, etc. Here we used chemical vapor deposition (CVD) to synthesize two types of CNTs namely, helically coiled CNTs and vertically aligned CNTs. These CNTs were subsequently used to make composites with conducting polymers and metal nanoparticles. One pot electrochemical synthesis was designed to electropolymerize aniline, pyrrole etc. on the surface of the electrode with simultaneous deposition of platinum and gold metal nanoparticles, and CNTs in the polymer matrix. The as synthesized composite materials were characterized with scanning electron microscope for surface morphology and spectroscopic techniques like Raman, UV-Vis for functionality. These were used to study electrocatalytic oxidation of methanol and ethanol for alkaline fuel cell applications. Electrodes fabricated from these composites not only showed good kinetics but also exhibited excellent stability. Uniqueness of this composite lies in its simple two step synthesis and it doesn't involve any surfactants unlike conventional chemical synthesis routes.

  17. Wettability influences cell behavior on superhydrophobic surfaces with different topographies

    NARCIS (Netherlands)

    Lourenco, B.N.; Marchioli, G.; Song, W; Reis, R L; van Blitterswijk, Clemens; Karperien, Hermanus Bernardus Johannes; van Apeldoorn, Aart A.; Mano, J.F.

    2012-01-01

    Surface wettability and topography are recognized as critical factors influencing cell behavior on biomaterials. So far only few works have reported cell responses on surfaces exhibiting extreme wettability in combination with surface topography. The goal of this work is to study whether cell behavi

  18. Wettability influences cell behavior on superhydrophobic surfaces with different topographies

    NARCIS (Netherlands)

    Lourenco, B.N.; Marchioli, G.; Song, W; Reis, R.L.; Blitterswijk, van C.A.; Karperien, H.B.J.; Apeldoorn, van A.A.; Mano, J.F.

    2012-01-01

    Surface wettability and topography are recognized as critical factors influencing cell behavior on biomaterials. So far only few works have reported cell responses on surfaces exhibiting extreme wettability in combination with surface topography. The goal of this work is to study whether cell behavi

  19. High surface area graphite as alternative support for proton exchange membrane fuel cell catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira-Aparicio, P.; Folgado, M.A. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, E-28040 Madrid (Spain); Daza, L. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, E-28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie, 2 Campus de Cantoblanco, E-28049 Madrid (Spain)

    2009-07-01

    The suitability of a high surface area graphite (HSAG) as proton exchange membrane fuel cell (PEMFC) catalyst support has been evaluated and compared with that of the most popular carbon black: the Vulcan XC72. It has been observed that Pt is arranged on the graphite surface resulting in different structures which depend on the catalysts synthesis conditions. The influence that the metal particle size and the metal-support interaction exert on the catalysts degradation rate is analyzed. Temperature programmed oxidation (TPO) under oxygen containing streams has been shown to be a useful method to assess the resistance of PEMFC catalysts to carbon corrosion. The synthesized Pt/HSAG catalysts have been evaluated in single cell tests in the cathode catalytic layer. The obtained results show that HSAG can be a promising alternative to the traditionally used Vulcan XC72 carbon black when suitable catalysts synthesis conditions are used. (author)

  20. Donor-Acceptor Block Copolymers: Synthesis and Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Kazuhiro Nakabayashi

    2014-04-01

    Full Text Available Fullerene derivatives have been widely used for conventional acceptor materials in organic photovoltaics (OPVs because of their high electron mobility. However, there are also considerable drawbacks for use in OPVs, such as negligible light absorption in the visible-near-IR regions, less compatibility with donor polymeric materials and high cost for synthesis and purification. Therefore, the investigation of non-fullerene acceptor materials that can potentially replace fullerene derivatives in OPVs is increasingly necessary, which gives rise to the possibility of fabricating all-polymer (polymer/polymer solar cells that can deliver higher performance and that are potentially cheaper than fullerene-based OPVs. Recently, considerable attention has been paid to donor-acceptor (D-A block copolymers, because of their promising applications as fullerene alternative materials in all-polymer solar cells. However, the synthesis of D-A block copolymers is still a challenge, and therefore, the establishment of an efficient synthetic method is now essential. This review highlights the recent advances in D-A block copolymers synthesis and their applications in all-polymer solar cells.

  1. Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

    Energy Technology Data Exchange (ETDEWEB)

    Sodipo, Bashiru Kayode, E-mail: bashirsodipo@gmail.com [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Aziz, Azlan Abdul [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia)

    2016-10-15

    Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION. - Highlights: • We present recent advances in synthesis of SPION and various routes of producing silica coated SPION • The synthetic routes of producing SPION can be classified into three: physical, chemical and biological methods. • The chemical method is the most cited method of producing SPION and it sub-classified into liquid and gas phase. • The techniques of producing silica coated SPION is grouped into seeded and non-seeded methods.

  2. Differential sensitivity to aphidicolin of replicative DNA synthesis and ultraviolet-induced unscheduled DNA synthesis in vivo in mammalian cells.

    Directory of Open Access Journals (Sweden)

    Seki,Shuji

    1984-06-01

    Full Text Available In vivo in mammalian cells, ultraviolet-induced unscheduled DNA synthesis was less sensitive to aphidicolin than was replicative DNA synthesis. Replicative DNA synthesis in HeLa, HEp-2, WI-38 VA-13 and CV-1 cells was inhibited more than 97% by aphidicolin at 10 micrograms/ml, whereas aphidicolin inhibition of DNA synthesis in ultraviolet-irradiated cells varied between 30% and 90% depending on cell types and assay conditions. Aphidicolin inhibition of unscheduled DNA synthesis (UDS in HeLa cells increased gradually with increasing aphidicolin concentration and reached approximately 90% at 100 micrograms/ml aphidicolin. A significant fraction of UDS in ultraviolet-irradiated HEp-2 cells was resistant to aphidicolin even at 300 micrograms/ml. Considered along with related information reported previously, the present results suggest that both aphidicolin-sensitive and insensitive DNA polymerases, DNA polymerase alpha and a non-alpha DNA polymerase (possibly DNA polymerase beta, are involved in in situ UDS in these ultraviolet-irradiated cells. Comparison of staphylococcal nuclease sensitivity between DNAs repaired in the presence and in the absence of aphidicolin in HEp-2 cells suggested that the involvement of DNA polymerase alpha in UDS favored DNA synthesis in the intranucleosomal region.

  3. Synthesis, chemical modification, and surface assembly of carbon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Amma, A.; St. Angelo, S.K.; Mallouk, T.E. [Department of Chemistry, The Pennsylvania State University, University Park, PA 16802 (United States); Razavi, B.; Mayer, T.S. [Electrical Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2003-05-01

    Carbon nanotubules and nanowires were synthesized by pyrolysis of polymer precursors in the pores of alumina membranes. The nanowires were released by dissolving the membranes, and were then made hydrophobic or hydrophilic by chemical surface derivatization. These nanowires could be placed into lithographically defined wells on surfaces by means of electrostatic interactions with monolayers at the bottoms of the wells. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  4. Swelling and Replicative DNA Synthesis of Detergent-treated Mouse Ascites Sarcoma Cells

    Directory of Open Access Journals (Sweden)

    Seki,Shuji

    1978-04-01

    Full Text Available Previous investigation showed that mouse ascites sarcoma cells permeabilized with appropriate concentrations of detergents (Triton X-100, Nonidet P-40 and Brij 58 had high replicative DNA synthesis in the presence of the four deoxyribonucleoside triphosphates, ATP, Mg2+ and proper ionic environment. The present study showed the optimum detergent concentration for DNA synthesis coincided closely with the minimum detergent concentration for inducing cell swelling. Phase contrast microscopy and electron microscopy of Triton-permeabilized cells showed the characteristic swollen cytoplasms and nucleus. Autoradiographic study showed that the DNA synthesis in permeable cells was confined to the nucleus. Cell viability and [3H] deoxythymidine uptake were impaired at much lower concentrations of Triton X-100 than the optimum concentration for in vitro DNA synthesis. In Triton-permeabilized cells, the minimum Triton concentration that produced cell swelling also seemed to produce high repliative DNA synthesis, which reflects the in vivo state of DNA synthesis.

  5. Synthesis and characterization of biodegradable lignin nanoparticles with tunable surface properties

    NARCIS (Netherlands)

    Richter, Alexander P.; Bharti, Bhuvnesh; Armstrong, Hinton B.; Brown, Joseph S.; Plemmons, Dayne; Paunov, Vesselin N.; Stoyanov, Simeon D.; Velev, Orlin D.

    2016-01-01

    Lignin nanoparticles can serve as biodegradable carriers of biocidal actives with minimal environmental footprint. Here we describe the colloidal synthesis and interfacial design of nanoparticles with tunable surface properties using two different lignin precursors, Kraft (Indulin AT) lignin and

  6. Synthesis and characterization of biodegradable lignin nanoparticles with tunable surface properties

    NARCIS (Netherlands)

    Richter, Alexander P.; Bharti, Bhuvnesh; Armstrong, Hinton B.; Brown, Joseph S.; Plemmons, Dayne; Paunov, Vesselin N.; Stoyanov, Simeon D.; Velev, Orlin D.

    2016-01-01

    Lignin nanoparticles can serve as biodegradable carriers of biocidal actives with minimal environmental footprint. Here we describe the colloidal synthesis and interfacial design of nanoparticles with tunable surface properties using two different lignin precursors, Kraft (Indulin AT) lignin and

  7. Synthesis and surface activity of diether-linked phosphoglycerols: potential applications for exogenous lung surfactants.

    Science.gov (United States)

    Notter, Robert H; Wang, Zhongyi; Wang, Zhengdong; Davy, Jason A; Schwan, Adrian L

    2007-01-01

    The synthesis of three phosphoglycerols is described, one of which contains the previously unknown phosphonoglycerol headgroup. The surface tension-lowering capabilities of synthetic lung surfactant mixtures containing the PG analogs were measured on the pulsating bubble surfactometer and compared to known controls. The PG-containing mixtures exhibited superior surface tension-lowering properties indicating the significant potential of these analogs as components in synthetic exogenous lung surfactants.

  8. Surface simulation synthesis: a new strategy to spy alpha-helix structure.

    Science.gov (United States)

    Dong, Xiao-Nan; Chen, Yu; Chen, Ying-Hua

    2007-09-04

    In key proteins, there are always some alpha-helix structures, which play important role in the structure and functions. Many epitopes lie on the surface of alpha-helix. These epitopes are not easy to be recruited into the vaccine development, because they are conformation dependent epitopes. Can such epitopes on alpha-helix be mimicked synthetically? Our findings undoubtedly validate the feasibility of surface simulation synthesis with short linear peptide to mimic the antigenic side of alpha-helix structure.

  9. Synthesis, characterization, Raman, and surface enhanced Raman studies of semiconductor quantum dots

    Science.gov (United States)

    Pan, Yi

    The major contributions and discoveries of the dissertation include: (1) Homogeneous nucleation processes for the formation of nanocrystals can occur at low temperature and do not need to proceed at high temperature to overcome a high energy barrier. Monodisperse PbS quantum dots (QDs) obtained with nucleation and growth at 45°C support this finding. (2) Monodisperse single elemental Se QDs can be produced by simple solution crystallization from TDE (1-tetradecene) or ODE (1-octadecene). (3) TDE is a better non-coordinating solvent compare to ODE. STDE (S dissolved in TDE) and SeTDE (Se dissolved in TDE) are stable reagents with long storage time. They can be used as universal precursors for S-containing and Se-containing QDs. (4) QDs synthesis can be carried out at low temperature and relatively short reaction time using the simple, non-injection, one-pot synthetic method. (5) The one-pot method can be extended for the synthesis of QDs and graphene oxide nanocomposites and metal and graphene oxide nanocomposites. (6) PbCl2-OLA (oleylamine) is a universal system for the synthesis of Pb-chaclogenides QDs. (7) Surface enhanced Raman spectroscopy (SERS) is used to probe both size and wave length dependent quantum confinement effects (QCEs) of PbS QDs. (8) Raman spectroscopy is a powerful tool to elucidate crystal structure of Se nanoclusters with size of 1--2 nm. Semiconductor QDs have attracted considerable attention due to their potential for energy-efficient materials in optoelectronic and solar cell applications. When the radius of a QD is decreased to that of the exciton Bohr radius, the valence and conduction bands are known to split into narrower bands due to QCEs. QCEs are both size and wave length dependent. We have developed, synthesized and characterized a series of Pb-chaclogenide QDs, which all the sizes of the QDs are monodisperse and smaller than their respective exciton Bohr radius, to study the QCEs of these QDs. SERS is used as a crucial tool to

  10. Knowledge discovery of cell-cell and cell-surface interactions

    Science.gov (United States)

    Su, Jing

    High-throughput cell culture is an emerging technology that shows promise as a tool for research in tissue engineering, drug discovery, and medical diagnostics. An important, but overlooked, challenge is the integration of experimental methods with information processing suitable for handling large databases of cell-cell and cell-substrate interactions. In this work the traditional global descriptions of cell behaviors and surface characteristics was shown insufficient for investigating short-distance cell-to-cell and cell-to-surface interactions. Traditional summary metrics cannot distinguish information of cell near neighborhood from the average, global features, thus often is not suitable for studying distance-sensitive cell behaviors. The problem of traditional summary metrics was addressed by introducing individual-cell based local metrics that emphasize cell local environment. An individual-cell based local data analysis method was established. Contact inhibition of cell proliferation was used as a benchmark for the effectiveness of the local metrics and the method. Where global, summary metrics were unsuccessful, the local metrics successfully and quantitatively distinguished the contact inhibition effects of MC3T3-E1 cells on PLGA, PCL, and TCPS surfaces. In order to test the new metrics and analysis method in detail, a model of cell contact inhibition was proposed. Monte Carlo simulation was performed for validating the individual-cell based local data analysis method as well as the cell model itself. The simulation results well matched with the experimental observations. The parameters used in the cell model provided new descriptions of both cell behaviors and surface characteristics. Based on the viewpoint of individual cells, the local metrics and local data analysis method were extended to the investigation of cell-surface interactions, and a new high-throughput screening and knowledge discovery method on combinatorial libraries, local cell

  11. Antigenic protein synthesis of Campylobacter jejuni in contact with chicken cells

    DEFF Research Database (Denmark)

    Vegge, Christina Skovgaard; Bang, Dang D.; Li, Yiping

    to the environment of the avian gastrointestinal tract. Consequently, the most important reservoir for C. jejuni is the gut of chickens, which are colonized efficiently without causing disease in the birds. Upon co-cultivation with mammalian cells, C. jejuni secrete specific Cia proteins, which are required...... the synthesis of antigenic C. jejuni proteins upon cultivation with chicken cells. Two strains of C. jejuni (the human isolate NCTC11168 and the chicken isolate DVI-SC11) were incubated with primary intestinal chicken cells and subsequently used to raise antisera in rabbits. Negative controls were carried out...... in parallel. These antisera were tested by Western blotting against C. jejuni total protein as well as periplasmic-, surface- and extracellular protein fractions. A unique antibody reaction was discovered to a protein from samples, which had been cultivated with chicken cells. The identity of this protein...

  12. Antigenic protein synthesis of Campylobacter jejuni in contact with chicken cells

    DEFF Research Database (Denmark)

    Vegge, Christina Skovgaard; Bang, Dang D.; Li, Yiping

    to the environment of the avian gastrointestinal tract. Consequently, the most important reservoir for C. jejuni is the gut of chickens, which are colonized efficiently without causing disease in the birds. Upon co-cultivation with mammalian cells, C. jejuni secrete specific Cia proteins, which are required...... the synthesis of antigenic C. jejuni proteins upon cultivation with chicken cells. Two strains of C. jejuni (the human isolate NCTC11168 and the chicken isolate DVI-SC11) were incubated with primary intestinal chicken cells and subsequently used to raise antisera in rabbits. Negative controls were carried out...... in parallel. These antisera were tested by Western blotting against C. jejuni total protein as well as periplasmic-, surface- and extracellular protein fractions. A unique antibody reaction was discovered to a protein from samples, which had been cultivated with chicken cells. The identity of this protein...

  13. Nanoscale analysis of caspofungin-induced cell surface remodelling in Candida albicans

    Science.gov (United States)

    El-Kirat-Chatel, Sofiane; Beaussart, Audrey; Alsteens, David; Jackson, Desmond N.; Lipke, Peter N.; Dufrêne, Yves F.

    2013-01-01

    The advent of fungal pathogens that are resistant to the classic repertoire of antifungal drugs has increased the need for new therapeutic agents. A prominent example of such a novel compound is caspofungin, known to alter cell wall biogenesis by inhibiting β-1,3-d-glucan synthesis. Although much progress has been made in understanding the mechanism of action of caspofungin, little is known about its influence on the biophysical properties of the fungal cells. Here, we use atomic force microscopy (AFM) to demonstrate that caspofungin induces major remodelling of the cell surface properties of Candida albicans. Caspofungin causes major morphological and structural alterations of the cells, which correlate with a decrease of the cell wall mechanical strength. Moreover, we find that the drug induces the massive exposure of the cell adhesion protein Als1 on the cell surface and leads to increased cell surface hydrophobicity, two features that trigger cell aggregation. This behaviour is not observed in yeast species lacking Als1, demonstrating the key role that the protein plays in determining the aggregation phenotype of C. albicans. The results show that AFM opens up new avenues for understanding the molecular bases of microbe-drug interactions and for developing new therapeutic agents.The advent of fungal pathogens that are resistant to the classic repertoire of antifungal drugs has increased the need for new therapeutic agents. A prominent example of such a novel compound is caspofungin, known to alter cell wall biogenesis by inhibiting β-1,3-d-glucan synthesis. Although much progress has been made in understanding the mechanism of action of caspofungin, little is known about its influence on the biophysical properties of the fungal cells. Here, we use atomic force microscopy (AFM) to demonstrate that caspofungin induces major remodelling of the cell surface properties of Candida albicans. Caspofungin causes major morphological and structural alterations of the

  14. Chemistry and material science at the cell surface

    Directory of Open Access Journals (Sweden)

    Weian Zhao

    2010-04-01

    Full Text Available Cell surfaces are fertile ground for chemists and material scientists to manipulate or augment cell functions and phenotypes. This not only helps to answer basic biology questions but also has diagnostic and therapeutic applications. In this review, we summarize the most recent advances in the engineering of the cell surface. In particular, we focus on the potential applications of surface engineered cells for 1 targeting cells to desirable sites in cell therapy, 2 programming assembly of cells for tissue engineering, 3 bioimaging and sensing, and ultimately 4 manipulating cell biology.

  15. Cell-Free Synthesis Meets Antibody Production: A Review

    Directory of Open Access Journals (Sweden)

    Marlitt Stech

    2015-01-01

    Full Text Available Engineered antibodies are key players in therapy, diagnostics and research. In addition to full size immunoglobulin gamma (IgG molecules, smaller formats of recombinant antibodies, such as single-chain variable fragments (scFv and antigen binding fragments (Fab, have emerged as promising alternatives since they possess different advantageous properties. Cell-based production technologies of antibodies and antibody fragments are well-established, allowing researchers to design and manufacture highly specific molecular recognition tools. However, as these technologies are accompanied by the drawbacks of being rather time-consuming and cost-intensive, efficient and powerful cell-free protein synthesis systems have been developed over the last decade as alternatives. So far, prokaryotic cell-free systems have been the focus of interest. Recently, eukaryotic in vitro translation systems have enriched the antibody production pipeline, as these systems are able to mimic the natural pathway of antibody synthesis in eukaryotic cells. This review aims to overview and summarize the advances made in the production of antibodies and antibody fragments in cell-free systems.

  16. Synthesis and surface properties of polyurethane modified by polysiloxane

    Institute of Scientific and Technical Information of China (English)

    Linlin FENG; Xingyuan ZHANG; Jiabing DAI; Zhen GE; Jing CHAO; Chenyan BAI

    2008-01-01

    A series of polyurethanes modified by polysiloxane (Si-PU) were synthesized based on 2,4-toluene diisocyanate (TDI), dihydroxybutyl-terminated polydimethylsiloxane (DHPDMS), polytetramethylene glycol (PTMG) and 1,4-butanediol (BDO). Fourier transform infrared spectroscopy analysis showed that DHPDMS had been incorporated into the polyurethane chains. With the increase of DHPDMS content, the water contact angle increased while the surface tension decreased. As the DHPDMS content increases above 5%, both the contact angle and the surface tension tend to approach a constant. The contact angle increases with increasing temperature, and it tends to approach a constant when the temperature is higher than 50℃. The result indicates that Si-PU exhibits good surface and mechanical properties when the DHPDMS content is 5%.

  17. Synthesis and biological evaluation of largazole analogues with modified surface recognition cap groups.

    Science.gov (United States)

    Bhansali, Pravin; Hanigan, Christin L; Perera, Lalith; Casero, Robert A; Tillekeratne, L M Viranga

    2014-10-30

    Several largazole analogues with modified surface recognition cap groups were synthesized and their HDAC inhibitory activities were determined. The C7-epimer 12 caused negligible inhibition of HDAC activity, failed to induce global histone 3 (H3) acetylation in the HCT116 colorectal cancer cell line and demonstrated minimal effect on growth. Although previous studies have shown some degree of tolerance of structural changes at C7 position of largazole, these data show the negative effect of conformational change accompanying change of configuration at this position. Similarly, analogue 16a with D-1-naphthylmethyl side chain at C2 too had negligible inhibition of HDAC activity, failed to induce global histone 3 (H3) acetylation in the HCT116 colorectal cancer cell line and demonstrated minimal effect on growth. In contrast, the L-allyl analogue 16b and the L-1-naphthylmethyl analogue 16c were potent HDAC inhibitors, showing robust induction of global H3 acetylation and significant effect on cell growth. The data suggest that even bulky substituents are tolerated at this position, provided the stereochemistry at C2 is retained. With bulky substituents, inversion of configuration at C2 results in loss of inhibitory activity. The activity profiles of 16b and 16c on Class I HDAC1 vs Class II HDAC6 are similar to those of largazole and, taken together with x-ray crystallography information of HDAC8-largazole complex, may suggest that the C2 position of largazole is not a suitable target for structural optimization to achieve isoform selectivity. The results of these studies may guide the synthesis of more potent and selective HDAC inhibitors.

  18. Synthesis of Branch Fluorinated Cationic Surfactant and Surface Properties

    Directory of Open Access Journals (Sweden)

    Hongke Wu

    2014-01-01

    Full Text Available A novel fluorinated quaternary ammonium salt cationic surfactant N,N,N-trimethyl-2-[[4-[[3,4,4,4-tetrafluoro-2-[1,2,2,2-tetrafluoro-1-(trifluoromethylethyl]-1,3-bis(tri-fluoromethyl-1-buten-1-yl]oxy]-benzoyl]amino]-iodide (FQAS was synthesized successfully, and its structure was characterized by FTIR, 1H-NMR, 19F-NMR, and MS. The surface activities of FQAS and the effect of temperature, electrolyte, and combination with hydrocarbon surfactant were investigated. The results showed that FQAS exhibited excellent surface activity and combination with hydrocarbon surfactant.

  19. Patterned hybrid nanohole array surfaces for cell adhesion and migration.

    Science.gov (United States)

    Westcott, Nathan P; Lou, Yi; Muth, John F; Yousaf, Muhammad N

    2009-10-06

    We report the fabrication of hybrid nanohole array surfaces to study the role of the surface nanoevironment on cell adhesion and cell migration. We use polystyrene beads and reactive ion etching to control the size and the spacing between nanoholes on a tailored self-assembled monolayer inert gold surface. The arrays were characterized by scanning electron microscopy and brightfield microscopy. For cell adhesion studies, cells were seeded to these substrates to study the effect of ligand spacing on cell spreading, stress fiber formation, and focal adhesion structure and size. Finally, comparative cell migration rates were examined on the various nanohole array surfaces using time-lapse microscopy.

  20. The energetics of organic synthesis inside and outside the cell

    Science.gov (United States)

    Amend, Jan P.; LaRowe, Douglas E.; McCollom, Thomas M.; Shock, Everett L.

    2013-01-01

    Thermodynamic modelling of organic synthesis has largely been focused on deep-sea hydrothermal systems. When seawater mixes with hydrothermal fluids, redox gradients are established that serve as potential energy sources for the formation of organic compounds and biomolecules from inorganic starting materials. This energetic drive, which varies substantially depending on the type of host rock, is present and available both for abiotic (outside the cell) and biotic (inside the cell) processes. Here, we review and interpret a library of theoretical studies that target organic synthesis energetics. The biogeochemical scenarios evaluated include those in present-day hydrothermal systems and in putative early Earth environments. It is consistently and repeatedly shown in these studies that the formation of relatively simple organic compounds and biomolecules can be energy-yielding (exergonic) at conditions that occur in hydrothermal systems. Expanding on our ability to calculate biomass synthesis energetics, we also present here a new approach for estimating the energetics of polymerization reactions, specifically those associated with polypeptide formation from the requisite amino acids. PMID:23754809

  1. The energetics of organic synthesis inside and outside the cell.

    Science.gov (United States)

    Amend, Jan P; LaRowe, Douglas E; McCollom, Thomas M; Shock, Everett L

    2013-07-19

    Thermodynamic modelling of organic synthesis has largely been focused on deep-sea hydrothermal systems. When seawater mixes with hydrothermal fluids, redox gradients are established that serve as potential energy sources for the formation of organic compounds and biomolecules from inorganic starting materials. This energetic drive, which varies substantially depending on the type of host rock, is present and available both for abiotic (outside the cell) and biotic (inside the cell) processes. Here, we review and interpret a library of theoretical studies that target organic synthesis energetics. The biogeochemical scenarios evaluated include those in present-day hydrothermal systems and in putative early Earth environments. It is consistently and repeatedly shown in these studies that the formation of relatively simple organic compounds and biomolecules can be energy-yielding (exergonic) at conditions that occur in hydrothermal systems. Expanding on our ability to calculate biomass synthesis energetics, we also present here a new approach for estimating the energetics of polymerization reactions, specifically those associated with polypeptide formation from the requisite amino acids.

  2. Friction Surface Modification by Nanodiamonds of Denotational Synthesis

    Science.gov (United States)

    Davidov, S. V.; Gorlenko, A. O.

    2016-04-01

    The paper deals with the technology and equipment for making a hardened antifriction surface layer of machine elements on the basis of using carbon nanomaterials in order to improve wear resistance. The paper presents the results of tribotechnical tests of pins according to standard techniques using an automated system for research.

  3. Chemical synthesis of Cd-free wide band gap materials for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sankapal, B.R.; Sartale, S.D.; Ennaoui, A. [Hahn-Meitner-Institut, Berlin (Germany). Department of Solar Energy Research; Lokhande, C.D. [Shivaji University, Kolhapur (India). Department of Physics

    2004-07-01

    Chemical methods are nowadays very attractive, since they are relatively simple, low cost and convenient for larger area deposition of thin films. In this paper, we outline our work related to the synthesis and characterization of some wide band gap semiconducting material thin films prepared by using solution methods, namely, chemical bath deposition and successive ionic layer adsorption and reaction (SILAR). The optimum preparative parameters are given and respective structural, surface morphological, compositional, optical, and electrical properties are described. Some materials we used in solar cells as buffer layers and achieved remarkable results, which are summarized. (author)

  4. Synthesis of Diazonium Tetrachloroaurate(III Precursors for Surface Grafting

    Directory of Open Access Journals (Sweden)

    Sabine N. Neal

    2013-12-01

    Full Text Available The synthesis of diazonium tetrachloroaurate(III complexes [R-4-C6H4N≡N]AuCl4 involves protonation of anilines CN-4-C6H4NH2, C8F17-4-C6H4NH2, and C6H13-4-C6H4NH2 with tetrachloroauric acid H[AuCl4] 3H2O in acetonitrile followed by one-electron oxidation using [NO]PF6. FT-IR shows the diazonium stretching frequency at 2277 cm−1 (CN, 2305 cm−1 (C8F17, and 2253 cm−1 (C6H13. Thermogravimetric Analysis (TGA shows the high stabilities of the electron-withdrawing substituents C8F17 and CN compared with the electron-donating substituent C6H13. Residual Gas Analysis (RGA shows the release of molecular nitrogen as the main gas residue among other small molecular weight chlorinated hydrocarbons and chlorobenzene. Temperature-Dependent X-Ray Powder Diffraction (TD-XRD shows the thermal decomposition in C6H13 diffraction patterns at low temperature of 80 °C which supports the TGA and RGA (TGA-MS conclusions. X-ray structure shows N≡N bond distance of approximately 1.10 Å and N≡N-C bond angle of 178°.

  5. Characterization of Cellulose Synthesis in Plant Cells

    Directory of Open Access Journals (Sweden)

    Samaneh Sadat Maleki

    2016-01-01

    Full Text Available Cellulose is the most significant structural component of plant cell wall. Cellulose, polysaccharide containing repeated unbranched β (1-4 D-glucose units, is synthesized at the plasma membrane by the cellulose synthase complex (CSC from bacteria to plants. The CSC is involved in biosynthesis of cellulose microfibrils containing 18 cellulose synthase (CesA proteins. Macrofibrils can be formed with side by side arrangement of microfibrils. In addition, beside CesA, various proteins like the KORRIGAN, sucrose synthase, cytoskeletal components, and COBRA-like proteins have been involved in cellulose biosynthesis. Understanding the mechanisms of cellulose biosynthesis is of great importance not only for improving wood production in economically important forest trees to mankind but also for plant development. This review article covers the current knowledge about the cellulose biosynthesis-related gene family.

  6. Attachment and invasion of Neisseria meningitidis to host cells is related to surface hydrophobicity, bacterial cell size and capsule.

    Directory of Open Access Journals (Sweden)

    Stephanie N Bartley

    Full Text Available We compared exemplar strains from two hypervirulent clonal complexes, strain NMB-CDC from ST-8/11 cc and strain MC58 from ST-32/269 cc, in host cell attachment and invasion. Strain NMB-CDC attached to and invaded host cells at a significantly greater frequency than strain MC58. Type IV pili retained the primary role for initial attachment to host cells for both isolates regardless of pilin class and glycosylation pattern. In strain MC58, the serogroup B capsule was the major inhibitory determinant affecting both bacterial attachment to and invasion of host cells. Removal of terminal sialylation of lipooligosaccharide (LOS in the presence of capsule did not influence rates of attachment or invasion for strain MC58. However, removal of either serogroup B capsule or LOS sialylation in strain NMB-CDC increased bacterial attachment to host cells to the same extent. Although the level of inhibition of attachment by capsule was different between these strains, the regulation of the capsule synthesis locus by the two-component response regulator MisR, and the level of surface capsule determined by flow cytometry were not significantly different. However, the diplococci of strain NMB-CDC were shown to have a 1.89-fold greater surface area than strain MC58 by flow cytometry. It was proposed that the increase in surface area without changing the amount of anchored glycolipid capsule in the outer membrane would result in a sparser capsule and increase surface hydrophobicity. Strain NMB-CDC was shown to be more hydrophobic than strain MC58 using hydrophobicity interaction chromatography and microbial adhesion-to-solvents assays. In conclusion, improved levels of adherence of strain NMB-CDC to cell lines was associated with increased bacterial cell surface and surface hydrophobicity. This study shows that there is diversity in bacterial cell surface area and surface hydrophobicity within N. meningitidis which influence steps in meningococcal pathogenesis.

  7. Controlling cell-cell interactions using surface acoustic waves.

    Science.gov (United States)

    Guo, Feng; Li, Peng; French, Jarrod B; Mao, Zhangming; Zhao, Hong; Li, Sixing; Nama, Nitesh; Fick, James R; Benkovic, Stephen J; Huang, Tony Jun

    2015-01-06

    The interactions between pairs of cells and within multicellular assemblies are critical to many biological processes such as intercellular communication, tissue and organ formation, immunological reactions, and cancer metastasis. The ability to precisely control the position of cells relative to one another and within larger cellular assemblies will enable the investigation and characterization of phenomena not currently accessible by conventional in vitro methods. We present a versatile surface acoustic wave technique that is capable of controlling the intercellular distance and spatial arrangement of cells with micrometer level resolution. This technique is, to our knowledge, among the first of its kind to marry high precision and high throughput into a single extremely versatile and wholly biocompatible technology. We demonstrated the capabilities of the system to precisely control intercellular distance, assemble cells with defined geometries, maintain cellular assemblies in suspension, and translate these suspended assemblies to adherent states, all in a contactless, biocompatible manner. As an example of the power of this system, this technology was used to quantitatively investigate the gap junctional intercellular communication in several homotypic and heterotypic populations by visualizing the transfer of fluorescent dye between cells.

  8. Photoluminescent silicon nanocrystals with chlorosilane surfaces - synthesis and reactivity

    Science.gov (United States)

    Höhlein, Ignaz M. D.; Kehrle, Julian; Purkait, Tapas K.; Veinot, Jonathan G. C.; Rieger, Bernhard

    2014-12-01

    We present a new efficient two-step method to covalently functionalize hydride terminated silicon nanocrystals with nucleophiles. First a reactive chlorosilane layer was formed via diazonium salt initiated hydrosilylation of chlorodimethyl(vinyl)silane which was then reacted with alcohols, silanols and organolithium reagents. With organolithium compounds a side reaction is observed in which a direct functionalization of the silicon surface takes place.We present a new efficient two-step method to covalently functionalize hydride terminated silicon nanocrystals with nucleophiles. First a reactive chlorosilane layer was formed via diazonium salt initiated hydrosilylation of chlorodimethyl(vinyl)silane which was then reacted with alcohols, silanols and organolithium reagents. With organolithium compounds a side reaction is observed in which a direct functionalization of the silicon surface takes place. Electronic supplementary information (ESI) available: Detailed experimental procedures and additional NMR, PL, EDX, DLS and TEM data. See DOI: 10.1039/C4NR05888G

  9. Synthesis and Surface Modification of CdTe Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CdTe nanocrystals were prepared in aqueous solution via the reaction between Cd2+ and NaHTe in the presence of mercaptoacetic acid. Interactions between CdTe nanocrystals and phenylalanine were formed via electrostatic/coordinate self-assembly. The photoluminescence intensity of CdTe nanocrystals was improved obviously. The interaction mechanism was discussed and was considered to be surface passivation.

  10. Surface modification of parylene-N films for the culture of osteoblast-like cells (MG-63)

    Energy Technology Data Exchange (ETDEWEB)

    Liaqat, Usman [Graduate Program of Nano Science and Technology, Yonsei University, 50-Yonsei Ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Ko, Hyuk [Department of Materials Science and Engineering, Yonsei University, 50-Yonsei Ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Suh, Hwal [Graduate Program of Nano Science and Technology, Yonsei University, 50-Yonsei Ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Department of Medical Engineering, College of Medicine, Yonsei University, 50-Yonsei Ro, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of); Lee, Misu [Division of Life Sciences, College of Life Science and Bioengineering, Incheon National University, Incheon 406-772 (Korea, Republic of); Pyun, Jae-Chul, E-mail: jcpyun@yonsei.ac.kr [Department of Materials Science and Engineering, Yonsei University, 50-Yonsei Ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2016-08-15

    Highlights: • Osteoblast-like cells (MG-63) was cultured on differently modified surfaces of parylene films. • Proliferation of MG-63 was observed to be far increased on UV-treated parylene-N film. • The influences of UV-treatment were found out on cell viability, proliferation rate and cell cycle. • The influence was estimated to be negligible on the protein synthesis, cell differentiation. • The UV-treated parylene-N was demonstrated to be effectively used for the culture of MG-63. - Abstract: The influence of microenvironments on the culture of osteoblast-like cells (MG-63) has been investigated using parylene films with different surfaces, such as parylene-N film, UV-modified parylene-N film, functional parylene film with amine groups (parylene-A), and UV-modified parylene-A film. In this work, parylene-N film was found to induce dramatic changes in cell adhesion and cell viability before and after UV-treatment with respect to the culture of osteoblast-like cells (MG-63). The influences of such a chemical environment on cell culture were investigated in relation to the cell proliferation (viability and proliferation rate) and the cell physiology (cell cycle, protein synthesis, and differentiation) of cells grown on parylene-N film, UV-modified parylene-N film, parylene-A film, and UV-modified parylene-A film in comparison with cells grown on a polystyrene surface.

  11. Mycobacterium tuberculosis CwsA overproduction modulates cell division and cell wall synthesis.

    Science.gov (United States)

    Plocinski, P; Martinez, L; Sarva, K; Plocinska, R; Madiraju, M; Rajagopalan, M

    2013-12-01

    We recently showed that two small membrane proteins of Mycobacterium tuberculosis, CwsA and CrgA, interact with each other, and that loss of CwsA in M. smegmatis is associated with defects in the cell division and cell wall synthesis processes. Here we show that CwsA overproduction also affected growth, cell division and cell shape of M. smegmatis and M. tuberculosis. CwsA overproduction in M. tuberculosis led to increased sensitivity to cefsulodin, a penicillin-binding protein (PBP) 1A/1B targeting beta (β) -lactam, but was unaffected by other β-lactams and vancomycin. A M. smegmatis cwsA overexpressing strain showed bulgy cells, increased fluorescent vancomycin staining and altered localization of Wag31-mCherry fusion protein. However, the levels of phosphorylated Wag31, important for optimal peptidoglycan synthesis and growth in mycobacteria, were not affected. Interestingly, CwsA overproduction in E. coli led to the formation of large rounded cells that eventually lysed whereas the overproduction of FtsZ along with CwsA reversed this phenotype. Together, our results emphasize that optimal levels of CwsA are required for regulated cell wall synthesis, hence maintenance of cell shape, and that CwsA likely interacts with and modulates the activities of other cell wall synthetic components including PBPs.

  12. Synthesis and Characterization of PEG-like Structures on Nitinol Surface under ECR-cold-plasma

    Institute of Scientific and Technical Information of China (English)

    YANG Jun; WANG Jianhua; Tong Sheyi

    2005-01-01

    The synthesis and characterization of PEG-like macromolecular structures on Nitinol surface from tri (ethylene glycol) dimethyl-ether under ECR-cold-plasma conditions were discussed. It was demonstrated that based on high-resolution ESCA, ATR-FTIR and contact angle investigations, the deposited PEG-like layers are composed mainly of -CH2-CH2-O- linkages. These structures have a relatively low contact angle. Compared to the unmodified surfaces, the plasma-treated Nitinol surfaces are more hydrophilic. Plasma enhanced coatings of PEG-like layers can prevent Ni ion from releasing, thereby improving the biocompatibility of Nitinol.

  13. Synthesis and texturization processes of (super)-hydrophobic fluorinated surfaces by atmospheric plasma

    CERN Document Server

    Hubert, Julie; Dufour, Thierry; Vandencasteele, Nicolas; Reniers, François; Viville, Pascal; Lazzaroni, Roberto; Raes, M; Terryn, Herman

    2016-01-01

    The synthesis and texturization processes of fluorinated surfaces by means of atmospheric plasma are investigated and presented through an integrated study of both the plasma phase and the resulting material surface. Three methods enhancing the surface hydrophobicity up to the production of super-hydrophobic surfaces are evaluated: (i) the modification of a polytetrafluoroethylene (PTFE) surface, (ii) the plasma deposition of fluorinated coatings and (iii) the incorporation of nanoparticles into those fluorinated films. In all the approaches, the nature of the plasma gas appears to be a crucial parameter for the desired property. Although a higher etching of the PTFE surface can be obtained with a pure helium plasma, the texturization can only be created if O2 is added to the plasma, which simultaneously decreases the total etching. The deposition of CxFy films by a dielectric barrier discharge leads to hydrophobic coatings with water contact angles (WCAs) of 115{\\textdegree}, but only the filamentary argon d...

  14. Inhibition of Interjacent Ribonucleic Acid (26S) Synthesis in Cells Infected by Sindbis Virus

    Science.gov (United States)

    Scheele, Christina M.; Pfefferkorn, E. R.

    1969-01-01

    The interrelationship of viral ribonucleic acid (RNA) and protein synthesis in cells infected by Sindbis virus was investigated. When cultures were treated with puromycin early in the course of infection, the synthesis of interjacent RNA (26S) was preferentially inhibited. A similar result was obtained by shifting cells infected by one temperature-sensitive mutant defective in RNA synthesis from the permissive (29 C) to the nonpermissive (41.5 C) temperature. Under both conditions, the viral RNA produced appeared to be fully active biologically. Once underway, the synthesis of viral RNA in wild-type Sindbis infections did not require concomitant protein synthesis. PMID:5817400

  15. Facile Synthesis of Biocompatible Fluorescent Nanoparticles for Cellular Imaging and Targeted Detection of Cancer Cells.

    Science.gov (United States)

    Tang, Fu; Wang, Chun; Wang, Xiaoyu; Li, Lidong

    2015-11-18

    In this work, we report the facile synthesis of functional core-shell structured nanoparticles with fluorescence enhancement, which show specific targeting of cancer cells. Biopolymer poly-l-lysine was used to coat the silver core with various shell thicknesses. Then, the nanoparticles were functionalized with folic acid as a targeting agent for folic acid receptor. The metal-enhanced fluorescence effect was observed when the fluorophore (5-(and-6)-carboxyfluorescein-succinimidyl ester) was conjugated to the modified nanoparticle surface. Cellular imaging assay of the nanoparticles in folic acid receptor-positive cancer cells showed their excellent biocompatibility and selectivity. The as-prepared functional nanoparticles demonstrate the efficiency of the metal-enhanced fluorescence effect and provide an alternative approach for the cellular imaging and targeting of cancer cells.

  16. Expression of Hepatitis B Virus Surface Antigen Gene in Cultured Cells by Using Recombinant Plasmid Vectors

    OpenAIRE

    Siddiqui, Aleem

    1983-01-01

    By using a new host-vector system, expression of the gene coding for hepatitis B surface antigen has been studied. A subgenomic fragment of cloned hepatitis B viral DNA was inserted into the plasmid vector pSV010. Transfection of COS cells with the recombinant plasmid vector containing hepatitis sequences leads to the synthesis of hepatitis B surface antigen, which is released in the culture medium in the form of 22-nm particles similar to those found in the sera of hepatitis carriers.

  17. Synthesis of tetramethyl ammonium hydroxide by cell diaphragm electrolytic method

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Under the conditions of tetramethyl ammonia chloride (TMAC) used as starting material, Ti-based Dimensionally Stable Anode (DSA), stainless steel used as cathode and Nafion 900 cation membrane as cell diaphragm, this paper studies the synthesis of tetramethyl ammonium hydroxide (TMAH) by cell diaphragm electrolytic method, examining not only the effects of current density, concentration of starting material and cell temperature, on the product purity and current efficiency, but also the effects of electrolyte circulation rate on the service life of Ti-based DSA.The experiment puts forward an optimum processing condition, and experimental findings show that preparing TMAH by using this technique can obtain a current efficiency 74.7 % and get product with a purity greater than 99.9%.

  18. Synthesis of Evolving Cells for Reconfigurable Manufacturing Systems

    Science.gov (United States)

    Padayachee, J.; Bright, G.

    2014-07-01

    The concept of Reconfigurable Manufacturing Systems (RMSs) was formulated due to the global necessity for production systems that are able to economically evolve according to changes in markets and products. Technologies and design methods are under development to enable RMSs to exhibit transformable system layouts, reconfigurable processes, cells and machines. Existing factory design methods and software have not yet advanced to include reconfigurable manufacturing concepts. This paper presents the underlying group technology framework for the design of manufacturing cells that are able to evolve according to a changing product mix by mechanisms of reconfiguration. The framework is based on a Norton- Bass forecast and time variant BOM models. An adaptation of legacy group technology methods is presented for the synthesis of evolving cells and two optimization problems are presented within this context.

  19. Plasma-enhanced synthesis of bactericidal quaternary ammonium thin layers on stainless steel and cellulose surfaces.

    Science.gov (United States)

    Jampala, Soujanya N; Sarmadi, M; Somers, E B; Wong, A C L; Denes, F S

    2008-08-19

    We have investigated bottom-up chemical synthesis of quaternary ammonium (QA) groups exhibiting antibacterial properties on stainless steel (SS) and filter paper surfaces via nonequilibrium, low-pressure plasma-enhanced functionalization. Ethylenediamine (ED) plasma under suitable conditions generated films rich in secondary and tertiary amines. These functional structures were covalently attached to the SS surface by treating SS with O 2 and hexamethyldisiloxane plasma prior to ED plasma treatment. QA structures were formed by reaction of the plasma-deposited amines with hexyl bromide and subsequently with methyl iodide. Structural compositions were examined by electron spectroscopy for chemical analysis and Fourier transform infrared spectroscopy, and surface topography was investigated with atomic force microscopy and water contact angle measurements. Modified SS surfaces exhibited greater than a 99.9% decrease in Staphylococcus aureus counts and 98% in the case of Klebsiella pneumoniae. The porous filter paper surfaces with immobilized QA groups inactivated 98.7% and 96.8% of S. aureus and K. pneumoniae, respectively. This technique will open up a novel way for the synthesis of stable and very efficient bactericidal surfaces with potential applications in development of advanced medical devices and implants with antimicrobial surfaces.

  20. Surface modification of parylene-N films for the culture of osteoblast-like cells (MG-63)

    Science.gov (United States)

    Liaqat, Usman; Ko, Hyuk; Suh, Hwal; Lee, Misu; Pyun, Jae-Chul

    2016-08-01

    The influence of microenvironments on the culture of osteoblast-like cells (MG-63) has been investigated using parylene films with different surfaces, such as parylene-N film, UV-modified parylene-N film, functional parylene film with amine groups (parylene-A), and UV-modified parylene-A film. In this work, parylene-N film was found to induce dramatic changes in cell adhesion and cell viability before and after UV-treatment with respect to the culture of osteoblast-like cells (MG-63). The influences of such a chemical environment on cell culture were investigated in relation to the cell proliferation (viability and proliferation rate) and the cell physiology (cell cycle, protein synthesis, and differentiation) of cells grown on parylene-N film, UV-modified parylene-N film, parylene-A film, and UV-modified parylene-A film in comparison with cells grown on a polystyrene surface.

  1. Response Surface Methodology Approach for the Synthesis of Ethyl Butyrate

    Directory of Open Access Journals (Sweden)

    Vitor Cardoso Aragão

    2011-01-01

    Full Text Available Response surface methodology was used to determine optimum conditions for the esterification of ethanol and butyric acid to produce a flavour ester using immobilized lipase. Various reaction parameters including butyric acid concentration, enzyme concentration, temperature and ethanol/butyric acid molar ratio affecting ethyl butyrate production were investigated using a fractional factorial design 24–1. Based on the results from the first factorial design, all of the variables which were significant in the process were selected to be used in a 24 central composite rotatable design (CCRD. The optimum conditions for the enzymatic reaction were obtained at a 90 mM butyric acid concentration using a 7.7 g/L enzyme concentration at 45 °C and the ethanol/butyric acid molar ratio of 1:1 for 3 h. The esterification percentage, under these conditions, was 87 %.

  2. Electrochemical synthesis and surface characterization of (pyrrole+2-methylfuran) copolymer

    Science.gov (United States)

    Djaouane, Linda; Nessark, Belkacem; Sibous, Lakhdar

    2017-02-01

    Electrochemical copolymerization of pyrrole (Py) and 2-methylfuran (2 MF) was performed on platinum and ITO substrates in acetonitrile/lithium perchlorate solution, using cyclic voltammetry method. The electrochemical behavior of the modified electrode surface by polypyrrole, poly(2-methylfuran) homopolymers and (pyrrole+2-methylfuran) copolymer was characterized by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), UV-visible spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The cyclic voltammetry shows anodic and cathodic peaks which are characteristic of the oxidation and the reduction of the formed films. The electrochemical impedance spectroscopy confirmed the results obtained by cyclic voltammetry. AFM and SEM analyses proved as well that the morphology and the electrochemical properties of the polypyrrole film are modified in the presence of 2-methylfuran.

  3. Assembly fabrication of linkers on glass surface and their effect on DNA synthesis and hybridization

    Institute of Scientific and Technical Information of China (English)

    ShenJiayao; XiaoPengfeng; HouPeng; JiMeiju; SunXiao; HeNongyue

    2003-01-01

    Linkers were assembled on a glass surface based on the hydrolysis and condensation of 3-glycidoxy-propyltrimethoxysilane (GPS). After the assembly of GPS, four approaches were tried to open the ending epoxide group of GPS or to further elongate the linkers. The effect of these approaches on DNA in situ synthesis and hybridization was investigated. For the spacing of the synthesis initiation sites, the wettability of the support and the length of the linking group that attaches the initiation site to the surface have direct influences on the yield of coupling reactions and the subsequent hybridization events. X-ray photoelectron spectroscopy (XPS) and mean contact angles of deionized water of the above slides were measured to assess the linker's characteristics in each procedure. It was proved that the glass slides were successfully modified and became excellent supports for the oligonucleotides synthesis. In addition, it proved best for the in situ oligonueleotides synthesis that a glass slide was in turn treated with ethylenediamine, glutaradehyde, ethanolamine and sodium borohydride solution at ambient temperature after silanized with GPS.

  4. Nanofabrication of Nonfouling Surfaces for Micropatterning of Cell and Microtissue

    Directory of Open Access Journals (Sweden)

    Hidenori Otsuka

    2010-08-01

    Full Text Available Surface engineering techniques for cellular micropatterning are emerging as important tools to clarify the effects of the microenvironment on cellular behavior, as cells usually integrate and respond the microscale environment, such as chemical and mechanical properties of the surrounding fluid and extracellular matrix, soluble protein factors, small signal molecules, and contacts with neighboring cells. Furthermore, recent progress in cellular micropatterning has contributed to the development of cell-based biosensors for the functional characterization and detection of drugs, pathogens, toxicants, and odorants. In this regards, the ability to control shape and spreading of attached cells and cell-cell contacts through the form and dimension of the cell-adhesive patches with high precision is important. Commitment of stem cells to different specific lineages depends strongly on cell shape, implying that controlled microenvironments through engineered surfaces may not only be a valuable approach towards fundamental cell-biological studies, but also of great importance for the design of cell culture substrates for tissue engineering. To develop this kind of cellular microarray composed of a cell-resistant surface and cell attachment region, micropatterning a protein-repellent surface is important because cellular adhesion and proliferation are regulated by protein adsorption. The focus of this review is on the surface engineering aspects of biologically motivated micropatterning of two-dimensional surfaces with the aim to provide an introductory overview described in the literature. In particular, the importance of non-fouling surface chemistries is discussed.

  5. Identification of Cell Wall Synthesis Regulatory Genes Controlling Biomass Characteristics and Yield in Rice (Oryza Sativa)

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Zhaohua PEng [Mississippi State University; Ronald, Palmela [UC-Davis; Wang, Guo-Liang [The Ohio State University

    2013-04-26

    This project aims to identify the regulatory genes of rice cell wall synthesis pathways using a cell wall removal and regeneration system. We completed the gene expression profiling studies following the time course from cell wall removal to cell wall regeneration in rice suspension cells. We also completed, total proteome, nuclear subproteome and histone modification studies following the course from cell wall removal and cell wall regeneration process. A large number of differentially expressed regulatory genes and proteins were identified. Meanwhile, we generated RNAi and over-expression transgenic rice for 45 genes with at least 10 independent transgenic lines for each gene. In addition, we ordered T-DNA and transposon insertion mutants for 60 genes from Korea, Japan, and France and characterized the mutants. Overall, we have mutants and transgenic lines for over 90 genes, exceeded our proposed goal of generating mutants for 50 genes. Interesting Discoveries a) Cell wall re-synthesis in protoplasts may involve a novel cell wall synthesis mechanism. The synthesis of the primary cell wall is initiated in late cytokinesis with further modification during cell expansion. Phragmoplast plays an essential role in cell wall synthesis. It services as a scaffold for building the cell plate and formation of a new cell wall. Only one phragmoplast and one new cell wall is produced for each dividing cell. When the cell wall was removed enzymatically, we found that cell wall re-synthesis started from multiple locations simultaneously, suggesting that a novel mechanism is involved in cell wall re-synthesis. This observation raised many interesting questions, such as how the starting sites of cell wall synthesis are determined, whether phragmoplast and cell plate like structures are involved in cell wall re-synthesis, and more importantly whether the same set of enzymes and apparatus are used in cell wall re-synthesis as during cytokinesis. Given that many known cell wall

  6. Growth of fibroblasts and endothelial cells on wettability gradient surfaces

    NARCIS (Netherlands)

    Ruardy, TG; Moorlag, HE; Schakenraad, JM; VanderMei, HC; Busscher, HJ

    1997-01-01

    The growth, spreading, and shape of human skin fibroblasts (PK 84) and human umbilical cord endothelial cells on dichlorodimethylsilane (DDS) and dimethyloctadecylchlorosilane (DOGS) gradient surfaces were investigated in the presence of serum proteins. Gradient surfaces were prepared on glass using

  7. Using Intracardiac Vectorcardiographic Loop for Surface ECG Synthesis

    Directory of Open Access Journals (Sweden)

    G. Carrault

    2008-09-01

    Full Text Available Current cardiac implantable devices offer improved processing power and recording capabilities. Some of these devices already provide basic telemonitoring features that may help to reduce health care expenditure. A challenge is posed in particular for the telemonitoring of the patient's cardiac electrical activity. Indeed, only intracardiac electrograms (EGMs are acquired by the implanted device and these signals are difficult to analyze directly by clinicians. In this paper, we propose a patient-specific method to synthesize the surface electrocardiogram (ECG from a set of EGM signals, based on a 3D representation of the cardiac electrical activity and principal component analysis (PCA. The results, in the case of sinus rhythm, show a correlation coefficient between the real ECG and the synthesized ECG of about 0.85. Moreover, the application of the proposed method to the patients who present an abnormal heart rhythm exhibits promising results, especially for characterizing the bundle branch blocs. Finally, in order to evaluate the behavior of our procedure in some practical situations, the quality of the ECG reconstruction is studied as a function of the number of EGM electrodes provided by the CIDs.

  8. Synthesis and tuning of gold nanorods with surface plasmon resonance

    Science.gov (United States)

    Shajari, Daryush; Bahari, Ali; Gill, Pooria; Mohseni, Mojtaba

    2017-02-01

    Gold nanostructures in general and gold nanorods in particular due to their plasmon resonance has been employed for many applications, such as biosensors. For the biosensors uses, gold nanorods remain popular and reproducibility of them is the most important and critical. In the present work we used six different CTAB (Hexadecyltrimethylammonium bromide) products and one BDAC (Benzyldimethylhexadecylammonium chloride) with varying silver nitrate concentration in the seed-mediated growth of gold nanostructures. We synthesized gold nanorods with varying aspect ratio up to 5.5 with a longitudinal surface plasmon resonance peak from 670 to 950 nm. We obtained excellent rod-shape gold nanostructures witch were reliable and reproducible with our method based on common seed-mediated growth. The synthesized nanostructures were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). Here, we report our method in more detail as a user-friendly guide for the production of gold nanorods and tuning of their aspect ratios.

  9. Biomimetic self-cleaning surfaces: synthesis, mechanism and applications.

    Science.gov (United States)

    Xu, Quan; Zhang, Wenwen; Dong, Chenbo; Sreeprasad, Theruvakkattil Sreenivasan; Xia, Zhenhai

    2016-09-01

    With millions of years of natural evolution, organisms have achieved sophisticated structures, patterns or textures with complex, spontaneous multifunctionality. Among all the fascinating characteristics observed in biosystems, self-cleaning ability is regarded as one of the most interesting topics in biomimicry because of its potential applications in various fields such as aerospace, energy conversion and biomedical and environmental protection. Recently, in-depth studies have been carried out on various compelling biostructures including lotus leaves, shark skins, butterfly wings and gecko feet. To understand and mimic their self-cleaning mechanisms in artificial structures, in this article, recent progress in self-cleaning techniques is discussed and summarized. Based on the underlying self-cleaning mechanisms, the methods are classified into two categories: self-cleaning with water and without water. The review gives a succinct account of the detailed mechanisms and biomimetic processes applied to create artificial self-cleaning materials and surfaces, and provides some examples of cutting-edge applications such as anti-reflection, water repellence, self-healing, anti-fogging and micro-manipulators. The prospectives and directions of future development are also briefly proposed.

