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Sample records for chemically modified peptide

  1. The Use of Aryl Hydrazide Linkers for the Solid Phase Synthesis of Chemically Modified Peptides

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Y; Mitchell, A R; Camarero, J A

    2006-11-03

    Since Merrifield introduced the concept of solid phase synthesis in 1963 for the rapid preparation of peptides, a large variety of different supports and resin-linkers have been developed that improve the efficiency of peptide assembly and expand the myriad of synthetically feasible peptides. The aryl hydrazide is one of the most useful resin-linkers for the synthesis of chemically modified peptides. This linker is completely stable during Boc- and Fmoc-based solid phase synthesis and yet it can be cleaved under very mild oxidative conditions. The present article reviews the use of this valuable linker for the rapid and efficient synthesis of C-terminal modified peptides, head-to-tail cyclic peptides and lipidated peptides.

  2. High-affinity triplex targeting of double stranded DNA using chemically modified peptide nucleic acid oligomers

    OpenAIRE

    Hansen, Mads E.; Bentin, Thomas; Nielsen, Peter E.

    2009-01-01

    While sequence-selective dsDNA targeting by triplex forming oligonucleotides has been studied extensively, only very little is known about the properties of PNA–dsDNA triplexes—mainly due to the competing invasion process. Here we show that when appropriately modified using pseudoisocytosine substitution, in combination with (oligo)lysine or 9-aminoacridine conjugation, homopyrimidine PNA oligomers bind complementary dsDNA targets via triplex formation with (sub)nanomolar affinities (at pH 7....

  3. High-affinity triplex targeting of double stranded DNA using chemically modified peptide nucleic acid oligomers

    DEFF Research Database (Denmark)

    Hansen, Mads E; Bentin, Thomas; Nielsen, Peter E

    2009-01-01

    While sequence-selective dsDNA targeting by triplex forming oligonucleotides has been studied extensively, only very little is known about the properties of PNA-dsDNA triplexes-mainly due to the competing invasion process. Here we show that when appropriately modified using pseudoisocytosine...... substitution, in combination with (oligo)lysine or 9-aminoacridine conjugation, homopyrimidine PNA oligomers bind complementary dsDNA targets via triplex formation with (sub)nanomolar affinities (at pH 7.2, 150 mM Na(+)). Binding affinity can be modulated more than 1000-fold by changes in pH, PNA oligomer...... length, PNA net charge and/or by substitution of pseudoisocytosine for cytosine, and conjugation of the DNA intercalator 9-aminoacridine. Furthermore, 9-aminoacridine conjugation also strongly enhanced triplex invasion. Specificity for the fully matched target versus one containing single centrally...

  4. Chemical modifiers of radiotherapy

    International Nuclear Information System (INIS)

    Only two groups, anticancer drugs and radiosensitizers are discussed among many groups of chemical modifiers. In combined radiotherapy (RT) with chemotherapy (CT), sequential administration seems to be superior to concomitant administration, because simultaneous use enhances intensively normal tissue damage. In sequential administration, interruption of CT during RT causes growth of distant metastases. So, alternating scheme of RT and CT is proposed and evaluated clinically. Hypoxic cell sensitizers including well-known misonidazole and PLDR inhibitors (Ara-A etc.) are promising in radiotherapy. They should be used intermittently two or three times during RT in order to avoid neurotoxicity of misonidazole. (author) 70 refs

  5. The use of chemically stabilised proteolytic enzymes in peptide synthesis

    OpenAIRE

    Colleary, Sandra

    2003-01-01

    The aim of this project was to study various serine proteases, both native and chemically modified, with a view to their application in peptide synthesis. Various chemical modifications of these were carried out to improve their stability before peptide synthesis. Porcine trypsin was stabilised by reaction with ethylene glycol bis-(succinic acid Nhydroxy-succinimide ester) (EG). The enhanced stability is likely due to intramolecular crosslink(s) being formed in the enzyme. EG-tiypsin reta...

  6. Chemical Methods for Peptide and Protein Production

    Directory of Open Access Journals (Sweden)

    Istvan Toth

    2013-04-01

    Full Text Available Since the invention of solid phase synthetic methods by Merrifield in 1963, the number of research groups focusing on peptide synthesis has grown exponentially. However, the original step-by-step synthesis had limitations: the purity of the final product decreased with the number of coupling steps. After the development of Boc and Fmoc protecting groups, novel amino acid protecting groups and new techniques were introduced to provide high quality and quantity peptide products. Fragment condensation was a popular method for peptide production in the 1980s, but unfortunately the rate of racemization and reaction difficulties proved less than ideal. Kent and co-workers revolutionized peptide coupling by introducing the chemoselective reaction of unprotected peptides, called native chemical ligation. Subsequently, research has focused on the development of novel ligating techniques including the famous click reaction, ligation of peptide hydrazides, and the recently reported a-ketoacid-hydroxylamine ligations with 5-oxaproline. Several companies have been formed all over the world to prepare high quality Good Manufacturing Practice peptide products on a multi-kilogram scale. This review describes the advances in peptide chemistry including the variety of synthetic peptide methods currently available and the broad application of peptides in medicinal chemistry.

  7. Synthesis of chemically modified DNA.

    Science.gov (United States)

    Shivalingam, Arun; Brown, Tom

    2016-06-15

    Naturally occurring DNA is encoded by the four nucleobases adenine, cytosine, guanine and thymine. Yet minor chemical modifications to these bases, such as methylation, can significantly alter DNA function, and more drastic changes, such as replacement with unnatural base pairs, could expand its function. In order to realize the full potential of DNA in therapeutic and synthetic biology applications, our ability to 'write' long modified DNA in a controlled manner must be improved. This review highlights methods currently used for the synthesis of moderately long chemically modified nucleic acids (up to 1000 bp), their limitations and areas for future expansion. PMID:27284032

  8. Chemical labeling of electrochemically cleaved peptides

    NARCIS (Netherlands)

    Roeser, Julien; Alting, Niels F. A.; Permentier, Hjalmar P.; Bruins, Andries P.; Bischoff, Rainer P. H.

    2013-01-01

    RATIONALE Cleavage of peptide bonds C-terminal to tyrosine and tryptophan after electrochemical oxidation may become a complementary approach to chemical and enzymatic cleavage. A chemical labeling approach specifically targeting reactive cleavage products is presented here and constitutes a promisi

  9. Interpretation of tandem mass spectra of posttranslationally modified peptides

    DEFF Research Database (Denmark)

    Bunkenborg, J.; Matthiesen, R.

    2013-01-01

    spectra and protein database search engines have been developed to match the experimental data to peptide candidates. In most studies there is a schism between discarding perfectly valid data and including nonsensical peptide identifications-this is currently a major bottleneck in data-analysis and it...... calls for an understanding of tandem mass spectrometry data. Manual evaluation of the data and perhaps experimental cross-checking of the MS data can save many months of experimental work trying to do biological follow-ups based on erroneous identifications. Especially for posttranslationally modified...... peptides there is a need for manual validation of the data because search algorithms seldom have been optimized for the identification of modified peptides and because there are many pitfalls for the unwary. This chapter describes some of the issues that should be considered when interpreting and...

  10. Chemically stabilized subtilisins in peptide synthesis

    OpenAIRE

    Colleary, Sandra; Ó'Fágáin, Ciarán

    2008-01-01

    We have stabilized alcalaseTM and subtilisin Carlsberg (SC) against heat by chemical modification with ethylene glycol bis-succinimidyl succinate (EGNHS), a procedure not previously reported for subtilisins. The increases in thermal stability at 65oC were 1.8-fold and 4.7-fold respectively. Caseinolytic activity of alcalase in aqueous buffer was unchanged following modification but apparent Km of SC decreased 2.5-fold. Native and modified forms of both enzymes synthesized the tripeptide Z-...

  11. Chemical instability of pharmaceutical peptides in polymeric controlled release systems

    NARCIS (Netherlands)

    Shirangi, M.

    2015-01-01

    Peptide and protein drugs are presently an important class of pharmaceuticals due to their favorable properties, i.e. high and selective activity. However, peptides and proteins are relatively sensitive for degradation and therefore there is need for investigation of the chemical stability of these

  12. Chemical Pyrophosphorylation of Functionally Diverse Peptides

    OpenAIRE

    Marmelstein, Alan M.; Yates, Lisa M.; Conway, John H.; Fiedler, Dorothea

    2013-01-01

    A highly selective and convenient method for the synthesis of pyrophosphopeptides in solution is reported. The remarkable compatibility with functional groups (alcohol, thiol, amine, carboxylic acid) in the peptide substrates suggests that the intrinsic nucleophilicity of the phosphoserine residue is much higher than previously appreciated. Because the methodology operates in polar solvents, including water, a broad range of pyrophosphopeptides can be accessed. We envision these peptides will...

  13. Human Bone Marrow Mesenchymal Stem Cell Behaviors on PCL/Gelatin Nanofibrous Scaffolds Modified with A Collagen IV-Derived RGD-Containing Peptide

    OpenAIRE

    Ali Mota; Abbas Sahebghadam Lotfi; Jalal Barzin; Mostafa Hatam; Behzad Adibi; Zahra Khalaj; Mohammad Massumi

    2014-01-01

    Objective We introduce an RGD (Arg-Gly-Asp)-containing peptide of collagen IV origin that possesses potent cell adhesion and proliferation properties. Materials and Methods In this experimental study, the peptide was immobilized on an electrospun nanofibrous polycaprolactone/gelatin (PCL/Gel) hybrid scaffold by a chemical bonding approach to improve cell adhesion properties of the scaffold. An io- dine-modified phenylalanine was introduced in the peptide to track the immobilization process. N...

  14. Properties Characterization of Chemically Modified Hemp Hurds

    Directory of Open Access Journals (Sweden)

    Nadezda Stevulova

    2014-12-01

    Full Text Available The effect of chemical treatment of hemp hurds slices in three solutions (EDTA (Ethylenediaminetetraacetic acid, NaOH and Ca(OH2 on the properties of natural material was discussed in this paper. Changes in the morphology, chemical composition and structure as well as thermal stability of hemp hurds before and after their modification were investigated by using FTIR (Fourier transform infrared spectroscopy, XRD (X-ray powder diffraction analysis and TG (thermogravimetry/DSC (differential scanning calorimetry. Size exclusion chromatography (SEC measurements were used for determination of degree of cellulose polymerization of hemp hurd samples. Chemical modification is related to the partial removal of non-cellulosic components of lignin, hemicellulose and pectin as well as waxes from the surface of hemp hurd slices. Another effect of the chemical treatment applied is connected with increasing the crystallinity index of cellulose determined by FTIR and XRD methods. Decrease in degree of cellulose polymerization and polydispersity index in chemically modified hemp hurds compared to the original sample was observed. Increase in thermal stability of treated hemp hurd was found. The most significant changes were observed in alkaline treated hemp hurds by NaOH.

  15. Cell-penetrating peptides; chemical modification, mechanism of uptake and formulation development

    OpenAIRE

    Ezzat, Kariem

    2012-01-01

    Gene therapy holds the promise of revolutionizing the way we treat diseases. By using recombinant DNA and oligonucleotides (ONs), gene functions can be restored, altered or silenced according to the therapeutic need. However, gene therapy approaches require the delivery of large and charged nucleic acid-based molecules to their intracellular targets across the plasma membrane, which is inherently impermeable to such molecules. In this thesis, two chemically modified cell-penetrating peptides ...

  16. Peptide protected gold clusters: chemical synthesis and biomedical applications

    Science.gov (United States)

    Yuan, Qing; Wang, Yaling; Zhao, Lina; Liu, Ru; Gao, Fuping; Gao, Liang; Gao, Xueyun

    2016-06-01

    Bridging the gap between atoms and nanoparticles, noble metal clusters with atomic precision continue to attract considerable attention due to their important applications in catalysis, energy transformation, biosensing and biomedicine. Greatly different to common chemical synthesis, a one-step biomimetic synthesis of peptide-conjugated metal clusters has been developed to meet the demand of emerging bioapplications. Under mild conditions, multifunctional peptides containing metal capturing, reactive and targeting groups are rationally designed and elaborately synthesized to fabricate atomically precise peptide protected metal clusters. Among them, peptide-protected Au Cs (peptide-Au Cs) possess a great deal of exceptional advantages such as nanometer dimensions, high photostability, good biocompatibility, accurate chemical formula and specific protein targeting capacity. In this review article, we focus on the recent advances in potential theranostic fields by introducing the rising progress of peptide-Au Cs for biological imaging, biological analysis and therapeutic applications. The interactions between Au Cs and biological systems as well as potential mechanisms are also our concerned theme. We expect that the rapidly growing interest in Au Cs-based theranostic applications will attract broader concerns across various disciplines.

  17. The direct peptide reactivity assay: selectivity of chemical respiratory allergens.

    Science.gov (United States)

    Lalko, Jon F; Kimber, Ian; Gerberick, G Frank; Foertsch, Leslie M; Api, Anne Marie; Dearman, Rebecca J

    2012-10-01

    It is well known that some chemicals are capable of causing allergic diseases of the skin and respiratory tract. Commonly, though not exclusively, chemical allergens are associated with the selective development of skin or respiratory sensitization. The reason for this divergence is unclear, although it is hypothesized that the nature of interactions between the chemical hapten and proteins is influential. The direct peptide reactivity assay (DPRA) has been developed as a screen for the identification of skin-sensitizing chemicals, and here we describe the use of this method to explore whether differences exist between skin and respiratory allergens with respect to their peptide-binding properties. Known skin and respiratory sensitizers were reacted with synthetic peptides containing either lysine (Lys) or cysteine (Cys) for 24 h. The samples were analyzed by HPLC/UV, and the loss of peptide from the reaction mixture was expressed as the percent depletion compared with the control. The potential for preferential reactivity was evaluated by comparing the ratio of Lys to Cys depletion (Lys:Cys ratio). The results demonstrate that the majority of respiratory allergens are reactive in the DPRA, and that in contrast to most skin-sensitizing chemicals, preferentially react with the Lys peptide. These data suggest that skin and respiratory chemical allergens can result in different protein conjugates, which may in turn influence the quality of induced immune responses. Overall, these investigations reveal that the DPRA has considerable potential to be incorporated into tiered testing approaches for the identification and characterization of chemical respiratory allergens. PMID:22713598

  18. Expanding the chemical toolbox for the synthesis of large and uniquely modified proteins

    Science.gov (United States)

    Bondalapati, Somasekhar; Jbara, Muhammad; Brik, Ashraf

    2016-05-01

    Methods to prepare proteins that include a specific modification at a desired position are essential for understanding their cellular functions and physical properties in living systems. Chemical protein synthesis, which relies on the chemoselective ligation of unprotected peptides, enables the preparation of modified proteins that are not easily fabricated by other methods. In contrast to recombinant approaches, chemical synthesis can be used to prepare protein analogues such as D-proteins, which are useful in protein structure determination and the discovery of novel therapeutics. Post-translationally modifying proteins is another example where chemical protein synthesis proved itself as a powerful approach for preparing samples with high homogeneity and in workable quantities. In this Review, we discuss the basic principles of the field, focusing on novel chemoselective peptide ligation approaches such as native chemical ligation and the recent advances based on this method with a proven record of success in the synthesis of highly important protein targets.

  19. Chemical Synthesis of Human Insulin-Like Peptide-6.

    Science.gov (United States)

    Wu, Fangzhou; Mayer, John P; Zaykov, Alexander N; Zhang, Fa; Liu, Fa; DiMarchi, Richard D

    2016-07-01

    Human insulin-like peptide-6 (INSL-6) belongs to the insulin superfamily and shares the distinctive disulfide bond configuration of human insulin. In this report we present the first chemical synthesis of INSL-6 utilizing fluorenylmethyloxycarbonyl-based (Fmoc) solid-phase peptide chemistry and regioselective disulfide bond construction protocols. Due to the presence of an oxidation-sensitive tryptophan residue, two new orthogonal synthetic methodologies were developed. The first method involved the identification of an additive to suppress the oxidation of tryptophan during iodine-mediated S-acetamidomethyl (Acm) deprotection and the second utilized iodine-free, sulfoxide-directed disulfide bond formation. The methodologies presented here offer an efficient synthetic route to INSL-6 and will further improve synthetic access to other multiple-disulfide-containing peptides with oxidation-sensitive residues. PMID:27259101

  20. Detection of cancer cells using a peptide nanotube–folic acid modified graphene electrode

    DEFF Research Database (Denmark)

    Castillo, John J.; Svendsen, Winnie Edith; Rozlosnik, Noemi;

    2013-01-01

    This article describes the preparation of a graphene electrode modified with a new conjugate of peptide nanotubes and folic acid for the selective detection of human cervical cancer cells over-expressing folate receptors. The functionalization of peptide nanotubes with folic acid was confirmed by...... fluorescence microscopy and atomic force microscopy. The peptide nanotube–folic acid modified graphene electrode was characterized by scanning electron microscopy and cyclic voltammetry. The modification of the graphene electrode with peptide nanotube–folic acid led to an increase in the current signal. The......–folic acid modified electrode lowered the electron transfer resulting in a decrease in the measured current. A detection limit of 250 human cervical cancer cells per mL was obtained. Control experiments confirmed that the peptide nanotube–folic acid electrode specifically recognized folate receptors. The...

  1. Antitumor activity of chemical modified natural compounds

    Directory of Open Access Journals (Sweden)

    Marilda Meirelles de Oliveira

    1991-01-01

    Full Text Available Search of new activity substances starting from chemotherapeutic agents, continously appears in international literature. Perhaps this search has been done more frequently in the field of anti-tumor chemotherapy on account of the unsuccess in saving advanced stage patients. The new point in this matter during the last decade was computer aid in planning more rational drugs. In near future "the accessibility of supercomputers and emergence of computer net systems, willopen new avenues to rational drug design" (Portoghese, P. S. J. Med. Chem. 1989, 32, 1. Unknown pharmacological active compounds synthetized by plants can be found even without this eletronic devices, as tradicional medicine has pointed out in many contries, and give rise to a new drug. These compounds used as found in nature or after chemical modifications have produced successful experimental medicaments as FAA, "flavone acetic acid" with good results as inibitors of slow growing animal tumors currently in preclinical evaluation for human treatment. In this lecture some international contributions in the field of chemical modified compounds as antineoplasic drugs will be examined, particularly those done by Brazilian researches.

  2. Peptide nanospheres self-assembled from a modified β-annulus peptide of Sesbania mosaic virus.

    Science.gov (United States)

    Matsuura, Kazunori; Mizuguchi, Yusaku; Kimizuka, Nobuo

    2016-11-01

    A novel β-annulus peptide of Sesbania mosaic virus bearing an FKFE sequence at the C terminus was synthesized, and its self-assembling behavior in water was investigated. Dynamic light scattering and transmission electron microscopy showed that the β-annulus peptide bearing an FKFE sequence self-assembled into approximately 30 nm nanospheres in water at pH 3.8, whereas the β-annulus peptide without the FKFE sequence afforded only irregular aggregates. The peptide nanospheres possessed a definite critical aggregation concentration (CAC = 26 μM), above which the size of nanospheres were nearly unaffected by the peptide concentration. The formation of peptide nanospheres was significantly affected by pH; the peptide did not form any assemblies at pH 2.2, whereas larger aggregates were formed at pH 6.4-11.6. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 470-475, 2016. PMID:26573103

  3. Validation of peptide and PTM identifications by chemical perturbation proteomics

    DEFF Research Database (Denmark)

    Bunkenborg, Jakob; Falkenby, Lasse Gaarde; Harder, Lea Mørch; Andersen, Jens S.

    procedure is repeating experiments and estimating false discovery rates by searching reverse or garbled protein sequence databases. One danger of this approach is that erroneous assignments can be made quite consistently and reproducibly by the software based on the measurement of a parent mass and the...... corresponding fragment ions. By derivatizing peptides the parent and fragment masses have to change consistently leading to non-redundant measurements. Here we explore chemical perturbation as a means of improving the confidence level of identifications....

  4. Chemically modified flexible strips as electrochemical biosensors.

    Science.gov (United States)

    Thota, Raju; Ganesh, V

    2014-09-21

    A flexible and disposable strip sensor for non-enzymatic glucose detection is demonstrated in this work. The strips are prepared by using chemical modification processes followed by a simple electroless deposition of copper. Essentially, polyester overhead projector (OHP) transparent films are modified with a monolayer of 3-aminopropyltrimethoxysilane (APTMS) and polyaniline (PANI) conducting polymer. Later, nanostructured copper is deposited onto this modified film. Scanning electron microscope (SEM) and X-ray diffraction (XRD) studies are used for the structural, morphological and crystallinity characterization of the modified films. Electrochemical techniques, namely cyclic voltammetry (CV) and chronoamperometry (CA), are employed for the non-enzymatic detection of glucose. These studies clearly reveal the formation of homogeneous, close-packed spherical Cu particles converged into uniform film that exhibits a good catalytic activity towards the oxidation of glucose. The Cu/PANI/APTMS/OHP sensor displays a remarkable enhancement in the oxidation current density, a very high sensitivity value of 2.8456 mA cm(-2) per mM, and a linear concentration range from 100 μM to 6.5 mM associated with glucose detection. Detection limit is estimated to be 5 μM and the response time of the sensor is determined to be less than 5 s. For comparison, similar studies are performed without PANI, namely Cu/APTMS/OHP films for glucose detection. In this case, a sensitivity value of 2.4457 mA cm(-2) per mM and a linear concentration range of 100 μM-3 mM are estimated. The higher performance characteristics observed in the case of Cu/PANI/APTMS/OHP are attributed to the synergistic effects of the conducting polymer acting as an electron facilitator and the nanostructured Cu films. These disposable, flexible and low-cost strip sensors have also been applied to the detection of glucose in clinical blood serum samples and the results obtained agree very well with the actual glucose

  5. Exploiting Protected Maleimides to Modify Oligonucleotides, Peptides and Peptide Nucleic Acids

    Directory of Open Access Journals (Sweden)

    Clément Paris

    2015-04-01

    Full Text Available This manuscript reviews the possibilities offered by 2,5-dimethylfuran-protected maleimides. Suitably derivatized building blocks incorporating the exo Diels-Alder cycloadduct can be introduced at any position of oligonucleotides, peptide nucleic acids, peptides and peptoids, making use of standard solid-phase procedures. Maleimide deprotection takes place upon heating, which can be followed by either Michael-type or Diels-Alder click conjugation reactions. However, the one-pot procedure in which maleimide deprotection and conjugation are simultaneously carried out provides the target conjugate more quickly and, more importantly, in better yield. This procedure is compatible with conjugates involving oligonucleotides, peptides and peptide nucleic acids. A variety of cyclic peptides and oligonucleotides can be obtained from peptide and oligonucleotide precursors incorporating protected maleimides and thiols.

  6. Peptide-modified PELCL electrospun membranes for regulation of vascular endothelial cells.

    Science.gov (United States)

    Zhou, Fang; Jia, Xiaoling; Yang, Yang; Yang, Qingmao; Gao, Chao; Zhao, Yunhui; Fan, Yubo; Yuan, Xiaoyan

    2016-11-01

    The efficiency of biomaterials used in small vascular repair depends greatly on their ability to interact with vascular endothelial cells (VECs). Rapid endothelialization of the vascular grafts is a promising way to prevent thrombosis and intimal hyperplasia. In this work, modification of electrospun membranes of poly(ethylene glycol)-b-poly(l-lactide-co-ε-caprolactone) (PELCL) by three different peptides for regulation of VECs were studied in order to obtain ideal bioactive biomaterials as small diameter vascular grafts. QK (a mimetic peptide to vascular endothelial growth factor), Arg-Glu-Asp-Val (REDV, a specific adhesive peptide to VECs) and Val-Ala-Pro-Gly (VAPG, a specific adhesive peptide to vascular smooth muscle cells) were investigated. Surface properties of the modified membranes and the response of VECs were verified. It was found that protein adsorption and platelet adhesion were effectively suppressed with the introduction of QK, REDV or VAPG peptides on the PELCL electrospun membranes. Both QK- and REDV-modified electrospun membranes could accelerate the proliferation of VECs in the first 9days, and the QK-modified electrospun membrane promoted cell proliferation more significantly than the REDV-modified one. The REDV-modified PELCL membrane was the most favorable for VECs adhesion than QK- and VAPG-modified membranes. It was suggested that QK- or REDV-modified PELCL electrospun membranes may have great potential applications in cardiovascular biomaterials for rapid endothelialization in situ. PMID:27524062

  7. Human Bone Marrow Mesenchymal Stem Cell Behaviors on PCL/Gelatin Nanofibrous Scaffolds Modified with A Collagen IV-Derived RGD-Containing Peptide

    Directory of Open Access Journals (Sweden)

    Ali Mota

    2014-03-01

    Full Text Available Objective: We introduce an RGD (Arg-Gly-Asp-containing peptide of collagen IV origin that possesses potent cell adhesion and proliferation properties. Materials and Methods: In this experimental study, the peptide was immobilized on an electrospun nanofibrous polycaprolactone/gelatin (PCL/Gel hybrid scaffold by a chemical bonding approach to improve cell adhesion properties of the scaffold. An iodine-modified phenylalanine was introduced in the peptide to track the immobilization process. Native and modified scaffolds were characterized with scanning electron microscopy (SEM and fourier transform infrared spectroscopy (FTIR. We studied the osteogenic and adipogenic differentiation potential of human bone marrow-derived mesenchymal stem cells (hBMSCs. In addition, cell adhesion and proliferation behaviors of hBMSCs on native and peptide modified scaffolds were evaluated by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay and 4',6-diamidino-2-phenylindole (DAPI staining, and the results compared with tissue culture plate, as the control. Results: FTIR results showed that the peptide successfully immobilized on the scaffold. MTT assay and DAPI staining results indicated that peptide immobilization had a dramatic effect on cell adhesion and proliferation. Conclusion: This peptide modified nanofibrous scaffold can be a promising biomaterial for tissue engineering and regenerative medicine with the use of hBMSCs.

  8. Transgenic tobacco expressing a modified spider peptide inhibits the growth of plant pathogens and insect larvae

    Science.gov (United States)

    The gene encoding lycotoxin I, an amphipathic pore-forming peptide, was modified to increase oral toxicity to insects. One of the most active modified genes was then constitutively expressed in tobacco (Nicotiana tabacum) and transformants were evaluated for insect and disease resistance. Pathogenic...

  9. Actively-targeted LTVSPWY peptide-modified magnetic nanoparticles for tumor imaging

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    Jie L-Y

    2012-07-01

    Full Text Available Li-Yong Jie,1 Li-Li Cai,2 Le-Jian Wang,2 Xiao-Ying Ying,2 Ri-Sheng Yu,1 Min-Ming Zhang,1 Yong-Zhong Du21Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, 2College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, People's Republic of ChinaBackground: Magnetic resonance imaging (MRI is widely used in modern clinical medicine as a diagnostic tool, and provides noninvasive and three-dimensional visualization of biological phenomena in living organisms with high spatial and temporal resolution. Therefore, considerable attention has been paid to magnetic nanoparticles as MRI contrast agents with efficient targeting ability and cellular internalization ability, which make it possible to offer higher contrast and information-rich images for detection of disease.Methods: LTVSPWY peptide-modified PEGylated chitosan (LTVSPWY-PEG-CS was synthesized by chemical reaction, and the chemical structure was confirmed by 1H-NMR. LTVSPWY-PEG-CS-modified magnetic nanoparticles were prepared successfully using the solvent diffusion method. Their particle size, size distribution, and zeta potential were measured by dynamic light scattering and electrophoretic mobility, and their surface morphology was investigated by transmission electron microscopy. To investigate their selective targeting ability, the cellular uptake of the LTVSPWY-PEG-CS-modified magnetic nanoparticles was observed in a cocultured system of SKOV-3 cells which overexpress HER2 and A549 cells which are HER2-negative. The in vitro cytotoxicity of these nanoparticles in SKOV-3 and A549 cells was measured using the MTT method. The SKOV-3-bearing nude mouse model was used to investigate the tumor targeting ability of the magnetic nanoparticles in vivo.Results: The average diameter and zeta potential of the LTVSPWY-PEG-CS-modified magnetic nanoparticles was 267.3 ± 23.4 nm and 30.5 ± 7.0 mV, respectively, with a narrow size distribution and

  10. Disposable pencil graphite electrode modified with peptide nanotubes for Vitamin B12 analysis

    Science.gov (United States)

    Pala, Betül Bozdoğan; Vural, Tayfun; Kuralay, Filiz; Çırak, Tamer; Bolat, Gülçin; Abacı, Serdar; Denkbaş, Emir Baki

    2014-06-01

    In this study, peptide nanostructures from diphenylalanine were synthesized in various solvents with various polarities and characterized with Scanning Electron Microscopy (SEM) and Powder X-ray Diffraction (PXRD) techniques. Formation of peptide nanofibrils, nanovesicles, nanoribbons, and nanotubes was observed in different solvent mediums. In order to investigate the effects of peptide nanotubes (PNT) on electrochemical behavior of disposable pencil graphite electrodes (PGE), electrode surfaces were modified with fabricated peptide nanotubes. Electrochemical activity of the pencil graphite electrode was increased with the deposition of PNTs on the surface. The effects of the solvent type, the peptide nanotube concentration, and the passive adsorption time of peptide nanotubes on pencil graphite electrode were studied. For further electrochemical studies, electrodes were modified for 30 min by immobilizing PNTs, which were prepared in water at 6 mg/mL concentration. Vitamin B12 analyses were performed by the Square Wave (SW) voltammetry method using modified PGEs. The obtained data showed linearity over the range of 0.2 μM and 9.50 μM Vitamin B12 concentration with high sensitivity. Results showed that PNT modified PGEs were highly simple, fast, cost effective, and feasible for the electro-analytical determination of Vitamin B12 in real samples.

  11. Disposable pencil graphite electrode modified with peptide nanotubes for Vitamin B{sub 12} analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pala, Betül Bozdoğan [Nanotechnology and Nanomedicine Division, Institute of Science, Hacettepe University, 06800 Ankara (Turkey); Vural, Tayfun [Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Kuralay, Filiz [Department of Chemistry, Faculty of Science and Arts, Ordu University, 52200 Ordu (Turkey); Çırak, Tamer [Nanotechnology and Nanomedicine Division, Institute of Science, Hacettepe University, 06800 Ankara (Turkey); Bolat, Gülçin; Abacı, Serdar [Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Denkbaş, Emir Baki, E-mail: denkbas@hacettepe.edu.tr [Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara (Turkey)

    2014-06-01

    In this study, peptide nanostructures from diphenylalanine were synthesized in various solvents with various polarities and characterized with Scanning Electron Microscopy (SEM) and Powder X-ray Diffraction (PXRD) techniques. Formation of peptide nanofibrils, nanovesicles, nanoribbons, and nanotubes was observed in different solvent mediums. In order to investigate the effects of peptide nanotubes (PNT) on electrochemical behavior of disposable pencil graphite electrodes (PGE), electrode surfaces were modified with fabricated peptide nanotubes. Electrochemical activity of the pencil graphite electrode was increased with the deposition of PNTs on the surface. The effects of the solvent type, the peptide nanotube concentration, and the passive adsorption time of peptide nanotubes on pencil graphite electrode were studied. For further electrochemical studies, electrodes were modified for 30 min by immobilizing PNTs, which were prepared in water at 6 mg/mL concentration. Vitamin B{sub 12} analyses were performed by the Square Wave (SW) voltammetry method using modified PGEs. The obtained data showed linearity over the range of 0.2 μM and 9.50 μM Vitamin B{sub 12} concentration with high sensitivity. Results showed that PNT modified PGEs were highly simple, fast, cost effective, and feasible for the electro-analytical determination of Vitamin B{sub 12} in real samples.

  12. Disposable pencil graphite electrode modified with peptide nanotubes for Vitamin B12 analysis

    International Nuclear Information System (INIS)

    In this study, peptide nanostructures from diphenylalanine were synthesized in various solvents with various polarities and characterized with Scanning Electron Microscopy (SEM) and Powder X-ray Diffraction (PXRD) techniques. Formation of peptide nanofibrils, nanovesicles, nanoribbons, and nanotubes was observed in different solvent mediums. In order to investigate the effects of peptide nanotubes (PNT) on electrochemical behavior of disposable pencil graphite electrodes (PGE), electrode surfaces were modified with fabricated peptide nanotubes. Electrochemical activity of the pencil graphite electrode was increased with the deposition of PNTs on the surface. The effects of the solvent type, the peptide nanotube concentration, and the passive adsorption time of peptide nanotubes on pencil graphite electrode were studied. For further electrochemical studies, electrodes were modified for 30 min by immobilizing PNTs, which were prepared in water at 6 mg/mL concentration. Vitamin B12 analyses were performed by the Square Wave (SW) voltammetry method using modified PGEs. The obtained data showed linearity over the range of 0.2 μM and 9.50 μM Vitamin B12 concentration with high sensitivity. Results showed that PNT modified PGEs were highly simple, fast, cost effective, and feasible for the electro-analytical determination of Vitamin B12 in real samples.

  13. Biological and chemical decoration of peptide nanostructures via biotin-avidin interactions.

    Science.gov (United States)

    Reches, Meital; Gazit, Ehud

    2007-07-01

    Novel architectures with nanometric dimensions hold an immense promise as building blocks for future nanotechnological applications. Biological nanostructures are of special interest due to their biocompatibility and because they allow the utilization of biochemical recognition interfaces. The ability to decorate bio-nanostructures with functional groups is highly important in order to utilize them in several applications including ultrasensitive sensors, drug delivery systems, and tissue engineering. Peptide-based nanostructures have a distinct advantage over other assemblies because they can be easily modified with chemical and biological elements. Aromatic dipeptide nanotubes (ADNT) are formed by the self-assembly of a very simple building block, the diphenylalanine peptide. These nanotubes have remarkable chemical and mechanical properties and their utilization in various applications has previously been demonstrated. Here we report on the chemical modification of ADNT with biotin moieties, in order to enable the selective decoration of the tubes with avidin-labeled species. First, ADNT were prepared in aqueous solution by self-assembly of the dipeptide building blocks. Next, they were modified using N-hydroxysuccinimido-biotin. The level of biotinylation was assessed by the interaction of the tubes with gold-labeled strepavidin and ultrastructural analysis by electron microscopy. The ability of the modified assemblies to serve as a generic functional platform was demonstrated by avidin-mediated conjugation. Avidin was added as a molecular linker to allow the decoration with biotin-labeled quantum dots. The efficient decoration was again probed by the imaging of the modified tubes using laser confocal microscopy. Taken together, we demonstrated the ability to decorate ADNT using a generic avidin-biotin adaptor. This decoration should lead to the integration and utilization of the tubes in various applications. PMID:17663236

  14. Preparation and characterization of carboxymethylated carrageenan modified with collagen peptides.

    Science.gov (United States)

    Fan, Lihong; Tong, Jun; Tang, Chang; Wu, Huan; Peng, Min; Yi, Jiayan

    2016-01-01

    The preparation of carboxymethyl κ-carrageenan collagen peptide (CMKC-COP) was via an imide-bond forming reaction between carboxyl groups in carboxymethyl κ-carrageenan (CMKC) and amino groups in collagen peptide in the presence of 1-ethyl-(dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy sulfosuccinimide (NHS). CMKC-COP products were verified with infrared spectroscopy (FT-IR). The results of degree of substitution (DS) of CMKC-COP was presented, which are depended on reaction time, molar ratio of collagen peptide to carboxymethyl κ-carrageenan and reaction temperature. The optimal reaction conditions were studied by means of single factor experiment. Also MTT assay was applied to evaluate the effects of CMKC-COP on proliferation of chick embryo fibroblasts. The animal experiment results indicated that the wound covered with CMKC-COP were completely filled with new epithelium within 2 weeks without any significant adverse side reactions. Therefore, the CMKC-COP showed the potentiality to repair skin in cosmetic, biomedical and pharmaceutical fields. PMID:26526172

  15. Properties Characterization of Chemically Modified Hemp Hurds

    OpenAIRE

    Nadezda Stevulova; Julia Cigasova; Adriana Estokova; Eva Terpakova; Anton Geffert; Frantisek Kacik; Eva Singovszka; Marian Holub

    2014-01-01

    The effect of chemical treatment of hemp hurds slices in three solutions (EDTA (Ethylenediaminetetraacetic acid), NaOH and Ca(OH)2) on the properties of natural material was discussed in this paper. Changes in the morphology, chemical composition and structure as well as thermal stability of hemp hurds before and after their modification were investigated by using FTIR (Fourier transform infrared spectroscopy), XRD (X-ray powder diffraction analysis) and TG (thermogravimetry)/DSC (differentia...

  16. Polymers based on chemically modified starch

    Czech Academy of Sciences Publication Activity Database

    Horák, Pavel; Kruliš, Zdeněk; Šárka, E.; Kobera, Libor

    Prague : Czech Chemical Society, 2014 - (Řápková, R.; Čopíková, J.; Šárka, E.), s. 88-90 ISBN 978-80-86238-70-8. [International Conference on Polysaccharides-Glycoscience /10./. Prague (CZ), 22.10.2014-24.10.2014] R&D Projects: GA TA ČR(CZ) TA04020853 Institutional support: RVO:61389013 Keywords : starch * chemical modification * degree of substitution Subject RIV: CD - Macromolecular Chemistry

  17. Solid-Phase Synthesis of Modified Peptides as Putative Inhibitors of Histone Modifying Enzymes

    DEFF Research Database (Denmark)

    Cohrt, Anders Emil O'Hanlon

    for the solid-phase synthesis of thiourea- and guanidinemodified peptides are presented. By activating N,N ’-di-Boc-thiourea with Mukaiyama’s reagent or HgCl2, the N -terminal of solid-supported peptides could be cleanly converted into the corresponding thiourea or guanidine derivative. The reactions...... strategy was employed in the identification of individual library members. Changes in the acetylation pattern could also be detecting using a quantitative ninhydrin assay....

  18. Properties of chemically modified gelatin films

    Directory of Open Access Journals (Sweden)

    R. A. de Carvalho

    2006-03-01

    Full Text Available Edible and/or biodegradable films usually have limited water vapor barriers, making it difficult to use them. Thus, the objective of this work was to evaluate the effect of a chemical reticulation treatment with formaldehyde and glyoxal on the mechanical properties, water vapor permeability, solubility and color parameters of gelatin-based films. Formaldehyde and glyoxal were added to the filmogenic solution in concentrations ranging from 3.8 to 8.8 mmoles/100 mL of filmogenic solution and 6.3 to 26.3 mmoles/100 mL of filmogenic solution, respectively. The treatments caused a reduction in permeability to water vapor and in solubility. Only the treatment with formaldehyde caused a significant increase in rupture tension for concentrations above 6.3 mmoles/100 mL of filmogenic solution. Scanning electron microscopy indicated a loss of matrix orientation due to the chemical reticulation treatment.

  19. Polymer based on chemically modified starch

    Czech Academy of Sciences Publication Activity Database

    Horák, Pavel; Kruliš, Zdeněk; Šárka, E.; Kobera, Libor

    Praha : Ústav makromolekulární chemie AV ČR, v. v. i, 2014. s. 82. ISBN 978-80-85009-81-1. [Česko-slovenská konference POLYMERY 2014 /8./. 06.10.2014-09.10.2014, Třešť] R&D Projects: GA TA ČR(CZ) TA04020853 Institutional support: RVO:61389013 Keywords : starch * chemical modification * degree of substitution Subject RIV: CD - Macromolecular Chemistry

  20. Obtention of chemically modified clays: organovermiculites

    International Nuclear Information System (INIS)

    The organovermiculite is obtained by incorporating the quaternary ammonium salt in the clay mineral vermiculite interlayer space. The objective of this work was to prepare organovermiculites for applications in organic contaminants adsorption. The variation of interlayer space was determined when the vermiculite was treated with an ionic salt (Praepagem WB) and a non-ionic salt (Amina Etoxilada TA50) in different concentrations. Before interacting with quaternary ammonium salt, the clay mineral was subjected to cationic change process with Na2CO3 to substitute Mg2+ by Na+. The results showed enlargement of interlayer space, reaching values up to 60.0 Å. The vermiculite pre-activated with Na2CO3 during 5 days and modified with the Praepagem WB showed the best performance. Amina Etoxilada TA50 salt was not observed significant changes with increasing concentration. The affinity of organovermiculite for organic solvents was confirmed by Foster swelling test and the best results were observed with diesel and petrol as solvents. (author)

  1. Antibacterial activity of a newly developed peptide-modified lysin against Acinetobacter baumannii and Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Hang eYang

    2015-12-01

    Full Text Available The global emergence of multidrug-resistant (MDR bacteria is a growing threat to public health worldwide. Natural bacteriophage lysins are promising alternatives in the treatment of infections caused by Gram-positive pathogens, but not Gram-negative ones, like Acinetobacter baumannii and Pseudomonas aeruginosa, due to the barriers posed by their outer membranes. Recently, modifying a natural lysin with an antimicrobial peptide was found able to break the barriers, and to kill Gram-negative pathogens. Herein, a new peptide-modified lysin (PlyA was constructed by fusing the cecropin A peptide residues 1–8 (KWKLFKKI with the OBPgp279 lysin and its antibacterial activity was studied. PlyA showed good and broad antibacterial activities against logarithmic phase A. baumannii and P. aeruginosa, but much reduced activities against the cells in stationary phase. Addition of outer membrane permeabilizers (EDTA and citric acid could enhance the antibacterial activity of PlyA against stationary phase cells. Finally, no antibacterial activity of PlyA could be observed in some bio-matrices, such as culture media, milk, and sera. In conclusion, we reported here a novel peptide-modified lysin with significant antibacterial activity against both logarithmic (without OMPs and stationary phase (with OMPs A. baumannii and P. aeruginosa cells in buffer, but further optimization is needed to achieve broad activity in diverse bio-matrices.

  2. One-pot/sequential native chemical ligation using N-sulfanylethylanilide peptide.

    Science.gov (United States)

    Otaka, Akira; Sato, Kohei; Ding, Hao; Shigenaga, Akira

    2012-10-01

    N-Sulfanylethylanilide (SEAlide) peptides were developed with the aim of achieving facile synthesis of peptide thioesters by 9-fluorenylmethyloxycarbonyl (Fmoc)-based solid-phase peptide synthesis (Fmoc SPPS). Initially, SEAlide peptides were found to be converted to the corresponding peptide thioesters under acidic conditions. However, the SEAlide moiety was proved to function as a thioester in the presence of phosphate salts and to participate in native chemical ligation (NCL) with N-terminal cysteinyl peptides, and this has served as a powerful protein synthesis methodology. The reactivity of a SEAlide peptide (anilide vs. thioester) can be easily tuned with or without the use of phosphate salts. This interesting property of SEAlide peptides allows sequential three-fragment or unprecedented four-fragment ligation for efficient one-pot peptide/protein synthesis. Furthermore, dual-kinetically controlled ligation, which enables three peptide fragments simultaneously present in the reaction to be ligated in the correct order, was first achieved using a SEAlide peptide. Beyond our initial expectations, SEAlide peptides have served in protein chemistry fields as very useful crypto-peptide thioesters. PMID:22927228

  3. Peptide o-aminoanilides as crypto-thioesters for protein chemical synthesis.

    Science.gov (United States)

    Wang, Jia-Xing; Fang, Ge-Min; He, Yao; Qu, Da-Liang; Yu, Min; Hong, Zhang-Yong; Liu, Lei

    2015-02-01

    Fully unprotected peptide o-aminoanilides can be efficiently activated by NaNO2 in aqueous solution to furnish peptide thioesters for use in native chemical ligation. This finding enables the convergent synthesis of proteins from readily synthesizable peptide o-aminoanilides as a new type of crypto-thioesters. The practicality of this approach is shown by the synthesis of histone H2B from five peptide segments. Purification or solubilization tags, which are sometimes needed to improve the efficiency of protein chemical synthesis, can be incorporated into the o-aminoanilide moiety, as demonstrated in the preparation of the cyclic protein lactocyclicin Q. PMID:25475965

  4. Chemically-Modified Cellulose Paper as a Microstructured Catalytic Reactor

    Directory of Open Access Journals (Sweden)

    Hirotaka Koga

    2015-01-01

    Full Text Available We discuss the successful use of chemically-modified cellulose paper as a microstructured catalytic reactor for the production of useful chemicals. The chemical modification of cellulose paper was achieved using a silane-coupling technique. Amine-modified paper was directly used as a base catalyst for the Knoevenagel condensation reaction. Methacrylate-modified paper was used for the immobilization of lipase and then in nonaqueous transesterification processes. These catalytic paper materials offer high reaction efficiencies and have excellent practical properties. We suggest that the paper-specific interconnected microstructure with pulp fiber networks provides fast mixing of the reactants and efficient transport of the reactants to the catalytically-active sites. This concept is expected to be a promising route to green and sustainable chemistry.

  5. Linear short histidine and cysteine modified arginine peptides constitute a potential class of DNA delivery agents.

    Science.gov (United States)

    Mann, Anita; Shukla, Vasundhara; Khanduri, Richa; Dabral, Spoorti; Singh, Harpal; Ganguli, Munia

    2014-03-01

    The success of gene therapy relies on the development of safe and efficient multifunctional carriers of nucleic acids that can overcome extra- and intracellular barriers, protect the nucleic acid and mediate its release at the desired site allowing gene expression. Peptides bear unique properties that are indispensable for any carrier, e.g., they can mediate DNA condensation, cellular targeting, membrane translocation, endosomal escape and nuclear localization. In an effort to design a multifunctional peptide, we have modified an arginine homopeptide R16 by replacement of seven arginines with histidines and addition of one cysteine at each end respectively to impart endosomal escape property while maintaining the DNA condensation and release balance. Addition of histidines imparts endosomal escape property to arginine homopeptide, but their arrangement with respect to arginines is more critical in controlling DNA condensation, release and transfection efficiency. Intriguingly, R5H7R4 peptide where charge/arginine is distributed in blocks is preferred for strong condensation while more efficient transfection is seen in the variants R9H7 and H4R9H3, which exhibit weak condensation and strong release. Addition of cysteine to each of these peptides further fine-tuned the condensation-release balance without application of any oxidative procedure unlike other similar systems reported in the literature. This resulted in a large increase in the transfection efficiency in all of the histidine modified peptides irrespective of the arginine and histidine positions. This series of multifunctional peptides shows comparable transfection efficiency to commercially available transfection reagent Lipofectamine 2000 at low charge ratios, with simple preparative procedure and exhibits much less toxicity. PMID:24476132

  6. Binding of leachable components of polymethyl methacrylate (PMMA) and peptide on modified SPR chip

    International Nuclear Information System (INIS)

    Many types of polymers are often used in dentistry, which may cause allergic reaction, mainly methyl methacrylate allergy due to the leachable, degradable components of polymerized dental products. The aim of this study was to investigate the interaction between the leachable components of PMMA and peptides by Fourier-transform Surface Plasmon Resonance (FT SPR). In our previous work binding of oligopeptides (Ph.D.-7 and Ph.D.-12 Peptide Library Kit) was investigated to PMMA surface by phage display technique. It was found that oligopeptides bounded specifically to PMMA surface. The most common amino acids were leucine and proline inside the amino acids sequences of DNA of phages. The binding of haptens, as formaldehyde and methacrylic acid, to frequent amino acids was to investigate on the modified gold SPR chip. Self assembled monolayer (SAM) modified the surface of gold chip and ensured the specific binding between the haptens and amino acids. It was found that amino acids bounded to modified SPR gold and the haptens bounded to amino acids by creating multilayer on the chip surface. By the application of phage display and SPR modern bioanalytical methods the interaction between allergens and peptides can be investigated

  7. Biosorption of uranium by chemically modified Rhodotorula glutinis

    Energy Technology Data Exchange (ETDEWEB)

    Bai Jing, E-mail: baijing@impcas.ac.c [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Yao Huijun [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Fan Fangli; Lin Maosheng [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang Lina; Ding Huajie; Lei Fuan; Wu Xiaolei [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Xiaofei [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Guo Junsheng; Qin Zhi [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2010-11-15

    The present paper reports the biosorption of uranium onto chemically modified yeast cells, Rhodotorula glutinis, in order to study the role played by various functional groups in the cell wall. Esterification of the carboxyl groups and methylation of the amino groups present in the cells were carried out by methanol and formaldehyde treatment, respectively. The uranium sorption capacity increased 31% for the methanol-treated biomass and 11% for the formaldehyde-treated biomass at an initial uranium concentration of 140 mg/L. The enhancement of uranium sorption capacity was investigated by Fourier transform infrared (FTIR) spectroscopy analysis, with amino and carboxyl groups were determined to be the important functional groups involved in uranium binding. The biosorption isotherms of uranium onto the raw and chemically modified biomass were also investigated with varying uranium concentrations. Langmuir and Freundlich models were well able to explain the sorption equilibrium data with satisfactory correlation coefficients higher than 0.9. -- Research highlights: {yields} Uranium biosorption on to chemically modified yeast cells {yields} Cells before and after uranium sorption were investigate by FTIR spectroscopy {yields} Amino and carboxyl groups were important functional groups involved in uranium binding {yields} The sorption equilibrium date of raw and chemically modified biomass fitted well with Langmuir and Freundlich models

  8. Peptide Synthesis through Cell-Free Expression of Fusion Proteins Incorporating Modified Amino Acids as Latent Cleavage Sites for Peptide Release.

    Science.gov (United States)

    Liutkus, Mantas; Fraser, Samuel A; Caron, Karine; Stigers, Dannon J; Easton, Christopher J

    2016-05-17

    Chlorinated analogues of Leu and Ile are incorporated during cell-free expression of peptides fused to protein, by exploiting the promiscuity of the natural biosynthetic machinery. They then act as sites for clean and efficient release of the peptides simply by brief heat treatment. Dehydro analogues of Leu and Ile are similarly incorporated as latent sites for peptide release through treatment with iodine under cold conditions. These protocols complement enzyme-catalyzed methods and have been used to prepare calcitonin, gastrin-releasing peptide, cholecystokinin-7, and prolactin-releasing peptide prohormones, as well as analogues substituted with unusual amino acids, thus illustrating their practical utility as alternatives to more traditional chemical peptide synthesis. PMID:26918308

  9. Tumor angiogenesis imaging: radioiodinated NGR peptide containing t-butyloxycarbonyl as a pharmacokinetic modifier

    International Nuclear Information System (INIS)

    Tumor growth and metastasis largely depend on persistent new blood vessel growth, which is even the rate-limiting step in solid tumor growth. Identified as a cell adhesion motif, NGR has been proven an effective tumor-homing agent, binding specifically on CD13/APN that is expressed in tumor vasculature undergoing angiogenesis and not detected in blood vessels of various other normal tissues. Whether NGR also possesses the potential of tumor imaging in vivo is still in suspension. Internalization of small peptides is an important phenomenon. Internalization brings on deiodination of directly radioiodinated small peptides, and the low weight radiolabeled catabolites are quickly removed from tumor, resulting in poor tumor imaging. It is of good value to study whether Boc could be an effective tyrosine-protecting group, increasing peptide's resistance to deiodination, meanwhile preserving peptide's original specialty. The cyclic peptide YGGGGGCNGRC (G5) and the t-butyloxycarbonyl (Boc)-modified analog (Boc-G5) were synthesized and radiolabeled with iodine-131. Biodistribution results in normal mice indicated that in the case of G5, deiodination in vivo was found, whereas for Boc-G5, the phenomenon was scarce (Figs.1 and 2). Although the radiotracer clearance in tumor became faster for Boc-G5, tumor-to-tissue ratios still improved, arid at 1 h post injection, the uptake ratios of tumor to muscle, blood, heart, and lung reached 4.73, 1.70, 4.09 and 1.70, respectively. It is demonstrated that Boc-group is an effective prosthetic one to prevent deiodination in vivo and meliorate tumor imaging for small peptide.

  10. Effect of Microwave Radiation on Enzymatic and Chemical Peptide Bond Synthesis on Solid Phase

    Directory of Open Access Journals (Sweden)

    Alessandra Basso

    2009-01-01

    Full Text Available Peptide bond synthesis was performed on PEGA beads under microwave radiations. Classical chemical coupling as well as thermolysin catalyzed synthesis was studied, and the effect of microwave radiations on reaction kinetics, beads' integrity, and enzyme activity was assessed. Results demonstrate that microwave radiations can be profitably exploited to improve reaction kinetics in solid phase peptide synthesis when both chemical and biocatalytic strategies are used.

  11. Vertically aligned peptide nanostructures using plasma-enhanced chemical vapor deposition.

    Science.gov (United States)

    Vasudev, Milana C; Koerner, Hilmar; Singh, Kristi M; Partlow, Benjamin P; Kaplan, David L; Gazit, Ehud; Bunning, Timothy J; Naik, Rajesh R

    2014-02-10

    In this study, we utilize plasma-enhanced chemical vapor deposition (PECVD) for the deposition of nanostructures composed of diphenylalanine. PECVD is a solvent-free approach and allows sublimation of the peptide to form dense, uniform arrays of peptide nanostructures on a variety of substrates. The PECVD deposited d-diphenylalanine nanostructures have a range of chemical and physical properties depending on the specific discharge parameters used during the deposition process. PMID:24400716

  12. Enhanced oral bioavailability of insulin using PLGA nanoparticles co-modified with cell-penetrating peptides and Engrailed secretion peptide (Sec).

    Science.gov (United States)

    Zhu, Siqi; Chen, Shuangxi; Gao, Yuan; Guo, Feng; Li, Fengying; Xie, Baogang; Zhou, Jianliang; Zhong, Haijun

    2016-07-01

    Biodegradable polymer nanoparticle drug carriers are an attractive strategy for oral delivery of peptide and protein drugs. However, their ability to cross the intestinal epithelium membrane is largely limited. Therefore, in the present study, cell-penetrating peptides (R8, Tat, penetratin) and a secretion peptide (Sec) with N-terminal stearylation were introduced to modify nanoparticles (NPs) on the surface to improve oral bioavailability of peptide and protein drugs. In vitro studies conducted in Caco-2 cells showed the value of the apparent permeability coefficient (Papp) of the nanoparticles co-modified with Sec and penetratin (Sec-Pen-NPs) was about two-times greater than that of the nanoparticles modified with only penetratin (Pen-NPs), while the increase of transcellular transport of nanoparticles modified together with Sec and R8 (Sec-R8-NPs), or Sec and Tat (Sec-Tat-NPs), was not significant compared with nanoparticles modified with only R8 (R8-NPs) or Tat (Tat-NPs). Using insulin as the model drug, in vivo studies performed on rats indicated that compared to Pen-NPs, the relative bioavailability of insulin for Sec-Pen-NPs was 1.71-times increased after ileal segments administration, and stronger hypoglycemic effects was also observed. Therefore, the nanoparticles co-modified with penetratin and Sec could act as attractive carriers for oral delivery of insulin. PMID:26181841

  13. Separation of toxic peptides (microcystins) in capillary electrophoresis, with the aid of organic mobile phase modifiers.