  10. Plasma-enhanced synthesis of surfaces that kill bacteria on contact

    Science.gov (United States)

    Jampala, Soujanya Naga

    High incidences of microbial contamination and infections are a major concern in all existing and evolving technologies of medicine and biology. The propensity towards infections is directly related to bacterial colonization and biofilms on surfaces. This dissertation presents the development of surfaces that can kill bacteria on contact by using cold plasma technology. Quaternary ammonium (QA) groups are known to exhibit antibacterial characteristics in water-based environments. To overcome the limitations of residual toxicity, alternative strategies involving covalent attachment of QA groups to metallic and cellulosic surfaces have been developed. Low pressure, non-equilibrium plasma-enhanced functionalization and subsequent ex situ chemical reactions were designed for step-by-step "bottom-up" chemical synthesis of QA groups covalently anchored to surfaces. The plasma processes under selected discharge parameters generated structure- and functionality-controlled crosslinked networks of macromolecular layers with high concentrations of reactive amine groups. Subsequent derivatization of the plasma-deposited films with alkyl halides yielded surface-bound QA groups rendering surfaces with high bactericidal efficacy against Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumoniae. Stainless steel and cotton surfaces sequentially treated with ethylene diamine plasma, n-hexyl bromide and methyl iodide exhibited at least 99.9% and 98% kill of S. aureus and K. pneumoniae respectively. The influence of chemical architecture of QA groups with different alkyl substituents on the efficacy of bactericidal surfaces was quantified. Results from this work will permit the development of novel plasma-aided technologies for the synthesis of antibacterial surfaces with potential biomedical applications. The cold plasma approach can be used on any solid material surfaces including polymers, metals, ceramics and semiconductors.

  11. Estradiol increases mucus synthesis in bronchial epithelial cells.

    Directory of Open Access Journals (Sweden)

    Anthony Tam

    Full Text Available Airway epithelial mucus hypersecretion and mucus plugging are prominent pathologic features of chronic inflammatory conditions of the airway (e.g. asthma and cystic fibrosis and in most of these conditions, women have worse prognosis compared with male patients. We thus investigated the effects of estradiol on mucus expression in primary normal human bronchial epithelial cells from female donors grown at an air liquid interface (ALI. Treatment with estradiol in physiological ranges for 2 weeks caused a concentration-dependent increase in the number of PAS-positive cells (confirmed to be goblet cells by MUC5AC immunostaining in ALI cultures, and this action was attenuated by estrogen receptor beta (ER-β antagonist. Protein microarray data showed that nuclear factor of activated T-cell (NFAT in the nuclear fraction of NHBE cells was increased with estradiol treatment. Estradiol increased NFATc1 mRNA and protein in ALI cultures. In a human airway epithelial (1HAE0 cell line, NFATc1 was required for the regulation of MUC5AC mRNA and protein. Estradiol also induced post-translational modification of mucins by increasing total fucose residues and fucosyltransferase (FUT-4, -5, -6 mRNA expression. Together, these data indicate a novel mechanism by which estradiol increases mucus synthesis in the human bronchial epithelium.

  12. One-step synthesis of silver nanoparticles, nanorods, and nanowires on the surface of DNA network.

    Science.gov (United States)

    Wei, Gang; Zhou, Hualan; Liu, Zhiguo; Song, Yonghai; Wang, Li; Sun, Lanlan; Li, Zhuang

    2005-05-12

    Here, we describe a one-step synthesis of silver nanoparticles, nanorods, and nanowires on DNA network surface in the absence of surfactant. Silver ions were first adsorbed onto the DNA network and then reduced in sodium borohydride solution. Silver nanoparticles, nanorods, and nanowires were formed by controlling the size of pores of the DNA network. The diameter of the silver nanoparticles and the aspect ratio of the silver nanorods and nanowires can be controlled by adjusting the DNA concentration and reduction time.

  13. Calreticulin: Roles in Cell-Surface Protein Expression

    Directory of Open Access Journals (Sweden)

    Yue Jiang

    2014-09-01

    Full Text Available In order to perform their designated functions, proteins require precise subcellular localizations. For cell-surface proteins, such as receptors and channels, they are able to transduce signals only when properly targeted to the cell membrane. Calreticulin is a multi-functional chaperone protein involved in protein folding, maturation, and trafficking. However, evidence has been accumulating that calreticulin can also negatively regulate the surface expression of certain receptors and channels. In these instances, depletion of calreticulin enhances cell-surface expression and function. In this review, we discuss the role of calreticulin with a focus on its negative effects on the expression of cell-surface proteins.

  14. A mass spectrometric-derived cell surface protein atlas.

    Science.gov (United States)

    Bausch-Fluck, Damaris; Hofmann, Andreas; Bock, Thomas; Frei, Andreas P; Cerciello, Ferdinando; Jacobs, Andrea; Moest, Hansjoerg; Omasits, Ulrich; Gundry, Rebekah L; Yoon, Charles; Schiess, Ralph; Schmidt, Alexander; Mirkowska, Paulina; Härtlová, Anetta; Van Eyk, Jennifer E; Bourquin, Jean-Pierre; Aebersold, Ruedi; Boheler, Kenneth R; Zandstra, Peter; Wollscheid, Bernd

    2015-01-01

    Cell surface proteins are major targets of biomedical research due to their utility as cellular markers and their extracellular accessibility for pharmacological intervention. However, information about the cell surface protein repertoire (the surfaceome) of individual cells is only sparsely available. Here, we applied the Cell Surface Capture (CSC) technology to 41 human and 31 mouse cell types to generate a mass-spectrometry derived Cell Surface Protein Atlas (CSPA) providing cellular surfaceome snapshots at high resolution. The CSPA is presented in form of an easy-to-navigate interactive database, a downloadable data matrix and with tools for targeted surfaceome rediscovery (http://wlab.ethz.ch/cspa). The cellular surfaceome snapshots of different cell types, including cancer cells, resulted in a combined dataset of 1492 human and 1296 mouse cell surface glycoproteins, providing experimental evidence for their cell surface expression on different cell types, including 136 G-protein coupled receptors and 75 membrane receptor tyrosine-protein kinases. Integrated analysis of the CSPA reveals that the concerted biological function of individual cell types is mainly guided by quantitative rather than qualitative surfaceome differences. The CSPA will be useful for the evaluation of drug targets, for the improved classification of cell types and for a better understanding of the surfaceome and its concerted biological functions in complex signaling microenvironments.

  15. A mass spectrometric-derived cell surface protein atlas.

    Directory of Open Access Journals (Sweden)

    Damaris Bausch-Fluck

    Full Text Available Cell surface proteins are major targets of biomedical research due to their utility as cellular markers and their extracellular accessibility for pharmacological intervention. However, information about the cell surface protein repertoire (the surfaceome of individual cells is only sparsely available. Here, we applied the Cell Surface Capture (CSC technology to 41 human and 31 mouse cell types to generate a mass-spectrometry derived Cell Surface Protein Atlas (CSPA providing cellular surfaceome snapshots at high resolution. The CSPA is presented in form of an easy-to-navigate interactive database, a downloadable data matrix and with tools for targeted surfaceome rediscovery (http://wlab.ethz.ch/cspa. The cellular surfaceome snapshots of different cell types, including cancer cells, resulted in a combined dataset of 1492 human and 1296 mouse cell surface glycoproteins, providing experimental evidence for their cell surface expression on different cell types, including 136 G-protein coupled receptors and 75 membrane receptor tyrosine-protein kinases. Integrated analysis of the CSPA reveals that the concerted biological function of individual cell types is mainly guided by quantitative rather than qualitative surfaceome differences. The CSPA will be useful for the evaluation of drug targets, for the improved classification of cell types and for a better understanding of the surfaceome and its concerted biological functions in complex signaling microenvironments.

  16. Theory of back-surface-field solar cells

    Science.gov (United States)

    Vonroos, O.

    1979-01-01

    Report describes simple concise theory of back-surface-field (BSF) solar cells (npp + junctions) based on Shockley's depletion-layer approximation and cites superiority of two-junction devices over conventional unijunction cells.

  17. Principles of Bacterial Cell-Size Determination Revealed by Cell-Wall Synthesis Perturbations

    Directory of Open Access Journals (Sweden)

    Carolina Tropini

    2014-11-01

    Full Text Available Although bacterial cell morphology is tightly controlled, the principles of size regulation remain elusive. In Escherichia coli, perturbation of cell-wall synthesis often results in similar morphologies, making it difficult to deconvolve the complex genotype-phenotype relationships underlying morphogenesis. Here we modulated cell width through heterologous expression of sequences encoding the essential enzyme PBP2 and through sublethal treatments with drugs that inhibit PBP2 and the MreB cytoskeleton. We quantified the biochemical and biophysical properties of the cell wall across a wide range of cell sizes. We find that, although cell-wall chemical composition is unaltered, MreB dynamics, cell twisting, and cellular mechanics exhibit systematic large-scale changes consistent with altered chirality and a more isotropic cell wall. This multiscale analysis enabled identification of distinct roles for MreB and PBP2, despite having similar morphological effects when depleted. Altogether, our results highlight the robustness of cell-wall synthesis and physical principles dictating cell-size control.

  18. Microfluidic-Based Synthesis of Hydrogel Particles for Cell Microencapsulation and Cell-Based Drug Delivery

    Directory of Open Access Journals (Sweden)

    Jiandi Wan

    2012-04-01

    Full Text Available Encapsulation of cells in hydrogel particles has been demonstrated as an effective approach to deliver therapeutic agents. The properties of hydrogel particles, such as the chemical composition, size, porosity, and number of cells per particle, affect cellular functions and consequently play important roles for the cell-based drug delivery. Microfluidics has shown unparalleled advantages for the synthesis of polymer particles and been utilized to produce hydrogel particles with a well-defined size, shape and morphology. Most importantly, during the encapsulation process, microfluidics can control the number of cells per particle and the overall encapsulation efficiency. Therefore, microfluidics is becoming the powerful approach for cell microencapsulation and construction of cell-based drug delivery systems. In this article, I summarize and discuss microfluidic approaches that have been developed recently for the synthesis of hydrogel particles and encapsulation of cells. I will start by classifying different types of hydrogel material, including natural biopolymers and synthetic polymers that are used for cell encapsulation, and then focus on the current status and challenges of microfluidic-based approaches. Finally, applications of cell-containing hydrogel particles for cell-based drug delivery, particularly for cancer therapy, are discussed.

  19. Signal enhancement of surface enhanced Raman scattering and surface enhanced resonance Raman scattering using in situ colloidal synthesis in microfluidics.

    Science.gov (United States)

    Wilson, Rab; Bowden, Stephen A; Parnell, John; Cooper, Jonathan M

    2010-03-01

    We demonstrate the enhanced analytical sensitivity of both surface enhanced Raman scattering (SERS) and surface enhanced resonance Raman scattering (SERRS) responses, resulting from the in situ synthesis of silver colloid in a microfluidic flow structure, where both mixing and optical interrogation were integrated on-chip. The chip-based sensor was characterized with a model Raman active label, rhodamine-6G (R6G), and had a limit of detection (LOD) of ca. 50 fM (equivalent to single molecule detection). The device was also used for the determination of the natural pigment, scytonemin, from cyanobacteria (as an analogue for extraterrestrial life existing in extreme environments). The observed LOD of approximately 10 pM (ca. microfluidic system than those measured using the same experimental parameters, with colloid synthesized off-chip, under quiescent conditions.

  20. Surface roughness and wettability of wool fabrics loaded with silver nanoparticles: Influence of synthesis and application methods

    NARCIS (Netherlands)

    Barani, H.; Montazer, M.; Calvimontes, A.; Dutschk, V.

    2013-01-01

    Hydrophilization of wool fabrics was performed by silver nanoparticles with different surface charge using three different methods: exhausting, pad–dry–cure and in situ synthesis. Dynamic wetting measurements and surface topography analysis were used to evaluate surface changes on wool fabrics. The

  1. Controlled chemical and morphological surface modifications via pulsed plasma polymerizations: Synthesis of ultrahydrophobic surfaces

    Science.gov (United States)

    Qiu, Haibo

    The RF plasma polymerization of saturated linear and cyclic perfluoroalkane monomers and vinyl acetic acid were studied in this dissertation. Film chemical compositions, deposition rates, surface wettabilities and morphologies were characterized as functions of various plasma processing conditions. Large progressive changes in chemical compositions with sequential variations in plasma duty cycle were demonstrated in polymerization of both perfluoroalkane and vinyl acetic acid monomers. As anticipated, polymer films obtained from the perfluorocarbon monomers exhibited a general trend towards more linear structures with decreasing plasma duty cycles. However, completely unexpectedly, ultrahydrophobic films were obtained from some of these monomers under restricted duty cycle and power input conditions. SEM and XPS characterizations revealed that a rough, fibrous-like surface morphology is responsible for this ultrahydrophobicity, as opposed to unusual chemical compositions. The growth of the fibrous surface is believed to arise from nucleation and hillock-like growth patterns on selectively activated sites of the growing polymer film. Surface mobility of plasma generated reactive species apparently plays an important role in the growth of the fibrous ultrahydrophobic surfaces, as shown by substrate temperature studies. Additionally, the present study revealed a number of interesting new observations of significant differences in the chemical compositions and deposition rates of polymer films obtained from the diverse range of perfluorocarbon monomers employed in this work. The ultrahydrophobic fluorocarbon films discovered in this investigation were evaluated for use in several biomaterial applications. The results obtained show excellent marine antifouling properties for these surfaces, as documented in ocean testing experiments. These surfaces have also been shown to be useful in controlling protein and peptide surface adsorptions, as well as in the inflammatory

  2. Molecularly engineered surfaces for cell biology: from static to dynamic surfaces.

    Science.gov (United States)

    Gooding, J Justin; Parker, Stephen G; Lu, Yong; Gaus, Katharina

    2014-04-01

    Surfaces with a well-defined presentation of ligands for receptors on the cell membrane can serve as models of the extracellular matrix for studying cell adhesion or as model cell surfaces for exploring cell-cell contacts. Because such surfaces can provide exquisite control over, for example, the density of these ligands or when the ligands are presented to the cell, they provide a very precise strategy for understanding the mechanisms by which cells respond to external adhesive cues. In the present feature article, we present an overview of the basic biology of cell adhesion before discussing surfaces that have a static presentation of immobile ligands. We outline the biological information that such surfaces have given us, before progressing to recently developed switchable surfaces and surfaces that mimic the lipid bilayer, having adhesive ligands that can move around the membrane and be remodeled by the cell. Finally, the feature article closes with some of the biological information that these new types of surfaces could provide.

  3. Synthesis and characterization of large specific surface area nanostructured amorphous silica materials.

    Science.gov (United States)

    Marquez-Linares, Francisco; Roque-Malherbe, Rolando M A

    2006-04-01

    Large specific surface area materials attract wide attention because of their applications in adsorption, catalysis, and nanotechnology. In the present study, we describe the synthesis and characterization of nanostructured amorphous silica materials. These materials were obtained by means of a modification of the Stobe-Fink-Bohn (SFB) method. The morphology and essential features of the synthesized materials have been studied using an automated surface area and pore size analyzer and scanning electron microscopy. The existence of a micro/mesoporous structure in the obtained materials has been established. It was also found that the obtained particle packing materials show large specific surface area up to 1,600 m2/g. (To our best knowledge, there is no any reported amorphous silica material with such a higher specific surface area.) The obtained materials could be useful in the manufacture of adsorbents, catalyst supports, and other nanotechnological applications.

  4. Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications

    Science.gov (United States)

    Wu, Wei; Wu, Zhaohui; Yu, Taekyung; Jiang, Changzhong; Kim, Woo-Sik

    2015-04-01

    This review focuses on the recent development and various strategies in the preparation, microstructure, and magnetic properties of bare and surface functionalized iron oxide nanoparticles (IONPs); their corresponding biological application was also discussed. In order to implement the practical in vivo or in vitro applications, the IONPs must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of IONPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The new functionalized strategies, problems and major challenges, along with the current directions for the synthesis, surface functionalization and bioapplication of IONPs, are considered. Finally, some future trends and the prospects in these research areas are also discussed.

  5. Progress in the synthesis and characterization of magnetite nanoparticles with amino groups on the surface

    Energy Technology Data Exchange (ETDEWEB)

    Durdureanu-Angheluta, A.; Dascalu, A.; Fifere, A.; Coroaba, A.; Pricop, L. [Centre of Advanced Research in Bionanoconjugates and Biopolymers, ' ' Petru Poni' ' Institute of Macromolecular Chemistry of Romanian Academy, 41A Aleea Grigore Ghica Voda, 700487 Iasi (Romania); Chiriac, H. [National Institute of Research and Development in Technical Physics, 700050 Iasi (Romania); Tura, V. [Faculty of Physics, ' ' Al. I. Cuza' ' University, B-dul Carol I, no. 11, 700506 Iasi (Romania); Pinteala, M., E-mail: pinteala@icmpp.ro [Centre of Advanced Research in Bionanoconjugates and Biopolymers, ' ' Petru Poni' ' Institute of Macromolecular Chemistry of Romanian Academy, 41A Aleea Grigore Ghica Voda, 700487 Iasi (Romania); Simionescu, B.C. [Centre of Advanced Research in Bionanoconjugates and Biopolymers, ' ' Petru Poni' ' Institute of Macromolecular Chemistry of Romanian Academy, 41A Aleea Grigore Ghica Voda, 700487 Iasi (Romania); Department of Natural and Synthetic Polymers, ' ' Gh. Asachi' ' Technical University of Iasi, 73 Mangeron Blvd, 700050 Iasi (Romania)

    2012-05-15

    This manuscript deals with the synthesis of new hydrophilic magnetite particles by employing a two-step method: in the first step magnetite particles with hydrophobic shell formed in presence of oleic acid-oleylamine complex through a synthesis in mass, without solvent, in a mortar with pestle were obtained; while in the second step the hydrophobic shell was interchanged with an aminosilane monomer. The influence of the Fe{sup 2+}/Fe{sup 3+} molar ratio on the dimension of the particles of high importance for their potential applications was carefully investigated. This paper, also presents an alternative method of synthesis of new core-shell magnetite particles and the complete study of their structure and morphology by FT-IR, XPS, TGA, ESEM and TEM techniques. The rheological properties and magnetization analysis of high importance for magnetic particles were also investigated. - Highlights: Black-Right-Pointing-Pointer Magnetite particles are superparamagnetic materials. Black-Right-Pointing-Pointer Magnetite has significant role in nanotechnology due to surface properties and applicability in physical and chemical processes. Black-Right-Pointing-Pointer We used an ecological method of synthesis, a reaction in mass, without solvent, in a mortar with pestle. Black-Right-Pointing-Pointer We prepared hydrophilic magnetite particles, precursors for biomedical applications.

  6. Developmental expression of a cell surface protein involved in sea urchin skeleton formation. [Strongylocentrotus purpuratus; Lytechinus pictus

    Energy Technology Data Exchange (ETDEWEB)

    Farach, M.C.; Valdizan, M.; Park, H.R.; Decker, G.L.; Lennarz, W.J.

    1986-05-01

    The authors have previously used a monoclonal antibody (1223) to identify a 130 Kd cell surface protein involved in skeleton formation is sea urchin embryos. In the current study the authors have examined the expression of the 1223 antigen over the course of development of embryos of two species, Strongylocentrotus purpuratus and Lytechinus pictus. The 130 Kd protein is detected in S. purp eggs on immunoblots. Labeling with (/sup 3/H) leucine and immunoaffinity chromatography show that it also is synthesized shortly after fertilization. Immunofluroescence reveals that at this early stage the 1223 antigen is uniformly distributed on all of the cells. Synthesis decreases to a minimum by the time of hatching (18 h), as does the total amount of antigen present in the embryo. A second period of synthesis commences at the mesenchyme blastula stage, when the spicule-forming primary mesenchyme cells (PMCs) have appeared. During this later stage, synthesis and cell surface expression are restricted to the PMCs. In contrast to S. purp., in L. pictus the 130 Kd protein does not appear until the PMCs are formed. Hybrid embryos demonstrate a pattern of expression of the maternal species. These results suggest that early expression of 1223 antigen in S. purp. is due to utilization of maternal transcripts present in the egg. In both species later expression in PMCs appears to be the result of cell-type specific synthesis, perhaps encoded by embryonic transcripts.

  7. Synthesis, surface characterization, and biointeraction studies of low-surface energy side-chain polyetherurethanes

    Science.gov (United States)

    Porter, Stephen Christopher

    1999-10-01

    New segmented polyetherurethanes (PEUs) with low surface energy hydrocarbon and fluorocarbon side-chains attached to the polymer hard segments were synthesized. The surface chemistry of solvent cast polymer films was studied using X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and dynamic contact angle (DCA) measurements. Increases in the overall density and length of the alkyl side-chains within the PEUs resulted in greater side-chain concentrations at the polymer surface. PEUs bearing long alkyl (> C10 ) and perfluorocarbon side-chains were found to posses surfaces with highly enriched side-chain concentrations relative to the bulk polymer. In PEUs with significant side-chain surface enrichment, the relatively polar hard segment blocks were shown to reside in high concentrations just below the side-chain enriched surface layer. Furthermore, DCA measurements demonstrated that the surface of the alkyl side-chain PEUs did not undergo significant rearrangement when placed into an aqueous environment, whereas the surface of a hard segment model polymer bearing C18 sidechains (PEU-C18-HS) did. Hydrogen bonding within the PEUs was examined using FTIR and was shown to be disrupted by the addition of side-chains; an effect dependent on the density but not on the length of the side-chains. Heteropolymer blends comprised of mixtures of high side-chain density and side-chain free PEUs were compared with homopolymers having the same overall side-chain concentration as the blends. Significantly more surface enrichment of side-chains was found in the heteropolymer blends whereas hydrogen bonding nearly the same as in the homopolymers. Adsorption of native and delipidized human serum albumin (HSA) from pure solution and blood plasma; the elutabilty of adsorbed HSA; and static platelet adhesion to plasma preadsorbed surfaces, were all examined on alkyl side-chain PEUs. Several polymers with high C18 side-chain densities displayed increased

  8. Cell surface expression and function of the macromolecular C1 complex on the surface of human monocytes

    Directory of Open Access Journals (Sweden)

    Kinga K Hosszu

    2012-03-01

    Full Text Available The synthesis of the subunits of the C1 complex (C1q, C1s, C1r, and its regulator C1 inhibitor (C1-Inh by human monocytes has been previously established. However, surface expression of these molecules by monocytes has not been shown. Using flow cytometry and antigen-capture ELISA, we show here for the first time that, in addition to C1q, PB monocytes and the monocyte-derived U937 cells express C1s and C1r, as well as Factor B and C1-Inh on their surface. C1s and C1r immunoprecipitated with C1q, suggesting that at least some of the C1q on these cells is part of the C1 complex. Furthermore, the C1 complex on U937 cells was able to trigger complement activation via the classical pathway. The presence of C1-Inh may ensure that an unwarranted autoactivation of the C1 complex does not take place. Since C1-Inh closely monitors the activation of the C1 complex in a sterile or infectious inflammatory environment, further elucidation of the role of C1 complex is crucial to dissect its function in monocyte, DC and T cell activities, and its implications in host defense and tolerance.

  9. Cell Surface-based Sensing with Metallic Nanoparticles

    OpenAIRE

    Jiang, Ziwen; Le, Ngoc D. B.; Gupta, Akash; Rotello, Vincent M.

    2015-01-01

    Metallic nanoparticles provide versatile scaffolds for biosensing applications. In this review, we focus on the use of metallic nanoparticles for cell surface sensings. Examples of the use of both specific recognition and array-based “chemical nose” approaches to cell surface sensing will be discussed.

  10. Epigallocatechin gallate inhibits HBV DNA synthesis in a viral replication - inducible cell line

    Institute of Scientific and Technical Information of China (English)

    Wei He; Li-Xia Li; Qing-Jiao Liao; Chun-Lan Liu; Xu-Lin Chen

    2011-01-01

    AIM: To analyze the antiviral mechanism of Epigallocatechin gallate (EGCG) against hepatitis B virus (HBV) replication. METHODS: In this research, the HBV-replicating cell line HepG2.117 was used to investigate the antiviral mechanism of EGCG. Cytotoxicity of EGCG was analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Hepatitis B virus e antigen (HBeAg) and hepatitis B virus surface antigen (HBsAg) in the supernatant were detected by enzyme-linked immunosorbent assay. Precore mRNA and pregenomic RNA (pgRNA) levels were determined by semi-quantitative reverse transcription polymerase chain reaction (PCR) assay. The effect of EGCG on HBV core promoter activity was measured by dual luciferase reporter assay. HBV covalently closed circular DNA and replicative intermediates of DNA were quantified by real-time PCR assay. RESULTS: When HepG2.117 cells were grown in the presence of EGCG, the expression of HBeAg was suppressed, however, the expression of HBsAg was not affected. HBV precore mRNA level was also downregulated by EGCG, while the transcription of precore mRNA was not impaired. The synthesis of both HBV covalently closed circular DNA and replicative intermediates of DNA were reduced by EGCG treatment to a similar extent, however, HBV pgRNA transcripted from chromosome-integrated HBV genome was not affected by EGCG treatment, indicating that EGCG targets only replicative intermediates of DNA synthesis. CONCLUSION: In HepG2.117 cells, EGCG inhibits HBV replication by impairing HBV replicative intermediates of DNA synthesis and such inhibition results in reduced production of HBV covalently closed circular DNA.

  11. Simultaneous light-directed synthesis of mirror-image microarrays in a photochemical reaction cell with flare suppression.

    Science.gov (United States)

    Sack, Matej; Kretschy, Nicole; Rohm, Barbara; Somoza, Veronika; Somoza, Mark M

    2013-09-17

    The use of photolabile protecting groups is a versatile and well-established means of synthesizing high complexity microarrays of biopolymers, such as nucleic acids and peptides, for high-throughput analysis. The synthesis takes place in a photochemical reaction cell which positions the microarray substrate at the focus of the optical system delivering the light and which can be connected to a fluidics system which delivers appropriate reagents to the surface in synchrony with the light exposure. Here we describe a novel photochemical reaction cell which allows for the simultaneous synthesis of microarrays on two substrates. The reaction cell positions both substrates within the limited depth-of-focus of the optical system while maintaining the necessary reagent flow conditions. The resulting microarrays are mirror images of each other but otherwise essentially identical. The new reaction cell doubles the throughput of microarray synthesis without increasing the consumption of reagents. In addition, a secondary flow chamber behind the reaction cell can be filled with an absorbent and index-matching fluid to eliminate reflections from light exiting the reaction cell assembly, greatly reducing unintended light exposure that reduces the sequence fidelity of the microarray probes.

  12. Chemical synthesis of carbohydrates and their surface immobilization: a brief introduction.

    Science.gov (United States)

    Werz, Daniel B

    2012-01-01

    For all carbohydrate microarrays, two important prerequisites are necessary: the carbohydrate of interest has to be obtained either by isolation from natural sources, enzymatic or chemical synthesis; an immobilization of the carbohydrate at the surface of the chip has to be achieved. This chapter provides a very brief overview of the chemical synthesis of carbohydrates (creation of building blocks, assembly, and deprotection) and of immobilization techniques. Numerous methods are known to construct oligosaccharides by chemical methods. A typical monosaccharide building block, used in oligosaccharide assembly, is equipped with different protecting groups that mask the hydroxyl and amine groups. In general, a good leaving group at the anomeric center that can easily be activated is mandatory; especially trichloroacetimidates, phosphates, and thioethers have been widely used for the creation of glycosidic bonds. After the complete assembly of the oligosaccharide, a global deprotection of all permanent protecting groups affords the desired target structure with free hydroxyl groups. Linkers, which were introduced during the synthesis, must often be modified at the end to create appropriate functionalities for surface immobilization.

  13. FABRICATION AND BIOCOMPATIBILITY OF CELL OUTER MEMBRANE MIMETIC SURFACES

    Institute of Scientific and Technical Information of China (English)

    Ming-ming Zong; Yong-kuan Gong

    2011-01-01

    The surface design used for improving biocompatibility is one of the most important issues for the fabrication of medical devices. For mimicking the ideal surface structure of cell outer membrane, a large number of polymers bearing phosphorylcholine (PC) groups have been employed to modify the surfaces of biomaterials and medical devices. It has been demonstrated that the biocompatibility of the modified materials whose surface is required to interact with a living organism has been obviously improved by introducing PC groups. In this review, the fabrication strategies of cell outer membrane mimetic surfaces and their resulted biocompatibilities were summarized.

  14. Mapping cell surface adhesion by rotation tracking and adhesion footprinting

    Science.gov (United States)

    Li, Isaac T. S.; Ha, Taekjip; Chemla, Yann R.

    2017-03-01

    Rolling adhesion, in which cells passively roll along surfaces under shear flow, is a critical process involved in inflammatory responses and cancer metastasis. Surface adhesion properties regulated by adhesion receptors and membrane tethers are critical in understanding cell rolling behavior. Locally, adhesion molecules are distributed at the tips of membrane tethers. However, how functional adhesion properties are globally distributed on the individual cell’s surface is unknown. Here, we developed a label-free technique to determine the spatial distribution of adhesive properties on rolling cell surfaces. Using dark-field imaging and particle tracking, we extract the rotational motion of individual rolling cells. The rotational information allows us to construct an adhesion map along the contact circumference of a single cell. To complement this approach, we also developed a fluorescent adhesion footprint assay to record the molecular adhesion events from cell rolling. Applying the combination of the two methods on human promyelocytic leukemia cells, our results surprisingly reveal that adhesion is non-uniformly distributed in patches on the cell surfaces. Our label-free adhesion mapping methods are applicable to the variety of cell types that undergo rolling adhesion and provide a quantitative picture of cell surface adhesion at the functional and molecular level.

  15. Attachment of human primary osteoblast cells to modified polyethylene surfaces.

    Science.gov (United States)

    Poulsson, Alexandra H C; Mitchell, Stephen A; Davidson, Marcus R; Johnstone, Alan J; Emmison, Neil; Bradley, Robert H

    2009-04-09

    Ultra-high-molecular-weight polyethylene (UHMWPE) has a long history of use in medical devices, primarily for articulating surfaces due to its inherent low surface energy which limits tissue integration. To widen the applications of UHMWPE, the surface energy can be increased. The increase in surface energy would improve the adsorption of proteins and attachment of cells to allow tissue integration, thereby allowing UHMWPE to potentially be used for a wider range of implants. The attachment and function of human primary osteoblast-like (HOB) cells to surfaces of UHMWPE with various levels of incorporated surface oxygen have been investigated. The surface modification of the UHMWPE was produced by exposure to a UV/ozone treatment. The resulting surface chemistry was studied using X-ray photoelectron spectroscopy (XPS), and the topography and surface structure were probed by atomic force microscopy (AFM) and scanning electron microscopy (SEM), which showed an increase in surface oxygen from 11 to 26 atom % with no significant change to the surface topography. The absolute root mean square roughness of both untreated and UV/ozone-treated surfaces was within 350-450 nm, and the water contact angles decreased with increasing oxygen incorporation, i.e., showing an increase in surface hydrophilicity. Cell attachment and functionality were assessed over a 21 day period for each cell-surface combination studied; these were performed using SEM and the alamarBlue assay to study cell attachment and proliferation and energy-dispersive X-ray (EDX) analysis to confirm extracellular mineral deposits, and total protein assay to examine the intra- and extracellular protein expressed by the cells. HOB cells cultured for 21 days on the modified UHMWPE surfaces with 19 and 26 atom % oxygen incorporated showed significantly higher cell densities compared to cells cultured on tissue culture polystyrene (TCPS) from day 3 onward. This indicated that the cells attached and proliferated more

  16. Touching Textured Surfaces: Cells in Somatosensory Cortex Respond Both to Finger Movement and to Surface Features

    Science.gov (United States)

    Darian-Smith, Ian; Sugitani, Michio; Heywood, John; Karita, Keishiro; Goodwin, Antony

    1982-11-01

    Single neurons in Brodmann's areas 3b and 1 of the macaque postcentral gyrus discharge when the monkey rubs the contralateral finger pads across a textured surface. Both the finger movement and the spatial pattern of the surface determine this discharge in each cell. The spatial features of the surface are represented unambiguously only in the responses of populations of these neurons, and not in the responses of the constituent cells.

  17. Polypeptide synthesis in alphavirus-infected Aedes albopictus cells during the establishment of persistent infection.

    Science.gov (United States)

    Richardson, M A; Boulton, R W; Raghow, R S; Dalgarno, L

    1980-01-01

    Polypeptide synthesis was examined in mosquito cells during the establishment of a persistent infection with two alphaviruses, Ross River virus (RRV) and Semliki Forest virus (SFV), and in vertebrate cells cytopathically-infected with the same viruses. In Aedes albopictus cell, RRV reached peak titres at 34--48 hours p.i. At 12 hours 85 per cent of cells assayed as infected by infective centre assay; by 48 hours when persistence was established, virus production was reduced and less than 5 per cent of cells assayed as infected. There was no shut-down of host polypeptide synthesis during infection. Viral polypeptide synthesis was maximal between 10 and 24 hours p.i. The major viral polypeptides labelled were nucleocapsid protein and envelope protein(s). The precursor polypeptide p95 which was prominent in infected BHK cells was not detected in mosquito cells. Similar results were obtained on SFV infection. During the establishment of persistence there was a coordinate decline in the synthesis of RRV polypeptides, reaching undetectable levels by 72 hours p.i. Subculturing persitently-infected cells led to a small increase in viral polypeptide synthesis and virus titre. In contrast, during RRV growth in BHK celos host protein synthesis was severly inhibited and by 9--11 hours p.i. virus-specific polypeptide synthesis represented more than 90 per cent of total protein synthetic activity.

  18. Biomaterial surface proteomic signature determines interaction with epithelial cells.

    Science.gov (United States)

    Abdallah, Mohamed-Nur; Tran, Simon D; Abughanam, Ghada; Laurenti, Marco; Zuanazzi, David; Mezour, Mohamed A; Xiao, Yizhi; Cerruti, Marta; Siqueira, Walter L; Tamimi, Faleh

    2017-03-01

    Cells interact with biomaterials indirectly through extracellular matrix (ECM) proteins adsorbed onto their surface. Accordingly, it could be hypothesized that the surface proteomic signature of a biomaterial might determine its interaction with cells. Here, we present a surface proteomic approach to test this hypothesis in the specific case of biomaterial-epithelial cell interactions. In particular, we determined the surface proteomic signature of different biomaterials exposed to the ECM of epithelial cells (basal lamina). We revealed that the biomaterial surface chemistry determines the surface proteomic profile, and subsequently the interaction with epithelial cells. In addition, we found that biomaterials with surface chemistries closer to that of percutaneous tissues, such as aminated PMMA and aminated PDLLA, promoted higher selective adsorption of key basal lamina proteins (laminins, nidogen-1) and subsequently improved their interactions with epithelial cells. These findings suggest that mimicking the surface chemistry of natural percutaneous tissues can improve biomaterial-epithelial integration, and thus provide a rationale for the design of improved biomaterial surfaces for skin regeneration and percutaneous medical devices.

  19. Bio-synthesis of gold nanoparticles by human epithelial cells, in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Larios-Rodriguez, E; Rangel-Ayon, C; Herrera-Urbina, R [Departamento de Ingenieria Quimica y Metalurgia, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora, C.P. 83000 (Mexico); Castillo, S J [Departamento de Investigacion en Fisica, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora, C.P. 83000 (Mexico); Zavala, G, E-mail: elarios@polimeros.uson.mx [Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico)

    2011-09-02

    Healthy epithelial cells, in vivo, have the ability to synthesize gold nanoparticles when aqueous tetrachloroauric acid is made to react with human skin. Neither a reducing agent nor a protecting chemical is needed for this bio-synthesis method. The first indication of gold nanoparticle formation is the staining of the skin, which turns deep purple. Stereoscopic optical micrographs of human skin tissue in contact with aqueous tetrachloroauric acid clearly show the staining of the epithelial cells. The UV-Vis spectrum of these epithelial cells shows an absorption band with a maximum at 553 nm. This absorption peak is within the wavelength region where the surface plasmon resonance (SPR) band of aqueous colloidal gold exhibits a maximum. Transmission electron micrographs show that gold nanoparticles synthesized by epithelial cells have sizes between 1 and 100 nm. The electron diffraction pattern of these nanoparticles reveals a crystalline structure whose interplanar distances correspond to fcc metallic gold. Transmission electron micrographs of ultra-thin (70 nm thick) slices of epithelial cells clearly and undoubtedly demonstrate that gold nanoparticles are inside the cell. According to high resolution transmission electron micrographs of intracellular single gold nanoparticles, they have the shape of a polyhedron.

  20. Synthesis of titanium dioxide and zinc oxide nanowires for excitonic solar cells

    Science.gov (United States)

    Boercker, Janice Elaine

    Dye-sensitized, quantum-dot sensitized, quantum-dot, and hybrid organic/inorganic solar cells are promising excitonic photovoltaic devices for the generation of low cost, carbon free energy. Wide-band gap semiconductor nanowire photoanodes have the potential to increase the efficiencies of these excitonic solar cells. Controlling and tailoring the dimensions of the nanowires (i.e. nanowire height, diameter, and planar number density) for each solar cell type is important for efficiency improvement. Obtaining such control will require a detailed and fundamental understanding of the nanowire growth process. Towards this end, the synthesis of TiO2 and ZnO nanowire films in aqueous solutions was studied. Anatase TiO2 nanowire films were grown on flexible titanium foil substrates using a three step hydrothermal synthesis. First, the top surface of the titanium foil was transformed to Na2Ti2O 4(OH)2 nanotubes through hydrothermal oxidation in NaOH. Next, the Na2Ti2O4(OH)2 nanotubes were converted to H2Ti2O4(OH)2 nanotubes by ion exchange. Finally, the H2Ti2O 4(OH)2 nanotubes were converted to polycrystalline anatase nanowires through a topotactic transformation. The film morphology evolution, crystal structure transformations, and growth mechanism were examined in detail. Dye-sensitized solar cells (DSSCs) were assembled from these TiO 2 nanowire films. Transient photocurrent and photovoltage spectroscopies were used to measure the electron transport and recombination rates in these solar cells. Compared to TiO2 nanoparticle DSSCs the electron collection efficiency in the TiO2 nanowire DSSCs was increased due to decreased electron recombination. However, the electron transport in the nanowire DSSCs was similar to that of TiO2 nanoparticle DSSCs. The synthesis of ZnO nanowires from aqueous solutions of methenamine (HMT) and zinc nitrate hexahydrate on substrates was studied in detail. A ZnO nanowire growth mechanism was proposed which predicts that the precursor is a zinc

  1. Cytotoxicity Induced by Engineered Silver Nanocrystallites is Dependent on Surface Coatings and Cell Types

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, Anil K [ORNL; Pelletier, Dale A [ORNL; Wang, Wei [ORNL; Morrell-Falvey, Jennifer L [ORNL; Doktycz, Mitchel John [ORNL

    2012-01-01

    Due to their unique antimicrobial properties silver nanocrystallites have garnered substantial recognition and are used extensively in biomedical applications such as wound dressing, surgical instruments and as bone substitute material. They are also released into unintended locations such as the environment or biosphere. Therefore it is imperative to understand the potential interactions, fate and transport of nanoparticles with environmental biotic systems. Although numerous factors including the composition, size, shape, surface charge and capping molecule of nanoparticles are known to influence the cell cytotoxicity, our results demonstrate for the first time that surface coatings are a major determinant in eliciting the potential cytotoxicity and cell interactions of silver nanoparticles. In the present investigation, silver nanocrystallites with nearly uniform size and shape distribution but with different surface coatings, imparting overall high negativity to high positivity, were synthesized. These nanoparticles were poly (diallyldimethylammonium) chloride-Ag, biogenic-Ag, colloidal-Ag (uncoated) and oleate-Ag with zeta potentials +45 5 mV, -12 2 mV, -42 5 mV and -45 5 mV respectively; the particles were thoroughly purified so as to avoid false cytotoxicity interpretations. A systematic investigation on the cytotoxic effects, cellular response and membrane damage caused by these four different silver nanoparticles were evaluated using multiple toxicity measurements on mouse macrophage (RAW-264.7) and lung epithelial (C-10) cell lines. From a toxicity perspective, our results clearly indicated that the cytotoxicity was depend on various factors such as synthesis procedure, surface coat or surface charge and the cell-type for the different silver nanoparticles that were investigated. Poly (diallyldimethylammonium) chloride -Ag was found to be the most toxic, followed by biogenic-Ag and oleate-Ag, whereas uncoated-Ag was found to be least toxic to both

  2. A Facile Synthesis of Silver-Coated Composite Particles by Swelling Surface Method

    Institute of Scientific and Technical Information of China (English)

    LIU Jun-Bing; LI Neng; WANG Si-Zhen; ZHANG Jian-Hui; WANG Zhen-Lin

    2005-01-01

    @@ We report a facile and rapid method for fabrication of composite particles consisting of a polystyrene (PS) core and a uniform silver shell.The process involves the PS colloid surface swelling, the anchoring of silver ions and nanoparticles onto the surfaces, and the subsequent growth of metal seeds in a short period.The present approach has the advantages of simplicity and high efficiency.The TEM images show the morphology of the obtained PS core-silver shell particles, and their chemical composition and crystallinity are analysed by x-ray diffraction.To our knowledge, this is the first study based on swelling PS surface for synthesis of silver-coated PS particles and may be implemented for preparing other metal-coated PS particles.

  3. A cell surface chondroitin sulfate proteoglycan, immunologically related to CD44, is involved in type I collagen-mediated melanoma cell motility and invasion

    DEFF Research Database (Denmark)

    Faassen, A E; Schrager, J A; Klein, D J

    1992-01-01

    motility and invasion. The current studies evaluate the role of a cell surface chondroitin sulfate proteoglycan (CSPG) in the adhesion, motility, and invasive behavior of a highly metastatic mouse melanoma cell line (K1735 M4) on type I collagen matrices. By blocking mouse melanoma cell production of CSPG...... with p-nitrophenyl beta-D-xylopyranoside (beta-D-xyloside), a compound that uncouples chondroitin sulfate from CSPG core protein synthesis, we observed a corresponding decrease in melanoma cell motility on type I collagen and invasive behavior into type I collagen gels. Melanoma cell motility on type I...... collagen could also be inhibited by removing cell surface chondroitin sulfate with chondroitinase. In contrast, type I collagen-mediated melanoma cell adhesion and spreading were not affected by either beta-D-xyloside or chondroitinase treatments. These results suggest that mouse melanoma CSPG...

  4. Cell multiplication following partial enzymatic removal of surface coat.

    Science.gov (United States)

    Wyroba, E

    1978-08-01

    Treatment of Paramecium aurelia with trypsin or pronase (1 mg per 10(5) cells, at 0 to 4 degrees C) partially removes the surface coat and modifies significantly multiplication of cells. The division rate after 24 hours of cultivation is diminished approximately twice in the case of pronase-treated cells and 1.5 for tyrpsin-digested ciliates as compared with the control. On the second day the division rate increases rapidly and number of cell divisions exceeds the values observed in the control. After 72 hours of cultivation the division rate in both untreated and enzyme-treated cells is almost the same. It is concluded that the observed inhibition of cell fission results from the enzymatic removal of the surface coat--the integrity of this surface coat seems to be necessary in the process of cell division. The influence of environmental factors on the rate of growth is presented.

  5. A molecular smart surface for spatio-temporal studies of cell mobility.

    Directory of Open Access Journals (Sweden)

    Eun-ju Lee

    Full Text Available Active migration in both healthy and malignant cells requires the integration of information derived from soluble signaling molecules with positional information gained from interactions with the extracellular matrix and with other cells. How a cell responds and moves involves complex signaling cascades that guide the directional functions of the cytoskeleton as well as the synthesis and release of proteases that facilitate movement through tissues. The biochemical events of the signaling cascades occur in a spatially and temporally coordinated manner then dynamically shape the cytoskeleton in specific subcellular regions. Therefore, cell migration and invasion involve a precise but constantly changing subcellular nano-architecture. A multidisciplinary effort that combines new surface chemistry and cell biological tools is required to understand the reorganization of cytoskeleton triggered by complex signaling during migration. Here we generate a class of model substrates that modulate the dynamic environment for a variety of cell adhesion and migration experiments. In particular, we use these dynamic substrates to probe in real-time how the interplay between the population of cells, the initial pattern geometry, ligand density, ligand affinity and integrin composition affects cell migration and growth. Whole genome microarray analysis indicates that several classes of genes ranging from signal transduction to cytoskeletal reorganization are differentially regulated depending on the nature of the surface conditions.

  6. A molecular smart surface for spatio-temporal studies of cell mobility.

    Science.gov (United States)

    Lee, Eun-ju; Luo, Wei; Chan, Eugene W L; Yousaf, Muhammad N

    2015-01-01

    Active migration in both healthy and malignant cells requires the integration of information derived from soluble signaling molecules with positional information gained from interactions with the extracellular matrix and with other cells. How a cell responds and moves involves complex signaling cascades that guide the directional functions of the cytoskeleton as well as the synthesis and release of proteases that facilitate movement through tissues. The biochemical events of the signaling cascades occur in a spatially and temporally coordinated manner then dynamically shape the cytoskeleton in specific subcellular regions. Therefore, cell migration and invasion involve a precise but constantly changing subcellular nano-architecture. A multidisciplinary effort that combines new surface chemistry and cell biological tools is required to understand the reorganization of cytoskeleton triggered by complex signaling during migration. Here we generate a class of model substrates that modulate the dynamic environment for a variety of cell adhesion and migration experiments. In particular, we use these dynamic substrates to probe in real-time how the interplay between the population of cells, the initial pattern geometry, ligand density, ligand affinity and integrin composition affects cell migration and growth. Whole genome microarray analysis indicates that several classes of genes ranging from signal transduction to cytoskeletal reorganization are differentially regulated depending on the nature of the surface conditions.

  7. SEPARATION OF CELL POPULATIONS BY SUPER-PARAMAGNETIC PARTICLES WITH CONTROLLED SURFACE FUNCTIONALITY

    Directory of Open Access Journals (Sweden)

    Lootsik M. D.

    2014-02-01

    Full Text Available The recognition and isolation of specific mammalian cells by the biocompatible polymer coated super-paramagnetic particles with determined surface functionality were studied. The method of synthesis of nanoscaled particles on a core of iron III oxide (Fe2O3, magemit coated with a polymer shell containing reactive oligoperoxide groups for attachment of ligands is described. By using the developed superparamagnetic particles functionalized with peanut agglutinin (PNA we have separated the sub-populations of PNA+ and PNA– cells from ascites of murine Nemeth-Kellner lymphoma. In another type of experiment, the particles were opsonized with proteins of the fetal calf serum that improved biocompatibility of the particles and their ingestion by cultivated murine macrophages J774.2. Macrophages loaded with the particles were effeciently separated from the particles free cells by using the magnet. Thus, the developed surface functionalized superparamagnetic particles showed to be a versatile tool for cell separation independent on the mode of particles’ binding with cell surface or their engulfment by the targeted cells.

  8. Surface-modified gold nanorods for specific cell targeting

    Science.gov (United States)

    Wang, Chan-Ung; Arai, Yoshie; Kim, Insun; Jang, Wonhee; Lee, Seonghyun; Hafner, Jason H.; Jeoung, Eunhee; Jung, Deokho; Kwon, Youngeun

    2012-05-01

    Gold nanoparticles (GNPs) have unique properties that make them highly attractive materials for developing functional reagents for various biomedical applications including photothermal therapy, targeted drug delivery, and molecular imaging. For in vivo applications, GNPs need to be prepared with very little or negligible cytotoxicitiy. Most GNPs are, however, prepared using growth-directing surfactants such as cetyl trimethylammonium bromide (CTAB), which are known to have considerable cytotoxicity. In this paper, we describe an approach to remove CTAB to a non-toxic concentration. We optimized the conditions for surface modification with methoxypolyethylene glycol thiol (mPEG), which replaced CTAB and formed a protective layer on the surface of gold nanorods (GNRs). The cytotoxicities of pristine and surface-modified GNRs were measured in primary human umbilical vein endothelial cells and human cell lines derived from hepatic carcinoma cells, embryonic kidney cells, and thyroid papillary carcinoma cells. Cytotoxicity assays revealed that treating cells with GNRs did not significantly affect cell viability except for thyroid papillary carcinoma cells. Thyroid cancer cells were more susceptible to residual CTAB, so CTAB had to be further removed by dialysis in order to use GNRs for thyroid cell targeting. PEGylated GNRs are further modified to present monoclonal antibodies that recognize a specific surface marker, Na-I symporter, for thyroid cells. Antibody-conjugated GNRs specifically targeted human thyroid cells in vitro.

  9. DNA replication initiation, doubling of rate of phospholipid synthesis, and cell division in Escherichia coli.

    OpenAIRE

    Joseleau-Petit, D; Képès, F; Peutat, L; D'Ari, R; Képès, A

    1987-01-01

    In synchronized culture of Escherichia coli, the specific arrest of phospholipid synthesis (brought about by glycerol starvation in an appropriate mutant) did not affect the rate of ongoing DNA synthesis but prevented the initiation of new rounds. The initiation block did not depend on cell age at the time of glycerol removal, which could be before, during, or after the doubling in the rate of phospholipid synthesis (DROPS) and as little as 10 min before the expected initiation. We conclude t...

  10. C8-structured carbon quantum dots: Synthesis, blue and green double luminescence, and origins of surface defects

    Science.gov (United States)

    Xifang, Chen; Wenxia, Zhang; Qianjin, Wang; Jiyang, Fan

    Carbon quantum dots (CQDs) have attracted great attention in the past few years due to their low cytotoxicity, exploited various synthesis methods, unexampled abundance of raw materials on earth, and robust near-infrared to near-UV luminescence. Carbon nanoparticles have applications in biological labeling, delivery of drugs and biological molecules into cells, and light emitting diodes and lasing. CQDs generally exist as nanodiamonds or graphite quantum dots according to previous research reports. In this study, we report the first synthesis of the third-allotrope CQDs through carbonization of sucrose and study their luminescence properties. These CQDs have a body-centered cubic structure and each lattice point is composed of eight atoms which form a sub-cube (so called C8 crystal structure). High-resolution transmission electron microscopy and X-ray diffraction confirm the C8 structure of the synthesized carbon nanocrystallites with an average size of 2 nm. The C8 CQDs exhibit double-band luminescence with two peaks centered at around 432 and 520 nm. The study based on the photoluminescence, UV-Vis absorption, Fourier-transform infrared, and X-ray photoelectron spectroscopies reveals that the green emission originates from the C=O related surface defect.

  11. Interaction of Epithelial Cells with Surfaces and Surfaces Decorated by Molecules

    CERN Document Server

    Martini, Daniele; Beil, Michael; Paust, T; Huang, C; Moosmann, M; Jin, J; Heiler, T; Gröger, R; Schimmel, Thomas; Walheim, Stefan

    2013-01-01

    A detailed understanding of the interface between living cells and substrate materials is of rising importance in many fields of medicine, biology and biotechnology. Cells at interfaces often form epithelia. The physical barrier that they form is one of their main functions. It is governed by the properties of the networks forming the cytoskeleton systems and by cell-to-cell contacts. Different substrates with varying surface properties modify the migration velocity of the cells. On the one hand one can change the materials composition. Organic and inorganic materials induce differing migration velocities in the same cell system. Within the same class of materials, a change of the surface stiffness or of the surface energy modifies the migration velocity, too. For our cell adhesion studies a variety of different, homogeneous substrates were used (polymers, bio-polymers, metals, oxides). In addition, an effective lithographic method, Polymer Blend Lithography (PBL), is reported, to produce patterned Self-Assem...

  12. Interactions between endothelial progenitor cells (EPC) and titanium implant surfaces.

    Science.gov (United States)

    Ziebart, Thomas; Schnell, Anne; Walter, Christian; Kämmerer, Peer W; Pabst, Andreas; Lehmann, Karl M; Ziebart, Johanna; Klein, Marc O; Al-Nawas, Bilal

    2013-01-01

    Endothelial cells play an important role in peri-implant angiogenesis during early bone formation. Therefore, interactions between endothelial progenitor cells (EPCs) and titanium dental implant surfaces are of crucial interest. The aim of our in vitro study was to investigate the reactions of EPCs in contact with different commercially available implant surfaces. EPCs from buffy coats were isolated by Ficoll density gradient separation. After cell differentiation, EPC were cultured for a period of 7 days on different titanium surfaces. The test surfaces varied in roughness and hydrophilicity: acid-etched (A), sand-blasted-blasted and acid-etched (SLA), hydrophilic A (modA), and hydrophilic SLA (modSLA). Plastic and fibronectin-coated plastic surfaces served as controls. Cell numbers and morphology were analyzed by confocal laser scanning microscopy. Secretion of vascular endothelial growth factor (VEGF)-A was measured by enzyme-linked immunosorbent assay and expressions of iNOS and eNOS were investigated by real-time polymerase chain reaction. Cell numbers were higher in the control groups compared to the cells of titanium surfaces. Initially, hydrophilic titanium surfaces (modA and modSLA) showed lower cell numbers than hydrophobic surfaces (A and SLA). After 7 days smoother surfaces (A and modA) showed increased cell numbers compared to rougher surfaces (SLA and modSLA). Cell morphology of A, modA, and control surfaces was characterized by a multitude of pseudopodia and planar cell soma architecture. SLA and modSLA promoted small and plump cell soma with little quantity of pseudopodia. The lowest VEGF level was measured on A, the highest on modSLA. The highest eNOS and iNOS expressions were found on modA surfaces. The results of this study demonstrate that biological behaviors of EPCs can be influenced by different surfaces. The modSLA surface promotes an undifferentiated phenotype of EPCs that has the ability to secrete growth factors in great quantities. In

  13. Osteoblastlike cell adhesion on titanium surfaces modified by plasma nitriding.

    Science.gov (United States)

    da Silva, Jose Sandro Pereira; Amico, Sandro Campos; Rodrigues, Almir Olegario Neves; Barboza, Carlos Augusto Galvao; Alves, Clodomiro; Croci, Alberto Tesconi

    2011-01-01

    The aim of this study was to evaluate the characteristics of various titanium surfaces modified by cold plasma nitriding in terms of adhesion and proliferation of rat osteoblastlike cells. Samples of grade 2 titanium were subjected to three different surface modification processes: polishing, nitriding by plasma direct current, and nitriding by cathodic cage discharge. To evaluate the effect of the surface treatment on the cellular response, the adhesion and proliferation of osteoblastlike cells (MC3T3) were quantified and the results were analyzed by Kruskal-Wallis and Friedman statistical tests. Cellular morphology was observed by scanning electron microscopy. There was more MC3T3 cell attachment on the rougher surfaces produced by cathodic cage discharge compared with polished samples (P Plasma nitriding improves titanium surface roughness and wettability, leading to osteoblastlike cell adhesion.

  14. High resolution imaging of surface patterns of single bacterial cells

    Energy Technology Data Exchange (ETDEWEB)

    Greif, Dominik; Wesner, Daniel [Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld (Germany); Regtmeier, Jan, E-mail: jan.regtmeier@physik.uni-bielefeld.de [Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld (Germany); Anselmetti, Dario [Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld (Germany)

    2010-09-15

    We systematically studied the origin of surface patterns observed on single Sinorhizobium meliloti bacterial cells by comparing the complementary techniques atomic force microscopy (AFM) and scanning electron microscopy (SEM). Conditions ranged from living bacteria in liquid to fixed bacteria in high vacuum. Stepwise, we applied different sample modifications (fixation, drying, metal coating, etc.) and characterized the observed surface patterns. A detailed analysis revealed that the surface structure with wrinkled protrusions in SEM images were not generated de novo but most likely evolved from similar and naturally present structures on the surface of living bacteria. The influence of osmotic stress to the surface structure of living cells was evaluated and also the contribution of exopolysaccharide and lipopolysaccharide (LPS) by imaging two mutant strains of the bacterium under native conditions. AFM images of living bacteria in culture medium exhibited surface structures of the size of single proteins emphasizing the usefulness of AFM for high resolution cell imaging.