    Science.gov (United States)

    Onyewuenyi, N; Hawkins, P

    1996-10-18

    A capillary electrophoretic (CE) method incorporating sodium dodecyl sulphate (SDS)-organic modifier solvents in the CE buffer was developed for the detection of toxic cyclic heptapeptide toxins (microcystins) produced by blue-green algae (cyanobacteria). The applicability of these run buffers for the analysis of microcystins was evaluated and optimum conditions for separation were determined. The migration times, elution order and selectivity of the toxic peptides were influenced by modifying the composition of the electrophoretic buffer with organic solvents [0 to 20% (v/v)]. At maximum addition, the organic solvents with the exception of acetonitrile, increased the viscosity of the buffer solution. In contrast to the migration time of the other microcystins, that of microcystin-RR was not increased by the addition of 2-propanol to the buffer solution. Rather, microcystin-RR eluted more quickly with the increase in 2-propanol, thereby effecting changes in the elution order of the microcystins. In addition, this solvent resulted in comigration of microcystin-LR and microcystin-YR. No significant relationship was found between the elution order and separation and the structure of the toxic peptides studied in micellar electrokinetic capillary chromatography with an organic modifier in the buffer solution; but there is an agreement between the effects of the organic modifiers and their dipole moments. Parameters such as linearity, sensitivity and reproducibility were also evaluated. High-efficiency separations of toxic peptide molecules having equal or nearly equal mass to charge ratios have been achieved using SDS as an additive to the running buffer. The influence of the pH has been examined. PMID:8921598

  14. Peptide- and Amine-Modified Glucan Particles for the Delivery of Therapeutic siRNA.

    Science.gov (United States)

    Cohen, Jessica L; Shen, Yuefei; Aouadi, Myriam; Vangala, Pranitha; Tencerova, Michaela; Amano, Shinya U; Nicoloro, Sarah M; Yawe, Joseph C; Czech, Michael P

    2016-03-01

    Translation of siRNA technology into the clinic is limited by the need for improved delivery systems that target specific cell types. Macrophages are particularly attractive targets for RNAi therapy because they promote pathogenic inflammatory responses in a number of important human diseases. We previously demonstrated that a multicomponent formulation of β-1,3-d-glucan-encapsulated siRNA particles (GeRPs) can specifically and potently silence genes in mouse macrophages. A major advance would be to simplify the GeRP system by reducing the number of delivery components, thus enabling more facile manufacturing and future commercialization. Here we report the synthesis and evaluation of a simplified glucan-based particle (GP) capable of delivering siRNA in vivo to selectively silence macrophage genes. Covalent attachment of small-molecule amines and short peptides containing weak bases to GPs facilitated electrostatic interaction of the particles with siRNA and aided in the endosomal release of siRNA by the proton-sponge effect. Modified GPs were nontoxic and were efficiently internalized by macrophages in vitro. When injected intraperitoneally (i.p.), several of the new peptide-modified GPs were found to efficiently deliver siRNA to peritoneal macrophages in lean, healthy mice. In an animal model of obesity-induced inflammation, i.p. administration of one of the peptide-modified GPs (GP-EP14) bound to siRNA selectively reduced the expression of target inflammatory cytokines in the visceral adipose tissue macrophages. Decreasing adipose tissue inflammation resulted in an improvement of glucose metabolism in these metabolically challenged animals. Thus, modified GPs represent a promising new simplified system for the efficient delivery of therapeutic siRNAs specifically to phagocytic cells in vivo for modulation of inflammation responses. PMID:26815386

  15. Influence of temperature on natural and chemically modified zeolites

    International Nuclear Information System (INIS)

    Zeolites from Nizny Hrabovec (Slovak Republic) were modified with solutions of NaOH. The changes of zeolites in the temperature range 20-1200 deg C were studied by thermal analysis (DTA, TG, ETA), X-ray analysis and REM analysis. Thermal analysis showed that the process of dehydration started between temperatures 20 and 600 deg C, over this temperature the dealumination and structural changes have taken place. X-ray analysis and REM analysis showed the structural changes of natural zeolites and gradual loss of cristallinity of the chemically modified zeolites. (author)

  16. Chemical sensors based on molecularly modified metallic nanoparticles

    International Nuclear Information System (INIS)

    This paper presents a concise, although admittedly non-exhaustive, didactic review of some of the main concepts and approaches related to the use of molecularly modified metal nanoparticles in or as chemical sensors. This paper attempts to pull together different views and terminologies used in sensors based on molecularly modified metal nanoparticles, including those established upon electrochemical, optical, surface Plasmon resonance, piezoelectric and electrical transduction approaches. Finally, this paper discusses briefly the main advantages and disadvantages of each of the presented class of sensors. (review article)

  17. Potent inhibition of late stages of hepadnavirus replication by a modified cell penetrating peptide

    DEFF Research Database (Denmark)

    Abdul, Fabien; Ndeboko, Bénédicte; Buronfosse, Thierry;

    2012-01-01

    Cationic cell-penetrating peptides (CPPs) and their lipid domain-conjugates (CatLip) are agents for the delivery of (uncharged) biologically active molecules into the cell. Using infection and transfection assays we surprisingly discovered that CatLip peptides were able to inhibit replication of...... particle secretion. This is the first report showing that a CPP is able to drastically block hepadnaviral release from infected cells by altering late stages of viral morphogenesis via interference with enveloped particle formation, without affecting naked nucleocapsid egress, thus giving a view inside the...... mode of inhibition. Deca-(Arg)8 may be a useful tool for elucidating the hepadnaviral secretory pathway, which is not yet fully understood. Moreover we provide the first evidence that a modified CPP displays a novel antiviral mechanism targeting another step of viral life cycle compared to what has...

  18. Reduced chemically modified graphene oxide for supercapacitor electrode

    OpenAIRE

    Rajagopalan, Balasubramaniyan; Chung, Jin Suk

    2014-01-01

    An efficient active material for supercapacitor electrodes is prepared by reacting potassium hydroxide (KOH) with graphene oxide followed by chemical reduction with hydrazine. The electrochemical performance of KOH treated graphene oxide reduced for 24 h (reduced chemically modified graphene oxide, RCMGO-24) exhibits a specific capacitance of 253 F g-1 at 0.2 A g-1 in 2 M H2SO4 compared to a value of 141 F g-1 for graphene oxide reduced for 24 h (RGO-24), and good cyclic stability up to 3,000...

  19. THE INDUSTRIAL UTILIZATION OF CHEMICAL MODIFIED AGRICULTURAL RESIDUES

    Institute of Scientific and Technical Information of China (English)

    FengXu; RuncangSun; HuaiyuZhan

    2004-01-01

    Various lignocellulosic materials such as wood, agricultural and forest residues has the potential to be valuable substitute for, or complement to, commercial sorbents for removing heavy metal ions or dyes from waste water or spilled oil from inland water or sea. More than 9 million tons of straw pulp are produced annually in china, which account for about 90% of the world's total straw pulp. However, huge quantity of remain straw is not used as industrial raw material and is burnt in the fields or on the side of road. These resources can be chemical modified such as acetylation. Modified straws have the characteristics of low cost, high capacity, quick uptake, and easy to desorb. This paper reviews the current status of the technology for modified agricultural residues, which focus on hemicellulose and cellulose. The potential of these natural sorbents in main industry is also indicated.

  20. THE INDUSTRIAL UTILIZATION OF CHEMICAL MODIFIED AGRICULTURAL RESIDUES

    Institute of Scientific and Technical Information of China (English)

    Feng Xu; Runcang Sun; Huaiyu Zhan

    2004-01-01

    Various lignocellulosic materials such as wood,agricultural and forest residues has the potential to be valuable substitute for, or complement to,commercial sorbents for removing heavy metal ions or dyes from waste water or spilled oil from inland water or sea. More than 9 million tons of straw pulp are produced annually in china, which account for about 90% of the world′s total straw pulp. However,huge quantity of remain straw is not used as industrial raw material and is burnt in the fields or on the side of road. These resources can be chemical modified such as acetylation. Modified straws have the characteristics of low cost, high capacity, quick uptake, and easy to desorb. This paper reviews the current status of the technology for modified agricultural residues, which focus on hemicellulose and cellulose. The potential of these natural sorbents in main industry is also indicated.

  1. Three-dimensional nanofibrillar surfaces covalently modified with tenascin-C-derived peptides enhance neuronal growth in vitro.

    Science.gov (United States)

    Ahmed, Ijaz; Liu, Hsing-Yin; Mamiya, Ping C; Ponery, Abdul S; Babu, Ashwin N; Weik, Thom; Schindler, Melvin; Meiners, Sally

    2006-03-15

    Current methods to promote growth of cultured neurons use two-dimensional (2D) glass or polystyrene surfaces coated with a charged molecule (e.g. poly-L-lysine (PLL)) or an isolated extracellular matrix (ECM) protein (e.g. laminin-1). However, these 2D surfaces represent a poor topological approximation of the three-dimensional (3D) architecture of the assembled ECM that regulates neuronal growth in vivo. Here we report on the development of a new 3D synthetic nanofibrillar surface for the culture of neurons. This nanofibrillar surface is composed of polyamide nanofibers whose organization mimics the porosity and geometry of the ECM. Neuronal adhesion and neurite outgrowth from cerebellar granule, cerebral cortical, hippocampal, motor, and dorsal root ganglion neurons were similar on nanofibers and PLL-coated glass coverslips; however, neurite generation was increased. Moreover, covalent modification of the nanofibers with neuroactive peptides derived from human tenascin-C significantly enhanced the ability of the nanofibers to facilitate neuronal attachment, neurite generation, and neurite extension in vitro. Hence the 3D nanofibrillar surface provides a physically and chemically stabile cell culture surface for neurons and, potentially, an exciting new opportunity for the development of peptide-modified matrices for use in strategies designed to encourage axonal regrowth following central nervous system injury. PMID:16345089

  2. Peptide Conjugation to a Polymer Coating via Native Chemical Ligation of Azlactones for Cell Culture.

    Science.gov (United States)

    Schmitt, Samantha K; Trebatoski, David J; Krutty, John D; Xie, Angela W; Rollins, Benjamin; Murphy, William L; Gopalan, Padma

    2016-03-14

    Conjugation of biomolecules for stable presentation is an essential step toward reliable chemically defined platforms for cell culture studies. In this work, we describe the formation of a stable and site-specific amide bond via the coupling of a cysteine terminated peptide at low concentration to an azlactone containing copolymer coating. A copolymer of polyethylene glycol methyl ether methacrylate-ran-vinyl azlactone-ran-glycidyl methacrylate P(PEGMEMA-r-VDM-r-GMA) was used to form a thin coating (20-30 nm) on silicon and polycarbonate substrates. The formation and stability of coating-peptide bonds for peptides containing free thiols and amines were quantified by X-ray photoelectron spectroscopy (XPS) after exposure to cell culture conditions. Peptides containing a thiol as the only nucleophile coupled via a thioester bond; however, the bond was labile under cell culture conditions and almost all the bound peptides were displaced from the surface over a period of 2 days. Coupling with N-terminal primary amine peptides resulted in the formation of an amide bond with low efficiency (<20%). In contrast, peptides containing an N-terminal cysteine, which contain both nucleophiles (free thiol and amine) in close proximity, bound with 67% efficiency under neutral pH, and were stable under the same conditions for 2 weeks. Control studies confirm that the stable amide formation was a result of an intramolecular rearrangement through a N-acyl intermediate that resembles native chemical ligation. Through a combination of XPS and cell culture studies, we show that the cysteine terminated peptides undergo a native chemical ligation process at low peptide concentration in aqueous media, short reaction time, and at room temperature resulting in the stable presentation of peptides beyond 2 weeks for cell culture studies. PMID:26835552

  3. Film forming capacity of chemically modified corn starches.

    Science.gov (United States)

    López, Olivia V; García, María A; Zaritzky, Noemí E

    2008-09-01

    Native starch can be chemically modified to improve its functionality and to expand its uses. Modified starches were characterized and the rheological behavior of filmogenic suspensions was analyzed. The film forming capacity of different chemical modified corn starches was evaluated. Acetylated starch was selected by the characteristics of the resulted films; its optimum concentration was 5% w/w since their films exhibited the lowest water vapor permeability (WVP, 1.26×10(-10)g/msPa). The effect of glycerol as plasticizer on film properties depend on its concentration, being 1.5% w/w those that allows to obtain the lowest WVP value (1.64×10(-11)g/msPa), low film solubility in water and a more compact structure than those of unplasticized films. Mechanical behavior of plasticized acetylated starch films depends on glycerol concentration, being rigid and brittle the unplasticized ones, ductile those containing 1.5% w/w of glycerol and very flexible those with a higher plasticizer content. PMID:26048223

  4. CHEMICALLY MODIFIED ZEOLITES: SURFACES AND INTERACTION WITH Cs AND Co

    Directory of Open Access Journals (Sweden)

    Pavel Dillinger

    2007-06-01

    Full Text Available Inorganic exchangers, including zeolites, have interesting properties such as resistance to decomposition in the presence of ionizing radiation or to high temperatures, what make them applicable for the purification of low and middle polluted radioactive waste waters. The research was focused on model radioactive waste effluents and the investigated metals were cobalt (Co and cesium (Cs. The performance of natural zeolite of clinoptilolite type and zeolite chemically modified with NaOH solutions was determined by studying their surface and sorption properties using volumetric method and static radioindicator method. The measurements of zeolite´s surfaces showed the double increase of the specific surface along with an increase of mesopore’s diameter. The reason is the extraction of silicon from zeolite caused by NaOH solution what creates secondary mesoporous structure. The radioactive tracer technique was used to evaluate sorption properties of zeolites and the best sorbent was selected based on KD, μ, Γ and S values. The sorption abilities of natural and chemically modified zeolites for Cs uptake were comparable. The uptake of Co with natural zeolite was negligible and it increased up to 14 times for modified zeolites depending on the concentration of treated NaOH solution.

  5. Controlling Peptide Self-Assembly through a Native Chemical Ligation/Desulfurization Strategy.

    Science.gov (United States)

    Rasale, Dnyaneshwar B; Konda, Maruthi; Biswas, Sagar; Das, Apurba K

    2016-03-18

    Self-assembled peptides were synthesized by using a native chemical ligation (NCL)/desulfurization strategy that maintained the chemical diversity of the self-assembled peptides. Herein, we employed oxo-ester-mediated NCL reactions to incorporate cysteine, a cysteine-based dipeptide, and a sterically hindered unnatural amino acid (penicillamine) into peptides. Self-assembly of the peptides resulted in the formation of self-supporting gels. Microscopy analysis indicated the formation of helical nanofibers, which were responsible for the formation of gel matrices. The self-assembly of the ligated peptides was governed by covalent and non-covalent interactions, as confirmed by FTIR, CD, fluorescence spectroscopy, and MS (ESI) analyses. Peptide disassembly was induced by desulfurization reactions with tris(2-carboxyethyl)phosphine (TCEP) and glutathione at 80 °C. Desulfurization reactions of the ligated peptides converted the Cys and penicillamine functionalities into Ala and Val moieties, respectively. The self-supporting gels showed significant shear-thinning and thixotropic properties. PMID:26808117

  6. Reaction of Phosphorylated and O-Glycosylated Peptides by Chemically Targeted Identification at Ambient Temperature

    OpenAIRE

    Rusnak, Felicia; Zhou, Jie; Hathaway, Gary M.

    2004-01-01

    Conditions for carrying out chemically targeted identification of peptides containing phosphorylated or glycosylated serine residues have been investigated. Ba(OH)2 was used at ambient temperature to catalyze the β-elimination reaction at 25°C. Nucleophilic addition of 2-aminoethanethiol was performed in both parallel and tandem experiments. The method was demonstrated by the reaction of β-casein tryptic digest phosphopeptides and an O-glycosylated peptide. Contrary to an earlier report by ot...

  7. Adsorption study of copper (II) by chemically modified orange peel

    International Nuclear Information System (INIS)

    An adsorbent, the chemically modified orange peel, was prepared from hydrolysis of the grafted copolymer, which was synthesized by interaction of methyl acrylate with cross-linking orange peel. The presence of poly (acrylic acid) on the biomass surface was verified by infrared spectroscopy (IR), scanning electron microscopy (SEM) and thermogravimetry (TG). Total negative charge in the biomass surface and the zeta potentials were determined. The modified biomass was found to present high adsorption capacity and fast adsorption rate for Cu (II). From Langmuir isotherm, the adsorption capacity for Cu (II) was 289.0 mg g-1, which is about 6.5 times higher than that of the unmodified biomass. The kinetics for Cu (II) adsorption followed the pseudo-second-order kinetics. The adsorbent was used to remove Cu (II) from electroplating wastewater and was suitable for repeated use for more than four cycles.

  8. Chemical sensors using peptide-functionalized conducting polymer nanojunction arrays

    Science.gov (United States)

    Aguilar, Alvaro Díaz; Forzani, Erica S.; Li, Xiulan; Tao, Nongjian; Nagahara, Larry A.; Amlani, Islamshah; Tsui, Raymond

    2005-11-01

    We demonstrate a heavy metal-ion sensor for drinking water analysis using a conducting polymer nanojunction array. Each nanojunction is formed by bridging a pair of nanoelectrodes separated with a small gap (sensor is based on the change in the nanojunction conductance as a result of polymer conformational changes induced by the metal-ion chelating peptide. The nanojunction sensor allows real-time detection of Cu2+ and Ni2+ at ppt range.

  9. Chemically modified tetracyclines: The novel host modulating agents.

    Science.gov (United States)

    Swamy, Devulapalli Narasimha; Sanivarapu, Sahitya; Moogla, Srinivas; Kapalavai, Vasavi

    2015-01-01

    Periodontal pathogens and destructive host responses are involved in the initiation and progression of periodontitis. The emergence of host response modulation as a treatment concept has resulted from our improved understanding of the pathogenesis of periodontal disease. A variety of drugs have been evaluated as host modulation agents (HMA), including Non Steroidal Anti Inflammatory Drugs (NSAIDS), bisphosphonates, tetracyclines, enamel matrix proteins and bone morphogenetic proteins. Chemically modified tetracyclines (CMTs) are one such group of drugs which have been viewed as potential host modulating agents by their anticollagenolytic property. The CMTs are designed to be more potent inhibitors of pro inflammatory mediators and can increase the levels of anti inflammatory mediators. PMID:26392682

  10. Chemically modified tetracyclines: The novel host modulating agents

    Directory of Open Access Journals (Sweden)

    Devulapalli Narasimha Swamy

    2015-01-01

    Full Text Available Periodontal pathogens and destructive host responses are involved in the initiation and progression of periodontitis. The emergence of host response modulation as a treatment concept has resulted from our improved understanding of the pathogenesis of periodontal disease. A variety of drugs have been evaluated as host modulation agents (HMA, including Non Steroidal Anti Inflammatory Drugs (NSAIDS, bisphosphonates, tetracyclines, enamel matrix proteins and bone morphogenetic proteins. Chemically modified tetracyclines (CMTs are one such group of drugs which have been viewed as potential host modulating agents by their anticollagenolytic property. The CMTs are designed to be more potent inhibitors of pro inflammatory mediators and can increase the levels of anti inflammatory mediators.

  11. Probing Chromatin-modifying Enzymes with Chemical Tools

    KAUST Repository

    Fischle, Wolfgang

    2016-02-04

    Chromatin is the universal template of genetic information in all eukaryotic organisms. Chemical modifications of the DNA-packaging histone proteins and the DNA bases are crucial signaling events in directing the use and readout of eukaryotic genomes. The enzymes that install and remove these chromatin modifications as well as the proteins that bind these marks govern information that goes beyond the sequence of DNA. Therefore, these so-called epigenetic regulators are intensively studied and represent promising drug targets in modern medicine. We summarize and discuss recent advances in the field of chemical biology that have provided chromatin research with sophisticated tools for investigating the composition, activity, and target sites of chromatin modifying enzymes and reader proteins.

  12. Importance of asparagine on the conformational stability and chemical reactivity of selected anti-inflammatory peptides

    Energy Technology Data Exchange (ETDEWEB)

    Soriano-Correa, Catalina, E-mail: csorico@comunidad.unam.mx [Química Computacional, Facultad de Estudios Superiores (FES)-Zaragoza, Universidad Nacional Autónoma de México (UNAM), Iztapalapa, C.P. 09230 México, D.F. (Mexico); Barrientos-Salcedo, Carolina [Laboratorio de Química Médica y Quimiogenómica, Facultad de Bioanálisis Campus Veracruz-Boca del Río, Universidad Veracruzana, C.P. 91700 Veracruz (Mexico); Campos-Fernández, Linda; Alvarado-Salazar, Andres [Química Computacional, Facultad de Estudios Superiores (FES)-Zaragoza, Universidad Nacional Autónoma de México (UNAM), Iztapalapa, C.P. 09230 México, D.F. (Mexico); Esquivel, Rodolfo O. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa (UAM-Iztapalapa), C.P. 09340 México, D.F. (Mexico)

    2015-08-18

    Highlights: • Asparagine plays an important role to anti-inflammatory effect of peptides. • The electron-donor substituent groups favor the formation of the hydrogen bonds, which contribute in the structural stability of peptides. • Chemical reactivity and the physicochemical features are crucial in the biological functions of peptides. - Abstract: Inflammatory response events are initiated by a complex series of molecular reactions that generate chemical intermediaries. The structure and properties of peptides and proteins are determined by the charge distribution of their side chains, which play an essential role in its electronic structure and physicochemical properties, hence on its biological functionality. The aim of this study was to analyze the effect of changing one central amino acid, such as substituting asparagine for aspartic acid, from Cys–Asn–Ser in aqueous solution, by assessing the conformational stability, physicochemical properties, chemical reactivity and their relationship with anti-inflammatory activity; employing quantum-chemical descriptors at the M06-2X/6-311+G(d,p) level. Our results suggest that asparagine plays a more critical role than aspartic acid in the structural stability, physicochemical features, and chemical reactivity of these tripeptides. Substituent groups in the side chain cause significant changes on the conformational stability and chemical reactivity, and consequently on their anti-inflammatory activity.

  13. Importance of asparagine on the conformational stability and chemical reactivity of selected anti-inflammatory peptides

    International Nuclear Information System (INIS)

    Highlights: • Asparagine plays an important role to anti-inflammatory effect of peptides. • The electron-donor substituent groups favor the formation of the hydrogen bonds, which contribute in the structural stability of peptides. • Chemical reactivity and the physicochemical features are crucial in the biological functions of peptides. - Abstract: Inflammatory response events are initiated by a complex series of molecular reactions that generate chemical intermediaries. The structure and properties of peptides and proteins are determined by the charge distribution of their side chains, which play an essential role in its electronic structure and physicochemical properties, hence on its biological functionality. The aim of this study was to analyze the effect of changing one central amino acid, such as substituting asparagine for aspartic acid, from Cys–Asn–Ser in aqueous solution, by assessing the conformational stability, physicochemical properties, chemical reactivity and their relationship with anti-inflammatory activity; employing quantum-chemical descriptors at the M06-2X/6-311+G(d,p) level. Our results suggest that asparagine plays a more critical role than aspartic acid in the structural stability, physicochemical features, and chemical reactivity of these tripeptides. Substituent groups in the side chain cause significant changes on the conformational stability and chemical reactivity, and consequently on their anti-inflammatory activity

  14. Chemically and biologically synthesized CPP-modified gelonin for enhanced anti-tumor activity.

    Science.gov (United States)

    Shin, Meong Cheol; Zhang, Jian; David, Allan E; Trommer, Wolfgang E; Kwon, Young Min; Min, Kyoung Ah; Kim, Jin H; Yang, Victor C

    2013-11-28

    The ineffectiveness of small molecule drugs against cancer has generated significant interest in more potent macromolecular agents. Gelonin, a plant-derived toxin that inhibits protein translation, has attracted much attention in this regard. Due to its inability to internalize into cells, however, gelonin exerts only limited tumoricidal effect. To overcome this cell membrane barrier, we modified gelonin, via both chemical conjugation and genetic recombination methods, with low molecular weight protamine (LMWP), a cell-penetrating peptide (CPP) which was shown to efficiently ferry various cargoes into cells. Results confirmed that gelonin-LMWP chemical conjugate (cG-L) and recombinant gelonin-LMWP chimera (rG-L) possessed N-glycosidase activity equivalent to that of unmodified recombinant gelonin (rGel); however, unlike rGel, both gelonin-LMWPs were able to internalize into cells. Cytotoxicity studies further demonstrated that cG-L and rG-L exhibited significantly improved tumoricidal effects, with IC50 values being 120-fold lower than that of rGel. Moreover, when tested against a CT26 s.c. xenograft tumor mouse model, significant inhibition of tumor growth was observed with rG-L doses as low as 2 μg/tumor, while no detectable therapeutic effects were seen with rGel at 10-fold higher doses. Overall, this study demonstrated the potential of utilizing CPP-modified gelonin as a highly potent anticancer drug to overcome limitations of current chemotherapeutic agents. PMID:23973813

  15. Total Chemical Synthesis of a Heterodimeric Interchain Bis-Lactam-Linked Peptide: Application to an Analogue of Human Insulin-Like Peptide 3

    Science.gov (United States)

    Karas, John; Shabanpoor, Fazel; Hossain, Mohammed Akhter; Wade, John D.; Scanlon, Denis B.

    2013-01-01

    Nonreducible cystine isosteres represent important peptide design elements in that they can maintain a near-native tertiary conformation of the peptide while simultaneously extending the in vitro and in vivo half-life of the biomolecule. Examples of these cystine mimics include dicarba, diselenide, thioether, triazole, and lactam bridges. Each has unique physicochemical properties that impact upon the resulting peptide conformation. Each also requires specific conditions for its formation via chemical peptide synthesis protocols. While the preparation of peptides containing two lactam bonds within a peptide is technically possible and reported by others, to date there has been no report of the chemical synthesis of a heterodimeric peptide linked by two lactam bonds. To examine the feasibility of such an assembly, judicious use of a complementary combination of amine and acid protecting groups together with nonfragment-based, total stepwise solid phase peptide synthesis led to the successful preparation of an analogue of the model peptide, insulin-like peptide 3 (INSL3), in which both of the interchain disulfide bonds were replaced with a lactam bond. An analogue containing a single disulfide-substituted interchain lactam bond was also prepared. Both INSL3 analogues retained significant cognate RXFP2 receptor binding affinity. PMID:24288548

  16. Total Chemical Synthesis of a Heterodimeric Interchain Bis-Lactam-Linked Peptide: Application to an Analogue of Human Insulin-Like Peptide 3

    Directory of Open Access Journals (Sweden)

    John Karas

    2013-01-01

    Full Text Available Nonreducible cystine isosteres represent important peptide design elements in that they can maintain a near-native tertiary conformation of the peptide while simultaneously extending the in vitro and in vivo half-life of the biomolecule. Examples of these cystine mimics include dicarba, diselenide, thioether, triazole, and lactam bridges. Each has unique physicochemical properties that impact upon the resulting peptide conformation. Each also requires specific conditions for its formation via chemical peptide synthesis protocols. While the preparation of peptides containing two lactam bonds within a peptide is technically possible and reported by others, to date there has been no report of the chemical synthesis of a heterodimeric peptide linked by two lactam bonds. To examine the feasibility of such an assembly, judicious use of a complementary combination of amine and acid protecting groups together with nonfragment-based, total stepwise solid phase peptide synthesis led to the successful preparation of an analogue of the model peptide, insulin-like peptide 3 (INSL3, in which both of the interchain disulfide bonds were replaced with a lactam bond. An analogue containing a single disulfide-substituted interchain lactam bond was also prepared. Both INSL3 analogues retained significant cognate RXFP2 receptor binding affinity.

  17. A Modified Peptide Stimulation Method for Efficient Amplification of Cytomegalovirus (CMV)-Specific CTLs

    Institute of Scientific and Technical Information of China (English)

    Guangping Ruan; Li Ma; Qian Wen; Wei Luo; Mingqian Zhou; Xiaoning Wang

    2008-01-01

    CMV-specific immunity is essential for control of human cytomegalovirus (HCMV) infection. Stem cell trans- plantation is used widely in the management of a range of diseases of the hemopoietic system. Patients are immunosuppressed profoundly in the early posttransplant period, and reactivation of cytomegalovirus (CMV) remains a significant cause of morbidity and mortality. Adoptive transfer of CMV-specific CD8+ T cell clones has been shown to reduce the rate of viral reactivation; however, the ex vivo production of cells for adoptive transfer is labor intensive and expensive. We report here a modified peptide stimulation method using CMV-specific epitope peptides to stimulate PBMCs for generation of CMV-specific CTLs. This method permits efficient amplification of CMV-specific CTLs and provides a large number of cells for FACS analysis from a single blood sample. Significantly, it achieves high frequencies of tetramer staining of CD8+ T cells allowing the data of different individuals to be easily compared and sequentially evaluated. Thus, this approach expands and selects HLA- restricted CMV-pp65-reactive T-cell lines of high specificity for potential adoptive immunotherapy. Cellular & Molecular Immunology. 2008;5(3):197-201.

  18. Peptide modified polymer poly (glycerol- dodecanedioate co-fumarate) for efficient control of motor neuron differentiation.

    Science.gov (United States)

    Dai, Xizi; Huang, Yen-Chih; Leichner, Jared; Nair, Madhvan; Lin, Wei-Chiang; Li, Chen-Zhong

    2015-12-01

    Neural tissue engineering is one of the most promising approaches for healing nerve damage, which bypasses the limits of contemporary conventional treatments. In a previous study, we developed a fibrous scaffold via electrospinning poly (glycerol dodecanedioate) (PGD) and gelatin that mimics the structure of a native extracellular matrix (ECM) for soft tissue engineering application. In this study, fumaric acid (FA) was incorporated into the PGD synthesis process, which produced a PGD derivative referred to as poly (glycerol dodecanedioate co-fumarate) (PGDF). This introduced a new functional group, a double bond, into the polymer thus providing new modification possibilities. Arg-Gly-Asp-Cys (RGDC) and laminin peptides were chosen as biomolecules to modify the fiber and facilitate cell attachment and differentiation efficiency. The release of FA into the medium was quantified to investigate the bioreactivity of the derived scaffolds. In combination with UV crosslinking, the developed PGDF fiber mats were able to withstand degradation processes for up to 2 months, which ensures that neural tissue engineering applications are viable. Cell viability and motor neuron differentiation efficiency were demonstrated to be significantly improved with the addition of FA, RGDC and laminin peptides. PMID:26584592

  19. B and C types natriuretic peptides modify norepinephrine uptake and release in the rat adrenal medulla.

    Science.gov (United States)

    Vatta, M S; Presas, M F; Bianciotti, L G; Rodriguez-Fermepin, M; Ambros, R; Fernandez, B E

    1997-01-01

    We have previously reported that atrial natriuretic factor (ANF) modulates adrenomedullar norepinephrine (NE) metabolism. On this basis, the aim of the present work was to study the effects of B and C types natriuretic peptides (BNP and CNP) on the uptake, intracellular distribution and release of 3H-NE. Experiments were carried out in rat adrenal medulla slices incubated "in vitro." Results showed that 100 nM of both, CNP and BNP, enhanced total and neuronal NE uptake. Both peptides (100 nM) caused a rapid increase in NE uptake during the first minute, which was sustained for 60 min. NE intracellular distribution was only modified by CNP (100 nM), which increased the granular fraction and decreased the cytosolic pool. On the other hand, spontaneous as well as evoked (KCl) NE release, was decreased by BNP and CNP (50 and 100 nM for spontaneous release and 1, 10, 50 and 100 nM for evoked output). The present results suggest that BNP and CNP may regulate catecholamine secretion and modulate adrenomedullary biological actions mediated by catecholamines, such as blood arterial pressure, smooth muscle tone, and metabolic activities. PMID:9437706

  20. Maltodextrins from chemically modified starches. Selected physicochemical properties.

    Science.gov (United States)

    Pycia, Karolina; Juszczak, Lesław; Gałkowska, Dorota; Witczak, Mariusz; Jaworska, Grażyna

    2016-08-01

    The aim of this work was to evaluate the effect of chemical modification of starch (cross-linking and/or stabilisation) on selected rheological and functional properties of maltodextrins of dextrose equivalent of 6, 11 and 16. It was found that values of glass transition temperatures were decreasing with dextrose equivalent of maltodextrin. The highest values of glass transition temperature (TG) were determined for maltodextrin of DE 6-obtained from distarch phosphate and acetylated distarch phosphate. Increase in DE value of maltodextrin was also accompanied by decrease and increase in values of intrinsic viscosity and the critical concentration, respectively; however, there was no significant effect of kind of chemical modification of starch on the values of these parameters. Maltodextrin solutions at concentrations of from 10 to 70 % exhibited Newtonian flow behaviour. In the case of 50% solutions of maltodextrins of DE 6 the highest viscosity was produced by maltodextrin from native potato starch, while the lowest one by maltodextrin from acetylated starch. On the other hand, among the maltodextrin of DE 11 this one produced from acetylated starch showed the highest viscosity. All the maltodextrins exhibited surfactant properties in a water-air system, with the strongest effect observed for maltodextrins produced from double chemically modified starches and from acetylated starch. The surface activity was increasing with increasing of the DE value of maltodextrin. Moreover, values of surface tension were decreasing with increasing in maltodextrin concentration in the system. PMID:27112878

  1. Application of Celluspots peptide arrays for the analysis of the binding specificity of epigenetic reading domains to modified histone tails

    Directory of Open Access Journals (Sweden)

    Dhayalan Arunkumar

    2011-08-01

    Full Text Available Abstract Background Epigenetic reading domains are involved in the regulation of gene expression and chromatin state by interacting with histones in a post-translational modification specific manner. A detailed knowledge of the target modifications of reading domains, including enhancing and inhibiting secondary modifications, will lead to a better understanding of the biological signaling processes mediated by reading domains. Results We describe the application of Celluspots peptide arrays which contain 384 histone peptides carrying 59 post translational modifications in different combinations as an inexpensive, reliable and fast method for initial screening for specific interactions of reading domains with modified histone peptides. To validate the method, we tested the binding specificities of seven known epigenetic reading domains on Celluspots peptide arrays, viz. the HP1ß and MPP8 Chromo domains, JMJD2A and 53BP1 Tudor domains, Dnmt3a PWWP domain, Rag2 PHD domain and BRD2 Bromo domain. In general, the binding results agreed with literature data with respect to the primary specificity of the reading domains, but in almost all cases we obtained additional new information concerning the influence of secondary modifications surrounding the target modification. Conclusions We conclude that Celluspots peptide arrays are powerful screening tools for studying the specificity of putative reading domains binding to modified histone peptides.

  2. Modelling Amperometric Biosensors Based on Chemically Modified Electrodes

    Science.gov (United States)

    Baronas, Romas; Kulys, Juozas

    2008-01-01

    The response of an amperometric biosensor based on a chemically modified electrode was modelled numerically. A mathematical model of the biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments: an enzyme layer and an outer diffusion layer. In order to define the main governing parameters the corresponding dimensionless mathematical model was derived. The digital simulation was carried out using the finite difference technique. The adequacy of the model was evaluated using analytical solutions known for very specific cases of the model parameters. By changing model parameters the output results were numerically analyzed at transition and steady state conditions. The influence of the substrate and mediator concentrations as well as of the thicknesses of the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially when the biosensor acts under a mixed limitation of the diffusion and the enzyme interaction with the substrate.

  3. 12-Tungstophosphates Immobilized on Chemically Modified Mesoporous Silica SBA-15

    Institute of Scientific and Technical Information of China (English)

    ZHU Jing; YOU Wan-sheng; ZHU Zai-ming; SUN Zhen-gang; ZHANG Lan-cui; GU Yuan-peng

    2005-01-01

    A functionalized material, PW/SBA-15m, was prepared successfully in diluted H2SO4 aqueous solutions by immobilizing 12-tungstophosphates on chemically modified mesoporous silica SBA-15 and characterized by elemental analysis, FTIR, 31P MAS NMR, XRD and TEM. The results indicate that the framework of SBA-15 and the Keggin structure of PW12O3-40 were retained, and that 23%-33%(mass fraction) of PW12O3-40 was immobilized; the PW12O3-40 anions were finely dispersed on the pore wall of SBA-15. Having been leached in ethanol at 60 ℃ for 7 h, the loss of PW12O3-40 anions was not found.

  4. Highly efficient adsorption of chlorophenols onto chemically modified chitosan

    Science.gov (United States)

    Zhou, Liang-Chun; Meng, Xiang-Guang; Fu, Jing-Wei; Yang, Yu-Chong; Yang, Peng; Mi, Chun

    2014-02-01

    A novel chemically modified chitosan CS-SA-CD with phenol and β-cyclodextrin groups was prepared. The adsorptions of phenol, 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) on the functional chitosan from aqueous solution were investigated. CS-SA-CD exhibited excellent adsorption ability for chlorophenols especially for DCP and TCP. The maximum adsorption capacities of phenol, 2-CP, 4-CP, DCP and TCP on CS-SA-CD were 59.74, 70.52, 96.43, 315.46 and 375.94 mg/g, respectively. The scanning electron microscope and Brunauer-Emmett-Teller analyses revealed that the introduction of phenol group changed the surface morphology and surface properties of chitosan. The modified chitosan CS-SA-CD possesses larger surface areas (4.72 m2/g), pore volume (7.29 × 10-3 mL/g) and average pore diameter (59.99 Å) as compared to those of chitosan 3.27 m2/g, 2.00 × 10-3 mL/g and 15.95 Å, respectively. The enhanced adsorption of chlorophenols was also attributed to the interaction of hydrogen bond between Cl atom and sbnd OH group. The adsorption of chlorophenols on CS-SA-CD followed the pseudo-second-order kinetic model. Adsorbent could be regenerated easily and the regenerated CS-SA-CD remained 80-91% adsorption efficiency.

  5. Highly efficient adsorption of chlorophenols onto chemically modified chitosan

    International Nuclear Information System (INIS)

    A novel chemically modified chitosan CS-SA-CD with phenol and β-cyclodextrin groups was prepared. The adsorptions of phenol, 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) on the functional chitosan from aqueous solution were investigated. CS-SA-CD exhibited excellent adsorption ability for chlorophenols especially for DCP and TCP. The maximum adsorption capacities of phenol, 2-CP, 4-CP, DCP and TCP on CS-SA-CD were 59.74, 70.52, 96.43, 315.46 and 375.94 mg/g, respectively. The scanning electron microscope and Brunauer–Emmett–Teller analyses revealed that the introduction of phenol group changed the surface morphology and surface properties of chitosan. The modified chitosan CS-SA-CD possesses larger surface areas (4.72 m2/g), pore volume (7.29 × 10−3 mL/g) and average pore diameter (59.99 Å) as compared to those of chitosan 3.27 m2/g, 2.00 × 10−3 mL/g and 15.95 Å, respectively. The enhanced adsorption of chlorophenols was also attributed to the interaction of hydrogen bond between Cl atom and -OH group. The adsorption of chlorophenols on CS-SA-CD followed the pseudo-second-order kinetic model. Adsorbent could be regenerated easily and the regenerated CS-SA-CD remained 80–91% adsorption efficiency.

  6. Iodinated derivatives of vasoactive intestinal peptide (VIP), PHI and PHM: purification, chemical characterization and biological activity

    International Nuclear Information System (INIS)

    The iodination of vasoactive intestinal peptide (VIP) was studied, using a variety of enzymatic and chemical iodination methods. Reversed phase high performance liquid chromatography (HPLC) was used to purify the reaction products. The lactoperoxidase-glucose oxidase method gave excellent results in terms of reproducibility, iodine incorporation, and yield of the non-oxidized products [Tyr(I)10]VIP and [Tyr(I)22]VIP, and was used to prepare both 125I and 127I labelled derivatives. In both cases, direct application to HPLC and a single column system were used. Although the oxidized peptides [Tyr(I)10,Met(O)17]VIP and [Tyr(I)22,Met(O)17]VIP could be generated to varying degrees directly by iodination of VIP, these were most conveniently prepared by iodination of [Met(O)17]VIP. Iodinated derivatives of the homologous peptides PHI and PHM were likewise prepared by rapid, one-step HPLC procedures. The site and degree of iodination were determined by HPLC peptide mapping of tryptic digests and amino acid analyses, and in the case of [Tyr(I)10]VIP also by sequencing. The vasorelaxant activities of the iodinated peptides in bovine cerebral artery preparations did not differ significantly from those of the corresponding noniodinated peptides, with the exception of [Tyr(I)10,Met(O)17]VIP and [Tyr(I)22,Met(O)17]VIP which, unlike [Met(O)17]VIP itself, had slightly lower potency than VIP

  7. High stability of self-assembled peptide nanowires against thermal, chemical, and proteolytic attacks.

    Science.gov (United States)

    Ryu, Jungki; Park, Chan Beum

    2010-02-01

    Understanding the self-assembly of peptides into ordered nanostructures is recently getting much attention since it can provide an alternative route for fabricating novel bio-inspired materials. In order to realize the potential of the peptide-based nanofabrication technology, however, more information is needed regarding the integrity or stability of peptide nanostructures under the process conditions encountered in their applications. In this study, we investigated the stability of self-assembled peptide nanowires (PNWs) and nanotubes (PNTs) against thermal, chemical, proteolytic attacks, and their conformational changes upon heat treatment. PNWs and PNTs were grown by the self-assembly of diphenylalanine (Phe-Phe), a peptide building block, on solid substrates at different chemical atmospheres and temperatures. The incubation of diphenylalanine under aniline vapor at 150 degrees C led to the formation of PNWs, while its incubation with water vapor at 25 degrees C produced PNTs. We analyzed the stability of peptide nanostructures using multiple tools, such as electron microscopy, thermal analysis tools, circular dichroism, and Fourier-transform infrared spectroscopy. Our results show that PNWs are highly stable up to 200 degrees C and remain unchanged when incubated in aqueous solutions (from pH 1 to 14) or in various chemical solvents (from polar to non-polar). In contrast, PNTs started to disintegrate even at 100 degrees C and underwent a conformational change at an elevated temperature. When we further studied their resistance to a proteolytic environment, we discovered that PNWs kept their initial structure while PNTs fully disintegrated. We found that the high stability of PNWs originates from their predominant beta-sheet conformation and the conformational change of diphenylalanine nanostructures. Our study suggests that self-assembled PNWs are suitable for future nano-scale applications requiring harsh processing conditions. PMID:19777585

  8. Highly efficient adsorption of chlorophenols onto chemically modified chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Liang-Chun [Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064 (China); National Center for Packaging Material Quality Supervision and Inspection, Chengdu Institute of Product Quality Supervision and Inspection, Chengdu 610064 (China); Meng, Xiang-Guang, E-mail: mengxgchem@163.com [Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064 (China); Fu, Jing-Wei [National Center for Packaging Material Quality Supervision and Inspection, Chengdu Institute of Product Quality Supervision and Inspection, Chengdu 610064 (China); Yang, Yu-Chong; Yang, Peng; Mi, Chun [Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064 (China)

    2014-02-15

    A novel chemically modified chitosan CS-SA-CD with phenol and β-cyclodextrin groups was prepared. The adsorptions of phenol, 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) on the functional chitosan from aqueous solution were investigated. CS-SA-CD exhibited excellent adsorption ability for chlorophenols especially for DCP and TCP. The maximum adsorption capacities of phenol, 2-CP, 4-CP, DCP and TCP on CS-SA-CD were 59.74, 70.52, 96.43, 315.46 and 375.94 mg/g, respectively. The scanning electron microscope and Brunauer–Emmett–Teller analyses revealed that the introduction of phenol group changed the surface morphology and surface properties of chitosan. The modified chitosan CS-SA-CD possesses larger surface areas (4.72 m{sup 2}/g), pore volume (7.29 × 10{sup −3} mL/g) and average pore diameter (59.99 Å) as compared to those of chitosan 3.27 m{sup 2}/g, 2.00 × 10{sup −3} mL/g and 15.95 Å, respectively. The enhanced adsorption of chlorophenols was also attributed to the interaction of hydrogen bond between Cl atom and -OH group. The adsorption of chlorophenols on CS-SA-CD followed the pseudo-second-order kinetic model. Adsorbent could be regenerated easily and the regenerated CS-SA-CD remained 80–91% adsorption efficiency.

  9. Modelling Amperometric Biosensors Based on Chemically Modified Electrodes

    Directory of Open Access Journals (Sweden)

    Juozas Kulys

    2008-08-01

    Full Text Available The response of an amperometric biosensor based on a chemically modified electrode was modelled numerically. A mathematical model of the biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments: an enzyme layer and an outer diffusion layer. In order to define the main governing parameters the corresponding dimensionless mathematical model was derived. The digital simulation was carried out using the finite difference technique. The adequacy of the model was evaluated using analytical solutions known for very specific cases of the model parameters. By changing model parameters the output results were numerically analyzed at transition and steady state conditions. The influence of the substrate and mediator concentrations as well as of the thicknesses of the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially when the biosensor acts under a mixed limitation of the diffusion and the enzyme interaction with the substrate.

  10. Radiation modification of swollen and chemically modified cellulose

    International Nuclear Information System (INIS)

    Complete text of publication follows. Biodegradable hydrogel was produced by radiation-induced crosslinking of water soluble carboxymethyl cellulose. Mobility of the molecular chain was found to play an important role in the crosslinking reaction. In this work the role of cellulose chains' mobility in radiation-induced reactions of fibrous cellulose was studied. Mobility of chains was improved by swelling (in sodium hydroxide and tetramethylammonium hydroxide) and chemical modification (substitution of about 3 % of hydroxyl groups with carboxymethyl groups), respectively. All samples were neutralized after the treatments. Accessibility of cellulose characterized by water adsorption and retention was significantly improved by the treatments in the following order: sodium hydroxide < tetramethylammonium hydroxide < carboxymethylation. Less fibrillar structure of modified fibers was observed by electron microscope. Samples were irradiated in wet form in open air (10 kGy). Untreated sample coated with soluble CMC was also irradiated. Degree of polymerization, FTIR spectra, and water sorption of samples before and after irradiation are presented. Amount of water adsorbed on samples decreased after irradiation. It can be considered the consequence of crosslinks, which might improve the crease recovery ability of cotton fabric. High accessibility improved degradation rather than crosslinking of cellulose chains

  11. Selective and Sensitive Sensing of Flame Retardant Chemicals Through Phage Display Discovered Recognition Peptide.

    Science.gov (United States)

    Jin, Hyo-Eon; Zueger, Chris; Chung, Woo-Jae; Wong, Winnie; Lee, Byung Yang; Lee, Seung-Wuk

    2015-11-11

    We report a highly selective and sensitive biosensor for the detection of an environmentally toxic molecule, decabrominated diphenyl ether (DBDE), one of the most common congeners of the polybrominated frame retardants (polybrominated diphenyl ether (PBDE)), using newly discovered DBDE peptide receptors integrated with carbon nanotube field-effect transistors (CNT-FET). The specific DBDE peptide receptor was identified using a high-throughput screening process of phage library display. The resulting binding peptide carries an interesting consensus binding pocket with two Trp-His/Asn-Trp repeats, which binds to the DBDE in a multivalent manner. We integrated the novel DBDE binding peptide onto the CNT-FET using polydiacetylene coating materials linked through cysteine-maleimide click chemistry. The resulting biosensor could detect the desired DBDE selectively with a 1 fM detection limit. Our combined approaches of selective receptor discovery, material nanocoating through click chemistry, and integration onto a sensitive CNT-FET electronic sensor for desired target chemicals will pave the way toward the rapid development of portable and easy-to-use biosensors for desired chemicals to protect our health and environment. PMID:26455834

  12. Conformational Stability!? : Synthesis and Conformational Studies of Unnatural Backbone Modified Peptides

    OpenAIRE

    Norgren, Anna S.

    2006-01-01

    The beauty of the wide functionality of proteins and peptides in Nature is determined by their ability to adopt three-dimensional structures. This thesis describes artificial molecules developed to mimic secondary structures similar to those found crucial for biological activities. In the first part of this thesis, we focused on post-translational modifications of a class of unnatural oligomers known as β-peptides. Through the design and synthesis of a glycosylated β3-peptide, the first such ...

  13. Multi-Component Ion Modifiers and Arcing Suppressants to Enhance Differential Mobility Spectrometry for Separation of Peptides and Drug Molecules

    Science.gov (United States)

    Blagojevic, Voislav; Koyanagi, Gregory K.; Bohme, Diethard K.

    2014-03-01

    The optimization of ion/molecule chemistry in a differential mobility spectrometer (DMS) is shown to result in improved peak capacity, separation, and sensitivity. We have experimented with a modifier composed of multiple components, where each component accomplishes a specific task on mixtures of peptides and small drug molecules. Use of a higher proton affinity modifier (hexanol) provides increased peak capacity and separation. Analyte ion/modifier proton transfer is suppressed by adding a large excess of low proton affinity modifier (water or methanol), significantly increasing signal intensity and sensitivity for low proton affinity analytes. Finally, addition of an electrical arcing suppressant (chloroform) allows the device to operate reliably at higher separation fields, improving peak capacity and separation. We demonstrate a 20 % increase in the device peak capacity without any loss of sensitivity and estimate that further optimization of the modifier composition can increase this to 50 %. Use of 3-, 4-, or even 5-component modifiers offers the opportunity for the user to fine-tune the modifier performance to maximize the device performance, something not possible with a single component modifier.

  14. Efficient Synthesis of Peptide and Protein Functionalized Pyrrole-Imidazole Polyamides Using Native Chemical Ligation

    Directory of Open Access Journals (Sweden)

    Brian M. G. Janssen

    2015-06-01

    Full Text Available The advancement of DNA-based bionanotechnology requires efficient strategies to functionalize DNA nanostructures in a specific manner with other biomolecules, most importantly peptides and proteins. Common DNA-functionalization methods rely on laborious and covalent conjugation between DNA and proteins or peptides. Pyrrole-imidazole (Py–Im polyamides, based on natural minor groove DNA-binding small molecules, can bind to DNA in a sequence specific fashion. In this study, we explore the use of Py–Im polyamides for addressing proteins and peptides to DNA in a sequence specific and non-covalent manner. A generic synthetic approach based on native chemical ligation was established that allows efficient conjugation of both peptides and recombinant proteins to Py–Im polyamides. The effect of Py–Im polyamide conjugation on DNA binding was investigated by Surface Plasmon Resonance (SPR. Although the synthesis of different protein-Py–Im-polyamide conjugates was successful, attenuation of DNA affinity was observed, in particular for the protein-Py–Im-polyamide conjugates. The practical use of protein-Py–Im-polyamide conjugates for addressing DNA structures in an orthogonal but non-covalent manner, therefore, remains to be established.

  15. Peptide nanofibers modified with a protein by using designed anchor molecules bearing hydrophobic and functional moieties.

    Science.gov (United States)

    Miyachi, Ayaka; Takahashi, Tsuyoshi; Matsumura, Sachiko; Mihara, Hisakazu

    2010-06-11

    Self-assembly of peptides and proteins is a key feature of biological functions. Short amphiphilic peptides designed with a beta-sheet structure can form sophisticated nanofiber structures, and the fibers are available as nanomaterials for arranging biomolecules. Peptide FI (H-PKFKIIEFEP-OH) self-assembles into nanofibers with a coiled fine structure, as reported in our previous work. We have constructed anchor molecules that have both a binding moiety for the fiber structure and a functional unit capable of capturing target molecules, with the purpose of arranging proteins on the designed peptide nanofibers. Designed anchors containing an alkyl chain as a binding unit and biotin as a functional moiety were found to bind to peptide fibers FI and F2i (H-ALEAKFAAFEAKLA-NH(2)). The surface-exposed biotin moiety on the fibers could capture an anti-biotin antibody. Moreover, hydrophobic dipeptide anchor units composed of iminodiacetate connected to Phe-Phe or Ile-Ile and a peptide composed of six histidine residues connected to biotin could also connect FI peptide fibers to the anti-biotin antibody through the chelation of Ni(2+) ions. This strategy of using designed anchors opens a novel approach to constructing nanoscale protein arrays on peptide nanomaterials. PMID:20419712

  16. Bio-inspired Silicification of Silica-binding Peptide-Silk Protein Chimeras: Comparison of Chemically and Genetically Produced Proteins

    OpenAIRE

    Canabady-Rochelle, Laetitia L.S.; Belton, David J.; Deschaume, Olivier; Currie, Heather A.; Kaplan, David L; Perry, Carole C.

    2012-01-01

    Novel protein chimeras constituted of ‘silk’ and a silica-binding peptide (KSLSRHDHIHHH) were synthesized by genetic or chemical approaches and their influence on silica-silk based chimera composite formation evaluated. Genetic chimeras were constructed from 6 or 15 repeats of the 32 amino acid consensus sequence of Nephila clavipes spider silk ([SGRGGLGGQG AGAAAAAGGA GQGGYGGLGSQG]n) to which one silica binding peptide was fused at the N terminus. For the chemical chimera, 25 equivalents of t...

  17. Purification and identification of O-GlcNAc-modified peptides using phosphate-based alkyne CLICK chemistry in combination with titanium dioxide chromatography and mass spectrometry

    DEFF Research Database (Denmark)

    Parker, Benjamin L; Gupta, Pankaj; Cordwell, Stuart;

    2011-01-01

    -containing peptides were enriched using titanium dioxide chromatography. Modified peptides were analyzed using a combination of higher energy collision dissociation for identification and electron transfer dissociation to localize the site of O-GlcNAc attachment. The enrichment method was developed and...

  18. Chemical treatment of the intra-canal dentin surface: a new approach to modify dentin hydrophobicity

    OpenAIRE

    GAITAN-FONSECA, Cesar; COLLART-DUTILLEUL, Pierre-Yves; SEMETEY, Vincent; Olivier ROMIEU; Roel CRUZ; Flores, Hector; Frederic CUISINIER; Elias PEREZ; POZOS-GUILLEN, Amaury

    2013-01-01

    Objective This study evaluated the hydrophobicity of dentin surfaces that were modified through chemical silanization with octadecyltrichlorosilane (OTS). Material and Methods An in vitro experimental study was performed using 40 human permanent incisors that were divided into the following two groups: non-silanized and silanized. The specimens were pretreated and chemically modified with OTS. After the chemical modification, the dentin hydrophobicity was examined using a water contact angl...

  19. Uranium (Vi) sorption onto zirconium diphosphate chemically modified

    International Nuclear Information System (INIS)

    This work deals with the uranium (Vi) speciation after sorption onto zirconium diphosphate (ZrP2O7) surface, hydrated and in a surface modified with organic acids. Oxalic and citric acids were chosen to modify the ZrP2O7 surface because they have poly carboxylic groups and they mimic the organic matter in nature. Thus the interest of this work is to evaluate the uranium (Vi) sorption edge at different s ph values in natural and modified surfaces. The luminescence technique (fluorescence and phosphorescence, respectively) was used for the quantification and speciation of uranyl sorbed at the zirconium diphosphate interface. The fluorescence experiment, showed that adsorption of uranyl on surface of zirconium diphosphate tends to 100%. The speciation shows that there are different complexes in surface which were formed between zirconium diphosphate and uranyl, since it is produced a displacement of wavelength in fluorescence spectra of each system. (Author)

  20. Safety evaluation of chemically modified beta-lactoglobulin administered intravaginally.

    Science.gov (United States)

    Guo, Xuetao; Qiu, Lixia; Wang, Yonghong; Wang, Yue; Meng, Yuanguang; Zhu, Yun; Lu, Lu; Jiang, Shibo

    2016-06-01

    Currently, there is no specific antiviral therapy for treatment of HPV infection. Jiang and colleagues previously reported that anhydride-modified proteins have inhibitory activities against multiple viruses including HPV. Here, we evaluated the safety of 3-hydroxyphthalic anhydride-modified bovine beta-lactoglobulin, designated JB01, vaginally applied in women infected by high-risk HPV. After the vaginal application of JB01 in 38 women for 3 months, no serious adverse events were reported, and normalization of the vaginal micro-environment has been observed. It can be concluded that JB01-BD is safe for vaginal use in HPV-infected women, suggesting its potential application for the treatment of HPV infection. J. Med. Virol. 88:1098-1101, 2016. © 2015 Wiley Periodicals, Inc. PMID:26629967

  1. PreS2-TML peptide or guanidinium modified Gd-DOTA exhibits efficient cellular uptake

    OpenAIRE

    Wolf, Markus; Bauder-Wüst, Ulrike; Pipkorn, Rüdiger

    2006-01-01

    The majority of magnetic resonance contrast agents are restricted to the extracellular domains. For the development of novel, intracellular magnetic resonance contrast agents, we have designed Gd-DOTA derivatives comprising PreS2-TML peptide or ethylguanidinium as carrier moiety. Initial in vitro cell uptake studies with Jurkat cells revealed efficient contrast agent uptake for imaging purposes, in the range of 0.04 fmol/cell (PreS2-TML peptide) to 0.2 fmol/cell (ethylguanidinium) followin...

  2. Importance of asparagine on the conformational stability and chemical reactivity of selected anti-inflammatory peptides

    Science.gov (United States)

    Soriano-Correa, Catalina; Barrientos-Salcedo, Carolina; Campos-Fernández, Linda; Alvarado-Salazar, Andres; Esquivel, Rodolfo O.

    2015-08-01

    Inflammatory response events are initiated by a complex series of molecular reactions that generate chemical intermediaries. The structure and properties of peptides and proteins are determined by the charge distribution of their side chains, which play an essential role in its electronic structure and physicochemical properties, hence on its biological functionality. The aim of this study was to analyze the effect of changing one central amino acid, such as substituting asparagine for aspartic acid, from Cys-Asn-Ser in aqueous solution, by assessing the conformational stability, physicochemical properties, chemical reactivity and their relationship with anti-inflammatory activity; employing quantum-chemical descriptors at the M06-2X/6-311+G(d,p) level. Our results suggest that asparagine plays a more critical role than aspartic acid in the structural stability, physicochemical features, and chemical reactivity of these tripeptides. Substituent groups in the side chain cause significant changes on the conformational stability and chemical reactivity, and consequently on their anti-inflammatory activity.

  3. Development of a method for environmentally friendly chemical peptide synthesis in water using water-dispersible amino acid nanoparticles

    Directory of Open Access Journals (Sweden)

    Fukumori Yoshinobu

    2011-08-01

    Full Text Available Abstract Due to the vast importance of peptides in biological processes, there is an escalating need for synthetic peptides to be used in a wide variety of applications. However, the consumption of organic solvent is extremely large in chemical peptide syntheses because of the multiple condensation steps in organic solvents. That is, the current synthesis method is not environmentally friendly. From the viewpoint of green sustainable chemistry, we focused on developing an organic solvent-free synthetic method using water, an environmentally friendly solvent. Here we described in-water synthesis technology using water-dispersible protected amino acids.

  4. Improved pyrite rejection by chemically-modified fine coal flotation

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J.D.; Ye, Y.; Jin, R.

    1989-01-01

    Improved pyrite rejection during fine coal flotation can be achieved by chemical pretreatment of the coal prior to flotation. The process involves conditioning the suspension with potassium monopersulfate or other peroxy compounds followed by conventional flotation. The ambient-temperature treatment seems to improve the hydrophobic character of certain low-rank coals as is evident from induction time measurements and bench-scale flotation experiments. In addition, the chemical pretreatment leads to an improvement in ash rejection and to enhanced depression of pyrite. 23 refs., 9 figs., 2 tabs.

  5. Correlation between dynamic wetting behavior and chemical components of thermally modified wood

    International Nuclear Information System (INIS)

    Highlights: • We studied the dynamic wetting behavior of thermally modified wood by wetting models. • We found lower wetting speed of water droplets on thermally modified wood surface. • Dynamic wetting behavior and surface chemical components show a strong correlation. - Abstract: In order to investigate the dynamic wetting behavior of thermally modified wood, Cathay poplar (Populus cathayana Rehd.) and Scots pine (Pinus sylvestris L.) samples were thermally modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on modified and unmodified wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally modified wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of wood, expressed in lowing spread and penetration speed of water droplets on wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C1/C2 ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally modified wood

  6. Chemically modified carbon nanotubes as material enhanced laser desorption ionisation (MELDI) material in protein profiling

    International Nuclear Information System (INIS)

    Biomarkers play a potential role in the early detection and diagnosis of a disease. Our aim is to derivatize carbon nanotubes for exploration of the differences in human body fluids e.g. serum, through matrix assisted laser desorption ionisation/time of flight mass spectrometry (MALDI/TOF-MS) that can be related to disease and subsequently to be employed in the biomarker discovery process. This application we termed as the material enhanced laser desorption ionisation (MELDI). The versatility of this technology is meant to increase the amount of information from biological samples on the protein level, which will have a major impact to serve the cause of diagnostic markers. Serum peptides and proteins are immobilized on derivatized carbon nanotubes, which function as binding material. Protein-loaded suspension is placed on a stainless steel target or buckypaper on aluminum target for direct analysis with MALDI-MS. The elution method to wash the bound proteins from carbon nanotubes was employed to compare with the direct analysis procedure. Elution is carried out by MALDI matrix solution to get them out of the entangled nanotubes, which are difficult to desorb by laser due to the complex nanotube structures. The advantage of these optimized methods compared to the conventional screening methods is the improved sensitivity, selectivity and the short analysis time without prior albumin and immunoglobulin depletion. The comparison of similarly modified diamond and carbon nanotubes exhibit differences in their nature to bind the proteins out of serum due to the differences in their physical characteristics. Infrared (IR) spectroscopy provided hint for the presence of tertiary amine peak at the crucial chemical step of iminodiacetic acid addition to acid chloride functionality on carbon nanotubes. Atomic absorption spectroscopy (AAS) was utilized to quantitatively measure the copper capacity of these derivatized carbon nanotubes which is a direct measure of capacity of

  7. Chemically modified carbon nanotubes as material enhanced laser desorption ionisation (MELDI) material in protein profiling

    Energy Technology Data Exchange (ETDEWEB)

    Najam-ul-Haq, M. [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University, Innrain 52a, A-6020 Innsbruck (Austria); Rainer, M. [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University, Innrain 52a, A-6020 Innsbruck (Austria); Schwarzenauer, T. [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University, Innrain 52a, A-6020 Innsbruck (Austria); Huck, C.W. [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University, Innrain 52a, A-6020 Innsbruck (Austria)]. E-mail: christian.w.huck@uibk.ac.at; Bonn, G.K. [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University, Innrain 52a, A-6020 Innsbruck (Austria)

    2006-03-02

    Biomarkers play a potential role in the early detection and diagnosis of a disease. Our aim is to derivatize carbon nanotubes for exploration of the differences in human body fluids e.g. serum, through matrix assisted laser desorption ionisation/time of flight mass spectrometry (MALDI/TOF-MS) that can be related to disease and subsequently to be employed in the biomarker discovery process. This application we termed as the material enhanced laser desorption ionisation (MELDI). The versatility of this technology is meant to increase the amount of information from biological samples on the protein level, which will have a major impact to serve the cause of diagnostic markers. Serum peptides and proteins are immobilized on derivatized carbon nanotubes, which function as binding material. Protein-loaded suspension is placed on a stainless steel target or buckypaper on aluminum target for direct analysis with MALDI-MS. The elution method to wash the bound proteins from carbon nanotubes was employed to compare with the direct analysis procedure. Elution is carried out by MALDI matrix solution to get them out of the entangled nanotubes, which are difficult to desorb by laser due to the complex nanotube structures. The advantage of these optimized methods compared to the conventional screening methods is the improved sensitivity, selectivity and the short analysis time without prior albumin and immunoglobulin depletion. The comparison of similarly modified diamond and carbon nanotubes exhibit differences in their nature to bind the proteins out of serum due to the differences in their physical characteristics. Infrared (IR) spectroscopy provided hint for the presence of tertiary amine peak at the crucial chemical step of iminodiacetic acid addition to acid chloride functionality on carbon nanotubes. Atomic absorption spectroscopy (AAS) was utilized to quantitatively measure the copper capacity of these derivatized carbon nanotubes which is a direct measure of capacity of

  8. Targeted delivery of microRNA-126 to vascular endothelial cells via REDV peptide modified PEG-trimethyl chitosan.

    Science.gov (United States)

    Zhou, Fang; Jia, Xiaoling; Yang, Qingmao; Yang, Yang; Zhao, Yunhui; Fan, Yubo; Yuan, Xiaoyan

    2016-05-26

    Manipulation of gene expression by means of microRNAs (miRNAs) is one of the emerging strategies to treat cardiovascular and cancer diseases. Nevertheless, efficient delivery of miRNAs to a specific vascular tissue is limited. In this work, a short peptide Arg-Glu-Asp-Val (REDV) was linked to trimethyl chitosan (TMC) via a bifunctional poly(ethylene glycol) (PEG) linker for the targeted delivery of microRNA-126 (miRNA-126) to vascular endothelial cells (VECs). The morphology, serum stability and cytotoxicity of the polyplex/miRNA complexes, namely, TMC/miRNA, TMC-g-PEG/miRNA and TMC-g-PEG-REDV/miRNA, were investigated along with the cellular uptake, proliferation and in vitro miRNA transfection efficiency. By REDV modification, the TMC-g-PEG-REDV/miRNA complex showed negligible cytotoxicity, increased expression of miRNA-126 and enhanced VEC proliferation compared with the TMC/miRNA and TMC-g-PEG/miRNA complexes. In particular, the approaches adopted for the miRNA delivery and targeted peptide REDV modification promote the selective uptake and the growth of VECs over vascular smooth muscle cells. It was suggested that the REDV peptide-modified TMC-g-PEG polyplex could be potentially used as a miRNA carrier in artificial blood vessels for rapid endothelialization. PMID:27055482

  9. Interpretation of collision-induced fragmentation tandem mass spectra of posttranslationally modified peptides

    DEFF Research Database (Denmark)

    Bunkenborg, Jakob; Matthiesen, Rune

    2007-01-01

    Tandem collision-induced dissociation (CID) mass spectrometry (MS) provides a sensitive means of analyzing the amino acid sequence of peptides. Modern MS instrumentation is capable of rapidly generating many thousands of tandem mass spectra, and protein database search engines have been developed...... validating low-energy CID tandem mass spectra and gives some useful tables to aid this process....

  10. Modified Smith Predictor Based Control Of Cascaded Chemical Reactor

    Directory of Open Access Journals (Sweden)

    Binu P. Mathew

    2014-04-01

    Full Text Available A cascade control with modified smith predictor is used for controlling an open loop unstable time delay process. It has three controllers, one is for servo response other two are for regulatory response. For two disturbance rejection controllers an analytical design method is used by proposing closed loop complementary sensitivity function. These two controllers are PID controller cascaded with second order lead/lag filter. Setpoint tracking controller is designed by using direct synthesis method. The main advantage of this control scheme is that the servo response can be decoupled from the regulatory response.

  11. A Nonantibiotic Chemically Modified Tetracycline (CMT-3) Inhibits Intimal Thickening

    OpenAIRE

    Islam, Muzharul M.; Franco, Christopher D.; Courtman, David W.; Bendeck, Michelle P.

    2003-01-01

    Recent research has shown that the tetracycline antibiotics are pluripotent drugs that inhibit the activity of matrix metalloproteinases (MMPs) and affect many cellular functions including proliferation, migration, and matrix remodeling. We have shown that doxycycline inhibits MMP activity and intimal thickening after injury of the rat carotid artery, however we do not know whether these effects are because of the antibiotic, anti-MMP, or other actions of doxycycline. Recently, chemically mod...

  12. A nonenzymatic biosensor based on gold electrodes modified with peptide self-assemblies for detecting ammonia and urea oxidation.

    Science.gov (United States)

    Bianchi, Roberta C; da Silva, Emerson Rodrigo; Dall'Antonia, Luiz H; Ferreira, Fabio Furlan; Alves, Wendel Andrade

    2014-09-30

    We have developed a nonenzymatic biosensor for the detection of ammonia and urea oxidation based on the deposition of peptide microstructures onto thiolated gold electrodes. FF-MNSs/MCP/Au assemblies were obtained by modifying gold substrates with 4-mercaptopyridine (MCP), followed by coating with l,l-diphenylalanine micro/nanostructures (FF-MNSs) grown in the solid-vapor phase. Benzene rings and amide groups with peptide micro/nanostructures interact with synthetic NH4(+) receptors through cation-π and hydrogen bonding. AuOH clusters on the Au surface provided the catalytic sites. The application of a predetermined concentration of analytes at the peptide interfaces activated the catalytic sites. We observed a relationship between the stability of films and the crystal structure of peptides, and we organized the FF-MNSs into an orthorhombic symmetry that was the most suitable assembly for creation of our biosensors. At 0.1 mol L(-1) NaOH, these FF-MNSs/MCP/Au electrodes have electrocatalytic properties regarding ammonia and urea oxidation that are comparable to those of enzyme-based architectures. Under optimal conditions, the electrocatalytic response is proportional to the ammonia and urea concentration in the range 0.1-1.0 mmol L(-1). The sensitivity was calculated as 2.83 and 81.3 μA mmol L(-1) cm(-2) for ammonia and urea, respectively, at +0.40 V (vs SCE). Our detection method is easy to follow, does not require a mediator or enzyme, and has strong potential for detecting urea via nonenzymatic routes. PMID:25188339

  13. Peptide-Mediated Tumor Targeting by a Degradable Nano Gene Delivery Vector Based on Pluronic-Modified Polyethylenimine

    Science.gov (United States)

    Wu, Zhaoyong; Zhan, Shuyu; Fan, Wei; Ding, Xueying; Wu, Xin; Zhang, Wei; Fu, Yinghua; Huang, Yueyan; Huang, Xuan; Chen, Rubing; Li, Mingjuan; Xu, Ningyin; Zheng, Yongxia; Ding, Baoyue

    2016-03-01

    Polyethylenimine (PEI) is considered to be a promising non-viral gene delivery vector. To solve the toxicity versus efficacy and tumor-targeting challenges of PEI used as gene delivery vector, we constructed a novel non-viral vector DR5-TAT-modified Pluronic-PEI (Pluronic-PEI-DR5-TAT), which was based on the attachment of low-molecular-weight polyethylenimine (LMW-PEI) to the amphiphilic polymer Pluronic to prepare Pluronic-modified LMW-PEI (Pluronic-PEI). This was then conjugated to a multifunctional peptide containing a cell-penetrating peptide (TAT) and a synthetic peptide that would bind to DR5—a receptor that is overexpressed in cancer cells. The vector showed controlled degradation, favorable DNA condensation and protection performance. The Pluronic-PEI-DR5-TAT/DNA complexes at an N/P ratio of 15:1 were spherical nanoparticles of 122 ± 11.6 nm and a zeta potential of about 22 ± 2.8 mV. In vitro biological characterization results indicated that Pluronic-PEI-DR5-TAT/DNA complexes had a higher specificity for the DR5 receptor and were taken up more efficiently by tumor cells than normal cells, compared to complexes formed with PEI 25 kDa or Pluronic-PEI. Thus, the novel complexes showed much lower cytotoxicity to normal cells and higher gene transfection efficiency in tumor cells than that exhibited by PEI 25 kDa and Pluronic-PEI. In summary, our novel, degradable non-viral tumor-targeting vector is a promising candidate for use in gene therapy.

  14. Peptide-Mediated Tumor Targeting by a Degradable Nano Gene Delivery Vector Based on Pluronic-Modified Polyethylenimine.

    Science.gov (United States)

    Wu, Zhaoyong; Zhan, Shuyu; Fan, Wei; Ding, Xueying; Wu, Xin; Zhang, Wei; Fu, Yinghua; Huang, Yueyan; Huang, Xuan; Chen, Rubing; Li, Mingjuan; Xu, Ningyin; Zheng, Yongxia; Ding, Baoyue

    2016-12-01

    Polyethylenimine (PEI) is considered to be a promising non-viral gene delivery vector. To solve the toxicity versus efficacy and tumor-targeting challenges of PEI used as gene delivery vector, we constructed a novel non-viral vector DR5-TAT-modified Pluronic-PEI (Pluronic-PEI-DR5-TAT), which was based on the attachment of low-molecular-weight polyethylenimine (LMW-PEI) to the amphiphilic polymer Pluronic to prepare Pluronic-modified LMW-PEI (Pluronic-PEI). This was then conjugated to a multifunctional peptide containing a cell-penetrating peptide (TAT) and a synthetic peptide that would bind to DR5-a receptor that is overexpressed in cancer cells. The vector showed controlled degradation, favorable DNA condensation and protection performance. The Pluronic-PEI-DR5-TAT/DNA complexes at an N/P ratio of 15:1 were spherical nanoparticles of 122 ± 11.6 nm and a zeta potential of about 22 ± 2.8 mV. In vitro biological characterization results indicated that Pluronic-PEI-DR5-TAT/DNA complexes had a higher specificity for the DR5 receptor and were taken up more efficiently by tumor cells than normal cells, compared to complexes formed with PEI 25 kDa or Pluronic-PEI. Thus, the novel complexes showed much lower cytotoxicity to normal cells and higher gene transfection efficiency in tumor cells than that exhibited by PEI 25 kDa and Pluronic-PEI. In summary, our novel, degradable non-viral tumor-targeting vector is a promising candidate for use in gene therapy. PMID:26932761

  15. Bioinspired silicification of silica-binding peptide-silk protein chimeras: comparison of chemically and genetically produced proteins.

    Science.gov (United States)

    Canabady-Rochelle, Laetitia L S; Belton, David J; Deschaume, Olivier; Currie, Heather A; Kaplan, David L; Perry, Carole C

    2012-03-12

    Novel protein chimeras constituted of "silk" and a silica-binding peptide (KSLSRHDHIHHH) were synthesized by genetic or chemical approaches and their influence on silica-silk based chimera composite formation evaluated. Genetic chimeras were constructed from 6 or 15 repeats of the 32 amino acid consensus sequence of Nephila clavipes spider silk ([SGRGGLGGQG AGAAAAAGGA GQGGYGGLGSQG](n)) to which one silica binding peptide was fused at the N terminus. For the chemical chimera, 28 equiv of the silica binding peptide were chemically coupled to natural Bombyx mori silk after modification of tyrosine groups by diazonium coupling and EDC/NHS activation of all acid groups. After silica formation under mild, biomaterial-compatible conditions, the effect of peptide addition on the properties of the silk and chimeric silk-silica composite materials was explored. The composite biomaterial properties could be related to the extent of silica condensation and to the higher number of silica binding sites in the chemical chimera as compared with the genetically derived variants. In all cases, the structure of the protein/chimera in solution dictated the type of composite structure that formed with the silica deposition process having little effect on the secondary structural composition of the silk-based materials. Similarly to our study of genetic silk based chimeras containing the R5 peptide (SSKKSGSYSGSKGSKRRIL), the role of the chimeras (genetic and chemical) used in the present study resided more in aggregation and scaffolding than in the catalysis of condensation. The variables of peptide identity, silk construct (number of consensus repeats or silk source), and approach to synthesis (genetic or chemical) can be used to "tune" the properties of the composite materials formed and is a general approach that can be used to prepare a range of materials for biomedical and sensor-based applications. PMID:22229696

  16. Highly Efficient Gene Suppression by Chemically Modified 27 Nucleotide Double-Stranded RNAs

    Science.gov (United States)

    Kubo, Takanori; Zhelev, Zhivko; Bakalova, Rumiana; Ohba, Hideki

    2008-02-01

    RNA interference (RNAi) technology, described by Fire and Mello in 1998, is a powerful tool for the suppression of gene expression in mammalian cells. RNAi technology has several advantages over other chemical and genetic drugs. However, several problems in RNAi technology, such as cellular delivery, nuclease stability, and side effects, should be solved before applying it in the clinic. In this study, we focused on the development of novel chemically modified 27 nucleotide (nt) double-stranded RNAs (dsRNAs) with improved biological properties. Our chemically modified 27 nt dsRNAs exhibited an enhanced RNAi activity and a markedly increased stability in cell culture medium (containing 10% serum) in comparison with widely used 21 nt siRNAs and recently reported nonmodified 27 nt dsRNAs. The chemically modified 27 nt dsRNAs also exhibited a strong high long-term gene silencing effect after the 7 d treatment of viable cells. The chemically modified 27 nt dsRNAs in specific positions could be processed to 21 nt siRNAs by a recombinant Dicer enzyme. We suggested that the chemically modified 27 nt dsRNAs could be used for therapeutic applications (as genetic drugs) and bioanalyses.

  17. Recognition of Double Stranded RNA by Guanidine-Modified Peptide Nucleic Acids (GPNA)

    OpenAIRE

    Gupta, Pankaj; Muse, Oluwatoyosi; Rozners, Eriks

    2011-01-01

    Double helical RNA has become an attractive target for molecular recognition because many non-coding RNAs play important roles in control of gene expression. Recently, we discovered that short peptide nucleic acids (PNA) bind strongly and sequence selectively to a homopurine tract of double helical RNA via triple helix formation. Herein we tested if the molecular recognition of RNA can be enhanced by α-guanidine modification of PNA. Our study was motivated by the discovery of Ly and co-worker...

  18. Appetite-modifying actions of pro-neuromedin U-derived peptides

    OpenAIRE

    Bechtold, David A.; Ivanov, Tina R.; Luckman, Simon M.

    2009-01-01

    Neuromedin U (NMU) is known to have potent actions on appetite and energy expenditure. Deletion of the NMU gene in mice leads to an obese phenotype, characterized by hyperphagia and decreased energy expenditure. Conversely, transgenic mice that overexpress proNMU exhibit reduced body weight and fat storage. Here, we show that central administration of NMU or the related peptide neuromedin S (NMS) dose-dependently decreases food intake, increases metabolic rate, and leads to significant weight...

  19. Breakdown of N-terminally modified peptides and an isopeptide by rumen microorganisms.

    OpenAIRE

    Wallace, R J; Frumholtz, P P; Walker, N. D.

    1993-01-01

    Treatment of Trypticase peptides with acetic anhydride, succinic anhydride, or maleic anhydride inhibited their breakdown to ammonia by rumen microorganisms by an average of 89% after 12 h of incubation in vitro. All three treatments gave similar protection. Acetylation also protected dipeptides containing lysine and methionine from degradation. However, more effective protection was obtained by linking lysine and methionine as N-epsilon-methionyl lysine.

  20. Stripping voltammetric behavior of technetium at various chemically modified electrodes

    International Nuclear Information System (INIS)

    In monitoring of nuclear processing plants and storage facilities the necessity arises of assaying traces of the artificial radioactive element technetium. The oxidation states IV and VII are of particular interest. Stripping voltammetry is among the methods of assay which are suited for this purpose. It allows an enhanced selectivity to be achieved by preconcentration of the analyte and of an oxidation state of the analyte, respectively, at the electrode used. This specific enrichment is successful after appropriate chemical modification of the electrode through immobilization of a Tc-specific reagent. When various approaches of chemical modification of a glassy carbon electrode were examined, the tetraphenylarsonium chloride extractant, which is highly selective with respect to technetium, proved to be the best suited reagent, capable of fixation both by ionic and by covalent bonding on an electrodeposited polymer film. For ionic immobilization the reagent was reacted to m-sulfophenyltriphenyl arsonium and then bound to a copolymer of vinylferrocene and vinylpyridine, which had been provided with cations. It was possible to enrich Tc(VII) at such an electrode and to determine it by stripping voltammetry down to a concentration of 1x10-8 M after 5 minutes enrichment time. (orig./EF)

  1. Interfacial characterization and analytical applications of chemically-modified surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.

    1998-02-23

    The goal of this work is to explore several new strategies and approaches to the surface modification and the microscopic characterization of interfaces in the areas mainly targeting sensor technologies that are of interest to environmental control or monitoring, and scanning probe microscopies techniques that can monitor interfacial chemical reactions in real time. Centered on the main theme, four specific topics are presented as four chapters in this dissertation following the general introduction. Chapter 1 describes the development of two immobilization schemes for covalently immobilizing fluoresceinamine at cellulose acetate and its application as a pH sensing film. Chapter 2 investigates the applicability of SFM to following the base-hydrolysis of a dithio-bis(succinimidylundecanoate) monolayer at gold in situ. Chapter 3 studies the mechanism for the accelerated rate of hydrolysis of the dithio-bis(succinimidylundecanoate) monolayer at Au(111) surface. Chapter 4 focuses on the development of an electrochemical approach to the elimination of chloride interference in Chemical Oxygen Demand (COD) analysis of waste water. The procedures, results and conclusions are described in each chapter. This report contains the introduction, references, and general conclusions. Chapters have been processed separately for inclusion on the data base. 95 refs.

  2. siRNAmod: A database of experimentally validated chemically modified siRNAs.

    Science.gov (United States)

    Dar, Showkat Ahmad; Thakur, Anamika; Qureshi, Abid; Kumar, Manoj

    2016-01-01

    Small interfering RNA (siRNA) technology has vast potential for functional genomics and development of therapeutics. However, it faces many obstacles predominantly instability of siRNAs due to nuclease digestion and subsequently biologically short half-life. Chemical modifications in siRNAs provide means to overcome these shortcomings and improve their stability and potency. Despite enormous utility bioinformatics resource of these chemically modified siRNAs (cm-siRNAs) is lacking. Therefore, we have developed siRNAmod, a specialized databank for chemically modified siRNAs. Currently, our repository contains a total of 4894 chemically modified-siRNA sequences, comprising 128 unique chemical modifications on different positions with various permutations and combinations. It incorporates important information on siRNA sequence, chemical modification, their number and respective position, structure, simplified molecular input line entry system canonical (SMILES), efficacy of modified siRNA, target gene, cell line, experimental methods, reference etc. It is developed and hosted using Linux Apache MySQL PHP (LAMP) software bundle. Standard user-friendly browse, search facility and analysis tools are also integrated. It would assist in understanding the effect of chemical modifications and further development of stable and efficacious siRNAs for research as well as therapeutics. siRNAmod is freely available at: http://crdd.osdd.net/servers/sirnamod. PMID:26818131

  3. Biosorption of Methylene Blue by Chemically Modified Cellulose Waste

    Institute of Scientific and Technical Information of China (English)

    JIN Yanqiao; ZHANG Yizhuan; Lü Qiufeng; CHENG Xiansu

    2014-01-01

    Citric acid modified cellulose waste (CMCW) was prepared via esterification and used as a low-cost biosorbent for the removal of methylene blue (MB) from aqueous solutions. The effects of biosorbent concentration, initial pH of MB solution, biosorption temperature, contact time, and initial MB concentration on the biosorption of MB were investigated using batch biosorption technique under static conditions. The experimental results showed that CMCW exhibited excellent biosorption characteristics for MB. The maximum biosorption capacity of MB was up to 214.5 mg/g at an adsorption temperature of 293 K. The removal rate of MB onto CMCW reached the maximum at pH>4 and the biosorption reached an equilibrium at about 50 min. The kinetic data can be described well with the pseudo-second-order model and the isotherm data was found to fit the Langmuir isotherm with a monolayer adsorption capacity of 211.42 mg/g. The biosorption appears to be controlled by chemisorption and may be involved in surface adsorption and pore diffusion during the whole biosorption process.

  4. CO2 adsorption on chemically modified activated carbon.

    Science.gov (United States)

    Caglayan, Burcu Selen; Aksoylu, A Erhan

    2013-05-15

    CO2 adsorption capacity of a commercial activated carbon was improved by using HNO3 oxidation, air oxidation, alkali impregnation and heat treatment under helium gas atmosphere. The surface functional groups produced were investigated by diffuse reflectance infrared Fourier transform spectrometer (DRIFTS). CO2 adsorption capacities of the samples were determined by gravimetric analyses for 25-200°C temperature range. DRIFTS studies revealed the formation of carboxylic acid groups on the HNO3 oxidized adsorbents. Increased aromatization and uniform distribution of the Na particles were observed on the samples prepared by Na2CO3 impregnation onto HNO3 oxidized AC support. The adsorption capacities of the nonimpregnated samples were increased by high temperature helium treatments or by increasing the adsorption temperature; both leading to decomposition of surface oxygen groups, forming sites that can easily adsorb CO2. The adsorption capacity loss due to cyclic adsorption/desorption procedures was overcome with further surface stabilization of Na2CO3 modified samples with high temperature He treatments. With Na2CO3 impregnation the mass uptakes of the adsorbents at 20 bars and 25 °C were improved by 8 and 7 folds and at 1 bar were increased 15 and 16 folds, on the average, compared to their air oxidized and nitric acid oxidized supports, respectively. PMID:23500788

  5. PET Imaging and biodistribution of chemically modified bacteriophage MS2.

    Science.gov (United States)

    Farkas, Michelle E; Aanei, Ioana L; Behrens, Christopher R; Tong, Gary J; Murphy, Stephanie T; O'Neil, James P; Francis, Matthew B

    2013-01-01

    The fields of nanotechnology and medicine have merged in the development of new imaging and drug delivery agents based on nanoparticle platforms. As one example, a mutant of bacteriophage MS2 can be differentially modified on the exterior and interior surfaces for the concurrent display of targeting functionalities and payloads, respectively. In order to realize their potential for use in in vivo applications, the biodistribution and circulation properties of this class of agents must first be investigated. A means of modulating and potentially improving the characteristics of nanoparticle agents is the appendage of PEG chains. Both MS2 and MS2-PEG capsids possessing interior DOTA chelators were labeled with (64)Cu and injected intravenously into mice possessing tumor xenografts. Dynamic imaging of the agents was performed using PET-CT on a single animal per sample, and the biodistribution at the terminal time point (24 h) was assessed by gamma counting of the organs ex vivo for 3 animals per agent. Compared to other viral capsids of similar size, the MS2 agents showed longer circulation times. Both MS2 and MS2-PEG bacteriophage behaved similarly, although the latter agent showed significantly less uptake in the spleen. This effect may be attributed to the ability of the PEG chains to mask the capsid charge. Although the tumor uptake of the agents may result from the enhanced permeation and retention (EPR) effect, selective tumor imaging may be achieved in the future by using exterior targeting groups. PMID:23214968

  6. Theory of nanoscale friction on chemically modified graphene

    Science.gov (United States)

    Ko, Jae-Hyeon; Kim, Yong-Hyun

    2013-03-01

    Recently, it is known from FFM experiments that friction force on graphene is significantly increased by chemical modification such as hydrogenation, oxidization, and fluorination, whereas adhesion properties are altered marginally. A novel nanotribological theory on two-dimensional materials is proposed on the basis of experimental results and first-principles density-functional theory (DFT) calculations. The proposed theory indicates that the total lateral stiffness that is the proportional constant of friction force is mostly associated with the out-of-plane bending stiffness of two-dimensional materials. This contrasts to the case of three-dimensional materials, in which the shear strength of materials determines nanoscale friction. We will discuss details of DFT calculations and how to generalize the current theory to three dimensional materials.

  7. WATER-BLOWN POLYURETHANE RIGID FOAMS MODIFIED BY CHEMICAL PLASTICATION

    Institute of Scientific and Technical Information of China (English)

    YU Ming; XU Qiang

    2006-01-01

    Water-blown polyurethane rigid foams are getting more and more attention, because the traditional blowing agent HCFC141b has already been abolished to prevent the ozone layer from destruction. However, the polyurethane rigid foams blown by water have serious defects, i.e. friability and resulting lower adhesion strength. Thus, the purpose of this study is to resolve the problems by chemical plastication. The maleate was added to polyol-premix containing water or to polyisocyanate,with both of which maleate does not react. To prove the reaction when polyol-premix and polyisocyanate were mixed, the model composite was synthesized and analyzed by IR, NMR and ESI (MS). Furthermore, a series of water-blown polyurethane rigid foams added different amount maleate were successfully prepared. By testing impact strength and adhesion strength of the foams, the actual effect of adding maleate was obtained.

  8. The presence of modifiable residues in the core peptide part of precursor nisin is not crucial for precursor nisin interactions with NisB- and NisC.

    Directory of Open Access Journals (Sweden)

    Rustem Khusainov

    Full Text Available Precursor nisin is a model posttranslationally modified precursor lantibiotic that can be structurally divided into a leader peptide sequence and a modifiable core peptide part. The nisin core peptide clearly plays an important role in the precursor nisin-nisin modification enzymes interactions, since it has previously been shown that the construct containing only the nisin leader sequence is not sufficient to pull-down the nisin modification enzymes NisB and NisC. Serines and threonines in the core peptide part are the residues that NisB specifically dehydrates, and cysteines are the residues that NisC stereospecifically couples to the dehydrated amino acids. Here, we demonstrate that increasing the number of negatively charged residues in the core peptide part of precursor nisin, which are absent in wild-type nisin, does not abolish binding of precursor nisin to the modification enzymes NisB and NisC, but dramatically decreases the antimicrobial potency of these nisin mutants. An unnatural precursor nisin variant lacking all serines and threonines in the core peptide part and an unnatural precursor nisin variant lacking all cysteines in the core peptide part still bind the nisin modification enzymes NisB and NisC, suggesting that these residues are not essential for direct interactions with the nisin modification enzymes NisB and NisC. These results are important for lantibiotic engineering studies.

  9. Equilibrium and thermodynamic studies of Cd (II) biosorption by chemically modified orange peel.

    Science.gov (United States)

    Kumar, Arbind; Kumar, Vipin

    2016-03-01

    Agricultural wastes have great potential of removing heavy metal ions from aqueous solution. Removal of Cd (II) from aqueous solutions onto chemically modified orange peel was studied at different pH, contact time, initial metal concentrations, adsorbent doses and temperature. Batch experiments were carried out under optimized conditions to evaluate the adsorption capacity of orange peel chemically modified with NaOH. The results showed that maximum adsorption capacity of modified orange peel, approximately 97.0%, was observed 3 mg 1⁻¹ of initial Cd(II) concentration pH 6 for 4 g 1⁻¹ adsorbent dosage, 200 min contact time and 298 K temperature. Adsorption efficiency of modified orange peel decreased with increase in temperature indicated exothermic nature of adsorption. A negative value of ΔG⁰(-8.59 kJ mol⁻¹) confirmed the feasibility of adsorption process and spontaneous nature of adsorption. A negative value of ΔH⁰ (-28.08 kJ mol⁻¹) indicated exothermic nature while a negative ΔS⁰ (-66.86 J K⁻¹ mol⁻¹) value suggested decrease in degree of freedom of the adsorbed species. The results showed that biosorption process of Cd(II) ions by chemically modified orange peel is feasible, spontaneous and exothermic under studied conditions. Chemically by modified orange peel investigated in the present study showed good potential for the removal of cadmium from aqueous solutions. PMID:27097438

  10. Unusual chemical properties of N-terminal histidine residues of glucagon and vasoactive intestinal peptide

    International Nuclear Information System (INIS)

    An N-terminal histidine residue of a protein or peptide has two functional groups, viz., an alpha-amino group and an imidazole group. A new procedure, based on the competitive labeling approach described by Duggleby and Kaplan has been developed by which the chemical reactivity of each functional group in such a residue can be determined as a function of pH. Only very small amounts of material are required, which makes it possible to determine the chemical properties in dilute solution or in proteins and polypeptides that can be obtained in only minute quantities. With this approach, the reactivity of the alpha-amino group of histidylglycine toward 1-fluoro-2,4-dinitrobenzene gave an apparent pK /sub a/ value of 7.64 +/- 0.07 at 37 degrees C, in good agreement with a value of 7.69 +/- 0.02 obtained by acid-base titration. However, the reactivity of the imidazole function gave an apparent pK /sub a/ value of 7.16 +/- 0.07 as compared to the pK /sub a/ value of 5.85 +/- 0.01 obtained by acid-base titration. Similarly, in glucagon and vasoactive intestinal peptide (VIP), apparent pKa values of 7.60 +/- 0.04 and 7.88 +/- 0.18, respectively, were obtained for the alpha-amino of their N-terminal histidine, and pKa values of 7.43 +/- 0.09 and 7.59 +/- 0.18 were obtained for the imidazole function

  11. Chitosan and chemically modified chitosan beads for acid dyes sorption

    Institute of Scientific and Technical Information of China (English)

    AZLAN Kamari; WAN SAIME Wan Ngah; LAI KEN Liew

    2009-01-01

    The capabilities of chitosan and chitosan-EGDE (ethylene glycol diglycidyl ether) beads for removing Acid Red 37 (AR 37) and Acid Blue 25 (AB 25) from aqueous solution were examined. Chitosan beads were cross-linked with EGDE to enhance its chemical resistance and mechanical strength. Experiments were performed as a function of pH, agitation period and concentration of AR 37 and AB 25. It was shown that the adsorption capacities of chitosan were comparatively higher than chitosan-EGDE for both acid dyes. This is mainly because cross-linking using EGDE reduces the major adsorption sites -NH3+ on chitosan. Langmuir isotherm model showed best conformity compared to Freundlich and BET. The kinetic experimental data agreed very well to the pseudo second-order kinetic model. The desorption study revealed that after three cycles of adsorption and desorption by NaOH and HCl, both adsorbents retained their promising adsorption abilities. FT-IR analysis proved that the adsorption of acid dyes onto chitosan-based adsorbents was a physical adsorption. Results also showed that chitosan and chitosan-EGDE beads were favourable adsorbers and could be employed as low-cost alternatives for the removal of acid dyes in wastewater treatment.

  12. Killing of trypanosomatid parasites by a modified bovine host defense peptide, BMAP-18.

    Directory of Open Access Journals (Sweden)

    Lee R Haines

    Full Text Available BACKGROUND: Tropical diseases caused by parasites continue to cause socioeconomic devastation that reverberates worldwide. There is a growing need for new control measures for many of these diseases due to increasing drug resistance exhibited by the parasites and problems with drug toxicity. One new approach is to apply host defense peptides (HDP; formerly called antimicrobial peptides to disease control, either to treat infected hosts, or to prevent disease transmission by interfering with parasites in their insect vectors. A potent anti-parasite effector is bovine myeloid antimicrobial peptide-27 (BMAP-27, a member of the cathelicidin family. Although BMAP-27 is a potent inhibitor of microbial growth, at higher concentrations it also exhibits cytotoxicity to mammalian cells. We tested the anti-parasite activity of BMAP-18, a truncated peptide that lacks the hydrophobic C-terminal sequence of the BMAP-27 parent molecule, an alteration that confers reduced toxicity to mammalian cells. METHODOLOGY/PRINCIPAL FINDINGS: BMAP-18 showed strong growth inhibitory activity against several species and life cycle stages of African trypanosomes, fish trypanosomes and Leishmania parasites in vitro. When compared to native BMAP-27, the truncated BMAP-18 peptide showed reduced cytotoxicity on a wide variety of mammalian and insect cells and on Sodalis glossindius, a bacterial symbiont of the tsetse vector. The fluorescent stain rhodamine 123 was used in immunofluorescence microscopy and flow cytometry experiments to show that BMAP-18 at low concentrations rapidly disrupted mitochondrial potential without obvious alteration of parasite plasma membranes, thus inducing death by apoptosis. Scanning electron microscopy revealed that higher concentrations of BMAP-18 induced membrane lesions in the parasites as early as 15 minutes after exposure, thus killing them by necrosis. In addition to direct killing of parasites, BMAP-18 was shown to inhibit LPS

  13. Lysosomally cleavable peptide-containing polymersomes modified with anti-EGFR antibody for systemic cancer chemotherapy.

    Science.gov (United States)

    Lee, Jung S; Groothuis, Tom; Cusan, Claudia; Mink, Daniel; Feijen, Jan

    2011-12-01

    Polymersomes (Ps) based on a biodegradable and biocompatible block copolymer of methoxy poly(ethylene glycol) (mPEG) and poly(D,L-lactide) (PDLLA) in which apeptide sequence, Gly-Phe-Leu-Gly-Phe (GFLGF), was introduced in between the two blocks(mPEG-pep-PDLLA) were developed. The peptide linker is cleavable by the lysosomal enzymecathepsin B (Cath B). Ps containing the peptide linker (Ps(pep)) with an average diameter of about 124 nm were prepared by injecting a THF solution of the block copolymer into DI water. The Ps had a membrane thickness of about 15 nm as determined by transmission electron microscopy (TEM). In order to investigate the enzymatic degradation of the Ps (pep), dynamic light scattering (DLS) measurements of Ps(pep) dispersions with different concentrations of Cath B at pH 5.5 and 7.4 were performed as a function of time. A gradual decrease in kilo counts per second (Kcps) of the Ps (pep) over 7 d was observed after incubation of the Ps (pep) dispersions with 5 units/ml of Cath B at pH 5.5 at 37 °C. The size distribution became also bimodal, indicating that aggregation and precipitation of Ps (pep) occurred by disintegration of the Ps (pep) as a result of cleavage of the peptide. The rate of disintegration of the Ps (pep) was depending on the concentration of Cath Band the pH. No changes by DLS were seen when the dispersions were incubated with the enzyme at pH 7.4. Acridine orange (AO) was encapsulated in Ps (pep)as a model drug and rapid release of AO triggered by Cath B degradation of Ps (pep) was observed at pH 5.5. Anti-epidermal growth factor receptor (anti-EGFR) antibody (abEGFR) was immobilized on the surface of Ps(pep)in order to enhance the cellular uptake of Ps (pep). Fluorescein isothiocyanate labeled dextran (40,000 g/mol) (FD40) was incorporated in the Ps (pep) for the cell study and Ps either without peptide or antibody or without both peptide and antibody were used as negative controls. After 3 d exposure to SKBR3 cells, ab

  14. How chelators can modified in vitro and in vivo response of indirect labelled BPTI peptide

    International Nuclear Information System (INIS)

    Aim: the aim of this work was to compare labeling methods for BPTI and in vitro and in vivo properties when it was labeled with 99mTc via two different chelators HYNIC and DTPA. BPTI (provided by Dr. Hnatowich) was used as a model for future labeling of HNE2, an analog peptide used in infection imaging. Materials and Methods: conjugation reaction was carried out at molar ratio of 5:1 between the chelators (NHS-HYNIC and cDTPA) and the peptide BPTI. After Biogel P4 purification, the first four fractions were labeled with 99mTc. The one with the best labelling efficiency was selected for testing each conjugated product. DTPA-BPTI was labeled with 99mTc at pH 5.2. HYNIC-BPTI was labeled with 99mTc using tricine as coligand. 99mTc-DTPA-BPTI was purified by C18 Sep-Pack cartridge due to its impurities. Both 99mTc-labelled BPTI were analysed by reverse phase high performance liquid chromatography (RP-HPLC). Stability of the labeled peptides was asses ed by incubating at 370 C with PBS 0.05M pH 7.2, for 24h. 99mTc-peptides were tested for instability toward cysteine, binding to serum protein and trypsin. Bio distributions in normal NIH mice were carried out for both labeled peptides at 2 h post injection (p.i.). Results: Radiochemical purity of 99mTc-((Tricine)HYNIC-BPTI) and 99mTc-DTPA-BPTI determined by RP-HPLC was higher than 95 % and 55 % respectively. The range of specific activity of these products was between 0.07-0.6-MBq/μg. The radiochemical purity of the C18 Sp-Pack purified 99mTc-DTPA-BPTI was 77 %. The dissociation value for 99mTc-((Tricine)HYNIC-BPTI)) was less than 10 % in PBS at 24 h. The results of a cysteine challenge assay of labelled BPTI showed anomalous behaviour for HYNIC conjugate. The activity bound to serum protein of 99mTc-((Tricine)HYNIC-BPTI) was 20 % higher than the value of 99mTc-DTPA-BPTI. G75 radiometric elution profile of 99mTc-((Tricine)HYNIC-BPTI)) : trypsin (Molar ratio 1:10) showed positive binding. Biodistribution in NIH normal mice

  15. Cell-penetrating peptide-doxorubicin conjugate loaded NGR-modified nanobubbles for ultrasound triggered drug delivery.

    Science.gov (United States)

    Lin, Wen; Xie, Xiangyang; Deng, Jianping; Liu, Hui; Chen, Ying; Fu, Xudong; Liu, Hong; Yang, Yang

    2016-01-01

    A new drug-targeting system for CD13(+) tumors has been developed, based on ultrasound-sensitive nanobubbles (NBs) and cell-permeable peptides (CPPs). Here, the CPP-doxorubicin conjugate (CPP-DOX) was entrapped in the asparagine-glycine-arginine (NGR) peptide modified NB (CPP-DOX/NGR-NB) and the penetration of CPP-DOX was temporally masked; local ultrasound stimulation could trigger the CPP-DOX release from NB and activate its penetration. The CPP-DOX/NGR-NBs had particle sizes of about 200 nm and drug entrapment efficiency larger than 90%. In vitro release results showed that over 85% of the encapsulated DOX or CPP-DOX would release from NBs in the presence of ultrasound, while less than 1.5% of that (30 min) without ultrasound. Cell experiments showed the higher cellular CPP-DOX uptake of CPP-DOX/NGR-NB among the various NB formulations in Human fibrosarcoma cells (HT-1080, CD13(+)). The CPP-DOX/NGR-NB with ultrasound treatment exhibited an increased cytotoxic activity than the one without ultrasound. In nude mice xenograft of HT-1080 cells, CPP-DOX/NGR-NB with ultrasound showed a higher tumor inhibition effect (3.1% of T/C%, day 24), longer median survival time (50 days) and excellent body safety compared with the normal DOX injection group. These results indicate that the constructed vesicle would be a promising drug delivery system for specific cancer treatment. PMID:26176270

  16. A comparison between the recombinant expression and chemical synthesis of a short cysteine-rich insecticidal spider peptide

    OpenAIRE

    Clement, Herlinda; Flores, Vianey; Diego-Garcia, Elia; Corrales-Garcia, Ligia; Villegas, Elba; Corzo, Gerardo

    2015-01-01

    Background The choice between heterologous expression versus chemical synthesis for synthesizing short cysteine-rich insecticidal peptides from arthropods may impact the obtainment of yields and well-folded bioactive molecules for scientific research. Therefore, two recombinant expression systems were compared to that of chemical synthesis for producing Ba1, a cysteine-rich spider neurotoxin. Methods The transcription of the insecticidal neurotoxin Ba1 was obtained from a cDNA library of veno...

  17. C-Terminally modified peptides via cleavage of the HMBA linker by O-, N- or S-nucleophiles

    DEFF Research Database (Denmark)

    Hansen, Jonas; Diness, Frederik; Meldal, Morten Peter

    2016-01-01

    A large variety of C-terminally modified peptides was obtained by nucleophilic cleavage of the ester bond in solid phase linked peptide esters of 4-hydroxymethyl benzamide (HMBA). The developed methods provided peptides, C-terminally functionalized as esters, amides and thioesters, with high puri...

  18. High-throughput peptide mass fingerprinting and protein macroarray analysis using chemical printing strategies

    International Nuclear Information System (INIS)

    We describe a 'chemical printer' that uses piezoelectric pulsing for rapid and accurate microdispensing of picolitre volumes of fluid for proteomic analysis of 'protein macroarrays'. Unlike positive transfer and pin transfer systems, our printer dispenses fluid in a non-contact process that ensures that the fluid source cannot be contaminated by substrate during a printing event. We demonstrate automated delivery of enzyme and matrix solutions for on-membrane protein digestion and subsequent peptide mass fingerprinting (pmf) analysis directly from the membrane surface using matrix-assisted laser-desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). This approach bypasses the more commonly used multi-step procedures, thereby permitting a more rapid procedure for protein identification. We also highlight the advantage of printing different chemistries onto an individual protein spot for multiple microscale analyses. This ability is particularly useful when detailed characterisation of rare and valuable sample is required. Using a combination of PNGase F and trypsin we have mapped sites of N-glycosylation using on-membrane digestion strategies. We also demonstrate the ability to print multiple serum samples in a micro-ELISA format and rapidly screen a protein macroarray of human blood plasma for pathogen-derived antigens. We anticipate that the 'chemical printer' will be a major component of proteomic platforms for high-throughput protein identification and characterisation with widespread applications in biomedical and diagnostic discovery

  19. Synthesis and Radiolabeling of Modified Peptides Attached to Heterocyclic Rings and Their Possible Medical Applications

    International Nuclear Information System (INIS)

    Keeping in mind the pharmacological potential of heterocyclic rings as well as the advantage of biodegradability and biocompatibility of amino acids/peptides, in this thesis we were prompted for the following: 1. Synthesis of novel dipeptide derivatives coupled with different heterocyclic rings (pyridine, 1,2,4-triazol-pyridine, 1,3,4-oxadiazolpyridine and tetrazol-pyridine rings). 2. Characterization of the synthesized compounds on the basis of their spectral data (IR, Mass and 1 H-NMR spectra). 3. Study their antimicrobial activity as one of their expected biological activities. 4. Study the radioiodination of some synthesized dipeptide derivatives. 5. Study the biodistribution of the radiolabeled compounds in normal mice as preliminary studies for the possibility of using them as agents for imaging and treatment.

  20. Total Synthesis of the Posttranslationally Modified Polyazole Peptide Antibiotic Plantazolicin A.

    Science.gov (United States)

    Wada, Hiroki; Williams, Huw E L; Moody, Christopher J

    2015-12-01

    The power of rhodium-carbene methodology in chemistry is demonstrated by the synthesis of a structurally complex polyazole antibiotic. Plantazolicin A, a novel soil-bacterium metabolite, comprises a linear array of 10 five-membered rings in two pentacyclic regions that derive from ribosomal peptide synthesis followed by extensive posttranslational modification. The compound possesses potent antimicrobial activity, and is selectively active against the anthrax-causing organism. A conceptually different synthesis of plantazolicin A is reported in which the key steps are the use of rhodium(II)-catalyzed reactions of diazocarbonyl compounds to generate up to six of the seven oxazole rings of the antibiotic. NMR spectroscopic studies and molecular modeling reveal a likely dynamic hairpin conformation with a hinge region around the two isoleucine residues. The compound has modest activity against methicillin-resistant Staphylococcus aureus (MRSA). PMID:26473502

  1. Chemical treatment of the intra-canal dentin surface: a new approach to modify dentin hydrophobicity

    Directory of Open Access Journals (Sweden)

    Cesar GAITAN-FONSECA

    2013-01-01

    Full Text Available Objective This study evaluated the hydrophobicity of dentin surfaces that were modified through chemical silanization with octadecyltrichlorosilane (OTS. Material and Methods An in vitro experimental study was performed using 40 human permanent incisors that were divided into the following two groups: non-silanized and silanized. The specimens were pretreated and chemically modified with OTS. After the chemical modification, the dentin hydrophobicity was examined using a water contact angle measurement (WCA. The effectiveness of the modification of hydrophobicity was verified by the fluid permeability test (FPT. Results and Conclusions Statistically significant differences were found in the values of WCA and FPT between the two groups. After silanization, the hydrophobic intraradicular dentin surface exhibited in vitro properties that limit fluid penetration into the sealed root canal. This chemical treatment is a new approach for improving the sealing of the root canal system.

  2. Towards electron transport measurements in chemically modified graphene: The effect of a solvent

    OpenAIRE

    Jacobsen, A.; Koehler, F. M.; Stark, W J; Ensslin, K.

    2010-01-01

    Chemical functionalization of graphene modifies the local electron density of the carbon atoms and hence electron transport. Measuring these changes allows for a closer understanding of the chemical interaction and the influence of functionalization on the graphene lattice. However, not only chemistry, in this case diazonium chemistry, has an effect on the electron transport. Latter is also influenced by defects and dopants resulting from different processing steps. Here, we show that solvent...

  3. Synthesis and physicochemical characterization of chemically modified chitosan by succinic anhydride

    OpenAIRE

    Karine Gargioni Pereira Correa de Mello; Leandra de Cássia Bernusso; Ronaldo Nogueira de Moraes Pitombo; Bronislaw Polakiewicz

    2006-01-01

    The N-succinil-chitosan is a chemically modified derivative of the biopolymer chitosan. The succinic anhydride attached to the free amino groups presented along the chitosan's polymer chain imparts to the molecule different physicochemical properties not exhibited before the modification. These chemical modifications enhance chitosan's solubility in slightly acid, neutral and alkaline media. These properties are related to the long alkyl chains attached to hydrophilic parts. In this case the ...

  4. Synergistic Effect of Chemical and Thermical Treatment on the Structure and Sorption Properties of Natural and Chemically Modified Slovak Zeolite

    Directory of Open Access Journals (Sweden)

    Štefan Svetík

    2005-06-01

    Full Text Available The calcinated natural and chemically modified zeolite from the deposit Nižný Hrabovec (Slovak Republic was studied. The changes of zeolite structure due to synergistic effect of temperature and chemical treat-ment were studied by DTA. The static radioindicatore method was used for studying the sorption of zeolite through the uptake of Cs and Co cations from model solutions. The results showed that the uptake of Cs and Co cations strongly depends on the modification of zeolite and on the higher temperature of calcination.

  5. Base-modified nucleotides and DNA for applications in diagnostics and chemical biology

    Czech Academy of Sciences Publication Activity Database

    Hocek, Michal

    Praha: Czech Chemical Society, 2015. s. 31. [Liblice 2015. Advances in Organic , Bioorganic and Pharmaceutical Chemistry /50./. 06.11.2015-08.11.2015, Olomouc] R&D Projects: GA ČR GBP206/12/G151; GA ČR GA14-04289S Institutional support: RVO:61388963 Keywords : base-modified nucleotides * DNA Subject RIV: CC - Organic Chemistry

  6. Chemical modifiers in electrothermal atomic absorption determination of Platinum and Palladium containing preparations in blood serum

    Directory of Open Access Journals (Sweden)

    Аntonina Alemasova

    2012-11-01

    Full Text Available The biological liquids matrixes influence on the characteristic masses and repeatability of Pt and Pd electrothermal atomic absorption spectroscopy (ETAAS determination was studied. The chemical modifiers dimethylglyoxime and ascorbic acid for matrix interferences elimination and ETAAS results repeatability improvement were proposed while bioliquids ETAAS analysis, and their action mechanism was discussed.

  7. Biomechanical properties of acellular sciatic nerves treated with a modified chemical method

    Institute of Scientific and Technical Information of China (English)

    Xinlong Ma; Zhao Yang; Xiaolei Sun; Jianxiong Ma; Xiulan Li; Zhenzhen Yuan; Yang Zhang; Honggang Guo

    2011-01-01

    Nerve grafts are able to adapt to surrounding biomechanical environments if the nerve graft itself exhibits appropriate biomechanical properties (load, elastic modulus, etc.). The present study was designed to determine the differences in biomechanical properties between fresh and chemically acellularized sciatic nerve grafts. Two different chemical methods were used to establish acellular nerve grafts. The nerve was chemically extracted in the Sondell method with a combination of Triton X-100 (nonionic detergent) and sodium deoxycholate (anionic detergent), and in the modified method with a combination of Triton X-200 (anionic detergent), sulfobetaine-10 (SB-10, amphoteric detergents), and sulfobetaine-16 (SB-16, amphoteric detergents). Following acellularization, hematoxylin-eosin staining and scanning electron microscopy demonstrated that the effect of acellularization via the modified method was similar to the traditional Sondell method. However, effects of demyelination and nerve fiber tube integrity were superior to the traditional Sondell method. Biomechanical testing showed that peripheral nerve graft treated using the chemical method resulted in decreased biomechanical properties (ultimate load, ultimate stress, ultimate strain, and mechanical work to fracture) compared with fresh nerves, but the differences had no statistical significance (P > 0.05). These results demonstrated no significant effect on biomechanical properties of nerves treated using the chemical method. In conclusion, nerve grafts treated via the modified method removed Schwann cells, preserved neural structures, and ensured biomechanical properties of the nerve graft, which could be more appropriate for implantation studies.

  8. Chemical synthesis of transmembrane peptide and its application for research on the transmembrane-juxtamembrane region of membrane protein.

    Science.gov (United States)

    Sato, Takeshi

    2016-11-01

    Membrane proteins possess one or more hydrophobic regions that span the membrane and interact with the lipids that constitute the membrane. The interactions between the transmembrane (TM) region and lipids affect the structure and function of these membrane proteins. Molecular characterization of synthetic TM peptides in lipid bilayers helps to understand how the TM region participates in the formation of the structure and in the function of membrane proteins. The use of synthetic peptides enables site-specific labeling and modification and allows for designing of an artificial TM sequence. Research involving such samples has resulted in significant increase in the knowledge of the mechanisms that govern membrane biology. In this review, the chemical synthesis of TM peptides has been discussed. The preparation of synthetic TM peptides is still not trivial; however, the accumulated knowledge summarized here should provide a basis for preparing samples for spectroscopic analyses. The application of synthetic TM peptides for gaining insights into the mechanism of signal transduction by receptor tyrosine kinase (RTK) has also been discussed. RTK is a single TM protein and is one of the difficult targets in structural biology as crystallization of the full-length receptor has not been successful. This review describes the structural characterization of the synthetic TM-juxtamembrane sequence and proposes a possible scheme for the structural changes in this region for the activation of ErbBs, the epidermal growth factor receptor family. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 613-621, 2016. PMID:26573237

  9. Extension of in vivo half-life of biologically active peptides via chemical conjugation to XTEN protein polymer.

    Science.gov (United States)

    Podust, Vladimir N; Sim, Bee-Cheng; Kothari, Dharti; Henthorn, Lana; Gu, Chen; Wang, Chia-wei; McLaughlin, Bryant; Schellenberger, Volker

    2013-11-01

    XTEN, unstructured biodegradable proteins, have been used to extend the in vivo half-life of genetically fused therapeutic proteins and peptides. To expand the applications of XTEN technology to half-life extension of other classes of molecules, XTEN protein polymers and methods for chemical XTENylation were developed. Two XTEN precursors were engineered to contain enzymatically removable purification tags. The proteins were readily expressed in bacteria and purified to homogeneity by chromatography techniques. As proof-of-principle, GLP2-2G peptide was chemically conjugated to each of the two XTEN protein polymers using maleimide-thiol chemistry. The monodisperse nature of XTEN protein polymer enabled reaction monitoring as well as the detection of peptide modifications in the conjugated state using reverse phase-high performance liquid chromatography (RP-HPLC) and electrospray ionization mass spectrometry. The resulting GLP2-2G-XTEN conjugates were purified by preparative RP-HPLC to homogeneity. In comparison with recombinantly fused GLP2-2G-XTEN, chemically conjugated GLP2-2G-XTEN molecules exhibited comparable in vitro activity, in vitro plasma stability and pharmacokinetics in rats. These data suggest that chemical XTENylation could effectively extend the half-life of a wide spectrum of biologically active molecules, therefore broadening its applicability. PMID:24133142

  10. Enhancing Polymer-Modified Mortar Adhesion to Ceramic Tile Surface by Chemical Functionalization with Organosilanes

    Science.gov (United States)

    Mansur, Alexandra Ancelmo Piscitelli; Do Nascimento, Otávio Luiz; Mansur, Herman Sander

    Adhesion between tiles and mortars is of paramount importance to the overall stability of ceramic tile systems. In this sense, from the chemical perspective, weak forces such as van der Waals forces and hydrophilic interactions are expected to occur preferably at the tiles and polymer-modified Portland cement mortar interfaces. Thus, the main goal of this study was to chemically modify the ceramic tile surface through organosilanes aiming to improve adhesion with polymer-modified mortars (PMMs). Glass tile surfaces were treated with five silane derivatives bearing specific functionalities. Fourier transform infrared spectroscopy and contact angle measurements were used for characterizing the novel surfaces produced as the chemical moieties were immobilized onto them. In addition, pull-off tests were conducted to assess the effect on adhesion properties between tile and poly(ethylene-co-vinyl acetate) modified mortar. The bond strength results have given strong evidence of the improvement on adherence at the tile-PMM interface, reflecting the whole balance of silane, cement, and polymer interactions.