  15. Yeast surface display of dehydrogenases in microbial fuel-cells.

    Science.gov (United States)

    Gal, Idan; Schlesinger, Orr; Amir, Liron; Alfonta, Lital

    2016-12-01

    Two dehydrogenases, cellobiose dehydrogenase from Corynascus thermophilus and pyranose dehydrogenase from Agaricus meleagris, were displayed for the first time on the surface of Saccharomyces cerevisiae using the yeast surface display system. Surface displayed dehydrogenases were used in a microbial fuel cell and generated high power outputs. Surface displayed cellobiose dehydrogenase has demonstrated a midpoint potential of -28mV (vs. Ag/AgCl) at pH=6.5 and was used in a mediator-less anode compartment of a microbial fuel cell producing a power output of 3.3μWcm(-2) using lactose as fuel. Surface-displayed pyranose dehydrogenase was used in a microbial fuel cell and generated high power outputs using different substrates, the highest power output that was achieved was 3.9μWcm(-2) using d-xylose. These results demonstrate that surface displayed cellobiose dehydrogenase and pyranose dehydrogenase may successfully be used in microbial bioelectrochemical systems.

  16. Synthesis and decomposition of ammonia on transition metal surfaces: bond-order-conservation-Morse-potential analysis

    Science.gov (United States)

    Shustorovich, Evgeny; Bell, Alexis T.

    1991-12-01

    The mechanism of ammonia synthesis and decomposition on transition metal surfaces has been analyzed using the BOC-MP (bond-order-conservation-Morse-potential) method. The analysis is based on calculations of the heats of chemisorption, Q, for all adsorbed species and activation barriers, Δ E∗, for all elementary reactions believed to be involved in the reaction N 2 + H 2 NH 3 over Pt(111), Ru(001), Fe(110), Re(001). The relevant experimental values of Q and Δ E∗ agree well with the BOC-MP estimates. It is shown that along the periodic series Pt, Ru, Fe, Re, the dissociation activation barriers decrease but the recombination and desorption barriers increase. In particular, we find that on all the surfaces the largest activation barrier corresponds to the recombinative desorption 2N s → N 2. This step is projected to be the rate-determining process for ammonia decomposition, and Pt is projected to be the most efficient catalyst. For the dissociation N 2 → 2N s, we find that the activation barrier sharply increases in the order Re ⩽ Fe ≪ Pt, which makes Pt surfaces incapable of catalyzing ammonia synthesis. These and other BOC-MP projections are in agreement with the results of mechanistic studies on Pt(111), Ru(001) and Fe(110).

  17. Nanoridges that characterize the surface morphology of flowers require the synthesis of cutin polyester.

    Science.gov (United States)

    Li-Beisson, Yonghua; Pollard, Mike; Sauveplane, Vincent; Pinot, Franck; Ohlrogge, John; Beisson, Fred

    2009-12-22

    Distinctive nanoridges on the surface of flowers have puzzled plant biologists ever since their discovery over 75 years ago. Although postulated to help attract insect pollinators, the function, chemical nature, and ontogeny of these surface nanostructures remain uncertain. Studies have been hampered by the fact that no ridgeless mutants have been identified. Here, we describe two mutants lacking nanoridges and define the biosynthetic pathway for 10,16-dihydroxypalmitate, a major cutin monomer in nature. Using gene expression profiling, two candidates for the formation of floral cutin were identified in the model plant Arabidopsis thaliana: the glycerol-3-phosphate acyltransferase 6 (GPAT6) and a member of a cytochrome P450 family with unknown biological function (CYP77A6). Plants carrying null mutations in either gene produced petals with no nanoridges and no cuticle could be observed by either scanning or transmission electron microscopy. A strong reduction in cutin content was found in flowers of both mutants. In planta overexpression suggested GPAT6 preferentially uses palmitate derivatives in cutin synthesis. Comparison of cutin monomer profiles in knockouts for CYP77A6 and the fatty acid omega-hydroxylase CYP86A4 provided genetic evidence that CYP77A6 is an in-chain hydroxylase acting subsequently to CYP86A4 in the synthesis of 10,16-dihydroxypalmitate. Biochemical activity of CYP77A6 was demonstrated by production of dihydroxypalmitates from 16-hydroxypalmitate, using CYP77A6-expressing yeast microsomes. These results define the biosynthetic pathway for an abundant and widespread monomer of the cutin polyester, show that the morphology of floral surfaces depends on the synthesis of cutin, and identify target genes to investigate the function of nanoridges in flower biology.

  18. Multijunction Solar Cell Technology for Mars Surface Applications

    Science.gov (United States)

    Stella, Paul M.; Mardesich, Nick; Ewell, Richard C.; Mueller, Robert L.; Endicter, Scott; Aiken, Daniel; Edmondson, Kenneth; Fetze, Chris

    2006-01-01

    Solar cells used for Mars surface applications have been commercial space qualified AM0 optimized devices. Due to the Martian atmosphere, these cells are not optimized for the Mars surface and as a result operate at a reduced efficiency. A multi-year program, MOST (Mars Optimized Solar Cell Technology), managed by JPL and funded by NASA Code S, was initiated in 2004, to develop tools to modify commercial AM0 cells for the Mars surface solar spectrum and to fabricate Mars optimized devices for verification. This effort required defining the surface incident spectrum, developing an appropriate laboratory solar simulator measurement capability, and to develop and test commercial cells modified for the Mars surface spectrum. This paper discusses the program, including results for the initial modified cells. Simulated Mars surface measurements of MER cells and Phoenix Lander cells (2007 launch) are provided to characterize the performance loss for those missions. In addition, the performance of the MER rover solar arrays is updated to reflect their more than two (2) year operation.

  19. Fluid dynamics and noise in bacterial cell-cell and cell-surface scattering

    CERN Document Server

    Drescher, Knut; Cisneros, Luis H; Ganguly, Sujoy; Goldstein, Raymond E; 10.1073/pnas.1019079108

    2011-01-01

    Bacterial processes ranging from gene expression to motility and biofilm formation are constantly challenged by internal and external noise. While the importance of stochastic fluctuations has been appreciated for chemotaxis, it is currently believed that deterministic long-range fluid dynamical effects govern cell-cell and cell-surface scattering - the elementary events that lead to swarming and collective swimming in active suspensions and to the formation of biofilms. Here, we report the first direct measurements of the bacterial flow field generated by individual swimming Escherichia coli both far from and near to a solid surface. These experiments allowed us to examine the relative importance of fluid dynamics and rotational diffusion for bacteria. For cell-cell interactions it is shown that thermal and intrinsic stochasticity drown the effects of long-range fluid dynamics, implying that physical interactions between bacteria are determined by steric collisions and near-field lubrication forces. This dom...

  20. Graphene–Gold Nanoparticles Hybrid—Synthesis, Functionalization, and Application in a Electrochemical and Surface-Enhanced Raman Scattering Biosensor

    Directory of Open Access Journals (Sweden)

    Ibrahim Khalil

    2016-05-01

    Full Text Available Graphene is a single-atom-thick two-dimensional carbon nanosheet with outstanding chemical, electrical, material, optical, and physical properties due to its large surface area, high electron mobility, thermal conductivity, and stability. These extraordinary features of graphene make it a key component for different applications in the biosensing and imaging arena. However, the use of graphene alone is correlated with certain limitations, such as irreversible self-agglomerations, less colloidal stability, poor reliability/repeatability, and non-specificity. The addition of gold nanostructures (AuNS with graphene produces the graphene–AuNS hybrid nanocomposite which minimizes the limitations as well as providing additional synergistic properties, that is, higher effective surface area, catalytic activity, electrical conductivity, water solubility, and biocompatibility. This review focuses on the fundamental features of graphene, the multidimensional synthesis, and multipurpose applications of graphene–Au nanocomposites. The paper highlights the graphene–gold nanoparticle (AuNP as the platform substrate for the fabrication of electrochemical and surface-enhanced Raman scattering (SERS-based biosensors in diverse applications as well as SERS-directed bio-imaging, which is considered as an emerging sector for monitoring stem cell differentiation, and detection and treatment of cancer.

  1. Graphene–Gold Nanoparticles Hybrid—Synthesis, Functionalization, and Application in a Electrochemical and Surface-Enhanced Raman Scattering Biosensor

    Science.gov (United States)

    Khalil, Ibrahim; Julkapli, Nurhidayatullaili Muhd; Yehye, Wageeh A.; Basirun, Wan Jefrey; Bhargava, Suresh K.

    2016-01-01

    Graphene is a single-atom-thick two-dimensional carbon nanosheet with outstanding chemical, electrical, material, optical, and physical properties due to its large surface area, high electron mobility, thermal conductivity, and stability. These extraordinary features of graphene make it a key component for different applications in the biosensing and imaging arena. However, the use of graphene alone is correlated with certain limitations, such as irreversible self-agglomerations, less colloidal stability, poor reliability/repeatability, and non-specificity. The addition of gold nanostructures (AuNS) with graphene produces the graphene–AuNS hybrid nanocomposite which minimizes the limitations as well as providing additional synergistic properties, that is, higher effective surface area, catalytic activity, electrical conductivity, water solubility, and biocompatibility. This review focuses on the fundamental features of graphene, the multidimensional synthesis, and multipurpose applications of graphene–Au nanocomposites. The paper highlights the graphene–gold nanoparticle (AuNP) as the platform substrate for the fabrication of electrochemical and surface-enhanced Raman scattering (SERS)-based biosensors in diverse applications as well as SERS-directed bio-imaging, which is considered as an emerging sector for monitoring stem cell differentiation, and detection and treatment of cancer. PMID:28773528

  2. Mask synthesis and verification based on geometric model for surface micro-machined MEMS

    Institute of Scientific and Technical Information of China (English)

    LI Jian-hua; LIU Yu-sheng; GAO Shu-ming

    2005-01-01

    Traditional MEMS (microelectromechanical system) design methodology is not a structured method and has become an obstacle for MEMS creative design. In this paper, a novel method of mask synthesis and verification for surface micro-machined MEMS is proposed, which is based on the geometric model of a MEMS device. The emphasis is focused on synthesizing the masks at the basis of the layer model generated from the geometric model of the MEMS device. The method is comprised of several steps: the correction of the layer model, the generation of initial masks and final masks including multi-layer etch masks, and mask simulation. Finally some test results are given.

  3. Stem cell responses to plasma surface modified electrospun polyurethane scaffolds.

    Science.gov (United States)

    Zandén, Carl; Hellström Erkenstam, Nina; Padel, Thomas; Wittgenstein, Julia; Liu, Johan; Kuhn, H Georg

    2014-07-01

    The topographical effects from functional materials on stem cell behavior are currently of interest in tissue engineering and regenerative medicine. Here we investigate the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell (hESC) and rat postnatal neural stem cell (NSC) responses. The plasma gases were found to induce three combinations of fiber surface functionalities and roughness textures. On randomly oriented fibers, plasma treatments lead to substantially increased hESC attachment and proliferation as compared to native fibers. Argon plasma was found to induce the most optimal combination of surface functionality and roughness for cell expansion. Contact guided migration of cells and alignment of cell processes were observed on aligned fibers. Neuronal differentiation around 5% was found for all samples and was not significantly affected by the induced variations of surface functional group distribution or individual fiber topography. In this study the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell and rat postnatal neural stem cell (NSC) responses is studied with the goal of clarifying the potential effects of functional materials on stem cell behavior, a topic of substantial interest in tissue engineering and regenerative medicine. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Biomechanics of cell rolling: shear flow, cell-surface adhesion, and cell deformability.

    Science.gov (United States)

    Dong, C; Lei, X X

    2000-01-01

    The mechanics of leukocyte (white blood cell; WBC) deformation and adhesion to endothelial cells (EC) has been investigated using a novel in vitro side-view flow assay. HL-60 cell rolling adhesion to surface-immobilized P-selectin was used to model the WBC-EC adhesion process. Changes in flow shear stress, cell deformability, or substrate ligand strength resulted in significant changes in the characteristic adhesion binding time, cell-surface contact and cell rolling velocity. A 2-D model indicated that cell-substrate contact area under a high wall shear stress (20 dyn/cm2) could be nearly twice of that under a low stress (0.5 dyn/cm2) due to shear flow-induced cell deformation. An increase in contact area resulted in more energy dissipation to both adhesion bonds and viscous cytoplasm, whereas the fluid energy that inputs to a cell decreased due to a flattened cell shape. The model also predicted a plateau of WBC rolling velocity as flow shear stresses further increased. Both experimental and computational studies have described how WBC deformation influences the WBC-EC adhesion process in shear flow.

  5. Surface Plasmon Resonance for Cell-Based Clinical Diagnosis

    Directory of Open Access Journals (Sweden)

    Yuhki Yanase

    2014-03-01

    Full Text Available Non-invasive real-time observations and the evaluation of living cell conditions and functions are increasingly demanded in life sciences. Surface plasmon resonance (SPR sensors detect the refractive index (RI changes on the surface of sensor chips in label-free and on a real-time basis. Using SPR sensors, we and other groups have developed techniques to evaluate living cells’ reactions in response to stimuli without any labeling in a real-time manner. The SPR imaging (SPRI system for living cells may visualize single cell reactions and has the potential to expand application of SPR cell sensing for clinical diagnosis, such as multi-array cell diagnostic systems and detection of malignant cells among normal cells in combination with rapid cell isolation techniques.

  6. Surface Coating of Oxide Powders: A New Synthesis Method to Process Biomedical Grade Nano-Composites

    Directory of Open Access Journals (Sweden)

    Paola Palmero

    2014-07-01

    Full Text Available Composite and nanocomposite ceramics have achieved special interest in recent years when used for biomedical applications. They have demonstrated, in some cases, increased performance, reliability, and stability in vivo, with respect to pure monolithic ceramics. Current research aims at developing new compositions and architectures to further increase their properties. However, the ability to tailor the microstructure requires the careful control of all steps of manufacturing, from the synthesis of composite nanopowders, to their processing and sintering. This review aims at deepening understanding of the critical issues associated with the manufacturing of nanocomposite ceramics, focusing on the key role of the synthesis methods to develop homogeneous and tailored microstructures. In this frame, the authors have developed an innovative method, named “surface-coating process”, in which matrix oxide powders are coated with inorganic precursors of the second phase. The method is illustrated into two case studies; the former, on Zirconia Toughened Alumina (ZTA materials for orthopedic applications, and the latter, on Zirconia-based composites for dental implants, discussing the advances and the potential of the method, which can become a valuable alternative to the current synthesis process already used at a clinical and industrial scale.

  7. Cytoskeletal Requirements for Hepatitis C Virus (HCV) RNA Synthesis in the HCV Replicon Cell Culture System

    OpenAIRE

    Bost, Anne G.; Venable, Daryl; Liu, Lifei; Heinz, Beverly A.

    2003-01-01

    Hepatitis C virus (HCV) induces microtubule aggregates in infected hepatocytes. To determine if cytoskeletal elements are important for HCV RNA synthesis, we examined the effect of cytoskeleton inhibitors on HCV replicon transcription in Huh7 cells. The data demonstrate that HCV replication complex-mediated RNA synthesis requires microtubule and actin polymerization.

  8. Cytoskeletal requirements for hepatitis C virus (HCV) RNA synthesis in the HCV replicon cell culture system.

    Science.gov (United States)

    Bost, Anne G; Venable, Daryl; Liu, Lifei; Heinz, Beverly A

    2003-04-01

    Hepatitis C virus (HCV) induces microtubule aggregates in infected hepatocytes. To determine if cytoskeletal elements are important for HCV RNA synthesis, we examined the effect of cytoskeleton inhibitors on HCV replicon transcription in Huh7 cells. The data demonstrate that HCV replication complex-mediated RNA synthesis requires microtubule and actin polymerization.

  9. Increased Adipogenic and Decreased Chondrogenic Differentiation of Adipose Derived Stem Cells on Nanowire Surfaces

    Directory of Open Access Journals (Sweden)

    Nathan A. Trujillo

    2014-03-01

    Full Text Available Despite many advances in tissue engineering, there are still significant challenges associated with restructuring, repairing, or replacing damaged tissue in the body. Currently, a major obstacle has been trying to develop a scaffold for cartilage tissue engineering that provides the correct mechanical properties to endure the loads associated with articular joints as well as promote cell-scaffold interactions to aid in extracellular matrix deposition. In addition, adipogenic tissue engineering is widely growing due to an increased need for more innovative reconstructive therapies following adipose tissue traumas and cosmetic surgeries. Recently, lipoaspirate tissue has been identified as a viable alternative source for mesenchymal stem cells because it contains a supportive stroma that can easily be isolated. Adipose derived stem cells (ADSCs can differentiate into a variety of mesodermal lineages including the adipogenic and chondrogenic phenotypes. Biodegradable polymeric scaffolds have been shown to be a promising alternative and stem cells have been widely used to evaluate the compatibility, viability, and bioactivity of these materials. Polycaprolactone is a bioresorbable polymer, which has been widely used for biomedical and tissue engineering applications. The fundamental concept behind successful synthetic tissue-engineered scaffolds is to promote progenitor cell migration, adhesion, proliferation, and induce differentiation, extracellular matrix synthesis, and finally integration with host tissue. In this study, we investigated the adhesion, proliferation, and chondrogenic and adipogenic differentiation of ADSCs on nanowire surfaces. A solvent-free gravimetric template technique was used to fabricate polycaprolactone nanowires surfaces. The results indicated that during the growth period i.e., initial 7 days of culture, the nanowire surfaces (NW supported adhesion and proliferation of the cells that had elongated morphologies. However

  10. Surface expression of HSP72 by LPS-stimulated neutrophils facilitates gammadeltaT cell-mediated killing.

    Science.gov (United States)

    Hirsh, Mark I; Hashiguchi, Naoyuki; Chen, Yu; Yip, Linda; Junger, Wolfgang G

    2006-03-01

    During inflammation and sepsis, accumulation of activated neutrophils causes lung tissue damage and organ failure. Effective clearance of neutrophils reduces the risk of organ failure; however, its mechanisms are poorly understood. Because lungs are rich in gammadeltaT cells, we investigated the physiological role of these cells in the protection of lung tissue from infiltrating neutrophils. In a mouse model of sepsis, we found that the lungs of survivors contained significantly higher numbers of gammadeltaT cells than those of mice that died from sepsis. The number of gammadeltaT cells correlated inversely with the number of neutrophils in the lungs and with the degree of lung tissue damage. LPS rapidly elicited the expression of heat shock protein (HSP) 72 on the surface of human neutrophils. Inhibitors of transcription, protein synthesis, and intracellular protein transport blocked HSP72 expression, indicating that de novo synthesis is required. gammadeltaT cells targeted and rapidly killed LPS-treated neutrophils through direct cell-to-cell contact. Pre-treatment with neutralizing antibodies to HSP72 diminished neutrophil killing. Our data indicate that HSP72 expression on the cell surface predisposes inflamed neutrophils to killing by gammadeltaT cells. This intercellular exchange may allow gammadeltaT cells to resolve inflammation and limit host tissue damage during sepsis.

  11. Dual functions of a monoclonal antibody against cell surface F1F0 ATP synthase on both HUVEC and tumor cells

    Institute of Scientific and Technical Information of China (English)

    Xia ZHANG; Feng GAO; Li-li YU; Yan PENG; Hong-hai LIU; Jin-ying LIU; Ming YIN; Jian NI

    2008-01-01

    Aim: To generate a monoclonal antibody (McAb) against cell surface FI F0 ATP synthase (ATPase) and observe its antitumoral activity on both human umbilical vein endothelial cells (HUVEC) and tumor cells. Methods: Hybridoma cells secret- ing McAb against ATPase were produced by polyethylene glycol-mediated fu- sions and screened by ELISA. The specificity of McAb was demonstrated by immunofluorescence and confocal imaging, as well as flow cytometry analysis. After the blockade of surface ATPase with McAb on HUVEC and human breast adenocarcinoma MDA-MB-231 cells, an ATP determination kit and CellTiter96 Aqueous Assay (MTS) assay were used to detect the effect of the antibody on extracellular ATP modification and cell proliferation. A cellular cytotoxicity assay in combination with doxorubicin, and a cell migration assay on MDA-MB-231 cells were used to determine the antitumoral activity. Finally, a HUVEC tube formation assay was used to detect the antiangiogenic effect of McAb178-5G10. Results: A monoclonal antibody (McAb178-SG10) against the β-subunit of ATPase was generated, and its reactivity toward HUVEC and tumor cells was studied. We demonstrate that McAb178-SG10 binds to ATPase at the cell surface, where it is able to inhibit ATP synthesis. This antibody also prevents the proliferation of HUVEC and MDA-MB-231 cells. Furthermore, McAb 178-5G l0 enhances the tumoricidal effects of doxorubicin (P<0.05), inhibits the migration of MDA-MB- 231 in transwell assays (P<0.01), and disrupts HUVEC tube formation on Matrigel (P<0.01). Conclusion: McAb178-5GI0 binds preferentially to cell surface ATPase, blocks ATP synthesis, and exhibits both antiangiogenic and antitumorigenic effects.

  12. Nanoscale crystallinity modulates cell proliferation on plasma sprayed surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Alan M. [School of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH (United Kingdom); Paxton, Jennifer Z.; Hung, Yi-Pei; Hadley, Martin J.; Bowen, James; Williams, Richard L. [School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom); Grover, Liam M., E-mail: l.m.grover@bham.ac.uk [School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom)

    2015-03-01

    Calcium phosphate coatings have been applied to the surface of metallic prostheses to mediate hard and soft tissue attachment for more than 40 years. Most coatings are formed of high purity hydroxyapatite, and coating methods are often designed to produce highly crystalline surfaces. It is likely however, that coatings of lower crystallinity can facilitate more rapid tissue attachment since the surface will exhibit a higher specific surface area and will be considerably more reactive than a comparable highly crystalline surface. Here we test this hypothesis by growing a population of MC3T3 osteoblast-like cells on the surface of two types of hip prosthesis with similar composition, but with differing crystallinity. The surfaces with lower crystallinity facilitated more rapid cell attachment and increased proliferation rate, despite having a less heterogeneous surface topography. This work highlights that the influence of the crystallinity of HA at the nano-scale is dominant over macro-scale topography for cell adhesion and growth. Furthermore, crystallinity could be easily adjusted by without compromising coating purity. These findings could facilitate designing novel coated calcium phosphate surfaces that more rapidly bond tissue following implantation. - Highlights: • Crystallinity of HA at the nano-scale was dominant over macro-scale topography. • Lower crystallinity caused rapid cell attachment and proliferation rate. • Crystallinity could be easily adjusted by without compromising coating purity.

  13. Derivatization and photolysis of a photoaffinity reagent for probing protein and cell surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, H.; Harris, H.W. Jr.

    1986-05-01

    The synthesis of the novel, heterobifunctional, cleavable, photoactivable crosslinking reagent, N-(4-(p-azido-m-(/sup 125/I) iodophenylazo)benzoyl)-3-aminopropyl-N'-oxysulfosuccinimide has been described by Denny and Blobel. This reagent is desirable because after photolysis and azo bond cleavage the /sup 125/I is transferred from the reagent to the crosslinked molecule. The authors demonstrate that using the reported synthesis 99% of the desired reagent is destroyed during the chloramine-T iodination step. They report a synthesis revision which produces high yields of the uniodinated (U) reagent. The derivatized reagent may be used in its iodinated (I) or U forms. To study the U reagent, a horseradish peroxidase (HRP) molecule is derivatized with nine reagent molecules. The derivatized HRP has 70% of its original enzymatic activity. After photolysis, 14% of this activity is retained and SDS-PAGE electrophoresis shows a crosslinked complex of HRP molecules. After endocytosis by cells, photolysis attaches the soluble derivatized HRP to membranes allowing them to be traced in the electron microscope. To study the I reagent, an amino-dextran (MW 73-400) molecule is derivatized with three U reagent molecules. The U reagent molecules are then iodinated by the chloramine-T method. With photolysis and cleavage, the /sup 125/I labeled reagent on dextran transfers its label to bovine serum albumin or ovalbumin. The authors conclude this reagent is a versatile probe for study of protein or cell surface topography.

  14. Electrocatalysis of formic acid on palladium and platinum surfaces: from fundamental mechanisms to fuel cell applications.

    Science.gov (United States)

    Jiang, Kun; Zhang, Han-Xuan; Zou, Shouzhong; Cai, Wen-Bin

    2014-10-14

    Formic acid as a natural biomass and a CO2 reduction product has attracted considerable interest in renewable energy exploitation, serving as both a promising candidate for chemical hydrogen storage material and a direct fuel for low temperature liquid fed fuel cells. In addition to its chemical dehydrogenation, formic acid oxidation (FAO) is a model reaction in the study of electrocatalysis of C1 molecules and the anode reaction in direct formic acid fuel cells (DFAFCs). Thanks to a deeper mechanistic understanding of FAO on Pt and Pd surfaces brought about by recent advances in the fundamental investigations, the "synthesis-by-design" concept has become a mainstream idea to attain high-performance Pt- and Pd-based nanocatalysts. As a result, a large number of efficient nanocatalysts have been obtained through different synthesis strategies by tailoring geometric and electronic structures of the two primary catalytic metals. In this paper, we provide a brief overview of recent progress in the mechanistic studies of FAO, the synthesis of novel Pd- and Pt-based nanocatalysts as well as their practical applications in DFAFCs with a focus on discussing studies significantly contributing to these areas in the past five years.

  15. Bleomycin-induced DNA synthesis in a cell-free system using a permeable mouse sarcoma cell Extract.

    Directory of Open Access Journals (Sweden)

    Seki,Shuji

    1987-10-01

    Full Text Available To investigate factors involved in excision repair DNA synthesis, a soluble extract was prepared from permeable mouse sarcoma (SR-C3H/He cells by homogenization and ultracentrifugation. DNA synthesis measured by using native calf thymus DNA as the template-primer and the extract as the polymerase source showed low activity. The DNA synthesis was enhanced more than ten-fold by the addition of an appropriate concentration of bleomycin, a radiomimetic DNA-damaging drug. Using selective inhibitors of DNA polymerases, it was shown that the DNA polymerase involved in the bleomycin-induced DNA synthesis was DNA polymerase beta. In addition to DNA polymerase beta, an exonuclease which converts bleomycin-damaged DNA into suitable template-primers for repair DNA synthesis appeared to be present in the permeable cell extract.

  16. Cell surface engineering of industrial microorganisms for biorefining applications.

    Science.gov (United States)

    Tanaka, Tsutomu; Kondo, Akihiko

    2015-11-15

    In order to decrease carbon emissions and negative environmental impacts of various pollutants, biofuel/biochemical production should be promoted for replacing fossil-based industrial processes. Utilization of abundant lignocellulosic biomass as a feedstock has recently become an attractive option. In this review, we focus on recent efforts of cell surface display using industrial microorganisms such as Escherichia coli and yeast. Cell surface display is used primarily for endowing cellulolytic activity on the host cells, and enables direct fermentation to generate useful fuels and chemicals from lignocellulosic biomass. Cell surface display systems are systematically summarized, and the drawbacks/perspectives as well as successful application of surface display for industrial biotechnology are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Influence of organic solvents on catalytic behaviors and cell morphology of whole-cell biocatalysts for synthesis of 5'-arabinocytosine laurate.

    Directory of Open Access Journals (Sweden)

    Meiyan Yang

    Full Text Available A whole-cell based method was developed for the regioselective synthesis of arabinocytosine laurate. Among the seven kinds of bacteria strains tested in the acylation reaction, Pseudomonas fluorescens gave the highest productivity and a higher 5'-regioselectivity than 99%. Compared with pure organic solvents, the use of organic solvent mixtures greatly promoted the yield of the whole-cell catalyzed reaction, but showed little influence on the 5'-regioselectivity. Of all the tested solvent mixtures, the best reaction result was found in isopropyl ether/pyridine followed by isopentanol/pyridine. However, the whole-cells showed much lower thermostability in isopropyl ether/pyridine than in THF-pyridine. To better understand the toxic effects of the organic solvents on P. fluorescens whole-cells and growing cells were further examined. Significant influences of organic solvents on the biomass of the cells were found, which differed depending on the type of solvents used. SEM analysis visually revealed the changes in the surface morphology of whole-cells and growing cells cultured in media containing various organic solvents, in terms of surface smoothness, bulges and changed cell sizes. Results demonstrated that organic toxicity to cell structure played an important role in whole-cell mediated catalysis.

  18. Influence of Organic Solvents on Catalytic Behaviors and Cell Morphology of Whole-Cell Biocatalysts for Synthesis of 5′-Arabinocytosine Laurate

    Science.gov (United States)

    Yang, Meiyan; Wu, Hui; Lian, Yan; Li, Xiaofeng; Lai, Furao; Zhao, Guanglei

    2014-01-01

    A whole-cell based method was developed for the regioselective synthesis of arabinocytosine laurate. Among the seven kinds of bacteria strains tested in the acylation reaction, Pseudomonas fluorescens gave the highest productivity and a higher 5′-regioselectivity than 99%. Compared with pure organic solvents, the use of organic solvent mixtures greatly promoted the yield of the whole-cell catalyzed reaction, but showed little influence on the 5′-regioselectivity. Of all the tested solvent mixtures, the best reaction result was found in isopropyl ether/pyridine followed by isopentanol/pyridine. However, the whole-cells showed much lower thermostability in isopropyl ether/pyridine than in THF-pyridine. To better understand the toxic effects of the organic solvents on P. fluorescens whole-cells and growing cells were further examined. Significant influences of organic solvents on the biomass of the cells were found, which differed depending on the type of solvents used. SEM analysis visually revealed the changes in the surface morphology of whole-cells and growing cells cultured in media containing various organic solvents, in terms of surface smoothness, bulges and changed cell sizes. Results demonstrated that organic toxicity to cell structure played an important role in whole-cell mediated catalysis. PMID:25136983

  19. Influence of organic solvents on catalytic behaviors and cell morphology of whole-cell biocatalysts for synthesis of 5'-arabinocytosine laurate.

    Science.gov (United States)

    Yang, Meiyan; Wu, Hui; Lian, Yan; Li, Xiaofeng; Lai, Furao; Zhao, Guanglei

    2014-01-01

    A whole-cell based method was developed for the regioselective synthesis of arabinocytosine laurate. Among the seven kinds of bacteria strains tested in the acylation reaction, Pseudomonas fluorescens gave the highest productivity and a higher 5'-regioselectivity than 99%. Compared with pure organic solvents, the use of organic solvent mixtures greatly promoted the yield of the whole-cell catalyzed reaction, but showed little influence on the 5'-regioselectivity. Of all the tested solvent mixtures, the best reaction result was found in isopropyl ether/pyridine followed by isopentanol/pyridine. However, the whole-cells showed much lower thermostability in isopropyl ether/pyridine than in THF-pyridine. To better understand the toxic effects of the organic solvents on P. fluorescens whole-cells and growing cells were further examined. Significant influences of organic solvents on the biomass of the cells were found, which differed depending on the type of solvents used. SEM analysis visually revealed the changes in the surface morphology of whole-cells and growing cells cultured in media containing various organic solvents, in terms of surface smoothness, bulges and changed cell sizes. Results demonstrated that organic toxicity to cell structure played an important role in whole-cell mediated catalysis.

  20. Synthesis of calcium-phosphorous doped TiO2 nanotubes by anodization and reverse polarization: A promising strategy for an efficient biofunctional implant surface

    Science.gov (United States)

    Alves, Sofia A.; Patel, Sweetu B.; Sukotjo, Cortino; Mathew, Mathew T.; Filho, Paulo N.; Celis, Jean-Pierre; Rocha, Luís A.; Shokuhfar, Tolou

    2017-03-01

    The modification of surface features such as nano-morphology/topography and chemistry have been employed in the attempt to design titanium oxide surfaces able to overcome the current dental implants failures. The main goal of this study is the synthesis of bone-like structured titanium dioxide (TiO2) nanotubes enriched with Calcium (Ca) and Phosphorous (P) able to enhance osteoblastic cell functions and, simultaneously, display an improved corrosion behavior. To achieve the main goal, TiO2 nanotubes were synthetized and doped with Ca and P by means of a novel methodology which relied, firstly, on the synthesis of TiO2 nanotubes by anodization of titanium in an organic electrolyte followed by reverse polarization and/or anodization, in an aqueous electrolyte. Results show that hydrophilic bone-like structured TiO2 nanotubes were successfully synthesized presenting a highly ordered nano-morphology characterized by non-uniform diameters. The chemical analysis of such nanotubes confirmed the presence of CaCO3, Ca3(PO4)2, CaHPO4 and CaO compounds. The nanotube surfaces submitted to reverse polarization, presented an improved cell adhesion and proliferation compared to smooth titanium. Furthermore, these surfaces displayed a significantly lower passive current in artificial saliva, and so, potential to minimize their bio-degradation through corrosion processes. This study addresses a very simple and promising multidisciplinary approach bringing new insights for the development of novel methodologies to improve the outcome of osseointegrated implants.

  1. Surface-Bound Intermediates in Low-Temperature Methanol Synthesis on Copper. Participants and Spectators

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yong; Mei, Donghai; Peden, Charles HF; Campbell, Charles T.; Mims, Charles A.

    2015-11-03

    The reactivity of surface adsorbed species present on copper catalysts during methanol synthesis at low temperatures was studied by simultaneous infrared spectroscopy (IR) and mass spectroscopy (MS) measurements during “titration” (transient surface reaction) experiments with isotopic tracing. The results show that adsorbed formate is a major bystander species present on the surface under steady-state methanol synthesis reaction conditions, but it cannot be converted to methanol by reaction with pure H2, nor with H2 plus added water. Formate-containing surface adlayers for these experiments were produced during steady state catalysis in (a) H2:CO2 (with substantial formate coverage) and (b) moist H2:CO (with no IR visible formate species). Both these reaction conditions produce methanol at steady state with relatively high rates. Adlayers containing formate were also produced by (c) formic acid adsorption. Various "titration" gases were used to probe these adlayers at modest temperatures (T = 410-450K) and 6 bar total pressure. Methanol gas (up to ~1% monolayer equivalent) was produced in "titration" from the H2:CO2 catalytic adlayers by H2 plus water, but not by dry hydrogen. The decay in the formate IR features accelerated in the presence of added water vapor. The H2:CO:H2O catalytic adlayer produced similar methanol titration yields in H2 plus water but showed no surface formate features in IR (less than 0.2% monolayer coverage). Finally, formate from formic acid chemisorption produced no methanol under any titration conditions. Even under (H2:CO2) catalytic reaction conditions, isotope tracing showed that pre-adsorbed formate from formic acid did not contribute to the methanol produced. Although non-formate intermediates exist during low temperature methanol synthesis on copper which can be converted to methanol gas

  2. Multi-scale cell/surface interaction on modified titanium aluminum vanadium surfaces

    Science.gov (United States)

    Chen, Jianbo

    This dissertation presents a series of experimental studies of the effects of multi-scale cell/surface interactions on modified Ti-6Al-4V surfaces. These include laser-grooved surfaces; porous structures and RGD-coated laser-grooved surfaces. A nano-second DPSS UV lasers with a Gaussian pulse energy profile was used to introduce the desired micro-groove geometries onto Ti-6Al-4V surfaces. This was done without inducing micro-cracks or significant changes in surface chemistry within the heat affected zones. The desired 8-12 mum groove depths and widths were achieved by the control of pulse frequency, scan speed, and the lens focal length that controls spot size. The interactions between human osteosarcoma (HOS) cells and laser-grooved Ti-6Al-4V surfaces were investigated after 48 hours of cell culture. The cell behavior, including cell spreading, alignment and adhesion, was elucidated using scanning electronic microscopy (SEM), immuno-fluorescence staining and enzymatic detachment. Contact guidance was shown to increase as grooved spacing decreased. For the range of micro-groove geometries studied, micro-grooves with groove spacings of 20 mum provided the best combination of cell orientation and adhesion. Short-term adhesion experiments (15 mins to 1 day) also revealed that there is a positive correlation between cell orientation and cell adhesion. Contact guidance on the micro-grooved surfaces is shown to be enhanced by nano- and micro-scale asperities that provide sites for the attachment of lamellopodia during cell locomotion and spreading. Contact guidance is also promoted by the geometrical confinement provided by laser grooves. An experimental study of initial cell spreading and ingrowth into Ti-6Al-4V porous structures was also carried out on porous structures with different pore sizes and geometries. A combination of SEM, the tetrazolium salt (MTT) colorimetric assay and enzymatic detachment were used to study cell spreading and adhesion. The extent of cell

  3. High efficiency photoluminescence from silicon nanocrystals prepared by plasma synthesis and organic surface passivation

    Energy Technology Data Exchange (ETDEWEB)

    Mangolini, L.; Kortshagen, U. [Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Jurbergs, D.; Rogojina, E. [Innovalight Inc., 3303 Octavius Drive Suite 104, Santa Clara, CA 95054 (United States)

    2006-07-01

    An efficient synthesis route for highly luminescent silicon quantum dots is presented. Silicon nanocrystals were synthesized in the gas phase using an argon-silane non-thermal plasma in a continuous flow reactor. Liquid phase surface passivation was used to improve the optical properties and avoid surface oxidation of the silicon quantum dots. Various alkenes, such as octadecene, dodecene and styrene, were covalently bonded to the plasma-produced particles, while strictly avoiding exposure of the raw powder to oxidizing agents. Stable colloidal solutions of silicon quantum dots with ensemble quantum yields between 60% and 70% were achieved. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Synthesis and Surface Tension Properties of Polyethyleneimine—Polyethylene Oxide Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    张剑; LONNIE,Bryant

    2003-01-01

    This peper describes the synthesis,surface tension and dispersancy properties of block copolymer nonionic surfactants comprised of polyethyleneimine(PEI) and polyethlene oxide(PEO) blocks of selected lengths.These block copolymers were prepared by a threestep synthetic sequence.Firstly,PEO glycol was converted to its dimethanesulphonylester (dimesyl) derivative by reacting with methanesulphonyl chloride.Then a tri-block polymer was preparaed by the ring-opening polymerization of 2-methly-2-oxazoline(MeOZO)with the dimesyl PEO derivative.Lastly,linear PEI blocks were obtained by subsequent hydrolysis and purification.1H NMR spectra confirmed the structures of the intermediate,final products and their purities(>99%).The utility of these block copolymers is described in terms of their surface tension and clay dispersancy measurements as a function of copolymer chain and block length.

  5. Solid-core and hollow magnetic nanostructures: Synthesis, surface modifications and biological applications.

    Science.gov (United States)

    Nieciecka, Dorota; Nawara, Krzysztof; Kijewska, Krystyna; Nowicka, Anna M; Mazur, Maciej; Krysinski, Pawel

    2013-10-01

    In the need of development of versatile and flexible platforms for sensing, nanostructured particles are one of the systems of choice. Additionally, the state-of-the-art, controlled surface modifications of these structures offer broad possibilities of using such systems for diagnostics and therapy, often referred to as thera(g)nostics. In this brief review we will focus on the synthesis and surface modifications of solid-core magnetic nanostructures and polymeric capsules containing nanoferrites modified with anti-cancer drug--doxorubicin, designed for magnetic field-driven drug delivery for cancer therapy. We will also outline some problems related to the usage of such structures. The encapsulation and distribution of magnetic iron oxide nanoparticles modified with doxorubicin will be demonstrated in the polypyrrole spherical microvessels.

  6. Membrane Tether Formation on a Cell Surface with Reservoir

    Institute of Scientific and Technical Information of China (English)

    JIANG Yu-Qiang; GUO Hong-Lian; LIU Chun-Xiang; LI Zhao-Lin; CHENG Bing-Ying; ZHANG Dao-Zhong; JIA Suo-Tang

    2004-01-01

    @@ We propose a mathematical model to analyse the membrane tether formation process on a cell surface with reservoir. Based on the experimental results, the membrane reservoir density of breast cancer cell was obtained,p = 8.02. The membrane surface viscosity between membrane and environment η is 0.021(pN.s/μm3), and the static force F0 = 5.71 pN.

  7. Microfabricated surface designs for cell culture and diagnosis.

    Science.gov (United States)

    Matsuda, T; Chung, D J

    1994-01-01

    Grooved and holed surfaces with a well fabricated design may serve as microsubstrates for cell culture and microreactors for diagnosis. In this study, the authors prepared chemically treated, micrometer scale grooved and holed glass surfaces by combined surface modification and ultraviolet (UV) excimer laser ablation techniques, as follows. 1) Microcell-culture substrate: Amino group attached glass surfaces, prepared by the treatment with an aminopropylsilane, were condensed with a carboxylated radical initiator. Subsequently, polyacrylamide was grafted by surface initiated radical polymerization to create a very hydrophilic surface layer. Ultraviolet excimer laser beams (KrF: 248 nm) were irradiated through a microscope onto surfaces to create grooves or holes that were 10 and 50 microns in width or diameter, respectively. The depth, depending on the irradiation light strength, ranged from a few to several tenths of a micrometer. On endothelial cell (EC) seeding, ECs adhered and grew on the bottoms of the grooved or holed surface where glass was exposed on ablation. Little cell adhesion was observed on non ablated, grafted surfaces. Endothelial cells aligned along the groove, resulting in very narrow tube like tissue formation, whereas ECs tended to form a multilayered spherical aggregate in a hole. A single cell resided in a 10 microns square hole. 2) Microreactor for diagnosis: The glass surface, treated with a fluorinated silane, was ablated to create round holes. On addition of a few microliters of water, water could be quantitatively transferred into a hole because of the water repellent characteristics of non ablated, fluorinated glass. As a model of a microreactor, enzyme reactions to affect different levels of glucose were carried out in tiny holed surfaces.

  8. One-Step Synthesis of PEGylated Gold Nanoparticles with Tunable Surface Charge

    Directory of Open Access Journals (Sweden)

    Rares Stiufiuc

    2013-01-01

    Full Text Available The present work reports a rapid, simple and efficient one-step synthesis and detailed characterisation of stable aqueous colloids of gold nanoparticles (AuNPs coated with unmodified poly(ethyleneglycol (PEG molecules of different molecular weights and surface charges. By mixing and heating aqueous solutions of PEG with variable molecular chain and gold(III chloride hydrate (HAuCl4 in the presence of NaOH, we have successfully produced uniform colloidal 5 nm PEG coated AuNPs of spherical shape with tunable surface charge and an average diameter of 30 nm within a few minutes. It has been found out that PEGylated AuNPs provide optical enhancement of the characteristic vibrational bands of PEG molecules attached to the gold surface when they are excited with both visible (532 nm and NIR (785 nm laser lines. The surface enhanced Raman scattering (SERS signal does not depend on the length of the PEG molecular chain enveloping the AuNPs, and the stability of the colloid is not affected by the addition of concentrated salt solution (0.1 M NaCl, thus suggesting their potential use for in vitro and in vivo applications. Moreover, by gradually changing the chain length of the biopolymer, we were able to control nanoparticles’ surface charge from −28 to −2 mV, without any modification of the Raman enhancement properties and of the colloidal stability.

  9. Synthesis and Characteristics of Mesoporous Silica Aerogels with One-step Solvent Exchange/Surface Modification

    Institute of Scientific and Technical Information of China (English)

    WANG Lijiu; ZHAO Shanyu

    2009-01-01

    The synthesis procedures and physical properties of the ambient dried hydrophobic silica aerogels by using different contents of ethanol(EtOH)/trimethylchlorosilane(TMCS)/n-Hexane as surface modification agent were investigated.One-step solvent exchange and surface modification were simultaneously progressed by immersing silica hydrogels in EtOH/TMCS/n-Hexane solution.It is found that microstructures as well as properties of silica aerogels like porosity,specific density and specific surface area are affected by the contents of surface modification agent in the sol from the re-sults of SEM,TEM morphology,FT-IR chemical structure,BET surface area and BJH pore size analyses.The volume of TMCS is of 10%and 20%of hydrogels,and the final product is hydrophilic xerogels.When TMCS's percent(v/v)is elevated to 75%-100%,hydrophobic silica aerogels with good performance are synthesized,the porosities of aerogels are in the range of 93.5%-95.8%and the av-erage pore size diameter is less than 20 nm.

  10. Overview of cell-free protein synthesis: historic landmarks, commercial systems, and expanding applications.

    Science.gov (United States)

    Chong, Shaorong

    2014-10-01

    During the early days of molecular biology, cell-free protein synthesis played an essential role in deciphering the genetic code and contributed to our understanding of translation of protein from messenger RNA. Owing to several decades of major and incremental improvements, modern cell-free systems have achieved higher protein synthesis yields at lower production costs. Commercial cell-free systems are now available from a variety of material sources, ranging from "traditional" E. coli, rabbit reticulocyte lysate, and wheat germ extracts, to recent insect and human cell extracts, to defined systems reconstituted from purified recombinant components. Although each cell-free system has certain advantages and disadvantages, the diversity of the cell-free systems allows in vitro synthesis of a wide range of proteins for a variety of downstream applications. In the post-genomic era, cell-free protein synthesis has rapidly become the preferred approach for high-throughput functional and structural studies of proteins and a versatile tool for in vitro protein evolution and synthetic biology. This unit provides a brief history of cell-free protein synthesis and describes key advances in modern cell-free systems, practical differences between widely used commercial cell-free systems, and applications of this important technology.

  11. Study of Surface Cell Madelung Constant and Surface Free Energy of Nanosized Crystal Grain

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-Jia; WANG Tian-Min; CUI Min

    2005-01-01

    Surface cell Madelung constant is firstly defined in calculating surface free energy of nanosized crystal grains, which explains the physical performance of small crystals and may be great benefit to make surface analysis and study dynamics of crystal nucleus growth. A new ap- proximative expression of surface energy and relevant thermodynamic data was used in this cal- culation. A new formula and computing method for calculating the Madelung constant α of any complex crystals is proposed, and surface free energies and surface electrostatic energies of nano- sized crystal grains as well as Madelung constant of some complex crystals are theoretically cal- culated in this paper. The surface free energy of nanosized crystal grain TiO2 and surface elec- trostatic energy(absolute value) of nanosized crystal grain α-Al2O3 are found to be the biggest among other crystal grains.

  12. Study of surface cell Madelung constant and surface free energy of nanosized crystal grain

    Institute of Scientific and Technical Information of China (English)

    Zhang Wei-Jia; Wang Tian-Min; Rong Ai-Lun; Cui Min

    2006-01-01

    Surface cell Madelung constant is firstly defined for calculating the surface free energy of nanosized crystal grains,which explains the physical performance of small crystals and may be greatly beneficial to the analysis of surface states and the study of the dynamics of crystal nucleation and growth.A new approximative expression of the surface energy and relevant thermodynamic data are used in this calculation.New formula and computing method for calculating the Madelung constant α of any complex crystals are proposed,and the surface free energies and surface electrostatic energies of nanosized crystal grains and the Madelung constant of some complex crystals are theoretically calculated in this paper.The surface free energy of nanosized-crystal-grain TiO2 and the surface electrostatic energy (absolute value) of nanosized-crystal-grain α-A12O3 are found to be the biggest among all the crystal grains including those of other species.

  13. In Vitro Optimization of Enzymes Involved in Precorrin-2 Synthesis Using Response Surface Methodology.

    Science.gov (United States)

    Fang, Huan; Dong, Huina; Cai, Tao; Zheng, Ping; Li, Haixing; Zhang, Dawei; Sun, Jibin

    2016-01-01

    In order to maximize the production of biologically-derived chemicals, kinetic analyses are first necessary for predicting the role of enzyme components and coordinating enzymes in the same reaction system. Precorrin-2 is a key precursor of cobalamin and siroheme synthesis. In this study, we sought to optimize the concentrations of several molecules involved in precorrin-2 synthesis in vitro: porphobilinogen synthase (PBGS), porphobilinogen deaminase (PBGD), uroporphyrinogen III synthase (UROS), and S-adenosyl-l-methionine-dependent urogen III methyltransferase (SUMT). Response surface methodology was applied to develop a kinetic model designed to maximize precorrin-2 productivity. The optimal molar ratios of PBGS, PBGD, UROS, and SUMT were found to be approximately 1:7:7:34, respectively. Maximum precorrin-2 production was achieved at 0.1966 ± 0.0028 μM/min, agreeing with the kinetic model's predicted value of 0.1950 μM/min. The optimal concentrations of the cofactor S-adenosyl-L-methionine (SAM) and substrate 5-aminolevulinic acid (ALA) were also determined to be 200 μM and 5 mM, respectively, in a tandem-enzyme assay. By optimizing the relative concentrations of these enzymes, we were able to minimize the effects of substrate inhibition and feedback inhibition by S-adenosylhomocysteine on SUMT and thereby increase the production of precorrin-2 by approximately five-fold. These results demonstrate the effectiveness of kinetic modeling via response surface methodology for maximizing the production of biologically-derived chemicals.

  14. In Vitro Optimization of Enzymes Involved in Precorrin-2 Synthesis Using Response Surface Methodology.

    Directory of Open Access Journals (Sweden)

    Huan Fang

    Full Text Available In order to maximize the production of biologically-derived chemicals, kinetic analyses are first necessary for predicting the role of enzyme components and coordinating enzymes in the same reaction system. Precorrin-2 is a key precursor of cobalamin and siroheme synthesis. In this study, we sought to optimize the concentrations of several molecules involved in precorrin-2 synthesis in vitro: porphobilinogen synthase (PBGS, porphobilinogen deaminase (PBGD, uroporphyrinogen III synthase (UROS, and S-adenosyl-l-methionine-dependent urogen III methyltransferase (SUMT. Response surface methodology was applied to develop a kinetic model designed to maximize precorrin-2 productivity. The optimal molar ratios of PBGS, PBGD, UROS, and SUMT were found to be approximately 1:7:7:34, respectively. Maximum precorrin-2 production was achieved at 0.1966 ± 0.0028 μM/min, agreeing with the kinetic model's predicted value of 0.1950 μM/min. The optimal concentrations of the cofactor S-adenosyl-L-methionine (SAM and substrate 5-aminolevulinic acid (ALA were also determined to be 200 μM and 5 mM, respectively, in a tandem-enzyme assay. By optimizing the relative concentrations of these enzymes, we were able to minimize the effects of substrate inhibition and feedback inhibition by S-adenosylhomocysteine on SUMT and thereby increase the production of precorrin-2 by approximately five-fold. These results demonstrate the effectiveness of kinetic modeling via response surface methodology for maximizing the production of biologically-derived chemicals.

  15. Cell orientation on a stripe-micropatterned surface

    Institute of Scientific and Technical Information of China (English)

    SUN JianGuo; TANG Jian; DING JianDong

    2009-01-01

    Stripe-micropatterned surfaces have recently been a unique tool to study cell orientation. In this paper,we prepared,by the photolithography transfer technique,stable gold (Au) micropatterns on PEG hydrogel surfaces with defined cell-resistant (PEG hydrogel) and cell-adhesive (gold microstripes) proparties. 3T3 fibroblasts were cultured on Au-microstripe surfaces to observe cell adhesion and orientation. Five statistical parameters were defined and used to describe cell orientation on micropatterns.With the increase of inter-stripe distance,the orientational order parameter,the ratio of long and short axes of a cell,and the occupation fraction of cells on stripes increased gradually,whereas the spreading area of a single cell decreased. The abrupt changes of these four parameters did not happen at the same inter-distance. The adhesion ratio of a cell on Au stripes over cell spreading area did not change monotonically as a function of inter-stripe distance. The combination of the 5 statistical parameters represented well the cell orientation behaviors semi-quantitatively.

  16. Immunogold labels: cell-surface markers in atomic force microscopy

    NARCIS (Netherlands)

    Putman, Constant A.J.; Grooth, de Bart G.; Hansma, Paul K.; Hulst, van Niek F.; Greve, Jan

    1993-01-01

    The feasibility of using immunogold labels as cell-surface markers in atomic force microscopy is shown in this paper. The atomic force microscope (AFM) was used to image the surface of immunogold-labeled human lymphocytes. The lymphocytes were isolated from whole blood and labeled by an indirect imm

  17. Sperm cell surface dynamics during activation and fertilization

    NARCIS (Netherlands)

    Boerke, A.

    2013-01-01

    Before the sperm cell can reach the oocyte it needs to be activated and to undergo a series of preparative steps. The sperm surface dynamics was studied in relation to this activation process and the modifications and removal of sperm surface components havebeen investigated. Bicarbonate-induced rad

  18. Fabrication of cell container arrays with overlaid surface topographies.

    NARCIS (Netherlands)

    Truckenmuller, R.; Giselbrecht, S.; Escalante-Marun, M.; Groenendijk, M.; Papenburg, B.; Rivron, N.; Unadkat, H.; Saile, V.; Subramaniam, V.; Berg, A. van den; Blitterswijk, C. Van; Wessling, M.; Boer, J. den; Stamatialis, D.

    2012-01-01

    This paper presents cell culture substrates in the form of microcontainer arrays with overlaid surface topographies, and a technology for their fabrication. The new fabrication technology is based on microscale thermoforming of thin polymer films whose surfaces are topographically prepatterned on a

  19. Fabrication of cell container arrays with overlaid surface topographies

    NARCIS (Netherlands)

    Truckenmüller, R.K.; Giselbrecht, S.; Escalante, M.; Groenendijk, M.N.W.; Papenburg, B.J.; Rivron, N.C.; Unadkat, H.V.; Saile, V.; Subramaniam, V.; Blitterswijk, van C.A.; Wessling, M.; Boer, de J.; Stamatialis, D.

    2012-01-01

    This paper presents cell culture substrates in the form of microcontainer arrays with overlaid surface topographies, and a technology for their fabrication. The new fabrication technology is based on microscale thermoforming of thin polymer films whose surfaces are topographically prepatterned on a

  20. DNA and RNA Synthesis in Animal Cells in Culture--Methods for Use in Schools

    Science.gov (United States)

    Godsell, P. M.; Balls, M.

    1973-01-01

    Describes the experimental procedures used for detecting DNA and RNA synthesis in xenopus cells by autoradiography. The method described is suitable for senior high school laboratory classes or biology projects, if supervised by a teacher qualified to handle radioisotopes. (JR)

  1. Inositol Hexakisphosphate Kinase 1 (IP6K1) Regulates Inositol Synthesis in Mammalian Cells.

    Science.gov (United States)

    Yu, Wenxi; Ye, Cunqi; Greenberg, Miriam L

    2016-05-13

    myo-Inositol, the precursor of all inositol compounds, has pivotal roles in cell metabolism and signaling pathways. Although physiological studies indicate a strong correlation between abnormal intracellular inositol levels and neurological disorders, very little is known about the regulation of inositol synthesis in mammalian cells. In this study, we report that IP6K1, an inositol hexakisphosphate kinase that catalyzes the synthesis of inositol pyrophosphate, regulates inositol synthesis in mammalian cells. Ip6k1 ablation led to profound changes in DNA methylation and expression of Isyna1 (designated mIno1), which encodes the rate-limiting enzyme inositol-3-phosphate synthase. Interestingly, IP6K1 preferentially bound to the phospholipid phosphatidic acid, and this binding was required for IP6K1 nuclear localization and the regulation of mIno1 transcription. This is the first demonstration of IP6K1 as a novel negative regulator of inositol synthesis in mammalian cells.

  2. DNA and RNA Synthesis in Animal Cells in Culture--Methods for Use in Schools

    Science.gov (United States)

    Godsell, P. M.; Balls, M.

    1973-01-01

    Describes the experimental procedures used for detecting DNA and RNA synthesis in xenopus cells by autoradiography. The method described is suitable for senior high school laboratory classes or biology projects, if supervised by a teacher qualified to handle radioisotopes. (JR)

  3. Influence of anabolic agents on protein synthesis and degradation in muscle cells grown in culture

    Energy Technology Data Exchange (ETDEWEB)

    Roeder, R.A.; Thorpe, S.D.; Byers, F.M.; Schelling, G.T.; Gunn, J.M.