  11. Chemical functionalization of ceramic tile surfaces by silane coupling agents: polymer modified mortar adhesion mechanism implications

    Directory of Open Access Journals (Sweden)

    Alexandra Ancelmo Piscitelli Mansur

    2008-09-01

    Full Text Available Adhesion between tiles and mortars are crucial to the stability of ceramic tile systems. From the chemical point of view, weak forces such as van der Waals forces and hydrophilic interactions are expected to be developed preferably at the tiles and polymer modified Portland cement mortar interface. The main goal of this paper was to use organosilanes as primers to modify ceramic tile hydrophilic properties to improve adhesion between ceramic tiles and polymer modified mortars. Glass tile surfaces were treated with several silane derivatives bearing specific functionalities. Contact angle measurements and Fourier Transform Infrared Spectroscopy (FTIR were used for evaluating the chemical changes on the tile surface. In addition, pull-off tests were conducted to assess the effect on adhesion properties between tile and poly(ethylene-co-vinyl acetate, EVA, modified mortar. The bond strength results have clearly shown the improvement of adherence at the tile-polymer modified mortar interface, reflecting the overall balance of silane, cement and polymer interactions.

  12. Enhancement of the Regenerative Potential of Anorganic Bovine Bone Graft Utilizing a Polyglutamate-Modified BMP2 Peptide with Improved Binding to Calcium-Containing Materials.

    Science.gov (United States)

    Bain, Jennifer L; Bonvallet, Paul P; Abou-Arraj, Ramzi V; Schupbach, Peter; Reddy, Michael S; Bellis, Susan L

    2015-09-01

    no side effects were observed with E7BMP2pep/ABB. Furthermore, histological analysis of the tissues revealed that grafts with rBMP2, but not E7BMP2pep, induced formation of adipose tissue in the defect area. Collectively, these results suggest that E7-modified BMP2-mimetic peptides may enhance the regenerative potential of commercial graft materials without the deleterious effects or high costs associated with rBMP2 treatments. PMID:26176902

  13. Reactive chemically modified piezoelectric crystal detectors: A new class of high-selectivity sensors

    International Nuclear Information System (INIS)

    A great number of works have focused on the study of properties of modified piezoelectric quartz crystal detectors (PQCDs) coated with sorbing substrates and on applying sensors based on them for the analysis of diluted gas mixtures and solutions. This work offers a new class of gravemetric sensors characterized by a reversible chemical reaction that occurs on their surface. Silica films are proposed as a sorbing coating of quartz detectors, and a chemical modification of a surface is suggested for covalent fixation of the necessary compounds. PQCDs were chemically modified with reactive diene derivatives that can also act as dienophiles. Hexachlorocyclopentadiene (HCCPD, resonater I) and cyclopentadiene (CPD, resonator II) were fixed on a PQCD surface in several stages. After treatment with the resonaters, the PQCD in a CPD gas phase exhibited time dependent frequency shifts from 20-100 Hz. The results suggest that there is a reversible chemical reaction on the electrode surface of resonators I and II when they interact with CPD vapors. Therefore, PQCDs modified with reactive dienes were prepared for the first time and may be employed as selective sensors for CPD

  14. Impact dynamics of water droplets on chemically modified WOx nanowire arrays

    Science.gov (United States)

    Kwak, Geunjae; Lee, Mikyung; Senthil, Karuppanan; Yong, Kijung

    2009-10-01

    The effects of surface energy on the wetting transition for impinging water droplets were investigated on the chemically modified WOx nanowire surfaces. We could modify the surface energy of the nanowires through chemisorption of alkyltrichlorosilanes with various carbon chain lengths and also by the ultraviolet-enhanced decomposition of self assembled monolayer molecules. Three surface wetting states could be identified through the balance between antiwetting and wetting pressures. This approach establishes a simple strategy for design of the water-repellent surface to impinging droplets.

  15. Active interfacial modifier: stabilization mechanism of water in silicone oil emulsions by peptide-silicone hybrid polymers.

    Science.gov (United States)

    Sakai, Kenichi; Ikeda, Ryosuke; Sharma, Suraj Chandra; Shrestha, Rekha Goswami; Ohtani, Naoko; Yoshioka, Masato; Sakai, Hideki; Abe, Masahiko; Sakamoto, Kazutami

    2010-04-20

    We have developed hybrid amphiphilic polymers consisting of a silicone backbone modified with hydrocarbon chains and hydrolyzed silk peptides. These polymers are molecularly soluble neither in water nor in most of organic solvent, but are attractive with these solvents. We assume that this property enables the polymers to form "an independent third phase" between immiscible two liquid phases and stabilize the emulsion system, based on a fundamentally distinguishable mechanism from the approach by conventional surfactants. We have named these amphiphilic polymers "active interfacial modifier (AIM)" and studied physicochemical properties of AIM-stabilized water-in-silicon oil emulsions. The addition of AIM to a mixture of water and decamethylcyclopentasiloxane (D(5)) has achieved preparation of stable W/O emulsions (droplet size = ca. 1 microm) in a wide range of the three components, even under relatively gentle vortex mixing. Interestingly, the prepared W/O emulsions are found to be nearly genuine or quasi Newtonian fluid with low viscosity when water content is in the range from 0 to 36 wt % for the fixed weight ratio of AIM/D(5) = 6/4. This is a good piece of evidence that AIM forms the independent third phase, where the Newtonian shear occurs at the D(5)/AIM interface. The presence of AIM as third phase has also been confirmed by fluorescence probe method with confocal laser scanning microscopy. As such, AIM can activate interfaces by the least amount to cover interfaces as an independent third phase, and hence, this provides a new concept achieving a precise control of interfacial properties. PMID:20232883

  16. Catalytic conversion of biomass pyrolysis-derived compounds with chemical liquid deposition (CLD) modified ZSM-5.

    Science.gov (United States)

    Zhang, Huiyan; Luo, Mengmeng; Xiao, Rui; Shao, Shanshan; Jin, Baosheng; Xiao, Guomin; Zhao, Ming; Liang, Junyu

    2014-03-01

    Chemical liquid deposition (CLD) with KH550, TEOS and methyl silicone oil as the modifiers was used to modify ZSM-5 and deposit its external acid sites. The characteristics of modified catalysts were tested by catalytic conversion of biomass pyrolysis-derived compounds. The effects of different modifying conditions (deposited amount, temperature, and time) on the product yields and selectivities were investigated. The results show KH550 modified ZSM-5 (deposited amount of 4%, temperature of 20°C and time of 6h) produced the maximum yields of aromatics (24.5%) and olefins (16.5%), which are much higher than that obtained with original ZSM-5 catalyst (18.8% aromatics and 9.8% olefins). The coke yield decreased from 44.1% with original ZSM-5 to 26.7% with KH550 modified ZSM-5. The selectivities of low-molecule-weight hydrocarbons (ethylene and benzene) decreased, while that of higher molecule-weight hydrocarbons (propylene, butylene, toluene, and naphthalene) increased comparing with original ZSM-5. PMID:24413482

  17. Towards electron transport measurements in chemically modified graphene: effect of a solvent

    Science.gov (United States)

    Jacobsen, Arnhild; Koehler, Fabian M.; Stark, Wendelin J.; Ensslin, Klaus

    2010-12-01

    The chemical functionalization of graphene modifies the local electron density of carbon atoms and hence electron transport. Measuring these changes allows for a closer understanding of the chemical interaction and the influence of functionalization on the graphene lattice. However, not only chemistry, in this case diazonium chemistry, has an effect on electron transport. The latter is also influenced by defects and dopants resulting from different processing steps. Here, we show that the solvents used in the chemical reaction process change the transport properties. In more detail, the investigated combination of isopropanol and heating treatment reduces the doping concentration and significantly increases the mobility of graphene. Furthermore, isopropanol treatment alone increases the concentration of dopants and introduces an asymmetry between electron and hole transport, which might be difficult to distinguish from the effect of functionalization. The results shown in this work demand a closer look at the influence of solvents used for chemical modification in order to understand their influence.

  18. Side chain modified peptide nucleic acids (PNA for knock-down of six3 in medaka embryos

    Directory of Open Access Journals (Sweden)

    Dorn Sebastian

    2012-08-01

    Full Text Available Abstract Background Synthetic antisense molecules have an enormous potential for therapeutic applications in humans. The major aim of such strategies is to specifically interfere with gene function, thus modulating cellular pathways according to the therapeutic demands. Among the molecules which can block mRNA function in a sequence specific manner are peptide nucleic acids (PNA. They are highly stable and efficiently and selectively interact with RNA. However, some properties of non-modified aminoethyl glycine PNAs (aegPNA hamper their in vivo applications. Results We generated new backbone modifications of PNAs, which exhibit more hydrophilic properties. When we examined the activity and specificity of these novel phosphonic ester PNAs (pePNA molecules in medaka (Oryzias latipes embryos, high solubility and selective binding to mRNA was observed. In particular, mixing of the novel components with aegPNA components resulted in mixed PNAs with superior properties. Injection of mixed PNAs directed against the medaka six3 gene, which is important for eye and brain development, resulted in specific six3 phenotypes. Conclusions PNAs are well established as powerful antisense molecules. Modification of the backbone with phosphonic ester side chains further improves their properties and allows the efficient knock down of a single gene in fish embryos.

  19. A composite scaffold of MSC affinity peptide-modified demineralized bone matrix particles and chitosan hydrogel for cartilage regeneration

    Science.gov (United States)

    Meng, Qingyang; Man, Zhentao; Dai, Linghui; Huang, Hongjie; Zhang, Xin; Hu, Xiaoqing; Shao, Zhenxing; Zhu, Jingxian; Zhang, Jiying; Fu, Xin; Duan, Xiaoning; Ao, Yingfang

    2015-12-01

    Articular cartilage injury is still a significant challenge because of the poor intrinsic healing potential of cartilage. Stem cell-based tissue engineering is a promising technique for cartilage repair. As cartilage defects are usually irregular in clinical settings, scaffolds with moldability that can fill any shape of cartilage defects and closely integrate with the host cartilage are desirable. In this study, we constructed a composite scaffold combining mesenchymal stem cells (MSCs) E7 affinity peptide-modified demineralized bone matrix (DBM) particles and chitosan (CS) hydrogel for cartilage engineering. This solid-supported composite scaffold exhibited appropriate porosity, which provided a 3D microenvironment that supports cell adhesion and proliferation. Cell proliferation and DNA content analysis indicated that the DBM-E7/CS scaffold promoted better rat bone marrow-derived MSCs (BMMSCs) survival than the CS or DBM/CS groups. Meanwhile, the DBM-E7/CS scaffold increased matrix production and improved chondrogenic differentiation ability of BMMSCs in vitro. Furthermore, after implantation in vivo for four weeks, compared to those in control groups, the regenerated issue in the DBM-E7/CS group exhibited translucent and superior cartilage-like structures, as indicated by gross observation, histological examination, and assessment of matrix staining. Overall, the functional composite scaffold of DBM-E7/CS is a promising option for repairing irregularly shaped cartilage defects.

  20. Highly improved chromium (III uptake capacity in modified sugarcane bagasse using different chemical treatments

    Directory of Open Access Journals (Sweden)

    Vanessa Cristina Gonçalves Dos Santos

    2012-01-01

    Full Text Available The present paper focuses on improving chromium (III uptake capacity of sugarcane bagasse through its chemical modification with citric acid and/or sodium hydroxide. The chemical modifications were confirmed by infrared spectroscopy, with an evident peak observed at 1730 cm-1, attributed to carbonyl groups. Equilibrium was reached after 24 h, and the kinetics followed the pseudo-second-order model. The highest chromium (III maximum adsorption capacity (MAC value was found when using sugarcane bagasse modified with sodium hydroxide and citric acid (58.00 mg g-1 giving a MAC value about three times greater (20.34 mg g-1 than for raw sugarcane bagasse.

  1. PRELIMINARY STUDY ON ENHANCED PROPERTIES AND BIOLOGICAL RESISTANCE OF CHEMICALLY MODIFIED ACACIA SPP.

    Directory of Open Access Journals (Sweden)

    H. P. S. Abdul Khalil

    2010-11-01

    Full Text Available A preliminary experimental study was carried out to examine the ability of a chemically modified Acacia spp. to resist biodegradation. The modifications of Acacia mangium and Acacia hybrid were carried out by propionic anhydride and succinic anhydride in the presence of sodium formate as a catalyst. The treated samples were found resistant to microbial attack, while the untreated ones were damaged on 12 months exposure to a soil burial. The appearance grading, mass loss, mechanical properties, and scanning electron microscopy results revealed that chemical modification enhances the resistance of Acacia mangium and Acacia hybrid wood species to biodegradation.

  2. Research on the chemical mechanism in the polyacrylate latex modified cement system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Wang, Rumin, E-mail: wangmin19@mail.nwpu.edu.cn [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Zheng, Shuirong [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Northwestern Polytechnical University–East China University of Science and Technology Combined Research Institute of New High Speed Railway Materials (China); Farhan, Shameel; Yao, Hao; Jiang, Hao [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China)

    2015-10-15

    In this paper, the chemical mechanism in the polyacrylate latex modified cement system was investigated by Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), gel permeation chromatography (GPC) and compact pH meter. All results have shown that the chemical reactions in the polyacrylate modified system can be divided into three stages. The hydration reactions of cement can produce large amounts of Ca(OH){sub 2} (calcium hydroxide) and lead the whole system to be alkali-rich and exothermic at the first stage. Subsequently, this environment can do great contributions to the hydrolysis of ester groups in the polyacrylate chains, resulting in the formation of carboxyl groups at the second stage. At the third stage, the final crosslinked network structure of the product was obtained by the reaction between the carboxyl groups in the polyacrylate latex chains and Ca(OH){sub 2}.

  3. Sorption and desorption of Fe(III) on natural and chemically modified zeolite

    International Nuclear Information System (INIS)

    The Fe(III) uptake from aqueous solutions by natural and chemically modified zeolites was investigated using a gradual radioexchange method and AAS technique. The leachability of Fe(III) from loaded zeolites was studied too. The Fe-uptake reached the value of 60 mg x g-1 for the zeolite chemically treated with 6 mol x l-1 solution of NaOH and it is more than twelve times higher than that of the raw zeolite. The leachability of the loaded zeolite samples in water and alkaline solution was up 5%. The leachability of the same zeolites in acid solution depended on the concentration of modifying solution. The leachability at pH = 2.6 in the range 2-20% at pH = 1.9 was many times higher. The results of the radioexchange and AAS methods were compared. (author)

  4. Research on the chemical mechanism in the polyacrylate latex modified cement system

    International Nuclear Information System (INIS)

    In this paper, the chemical mechanism in the polyacrylate latex modified cement system was investigated by Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), gel permeation chromatography (GPC) and compact pH meter. All results have shown that the chemical reactions in the polyacrylate modified system can be divided into three stages. The hydration reactions of cement can produce large amounts of Ca(OH)2 (calcium hydroxide) and lead the whole system to be alkali-rich and exothermic at the first stage. Subsequently, this environment can do great contributions to the hydrolysis of ester groups in the polyacrylate chains, resulting in the formation of carboxyl groups at the second stage. At the third stage, the final crosslinked network structure of the product was obtained by the reaction between the carboxyl groups in the polyacrylate latex chains and Ca(OH)2

  5. Adsorption and desorption of Cr(III) on natural and chemically modified Slovak zeolites

    International Nuclear Information System (INIS)

    Natural and chemically modified zeolites from the Slovak Republic and Ukraine have been investigated as the adsorbents for the uptake of Cr(III). Model water solution of low radioactivity was used. The adsorption and desorption kinetics of chromium were established with the gradual radioexchange technique (tracer 51Cr) and flame AAS. The effect of the factors studied are examined and explained. The sorption coefficient μ, distribution coefficient KD, sorption capacity Γ, sorption rate S, and leachability of Cr were calculated in neutral, alkaline and acidic aqueous solutions. The sorption capacity of the modified zeolites was found to be greater by a factor of 2 to 16 than that of the unmodified ones depending on the modifying solution applied. The leachability of chromium from loaded zeolites into the neutral solution was negligible. The leachability into alkaline and acidic solutions increased over 40%. (author)

  6. Chemically modified STM tips for atomic-resolution imaging of ultrathin NaCI films

    Institute of Scientific and Technical Information of China (English)

    Zhe Li[1; Koen Schouteden[1; Violeta lancu[1; Ewald Janssens[1; Peter Lievens[1; Chris Van Haesendonck[1; Jorge I. Cerda[2

    2015-01-01

    Cl-functionalized scanning tunneling microscopy (STM) tips are fabricated by modifying a tungsten STM tip in situ on islands of ultrathin NaCI(100) films on Au(111) surfaces. The functionalized tips are used to achieve clear atomic- resolution imaging of NaCI(100) islands. In comparison with bare metal tips, the chemically modified tips yield drastically enhanced spatial resolution as well as contrast reversal in STM topographs, implying that Na atoms, rather than C1 atoms, are imaged as protrusions. STM simulations based on a Green's function formalism reveal that the experimentally observed contrast reversal in the STM topographs is due to the highly localized character of the Cl-pz states at the tip apex. An additional remarkable characteristic of the modified tips is that in dI/dV maps, a Na atom appears as a ring with a diameter that depends crucially on the tip-sample distance.

  7. Nucleocytoplasmic transport blockage by SV40 peptide-modified gold nanoparticles induces cellular autophagy

    Directory of Open Access Journals (Sweden)

    Tsai TL

    2012-10-01

    Full Text Available Tsung-Lin Tsai,1,5 Chia-Cheng Hou,1,5 Hao-Chen Wang,1,5 Zih-Syuan Yang,2 Chen-Sheng Yeh,4 Dar-Bin Shieh,2,3 Wu-Chou Su1,51Institute of Basic Medical Sciences, 2Institute of Oral Medicine and Department of Stomatology, 3Center for Micro/Nano Science and Technology, 4Department of Chemistry, National Cheng Kung University, Tainan, Taiwan; 5Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, TaiwanAbstract: Gold nanoparticles modified with the nuclear localization signal from simian virus 40 large T antigen (GNP-PEG/SV40 accumulate on the cytoplasmic side of the nuclear membrane in HeLa cells. Accumulation of GNP-PEG/SV40 around the nucleus blocks nucleocytoplasmic transport and prevents RNA export and nuclear shuttling of signaling proteins. This long-term blockage of nucleocytoplasmic transport results in cell death. This cell death is not caused by apoptosis or necrosis because caspases 3 and 9 are not activated, and the expression of annexin V/propidium iodide is not enhanced in HeLa cells after treatment. Using transmission electron microscopy, autophagosomes and autolysosomes were seen to appear after 72 hours of treatment with GNP-PEG/SV40. Increasing levels of enhanced green fluorescent protein-microtubule-associated protein 1 light chain 3 (EGFP-LC3-positive punctate and LC3-II confirmed GNP-PEG/SV40-induced autophagy. In SiHa cells, treatment did not induce accumulation of GNP-PEG/SV40 around the nucleus and autophagy. Treating cells with wheat germ agglutinin, a nuclear pore complex inhibitor, induced autophagy in both HeLa and SiHa cells. GNP-PEG/SV40-induced autophagy plays a role in cell death, not survival, and virus-mediated small hairpin RNA silencing of Beclin-1 attenuates cell death. Taken together, the results indicate that long-term blockade of nucleocytoplasmic transport results in autophagic cell death.Keywords: gold nanoparticles

  8. Chemically modified heparins inhibit fibrinogen-bridged indirect adhesion between tumor cells and platelets

    OpenAIRE

    Zheng, Sheng; Liu, Yan; Jiao, Yang; Min WEI; ZENG, XIANLU

    2011-01-01

    The interaction between platelets and tumor cells is critical for the hematogenous metastasis of tumor cells. We recently reported that fibrinogen was capable of bridging and enhancing the interaction of platelets and tumor cells under conditions of physical shear force. In the present study, we aimed to detect the effects of 8 chemically modified heparins on the binding of fibrinogen to platelets or tumor cells using flow cytometry assays, as well as the fibrinogen-bridged adhesion of platel...

  9. Electrodeposition of platinum and silver into chemically modified microporous silicon electrodes

    OpenAIRE

    Koda, Ryo; Fukami, Kazuhiro; Sakka, Tetsuo; Ogata, Yukio H.

    2012-01-01

    Electrodeposition of platinum and silver into hydrophobic and hydrophilic microporous silicon layers was investigated using chemically modified microporous silicon electrodes. Hydrophobic microporous silicon enhanced the electrodeposition of platinum in the porous layer. Meanwhile, hydrophilic one showed that platinum was hardly deposited within the porous layer, and a film of platinum on the top of the porous layer was observed. On the other hand, the electrodeposition of silver showed simil...

  10. Uptake of plutonium from nuclear waste water by natural and chemically modified sorbents

    International Nuclear Information System (INIS)

    The uptake of plutonium from model solution of boric acid labelled with 239Pu by natural sorbents was studied. The range of pH of solution was from 5.1 to 8. For the uptake of Pu were used different natural and chemically modified natural sorbents of different mineralogical composition and from different deposits. The distribution coefficients for plutonium uptake were calculated and the best conditions for uptake were evaluated. (author)

  11. PRELIMINARY STUDY ON ENHANCED PROPERTIES AND BIOLOGICAL RESISTANCE OF CHEMICALLY MODIFIED ACACIA SPP.

    OpenAIRE

    H. P. S. Abdul Khalil; Irshad ul Haq Bhat,; Khairul B. Awang

    2010-01-01

    A preliminary experimental study was carried out to examine the ability of a chemically modified Acacia spp. to resist biodegradation. The modifications of Acacia mangium and Acacia hybrid were carried out by propionic anhydride and succinic anhydride in the presence of sodium formate as a catalyst. The treated samples were found resistant to microbial attack, while the untreated ones were damaged on 12 months exposure to a soil burial. The appearance grading, mass loss, mechanical properties...

  12. Chemically modified bitumens with enhanced rheology and adhesion properties to siliceous aggregates

    OpenAIRE

    Cuadri Vega, Antonio Abad; Partal López, Pedro; Ahmad, Naveed; Grenfell, James; Airey, Gordon

    2015-01-01

    Moisture damage is one of the major premature failures that worsens the performance and shortens service life of pavements. This research assesses the effect that two chemical modifiers (thiourea and an isocyanate-functionalized castor oil prepolymer) exerts on the bitumen rheology and on the resistance to potential moisture damage of asphalt mixtures based on siliceous aggregates. Both thiourea and the isocyanate-based prepolymer improve the viscous and viscoelastic behaviours of bitumen at ...

  13. Bending creep of Maritime pine wood (Pinus pinaster Ait.) chemically modified

    OpenAIRE

    Lopes, Duarte Barroso; Mai, Carsten; Militz, Holger

    2013-01-01

    The long-term performance of a structural member is determined by its durability and deformation with time. The bending creep behaviour of modified wood was assessed experimentally over a period of 35 days (840 hours). Four chemical modification processes were used: 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU), mmethylated melamine formaldehyde resin (MMF), tetraethoxysilane (TEOS) and amid wax (WA). Wood stakes with 20.10.200 mm RTL dimensions of Portuguese Maritime pine (Pinus pi...

  14. PREPARATION OF CHEMICAL AND PHYSICAL CONJUGATES OF SELF-ASSEMBLING NANOPARTICLES WITH CELL-PENETRATING PEPTIDE AND DOXORUBICIN

    Directory of Open Access Journals (Sweden)

    Zhadyra Sagykyzy Shagyrova

    2015-09-01

    Full Text Available Abstract: Nano-sized carriers can help to reduce toxicity and improve clinical efficacy of drugs. Virus-like particles (VLPs are biocompatible and biodegradable self-assembling nanoparticles, which show great promise as carriers for substances for targeted delivery and controlled release. Either chemical conjugation of physical incorporation without formation of covalent bonds is possible to load substances of interest into VLPs.Objectives: To produce VLPs from recombinant viral capsid protein (HBcAg and test feasibility of methods of formation of chemical and physical conjugates of VLPs with substances of pharmacological interest.Methods: Virus-like particles composed from recombinant hepatitis B core antigen (HBcAg were produced by recombinant expression in E.coli and purified by successive centrifugation through sucrose gradients. Peptide transportan 10 was synthesized and used for carbodiimide (EDC-mediated conjugation to VLPs. Doxorubicin (DOX was loaded into the nucleic acid-containing VLPs to form physical conjugate.Results: VLPs with chemically attached moieties of cell-penetrating peptide transportan 10 were produced. The conjugate was examined in SDS-PAGE to confirm presence of conjugation products. Conjugation efficiency (molar ration peptide/protein in the conjugate reaches 0.5:1 (i.e. 50% of protein chains have one attached peptide moiety. The nucleic acid-containing VLPs can be loaded with the DOX forming stable non-covalent physical conjugate.Conclusion: Recombinantly expressed VLPs allow easy attaching of small molecules making them a convenient platform to develop drug carriers.

  15. BIOSORPTION OF METHYLENE BLUE ON CHEMICALLY MODIFIED CHAETOPHORA ELEGANS ALGA BY HCl AND CITRIC ACID

    International Nuclear Information System (INIS)

    Chemical modification of Chaetophora Elegans algae with HCl and citric acid was undertaken in order to improve the methylene blue adsorption. The modified algae with 1 M HCl showed an increase in the maximum uptake from 143 mg g-1 to 320 mg g-1 due to elimination of carbonate. The modified algae with 1M citric acid showed an important decrease in the uptake from 143 mg g-1 to 20 mg g-1 due to increase in the cross linking degree. Acid concentration used in the chemical modification (0.1 M -1 M) is the major parameter affecting the maximum uptake. The temperature of the chemical modifica- tion has a small effect on the uptake. Langmuir-Freundlich isotherm model fitted better the isotherm adsorption data for all samples studied. Pseudo second order model was well in line with the experimental data. The adsorption rate constant (K ) is higher for modified algae with HCl than that of raw algae. The activation thermodynamic parameters E-a , ΔH, ΔS and ΔG were calculated. The maximum uptake is independent of isotherm adsorption temperature in the range studied. (author)

  16. Novel highly-soluble peptide-chitosan polymers: Chemical synthesis and spectral characterization

    OpenAIRE

    Batista, MKS; Pinto, LF; Gomes, CAR; Gomes, P.

    2006-01-01

    Novel water-soluble polymers, N-(gamma-propanoyl-valin)-chitosan and N-(gamma-propanoyi-aspartic acid)-chitosan, were synthesized by reaction of low molecular weight chitosan with N-alpha-(3-bromopropanoyl)-valine and N-alpha-(3-bromopropanoyl)-aspartic acid, respectively, under mild conditions. Prior to reaction with chitosan, the peptide substituents have been prepared by standard peptide chemistry methods from 3-bromopropanoic acid and the relevant a-amino acid tert-butyl esters. The chemi...

  17. Structure and Bioactivity of a Modified Peptide Derived from the LPS-Binding Domain of an Anti-Lipopolysaccharide Factor (ALF) of Shrimp

    Science.gov (United States)

    Yang, Hui; Li, Shihao; Li, Fuhua; Xiang, Jianhai

    2016-01-01

    The lipopolysaccharide binding domain (LBD) in anti-lipopolysaccharide factor (ALF) is the main functional element of ALF, which exhibits antimicrobial activities. Our previous studies show that the peptide LBDv, synthesized based on the modified sequence of LBD (named LBD2) from FcALF2, exhibited an apparently enhanced antimicrobial activity. To learn the prospect of LBDv application, the characteristics of LBDv were analyzed in the present study. The LBDv peptide showed higher antimicrobial and bactericidal activities compared with LBD2. These activities of the LBDv peptide were stable after heat treatment. LBDv could also exhibit in vivo antimicrobial activity to Vibrio harveyi. The LBDv peptide was found to bind bacteria, quickly cause bacterial agglutination, and kill bacteria by damaging their membrane integrity. Structure analysis showed that both LBDv and LBD2 held the β-sheet structure, and the positive net charge and amphipathicity characteristic were speculated as two important components for their antimicrobial activity. The cytotoxicity of LBDv was evaluated in cultured Spodoptera frugiperda (Sf9) cells and Cherax quadricarinatus hemocytes. More than 80% cells could survive with the LBDv concentration up to 16 μM. Collectively, these findings highlighted the potential antimicrobial mechanism of LBD peptides, and provided important information for the commercial use of LBDv in the future. PMID:27213409

  18. Structure and Bioactivity of a Modified Peptide Derived from the LPS-Binding Domain of an Anti-Lipopolysaccharide Factor (ALF) of Shrimp.

    Science.gov (United States)

    Yang, Hui; Li, Shihao; Li, Fuhua; Xiang, Jianhai

    2016-05-01

    The lipopolysaccharide binding domain (LBD) in anti-lipopolysaccharide factor (ALF) is the main functional element of ALF, which exhibits antimicrobial activities. Our previous studies show that the peptide LBDv, synthesized based on the modified sequence of LBD (named LBD2) from FcALF2, exhibited an apparently enhanced antimicrobial activity. To learn the prospect of LBDv application, the characteristics of LBDv were analyzed in the present study. The LBDv peptide showed higher antimicrobial and bactericidal activities compared with LBD2. These activities of the LBDv peptide were stable after heat treatment. LBDv could also exhibit in vivo antimicrobial activity to Vibrio harveyi. The LBDv peptide was found to bind bacteria, quickly cause bacterial agglutination, and kill bacteria by damaging their membrane integrity. Structure analysis showed that both LBDv and LBD2 held the β-sheet structure, and the positive net charge and amphipathicity characteristic were speculated as two important components for their antimicrobial activity. The cytotoxicity of LBDv was evaluated in cultured Spodoptera frugiperda (Sf9) cells and Cherax quadricarinatus hemocytes. More than 80% cells could survive with the LBDv concentration up to 16 μM. Collectively, these findings highlighted the potential antimicrobial mechanism of LBD peptides, and provided important information for the commercial use of LBDv in the future. PMID:27213409

  19. Structure and Bioactivity of a Modified Peptide Derived from the LPS-Binding Domain of an Anti-Lipopolysaccharide Factor (ALF of Shrimp

    Directory of Open Access Journals (Sweden)

    Hui Yang

    2016-05-01

    Full Text Available The lipopolysaccharide binding domain (LBD in anti-lipopolysaccharide factor (ALF is the main functional element of ALF, which exhibits antimicrobial activities. Our previous studies show that the peptide LBDv, synthesized based on the modified sequence of LBD (named LBD2 from FcALF2, exhibited an apparently enhanced antimicrobial activity. To learn the prospect of LBDv application, the characteristics of LBDv were analyzed in the present study. The LBDv peptide showed higher antimicrobial and bactericidal activities compared with LBD2. These activities of the LBDv peptide were stable after heat treatment. LBDv could also exhibit in vivo antimicrobial activity to Vibrio harveyi. The LBDv peptide was found to bind bacteria, quickly cause bacterial agglutination, and kill bacteria by damaging their membrane integrity. Structure analysis showed that both LBDv and LBD2 held the β-sheet structure, and the positive net charge and amphipathicity characteristic were speculated as two important components for their antimicrobial activity. The cytotoxicity of LBDv was evaluated in cultured Spodoptera frugiperda (Sf9 cells and Cherax quadricarinatus hemocytes. More than 80% cells could survive with the LBDv concentration up to 16 μM. Collectively, these findings highlighted the potential antimicrobial mechanism of LBD peptides, and provided important information for the commercial use of LBDv in the future.

  20. Chemically modified biochar produced from conocarpus waste increases NO3 removal from aqueous solutions.

    Science.gov (United States)

    Usman, Adel R A; Ahmad, Mahtab; El-Mahrouky, Mohamed; Al-Omran, Abdulrasoul; Ok, Yong Sik; Sallam, Abdelazeem Sh; El-Naggar, Ahmed H; Al-Wabel, Mohammad I

    2016-04-01

    Biochar has emerged as a universal sorbent for the removal of contaminants from water and soil. However, its efficiency is lower than that of commercially available sorbents. Engineering biochar by chemical modification may improve its sorption efficiency. In this study, conocarpus green waste was chemically modified with magnesium and iron oxides and then subjected to thermal pyrolysis to produce biochar. These chemically modified biochars were tested for NO3 removal efficiency from aqueous solutions in batch sorption isothermal and kinetic experiments. The results revealed that MgO-biochar outperformed other biochars with a maximum NO3 sorption capacity of 45.36 mmol kg(-1) predicted by the Langmuir sorption model. The kinetics data were well described by the Type 1 pseudo-second-order model, indicating chemisorption as the dominating mechanism of NO3 sorption onto biochars. Greater efficiency of MgO-biochar was related to its high specific surface area (391.8 m(2) g(-1)) and formation of strong ionic complexes with NO3. At an initial pH of 2, more than 89 % NO3 removal efficiency was observed for all of the biochars. We conclude that chemical modification can alter the surface chemistry of biochar, thereby leading to enhanced sorption capacity compared with simple biochar. PMID:26100325

  1. Chemically modified Si(111) surfaces simultaneously demonstrating hydrophilicity, resistance against oxidation, and low trap state densities

    Science.gov (United States)

    Brown, Elizabeth S.; Hlynchuk, Sofiya; Maldonado, Stephen

    2016-03-01

    Chemically modified Si(111) surfaces have been prepared through a series of wet chemical surface treatments that simultaneously show resistance towards surface oxidation, selective reactivity towards chemical reagents, and areal defect densities comparable to unannealed thermal oxides. Specifically, grazing angle attenuated total reflectance infrared and X-ray photoelectron (XP) spectroscopies were used to characterize allyl-, 3,4-methylenedioxybenzene-, or 4-[bis(trimethylsilyl)amino]phenyl-terminated surfaces and the subsequently hydroxylated surfaces. Hydroxylated surfaces were confirmed through reaction with 4-(trifluoromethyl)benzyl bromide and quantified by XP spectroscopy. Contact angle measurements indicated all surfaces remained hydrophilic, even after secondary backfilling with CH3sbnd groups. Surface recombination velocity measurements by way of microwave photoconductivity transients showed the relative defect-character of as-prepared and aged surfaces. The relative merits for each investigated surface type are discussed.

  2. Self-assembled monolayer-modified block copolymers for chemical surface nanopatterning

    International Nuclear Information System (INIS)

    Research highlights: → Self-organizing PS-b-PMMA creates striped nanostructure scaffolds. → These striped nanostructures can be selectively metalized and modified using light. → Metalized stripes can be decorated with SAMs to create functional substrates. → Nanostructured surfaces thus prepared exhibit controlled wetting and recognition. - Abstract: Thin-film poly(styrene-block-methyl methacrylate) diblock copolymer (PS-b-PMMA) is used to create chemically patterned surfaces via metal deposition combined with self-assembled monolayers (SAMs) and UV exposure. We use this method to produce surfaces that are chemically striped on the scale of a few tens of nanometers. Atomic force and transmission electron microscopies are used to verify the spatially localized organization of materials, and contact angle measurements confirm the chemical tunability of these scaffolds. These surfaces may be used for arraying nanoscale objects, such as nanoparticles or biological species, or for electronic, magnetic memory or photovoltaic applications.

  3. Transfer of Chemically Modified Graphene with Retention of Functionality for Surface Engineering.

    Science.gov (United States)

    Whitener, Keith E; Lee, Woo-Kyung; Bassim, Nabil D; Stroud, Rhonda M; Robinson, Jeremy T; Sheehan, Paul E

    2016-02-10

    Single-layer graphene chemically reduced by the Birch process delaminates from a Si/SiOx substrate when exposed to an ethanol/water mixture, enabling transfer of chemically functionalized graphene to arbitrary substrates such as metals, dielectrics, and polymers. Unlike in previous reports, the graphene retains hydrogen, methyl, and aryl functional groups during the transfer process. This enables one to functionalize the receiving substrate with the properties of the chemically modified graphene (CMG). For instance, magnetic force microscopy shows that the previously reported magnetic properties of partially hydrogenated graphene remain after transfer. We also transfer hydrogenated graphene from its copper growth substrate to a Si/SiOx wafer and thermally dehydrogenate it to demonstrate a polymer- and etchant-free graphene transfer for potential use in transmission electron microscopy. Finally, we show that the Birch reduction facilitates delamination of CMG by weakening van der Waals forces between graphene and its substrate. PMID:26784372

  4. NisT, the Transporter of the Lantibiotic Nisin, Can Transport Fully Modified, Dehydrated, and Unmodified Prenisin and Fusions of the Leader Peptide with Non-lantibiotic Peptides

    NARCIS (Netherlands)

    Kuipers, Anneke; Boef, Esther de; Rink, Rick; Fekken, Susan; Kluskens, Leon D.; Driessen, Arnold J.M.; Leenhouts, Kees; Kuipers, Oscar P.; Moll, Gert N.

    2004-01-01

    Lantibiotics are lanthionine-containing peptide antibiotics. Nisin, encoded by nisA, is a pentacyclic lantibiotic produced by some Lactococcus lactis strains. Its thioether rings are posttranslationally introduced by a membrane-bound enzyme complex. This complex is composed of three enzymes: NisB, w

  5. Chemical composition and corrosion protection of silane films modified with CeO2 nanoparticles

    International Nuclear Information System (INIS)

    The present work aims at understanding the role of CeO2 nanoparticles (with and without activation in cerium(III) solutions) used as fillers for hybrid silane coatings applied on galvanized steel substrates. The work reports the improved corrosion protection performance of the modified silane films and discusses the chemistry of the cerium-activated nanoparticles, the mechanisms involved in the formation of the surface coatings and its corrosion inhibition ability. The anti-corrosion performance was investigated using electrochemical impedance spectroscopy (EIS), the scanning vibrating electrode technique (SVET) and d.c. potentiodynamic polarization. The chemical composition of silanised nanoparticles and the chemical changes of the silane solutions due to the presence of additives were studied using X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance spectroscopy (NMR), respectively. The NMR and XPS data revealed that the modified silane solutions and respective coatings have enhanced cross-linking and that silane-cerium bonds are likely to occur. Electrochemical impedance spectroscopy showed that the modified coatings have improved barrier properties and the SVET measurements highlight the corrosion inhibition effect of ceria nanoparticles activated with Ce(III) ions. Potentiodynamic polarization curves demonstrate an enhanced passive domain for zinc, in the presence of nanoparticles, in solutions simulating the cathodic environment.

  6. Chemically modified nucleic acid aptamers for in vitro selections: evolving evolution.

    Science.gov (United States)

    Kusser, W

    2000-03-01

    Combinatorial library selections through the systematic evolution of ligands by exponential enrichment (SELEX) technique identify so-called nucleic acid aptamers that bind with high-affinity and specificity to a wide range of selected molecules. However, the modest chemical functionality of nucleic acids poses some limits on their versatility as binders and catalysts, and, furthermore, the sensitivity of pure RNA- and DNA-based aptamers to nucleases restricts their use as therapeutic and diagnostic agents. Here we review synthetic chemistries for modifying nucleotides that have been developed to enhance the affinity of aptamers for targets and to increase their stability in biological fluids. Implementation of in vitro selections with modified nucleotides promises to be an elegant technique for the creation of ligands with novel physical and chemical properties and is anticipated to have a significant impact on biotechnology, diagnostics and drug development. The current molecular designs and applications of modified nucleotides for in vitro selections are reviewed, along with a discussion of future developments expected to further the utility of this approach in both practical and theoretical terms. PMID:10943570

  7. Evaluation of batch biosorption of chromium (vi) from aqueous solution by chemically modified polyalthia longifolia leaves

    International Nuclear Information System (INIS)

    Removal of toxic metals from surface water is a significant matter of concern. Biosorption is emerging as an economical and eco friendly methodology for the removal of toxic chemicals from waste water. Optimization of operating conditions has a large impact on the efficiency of this process. Simple untreated and chemically modified Polyalthia longifolia leaves were used to study biosorption of Cr (VI) from aqueous media within various experimental conditions and their efficiency of biosorption were compared. The effects of different conditions, such as contact time of solution with bio sorbent, temperature, pH, biosorbent dose and agitation speed for the removal of Cr (VI) were studied. It is found that acid treated Polyalthia longifolia leaves have greater biosorption capacity as compared to untreated and base treated leaves. Langmuir and Freundlich isotherms were also applied to evaluate maximum biosorption capacity of simple untreated and chemically modified Polyalthia longifolia leaves for Cr (VI). This research work is of great importance in regard of practical waste water treatment by biosorption. (author)

  8. Highly dispersed Pd nanoparticles on chemically modified graphene with aminophenyl groups for formic acid oxidation

    Institute of Scientific and Technical Information of China (English)

    Yang Su-Dong; Shen Cheng-Min; Tong Hao; He Wei; Zhang Xiao-Gang; Gao Hong-Jun

    2011-01-01

    A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the aminophenyl groups of p-phenylenediamine.Palladium nanoparticles with an average diameter of 4.2 nm are deposited on the CMG by a liquid-phase borohydride reduction.The electrocatalytic activity and stability of the Pd/CMG composite towards formic acid oxidation are found to be higher than those of reduced graphene oxide and commercial carbon materials such as Vulcan XC-72 supported Pd electrocatalysts.

  9. Size-dependent mobility of gold nano-clusters during growth on chemically modified graphene

    International Nuclear Information System (INIS)

    Gold nano-clusters were grown on chemically modified graphene by direct sputter deposition. Transmission electron microscopy of the nano-clusters on these electron-transparent substrates reveals an unusual bimodal island size distribution (ISD). A kinetic Monte Carlo model of growth incorporating a size-dependent cluster mobility rule uniquely reproduces the bimodal ISD, providing strong evidence for the mobility of large clusters during surface growth. The cluster mobility exponent of −5/3 is consistent with cluster motion via one-dimensional diffusion of gold atoms around the edges of the nano-clusters

  10. Size-dependent mobility of gold nano-clusters during growth on chemically modified graphene

    Directory of Open Access Journals (Sweden)

    Gavin R. Bell

    2014-01-01

    Full Text Available Gold nano-clusters were grown on chemically modified graphene by direct sputter deposition. Transmission electron microscopy of the nano-clusters on these electron-transparent substrates reveals an unusual bimodal island size distribution (ISD. A kinetic Monte Carlo model of growth incorporating a size-dependent cluster mobility rule uniquely reproduces the bimodal ISD, providing strong evidence for the mobility of large clusters during surface growth. The cluster mobility exponent of −5/3 is consistent with cluster motion via one-dimensional diffusion of gold atoms around the edges of the nano-clusters.

  11. The Viscoelastic Properties of Chemically Modified alpha-Keratins in Human Hair

    OpenAIRE

    Jinks, Ian Robert

    2014-01-01

    The University of ManchesterIan Robert JinksPh. D. MaterialsThe Viscoelastic Properties of Chemically Modified α-Keratins in Human HairMarch 2014Human hair, like other α-keratinous fibres, is a highly complex biomaterial. For the analysis of its mechanical and thermal properties it is, however, well described by a two-phase structure, which contains as morphological components the highly-ordered, crystalline intermediate filaments (IFs) and the less-ordered, amorphous matrix. The presence of ...

  12. Modified Augmented Lagrange Multiplier Methods for Large-Scale Chemical Process Optimization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Chemical process optimization can be described as large-scale nonlinear constrained minimization. The modified augmented Lagrange multiplier methods (MALMM) for large-scale nonlinear constrained minimization are studied in this paper. The Lagrange function contains the penalty terms on equality and inequality constraints and the methods can be applied to solve a series of bound constrained sub-problems instead of a series of unconstrained sub-problems. The steps of the methods are examined in full detail. Numerical experiments are made for a variety of problems, from small to very large-scale, which show the stability and effectiveness of the methods in large-scale problems.

  13. Fast and simple purification of chemically modified hammerhead ribozymes using a lipophilic capture tag.

    OpenAIRE

    Sproat, B S; Rupp, T; Menhardt, N; Keane, D.; Beijer, B

    1999-01-01

    A new type of 5'-lipophilic capture tag is described, enabling the facile reverse phase HPLC purification of chemically modified hammerhead ribozymes (oligozymes) whilst still carrying the 2'-O-tert.-butyldimethylsilyl protection of the essential riboses. In its most convenient form, the capture tag consists of a simple diol, such as hexan-1,6-diol, which at one end is attached via a silyl residue to a highly lipophilic entity such as tocopherol (vitamin E) or cholesterol, and the other end i...

  14. Highly dispersed Pd nanoparticles on chemically modified graphene with aminophenyl groups for formic acid oxidation

    International Nuclear Information System (INIS)

    A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the aminophenyl groups of p-phenylenediamine. Palladium nanoparticles with an average diameter of 4.2 nm are deposited on the CMG by a liquid-phase borohydride reduction. The electrocatalytic activity and stability of the Pd/CMG composite towards formic acid oxidation are found to be higher than those of reduced graphene oxide and commercial carbon materials such as Vulcan XC-72 supported Pd electrocatalysts. (atomic and molecular physics)

  15. Peroxide-modified titanium dioxide: a chemical analog of putative Martian soil oxidants

    Science.gov (United States)

    Quinn, R. C.; Zent, A. P.

    1999-01-01

    Hydrogen peroxide chemisorbed on titanium dioxide (peroxide-modified titanium dioxide) is investigated as a chemical analog to the putative soil oxidants responsible for the chemical reactivity seen in the Viking biology experiments. When peroxide-modified titanium dioxide (anatase) was exposed to a solution similar to the Viking labeled release (LR) experiment organic medium, CO2 gas was released into the sample cell headspace. Storage of these samples at 10 degrees C for 48 hr prior to exposure to organics resulted in a positive response while storage for 7 days did not. In the Viking LR experiment, storage of the Martian surface samples for 2 sols (approximately 49 hr) resulted in a positive response while storage for 141 sols essentially eliminated the initial rapid release of CO2. Heating the peroxide-modified titanium dioxide to 50 degrees C prior to exposure to organics resulted in a negative response. This is similar to, but not identical to, the Viking samples where heating to approximately 46 degrees C diminished the response by 54-80% and heating to 51.5 apparently eliminated the response. When exposed to water vapor, the peroxide-modified titanium dioxide samples release O2 in a manner similar to the release seen in the Viking gas exchange experiment (GEx). Reactivity is retained upon heating at 50 degrees C for three hours, distinguishing this active agent from the one responsible for the release of CO2 from aqueous organics. The release of CO2 by the peroxide-modified titanium dioxide is attributed to the decomposition of organics by outer-sphere peroxide complexes associated with surface hydroxyl groups, while the release of O2 upon humidification is attributed to more stable inner-sphere peroxide complexes associated with Ti4+ cations. Heating the peroxide-modified titanium dioxide to 145 degrees C inhibited the release of O2, while in the Viking experiments heating to this temperature diminished but did not eliminated the response. Although the

  16. A Mechanistic Study of Chemically Modified Inorganic Membranes for Gas and Liquid Separations

    Energy Technology Data Exchange (ETDEWEB)

    Way, J Douglas

    2011-01-21

    This final report will summarize the progress made during the period August 1, 1993 - October 31, 2010 with support from DOE grant number DE-FG03-93ER14363. The objectives of the research have been to investigate the transport mechanisms in micro- and mesoporous, metal oxide membranes and to examine the relationship between the microstructure of the membrane, the membrane surface chemistry, and the separation performance of the membrane. Examples of the membrane materials under investigation are the microporous silica hollow fiber membrane manufactured by PPG Industries, chemically modified mesoporous oxide membranes, and polymer membranes containing microporous oxides (mixed matrix membranes). Analytical techniques such as NMR, FTIR and Raman spectroscopy, thermal analysis, and gas adsorption were used to investigate membrane microstructure and to probe the chemical interactions occurring at the gas-membrane interface.

  17. Two dimensional solid state NMR methods applied to whole coals and chemically modified coals

    Energy Technology Data Exchange (ETDEWEB)

    Zilm, K.W.; Webb, G.G.; Millar, J.M.

    1987-04-01

    Two dimensional NMR methods have been shown to provide a much finer accounting of the functional types present in coals than by CPMAS spectroscopy alone. The ADIPSHIFT method has been shown to be at least as quantitative as CPMAS both in theory and experimentally. The method gives reliable distributions of carbons with differing multiplicities which is useful in identifying different functionalities that overlap in chemical shift. Recent studies of a model system indicate that the connectivity of the different groups in chemically modified coals should be obtainable from solid state COSY and NOESY experiments. This type of information will provide a very accurate picture of the structure of the alkylated sites and the substitution patterns surrounding them.

  18. Lubricity of bio-based lubricant derived from chemically modified jatropha methyl ester

    Directory of Open Access Journals (Sweden)

    N.W.M. Zulkifli

    2014-06-01

    Full Text Available Many studies have been undertaken with a view to using chemically modified vegetable oil as a bio-based lubricant. This research focused on tribological properties of trimethylolpropane (TMP ester, which is derived from renewable resource. This TMP ester was produced from jatropha methyl ester; it is biodegradable and has high lubricity properties. Two different conditions of lubrication are being investigated: extreme pressure and anti-wear. It was found that the TMP ester (Jatropha has better lubricity in terms of wear and friction compared to paraffin oil under extreme pressure conditions. TMP ester (Jatropha has similar characteristics to fully formulated lubricant (FFL, in terms of the coefficient of friction (CoF. In terms of the anti-wear condition, TMP ester (Jatropha has the lowest CoF; however it also has the high wear scar diameter. This is due to corrosion and chemical attack.

  19. Induction of primary mixed leukocyte reactions with ultraviolet B or chemically modified stimulator cells

    International Nuclear Information System (INIS)

    Treatment of stimulator cells with paraformaldehyde for 60 sec or ultraviolet-B (UV-B) irradiation eliminates their ability to elicit T cell proliferation in a primary mixed leukocyte reaction. However, a T cell response equal to 20-40% of control value could be elicited by paraformaldehyde fixed or UV-B irradiated cells providing the latter are incubated at 37 degrees C for 18 hr prior to treatment. The incubation also induces a one-log increase in the density of fluorescence when the cells are stained with monoclonal antibodies against class II molecules DR and DP as well as the intercellular adhesion molecule -1. We interpret this as an increase in the membrane expression of these structures following incubation. Chloroquine and cerulenin, known to inhibit protein degradation and antigen processing and presentation do not influence the upregulation in membrane expression of these class II and adhesion molecules, but do prevent incubation from overriding the effect of paraformaldehyde treatment. Colchicine, which reduces the traffic through tubular lysosomes, also has no effect on the upregulation but enhances allopresentation. We propose that incubation of stimulator cells in the presence of chloroquine and cerulenin results in the membrane expression of class II molecules without associated peptides. The inability of stimulator cells expressing such nude MHC molecules to elicit T cell proliferation after chemical modification could be due to easier crosslinking of the allodeterminants by paraformaldehyde when the binding site is empty but could also mean that nude MHC molecules are not per se immunogenic and become so only after acquisition of a peptide. It is also possible that chloroquine, NH4Cl, and cerulenin block the expression of signals other than the class II and cell adhesion molecules that are essential for induction of T cell proliferation

  20. Kinetics of cadmium, chromium, and lead sorption onto chemically modified sugarcane bagasse and wheat straw.

    Science.gov (United States)

    Mahmood-ul-Hassan, M; Suthar, V; Rafique, E; Ahmad, R; Yasin, M

    2015-07-01

    In this study, cadmium (Cd), chromium (Cr), and lead (Pb) adsorption potential of unmodified and modified sugarcane bagasse and ground wheat straw was explored from aqueous solution through batch equilibrium technique. Both the materials were chemically modified by treating with sodium hydroxide (NaOH) alone and in combination with nitric acid (HNO3) and sulfuric acid (H2SO4). Two kinetic models, pseudo-first order and pseudo-second order were used to follow the adsorption process and reaction fallowed the later model. The Pb removal by both the materials was highest and followed by Cr and Cd. The chemical treatment invariably increased the adsorption capacity and NaOH treatment proved more effective than others. Langmuir maximum sorption capacity (q m) of Pb was utmost (12.8-23.3 mg/g of sugarcane bagasse, 14.5-22.4 mg/g of wheat straw) and of Cd was least (1.5-2.2 mg/g of sugarcane bagasse, 2.5-3.8 mg/g of wheat straw). The q m was in the order of Pb > Cr > Cd for all the three adsorbents. Results demonstrate that agricultural waste materials used in this study could be used to remediate the heavy metal-polluted water. PMID:26116198

  1. Chemically modified inulin microparticles serving dual function as a protein antigen delivery vehicle and immunostimulatory adjuvant.

    Science.gov (United States)

    Gallovic, Matthew D; Montjoy, Douglas G; Collier, Michael A; Do, Clement; Wyslouzil, Barbara E; Bachelder, Eric M; Ainslie, Kristy M

    2016-02-23

    To develop a new subunit vaccine adjuvant, we chemically modified a naturally-occurring, immunostimulatory inulin polysaccharide to produce an acid-sensitive biopolymer (acetalated inulin, Ace-IN). Various hydrophobic Ace-IN polymers were formed into microparticles (MPs) by oil-in-water emulsions followed by solvent evaporation These Ace-IN MPs possessed tunable degradation characteristics that, unlike polyesters used in FDA-approved microparticulate formulations, had only pH-neutral hydrolytic byproducts. Macrophages were passively targeted with cytocompatible Ace-IN MPs. TNF-α production by macrophages treated with Ace-IN MPs could be altered by adjusting the polymers' chemistry. Mice immunized with Ace-IN MPs encapsulating a model ovalbumin (OVA) antigen showed higher production of anti-OVA IgG antibody levels relative to soluble antigen. The antibody titers were also comparable to an alum-based formulation. This proof-of-concept establishes the potential for chemically-modified inulin MPs to simultaneously enable dual functionality as a stimuli-controlled antigen delivery vehicle and immunostimulatory adjuvant. PMID:26753184

  2. Facile Synthesis of Mono-Dispersed Polystyrene (PS/Ag Composite Microspheres via Modified Chemical Reduction

    Directory of Open Access Journals (Sweden)

    Wen Zhu

    2013-12-01

    Full Text Available A modified method based on in situ chemical reduction was developed to prepare mono-dispersed polystyrene/silver (PS/Ag composite microspheres. In this approach; mono-dispersed PS microspheres were synthesized through dispersion polymerization using poly-vinylpyrrolidone (PVP as a dispersant at first. Then, poly-dopamine (PDA was fabricated to functionally modify the surfaces of PS microspheres. With the addition of [Ag(NH32]+ to the PS dispersion, [Ag(NH32]+ complex ions were absorbed and reduced to silver nanoparticles on the surfaces of PS-PDA microspheres to form PS/Ag composite microspheres. PVP acted both as a solvent of the metallic precursor and as a reducing agent. PDA also acted both as a chemical protocol to immobilize the silver nanoparticles at the PS surface and as a reducing agent. Therefore, no additional reducing agents were needed. The resulting composite microspheres were characterized by TEM, field emission scanning electron microscopy (FESEM, energy-dispersive X-ray spectroscopy (EDS, XRD, UV-Vis and surface-enhanced Raman spectroscopy (SERS. The results showed that Ag nanoparticles (NPs were homogeneously immobilized onto the PS microspheres’ surface in the presence of PDA and PVP. PS/Ag composite microspheres were well formed with a uniform and compact shell layer and were adjustable in terms of their optical property.

  3. Native Chemical Ligation Strategy to Overcome Side Reactions during Fmoc-Based Synthesis of C-Terminal Cysteine-Containing Peptides.

    Science.gov (United States)

    Lelièvre, Dominique; Terrier, Victor P; Delmas, Agnès F; Aucagne, Vincent

    2016-03-01

    The Fmoc-based solid phase synthesis of C-terminal cysteine-containing peptides is problematic, due to side reactions provoked by the pronounced acidity of the Cα proton of cysteine esters. We herein describe a general strategy consisting of the postsynthetic introduction of the C-terminal Cys through a key chemoselective native chemical ligation reaction with N-Hnb-Cys peptide crypto-thioesters. This method was successfully applied to the demanding peptide sequences of two natural products of biological interest, giving remarkably high overall yields compared to that of a state of the art strategy. PMID:26878883

  4. Sensory and rheological properties of transgenically and chemically modified starch ingredients as evaluated in a food product model

    DEFF Research Database (Denmark)

    Ahmt, T.; Wischmann, Bente; Blennow, A.; Madsen, F.; Bandsholm, O.; Thomsen, J.

    2004-01-01

    Starches derived from five genetically modified potato lines, two chemically modified potato starches and two native starches from potato and maize were subjected to physical and chemical analyses and their functionality evaluated in a milk-based food product model. The transgenic starches were...... specifically modified with respect to amylopectin chain length and phosphorous content by suppression of the starch branching enzyme and overexpression of glycogen branching enzyme. Transgenic starches with long amylopectin chains and high phosphorous content had increased gelatinisation temperatures, produced...... gels with a higher tendency to retrograde and a low freeze/thaw stability as compared to starches with shorter amylopectin chains and lower phosphorous content. The textural properties of the food product model prepared from genetically and chemically modified starches were characterised by sensory and...

  5. Characterization of post-translationally modified peptides by hydrophilic interaction and reverse phase liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry.

    Science.gov (United States)

    Hernandez-Hernandez, Oswaldo; Quintanilla-Lopez, Jesus Eduardo; Lebron-Aguilar, Rosa; Sanz, Maria Luz; Moreno, F Javier

    2016-01-01

    This work explores the use of both hydrophilic interaction liquid chromatography (HILIC) and reverse phase liquid chromatography (RPLC) for the separation and subsequent characterization of bovine caseinomacropeptide (CMP) phosphopeptides and O-glycopeptides using a quadrupole-time-of-flight (QTOF) mass spectrometer with electrospray ionization. Two neutral, ethylene bridged hybrid (BEH) amide and polyhydroxyethyl aspartamide (PHEA), and a zwitterionic, sulfobetaine (ZIC), stationary phases were used for the HILIC mode, whilst an octadecylsilane (C18) stationary phase was employed for the RPLC separation. Overall, developed HILIC-QTOF method using the ZIC or BEH amide stationary phases resulted to be the most efficient methods to separate and characterize post-translationally modified (PTM) peptides without the need of any previous fractionation or derivatization step. The separation of phosphopeptides and differently sialylated O-glycopeptides in the ZIC stationary phase was dominated by an electrostatic repulsion interaction mechanism between the negatively charged phosphate groups or sialic acid moieties and the negatively charged terminal sulfonate group of the stationary phase, whereas the separation of either non-modified peptides or neutral O-glycopeptides both free of basic amino acids was based on a partitioning mechanism. In neutral amide columns, the separation was mainly dominated by hydrophilic partitioning, leading to a higher retention of the post-translationally modified peptides than the unmodified counterparts due to the hydrophilicity provided by the phosphate groups and/or O-glycans. As a consequence, HILIC-ESI-QTOF MS operating in the positive ion mode is a powerful tool for the characterization of underivatized O-glycopeptides and phosphopeptides. PMID:26278355

  6. Dual-tracer method to estimate coral reef response to a plume of chemically modified seawater

    Science.gov (United States)

    Maclaren, J. K.; Caldeira, K.

    2013-12-01

    We present a new method, based on measurement of seawater samples, to estimate the response of a reef ecosystem to a plume of an additive (for example, a nutrient or other chemical). In the natural environment, where there may be natural variability in concentrations, it can be difficult to distinguish between changes in concentrations that would occur naturally and changes in concentrations that result from a chemical addition. Furthermore, in the unconfined natural environment, chemically modified water can mix with waters that have not been modified, making it difficult to distinguish between effects of dilution and effects of chemical fluxes or transformations. We present a dual-tracer method that extracts signals from observations that may be affected by both natural variability and dilution. In this dual-tracer method, a substance (in our example case, alkalinity) is added to the water in known proportion to a passive conservative tracer (in our example case, Rhodamine WT dye). The resulting plume of seawater is allowed to flow over the study site. Two transects are drawn across the plume at the front and back of the study site. If, in our example, alkalinity is plotted as a function of dye concentration for the front transect, the slope of the resulting mixing line is the ratio of alkalinity to dye in the added fluid. If a similar mixing line is measured and calculated for the back transect, the slope of this mixing line will indicate the amount of added alkalinity that remains in the water flowing out of the study site per unit of added dye. The ratio of the front and back slopes indicates the fraction of added alkalinity that was taken up by the reef. The method is demonstrated in an experiment performed on One Tree Reef (Queensland, Australia) aimed at showing that ocean acidification is already affecting coral reef growth. In an effort to chemically reverse some of the changes to seawater chemistry that have occurred over the past 200 years, we added

  7. REMOVAL OF Pb (II FROM AQUEOUS SOLUTION WITH ORANGE SUB-PRODUCTS CHEMICALLY MODIFIED AS BIOSORBENT

    Directory of Open Access Journals (Sweden)

    João Valdir Tadioto Miranda De Souza,

    2012-02-01

    Full Text Available The effects of chemical modification of orange peel, bagasse, and a mixture of peel and bagasse for lead ion removal from aqueous medium were evaluated. The chemical modification of biomass was carried out with sodium hydroxide and citric acid to introduce carboxylate groups on the surface of the biomass. Infrared spectra confirmed the presence of carboxylate groups at 1735 cm-1. Adsorption isotherms performed by static adsorption experiments fitted very well to the linear Langmuir and Freundlich models. The experiments were carried out at pH 5 during 500 min of shaking time. Orange modified peel (O-MP presented the highest adsorption capacity (84.5 mg g-1, notably higher than other biosorbents described in the literature. The kinetic studies showed that the process obeyed a pseudo-second-order rate expression, thus indicating a strong interaction between the biosorbent and adsorbate. It was found that the chemical modifications of sorbents promoted an adsorption energetically more spontaneous, as indicated by negative values of Gibbs free energy. On the other hand, desorption studies showed low leaching of lead ions from the biosorbent, thus confirming the strong interaction of lead ions and the biosorbent. The satisfactory maximum adsorption capacity obtained and negligible cost of biosorbent makes the sub-products of orange a reliable natural material for the removal of lead ions from aqueous effluents.

  8. The performance of chemically and physically modified local kaolinite in methanol dehydration to dimethyl ether

    International Nuclear Information System (INIS)

    The catalytic activity of modified natural kaolinite as a solid acid catalyst for dimethyl ether (DME) preparation was investigated by following up the conversion % of methanol and the yield % of DME. Natural kaolinite (KN) was treated chemically with H2O2 (KT) followed by thermal treatment at 500 degree C (KC) and then mechano-chemically by ball milling with and without CaSO4 (KB-Ca and KB, respectively). These samples were characterized by XRD, FTIR, SEM, HRTEM, TGA and NH3 -TPD techniques. The different techniques showed that the chemical treatment of kaolinite with H2O2 resulted in partial exfoliation/delamination of kaolinite, decreased the amount of acidic sites which is accompanied by increasing their strength. Calcination only decreased the acidic strength and slightly enlarged the particle size mostly due to heat effect. Ball milling resulted in multitude randomly-oriented crystals and increased the amount of acidic sites with the same strength of KT sample. CaSO4 mostly produced ordered monocrystalline kaolinite and created new acidic sites with slightly lower strength relative to KB. The catalytic activity and selectivity depend on the reaction temperature, the space velocity and the strength of acid sites. The most active sample is KB-Ca, which gives 84% DME due to its high amount and strength of acidic sites. The different modification methods resulted in 100% selectivity for DME

  9. The chemical synthesis of α-conotoxins and structurally modified analogs with enhanced biological stability.

    Science.gov (United States)

    Banerjee, Jayati; Gyanda, Reena; Chang, Yi-Pin; Armishaw, Christopher J

    2013-01-01

    α-Conotoxins are peptide neurotoxins isolated from the venom ducts of carnivorous marine cone snails that exhibit exquisite pharmacological potency and selectivity for various nicotinic acetylcholine receptor subtypes. As such, they are important research tools and drug leads for treating various diseases of the central nervous system, including pain and tobacco addiction. Despite their therapeutic potential, the chemical synthesis of α-conotoxins for use in structure-activity relationship studies is complicated by the possibility of three disulfide bond isomers, where inefficient folding methods can lead to a poor recovery of the pharmacologically active isomer. In order to achieve higher yields of the native isomer, especially in high-throughput syntheses it is necessary to select appropriate oxidative folding conditions. Moreover, the poor biochemical stability exhibited by α-conotoxins limits their general therapeutic applicability in vivo. Numerous strategies to enhance their stability including the substitution of disulfide bond with diselenide bond and N-to-C cyclization via an oligopeptide spacer have successfully overcome these limitations. This chapter describes methods for performing both selective and nonselective disulfide bond oxidation strategies for controlling the yields and formation of α-conotoxin disulfide bond isomers, as well as methods for the production of highly stable diselenide-containing and N-to-C cyclized conotoxin analogs. PMID:24014431

  10. A chemically synthesized peptide which elicits humoral and cellular immune responses to mycobacterial antigens.

    OpenAIRE

    Minden, P; Houghten, R A; Spear, J R; Shinnick, T M

    1986-01-01

    Monoclonal antibodies directed to Mycobacterium bovis BCG (BCG) and to M. tuberculosis H37Rv (H37Rv) were used in conjunction with affinity chromatography to prepare a mycobacterial component which was designated BCG-a. A synthetic peptide antigen was prepared based on the amino acid sequence of BCG-a and was designated BCG-a-P. Significant immunological similarities were found between BCG-a-P and antigens in extracts of BCG and H37Rv but not between BCG-a-P and antigens of nontuberculous myc...

  11. Chemically modified and nanostructured porous silicon as a drug delivery material and device

    Science.gov (United States)

    Anglin, Emily Jessica

    This thesis describes the fabrication, chemical modification, drug release, and toxicity studies of nanostructured porous silicon for the purposes of developing a smart drug delivery device. The first chapter is an introductory chapter, presenting the chemical and physical properties of porous silicon, the concepts and issues of current drug delivery devices and materials, and how porous silicon can address the issues regarding localized and controlled drug therapies. The second chapter discusses chemical modifications of nanostructured porous Si for stabilizing the material in biologically relevant media while providing an extended release of a therapeutic in vitro. This chapter also demonstrates the utility of the porous silicon optical signatures for effectively monitoring drug release from the system and its applications for development of a self-reporting drug delivery device. In chapter three, the concept of providing a triggered release of a therapeutic from porous silicon microparticles through initiation by an external stimulus is demonstrated. The microparticles are chemically modified, and the release is enhanced by a short application of ultrasound to the particulate system. The effect of ultrasound on the drug release and particle size is discussed. Chapter four presents a new method for sustaining the release of a monoclonal antibody from the porous matrix of porous SiO2. The therapeutic is incorporated into the films through electrostatic adsorption and a slow release is observed in vitro. A new method of quantifying the extent of drug loading is monitored with interferometry. The last chapter of the thesis provides a basic in vivo toxicity study of various porous Si microparticles for intraocular applications. Three types of porous Si particles are fabricated and studied in a rabbit eye model. The toxicity studies were conducted by collaborators at the Shiley Eye Center, La Jolla, CA. This work, demonstrates the feasibility of developing a self

  12. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    CERN Document Server

    Blanc, Wilfried; Nguyen, Luan; Bhaktha, S N B; Sebbah, Patrick; Pal, Bishnu P; Dussardier, Bernard

    2011-01-01

    Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporati...

  13. Effect of three biological response modifiers on chemical carcinogenesis in mice.

    Science.gov (United States)

    Bogdanović, Z; Culo, F; Marusić, M

    1993-01-01

    The modulation of chemical carcinogenesis by three biological response modifiers was assessed in a mouse model. CBA mice given 20-methylcholanthrene s.c. were treated with peptidoglycan monomer, azure B and indomethacin for one month, either from day 0 or 75 after methylcholanthrene injection to assess their effects on tumor incidence (on days 150 and 300), time of tumor appearance, time of death, and duration and dynamics of tumor growth. All three agents significantly influenced some of the parameters of tumor growth, except tumor incidence on day 300. Highly significant sex differences in tumor appearance and growth were observed. Tumors with late appearance grew faster in comparison to tumors with early appearance. The data presented indicate that the effectiveness of anti-cancer body defense mechanisms can be best defined by the time of tumor appearance. PMID:8272149

  14. Immobilization of chemically modified horse radish peroxidase within activated alginate beads

    Directory of Open Access Journals (Sweden)

    Spasojević Dragica

    2014-01-01

    Full Text Available Immobilization of horse radish peroxidase (HRP within alginate beads was improved by chemical modification of the enzyme and polysaccharide chains. HRP and alginate were oxidized by periodate and subsequently modified with ethylenediamine. Highest specific activity of 0.43 U/ml of gel and 81 % of bound enzyme activity was obtained using aminated HRP and alginate oxidized by periodate. Immobilized enzyme retained 75 % of original activity after 2 days of incubation in 80 % (v/v dioxane and had increased activity at basic pH values compared to native enzyme. During repeated use in batch reactor for pyrogallol oxidation immobilized peroxidase retained 75 % of original activity. [Projekat Ministarstva nauke Republike Srbije, br. ON173017 i br. ON172049

  15. Genetic and chemical modifiers of a CUG toxicity model in Drosophila.

    Directory of Open Access Journals (Sweden)

    Amparo Garcia-Lopez

    Full Text Available Non-coding CUG repeat expansions interfere with the activity of human Muscleblind-like (MBNL proteins contributing to myotonic dystrophy 1 (DM1. To understand this toxic RNA gain-of-function mechanism we developed a Drosophila model expressing 60 pure and 480 interrupted CUG repeats in the context of a non-translatable RNA. These flies reproduced aspects of the DM1 pathology, most notably nuclear accumulation of CUG transcripts, muscle degeneration, splicing misregulation, and diminished Muscleblind function in vivo. Reduced Muscleblind activity was evident from the sensitivity of CUG-induced phenotypes to a decrease in muscleblind genetic dosage and rescue by MBNL1 expression, and further supported by the co-localization of Muscleblind and CUG repeat RNA in ribonuclear foci. Targeted expression of CUG repeats to the developing eye and brain mushroom bodies was toxic leading to rough eyes and semilethality, respectively. These phenotypes were utilized to identify genetic and chemical modifiers of the CUG-induced toxicity. 15 genetic modifiers of the rough eye phenotype were isolated. These genes identify putative cellular processes unknown to be altered by CUG repeat RNA, and they include mRNA export factor Aly, apoptosis inhibitor Thread, chromatin remodelling factor Nurf-38, and extracellular matrix structural component Viking. Ten chemical compounds suppressed the semilethal phenotype. These compounds significantly improved viability of CUG expressing flies and included non-steroidal anti-inflammatory agents (ketoprofen, muscarinic, cholinergic and histamine receptor inhibitors (orphenadrine, and drugs that can affect sodium and calcium metabolism such as clenbuterol and spironolactone. These findings provide new insights into the DM1 phenotype, and suggest novel candidates for DM1 treatments.

  16. Bone marrow stromal cells cultured on poly (lactide-co-glycolide)/nano-hydroxyapatite composites with chemical immobilization of Arg-Gly-Asp peptide and preliminary bone regeneration of mandibular defect thereof.

    Science.gov (United States)

    Huang, Yanxia; Ren, Jie; Ren, Tianbin; Gu, Shuying; Tan, Qinggang; Zhang, Lihong; Lv, Kaige; Pan, Kefeng; Jiang, Xinquan

    2010-12-15

    Polyethyleneimine (PEI) was used to create active groups on the poly (lactide-co-glycolide)/nano-hydroxyapatite (PLGA/NHA) surface and Arg-Gly-Asp (RGD) was grafted on the active groups and novel PLGA/NHA 2-D membranes and 3D scaffolds modified with RGD were obtained. X-ray photoelectron spectrum (XPS) results show that sulfur displays only on the modified surface. The RGD-modified PLGA/NHA materials also have much lower static water contact angle and much higher water-absorption ability, which shows that after chemical treatment, the modified materials show better hydrophilic properties. Atomic force microscope (AFM) shows that after surface modification, the surface morphology of PLGA is greatly changed. All these results indicate that RGD peptide has successfully grafted on the surface of PLGA. Rabbit bone marrow stromal cells (MSCs) were seeded in the 2D membranes and 3D scaffolds materials. The influences of the RGD on the cell attachment, growth and differentiation, and proliferation on the different materials were studied. The modified scaffolds were implanted into rabbits to observe preliminary application in regeneration of mandibular defect. The PLGA/NHA-RGD presents better results in bone regeneration in rabbit mandibular defect. PMID:20872750

  17. Synthetic procedure for N-Fmoc amino acyl-N-sulfanylethylaniline linker as crypto-peptide thioester precursor with application to native chemical ligation.

    Science.gov (United States)

    Sakamoto, Ken; Sato, Kohei; Shigenaga, Akira; Tsuji, Kohei; Tsuda, Shugo; Hibino, Hajime; Nishiuchi, Yuji; Otaka, Akira

    2012-08-17

    N-sulfanylethylanilide (SEAlide) peptides 1, obtainable using Fmoc-based solid-phase peptide synthesis (Fmoc SPPS), function as crypto-thioesters in native chemical ligation (NCL), yielding a wide variety of peptides/proteins. Their acylating potential with N-terminal cysteinyl peptides 2 can be tuned by the presence or absence of phosphate salts, leading to one-pot/multifragment ligation, operating under kinetically controlled conditions. SEAlide peptides have already been shown to be promising for use in protein synthesis; however, a widely applicable method for the synthesis of N-Fmoc amino acyl-N-sulfanylethylaniline linkers 4, required for the preparation of SEAlide peptides, is unavailable. The present study addresses the development of efficient condensation protocols of 20 naturally occurring amino acid derivatives to the N-sulfanylethylaniline linker 5. N-Fmoc amino acyl aniline linkers 4 of practical use in NCL chemistry, except in the case of the proline- or aspartic acid-containing linker, were successfully synthesized by coupling of POCl(3)- or SOCl(2)-activated Fmoc amino acid derivatives with sodium anilide species 6, without accompanying racemization and loss of side-chain protection. Furthermore, SEAlide peptides 7 possessing various C-terminal amino acids (Gly, His, Phe, Ala, Asn, Ser, Glu, and Val) were shown to be of practical use in NCL chemistry. PMID:22816612

  18. Kinetic and thermodynamic studies on biosorption of Cu(Ⅱ) by chemically modified orange peel

    Institute of Scientific and Technical Information of China (English)

    FENG Ning-chuan; GUO Xue-yi; LIANG Sha

    2009-01-01

    Cu(H) biosorption by orange peel that was chemically modified with sodium hydroxide and calcium chloride was investigated. The effects of temperature, contact time, initial concentration of metal ions and pH on the biosorption of Cu( II) ions were assessed. Thermodynamic parameters including change of free energy(△G~Θ), enthalpy (△H~Θ) and entropy(△S~Θ) during the biosorption were determined. The results show that the biosorption process of Cu( II) ions by chemically treated orange peel is feasible, spontaneous and exothermic under studied conditions. Equilibrium is well described by Langmuir equation with the maximum biosorption capacity(q_m) for Cu( II) as 72.73 mg/g and kinetics is found to fit pseudo-second order type biosorption kinetics. As the temperature increases from 16 ℃ to 60 ℃, copper biosorption decreases. The loaded biosorbent is regenerated using HC1 solution for repeatedly use for five times with little loss of biosorption capacity.

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

    International Nuclear Information System (INIS)

    Hydroxyapatite (HA)-based nanocomposites were prepared by a co-precipitation method with silk fibroin (SF) serving as organic matrix. Silk fibroin was chemically modified with an alkali solution or an enzyme attempting to improve the interface between the mineral and the organic matrix. The influences of the alkali and enzyme pretreatments on microstructure and physicochemical properties of HA-SF composite were examined and compared. The results reveal that both the two kinds of pretreatments facilitate the formation of highly ordered three-dimensional porous network throughout the composites, increase the microhardness of the composite, and promote the preferential growth of HA crystallites along c-axis. Among all the as-prepared samples, the composite containing the enzyme pretreated SF shows desirable hierarchical microstructure with higher degree of organization and more uniform pore size distribution. Due to the enzyme pretreatment, HA crystallites undergo obvious changes in morphology from rod-like to whisker-like and in crystal growth towards more apparent epitaxy along c-axis. The alkali pretreatment induces the stronger chemical interactions between HA and SF and thus to strengthen the inorganic-organic interfacial adhesion. The newly developed HA-SF composites are expected to be attractive biomedical materials for bone repair and remodeling

  20. Efficiency of modified chemical remediation techniques for soil contaminated by organochlorine pesticides

    Science.gov (United States)

    Correa-Torres, S. N.; Kopytko, M.; Avila, S.

    2016-07-01

    This study reports the optimization of innovation chemical techniques in order to improve the remediation of soils contaminated with organochloride pesticides. The techniques used for remediation were dehalogenation and chemical oxidation in soil contaminated by pesticides. These techniques were applied sequentially and combined to evaluate the design optimize the concentration and contact time variables. The soil of this study was collect in cotton crop zone in Agustin Codazzi municipality, Colombia, and its physical properties was measure. The modified dehalogenation technique of EPA was applied on the contaminated soil by adding Sodium Bicarbonate solution at different concentrations and rates during 4, 7 and 14 days, subsequently oxidation technique was implemented by applying a solution of KMnO4 at different concentration and reaction times. Organochlorine were detected by Gas Chromatography analysis coupled Mass Spectrometry and its removals were between 85.4- 90.0% of compounds such as 4, 4’-DDT, 4,4’-DDD, 4,4-DDE, trans-Clordane y Endrin. These results demonstrate that the technique of dehalogenation with oxidation chemistry can be used for remediation soils contaminated by organochloride pesticides.

  1. Sensory and rheological properties of transgenically and chemically modified starch ingredients as evaluated in a food product model

    DEFF Research Database (Denmark)

    Ahmt, T.; Wischmann, Bente; Blennow, A.;

    2004-01-01

    Starches derived from five genetically modified potato lines, two chemically modified potato starches and two native starches from potato and maize were subjected to physical and chemical analyses and their functionality evaluated in a milk-based food product model. The transgenic starches were...... specifically modified with respect to amylopectin chain length and phosphorous content by suppression of the starch branching enzyme and overexpression of glycogen branching enzyme. Transgenic starches with long amylopectin chains and high phosphorous content had increased gelatinisation temperatures, produced...... rheological analyses. To clearly visualise the effects of the modifications, data was evaluated by radar plots and multiple regression analysis (chemometrics). Genetically modified potato starches with longer amylopectin chains and increased phosphorous content gave a more gelled and a shorter texture as...

  2. A new class of HIV-1 protease inhibitor: the crystallographic structure, inhibition and chemical synthesis of an aminimide peptide isostere.

    Science.gov (United States)

    Rutenber, E E; McPhee, F; Kaplan, A P; Gallion, S L; Hogan, J C; Craik, C S; Stroud, R M

    1996-09-01

    The essential role of HIV-1 protease (HIV-1 PR) in the viral life cycle makes it an attractive target for the development of substrate-based inhibitors that may find efficacy as anti-AIDS drugs. However, resistance has arisen to potent peptidomimetic drugs necessitating the further development of novel chemical backbones for diversity based chemistry focused on probing the active site for inhibitor interactions and binding modes that evade protease resistance. AQ148 is a potent inhibitor of HIV-1 PR and represents a new class of transition state analogues incorporating an aminimide peptide isostere. A 3-D crystallographic structure of AQ148, a tetrapeptide isostere, has been determined in complex with its target HIV-1 PR to a resolution of 2.5 A and used to evaluate the specific structural determinants of AQ148 potency and to correlate structure-activity relationships within the class of related compounds. AQ148 is a competitive inhibitor of HIV-1 PR with a Ki value of 137 nM. Twenty-nine derivatives have been synthesized and chemical modifications have been made at the P1, P2, P1', and P2' sites. The atomic resolution structure of AQ148 bound to HIV-1 PR reveals both an inhibitor binding mode that closely resembles that of other peptidomimetic inhibitors and specific protein/inhibitor interactions that correlate with structure-activity relationships. The structure provides the basis for the design, synthesis and evaluation of the next generation of hydroxyethyl aminimide inhibitors. The aminimide peptide isostere is a scaffold with favorable biological properties well suited to both the combinatorial methods of peptidomimesis and the rational design of potent and specific substrate-based analogues. PMID:8894111

  3. What Goes around Comes around-A Comparative Study of the Influence of Chemical Modifications on the Antimicrobial Properties of Small Cyclic Peptides

    Directory of Open Access Journals (Sweden)

    Margitta Dathe

    2013-09-01

    Full Text Available Tryptophan and arginine-rich cyclic hexapeptides of the type cyclo-RRRWFW combine high antibacterial activity with rapid cell killing kinetics, but show low toxicity in human cell lines. The peptides fulfil the structural requirements for membrane interaction such as high amphipathicity and cationic charge, but membrane permeabilisation, which is the most common mode of action of antimicrobial peptides (AMPs, could not be observed. Our current studies focus on elucidating a putative membrane translocation mechanism whereupon the peptides might interfere with intracellular processes. These investigations require particular analytical tools: fluorescent analogues and peptides bearing appropriate reactive groups were synthesized and characterized in order to be used in confocal laser scanning microscopy and HPLC analysis. We found that minimal changes in both the cationic and hydrophobic domain of the peptides in most cases led to significant reduction of antimicrobial activity and/or changes in the mode of action. However, we were able to identify two modified peptides which exhibited properties similar to those of the cyclic parent hexapeptide and are suitable for subsequent studies on membrane translocation and uptake into bacterial cells.

  4. Surface chemical and biological characterization of flax fabrics modified with silver nanoparticles for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Paladini, F., E-mail: federica.paladini@unisalento.it [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy); Picca, R.A.; Sportelli, M.C.; Cioffi, N. [Department of Chemistry, University of Bari “Aldo Moro”, Via Orabona 4, 70126 Bari (Italy); Sannino, A.; Pollini, M. [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy)

    2015-07-01

    Silver nanophases are increasingly used as effective antibacterial agent for biomedical applications and wound healing. This work aims to investigate the surface chemical composition and biological properties of silver nanoparticle-modified flax substrates. Silver coatings were deposited on textiles through the in situ photo-reduction of a silver solution, by means of a large-scale apparatus. The silver-coated materials were characterized through X-ray Photoelectron Spectroscopy (XPS), to assess the surface elemental composition of the coatings, and the chemical speciation of both the substrate and the antibacterial nanophases. A detailed investigation of XPS high resolution regions outlined that silver is mainly present on nanophases' surface as Ag{sub 2}O. Scanning electron microscopy and energy dispersive X-ray spectroscopy were also carried out, in order to visualize the distribution of silver particles on the fibers. The materials were also characterized from a biological point of view in terms of antibacterial capability and cytotoxicity. Agar diffusion tests and bacterial enumeration tests were performed on Gram positive and Gram negative bacteria, namely Staphylococcus aureus and Escherichia coli. In vitro cytotoxicity tests were performed through the extract method on murine fibroblasts in order to verify if the presence of the silver coating affected the cellular viability and proliferation. Durability of the coating was also assessed, thus confirming the successful scaling up of the process, which will be therefore available for large-scale production. - Highlights: • Silver nanophases are increasingly used as effective antibacterial agent for biomedical applications. • Silver coatings were deposited on textiles through the in situ photo-reduction of a silver solution. • Flax fabrics were characterized from a biological and surface chemical point of view. • Scaling up of the process was confirmed.

  5. Surface chemical and biological characterization of flax fabrics modified with silver nanoparticles for biomedical applications

    International Nuclear Information System (INIS)

    Silver nanophases are increasingly used as effective antibacterial agent for biomedical applications and wound healing. This work aims to investigate the surface chemical composition and biological properties of silver nanoparticle-modified flax substrates. Silver coatings were deposited on textiles through the in situ photo-reduction of a silver solution, by means of a large-scale apparatus. The silver-coated materials were characterized through X-ray Photoelectron Spectroscopy (XPS), to assess the surface elemental composition of the coatings, and the chemical speciation of both the substrate and the antibacterial nanophases. A detailed investigation of XPS high resolution regions outlined that silver is mainly present on nanophases' surface as Ag2O. Scanning electron microscopy and energy dispersive X-ray spectroscopy were also carried out, in order to visualize the distribution of silver particles on the fibers. The materials were also characterized from a biological point of view in terms of antibacterial capability and cytotoxicity. Agar diffusion tests and bacterial enumeration tests were performed on Gram positive and Gram negative bacteria, namely Staphylococcus aureus and Escherichia coli. In vitro cytotoxicity tests were performed through the extract method on murine fibroblasts in order to verify if the presence of the silver coating affected the cellular viability and proliferation. Durability of the coating was also assessed, thus confirming the successful scaling up of the process, which will be therefore available for large-scale production. - Highlights: • Silver nanophases are increasingly used as effective antibacterial agent for biomedical applications. • Silver coatings were deposited on textiles through the in situ photo-reduction of a silver solution. • Flax fabrics were characterized from a biological and surface chemical point of view. • Scaling up of the process was confirmed

  6. Enhanced compatibility of chemically modified titanium surface with periodontal ligament cells

    Science.gov (United States)

    Kado, T.; Hidaka, T.; Aita, H.; Endo, K.; Furuichi, Y.

    2012-12-01

    A simple chemical modification method was developed to immobilize cell-adhesive molecules on a titanium surface to improve its compatibility with human periodontal ligament cells (HPDLCs).The polished titanium disk was immersed in 1% (v/v) p-vinylbenzoic acid solution for 2 h to introduce carboxyl groups onto the surface. After rinsing with distilled deionized water, the titanium disk was dipped into 1.47% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide solution containing 0.1 mg/ml Gly-Arg-Gly-Asp-Ser (GRGDS), human plasma fibronectin (pFN), or type I collagen from calf skin (Col) to covalently immobilize the cell-adhesive molecules on the titanium surface via formation of peptide bonds. X-ray photoelectron spectroscopy analyses revealed that cell-adhesive molecules were successfully immobilized on the titanium surfaces. The Col-immobilized titanium surface revealed higher values regarding nano rough characteristics than the as-polished titanium surface under scanning probe microscopy. The number of HPDLCs attached to both the pFN- and Col-immobilized titanium surfaces was twice that attached to the as-polished titanium surfaces. The cells were larger with the cellular processes that stretched to a greater extent on the pFN- and Col-immobilized titanium surfaces than on the as-polished titanium surface (p < 0.05). HPDLCs on the Col-immobilized titanium surfaces showed more extensive expression of vinculin at the tips of cell projections and more contiguously along the cell outline than on the as-polished, GRGDS-immobilized and pFN-immobilized titanium surfaces. It was concluded that cell-adhesive molecules successfully immobilized on the titanium surface and improved the compatibility of the surface with HPDLCs. The Col-immobilized titanium surface could be used for forming ligament-like tissues around titanium dental implants.

  7. Pharmacological characterization of lipidized analogs of prolactin-releasing peptide with a modified C-terminal aromatic ring

    Czech Academy of Sciences Publication Activity Database

    Pražienková, Veronika; Tichá, Anežka; Blechová, Miroslava; Špolcová, Andrea; Železná, Blanka; Maletínská, Lenka

    2016-01-01

    Roč. 67, č. 1 (2016), s. 121-128. ISSN 0867-5910 R&D Projects: GA ČR(CZ) GA15-08679S Institutional support: RVO:61388963 Keywords : prolactin-releasing peptide * blood-brain barrier * food intake * lipidization * phenylalanine derivatives Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 2.386, year: 2014 http://www.jpp.krakow.pl/journal/archive/02_16/articles/11_article.html

  8. Effect of emulsifiers on complexation and retrogradation characteristics of native and chemically modified White sorghum (Sorghum bicolor) starch

    International Nuclear Information System (INIS)

    Highlights: ► Sorghum starches were chemically modified. ► Starch–lipid complexes were studied in the presence of emulsifiers. ► Type II complexes were also detected in native and oxidized starches on adding GMS. ► Starch–lipid complexes sharply reduced retrogradation in modified starches. - Abstract: The effect of emulsifiers on complexation and retrogradation characteristics of native and chemically modified white sorghum starches was studied. Complex forming tendency of white sorghum starch with commercially available emulsifiers GMS and DATEM improved after acetylation. Presence of emulsifiers reduced λmax (wavelength of maximum absorbance) both for native and modified sorghum starches suggesting lower availability of amylose chains to complex with iodine. In native white sorghum starch (NWSS) and oxidized white sorghum starch (OWSS), both Type I and Type II starch–lipid complexes were observed on addition of 1.0% GMS prior to gelatinization. Acetylated-oxidized white sorghum starch (AOWSS) formed weakest complexes among all the modified starches. The results revealed that antistaling characteristics of modified sorghum starches were enhanced when used in combination with emulsifiers. The most prominent decline in reassociative capability among modified starches was observed for acetylated starches.

  9. Benchmarks for the 13C NMR chemical shielding tensors in peptides in the solid state

    Science.gov (United States)

    Czernek, Jiří; Pawlak, Tomasz; Potrzebowski, Marek J.

    2012-02-01

    The benchmark set is proposed, which comprises 126 principal elements of chemical shielding tensors, and the respective isotropic chemical shielding values, of all 42 13C nuclei in crystalline Tyr-D-Ala-Phe and Tyr-Ala-Phe tripeptides with known, but highly dissimilar structures. These data are obtained by both the NMR measurements and the density functional theory in the pseudopotential plane-wave scheme. Using the CASTEP program, several computational strategies are employed, for which the level of agreement between calculations and experiment is established. This set is mainly intended for the validation of methods capable of predicting the 13C NMR parameters in solid-state systems.

  10. Chemical reaction of sputtered Cu film with PI modified by low energy reactive atomic beam

    International Nuclear Information System (INIS)

    Polyimide (PMDA-ODA) surface was irradiated by low energy reactive atomic beam with energy 160-180 eV to enhance the adhesion with metal Cu film. O2+ and N2+ ions were irradiated at the fluence from 5 x 1015 to 1 x 1018 cm-2. Wetting angle 78o of distilled deionized (DI) water for bare PI was greatly reduced down to 2-4o after critical ion flounce, and the surface energy was increased from 37 to 81.2 erg/cm. From the analysis of O 1s core-level XPS spectra, such improvement seemed to result from the increment of hydrophilic carbonyl oxygen content on modified PI surface. To see more carefully correlation of the peel strength with interfacial reaction between Cu and PI, flexible copper clad laminate with Cu (9 μm)/Cu (200 nm) on modified PI substrate (25 μm) was fabricated by successive sputtering and electroplating. Firstly, peel strength was measured by using t-test and it was largely increased from 0.2 to 0.5 kgf/cm for Ar+ only irradiated PI to 0.72-0.8 kgf/cm for O2+ or N2O+ irradiated PI. Chemical reaction at the interface was reasoned by analyzing C 1s, O 1s, N 1s, and Cu 2p core-level X-ray photoelectron spectroscopy over the as-cleaved Cu-side and PI side surface through depth profiling. From the C 1s spectra of cleaved Cu-side, by the electron transfer from Cu to carbonyl oxygen, carbonyl carbon atom became less positive and as a result shifted to lower binding energy not reaching the binding energy of C2 and C3. The binding energy shift of the peak C4 as small as 1.7 eV indicates that carbonyl oxygen atoms were not completely broken. From the analysis of the O 1s spectra, it was found that new peak at 530.5 eV (O3) was occurred and the increased area of the peak O3 was almost the same with reduced area of the peak carbonyl oxygen peak O1. Since there was no change in the relative intensity of ether oxygen (O2) to carbonyl oxygen (O1), and thus O3 was believed to result from Cu oxide formation via a local bonding of Cu with carbonyl oxygen atoms

  11. Structure and magnetic properties of detonation nanodiamond chemically modified by copper

    Science.gov (United States)

    Shames, A. I.; Panich, A. M.; Osipov, V. Yu.; Aleksenskiy, A. E.; Vul', A. Ya.; Enoki, T.; Takai, K.

    2010-01-01

    We report on detailed study of detonation nanodiamonds (DNDs) whose surface has been chemically modified by copper with the aid of ion exchange in water DND suspension. High resolution transmission electron microscopy, Raman, IR, electron magnetic resonance (EMR), nuclear magnetic resonance (NMR), and superconducting quantum interference device techniques were used for the characterization of DND. Carboxyl groups, appearing on the surface of a nanodiamond particle during its synthesis and purification processes, provide an effective binding of divalent copper ions to the surface. The binding results from the ion exchange between metal cations and protons of surface carboxyl groups in water solutions. IR data evidence the presence of multiple COC groups in the dried copper-modified DND product. Both EMR and C13 NMR provide direct evidences of the appearance of isolated Cu2+ ions on the surface of the 5 nm nanodiamond particles. EMR spectra reveal well-pronounced hyperfine structure due to C63,65u nuclear spin I =3/2 with the spectral pattern which is typical for mononuclear axially distorted Cu2+ complexes in polycrystals. Using Cu2+ ions as paramagnetic probes two-component model of carbon inherited paramagnetic centers in DND is suggested. Magnetic susceptibility for all samples follows the Curie-Weiss law above 30 K. The concentration of magnetically observable copper ions Cu2+ (spin S =1/2) localized on the nanodiamonds surface increases up to approximately 1.5-3.5 ions per nanoparticle with increasing concentration of copper acetate in starting solutions.

  12. Recognition of RNA duplexes by chemically modified triplex-forming oligonucleotides.

    Science.gov (United States)

    Zhou, Yuan; Kierzek, Elzbieta; Loo, Zi Ping; Antonio, Meraldo; Yau, Yin Hoe; Chuah, York Wieo; Geifman-Shochat, Susana; Kierzek, Ryszard; Chen, Gang

    2013-07-01

    Triplex is emerging as an important RNA tertiary structure motif, in which consecutive non-canonical base pairs form between a duplex and a third strand. RNA duplex region is also often functionally important site for protein binding. Thus, triplex-forming oligonucleotides (TFOs) may be developed to regulate various biological functions involving RNA, such as viral ribosomal frameshifting and reverse transcription. How chemical modification in TFOs affects RNA triplex stability, however, is not well understood. Here, we incorporated locked nucleic acid, 2-thio U- and 2'-O methyl-modified residues in a series of all pyrimidine RNA TFOs, and we studied the binding to two RNA hairpin structures. The 12-base-triple major-groove pyrimidine-purine-pyrimidine triplex structures form between the duplex regions of RNA/DNA hairpins and the complementary RNA TFOs. Ultraviolet-absorbance-detected thermal melting studies reveal that the locked nucleic acid and 2-thio U modifications in TFOs strongly enhance triplex formation with both parental RNA and DNA duplex regions. In addition, we found that incorporation of 2'-O methyl-modified residues in a TFO destabilizes and stabilizes triplex formation with RNA and DNA duplex regions, respectively. The (de)stabilization of RNA triplex formation may be facilitated through modulation of van der Waals contact, base stacking, hydrogen bonding, backbone pre-organization, geometric compatibility and/or dehydration energy. Better understanding of the molecular determinants of RNA triplex structure stability lays the foundation for designing and discovering novel sequence-specific duplex-binding ligands as diagnostic and therapeutic agents targeting RNA. PMID:23658228

  13. Adsorption Studies of Phenol Using Thermally and Chemically Modified Rice Husk as Adsorbents

    Directory of Open Access Journals (Sweden)

    *M. M. Yousaf

    2014-03-01

    Full Text Available Most of the Phenols are hazardous substances and some are supposed to have carcinogenic activity. Thus it is necessary to remove Phenolics and other aromatics from the aqueous ecosystem. Traditional processes for the removal of Phenolics compounds are extraction, adsorption on granulated activated carbon, steam distillation, chemical and bacterial techniques. Literature survey show a number of methods like oxidation, ion exchange, reverse osmosis, electrochemical oxidation and adsorption. Phenol removal by process like, adsorption is the best method of choice as it can remove most of phenols in simple and easy way. In recent past; agricultural by-products such as, maize cob, date stone, apricot Stones, rice bran, and bagass pith have been extensively studied and used as adsorbents for the adsorption of hazardous substances from wastewater. In the present study we tried modified rice husks as potential adsorbents for the removal of Phenol from aqueous system. Batch mode studies were carried out. Isotherm data was generated and fitted in Freundlich and Langmuir equation to explain the phenomenon of adsorption. The adsorption capacities based on Langmuir model (Qm of the 3 adsorbents were found to be 0.81 for raw husk (RH, 0.395 for the Grafted (G and 2.306 mg/g for the Charred (C. The R2 values were 0.92 for raw husk, 0.97 for grafted and 0.91 for charred husk. Based on Freundlich model the adsorption capacities (K were 2.94, 2.29 and 1.25mg/g for Raw husk, grafted husk and charred husk. The R2 values were found to be 0.72, 0.95 and 0.83 for the raw husk, grafted husk and charred husk respectively. Our result showed that modified rice husks could be used as potential adsorbents for Phenol removal from aqueous system.

  14. Synthesis and physicochemical characterization of chemically modified chitosan by succinic anhydride

    Directory of Open Access Journals (Sweden)

    Karine Gargioni Pereira Correa de Mello

    2006-07-01

    Full Text Available The N-succinil-chitosan is a chemically modified derivative of the biopolymer chitosan. The succinic anhydride attached to the free amino groups presented along the chitosan's polymer chain imparts to the molecule different physicochemical properties not exhibited before the modification. These chemical modifications enhance chitosan's solubility in slightly acid, neutral and alkaline media. These properties are related to the long alkyl chains attached to hydrophilic parts. In this case the hydrophilic part of D-glucosamine promotes stronger interactions with the water molecules, and consequently, enhances the solubility of the chitosan polymer. Non-modified free chitosan is soluble only in acidic medium (pH A N-succinil-quitosana é um derivado quimicamente modificado do biopolímero quitosana. A inserção de substituintes de anidrido succínico nas aminas protonadas presentes ao longo da cadeia do polímero quitosana, conferem diferentes características físico-químicas a molécula de quitosana. Esta modificação química, possibilitou à quitosana, solubilidade em pHs que variam do ácido (2.0 a 3.0 até alcalino (13.0 a 14.0. Estas propriedades são atribuídas ao alongamento da cadeia alquílica, que afasta a parte hidrofílica da cadeia fechada da D-glicosamina, facilitando o acesso da água, a qual irá estabelecer uma interação mais forte com a molécula de quitosana. Esta propriedade não está presente em amostras de quitosana pura, a qual sabe-se que solubiliza-se apenas em pH abaixo de 5.5. Estas modificações na quitosana possibilitam novas aplicações na área de biotecnologia, uma vez que a solubilidade em meio neutro e levemente alcalino é importante na área biológica.

  15. Chemical Sensors Based on IR Spectroscopy and Surface-Modified Waveguides

    Science.gov (United States)

    Lopez, Gabriel P.; Niemczyk, Thomas

    1999-01-01

    Sol-gel processing techniques have been used to apply thin porous films to the surfaces of planar infrared (IR) waveguides to produce widely useful chemical sensors. The thin- film coating serves to diminish the concentration of water and increase the concentration of the analyte in the region probed by the evanescent IR wave. These porous films are composed of silica, and therefore, conventional silica surface modification techniques can be used to give the surface a specific functional character. The sol-gel film was surface-modified to make the film highly hydrophobic. These sensors were shown to be capable of detecting non-polar organic analytes, such as benzonitrile, in aqueous solution with detection limits in the ppb range. Further, these porous sol-gel structures allow the analytes to diffuse into and out of the films rapidly, thus reaching equilibrium in less than ten seconds. These sensors are unique because of the fact that their operation is based on the measurement of an IR absorption spectrum. Thus, these sensors are able to identify the analytes as well as measure concentration with high sensitivity. These developments have been documented in previous reports and publications. Recently, we have also targeted detection of the polar organic molecules acetone and isopropanol in aqueous solution. Polar organics are widely used in industrial and chemical processes, hence it is of interest to monitor their presence in effluents or decontamination process flows. Although large improvements in detection limits were expected with non-polar organic molecules in aqueous solutions using very hydrophobic porous sol-gel films on silicon attenuated total reflectance (Si ATR) waveguides, it was not as clear what the detection enhancements might be for polar organic molecules. This report describes the use of modified sol-gel-coated Si ATR sensors for trace detection and quantitation of small polar organic molecules in aqueous solutions. The detection of both acetone

  16. Biological evaluation of an ornithine-modified 99mTc-labeled RGD peptide as an angiogenesis imaging agent

    International Nuclear Information System (INIS)

    Introduction: Radiolabeled RGD peptides that specifically target integrin ανβ3 have great potential in early tumor detection through noninvasive monitoring of tumor angiogenesis. Based on previous findings of our group on radiopeptides containing positively charged aminoacids, we developed a new cyclic cRGDfK derivative, c(RGDfK)-(Orn)3-CGG. This new peptide availing the polar linker (Orn)3 and the 99mTc-chelating moiety CGG (Cys-Gly-Gly) is appropriately designed for 99mTc-labeling, as well as consequent conjugation onto nanoparticles. Methods: A tumor imaging agent, c(RGDfK)-(Orn)3-[CGG-99mTc], is evaluated with regard to its radiochemical, radiobiological and imaging characteristics. Results: The complex c(RGDfK)-(Orn)3-[CGG-99mTc] was obtained in high radiochemical yield (> 98%) and was stable in vitro and ex vivo. It presented identical to the respective, fully analytically characterized 185/187Re complex retention time in RP-HPLC. In contrary to other RGD derivatives, we showed that the new radiopeptide exhibits kidney uptake and urine excretion due to the ornithine linker. High tumor uptake (3.87 ± 0.48% ID/g at 60 min p.i.) was observed and was maintained relatively high even at 24 h p.i. (1.83 ± 0.05 % ID/g), thus providing well-defined scintigraphic imaging. Accumulation in other organs was negligible. Blocking experiments indicated target specificity for integrin receptors in U87MG glioblastoma cells. Conclusion: Due to its relatively high tumor uptake, renal elimination and negligible abdominal localization, the new 99mTc-RGD peptide is considered promising in the field of imaging ανβ3-positive tumors. However, the preparation of multifunctional SPECT/MRI contrast agents (RGD-conjugated nanoparticles) for dual modality imaging of integrin expressing tumors should be further investigated

  17. Electrochemical sandwich immunoassay for the peptide hormone prolactin using an electrode modified with graphene, single walled carbon nanotubes and antibody-coated gold nanoparticles

    International Nuclear Information System (INIS)

    We describe a new kind of electrochemical immunoassay for the peptide hormone prolactin. A glassy carbon electrode (GCE) was modified with a hybrid material consisting of graphene, single walled carbon nanotubes and gold nanoparticles (AuNPs) in a chitosan (CS) matrix. The graphene and the single wall carbon nanotubes were first placed on the GCE, and the AuNPs were then electrodeposited on the surface by cyclic voltammetry. This structure results in a comparably large surface for immobilization of the capturing antibody (Ab1). The modified electrode was used in a standard sandwich-type of immunoassay. The secondary antibody (Ab2) consisted of AuNPs with immobilized Ab2 and modified with biotinylated DNA as signal tags. Finally, alkaline phosphatase was bound to the biotinylated DNA-AuNPs-Ab2 conjugate via streptavidin chemistry. The enzyme catalyzes the hydrolysis of the α-naphthyl phosphate to form α-naphthol which is highly electroactive at an operating voltage as low as 180 mV (vs. Ag/AgCl). The resulting immunoassay exhibits high sensitivity, wide linear range (50 to 3200 pg∙mL-1), low detection limit (47 pg∙mL-1), acceptable selectivity and reproducibility. The assay provides a pragmatic platform for signal amplification and has a great potential for the sensitive determination of antigens other than prolactine. (author)

  18. Uranium adsorption by non-treated and chemically modified cactus fibres in aqueous solutions

    International Nuclear Information System (INIS)

    The adsorption efficiency of Opuntia ficus indica fibres regarding the removal of hexavalent uranium [U(VI)] from aqueous solutions has been investigated prior and after the chemical treatment (e.g. phosphorylation and MnO2-coating) of the biomass. The separation/removal efficiency has been studied as a function of pH, uranium concentration, adsorbent mass, ionic strength, temperature and contact time. Evaluation of the experimental data shows that biosorption is strongly pH-depended and that the MnO2-coated product presents the highest adsorption capacity followed by the phosphorylated and non-treated material. Experiments with varying ionic strength/salinity don't show any significant effect on the adsorption efficiency, indicating the formation of inner-sphere surface complexes. The adsorption reactions are in all cases exothermic and relatively fast, particularly regarding the adsorption on the MnO2-coated product. The results of the present study indicate that adsorption of uranium from waters is very effective by cactus fibres and particularly the modified treated fibres. The increased adsorption efficiency of the cactus fibres is attributed to their primary and secondary fibrillar structure, which result in a relative relative high specific surface available for sorption. (author)

  19. Progress in chemical treatment of LEU targets by the modified Cintichem process

    International Nuclear Information System (INIS)

    Presented here are recent experimental results on tests of a modified Cintichem process for producing 99Mo from low enriched uranium (LEU). Studies were focused in three areas: (1) testing the effects on 99Mo recovery and purity of dissolving LEU foil in nitric acid alone, rather than in the sulfuric/nitric acid mixture currently used, (2) measuring decontamination factors for radionuclide impurities in each purification step, and (3) testing the effects on processing of adding barrier materials to the LEU metal-foil target. The experimental results show that switching from dissolving the target in the sulfuric/nitric mixture to using nitric acid alone should cause no significant difference in 99Mo product yield or purity. Further, the results show that overall decontamination factors for gamma emitters in the LEU target processing are high enough to meet the purity requirements for the 99Mo product. The results also show that the selected barrier materials, Cu, Fe, and Ni, do not interfere with 99Mo recovery and can be removed during chemical processing of the LEU target. (author)

  20. High carrier mobility in chemically modified graphene on an atomically flat high-resistive substrate

    International Nuclear Information System (INIS)

    Special high-resistive substrates for graphene sheets are suggested with the aim of providing high conductivity and mobility of charge carriers in graphene. The substrates were created from N-methylpyrrolidone-intercalated few-layer graphene (FLG) using anneals given to FLG samples in the temperature range 100–180 °C. Structures containing a highly conductive single-layer graphene on an atomically flat, high-resistive substrate were produced by recovering the top-layer conductivity. The obtained structures have potential in electronic applications due to a high carrier mobility (up to 16 000–42 000 cm2 V−1 s−1) and strong gate-voltage-induced modulation (by 4–5 orders of magnitude) of the current in the top graphene layer. The strong gate-voltage-induced modulation of the current clearly demonstrated that the top layer was chemically modified graphene. The possibility of governing the surface conductivity in the described structures offers a unique tool for two-dimensional nanodesign. (paper)

  1. Removal of Cu(II) from aqueous solutions using chemically modified chitosan

    International Nuclear Information System (INIS)

    Chemically modified chitosan namely epichlorohydrin cross-linked xanthate chitosan (ECXCs) has been used for the removal of Cu(II) ions from aqueous medium. The influence of various operating parameters such as pH, temperature, sorbent dosage, initial concentration of Cu(II) ions and contact time on the adsorption capacity of ECXCs has been investigated. Thermodynamic parameters namely ΔGo, ΔHo and ΔSo of the Cu(II) adsorption process have been calculated. Differential anodic stripping voltammetric technique was used to determine the concentration of Cu(II) in the test solution before and after adsorption. The nature of the possible adsorbent-metal ion interactions was studied by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The studies showed that the adsorption of Cu(II) on ECXCs strongly depends on pH and temperature. The maximum adsorption capacity was observed at pH 5.0 and the adsorption capacity of ECXCs increased with increasing temperature indicating the endothermic nature of adsorption process. Langmuir and Freundlich adsorption equations were used to fit the experimental data. The adsorption process is found to follow the pseudo-second-order kinetic model. The maximum adsorption capacity was found to be 43.47 mg g-1 from the Langmuir isotherm model at 50 deg. C. During desorption studies 97-100% of adsorbed copper ion is released into solution in presence of 1N EDTA, HCl and H2SO4.

  2. A novel chemically modified curcumin reduces severity of experimental periodontal disease in rats: initial observations.

    Science.gov (United States)

    Elburki, Muna S; Rossa, Carlos; Guimaraes, Morgana R; Goodenough, Mark; Lee, Hsi-Ming; Curylofo, Fabiana A; Zhang, Yu; Johnson, Francis; Golub, Lorne M

    2014-01-01

    Tetracycline-based matrix metalloproteinase- (MMP-) inhibitors are currently approved for two inflammatory diseases, periodontitis and rosacea. The current study addresses the therapeutic potential of a novel pleiotropic MMP-inhibitor not based on an antibiotic. To induce experimental periodontitis, endotoxin (LPS) was repeatedly injected into the gingiva of rats on one side of the maxilla; the contralateral (control) side received saline injections. Two groups of rats were treated by daily oral intubation with a chemically modified curcumin, CMC 2.24, for two weeks; the control groups received vehicle alone. After sacrifice, gingiva, blood, and maxilla were collected, the jaws were defleshed, and periodontal (alveolar) bone loss was quantified morphometrically and by μ-CT scan. The gingivae were pooled per experimental group, extracted, and analyzed for MMPs (gelatin zymography; western blot) and for cytokines (e.g., IL-1β; ELISA); serum and plasma samples were analyzed for cytokines and MMP-8. The LPS-induced pathologically excessive bone loss was reduced to normal levels based on either morphometric (P = 0.003) or μ-CT (P = 0.008) analysis. A similar response was seen for MMPs and cytokines in the gingiva and blood. This initial study, on a novel triketonic zinc-binding CMC, indicates potential efficacy on inflammatory mediators and alveolar bone loss in experimental periodontitis and warrants future therapeutic and pharmacokinetic investigations. PMID:25104884

  3. Chemically modified graphene films for high-performance optical NO2 sensors.

    Science.gov (United States)

    Xing, Fei; Zhang, Shan; Yang, Yong; Jiang, Wenshuai; Liu, Zhibo; Zhu, Siwei; Yuan, Xiaocong

    2016-08-01

    Various graphene-based gas sensors that operate based on the electrical properties of graphene have been developed for accurate detection of gas components. However, electronic graphene-based gas sensors are unsafe under explosive atmospheres and sensitive to electromagnetic interference. Here, a novel optical graphene-based gas sensor for NO2 detection is established based on surface chemical modification of high-temperature-reduced graphene oxide (h-rGO) films with sulfo groups. Sulfo group-modified h-rGO (S-h-rGO) films with a thickness of several nanometers exhibit excellent performance in NO2 detection at room temperature and atmospheric pressure based on the polarization absorption effect of graphene. Initial slope analysis of the S-h-rGO sensor indicates that it has a limit of detection of 0.28 ppm and a response time of 300 s for NO2 gas sensing. Furthermore, the S-h-rGO sensor also possesses the advantages of good linearity, reversibility, selectivity, non-contact operation, low cost and safety. This novel optical gas sensor has the potential to serve as a general platform for the selective detection of a variety of gases with high performance. PMID:27265308

  4. Structural and dynamical properties of water on chemically modified surfaces: The role of the instantaneous surface

    Science.gov (United States)

    Bekele, Selemon; Tsige, Mesfin

    Surfaces of polymers such as atactic polystyrene (aPS) represent very good model systems for amorphous material surfaces. Such polymer surfaces are usually modified either chemically or physically for a wide range of applications that include friction, lubrication and adhesion. It is thus quite important to understand the structural and dynamical properties of liquids that come in contact with them to achieve the desired functional properties. Using molecular dynamics (MD) simulations, we investigate the structural and dynamical properties of water molecules in a slab of water in contact with atactic polystyrene surfaces of varying polarity. We find that the density of water molecules and the number distribution of hydrogen bonds as a function of distance relative to an instantaneous surface exhibit a structure indicative of a layering of water molecules near the water/PS interface. For the dynamics, we use time correlation functions of hydrogen bonds and the incoherent structure function for the water molecules. Our results indicate that the polarity of the surface dramatically affects the dynamics of the interfacial water molecules with the dynamics slowing down with increasing polarity. This work was supported by NSF Grant DMR1410290.