    Muscle cell culture (L/sub 6/) studies were conducted to determine whether anabolic agents have a direct effect on the muscle cell. The effect of zeranol, testosterone propionate, estradiol benzoate, progesterone, dexamethasone and anabolic agent-dexamethasone combinations on protein synthesis and degradation were measured. Myoblast and myotube cultures were pretreated with 1 ..mu..M compounds for 12, 24 and 48 h before a 6-h synthesis or degradation measuring period. Protein synthesis was determined as cpm of (/sup 3/H) leucine incorporated per mg cell protein. Protein degradation was measured by a pulse-chase procedure using (/sup 3/H) leucine and expressed as the percentage labeled protein degraded in 6 h. Progesterone slightly increased protein synthesis in myoblast cultures. Testosterone propionate had no effect on synthesis. Protein synthesis was decreased by estradiol benzoate in myotube cultures. Protein degradation was not altered appreciably by anabolic agents. Protein synthesis was initially inhibited in myotubes by dexamethasone, but increased in myoblasts and myotubes in the extended incubation time. Dexamethasone also consistently increased protein degradation, but this required several hours to be expressed. Anabolic agents did not interfere with dexamethasone-induced increases in protein synthesis and degradation. The magnitude of response and sensitivity were similar for both the myoblast and the more fully differentiated myotube for all compounds tested. These results indicate that anabolic agents at the 1 ..mu..M level do not have a direct anabolic effect on muscle or alter glucocorticoid-induced catabolic response in muscle.

  4. Tyrosine and the synthesis of melanin in embryonic cells fromAmbystoma mexicanum.

    Science.gov (United States)

    Landström, Ulf; Løvtrup, Søren

    1978-09-01

    Explants comprising about 15 cells were dissected from various regions of the blastula ofAmbystoma mexicanum and cultured in Barth's medium. By addition of L-tyrosine to the culture medium it was possible to induce melanin synthesis in three different cells types: undifferentiated embryonic cells, mesenchyme cells and nerve cells. Tyrosine was found to act as an inductor in a very low concentration (1 μM). It is suggested that tyrosine serves both as an inductor and as a substrate for melanin synthesis in the amphibian larva.

  5. Differences in claudin synthesis in primary cultures of acinar cells from rat salivary gland are correlated with the specific three-dimensional organization of the cells.

    Science.gov (United States)

    Qi, Bing; Fujita-Yoshigaki, Junko; Michikawa, Hiromi; Satoh, Keitaro; Katsumata, Osamu; Sugiya, Hiroshi

    2007-07-01

    Tight junctions are essential for the maintenance of epithelial cell polarity. We have previously established a system for the primary culture of salivary parotid acinar cells that retain their ability to generate new secretory granules and to secrete proteins in a signal-dependent manner. Because cell polarity and cell-cell adhesion are prerequisites for the formation of epithelial tissues, we have investigated the structure of the tight junctions in these cultures. We have found two types of cellular organization in the culture: monolayers and semi-spherical clusters. Electron microscopy has revealed tight junctions near the apical region of the lateral membranes between cells in the monolayers and cells at the surface of the clusters. The cells in the interior of the clusters also have tight junctions and are organized around a central lumen. These interior cells retain more secretory granules than the surface or monolayer cells, suggesting that they maintain their original character as acinar cells. The synthesis of claudin-4 increases during culture, although it is not detectable in the cells immediately after isolation from the glands. Immunofluorescence microscopy has shown that claudin-4 is synthesized in the monolayers and at the surface of the clusters, but not inside the clusters. Only claudin-3, which is present in the original acinar cells following isolation and in the intact gland, has been detected inside the clusters. These results suggest that differences in claudin expression are related to the three-dimensional structures of the cell cultures and reflect their ability to function as acinar cells.

  6. Recharging Red Blood Cell Surface by Hemodialysis

    Directory of Open Access Journals (Sweden)

    Katrin Kliche

    2015-02-01

    Full Text Available Background: Similar as in vascular endothelium the negatively charged glycocalyx of erythrocytes selectively buffers sodium. Loss of glycocalyx (i.e. loss of negative charges leads to increased erythrocyte sodium sensitivity (ESS quantified by a recently developed salt-blood-test (SBT. The hypothesis was tested whether a regular 4-hour hemodialysis (4h-HD alters ESS. Methods: In 38 patients with end stage renal disease (ESRD ESS was measured before and after 4h-HD, together with standard laboratory and clinical parameters (electrolytes, acid-base status, urea, creatinine, hemoglobin, c-reactive protein and blood pressure. Results: Before 4h-HD, 20 patients (out of 38 were classified as “salt sensitive” by SBT. After 4h-HD, this number decreased to 11. Erythrocyte sodium buffering power remained virtually constant in patients with already low ESS before dialysis, whereas in patients with high ESS, 4h-HD improved the initially poor sodium buffering power by about 20%. No significant correlations could be detected between standard blood parameters and the respective ESS values except for plasma sodium concentration which was found increased by 3.1 mM in patients with high salt sensitivity. Conclusions: 4h-HD apparently recharges “run-down” erythrocytes and thus restores erythrocyte sodium buffering capacity. Besides the advantage of efficient sodium buffering in blood, erythrocytes with sufficient amounts of free negative charges at the erythrocyte surface will cause less (mechanical injury to the negatively charged endothelial surface due to efficient repulsive forces between blood and vessel wall. Hemodialysis improves erythrocyte surface properties and thus may prevent early vascular damage in patients suffering from ESRD.

  7. Expanding the diversity of unnatural cell surface sialic acids

    Energy Technology Data Exchange (ETDEWEB)

    Luchansky, Sarah J.; Goon, Scarlett; Bertozzi, Carolyn R.

    2003-10-30

    Novel chemical reactivity can be introduced onto cell surfaces through metabolic oligosaccharide engineering. This technique exploits the substrate promiscuity of cellular biosynthetic enzymes to deliver unnatural monosaccharides bearing bioorthogonal functional groups into cellular glycans. For example, derivatives of N-acetylmannosamine (ManNAc) are converted by the cellular biosynthetic machinery into the corresponding sialic acids and subsequently delivered to the cell surface in the form of sialoglycoconjugates. Analogs of N-acetylglucosamine (GlcNAc) and N-acetylgalactosamine (GalNAc) are also metabolized and incorporated into cell surface glycans, likely through the sialic acid and GalNAc salvage pathways, respectively. Furthermore, GlcNAc analogs can be incorporated into nucleocytoplasmic proteins in place of {beta}-O-GlcNAc residues. These pathways have been exploited to integrate unique electrophiles such as ketones and azides into the target glycoconjugate class. These functional groups can be further elaborated in a chemoselective fashion by condensation with hydrazides and by Staudinger ligation, respectively, thereby introducing detectable probes onto the cell. In conclusion, sialic acid derivatives are efficient vehicles for delivery of bulky functional groups to cell surfaces and masking of their hydroxyl groups improves their cellular uptake and utilization. Furthermore, the successful introduction of photoactivatable aryl azides into cell surface glycans opens up new avenues for studying sialic acid-binding proteins and elucidating the role of sialic acid in essential processes such as signaling and cell adhesion.

  8. Responses of fibroblasts and glial cells to nanostructured platinum surfaces

    Science.gov (United States)

    Pennisi, C. P.; Sevcencu, C.; Dolatshahi-Pirouz, A.; Foss, M.; Lundsgaard Hansen, J.; Nylandsted Larsen, A.; Zachar, V.; Besenbacher, F.; Yoshida, K.

    2009-09-01

    The chronic performance of implantable neural prostheses is affected by the growth of encapsulation tissue onto the stimulation electrodes. Encapsulation is associated with activation of connective tissue cells at the electrode's metallic contacts, usually made of platinum. Since surface nanotopography can modulate the cellular responses to materials, the aim of the present work was to evaluate the 'in vitro' responses of connective tissue cells to platinum strictly by modulating its surface nanoroughness. Using molecular beam epitaxy combined with sputtering, we produced platinum nanostructured substrates consisting of irregularly distributed nanopyramids and investigated their effect on the proliferation, cytoskeletal organization and cellular morphology of primary fibroblasts and transformed glial cells. Cells were cultured on these substrates and their responses to surface roughness were studied. After one day in culture, the fibroblasts were more elongated and their cytoskeleton less mature when cultured on rough substrates. This effect increased as the roughness of the surface increased and was associated with reduced cell proliferation throughout the observation period (4 days). Morphological changes also occurred in glial cells, but they were triggered by a different roughness scale and did not affect cellular proliferation. In conclusion, surface nanotopography modulates the responses of fibroblasts and glial cells to platinum, which may be an important factor in optimizing the tissue response to implanted neural electrodes.

  9. Cell surface area and membrane folding in glioblastoma cell lines differing in PTEN and p53 status.

    Directory of Open Access Journals (Sweden)

    Simon Memmel

    Full Text Available Glioblastoma multiforme (GBM is characterized by rapid growth, invasion and resistance to chemo-/radiotherapy. The complex cell surface morphology with abundant membrane folds, microvilli, filopodia and other membrane extensions is believed to contribute to the highly invasive behavior and therapy resistance of GBM cells. The present study addresses the mechanisms leading to the excessive cell membrane area in five GBM lines differing in mutational status for PTEN and p53. In addition to scanning electron microscopy (SEM, the membrane area and folding were quantified by dielectric measurements of membrane capacitance using the single-cell electrorotation (ROT technique. The osmotic stability and volume regulation of GBM cells were analyzed by video microscopy. The expression of PTEN, p53, mTOR and several other marker proteins involved in cell growth and membrane synthesis were examined by Western blotting. The combined SEM, ROT and osmotic data provided independent lines of evidence for a large variability in membrane area and folding among tested GBM lines. Thus, DK-MG cells (wild type p53 and wild type PTEN exhibited the lowest degree of membrane folding, probed by the area-specific capacitance C m = 1.9 µF/cm(2. In contrast, cell lines carrying mutations in both p53 and PTEN (U373-MG and SNB19 showed the highest C m values of 3.7-4.0 µF/cm(2, which corroborate well with their heavily villated cell surface revealed by SEM. Since PTEN and p53 are well-known inhibitors of mTOR, the increased membrane area/folding in mutant GBM lines may be related to the enhanced protein and lipid synthesis due to a deregulation of the mTOR-dependent downstream signaling pathway. Given that membrane folds and extensions are implicated in tumor cell motility and metastasis, the dielectric approach presented here provides a rapid and simple tool for screening the biophysical cell properties in studies on targeting chemo- or radiotherapeutically the

  10. Cell-surface expression of Hsp70 on hematopoietic cancer cells after inhibition of HDAC activity

    DEFF Research Database (Denmark)

    Jensen, Helle

    -derived antigenic peptides, a function which is currently explored in immunotherapeutic approaches against cancer. Additionally, membrane-bound Hsp70 can stimulate antigen presenting cells to release proinflammatory cytokines and can provide a target structure for NK cell-mediated lysis. Human cancer cells...... frequently express Hsp70 on their cell surface, whereas the corresponding normal tissues do not. In addition, several clinically applied reagents, such as alkyl-lysophospholipides, chemotherapeutic agents, and anti-inflammatory reagents, have been found to enhance Hsp70 cell surface expression on cancer...... cells. We have found that inhibition of histone deacetylase (HDAC) activity leads to surface expression of Hsp70 on various hematopoietic cancer cells, an occurance that was not observed on naïve or activated peripheral blood cells. HDAC-inhibitor mediated Hsp70 cell surface expression was confined...

  11. Green Synthesis and Antimicrobial Activities of Silver Nanoparticles using Cell Free-Extracts of Enterococcus species

    Directory of Open Access Journals (Sweden)

    Iyabo C. OLADIPO

    2017-06-01

    Full Text Available Cell-free extracts of six strains of Enterococcus species obtained from fermented foods were used for the green synthesis of silver nanoparticles (AgNPs, which was characterized by UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR and transmission electron microscopy (TEM. The biosynthesized AgNPs were dark brown in colour having surface plasmon resonance in the range of 420-442 nm. The spherical shaped AgNPs had sizes of 4-55 nm, whose formations were facilitated by proteins as indicated by the presence of peaks 1,635-1,637 and 3,275-3,313 cm-1 in the FTIR spectra. The energy dispersive x-ray (EDX showed prominent presence of silver in the AgNPs colloidal solution, while the selected area electron diffraction was typified by the face-centred crystalline nature of silver. The particles inhibited the growth of multi-drug resistant clinical isolates of Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris, and also potentiated the activities of ampicillin, ciprofloxacin and cefuroxime in the AgNPs-antibiotic synergy studies. In addition, the prospective relevance of the particles as nanopreservative in paints was demonstrated with the inhibition of growth of Staphylococcus aureus, Pseudomonas aeruginosa, Aspergillus niger and A. flavus in AgNPs-paint admixture. This report further demonstrates the green synthesis of AgNPs by strains of Enterococcus species.

  12. Zinc uptake by brain cells: `surface' versus `bulk'

    Science.gov (United States)

    DeStasio, Gelsomina; Pochon, S.; Lorusso, G. F.; Tonner, B. P.; Mercanti, Delio; Ciotti, M. Teresa; Oddo, Nino; Galli, Paolo; Perfetti, P.; Margaritondo, G.

    1996-08-01

    The uptake of zinc by cerebellar rat cultures upon exposure to 0022-3727/29/8/023/img12 solutions was comparatively investigated using two well known condensed matter physics techniques: synchrotron photoelectron spectromicroscopy and inductively coupled plasma atomic emission spectroscopy. The objective was to apply a strategy - well known in surface physics - to distinguish between `surface' and `bulk' phenomena. The results clearly demonstrate that exposure significantly enhances the bulk (cell cytoplasm) Zn concentration with respect to the physiological level, whereas the effect on the surface (cell membrane) is negligible.

  13. Synthesis and surface active properties of cationic surface active agents from crude rice bran oil

    Directory of Open Access Journals (Sweden)

    El-Dougdoug, W. I. A.

    1999-10-01

    Full Text Available Cationic surfactants of 2-hidroxy-3-(2- alkylamidopolyethyl amino propane-1-triethylammonium hydroxides (ix-xuia-d were prepared from fatty acids (ia-d [palmitic, stearic, oleic, linoleic acid] and mixed fatty acids of crude rice bran oil ie [RBO]. The reaction of these acids with ethylenediamine, diethylenetriamine, triethylenetetramine andletraethylenepentamine (iia-d produced (iii-viia-d. The produced amidopolyethylamine (iii-viia-d reacted with 2-epoxypropylenetriethylammonium chloride (viii to give the cationic surfactants (ix-xiiia-d . The produced derivatives were purified and characterized by microanalysis, molecular weight determination, infra-red (IR, and proton nuclear magnetic resonance (1H NMR spectra. The surface active properties and inhibition efficiency of the prepared cationic surfactants were determined.

    Se han preparado tensioactivos catiónicos de hidróxidos de! 2-hidroxi-3-(2-alquilamidopolietilamino propano-1;trietilamonio (ix-xiiia-d a partir de los ácidos grasos (ia-d [ácido palmítico, esteárico, oleico y linoleico] y mezclas de ácidos grasos de aceite de germen de arroz crudo ie [RBO]. La reacción de estos ácidos con etilenodiamina, dietilenotriamina, trietilenotetramina y tetraetilenopentamina (iia-d produjo los compuestos (iv-viia-d . Los amidopolietilaminos producidos (iii-viia-d reaccionaron con el cloruro de 2-epoxipropilenotrietilamonio (viii para dar los tensioactivos catiónicos (ix-xiiia-d. Los derivados producidos se purificaron y caracterizaron por microanálisis, determinación del peso molecular, espectros de infrarrojo (IR y resonancia magnética nuclear de protón (1H NMR. Se determinaron las propiedades tensioactivas y la eficacia de inhibición de los tensioactivos cati

  14. Transforming ocular surface stem cell research into successful clinical practice

    Directory of Open Access Journals (Sweden)

    Virender S Sangwan

    2014-01-01

    Full Text Available It has only been a quarter of a century since the discovery of adult stem cells at the human corneo-scleral limbus. These limbal stem cells are responsible for generating a constant and unending supply of corneal epithelial cells throughout life, thus maintaining a stable and uniformly refractive corneal surface. Establishing this hitherto unknown association between ocular surface disease and limbal dysfunction helped usher in therapeutic approaches that successfully addressed blinding conditions such as ocular burns, which were previously considered incurable. Subsequent advances in ocular surface biology through basic science research have translated into innovations that have made the surgical technique of limbal stem cell transplantation simpler and more predictable. This review recapitulates the basic biology of the limbus and the rationale and principles of limbal stem cell transplantation in ocular surface disease. An evidence-based algorithm is presented, which is tailored to clinical considerations such as laterality of affliction, severity of limbal damage and concurrent need for other procedures. Additionally, novel findings in the form of factors influencing the survival and function of limbal stem cells after transplantation and the possibility of substituting limbal cells with epithelial stem cells of other lineages is also discussed. Finally this review focuses on the future directions in which both basic science and clinical research in this field is headed.

  15. Amplified effect of surface charge on cell adhesion by nanostructures

    Science.gov (United States)

    Xu, Li-Ping; Meng, Jingxin; Zhang, Shuaitao; Ma, Xinlei; Wang, Shutao

    2016-06-01

    Nano-biointerfaces with varied surface charge can be readily fabricated by integrating a template-based process with maleimide-thiol coupling chemistry. Significantly, nanostructures are employed for amplifying the effect of surface charge on cell adhesion, as revealed by the cell-adhesion performance, cell morphology and corresponding cytoskeletal organization. This study may provide a promising strategy for developing new biomedical materials with tailored cell adhesion for tissue implantation and regeneration.Nano-biointerfaces with varied surface charge can be readily fabricated by integrating a template-based process with maleimide-thiol coupling chemistry. Significantly, nanostructures are employed for amplifying the effect of surface charge on cell adhesion, as revealed by the cell-adhesion performance, cell morphology and corresponding cytoskeletal organization. This study may provide a promising strategy for developing new biomedical materials with tailored cell adhesion for tissue implantation and regeneration. Electronic supplementary information (ESI) available: Experimental details, SEM, KFM AFM, chemical modification and characterization. See DOI: 10.1039/c6nr00649c

  16. Surface modified stainless steels for PEM fuel cell bipolar plates

    Science.gov (United States)

    Brady, Michael P [Oak Ridge, TN; Wang, Heli [Littleton, CO; Turner, John A [Littleton, CO

    2007-07-24

    A nitridation treated stainless steel article (such as a bipolar plate for a proton exchange membrane fuel cell) having lower interfacial contact electrical resistance and better corrosion resistance than an untreated stainless steel article is disclosed. The treated stainless steel article has a surface layer including nitrogen-modified chromium-base oxide and precipitates of chromium nitride formed during nitridation wherein oxygen is present in the surface layer at a greater concentration than nitrogen. The surface layer may further include precipitates of titanium nitride and/or aluminum oxide. The surface layer in the treated article is chemically heterogeneous surface rather than a uniform or semi-uniform surface layer exclusively rich in chromium, titanium or aluminum. The precipitates of titanium nitride and/or aluminum oxide are formed by the nitriding treatment wherein titanium and/or aluminum in the stainless steel are segregated to the surface layer in forms that exhibit a low contact resistance and good corrosion resistance.

  17. Action of cytochalasin D on cells of established lines. III. Zeiosis and movements at the cell surface.

    Science.gov (United States)

    Godman, G C; Miranda, A F; Deitch, A D; Tanenbaum, S W

    1975-03-01

    The projection of knobby protuberances at the cell surface (zeiosis) is a general cellular response to cytochalasin D (CD), resulting from herniation of endoplasm through undefended places of the cortex during cell contractions and displacement of microfilaments induced by CD. Zeiosis is prevented by agents that interfere with the contractile response to CD, such as inhibitors of energy metabolism or cyclic AMP. The developed protrusions, which remain relatively stable in the presence of CD, contain chiefly mono- or subribosomes, and occasionally other organelles normally resident in endoplasm; compact microfilament felt occupies their bases and extends into their proximal stalks. Protein synthesis in the knobs is less than half of that in the polyribosome-containing endoplasm residual in the main body of the cell. Knobs first protrude singly near the margin of the contracting cells and rapidly cluster into small groups in the periphery even at lower temperature. The clusters then migrate centripetally and coalesce into a large aggregate near the apex of the immobilized and retracted cell: this movement is energy- and temperature-dependent. Aggregation is more prominent and stable in cell lines of epithelial derivation than in fibroblastic or other lines in which nuclear extrusion occurs more readily. The latter is regarded as a special manifestation of zeiosis. Macromarkers, such as latex spherules, migrate like the zeiotic knobs on the cell surfaces in the presence of CD. The aggregated knobs, although persistent for days in the presence of CD, are rapidly recessed after withdrawal of the agent as ruffling is resumed and the cells spread. These movements are discussed in terms of current concepts of mobility of the cell membrane.

  18. CD44 is the principal cell surface receptor for hyaluronate.

    Science.gov (United States)

    Aruffo, A; Stamenkovic, I; Melnick, M; Underhill, C B; Seed, B

    1990-06-29

    CD44 is a broadly distributed cell surface protein thought to mediate cell attachment to extracelular matrix components or specific cell surface ligands. We have created soluble CD44-immunoglobulin fusion proteins and characterized their reactivity with tissue sections and lymph node high endothelial cells in primary culture. The CD44 target on high endothelial cells is sensitive to enzymes that degrade hyaluronate, and binding of soluble CD44 is blocked by low concentrations of hyaluronate or high concentrations of chondroitin 4- and 6-sulfates. A mouse anti-hamster hyaluonate receptor antibody reacts with COS cells expressing hamster CD44 cDNA. In sections of all tissues examined, including lymph nodes and Peyer's patches, predigestion with hyaluronidase eliminated CD44 binding.

  19. Soluble and cell surface receptors for tumor necrosis factor

    DEFF Research Database (Denmark)

    Wallach, D; Engelmann, H; Nophar, Y

    1991-01-01

    Tumor necrosis factor (TNF) initiates its multiple effects on cell function by binding at a high affinity to specific cell surface receptors. Two different molecular species of these receptors, which are expressed differentially in different cells, have been identified. The cDNAs of both receptor...... have recently been cloned. Antibodies to one of these receptor species (the p55, type I receptor) can trigger a variety of TNF like effects by cross-linking of the receptor molecules. Thus, it is not TNF itself but its receptors that provide the signal for the response to this cytokine...... in certain pathological situations. Release of the soluble receptors from the cells seems to occur by proteolytic cleavage of the cell surface forms and appears to be a way of down-regulating the cell response to TNF. Because of their ability to bind TNF, the soluble receptors exert an inhibitory effect...

  20. Specific nature of Trichomonas vaginalis parasitism of host cell surfaces.

    Science.gov (United States)

    Alderete, J F; Garza, G E

    1985-01-01

    The adherence of Trichomonas vaginalis NYH 286 to host cells was evaluated by using monolayer cultures of HeLa and HEp-2 epithelial cells and human fibroblast cell lines. Saturation of sites on HeLa cells was achieved, yielding a maximal T. vaginalis NYH 286-to-cell ratio of two. The ability of radiolabeled NYH 286 to compete with unlabeled trichomonads for attachment and the time, temperature, and pH-dependent nature of host cell parasitism reinforced the idea of specific parasite-cell associations. Other trichomonal isolates (JH31A, RU375, and JHHR) were also found to adhere to cell monolayers, albeit to different degrees, and all isolates produced maximal contact-dependent HeLa cell cytotoxicity. The avirulent trichomonad, Trichomonas tenax, did not adhere to cell monolayers and did not cause host cell damage. Interestingly, parasite cytadherence was greater with HeLa and HEp-2 epithelial cells than with fibroblast cells. In addition, cytotoxicity with fibroblast cells never exceeded 20% of the level of cell killing observed for epithelial cells. Elucidation of properties of the pathogenic human trichomonads that allowed for host cell surface parasitism was also attempted. Treatment of motile T. vaginalis NYH 286 with trypsin diminished cell parasitism. Incubation of trypsinized organisms in growth medium allowed for regeneration of trichomonal adherence, and cycloheximide inhibited the regeneration of attachment. Organisms poisoned with metronidazole or iodoacetate failed to attach to host cells, and adherent trichomonads exposed to metronidazole or iodoacetate were readily released from parasitized cells. Coincubation experiments with polycationic proteins and sugars and pretreatment of parasites or cells with neuraminidase or periodate had no effect on host cell parasitism. Colchicine and cytochalasin B, however, did produce some inhibition of adherence to HeLa cells. The data suggest that metabolizing T. vaginalis adheres to host cells via parasite surface

  1. Sulforaphane, a cruciferous vegetable-derived isothiocyanate, inhibits protein synthesis in human prostate cancer cells.

    Science.gov (United States)

    Wiczk, Aleksandra; Hofman, Dagmara; Konopa, Grażyna; Herman-Antosiewicz, Anna

    2012-08-01

    Sulforaphane (SFN) is a compound derived from cruciferous plants. Its anticancer properties have been demonstrated both, in cancer cell lines as well as tumors in animal models. It has been shown that SFN inhibits cell proliferation, induces apoptosis, autophagy, and sensitizes cancer cells to therapies. As induction of catabolic processes is often related to perturbation in protein synthesis we aimed to investigate the impact of SFN on this process in PC-3 human prostate cancer cells. In the present study we show that SFN inhibits protein synthesis in PC-3 cells in a dose- and time-dependent manner which is accompanied by a decreased phosphorylation of mTOR substrates. Translation inhibition is independent of mitochondria-derived ROS as it is observed in PC-3 derivatives devoid of functional mitochondrial respiratory chain (Rho0 cells). Although SFN affects mitochondria and slightly decreases glycolysis, the ATP level is maintained on the level characteristic for control cells. Inhibition of protein synthesis might be a protective response of prostate cancer cells to save energy. However, translation inhibition contributes to the death of PC-3 cells due to decreased level of a short-lived protein, survivin. Overexpression of this anti-apoptotic factor protects PC-3 cells against SFN cytotoxicity. Protein synthesis inhibition by SFN is not restricted to prostate cancer cells as we observed similar effect in SKBR-3 breast cancer cell line. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Antifouling property of highly oleophobic substrates for solar cell surfaces

    Science.gov (United States)

    Fukada, Kenta; Nishizawa, Shingo; Shiratori, Seimei

    2014-03-01

    Reduction of solar cell conversion efficiency by bird spoor or oil smoke is a common issue. Maintaining the surface of solar cells clean to retain the incident light is of utmost importance. In this respect, there has been growing interest in the area of superhydrophobicity for developing water repelling and self-cleaning surfaces. This effect is inspired by lotus leaves that have micro papillae covered with hydrophobic wax nanostructures. Superhydrophobic surfaces on transparent substrates have been developed for removing contaminants from solar cell surfaces. However, oil cannot be removed by superhydrophobic effect. In contrast, to prevent bird spoor, a highly oleophobic surface is required. In a previous study, we reported transparent-type fabrics comprising nanoparticles with a nano/micro hierarchical structure that ensured both oleophobicity and transparency. In the current study, we developed new highly oleophobic stripes that were constructed into semi-transparent oleophobic surfaces for solar cells. Solar cell performance was successfully maintained; the total transmittance was a key factor for determining conversion efficiency.

  3. Recent progress in design, synthesis, and applications of one-dimensional TiO2 nanostructured surface heterostructures: a review.

    Science.gov (United States)

    Tian, Jian; Zhao, Zhenhuan; Kumar, Anil; Boughton, Robert I; Liu, Hong

    2014-01-01

    One-dimensional TiO2 nanostructured surface heterostructures (1D TiO2NSHs) have been comprehensively studied during the past two decades because of the possible practical applications in various fields, including photocatalysis, dye-sensitized solar cells, sensors, lithium batteries, biomedicine, catalysis, and supercapacitors. Combining extensive advancements in materials science and nanotechnology, a 1D TiO2NSH material with well-controlled size, morphology, and composition has been designed and synthesized. More importantly, its superior properties, including a high aspect ratio structure, chemical stability, large specific surface area, excellent electronic or ionic charge transfer, and a specific interface effect, have attracted a great deal of interest in improving current performance and exploring new applications. In this tutorial review, we introduce the characteristics of 1D TiO2 nanostructures, the design principles for the fabrication of 1D TiO2NSHs, and we also summarize the recent progress in developing synthesis methods and applications of 1D TiO2NSHs in different fields. The relationship between the secondary phase and the 1D TiO2 nanostructure and between the performance in applications and the excellent physical properties of 1D TiO2NSHs are also discussed.

  4. Plasma synthesis and liquid-phase surface passivation of brightly luminescent Si nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Mangolini, L. [Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE, Minneapolis, MN 55455 (United States); Jurbergs, D. [InnovaLight, Inc., 3303 Octavius Dr., Suite 104, Santa Clara, CA 95054 (United States); Rogojina, E. [InnovaLight, Inc., 3303 Octavius Dr., Suite 104, Santa Clara, CA 95054 (United States); Kortshagen, U. [Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE, Minneapolis, MN 55455 (United States)]. E-mail: uk@me.umn.edu

    2006-12-15

    While silicon's optical properties are improved at the nanoscale, they also become highly sensitive to the properties of the surfaces and interfaces of silicon nanostructures. For instance, while reported quantum yields for photoluminescence of silicon quantum dots covered by a native oxide are often in the few percent range, quantum yields as high as 30% have been found in quantum dots whose surfaces were passivated by covalently bonded organic molecules. In this paper, we describe an approach that is based on the gas phase synthesis of silicon quantum dots in a nonthermal plasma, and the subsequent organic surface passivation in the liquid phase. Nanocrystals are formed within a few milliseconds with a high mass yield in a nonthermal plasma. Various organic ligands such as octadecene, dodecence, and styrene are grafted onto the nanocrystal surfaces in a reaction known as hydrosilylation. Materials are characterized through transmission electron microscopy, atomic force microscopy, and fluorescence measurements. The particle size distributions are found to be relatively monodisperse and are well controllable through the plasma process parameters. Photoluminescence quantum yields as high as 60-70% have been achieved for particles luminescing in the red range of the visible spectrum.

  5. Heparin prevents intracellular hyaluronan synthesis and autophagy responses in hyperglycemic dividing mesangial cells and activates synthesis of an extensive extracellular monocyte-adhesive hyaluronan matrix after completing cell division.

    Science.gov (United States)

    Wang, Aimin; Ren, Juan; Wang, Christina P; Hascall, Vincent C

    2014-03-28

    Growth-arrested rat mesangial cells (RMCs) at a G0/G1 interphase stimulated to divide in hyperglycemic medium initiate intracellular hyaluronan synthesis that induces autophagy/cyclin D3-induced formation of a monocyte-adhesive extracellular hyaluronan matrix after completing cell division. This study shows that heparin inhibits the intracellular hyaluronan synthesis and autophagy responses, but at the end of cell division it induces synthesis of a much larger extracellular monocyte-adhesive hyaluronan matrix. Heparin bound to RMC surfaces by 1 h, internalizes into the Golgi/endoplasmic reticulum region by 2 h, and was nearly gone by 4 h. Treatment by heparin for only the first 4 h was sufficient for its function. Streptozotocin diabetic rats treated daily with heparin showed similar results. Glomeruli in sections of diabetic kidneys showed extensive accumulation of autophagic RMCs, increased hyaluronan matrix, and influx of macrophages over 6 weeks. Hyaluronan staining in the glomeruli of heparin-treated diabetic rats was very high at week 1 and decreased to near control level by 6 weeks without any RMC autophagy. However, the influx of macrophages by 6 weeks was as pronounced as in diabetic glomeruli. The results are as follows: 1) heparin blocks synthesis of hyaluronan in intracellular compartments, which prevents the autophagy and cyclin D3 responses thereby allowing RMCs to complete cell division and sustain function; 2) interaction of heparin with RMCs in early G1 phase is sufficient to induce signaling pathway(s) for its functions; and 3) influxed macrophages effectively remove the hyaluronan matrix without inducing pro-fibrotic responses that lead to nephropathy and proteinurea in diabetic kidneys.

  6. Cell-surface acceleration of urokinase-catalyzed receptor cleavage

    DEFF Research Database (Denmark)

    Høyer-Hansen, G; Ploug, M; Behrendt, N

    1997-01-01

    The urokinase-type plasminogen activator (uPA) binds to a specific cell-surface receptor, uPAR. On several cell types uPAR is present both in the full-length form and a cleaved form, uPAR(2+3), which is devoid of binding activity. The formation of uPAR(2+3) on cultured U937 cells is either direct...

  7. Effect of hydroxyapatite surface morphology on cell adhesion.

    Science.gov (United States)

    Iwamoto, Takashi; Hieda, Yohki; Kogai, Yasumichi

    2016-12-01

    We obtained hydroxyapatite (HAp) materials as a block by mixing HAp nanoparticles and polymer, and then calcining the mixtures. The surface morphology of the HAp materials was tuned by varying heat treatment conditions. After calcining the mixtures at 1200 or 800°C for 4h, the surface morphology of the HAp materials was flat or convexo-concave, respectively. The flat surface morphology, which showed micrometer-ordered grain boundaries, was formed by the aggregation of HAp nanoparticles. On the other hand, the convexo-concave surface morphology resulted from the agglomeration of HAp nanoparticles after heat treatment at 800°C for 4h with nanometer-ordered particle size. We tested cell adhesion to HAp materials with flat or convexo-concave surface morphology and found that cells adhered well to the flat HAp materials but not to the convexo-concave HAp materials. This technique for selectively preparing HAp materials with flat or convexo-concave surface morphology was very easy because we merely mixed commercial HAp nanoparticles with polymer and then calcined the mixtures. As a result, the heat treatment temperature affected the surface morphology of our HAp materials, and their surface morphologies contributed to cell adhesion independently of other material properties.

  8. A continuous-exchange cell-free protein synthesis system based on extracts from cultured insect cells.

    Directory of Open Access Journals (Sweden)

    Marlitt Stech

    Full Text Available In this study, we present a novel technique for the synthesis of complex prokaryotic and eukaryotic proteins by using a continuous-exchange cell-free (CECF protein synthesis system based on extracts from cultured insect cells. Our approach consists of two basic elements: First, protein synthesis is performed in insect cell lysates which harbor endogenous microsomal vesicles, enabling a translocation of de novo synthesized target proteins into the lumen of the insect vesicles or, in the case of membrane proteins, their embedding into a natural membrane scaffold. Second, cell-free reactions are performed in a two chamber dialysis device for 48 h. The combination of the eukaryotic cell-free translation system based on insect cell extracts and the CECF translation system results in significantly prolonged reaction life times and increased protein yields compared to conventional batch reactions. In this context, we demonstrate the synthesis of various representative model proteins, among them cytosolic proteins, pharmacological relevant membrane proteins and glycosylated proteins in an endotoxin-free environment. Furthermore, the cell-free system used in this study is well-suited for the synthesis of biologically active tissue-type-plasminogen activator, a complex eukaryotic protein harboring multiple disulfide bonds.

  9. Surface modification of closed plastic bags for adherent cell cultivation

    Science.gov (United States)

    Lachmann, K.; Dohse, A.; Thomas, M.; Pohl, S.; Meyring, W.; Dittmar, K. E. J.; Lindenmeier, W.; Klages, C.-P.

    2011-07-01

    In modern medicine human mesenchymal stem cells are becoming increasingly important. However, a successful cultivation of this type of cells is only possible under very specific conditions. Of great importance, for instance, are the absence of contaminants such as foreign microbiological organisms, i.e., sterility, and the chemical functionalization of the ground on which the cells are grown. As cultivation of these cells makes high demands, a new procedure for cell cultivation has been developed in which closed plastic bags are used. For adherent cell growth chemical functional groups have to be introduced on the inner surface of the plastic bag. This can be achieved by a new, atmospheric-pressure plasma-based method presented in this paper. The method which was developed jointly by the Fraunhofer IST and the Helmholtz HZI can be implemented in automated equipment as is also shown in this contribution. Plasma process gases used include helium or helium-based gas mixtures (He + N2 + H2) and vapors of suitable film-forming agents or precursors such as APTMS, DACH, and TMOS in helium. The effect of plasma treatment is investigated by FTIR-ATR spectroscopy as well as surface tension determination based on contact angle measurements and XPS. Plasma treatment in nominally pure helium increases the surface tension of the polymer foil due to the presence of oxygen traces in the gas and oxygen diffusing through the gas-permeable foil, respectively, reacting with surface radical centers formed during contact with the discharge. Primary amino groups are obtained on the inner surface by treatment in mixtures with nitrogen and hydrogen albeit their amount is comparably small due to diffusion of oxygen through the gas-permeable bag, interfering with the plasma-amination process. Surface modifications introducing amino groups on the inner surface turned out to be most efficient in the promotion of cell growth.

  10. Anisotropic cell growth-regulated surface micropatterns in flower petals

    Directory of Open Access Journals (Sweden)

    Xiao Huang

    2017-05-01

    Full Text Available Flower petals have not only diverse macroscopic morphologies but are rich in microscopic surface patterns, which are crucial to their biological functions. Both experimental measurements and theoretical analysis are conducted to reveal the physical mechanisms underlying the formation of minute wrinkles on flower petals. Three representative flowers, daisy, kalanchoe blossfeldiana, and Eustoma grandiflorum, are investigated as examples. A surface wrinkling model, incorporating the measured mechanical properties and growth ratio, is used to elucidate the difference in their surface morphologies. The mismatch between the anisotropic epidermal cell growth and the isotropic secretion of surficial wax is found to dictate the surface patterns.

  11. Cell-surface expression of Hsp70 on hematopoietic cancer cells after inhibition of HDAC activity

    DEFF Research Database (Denmark)

    Jensen, Helle; Andresen, Lars; Hansen, Karen Aagaard

    , membrane-bound Hsp70 can stimulate antigen presenting cells (APCs) to release proinflammatory cytokines and can provide a target structure for NK cell-mediated lysis. Human cancer cells frequently express Hsp70 on their cell surface, whereas the corresponding normal tissues do not. In addition, several...... clinically applied reagents, such as alkyl-lysophospholipides, chemotherapeutic agents, and anti-inflammatory reagents, have been found to enhance Hsp70 surface expression on cancer cells. We have found that inhibition of histone deacetylase (HDAC) activity leads to surface expression of Hsp70 on various...... hematopoietic cancer cells, an occurance that was not observed on naïve or activated peripheral blood cells. HDAC-inhibitor mediated Hsp70 surface expression was confined to the apoptotic Annexin V positive cells and blocked by inhibition of apoptosis. Other chemotherapeutic inducers of apoptosis...

  12. Adhesion defective BHK cell mutant has cell surface heparan sulfate proteoglycan of altered properties

    DEFF Research Database (Denmark)

    Couchman, J R; Austria, R; Woods, A;

    1988-01-01

    In the light of accumulating data that implicate cell surface heparan sulfate proteoglycans (HSPGs) with a role in cell interactions with extracellular matrix molecules such as fibronectin, we have compared the properties of these molecules in wild-type BHK cells and an adhesion-defective ricin......-resistant mutant (RicR14). Our results showed that the mutant, unlike BHK cells, cannot form focal adhesions when adherent to planar substrates in the presence of serum. Furthermore, while both cell lines possess similar amounts of cell surface HSPG with hydrophobic properties, that of RicR14 cells had decreased...

  13. Engineered microtopographies and surface chemistries direct cell attachment and function

    Science.gov (United States)

    Magin, Chelsea Marie

    Harrison, in 1914, first recognized that cells respond to physicochemical cues such as substratum topography when he observed that fibroblasts elongated while cultured on spider silk. Recently, techniques developed in the micro-electronics industry have been used to create molds for producing microscaled topographies with various shapes and spatial arrangements. Although these patterning techniques are well-established, very little is known about the mechanisms underlying cell sensing and response to microtopographies. In this work cellular micro-environments with varying surface topographies and chemistries were evaluated with marine organisms and mammalian cells to investigate cellular sensing and response. Biofouling---the accumulation of micro-organisms, plants, and animals on submerged surfaces---is an environmental and economic concern. Engineered topographies, replicated in polydimethylsiloxane elastomer (PDMSe) and functionalized poly(ethylene glycol)-dimethacrylate (PEGDMA) hydrogels, were evaluated for inhibition of marine fouling organism attachment. Microtopographies replicated in PDMSe inhibited attachment of the marine bacterium, Cobetia marina up to 99% versus smooth. The average normalized attachment densities of cells of C. marina and zoospores of the green algae Ulva on PDMSe topographies scaled inversely with the Engineered Roughness Index (ERIII), a representation of surface energy. Attachment densities of Ulva from four assays and C. marina from two growth phases to PDMSe surfaces scaled inversely with one equation: ERI II multiplied by the Reynolds number of the organism (Re) (R 2 = 0.77). The same microtopographies created in PDMSe reduced the initial attachment density and attachment strength of cells of the diatoms Navicula incerta and Seminavis robusta compared to smooth PDMSe. The average normalized attachment density of Navicula after exposure to shear stress (48 Pa) was correlated with the contact area between the diatom and a

  14. A cell cycle and nutritional checkpoint controlling bacterial surface adhesion.

    Directory of Open Access Journals (Sweden)

    Aretha Fiebig

    2014-01-01

    Full Text Available In natural environments, bacteria often adhere to surfaces where they form complex multicellular communities. Surface adherence is determined by the biochemical composition of the cell envelope. We describe a novel regulatory mechanism by which the bacterium, Caulobacter crescentus, integrates cell cycle and nutritional signals to control development of an adhesive envelope structure known as the holdfast. Specifically, we have discovered a 68-residue protein inhibitor of holdfast development (HfiA that directly targets a conserved glycolipid glycosyltransferase required for holdfast production (HfsJ. Multiple cell cycle regulators associate with the hfiA and hfsJ promoters and control their expression, temporally constraining holdfast development to the late stages of G1. HfiA further functions as part of a 'nutritional override' system that decouples holdfast development from the cell cycle in response to nutritional cues. This control mechanism can limit surface adhesion in nutritionally sub-optimal environments without affecting cell cycle progression. We conclude that post-translational regulation of cell envelope enzymes by small proteins like HfiA may provide a general means to modulate the surface properties of bacterial cells.

  15. Development of exosome surface display technology in living human cells.

    Science.gov (United States)

    Stickney, Zachary; Losacco, Joseph; McDevitt, Sophie; Zhang, Zhiwen; Lu, Biao

    2016-03-25

    Surface display technology is an emerging key player in presenting functional proteins for targeted drug delivery and therapy. Although a number of technologies exist, a desirable mammalian surface display system is lacking. Exosomes are extracellular vesicles that facilitate cell-cell communication and can be engineered as nano-shuttles for cell-specific delivery. In this study, we report the development of a novel exosome surface display technology by exploiting mammalian cell secreted nano-vesicles and their trans-membrane protein tetraspanins. By constructing a set of fluorescent reporters for both the inner and outer surface display on exosomes at two selected sites of tetraspanins, we demonstrated the successful exosomal display via gene transfection and monitoring fluorescence in vivo. We subsequently validated our system by demonstrating the expected intracellular partitioning of reporter protein into sub-cellular compartments and secretion of exosomes from human HEK293 cells. Lastly, we established the stable engineered cells to harness the ability of this robust system for continuous production, secretion, and uptake of displayed exosomes with minimal impact on human cell biology. In sum, our work paved the way for potential applications of exosome, including exosome tracking and imaging, targeted drug delivery, as well as exosome-mediated vaccine and therapy.

  16. Cell surface differences of Naegleria fowleri and Naegleria lovaniensis exposed with surface markers.

    Science.gov (United States)

    González-Robles, Arturo; Castañón, Guadalupe; Cristóbal-Ramos, Ana Ruth; Hernández-Ramírez, Verónica Ivonne; Omaña-Molina, Maritza; Martínez-Palomo, Adolfo

    2007-12-01

    Differences in the distribution of diverse cell surface coat markers were found between Naegleria fowleri and Naegleria lovaniensis. The presence of carbohydrate-containing components in the cell coat of the two species was detected by selective staining with ruthenium red and alcian blue. Using both markers, N. fowleri presented a thicker deposit than N. lovaniensis. The existence of exposed mannose or glucose residues was revealed by discriminatory agglutination with the plant lectin Concanavalin A. These sugar residues were also visualized at the cell surface of these parasites either by transmission electron microscopy or by fluorescein-tagged Concanavalin A. Using this lectin cap formation was induced only in N. fowleri. The anionic sites on the cell surface detected by means of cationized ferritin were more apparent in N. fowleri. Biotinylation assays confirmed that even though the two amoebae species have some analogous plasma membrane proteins, there is a clear difference in their composition.

  17. Development of drug loaded nanoparticles for tumor targeting. Part 1: synthesis, characterization, and biological evaluation in 2D cell cultures

    Science.gov (United States)

    El-Dakdouki, Mohammad H.; Puré, Ellen; Huang, Xuefei

    2013-04-01

    Nanoparticles (NPs) are being extensively studied as carriers for drug delivery, but they often have limited penetration inside tumors. We envision that by targeting an endocytic receptor on the cell surface, the uptake of NPs can be significantly enhanced through receptor mediated endocytosis. In addition, if the receptor is recycled to the cell surface, the NP cargo can be transported out of the cells, which is then taken up by neighboring cells thus enhancing solid tumor penetration. To validate our hypothesis, in the first of two articles, we report the synthesis of doxorubicin (DOX)-loaded, hyaluronan (HA) coated silica nanoparticles (SNPs) containing a highly fluorescent core to target CD44, a receptor expressed on the cancer cell surface. HA was conjugated onto amine-functionalized SNPs prepared through an oil-water microemulsion method. The immobilization of the cytotoxic drug DOX was achieved through an acid sensitive hydrazone linkage. The NPs were fully characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements, thermogravimetric analysis (TGA), UV-vis absorbance, and nuclear magnetic resonance (NMR). Initial biological evaluation experiments demonstrated that compared to ligand-free SNPs, the uptake of HA-SNPs by the CD44-expressing SKOV-3 ovarian cancer cells was significantly enhanced when evaluated in the 2D monolayer cell culture. Mechanistic studies suggested that cellular uptake of HA-SNPs was mainly through CD44 mediated endocytosis. HA-SNPs with immobilized DOX were endocytosed efficiently by the SKOV-3 cells as well. The enhanced tumor penetration and drug delivery properties of HA-SNPs will be evaluated in 3D tumor models in the subsequent paper.Nanoparticles (NPs) are being extensively studied as carriers for drug delivery, but they often have limited penetration inside tumors. We envision that by targeting an endocytic receptor on the cell surface, the uptake of NPs can be

  18. Effect of Anatase Synthesis on the Performance of Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Sánchez-García, Mario Alberto; Bokhimi, Xim; Maldonado-Álvarez, Arturo; Jiménez-González, Antonio Esteban

    2015-12-01

    Anatase nanoparticles were synthesized from a titanium isopropoxide solution using a hydrothermal process at different pressures in an autoclave system while keeping the volume of the solution constant. As the autoclave pressure was increased from 1 to 71 atm (23 to 210 °C), the crystal size in the nanoparticles increased from 9 to 13.8 nm. The anatase nanoparticles were used to build dye-sensitized solar cells (DSSC). Mesoporous films of this oxide were deposited over conducting SnO2:F substrates using the screen-printing technique and then annealed at 530 °C at 1 atm of air pressure. The morphology of the mesoporous film surface of anatase, studied using scanning electron microscopy, revealed that the crystal size and pore distribution were functions of the pressure conditions. The energy band gap of the films as a function of the crystal size exhibited quantum effects below 11.8 nm. The effects of the anatase synthesis conditions and properties of the mesoporous film on the DSSC-type solar cell parameters, η%, V OC, J SC, and FF, were also investigated: the mesoporous anatase films prepared at 200 °C (54 atm of pressure in the autoclave) and annealed at 530 °C in air generated the best solar cell, having the highest conversion efficiency.

  19. Synthesis of Diamond Films on Molybdenum Substrate Surface by Combustion Flame

    Science.gov (United States)

    Takahashi, Mamoru; Kamiya, Osamu; Ohyoshi, Tadashi

    Diamond films were synthesized on a Mo substrate using combustion flame. During the cooling process, most diamond films delaminated. From previous work it was shown that diamond films delaminated at a synthesis temperature less than 1300K (low temperature), and films did not delaminate at synthesis temperature more than 1400K (high temperature). In this study, to clarify the influences on the delamination of the interface, films synthesized at high temperature and low temperature were investigated by SEM and X-ray diffraction. The results show that in the case of low temperature, diamond films were synthesized on the Mo substrate, case of high temperature, Mo2C and diamond phases were synthesized on the Mo substrate. Thermally induced interfacial stress occurs due to the thermal expansion mismatch between the synthesized film and the Mo substrate. The interfacial stress by high temperature and low temperature was determined as the cause of the delamination. Thus, the interfacial stress of each synthesized temperature was calculated by a finite element method. The results show that the interfacial stress in the film synthesized by high temperature was smaller than that by the low temperature. As the buffer phases prevent the delamination, synthesized films by high temperature will be useful as hardcoating layer for a metal surface.

  20. Cell patterning on polylactic acid through surface-tethered oligonucleotides.

    Science.gov (United States)

    Matsui, Toshiki; Arima, Yusuke; Takemoto, Naohiro; Iwata, Hiroo

    2015-02-01

    Polylactic acid (PLA) is a candidate material to prepare scaffolds for 3-D tissue regeneration. However, cells do not adhere or proliferate well on the surface of PLA because it is hydrophobic. We report a simple and rapid method for inducing cell adhesion to PLA through DNA hybridization. Single-stranded DNA (ssDNA) conjugated to poly(ethylene glycol) (PEG) and to a terminal phospholipid (ssDNA-PEG-lipid) was used for cell surface modification. Through DNA hybridization, modified cells were able to attach to PLA surfaces modified with complementary sequence (ssDNA'). Different cell types can be attached to PLA fibers and films in a spatially controlled manner by using ssDNAs with different sequences. In addition, they proliferate well in a culture medium supplemented with fetal bovine serum. The coexisting modes of cell adhesion through DNA hybridization and natural cytoskeletal adhesion machinery revealed no serious effects on cell growth. The combination of a 3-D scaffold made of PLA and cell immobilization on the PLA scaffold through DNA hybridization will be useful for the preparation of 3-D tissue and organs.

  1. Human CD4+ T cells require exogenous cystine for glutathione and DNA synthesis.

    Science.gov (United States)

    Levring, Trine B; Kongsbak, Martin; Rode, Anna K O; Woetmann, Anders; Ødum, Niels; Bonefeld, Charlotte Menné; Geisler, Carsten

    2015-09-08

    Adaptive immune responses require activation and expansion of antigen-specific T cells. Whereas early T cell activation is independent of exogenous cystine (Cys2), T cell proliferation is dependent of Cys2. However, the exact roles of Cys2 in T cell proliferation still need to be determined. The aim of this study was to elucidate why activated human T cells require exogenous Cys2 in order to proliferate. We activated purified naïve human CD4+ T cells and found that glutathione (GSH) levels and DNA synthesis were dependent on Cys2 and increased in parallel with increasing concentrations of Cys2. Vice-versa, the GSH synthesis inhibitor L-buthionine-sulfoximine (BSO) and inhibition of Cys2 uptake with glutamate inhibited GSH and DNA synthesis in parallel. We further found that thioredoxin (Trx) can partly substitute for GSH during DNA synthesis. Finally, we show that GSH or Trx is required for the activity of ribonucleotide reductase (RNR), the enzyme responsible for generation of the deoxyribonucleotide DNA building blocks. In conclusion, we show that activated human T cells require exogenous Cys2 to proliferate and that this is partly explained by the fact that Cys2 is required for production of GSH, which in turn is required for optimal RNR-mediated deoxyribonucleotide synthesis and DNA replication.

  2. Nanostructured electrocatalyst for fuel cells : silica templated synthesis of Pt/C composites.

    Energy Technology Data Exchange (ETDEWEB)

    Stechel, Ellen Beth; Switzer, Elise E.; Fujimoto, Cy H.; Atanassov, Plamen Borissov; Cornelius, Christopher James; Hibbs, Michael R.

    2007-09-01

    Platinum-based electrocatalysts are currently required for state-of-the-art fuel cells and represent a significant portion of the overall fuel cell cost. If fuel cell technology is to become competitive with other energy conversion technologies, improve the utilization of precious metal catalysts is essential. A primary focus of this work is on creating enhanced nanostructured materials which improve precious-metal utilization. The goal is to engineer superior electrocatalytic materials through the synthesis, development and investigation of novel templated open frame structures synthesized in an aerosol-based approach. Bulk templating methods for both Pt/C and Pt-Ru composites are evaluated in this study and are found to be limited due to the fact that the nanostructure is not maintained throughout the entire sample. Therefore, an accurate examination of structural effects was previously impossible. An aerosol-based templating method of synthesizing nanostructured Pt-Ru electrocatalysts has been developed wherein the effects of structure can be related to electrocatalytic performance. The aerosol-based templating method developed in this work is extremely versatile as it can be conveniently modified to synthesize alternative materials for other systems. The synthesis method was able to be extended to nanostructured Pt-Sn for ethanol oxidation in alkaline media. Nanostructured Pt-Sn electrocatalysts were evaluated in a unique approach tailored to electrocatalytic studies in alkaline media. At low temperatures, nanostructured Pt-Sn electrocatalysts were found to have significantly higher ethanol oxidation activity than a comparable nanostructured Pt catalyst. At higher temperatures, the oxygen-containing species contribution likely provided by Sn is insignificant due to a more oxidized Pt surface. The importance of the surface coverage of oxygen-containing species in the reaction mechanism is established in these studies. The investigations in this work present

  3. Stimulation of DNA synthesis in cultured rat alveolar type II cells

    Energy Technology Data Exchange (ETDEWEB)

    Leslie, C.C.; McCormick-Shannon, K.; Robinson, P.C.; Mason, R.J.

    1985-01-01

    Restoration of the alveolar epithelium after injury is thought to be dependent on the proliferation of alveolar type II cells. To understand the factors that may be involved in promoting type II cell proliferation in vivo, we determined the effect of potential mitogens and culture substrata on DNA synthesis in rat alveolar type II cells in primary culture. Type II cells cultured in basal medium containing 10% fetal bovine serum (FBS) exhibited essentially no DNA synthesis. Factors that stimulated /sup 3/H-thymidine incorporation included cholera toxin, epidermal growth factor, and rat serum. The greatest degree of stimulation was achieved by plating type II cells on an extracellular matrix prepared from bovine corneal endothelial cells and then by culturing the pneumocytes in medium containing rat serum, cholera toxin, insulin, and epidermal growth factor. Under conditions of stimulation of /sup 3/H-thymidine incorporation there was an increased DNA content per culture dish but no increase in cell number. The ability of various culture conditions to promote DNA synthesis in type II cells was verified by autoradiography. Type II cells were identified by the presence of cytoplasmic inclusions, which were visualized by tannic acid staining before autoradiography. These results demonstrate the importance of soluble factors and culture substratum in stimulating DNA synthesis in rat alveolar type II cells in primary culture.

  4. Hepatic Bel-7402 Cell Proliferation on Different Phospholipid Surfaces

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Phospholipids are believed to be important biomaterials.However, limited information is available on their cytocompatibilities.The objective of this study is to evaluate the effects of different phospholipids on the proliferation of hepatic Bel-7402 cells by comparing the adhesion, viability and proliferation of Bel-7402 cells cultured on different phospholipid surfaces.The cell adhesion, determined by counting the number of adhered cells to the surface, indicated that the cell adhesion was enhanced on charged phospolipid membranes.The cell viability evaluated by MTT[3 (4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium-bromide] showed that cells cultured on charged phospholipids have greater viability than those cultured on the control, while cells cultured on neutral phospholipids showed lower viability.The cell cycle analysis using flow cytometry demonstrated that S phase entry increased on charged phospholipids, while S phase entry decreased on neutral phospholipids.The results suggested that charged phospholipids, especially positively charged phospholipids, show better cytocompatibilities than neutral phospholipids to hepatic Bel-7402 cell.