  5. A Novel Chemically Modified Curcumin Reduces Severity of Experimental Periodontal Disease in Rats: Initial Observations

    Directory of Open Access Journals (Sweden)

    Muna S. Elburki

    2014-01-01

    Full Text Available Tetracycline-based matrix metalloproteinase- (MMP- inhibitors are currently approved for two inflammatory diseases, periodontitis and rosacea. The current study addresses the therapeutic potential of a novel pleiotropic MMP-inhibitor not based on an antibiotic. To induce experimental periodontitis, endotoxin (LPS was repeatedly injected into the gingiva of rats on one side of the maxilla; the contralateral (control side received saline injections. Two groups of rats were treated by daily oral intubation with a chemically modified curcumin, CMC 2.24, for two weeks; the control groups received vehicle alone. After sacrifice, gingiva, blood, and maxilla were collected, the jaws were defleshed, and periodontal (alveolar bone loss was quantified morphometrically and by μ-CT scan. The gingivae were pooled per experimental group, extracted, and analyzed for MMPs (gelatin zymography; western blot and for cytokines (e.g., IL-1β; ELISA; serum and plasma samples were analyzed for cytokines and MMP-8. The LPS-induced pathologically excessive bone loss was reduced to normal levels based on either morphometric (P=0.003 or μ-CT (P=0.008 analysis. A similar response was seen for MMPs and cytokines in the gingiva and blood. This initial study, on a novel triketonic zinc-binding CMC, indicates potential efficacy on inflammatory mediators and alveolar bone loss in experimental periodontitis and warrants future therapeutic and pharmacokinetic investigations.

  6. Adhesion-dependent negative friction coefficient on chemically modified graphite at the nanoscale

    Science.gov (United States)

    Deng, Zhao; Smolyanitsky, Alex; Li, Qunyang; Feng, Xi-Qiao; Cannara, Rachel J.

    2012-12-01

    From the early tribological studies of Leonardo da Vinci to Amontons’ law, friction has been shown to increase with increasing normal load. This trend continues to hold at the nanoscale, where friction can vary nonlinearly with normal load. Here we present nanoscale friction force microscopy (FFM) experiments for a nanoscale probe tip sliding on a chemically modified graphite surface in an atomic force microscope (AFM). Our results demonstrate that, when adhesion between the AFM tip and surface is enhanced relative to the exfoliation energy of graphite, friction can increase as the load decreases under tip retraction. This leads to the emergence of an effectively negative coefficient of friction in the low-load regime. We show that the magnitude of this coefficient depends on the ratio of tip-sample adhesion to the exfoliation energy of graphite. Through both atomistic- and continuum-based simulations, we attribute this unusual phenomenon to a reversible partial delamination of the topmost atomic layers, which then mimic few- to single-layer graphene. Lifting of these layers with the AFM tip leads to greater deformability of the surface with decreasing applied load. This discovery suggests that the lamellar nature of graphite yields nanoscale tribological properties outside the predictive capacity of existing continuum mechanical models.

  7. A highly stable and sensitive chemically modified screen-printed electrode for sulfide analysis

    International Nuclear Information System (INIS)

    We report here a highly stable and sensitive chemically modified screen-printed carbon electrode (CMSPE) for sulfide analysis. The CMSPE was prepared by first ion-exchanging ferricyanide into a Tosflex anion-exchange polymer and then sealing with a tetraethyl orthosilicate sol-gel layer. The sol-gel overlayer coating was crucial to stabilize the electron mediator (i.e., Fe(China)63-) from leaching. The strong interaction between the oxy-hydroxy functional group of sol-gel and the hydrophilic sites of Tosflex makes the composite highly rigid to trap the ferricyanide mediator. An obvious electrocatalytic sulfide oxidation current signal at ∼0.20 V versus Ag/AgCl in pH 7 phosphate buffer solution was observed at the CMSPE. A linear calibration plot over a wide range of 0.1 μM to 1 mM with a slope of 5.6 nA/μM was obtained by flow injection analysis. The detection limit (S/N = 3) was 8.9 nM (i.e., 25.6 ppt). Practical utility of the system was applied to the determination of sulfide trapped from cigarette smoke and sulfide content in hot spring water

  8. Enhanced forward osmosis from chemically modified polybenzimidazole (PBI) nanofiltration hollow fiber membranes with a thin wall

    KAUST Repository

    Wang, Kai Yu

    2009-04-01

    To develop high-flux and high-rejection forward osmosis (FO) membranes for water reuses and seawater desalination, we have fabricated polybenzimidazole (PBI) nanofiltration (NF) hollow fiber membranes with a thin wall and a desired pore size via non-solvent induced phase inversion and chemically cross-linking modification. The cross-linking by p-xylylene dichloride can finely tune the mean pore size and enhance the salt selectivity. High water permeation flux and improved salt selectivity for water reuses were achieved by using the 2-h modified PBI NF membrane which has a narrow pore size distribution. Cross-linking at a longer time produces even a lower salt permeation flux potentially suitable for desalination but at the expense of permeation flux due to tightened pore sizes. It is found that draw solution concentration and membrane orientations are main factors determining the water permeation flux. In addition, effects of membrane morphology and operation conditions on water and salt transport through membrane have been investigated. © 2008 Elsevier Ltd. All rights reserved.

  9. Effects of Zn Content on Crystal Structure, Cytocompatibility, Antibacterial Activity, and Chemical Stability in Zn-Modified Calcium Silicate Coatings

    Science.gov (United States)

    Li, Kai; Yu, Jiangming; Xie, Youtao; Huang, Liping; Ye, Xiaojian; Zheng, Xuebin

    2013-08-01

    In our previous study, Zn-modified calcium silicate coatings possess not only excellent chemical stability but also well antibacterial activity. Still, effects of zinc content on these properties and cytocompatibility remain unclear. In this paper, two kinds of Zn-modified calcium silicate coatings (ZC0.3, ZC0.5) were fabricated on Ti-6Al-4V substrates via plasma spraying technology. X-ray diffraction results and transmission electron microscopy observations showed that the ZC0.5 coating was composed of pure hardystonite (Ca2ZnSi2O7) phase, while, besides Ca2ZnSi2O7 phase, the amorphous CaSiO3 phase was also detected in the ZC0.3 coating. Chemical stability in Tris-HCl buffer solution and antibacterial activity of the Zn-modified calcium silicate coatings increased with an increase in zinc content. In vitro cytocompatibility evaluation demonstrated that the proliferation and alkaline phosphatase activity and collagen type I (COLI) secretion of osteoblast-like MC3T3-E1 cells on Zn-modified coatings were significantly enhanced compared to the Zn-free coating and Ti-6Al-4V control, and no cytotoxicity appeared on Zn-modified coatings. The better antibacterial activity and the enhanced capability to promote MC3T3-E1 cells differentiation of Zn-modified coatings should be attributed to the slow and constant Zn2+ releasing from the coatings.

  10. Enhanced compatibility of chemically modified titanium surface with periodontal ligament cells

    Energy Technology Data Exchange (ETDEWEB)

    Kado, T.; Hidaka, T. [Division of Periodontology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Aita, H. [Division of Occlusion and Removable Prosthodontics, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Endo, K. [Division of Biomaterials and Bioengineering, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Furuichi, Y., E-mail: furuichi@hoku-iryo-u.ac.jp [Division of Periodontology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Cell-adhesive molecules were covalently immobilized on a Ti surface. Black-Right-Pointing-Pointer Immobilized cell-adhesive molecules maintained native function on the Ti surface. Black-Right-Pointing-Pointer Immobilized collagen enhanced adhesion of periodontal ligament cells to the Ti. - Abstract: A simple chemical modification method was developed to immobilize cell-adhesive molecules on a titanium surface to improve its compatibility with human periodontal ligament cells (HPDLCs).The polished titanium disk was immersed in 1% (v/v) p-vinylbenzoic acid solution for 2 h to introduce carboxyl groups onto the surface. After rinsing with distilled deionized water, the titanium disk was dipped into 1.47% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide solution containing 0.1 mg/ml Gly-Arg-Gly-Asp-Ser (GRGDS), human plasma fibronectin (pFN), or type I collagen from calf skin (Col) to covalently immobilize the cell-adhesive molecules on the titanium surface via formation of peptide bonds. X-ray photoelectron spectroscopy analyses revealed that cell-adhesive molecules were successfully immobilized on the titanium surfaces. The Col-immobilized titanium surface revealed higher values regarding nano rough characteristics than the as-polished titanium surface under scanning probe microscopy. The number of HPDLCs attached to both the pFN- and Col-immobilized titanium surfaces was twice that attached to the as-polished titanium surfaces. The cells were larger with the cellular processes that stretched to a greater extent on the pFN- and Col-immobilized titanium surfaces than on the as-polished titanium surface (p < 0.05). HPDLCs on the Col-immobilized titanium surfaces showed more extensive expression of vinculin at the tips of cell projections and more contiguously along the cell outline than on the as-polished, GRGDS-immobilized and pFN-immobilized titanium surfaces. It was concluded that cell-adhesive molecules successfully

  11. Enhanced compatibility of chemically modified titanium surface with periodontal ligament cells

    International Nuclear Information System (INIS)

    Highlights: ► Cell-adhesive molecules were covalently immobilized on a Ti surface. ► Immobilized cell-adhesive molecules maintained native function on the Ti surface. ► Immobilized collagen enhanced adhesion of periodontal ligament cells to the Ti. - Abstract: A simple chemical modification method was developed to immobilize cell-adhesive molecules on a titanium surface to improve its compatibility with human periodontal ligament cells (HPDLCs).The polished titanium disk was immersed in 1% (v/v) p-vinylbenzoic acid solution for 2 h to introduce carboxyl groups onto the surface. After rinsing with distilled deionized water, the titanium disk was dipped into 1.47% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide solution containing 0.1 mg/ml Gly-Arg-Gly-Asp-Ser (GRGDS), human plasma fibronectin (pFN), or type I collagen from calf skin (Col) to covalently immobilize the cell-adhesive molecules on the titanium surface via formation of peptide bonds. X-ray photoelectron spectroscopy analyses revealed that cell-adhesive molecules were successfully immobilized on the titanium surfaces. The Col-immobilized titanium surface revealed higher values regarding nano rough characteristics than the as-polished titanium surface under scanning probe microscopy. The number of HPDLCs attached to both the pFN- and Col-immobilized titanium surfaces was twice that attached to the as-polished titanium surfaces. The cells were larger with the cellular processes that stretched to a greater extent on the pFN- and Col-immobilized titanium surfaces than on the as-polished titanium surface (p < 0.05). HPDLCs on the Col-immobilized titanium surfaces showed more extensive expression of vinculin at the tips of cell projections and more contiguously along the cell outline than on the as-polished, GRGDS-immobilized and pFN-immobilized titanium surfaces. It was concluded that cell-adhesive molecules successfully immobilized on the titanium surface and improved the compatibility of the surface

  12. Surfactants as bubble surface modifiers in the flotation of algae: dissolved air flotation that utilizes a chemically modified bubble surface.

    Science.gov (United States)

    Henderson, Rita K; Parsons, Simon A; Jefferson, Bruce

    2008-07-01

    In this paper we present an investigation into the use of bubbles modified with surfactants in dissolved air flotation (DAF). Bubble modification was investigated by dosing surfactants of varying character into the saturator of a DAF unit in turn. The cell removal efficiency only improved when using a cationic surfactant where optimum removal of Microcystis aeruginosa cells was obtained when using 0.0022-0.004 mequiv L(-1) surfactant. However, the magnitude of the removal differed according to the hydrophobicity of the surfactant. Typically, the more efficiently the surfactant adsorbed at the bubble interface, the better the removal efficiency. When the dose to saturator ratio was kept constant and the recycle ratio varied, the removal efficiency improved with increasing recycle ratio, reaching a maximum removal efficiency of 87% for M. aeruginosa. This value was comparable with that predicted by a theoretical model. The bubble collection efficiency of a maximum of two cells per bubble was constant irrespective of the influent cell number or recycle ratio. Treatment of additional species in this way revealed a relationship between increasing size and both increasing removal efficiency and decreasing surfactant dose, which is supported by theoretical relationships. PMID:18678021

  13. Direct determination of cadmium in Orujo spirit samples by electrothermal atomic absorption spectrometry: Comparative study of different chemical modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Vilar Farinas, M. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain); Barciela Garcia, J. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain); Garcia Martin, S. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain); Pena Crecente, R. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain); Herrero Latorre, C. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain)]. E-mail: cherrero@lugo.usc.es

    2007-05-22

    In this work, several analytical methods are proposed for cadmium determination in Orujo spirit samples using electrothermal atomic absorption spectrometry (ETAAS). Permanent chemical modifiers thermally coated on the platforms inserted in pyrolytic graphite tubes (such as W, Ir, Ru, W-Ir and W-Ru) were comparatively studied in relation to common chemical modifier mixtures [Pd-Mg(NO{sub 3}){sub 2} and (NH{sub 4})H{sub 2}PO{sub 4}-Mg(NO{sub 3}){sub 2}] for cadmium stabilization. Different ETAAS Cd determination methods based on the indicated modifiers have been developed. In each case, pyrolysis and atomization temperatures, atomization shapes, characteristic masses and detection limits as well as other analytical characteristics have been determined. All the assayed modifiers (permanent and conventional) were capable of achieving the appropriate stabilization of the analyte, with the exception of Ru and W-Ru. Moreover, for all developed methods, recoveries (99-102%) and precision (R.S.D. lower than 10%) were acceptable. Taking into account the analytical performance (best detection limit LOD = 0.01 {mu}g L{sup -1}), the ETAAS method based on the use of W as a permanent modifier was selected for further direct Cd determinations in Orujo samples from Galicia (NW Spain). The chosen method was applied in the determination of the Cd content in 38 representative Galician samples. The cadmium concentrations ranged

  14. Direct determination of cadmium in Orujo spirit samples by electrothermal atomic absorption spectrometry: Comparative study of different chemical modifiers

    International Nuclear Information System (INIS)

    In this work, several analytical methods are proposed for cadmium determination in Orujo spirit samples using electrothermal atomic absorption spectrometry (ETAAS). Permanent chemical modifiers thermally coated on the platforms inserted in pyrolytic graphite tubes (such as W, Ir, Ru, W-Ir and W-Ru) were comparatively studied in relation to common chemical modifier mixtures [Pd-Mg(NO3)2 and (NH4)H2PO4-Mg(NO3)2] for cadmium stabilization. Different ETAAS Cd determination methods based on the indicated modifiers have been developed. In each case, pyrolysis and atomization temperatures, atomization shapes, characteristic masses and detection limits as well as other analytical characteristics have been determined. All the assayed modifiers (permanent and conventional) were capable of achieving the appropriate stabilization of the analyte, with the exception of Ru and W-Ru. Moreover, for all developed methods, recoveries (99-102%) and precision (R.S.D. lower than 10%) were acceptable. Taking into account the analytical performance (best detection limit LOD = 0.01 μg L-1), the ETAAS method based on the use of W as a permanent modifier was selected for further direct Cd determinations in Orujo samples from Galicia (NW Spain). The chosen method was applied in the determination of the Cd content in 38 representative Galician samples. The cadmium concentrations ranged -1

  15. Synthetic surfactant containing SP-B and SP-C mimics is superior to single-peptide formulations in rabbits with chemical acute lung injury.

    Science.gov (United States)

    Walther, Frans J; Hernández-Juviel, José M; Gordon, Larry M; Waring, Alan J

    2014-01-01

    Background. Chemical spills are on the rise and inhalation of toxic chemicals may induce chemical acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Although the pathophysiology of ALI/ARDS is well understood, the absence of specific antidotes has limited the effectiveness of therapeutic interventions. Objectives. Surfactant inactivation and formation of free radicals are important pathways in (chemical) ALI. We tested the potential of lipid mixtures with advanced surfactant protein B and C (SP-B and C) mimics to improve oxygenation and lung compliance in rabbits with lavage- and chemical-induced ALI/ARDS. Methods. Ventilated young adult rabbits underwent repeated saline lung lavages or underwent intratracheal instillation of hydrochloric acid to induce ALI/ARDS. After establishment of respiratory failure rabbits were treated with a single intratracheal dose of 100 mg/kg of synthetic surfactant composed of 3% Super Mini-B (S-MB), a SP-B mimic, and/or SP-C33 UCLA, a SP-C mimic, in a lipid mixture (DPPC:POPC:POPG 5:3:2 by weight), the clinical surfactant Infasurf(®), a bovine lung lavage extract with SP-B and C, or synthetic lipids alone. End-points consisted of arterial oxygenation, dynamic lung compliance, and protein and lipid content in bronchoalveolar lavage fluid. Potential mechanism of surfactant action for S-MB and SP-C33 UCLA were investigated with captive bubble surfactometry (CBS) assays. Results. All three surfactant peptide/lipid mixtures and Infasurf equally lowered the minimum surface tension on CBS, and also improved oxygenation and lung compliance. In both animal models, the two-peptide synthetic surfactant with S-MB and SP-C33 UCLA led to better arterial oxygenation and lung compliance than single peptide synthetic surfactants and Infasurf. Synthetic surfactants and Infasurf improved lung function further in lavage- than in chemical-induced respiratory failure, with the difference probably due to greater capillary-alveolar protein

  16. Synthetic surfactant containing SP-B and SP-C mimics is superior to single-peptide formulations in rabbits with chemical acute lung injury

    Directory of Open Access Journals (Sweden)

    Frans J. Walther

    2014-05-01

    Full Text Available Background. Chemical spills are on the rise and inhalation of toxic chemicals may induce chemical acute lung injury (ALI/acute respiratory distress syndrome (ARDS. Although the pathophysiology of ALI/ARDS is well understood, the absence of specific antidotes has limited the effectiveness of therapeutic interventions. Objectives. Surfactant inactivation and formation of free radicals are important pathways in (chemical ALI. We tested the potential of lipid mixtures with advanced surfactant protein B and C (SP-B and C mimics to improve oxygenation and lung compliance in rabbits with lavage- and chemical-induced ALI/ARDS. Methods. Ventilated young adult rabbits underwent repeated saline lung lavages or underwent intratracheal instillation of hydrochloric acid to induce ALI/ARDS. After establishment of respiratory failure rabbits were treated with a single intratracheal dose of 100 mg/kg of synthetic surfactant composed of 3% Super Mini-B (S-MB, a SP-B mimic, and/or SP-C33 UCLA, a SP-C mimic, in a lipid mixture (DPPC:POPC:POPG 5:3:2 by weight, the clinical surfactant Infasurf®, a bovine lung lavage extract with SP-B and C, or synthetic lipids alone. End-points consisted of arterial oxygenation, dynamic lung compliance, and protein and lipid content in bronchoalveolar lavage fluid. Potential mechanism of surfactant action for S-MB and SP-C33 UCLA were investigated with captive bubble surfactometry (CBS assays. Results. All three surfactant peptide/lipid mixtures and Infasurf equally lowered the minimum surface tension on CBS, and also improved oxygenation and lung compliance. In both animal models, the two-peptide synthetic surfactant with S-MB and SP-C33 UCLA led to better arterial oxygenation and lung compliance than single peptide synthetic surfactants and Infasurf. Synthetic surfactants and Infasurf improved lung function further in lavage- than in chemical-induced respiratory failure, with the difference probably due to greater capillary

  17. Effective gene delivery into human stem cells with a cell-targeting Peptide-modified bioreducible polymer.

    Science.gov (United States)

    Beloor, Jagadish; Ramakrishna, Suresh; Nam, Kihoon; Seon Choi, Chang; Kim, Jongkil; Kim, Sung Hwa; Cho, Hyong Jin; Shin, HeungSoo; Kim, Hyongbum; Kim, Sung Wan; Lee, Sang-Kyung; Kumar, Priti

    2015-05-01

    Stem cells are poorly permissive to non-viral gene transfection reagents. In this study, we explored the possibility of improving gene delivery into human embryonic (hESC) and mesenchymal (hMSC) stem cells by synergizing the activity of a cell-binding ligand with a polymer that releases nucleic acids in a cytoplasm-responsive manner. A 29 amino acid long peptide, RVG, targeting the nicotinic acetylcholine receptor (nAchR) was identified to bind both hMSC and H9-derived hESC. Conjugating RVG to a redox-sensitive biodegradable dendrimer-type arginine-grafted polymer (PAM-ABP) enabled nanoparticle formation with plasmid DNA without altering the environment-sensitive DNA release property and favorable toxicity profile of the parent polymer. Importantly, RVG-PAM-ABP quantitatively enhanced transfection into both hMSC and hESC compared to commercial transfection reagents like Lipofectamine 2000 and Fugene. ∼60% and 50% of hMSC and hESC were respectively transfected, and at increased levels on a per cell basis, without affecting pluripotency marker expression. RVG-PAM-ABP is thus a novel bioreducible, biocompatible, non-toxic, synthetic gene delivery system for nAchR-expressing stem cells. Our data also demonstrates that a cell-binding ligand like RVG can cooperate with a gene delivery system like PAM-ABP to enable transfection of poorly-permissive cells. PMID:25515928

  18. Physico-Chemical Properties of Rice Starch Modified by Hydrothermal Treatments

    Science.gov (United States)

    Rice starches of long grain and waxy cultivars were annealed (ANN) in excess water at 50 oC for 4 hours. They were also modified under heat-moisture treatment (MHT) conditions at 110 oC, and various moisture contents (20%, 30%, and 40%) for 8 hours. The modified products were analyzed by Rapid-Vis...

  19. Utilization of chemically modified citrus reticulata peels for biosorptive removal of acid yellow-73 dye from water

    International Nuclear Information System (INIS)

    Textile effluents contain several varieties of natural and synthetic dyes, which are non-biodegradable. Acid Yellow-73 is one of them. In this research work, adsorptive removal of this dye was investigated using chemically modified Citrus reticulata peels, in batch mode. It was noted that adsorption of dye on Citrus reticulata peels increased by increasing contact time and decreased in basic pH conditions. Langmuir and Freundlich isothermal models were followed by equilibrium data, but the first isotherm fitted the data better, showing that chemisorption occurred more as compared to physiosorption, showing maximum adsorption capacity 96.46 mg.g-1.L-1. The thermodynamic study showed that adsorption of Acid Yellow-73 on chemically modified Citrus reticulata peels was favorable in nature, following pseudo-second order kinetics. (author)

  20. Lasso peptide, a highly stable structure and designable multifunctional backbone.

    Science.gov (United States)

    Zhao, Ning; Pan, Yongxu; Cheng, Zhen; Liu, Hongguang

    2016-06-01

    Lasso peptide belongs to a new class of natural product with highly compact and stable structure. It has varieties of biological activities, among which the most important one is its antibacterial efficacy. Novel lasso peptides have been constantly discovered and analyzed by advanced techniques, and the biosynthesis or even chemical synthesis of lasso peptide has been studied after learning its constituent amino acids and maturation process. Structural identification of lasso peptide provides information for elucidating the mechanisms of its antibacterial activity and basis for further modifications. Ring of lasso peptide is the key to both its highly compact and stable structure and its intrinsic antibacterial property. The loop has been considered as suitable modification region of lasso peptide, such as V11-S18 of MccJ25 being modifiable without disrupting the lasso structure in biosynthesis. The tail is the immunity protein that can export lasso peptide out of its produced strain and serve as a self-protection mechanism at the same time. Most of currently known lasso peptides are non-pathogenic, which implies that the modified lasso peptides are promising candidates for medical applications. Arginine, glycine, and aspartic acid as a ligands of cancer-specific receptor have been grafted to the loop of lasso peptide without losing its bioactivity, and many other targets are expected to be used for lasso peptide modification. Multi-molecular modification and large-scale production need to be studied and solved in future for designing and using multifunctional lasso peptide based on its extraordinary stable structure. PMID:27074719

  1. Applicability of Vacuum Impregnation to Modify Physico-Chemical, Sensory and Nutritive Characteristics of Plant Origin Products—A Review

    OpenAIRE

    Elżbieta Radziejewska-Kubzdela; Róża Biegańska-Marecik; Marcin Kidoń

    2014-01-01

    Vacuum impregnation is a non-destructive method of introducing a solution with a specific composition to the porous matrices of fruit and vegetables. Mass transfer in this process is a result of mechanically induced differences in pressure. Vacuum impregnation makes it possible to fill large volumes of intercellular spaces in tissues of fruit and vegetables, thus modifying physico-chemical properties and sensory attributes of products. This method may be used, e.g., to reduce pH and water act...

  2. Impact of chemically-modified tetracycline 3 on intertwined physiological, biochemical, and inflammatory networks in porcine sepsis/ARDS

    OpenAIRE

    Sadowsky, David; Nieman, Gary; Barclay, Derek; Mi, Qi; Zamora, Ruben; Constantine, Gregory; Golub, Lorne; Lee, Hsi-Ming; Roy, Shreyas; Gatto, Louis A; Vodovotz, Yoram

    2015-01-01

    Sepsis can lead to multiple organ dysfunction, including the Acute Respiratory Distress Syndrome (ARDS), due to intertwined, dynamic changes in inflammation and organ physiology. We have demonstrated the efficacy of Chemically-Modified Tetracycline 3 (CMT-3) at reducing inflammation and ameliorating pathophysiology in the setting of a clinically realistic porcine model of ARDS. Here, we sought to gain insights into the derangements that characterize sepsis/ARDS and the possible impact of CMT-...

  3. Physicochemical properties, morphological and X-ray pattern of chemically modified white sorghum starch. (Bicolor-Moench)

    OpenAIRE

    Olayinka, O. O.; Adebowale, K. O.; Olu-Owolabi, I. B.

    2011-01-01

    Starch isolated from white sorghum was subjected to chemical modifications like oxidation, acetylation and acid thinning. Proximate composition of these, such as crude protein, crude fat, moisture content and ash content were studied. Wide angle X-ray diffractograms showed typical ‘A’ pattern characteristic of cereal starches, but significant differences were observed between the X-ray pattern of native and modified starches. Scanning electron microscopy revealed round and polygonal shapes fo...

  4. Chemically modified graphite felt as an efficient cathode in electro-Fenton for p-nitrophenol degradation

    International Nuclear Information System (INIS)

    Highlights: • Chemically modified graphite felt was prepared using ethanol and hydrazine hydrate as reagents. • Carbon nanoparticles with functional groups were deposited on the surface after modification. • The electrochemical activity for ORR and H2O2 generation on the modified electrode was improved. • The cathode modification effictively improved the EF performance for pollutant degradation. - Abstract: A simple method with low-cost chemical reagents ethanol and hydrazine hydrate was used to modify graphite felt as the cathode for electro-Fenton (EF) application, using p-nitrophenol (p-Np) as the model pollutant. Characterized by scanning electron microscope, contact angle, Raman spectrum and X-ray photoelectron spectroscopy, the morphology and surface physicochemical properties after modification were observed considerably changed. After modification, some nanoparticles and oxygen and nitrogen-containing functional groups appeared on the cathode surface, which greatly improved the surface hydrophilic property and the electrocatalytic activity for oxygen reduction reaction. The effects led to the hydrogen peroxide accumulation on the modified cathode markedly increased to 175.8 mg L−1, while that on the unmodified one was only 67.5 mg L−1. p-Np of initial 50 mg L−1 could be completely removed by EF using the modified cathode, and the mineralization ratio reached 51.4%, more than 2 times of the pristine one. After 10 cycles, the mineralization ratio of the modified cathode was still above 45%, suggesting that the modification method can provide an effective approach to improve EF performance, and thus benefits to promote its environmental applications

  5. Computational Study of the Cation-Modified GSH Peptide Interactions With Perovskite-Type BFO-(111) Membranes Under Aqueous Conditions.

    Science.gov (United States)

    Bian, Liang; Dong, Fa-Qin; Song, Mian-Xin; Xu, Jin-Bao; Zhang, Xiao-Yan

    2015-12-01

    We elucidated a number of facets regarding glutathione (GSH)-bismuth ferrite (BiFeO3, BFO) interactions and reactivity that have previously remained unexplored on a molecular level. In this approach, the cation-modified reduced GSH (or oxidised glutathione (GS·)) formed on the (111)-oriented BiFeO3 membrane (namely BFO-(111)) can serve as an efficient quencher, and the luminescence mechanism is explained in aqueous conditions. Notably, we suggest the use of Fe(2+)↓ ion as an electron donor and K(+) ion as an electron acceptor to exert a "gluing" effect on the glutamic acid (Glu) and glycine (Gly) side chains, producing an exposed sulfhydryl (-SH) configuration. This method may enable the rational design of a convenient platform for biosensors. PMID:26061445

  6. Renewable resources as reinforcement of polymeric matrices: composites based on phenolic thermosets and chemically modified sisal fibers.

    Science.gov (United States)

    Megiatto, Jackson D; Oliveira, Franciéli B; Rosa, Derval S; Gardrat, Christian; Castellan, Alain; Frollini, Elisabete

    2007-09-11

    Lignocellulosic materials can significantly contribute to the development of composites, since it is possible to chemically and/or physically modify their main components, cellulose, hemicelluloses and lignin. This may result in materials more stable and with more uniform properties. It has previously been shown that chemically modified sisal fibers by ClO(2) oxidation and reaction with FA and PFA presented a thin coating layer of PFA on their surface. FA and PFA were chosen as reagents because these alcohols can be obtained from renewable sources. In the present work, the effects of the polymeric coating layer as coupling agent in phenolic/sisal fibers composites were studied. For a more detailed characterization of the fibers, IGC was used to evaluate the changes that occurred at the sisal fibers surface after the chemical modifications. The dispersive and acid-base properties of untreated and treated sisal fibers surfaces were determined. Biodegradation experiments were also carried out. In a complementary study, another PFA modification was made on sisal fibers, using K2Cr2O(7) as oxidizing agent. In this case the oxidation effects involve mainly the cellulose polymer instead of lignin, as observed when the oxidation was carried out with ClO(2). The SEM images showed that the oxidation of sisal fibers followed by reaction with FA or PFA favored the fiber/phenolic matrix interaction at the interface. However, because the fibers were partially degraded by the chemical treatment, the impact strength of the sisal-reinforced composites decreased. By contrast, the chemical modification of fibers led to an increase of the water diffusion coefficient and to a decrease of the water absorption of the composites reinforced with modified fibers. The latter property is very important for certain applications, such as in the automotive industry. PMID:17676656

  7. Sulfur Fixation by Chemically Modified Red Mud Samples Containing Inorganic Additives: A Parametric Study

    OpenAIRE

    Liu, Yang; LI Yang; Zhou, Feng-shan; Hu, Ying-mo; Zhang, Yi-he

    2016-01-01

    Sulfur retention ability of Bayer red mud from alumina plant was investigated. Bayer red mud modified by fusel salt and waste mother liquor of sodium ferrocyanide as the main sulfur fixation agent and the calcium based natural mineral materials as servicing additives; the experimental results showed the following: (1) Through 10 wt% waste mother liquor of sodium ferrocyanide modifying Bayer red mud, sulfur fixation rate can increase by 13 wt%. (2) Magnesium oxide can obviously improve the sul...

  8. Effects of increasing hydrophobicity on the physical-chemical and biological properties of a class A amphipathic helical peptide.

    Science.gov (United States)

    Datta, G; Chaddha, M; Hama, S; Navab, M; Fogelman, A M; Garber, D W; Mishra, V K; Epand, R M; Epand, R F; Lund-Katz, S; Phillips, M C; Segrest, J P; Anantharamaiah, G M

    2001-07-01

    We have recently shown that a class A amphipathic peptide 5F with increased amphipathicity protected mice from diet-induced atherosclerosis (Garber et al. J. Lipid Res. 2001. 42: 545-552). We have now examined the effects of increasing the hydrophobicity of a series of homologous class A amphipathic peptides, including 5F, on physical and functional properties related to atherosclerosis inhibition by systematically replacing existing nonpolar amino acids with phenylalanine. The peptides, based on the sequence Ac-D-W-L-K-A-F-Y-D-K-V-A-E-K-L-K-E-A-F-NH(2) (Ac-18A-NH(2) or 2F) were: 3F(3)(Ac-F(3)18A-NH(2)), 3F(14)(Ac-F(14)18A-NH(2)), 4F(Ac-F(3,14)18A-NH(2)), 5F(Ac-F(11,14,17) 18A-NH(2)), 6F(Ac-F(10,11,14,17)18A-NH(2)), and 7F(Ac-F(3,10,11,14,17) 18A-NH(2)). Measurements of aqueous solubility, HPLC retention time, exclusion pressure for penetration into an egg phosphatidylcholine (EPC) monolayer, and rates of EPC solubilization revealed an abrupt increase in the hydrophobicity between peptides 4F and 5F; this was accompanied by increased ability to associate with phospholipids. The peptides 6F and 7F were less effective, indicating a limit to increased hydrophobicity for promoting lipid interaction in these peptides. Despite this marked increase in lipid affinity, these peptides were less effective than apoA-I in activating the plasma enzyme, lecithin:cholesterol acyltransferase, with 5F activating LCAT the best (80% of apoA-I). Peptides 4F, 5F, and 6F were equally potent in inhibiting LDL-induced monocyte chemotactic activity. These studies suggest that an appropriate balance between peptide-peptide and peptide-lipid interactions is required for optimal biological activity of amphipathic peptides. These studies provide a rationale for the design of small apoA-I-mimetics with increased potency for atherosclerosis inhibition. PMID:11441137

  9. Cyclic RGD peptide-modified liposomal drug delivery system: enhanced cellular uptake in vitro and improved pharmacokinetics in rats

    Directory of Open Access Journals (Sweden)

    Chen Z

    2012-07-01

    Full Text Available Zhongya Chen,1,2 Jiaxin Deng,1,2 Yan Zhao,1,2 Tao Tao1,21National Pharmaceutical Engineering Research Center, 2Shanghai Institute of Pharmaceutical Industry, China State Institute of Pharmaceutical Industry, Shanghai, People's Republic of ChinaBackground: Integrins αvβ3 and αvβ5, both of which specifically recognize the Arg-Gly-Asp (RGD motif, are overexpressed on many solid tumors and in tumor neovasculature. Thus, coupling the RGD motif to the liposomal surface for achieving active targeting can be a promising strategy for the treatment of tumors.Methods: Cyclo(Arg-Gly-Asp-D-Phe-Cys (cRGD was covalently coupled with the liposomal membrane surface, followed by coating with poly(ethylene glycol (PEG using the post-insertion technique. The coupling efficiency of cRGD was determined. Doxorubicin as a model anticancer drug was loaded into liposomes using an ammonium sulfate gradient method to investigate the encapsulation efficiency, cellular uptake by the integrin-overexpressing human glioma cell line U87MG in vitro, and pharmacokinetic properties in Sprague-Dawley rats.Results: cRGD was conjugated to the liposomal surface by a thiol-maleimide coupling reaction. The coupling efficiency reached 98%. The encapsulation efficiency of doxorubicin in liposomes was more than 98%. The flow cytometry test result showed that cRGD-modified liposomes (RGD-DXRL-PEG had higher cell uptake by U87MG cells, compared with nontargeted liposomes (DXRL-PEG. The cellular uptake was significantly inhibited in the presence of excess free cRGD. Both the targeted (t1/2 = 24.10 hours and non-targeted (t1/2 = 25.32 hours liposomes showed long circulating properties in rat plasma. The area under the curve of the targeted and nontargeted liposomes was 6.4-fold and 8.3-fold higher than that of doxorubicin solution, respectively.Conclusion: This study indicates preferential targeting and long circulating properties for cRGD-modified liposomes in vivo, which could be used as

  10. Removal of heavy metals from water by zeolite mineral chemically modified. Mercury as a particular case

    International Nuclear Information System (INIS)

    Research works on the removal of mercury from water by zeolite minerals show that a small quantity of this element is sorbed. In this work the mercury sorption from aqueous solutions in the presence and absence of Cu(l l), Ni(l l) and/or Zn(l l) by a Mexican zeolite mineral, natural and modified by cisteaminium chloride or cistaminium dichloride, was investigated in acidic p H. The zeolite minerals were characterized by X- Ray diffraction Ftir, scanning electron microscopy and semiquantitative elemental analysis (EDS), surface area analysis (BET) and thermogravimetric analysis (TGA). Mercury from aqueous solutions was quantified by Atomic absorption spectroscopy. The amount of sulphur on the zeolite samples treated with Na CI and modified with cisteaminium chloride (0.375 mmol/g) or cistaminium dichloride(0.475 mmol/g) was found to be higher than that of the zeolite minerals modified with cisteaminium chloride and cistaminium dichloride without treating them with Na CI. The amount of sulphur on the zeolite minerals modified with thiourea was the lowest. The diffusion coefficients and sorption isotherms for mercury were determined in the natural, treated with Na CI and, treated with Na CI and then modified with the cisteaminium chloride or cistaminium dichloride zeolite samples. The retention of mercury was the highest for the zeolite minerals treated Na CI and then modified with cisteaminium chloride or cistaminium dichloride, with adsorption capacity of 0.0511 and 0.0525 mmol Hg/g, respectively. In this research work, it was found that the retention of mercury by the modified minerals was not affected by the presence of Cu (Il), Zn(l l) y Ni (I l) under the experimental conditions. (Author)

  11. HIGHLY EFFECTIVE CHEMICAL MODIFIERS FOR PRODUCTION OF CONCRETES WITH PRE-SET PROPERTIES

    Directory of Open Access Journals (Sweden)

    Tkach Evgeniya Vladimirovna

    2012-10-01

    Full Text Available The paper demonstrates the application of industrial by-products and recycled materials. Waterproofing admixtures improve the structure and the properties of the cement stone. Development and preparation of highly effective waterproofing modifiers of durable effect, as well as development of the process procedure parameters, including mixing, activation, heat treatment, etc. are to be implemented. The composition of waterproofing modifiers is to be fine-tuned to synergize the behaviour of various ingredients of cement systems to assure the substantial improvement of their strength, freeze- and corrosion resistance. Multi-functional waterproofing admixtures were used to produce highly effective modified concretes. The key idea of the new method of modifying cement-based building materials is that the waterproofing admixture concentration is to exceed 10% of the weight of the binding agent within the per-unit weight of the cement stone, given that its strength does not deteriorate. GKM-type modifier coupled with organo-mineral waterproofing admixture concentration agent GT-M may be recommended for mass use in the manufacturing of hydraulic concrete and reinforced concrete products. Overview of their practical implementation has proven that waterproofing modifier GKM-S, if coupled with waterproofing admixture concentration agent GT-M, improves the corrosion control inside the cement stone and makes it possible to manufacture durable concrete and reinforced concrete products that demonstrate pre-set physical and processing behaviour. Comprehensive concrete modification by modifier GKM-S and waterproofing admixture concentration agent GT-M may be regarded as one of the most ambitious methods of production of highly effective waterproof concretes.

  12. Pepsin immobilized in dextran-modified fused-silica capillaries for on-line protein digestion and peptide mapping

    Energy Technology Data Exchange (ETDEWEB)

    Stigter, E.C.A. [Division of Biomedical Analysis, Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht (Netherlands)], E-mail: e.c.a.stigter@uu.nl; Jong, G.J. de; Bennekom, W.P. van [Division of Biomedical Analysis, Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht (Netherlands)

    2008-07-07

    On-line digestion of proteins under acidic conditions was studied using micro-reactors consisting of dextran-modified fused-silica capillaries with covalently immobilized pepsin. The proteins used in this study differed in molecular weight, isoelectric point and sample composition. The injected protein samples were completely digested in 3 min and the digest was analyzed with micro-high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS). The different proteins present in the samples could be identified with a Mascot database search on the basis of auto-MS/MS data. It proved also to be possible to digest and analyze protein mixtures with a sequence coverage of 55% and 97% for the haemoglobin {beta}- and {alpha}-chain, respectively, and 35-55% for the various casein variants. Protease auto-digestion, sample carry-over and loss of signal due to adsorption of the injected proteins were not observed. The backpressure of the reactor is low which makes coupling to systems such as Surface Plasmon Resonance biosensors, which do not tolerate too high pressure, possible. The reactor was stable for at least 40 days when used continuously.

  13. Pepsin immobilized in dextran-modified fused-silica capillaries for on-line protein digestion and peptide mapping

    International Nuclear Information System (INIS)

    On-line digestion of proteins under acidic conditions was studied using micro-reactors consisting of dextran-modified fused-silica capillaries with covalently immobilized pepsin. The proteins used in this study differed in molecular weight, isoelectric point and sample composition. The injected protein samples were completely digested in 3 min and the digest was analyzed with micro-high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS). The different proteins present in the samples could be identified with a Mascot database search on the basis of auto-MS/MS data. It proved also to be possible to digest and analyze protein mixtures with a sequence coverage of 55% and 97% for the haemoglobin β- and α-chain, respectively, and 35-55% for the various casein variants. Protease auto-digestion, sample carry-over and loss of signal due to adsorption of the injected proteins were not observed. The backpressure of the reactor is low which makes coupling to systems such as Surface Plasmon Resonance biosensors, which do not tolerate too high pressure, possible. The reactor was stable for at least 40 days when used continuously

  14. Water-in-oil emulsions prepared by peptide-silicone hybrid polymers as active interfacial modifier: effects of silicone oil species on dispersion stability of emulsions.

    Science.gov (United States)

    Sakai, Kenichi; Iijima, Satoshi; Ikeda, Ryosuke; Endo, Takeshi; Yamazaki, Takahiro; Yamashita, Yuji; Natsuisaka, Makoto; Sakai, Hideki; Abe, Masahiko; Sakamoto, Kazutami

    2013-01-01

    We have recently proposed a new general concept regarding amphiphilic materials that have been named as "active interfacial modifier (AIM)." In emulsion systems, an AIM is essentially insoluble in both water and organic solvents; however, it possesses moieties that are attracted to each of these immiscible liquid phases. Hence, an AIM practically stays just at the interface between the two phases and makes the resulting emulsion stable. In this study, the effects of silicone oil species on the dispersion stability of water-in-oil (W/O) emulsions in the presence of an AIM sample were evaluated in order to understand the destabilization mechanism in such emulsion systems. The AIM sample used in this study is an amphiphilic polymer consisting of a silicone backbone modified with hydrocarbon chains and hydrolyzed silk peptides. The Stokes equation predicts that the sedimentation velocity of water droplets dispersed in a continuous silicone oil phase simply depends on the expression (ρ - ρ₀)/η assuming that the droplet size is constant (where ρ is the density of the dispersed water phase, ρ₀ is the density of the continuous silicone oil phase, and η is the viscosity of the oil phase). The experimental results shown in this paper are consistent with the Stokes prediction: i.e., in the low-viscous genuine or quasi-Newtonian fluid region, the dispersion stability increases in the following order: dodecamethylpentasiloxane (DPS) D₅ > D₆. This indicates that our emulsion system experiences destabilization through sedimentation, but hardly any coalescence occurs owing to the presence of an additional third phase consisting of the AIM that stabilizes the silicone oil/water interface in the emulsions. PMID:23823917

  15. Chemical vapour generation of silver: reduced palladium as permanent reaction modifier for enhanced performance

    Czech Academy of Sciences Publication Activity Database

    Matoušek, Tomáš; Sturgeon, R. E.

    2004-01-01

    Roč. 19, č. 8 (2004), s. 1014-1017. ISSN 0267-9477 R&D Projects: GA ČR GA203/01/0453 Institutional research plan: CEZ:AV0Z4031919 Keywords : chemical vapour generation * chemical modification * silver Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.926, year: 2004

  16. Determination of bismuth in environmental samples by slurry sampling graphite furnace atomic absorption spectrometry using combined chemical modifiers.

    Science.gov (United States)

    Dobrowolski, Ryszard; Dobrzyńska, Joanna; Gawrońska, Barbara

    2015-01-01

    Slurry sampling graphite furnace atomic absorption spectrometry technique was applied for the determination of Bi in environmental samples. The study focused on the effect of Zr, Ti, Nb and W carbides, as permanent modifiers, on the Bi signal. Because of its highest thermal and chemical stability and ability to substantially increase Bi signal, NbC was chosen as the most effective modifier. The temperature programme applied for Bi determination was optimized based on the pyrolysis and atomization curves obtained for slurries prepared from certified reference materials (CRMs) of the soil and sediments. To overcome interferences caused by sulfur compounds, Ba(NO₃)₂ was used as a chemical modifier. Calibration was performed using the aqueous standard solutions. The analysis of the CRMs confirmed the reliability of the proposed analytical method. The characteristic mass for Bi was determined to be 16 pg with the detection limit of 50 ng/g for the optimized procedure at the 5% (w/v) slurry concentration. PMID:25384374

  17. Sulfur Fixation by Chemically Modified Red Mud Samples Containing Inorganic Additives: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-01-01

    Full Text Available Sulfur retention ability of Bayer red mud from alumina plant was investigated. Bayer red mud modified by fusel salt and waste mother liquor of sodium ferrocyanide as the main sulfur fixation agent and the calcium based natural mineral materials as servicing additives; the experimental results showed the following: (1 Through 10 wt% waste mother liquor of sodium ferrocyanide modifying Bayer red mud, sulfur fixation rate can increase by 13 wt%. (2 Magnesium oxide can obviously improve the sulfur fixation performance of Bayer red mud and up to a maximum sulfur fixation rate of 47 wt% at adding 1 wt% magnesium oxide. (3 Dolomite enhanced the sulfur fixation performances with the sulfur fixation rate of 68 wt% in optimized condition. (4 Vermiculite dust reduced sulfur dioxide during the fixed-sulfur process of modified Bayer red mud, and the desulphurization ration could reach up to a maximum 76 wt% at 950°C. (5 An advanced three-component sulfur fixation agent was investigated, in which the optimized mass ratio of modified Bayer red mud, dolomite, and vermiculite dust was 70 : 28 : 2 in order, and its sulfur fixation efficiency has reached to a maximum 87 wt% under its 20 wt% dosage in the coal.

  18. Fabrication and characterization of indium sulfide thin films deposited on SAMs modified substrates surfaces by chemical bath deposition

    International Nuclear Information System (INIS)

    In an effort to explore the optoelectronic properties of nanostructured indium sulfide (In2S3) thin films for a wide range of applications, the In2S3 thin films were successfully deposited on the APTS layers (-NH2-terminated) modified ITO glass substrates using the chemical bath deposition technique. The surface morphology, structure and composition of the resultant In2S3 thin films were characterized by FESEM, XRD, and XPS, respectively. Also, the correlations between the optical properties, photocurrent response and the thickness of thin films were established. According to the different deposition mechanisms on the varying SAMs terminational groups, the positive and negative micropatterned In2S3 thin films were successfully fabricated on modified Si substrates surface combining with the ultraviolet lithography process. This offers an attractive opportunity to fabricate patterned In2S3 thin films for controlling the spatial positioning of functional materials in microsystems.

  19. A radiobiological approach to cancer treatment. Possible chemical and physical agents modifying radiosensitivity in comparison with high LET radiations

    International Nuclear Information System (INIS)

    Biological characteristics of high LET radiations are summarized to be low oxygen enhancement ratio, high RBE, low repair and low cell cycle dependency of radiosensitivity. Various chemical modifiers of radiosensitivity and radiological effect of hyperthermia are classified into these four properties. It is evident that we have now various means to mimic high LET radiations as far as biological response is concerned though some of them are still in experimental stage. Among them, the means to cope with hypoxia and repair which are assumed to be the most important causes of radioresistance of human tumors are discussed in some detail. It is expected that through the present seminar we would have consensus to concentrate our effort of development for new modifying means available and useful in developing countries. (author)

  20. Interpenetrating polymer networks based on polyol modified castor oil polyurethane and poly(2-hydroxyethylmethacrylate): Synthesis, chemical, mechanical and thermal properties

    Indian Academy of Sciences (India)

    K Prashantha; K Vasanth Kumar Pai; B S Sherigara; S Prasannakumar

    2001-10-01

    Interpenetrating polymer networks (IPNs) of glycerol modified castor oil polyurethane (GC–PU) and poly[2-hydroxyethylmethacrylate] (PHEMA) were synthesized using benzoyl peroxide as initiator and N,N-methylene bis acrylamide as crosslinker. GC–PU/PHEMA interpenetrating polymer networks were obtained by transfer moulding. These were characterized with respect to their resistance to chemical reagents and mechanical properties such as tensile strength, per cent elongation and shore A hardness. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were undertaken for thermal characterization. The changes in NCO/OH ratio and GC–PU/PHEMA composition on the properties of the IPNs were studied.

  1. Biosorption of Cu (II onto chemically modified waste mycelium of Aspergillus awamori: Equilibrium, kinetics and modeling studies

    Directory of Open Access Journals (Sweden)

    ZDRAVKA VELKOVA

    2012-01-01

    Full Text Available The biosorption potential of chemically modified waste mycelium of industrial xylanase-producing strain Aspergillus awamori for Cu (II removal from aqueous solutions was evaluated. The influence of pH, contact time and initial Cu (II concentration on the removal efficiency was evaluated. Maximum biosorption capacity was reached by sodium hydroxide treated waste fungal mycelium at pH 5.0. The Langmuir adsorption equation matched very well the adsorption equilibrium data in the studied conditions. The process kinetic followed the pseudo-firs order model.

  2. Comparison of Chemical Modifiers for Simultaneous Determination of Different Selenium-Compounds in Serum and Urine by Zeeman-Effect Electrothermal Atomic-Absorption Spectrometry

    DEFF Research Database (Denmark)

    Johannessen, J.K.; Gammelgaard, Bente; Jons, O.;

    1993-01-01

    The thermal stability of selenite, selenate, selenomethionine and trimethylselenonium was studied using different chemical modifiers in various amounts. The normally recommended amounts of nickel nitrate, magnesium nitrate, copper nitrate, copper nitrate mixed with magnesium nitrate, palladium ni...

  3. Determination of vanadium in mussels by electrothermal atomic absorption spectrometry without chemical modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Saavedra, Y.; Fernandez, P. [Centro de Control do Medio Marino, Peirao de Vilaxoan s/n, Vilagarcia de Arousa, 36611 Pontevedra (Spain); Gonzalez, A. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Quimica, 15706, Santiago de Compostela (Spain)

    2004-05-01

    A method was developed for the quantitative determination of total vanadium concentration in mussels via electrothermal atomic absorption spectrometry (ETAAS). After the microwave digestion of the samples, a program using temperatures of 1600 C and 2600 C for ashing and atomization respectively, without any matrix modifiers, allowed us to obtain results that were satisfactory since they agreed closely with certified reference material values. The detection limit was 0.03 mg kg{sup -1} (dry weight), indicating that the method is suitable for the analysis of mussel samples. This determination was compared with matrix modifiers that have been reported previously. The method was applied to various cultivated and wild mussels from the Galician coast, yielding levels below 1 mg kg{sup -1} (wet weight). (orig.)

  4. Thrombin Binding Aptamer, More than a Simple Aptamer: Chemically Modified Derivatives and Biomedical Applications

    OpenAIRE

    Aviñó, Anna Maria; Eritja Casadellà, Ramón; Fàbrega, Carme; Tintoré, María

    2012-01-01

    The thrombin binding aptamer (TBA) is a well characterized chair-like, antiparallel quadruplex structure that binds specifically to thrombin at nanomolar concentrations and therefore it has interesting anticoagulant properties. In this article we review the research involved in the development of new TBA derivatives with improved anticoagulant properties as well as the use of the TBA as a model compound for the study of quadruplex structures. Specifically, we describe the impact of modified n...

  5. Rheological behaviour of polymer-modified bituminous mastics : a comparative analysis between physical and chemical modification

    OpenAIRE

    Shivokhin, Maxim; García Morales, Moisés; Partal López, Pedro; Cuadri Vega, Antonio Abad; Gallegos Montes, Críspulo

    2012-01-01

    Mastic, a bitumen/filler blend which naturally forms when bitumen is mixed with aggregates is the actual product used to bind coarse mineral particles in the asphalt mixtures. As a result, the characterisation of mastics is essential to improve the understanding of the response and performance of asphalt concrete pavements. On the other hand, the lack of experimental data concerning the behaviour of mastics and, above all, polymer-modified mastics has been lately claimed. In that sense, this ...

  6. Chemically-modified graphene sheets as an active layer for eco-friendly metal electroplating on plastic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Joon-Suk; Hwang, Taeseon; Nam, Gi-Yong; Hong, Jung-Pyo [Department of Polymer Science and Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-gu, Suwon, 440-746 (Korea, Republic of); Bae, Ah-Hyun; Son, Sang-Ik; Lee, Geun-Ho; Sung, Hak kyung [Manufacturing Tech. Center, Samsung Electronics Co., Ltd., Maetan-dong, Yeongtong-gu, Suwon, 443-742 (Korea, Republic of); Choi, Hyouk Ryeol; Koo, Ja Choon [School of Mechanical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of); Nam, Jae-Do, E-mail: jdnam@skku.edu [Department of Polymer Science and Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-gu, Suwon, 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon (Korea, Republic of)

    2012-10-30

    Eco-friendly nickel (Ni) electroplating was carried out on a plastic substrate using chemically modified graphene sheets as an active and conductive layer to initiate electroplating without using conventional pre-treatment or electroless metal-seeding processes. A graphene oxide (GO) solution was self-assembled on a polyethylene terephthalate (PET) film followed by evaporation to give GO layers (thickness around 6.5 {mu}m) on PET (GO/PET) film. Then, the GO/PET film was chemically and thermally reduced to convert the GO layers to reduced graphene oxide (RGO) layers on the PET substrate. The RGO-coated PET (RGO/PET) film showed the sheet resistance of 100 {Omega} per square. On RGO/PET film, Ni electroplating was conducted under the constant-current condition and the entire surface of the PET film was completely metalized with Ni without any voids.

  7. Chemically-modified graphene sheets as an active layer for eco-friendly metal electroplating on plastic substrates

    International Nuclear Information System (INIS)

    Eco-friendly nickel (Ni) electroplating was carried out on a plastic substrate using chemically modified graphene sheets as an active and conductive layer to initiate electroplating without using conventional pre-treatment or electroless metal-seeding processes. A graphene oxide (GO) solution was self-assembled on a polyethylene terephthalate (PET) film followed by evaporation to give GO layers (thickness around 6.5 μm) on PET (GO/PET) film. Then, the GO/PET film was chemically and thermally reduced to convert the GO layers to reduced graphene oxide (RGO) layers on the PET substrate. The RGO-coated PET (RGO/PET) film showed the sheet resistance of 100 Ω per square. On RGO/PET film, Ni electroplating was conducted under the constant-current condition and the entire surface of the PET film was completely metalized with Ni without any voids.