  5. Development of exosome surface display technology in living human cells

    Energy Technology Data Exchange (ETDEWEB)

    Stickney, Zachary, E-mail: zstickney@scu.edu; Losacco, Joseph, E-mail: jlosacco@scu.edu; McDevitt, Sophie, E-mail: smmcdevitt@scu.edu; Zhang, Zhiwen, E-mail: zzhang@scu.edu; Lu, Biao, E-mail: blu2@scu.edu

    2016-03-25

    Surface display technology is an emerging key player in presenting functional proteins for targeted drug delivery and therapy. Although a number of technologies exist, a desirable mammalian surface display system is lacking. Exosomes are extracellular vesicles that facilitate cell–cell communication and can be engineered as nano-shuttles for cell-specific delivery. In this study, we report the development of a novel exosome surface display technology by exploiting mammalian cell secreted nano-vesicles and their trans-membrane protein tetraspanins. By constructing a set of fluorescent reporters for both the inner and outer surface display on exosomes at two selected sites of tetraspanins, we demonstrated the successful exosomal display via gene transfection and monitoring fluorescence in vivo. We subsequently validated our system by demonstrating the expected intracellular partitioning of reporter protein into sub-cellular compartments and secretion of exosomes from human HEK293 cells. Lastly, we established the stable engineered cells to harness the ability of this robust system for continuous production, secretion, and uptake of displayed exosomes with minimal impact on human cell biology. In sum, our work paved the way for potential applications of exosome, including exosome tracking and imaging, targeted drug delivery, as well as exosome-mediated vaccine and therapy.

  6. Synthesis of aluminium nanoparticles by arc evaporation of an aluminium cathode surface

    Indian Academy of Sciences (India)

    M Gazanfari; M Karimzadeh; S Ghorbani; M R Sadeghi; G Azizi; H Karimi; N Fattahi; Z Karimzadeh

    2014-06-01

    Aluminium nanoparticles (Al Nps) are synthesized using arc discharge method by applying direct current between aluminium electrodes in liquid environment without any use of vacuum equipment, heat exchangers, high temperatures furnaces and inert gases. After synthesis of Al Nps, in situ coating process on the nanoparticles was performed immediately. The effects of media on the yield and morphology of aluminium nanoparticles were investigated. Analysis result of the samples indicated that particle size was less than 30 nm, when 120 A/cm2 arc current was used. In addition, coating agent can affect arc velocity, arc stability, morphology and composition of the nanoparticles. Resultant nanoparticles were identified using X-ray powder diffraction (XRD), also their surface morphology was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and finally the accuracy of coating was assessed with infrared (IR) spectroscopy.

  7. Synthesis of gold nanoflowers using deep eutectic solvent with high surface enhanced Raman scattering properties

    Science.gov (United States)

    Aghakhani Mahyari, Farzaneh; Tohidi, Maryam; Safavi, Afsaneh

    2016-09-01

    A facile, seed-less and one-pot method was developed for synthesis of gold nanoflowers with multiple tips through reduction of HAuCl4 with deep eutectic solvent at room temperature. This solvent is eco-friendly, low-cost, non-toxic and biodegradable and can act as both reducing and shape-controlling agent. In this protocol, highly branched and stable gold nanoflowers were obtained without using any capping agent. The obtained products were characterized by different techniques including, field emission scanning electron microscopy, transmission electron microscopy, x-ray diffraction and UV-vis spectroscopy. The as-prepared gold nanoflowers exhibit efficient surface-enhanced Raman scattering (SERS) properties which can be used as excellent substrates for SERS.

  8. Synthesis and surface plasmonic properties of ultra-thick silver nanowires.

    Science.gov (United States)

    Hua, Jiaojiao; Wu, Fan; Fan, Fengru; Wang, Wenhui; Xu, Zhongfeng; Li, Fuli

    2016-06-29

    Metallic nanowires (NWs) possess significant potential for applications in integrated photonic and electronic devices at the nanoscale. Considering the manipulation of NWs and energy loss associated with surface plasmon polaritons (SPPs) modes which serve as signal carriers in the nanophotonic devices, NWs with large diameters are significant. In this work, we report a successive multi-step polyol process approach for the synthesis of ultra-thick silver nanowires (Ag NWs) and investigate their energy loss. Thin Ag NWs prepared in the first step are used as seeds for the further growth of thick Ag NWs in the subsequent steps, where Ag NWs with diameter as large as 1820 nm have been prepared. We further investigate the SPP propagation properties of these thick Ag NWs, and find that energy loss is decreased in Ag NWs with improved diameter. Our experimental results are important for the design and fabrication of SPP-based nanophotonic components and circuits.

  9. SnSe Nanocrystals: Synthesis, Structure, Optical Properties, and Surface Chemistry

    KAUST Repository

    Baumgardner, William J.

    2010-07-21

    The colloidal synthesis of SnSe nanoparticles is accomplished through the injection of bis[bis(trimethylsilyl)amino]tin(II) into hot trioctylphosphine: selenium in the presence of oleylamine. Through the manipulation of reaction temperature particles are grown with the average diameter reliably tuned to 4-10 nm. Quantum confinement is examined by establishing a relationship between particle size and band gap while the in depth growth dynamics are illuminated through UV-vis-NIR spectroscopy. Surface chemistry effects are explored, including the demonstration of useful ligand exchanges and the development of routes toward anisotropic particle growth. Finally, transient current-voltage properties of SnSe nanocrystal films in the dark and light are examined. © 2010 American Chemical Society.

  10. Synthesis of a New Optoelectronic Material Based on Oriented Adsorption of Dyes to Nanoparticles Surface

    Institute of Scientific and Technical Information of China (English)

    LI Gui-an; SONG Jian-ping; LI Xiu

    2005-01-01

    Synthesis of the optoelectronic storage material with structure for coating by nanosized metal and azo-dye was reported. The characterization of composites was made by using transmission electron microscope (TEM), ultraviolet-visible spectrometer (UV-Vis) and thermogravity analyzer (TGA). It is found that, due to the specific structure, in which azo-dye molecules are oriented and adsorbed on the spherical surface of nanosized metal, the absorption maximum of azo-dye methyl orange shift towards shorter wavelength band. The experimental results show that the proposed technique here would offer a promising way to synthesize short wavelength optoelectronic storage material by doping of metal nanoparticles coated with dyes in polymer. Furthermore, the composites based on the structure can present excellent thermal properties suitable for the requirements of optical storage. This new type of material is capable of matching semiconductor laser (GaN) in optoelectronic storage technology.

  11. Fungal surface protein mediated one-pot synthesis of stable and hemocompatible gold nanoparticles.

    Science.gov (United States)

    Kitching, Michael; Choudhary, Priyadarshani; Inguva, Saikumar; Guo, Yina; Ramani, Meghana; Das, Sujoy K; Marsili, Enrico

    2016-12-01

    Despite their large secretome and wide applications in bioprocesses, fungi remain underexplored in metal nanoparticles (MNP) biosynthesis. Previous studies have shown that cell surface proteins of Rhizopus oryzae play a crucial role in biomineralization of Au(III) to produce gold nanoparticles (AuNPs). Therefore, it is hypothesized that purified cell surface protein may produce in vitro AuNPs with narrow size distribution for biomedical and biocatalytic applications. However, different protein extraction methods might affect protein stability and the AuNP biosynthesis process. Herein, we have explored the extraction of cell surface proteins from R. oryzae using common detergents and reducing agent (sodium dodecyl sulfate (SDS) Triton X-100, and 1,4-dithiothreitol (DTT)) and their effect on the size and shape of the biosynthetic AuNPs. The surface proteins extracted with reducing agent (DTT) and non-ionic detergent (Triton X-100) produce spherical AuNPs with a mean particle size of 16±7nm, and 19±4nm, respectively, while the AuNPs produced by the surface protein extracted by ionic detergent (SDS) are flower-like AuNPs with broader size distribution of 43±19nm. This synthetic approach does not require use of any harsh chemicals, multistep preparation and separation process, favouring environmental sustainability. The biosynthetic AuNPs thus formed, are stable in different physiological buffers and hemocompatible, making them suitable for biomedical applications.

  12. Surface and catalytic properties of potassium-modified cobalt molybdenum catalysts for ammonia synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Moszynski, Dariusz, E-mail: dmoszynski@ps.pl [West Pomeranian University of Technology, Szczecin, Pulaskiego 10, 70-322 Szczecin (Poland); Jedrzejewski, Roman; Ziebro, Janusz; Arabczyk, Walerian [West Pomeranian University of Technology, Szczecin, Pulaskiego 10, 70-322 Szczecin (Poland)

    2010-06-15

    The influence of potassium addition on the structural, catalytic and surface properties of the cobalt molybdenum nitride was studied. The measurements of the catalytic activity and the specific surface area as well as the phase analysis with the use of X-ray diffraction were performed. The mixtures of Co{sub 3}Mo{sub 3}N and Co{sub 2}Mo{sub 3}N phases have been found to constitute the samples. The concentration ratio between the Co{sub 2}Mo{sub 3}N and Co{sub 3}Mo{sub 3}N phases is notably influenced by potassium admixture. The specific surface area of the catalysts changes also with the Co{sub 2}Mo{sub 3}N/Co{sub 3}Mo{sub 3}N ratio. The catalytic activity of the catalysts in the ammonia synthesis carried out at 400 deg. C and under the pressure of 10 MPa can be increased up to 2.4 times by the addition of potassium compounds. There is the optimal range of potassium concentration between 0.8 and 1.2 wt.%.

  13. Synthesis and Modification of Nanoparticles for Surface Nanostructuration of Polymeric Membranes

    KAUST Repository

    Prada, Iran David Charry

    2012-05-01

    The objectives of this work are (i) to prepare silver and TiO2 nanoparticles functionalized with polymers or alkoxysilanes as capping agents with specific control of morphology, size, and chemical reactivity and (ii) their attachment to the surface and pore wall of ultrafiltration membranes. These particles are interesting due to their known antibacterial, anti-biofouling efficiency, besides the photocatytic activity exhibited by TiO2. The first chapter focuses on the synthesis and characterization of silver nanoparticles. Their performance depends on the shape, size and other colloidal characteristics. A complete analysis of the effect of the stabilizer and pH conditions on particle size and shape was conducted by using polyethyleneimine and polyvinylpyrrolidone. Opposite trends and different morphologies were observed for both stabilizers. The second chapter describes the surface attachment of TiO2 nanoparticles onto polyetherimide ultrafiltration membrane with pore size around 134nm by using organoalkylsilanes. Excellent hydrophilicity (contact angle 39  2) and high and thermal stability (260oC) was achieved. Particles and membranes samples were characterized by microscopy, chemical and surface analysis.

  14. Product surface hardening in non-self-sustained glow discharge plasma before synthesis of superhard coatings

    Science.gov (United States)

    Krasnov, P. S.; Metel, A. S.; Nay, H. A.

    2017-05-01

    Before the synthesis of superhard coating, the product surface is hardened by means of plasma nitriding, which prevents the surface deformations and the coating brittle rupture. The product heating by ions accelerated from plasma by applied to the product bias voltage leads to overheating and blunting of the product sharp edges. To prevent the blunting, it is proposed to heat the products with a broad beam of fast nitrogen molecules. The beam injection into a working vacuum chamber results in filling of the chamber with quite homogeneous plasma suitable for nitriding. Immersion in the plasma of the electrode and heightening of its potential up to 50-100 V initiate a non-self-sustained glow discharge between the electrode and the chamber. It enhances the plasma density by an order of magnitude and reduces its spatial nonuniformity down to 5-10%. When a cutting tool is isolated from the chamber, it is bombarded by plasma ions with an energy corresponding to its floating potential, which is lower than the sputtering threshold. Hence, the sharp edges are sputtered only by fast nitrogen molecules with the same rate as other parts of the tool surface. This leads to sharpening of the cutting tools instead of blunting.

  15. Cytotoxicity of organic surface coating agents used for nanoparticles synthesis and stability.

    Science.gov (United States)

    Zhang, Ying; Newton, Brandon; Lewis, Eybriunna; Fu, Peter P; Kafoury, Ramzi; Ray, Paresh C; Yu, Hongtao

    2015-06-01

    Impact on health by nanomaterials has become a public concern with the great advances of nanomaterials for various applications. Surface coating agents are an integral part of nanoparticles, but not enough attention has been paid during toxicity tests of nanoparticles. As a result, there are inconsistent toxicity results for certain nanomaterials. In this study, we explored the cytotoxicity of eleven commonly used surface coating agents in two cell lines, human epidermal keratinocyte (HaCaT) and lung fibroblast (CRL-1490) cells, at surface coating agent concentrations of 3, 10, 30, and 100 μM. Two exposure time points, 2 h and 24 h, were employed for the study. Six of the eleven surface coating agents are cytotoxic, especially those surfactants with long aliphatic chains, both cationic (cetyltrimethylammonium bromide, oleylamine, tetraoctylammonium bromide, and hexadecylamine) and anionic (sodium dodecylsulfate). In addition, exposure time and the use of different cell lines also affect the cytotoxicity results. Therefore, factors such as cell lines used and exposure times must be considered when conducting toxicity tests or comparing cytotoxicity results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Synthesis and evaluation of some surface active agents from long chain fatty amine

    Directory of Open Access Journals (Sweden)

    Eissa, A. M. F.

    2007-12-01

    Full Text Available This study continues our series of synthesis of surface active agents containing heterocyclic moiety. NHeptadecanoyl- 3-(4-oxo-4H-benzo[d][1,3]oxazin-2-yl- acrylamide (4 was used as a new starting material to synthesize propenoxylated nonionic surface active agents having heterocycles such as (thiazole, triazole, benzoxazine, quinazoline, triazine, and oxazine. The structures of the prepared compounds were elucidated by using spectroscopic tools (IR, 1H NMR and Mass spectroscopy. Physical properties such as surface and interfacial tension, cloud point, foaming height, wetting time, emulsification power and critical micelle concentration (CMC were determined. Antimicrobial and biodegradability properties were also screened. It was found that the produced novel groups of nonionic surface active agents have pronounced surface properties and good antimicrobial activities.Este estudio continua nuestra serie sobre la síntesis de agentes surfactantes que contienen grupos heterociclicos. N-Heptadecanoyl-3-(4-oxo-4H-benzo[d][1,3]oxazin-2-yl- acrylamida (4 se usa como nueva materia prima para sintetizar surfactantes noiónico propenoxilado conteniendo herociclos tales como thiazol, triazol, benzoxazina, quinazolina, triazina, y oxazina. Las estructuras de los compuestos preparados se dilucidan mediante herramientas espectroscópicas (IR, 1H NMR and espectroscopía de masas. Se determinan sus propiedades físicas, tensión superficial e interfacial, punto de nube, altura de espuma, poder de emulsificación y concentración micelar critica.También se revisan sus propiedades antimicrobianas y de biodegradabilidad Se encontró que los nuevos compuestos poseían destacadas propiedades superficiales y unas buenas actividades antimicrobianas.

  17. Cell surface engineering of microorganisms towards adsorption of heavy metals.

    Science.gov (United States)

    Li, Peng-Song; Tao, Hu-Chun

    2015-06-01

    Heavy metal contamination has become a worldwide environmental concern due to its toxicity, non-degradability and food-chain bioaccumulation. Conventional physical and chemical treatment methods for heavy metal removal have disadvantages such as cost-intensiveness, incomplete removal, secondary pollution and the lack of metal specificity. Microbial biomass-based biosorption is one of the approaches gaining increasing attention because it is effective, cheap, and environmental friendly and can work well at low concentrations. To enhance the adsorption properties of microbial cells to heavy metal ions, the cell surface display of various metal-binding proteins/peptides have been performed using a cell surface engineering approach. The surface engineering of Gram-negative bacteria, Gram-positive bacteria and yeast towards the adsorption of heavy metals are reviewed in this article. The problems and future perspectives of this technology are discussed.

  18. Surface Modification of Macroporous Matrix for Immobilization of Lipase for Fructose Oleic Ester Synthesis

    Directory of Open Access Journals (Sweden)

    Hani Hilmanto

    2016-10-01

    Full Text Available The objective of this research was to modify the matrix surfaces to obtain both hydrophobic matrix (HM and hydrophilic-hydrophobic matrix (HHM for enzymatic synthesis of fructose oleic ester (FOE. The modification was performed by the attachment of 2-phenylpropionaldehyde (PPA and PPA followed by polyethyleneimine (PEI for HM and HHM, respectively. The results from FT-IR analysis showed that the peak of stretching vibration of NH2 bond decreased and it was followed by an increase of the peak vibration of –C=N– bond at wave number 1667 cm-1. The peak of bending vibrations of the C=C bond also increased. It indicated that PPA was successfully attached on matrix. For HHM, an increase in the peak area of NH2 bond indicated that PEI was also successfully attached on the matrix. The optimum conditions of lipase adsorption were obtained at buffer pH 7 containing 0.5 M NaCl (9.27 mg protein/g matrix and without NaCl (9.23 mg protein/g matrix for HM and HHM, respectively. For FOE synthesis, the best immobilized lipase concentration was about 8% and 6% for HM and HHM, respectively. The optimum time of esterification was 24 h and 18 h for HM and HHM, respectively, in which the yields were 75.96% and 85.29%, respectively. The immobilized lipase could be used up to 3 cycles of esterification reaction. Copyright © 2016 BCREC GROUP. All rights reserved Received: 21st December 2015; Revised: 23rd February 2016; Accepted: 14th April 2016 How to Cite: Hilmanto, H., Hidayat, C., Hastuti, P. (2016. Surface Modification of Macroporous Matrix for Immobilization of Lipase for Fructose Oleic Ester Synthesis. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (3: 339-345 (doi:10.9767/bcrec.11.3.573.339-345 Permalink/DOI: http://doi.org/10.9767/bcrec.11.3.573.339-345

  19. Investigation of the Cell Surface Proteome of Human Periodontal Ligament Stem Cells

    Directory of Open Access Journals (Sweden)

    Jimin Xiong

    2016-01-01

    Full Text Available The present study examined the cell surface proteome of human periodontal ligament stem cells (PDLSC compared to human fibroblasts. Cell surface proteins were prelabelled with CyDye before processing to extract the membrane lysates, which were separated using 2D electrophoresis. Selected differentially expressed protein “spots” were identified using Mass spectrometry. Four proteins were selected for validation: CD73, CD90, Annexin A2, and sphingosine kinase 1 previously associated with mesenchymal stem cells. Flow cytometric analysis found that CD73 and CD90 were highly expressed by human PDLSC and gingival fibroblasts but not by keratinocytes, indicating that these antigens could be used as potential markers for distinguishing between mesenchymal cells and epithelial cell populations. Annexin A2 was also found to be expressed at low copy number on the cell surface of human PDLSC and gingival fibroblasts, while human keratinocytes lacked any cell surface expression of Annexin A2. In contrast, sphingosine kinase 1 expression was detected in all the cell types examined using immunocytochemical analysis. These proteomic studies form the foundation to further define the cell surface protein expression profile of PDLSC in order to better characterise this cell population and help develop novel strategies for the purification of this stem cell population.

  20. Inositol synthesis regulates the activation of GSK-3α in neuronal cells.

    Science.gov (United States)

    Ye, Cunqi; Greenberg, Miriam L

    2015-04-01

    The synthesis of inositol provides precursors of inositol lipids and inositol phosphates that are pivotal for cell signaling. Mood stabilizers lithium and valproic acid, used for treating bipolar disorder, cause cellular inositol depletion, which has been proposed as a therapeutic mechanism of action of both drugs. Despite the importance of inositol, the requirement for inositol synthesis in neuronal cells is not well understood. Here, we examined inositol effects on proliferation of SK-N-SH neuroblastoma cells. The essential role of inositol synthesis in proliferation is underscored by the findings that exogenous inositol was dispensable for proliferation, and inhibition of inositol synthesis decreased proliferation. Interestingly, the inhibition of inositol synthesis by knocking down INO1, which encodes inositol-3-phosphate synthase, the rate-limiting enzyme of inositol synthesis, led to the inactivation of GSK-3α by increasing the inhibitory phosphorylation of this kinase. Similarly, the mood stabilizer valproic acid effected transient decreases in intracellular inositol, leading to inactivation of GSK-3α. As GSK-3 inhibition has been proposed as a likely therapeutic mechanism of action, the finding that inhibition of inositol synthesis results in the inactivation of GSK-3α suggests a unifying hypothesis for mechanism of mood-stabilizing drugs. Inositol is an essential metabolite that serves as a precursor for inositol lipids and inositol phosphates. We report that inhibition of the rate-limiting enzyme of inositol synthesis leads to the inactivation of glycogen synthase kinase (GSK) 3α by increasing inhibitory phosphorylation of this kinase. These findings have implications for the therapeutic mechanisms of mood stabilizers and suggest that inositol synthesis and GSK 3α activity are intrinsically related.

  1. Synthesis, Surface Active Properties and Cytotoxicity of Sodium N-Acyl Prolines.

    Science.gov (United States)

    Sreenu, Madhumanchi; Narayana Prasad, Rachapudi Badari; Sujitha, Pombala; Kumar, Chityal Ganesh

    2015-01-01

    Sodium N-acyl prolines (NaNAPro) were synthesized using mixture of fatty acids obtained from coconut, palm, karanja, Sterculia foetida and high oleic sunflower oils via Schotten-Baumann reaction in 58-75% yields to study the synergetic effect of mixture of hydrophobic fatty acyl functionalities like saturation, unsaturation and cyclopropene fatty acids with different chain lengths and aliphatic hetero cyclic proline head group on their surface and cytotoxicity activities. The products were characterized by chromatographic and spectral techniques. The synthesized products were evaluated for their surface active properties such as surface tension, wetting power, foaming characteristics, emulsion stability, calcium tolerance, critical micelle concentration (CMC) and thermodynamic properties. The results revealed that all the products exhibited superior surface active properties like CMC, calcium tolerance and emulsion stability as compared to the standard surfactant, sodium lauryl sulphate (SLS). In addition, palm, Sterculia foetida and high oleic sunflower fatty N-acyl prolines exhibited promising cytotoxicity against different tumor cell lines.

  2. In vitro behaviour of endothelial cells on a titanium surface

    Directory of Open Access Journals (Sweden)

    Oliveira-Filho Ricardo

    2008-07-01

    Full Text Available Abstract Background Endothelial cells play an important role in the delivery of cells to the inflammation site, chemotaxis, cell adhesion and extravasation. Implantation of a foreign material into the human body determines inflammatory and repair reactions, involving different cell types with a plethora of released chemical mediators. The evaluation of the interaction of endothelial cells and implanted materials must take into account other parameters in addition to the analysis of maintenance of cell viability. Methods In the present investigation, we examined the behavior of human umbilical vein endothelial cells (HUVECs harvested on titanium (Ti, using histological and immunohistochemical methods. The cells, after two passages, were seeded in a standard density on commercially plate-shaped titanium pieces, and maintained for 1, 7 or 14 days. Results After 14 days, we could observe a confluent monolayer of endothelial cells (ECs on the titanium surface. Upon one-day Ti/cell contact the expression of fibronectin was predominantly cytoplasmatic and stronger than on the control surface. It was observed strong and uniform cell expression along the time of α5β1 integrin on the cells in contact with titanium. Conclusion The attachment of ECs on titanium was found to be related to cellular-derived fibronectin and the binding to its specific receptor, the α5β1 integrin. It was observed that titanium effectively serves as a suitable substrate for endothelial cell attachment, growth and proliferation. However, upon a 7-day contact with Ti, the Weibel-Palade bodies appeared to be not fully processed and exhibited an anomalous morphology, with corresponding alterations of PECAM-1 localization.

  3. Function of SREBP1 in the Milk Fat Synthesis of Dairy Cow Mammary Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Nan Li

    2014-09-01

    Full Text Available Sterol regulatory element-binding proteins (SREBPs belong to a family of nuclear transcription factors. The question of which is the most important positive regulator in milk fat synthesis in dairy cow mammary epithelial cells (DCMECs between SREBPs or other nuclear transcription factors, such as peroxisome proliferator-activated receptor γ (PPARγ, remains a controversial one. Recent studies have found that mTORC1 (the mammalian target of rapamycin C1 regulates SREBP1 to promote fat synthesis. Thus far, however, the interaction between the SREBP1 and mTOR (the mammalian target of rapamycin pathways in the regulation of milk fat synthesis remains poorly understood. This study aimed to identify the function of SREBP1 in milk fat synthesis and to characterize the relationship between SREBP1 and mTOR in DCMECs. The effects of SREBP1 overexpression and gene silencing on milk fat synthesis and the effects of stearic acid and serum on SREBP1 expression in the upregulation of milk fat synthesis were investigated in DCMECs using immunostaining, Western blotting, real-time quantitative PCR, lipid droplet staining, and detection kits for triglyceride content. SREBP1 was found to be a positive regulator of milk fat synthesis and was shown to be regulated by stearic acid and serum. These findings indicate that SREBP1 is the key positive regulator in milk fat synthesis.

  4. Fabrication of cell container arrays with overlaid surface topographies.

    Science.gov (United States)

    Truckenmüller, Roman; Giselbrecht, Stefan; Escalante-Marun, Maryana; Groenendijk, Max; Papenburg, Bernke; Rivron, Nicolas; Unadkat, Hemant; Saile, Volker; Subramaniam, Vinod; van den Berg, Albert; van Blitterswijk, Clemens; Wessling, Matthias; de Boer, Jan; Stamatialis, Dimitrios

    2012-02-01

    This paper presents cell culture substrates in the form of microcontainer arrays with overlaid surface topographies, and a technology for their fabrication. The new fabrication technology is based on microscale thermoforming of thin polymer films whose surfaces are topographically prepatterned on a micro- or nanoscale. For microthermoforming, we apply a new process on the basis of temporary back moulding of polymer films and use the novel concept of a perforated-sheet-like mould. Thermal micro- or nanoimprinting is applied for prepatterning. The novel cell container arrays are fabricated from polylactic acid (PLA) films. The thin-walled microcontainer structures have the shape of a spherical calotte merging into a hexagonal shape at their upper circumferential edges. In the arrays, the cell containers are arranged densely packed in honeycomb fashion. The inner surfaces of the highly curved container walls are provided with various topographical micro- and nanopatterns. For a first validation of the microcontainer arrays as in vitro cell culture substrates, C2C12 mouse premyoblasts are cultured in containers with microgrooved surfaces and shown to align along the grooves in the three-dimensional film substrates. In future stem-cell-biological and tissue engineering applications, microcontainers fabricated using the proposed technology may act as geometrically defined artificial microenvironments or niches.

  5. 3D surface topology guides stem cell adhesion and differentiation.

    Science.gov (United States)

    Viswanathan, Priyalakshmi; Ondeck, Matthew G; Chirasatitsin, Somyot; Ngamkham, Kamolchanok; Reilly, Gwendolen C; Engler, Adam J; Battaglia, Giuseppe

    2015-06-01

    Polymerized high internal phase emulsion (polyHIPE) foams are extremely versatile materials for investigating cell-substrate interactions in vitro. Foam morphologies can be controlled by polymerization conditions to result in either open or closed pore structures with different levels of connectivity, consequently enabling the comparison between 2D and 3D matrices using the same substrate with identical surface chemistry conditions. Additionally, here we achieve the control of pore surface topology (i.e. how different ligands are clustered together) using amphiphilic block copolymers as emulsion stabilizers. We demonstrate that adhesion of human mesenchymal progenitor (hES-MP) cells cultured on polyHIPE foams is dependent on foam surface topology and chemistry but is independent of porosity and interconnectivity. We also demonstrate that the interconnectivity, architecture and surface topology of the foams has an effect on the osteogenic differentiation potential of hES-MP cells. Together these data demonstrate that the adhesive heterogeneity of a 3D scaffold could regulate not only mesenchymal stem cell attachment but also cell behavior in the absence of soluble growth factors.

  6. Synthesis of Prostaglandins and Eicosanoids by the Mast Cell Secretory Granule

    Science.gov (United States)

    1988-01-01

    constituents of the so-called "slow reacting substance of anaphylaxis" (SRS-A) (1,3). Like many other cell types, the mast cell can incorporate exogenous...arachidonic acid into its cellular phospholipid. The stimulation of mast cells which have been pre-loaded with radioactive arachidonic acid can result in...synthesis of eicosanoids has not been identified. Recently, we found that the secretory granule of the quiescent mast cell contains a large amount of matrix

  7. Green synthesis of graphene and its cytotoxic effects in human breast cancer cells.

    Science.gov (United States)

    Gurunathan, Sangiliyandi; Han, Jae Woong; Eppakayala, Vasuki; Kim, Jin-Hoi

    2013-01-01

    This paper describes an environmentally friendly ("green") approach for the synthesis of soluble graphene using Bacillus marisflavi biomass as a reducing and stabilizing agent under mild conditions in aqueous solution. In addition, the study reported here investigated the cytotoxicity effects of graphene oxide (GO) and bacterially reduced graphene oxide (B-rGO) on the inhibition of cell viability, reactive oxygen species (ROS) generation, and membrane integrity in human breast cancer cells. The reduction of GO was characterized by ultraviolet-visible spectroscopy. Size distribution was analyzed by dynamic light scattering. Further, X-ray diffraction and high-resolution scanning electron microscopy were used to investigate the crystallinity of graphene and the morphologies of prepared graphene, respectively. The formation of defects further supports the bio-functionalization of graphene, as indicated in the Raman spectrum of B-rGO. Surface morphology and the thickness of the GO and B-rGO were analyzed using atomic force microscopy, while the biocompatibility of GO and B-rGO were investigated using WST-8 assays on MCF-7 cells. Finally, cellular toxicity was evaluated by ROS generation and membrane integrity assays. In this study, we demonstrated an environmentally friendly, cost-effective, and simple method for the preparation of water-soluble graphene using bacterial biomass. This reduction method avoids the use of toxic reagents such as hydrazine and hydrazine hydrate. The synthesized soluble graphene was confirmed using various analytical techniques. Our results suggest that both GO and B-rGO exhibit toxicity to MCF-7 cells in a dose-dependent manner, with a dose > 60 μg/mL exhibiting obvious cytotoxicity effects, such as decreasing cell viability, increasing ROS generation, and releasing of lactate dehydrogenase. We developed a green and a simple approach to produce graphene using bacterial biomass as a reducing and stabilizing agent. The proposed approach

  8. Cell-surface expression of Hsp70 on hematopoietic cancer cells after inhibition of HDAC activity

    DEFF Research Database (Denmark)

    Jensen, Helle; Andresen, Lars; Hansen, Karen Aagaard

    2009-01-01

    We show that inhibition of HDAC activity leads to surface expression of Hsp70 on various hematopoietic cancer cells, an occurance that was not observed on naïve or activated peripheral blood cells. HDAC inhibitor-mediated Hsp70 surface expression was confined to the apoptotic Annexin V...... activity selectively induces surface expression of Hsp70 on hematopoietic cancer cells and that this may increase immunorecognition of these cells.......-positive cells and blocked by inhibition of apoptosis. Other chemotherapeutic inducers of apoptosis such as etoposide and camptothecin also led to a robust induction of Hsp70 surface expression. Hsp70 expression was, however, not caused by induction of apoptosis per se, as activated CD4 T cells remained Hsp70...

  9. Host range restriction of vaccinia virus in Chinese hamster ovary cells: relationship to shutoff of protein synthesis.

    Science.gov (United States)

    Drillien, R; Spehner, D; Kirn, A

    1978-12-01

    Chinese hamster ovary cells were found to be nonpermissive for vaccinia virus. Although early virus-induced events occurred in these cells (RNA and polypeptide synthesis), subsequent events appeared to be prevented by a very rapid and nonselective shutoff of protein synthesis. Within less than 2 h after infection, both host and viral protein syntheses were arrested. At low multiplicities of infection, inhibition of RNA synthesis with cordycepin resulted in failure of the virus to block protein synthesis. Moreover, infection of the cells in the presence of cycloheximide prevented the immediate onset of shutoff after reversal of cycloheximide. Inactivation of virus particles by UV irradiation also impaired the capacity of the virus to inhibit protein synthesis. These results suggested that an early vaccinia virus-coded product was implicated in the shutoff of protein synthesis. Either the nonpermissive Chinese hamster ovary cells were more sensitive to this inhibition than permissive cells, or a regulatory control of the vaccinia shutoff function was defective.

  10. Application of a nonradioactive method of measuring protein synthesis in industrially relevant Chinese hamster ovary cells.

    Science.gov (United States)

    Dadehbeigi, Nazanin; Dickson, Alan James

    2013-01-01

    Due to the high medical and commercial value of recombinant proteins for clinical and diagnostic purposes, the protein synthesis machinery of mammalian host cells is the subject of extensive research by the biopharmaceutical industry. RNA translation and protein synthesis are steps that may determine the extent of growth and productivity of host cells. To address the problems of utilization of current radioisotope methods with proprietary media, we have focused on the application of an alternative method of measuring protein synthesis in recombinant Chinese hamster ovary (CHO) cells. This method employs puromycin as a nonradioactive label which incorporates into nascent polypeptide chains and is detectable by western blotting. This method, which is referred to as SUnSET, successfully demonstrated the expected changes in protein synthesis in conditions that inhibit and restore translation activity and was reproducibly quantifiable. The study of the effects of feed and sodium butyrate addition on protein synthesis by SUnSET revealed an increase following 1 h feed supplementation while a high concentration of sodium butyrate was able to decrease translation during the same treatment period. Finally, SUnSET was used to compare protein synthesis activity during batch culture of the CHO cell line in relation to growth. The results indicate that as the cells approached the end of batch culture, the global rate of protein synthesis declined in parallel with the decreasing growth rate. In conclusion, this method can be used as a "snapshot" to directly monitor the effects of different culture conditions and treatments on translation in recombinant host cells.

  11. High-throughput synthesis of stable isotope-labeled transmembrane proteins for targeted transmembrane proteomics using a wheat germ cell-free protein synthesis system.

    Science.gov (United States)

    Takemori, Nobuaki; Takemori, Ayako; Matsuoka, Kazuhiro; Morishita, Ryo; Matsushita, Natsuki; Aoshima, Masato; Takeda, Hiroyuki; Sawasaki, Tatsuya; Endo, Yaeta; Higashiyama, Shigeki

    2015-02-01

    Using a wheat germ cell-free protein synthesis system, we developed a high-throughput method for the synthesis of stable isotope-labeled full-length transmembrane proteins as proteoliposomes to mimic the in vivo environment, and we successfully constructed an internal standard library for targeted transmembrane proteomics by using mass spectrometry.

  12. Ultrastructural and metabolic transformations of differentiating Hyacinthus orientalis L, pollen grain cells. I. RNA and protein synthesis

    Directory of Open Access Journals (Sweden)

    Elżbieta Bednarska

    2014-01-01

    Full Text Available RNA and protein synthesis were investigated in generative and vegetative cells during maturation of pollen grains. The rate of RNA and protein synthesis was analysed in reference to the successive interphase periods of the life cycle of pollen cells as well as against the background of the growth dynamics of the cell volume. The results of studies demonstrated that the pollen grain increases in size owing to the growth of the vegetative cell. The generative one does not grow. RNA synthesis and that of proteins in differentiating pollen cells has a different course. In the growing vegetative cell it lasts longer and is more intensive than in the generative cell which does not grow. RNA and protein synthesis in the vegetative cell take place in the period from the callose stage to the stage of lemon-shaped generative cell, that is in the period of phases G1, S and G2. This synthesis is positively correlated with the growth of the pollen grain. RNA and protein synthesis in the generative cell comprises the period from the callose-less lenticular stage to the stage of spherical generative cell, that is the phases S and early phase G2. These results suggest that in the vegetative cell RNA and protein synthesis is utilised above all to increase of its cell, instead in non growing generative cell protein synthese is probably limited mostly to a histones and enzymatic proteins serving for the DNA replication process.

  13. Biogenic nanoparticulate UO 2: Synthesis, characterization, and factors affecting surface reactivity

    Science.gov (United States)

    Singer, David M.; Farges, François; Brown, Gordon E., Jr.

    2009-06-01

    The surface reactivity of biogenic, nanoparticulate UO 2 with respect to sorption of aqueous Zn(II) and particle annealing is different from that of bulk uraninite because of the presence of surface-associated organic matter on the biogenic UO 2. Synthesis of biogenic UO 2 was accomplished by reduction of aqueous uranyl ions, UO22+ by Shewanella putrefaciens CN32, and the resulting nanoparticles were washed using one of two protocols: (1) to remove surface-associated organic matter and soluble uranyl species (NAUO2), or (2) to remove only soluble uranyl species (BIUO2). A suite of bulk and surface characterization techniques was used to examine bulk and biogenic, nanoparticulate UO 2 as a function of particle size and surface-associated organic matter. The N 2-BET surface areas of the two biogenic UO 2 samples following the washing procedures are 128.63 m 2 g -1 (NAUO2) and 92.56 m 2 g -1 (BIUO2), and the average particle sizes range from 5-10 nm based on TEM imaging. Electrophoretic mobility measurements indicate that the surface charge behavior of biogenic, nanoparticulate UO 2 (both NAUO2 and BIUO2) over the pH range 3-9 is the same as that of bulk. The U L III-edge EXAFS spectra for biogenic UO 2 (both NAUO2 and BIUO2) were best fit with half the number of second-shell uranium neighbors compared to bulk uraninite, and no oxygen neighbors were detected beyond the first shell around U(IV) in the biogenic UO 2. At pH 7, sorption of Zn(II) onto both bulk uraninite and biogenic, nanoparticulate UO 2 is independent of electrolyte concentration, suggesting that Zn(II) sorption complexes are dominantly inner-sphere. The maximum surface area-normalized Zn(II) sorption loadings for the three substrates were 3.00 ± 0.20 μmol m -2 UO 2 (bulk uraninite), 2.34 ± 0.12 μmol m -2 UO 2 (NAUO2), and 2.57 ± 0.10 μmol m -2 UO 2 (BIUO2). Fits of Zn K-edge EXAFS spectra for biogenic, nanoparticulate UO 2 indicate that Zn(II) sorption is dependent on the washing protocol. Zn

  14. Combinatorial synthesis with high throughput discovery of protein-resistant membrane surfaces.

    Science.gov (United States)

    Gu, Minghao; Vegas, Arturo J; Anderson, Daniel G; Langer, Robert S; Kilduff, James E; Belfort, Georges

    2013-08-01

    Using combinatorial methods, we synthesized a series of new vinyl amide monomers and graft-polymerized them to light-sensitive poly(ether sulfone) (PES) porous films for protein resistance. To increase the discovery rate and statistical confidence, we developed high throughput surface modification methods (HTP) that allow synthesis, screening and selection of desirable monomers from a large library in a relatively short time (days). A series of amide monomers were synthesized by amidation of methacryloyl chloride with amines and grafted onto commercial poly(ether sulfone) (PES) membranes using irradiation from atmospheric pressure plasma (APP). The modified PES membrane surfaces were then tested and screened for static protein adhesion using HTP. Hydroxyl amide monomers N-(3-hydroxypropyl)methacrylamide (A3), N-(4-hydroxybutyl)methacrylamide (A4), and N-(4-hydroxybutyl)methacrylamide (A6), ethylene glycol (EG) monomer N-(3-methoxypropyl)methacrylamide (A7), and N-(2-(dimethylamino)ethyl)-N-methylmethacrylamide (A8), and N-(2-(diethylamino)ethyl)-N-methylmethacrylamide (A9) all terminated with tertiary amines and were shown to have protein resistance. The PES membranes modified with these monomers exhibited both low protein adhesion (i.e. membrane plugging or fouling) and high flux. Their performance is comparable with previously identified best performing PEG and zwitterionic monomers, i.e. the so-called gold-standard for protein resistance. Combining a Hansen solubility parameter (HSP) analysis of the amide monomers and the HTP filtration results, we conclude that monomer solubility in water correlates with protein-resistant surfaces, presumably through its effects on surface-water interactions.

  15. Monoclonal antibody to human endothelial cell surface internalization and liposome delivery in cell culture.

    Science.gov (United States)

    Trubetskaya, O V; Trubetskoy, V S; Domogatsky, S P; Rudin, A V; Popov, N V; Danilov, S M; Nikolayeva, M N; Klibanov, A L; Torchilin, V P

    1988-02-01

    A monoclonal antibody (mAb), E25, is described that binds to the surface of cultured human endothelial cells. Upon binding E25 is rapidly internalized and digested intracellularly. Selective liposome targeting to the surface of the cells is performed using a biotinylated E25 antibody and an avidin-biotin system. Up to 30% of the cell-adherent liposomal lipid is internalized.

  16. Stress-induced cell death is mediated by ceramide synthesis in Neurospora crassa

    DEFF Research Database (Denmark)

    Plesofsky, Nora S; Levery, Steven B; Castle, Sherry A

    2008-01-01

    The combined stresses of moderate heat shock (45 degrees C) and analog-induced glucose deprivation constitute a lethal stress for Neurospora crassa. We found that this cell death requires fatty acid synthesis and the cofactor biotin. In the absence of the cofactor, the stressed cells are particul...

  17. Enhanced in vivo protein synthesis in circulating immune cells of ICU patients.

    Science.gov (United States)

    Januszkiewicz, Anna; Klaude, Maria; Loré, Karin; Andersson, Jan; Ringdén, Olle; Rooyackers, Olav; Wernerman, Jan

    2007-11-01

    Insufficient function of the immune system contributes to a poor prognosis in intensive care unit (ICU) patients. However, the immune system function is not easily monitored and evaluated. In vivo protein synthesis determination in immune competent cells offers a possibility to quantify immunological activation. The aim of this descriptive study was to determine the in vivo fractional protein synthesis rate (FSR) in immune cells of ICU patients during the initial phase of the critical illness. Patients (n = 20) on ventilator treatment in the general ICU were studied during their first week of ICU stay. FSR was determined in circulating T lymphocytes, mononuclear cells, the whole population of blood leukocytes, and in stationary immune cells of palatine tonsils during a 90-min period by a flooding technique. Healthy, adult subjects (n = 11), scheduled for elective ear, nose, and throat surgery served as a control group. The FSR in leukocytes and mononuclear cells of ICU patients was higher compared with the control group. In contrast, the FSR of circulating T lymphocytes and of tonsillar cells was not different from that in the healthy subjects. In summary, the ICU patients showed a distinct polarization of metabolic responses during the initial phase of the critical illness. The in vivo rate of protein synthesis was high in the circulating mononuclear cells and leukocytes, reflecting enhanced metabolic activity in these cell populations. Determination of the in vivo protein synthesis rate may be used as a tool to obtain additional information on activation of the immune system.

  18. Labelling of Cells Engaged in DNA Synthesis: Autoradiography and BrdU Staining

    DEFF Research Database (Denmark)

    Madsen, Peder Søndergaard

    2010-01-01

    The cell cycle is divided in four phases: G1 phase, S phase (DNA-synthesis), G2 phase (together termed interphase) and M phase (mitosis). Cells that have ceased proliferation enter a state of quiescence called G0. M phase is itself composed of two tightly coupled processes: mitosis, in which...

  19. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells

    Science.gov (United States)

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2...

  20. Surface-enhanced Raman spectroscopy of the endothelial cell membrane.

    Directory of Open Access Journals (Sweden)

    Simon W Fogarty

    Full Text Available We applied surface-enhanced Raman spectroscopy (SERS to cationic gold-labeled endothelial cells to derive SERS-enhanced spectra of the bimolecular makeup of the plasma membrane. A two-step protocol with cationic charged gold nanoparticles followed by silver-intensification to generate silver nanoparticles on the cell surface was employed. This protocol of post-labelling silver-intensification facilitates the collection of SERS-enhanced spectra from the cell membrane without contribution from conjugated antibodies or other molecules. This approach generated a 100-fold SERS-enhancement of the spectral signal. The SERS spectra exhibited many vibrational peaks that can be assigned to components of the cell membrane. We were able to carry out spectral mapping using some of the enhanced wavenumbers. Significantly, the spectral maps suggest the distribution of some membrane components are was not evenly distributed over the cells plasma membrane. These results provide some possible evidence for the existence of lipid rafts in the plasma membrane and show that SERS has great potential for the study and characterization of cell surfaces.

  1. Engineered Aptamers to Probe Molecular Interactions on the Cell Surface.

    Science.gov (United States)

    Batool, Sana; Bhandari, Sanam; George, Shanell; Okeoma, Precious; Van, Nabeela; Zümrüt, Hazan E; Mallikaratchy, Prabodhika

    2017-08-29

    Significant progress has been made in understanding the nature of molecular interactions on the cell membrane. To decipher such interactions, molecular scaffolds can be engineered as a tool to modulate these events as they occur on the cell membrane. To guarantee reliability, scaffolds that function as modulators of cell membrane events must be coupled to a targeting moiety with superior chemical versatility. In this regard, nucleic acid aptamers are a suitable class of targeting moieties. Aptamers are inherently chemical in nature, allowing extensive site-specific chemical modification to engineer sensing molecules. Aptamers can be easily selected using a simple laboratory-based in vitro evolution method enabling the design and development of aptamer-based functional molecular scaffolds against wide range of cell surface molecules. This article reviews the application of aptamers as monitors and modulators of molecular interactions on the mammalian cell surface with the aim of increasing our understanding of cell-surface receptor response to external stimuli. The information gained from these types of studies could eventually prove useful in engineering improved medical diagnostics and therapeutics.

  2. Studies of cell-surface glorin receptors, glorin degradation, and glorin-induced cellular responses during development of Polysphondylium violaceum.

    Science.gov (United States)

    De Wit, R J; van Bemmelen, M X; Penning, L C; Pinas, J E; Calandra, T D; Bonner, J T

    1988-12-01

    The chemoattractant mediating cell aggregation in the slime mold Polysphondylium violaceum is N-propionyl-gamma-L-glutamyl-L-ornithine-delta-lactam ethylester (glorin). Here we examine the binding properties of tritiated glorin to intact P. violaceum cells. Scatchard analysis of binding data yielded slightly curvilinear plots with Kd values in the range of 20 and 100 nM. The number of glorin receptors increased from 35,000 in the vegetative stage to 45,000 per cell during aggregation. Later, during culmination receptor numbers decreased to undetectable levels (less than 1000). The receptor binding kinetics show binding equilibrium within 30 s at 0 degrees C, and ligand dissociation occurs from two kinetically distinct receptors whose half-times were 2 s for 72% of the bound glorin and 28 s for the remainder. The enzymatic degradation of glorin did not affect binding data during incubations of up to 1 min at 0 degrees C. Two glorinase activities were observed. An ornithine delta-lactam cleaving activity with a Km of ca. 10(-4) M and a propionic acid removing activity (Km 10(-5) M), both of which were detected mainly on the cell surface. Cleavage of the lactam occurred at a higher rate than removal of propionic acid. Lactam-cleaved glorin showed no chemotactic activity nor did it bind to cell-surface glorin receptors. Cell-surface-bound glorinase activity and glorin-induced cGMP synthesis were developmentally regulated, peaking at aggregation. In the most sensitive stage half-maximal responses (cGMP synthesis, chemotaxis, light-scattering) were elicited in the 10-100 nM range. Neither cAMP synthesis nor glorin-induced glorin synthesis was observed. Guanine nucleotides specifically modulated glorin receptor binding on isolated membranes, and, conversely, glorin modulated GTP gamma S binding to membrane preparations. Our results support the notion that glorin mediates chemotactic cell aggregation in P. violaceum acting via cell-surface receptors, G-proteins, and c

  3. Preparation of ubiquitin-conjugated proteins using an insect cell-free protein synthesis system.

    Science.gov (United States)

    Suzuki, Takashi; Ezure, Toru; Ando, Eiji; Nishimura, Osamu; Utsumi, Toshihiko; Tsunasawa, Susumu

    2010-01-01

    Ubiquitination is one of the most significant posttranslational modifications (PTMs). To evaluate the ability of an insect cell-free protein synthesis system to carry out ubiquitin (Ub) conjugation to in vitro translated proteins, poly-Ub chain formation was studied in an insect cell-free protein synthesis system. Poly-Ub was generated in the presence of Ub aldehyde (UA), a de-ubiquitinating enzyme inhibitor. In vitro ubiquitination of the p53 tumor suppressor protein was also analyzed, and p53 was poly-ubiquitinated when Ub, UA, and Mdm2, an E3 Ub ligase (E3) for p53, were added to the in vitro reaction mixture. These results suggest that the insect cell-free protein synthesis system contains enzymatic activities capable of carrying out ubiquitination. CBB-detectable ubiquitinated p53 was easily purified from the insect cell-free protein synthesis system, allowing analysis of the Ub-conjugated proteins by mass spectrometry (MS). Lys 305 of p53 was identified as one of the Ub acceptor sites using this strategy. Thus, we conclude that the insect cell-free protein synthesis system is a powerful tool for studying various PTMs of eukaryotic proteins including ubiqutination presented here.

  4. Synthesis of POP3HT/lead sulfide nanocomposites for hybrid solar cell

    Science.gov (United States)

    Zhou, Miaoxin

    2007-12-01

    The recent discovery of high efficiency multiexciton generation in lead sulfide (PbS) and lead selenide (PbSe) nanocrystals makes them promising materials for high efficiency solar cells. One complication of extracting charges from the nanocrystals is the insulating ligands capping their surfaces. In this dissertation, we have successfully developed and characterized a phosphonate functionalized poly-3-hexylthiophene (POP3HT-50) and used it in the direct synthesis of PbS nanocrystals without the aid of extraneous ligands. These POP3HT/PbS nanocomposites were characterized by HR-TEM, TM-AFM, 1H NMR and absorption spectroscopy. The nanocomposites were also incorporated into solar cell devices and tested under AM 1.5G conditions. Devices made of POP3HT-50/PbS nanocomposites show an order of magnitude improvement in photocurrent and power conversion efficiency (eta) when compared to that reported for a P3HT/PbS device (eta = 0.011% vs. 0.001%). The improved photocurrent is consistent with improved contact between PbS nanocrystals and POP3HT-50, presumably leading to more efficient charge transfer. However, the overall efficiencies of such devices were still very low suggesting that further modification was needed. Future research could be focused on developing functional conductive polymer with lower ionization potential (Ip) for proper band alignment with these infrared nanocrystals, and on developing elongated nanocrystals with proper aspect ratio to reduce the rate of Auger recombination (decay process of multiexciton state).

  5. Synthesis of Novel Arylazothiazolyl-thiophene Dyes for Solar Cell and Nonlinear Optical Materials.

    Science.gov (United States)

    Khalifa, Mohamed E; Al-Amoudi, Muhammed S; Gobouri, Adil A; Merazga, Amar; Fadda, Ahmed A

    2016-01-01

    Synthesis and investigation of new donor-acceptor conjugated N-(5-arylazothiazol-2-yl)-2-aminothiophene derivatives with the aim to elucidate the contribution of their interaction with solvent molecules upon intramolecular charge transfer for their potential solar cells application. The UV-visible and emission spectra measurements indicated that the properties of the synthesized dyes had a significant effect on the visible absorption and emission maxima. The effect of the donor and acceptor groups were studied for the nonlinearity based on their HOMO-LUMO band gap energy. The dye-sensitized solar cells (DSSCs) were assembled by using the newly synthesized aryl thiazolyl-thiophene dyes as sensitizers. The promising results of J(SC) (2.46 × 10(-2) and 4.07 × 10(-2) mA/cm(2)), the V(OC) (0.429 V and 0.426 V) and the FF (0.66 %) values obtained comparing with other organic and natural sensitizer were due to the better interaction between the carboxyl and carbonyl groups of aryl azo molecule attached to the thiazolyl nucleus and the surface of TiO(2) porous film.

  6. Cell surface activation of progelatinase A (proMMP—2) and cell migration

    Institute of Scientific and Technical Information of China (English)

    NAGASEHIDEAKI

    1998-01-01

    Gelatinase A (MMP-2) is considered to play a critical role in cell migration and invasion.The proteinase is cerceted from the cell as an inactive zymogen.In vivo it is postulated that activation of progelationase A (proMMP-2) takes place on the cell surface mediated by membrane-type matrix metalloproteinases (MT-MMPs).Recent studies have demonstrated that proMMP-2 is recruited to the cell surface by interacting with tissue inhibitor of metalloproteinases-2 (TIMP-2) bound to MT1-MMP by forming a ternary complex.Free MT1-MMP closely located to the ternary complex then activates proMMP-2 on the cell surface.MT1-MMP is found in cultured invasive cancer cells at the invadopodia.The MT-MMP/TIMP-2/MMP-2 system thus provides localized expression of proteolysis of the extracellular matrix required for cell migration.

  7. Facile synthesis of Cu2S nanoarchitectures in application of surface enhanced Raman scattering

    Science.gov (United States)

    Fu, Shih-Yu; Chang, Hao-Hsuan; Hsu, Yu-Kuei; Lin, Yan-Gu

    2014-09-01

    Surface plasmon resonance (SPR) is one of the main mechanisms of Surface Raman Enhance Scattering (SERS) and it will depend on the morphology and free carrier density of substrates, in many of discussions have been proved. Recently, the semiconductor copper(I) sulphide (Cu2S), the natural p-type semiconductor, exhibits remarkable SPR in the nearinfrared region[1] and can be regards as best candidate for active SERS substrates. In this report, the successive ionic layer adsorption and reaction (SILAR) process will be used to synthesis Cu2S nanostructures[2] from ZnO nanorods as template deposited by electrochemical reaction. To further manipulate the different carrier densities of Cu2S nanostructuress, the adjustment of Cu vacancy in Cu2S can be accomplished by thermal processes under noble gas. Taking 4-aminothiophenol (4-ATP) as probe molecule to measure the SERS performance by Cu2S nanostructures made in this fabrication and also examines the effect on SERS by adjusting Cu vacancy under an excited wavelength of 632.8 nm and light power of 15 mW. In fact, the modulation of Cu vacancy will positively correlate to the SPR frequencies and so could get the best enhancement factor under the limited condition of excited source. Therefore, our results could provide a new opportunity to use SERS to explore the molecule-semiconductor interaction, a fundamental but essential question for designing novel devices.

  8. Synthesis of positively and negatively charged silver nanoparticles and their deposition on the surface of titanium

    Science.gov (United States)

    Sharonova, A.; Loza, K.; Surmeneva, M.; Surmenev, R.; Prymak, O.; Epple, M.

    2016-02-01

    Bacterial infections related to dental implants are currently a significant complication. A good way to overcome this challenge is functionalization of implant surface with Ag nanoparticles (NPs) as antibacterial agent. This article aims at review the synthesis routes, size and electrical properties of AgNPs. Polyvinyl pyrrolidone (PVP) and polyethyleneimine (PEI) were used as stabilizers. Dynamic Light Scattering, Nanoparticle Tracking Analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) have been used to characterize the prepared AgNPs. Two types of NPs were synthesized in aqueous solutions: PVP-stabilized NPs with a diameter of the metallic core of 70 ± 20 nm, and negative charge of -20 mV, PEI-stabilized NPs with the size of the metallic core of 50 ± 20 nm and positive charge of +55 mV. According to SEM results, all the NPs have a spherical shape. Functionalization of the titanium substrate surface with PVP and PEI-stabilized AgNPs was carried out by dropping method. XRD patterns revealed that the AgNPs are crystalline with the crystallite size of 14 nm.

  9. Direct chemical synthesis of MnO2 nanowhiskers on MXene surfaces for supercapacitor applications

    KAUST Repository

    Rakhi, Raghavan Baby

    2016-07-05

    Transition metal carbides (MXenes) are an emerging class of two dimensional (2D) materials with promising electrochemical energy storage performance. Herein, for the first time, by direct chemical synthesis, nanocrystalline ε-MnO2 whiskers were formed on MXene nanosheet surfaces (ε-MnO2/Ti2CTx and ε-MnO2/Ti3C2Tx) to make nanocomposite electrodes for aqueous pseudocapacitors. The ε-MnO2 nanowhiskers increase the surface area of the composite electrode and enhance the specific capacitance by nearly three orders of magnitude compared to pure MXene based symmetric supercapacitors. Combined with enhanced pseudocapacitance, the fabricated ε-MnO2/MXene supercapacitors exhibited excellent cycling stability with ~88% of the initial specific capacitance retained after 10000 cycles which is much higher than pure ε-MnO2 based supercapacitors (~74%). The proposed electrode structure capitalizes on the high specific capacitance of MnO2 and the ability of MXenes to improve conductivity and cycling stability.

  10. Lithography-free synthesis of nanostructured cobalt on Si (111) surfaces: structural and magnetic properties

    Science.gov (United States)

    Bounour-Bouzamouche, W.; Chérif, S. M.; Farhat, S.; Roussigné, Y.; Lungu, C. P.; Mazaleyrat, F.; Guerioune, M.

    2014-07-01

    We illustrate the concept of lithography-free synthesis and patterning of magnetic cobalt in the nanometric scale. Our elaboration method allows fabricating 2D architectures of cobalt and cobalt silicide onto silicon (111) surfaces. A continuous cobalt layer of 1, 3 and 10 nm thickness was first deposited by using thermoionic vacuum arc (TVA) technology and then, thermally annealed on vacuum at temperatures from 450° C to 800° C. Surface structure was analyzed by atomic force and field emission-scanning electron microscopies. Above 750° C, regular triangular shape cobalt nanostructures are formed with pattern dimensions varying between 10 and 200 nm. Good control of shape and packing density could be achieved by adjusting the initial thickness and the substrate temperature. Magnetic properties were investigated by means of vibrating sample magnetometer (VSM) technique. The evolution of the coercive field versus packing density and dimensions of the nanostructures was studied and compared to micromagnetic calculations. The observed nanostructures have been modelled by a series of shapes tending to a fractal curve.

  11. Synthesis of silica aerogel monoliths with controlled specific surface areas and pore sizes

    Science.gov (United States)

    Gao, Bingying; Lu, Shaoxiang; Kalulu, Mulenga; Oderinde, Olayinka; Ren, Lili

    2017-07-01

    To replace traditional preparation methods of silica aerogels, a small-molecule 1,2-epoxypropane (PO) has been introduced into the preparation process instead of using ammonia as the cross-linking agent, thus generating a lightweight, high porosity, and large surface area silica aerogel monolithic. We put forward a simple solution route for the chemical synthesis of silica aerogels, which was characterized by scanning electron microscopy (SEM), TEM, XRD, FTIR, thermogravimetric analysis (TGA) and the Brunauer-Emmett-Teller (BET) method In this paper, the effect of the amount of PO on the microstructure of silica aerogels is discussed. The BET surface areas and pore sizes of the resulting silica aerogels can be freely adjusted by changing the amount of PO, which will be helpful in promoting the development of silica aerogels to fabricate other porous materials with similar requirements. We also adopted a new organic solvent sublimation drying (OSSD) method to replace traditional expensive and dangerous drying methods such as critical point drying and freeze drying. This simple approach is easy to operate and has good repeatability, which will further facilitate actual applications of silica aerogels.

  12. Multijunction Solar Cells Optimized for the Mars Surface Solar Spectrum

    Science.gov (United States)

    Edmondson, Kenneth M.; Fetzer, Chris; Karam, Nasser H.; Stella, Paul; Mardesich, Nick; Mueller, Robert

    2007-01-01

    This paper gives an update on the performance of the Mars Exploration Rovers (MER) which have been continually performing for more than 3 years beyond their original 90-day missions. The paper also gives the latest results on the optimization of a multijunction solar cell that is optimized to give more power on the surface of Mars.

  13. Cell surface hydrophobicity is conveyed by S-layer proteins - A study in recombinant lactobacilli

    NARCIS (Netherlands)

    Mei, H.C. van der; Belt-Gritter, B. van de; Pouwels, P.H.; Martinez, B.; Busscher, H.J.

    2003-01-01

    Cell surface hydrophobicity is one of the most important factors controlling adhesion of microorganisms to surfaces. In this paper, cell surface properties of lactobacilli and recombinant lactobacilli with and without a surface layer protein (SLP) associated with cell surface hydrophobicity were det

  14. Cell surface hydrophobicity is conveyed by S-layer proteins - A study in recombinant lactobacilli

    NARCIS (Netherlands)

    Mei, H.C. van der; Belt-Gritter, B. van de; Pouwels, P.H.; Martinez, B.; Busscher, H.J.

    2003-01-01

    Cell surface hydrophobicity is one of the most important factors controlling adhesion of microorganisms to surfaces. In this paper, cell surface properties of lactobacilli and recombinant lactobacilli with and without a surface layer protein (SLP) associated with cell surface hydrophobicity were det

  15. Micromechanical and surface adhesive properties of single saccharomyces cerevisiae cells

    Science.gov (United States)

    Farzi, Bahman; Cetinkaya, Cetin

    2017-09-01

    The adhesion and mechanical properties of a biological cell (e.g. cell membrane elasticity and adhesiveness) are often strong indicators for the state of its health. Many existing techniques for determining mechanical properties of cells require direct physical contact with a single cell or a group of cells. Physical contact with the cell can trigger complex mechanotransduction mechanisms, leading to cellular responses, and consequently interfering with measurement accuracy. In the current work, based on ultrasonic excitation and interferometric (optical) motion detection, a non-contact method for characterizing the adhesion and mechanical properties of single cells is presented. It is experimentally demonstrated that the rocking (rigid body) motion and internal vibrational resonance frequencies of a single saccharomyces cerevisiae (SC) (baker’s yeast) cell can be acquired with the current approach, and the Young’s modulus and surface tension of the cell membrane as well as surface adhesion energy can be extracted from the values of these acquired resonance frequencies. The detected resonance frequency ranges for single SC cells include a rocking (rigid body) frequency of 330  ±  70 kHz and two breathing resonance frequencies of 1.53  ±  0.12 and 2.02  ±  0.31 MHz. Based on these values, the average work-of-adhesion of SC cells on a silicon substrate in aqueous medium is extracted, for the first time, as WASC-Si=16.2+/- 3.8 mJ {{m}-2} . Similarly, the surface tension and the Young’s modulus of the SC cell wall are predicted as {{σ }SC}=0.16+/- 0.02 N {{m}-1} and {{E}SC}= 9.20  ±  2.80 MPa, respectively. These results are compared to those reported in the literature by utilizing various methods, and good agreements are found. The current approach eliminates the measurement inaccuracies associated with the physical contact. Exciting and detecting cell dynamics at micro-second time-scales is significantly faster than the

  16. The role of alpha-synuclein in melanin synthesis in melanoma and dopaminergic neuronal cells.

    Directory of Open Access Journals (Sweden)

    Tianhong Pan

    Full Text Available The relatively high co-occurrence of Parkinson's disease (PD and melanoma has been established by a large number of epidemiological studies. However, a clear biological explanation for this finding is still lacking. Ultra-violet radiation (UVR-induced skin melanin synthesis is a defense mechanism against UVR-induced damage relevant to the initiation of melanoma, whereas, increased neuromelanin (NM, the melanin synthesized in dopaminergic neurons, may enhance the susceptibility to oxidative stress-induced neuronal injury relevant to PD. SNCA is a PD-causing gene coding for alpha-Synuclein (α-Syn that expresses not only in brain, but also in skin as well as in tumors, such as melanoma. The findings that α-Syn can interact with tyrosinase (TYR and inhibit tyrosine hydroxylase (TH, both of which are enzymes involved in the biosynthesis of melanin and dopamine (DA, led us to propose that α-Syn may participate in the regulation of melanin synthesis. In this study, by applying ultraviolet B (UVB light, a physiologically relevant stimulus of melanogenesis, we detected melanin synthesis in A375 and SK-MEL-28 melanoma cells and in SH-SY5Y and PC12 dopaminergic neuronal cells and determined effects of α-Syn on melanin synthesis. Our results showed that UVB light exposure increased melanin synthesis in all 4 cell lines. However, we found that α-Syn expression reduced UVB light-induced increase of melanin synthesis and that melanin content was lower when melanoma cells were expressed with α-Syn, indicating that α-Syn may have inhibitory effects on melanin synthesis in melanoma cells. Different from melanoma cells, the melanin content was higher in α-Syn-over-expressed dopaminergic neuronal SH-SY5Y and PC12 cells, cellular models of PD, than that in non-α-Syn-expressed control cells. We concluded that α-Syn could be one of the points responsible for the positive association between PD and melanoma via its differential roles in melanin synthesis in

  17. Regulation of T Cell Trafficking by Enzymatic Synthesis of O-Glycans

    Directory of Open Access Journals (Sweden)

    Samuel J. Hobbs

    2017-05-01

    Full Text Available Selectins constitute a family of oligosaccharide binding proteins that play critical roles in regulating the trafficking of leukocytes. In T cells, L-selectin (CD62L controls the capacity for naive and memory T cells to actively survey peripheral lymph nodes, whereas P- and E-selectin capture activated T cells on inflamed vascular endothelium to initiate extravasation into non-lymphoid tissues. The capacity for T cells to interact with all of these selectins is dependent on the enzymatic synthesis of complex O-glycans, and thus, this protein modification plays an indispensable role in regulating the distribution and homing of both naive and previously activated T cells in vivo. In contrast to neutrophils, O-glycan synthesis is highly dynamic in T cell populations and is largely controlled by extracellular stimuli such as antigen recognition or signaling though cytokine receptors. Herein, we review the basic principles of enzymatic synthesis of complex O-glycans, discuss tools and reagents for studying this type of protein modification and highlight our current understanding of how O-glycan synthesis is regulated and subsequently impacts the trafficking potential of diverse T cell populations.

  18. Association Mapping of Cell Wall Synthesis Regulatory Genes and Cell Wall Quality in Switchgrass

    Energy Technology Data Exchange (ETDEWEB)

    Bartley, Laura [Univ. of Oklahoma, Norman, OK (United States). Dept. of Microbiology and Plant Biology; Wu, Y. [Oklahoma State Univ., Stillwater, OK (United States); Zhu, L. [Oklahoma State Univ., Stillwater, OK (United States); Brummer, E. C. [Noble Foundation, Ardmore, OK (United States); Saha, M. [Noble Foundation, Ardmore, OK (United States)

    2016-05-31

    markers might be used to select switchgrass genotypes with improved composition in breeding programs for biofuel and forage production. Because the SSAC continues to be characterized by collaborators in the bioenergy community, the data generated will be used to identify additional markers in higher resolution genotyping data to approach identifying the genes and alleles that cause natural variation in switchgrass cell wall quality. For example, these markers can be surveyed in the 2100-member Oklahoma Southern and Northern Lowland switchgrass collections that this project also characterized. An orthogonal approach to biodiversity studies, using comparative functional genomics permits systematic querying of how much regulatory information is likely to be transferable from dicots to grasses and use of accumulated functional genomics resources for better-characterized grass species, such as rice, itself a biomass source in global agriculture and in certain regions. The project generated and tested a number of specific hypotheses regarding cell wall transcription factors and enzymes of grasses. To aid identification of cell wall regulators, the project assembled a novel, highdepth and -quality gene association network using a general linearized model scoring system to combine rice gene network data. Using known or putative orthologs of Arabidopsis cell wall biosynthesis genes and regulators, the project pulled from this network a cell wall sub-network that includes 96 transcription factors. Reverse genetics of a co-ortholog of the Arabidopsis MYB61 transcription factor in rice revealed that this regulatory node has evolved the ability to regulate grass-specific cell wall synthesis enzymes. A transcription factor with such activity has not been previously characterized to our knowledge, representing a major conclusion of this work. Changes in gene expression in a protoplast-based assay demonstrated positive or negative roles in cell wall regulation for eleven other

  19. Unleashing Cancer Cells on Surfaces Exposing Motogenic IGDQ Peptides.

    Science.gov (United States)

    Corvaglia, Valentina; Marega, Riccardo; De Leo, Federica; Michiels, Carine; Bonifazi, Davide

    2016-01-20

    Thiolated peptides bearing the Ile-Gly-Asp (IGD) motif, a highly conserved sequence of fibronectin, are used for the preparation of anisotropic self-assembled monolayers (SAM gradients) to study the whole-population migratory behavior of metastatic breast cancer cells (MDA-MB-231 cells). Ile-Gly-Asp-Gln-(IGDQ)-exposing SAMs sustain the adhesion of MDA-MB-231 cells by triggering focal adhesion kinase phosphorylation, similarly to the analogous Gly-Arg-Gly-Asp-(GRGD)-terminating surfaces. However, the biological responses of different cell lines interfaced with the SAM gradients show that only those exposing the IGDQ sequence induce significant migration of MDA-MB-231 cells. In particular, the observed migratory behavior suggests the presence of cell subpopulations associated with a "stationary" or a "migratory" phenotype, the latter determining a considerable cell migration at the sub-cm length scale. These findings are of great importance as they suggest for the first time an active role of biological surfaces exposing the IGD motif in the multicomponent orchestration of cellular signaling involved in the metastatic progression.

  20. Surface modification of hydrophobic polymers for improvement of endothelial cell-surface interactions

    NARCIS (Netherlands)

    Dekker, A.; Reitsma, K.; Beugeling, T.; Bantjes, A.; Feijen, J.; Kirkpatrick, C.J.; Aken, van W.G.

    1992-01-01

    The aim of this study is to improve the interaction of endothelial cells with polymers used in vascular prostheses. Polytetrafluoroethylene (PTFE; Teflon) films were treated by means of nitrogen and oxygen plasmas. Depending on the plasma exposure time, modified PTFE surfaces showed water-contact an

  1. Methods To Identify Aptamers against Cell Surface Biomarkers

    Directory of Open Access Journals (Sweden)

    Frédéric Ducongé

    2011-09-01

    Full Text Available Aptamers are nucleic acid-based ligands identified through a process of molecular evolution named SELEX (Systematic Evolution of Ligands by Exponential enrichment. During the last 10-15 years, numerous aptamers have been developed specifically against targets present on or associated with the surface of human cells or infectious pathogens such as viruses, bacteria, fungi or parasites. Several of the aptamers have been described as potent probes, rivalling antibodies, for use in flow cytometry or microscopy. Some have also been used as drugs by inhibiting or activating functions of their targets in a manner similar to neutralizing or agonistic antibodies. Additionally, it is straightforward to conjugate aptamers to other agents without losing their affinity and they have successfully been used in vitro and in vivo to deliver drugs, siRNA, nanoparticles or contrast agents to target cells. Hence, aptamers identified against cell surface biomarkers represent a promising class of ligands. This review presents the different strategies of SELEX that have been developed to identify aptamers for cell surface-associated proteins as well as some of the methods that are used to study their binding on living cells.

  2. Cell adhesion on Ti surface with controlled roughness

    Energy Technology Data Exchange (ETDEWEB)

    Burgos-Asperilla, L.; Garcia-Alonso, M. C.; Escudero, M. L.; Alonso, C.

    2015-07-01

    In this report, the in situ interaction between Saos-2 osteoblast cells and a smooth Ti surface was examined over time. The adhesion kinetics and mechanisms of cellular proliferation were monitored by quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). The rate of Saos-2 attachment on Ti surfaces, obtained from the measurements performed with the QCM, is a first-order reaction, with k=2.10{sup -}3 min{sup -}1. The impedance measurements indicate that in the absence of cells, the Ti resistance diminishes over time (7 days), due to the presence of amino acids and proteins from the culture medium that have been adsorbed, while in the presence of osteoblasts, this decrease is much greater because of the compounds generated by the cells that accelerate the dissolution of Ti. (Author)

  3. "Race for the Surface": Eukaryotic Cells Can Win.

    Science.gov (United States)

    Pham, Vy T H; Truong, Vi Khanh; Orlowska, Anna; Ghanaati, Shahram; Barbeck, Mike; Booms, Patrick; Fulcher, Alex J; Bhadra, Chris M; Buividas, Ričardas; Baulin, Vladimir; Kirkpatrick, C James; Doran, Pauline; Mainwaring, David E; Juodkazis, Saulius; Crawford, Russell J; Ivanova, Elena P

    2016-08-31

    With an aging population and the consequent increasing use of medical implants, managing the possible infections arising from implant surgery remains a global challenge. Here, we demonstrate for the first time that a precise nanotopology provides an effective intervention in bacterial cocolonization enabling the proliferation of eukaryotic cells on a substratum surface, preinfected by both live Gram-negative, Pseudomonas aeruginosa, and Gram-positive, Staphylococcus aureus, pathogenic bacteria. The topology of the model black silicon (bSi) substratum not only favors the proliferation of eukaryotic cells but is biocompatible, not triggering an inflammatory response in the host. The attachment behavior and development of filopodia when COS-7 fibroblast cells are placed in contact with the bSi surface are demonstrated in the dynamic study, which is based on the use of real-time sequential confocal imaging. Bactericidal nanotopology may enhance the prospect for further development of inherently responsive antibacterial nanomaterials for bionic applications such as prosthetics and implants.

  4. Surface manipulation of biomolecules for cell microarray applications.

    Science.gov (United States)

    Hook, Andrew L; Thissen, Helmut; Voelcker, Nicolas H

    2006-10-01

    Many biological events, such as cellular communication, antigen recognition, tissue repair and DNA linear transfer, are intimately associated with biomolecule interactions at the solid-liquid interface. To facilitate the study and use of these biological events for biodevice and biomaterial applications, a sound understanding of how biomolecules behave at interfaces and a concomitant ability to manipulate biomolecules spatially and temporally at surfaces is required. This is particularly true for cell microarray applications, where a range of biological processes must be duly controlled to maximize the efficiency and throughput of these devices. Of particular interest are transfected-cell microarrays (TCMs), which significantly widen the scope of microarray genomic analysis by enabling the high-throughput analysis of gene function within living cells. This article reviews this current research focus, discussing fundamental and applied research into the spatial and temporal surface manipulation of DNA, proteins and other biomolecules and the implications of this work for TCMs.

  5. Studies on bleomycin-induced repair DNA synthesis in permeable mouse ascites sarcoma cells.

    Directory of Open Access Journals (Sweden)

    Mori,Shigeru

    1989-04-01

    Full Text Available To study the mechanism of DNA excision repair, a DNA repair system employing permeable mouse sarcoma (SR-C3H/He cells was established and characterized. SR-C3H/He cells were permeabilized with a 0.0175% Triton X-100 solution. The permeable cells were treated with 1 mM ATP and 0.11 mM bleomycin, and then washed thoroughly to remove ATP and bleomycin. Repair DNA synthesis occurred in the bleomycin-damaged, permeable SR-C3H/He cells when incubated with ATP and four deoxyribonucleoside triphosphates. The repair nature of the DNA synthesis was confirmed by the BrdUMP density shift technique, and by the reduced sensitivity of the newly synthesized DNA to Escherichia coli exonuclease III. The DNA synthesis was optimally enhanced by addition of 0.08 M NaCl. Studies using selective inhibitors of DNA synthesis showed that aphidicolin-sensitive DNA polymerase (DNA polymerase alpha and/or delta and DNA polymerase beta were involved in the repair process. The present DNA repair system is thought to be useful to study nuclear DNA damage by bleomycin, removal of the damaged ends by an exonuclease, repair DNA synthesis by DNA polymerases and repair patch ligation by DNA ligase(s.

  6. Intrathecal IgG synthesis and autoantibody-secreting cells in multiple sclerosis

    DEFF Research Database (Denmark)

    Sellebjerg, Finn; Jensen, Claus V; Christiansen, Michael

    2000-01-01

    We studied intrathecal IgG synthesis and autoantibody-secreting cells in 148 patients with possible onset symptoms of MS (POSMS) or clinically definite MS (CDMS). In POSMS intrathecal synthesis of IgG oligoclonal bands and abnormalities on T2-weighted magnetic resonance imaging were associated...... but the former were more prevalent. The cerebrospinal fluid (CSF) leukocyte count and the number of anti-protelipid protein antibody-secreting cells in cerebrospinal fluid (CSF) correlated with disease activity in POSMS. Intrathecal IgG synthesis levels and the number of anti-myelin basic protein antibody......-secreting cells in CSF correlated with disease activity in CDMS. Our results support recent reports of pathogenetic heterogeneity and a pathogenetic role of the antibody response in MS...

  7. Synthesis and Characterization of a Novel Polyacetal & Design and Preparation of Superhydrophobic Photocatalytic Surfaces

    Science.gov (United States)

    Zhao, Yuanyuan

    Acetal copolymers represent a family of well-established engineering thermoplastics serving a broad range of important industrial applications including replacement for metals. The first part of this thesis describes the first synthesis of an eight-member ring acetal, 6-methyl-1, 3-dioxocane (MDOC), and its cationic copolymerization with trioxane initiated by boron trifluoride dibutyl etherate. The copolymerization process was monitored in situ using proton NMR. Incorporation of MDOC led to the insertion of the "stopper" unit, "--[CH2CH2CH(CH3)CH 2CH2)O]--", thus synthesizing the new acetal copolymer. A superior copolymer thermal stability with a ~ 20oC increase in degradation onset temperature compared with end-capped polyoxmethylene was observed. Both TGA and DSC data indicated the random placement of the "stopper" in the copolymer likely due to efficient transacetalization because of the higher basicity and flexibility of the stopper unit compared with co-units comprising 2 to 4 carbons in length. DSC thermo-grams showed a melting curve of a polymer with melting point lower, as expected, than that of oxymethylene homopolymer. No homopolymer in the copolymer samples was in indicated by TGA. The new acetal copolymer, poly(6-methyl-1,3-dioxocane-co-trioxane), which has a "stopper" co-unit with five carbon atoms along the backbone, contains the longest reported stopper co-unit, potentially leading to improved elongation, and toughness and better compatibility with a range of additives compared to acetal homopolymers.. Chapter 3 presents a novel lamination fabrication method that enables pre-formed TiO2 nanoparticles to become partially embedded in the surface of a thermoplastic polymer film. In this way, the particles are strongly adhered to the surface while remaining accessible to the aqueous solution. By modifying the fabrication conditions (e.g. temperature, pressure, polymer melt viscosity, etc.), the morphology of the hierarchical TiO2-polymer surface can be

  8. Stem cell function and stress response are controlled by protein synthesis.

    Science.gov (United States)

    Blanco, Sandra; Bandiera, Roberto; Popis, Martyna; Hussain, Shobbir; Lombard, Patrick; Aleksic, Jelena; Sajini, Abdulrahim; Tanna, Hinal; Cortés-Garrido, Rosana; Gkatza, Nikoletta; Dietmann, Sabine; Frye, Michaela

    2016-06-15

    Whether protein synthesis and cellular stress response pathways interact to control stem cell function is currently unknown. Here we show that mouse skin stem cells synthesize less protein than their immediate progenitors in vivo, even when forced to proliferate. Our analyses reveal that activation of stress response pathways drives both a global reduction of protein synthesis and altered translational programmes that together promote stem cell functions and tumorigenesis. Mechanistically, we show that inhibition of post-transcriptional cytosine-5 methylation locks tumour-initiating cells in this distinct translational inhibition programme. Paradoxically, this inhibition renders stem cells hypersensitive to cytotoxic stress, as tumour regeneration after treatment with 5-fluorouracil is blocked. Thus, stem cells must revoke translation inhibition pathways to regenerate a tissue or tumour.

  9. Integration of plasma-assisted surface chemical modification, soft lithography, and protein surface activation for single-cell patterning

    Science.gov (United States)

    Cheng, Q.; Komvopoulos, K.

    2010-07-01

    Surface patterning for single-cell culture was accomplished by combining plasma-assisted surface chemical modification, soft lithography, and protein-induced surface activation. Hydrophilic patterns were produced on Parylene C films deposited on glass substrates by oxygen plasma treatment through the windows of polydimethylsiloxane shadow masks. After incubation first with Pluronic F108 solution and then serum medium overnight, surface seeding with mesenchymal stem cells in serum medium resulted in single-cell patterning. The present method provides a means of surface patterning with direct implications in single-cell culture.

  10. Bio-inspired strategy for on-surface synthesis of silver nanoparticles for metal/organic hybrid nanomaterials and LDI-MS substrates.

    Science.gov (United States)

    Hong, Seonki; Lee, Joon Seok; Ryu, Jungki; Lee, Sahng Ha; Lee, Dong Yun; Kim, Dong-Pyo; Park, Chan Beum; Lee, Haeshin

    2011-12-09

    A strategy for the on-surface synthesis of silver nanoparticles (AgNPs) on a variety of two- to three-dimensional material surfaces, utilizing polydopamine, an emerging surface modifying agent, is reported in this paper. This material-independent platform for AgNP synthesis is useful for fabricating organic/inorganic hybrid nanomaterials and for preparing substrates for laser desorption-ionization time-of-flight mass spectrometry (LDI-ToF MS).

  11. Microwave-assisted green synthesis of superparamagnetic nanoparticles using fruit peel extracts: surface engineering, T2 relaxometry, and photodynamic treatment potential

    Directory of Open Access Journals (Sweden)

    Bano S

    2016-08-01

    Full Text Available Shazia Bano,1–3 Samina Nazir,2 Alia Nazir,1 Saeeda Munir,3 Tariq Mahmood,2 Muhammad Afzal,1 Farzana Latif Ansari,4 Kehkashan Mazhar3 1Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, 2Nanosciences and Technology Department, National Centre for Physics, 3Institute of Biomedical and Genetic Engineering (IBGE, 4Pakistan Council for Science and Technology, Islamabad, Pakistan Abstract: Superparamagnetic iron oxide nanoparticles (SPIONs have the potential to be used as multimodal imaging and cancer therapy agents due to their excellent magnetism and ability to generate reactive oxygen species when exposed to light. We report the synthesis of highly biocompatible SPIONs through a facile green approach using fruit peel extracts as the biogenic reductant. This green synthesis protocol involves the stabilization of SPIONs through coordination of different phytochemicals. The SPIONs were functionalized with polyethylene glycol (PEG-6000 and succinic acid and were extensively characterized by X-ray diffraction analysis, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, Rutherford backscattering spectrometry, diffused reflectance spectroscopy, fluorescence emission, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and magnetization analysis. The developed SPIONs were found to be stable, almost spherical with a size range of 17–25 nm. They exhibited excellent water dispersibility, colloidal stability, and relatively high R2 relaxivity (225 mM-1 s-1. Cell viability assay data revealed that PEGylation or carboxylation appears to significantly shield the surface of the particles but does not lead to improved cytocompatibility. A highly significant increase of reactive oxygen species in light-exposed samples was found to play an important role in the photokilling of human cervical epithelial malignant carcinoma (HeLa cells. The bio-SPIONs developed

  12. Studies on the control of ribosomal RNA synthesis in HeLa cells.

    Science.gov (United States)

    Chesterton, C J; Coupar, B E; Butterworth, P H; Green, M H

    1975-09-01

    In many eucaryotic systems protein synthesis is coupled to ribosomal RNA synthesis such that shut-down of the former causes inhibition of the latter. We have investigated this stringency phenomenon in HeLa cells. The protein synthesis inhibitors cycloheximide and puromycin cause inactivation of both processes but valine starvation totally inhibits only the processing of 45-S RNA. DNA-dependent RNA polymerases from A, B and C (or I, II and III respectively) were extracted, separated partially by DEAE-cellulose chromatography and their activity levels determined. These do not decrease significantly during inhibition of protein synthesis. To find out whether or not form A is bound to its template under these conditions, proteins were removed from chromatin with the detergent sarkosyl. This does not affect bound RNA polymerase. Inhibition of protein synthesis caused up to 50% reduction in endogenous alpha-amanitin-insensitive chromatin-RNA-synthesising activity. This reduced level of activity was not affected by sarkosyl treatment. Levels in normal cells were stimulated. This result indicates that the form A RNA polymerase is not bound to its template when protein synthesis is inhibited.

  13. Surface modification of substrates for bacteria and cell culture.

    Science.gov (United States)

    Baede, Tom; Sladek, Raymond; Stoffels, Eva

    2006-10-01

    The plasma needle is a medical device that consists of a tungsten wire placed in a tube through which helium flows. A RF voltage frequency of 13.05 MHz is applied to the wire to produce the plasma. The device has a non-thermal effect and is therefore suited for both organic and inorganic surfaces. It was designed to manipulate tissues, but can also be used to modify the bacterial adhesion properties of material surfaces. The surface modification has a number of applications, most notably cell culture and the preventive treatment of caries. The research consists of two sets of experiments. In the first experiments the effect of the plasma treatment on the wettability was studied by means of contact angle measurements. The wettability quantifies the hydrophilic behavior of a surface. Plasma treatment with the plasma needle significantly increased the wettability of the studied materials. The persistence of the wettability change was also examined. For some materials the effect was only temporary. Bacteria are very particular about the surfaces they adhere to and the wettability of the surface plays an important role in their preference. The next set of experiments dealt with the effect of plasma treatment on bacterial adhesion. This effect was measured by comparing the growth rates of E. coli and S. mutans bacteria that were cultured on both plasma and non-treated surfaces. The effect appears to be species specific.

  14. Induction of phytic acid synthesis by abscisic acid in suspension-cultured cells of rice.

    Science.gov (United States)

    Matsuno, Koya; Fujimura, Tatsuhito

    2014-03-01

    A pathway of phytic acid (PA) synthesis in plants has been revealed via investigations of low phytic acid mutants. However, the regulation of this pathway is not well understood because it is difficult to control the environments of cells in the seeds, where PA is mainly synthesized. We modified a rice suspension culture system in order to study the regulation of PA synthesis. Rice cells cultured with abscisic acid (ABA) accumulate PA at higher levels than cells cultured without ABA, and PA accumulation levels increase with ABA concentration. On the other hand, higher concentrations of sucrose or inorganic phosphorus do not affect PA accumulation. Mutations in the genes RINO1, OsMIK, OsIPK1 and OsLPA1 have each been reported to confer low phytic acid phenotypes in seeds. Each of these genes is upregulated in cells cultured with ABA. OsITPK4 and OsITPK6 are upregulated in cells cultured with ABA and in developing seeds. These results suggest that the regulation of PA synthesis is similar between developing seeds and cells in this suspension culture system. This system will be a powerful tool for elucidating the regulation of PA synthesis.

  15. Iron reverses impermeable chelator inhibition of DNA synthesis in CCl 39 cells.

    OpenAIRE

    Alcain, F J; Löw, H; Crane, F. L.

    1994-01-01

    Treatment of Chinese hamster lung fibroblasts (CCl 39 cells) with the impermeable iron(II) chelator bathophenanthroline disulfonate (BPS) inhibits DNA synthesis when cell growth is initiated with growth factors including epidermal growth factor plus insulin, thrombin, or ceruloplasmin, but not with 10% fetal calf serum. The BPS treatment inhibits transplasma membrane electron transport. The treatment leads to release of iron from the cells as determined by BPS iron(II) complex formation over ...

  16. Proteomics and glycoproteomics of pluripotent stem-cell surface proteins.

    Science.gov (United States)

    Sun, Bingyun

    2015-03-01

    Pluripotent stem cells are a unique cell type with promising potential in regenerative and personalized medicine. Yet the difficulty to understand and coax their seemingly stochastic differentiation and spontaneous self-renewal have largely limited their clinical applications. A call has been made by numerous researchers for a better characterization of surface proteins on these cells, in search of biomarkers that can dictate developmental stages and lineage specifications, and can help formulate mechanistic insight of stem-cell fate choices. In the past two decades, proteomics has gained significant recognition in profiling surface proteins at high throughput. This review will summarize the impact of these studies on stem-cell biology, and discuss the used proteomic techniques. A systematic comparison of all the techniques and their results is also attempted here to help reveal pros, cons, and the complementarity of the existing methods. This awareness should assist in selecting suitable strategies for stem-cell related research, and shed light on technical improvements that can be explored in the future.

  17. Facile synthesis of hydrangea flower-like hierarchical gold nanostructures with tunable surface topographies for single-particle surface-enhanced Raman scattering

    Science.gov (United States)

    Song, C. Y.; Zhou, N.; Yang, B. Y.; Yang, Y. J.; Wang, L. H.

    2015-10-01

    The physicochemical properties of noble metal nanocrystals depend strongly on their size and shape, and it is becoming clear that the design and facile synthesis of particular nanostructures with tailored shape and size is especially important. Herein a novel class of hydrangea flower-like hierarchical gold nanostructures with tunable surface topographies and optical properties are prepared for the first time by a facile, one-pot, seedless synthesis using ascorbic acid (AA) to reduce hydrogen tetrachloroaurate (HAuCl4) in the presence of (1-hexadecyl)trimethylammonium chloride (CTAC). The morphologies of the synthesized gold nanoflowers are controlled and fine-tuned by varying the synthetic conditions such as the concentration of reagents and the growth temperature. Due to their unique hierarchical three-dimensional (3D) structures with rich hot spots, these gold nanoflowers exhibit an efficient performance in single-particle surface-enhanced Raman scattering (SERS). The work stands out as an interesting approach for anisotropic particle synthesis and morphological control, and the proposed novel, hierarchical gold nanoflowers have a number of exciting potential applications in SERS-based sensors.The physicochemical properties of noble metal nanocrystals depend strongly on their size and shape, and it is becoming clear that the design and facile synthesis of particular nanostructures with tailored shape and size is especially important. Herein a novel class of hydrangea flower-like hierarchical gold nanostructures with tunable surface topographies and optical properties are prepared for the first time by a facile, one-pot, seedless synthesis using ascorbic acid (AA) to reduce hydrogen tetrachloroaurate (HAuCl4) in the presence of (1-hexadecyl)trimethylammonium chloride (CTAC). The morphologies of the synthesized gold nanoflowers are controlled and fine-tuned by varying the synthetic conditions such as the concentration of reagents and the growth temperature. Due to

  18. Surface science studies of model fuel cell electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, N.M.; Ross, P.N. [Lawrence Berkeley National Laboratory, Materials Sciences Division, University of California, 94720 Berkeley, CA (United States)

    2002-04-01

    The purpose of this review is to discuss progress in the understanding of electrocatalytic reactions through the study of model systems with surface spectroscopies. Pure metal single crystals and well-characterized bulk alloys have been used quite successfully as models for real (commercial) electrocatalysts. Given the sheer volume of all work in electrocatalysis that is on fuel cell reactions, we will focus on electrocatalysts for fuel cells. Since Pt is the model fuel cell electrocatalyst, we will focus entirely on studies of pure Pt and Pt bimetallic alloys. The electrode reactions discussed include hydrogen oxidation/evolution, oxygen reduction, and the electrooxidation of carbon monoxide, formic acid, and methanol. Surface spectroscopies emphasized are FTIR, STM/AFM and surface X-ray scattering (SXS). The discussion focuses on the relation between the energetics of adsorption of intermediates and the reaction pathway and kinetics, and how the energetics and kinetics relate to the extrinsic properties of the model system, e.g. surface structure and/or composition. Finally, we conclude by discussing the limitations that are reached by using pure metal single crystals and well-characterized bulk alloys as models for real catalysts, and suggest some directions for developing more realistic systems.

  19. Surface science studies of model fuel cell electrocatalysts

    Science.gov (United States)

    Marković, N. M.; Ross, P. N.

    2002-04-01

    The purpose of this review is to discuss progress in the understanding of electrocatalytic reactions through the study of model systems with surface spectroscopies. Pure metal single crystals and well-characterized bulk alloys have been used quite successfully as models for real (commercial) electrocatalysts. Given the sheer volume of all work in electrocatalysis that is on fuel cell reactions, we will focus on electrocatalysts for fuel cells. Since Pt is the model fuel cell electrocatalyst, we will focus entirely on studies of pure Pt and Pt bimetallic alloys. The electrode reactions discussed include hydrogen oxidation/evolution, oxygen reduction, and the electrooxidation of carbon monoxide, formic acid, and methanol. Surface spectroscopies emphasized are FTIR, STM/AFM and surface X-ray scattering (SXS). The discussion focuses on the relation between the energetics of adsorption of intermediates and the reaction pathway and kinetics, and how the energetics and kinetics relate to the extrinsic properties of the model system, e.g. surface structure and/or composition. Finally, we conclude by discussing the limitations that are reached by using pure metal single crystals and well-characterized bulk alloys as models for real catalysts, and suggest some directions for developing more realistic systems.

  20. Multi-domain short peptide molecules for in situ synthesis and biofunctionalization of gold nanoparticles for integrin-targeted cell uptake.

    Science.gov (United States)

    Gulsuner, Hilal Unal; Ceylan, Hakan; Guler, Mustafa O; Tekinay, Ayse B

    2015-05-27

    We describe design and synthesis model of multidomain (modular) peptides (MDPs), which direct a reaction cascade coupling the synthesis and surface functionalization of gold nanoparticles (AuNPs) in a single step. The synthesis is achieved via simple mixing of the aqueous solutions of auric acid and MDPs at room temperature without the addition of any surfactants or toxic intermediate reagents. This method allows facile control over the nanoparticle size between ∼2-15 nm, which opens a practical window for biomedical applications. In contrast to the conventional citrate-mediated methods, peptide-mediated synthesis and stabilization provide increased colloidal stability to AuNPs. As a proof of this concept, we demonstrate active targeting of human breast adenocarcinoma cell line (MCF7) using the one-step-prepared engineered AuNPs. Overall, we propose a single-step, chemically greener, biologically safer method for the synthesis and surface functionalization of gold nanoparticles in a size-controlled manner. The chemical versatility of the MDP design broadens the applicability of this strategy, thereby emerging as a successful alternative for the currently available nanoparticle preparation technologies.

  1. Fixation and stabilization of Escherichia coli cells displaying genetically engineered cell surface proteins.

    Science.gov (United States)

    Freeman, A; Abramov, S; Georgiou, G

    1996-12-05

    A large biotechnological potential is inherent in the display of proteins (e.g., enzymes, single-chain antibodies, on the surface of bacterial cells) (Georgiou et al., 1993). Applications such as immobilized whole-cell biocatalysts or cellular adsorbents require cell fixation to prevent disintegration, stabilization of the anchored protein from leakage, denaturation or proteolysis, and total loss of cell viability, preventing medium and potential product contamination with cells. In this article we describe the adaptation of a simple two-stage chemical crosslinking procedure based on "bi-layer encagement" (Tor et al., 1989) for stabilizing Escherichia coli cells expressing an Lpp-OmpA (46-159)-beta-lactamase fusion that displays beta-lactamase on the cell surface. Bilayer crosslinking and coating the bacteria with a polymeric matrix is accomplished by treating the cells first with either glutaraldehyde or polyglutaraldehyde, followed by secondary crosslinking with polyacrylamide hydrazide. These treatments resulted in a 5- to 25-fold reduction of the thermal inactivation rate constant at 55 degrees C of surface anchored beta-lactamase and completely prevented the deterioration of the cells for at least a week of storage at 4 degrees C. The stabilization procedure developed paves the way to scalable biotechnological applications of E. coli displaying surface anchored proteins as whole-cell biocatalysts and adsorbents.

  2. MEMS-based dynamic cell-to-cell culture platforms using electrochemical surface modifications

    Science.gov (United States)

    Chang, Jiyoung; Yoon, Sang-Hee; Mofrad, Mohammad R. K.; Lin, Liwei

    2011-05-01

    MEMS-based biological platforms with the capability of both spatial placements and time releases of living cells for cell-to-cell culture experiments have been designed and demonstrated utilizing electrochemical surface modification effects. The spatial placement is accomplished by electrochemical surface modification of substrate surfaces to be either adhesive or non-adhesive for living cells. The time control is achieved by the electrical activation of the selective indium tin oxide co-culture electrode to allow the migration of living cells onto the electrode to start the cell-to-cell culture studies. Prototype devices have a three-electrode design with an electrode size of 50 × 50 µm2 and the separation gaps of 2 µm between them. An electrical voltage of -1.5 V has been used to activate the electrodes independently and sequentially to demonstrate the dynamic cell-to-cell culture experiments of NIH 3T3 fibroblast and Madin Darby canine kidney cells. As such, this MEMS platform could be a basic yet versatile tool to characterize transient cell-to-cell interactions.

  3. Analysis of cell surface alterations in Legionella pneumophila cells treated with human apolipoprotein E.

    Science.gov (United States)

    Palusinska-Szysz, Marta; Zdybicka-Barabas, Agnieszka; Cytryńska, Małgorzata; Wdowiak-Wróbel, Sylwia; Chmiel, Elżbieta; Gruszecki, Wiesław I

    2015-03-01

    Binding of human apolipoprotein E (apoE) to Legionella pneumophila lipopolysaccharide was analysed at the molecular level by Fourier-transform infrared spectroscopy, thereby providing biophysical evidence for apoE-L. pneumophila lipopolysaccharide interaction. Atomic force microscopy imaging of apoE-exposed L. pneumophila cells revealed alterations in the bacterial cell surface topography and nanomechanical properties in comparison with control bacteria. The changes induced by apoE binding to lipopolysaccharide on the surface of L. pneumophila cells may participate in: (1) impeding the penetration of host cells by the bacteria; (2) suppression of pathogen intracellular growth and eventually; and (3) inhibition of the development of infection.

  4. Study on the Effect of Synthesis Temperature on the Structural, Surface Morphological and Optical Properties of Methyl Ammonium Lead Iodide Nanoparticles by Sol-Gel Method

    Science.gov (United States)

    Benazeera Beegum, K. A.; Paulose, Maria; Peter, V. J.; Raphael, Rakhy; Sreeja, V. G.; Anila, E. I.

    2016-09-01

    Lead halide perovskite solar cells have recently attracted tremendous attention because of their excellent photovoltaic efficiency. The quality and stability of perovskite films are critical for solar cells. We report the synthesis of methyl ammonium lead iodide (MAPbKI3) nanoparticles from methyl amine, hydroiodic acid and lead iodide by sol-gel method. Three powder samples of Methyl ammonium Lead Iodide were prepared at 50 °C, 90 °C, and 100 °C. The powder samples were characterised by X-ray diffraction (XRD), Diffuse reflectance spectroscopy (DRS), Scanning Electron Microscopy (SEM), Energy Dispersive Analysis of X- rays (EDAX) and Photoluminescence (PL). The presence of carbon, hydrogen and nitrogen were examined through CHN studies. The surface morphology, band gap, and elemental contents changes with temperature. The XRD pattern exhibited major reflections from (110), (220), (310), (224) and (314) planes in agreement with JCPDS file No: 00-021-1276, revealing tetragonal structure.

  5. A versatile chemical conversion synthesis of Cu2S nanotubes and the photovoltaic activities for dye-sensitized solar cell.

    Science.gov (United States)

    Shuai, Xuemin; Shen, Wenzhong; Hou, Zhaoyang; Ke, Sanmin; Xu, Chunlong; Jiang, Cheng

    2014-01-01

    A versatile, low-temperature, and low-cost chemical conversion synthesis has been developed to prepare copper sulfide (Cu2S) nanotubes. The successful chemical conversion from ZnS nanotubes to Cu2S ones profits by the large difference in solubility between ZnS and Cu2S. The morphology, structure, and composition of the yielded products have been examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements. We have further successfully employed the obtained Cu2S nanotubes as counter electrodes in dye-sensitized solar cells. The light-to-electricity conversion results show that the Cu2S nanostructures exhibit high photovoltaic conversion efficiency due to the increased surface area and the good electrocatalytical activity of Cu2S. The present chemical route provides a simple way to synthesize Cu2S nanotubes with a high surface area for nanodevice applications.

  6. Effects of ZnO nanowire synthesis parameters on the photovoltaic performance of dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Juneui; Myoung, Jihyun; Lim, Sangwoo, E-mail: swlim@yonsei.ac.kr

    2012-06-30

    Determination of the effects of ZnO nanowires on the efficiency of ZnO nanowire-based dye-sensitized solar cells (DSSCs) is important. In this study, we determined the effects of different OH{sup -} precursors, concentrations, the ratio of zinc nitrate to hexamethylene tetramine (HMT), and the hydrothermal synthesis temperature on the physical, crystal, and optical properties of ZnO nanowires and investigated the performance of the resulting DSSCs. We observed that ZnO nanowires synthesized using an equimolar ratio of HMT to zinc nitrate yielded a DSSC with high incident photon-to-current efficiency (IPCE), cell efficiency, short circuit current density (J{sub sc}), and fill factor (FF), and low ZnO-dye-electrolyte interface resistance due to an increased amount of dye and a decreased density of defects. Furthermore, ZnO nanowires made using optimal concentrations and ratios of zinc nitrate to HMT had a high surface area and low defect density. All the photovoltaic performance parameters of DSSCs assessed such as IPCE, cell efficiency, J{sub sc}, open circuit potential (V{sub oc}), and FF increased with synthesis temperature, which was related to a decrease in the resistance at the ZnO-dye-electrolyte interface. We attributed these results to an increased amount of dye facilitated by a large nanowire surface area and fast electron transfer because of the improved crystalline structure of the ZnO nanowires and their low defect density. By optimizing the ZnO nanowires, we increased DSSC efficiency to 0.26% using ZnO nanowires synthesized with 25 mM of both zinc nitrate and HMT at 90 Degree-Sign C, while only a 0.02% increase in efficiency was obtained when NH{sub 4}OH was used as OH{sup -} precursor. - Highlights: Black-Right-Pointing-Pointer Fabrication of ZnO nanowire-based dye-sensitized solar cells (DSSCs) Black-Right-Pointing-Pointer Correlation of synthesis parameters with ZnO nanowires' properties and DSSC performance Black

  7. Novel Salt-Assisted Combustion Synthesis of High Surface Area Ceria Nanopowders by An Ethylene Glycol-Nitrate Combustion Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A novel salt-assisted combustion process with ethylene glycol as a fuel and nitrate as an oxidant to synthesize high surface area ceria nanopowders was reported. The effects of various tunable conditions, such as fuel-to-oxidant ratio, type of salts, and amount of added salts, on the characteristics of the as-prepared powders were investigated by X-ray diffraction, transmission electron microscopy and BET surface area measurement. A mechanism scheme was proposed to illustrate the possible formation processes of well-dispersed ceria nanoparticles in the salt-assisted combustion synthesis. It was verified that the simple introduction of leachable inert inorganic salts as an excellent agglomeration inhibitor into the redox mixture precursor leads to the formation of well-dispersed ceria particles with particle size in the range of 4~6 nm and a drastic increase in the surface area. The presence of KCl results in an over ten-fold increment in specific surface area from 14.10 m2·g-1 for the produced ceria powders via the conventional combustion synthesis process to 156.74 m2·g-1 for the product by the salt-assisted combustion synthesis process at the same molar ratio of ethylene glycol-nitrate.

  8. Surface modified alginate microcapsules for 3D cell culture

    Science.gov (United States)

    Chen, Yi-Wen; Kuo, Chiung Wen; Chueh, Di-Yen; Chen, Peilin

    2016-06-01

    Culture as three dimensional cell aggregates or spheroids can offer an ideal platform for tissue engineering applications and for pharmaceutical screening. Such 3D culture models, however, may suffer from the problems such as immune response and ineffective and cumbersome culture. This paper describes a simple method for producing microcapsules with alginate cores and a thin shell of poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) to encapsulate mouse induced pluripotent stem (miPS) cells, generating a non-fouling surface as an effective immunoisolation barrier. We demonstrated the trapping of the alginate microcapsules in a microwell array for the continuous observation and culture of a large number of encapsulated miPS cells in parallel. miPS cells cultured in the microcapsules survived well and proliferated to form a single cell aggregate. Droplet formation of monodisperse microcapsules with controlled size combined with flow cytometry provided an efficient way to quantitatively analyze the growth of encapsulated cells in a high-throughput manner. The simple and cost-effective coating technique employed to produce the core-shell microcapsules could be used in the emerging field of cell therapy. The microwell array would provide a convenient, user friendly and high-throughput platform for long-term cell culture and monitoring.

  9. Surface engineering and characterization of quantum dots and its application in living cell imaging

    Directory of Open Access Journals (Sweden)

    Han QIU

    2016-06-01

    Full Text Available Objective  Surface modification of hydrophobic nanoparticles is a key process for their application in the biological medicine fields. The aim of present study is to prepare the immunofluorescent probes by conjugation of hydrophilic surface-engineered quantum dots (QDs and monoclonal antibody for use of fluorescence labeled cells tracing. Methods  The bovine serum albumin (BSA with excellent water-solubility and biocompatibility was employed as the emulsifying agent, and used for surface modification of hydrophobic QDs under ultrasonication. The diameter, fluorescence spectrum and cytotoxicity of BSA-coated QDs (BSA-triP.QDs were analyzed. Then the BSA-coated QDs were conjugated with trastuzumab, which can be recognized and bound specifically to HER2. SKBR-3 breast cancer cells, with over-expression of HER-2, were labeled with hydrophilic QDstrastuzumab and imaged on a fluorescence planar imaging system. Results  The experimental results revealed that BSA as the emulsifying agent, combined with other polymers, can effectively phase transfer hydrophobic QDs. The BSA functionalized QDs exhibited excellent colloidal stability with fine hydrodynamic size distribution (about 70nm in a wide range of pH and ionic strengths values. Moreover, no significant cytotoxic effect was observed in SKBR-3 cells treated with BSA-coated QDs. After being coupled with trastuzumab, the hydrophilic QDs can be used as an immunofluorescence probe for HER2-positive breast cancer cell imaging. Conclusions  The advantages of BSA-coated QDs include straight forward synthesis, high colloidal stability, and promising immunofluorescence characteristic when coupled with specific antibody. These are therefore proved to be ideal nano systems for biomedical labeling, targeting, and imaging. DOI: 10.11855/j.issn.0577-7402.2016.05.04

  10. The flavoprotein Tah18-dependent NO synthesis confers high-temperature stress tolerance on yeast cells

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Akira; Kawahara, Nobuhiro [Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Takagi, Hiroshi, E-mail: hiro@bs.naist.jp [Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan)

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer NO is produced from L-arginine in response to elevated temperature in yeast. Black-Right-Pointing-Pointer Tah18 was first identified as the yeast protein involved in NO synthesis. Black-Right-Pointing-Pointer Tah18-dependent NO synthesis confers tolerance to high-temperature on yeast cells. -- Abstract: Nitric oxide (NO) is a ubiquitous signaling molecule involved in the regulation of a large number of cellular functions. In the unicellular eukaryote yeast, NO may be involved in stress response pathways, but its role is poorly understood due to the lack of mammalian NO synthase (NOS) orthologues. Previously, we have proposed the oxidative stress-induced L-arginine synthesis and its physiological role under stress conditions in yeast Saccharomyces cerevisiae. Here, our experimental results indicated that increased conversion of L-proline into L-arginine led to NO production in response to elevated temperature. We also showed that the flavoprotein Tah18, which was previously reported to transfer electrons to the Fe-S cluster protein Dre2, was involved in NO synthesis in yeast. Gene knockdown analysis demonstrated that Tah18-dependent NO synthesis confers high-temperature stress tolerance on yeast cells. As it appears that such a unique cell protection mechanism is specific to yeasts and fungi, it represents a promising target for antifungal activity.

  11. Surface proteome analysis and characterization of surface cell antigen (Sca or autotransporter family of Rickettsia typhi.

    Directory of Open Access Journals (Sweden)

    Khandra T Sears

    Full Text Available Surface proteins of the obligate intracellular bacterium Rickettsia typhi, the agent of murine or endemic typhus fever, comprise an important interface for host-pathogen interactions including adherence, invasion and survival in the host cytoplasm. In this report, we present analyses of the surface exposed proteins of R. typhi based on a suite of predictive algorithms complemented by experimental surface-labeling with thiol-cleavable sulfo-NHS-SS-biotin and identification of labeled peptides by LC MS/MS. Further, we focus on proteins belonging to the surface cell antigen (Sca autotransporter (AT family which are known to be involved in rickettsial infection of mammalian cells. Each species of Rickettsia has a different complement of sca genes in various states; R. typhi, has genes sca1 thru sca5. In silico analyses indicate divergence of the Sca paralogs across the four Rickettsia groups and concur with previous evidence of positive selection. Transcripts for each sca were detected during infection of L929 cells and four of the five Sca proteins were detected in the surface proteome analysis. We observed that each R. typhi Sca protein is expressed during in vitro infections and selected Sca proteins were expressed during in vivo infections. Using biotin-affinity pull down assays, negative staining electron microscopy, and flow cytometry, we demonstrate that the Sca proteins in R. typhi are localized to the surface of the bacteria. All Scas were detected during infection of L929 cells by immunogold electron microscopy. Immunofluorescence assays demonstrate that Scas 1-3 and 5 are expressed in the spleens of infected Sprague-Dawley rats and Scas 3, 4 and 5 are expressed in cat fleas (Ctenocephalides felis. Sca proteins may be crucial in the recognition and invasion of different host cell types. In short, continuous expression of all Scas may ensure that rickettsiae are primed i to infect mammalian cells should the flea bite a host, ii to remain

  12. Basic surface properties of Aedes albopictus cells: effect of Mayaro virus infection on electrostatic charge and surface tension.

    Science.gov (United States)

    Mezêncio, J M; Costa e Silva Filho, F; Rebello, M A

    1997-01-01

    Aedes albopictus cells possess a negative cell surface charge of -12.7 mV with an isoelectrophoretic point (IEP) located between pH 3.0 and 4.0. Infection with Mayaro virus rendered the surface of A. albopictus cells less negative reaching a zeta-potential value of -9.7 mV after 100 h of infection. Concomitantly, the IEP of the infected cells were also altered from 3.0-4.0 to 4.0-5.0. Furthermore, the contact angle measurements clearly showed qualitative alterations in the cell surface of infected cells.

  13. Distinguishing between whole cells and cell debris using surface plasmon coupled emission (Conference Presentation)

    Science.gov (United States)

    Talukder, Muhammad A.; Menyuk, Curtis R.; Kostov, Yordan

    2017-02-01

    Distinguishing between intact cells, dead but still whole cells, and cell debris is an important but difficult task in life sciences. The most common way to identify dead cells is using a cell-impermeant DNA binding dye, such as propidium iodide. A healthy living cell has an intact cell membrane and will act as a barrier to the dye so that it cannot enter the cell. A dead cell has a compromised cell membrane, and it will allow the dye into the cell to bind to the DNA and become fluorescent. The dead cells therefore will be positive and the live cells will be negative. The dead cells later deteriorate quickly into debris. Different pieces of debris from a single cell can be incorrectly identified as separate dead cells. Although a flow cytometer can quickly perform numerous quantitative, sensitive measurements on each individual cell to determine the viability of cells within a large, heterogeneous population, it is bulky, expensive, and only large hospitals and laboratories can afford them. In this work, we show that the distance-dependent coupling of fluorophore light to surface plasmon coupled emission (SPCE) from fluorescently-labeled cells can be used to distinguish whole cells from cell debris. Once the fluorescent labels are excited by a laser, the fluorescently-labeled whole cells create two distinct intensity rings in the far-field, in contrast to fluorescently-labeled cell debris, which only creates one ring. The distinct far-field patterns can be captured by camera and used to distinguish between whole cells and cell debris.

  14. Synthesis of polymer nanostructures via the use of surfactant surface aggregates as templates

    Science.gov (United States)

    Marquez, Maricel

    The subject of this work is the synthesis of polymer nanostructures via the use of surfactant surface aggregates as templates, also termed Template Assisted Admicellar Polymerization (TAAP). The first chapter reviews some of the most current nanopatterning techniques (including both top-down and bottom-up approaches), with particular emphasis on the fabrication of organic and inorganic patterned nanostructures via particle lithography. In chapter 2, highly ordered hexagonal arrays of latex spheres were prepared on highly ordered pyrolytic graphite (HOPG) from a variation of the Langmuir Blodgett technique, using an anionic surfactant (SDS), and a low molecular weight (ca. 10000) polyacrylamide as spreading agents. When a nonionic polyethoxylated (EO = 9) surfactant was used as the spreading agent, no ordered arrays were observed. Based on the correlation found between the surface tension in the presence of the latex particles and the critical concentration at which hexagonal arrangements of latex spheres occurs; a model was proposed to explain the role of the spreading agent in forming stable monolayers at the air/liquid interface, which in turn are necessary for the formation of well-ordered monolayers on a solid substrate from the LB technique. According to this model, solid-like regions of small numbers of latex spheres form at the liquid-air interface, which are then transferred to the substrate. These ordered regions then act as nuclei for the formation of 2D arrays of latex spheres on the surface upon water evaporation. The role of other factors such as relative humidity, substrate and solvent choice, and pulling vs. compression speed were also found to affect the quality of the monolayers formed. Finally, a simple, easy to automate, yet effective surface tension method was proposed to predict the optimal conditions for the formation of ordered monolayers using a variation of the LB deposition method from any monodisperse set of spheres. In chapter 3, a novel

  15. Hydrothermal synthesis of high surface area ZIF-8 with minimal use of TEA

    Science.gov (United States)

    Butova, V. V.; Budnyk, A. P.; Bulanova, E. A.; Lamberti, C.; Soldatov, A. V.