  8. Effects of the substitution of amino acid residues, through chemical synthesis, on the conformation and activity of antimicrobial peptides

    Directory of Open Access Journals (Sweden)

    Regina C. Adão

    2012-06-01

    Full Text Available Antimicrobial peptides make up an assorted group of molecules which contain from 12 to 50 amino acid residues and which may be produced by microorganisms, plants and animals. From the discovery that these biomolecules are lethal to bacteria, inhibiting the pathogenic organism’s growth, and are also related to innate and adapted defense mechanisms, the investigation of such molecules came to be an emergent research field, in which more than 1800 antimicrobial peptides have so far been discovered throughout the last three decades. These molecules are potential representatives of a new generation of antibiotic agents and the main motivation for such use is their activity against a wide variety of pathogens, including Gram-positive and Gram-negative bacteria as well as fungi and viruses. An important class of comprising some of these peptides may be found in anurans, from which it has been isolated, a considerable number of antimicrobial peptides with diverse sequences and structures, including linear and dimeric ones. In this work monomeric chains (CH1 e CH2 of the heterodimeric antimicrobial peptide distinctin (isolated in 1999 from Phyllomedusa distincta anurans, as well as its mutated monomers (CH1-S and CH2-S and the heterodimer itself were synthesized. The distinctin is the peptide with two chains of different sequences (Table 1 bound each other by disulfide bond from the cystein residues constituting the heterodimer. To investigate the effects on the biological activity by amino acids substitution at normal distinctin CH1 and CH2 chains, both were synthesized as well as their similar chains (CH1-S and CH2-S in which the cystein (Fig.1 a residues of each chain were changed by serin residues (Fig. 1 b. The new chains were named mutants. The synthesis was carried out in solid phase, using Fmoc strategy. The heterodimer distinctin was obtained from CH1 and CH2 chains coupling through cystein residues air oxidation. The results from HPLC

  9. A Fly-Through Mission Strategy Targeting Peptide as a Signature of Chemical Evolution and Possible Life in Enceladus Plumes

    Science.gov (United States)

    Fujishima, Kosuke; Dziomba, Szymon; Takahagi, Wataru; Shibuya, Takazo; Takano, Yoshinori; Guerrouache, Mohamed; Carbonnier, Benjamin; Takai, Ken; Rothschild, Lynn J.; Yano, Hajime

    2016-01-01

    In situ detection of organic molecules in the extraterrestrial environment provides a key step towards better understanding the variety and the distribution of building blocks of life and it may ultimately lead to finding extraterrestrial life within the Solar System. Here we present combined results of two separate experiments that enable us to realize such in situ life signature detection from the deep habitats of the "Ocean World": a hydrothermal reactor experiment simulating complex organic synthesis and a simulated fly-through capture experiment of organic-bearing microparticles using silica aerogels, followed by subsequent analysis. Both experiments employ peptide as a plausible organics existing in Encleadus plume particles produced in its subsurface ocean. Recent laboratory hydrothermal experiments and a theoretical model on silica saturation indicated an on going hydrothermal reactions in subsurface Enceladus ocean. Given the porous chondritic origin of the core, it is likely that organic compounds originated by radiation chemistry such as amino acid precursors could have been provided, leached, and altered through widespread water-rock interactions. By using the same laboratory experimental setup from the latest water-rock interaction study, we performed amino acid polymerization experiments for 144 days and monitored the organic complexity changing over time. So far over 3,000 peaks up to the size of greater than 600 MW were observed through the analysis of capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS) with an indication of amino acid derivatives and short peptides. Generally abiotic polymerization of enantiomeric amino acids results in forming stereoisomeric peptides with identical molecular weight and formula as opposed to homochiral biopolymers. Assuming Enceladus plume particles may contain a mixture of stereoisomeric peptides, we were able to distinguish 16 of the 17 stereoisomeric tripeptides as a test sample using

  10. Physical, chemical and sensory changes in irradiated fresh pork packaged in modified atmosphere

    International Nuclear Information System (INIS)

    The effects of irradiation dose (0, 0.5 and 1.0 kGy), headspace oxygen (0, 10 and 20% O2 balance nitrogen) and storage temperature (5, 15 and 25 degrees C) on the physical, chemical and sensory changes in fresh pork were studied using factorial design experiments. Irradiation in the absence of oxygen extended the sensory shelf life of pork from 9 to 26 days at 5 degrees C and from 2 to 2 days at 25 degrees C. Oxygen in the package headspace combined with irradiation adversely affected physical, chemical and sensory characteristics of the end product

  11. Study of sorption and desorption characteristics of natural and chemically modified ionexes

    International Nuclear Information System (INIS)

    The aim of this paper was give information for scientific community about not-traditionally, simply, high precise and effective radio-indicator method and possibilities its use for determination of sorption characteristics of naturals and chemically adjusted ionexes. These materials are suitable as barrier materials for water, soil and air cleaning

  12. Structure and Electrical Study of New Chemically Modified Poly(vinyl chloride

    Directory of Open Access Journals (Sweden)

    F. Ammari

    2015-01-01

    Full Text Available The aim of this work was to study the structural and electrical properties of a new polymer obtained by functionalization of a commercial poly(vinyl chloride (PVC (Mw = 48000 by grafting aminoalkyl and aminoaryl groups. Modified poly(vinyl chloride was prepared in two steps. The structural properties of the polymer were systematically investigated by varieties of techniques as differential scanning calorimetric (DSC, thermogravimetry analysis (TG, X-ray diffraction (XRD, and Fourier transform infrared (FTIR spectroscopy. The electrical properties of the polymer were studied by electrochemical impedance spectroscopy (EIS.

  13. Chemically Modified Chitosan Beads as Molecularly Imprinted Polymer Matrix for Adsorptive Separation of Proteins

    Institute of Scientific and Technical Information of China (English)

    Tian Ying GUO; Yong Qing XIA; Guang Jie HAO; Bang Hua ZHANG

    2004-01-01

    In a phosphate buffer, a hemoglobin (Hb)-imprinted polymer complex was prepared using maleic anhydride (MAH) modified chitosan beads as matrix, acrylamide (AM) as functional monomer, N,N-methylenebisacrylamide (MBA) as cross-linker and potassiumpersulfate (KPS)/sodium hydrogen sulfite (NaHSO3) as initiators. Langmuir analysis showed that an equal class of adsorption was formed in the molecular imprinting polymer (MIP), and the MIP has high adsorption capacity and selectivity for the imprinted molecule. The MIP can be reused and the recovery was approximately 100% at low concentration.

  14. Biosorption of stable cesium by chemically modified biomass of Sargassum glaucescens and Cystoseira indica in a continuous flow system

    International Nuclear Information System (INIS)

    Pretreatment of biosorbents have been suggested to modify the surface characteristics which could improve biosorption process. Stable cesium biosorption was studied in continuous fixed-bed column by chemically modified biosorbents. Two kinds of brown algae (Sargassum glaucescens and Cystoseira indica) were treated with chemical agents including formaldehyde (FA), glutaraldehyde (GA), potassium hexacyanoferrate (HCF), FA and HCF, and GA and HCF. The highest biosorption capacity (BC) was obtained from C. indica treated with FA (63.5 mg Cs/g biomass) and S. glaucescens treated with FA and HCF (62 mg Cs/g biomass). To study the effect of the best treatments on the BC, the concentration of each treatment agent was decreased. With decreasing FA agent for C. indica treatment, the BC dropped. Treatment of 1 g S. glaucescens biomass with 2.2 g FA and then 0.18 g HCF resulted in the highest BC (73.08 mg Cs/g dry biomass) which was 35.8 times higher than intact S. glaucescens

  15. Thermo-chemical characterization of a Al nanoparticle and NiO nanowire composite modified by Cu powder

    Energy Technology Data Exchange (ETDEWEB)

    Bohlouli-Zanjani, Golnaz [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave West, Waterloo, ON N2L 3G1 (Canada); Wen, John Z., E-mail: john.wen@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave West, Waterloo, ON N2L 3G1 (Canada); Hu, Anming [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave West, Waterloo, ON N2L 3G1 (Canada); Persic, John [Microbonds Inc., 151 Amber St., Unit 12, Markham, ON L3R 3B3 (Canada); Ringuette, Sophie [Defence Research and Development Canada – Valcartier, 2459 Pie-XI Blvd North, Quebec, QC G3K1Y1 (Canada); Zhou, Y. Norman [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave West, Waterloo, ON N2L 3G1 (Canada)

    2013-11-20

    Highlights: • First study on the copper modified powder-type Al nanoparticle and NiO nanowire composites. • Experimental findings were unique in identifying the AlNi formation and comparing with the Al/CuO thermite. • Potential applications in material joining and bonding. - Abstract: Thermo-chemical properties of the Al nanoparticle and NiO nanowire composites modified by the micro-sized copper additive were investigated experimentally. Their onset temperatures of ignition and energy release data per mass were characterized using differential thermal analysis measurements. These microstructures and chemical compositions of reaction products were analyzed using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. The fuel-rich Al/NiO/Cu composites produced two types of metallic spheres. Copper spheres were formed from melting and solidification of the copper additive, while AlNi composite spheres were identified by the energy dispersive X-ray spectroscopy and X-ray diffraction analyses. It was found that the amount of the copper additive did not significantly influence the onset temperature of thermite peaks, but caused a dramatic change in energy release. The aforementioned ignition and energetic properties were compared with these from the Al nanoparticle and CuO nanowire composites.

  16. Adsorption of hexavalent chromium from synthetic and electroplating effluent on chemically modified Swietenia mahagoni shell in a packed bed column.

    Science.gov (United States)

    Rangabhashiyam, S; Nandagopal, M S Giri; Nakkeeran, E; Selvaraju, N

    2016-07-01

    Packed bed column studies were carried out to evaluate the performance of chemically modified adsorbents for the sequestration of hexavalent chromium from synthetic and electroplating industrial effluent. The effects of parameters such as bed height (3-9 cm), inlet flow rate (5-15 mL/min), and influent Cr(VI) concentration (50-200 mg/L) on the percentage removal of Cr(VI) and the adsorption capacity of the adsorbents in a packed bed column were investigated. The breakthrough time increased with increasing bed height and decreased with the increase of inlet flow rate and influent Cr(VI) concentration. The adsorption column models such as Thomas, Adams-Bohart, Yoon-Nelson, and bed depth service time (BDST) were successfully correlated with the experimental data. The Yoon-Nelson and BDST model showed good agreement with the experimental data for all the studied parameter conditions. Results of the present study indicated that the chemically modified Swietenia mahagoni shell can be used as an adsorbent for the removal of Cr(VI) from industrial wastewater in a packed bed column. PMID:27312254

  17. Thermo-chemical characterization of a Al nanoparticle and NiO nanowire composite modified by Cu powder

    International Nuclear Information System (INIS)

    Highlights: • First study on the copper modified powder-type Al nanoparticle and NiO nanowire composites. • Experimental findings were unique in identifying the AlNi formation and comparing with the Al/CuO thermite. • Potential applications in material joining and bonding. - Abstract: Thermo-chemical properties of the Al nanoparticle and NiO nanowire composites modified by the micro-sized copper additive were investigated experimentally. Their onset temperatures of ignition and energy release data per mass were characterized using differential thermal analysis measurements. These microstructures and chemical compositions of reaction products were analyzed using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. The fuel-rich Al/NiO/Cu composites produced two types of metallic spheres. Copper spheres were formed from melting and solidification of the copper additive, while AlNi composite spheres were identified by the energy dispersive X-ray spectroscopy and X-ray diffraction analyses. It was found that the amount of the copper additive did not significantly influence the onset temperature of thermite peaks, but caused a dramatic change in energy release. The aforementioned ignition and energetic properties were compared with these from the Al nanoparticle and CuO nanowire composites

  18. Thermogravimetric Analysis of Modified Hematite by Methane (CH{sub 4}) for Chemical-Looping Combustion: A Global Kinetics Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Monazam, Esmail R; Breault, Ronald W; Siriwardane, Ranjani; Miller, Duane D

    2013-10-01

    Iron oxide (Fe{sub 2}O{sub 3}) or in its natural form (hematite) is a potential material to capture CO{sub 2} through the chemical-looping combustion (CLC) process. It is known that magnesium (Mg) is an effective methyl cleaving catalyst and as such it has been combined with hematite to assess any possible enhancement to the kinetic rate for the reduction of Fe{sub 2}O{sub 3} with methane. Therefore, in order to evaluate its effectiveness as a hematite additive, the behaviors of Mg-modified hematite samples (hematite –5% Mg(OH){sub 2}) have been analyzed with regard to assessing any enhancement to the kinetic rate process. The Mg-modified hematite was prepared by hydrothermal synthesis. The reactivity experiments were conducted in a thermogravimetric analyzer (TGA) using continuous stream of CH{sub 4} (5, 10, and 20%) at temperatures ranging from 700 to 825 {degrees}C over ten reduction cycles. The mass spectroscopy analysis of product gas indicated the presence of CO{sub 2}, H{sub 2}O, H{sub 2} and CO in the gaseous product. The kinetic data at reduction step obtained by isothermal experiments could be well fitted by two parallel rate equations. The modified hematite samples showed higher reactivity as compared to unmodified hematite samples during reduction at all investigated temperatures.

  19. Enhanced Electrochemical Performance of Lithium Iron(II) Phosphate Modified Cooperatively via Chemically Reduced Graphene Oxide and Polyaniline

    International Nuclear Information System (INIS)

    Highlights: •LiFePO4 was modified cooperatively with reduced graphene oxide and PANI •LiFePO4/ reduced graphene oxide /PANI composites showed unique 3D network structures •The composites exhibited enhanced electrochemical performances as cathode •The enhanced property is from unique structure and inherent properties of components -- Abstract: It is essential to improve the electron and lithium ion conductivities of Lithium iron(II) phosphate (LiFePO4) used as a cathode material for lithium-ion batteries. In the work, we designed and fabricated a series of composites of LiFePO4 modified cooperatively with chemically reduced graphene oxide (RGO) and polyaniline. It was demonstrated that the composites have a three dimensional network structures in which the CRGO and the polyaniline were intertwined and coated uniformly on the surface of LiFePO4. Comparably, as cathode for lithium-ion batteries, the as-prepared composites showed better electrochemical performances than the bare LiFePO4 and the LiFePO4 modified simply with CRGO or polyaniline alone. The elaboration of the underneath mechanism on the pronounced electrochemical properties of the composites was also attempted and discussed

  20. Chemically modified graphene and nitrogen-doped graphene: Electrochemical characterisation and sensing applications

    International Nuclear Information System (INIS)

    Highlights: •Characterisation of graphene, N-doped graphene, acid/base functionalised derivatives. •N-doping superior to time-consuming functionalisation procedures. •N-doped graphene with redox or conducting polymer composites characterised. •Electrocatalysis of enzyme cofactors FAD+ and NADH2, by N-doped graphene. -- Abstract: Functionalised graphene (G) and nitrogen doped graphene (NG) nanomaterials are excellent candidates for electrocatalytic sensing of biomolecules and for developing biosensors, due to their unique physicochemical and electronic properties. Electrochemical characterisation and comparison of basic or acidic functionalised G and NG has been carried out, as well as of composite materials based on NG with the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and the redox polymer poly(neutral red) by cyclic voltammetry and electrochemical impedance spectroscopy. Electroactive areas and heterogeneous electron transfer constant, of the GCE modified with the graphene derivatives have been evaluated, in order to choose the best material for electrode modification. The NG modified GCE enabled excellent electrocatalytic regeneration of the enzyme cofactors β-nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), underlining the applicability of NG for the development of new sensitive biosensors

  1. Biosorption of heavy metals from aqueous solutions by chemically modified orange peel

    International Nuclear Information System (INIS)

    Equilibrium, thermodynamic and kinetic studies were carried out for the biosorption of Pb2+, Cd2+ and Ni2+ ions from aqueous solution using the grafted copolymerization-modified orange peel (OPAA). Langmuir and Freundlich isotherm models were applied to describe the biosorption of the metal ions onto OPAA. The influences of pH and contact time of solution on the biosorption were studied. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. According to the Langmuir equation, the maximum uptake capacities for Pb2+, Cd2+ and Ni2+ ions were 476.1, 293.3 and 162.6 mg g-1, respectively. Compared with the unmodified orange peel, the biosorption capacity of the modified biomass increased 4.2-, 4.6- and 16.5-fold for Pb2+, Cd2+ and Ni2+, respectively. The kinetics for Pb2+, Cd2+ and Ni2+ ions biosorption followed the pseudo-second-order kinetics. The free energy changes (ΔGo) for Pb2+, Cd2+ and Ni2+ ions biosorption process were found to be -3.77, -4.99 and -4.22 kJ mol-1, respectively, which indicates the spontaneous nature of biosorption process. FTIR demonstrated that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions. Desorption of Pb2+, Cd2+ and Ni2+ ions from the biosorbent was effectively achieved in a 0.05 mol L-1 HCl solution.

  2. Chemically Modified Activated Carbons as Catalysts of Oxidative Dehydrogenation of n-Butane

    International Nuclear Information System (INIS)

    Commercial availability and low price of light alkanes make them very attractive in many branches of industry. Potentially interesting is their use in the process of oxidative dehydrogenation leading to production of olefins. This study was undertaken to characterise the oxidative dehydrogenation of n-butane to 1,3-butadiene (important substrate in production of synthetic rubber and polyamides) taking place over the modified carbon catalysts obtained from peach stones precursor. The catalytic tests were performed in the temperature range 250-450oC at oxygen/n-butane ratio of 1:1. For the majority of the activated carbon samples studied at the lowest temperature the only product was CO2. At 300oC the products of dehydrogenation of n-butane and side products appeared. With increasing temperature the amount of compounds generated increased and in the group of C4 hydrocarbons the dominant were 1-butene and 1,3-butadiene. The most effective catalyst was the sample oxidised with air, the least effective was the sample modified with ammonium peroxydisulphate. (authors)

  3. Physico-chemical properties of corn starch modified with cyclodextrin glycosyltransferase.

    Science.gov (United States)

    Dura, Angela; Rosell, Cristina M

    2016-06-01

    Cyclodextrin glycosyltransferase (CGTase) has been used to produce cyclodextrins (CDs) from starches, but their ability to modify starches has been barely explored. The effect of CGTase on corn starch at sub-gelatinization temperature (50°C) and at different pH conditions, pH 4.0 and pH 6.0, was evaluated. Biochemical features, thermal and structural analysis, oligosaccharides and CDs content were studied. Microscopic analysis of the granules confirmed the enzymatic modification of the starches obtaining structures with irregular surface and small pinholes. The extent of the starch modification was largely dependent on the pHs, being higher at pH 6.0. This was also confirmed by the low viscosity of the resulting pastes during a heating and cooling cycle. Thermal parameters were not affected due to enzymatic treatment. Modified starches were less susceptible to undergo α-amylase hydrolysis. CDs released were higher for samples treated at pH 4.0. Therefore, CGTase modification of corn starches at sub-gelatinization temperature offers an attractive alternative for obtaining porous starches with different properties depending on the pH conditions. PMID:26970178

  4. Amyloid fibrillation in native and chemically-modified forms of carbonic anhydrase II: role of surface hydrophobicity.

    Science.gov (United States)

    Es-Haghi, Ali; Shariatizi, Sajad; Ebrahim-Habibi, Azadeh; Nemat-Gorgani, Mohsen

    2012-03-01

    Chemical modification or mutation of proteins may bring about significant changes in the net charge or surface hydrophobicity of a protein structure. Such events may be of major physiological significance and may provide important insights into the genetics of amyloid diseases. In the present study, fibrillation potential of native and chemically-modified forms of bovine carbonic anhydrase II (BCA II) were investigated. Initially, various denaturing conditions including low pH and high temperatures were tested to induce fibrillation. At a low pH of around 2.4, where the protein is totally dissociated, the apo form was found to take up a pre-molten globular (PMG) conformation with the capacity for fibril formation. Upon increasing the pH to around 3.6, a molten globular (MG) form became abundant, forming amorphous aggregates. Charge neutralization and enhancement of hydrophobicity by methylation, acetylation and propionylation of lysine residues appeared very effective in promoting fibrillation of both the apo and holo forms under native conditions, the rates and extents of which were directly proportional to surface hydrophobicity, and influenced by salt concentration and temperature. These modified structures underwent more pronounced fibrillation under native conditions, than the PMG intermediate form, observed under denaturing conditions. The nature of the fibrillation products obtained from intermediate and modified structures were characterized and compared and their possible cytotoxicity determined. Results are discussed in terms of the importance of surface net charge and hydrophobicity in controlling protein aggregation. A discussion on the physiological significance of the observations is also presented. PMID:22251892

  5. Catalytic activity of platinum on ruthenium electrodes with modified (electro)chemical states.

    Science.gov (United States)

    Park, Kyung-Won; Sung, Yung-Eun

    2005-07-21

    Using Pt on Ru thin-film electrodes with various (electro)chemical states designed by the sputtering method, the effect of Ru states on the catalytic activity of Pt was investigated. The chemical and electrochemical properties of Pt/Ru thin-film samples were confirmed by X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry. In addition, Pt nanoparticles on Ru metal or oxide for an actual fuel cell system showed an effect of Ru states on the catalytic activity of Pt in methanol electrooxidation. Finally, it was concluded that such an enhancement of methanol electrooxidation on the Pt is responsible for Ru metallic and/or oxidation sites compared to pure Pt without any Ru state. PMID:16852701

  6. Recognition of RNA duplexes by chemically modified triplex-forming oligonucleotides

    OpenAIRE

    Zhou, Yuan; Kierzek, Elzbieta; Loo, Zi Ping; Antonio, Meraldo; Yau, Yin Hoe; Chuah, York Wieo; Geifman-Shochat, Susana; Kierzek, Ryszard; Chen, Gang

    2013-01-01

    Triplex is emerging as an important RNA tertiary structure motif, in which consecutive non-canonical base pairs form between a duplex and a third strand. RNA duplex region is also often functionally important site for protein binding. Thus, triplex-forming oligonucleotides (TFOs) may be developed to regulate various biological functions involving RNA, such as viral ribosomal frameshifting and reverse transcription. How chemical modification in TFOs affects RNA triplex stability, however, is n...

  7. Adsorption Studies of Phenol Using Thermally and Chemically Modified Rice Husk as Adsorbents

    OpenAIRE

    *M. M. Yousaf; Ibrahim ,

    2014-01-01

    Most of the Phenols are hazardous substances and some are supposed to have carcinogenic activity. Thus it is necessary to remove Phenolics and other aromatics from the aqueous ecosystem. Traditional processes for the removal of Phenolics compounds are extraction, adsorption on granulated activated carbon, steam distillation, chemical and bacterial techniques. Literature survey show a number of methods like oxidation, ion exchange, reverse osmosis, electrochemical oxidation and adsorption. Phe...

  8. Developing electrodes chemically modified with cucurbit[6]uril to detect 3,4-methylenedioxymethamphetamine (MDMA) by voltammetry

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • A new stand in forensic chemistry. • Voltammetric method for the determination of MDMA in seized samples. • A new voltammetric sensor for MDMA. - Abstract: This study aimed to develop an electrode chemically modified with cucurbit[6]uril to detect 3,4-methylenedioxymethamphetamine (MDMA), the main active principle of ecstasy samples, by voltammetry. We modified the electrode surface with a film containing cucurbit[6]uril, Nafion, and methanol, using the dip coating or the spin coating technique. During analysis, we employed an electrochemical cell with a conventional three-electrode system and KCl solution (0.1 mol L−1) as the supporting electrolyte. We conducted cyclic voltammetry at concentrations ranging from 4.2 × 10−6 to 4.8 × 10−5mol L−1. We also accomplished scanning electron microscopy, to investigate the structural behavior of the film that originated on the electrode surface. We obtained the following results when we used dip coating to prepare the modified electrode: standard deviation (SD) = 0.024 μA, limit of detection (LOD) = 3.5 μmol L−1, limit of quantification (LOQ) = 11.7 μmol L−1, and amperometric sensitivity (m) = 20.9 × 103 μA L mol−1. As for spin coating, we obtained SD = 0.024 μA, LOD = 2.7 μmol L−1, LOQ = 9.1 μmol L−1 and m = 25.9 × 103 μA mol L−1. These are very promising data: the modified electrode is more sensitive than the conventional glassy carbon electrode under the studied experimental conditions

  9. Radiation chemical and photochemical study of Z-DNA modified by 2-aminopurine and 8- bromodeoxyguanosine

    International Nuclear Information System (INIS)

    DNA is able to take a number of local conformations. (CG) n repeats have the highest potential to Z-DNA which has a left-handed zig-zag backbone and unusual syn-conformation purine base. Because of the polymorphic nature of dinucleotide repeats, it seems possible that Z-DNA forming sequences may provide a source of genetic variation if they occur in regions that are important for the regulation of gene activity. Here, we investigated structural properties of Z-DNA compared with those of B-DNA with respects to one-electron attachment reaction of 8-bromodeoxyguanosine (dBrG) and fluorescence properties of 2-aminopurine (Ap). To investigate one-electron attachment reaction of Z-DNA, we synthesized oligodeoxynucleotides modified by dBrG in which syn-conformation deoxyguanosine was stabilized by steric repulsion between 8-bromo group of dBrG and sugar moiety in Z-DNA. Debromination from the dBrG modified oligodeoxynucleotides occurred from the one-electron attachment during the gamma-ray irradiation. The structural dependence of B- and Z-DNA was observed in the one-electron attachment reaction. Interestingly, the higher conversion of dBrG were observed in the Z-DNA than in the B-DNA. Since the solvent accessibility to purine base in Z-DNA increases compared with that in B-DNA, it is suggested that the electron attachment is enhanced in Z-DNA than in B-DNA. Next we studied the fluorescence properties of Ap in left-handed Z-DNA and compared with those in B-DNA. Since photoexcited adenine analogue Ap can serve as a sensitive probe of DNA structural dynamics, we synthesized Ap- and dBrG-modified oligodeoxynucleotides. Higher intensity was observed in the steady-state fluorescence of Ap in Z-DNA than in B-DNA. A new peak at 275 nm was observed in the excitation spectrum measured at the Ap emission wavelength 370 nm in Z-DNA. This has been explained by the energy transfer from the excited nucleobases to Ap. It is found that Ap is a useful fluorescence probe of Z-DNA

  10. Biosorption of heavy metals from aqueous solutions by chemically modified orange peel

    Energy Technology Data Exchange (ETDEWEB)

    Feng Ningchuan [School of Basic Medical Science, Ningxia Medical University, Yinchuan 750004 (China); Guo Xueyi, E-mail: xyguo@mail.csu.edu.cn [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Liang Sha [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Zhu Yanshu; Liu Jianping [School of Basic Medical Science, Ningxia Medical University, Yinchuan 750004 (China)

    2011-01-15

    Equilibrium, thermodynamic and kinetic studies were carried out for the biosorption of Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions from aqueous solution using the grafted copolymerization-modified orange peel (OPAA). Langmuir and Freundlich isotherm models were applied to describe the biosorption of the metal ions onto OPAA. The influences of pH and contact time of solution on the biosorption were studied. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. According to the Langmuir equation, the maximum uptake capacities for Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions were 476.1, 293.3 and 162.6 mg g{sup -1}, respectively. Compared with the unmodified orange peel, the biosorption capacity of the modified biomass increased 4.2-, 4.6- and 16.5-fold for Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+}, respectively. The kinetics for Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions biosorption followed the pseudo-second-order kinetics. The free energy changes ({Delta}G{sup o}) for Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions biosorption process were found to be -3.77, -4.99 and -4.22 kJ mol{sup -1}, respectively, which indicates the spontaneous nature of biosorption process. FTIR demonstrated that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions. Desorption of Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions from the biosorbent was effectively achieved in a 0.05 mol L{sup -1} HCl solution.

  11. Investigation of the biofouling properties of several algae on different textured chemical modified silicone surfaces

    International Nuclear Information System (INIS)

    Highlights: • Engineered pillars, pits and grooves spaced 3–12 μm apart were fabricated on siloxane modified acrylic resin films. • The effect of feature size, geometry, and wettability on the settlement of different algae was evaluated. • The feature size and geometry displayed a substantial correlation with the antifouling properties. • A comparatively physical fouling deterrent mechanism was analyzed. - Abstract: Engineered pillars, pits and grooves spaced 3, 6, 9 and 12 μm apart were fabricated on siloxane modified acrylic resin films. The effect of feature size, geometry, and wettability on the settlement of different algae was evaluated. These films showed various antifouling performances to Ulothrix, Closterium and Navicula. For Navicula (length: 10–12 μm), the feature size and geometry displayed a substantial correlation with the antifouling properties. The film with pillars spaced 3 μm reduced Navicula settlement by 73% compared to the control surface. For Closterium (length: 45–55 μm), their responses were governed by the same underlying thermodynamic principles as wettability, the largest reduction in Closterium, 81%, was obtained on the surface with grooves spaced 12 μm apart. For Ulothrix (length: 5–8 mm), the surface also showed the best antifouling performance, the reduction ratio of the settlement on the surface with grooves spaced 12 μm apart could even reach 92%. At last, physical fouling deterrent mechanisms for the films with various textures were analyzed in detail. The feature size and geometry display a substantial correlation with the antifouling properties when the size of fouling algae is close to the textures. With the increasing size for algae, antifouling performance was getting better on surface with pillars or grooves because the algae are bridged between two or more features other than stabilizing its entire mass on one single feature or able to settle between features

  12. Investigation of the biofouling properties of several algae on different textured chemical modified silicone surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jihai [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Wenjie, E-mail: zhaowj@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Peng, Shusen; Zeng, Zhixiang; Zhang, Xin [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Wu, Xuedong, E-mail: xdwu@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Xue, Qunji [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2014-08-30

    Highlights: • Engineered pillars, pits and grooves spaced 3–12 μm apart were fabricated on siloxane modified acrylic resin films. • The effect of feature size, geometry, and wettability on the settlement of different algae was evaluated. • The feature size and geometry displayed a substantial correlation with the antifouling properties. • A comparatively physical fouling deterrent mechanism was analyzed. - Abstract: Engineered pillars, pits and grooves spaced 3, 6, 9 and 12 μm apart were fabricated on siloxane modified acrylic resin films. The effect of feature size, geometry, and wettability on the settlement of different algae was evaluated. These films showed various antifouling performances to Ulothrix, Closterium and Navicula. For Navicula (length: 10–12 μm), the feature size and geometry displayed a substantial correlation with the antifouling properties. The film with pillars spaced 3 μm reduced Navicula settlement by 73% compared to the control surface. For Closterium (length: 45–55 μm), their responses were governed by the same underlying thermodynamic principles as wettability, the largest reduction in Closterium, 81%, was obtained on the surface with grooves spaced 12 μm apart. For Ulothrix (length: 5–8 mm), the surface also showed the best antifouling performance, the reduction ratio of the settlement on the surface with grooves spaced 12 μm apart could even reach 92%. At last, physical fouling deterrent mechanisms for the films with various textures were analyzed in detail. The feature size and geometry display a substantial correlation with the antifouling properties when the size of fouling algae is close to the textures. With the increasing size for algae, antifouling performance was getting better on surface with pillars or grooves because the algae are bridged between two or more features other than stabilizing its entire mass on one single feature or able to settle between features.

  13. Peptides from milk proteins and their properties.

    Science.gov (United States)

    Kilara, Arun; Panyam, Dinakar

    2003-01-01

    This review has attempted to study the literature pertaining to peptides derived from milk proteins. Hydrolysis of milk proteins to generate peptides has been practiced for a long time and it was recognized early on in this process that the taste of hydrolyzates might hinder use of these products in food formulations. Modification of protein is necessary to form a more acceptable or utilizable product, to form a product that is less susceptible to deteriorative reactions and to form a product that is of higher nutritionall quality. Modifications may be achieved by a number of chemical and enzymatic means. This review has considered only enzymatic modification of dairy proteins. Modified proteins contain peptides and some of these peptides have been purified and their functionalities have been compared with unmodified proteins. This paper has examined the literature pertaining to improvement in functionality of enzyme-modified proteins. Improvements in solubility, emulsification, foaming and gelation were examined. There is limited information available on the sequence of the peptides necessary to improve the functional characteristics of proteins. Knowing the sequences of desirable functional peptides can lead to genetic alteration of proteins to improve functionality. Addition of synthetic peptides to intact proteins may be another way in which the functionality of proteins can be augmented. Some of the peptides in milk proteins are capable of affecting biological functions of an organism. These effects can be antimicrobial and probiotic, i.e., prevent the growth and proliferation of undesirable and pathogenic organisms, or they may promote the growth of desirable bacteria in the digestive tract of humans and animals. Peptides derived from milk protein have been shown to exert digestive and metabolic effects as well. They may also influence the immune system. These biological effects may play an important role in the development of medical foods that treat or

  14. Edge Effects on the Electronic Structures of Chemically Modified Armchair Graphene Nanoribbons

    OpenAIRE

    Ren, Hao; Li, Qunxiang; Su, Haibin; Shi, Q. W.; Chen, Jie; Yang, Jinlong

    2007-01-01

    In this paper, we apply the first-principle theory to explore how the electronic structures of armchair graphene nanoribbons (AGNRs) are affected by chemical modifications. The edge addends include H, F, N, NH$_{2}$, and NO$_{2}$. Our theoretical results show that the energy gaps are highly tunable by controlling the widths of AGNRs and addends. The most interesting finding is that N-passivated AGNRs with various widths are metallic due to the unique electronic features of N-N bonds. This pro...

  15. Modified CTAB and TRIzol protocols improve RNA extraction from chemically complex Embryophyta 1

    OpenAIRE

    Jordon-Thaden, Ingrid E.; Chanderbali, Andre S; Gitzendanner, Matthew A.; Soltis, Douglas E.

    2015-01-01

    Premise of the study: Here we present a series of protocols for RNA extraction across a diverse array of plants; we focus on woody, aromatic, aquatic, and other chemically complex taxa. Methods and Results: Ninety-one taxa were subjected to RNA extraction with three methods presented here: (1) TRIzol/TURBO DNA-free kits using the manufacturer’s protocol with the addition of sarkosyl; (2) a combination method using cetyltrimethylammonium bromide (CTAB) and TRIzol/sarkosyl/TURBO DNA-free; and (...

  16. In Vivo Screening of Chemically Modified RNA duplexes for their Ability to Induce Innate Immune Responses

    DEFF Research Database (Denmark)

    Schyth, Brian Dall; Bramsen, Jesper Bertram; Kjems, Jørgen; Wengel, Jesper; Lorenzen, Niels

    Due to their sequence specific gene targeting activity siRNAs are regarded as promising active compounds in gene medicine. But one serious problem with delivering siRNAs as treatment is the now well-established non-specific activities of some RNA duplexes. Cellular reactions towards double stranded...... protection against a fish pathogenic virus. This protection corresponded with an interferon response in the fish. Here we use this fish model to screen siRNAs containing various chemical modifications of the RNA backbone for their antiviral activity, the overall aim being identification of an siRNA form with...

  17. Helleborus purpurascens—Amino Acid and Peptide Analysis Linked to the Chemical and Antiproliferative Properties of the Extracted Compounds

    Directory of Open Access Journals (Sweden)

    Adina-Elena Segneanu

    2015-12-01

    Full Text Available There is a strong drive worldwide to discover and exploit the therapeutic potential of a large variety of plants. In this work, an alcoholic extract of Helleborus purpurascens (family Ranunculaceae was investigated for the identification of amino acids and peptides with putative antiproliferative effects. In our work, a separation strategy was developed using solvents of different polarity in order to obtain active compounds. Biochemical components were characterized through spectroscopic (mass spectroscopy and chromatographic techniques (RP-HPLC and GC-MS. The biological activity of the obtained fractions was investigated in terms of their antiproliferative effects on HeLa cells. Through this study, we report an efficient separation of bioactive compounds (amino acids and peptides from a plant extract dependent on solvent polarity, affording fractions with unaffected antiproliferative activities. Moreover, the two biologically tested fractions exerted a major antiproliferative effect, thereby suggesting potential anticancer therapeutic activity.

  18. Modifying the effects of fast neutrons in rice seeds by post-treatment with chemical mutagens

    International Nuclear Information System (INIS)

    Dormant rice seeds were exposed to 290-1160 rad of neutrons, dehulled and then soaked in buffered aqueous solutions of either 0.03M EMS or 0.005M MMS for 15h at 30 deg. C. The neutron plus EMS treatment did not affect seedling height and seedset as much as did the neutron plus MMS treatment, which caused marked reductions over those due to neutrons alone. The mutation frequency (Msp) in all neutron doses was slightly to markedly increased by EMS, and reduced by MMS. Neutrons + EMS was found to be an efficient mutagenic combination whereas neutrons + MMS was inefficient (Msp/I). Differences in the synergistic effects of these combined treatments may be due to the specific biological action of the chemicals as determined by their physical properties. An idea that the chemicals may have acted essentially as selective factors for survival of neutron-damage or mutated tiller initials is briefly discussed. (author). 26 refs, 3 tabs

  19. Synergetic Targeted Delivery of Sleeping-Beauty Transposon System to Mesenchymal Stem Cells Using LPD Nanoparticles Modified with a Phage-Displayed Targeting Peptide.

    Science.gov (United States)

    Ma, Kun; Wang, Dong-Dong; Lin, Yiyang; Wang, Jianglin; Petrenko, Valery; Mao, Chuanbin

    2013-03-01

    An important criterion for effective gene therapy is sufficient chromosomal integration activity. The Sleeping Beauty (SB) transposon system is a plasmid system allowing efficient insertion of transgenes into the host genome. However, such efficient insertion occurs only after the system is delivered to nuclei. Since transposons do not have the transducing abilities of viral vectors, efficient delivery of this system first into cells and then into cell nuclei is still a challenge. Here, a phage display technique using a major coat displayed phage library is employed to identify a peptide (VTAMEPGQ) that can home to rat mesenchymal stem cells (rMSCs). A nanoparticle, called liposome protamine/DNA lipoplex (LPD), is electrostatically assembled from cationic liposomes and an anionic complex of protamine, DNA and targeting peptides. Various peptides are enveloped inside the LPD to improve its targeting capability for rMSCs and nuclei. The rMSC-targeting peptide and nuclear localization signal (NLS) peptide can execute the synergetic effect to promote transfection action of LPD. The homing peptide directs the LPD to target the MSCs, whereas the NLS peptide directs transposon to accumulate into nuclei once LPD is internalized inside the cells, leading to increased gene expression. This suggests that rMSC-targeting peptide and NLS peptide within LPD can target to rMSCs and then guide transposon into nuclei. After entering the nuclei, SB transposon increase the insertion rates into cellular chromosomes. The targeting LPD does not show obvious cell toxicity and influence on the differentiation potential of rMSCs. Therefore, the integration of SB transposon and LPD system is a promising nonviral gene delivery vector in stem cell therapy. PMID:23885226

  20. Amperometric biosensors for detection of phenol using chemically modified electrodes containing immobilized bacteria.

    Science.gov (United States)

    Skládal, Petr; Morozova, Natalya O; Reshetilov, Anatoly N

    2002-10-01

    Eight strains of Pseudomonas were studied for development of phenol sensor. The immobilization of cells was performed by absorbing them on the working part of mediator-modified screen-printed electrodes (SPEs). Only three Pseudomonas strains were able to transfer electrons resulting from specific oxidation of phenol to the electrode by means of mediators; ferrocene, duroquinone and dimethyferrocene were successfully used with the strains 394 (p20), 74-III and 83-IV (working names), respectively. The lower limits for detection of phenol were 1 micro M for the strain 74-III and 10 micro M for the strain 83-IV and 394 (p20). Calibrations were obtained as the dependencies of logarithm of current changes (log deltaI) on logarithm of concentration (logC), log delta I vs. logC. Among all substrates tested (phenol, catechol, hydroquinone, ethanol, methanol, propanol, isopropanol, isobutanol, isoamylalcohol, acetate, glucose, xylose, vanillin, 2,4,6-trichlorphenol, 2,3,6-trichlorphenol, 4-hydroxy-3-methoxybenzoic acid, coumarin, pentafluorophenol), bacterial sensor demonstrated a good selectivity with respect to phenol and lower responses to catechol and hydroquinone (10-times lower). The dependence of signals on operating conditions was studied. The biosensor should be used during the day of preparation. The operational stability was satisfactory to perform up to 10 consecutive measurements. Low cost and very simple manufacturing procedure allow for bacterial sensor to be applied as disposable devices. PMID:12243905

  1. NOx Direct Decomposition: Potentially Enhanced Thermodynamics and Kinetics on Chemically Modified Ferroelectric Surfaces

    Science.gov (United States)

    Kakekhani, Arvin; Ismail-Beigi, Sohrab

    2014-03-01

    NOx are regulated pollutants produced during automotive combustion. As part of an effort to design catalysts for NOx decomposition that operate in oxygen rich environment and permit greater fuel efficiency, we study chemistry of NOx on (001) ferroelectric surfaces. Changing the polarization at such surfaces modifies electronic properties and leads to switchable surface chemistry. Using first principles theory, our previous work has shown that addition of catalytic RuO2 monolayer on ferroelectric PbTiO3 surface makes direct decomposition of NO thermodynamically favorable for one polarization. Furthermore, the usual problem of blockage of catalytic sites by strong oxygen binding is overcome by flipping polarization that helps desorb the oxygen. We describe a thermodynamic cycle for direct NO decomposition followed by desorption of N2 and O2. We provide energy barriers and transition states for key steps of the cycle as well as describing their dependence on polarization direction. We end by pointing out how a switchable order parameter of substrate,in this case ferroelectric polarization, allows us to break away from some standard compromises for catalyst design(e.g. the Sabatier principle). This enlarges the set of potentially catalytic metals. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

  2. Investigation of the biofouling properties of several algae on different textured chemical modified silicone surfaces

    Science.gov (United States)

    Xu, Jihai; Zhao, Wenjie; Peng, Shusen; Zeng, Zhixiang; Zhang, Xin; Wu, Xuedong; Xue, Qunji

    2014-08-01

    Engineered pillars, pits and grooves spaced 3, 6, 9 and 12 μm apart were fabricated on siloxane modified acrylic resin films. The effect of feature size, geometry, and wettability on the settlement of different algae was evaluated. These films showed various antifouling performances to Ulothrix, Closterium and Navicula. For Navicula (length: 10-12 μm), the feature size and geometry displayed a substantial correlation with the antifouling properties. The film with pillars spaced 3 μm reduced Navicula settlement by 73% compared to the control surface. For Closterium (length: 45-55 μm), their responses were governed by the same underlying thermodynamic principles as wettability, the largest reduction in Closterium, 81%, was obtained on the surface with grooves spaced 12 μm apart. For Ulothrix (length: 5-8 mm), the surface also showed the best antifouling performance, the reduction ratio of the settlement on the surface with grooves spaced 12 μm apart could even reach 92%. At last, physical fouling deterrent mechanisms for the films with various textures were analyzed in detail. The feature size and geometry display a substantial correlation with the antifouling properties when the size of fouling algae is close to the textures. With the increasing size for algae, antifouling performance was getting better on surface with pillars or grooves because the algae are bridged between two or more features other than stabilizing its entire mass on one single feature or able to settle between features.

  3. Chemically modified glasses for analysis of hydrogen isotopes by gas chromatography

    International Nuclear Information System (INIS)

    An extensive experimental research has been carried out by gas chromatographic runs in order to identify the most suitable adsorbents and define the best operated conditions for selective separation and analysis of hydrogen isotopes in near real-time (i.e. less than 10 min.). Preparation and operation procedures of chromatographic column for hydrogen isotope separation have been examined. This is one of the main requirements of the tritium separation from heavy water of CANDU reactor and of the tritium fuel cycle in D-T fusion reactors. This paper describes the preparation of absorbent materials utilised as stationary phase in the gas-chromatographic column for hydrogen isotope separation and treatment (activation) of stationary phase. Modified thermoresisting glass with Fe(NH4)2(SO4)2 6H2O and Cr2O3, respectively, have been experimentally investigated at 77 K for H2, HD, and D2 separation and the results of chromatographic runs are also reported and discussed. The hydrogen operating conditions of the adsorbent column Fe (III)/glass and Cr2O3/glass, i.e. granulometry, column length, pressure-drop along the column, carrier gas flow rate, sample volume have been study by means of the analysis of the retention times, separation factors and HETP. (authors)

  4. Radiation-chemical solidification of compositions based on modified epoxide resins

    International Nuclear Information System (INIS)

    Possibilites of obtaining radiation-solidified compositions on the base of EhD-20 epoxide resin where the greatest part of epoxide groups is replaced by methacrylates, are studied. Coatings on the base of epoxide groups have been solidified with γ-rays and accelerated electrons in the atmosphere of the inert gas (electron energy 600 keV, radiation intensity 9.8 Mrad/min). It is shown that dimethylaminoethylmethacrylate is a catalyst of radiation solidification. Its optimum quantity in compositions is 5%. The dose neccessary for solidification decreases considerably (from 5-7 Mrad to 2 Mrad) and gel fraction maximum content increases. Physical and chemical properties of the above coating on the metal are investigated

  5. 经穿膜肽与PEG修饰的核糖体失活蛋白Gelonin抗肿瘤作用的研究%Study on cell-penetrating peptide modified and PEGylated ribosome inactive protein Gelonin

    Institute of Scientific and Technical Information of China (English)

    张娅洁; 王慧媛; 陈应之; 汤懿斯; 杨志民; 黄永焯

    2015-01-01

    Objective:To improve anti-tumor effect of Gelonin, the plant-sourced RIP is modified by chemically conjugating a cell-penetrating peptide and polyethylene glycol (PEG). Methods:Purified protein was obtained after being performed on FPLC (fast protein liquid chromatography) Superdex75 column. Cytotoxicity was detected by MTT assay. The cellular uptake by HT1080 cells was studied by using inverted fluorescence microscopy and flow cytometry. In-vivo imaging technology was utilized for investigation of the in-vivo drug distribution in the HT1080 tumor-bearing mice. Results:The modified product was purified by using gel filtration chromatergraphy. Moreover, compared with native Gelonin, the cytotoxicity of modified protein was increased, especially in HT1080, presumably due to the enhanced cellular uptake. The in-vivo imaging results suggested that drug accumulation in tumor was improved by PEGylation. Conclusion:Modified Gelonin can improve cell penetration and cytotoxicity in tumor cells. PEGylation can increase tumor accumulation of the protein drug, and thereby enhance its anti-tumor effect.%目的:通过对核糖体失活蛋白Gelonin进行化学修饰,利用穿膜肽和聚乙二醇(PEG)偶联来提高其到达肿瘤部位和进入肿瘤细胞的能力,使Gelonin更高效地发挥抑瘤作用. 方法:利用FPLC Superdex75分子筛预装柱纯化系统对所修饰的Gelonin进行纯化后,在不同细胞系测试细胞毒性;通过倒置荧光显微镜、流式细胞分析技术等对药物进入纤维肉瘤细胞HT1080的能力进行评价;采用小动物活体成像技术考察药物体系在荷瘤动物体内的分布情况. 结果:采用分子筛色谱纯化可以得到纯度相对较高的修饰产物,其毒性较无修饰的Gelonin强,且在HT1080细胞系作用最明显;细胞摄取结果显示,与未修饰的Gelonin相比,该药物体系具有更高的细胞摄取效率;动物成像结果表明,PEG5000修饰可以改变Gelonin在动物体内的分布情况,

  6. The photosensitivity and ultraviolet absorption change of Sn-doped silica film fabricated by modified chemical vapor deposition

    International Nuclear Information System (INIS)

    10.5 μm thick Sn-doped silica films were prepared by the modified chemical vapor deposition followed by the solution-doping method. The films were exposed to 248 and 266 nm laser light, respectively. Positive refractive index change up to 2x10-4 at 1550 nm was observed by measuring the reflectivity based on Fresnel formulas. The data of UV absorption spectra suggest that the photosensitivity of the Sn-doped silica film under high energy density laser irradiation should be mainly due to the bond breaking of oxygen deficient defects, while under relatively low energy density laser irradiation, the refractive index change probably originates from photoconversion of optically active defects

  7. Applicability of vacuum impregnation to modify physico-chemical, sensory and nutritive characteristics of plant origin products--a review.

    Science.gov (United States)

    Radziejewska-Kubzdela, Elżbieta; Biegańska-Marecik, Róża; Kidoń, Marcin

    2014-01-01

    Vacuum impregnation is a non-destructive method of introducing a solution with a specific composition to the porous matrices of fruit and vegetables. Mass transfer in this process is a result of mechanically induced differences in pressure. Vacuum impregnation makes it possible to fill large volumes of intercellular spaces in tissues of fruit and vegetables, thus modifying physico-chemical properties and sensory attributes of products. This method may be used, e.g., to reduce pH and water activity of the product, change its thermal properties, improve texture, color, taste and aroma. Additionally, bioactive compounds may be introduced together with impregnating solutions, thus improving health-promoting properties of the product or facilitating production of functional food. PMID:25244012

  8. Applicability of Vacuum Impregnation to Modify Physico-Chemical, Sensory and Nutritive Characteristics of Plant Origin Products—A Review

    Directory of Open Access Journals (Sweden)

    Elżbieta Radziejewska-Kubzdela

    2014-09-01

    Full Text Available Vacuum impregnation is a non-destructive method of introducing a solution with a specific composition to the porous matrices of fruit and vegetables. Mass transfer in this process is a result of mechanically induced differences in pressure. Vacuum impregnation makes it possible to fill large volumes of intercellular spaces in tissues of fruit and vegetables, thus modifying physico-chemical properties and sensory attributes of products. This method may be used, e.g., to reduce pH and water activity of the product, change its thermal properties, improve texture, color, taste and aroma. Additionally, bioactive compounds may be introduced together with impregnating solutions, thus improving health-promoting properties of the product or facilitating production of functional food.

  9. Interaction of plasma-generated water cluster ions with chemically-modified Si surfaces investigated by infrared absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    Ayumi Hirano-Iwata

    2016-03-01

    Full Text Available We have investigated the interaction of water cluster ions generated by discharge plasma, with chemically modified Si surfaces using infrared absorption spectroscopy in the multiple internal reflection geometry. We observe that water cluster ions readily adsorb on SiO2-covered Si surfaces to form water droplets. We demonstrate that positively- and negatively-charged cluster ions adsorb on the SiO2-covered Si surface in different manners, indicating ionic interaction of the water droplets with the negatively-charged SiO2 surface. Water droplets formed on the protein-coated surface rupture the amide bond of the proteins, suggesting the function of protein decomposition of water cluster ions.

  10. Effect of chemically converted graphene as an electrode interfacial modifier on device-performances of inverted organic photovoltaic cells

    International Nuclear Information System (INIS)

    This study examined the effects of chemically converted graphene (CCG) materials as a metal electrode interfacial modifier on device-performances of inverted organic photovoltaic cells (OPVs). As CCG materials for interfacial layers, a conventional graphene oxide (GO) and reduced graphene oxide (rGO) were prepared, and their functions on OPV-performances were compared. The inverted OPVs with CCG materials showed all improved cell-efficiencies compared with the OPVs with no metal/bulk-heterojunction (BHJ) interlayers. In particular, the inverted OPVs with reduction form of GO showed better device-performances than those with GO and better device-stability than poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)-based inverted solar cells, showing that the rGO can be more desirable as a metal/BHJ interfacial material for fabricating inverted-configuration OPVs. (paper)

  11. Surface charge, electroosmotic flow and DNA extension in chemically modified thermoplastic nanoslits and nanochannels.

    Science.gov (United States)

    Uba, Franklin I; Pullagurla, Swathi R; Sirasunthorn, Nichanun; Wu, Jiahao; Park, Sunggook; Chantiwas, Rattikan; Cho, Yoon-Kyoung; Shin, Heungjoo; Soper, Steven A

    2015-01-01

    Thermoplastics have become attractive alternatives to glass/quartz for microfluidics, but the realization of thermoplastic nanofluidic devices has been slow in spite of the rather simple fabrication techniques that can be used to produce these devices. This slow transition has in part been attributed to insufficient understanding of surface charge effects on the transport properties of single molecules through thermoplastic nanochannels. We report the surface modification of thermoplastic nanochannels and an assessment of the associated surface charge density, zeta potential and electroosmotic flow (EOF). Mixed-scale fluidic networks were fabricated in poly(methylmethacrylate), PMMA. Oxygen plasma was used to generate surface-confined carboxylic acids with devices assembled using low temperature fusion bonding. Amination of the carboxylated surfaces using ethylenediamine (EDA) was accomplished via EDC coupling. XPS and ATR-FTIR revealed the presence of carboxyl and amine groups on the appropriately prepared surfaces. A modified conductance equation for nanochannels was developed to determine their surface conductance and was found to be in good agreement with our experimental results. The measured surface charge density and zeta potential of these devices were lower than glass nanofluidic devices and dependent on the surface modification adopted, as well as the size of the channel. This property, coupled to an apparent increase in fluid viscosity due to nanoconfinement, contributed to the suppression of the EOF in PMMA nanofluidic devices by an order of magnitude compared to the micro-scale devices. Carboxylated PMMA nanochannels were efficient for the transport and elongation of λ-DNA while these same DNA molecules were unable to translocate through aminated nanochannels. PMID:25369728

  12. Characterization of Heme-DNA Complexes Composed of Some Chemically Modified Hemes and Parallel G-Quadruplex DNAs.

    Science.gov (United States)

    Yamamoto, Yasuhiko; Kinoshita, Masashi; Katahira, Yuya; Shimizu, Haruna; Di, Yue; Shibata, Tomokazu; Tai, Hulin; Suzuki, Akihiro; Neya, Saburo

    2015-12-15

    Heme {Fe(II)- or Fe(III)-protoporphyrin IX complex [heme(Fe(2+)) or heme(Fe(3+)), respectively]} binds selectively to the 3'-terminal G-quartet of a parallel G-quadruplex DNA formed from a single repeat sequence of the human telomere, d(TTAGGG), through a π-π stacking interaction between the porphyrin moiety of the heme and the G-quartet. The binding affinities of some chemically modified hemes(Fe(3+)) for DNA and the structures of complexes between the modified hemes(Fe(2+)) and DNA, with carbon monoxide (CO) coordinated to the heme Fe atom on the side of the heme opposite the G6 G-quartet, have been characterized to elucidate the interaction between the heme and G-quartet in the complexes through analysis of the effects of the heme modification on the structural properties of the complex. The study revealed that the binding affinities and structures of the complexes were barely affected by the heme modification performed in the study. Such plasticity in the binding of heme to the G-quartet is useful for the versatile design of the complex through heme chemical modification and DNA sequence alteration. Furthermore, exchangeable proton signals exhibiting two-proton intensity were observed at approximately -3.5 ppm in the (1)H nuclear magnetic resonance (NMR) spectra of the CO adducts of the complexes. Through analysis of the NMR results, together with theoretical consideration, we concluded that the heme(Fe(2+)) axial ligand trans to CO in the complex is a water molecule (H2O). Identification of the Fe-bound H2O accommodated between the heme and G-quartet planes in the complex provides new insights into the structure-function relationship of the complex. PMID:26595799

  13. Fabrication and characterization of indium sulfide thin films deposited on SAMs modified substrates surfaces by chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Meng Xu [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou, 730050 (China); Lu Yongjuan; Zhang Xiaoliang [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Graduate School of Chinese Academy of Sciences, Beijing, 10049 (China); Yang Baoping [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou, 730050 (China); Yi Gewen [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Jia Junhong, E-mail: jhjia@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

    2011-11-01

    In an effort to explore the optoelectronic properties of nanostructured indium sulfide (In{sub 2}S{sub 3}) thin films for a wide range of applications, the In{sub 2}S{sub 3} thin films were successfully deposited on the APTS layers (-NH{sub 2}-terminated) modified ITO glass substrates using the chemical bath deposition technique. The surface morphology, structure and composition of the resultant In{sub 2}S{sub 3} thin films were characterized by FESEM, XRD, and XPS, respectively. Also, the correlations between the optical properties, photocurrent response and the thickness of thin films were established. According to the different deposition mechanisms on the varying SAMs terminational groups, the positive and negative micropatterned In{sub 2}S{sub 3} thin films were successfully fabricated on modified Si substrates surface combining with the ultraviolet lithography process. This offers an attractive opportunity to fabricate patterned In{sub 2}S{sub 3} thin films for controlling the spatial positioning of functional materials in microsystems.

  14. A reagentless enzymatic fluorescent biosensor for glucose based on upconverting glasses, as excitation source, and chemically modified glucose oxidase.

    Science.gov (United States)

    Del Barrio, Melisa; Cases, Rafael; Cebolla, Vicente; Hirsch, Thomas; de Marcos, Susana; Wilhelm, Stefan; Galbán, Javier

    2016-11-01

    Upon near-infrared excitation Tm(3+)+Yb(3+) doped fluorohafnate glasses present upconversion properties and emit visible light. This property permits to use these glasses (UCG) as excitation sources for fluorescent optical biosensors. Taking this into account, in this work a fluorescent biosensor for glucose determination is designed and evaluated. The biosensor combines the UCG and the fluorescence of the enzyme glucose oxidase chemically modified with a fluorescein derivative (GOx-FS), whose intensity is modified during the enzymatic reaction with glucose. Optical parameters have been optimized and a mathematical model describing the behavior of the analytical signal is suggested. Working in FIA mode, the biosensor responds to glucose concentrations up to, at least, 15mM with a limit of detection of 1.9mM. The biosensor has a minimum lifetime of 9 days and has been applied to glucose determination in drinks. The applicability of the sensor was tested by glucose determination in two fruit juices. PMID:27591654

  15. Efficient acetone-butanol-ethanol production (ABE) by Clostridium acetobutylicum XY16 immobilized on chemically modified sugarcane bagasse.