    2017-07-01

    In this paper we present, for the first time, a simple hydrothermal recipe for the synthesis of ZIF-8 Metal-Organic Framework (MOF) with a large specific surface area (1340 m2/g by BET). An important feature of the method is that the product forms in aqueous medium under standard hydrothermal conditions without DMF and great excess of linker with the use of TEA as structure directing agent. The ZIF-8 crystal phase of the product was confirmed by XRD; this technique has been also exploited to check the crystallinity and to follow the changes in the MOF structure induced by heating. TGA and temperature dependent XRD testify the high thermal stability of the material (470 °C in N2 and at 400 °C in air). The IR spectral profile of the material provides a complete picture of vibrations assigned to the linker and the metal center. The systematic investigation of the products obtained by increasing the TEA amount in the reacting medium from 0 to 25.5 mol equivalent Zn2+, allowed us to understand its role and to find 2.6 mol equivalent Zn2+ as the minimum amount needed to obtain a single phase ZIF-8 material with the high standard reported above. The stability of the material under severe basic conditions makes it a promising candidate in heterogeneous catalysis. The material has shown high capacity in I2 uptake, making it interesting also for selective molecular adsorption.

  16. CdSe Nanoparticles with Clean Surfaces: Gas Phase Synthesis and Optical Properties

    Directory of Open Access Journals (Sweden)

    Zhang Hongwei

    2015-01-01

    Full Text Available CdSe nanoparticles (NPs were generated in gas phase with a magnetron plasma gas aggregation cluster beam source. Coagulation-free CdSe nanocrystals with very clean particle surface and interface, as well as a fairly uniform spatial distribution were obtained. The deposited NPs have a good dispersity with a mean diameter of about 4.8nm. A strong photoluminescence band corresponding to the near- band-edge transition of the CdSe NPs was observed. The CdSe NP films show a significant photoconductance induced by laser irradiation. With an applied bias voltage of 10V, the photo- induced current can be as high as 0.4mA under 0.01mW/mm2 405nm laser illumination. Our approach offers an alternative method for CdSe NP synthesis, which has the advantages such as high purity, good process and product control, as well as mass production, as compared to the existing methods.

  17. Optimization of reaction conditions for enzymatic synthesis of palm fatty hydrazides using response surface methodology.

    Science.gov (United States)

    Tuan Noor Maznee, T I; Hazimah, A H; Wan Zin, W Y

    2012-01-01

    Optimization of the enzymatic synthesis of palm fatty hydrazide by the response surface methodology (RSM) was conducted using the Design-Expert 6 software. The palm fatty hydrazide was synthesized from refined, bleached and deodorized palm olein (RBDPOo) and neutralized hydrazine monohydrate in the presence of Rhizomucor miehei lipase, Lipozyme RMIM, an immobilized lipase in n-hexane. The reaction conditions such as the percentage of enzyme, reaction temperature, stirring speed and reaction time were selected as independent variables or studied factors, while the amount of crude palm fatty hydrazide obtained was selected as a dependent variable or response. The study was conducted using a central composite design (CCD) at five coded levels and the experimental data were analyzed using a quadratic model. The analysis of variance (ANOVA) indicates that the model was significant at 95% confidence level with Prob>F of 0.0033, where the regression coefficient value, R² was 0.8415 and lack-of-fit of 0.0984. A percentage of enzyme of 6%, a reaction temperature of 40°C, a stirring speed of 350 rpm and a reaction time of 18 h were found to be the optimum conditions for the conversion of RBDPOo into palm fatty hydrazide.

  18. A New Energy Source for Organic Synthesis in Europa's Surface Ice

    Science.gov (United States)

    Borucki, Jerome G.; Khare, Bishun; Cruikshank, Dale P.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    Colored regions on Jupiter's satellite Europa and other icy bodies in the outer Solar System may be contaminated by organic macromolecular solid material that is produced when surface ices are exposed to electrical energy. Hypervelocity meteorite impacts and fracture release tidal and tectonic stresses in icy crusts in the form of electrical discharges, which provide the energy for in situ synthesis of the organic solids. We report measurements of electrical discharge, light emission, and magnetic phenomena in hypervelocity impacts into ice with projectiles with V approx. 5 km/s. Part of the projectile's kinetic energy is converted into electrical potential, while the mechanical disruption of the impact also releases stress energy as light, heat, electrical, and magnetic fields as secondary emissions. These newly recognized energy sources suggest that the dark material in the area of impact craters are tholins generated from the energy of the impacts and that well up from the fracture zone. Large pools of liquid water would persist under the meteorite crater for thousands of years, with the potential for prebiotic chemistry to take place at an accelerated rate due to energy pumped in from the secondary emissions.

  19. SYNTHESIS OF AMPHIPHILIC COMB-SHAPED COPOLYMERS USED FOR SURFACE MODIFICATION OF PVDF MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    Jian-hua Li; You-yi Xu; Jian-hua Wang; Chun-hui Du

    2009-01-01

    The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4-hydroxyphenyl) maleimide) (SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate (PEGMA) side groups was achieved by atom transfer radical polymerization (ATRP). The amphiphilic copolymers were characterized by ~1H-NMR, Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). From thermogravimetric analysis (TGA), the decomposition temperature of SHMI-g-PEGMA is lower than that of SHMI, and the graft ratio of PEGMA in the SHMI is 18.6%. The experimental results of solubilities showed that SHMI, SHMI-Br and SHMI-g-PEGMA had excellent solubility in polar solvents, such as DMF, DMSO and NMP. SHMI-g-PEGMA had higher solubilities in H_2O and methanol, while lower solubility in CHCl_3 than SHMI and SHMI-Br. PVDF blend membranes were prepared via the standard immersion precipitation phase inversion process, using amphiphilic SHMI-g-PEGMA copolymer as additives. The morphology and hydrophilicity of the blend membrane surfaces were characterized by SEM and water contact angle. It is demonstrated that the blend membranes display enhanced hydrophilicity compared to unmodified PVDF membranes. Finally, the permeation and anti-fouling properties were investigated. The result shows that amphiphilic SHMI-g-PEGMA copolymer increases the permeatability and anti-fouling property of PVDF membranes greatly.

  20. Facile synthesis of diverse graphene nanomeshes based on simultaneous regulation of pore size and surface structure

    Science.gov (United States)

    Zhang, Jia; Song, Huaibing; Zeng, Dawen; Wang, Hao; Qin, Ziyu; Xu, Keng; Pang, Aimin; Xie, Changsheng

    2016-08-01

    Recently, graphene nanomesh (GNM) has attracted great attentions due to its unique porous structure, abundant active sites, finite band gap and possesses potential applications in the fields of electronics, gas sensor/storage, catalysis, etc. Therefore, diverse GNMs with different physical and chemical properties are required urgently to meet different applications. Herein we demonstrate a facile synthetic method based on the famous Fenton reaction to prepare GNM, by using economically fabricated graphene oxide (GO) as a starting material. By precisely controlling the reaction time, simultaneous regulation of pore size from 2.9 to 11.1 nm and surface structure can be realized. Ultimately, diverse GNMs with tunable band gap and work function can be obtained. Specially, the band gap decreases from 4.5-2.3 eV for GO, which is an insulator, to 3.9-1.24 eV for GNM-5 h, which approaches to a semiconductor. The dual nature of electrophilic addition and oxidizability of HO• is responsible for this controllable synthesis. This efficient, low-cost, inherently scalable synthetic method is suitable for provide diverse and optional GNMs, and may be generalized to a universal technique.

  1. Seedless synthesis of nanocomposites, optical properties, and effects of additives on their surface resonance plasmon bands

    Science.gov (United States)

    Zaheer, Zoya; Aazam, Elham Shafik

    2017-07-01

    The work describes an easy seedless competitive chemical reduction method for the synthesis of Ag@Au/Ag bimetallic nanoparticles by mixing AgNO3, HAuCl4 and cysteine. Transmission electron microscope (TEM) images show that the large number of irregular, cross-linking, and aggregated Ag@Au/Ag are formed in a reaction mixture (HAuCl4 + AgNO3 + cysteine), whereas flower-like nanocomposites are obtained in presence of cetyltrimethylammonium bromide (CTAB), which acted as a shape-directing agent. Optical images reveal that the initially reaction proceeds through formation of purple color, which changes into dark brown color with the reaction time, indicating the formation of Ag@Au/Ag nanocomposites. The Ag+ has strong tendency to form complex with cysteine. Firstly, the reduction of Ag+ ions to Ag0 occurred by the sbnd HSsbnd group of the cysteine-Ag complex. Secondly, AuCl4- ions adsorbed on the positive surface of Ag0, which undergoes reduction by potential deposition, and leads to the formation of Ag@Au/Ag bimetallic nanoparticles. Inorganic electrolytes (NaCl, NaBr, NaNO3 and Na2SO4) have significant impact on the stability and aggregation of Ag@Au/Ag nanocomposites.

  2. A new approach to synthesis of benzyl cinnamate: Optimization by response surface methodology.

    Science.gov (United States)

    Zhang, Dong-Hao; Zhang, Jiang-Yan; Che, Wen-Cai; Wang, Yun

    2016-09-01

    In this work, the new approach to synthesis of benzyl cinnamate by enzymatic esterification of cinnamic acid with benzyl alcohol is optimized by response surface methodology. The effects of various reaction conditions, including temperature, enzyme loading, substrate molar ratio of benzyl alcohol to cinnamic acid, and reaction time, are investigated. A 5-level-4-factor central composite design is employed to search for the optimal yield of benzyl cinnamate. A quadratic polynomial regression model is used to analyze the experimental data at a 95% confidence level (P<0.05). The coefficient of determination of this model is found to be 0.9851. Three sets of optimum reaction conditions are established, and the verified experimental trials are performed for validating the optimum points. Under the optimum conditions (40°C, 31mg/mL enzyme loading, 2.6:1 molar ratio, 27h), the yield reaches 97.7%, which provides an efficient processes for industrial production of benzyl cinnamate.

  3. Large-scale synthesis and surface plasmon resonance properties of angled silver/silver homojunction nanowires

    Science.gov (United States)

    Lai, Xuandi; Feng, Xiumei; Zhang, Menghuan; Hong, Ruijin; Chen, Yongxiang; Li, Aiqing; Deng, Xiulong; Hu, Jianqiang

    2014-03-01

    Angled silver/silver (Ag/Ag) homojunction nanowires (HNWs) with an average diameter of about 72 nm have been prepared by a straightforward and effective solvothermal method. The synthesis involves a one-step, non-seed, and template-less process to large-scale Ag/Ag HNWs, which is low-cost and proceeds at moderate temperatures. Two neighboring Ag nanorods or nanowires were connected into obtuse angle by Ag/Ag homojunction. It was found that synthesizing Ag/Ag HNWs were very sensitive to reaction temperature and polyvinylpyrrolidone concentration. Only through finely controlling these reaction parameters, the high-quality Ag/Ag HNWs could be formed in large scale and their surface plasmon resonance properties could be effectively tailored. High-resolution transmission electron microscopy and selected area electron diffraction investigations showed that the Ag/Ag HNWs were generated with a twinned crystalline structure. We also proposed a primary experimental model to illustrate the growth mechanism of the angled Ag/Ag HNWs.

  4. A New Energy Source for Organic Synthesis in Europa's Surface Ice

    Science.gov (United States)

    Borucki, Jerome G.; Khare, Bishun; Cruikshank, Dale P.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    Colored regions on Jupiter's satellite Europa and other icy bodies in the outer Solar System may be contaminated by organic macromolecular solid material that is produced when surface ices are exposed to electrical energy. Hypervelocity meteorite impacts and fracture release tidal and tectonic stresses in icy crusts in the form of electrical discharges, which provide the energy for in situ synthesis of the organic solids. We report measurements of electrical discharge, light emission, and magnetic phenomena in hypervelocity impacts into ice with projectiles with V approx. 5 km/s. Part of the projectile's kinetic energy is converted into electrical potential, while the mechanical disruption of the impact also releases stress energy as light, heat, electrical, and magnetic fields as secondary emissions. These newly recognized energy sources suggest that the dark material in the area of impact craters are tholins generated from the energy of the impacts and that well up from the fracture zone. Large pools of liquid water would persist under the meteorite crater for thousands of years, with the potential for prebiotic chemistry to take place at an accelerated rate due to energy pumped in from the secondary emissions.

  5. On-surface synthesis of graphene nanoribbons with zigzag edge topology.

    Science.gov (United States)

    Ruffieux, Pascal; Wang, Shiyong; Yang, Bo; Sánchez-Sánchez, Carlos; Liu, Jia; Dienel, Thomas; Talirz, Leopold; Shinde, Prashant; Pignedoli, Carlo A; Passerone, Daniele; Dumslaff, Tim; Feng, Xinliang; Müllen, Klaus; Fasel, Roman

    2016-03-24

    Graphene-based nanostructures exhibit electronic properties that are not present in extended graphene. For example, quantum confinement in carbon nanotubes and armchair graphene nanoribbons leads to the opening of substantial electronic bandgaps that are directly linked to their structural boundary conditions. Nanostructures with zigzag edges are expected to host spin-polarized electronic edge states and can thus serve as key elements for graphene-based spintronics. The edge states of zigzag graphene nanoribbons (ZGNRs) are predicted to couple ferromagnetically along the edge and antiferromagnetically between the edges, but direct observation of spin-polarized edge states for zigzag edge topologies--including ZGNRs--has not yet been achieved owing to the limited precision of current top-down approaches. Here we describe the bottom-up synthesis of ZGNRs through surface-assisted polymerization and cyclodehydrogenation of specifically designed precursor monomers to yield atomically precise zigzag edges. Using scanning tunnelling spectroscopy we show the existence of edge-localized states with large energy splittings. We expect that the availability of ZGNRs will enable the characterization of their predicted spin-related properties, such as spin confinement and filtering, and will ultimately add the spin degree of freedom to graphene-based circuitry.

  6. New nanostructured materials: synthesis of dodecanuclear Ni(II) complexes and surface deposition studies.

    Science.gov (United States)

    Pons-Balagué, Alba; Piligkos, Stergios; Teat, Simon J; Sánchez Costa, Jose; Shiddiq, Muhandis; Hill, Stephen; Castro, German R; Ferrer-Escorihuela, Pilar; Sañudo, E Carolina

    2013-07-01

    Microwave-assisted synthesis has been used to obtain the family of dodecanuclear Ni(II) complexes [Ni12(NO3)(MeO)12(MeC6H4CO2)9(MeOH)10(H2O)2][ClO4]2 (1), [Ni12(NO3)(MeO)12(BrC6H4CO2)9(MeOH)10(H2O)2][ClO4]2 (2), [Ni12(CO3)(MeO)12(MeC6H4CO2)9(MeOH)10(H2O)2]2[SO4] (3) and [Ni12(NO3)(MeO)12(MeC6H4CO2)9(MeOH)8(H2O)7][NO3]2 (4). They contain three {Ni4O4} cubane units which template around a central μ6 anion, either NO3(-) or CO3(2-). Their magnetic properties have been studied by superconducting quantum interference device (SQUID) magnetometry and high-field EPR measurements. The nanostructuration of the Ni12 species on mica surfaces is studied by AFM and grazing-incidence X-ray diffraction, which reveal the formation of polycrystalline thin layers.

  7. Cell-Autonomous Gβ Signaling Defines Neuron-Specific Steady State Serotonin Synthesis in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Lu Xu

    2015-09-01

    Full Text Available Heterotrimeric G proteins regulate a vast array of cellular functions via specific intracellular effectors. Accumulating pharmacological and biochemical studies implicate Gβ subunits as signaling molecules interacting directly with a wide range of effectors to modulate downstream cellular responses, in addition to their role in regulating Gα subunit activities. However, the native biological roles of Gβ-mediated signaling pathways in vivo have been characterized only in a few cases. Here, we identified a Gβ GPB-1 signaling pathway operating in specific serotonergic neurons to the define steady state serotonin (5-HT synthesis, through a genetic screen for 5-HT synthesis mutants in Caenorhabditis elegans. We found that signaling through cell autonomous GPB-1 to the OCR-2 TRPV channel defines the baseline expression of 5-HT synthesis enzyme tryptophan hydroxylase tph-1 in ADF chemosensory neurons. This Gβ signaling pathway is not essential for establishing the serotonergic cell fates and is mechanistically separated from stress-induced tph-1 upregulation. We identified that ADF-produced 5-HT controls specific innate rhythmic behaviors. These results revealed a Gβ-mediated signaling operating in differentiated cells to specify intrinsic functional properties, and indicate that baseline TPH expression is not a default generic serotonergic fate, but is programmed in a cell-specific manner in the mature nervous system. Cell-specific regulation of TPH expression could be a general principle for tailored steady state 5-HT synthesis in functionally distinct neurons and their regulation of innate behavior.

  8. Anisotropic noble metal nanoparticles: Synthesis, surface functionalization and applications in biosensing, bioimaging, drug delivery and theranostics.

    Science.gov (United States)

    Paramasivam, Gokul; Kayambu, Namitharan; Rabel, Arul Maximus; Sundramoorthy, Ashok K; Sundaramurthy, Anandhakumar

    2017-02-01

    Anisotropic nanoparticles have fascinated scientists and engineering communities for over a century because of their unique physical and chemical properties. In recent years, continuous advances in design and fabrication of anisotropic nanoparticles have opened new avenues for application in various areas of biology, chemistry and physics. Anisotropic nanoparticles have the plasmon absorption in the visible as well as near-infrared (NIR) region, which enables them to be used for crucial applications such as biological imaging, medical diagnostics and therapy ("theranostics"). Here, we describe the progress in anisotropic nanoparticles achieved since the millennium in the area of preparation including various shapes and modification of the particle surface, and in areas of application by providing examples of applications in biosensing, bio-imaging, drug delivery and theranostics. Furthermore, we also explain various mechanisms involved in cellular uptake of anisotropic nanoparticles, and conclude with our opinion on various obstacles that limit their applications in biomedical field. Anisotropy at the molecular level has always fascinated scientists and engineering communities for over a century, however, the research on novel methods through which shape and size of nanoparticles can be precisely controlled has opened new avenues for anisotropic nanoparticles in various areas of biology, chemistry and physics. In this manuscript, we describe progress achieved since the millennium in the areas of preparation of various shapes of anisotropic nanoparticles, investigate various methods involved in modifying the surface of these NPs, and provide examples of applications in biosensing and bio-imaging, drug delivery and theranostics. We also present mechanisms involved in cellular uptake of nanoparticles, describe different methods of preparation of anisotropic nanoparticles including biomimetic and photochemical synthesis, and conclude with our opinion on various

  9. Characterization of atrial natriuretic peptide degradation by cell-surface peptidase activity on endothelial cells

    Science.gov (United States)

    Frost, S. J.; Whitson, P. A.

    1993-01-01

    Atrial natriuretic peptide (ANP) is a fluid-regulating peptide hormone that promotes vasorelaxation, natriuresis, and diuresis. The mechanisms for the release of ANP and for its clearance from the circulation play important roles in modulating its biological effects. Recently, we have reported that the cell surface of an endothelial cell line, CPA47, could degrade 125I-ANP in the presence of EDTA. In this study, we have characterized this degradation of 125I-ANP. The kinetics of ANP degradation by the surface of CPA47 cells were first order, with a Km of 320 +/- 60 nM and Vmax of 35 +/- 14 pmol of ANP degraded/10 min/10(5) cells at pH 7.4. ANP is degraded by the surface of CPA47 cells over a broad pH range from 7.0-8.5. Potato carboxypeptidase inhibitor and bestatin inhibited 125I-ANP degradation, suggesting that this degradative activity on the surface of CPA47 cells has exopeptidase characteristics. The selectivity of CPA47 cell-surface degradation of ANP was demonstrated when 125I-ANP degradation was inhibited in the presence of neuropeptide Y and angiotensin I and II but not bradykinin, bombesin, endothelin-1, or substance P. The C-terminal amino acids phe26 and tyr28 were deduced to be important for ANP interaction with the cell-surface peptidase(s) based on comparison of the IC50 of various ANP analogues and other natriuretic peptides for the inhibition of ANP degradation. These data suggest that a newly characterized divalent cation-independent exopeptidase(s) that selectively recognizes ANP and some other vasoactive peptides exists on the surface of endothelial cells.

  10. Brown spider venom toxins interact with cell surface and are endocytosed by rabbit endothelial cells.

    Science.gov (United States)

    Nowatzki, Jenifer; de Sene, Reginaldo Vieira; Paludo, Katia Sabrina; Veiga, Silvio Sanches; Oliver, Constance; Jamur, Maria Célia; Nader, Helena Bonciani; Trindade, Edvaldo S; Franco, Célia Regina C

    2010-09-15

    Bites from the Loxosceles genus (brown spiders) cause severe clinical symptoms, including dermonecrotic injury, hemorrhage, hemolysis, platelet aggregation and renal failure. Histological findings of dermonecrotic lesions in animals exposed to Loxosceles intermedia venom show numerous vascular alterations. Study of the hemorrhagic consequences of the venom in endothelial cells has demonstrated that the degeneration of blood vessels results not only from degradation of the extracellular matrix molecule or massive leukocyte infiltration, but also from a direct and primary activity of the venom on endothelial cells. Exposure of an endothelial cell line in vitro to L. intermedia venom induce morphological alterations, such as cell retraction and disadhesion to the extracellular matrix. The aim of the present study was to investigate the interaction between the venom toxins and the endothelial cell surface and their possible internalization, in order to illuminate the information about the deleterious effect triggered by venom. After treating endothelial cells with venom toxins, we observed that the venom interacts with cell surface. Venom treatment also can cause a reduction of cell surface glycoconjugates. When cells were permeabilized, it was possible to verify that some venom toxins were internalized by the endothelial cells. The venom internalization involves endocytic vesicles and the venom was detected in the lysosomes. However, no damage to lysosomal integrity was observed, suggesting that the cytotoxic effect evoked by L. intermedia venom on endothelial cells is not mediated by venom internalization.

  11. Bacterial Cell Surface Adsorption of Rare Earth Elements

    Science.gov (United States)

    Jiao, Y.; Park, D.; Reed, D.; Fujita, Y.; Yung, M.; Anderko, A.; Eslamimanesh, A.

    2015-12-01

    Rare earth elements (REE) play a critical role in many emerging clean energy technologies, including high-power magnets, wind turbines, solar panels, hybrid/electric vehicle batteries and lamp phosphors. In order to sustain demand for such technologies given current domestic REE shortages, there is a need to develop new approaches for ore processing/refining and recycling of REE-containing materials. To this end, we have developed a microbially-mediated bioadsorption strategy with application towards enrichment of REE from complex mixtures. Specifically, the bacterium Caulobacter crescentus was genetically engineered to display lanthanide binding tags (LBTs), short peptides that possess high affinity and specificity for rare earth elements, on its cell surface S-layer protein. Under optimal conditions, LBT-displayed cells adsorbed greater than 5-fold more REE than control cells lacking LBTs. Competition binding experiments with a selection of REEs demonstrated that our engineered cells could facilitate separation of light- from heavy- REE. Importantly, binding of REE onto our engineered strains was much more favorable compared to non-REE metals. Finally, REE bound to the cell surface could be stripped off using citrate, providing an effective and non-toxic REE recovery method. Together, this data highlights the potential of our approach for selective REE enrichment from REE containing mixtures.

  12. Effects of beta interferon on human fibroblasts at different population doubling levels. Proliferation, cell volume, thymidine uptake, and DNA synthesis

    OpenAIRE

    1984-01-01

    Cellular aging had no effect on the ability of beta interferon to increase cell volume and population doubling time in 76-109 cells, a line of human skin fibroblasts. However, DNA synthesis in cells at high population doubling levels (PDL 55-70) was inhibited after 72 h of beta interferon treatment (1,000 U/ml) while no inhibition of DNA synthesis was observed in cells at middle population doubling levels (PDL 30-40).

  13. Active screen plasma nitriding enhances cell attachment to polymer surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kaklamani, Georgia, E-mail: g.kaklamani@bham.ac.uk [University of Birmingham, College of Engineering and Physical Sciences, School of Metallurgy and Materials, Edgbaston, Birmingham B15 2TT (United Kingdom); Bowen, James; Mehrban, Nazia [University of Birmingham, College of Engineering and Physical Sciences, School of Chemical Engineering, Edgbaston, Birmingham B15 2TT (United Kingdom); Dong, Hanshan [University of Birmingham, College of Engineering and Physical Sciences, School of Metallurgy and Materials, Edgbaston, Birmingham B15 2TT (United Kingdom); Grover, Liam M. [University of Birmingham, College of Engineering and Physical Sciences, School of Chemical Engineering, Edgbaston, Birmingham B15 2TT (United Kingdom); Stamboulis, Artemis [University of Birmingham, College of Engineering and Physical Sciences, School of Metallurgy and Materials, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2013-05-15

    Active screen plasma nitriding (ASPN) is a well-established technique used for the surface modification of materials, the result of which is often a product with enhanced functional performance. Here we report the modification of the chemical and mechanical properties of ultra-high molecular weight poly(ethylene) (UHMWPE) using 80:20 (v/v) N{sub 2}/H{sub 2} ASPN, followed by growth of 3T3 fibroblasts on the treated and untreated polymer surfaces. ASPN-treated UHMWPE showed extensive fibroblast attachment within 3 h of seeding, whereas fibroblasts did not successfully attach to untreated UHMWPE. Fibroblast-coated surfaces were maintained for up to 28 days, monitoring their metabolic activity and morphology throughout. The chemical properties of the ASPN-treated UHMWPE surface were studied using X-ray photoelectron spectroscopy, revealing the presence of C-N, C=N, and C≡N chemical bonds. The elastic modulus, surface topography, and adhesion properties of the ASPN-treated UHMWPE surface were studied over 28 days during sample storage under ambient conditions and during immersion in two commonly used cell culture media.

  14. Nematic twist cell: Strong chirality induced at the surfaces

    Science.gov (United States)

    Lin, Tzu-Chieh; Nemitz, Ian R.; Pendery, Joel S.; Schubert, Christopher P. J.; Lemieux, Robert P.; Rosenblatt, Charles

    2013-04-01

    A nematic twist cell having a thickness gradient was filled with a mixture containing a configurationally achiral liquid crystal (LC) and chiral dopant. A chiral-based linear electrooptic effect was observed on application of an ac electric field. This "electroclinic effect" varied monotonically with d, changing sign at d =d0 where the chiral dopant exactly compensated the imposed twist. The results indicate that a significant chiral electrooptic effect always exists near the surfaces of a twist cell containing molecules that can be conformationally deracemized. Additionally, this approach can be used to measure the helical twisting power (HTP) of a chiral dopant in a liquid crystal.

  15. Library synthesis, screening, and discovery of modified Zinc(II)-Bis(dipicolylamine) probe for enhanced molecular imaging of cell death.

    Science.gov (United States)

    Plaunt, Adam J; Harmatys, Kara M; Wolter, William R; Suckow, Mark A; Smith, Bradley D

    2014-04-16

    Zinc(II)-bis(dipicolylamine) (Zn-BDPA) coordination complexes selectively target the surfaces of dead and dying mammalian cells, and they have promise as molecular probes for imaging cell death. A necessary step toward eventual clinical imaging applications is the development of next-generation Zn-BDPA complexes with enhanced affinity for the cell death membrane biomarker, phosphatidylserine (PS). This study employed an iterative cycle of library synthesis and screening, using a novel rapid equilibrium dialysis assay, to discover a modified Zn-BDPA structure with high and selective affinity for vesicles containing PS. The lead structure was converted into a deep-red fluorescent probe and its targeting and imaging performance was compared with an unmodified control Zn-BDPA probe. The evaluation process included a series of FRET-based vesicle titration studies, cell microscopy experiments, and rat tumor biodistribution measurements. In all cases, the modified probe exhibited comparatively higher affinity and selectivity for the target membranes of dead and dying cells. The results show that this next-generation deep-red fluorescent Zn-BDPA probe is well suited for preclinical molecular imaging of cell death in cell cultures and animal models. Furthermore, it should be possible to substitute the deep-red fluorophore with alternative reporter groups that enable clinically useful, deep-tissue imaging modalities, such as MRI and nuclear imaging.

  16. Nicotine promotes Streptococcus mutans extracellular polysaccharide synthesis, cell aggregation and overall lactate dehydrogenase activity.

    Science.gov (United States)

    Huang, R; Li, M; Gregory, R L

    2015-08-01

    Several epidemiology studies have reported a positive relationship between smoking and dental caries. Nicotine, an alkaloid component of tobacco, has been demonstrated to stimulate biofilm formation and metabolic activity of Streptococcus mutans, one of the most important pathogens of dental caries. The first aim of the present study was to explore the possible mechanisms leading to increased biofilm by nicotine treatment from three aspects, extracellular polysaccharides (EPS) synthesis, glucosyltransferase (Gtf) synthesis and glucan-binding protein (Gbp) synthesis at the mRNA and protein levels. The second aim was to investigate how nicotine affects S. mutans virulence, particular in lactate dehydrogenase (LDH) activity. Confocal laser scanning microscopy results demonstrated that both biofilm bacterial cell numbers and EPS were increased by nicotine. Gtf and GbpA protein expression of S. mutans planktonic cells were upregulated while GbpB protein expression of biofilm cells were downregulated by nicotine. The mRNA expression trends of those genes were mostly consistent with results on protein level but not statistically significant, and gtfD and gbpD of biofilm cells were inhibited. Nicotine was not directly involved in S. mutans LDH activity. However, since it increases the total number of bacterial cells in biofilm, the overall LDH activity of S. mutans biofilm is increased. In conclusion, nicotine stimulates S. mutans planktonic cell Gtf and Gbp expression. This leads to more planktonic cells attaching to the dental biofilm. Increased cell numbers within biofilm results in higher overall LDH activity. This contributes to caries development in smokers.

  17. Identifying intracellular sites of eicosanoid lipid mediator synthesis with EicosaCell assays.

    Science.gov (United States)

    Bandeira-Melo, Christianne; Weller, Peter F; Bozza, Patricia T

    2011-01-01

    Eicosanoids, arachidonic acid-derived signaling lipid mediators, are newly formed and nonstorable molecules that have important roles in physiological and pathological processes. EicosaCell is a microscopic assay that enables the intracellular detection and localization of eicosanoid lipid mediator-synthesizing compartments by means of a strategy to covalently cross-link and immobilize eicosanoids at their sites of synthesis followed by immunofluorescent-based localization of the targeted eicosanoid. EicosaCell is a versatile assay which allows analyses of different types of cell preparations, such as cells isolated from humans or harvested cells from in vivo models of inflammation and adherent or suspension cells stimulated in vitro. EicosaCell assays have been successfully used to identify different intracellular compartments of synthesis of prostaglandins and leukotrienes upon cellular activation. This is of particular interest given that over the past decade intracellular compartmentalization of eicosanoid-synthetic machinery has emerged both as a key component in the regulation of eicosanoid synthesis and in delineating functional intracellular and extracellular actions of eicosanoids. This review covers basics of EicosaCell assay including its selection of reagents, immunodetection design as well as some troubleshooting recommendations.

  18. Vaccines based on the cell surface carbohydrates of pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Jones Christopher

    2005-01-01

    Full Text Available Glycoconjugate vaccines, in which a cell surface carbohydrate from a micro-organism is covalently attached to an appropriate carrier protein are proving to be the most effective means to generate protective immune responses to prevent a wide range of diseases. The technology appears to be generic and applicable to a wide range of pathogens, as long as antibodies against surface carbohydrates help protect against infection. Three such vaccines, against Haemophilus influenzae type b, Neisseria meningitidis Group C and seven serotypes of Streptococcus pneumoniae, have already been licensed and many others are in development. This article discusses the rationale for the development and use of glycoconjugate vaccines, the mechanisms by which they elicit T cell-dependent immune responses and the implications of this for vaccine development, the role of physicochemical methods in the characterisation and quality control of these vaccines, and the novel products which are under development.

  19. Gemini alkyldeoxy-D-glucitolammonium salts as modern surfactants and microbiocides: synthesis, antimicrobial and surface activity, biodegradation.

    Science.gov (United States)

    Brycki, Bogumił; Szulc, Adrianna

    2014-01-01

    Dimeric quaternary alkylammonium salts possess a favourable surface and antimicrobial activity. In this paper we describe synthesis, spectroscopic analysis, surface and antimicrobial activity as well as biodegradability of polymethylene-α,ω-bis(N,N-dialkyl-N-deoxy-D-glucitolammonium iodides), a new group of dimeric quaternary ammonium salts. This new group of gemini surfactants can be produced from chemicals which come from renewable sources. The structure of products has been determined by the FTIR and (1)H and (13)C NMR spectroscopy. The biodegradability, surface activity and antimicrobial efficacy against Escherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus niger and Penicillium chrysogenum were determined. The influence of the number of alkyl chains and their lengths on surface and antimicrobial properties has been shown. In general, dimeric quaternary alkyldeoxy-D-glucitolammonium salts with long alkyl substituents show favourable surface properties and an excellent antimicrobial activity.

  20. Gemini alkyldeoxy-D-glucitolammonium salts as modern surfactants and microbiocides: synthesis, antimicrobial and surface activity, biodegradation.

    Directory of Open Access Journals (Sweden)

    Bogumił Brycki

    Full Text Available Dimeric quaternary alkylammonium salts possess a favourable surface and antimicrobial activity. In this paper we describe synthesis, spectroscopic analysis, surface and antimicrobial activity as well as biodegradability of polymethylene-α,ω-bis(N,N-dialkyl-N-deoxy-D-glucitolammonium iodides, a new group of dimeric quaternary ammonium salts. This new group of gemini surfactants can be produced from chemicals which come from renewable sources. The structure of products has been determined by the FTIR and (1H and (13C NMR spectroscopy. The biodegradability, surface activity and antimicrobial efficacy against Escherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus niger and Penicillium chrysogenum were determined. The influence of the number of alkyl chains and their lengths on surface and antimicrobial properties has been shown. In general, dimeric quaternary alkyldeoxy-D-glucitolammonium salts with long alkyl substituents show favourable surface properties and an excellent antimicrobial activity.

  1. ER-mitochondria contacts couple mtDNA synthesis with mitochondrial division in human cells.

    Science.gov (United States)

    Lewis, Samantha C; Uchiyama, Lauren F; Nunnari, Jodi

    2016-07-15

    Mitochondrial DNA (mtDNA) encodes RNAs and proteins critical for cell function. In human cells, hundreds to thousands of mtDNA copies are replicated asynchronously, packaged into protein-DNA nucleoids, and distributed within a dynamic mitochondrial network. The mechanisms that govern how nucleoids are chosen for replication and distribution are not understood. Mitochondrial distribution depends on division, which occurs at endoplasmic reticulum (ER)-mitochondria contact sites. These sites were spatially linked to a subset of nucleoids selectively marked by mtDNA polymerase and engaged in mtDNA synthesis--events that occurred upstream of mitochondrial constriction and division machine assembly. Our data suggest that ER tubules proximal to nucleoids are necessary but not sufficient for mtDNA synthesis. Thus, ER-mitochondria contacts coordinate licensing of mtDNA synthesis with division to distribute newly replicated nucleoids to daughter mitochondria.

  2. Synthesis and self-assembly of thio derivatives of calix[4]arene on noble metal surfaces.

    Science.gov (United States)

    Genorio, Bostjan; He, Tao; Meden, Anton; Polanc, Slovenko; Jamnik, Janko; Tour, James M

    2008-10-21

    Self-assembled monolayers (SAMs) provide a simple route to functionalize electrode surfaces with organic molecules. Herein we use cavity-containing derivatives of calix[4]arenes in SAMs. Bound to noble metal surface, the assembled molecules are candidates to serve as molecular sieves for H 2 molecules and H (+) ions, which could have relevance for fuel cell applications. Tetra- O-alkylated calix[4]arenes with thiolacetate and thiolamide wide-rim anchoring groups in cone and partial-cone conformations were designed, synthesized and self-assembled onto Au, Pt, and Pd surfaces. The resulting SAMs were systematically examined. Single crystal X-ray diffraction of 5,11,17,23-tetrakis(thioacetyl)-25,26,27,28-tetra- i-propoxycalix[4]arene confirmed the cone conformation and revealed the cavity dimensions of the SAMs that were formed by immersing noble metal substrates (Au, Pt and Pd deposited on Si-wafers) in solutions of calix[4]arenes. Surface characterization techniques including ellipsometry, cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) were used, indicating that the metal surface is terminated with a monomolecular layer. Experimental thicknesses obtained from the ellipsometry are consistent with the calculated values. CV results showed 50 to 80% physical passivation against the Fe(CN) 6 (3-/4-) couple, implying an overall relatively low concentration of defects and pinholes in the films. The binding energies of the S2p core level in the XPS were consistent with the literature values and revealed that up to 3.2 out of four anchoring groups were bonded to the noble metal surface.

  3. Recent Insights into Cell Surface Heparan Sulphate Proteoglycans and Cancer

    DEFF Research Database (Denmark)

    Couchman, John R; Multhaupt, Hinke; Sanderson, Ralph D

    2016-01-01

    A small group of cell surface receptors are proteoglycans, possessing a core protein with one or more covalently attached glycosaminoglycan chains. They are virtually ubiquitous and their chains are major sites at which protein ligands of many types interact. These proteoglycans can signal and re...... or fragmented proteoglycans into exosomes that can be paracrine effectors or biomarkers, and lateral interactions between some proteoglycans and calcium channels that impact the actin cytoskeleton....

  4. Live Cell Surface Labeling with Fluorescent Ag Nanocluster Conjugates†

    OpenAIRE

    Yu, Junhua; Choi, Sungmoon; Richards, Chris I.; Antoku, Yasuko; Dickson, Robert M

    2008-01-01

    DNA-encapsulated silver clusters are readily conjugated to proteins and serve as alternatives to organic dyes and semiconductor quantum dots. Stable and bright on the bulk and single molecule levels, Ag nanocluster fluorescence is readily observed when staining live cell surfaces. Being significantly brighter and more photostable than organics and much smaller than quantum dots with a single point of attachment, these nanomaterials offer promising new approaches for bulk and single molecule b...

  5. A new synthesis route to high surface area sol gel bioactive glass through alcohol washing

    Science.gov (United States)

    M. Mukundan, Lakshmi; Nirmal, Remya; Vaikkath, Dhanesh; Nair, Prabha D.

    2013-01-01

    Bioactive glass is one of the widely used bone repair material due to its unique properties like osteoconductivity, osteoinductivity and biodegradability. In this study bioactive glass is prepared by the sol gel process and stabilized by a novel method that involves a solvent instead of the conventional calcinations process. This study represents the first attempt to use this method for the stabilization of bioactive glass. The bioactive glass stabilized by this ethanol washing process was characterized for its physicochemical and biomimetic property in comparison with similar composition of calcined bioactive glass. The compositional similarity of the two stabilized glass powders was confirmed by spectroscopic and thermogravimetric analysis. Other physicochemical characterizations together with the cell culture studies with L929 fibroblast cells and bone marrow mesenchymal stem cells proved that the stabilization was achieved with the retention of its inherent bioactive potential. However an increase in the surface area of the glass powder was obtained as a result of this ethanol washing process and this add up to the success of the study. Hence the present study exhibits a promising route for high surface area bioactive glass for increasing biomimicity. PMID:23512012

  6. Synthesis and characterization of cobaltite nanotubes for solid-oxide fuel cell cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Napolitano, F; Baque, L; Troiani, H; Granada, M; Serquis, A, E-mail: aserquis@cab.cnea.gov.a [Instituto Balseiro-Centro Atomico Bariloche and CONICET, San Carlos de Bariloche (Argentina)

    2009-05-01

    La{sub 1-x}Sr{sub x}Co{sub 1-y}FeyO{sub 3-d}elta oxides are good candidates for solid oxide fuel cell (SOFC) cathodes because these materials present high ionic and electronic conductivity, and compatibility with Cerium Gadolinium Oxide (CGO) electrolytes allowing a lower operation temperature. In this work, we report the synthesis of La{sub 0.4}Sr{sub 0.6}Co{sub 0.8}Fe{sub 0.2}O{sub 3-d}elta (LSCF) nanotubes prepared by a porous polycarbonate membrane approach, obtaining different microstructures depending on sintering conditions. The structure and morphology of the nanotubes and deposited films were characterized by X-ray diffraction, transmission and scanning microscopy. Finally, we obtained nanostructured films of vertically aligned LSCF tubes deposited over the whole surface of CGO pellets with diameter up to 2.5cm in a direct and single step process.

  7. Surface recombination analysis in silicon-heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Barrio, R.; Gandia, J.J.; Carabe, J.; Gonzalez, N.; Torres, I. [CIEMAT, Madrid (Spain); Munoz, D.; Voz, C. [Universitat Politecnica de Catalunya, Barcelona (Spain)

    2010-02-15

    The origin of this work is the understanding of the correlation observed between efficiency and emitter-deposition temperature in single silicon-heterojunction solar cells prepared by depositing an n-doped hydrogenated-amorphous-silicon thin film onto a p-type crystalline-silicon wafer. In order to interpret these results, surface-recombination velocities have been determined by two methods, i.e. by fitting the current-voltage characteristics to a theoretical model and by means of the Quasi-Steady-State Photoconductance Technique (QSSPC). In addition, effective diffusion lengths have been estimated from internal quantum efficiencies. The analysis of these data has led to conclude that the performance of the cells studied is limited by back-surface recombination rather than by front-heterojunction quality. A 12%-efficient cell has been prepared by combining optimum emitter-deposition conditions with back-surface-field (BSF) formation by vacuum annealing of the back aluminium contact. This result has been achieved without using any transparent conductive oxide. (author)

  8. Structure of a bacterial cell surface decaheme electron conduit.

    Science.gov (United States)

    Clarke, Thomas A; Edwards, Marcus J; Gates, Andrew J; Hall, Andrea; White, Gaye F; Bradley, Justin; Reardon, Catherine L; Shi, Liang; Beliaev, Alexander S; Marshall, Matthew J; Wang, Zheming; Watmough, Nicholas J; Fredrickson, James K; Zachara, John M; Butt, Julea N; Richardson, David J

    2011-06-07

    Some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. In Shewanella oneidensis this involves decaheme cytochromes that are located on the bacterial cell surface at the termini of trans-outer-membrane electron transfer conduits. The cell surface cytochromes can potentially play multiple roles in mediating electron transfer directly to insoluble electron sinks, catalyzing electron exchange with flavin electron shuttles or participating in extracellular intercytochrome electron exchange along "nanowire" appendages. We present a 3.2-Å crystal structure of one of these decaheme cytochromes, MtrF, that allows the spatial organization of the 10 hemes to be visualized for the first time. The hemes are organized across four domains in a unique crossed conformation, in which a staggered 65-Å octaheme chain transects the length of the protein and is bisected by a planar 45-Å tetraheme chain that connects two extended Greek key split β-barrel domains. The structure provides molecular insight into how reduction of insoluble substrate (e.g., minerals), soluble substrates (e.g., flavins), and cytochrome redox partners might be possible in tandem at different termini of a trifurcated electron transport chain on the cell surface.

  9. Simulation and Optimization of Silicon Solar Cell Back Surface Field

    Directory of Open Access Journals (Sweden)

    Souad TOBBECHE

    2015-11-01

    Full Text Available In this paper, TCAD Silvaco (Technology Computer Aided Design software has been used to study the Back Surface Field (BSF effect of a p+ silicon layer for a n+pp+ silicon solar cell. To study this effect, the J-V characteristics and the external quantum efficiency (EQE are simulated under AM 1.5 illumination for two types of cells. The first solar cell is without BSF (n+p structure while the second one is with BSF (n+pp+ structure. The creation of the BSF on the rear face of the cell results in efficiency h of up to 16.06% with a short-circuit current density Jsc = 30.54 mA/cm2, an open-circuit voltage Voc = 0.631 V, a fill factor FF = 0.832 and a clear improvement of the spectral response obtained in the long wavelengths range. An electric field and a barrier of potential are created by the BSF and located at the junction p+/p with a maximum of 5800 V/cm and 0.15 V, respectively. The optimization of the BSF layer shows that the cell performance improves with the p+ thickness between 0.35 – 0.39 µm, the p+ doping dose is about 2 × 1014 cm-2, the maximum efficiency up to 16.19 %. The cell efficiency is more sensitive to the value of the back surface recombination velocity above a value of 103 cm/s in n+p than n+pp+ solar cell.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9565

  10. Association Mapping of Cell Wall Synthesis Regulatory Genes and Cell Wall Quality in Switchgrass

    Energy Technology Data Exchange (ETDEWEB)

    Bartley, Laura [Univ. of Oklahoma, Norman, OK (United States). Dept. of Microbiology and Plant Biology; Wu, Y. [Oklahoma State Univ., Stillwater, OK (United States); Zhu, L. [Oklahoma State Univ., Stillwater, OK (United States); Brummer, E. C. [Noble Foundation, Ardmore, OK (United States); Saha, M. [Noble Foundation, Ardmore, OK (United States)

    2016-05-31

    markers might be used to select switchgrass genotypes with improved composition in breeding programs for biofuel and forage production. Because the SSAC continues to be characterized by collaborators in the bioenergy community, the data generated will be used to identify additional markers in higher resolution genotyping data to approach identifying the genes and alleles that cause natural variation in switchgrass cell wall quality. For example, these markers can be surveyed in the 2100-member Oklahoma Southern and Northern Lowland switchgrass collections that this project also characterized. An orthogonal approach to biodiversity studies, using comparative functional genomics permits systematic querying of how much regulatory information is likely to be transferable from dicots to grasses and use of accumulated functional genomics resources for better-characterized grass species, such as rice, itself a biomass source in global agriculture and in certain regions. The project generated and tested a number of specific hypotheses regarding cell wall transcription factors and enzymes of grasses. To aid identification of cell wall regulators, the project assembled a novel, highdepth and -quality gene association network using a general linearized model scoring system to combine rice gene network data. Using known or putative orthologs of Arabidopsis cell wall biosynthesis genes and regulators, the project pulled from this network a cell wall sub-network that includes 96 transcription factors. Reverse genetics of a co-ortholog of the Arabidopsis MYB61 transcription factor in rice revealed that this regulatory node has evolved the ability to regulate grass-specific cell wall synthesis enzymes. A transcription factor with such activity has not been previously characterized to our knowledge, representing a major conclusion of this work. Changes in gene expression in a protoplast-based assay demonstrated positive or negative roles in cell wall regulation for eleven other

  11. No changes in heme synthesis in human Friedreich´s ataxia erythroid progenitor cells.

    Science.gov (United States)

    Steinkellner, Hannes; Singh, Himanshu Narayan; Muckenthaler, Martina U; Goldenberg, Hans; Moganty, Rajeswari R; Scheiber-Mojdehkar, Barbara; Sturm, Brigitte

    2017-07-20

    Friedreich's ataxia (FRDA) is a neurodegenerative disease caused by reduced expression of the protein frataxin. Frataxin is thought to play a role in iron-sulfur cluster biogenesis and heme synthesis. In this study, we used erythroid progenitor stem cells obtained from FRDA patients and healthy donors to investigate the putative role, if any, of frataxin deficiency in heme synthesis. We used electrochemiluminescence and qRT-PCR for frataxin protein and mRNA quantification. We used atomic absorption spectrophotometry for iron levels and a photometric assay for hemoglobin levels. Protoporphyrin IX and Ferrochelatase were analyzed using auto-fluorescence. An "IronChip" microarray analysis followed by a protein-protein interaction analysis was performed. FRDA patient cells showed no significant changes in iron levels, hemoglobin synthesis, protoporphyrin IX levels, and ferrochelatase activity. Microarray analysis presented 11 genes that were significantly changed in all patients compared to controls. The genes are especially involved in oxidative stress, iron homeostasis and angiogenesis. The mystery about the involvement of frataxin on iron metabolism raises the question why frataxin deficiency in primary FRDA cells did not lead to changes in biochemical parameters of heme synthesis. It seems that alternative pathways can circumvent the impact of frataxin deficiency on heme synthesis. We show for the first time in primary FRDA patient cells that reduced frataxin levels are still sufficient for heme synthesis and possibly other mechanisms can overcome reduced frataxin levels in this process. Our data strongly support the fact that so far no anemia in FRDA patients was reported. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. The Mesenchymal Precursor Cell Marker Antibody STRO-1 Binds to Cell Surface Heat Shock Cognate 70.

    Science.gov (United States)

    Fitter, Stephen; Gronthos, Stan; Ooi, Soo Siang; Zannettino, Andrew C W

    2016-12-27

    Since its discovery more than 25 years ago, the STRO-1 antibody has played a fundamental role in defining the hierarchical nature of mesenchymal precursor cells (MPC) and their progeny. STRO-1 antibody binding remains a hallmark of immature pluripotent MPC. Despite the significance of STRO-1 in the MPC field, the identity of the antigen has remained elusive. Using a combination of two-dimensional gel electrophoresis, coupled with Western blotting and Tandem mass spectroscopy, we have identified the STRO-1 antigen as heat shock cognate 70 (HSC70;HSPA8). STRO-1 binds to immune-precipitated HSC70 and siRNA-mediated knock down of HSPA8 reduced STRO-1 binding. STRO-1 surface binding does not correlate with HSC70 expression and sequestration of cholesterol reduces STRO-1 surface binding, suggesting that the plasma membrane lipid composition may be an important determinant in the presentation of HSC70 on the cell surface. HSC70 is present on the surface of STRO-1(+) but not STRO-1(-) cell lines as assessed by cell surface biotinylation and recombinant HSC70 blocks STRO-1 binding to the cell surface. The STRO-1 epitope on HSC70 was mapped to the ATPase domain using a series of deletion mutants in combination with peptide arrays. Deletion of the first four amino acids of the consensus epitope negated STRO-1 binding. Notably, in addition to HSC70, STRO-1 cross-reacts with heat shock protein 70 (HSP70), however all the clonogenic cell activity is restricted to the STRO-1(BRIGHT) /HSP70(-) fraction. These results provide important insight into the properties that define multipotent MPC and provide the impetus to explore the role of cell surface HSC70 in MPC biology. Stem Cells 2016.

  13. A Simple Hydrophilic Treatment of SU-8 Surfaces for Cell Culturing and Cell Patterning

    DEFF Research Database (Denmark)

    Wang, Zhenyu; Stangegaard, Michael; Dufva, Hans Martin

    2005-01-01

    SU-8, an epoxy-based photoresist, widely used in constitution different mTAS systems, is incompatible with mammalian cell adhesion and culture in its native form. Here, we demonstrate a simple, cheap and robust two-step method to render a SU-8 surface hydrophilic and compatible with cell culture...

  14. Cell surface heparan sulfate proteoglycans control adhesion and invasion of breast carcinoma cells

    DEFF Research Database (Denmark)

    Lim, Hooi Ching; Multhaupt, Hinke A. B.; Couchman, John R.

    2015-01-01

    phenotype of mammary carcinoma cells. Finally, both syndecan-2 and caveolin-2 were upregulated in tissue arrays from breast cancer patients compared to normal mammary tissue. Moreover their expression levels were correlated in triple negative breast cancers. Conclusion: Cell surface proteoglycans, notably...

  15. A Simple Hydrophilic Treatment of SU-8 Surfaces for Cell Culturing and Cell Patterning

    DEFF Research Database (Denmark)

    Wang, Zhenyu; Stangegaard, Michael; Dufva, Hans Martin;

    2005-01-01

    SU-8, an epoxy-based photoresist, widely used in constitution different mTAS systems, is incompatible with mammalian cell adhesion and culture in its native form. Here, we demonstrate a simple, cheap and robust two-step method to render a SU-8 surface hydrophilic and compatible with cell culture...

  16. Aminolysis of polyethylene terephthalate surface along with in situ synthesis and stabilizing ZnO nanoparticles using triethanolamine optimized with response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Poortavasoly, Hajar; Montazer, Majid, E-mail: tex5mm@aut.ac.ir; Harifi, Tina

    2016-01-01

    This research concerned the simultaneous polyester surface modification and synthesis of zinc oxide nano-reactors to develop durable photo-bio-active fabric with variable hydrophobicity/hydrophilicity under sunlight. For this purpose, triethanolamine (TEA) was applied as a stabilizer and pH adjusting chemical for the aminolysis of polyester surface and enhancing the surface reactivity along with synthesis and deposition of ZnO nanoparticles on the fabric. Therefore, TEA played a crucial role in providing the alkaline condition for the preparation of zinc oxide nanoparticles and acting as stabilizer controlling the size of the prepared nanoparticles. The stain–photodegradability regarded as self-cleaning efficiency, wettability and weight change under the process was optimized based on zinc acetate and TEA concentrations, using central composite design (CCD). Findings also suggested the potential of the prepared fabric in inhibiting Staphylococcus aureus and Escherichia coli bacteria growth with greater than 99.99% antibacterial efficiency. Besides, the proposed treatment had no detrimental effect on tensile strength and hand feeling of the polyester fabric. - Highlights: • Durable photo-bio-active polyester with variable hydrophobicity/hydrophilicity • Simultaneous polyester surface aminolysis and ZnO ball-like nanoparticle production • Multi-role of TEA for polyester aminolysis and nanoparticle formation • Optimization of photoactivity and wettability by central composite design.

  17. Efficient synthesis of triarylamine-based dyes for p-type dye-sensitized solar cells

    Science.gov (United States)

    Wild, Martin; Griebel, Jan; Hajduk, Anna; Friedrich, Dirk; Stark, Annegret; Abel, Bernd; Siefermann, Katrin R.

    2016-05-01

    The class of triarylamine-based dyes has proven great potential as efficient light absorbers in inverse (p-type) dye sensitized solar cells (DSSCs). However, detailed investigation and further improvement of p-type DSSCs is strongly hindered by the fact that available synthesis routes of triarylamine-based dyes are inefficient and particularly demanding with regard to time and costs. Here, we report on an efficient synthesis strategy for triarylamine-based dyes for p-type DSSCs. A protocol for the synthesis of the dye-precursor (4-(bis(4-bromophenyl)amino)benzoic acid) is presented along with its X-ray crystal structure. The dye precursor is obtained from the commercially available 4(diphenylamino)benzaldehyde in a yield of 87% and serves as a starting point for the synthesis of various triarylamine-based dyes. Starting from the precursor we further describe a synthesis protocol for the dye 4-{bis[4‧-(2,2-dicyanovinyl)-[1,1‧-biphenyl]-4-yl]amino}benzoic acid (also known as dye P4) in a yield of 74%. All synthesis steps are characterized by high yields and high purities without the need for laborious purification steps and thus fulfill essential requirements for scale-up.

  18. Cell surface alpha 2,6 sialylation affects adhesion of breast carcinoma cells.

    Science.gov (United States)

    Lin, Shaoqiang; Kemmner, Wolfgang; Grigull, Sabine; Schlag, Peter M

    2002-05-15

    Tumor-associated alterations of cell surface glycosylation play a crucial role in the adhesion and metastasis of carcinoma cells. The aim of this study was to examine the effect of alpha 2,6-sialylation on the adhesion properties of breast carcinoma cells. To this end mammary carcinoma cells, MDA-MB-435, were sense-transfected with sialyltransferase ST6Gal-I cDNA or antisense-transfected with a part of the ST6Gal-I sequence. Sense transfectants showed an enhanced ST6Gal-I mRNA expression and enzyme activity and an increased binding of the lectin Sambucus nigra agglutinin (SNA), specific for alpha 2,6-linked sialic acid. Transfection with ST6Gal-I in the antisense direction resulted in less enzyme activity and SNA reactivity. A sense-transfected clone carrying increased amounts of alpha 2,6-linked sialic acid adhered preferentially to collagen IV and showed reduced cell-cell adhesion and enhanced invasion capacity. In contrast, antisense transfection led to less collagen IV adhesion but enhanced homotypic cell-cell adhesion. In another approach, inhibition of ST6Gal-I enzyme activity by application of soluble antisense-oligodeoxynucleotides was studied. Antisense treatment resulted in reduced ST6 mRNA expression and cell surface 2,6-sialylation and significantly decreased collagen IV adhesion. Our results suggest that cell surface alpha 2,6-sialylation contributes to cell-cell and cell-extracellular matrix adhesion of tumor cells. Inhibition of sialytransferase ST6Gal-I by antisense-oligodeoxynucleotides might be a way to reduce the metastatic capacity of carcinoma cells.

  19. Helium-neon laser irradiation enhances DNA synthesis in a human neuroblastoma cell line

    Science.gov (United States)

    Condon, Michael R.; Gump, Frank; Wu, Wen-hsien

    1993-07-01

    To gain further insight into the mechanism of cell photostimulation by laser light ((lambda) equals 632.8 nm), DNA synthesis was measured in the human neuroblastoma cell line BE(2)-C. Cells were irradiated at high density to establish the characteristics of cellular energy into S- phase in response to laser stimulation. BE(2)-C cells after release from a quiescent, growth arrested state exhibited increased incorporation of isotope 12 hours after replating at subconfluent density in the presence of 2.5% fetal bovine serum (FBS) and [3H] thymidine. In contrast, cells replated under the same conditions, but stimulated with 15% FBS exhibited a time lag of approximately 16 hours in apparent DNA synthesis. These results were not corroborated by flow cytometry. Laser irradiation did not affect the fraction of cells entering S-phase. It therefore appears that the stimulatory effect of He-Ne laser irradiation on BE(2)-C cells is to enhance DNA synthesis while not altering the G1-S transition rate.

  20. Superparamagnetic iron oxide nanoparticles (SPIONs): from synthesis to in vivo studies--a summary of the synthesis, characterization, in vitro, and in vivo investigations of SPIONs with particular focus on surface and colloidal properties.

    Science.gov (United States)

    Petri-Fink, Alke; Hofmann, Heinrich

    2007-12-01

    In this work, we present a short summary of the synthesis and characterization of superparamagnetic iron oxide nanoparticles and their behavior in vitro and in vivo. Therefore, we have used various characterization techniques to deduce the physical particle size as well as magnetic properties. It is shown that the particle properties were significantly improved by a thermochemical treatment and dialysis, obtaining weakly interacting particles with a clear blocking temperature. We also present the interaction of polyvinyl alcohol and vinyl alcohol/vinyl amine copolymer-coated SPIONs with HELA cells. It is shown that the uptake increased significantly in the presence of a magnetic field and that surface functional groups had an impact on particle uptake and metabolic activity. Furthermore, the influences of the varied parameters (polymer type and therefore surface charge, cell medium, and serum) on the agglomeration rate and the cell uptake are presented and discussed. Finally, we briefly describe the intraarticular application of SPIONs in sheep, their uptake by synovial membrane, and their systemic distribution and elimination.

  1. Interaction of Human Tumor Viruses with Host Cell Surface Receptors and Cell Entry

    Directory of Open Access Journals (Sweden)

    Georgia Schäfer

    2015-05-01

    Full Text Available Currently, seven viruses, namely Epstein-Barr virus (EBV, Kaposi’s sarcoma-associated herpes virus (KSHV, high-risk human papillomaviruses (HPVs, Merkel cell polyomavirus (MCPyV, hepatitis B virus (HBV, hepatitis C virus (HCV and human T cell lymphotropic virus type 1 (HTLV-1, have been described to be consistently associated with different types of human cancer. These oncogenic viruses belong to distinct viral families, display diverse cell tropism and cause different malignancies. A key to their pathogenicity is attachment to the host cell and entry in order to replicate and complete their life cycle. Interaction with the host cell during viral entry is characterized by a sequence of events, involving viral envelope and/or capsid molecules as well as cellular entry factors that are critical in target cell recognition, thereby determining cell tropism. Most oncogenic viruses initially attach to cell surface heparan sulfate proteoglycans, followed by conformational change and transfer of the viral particle to secondary high-affinity cell- and virus-specific receptors. This review summarizes the current knowledge of the host cell surface factors and molecular mechanisms underlying oncogenic virus binding and uptake by their cognate host cell(s with the aim to provide a concise overview of potential target molecules for prevention and/or treatment of oncogenic virus infection.

  2. A New Method of Solving Kernels in Algebraic Decomposition for the Synthesis of Logic Cell Array

    Institute of Scientific and Technical Information of China (English)

    马光胜; 张忠伟; 等

    1995-01-01

    In this paper,an improvement has been made on the algorithm of solving the kernels of new functions which are generated after a common divisor appearing in the original functions is replaced by a new intermediate variable.And an efficient method based on kernel heritage is presented.This method has been successfully used in synthesis of LCA (Logic Cell Array).

  3. Problem-Solving Test: RNA and Protein Synthesis in Bacteriophage-Infected "E. coli" Cells

    Science.gov (United States)

    Szeberenyi, Jozsef

    2008-01-01

    The classic experiment presented in this problem-solving test was designed to identify the template molecules of translation by analyzing the synthesis of phage proteins in "Escherichia coli" cells infected with bacteriophage T4. The work described in this test led to one of the most seminal discoveries of early molecular biology: it dealt a…

  4. The membrane steps of bacterial cell wall synthesis as antibiotic targets

    NARCIS (Netherlands)

    Liu, Yao; Breukink, Eefjan

    2016-01-01

    Peptidoglycan is the major component of the cell envelope of virtually all bacteria. It has structural roles and acts as a selective sieve for molecules from the outer environment. Peptidoglycan synthesis is therefore one of the most important biogenesis pathways in bacteria and has been studied ext

  5. Design, Synthesis, and Inhibitory Activity of Potent, Photoswitchable Mast Cell Activation Inhibitors

    NARCIS (Netherlands)

    Velema, Willem A.; van der Toorn, Marco; Szymanski, Wiktor; Feringa, Ben L.

    2013-01-01

    Allergic reactions affect millions of people worldwide. The need for new and effective antiallergic agents is evident, and insight into the underlying mechanisms that lead to allergic events is necessary. Herein, we report the design, synthesis, and activity of photoswitchable mast cell activation

  6. Interactions between membrane-bound cellulose synthases involved in the synthesis of the secondary cell wall

    NARCIS (Netherlands)

    Timmers, J.F.P.; Vernhettes, S.; Desprez, T.; Vincken, J.P.; Visser, R.G.F.; Trindade, L.M.

    2009-01-01

    It has not yet been reported how the secondary CESA (cellulose synthase) proteins are organized in the rosette structure. A membrane-based yeast two-hybrid (MbYTH) approach was used to analyze the interactions between the CESA proteins involved in secondary cell wall synthesis of Arabidopsis and the

  7. Organometallic nucleoside analogues with ferrocenyl linker groups: synthesis and cancer cell line studies.

    Science.gov (United States)

    Nguyen, Huy V; Sallustrau, Antoine; Balzarini, Jan; Bedford, Matthew R; Eden, John C; Georgousi, Niki; Hodges, Nikolas J; Kedge, Jonathan; Mehellou, Youcef; Tselepis, Chris; Tucker, James H R

    2014-07-10

    Examples of organometallic compounds as nucleoside analogues are rare within the field of medicinal bioorganometallic chemistry. We report on the synthesis and properties of two chiral ferrocene derivatives containing a nucleobase and a hydroxyalkyl group. These so-called ferronucleosides show promising anticancer activity, with cytostatic studies on five different cancer cell lines indicating that both functional groups are required for optimal activity.

  8. Recycling Spent Primary Cells for the Synthesis of Spinel ZnMn 2 O ...

    African Journals Online (AJOL)

    Recycling Spent Primary Cells for the Synthesis of Spinel ZnMn 2 O 4 using Waste Polypropylene as Reductant in a Microwave Oven. ... The residual casing was dismantled and scrap iron, plastic and paper separated. The removed mixture ...

  9. Palmitic acid and linoleic acid metabolism in Caco-2 cells: Different triglyceride synthesis and lipoprotein secretion

    NARCIS (Netherlands)

    van Greevenbroek, M.M.J.; Voorhout, W.F.; Erkelens, D.W.; van Meer, G.; de Bruin, T.W.A.

    1995-01-01

    Polarized monolayers of intestinal Caco-2 cells were used to study the effects of saturated palmitic acid (16:0) and polyunsaturated linoleic acid (18:2) on triglyceride synthesis and lipoprotein secretion. Monolayers were incubated for 24 h, at the apical or lumenal side, with palmitic acid (16:0)

  10. Problem-Solving Test: RNA and Protein Synthesis in Bacteriophage-Infected "E. coli" Cells

    Science.gov (United States)

    Szeberenyi, Jozsef

    2008-01-01

    The classic experiment presented in this problem-solving test was designed to identify the template molecules of translation by analyzing the synthesis of phage proteins in "Escherichia coli" cells infected with bacteriophage T4. The work described in this test led to one of the most seminal discoveries of early molecular biology: it dealt a…

  11. Design, Synthesis, and Inhibitory Activity of Potent, Photoswitchable Mast Cell Activation Inhibitors

    NARCIS (Netherlands)

    Velema, Willem A.; van der Toorn, Marco; Szymanski, Wiktor; Feringa, Ben L.

    2013-01-01

    Allergic reactions affect millions of people worldwide. The need for new and effective antiallergic agents is evident, and insight into the underlying mechanisms that lead to allergic events is necessary. Herein, we report the design, synthesis, and activity of photoswitchable mast cell activation i

  12. Knockdown of XBP1 by RNAi in Mouse Granulosa Cells Promotes Apoptosis, Inhibits Cell Cycle, and Decreases Estradiol Synthesis

    Directory of Open Access Journals (Sweden)

    Nan Wang

    2017-05-01

    Full Text Available Granulosa cells are crucial for follicular growth, development, and follicular atresia. X-box binding protein 1 (XBP1, a basic region-leucine zipper protein, is widely involved in cell differentiation, proliferation, apoptosis, cellular stress response, and other signaling pathways. In this study, RNA interference, flow cytometry, western blot, real-time PCR, Cell Counting Kit (CCK8, and ELISA were used to investigate the effect of XBP1 on steroidogenesis, apoptosis, cell cycle, and proliferation of mouse granulosa cells. ELISA analysis showed that XBP1 depletion significantly decreased the concentrations of estradiol (E2. Additionally, the expression of estrogen synthesis enzyme Cyp19a1 was sharply downregulated. Moreover, flow cytometry showed that knockdown of XBP1 increased the apoptosis rate and arrests the cell cycle in S-phase in granulosa cells (GCs. Further study confirmed these results. The expression of CCAAT-enhancer-binding protein homologous protein (CHOP, cysteinyl aspartate specific proteases-3 (caspase-3, cleaved caspase-3, and Cyclin E was upregulated, while that of Bcl-2, Cyclin A1, and Cyclin B1 was downregulated. Simultaneously, CCK8 analysis indicated that XBP1 disruption inhibited cell proliferation. In addition, XBP1 knockdown also alters the expression of Has2 and Ptgs2, two essential genes for folliculogenesis. Collectively, these data reveal a novel critical role of XBP1 in folliculogenesis by regulating the cell cycle, apoptosis, and steroid synthesis of mouse granulosa cells.

  13. Paired Expression Analysis of Tumor Cell Surface Antigens

    Directory of Open Access Journals (Sweden)

    Rimas J. Orentas

    2017-08-01

    Full Text Available Adoptive immunotherapy with antibody-based therapy or with T cells transduced to express chimeric antigen receptors (CARs is useful to the extent that the cell surface membrane protein being targeted is not expressed on normal tissues. The most successful CAR-based (anti-CD19 or antibody-based therapy (anti-CD20 in hematologic malignancies has the side effect of eliminating the normal B cell compartment. Targeting solid tumors may not provide a similar expendable marker. Beyond antibody to Her2/NEU and EGFR, very few antibody-based and no CAR-based therapies have seen broad clinical application for solid tumors. To expand the way in which the surfaceome of solid tumors can be analyzed, we created an algorithm that defines the pairwise relative overexpression of surface antigens. This enables the development of specific immunotherapies that require the expression of two discrete antigens on the surface of the tumor target. This dyad analysis was facilitated by employing the Hotelling’s T-squared test (Hotelling–Lawley multivariate analysis of variance for two independent variables in comparison to a third constant entity (i.e., gene expression levels in normal tissues. We also present a unique consensus scoring mechanism for identifying transcripts that encode cell surface proteins. The unique application of our bioinformatics processing pipeline and statistical tools allowed us to compare the expression of two membrane protein targets as a pair, and to propose a new strategy based on implementing immunotherapies that require both antigens to be expressed on the tumor cell surface to trigger therapeutic effector mechanisms. Specifically, we found that, for MYCN amplified neuroblastoma, pairwise expression of ACVR2B or anaplastic lymphoma kinase (ALK with GFRA3, GFRA2, Cadherin 24, or with one another provided the strongest hits. For MYCN, non-amplified stage 4 neuroblastoma, neurotrophic tyrosine kinase 1, or ALK paired with GFRA2, GFRA3, SSK

  14. Characteristic Changes in Cell Surface Glycosylation Accompany Intestinal Epithelial Cell (IEC) Differentiation: High Mannose Structures Dominate the Cell Surface Glycome of Undifferentiated Enterocytes.

    Science.gov (United States)

    Park, Dayoung; Brune, Kristin A; Mitra, Anupam; Marusina, Alina I; Maverakis, Emanual; Lebrilla, Carlito B

    2015-11-01

    Changes in cell surface glycosylation occur during the development and differentiation of cells and have been widely correlated with the progression of several diseases. Because of their structural diversity and sensitivity to intra- and extracellular conditions, glycans are an indispensable tool for analyzing cellular transformations. Glycans present on the surface of intestinal epithelial cells (IEC) mediate interactions with billions of native microorganisms, which continuously populate the mammalian gut. A distinct feature of IECs is that they differentiate as they migrate upwards from the crypt base to the villus tip. In this study, nano-LC/ESI QTOF MS profiling was used to characterize the changes in glycosylation that correspond to Caco-2 cell differentiation. As Caco-2 cells differentiate to form a brush border membrane, a decrease in high mannose type glycans and a concurrent increase in fucosylated and sialylated complex/hybrid type glycans were observed. At day 21, when cells appear to be completely differentiated, remodeling of the cell surface glycome ceases. Differential expression of glycans during IEC maturation appears to play a key functional role in regulating the membrane-associated hydrolases and contributes to the mucosal surface innate defense mechanisms. Developing methodologies to rapidly identify changes in IEC surface glycans may lead to a rapid screening approach for a variety of disease states affecting the GI tract. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. RPE cell surface proteins in normal and dystrophic rats

    Energy Technology Data Exchange (ETDEWEB)

    Clark, V.M.; Hall, M.O.

    1986-02-01

    Membrane-bound proteins in plasma membrane enriched fractions from cultured rat RPE were analyzed by two-dimensional gel electrophoresis. Membrane proteins were characterized on three increasingly specific levels. Total protein was visualized by silver staining. A maximum of 102 separate proteins were counted in silver-stained gels. Glycoproteins were labeled with 3H-glucosamine or 3H-fucose and detected by autoradiography. Thirty-eight fucose-labeled and 61-71 glucosamine-labeled proteins were identified. All of the fucose-labeled proteins were labeled with glucosamine-derived radioactivity. Proteins exposed at the cell surface were labeled by lactoperoxidase-catalyzed radioiodination prior to preparation of membranes for two-dimensional analysis. Forty separate 125I-labeled surface proteins were resolved by two-dimensional electrophoresis/autoradiography. Comparison with the glycoprotein map showed that a number of these surface labeled proteins were glycoproteins. Two-dimensional maps of total protein, fucose-labeled, and glucosamine-labeled glycoproteins, and 125I-labeled surface proteins of membranes from dystrophic (RCS rdy-p+) and normal (Long Evans or RCS rdy+p+) RPE were compared. No differences in the total protein or surface-labeled proteins were observed. However, the results suggest that a 183K glycoprotein is more heavily glycosylated with glucosamine and fucose in normal RPE membranes as compared to membranes from dystrophic RPE.

  16. Advances in the theory and application of BSF cells. [Back Surface Field solar cells

    Science.gov (United States)

    Mandelkorn, J.; Lamneck, J. H.

    1975-01-01

    A study to determine the influence of fabrication processes and bulk material properties on the behavior of back surface field (BSF) cells is reported. It is concluded that a photovoltage is generated at the p(+), p back junction of the cell. The concept of majority carrier collection is proposed as a possible mechanism for this generation. Advantages accruing to the advent of BSF cells are outlined.

  17. Microwave-assisted green synthesis of superparamagnetic nanoparticles using fruit peel extracts: surface engineering, T 2 relaxometry, and photodynamic treatment potential.

    Science.gov (United States)

    Bano, Shazia; Nazir, Samina; Nazir, Alia; Munir, Saeeda; Mahmood, Tariq; Afzal, Muhammad; Ansari, Farzana Latif; Mazhar, Kehkashan

    2016-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have the potential to be used as multimodal imaging and cancer therapy agents due to their excellent magnetism and ability to generate reactive oxygen species when exposed to light. We report the synthesis of highly biocompatible SPIONs through a facile green approach using fruit peel extracts as the biogenic reductant. This green synthesis protocol involves the stabilization of SPIONs through coordination of different phytochemicals. The SPIONs were functionalized with polyethylene glycol (PEG)-6000 and succinic acid and were extensively characterized by X-ray diffraction analysis, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, Rutherford backscattering spectrometry, diffused reflectance spectroscopy, fluorescence emission, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and magnetization analysis. The developed SPIONs were found to be stable, almost spherical with a size range of 17-25 nm. They exhibited excellent water dispersibility, colloidal stability, and relatively high R 2 relaxivity (225 mM(-1) s(-1)). Cell viability assay data revealed that PEGylation or carboxylation appears to significantly shield the surface of the particles but does not lead to improved cytocompatibility. A highly significant increase of reactive oxygen species in light-exposed samples was found to play an important role in the photokilling of human cervical epithelial malignant carcinoma (HeLa) cells. The bio-SPIONs developed are highly favorable for various biomedical applications without risking interference from potentially toxic reagents.

  18. Multiple hormonal control of enzyme synthesis in liver and hepatoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Kenney, F.T.; Lee, K.L.; Pomato, N.; Nickol, J.M.

    1978-01-01

    Synthesis of hepatic tyrosine aminotransferase is accelerated in vivo by either of the pancreatic hormones, insulin and glucagon as well as by glucocorticoids, and glucagon acts via the intracellular mediator, cyclic AMP. The mechanisms responsive to these hormones have also been retained in cultured hepatoma cells: in H-35 cells the responses appear to be essentially identical to those in liver, especially in that each inducer can act independently of the others. In this paper we describe recent analyses of the cellular mechanisms involved in this multiple hormonal control of synthesis of a single enzyme. These experiments have been done with rat liver in vivo, owing to a need for larger quantities of cellular components that can readily be obtained from cultured cells. As some of these results appear to be at variance in important respects with those of earlier analyses carried out in H-35 cells, we briefly review these earlier experiments as well.

  19. Applications of cell-free protein synthesis in synthetic biology: Interfacing bio-machinery with synthetic environments.

    Science.gov (United States)

    Lee, Kyung-Ho; Kim, Dong-Myung

    2013-11-01

    Synthetic biology is built on the synthesis, engineering, and assembly of biological parts. Proteins are the first components considered for the construction of systems with designed biological functions because proteins carry out most of the biological functions and chemical reactions inside cells. Protein synthesis is considered to comprise the most basic levels of the hierarchical structure of synthetic biology. Cell-free protein synthesis has emerged as a powerful technology that can potentially transform the concept of bioprocesses. With the ability to harness the synthetic power of biology without many of the constraints of cell-based systems, cell-free protein synthesis enables the rapid creation of protein molecules from diverse sources of genetic information. Cell-free protein synthesis is virtually free from the intrinsic constraints of cell-based methods and offers greater flexibility in system design and manipulability of biological synthetic machinery. Among its potential applications, cell-free protein synthesis can be combined with various man-made devices for rapid functional analysis of genomic sequences. This review covers recent efforts to integrate cell-free protein synthesis with various reaction devices and analytical platforms. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Aminopropyltriethoxysilane-mediated surface functionalization of hydroxyapatite nanoparticles: synthesis, characterization, and in vitro toxicity assay

    Directory of Open Access Journals (Sweden)

    Wang S

    2011-12-01

    Full Text Available Shige Wang1, Shihui Wen2, Mingwu Shen2, Rui Guo2, Xueyan Cao2, Jianhua Wang3, Xiangyang Shi1,2,41State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, 2College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, 3Department of Biochemistry and Molecular Cell Biology, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China; 4Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, Funchal, PortugalBackground: We report on aminopropyltriethoxysilane (APTS-mediated surface modification of nanohydroxyapatite with different surface functional groups for potential biomedical applications. In this study, nanohydroxyapatite covalently linked with APTS (n-HA-APTS was reacted with acetic anhydride or succinic anhydride to produce neutralized (n-HA-APTS.Ac or negatively charged (n-HA-APTS.SAH nanohydroxyapatite, respectively. Nanohydroxyapatite formed with amine, acetyl, and carboxyl groups was extensively characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, 1H nuclear magnetic resonance spectroscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectroscopy, and zeta potential measurements.Results: In vitro 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide colorimetric assay revealed that the slight toxicity of the amine-functionalized n-HA-APTS could be eliminated by post-functionalization of APTS amines to form acetyl and carboxyl groups. Blood compatibility assessment demonstrated that the negligible hemolytic activity of the pristine nanohydroxyapatite particles did not appreciably change after APTS-mediated surface functionalization.Conclusion: APTS-mediated functionalization of nanohydroxyapatite with different surface groups may be useful for further functionalization of nanohydroxyapatite with biologically active materials, thereby providing possibilities for a broad range of

  1. Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications.

    Science.gov (United States)

    Gupta, Ajay Kumar; Gupta, Mona

    2005-06-01

    Superparamagnetic iron oxide nanoparticles (SPION) with appropriate surface chemistry have been widely used experimentally for numerous in vivo applications such as magnetic resonance imaging contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, hyperthermia, drug delivery and in cell separation, etc. All these biomedical and bioengineering applications require that these nanoparticles have high magnetization values and size smaller than 100 nm with overall narrow particle size distribution, so that the particles have uniform physical and chemical properties. In addition, these applications need special surface coating of the magnetic particles, which has to be not only non-toxic and biocompatible but also allow a targetable delivery with particle localization in a specific area. To this end, most work in this field has been done in improving the biocompatibility of the materials, but only a few scientific investigations and developments have been carried out in improving the quality of magnetic particles, their size distribution, their shape and surface in addition to characterizing them to get a protocol for the quality control of these particles. Nature of surface coatings and their subsequent geometric arrangement on the nanoparticles determine not only the overall size of the colloid but also play a significant role in biokinetics and biodistribution of nanoparticles in the body. The types of specific coating, or derivatization, for these nanoparticles depend on the end application and should be chosen by keeping a particular application in mind, whether it be aimed at inflammation response or anti-cancer agents. Magnetic nanoparticles can bind to drugs, proteins, enzymes, antibodies, or nucleotides and can be directed to an organ, tissue, or tumour using an external magnetic field or can be heated in alternating magnetic fields for use in hyperthermia. This review discusses the synthetic chemistry, fluid stabilization and

  2. Fixation and stabilization of Escherichia coli cells displaying genetically engineered cell surface proteins

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, A.; Abramov, S. [Tel-Aviv Univ. (Israel); Georgiou, G. [Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering

    1996-12-05

    A large biotechnological potential is inherent in the display of proteins. Applications such as immobilized whole-cell biocatalysts or cellular adsorbents require cell fixation to prevent disintegration, stabilization of the anchored protein from leakage, denaturation or proteolysis, and total loss of cell viability, preventing medium and potential product contamination with cells. In this article the authors describe the adaptation of a simple two-stage chemical crosslinking procedure based on bi-layer encagement for stabilizing Escherichia coli cells expressing an Lpp-OmpA-{beta}-lactamase fusion that displays {beta}-lactamase on the cell surface. Bilayer crosslinking and coating the bacteria with a polymeric matrix is accomplished by treating the cells first with either glutaraldehyde or polyglutaraldehyde, followed by secondary crosslinking with polyacrylamide hydrazide. These treatments resulted in a 5- to 25-fold reduction of the thermal inactivation rate constant at 55 C of surface anchored {beta}-lactamase and completely prevented the deterioration of the cells for at least a week of storage at 4 C. The stabilization procedure developed paves the way to scalable biotechnological applications of E. coli displaying surface anchored proteins as whole-cell biocatalysts and adsorbents.

  3. Surface modification for interaction study with bacteria and preosteoblast cells

    Science.gov (United States)

    Song, Qing

    Surface modification plays a pivotal role in bioengineering. Polymer coatings can provide biocompatibility and biofunctionalities to biomaterials through surface modification. In this dissertation, initiated chemical vapor deposition (iCVD) was utilized to coat two-dimensional (2D) and three-dimensional (3D) substrates with differently charged polyelectrolytes in order to generate antimicrobial and osteocompatible biomaterials. ICVD is a modified CVD technique that enables surface modification in an all-dry condition without substrate damage and solvent contamination. The free-radical polymerization allows the vinyl polymers to conformally coat on various micro- and nano-structured substrates and maintains the delicate structure of the functional groups. The vapor deposition of polycations provided antimicrobial activity to planar and porous substrates through destroying the negatively charged bacterial membrane and brought about high contact-killing efficiency (99.99%) against Gram-positive Bacillus subtilis and Gram-negative Escherichia coli. Additionally, the polyampholytes synthesized by iCVD exhibited excellent antifouling performance against the adhesion of Gram-positive Listeria innocua and Gram-negative E. coli in phosphate buffered saline (PBS). Their antifouling activities were attributed to the electrostatic interaction and hydration layers that served as physical and energetic barriers to prevent bacterial adhesion. The contact-killing and antifouling polymers synthesized by iCVD can be applied to surface modification of food processing equipment and medical devices with the aim of reducing foodborne diseases and medical infections. Moreover, the charged polyelectrolyte modified 2D polystyrene surfaces displayed good osteocompatibility and enhanced osteogenesis of preosteoblast cells than the un-modified polystyrene surface. In order to promote osteoinduction of hydroxyapatite (HA) scaffolds, bioinspired polymer-controlled mineralization was conducted

  4. Glucocorticoids Inhibit Basal and Hormone-Induced Serotonin Synthesis in Pancreatic Beta Cells

    OpenAIRE

    Moina Hasni Ebou; Amrit Singh-Estivalet; Jean-Marie Launay; Jacques Callebert; François Tronche; Pascal Ferré; Jean-François Gautier; Ghislaine Guillemain; Bernadette Bréant; Bertrand Blondeau; Jean-Pierre Riveline

    2016-01-01

    International audience; Diabetes is a major complication of chronic Glucocorticoids (GCs) treatment. GCs induce insulin resistance and also inhibit insulin secretion from pancreatic beta cells. Yet, a full understanding of this negative regulation remains to be deciphered. In the present study, we investigated whether GCs could inhibit serotonin synthesis in beta cell since this neurotransmitter has been shown to be involved in the regulation of insulin secretion. To this aim, serotonin synth...

  5. Regulation of Insulin Synthesis and Secretion and Pancreatic Beta-Cell Dysfunction in Diabetes

    OpenAIRE

    Fu, Zhuo; Gilbert, Elizabeth R.; Liu, Dongmin

    2013-01-01

    Pancreatic β-cell dysfunction plays an important role in the pathogenesis of both type 1 and type 2 diabetes. Insulin, which is produced in β-cells, is a critical regulator of metabolism. Insulin is synthesized as preproinsulin and processed to proinsulin. Proinsulin is then converted to insulin and C-peptide and stored in secretary granules awaiting release on demand. Insulin synthesis is regulated at both the transcriptional and translational level. The cis-acting sequences within the 5′ fl...

  6. A model for the biosynthesis and transport of plasma membrane-associated signaling receptors to the cell surface

    Directory of Open Access Journals (Sweden)

    Sorina Claudia Popescu

    2012-04-01

    Full Text Available Intracellular protein transport is emerging as critical in determining the outcome of receptor-activated signal transduction pathways. In plants, relatively little is known about the nature of the molecular components and mechanisms involved in coordinating receptor synthesis and transport to the cell surface. Recent advances in this field indicate that signaling pathways and intracellular transport machinery converge and coordinate to render receptors competent for signaling at their plasma membrane activity sites. The biogenesis and transport to the cell surface of signaling receptors appears to require both general trafficking and receptor-specific factors. Several molecular determinants, residing or associated with compartments of the secretory pathway and known to influence aspects in receptor biogenesis, are discussed and integrated into a predictive cooperative model for the functional expression of signaling receptors at the plasma membrane.

  7. Layer-by-Layer Method for the Synthesis and Growth of Surface Mounted Metal-Organic Frameworks (SURMOFs

    Directory of Open Access Journals (Sweden)

    Osama Shekhah

    2010-02-01

    Full Text Available A layer-by-layer method has been developed for the synthesis of metal-organic frameworks (MOFs and their deposition on functionalized organic surfaces. The approach is based on the sequential immersion of functionalized organic surfaces into solutions of the building blocks of the MOF, i.e., the organic ligand and the inorganic unit. The synthesis and growth of different types of MOFs on substrates with different functionalization, like COOH, OH and pyridine terminated surfaces, were studied and characterized with different surface characterization techniques. A controlled and highly oriented growth of very homogenous films was obtained using this method. The layer-by-layer method offered also the possibility to study the kinetics of film formation in more detail using surface plasmon resonance and quartz crystal microbalance. In addition, this method demonstrates the potential to synthesize new classes of MOFs not accessible by conventional methods. Finally, the controlled growth of MOF thin films is important for many applications like chemical sensors, membranes and related electrodes.

  8. Effect of surface hydroxyls on dimethyl ether synthesis over the γ-Al₂O₃ in liquid paraffin: a computational study.

    Science.gov (United States)

    Zuo, Zhi-Jun; Wang, Le; Han, Pei-de; Huang, Wei

    2013-11-01

    In a recent paper (Zuo et al., Appl Catal A 408:130-136, 2011), the mechanism of dimethyl ether (DME) synthesis from methanol dehydration over γ-Al2O3 (110) was studied using density functional theory (DFT). Using the same method, the effect of surface hydroxyls on γ-Al2O3 in liquid paraffin during DME synthesis from methanol dehydration is investigated. It is found that DME is mainly formed from two adsorbed CH3O groups via methanol dehydrogenation on both dehydrated and hydrated γ-Al2O3 in liquid paraffin. No close correlation between catalytic activity and acid intensity was found. Before and after water adsorption at typical catalytic conditions (e.g., 553 K), the reaction rate is not obviously changed on γ-Al2O3(100) surface in liquid paraffin, but the reaction rate decreases by about 11 times on the (110) in liquid paraffin. Considering the area of the (110) and (100) surfaces under actual conditions, the catalytic activity decreased mainly because the Al3 sites on the (110) surface gradually become inactive. Catalytic activity decreased mainly due to surface hydrophilicity. The calculated results were consistent with the experiment.

  9. Ergosterol-induced sesquiterpenoid synthesis in tobacco Cells

    CSIR Research Space (South Africa)

    Tugizimana, F

    2012-02-01

    Full Text Available molecule to trigger defence mechanisms. Here we investigated the effect of ergosterol on the secondary metabolites in tobacco (Nicotiana tabacum) cells by profiling the induced sesquiterpenoids. Suspensions of tobacco cells were treated with different...

  10. Heme oxygenase activity modulates vascular endothelial growth factor synthesis in vascular smooth muscle cells.

    Science.gov (United States)

    Dulak, Jozef; Józkowicz, Alicja; Foresti, Roberta; Kasza, Aneta; Frick, Matthias; Huk, Ihor; Green, Colin J; Pachinger, Otmar; Weidinger, Franz; Motterlini, Roberto

    2002-04-01

    Hypoxia, cytokines, and nitric oxide (NO) stimulate the generation of vascular endothelial growth factor (VEGF) and induce heme oxygenase-1 (HO-1) expression in vascular tissue. HO-1 degrades heme to carbon monoxide (CO), iron, and biliverdin, the latter being reduced to bilirubin by biliverdin reductase. In the present study, we investigated the role of HO-1 in the modulation of VEGF synthesis in rat vascular smooth muscle cells (VSMC). In VSMC stimulated with cytokines, inhibition of NO production significantly, but not completely, reduced VEGF release. In contrast, inhibition of HO activity by tin protoporphyrin IX (SnPPIX) totally prevented cytokine-induced increase in VEGF, despite an augmented synthesis of intracellular NO. Stimulation of HO-1 activity by hemin enhanced VEGF production; this effect was abrogated by blockade of the HO pathway. Similarly, VEGF synthesis induced by hypoxia was down-regulated by SnPPIX, but not by inhibitors of NO synthase. To elucidate further a direct involvement of HO-1 in the observed effects, we generated transfected cells that overexpressed the HO-1 gene. Notably, these cells synthesized significantly more VEGF protein than cells transfected with a control gene. Among the products of HO-1, biliverdin and bilirubin showed no effect, whereas iron ions inhibited VEGF synthesis. Exposure of cells to 1% CO resulted in a marked accumulation of VEGF (20-fold increase) over the basal level. Our data indicate that HO-1 activity influences the generation of VEGF in VSMC in both normoxic and hypoxic conditions. As CO and iron, respectively the inducer and the inhibitor of VEGF synthesis, are concomitantly produced during the degradation of heme, these data indicate that HO by-products may differentially modulate VEGF production.

  11. Alpha-ketoglutarate inhibits glutamine degradation and enhances protein synthesis in intestinal porcine epithelial cells.

    Science.gov (United States)

    Yao, Kang; Yin, Yulong; Li, Xilong; Xi, Pengbin; Wang, Junjun; Lei, Jian; Hou, Yongqing; Wu, Guoyao

    2012-06-01

    α-Ketoglutarate (AKG) is a key intermediate in glutamine metabolism. Emerging evidence shows beneficial effects of AKG on clinical and experimental nutrition, particularly with respect to intestinal growth and integrity. However, the underlying mechanisms are unknown. Intestinal porcine epithelial cells (IPEC-1) were used to test the hypothesis that AKG inhibits glutamine degradation and enhances protein synthesis. IPEC-1 cells were cultured for 3 days in Dulbecco's modified Eagle's-F12 Ham medium (DMEM-F12) containing 0, 0.2, 0.5 or 2 mM of AKG. At the end of the 3-day culture, cells were used to determine L-[U-14C]glutamine utilization, protein concentration, protein synthesis, and the total and phosphorylated levels of the mammalian target of the rapamycin (mTOR), ribosomal protein S6 kinase-1 (S6K1) and eukaryotic initiation factor (eIF) 4E-binding protein-1 (4E-BP1). Compared with 0 mM of AKG (control), 0.2 and 0.5 mM of AKG dose-dependently reduced (P<0.05) glutamine degradation and the production of glutamate, alanine and aspartate in IPEC-1 cells. Addition of 0.5 and 2 mM of AKG to culture medium enhanced protein synthesis (P<0.05) by 78 and 101% without affecting protein degradation, compared to the control group. Rapamycin (50 nM; a potent inhibitor of mTOR) attenuated the stimulatory effect of AKG on protein synthesis. Consistent with these metabolic data, the addition of 0.5 or 2 mM of AKG to culture medium increased (P<0.05) the phosphorylated levels of mTOR, S6k1 and 4E-BP1 proteins. Collectively, these results indicate that AKG can spare glutamine and activate the mTOR signaling pathway to stimulate protein synthesis in intestinal epithelial cells.

  12. Asiaticoside induces cell proliferation and collagen synthesis in human dermal fibroblasts

    Directory of Open Access Journals (Sweden)

    Linda Yulianti

    2015-08-01

    Full Text Available Asiatiocoside, a saponin component isolated from Centella asiatica can improve wound healing by promoting the proliferation of human dermal fibroblasts (HDF and synthesis of collagen. The skin-renewing cells and type I and III collagen synthesis decrease with aging, resulting in the reduction of skin elasticity and delayed wound healing. Usage of natural active compounds from plants in wound healing should be evaluated and compared to retinoic acid as an active agent that regulates wound healing. The aim of this study was to compare and evaluate the effect of asiaticoside and retinoic acid to induce greater cell proliferation and type I and III collagen synthesis in human dermal fibroblast. Methods Laboratory experiments were conducted using human dermal fibroblasts (HDF isolated from human foreskin explants. Seven passages of HDF were treated with asiaticoside and retinoic acid at several doses and incubated for 24 and 48 hours. Cell viability in all groups was tested with the MTT assay to assess HDF proliferation. Type I and III collagen synthesis was examined using the respective ELISA kits. Analysis of variance was performed to compare the treatment groups. Results Asiaticoside had significantly stronger effects on HDF proliferation than retinoic acid (p<0.05. The type III collagen production was significantly greater induction with asiaticoside compared to retinoic acid (p<0.05. Conclusion Asiaticoside induces HDF proliferation and type I and III collagen synthesis in a time- and dose-dependent pattern. Asiaticoside has a similar effect as retinoic acid on type I and type III collagen synthesis.

  13. Arginine deiminase modulates endothelial tip cells via excessive synthesis of reactive oxygen species.

    Science.gov (United States)

    Zhuo, Wei; Song, Xiaomin; Zhou, Hao; Luo, Yongzhang

    2011-10-01

    ADI (arginine deiminase), an enzyme that hydrolyses arginine, has been reported as an anti-angiogenesis agent. However, its molecular mechanism is unclear. We have demonstrated for the first time that ADI modulates the angiogenic activity of endothelial tip cells. By arginine depletion, ADI disturbs actin filament in endothelial tip cells, causing disordered migratory direction and decreased migration ability. Furthermore, ADI induces excessive synthesis of ROS (reactive oxygen species), and activates caspase 8-, but not caspase 9-, dependent apoptosis in endothelial cells. These findings provide a novel mechanism by which ADI inhibits tumour angiogenesis through modulating endothelial tip cells.

  14. Cell-Free Protein Synthesis: Pros and Cons of Prokaryotic and Eukaryotic Systems.

    Science.gov (United States)

    Zemella, Anne; Thoring, Lena; Hoffmeister, Christian; Kubick, Stefan

    2015-11-01

    From its start as a small-scale in vitro system to study fundamental translation processes, cell-free protein synthesis quickly rose to become a potent platform for the high-yield production of proteins. In contrast to classical in vivo protein expression, cell-free systems do not need time-consuming cloning steps, and the open nature provides easy manipulation of reaction conditions as well as high-throughput potential. Especially for the synthesis of difficult to express proteins, such as toxic and transmembrane proteins, cell-free systems are of enormous interest. The modification of the genetic code to incorporate non-canonical amino acids into the target protein in particular provides enormous potential in biotechnology and pharmaceutical research and is in the focus of many cell-free projects. Many sophisticated cell-free systems for manifold applications have been established. This review describes the recent advances in cell-free protein synthesis and details the expanding applications in this field. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  15. Recent advances towards development and commercialization of plant cell culture processes for the synthesis of biomolecules.

    Science.gov (United States)

    Wilson, Sarah A; Roberts, Susan C

    2012-04-01

    Plant cell culture systems were initially explored for use in commercial synthesis of several high-value secondary metabolites, allowing for sustainable production that was not limited by the low yields associated with natural harvest or the high cost associated with complex chemical synthesis. Although there have been some commercial successes, most notably paclitaxel production from Taxus sp., process limitations exist with regards to low product yields and inherent production variability. A variety of strategies are being developed to overcome these limitations including elicitation, in situ product removal and metabolic engineering with single genes and transcription factors. Recently, the plant cell culture production platform has been extended to pharmaceutically active heterologous proteins. Plant systems are beneficial because they are able to produce complex proteins that are properly glycosylated, folded and assembled without the risk of contamination by toxins that are associated with mammalian or microbial production systems. Additionally, plant cell culture isolates transgenic material from the environment, allows for more controllable conditions over field-grown crops and promotes secretion of proteins to the medium, reducing downstream purification costs. Despite these benefits, the increase in cost of heterologous protein synthesis in plant cell culture as opposed to field-grown crops is significant and therefore processes must be optimized with regard to maximizing secretion and enhancing protein stability in the cell culture media. This review discusses recent advancements in plant cell culture processing technology, focusing on progress towards overcoming the problems associated with commercialization of these production systems and highlighting recent commercial successes.

  16. Green synthesis of graphene and its cytotoxic effects in human breast cancer cells

    Science.gov (United States)

    Gurunathan, Sangiliyandi; Han, Jae Woong; Eppakayala, Vasuki; Kim, Jin-Hoi

    2013-01-01

    Background: This paper describes an environmentally friendly (“green”) approach for the synthesis of soluble graphene using Bacillus marisflavi biomass as a reducing and stabilizing agent under mild conditions in aqueous solution. In addition, the study reported here investigated the cytotoxicity effects of graphene oxide (GO) and bacterially reduced graphene oxide (B-rGO) on the inhibition of cell viability, reactive oxygen species (ROS) generation, and membrane integrity in human breast cancer cells. Methods: The reduction of GO was characterized by ultraviolet–visible spectroscopy. Size distribution was analyzed by dynamic light scattering. Further, X-ray diffraction and high-resolution scanning electron microscopy were used to investigate the crystallinity of graphene and the morphologies of prepared graphene, respectively. The formation of defects further supports the bio-functionalization of graphene, as indicated in the Raman spectrum of B-rGO. Surface morphology and the thickness of the GO and B-rGO were analyzed using atomic force microscopy, while the biocompatibility of GO and B-rGO were investigated using WST-8 assays on MCF-7 cells. Finally, cellular toxicity was evaluated by ROS generation and membrane integrity assays. Results: In this study, we demonstrated an environmentally friendly, cost-effective, and simple method for the preparation of water-soluble graphene using bacterial biomass. This reduction method avoids the use of toxic reagents such as hydrazine and hydrazine hydrate. The synthesized soluble graphene was confirmed using various analytical techniques. Our results suggest that both GO and B-rGO exhibit toxicity to MCF-7 cells in a dose-dependent manner, with a dose > 60 μg/mL exhibiting obvious cytotoxicity effects, such as decreasing cell viability, increasing ROS generation, and releasing of lactate dehydrogenase. Conclusion: We developed a green and a simple approach to produce graphene using bacterial biomass as a reducing

  17. Green synthesis of graphene and its cytotoxic effects in human breast cancer cells

    Directory of Open Access Journals (Sweden)

    Gurunathan S

    2013-03-01

    Full Text Available Sangiliyandi Gurunathan, Jae Woong Han, Vasuki Eppakayala, Jin-Hoi Kim Department of Animal Biotechnology, Konkuk University, Seoul, South Korea Background: This paper describes an environmentally friendly (“green” approach for the synthesis of soluble graphene using Bacillus marisflavi biomass as a reducing and stabilizing agent under mild conditions in aqueous solution. In addition, the study reported here investigated the cytotoxicity effects of graphene oxide (GO and bacterially reduced graphene oxide (B-rGO on the inhibition of cell viability, reactive oxygen species (ROS generation, and membrane integrity in human breast cancer cells. Methods: The reduction of GO was characterized by ultraviolet–visible spectroscopy. Size distribution was analyzed by dynamic light scattering. Further, X-ray diffraction and high-resolution scanning electron microscopy were used to investigate the crystallinity of graphene and the morphologies of prepared graphene, respectively. The formation of defects further supports the bio-functionalization of graphene, as indicated in the Raman spectrum of B-rGO. Surface morphology and the thickness of the GO and B-rGO were analyzed using atomic force microscopy, while the biocompatibility of GO and B-rGO were investigated using WST-8 assays on MCF-7 cells. Finally, cellular toxicity was evaluated by ROS generation and membrane integrity assays. Results: In this study, we demonstrated an environmentally friendly, cost-effective, and simple method for the preparation of water-soluble graphene using bacterial biomass. This reduction method avoids the use of toxic reagents such as hydrazine and hydrazine hydrate. The synthesized soluble graphene was confirmed using various analytical techniques. Our results suggest that both GO and B-rGO exhibit toxicity to MCF-7 cells in a dose-dependent manner, with a dose > 60 µg/mL exhibiting obvious cytotoxicity effects, such as decreasing cell viability, increasing ROS

  18. (A structural assessment of the role of the cell surface carbohydrates of Rhizobium in the Rhizobium/legume symbiosis)

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, R.I.

    1991-01-01

    Research continued on the study of cell surface carbohydrates of Rhizobium. Objectives include: To characterize, at a structural level, the differences between the lipopolysaccharides of a representative number of strains from different Rhizobium species to determine which features of LPS structure are species-specific and might, therefore, be determinants of host specificity. Determine the effect(s) of nod gene induction on the structure of Rhizobium lipopolysaccharides and determine whether synthesis of a modified LPS molecule or a new surface glycoconjugate is initiated by nod gene induction. Develop a non-chemical means for rapidly screening large numbers of bacterial strains in order to determine which glycoconjugate structural features are conserved between strains of the same species. Provide the necessary structural information which, when coupled with developments in the rapidly expanding field of Rhizobium genetics, should lead to a clear understanding of the role of Rhizobium surface glycoconjugates in host/symbiont interactions. Progress is discussed.

  19. Improvement in efficiency of solar cell by removing Cu2-xSe from CIGS film surface

    Institute of Scientific and Technical Information of China (English)

    Li Wei; Sun Yun; Liu Wei; Li Feng-Yan; Zhou Lin

    2006-01-01

    CIGS thin films are deposited by sputtering and selenization.The synthesis of semiconducting polycrystalline thin films and characteristics of devices based on the CIGS absorbing layers are investigated.Their microstructures are characterized by X-ray diffraction and Raman spectroscopy.The results reveal that there exist metallic Cu2-xSe compounds in CIGS film surfaces and the compounds are thought to be responsible for the degradation of the open circuit voltage of solar cells.The optimization of selenization temperature profile and copper content in the precursor surfaces is studied,concluding that the conversion efficiency may be improved by removing metallic Cu2-xSe compounds from the surfaces of CIGS thin films.

  20. Trace element proxies for surface ocean conditions: A synthesis of culture calibrations with planktic foraminifera

    Science.gov (United States)

    Allen, Katherine A.; Hönisch, Bärbel; Eggins, Stephen M.; Haynes, Laura L.; Rosenthal, Yair; Yu, Jimin

    2016-11-01

    The trace element composition of planktic foraminiferal calcite provides a useful means of determining past surface ocean conditions. We have assembled the results of culture experiments for three species of symbiont-bearing planktic foraminifera, Globigerinoides ruber, Globigerinoides sacculifer, and Orbulina universa, and one symbiont-barren species, Globigerina bulloides, to evaluate their responses to temperature, salinity, pH, carbonate ion, and dissolved inorganic carbon (DIC) growth conditions. Trace element ratios (Li/Ca, B/Ca, Mg/Ca, Sr/Ca, Mn/Ca, Cd/Ca, Ba/Ca, Na/Ca, and U/Ca) were measured simultaneously on samples grown with the same culture techniques, which provides robust, relatable calibrations that may be used together in multi-proxy paleoceanographic studies. Our data confirm that temperature is the dominant control on foraminiferal Mg/Ca under the ranges of conditions studied and that the potential effects of salinity and CO32- on Mg/Ca of these tropical species across late Pleistocene glacial cycles are relatively small. Carbonate system experiments suggest that Sr/Ca may be useful for reconstructing large DIC changes. Na/Ca increases with salinity in G. ruber (pink), but not in G. sacculifer. As these emerging proxy relationships become more firmly established, the synthesis of multiple trace element ratios may help paleoceanographers isolate the effects of different environmental parameters in paleo records. Calcification rates (μg/day) vary among species and do not respond consistently to any experimental parameter. Comparison of our calcification rates with those observed in inorganic calcite precipitation experiments suggest that foraminifera calcify ∼100× more slowly than inorganic calcites grown in similar solutions. We suggest that calcification rate does not typically exert a dominant control on trace element partitioning in planktic foraminiferal calcite, though it may play a role for some elements under certain circumstances

  1. Synthesis of the diazonium (perfluoroalkyl) benzenesulfonimide monomer from Nafion monomer for proton exchange membrane fuel cells

    Science.gov (United States)

    Mei, Hua; D'Andrea, Dan; Nguyen, Tuyet-Trinh; Nworie, Chima

    2014-02-01

    One diazonium (perfluoroalkyl) benzenesulfonimide monomer, perfluoro-3, 6-dioxa-4-methyl-7-octene benzenesulfonyl imide, has been synthesized from Nafion monomer for the first time. With trifluorovinyl ether and diazonium precursors, the partially-fluorinated diazonium PFSI monomer can be polymerized and will provide chemically bonding with carbon electrode in proton exchange membrane fuel cells. A systematic study of the synthesis and characterization of this diazonium PFSI monomer has been conducted by varying reaction conditions. The optimized synthesis method has been established in the lab.

  2. Assessment of DNA synthesis in Islet-1{sup +} cells in the adult murine heart

    Energy Technology Data Exchange (ETDEWEB)

    Weinberger, Florian, E-mail: f.weinberger@uke.de; Mehrkens, Dennis, E-mail: dennis.mehrkens@uk-koeln.de; Starbatty, Jutta, E-mail: starbatty@uke.uni-hamburg.de; Nicol, Philipp, E-mail: Philipp.Nicol@gmx.de; Eschenhagen, Thomas, E-mail: t.eschenhagen@uke.de

    2015-01-02

    Highlights: • Islet-1 was expressed in the adult heart. • Islet-1-positive cells did not proliferate in the adult heart. • Sinoatrial node cells did not proliferate in the adult heart. - Abstract: Rationale: Islet-1 positive (Islet-1{sup +}) cardiac progenitor cells give rise to the right ventricle, atria and outflow tract during murine cardiac development. In the adult heart Islet-1 expression is limited to parasympathetic neurons, few cardiomyocytes, smooth muscle cells, within the proximal aorta and pulmonary artery and sinoatrial node cells. Its role in these cells is unknown. Here we tested the hypothesis that Islet-1{sup +} cells retain proliferative activity and may therefore play a role in regenerating specialized regions in the heart. Methods and results: DNA synthesis was analyzed by the incorporation of tritiated thymidine ({sup 3}H-thymidine) in Isl-1-nLacZ mice, a transgenic model with an insertion of a nuclear beta-galactosidase in the Islet-1 locus. Mice received daily injections of {sup 3}H-thymidine for 5 days. DNA synthesis was visualized throughout the heart by dipping autoradiography of cryosections. Colocalization of an nLacZ-signal and silver grains would indicate DNA synthesis in Islet-1{sup +} cells. Whereas Islet{sup −} non-myocyte nuclei were regularly marked by accumulation of silver grains, colocalization with nLacZ-signals was not detected in >25,000 cells analyzed. Conclusions: Islet-1{sup +} cells are quiescent in the adult heart, suggesting that, under normal conditions, even pacemaking cells do not proliferate at higher rates than normal cardiac myocytes.

  3. Significant role of adhesion properties of primary osteoblast-like cells in early adhesion events for chondroitin sulfate and dermatan sulfate surface molecules.

    Science.gov (United States)

    Stanford, C M; Solursh, M; Keller, J C

    1999-12-05

    The purpose of this study was to characterize the role of cell surface adhesive macromolecules through enzyme modulation and metabolic recovery prior to and during a kinetic cell adhesion assay. Primary rat calvarial osteoblast-like cells were derived from Sprague-Dawley calvarial plates. Cell adhesion kinetics was evaluated with the definition of first-order adhesion kinetics. Osteoblasts were incubated in an adhesion buffer for 1 h prior to a cell attachment assay using various enzymes to remove cell surface glycosaminoglycans (GAGs). A subtractive adhesion analysis was performed by plating cells at 5 x 10(4)/well for variable periods through 2 h. The medium was collected, the well surface washed and pooled, and the number of cells enumerated with a Coulter Counter. Cell adhesion demonstrated first-order logarithmic adhesion kinetics in the first 60 min. Scatchard analysis demonstrated a linear relationship. Preexposure of cells to various enzyme combinations demonstrated that 50% of the equilibrium adhesion was dependent on chondroitin sulfate or dermatan sulfate surface macromolecules. These results were confirmed with pretreatment with a metabolic inhibitor of GAG synthesis (beta-D-xyloside). These results suggest an important role for cell associated chondroitin sulfate and dermatan sulfate in cell adhesion in addition to Arg-Gly-Asp or integrin mediated adhesion events.

  4. Cell-Surface Protein Profiling Identifies Distinctive Markers of Progenitor Cells in Human Skeletal Muscle

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    Akiyoshi Uezumi

    2016-08-01

    Full Text Available Skeletal muscle contains two distinct stem/progenitor populations. One is the satellite cell, which acts as a muscle stem cell, and the other is the mesenchymal progenitor, which contributes to muscle pathogeneses such as fat infiltration and fibrosis. Detailed and accurate characterization of these progenitors in humans remains elusive. Here, we performed comprehensive cell-surface protein profiling of the two progenitor populations residing in human skeletal muscle and identified three previously unrecognized markers: CD82 and CD318 for satellite cells and CD201 for mesenchymal progenitors. These markers distinguish myogenic and mesenchymal progenitors, and enable efficient isolation of the two types of progenitors. Functional study revealed that CD82 ensures expansion and preservation of myogenic progenitors by suppressing excessive differentiation, and CD201 signaling favors adipogenesis of mesenchymal progenitors. Thus, cell-surface proteins identified here are not only useful markers but also functionally important molecules, and provide valuable insight into human muscle biology and diseases.

  5. Fast ultrahigh-degree global spherical harmonic synthesis on nonequispaced grid points at irregular surfaces

    Science.gov (United States)

    Moazezi, Siamak; Zomorrodian, Hossein; Siahkoohi, Hamid Reza; Azmoudeh-Ardalan, Alireza; Gholami, Ali

    2016-09-01

    In this paper, we presented a fast unified method to compute the gravity field functionals and their directional derivatives up to arbitrary orders on nonequispaced grid points at irregular surfaces using ultrahigh-degree models. The direct spherical harmonic synthesis (SHS) for computing the gravity field functionals at arbitrary locations through the Legendre functions is a time-consuming task for high-order and -degree models. Besides, to compute the derivatives of SHS in terms of latitude, the derivatives of the Legendre functions are needed. Therefore, we used Fourier coefficients of Wigner d-functions to compute the directional derivatives of SHS up to arbitrary orders. We also showed that these functions and their derivatives up to order 2 are stable up to ultrahigh-degree 2^{14} = 16{,}384 using extended double precision (i.e., 80 bits variables). Although 2D-FFT can accelerate the computation of global SHS (GSHS), it restricts the results on equispaced grid points. Hence, we used the nonequispaced FFT (NFFT) for computing GSHS on irregular grid points on the sphere that it is the fast nonequispaced GSHS (NGSHS). For maximum degree N and computing points of {{O}}(N^2) with arbitrary locations, the direct computation methods have the complexity of {{O}}(N^4). But the presented algorithm with and without precomputed Fourier coefficients of Wigner d-functions has the complexity of {{O}}(N^2 log ^2 N + N^2 s^2) and {{O}}(N^3 + N^2 s^2), respectively, where s is cutoff parameter of convolu