    Science.gov (United States)

    Kong, Xiangping; He, Aiyong; Zhao, Jie; Wu, Hao; Jiang, Min

    2015-07-01

    Sugarcane bagasse was chemically modified by polyethylenimine (PEI) and glutaraldehyde (GA) and then used as a support to immobilize Clostridium acetobutylicum XY16 in the process of butanol production. Compared with batch fermentation using unmodified sugarcane bagasse, 22.3 g/L total solvents were produced by cells immobilized on 4 g/L PEI treated sugarcane bagasse with high solvent productivity of 0.62 g/(L h) and glucose consumption rate of 1.67 g/(L h). Improvement of 14, 43, and 37 % in total solvent titer, solvent productivity and glucose consumption rate was observed, respectively. Enhanced solvent production of 25.14 g/L was obtained when using a high concentration of glucose of 80 g/L. Continuous fermentation was studied using PEI/GA modified sugarcane bagasse as immobilization support with a range of dilution which rates from 0.2 to 2.5 to find an optimal condition. The maximum solvent productivity of 11.32 g/(L h) was obtained at a high dilution rate of 2.0 h(-1). PMID:25694132

  16. Development of Green Solvent Modified Zeolite (GSMZ) for the Removal of Chemical Contaminants and Pathogens from Water

    Science.gov (United States)

    Li, Z.; Stapleton, E. R.; Xu, S.

    2012-12-01

    Sorption represents an important strategy in the remediation of groundwater contamination. As a naturally-occurring mineral with large cation exchange capacity, zeolite is negatively charged and has been widely used as an inexpensive and effective sorbent for the removal of positively charged contaminants such as heavy metals from water. The negative charges of zeolite, however, make it generally ineffective in the sorption of anionic contaminants such as chromate and arsenate as well as many pathogens. In this research, we used the imidazolium group of chemicals, which are considered as "green solvents" and differ from the surfactants used in previous studies, to modify zeolite. Both batch and column experiments were performed to evaluate the effectiveness of GSMZ in the removal of representative anionic pollutant (i.e., Cr) and bacterium (i.e., Eschericha coli) under various water chemistry conditions. Our experimental results showed that the adsorption of Cr on GSMZ was fast (equilibrium was reached within ~5 min) and the capacity of GSMZ to remove chromate (>1000 mg/kg) was ~100% higher than surfactant modified zeolite (SMZ). GSMZ was also found to be very effective in the removal of E. coli. As pH was found to have minimal effects on the adsorption of chromium on GSMZ, higher ionic strength could lower the adsorption capacity of chromium by GSMZ.

  17. Introduction to Peptide Synthesis

    OpenAIRE

    Stawikowski, Maciej; Fields, Gregg B.

    2002-01-01

    A number of synthetic peptides are significant commercial or pharmaceutical products, ranging from the dipeptide sugar-substitute aspartame to clinically used hormones, such as oxytocin, adrenocorticotropic hormone, and calcitonin. This unit provides an overview of the field of synthetic peptides and proteins. It discusses selecting the solid support and common coupling reagents. Additional information is provided regarding common side reactions and synthesizing modified residues.

  18. Biomimetic Deposition of Apatite on Surface Chemically Modified Porous NiTi Shapememory Alloy

    Science.gov (United States)

    Wu, S. L.; Liu, X. M.; Chung, C. Y.; Chu, Paul K.; Chan, Y. L.; Yeung, K. W. K.; Chu, C. L.

    Porous NiTi shape memory alloy (SMA) with 48% porosity and an average pore size of 50-800 μm was synthesized by capsule-free hot isostatic pressing (CF-HIP). To enhance the surface bioactivity, the porous NiTi SMA was subjected to H2O2 and subsequent NaOH treatment. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses revealed that a porous sodium titanate (Na2TiO3) film had formed on the surface of the porous NiTi SMA. An apatite layer was deposited on this film after immersion in simulated body fluid at 37°C, while no apatite could be found on the surface of the untreated porous NiTi SMA. The formation of the apatite layer infers that the bioactivity of the porous NiTi SMA may be enhanced by surface chemical treatment, which is favorable for its application as bone implants.

  19. Synthesis and Self-Assembly of Gold Nanoparticles by Chemically Modified Polyol Methods under Experimental Control

    International Nuclear Information System (INIS)

    In our present research, bottom-up self-assembly of gold (Au) nanoparticles on a flat copper (Cu) substrate is performed by a facile method. The very interesting evidence of self-assembly of Au nanoparticles on the top of the thin assembled layer was observed by scanning electron microscopy (SEM). We had discovered one of the most general and simple methods for the self-assembly of metal nanoparticles. The general physical and chemical mechanisms of the evaporation process of the solvents can be used for self-assembly of the as-prepared nanoparticles. The important roles of molecules of the used solvents are very critical to self-assembly of the as-prepared Au nanoparticles in the case without using any polymers for those processes. It is clear that self-assembly of such one nano system of the uniform Au nanoparticles is fully examined. Finally, an exciting surface plasmon resonance (SPR) phenomenon of the pure Au nanoparticles in the solvent was fully discovered in their exciting changes of the narrow and large SPR bands according to synthesis time. The SPR was considered as the collective oscillation of valence electrons of the surfaces of the pure Au nanoparticles in the solvent by incident ultraviolet-visible light. Then, the frequency of light photons matches the frequency of the oscillation of surface electrons of the Au nanoparticles that are excited.

  20. Field Deployable Chemical Redox Probe for Quantitative Characterization of Carboxymethylcellulose Modified Nano Zerovalent Iron.

    Science.gov (United States)

    Fan, Dimin; Chen, Shengwen; Johnson, Richard L; Tratnyek, Paul G

    2015-09-01

    Nano zerovalent iron synthesized with carboxymethylcelluose (CMC-nZVI) is among the leading formulations of nZVI currently used for in situ groundwater remediation. The main advantage of CMC-nZVI is that it forms stable suspensions, which are relatively mobile in porous media. Rapid contaminant reduction by CMC-nZVI is well documented, but the fate of the CMC-nZVI (including "aging" and "reductant demand") is not well characterized. Improved understanding of CMC-nZVI fate requires methods with greater specificity for Fe(0), less vulnerability to sampling/recovery artifacts, and more practical application in the field. These criteria can be met with a simple and specific colorimetric approach using indigo-5,5'-disulfonate (I2S) as a chemical redox probe (CRP). The measured stoichiometric ratio for reaction between I2S and nZVI is 1.45 ± 0.03, suggesting complete oxidation of nZVI to Fe(III) species. However, near pH 7, reduction of I2S is diagnostic for Fe(0), because aqueous Fe(II) reduces I2S much more slowly than Fe(0). At that pH, adding Fe(II) increased I2S reduction rates by Fe(0), consistent with depassivation of nZVI, but did not affect the stoichiometry. Using the I2S assay to quantify changes in the Fe(0) content of CMC-nZVI, the rate of Fe(0) oxidation by water was found to be orders of magnitude faster than previously reported values for other types of nZVI. PMID:26218836

  1. TREATMENT OF RADIOACTIVE WASTE SOLUTIONS CONTAINING CESIUM AND STRONTIUM BY CHEMICALLY MODIFIED ACTIVATED CARBON

    International Nuclear Information System (INIS)

    The aim of this study is to develop activated carbon prepared from peach stone shell as an adsorbent for Cs+ and Sr2+ ions from their aqueous waste solutions. In this respect, five samples of peach stone shell were investigated. The first four samples were prepared by immersing the samples in different concentrations of either ZnCl2 or KOH, individually, prior to heat treatment at 500oC. The fifth sample was prepared only by thermal treatment at 500oC.The physical and chemical characteristics of the prepared samples were carried out. A comparative study for the removal of Cs+ and Sr2+ ions from their aqueous waste solutions using the investigated samples have been carried out using batch experiments.The different parameters affecting adsorption process such as contact time and metal ion concentration were studied. The results obtained showed that the activated carbon prepared using ZnCl2 was more effective than the other investigated samples for adsorbing Cs+ and Sr2+ ions since the removal percentages reached 85% and 98% , respectively, while the activated carbon prepared using KOH was less effective for the removal of the same elements since the removal percentages reached 69% and 60%, respectively. In case of using physically activated carbon, the removal percentages reached 18% and 25% for Cs+ and Sr2+, respectively.From the obtained data, it can be concluded that the activated carbon prepared using ZnCl2 can be used as a good adsorbent for the removal of the investigated elements that may present in radioactive waste solutions before their discharge to the environment

  2. Phase Stability of Ce-Modified La2Zr2O7 Coatings and Chemical Compatibility with YSZ

    Science.gov (United States)

    Wu, Qiong; Ji, Xiaojuan; Peng, Haoran; Ren, Xianjing; Yu, Yueguang

    2016-04-01

    Ce-modified La2Zr2O7 powders, i.e., La2Zr2O7 (LZ), La2(Zr0.7Ce0.3)2O7 (LZ7C3), and La2(Zr0.3Ce0.7)2O7 (LZ3C7), were used to produce thermal barrier coatings by atmospheric plasma spray process. The chemical compatibility of the CeO2-doped La2Zr2O7 with the traditional YSZ was investigated in LZ-YSZ powder mixtures and LZ-YSZ bilayer coatings by x-ray diffraction and scanning electron microscope. The powder mixtures and coatings were aged at 1200 and 1300 °C for 100 h. The results showed that LZ and LZ7C3 presented single pyrochlore structure after the heat treatments at both 1200 and 1300 °C. For LZ3C7, however, fluorite structure was observed at 1300 °C, indicating a poor phase stability of LZ3C7 at the elevated temperature. The results further showed that La2(Zr0.3Ce0.7)2O7 reacted with YSZ in the bilayer ceramic coatings due to the diffusion of cerium, zirconium, and yttrium. While for La2Zr2O7(LZ) and La2(Zr0.7Ce0.3)2O7, a better chemical compatibility with YSZ was shown.

  3. A chemically modified [alpha]-amylase with a molten-globule state has entropically driven enhanced thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, Khawar Sohail; Poljak, Anne; De Francisci, Davide; Guerriero, Gea; Pilak, Oliver; Burg, Dominic; Raftery, Mark J.; Parkin, Don M.; Trewhella, Jill; Cavicchioli, Ricardo (Sydney); (New South)

    2010-11-15

    The thermostability properties of TAA were investigated by chemically modifying carboxyl groups on the surface of the enzyme with AMEs. The TAA{sub MOD} exhibited a 200% improvement in starch-hydrolyzing productivity at 60 C. By studying the kinetic, thermodynamic and biophysical properties, we found that TAA{sub MOD} had formed a thermostable, MG state, in which the unfolding of the tertiary structure preceded that of the secondary structure by at least 20 C. The X-ray crystal structure of TAA{sub MOD} revealed no new permanent interactions (electrostatic or other) resulting from the modification. By deriving thermodynamic activation parameters of TAA{sub MOD}, we rationalised that thermostabilisation have been caused by a decrease in the entropy of the transition state, rather than being enthalpically driven. Far-UV CD shows that the origin of decreased entropy may have arisen from a higher helical content of TAA{sub MOD}. This study provides new insight into the intriguing properties of an MG state resulting from the chemical modification of TAA.

  4. Electron Transfer Reactivity Patterns at Chemically Modified Electrodes: Fundamentals and Application to the Optimization of Redox Recycling Amplification Systems

    Energy Technology Data Exchange (ETDEWEB)

    Adam Johan Bergren

    2006-05-01

    Electroanalytical chemistry is often utilized in chemical analysis and Fundamental studies. Important advances have been made in these areas since the advent of chemically modified electrodes: the coating of an electrode with a chemical film in order to impart desirable, and ideally, predictable properties. These procedures enable the exploitation of unique reactivity patterns. This dissertation presents studies that investigate novel reaction mechanisms at self-assembled monolayers on gold. In particular, a unique electrochemical current amplification scheme is detailed that relies on a selective electrode to enable a reactivity pattern that results in regeneration of the analyte (redox recycling). This regenerating reaction can occur up to 250 times for each analyte molecule, leading to a notable enhancement in the observed current. The requirements of electrode selectivity and the resulting amplification and detection limit improvements are described with respect to the heterogeneous and homogeneous electron transfer rates that characterize the system. These studies revealed that the heterogeneous electrolysis of the analyte should ideally be electrochemically reversible, while that for the regenerating agent should be held to a low level. Moreover, the homogeneous reaction that recycles the analyte should occur at a rapid rate. The physical selectivity mechanism is also detailed with respect to the properties of the electrode and redox probes utilized. It is shown that partitioning of the analyte into/onto the adlayer leads to the extraordinary selectivity of the alkanethiolate monolayer modified electrode. Collectively, these studies enable a thorough understanding of the complex electrode mechanism required for successful redox recycling amplification systems, Finally, in a separate (but related) study, the effect of the akyl chain length on the heterogeneous electron transfer behavior of solution-based redox probes is reported, where an odd-even oscillation

  5. A STUDY COMPARING CHEMICAL PEELING USING MODIFIED JESSNER'S SOLUTION AND 15%TRICHLOROACETIC ACID VERSUS 15% TRICHLOROACETIC ACID IN THE TREATMENT OF MELASMA

    OpenAIRE

    Safoury, Omar Soliman; Zaki, Nagla Mohamed; El Nabarawy, Eman Ahmad; Farag, Eman Abas

    2009-01-01

    Background: Melasma is a symmetric progressive hyperpigmentation of the facial skin that occurs in all races but has a predilection for darker skin phenotypes. Depigmenting agents, laser and chemical peeling as classic Jessner's solution, modified Jessner's solution and trichloroacetic acid have been used alone and in combination in the treatment of melasma. Objectives: The aim of the study was to compare the therapeutic effect of combined 15% Trichloroacetic acid (TCA) and modified Jessner's...

  6. Purification of labeled cyanogen bromide peptides of the alpha polypeptide from sodium ion and potassium ion activated adenosinetriphosphatase modified with N-[3H]ethylmaleimide

    International Nuclear Information System (INIS)

    Sodium ion and potassium ion activated adenosinetriphosphatase, isolated from canine kidney, was reacted with N-[3H]ethylmaleimide while it was poised in three different conformations, ostensibly E2-P, E2, and E1, respectively. These assignments were made from a consideration of the particular concentrations of ligands in the respective alkylation mixtures. After a 30-min reaction, the remaining enzymatic activity was found to vary among these three different samples from 90 to 30% of that of unalkylated controls. In all cases, the alpha polypeptide was purified and subjected to digestion with cyanogen bromide, and in each digest the same two distinct radioactive peptides were identified and purified by gel filtration on a column of Sephadex LH-60. The incorporation of N-[3H]ethylmaleimide into one of these two peptides correlated closely with enzymatic inactivation, while the incorporation into the other was most extensive when the portion of the active site to which ATP binds was unoccupied. Alkylation of the residue within the latter peptide, however, does not result in inactivation of the enzyme. Both peptides were further purified by high-pressure liquid chromatography, and their amino-terminal sequences were determined by manual dansyl Edman or solid-phase techniques. The peptide containing the sulfhydryl protected by ATP has, as its amino terminus, the lysine that reacts exclusively with fluoresceinyl 5'-isothiocyanate

  7. Purification of the labeled cyanogen bromide peptides of the α polypeptide from sodium and potassium ion-activated adenosinetriphosphatase modified with N-[3H]ethylmaleimide

    International Nuclear Information System (INIS)

    Sodium and potassium ion-activated adenosinetriphosphatase, isolated from canine kidney, was reacted with N-[3H]ethylmaleimide under three different conditions, defined by particular concentrations of ligands for the enzyme, such that after the same amount of time the remaining activity of then enzyme varied from 90% to 30%. The conformation of the enzyme also differed among the three conditions. In all cases, the α-polypeptide was purified and subjected to cyanogen bromide digestion. Two distinct, radioactive peptides were separated by gel filtration of the cyanogen bromide digest on a column of Sephadex LH-60 equilibrated with 95% ethanol: 88% formic acid:4:1. One of the radioactive peptides was shown to contain the sulfhydryl residue whose reaction with N-ethylmaleimide inactivates the enzyme. The other radioactive peptide contained a sulfhydryl residue that seems to react with N-ethylmaleimide only when the binding site for ATP is not occupied. Alkylation of this residue, however, does not result in inactivation of enzyme. Both peptides were purified further by high-pressure liquid chromatography, and their amino-terminal sequences were determined by the manual dansyl-Edman or solid-phase techniques. The peptide containing the sulfhydryl protected by ATP has, as its amino terminus, the lysine that reacts exclusively with fluorescein-5'-isothiocyanate

  8. Ultrasmall Peptides Self-Assemble into Diverse Nanostructures: Morphological Evaluation and Potential Implications

    Directory of Open Access Journals (Sweden)

    Charlotte A.E. Hauser

    2011-09-01

    Full Text Available In this study, we perform a morphological evaluation of the diverse nanostructures formed by varying concentration and amino acid sequence of a unique class of ultrasmall self-assembling peptides. We modified these peptides by replacing the aliphatic amino acid at the C-aliphatic terminus with different aromatic amino acids. We tracked the effect of introducing aromatic residues on self-assembly and morphology of resulting nanostructures. Whereas aliphatic peptides formed long, helical fibers that entangle into meshes and entrap >99.9% water, the modified peptides contrastingly formed short, straight fibers with a flat morphology. No helical fibers were observed for the modified peptides. For the aliphatic peptides at low concentrations, different supramolecular assemblies such as hollow nanospheres and membrane blebs were found. Since the ultrasmall peptides are made of simple, aliphatic amino acids, considered to have existed in the primordial soup, study of these supramolecular assemblies could be relevant to understanding chemical evolution leading to the origin of life on Earth. In particular, we propose a variety of potential applications in bioengineering and nanotechnology for the diverse self-assembled nanostructures.

  9. Ultrasmall peptides self-assemble into diverse nanostructures: morphological evaluation and potential implications.

    Science.gov (United States)

    Lakshmanan, Anupama; Hauser, Charlotte A E

    2011-01-01

    In this study, we perform a morphological evaluation of the diverse nanostructures formed by varying concentration and amino acid sequence of a unique class of ultrasmall self-assembling peptides. We modified these peptides by replacing the aliphatic amino acid at the C-aliphatic terminus with different aromatic amino acids. We tracked the effect of introducing aromatic residues on self-assembly and morphology of resulting nanostructures. Whereas aliphatic peptides formed long, helical fibers that entangle into meshes and entrap >99.9% water, the modified peptides contrastingly formed short, straight fibers with a flat morphology. No helical fibers were observed for the modified peptides. For the aliphatic peptides at low concentrations, different supramolecular assemblies such as hollow nanospheres and membrane blebs were found. Since the ultrasmall peptides are made of simple, aliphatic amino acids, considered to have existed in the primordial soup, study of these supramolecular assemblies could be relevant to understanding chemical evolution leading to the origin of life on Earth. In particular, we propose a variety of potential applications in bioengineering and nanotechnology for the diverse self-assembled nanostructures. PMID:22016623

  10. TUMOR SELECTIVE DRUG DELIVERY BY NEUROTENSIN BRANCHED PEPTIDES

    Directory of Open Access Journals (Sweden)

    L. Depau

    2012-05-01

    Full Text Available Detection of new tumor-selective targets, which allow either cancer cell tracing or therapy, is a crucial issue in cancer research. Membrane receptors for endogenous peptides such as Neurotensin are over-expressed in many human cancers and could therefore be used as tumor-specific antigen, while peptide ligands might act as targeting agents. The development of peptides as drug has always been limited by their short half-life, due to degradation by peptidases and proteases. Chemical modification, which can stabilize the molecules, may modify peptide affinity or specificity. More- over, coupling of peptides to effector units for imaging or therapy, may interfere with biological activity. We demonstrated that peptide sequences, when synthesized in an oligo-branched form, be- come resistant to proteolysis and thank to their multimericity are more efficient than correspon- ding monomers in binding cellular antigens1. Moreover, the branched core allow coupling of effector units without affecting peptide activity. Drug-armed tetra-branched neurotensin peptides (NT4 were synthesized with different conjugation methods, resulting either in uncleavable adducts or drug-releasing molecules2-4. Recently we de- veloped DOPC liposomes filled with the cytotoxic drug Doxorubicin (Doxo and functionalized with NT4. Armed DOPC liposomes showed a clear advantage with respect to nude liposomes in drug internalization and their cytotoxicity is fourfold increased with respect to the same nude lipo- somes. Conjugation to NT4 switches drug internalization to a peptide-receptor mediated mechanism, which greatly increases drug selectivity and also might allow by-passing drug cell resistance. In vitro and in vivo results indicated that branched NT peptides are valuable tools for tumor selective targeting.

  11. Topical non-peptide antagonists of sensory neurotransmitters substance P and CGRP do not modify patch test and prick test reactions

    DEFF Research Database (Denmark)

    Wallengren, Joanna; Edvinsson, Lars

    2014-01-01

    Immunologic responses in the skin can be modulated by such neurotransmitters of sensory nerve fibers as substance P (SP) and calcitonin gene-related peptide (CGRP). The first-generation receptor antagonists were peptides with large molecules and had to be injected intracutaneously. The aim of this...... study was to examine the topical effects of non-peptide antagonists to substance P (aprepitant) and CGRP (telcagepant), respectively, on delayed and immediate reactions in the skin and on associated pruritus. A lipophilic formulation of aprepitant 5% and a hydrophilic formulation of telcagepant 1% were...... developed. Their effect on the skin barrier was measured in terms of transepidermal water loss (TEWL) while permeation was calculated using permeation coefficients. Patch tests in patients allergic to nickel and prick test reactions to histamine were used as models. None of the treatments increased TEWL...

  12. Orthogonal ring-closing alkyne and olefin metathesis for the synthesis of small GTPase-targeting bicyclic peptides.

    Science.gov (United States)

    Cromm, Philipp M; Schaubach, Sebastian; Spiegel, Jochen; Fürstner, Alois; Grossmann, Tom N; Waldmann, Herbert

    2016-01-01

    Bicyclic peptides are promising scaffolds for the development of inhibitors of biological targets that proved intractable by typical small molecules. So far, access to bioactive bicyclic peptide architectures is limited due to a lack of appropriate orthogonal ring-closing reactions. Here, we report chemically orthogonal ring-closing olefin (RCM) and alkyne metathesis (RCAM), which enable an efficient chemo- and regioselective synthesis of complex bicyclic peptide scaffolds with variable macrocycle geometries. We also demonstrate that the formed alkyne macrocycle can be functionalized subsequently. The orthogonal RCM/RCAM system was successfully used to evolve a monocyclic peptide inhibitor of the small GTPase Rab8 into a bicyclic ligand. This modified peptide shows the highest affinity for an activated Rab GTPase that has been reported so far. The RCM/RCAM-based formation of bicyclic peptides provides novel opportunities for the design of bioactive scaffolds suitable for the modulation of challenging protein targets. PMID:27075966

  13. Novel pharmaceutical composition of bradykinin potentiating penta peptide with beta-cyclodextrin: physical-chemical characterization and anti-hypertensive evaluation.

    Science.gov (United States)

    Denadai, Angelo M L; Ianzer, Danielle; Alcântara, Antônio Flávio de C; Santoro, Marcelo M; Santos, Cynthia F F; Lula, Ivana Silva; de Camargo, Antônio C M; Faljoni-Alario, Adelaide; dos Santos, Robson A S; Sinisterra, Rubén D

    2007-05-01

    This work describes chemical properties and anti-hypertensive activity of an oral pharmaceutical formulation obtained from the complexation of beta-cyclodextrin (beta-CD) with bradykinin potentiating penta peptide (BPP-5a) founded in the Bothrops jararaca poison. Physical chemistry characterizations were recorded in order to investigate the intermolecular interactions between species in complex. Circular dichroism data indicated conformational changes of BPP-5a upon complexation with beta-CD. ROESY and theoretical calculations showed a selective approximation of triptophan moiety into cavity of beta-CD. Isothermal titration calorimetry data indicated an exothermic formation of the complex, which is accomplished by reduction of entropy. The anti-hypertensive activity of the BPP-5a/beta-CD complex has been evaluated in spontaneous hypertensive rats, showing better results than pure BPP-5a. PMID:17196774

  14. Enhancement of uranium(VI) biosorption by chemically modified marine-derived mangrove endophytic fungus Fusarium sp. ZZF51

    International Nuclear Information System (INIS)

    Fusarium sp. ZZF51, mangrove endophytic fungus originated from South China Sea coast, was chemically modified by formaldehyde, methanol and acetic acid to enhance its affinity of uranium(VI) from waste water. The influencing factors about uranium(VI) adsorption such as contact time, solution pH, the ratio of solid/liquid (S/L) and initial uranium(VI) concentration were investigated, and the suitable adsorption isotherm and kinetic models were determined. In addition, the biosorption mechanism was also discussed by FTIR analysis. Experimental results show that the maximum biosorption capacity of formaldehyde-treated biomass for uranium(VI) at the optimized condition of pH 6.0, S/L 0.6 and equilibrium time 90 min is 318.04 mg g-1, and those of methanol-treated and HAc-treated biomass are 311.95 and 351.67 mg g-1 at the same pH and S/L values but different equilibrium time of 60 and 90 min, respectively. Thus the maximum biosorption capacity of the three kind of modified biomass have greatly surpassed that of the raw biomass (21.42 mg g-1). The study of kinetic exhibits a high level of compliance with the Lagergren's pseudo-second-order kinetic models. Langumir and Freundlich models have proved to be well able to explain the sorption equilibrium with the satisfactory correlation coefficients higher than 0.96. FTIR analysis reveals that the carboxyl, amino and hydroxyl groups on the cell wall of Fusarium sp. ZZF51 play an important role in uranium(VI) biosorption process. (author)

  15. Is the titer of adipokinetic peptides in colorado potato beetle (Leptinotarsa decemlineata) fed on genetically modified potatoes increased by oxidative stress?

    Czech Academy of Sciences Publication Activity Database

    Kodrík, Dalibor; Krishnan, N.; Habuštová, Oxana

    České Budějovice : Biology Centre of Academy of Sciences of the Czech Republic, 2009 - (Sehnal, F.; Drobník, J.), s. 64-64 ISBN 978-80-86668-05-3 Institutional research plan: CEZ:AV0Z50070508 Keywords : adipokinetic peptides Subject RIV: ED - Physiology

  16. The effect of different annealing temperatures on tin and cadmium telluride phases obtained by a modified chemical route

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Highlights: ► Synthesis of cadmium and tin telluride. ► Chemical route to obtain pure crystalline cadmium and tin telluride. ► Effect of the annealing temperature on the crystalline phases. ► Removal of tin oxide as side product through thermal treatment. -- Abstract: In this work tin and cadmium telluride were prepared by a modification of a chemical route reported in the literature to obtain metallacycles formed by oxidative addition of tin-tellurium bonds to platinum (II). Through this procedure it was possible to obtain tin and cadmium telluride. X-ray diffraction and X-ray photoelectron spectroscopy were used to identify the crystalline phases obtained as well as the presence of side products. In the case of tin telluride it was identified potassium chloride, metallic tellurium and tin oxide as contaminants. The tin oxidation states were also monitored by 119Sn Mössbauer spectroscopy. The annealing in hydrogen atmosphere was chosen as a strategy to reduce the tin oxide and promote its reaction with the excess of tellurium present in the medium. The evolution of this tin oxide phase was studied through the annealing of the sample at different temperatures. Cadmium telluride was obtained with high degree of purity (98.5% relative weight fraction) according to the Rietveld refinement of X-ray diffraction data. The modified procedure showed to be very effective to obtain amorphous tin and cadmium telluride and the annealing at 450 °C has proven to be useful to reduce the amount of oxide produced as side product.

  17. Enzymatic grafting of peptides from casein hydrolysate to chitosan. Potential for value-added byproducts from food-processing wastes.

    Science.gov (United States)

    Aberg, Christopher M; Chen, Tianhong; Olumide, Ayotunde; Raghavan, Srinivasa R; Payne, Gregory F

    2004-02-25

    Tyrosinase was used to initiate the grafting of peptides onto the amine-containing polysaccharide chitosan. Chemical evidence for covalent grafting was obtained from electrospray mass spectrometry for products formed from reactions with glucosamine (the monomeric unit of chitosan) and the model dipeptide Tyr-Ala. When this model dipeptide was incubated with tyrosinase and chitosan, there was a marked increase in the viscosity of the solution. This viscosity increase provides physical evidence that tyrosinase can initiate peptide grafting onto the chitosan backbone. A peptide-modified chitosan derivative was generated by reacting chitosan (0.32 w/v%) with acid-hydrolyzed casein (0.5 w/v %) using tyrosinase. After reaction, the peptide-modified chitosan was partially purified and dissolved in an aqueous acetic acid solution. Low concentrations of this peptide-modified chitosan were observed to confer viscoelastic properties to the solutions. Specifically they conferred high viscosities and shear thinning properties to the solutions, and solutions containing only 1 w/w % of the peptide-modified chitosan behaved as weak gels. Thus, tyrosinase provides a simple and safe way to convert food-processing byproducts into environmentally friendly products that offer useful functional properties. The selectivity of tyrosinase and the relatively high reactivity of chitosan's amines allow grafting to be performed with uncharacterized peptide mixtures present in crude hydrolysates. PMID:14969532

  18. Glassy carbon electrode modified with a graphene oxide/poly(o-phenylenediamine) composite for the chemical detection of hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Van Hoa [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of); Department of Chemistry, Nha Trang University, 2 Nguyen Dinh Chieu, Nha Trang (Viet Nam); Tran, Trung Hieu [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of); Shim, Jae-Jin, E-mail: jjshim@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of)

    2014-11-01

    Conducting poly(o-phenylenediamine) (POPD)/graphene oxide (GO) composites were prepared using a facile and efficient method involving the in-situ polymerization of OPD in the presence of GO in an aqueous medium. Copper sulfate was used as an oxidative initiator for the polymerization of OPD. Scanning electron microscopy and transmission electron microscopy images showed that POPD microfibrils were formed and distributed relatively uniformly with GO sheets in the obtained composites. X-ray diffraction results revealed the highly crystal structure of POPD. This composite exhibited good catalytic activity and stability. These results highlight the potential applications of POPD/GO composites as excellent electrochemical sensors. The composites were used to modify glass carbon electrodes for the chemical detection of hydrogen peroxide in aqueous media. - Highlights: • Graphene oxide/poly(o-phenylenediamine) composites were prepared efficiently. • POPD microfibrils were distributed relatively uniformly with GO sheets. • The composite exhibited good catalytic activity and stability for H{sub 2}O{sub 2} sensing.

  19. Physical characteristics of chemically modified starch from potatoes, evaluated by X-ray diffraction, SEM and NMR

    International Nuclear Information System (INIS)

    The aim of this study was to compare the physical characteristics of chemically modified starch by cross-linking and methylation in order to observe the changes occurred in the molecule which could give it a positive and specific application. The physical characteristics were evaluated by morphometric analysis using analytical methods as scanning electron microscopy, x-ray diffraction and nuclear magnetic resonance in solid state. The results point for all the evaluated characteristics that the cross-linked starch from potato maintains a granular size and shape similar to native starch, through some granules were affected since they presented cracks and outlet of internal material; the introduction of phosphate groups in the molecule is evident in the NMR spectra: the methylated starch from potato changed in a drastic way the structure of granules since the size increased from 9 to 53 μm of the native starch to 44 to 181 μm for the methylated, the X-ray spectra shows a formation of crystals, banishing the characteristic standard type B, likewise with NMR a modification of starch was observed due to the presence of methyl groups. (Author)

  20. Transcriptionally active and inactive genes are similarly modified by chemical carcinogens or X-ray in normal human fibroblasts

    International Nuclear Information System (INIS)

    Chemical carcinogens and ionizing radiation induce DNA modifications and strand breaks in cells. This damage is reported to be affected by chromatin proteins or chromatin of a higher structure order. To compare the sensitivity of transcriptionally active and inactive genes on chromatin toward DNA-damaging agents, we treated normal human fibroblasts (WI-38) cells with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), X-ray, 4-hydroxyaminoquinoline 1-oxide or N-acetoxy-2-acetylaminofluorene, and high molecular weight DNA was isolated. After digestion with EcoRI to completion, the DNA was electrophoresed on an alkaline agarose gel, blotted on a nitrocellulose filter and hybridized with a transcriptionally active gene probe (human type I(α2) procollagen gene) or an inactive gene probe (human β-globin gene). The results show that both genes are similarly modified by these agents. Repair of DNA damage caused by MNNG also occurred similarly in collagen and β-globin genes after removal of MNNG. (Auth.)

  1. Magnetic and Electrical Properties of Nitrogen-Doped Multiwall Carbon Nanotubes Fabricated by a Modified Chemical Vapor Deposition Method

    Directory of Open Access Journals (Sweden)

    María Luisa García-Betancourt

    2015-01-01

    Full Text Available Chemical vapor deposition (CVD is a preferential method to fabricate carbon nanotubes (CNTs. Several changes have been proposed to obtain improved CNTs. In this work we have fabricated nitrogen-doped multiwall carbon nanotubes (N-MWCNTs by means of a CVD which has been slightly modified. Such modification consists in changing the content of the by-product trap. Instead of acetone, we have half-filled the trap with an aqueous solution of NaCl (0–26.82 wt.%. Scanning electron microscope (SEM characterization showed morphological changes depending upon concentration of NaCl included in the trap. Using high resolution transmission electron microscopy several shape changes on the catalyst nanoparticles were also observed. According to Raman spectroscopy results N-MWCNTs fabricated using pure distillate water exhibit better crystallinity. Resistivity measurements performed on different samples by physical properties measurement Evercool system (PPMS showed metallic to semiconducting temperature dependent transitions when high content of NaCl is used. Results of magnetic properties show a ferromagnetic response to static magnetic fields and the coercive fields were very similar for all the studied cases. However, saturation magnetization is decreased if aqueous solution of NaCl is used in the trap.

  2. Eletrodos quimicamente modificados aplicados à eletroanálise: uma breve abordagem Chemically modified electrodes applyes to electroanalysis: a brief presentation

    Directory of Open Access Journals (Sweden)

    Maria de Fátima Brito Souza

    1997-04-01

    Full Text Available Chemically modified electrodes (CMEs have been subject of considerable attention since its inception about 23 years ago. CMEs result of a deliberate immobilization of a modifier agent onto the electrode surface obtained through chemical reactions, chemisorption, composite formation or polymer coating. This immobilization seeks transfer the physicochemical properties of the modifier to the electrode surface and thus to dictate and control the behavior of the electrode/solution interface. In recent years the interest in CMEs has increased particularly to enhance the sensitivity and/or the selectivity of electroanalytical techniques. In general higher sensitivity and/or selectivity may be achieved by exploiting one or more of the following phenomena: electrocatalysis, preconcentration and interferents exclusion. This paper deals with the application of CMEs in electroanalysis, including a brief presentation of the more general procedures that have been employed for the modification of electrode surfaces.

  3. Small lytic peptides escape the inhibitory effect of heparan sulfate on the surface of cancer cells

    Directory of Open Access Journals (Sweden)

    Lindin Inger

    2011-03-01

    Full Text Available Abstract Background Several naturally occurring cationic antimicrobial peptides (CAPs, including bovine lactoferricin (LfcinB, display promising anticancer activities. These peptides are unaffected by multidrug resistance mechanisms and have been shown to induce a protective immune response against solid tumors, thus making them interesting candidates for developing novel lead structures for anticancer treatment. Recently, we showed that the anticancer activity by LfcinB was inhibited by the presence of heparan sulfate (HS on the surface of tumor cells. Based on extensive structure-activity relationship studies performed on LfcinB, shorter and more potent peptides have been constructed. In the present study, we have investigated the anticancer activity of three chemically modified 9-mer peptides and the influence of HS and chondroitin sulfate (CS on their cytotoxic activity. Methods Various cell lines and red blood cells were used to investigate the anticancer activity and selectivity of the peptides. The cytotoxic effect of the peptides against the different cell lines was measured by use of a colorimetric MTT viability assay. The influence of HS and CS on their cytotoxic activity was evaluated by using HS/CS expressing and HS/CS deficient cell lines. The ability of soluble HS and CS to inhibit the cytotoxic activity of the peptides and the peptides' affinity for HS and CS were also investigated. Results The 9-mer peptides displayed selective anticancer activity. Cells expressing HS/CS were equally or more susceptible to the peptides than cells not expressing HS/CS. The peptides displayed a higher affinity for HS compared to CS, and exogenously added HS inhibited the cytotoxic effect of the peptides. Conclusions In contrast to the previously reported inhibitory effect of HS on LfcinB, the present study shows that the cytotoxic activity of small lytic peptides was increased or not affected by cell surface HS.

  4. Synthesis of Base-Modified 2 '-Deoxyribonucleoside Triphosphates and Their Use in Enzymatic Synthesis of Modified DNA for Applications in Bioanalysis and Chemical Biology

    Czech Academy of Sciences Publication Activity Database

    Hocek, Michal

    2014-01-01

    Roč. 79, č. 21 (2014), s. 9914-9921. ISSN 0022-3263 R&D Projects: GA ČR GBP206/12/G151; GA ČR GA14-04289S Institutional support: RVO:61388963 Keywords : cross-coupling reactions * modified nucleoside triphosphates * nucleic acids Subject RIV: CC - Organic Chemistry Impact factor: 4.721, year: 2014

  5. Dennexin peptides modeled after the homophilic binding sites of the neural cell adhesion molecule (NCAM) promote neuronal survival, modify cell adhesion and impair spatial learning

    DEFF Research Database (Denmark)

    Køhler, Lene B; Christensen, Claus; Rossetti, Clara; Fantin, Martina; Sandi, Carmen; Bock, Elisabeth; Berezin, Vladimir

    2010-01-01

    Neural cell adhesion molecule (NCAM)-mediated cell adhesion results in activation of intracellular signaling cascades that lead to cellular responses such as neurite outgrowth, neuronal survival, and modulation of synaptic activity associated with cognitive processes. The crystal structure of the...... between Ig1 and Ig3 and between Ig2 and Ig2, respectively, observed in the crystal structure. Although the two dennexin peptides differed in amino acid sequence, they both modulated cell adhesion, reflected by inhibition of NCAM-mediated neurite outgrowth. Both dennexins also promoted neuronal survival...... immunoglobulin (Ig) 1-2-3 fragment of the NCAM ectodomain has revealed novel mechanisms for NCAM homophilic adhesion. The present study addressed the biological significance of the so called dense zipper formation of NCAM. Two peptides, termed dennexinA and dennexinB, were modeled after the contact interfaces...

  6. Doxorubicin in TAT peptide-modified multifunctional immunoliposomes demonstrates increased activity against both drug-sensitive and drug-resistant ovarian cancer models

    OpenAIRE

    Apte, Anjali; Koren, Erez; Koshkaryev, Alexander; Torchilin, Vladimir P.

    2013-01-01

    Multidrug resistance (MDR) is a hallmark of cancer cells and a crucial factor in chemotherapy failure, cancer reappearance, and patient deterioration. We have previously described the physicochemical characteristics and the in vitro anticancer properties of a multifunctional doxorubicin-loaded liposomal formulation. Lipodox®, a commercially available PEGylated liposomal doxorubicin, was made multifunctional by surface-decorating with a cell-penetrating peptide, TATp, conjugated to PEG1000-PE,...

  7. Nanoencapsulation of Biologically Active Peptides from Whey Proteins

    Directory of Open Access Journals (Sweden)

    Sebnem Tellioglu Harsa

    2014-06-01

    Full Text Available "Now a days consumers, in order to feed with balanced diet, prefer healthy and reliable foods. In this respect food manufacturers are trying to respond the demands of consumers by developing new types of foods such as diet foods ( low calorie foods, modified foods (organic foods and functional foods (probiotic and prebiotics. Thus, production of nutritious, functional and beneficial foods has become a growing sector in the United States and European countries. Proteins are major source of many bioactive peptides. Bioactive peptides have been defined as specific protein fragments that have a positive impact on body functions and may ultimately influence human health. These peptides stay inactive within the main protein structure and activated by the enzymatic hydrolysis. These bioactive peptides, derived from proteins, are able to influence basic body systems (cardiovascular, nervous, gastrointestinal and immune systems and show multi-functional character. Due to these properties, studies have recently been focused on milk proteins and their bioactive peptides. Such peptides are inactive within the sequence of the milk protein. Whey contains a multitude of biologically active proteins and peptides. Physiologically active serum proteins are serum albumin, immunoglobulins, proteose-peptone, lactoferrin, lactoperoxidase and growth factors. In addition to these, enzymatic degradation of serum proteins releases a number of bioactive peptides such as alfa-lactophorin, beta-lactophorin, beta- lactotensin, lactokinin, albutensin, serophorin and lactoferricin. One of the common qualities of bioactive substances is their sensitivity to the physical and chemical properties of the environment. For this reason, the usefulness of bioactive components in food is limited by the structure. In order to sustain bioavailibility of these peptides, limiting its relationship with the media by encapsulation technology is one of them osthotly debated issues on in recent

  8. Pressure dependence of backbone chemical shifts in the model peptides Ac-Gly-Gly-Xxx-Ala-NH2.

    Science.gov (United States)

    Erlach, Markus Beck; Koehler, Joerg; Crusca, Edson; Kremer, Werner; Munte, Claudia E; Kalbitzer, Hans Robert

    2016-06-01

    For a better understanding of nuclear magnetic resonance (NMR) detected pressure responses of folded as well as unstructured proteins the availability of data from well-defined model systems are indispensable. In this work we report the pressure dependence of chemical shifts of the backbone atoms (1)H(α), (13)C(α) and (13)C' in the protected tetrapeptides Ac-Gly-Gly-Xxx-Ala-NH2 (Xxx one of the 20 canonical amino acids). Contrary to expectation the chemical shifts of these nuclei have a nonlinear dependence on pressure in the range from 0.1 to 200 MPa. The polynomial pressure coefficients B 1 and B 2 are dependent on the type of amino acid studied. The coefficients of a given nucleus show significant linear correlations suggesting that the NMR observable pressure effects in the different amino acids have at least partly the same physical cause. In line with this observation the magnitude of the second order coefficients of nuclei being direct neighbors in the chemical structure are also weakly correlated. PMID:27335085

  9. A Standardized Chemically Modified Curcuma longa Extract Modulates IRAK-MAPK Signaling in Inflammation and Potentiates Cytotoxicity.

    Science.gov (United States)

    Rana, Minakshi; Maurya, Preeti; Reddy, Sukka S; Singh, Vishal; Ahmad, Hafsa; Dwivedi, Anil K; Dikshit, Madhu; Barthwal, Manoj K

    2016-01-01

    The TLR/IL-1R pathway is a critical signaling module that is misregulated in pathologies like inflammation and cancer. Extracts from turmeric (Curcuma longa L.) enriched in curcumin and carbonyls like turmerones have been shown to exert potent anti-inflammatory effects. The present study evaluated the anti-inflammatory activity, cytotoxic effect and the underlying mechanism of a novel chemically modified, non-carbonyl compound enriched Curcuma longa L. (C. longa) extract (CMCE). CMCE (1 or 10 μg/mL; 14 h) significantly decreased LPS (50-100 ng/mL) induced TNF-α and IL-1β production in THP-1 cells, human, and mouse whole blood as measured by ELISA. LPS-induced IRAK1, MAPK activation, TLR4 expression, TLR4-MyD88 interaction, and IκBα degradation were significantly reduced in CMCE pre-treated THP-1 cells as assessed by Western blotting. CMCE (30, 100, and 300 mg/kg; 10 days p.o.) pre-treated and LPS (10 mg/kg) challenged Swiss mice exhibited attenuated plasma TNF-α, IL-1β, nitrite, aortic iNOS expression, and vascular dysfunction. In a PI permeability assay, cell lines derived from acute myeloid leukemia were most sensitive to the cytotoxic effects of CMCE. Analysis of Sub-G1 phase, Annexin V-PI positivity, loss of mitochondrial membrane potential, increased caspase-3, and PARP-1 activation confirmed CMCE induced apoptosis in HL-60 cells. IRAK inhibition also sensitized HL-60 cells to CMCE induced cytotoxicity. The present study defines the mechanism underlying the action of CMCE and suggests a therapeutic potential for its use in sepsis and leukemia. PMID:27504095

  10. Chemically modified RNA induces osteogenesis of stem cells and human tissue explants as well as accelerates bone healing in rats.

    Science.gov (United States)

    Balmayor, Elizabeth R; Geiger, Johannes P; Aneja, Manish K; Berezhanskyy, Taras; Utzinger, Maximilian; Mykhaylyk, Olga; Rudolph, Carsten; Plank, Christian

    2016-05-01

    Limitations associated to the use of growth factors represent a major hurdle to musculoskeletal regeneration. On the one hand, they are needed to induce neo-tissue formation for the substitution of a necrotic or missing tissue. On the other hand, these factors are used in supraphysiological concentrations, are short lived and expensive and result in many side effects. Here we develop a gene transfer strategy based on the use of chemically modified mRNA (cmRNA) coding for human bone morphogenetic protein 2 (hBMP-2) that is non-immunogenic and highly stable when compared to unmodified mRNA. Transfected stem cells secrete hBMP-2, show elevated alkaline phosphatase levels and upregulated expression of RunX2, ALP, Osterix, Osteocalcin, Osteopontin and Collagen Type I genes. Mineralization was induced as seen by positive Alizarin red staining. hBMP-2 cmRNA transfected human fat tissue also yielded an osteogenic response in vitro as indicated by expression of hBMP-2, RunX2, ALP and Collagen Type I. Delivering hBMP-2 cmRNA to a femur defect in a rat model results in new bone tissue formation as early as 2 weeks after application of very low doses. Overall, our studies demonstrate the feasibility and therapeutic potential of a new cmRNA-based gene therapy strategy that is safe and efficient. When applied clinically, this approach could overcome BMP-2 growth factor associated limitations in bone regeneration. PMID:26923361

  11. Investigation of chemical modifiers for sulfur determination in diesel fuel samples by high-resolution continuum source graphite furnace molecular absorption spectrometry using direct analysis

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Charles S. [Instituto Federal Sul-rio-grandense, Câmpus Pelotas, Pelotas, RS (Brazil); Universidade Federal do Rio Grande do Sul, Instituto de Química, Porto Alegre, RS (Brazil); Vale, Maria Goreti R. [Universidade Federal do Rio Grande do Sul, Instituto de Química, Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Welz, Bernhard [Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Universidade Federal de Santa Catarina, Departamento de Química, Florianópolis, SC (Brazil); Andrade, Jailson B. [Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Dessuy, Morgana B., E-mail: mbdessuy@ufrgs.br [Universidade Federal do Rio Grande do Sul, Instituto de Química, Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil)

    2015-06-01

    High-resolution continuum source graphite furnace molecular absorption spectrometry has been applied for sulfur determination in diesel fuel. The sharp rotational lines of the carbon monosulfide molecule (formed during the vaporization step) were used to measure the absorbance. The analytical line at 258.056 nm was monitored using the sum of three pixels. Different chemical modifiers were investigated and the mixture of palladium and magnesium was used as chemical modifier in combination with iridium as permanent modifier. L-Cysteine was chosen as sulfur standard and the calibration was done against aqueous standard solutions. The proposed method was applied for the analyses of four diesel samples: two S10 samples and two S500 samples. The trueness of the method was checked with a certified reference material (CRM) of sulfur in diesel fuel (NIST 2724b). Accurate results, for samples and CRM, were achieved after a dilution with propan-1-ol. The following figures of merit were obtained: characteristic mass of 17 ± 3 ng, limit of detection and limit of quantification of 1.4 mg kg{sup −1} and 4.7 mg kg{sup −1}, respectively. - Highlights: • Ir, Ru and Zr were investigated as permanent modifiers. • Ca, Mg, Pd and Pd/Mg were investigated as modifiers in solution. • Indirect determination of sulfur monitoring the molecular absorbance of the CS • Direct analysis of diesel samples using a dilution in propan-1-ol.

  12. Investigation of chemical modifiers for sulfur determination in diesel fuel samples by high-resolution continuum source graphite furnace molecular absorption spectrometry using direct analysis

    International Nuclear Information System (INIS)

    High-resolution continuum source graphite furnace molecular absorption spectrometry has been applied for sulfur determination in diesel fuel. The sharp rotational lines of the carbon monosulfide molecule (formed during the vaporization step) were used to measure the absorbance. The analytical line at 258.056 nm was monitored using the sum of three pixels. Different chemical modifiers were investigated and the mixture of palladium and magnesium was used as chemical modifier in combination with iridium as permanent modifier. L-Cysteine was chosen as sulfur standard and the calibration was done against aqueous standard solutions. The proposed method was applied for the analyses of four diesel samples: two S10 samples and two S500 samples. The trueness of the method was checked with a certified reference material (CRM) of sulfur in diesel fuel (NIST 2724b). Accurate results, for samples and CRM, were achieved after a dilution with propan-1-ol. The following figures of merit were obtained: characteristic mass of 17 ± 3 ng, limit of detection and limit of quantification of 1.4 mg kg−1 and 4.7 mg kg−1, respectively. - Highlights: • Ir, Ru and Zr were investigated as permanent modifiers. • Ca, Mg, Pd and Pd/Mg were investigated as modifiers in solution. • Indirect determination of sulfur monitoring the molecular absorbance of the CS • Direct analysis of diesel samples using a dilution in propan-1-ol

  13. Peptide dendrimers

    Czech Academy of Sciences Publication Activity Database

    Niederhafner, Petr; Šebestík, Jaroslav; Ježek, Jan

    2005-01-01

    Roč. 11, - (2005), 757-788. ISSN 1075-2617 R&D Projects: GA ČR(CZ) GA203/03/1362 Institutional research plan: CEZ:AV0Z40550506 Keywords : multiple antigen peptides * peptide dendrimers * synthetic vaccine * multipleantigenic peptides Subject RIV: CC - Organic Chemistry Impact factor: 1.803, year: 2005

  14. Exploration of the Medicinal Peptide Space.

    Science.gov (United States)

    Gevaert, Bert; Stalmans, Sofie; Wynendaele, Evelien; Taevernier, Lien; Bracke, Nathalie; D'Hondt, Matthias; De Spiegeleer, Bart

    2016-01-01

    The chemical properties of peptide medicines, known as the 'medicinal peptide space' is considered a multi-dimensional subset of the global peptide space, where each dimension represents a chemical descriptor. These descriptors can be linked to biofunctional, medicinal properties to varying degrees. Knowledge of this space can increase the efficiency of the peptide-drug discovery and development process, as well as advance our understanding and classification of peptide medicines. For 245 peptide drugs, already available on the market or in clinical development, multivariate dataexploration was performed using peptide relevant physicochemical descriptors, their specific peptidedrug target and their clinical use. Our retrospective analysis indicates that clusters in the medicinal peptide space are located in a relatively narrow range of the physicochemical space: dense and empty regions were found, which can be explored for the discovery of novel peptide drugs. PMID:26876881

  15. Alterations in chemical shifts and exchange broadening upon peptide boronic acid inhibitor binding to α-lytic protease

    International Nuclear Information System (INIS)

    α-Lytic protease, a bacterial serine protease of 198 aminoacids (19800 Da), has been used as a model system for studies of catalytic mechanism, structure-function relationships, and more recently for studies of pro region-assisted protein folding. We have assigned the backbones of the enzyme alone, and of its complex with the tetrahedral transition state mimic N-tert-butyloxycarbonyl-Ala-Pro-boroVal, using double- and triple-resonance 3D NMR spectroscopy on uniformly15N- and 13C/15N-labeled protein.Changes in backbone chemical shifts between the uncomplexed and inhibited form of the protein are correlated with distance from the inhibitor, the displacement of backbone nitrogens, and change in hydrogen bond strength upon inhibitor binding (derived from previously solved crystal structures).A comparison of the solution secondary structure of the uninhibited enzyme with that of the X-ray structure reveals no significant differences.Significant line broadening, indicating intermediate chemical exchange, was observed in many of the active site amides (including three broadened to invisibility), and in a majority of cases the broadening was reversed upon addition of the inhibitor. Implications and possible mechanisms of this line broadening are discussed

  16. Low-Molecular Weight Polyethylenimine Modified with Pluronic 123 and RGD- or Chimeric RGD-NLS Peptide: Characteristics and Transfection Efficacy of Their Complexes with Plasmid DNA

    OpenAIRE

    Jing Hu; Wenfang Zhao; Kehai Liu; Qian Yu; Yuan Mao; Zeyu Lu; Yaguang Zhang; Manman Zhu

    2016-01-01

    To solve the problem of transfection efficiency vs. cytotoxicity and tumor-targeting ability when polyethylenimine (PEI) was used as a nonviral gene delivery vector, new degradable PEI polymers were synthesized via cross-linking low-molecular-weight PEI with Pluronic P123 and then further coupled with a targeting peptide R4 (RGD) and a bifunctional R11 (RGD-NLS), which were termed as P123-PEI-R4 and P123-PEI-R11, respectively. Agarose gel electrophoresis showed that both P123-PEI-R4 and P123-...

  17. Preparation and use of chemically modified MCM-41 and silica gel as selective adsorbents for Hg(II) ions

    International Nuclear Information System (INIS)

    Adsorbents for Hg(II) ion extraction were prepared using amorphous silica gel and ordered MCM-41. Grafting with 2-(3-(2-aminoethylthio)propylthio)ethanamine was used to functionalize the silica. The functionalized adsorbents were characterized by nitrogen adsorption, X-ray diffraction, 13C MAS NMR spectroscopy and thermogravimetric analysis. The adsorption properties of the modified silica gel and MCM-41 were compared using batch method. The effect of pH, stirring time, ionic strength and foreign ions were studied. The extraction of Hg(II) ions occurred rapidly with the modified MCM-41 and the optimal pH range for the extraction by the modified materials was pH 4-7. Foreign ions, especially Cl- had some effect on the extraction efficiency of the modified silica gel and the modified MCM-41. The adsorption behavior of both adsorbents could be described by a Langmuir model at 298 K, and the maximum adsorption capacity of the modified silica gel and MCM-41 at pH 3 was 0.79 and 0.70 mmol g-1, respectively. The modified MCM-41 showed a larger Langmuir constant than that of the modified silica gel, indicating a better ability for Hg(II) ion adsorption. The results indicate that the structure of the materials affects the adsorption behavior. These materials show a potential for the application as effective and selective adsorbents for Hg(II) removal from water

  18. Poly(ε-caprolactone) modified with fusion protein containing self-assembled hydrophobin and functional peptide for selective capture of human blood outgrowth endothelial cells.

    Science.gov (United States)

    Huang, Yujian; Zhang, Suai; Niu, Baolong; Wang, Dandan; Wang, Zefang; Feng, Shuren; Xu, Haijin; Kong, Deling; Qiao, Mingqiang

    2013-01-01

    Human blood outgrowth endothelial cells (HBOECs)-specific binding peptide, TPSLEQRTVYAK (TPS), was proposed to be applied on autologous cell therapy for treating cardiovascular diseases. Hydrophobins, as a family of self-assembly proteins originated from fungi, have demonstrated unique characteristics to modulate surface properties of other materials coated with these amphiphilic proteins in previous studies. In this report, a fusion protein which was composed of class I hydrophobin HGFI originated from Grifola frondosa and functional peptide TPS was expressed by Pichia pastoris expression system. Then, we purified this fusion protein by ultrafiltration and reverse-phase high performance liquid chromatography. Water contact angle, X-ray photoelectron spectroscopy measurements indicated that the surface properties of hydrophobin were greatly preserved by this fusion protein while comparing with wild HGFI. Cell binding assay showed that this fusion protein demonstrated specific binding property to HBOECs while coating on biodegradable poly(ε-caprolactone) (PCL) grafts in the presence of fetal bovine serum, whereas HGFI-coated PCL non-selectively enhanced all types of cells attachments. Methylthiazol tetrazolium assay was employed to verify the cytocompatibility of this fusion protein-based material. This work presented a new perspective to apply hydrophobin in tissue engineering and regenerative medicine and provided an alternative approach to study endothelial progenitor cells. PMID:23010042

  19. Cerebellar distribution of calcitonin gene-related peptide (CGRP) and its receptor components calcitonin receptor-like receptor (CLR) and receptor activity modifying protein 1 (RAMP1) in rat

    DEFF Research Database (Denmark)

    Edvinsson, Lars; Eftekhari, Sajedeh; Salvatore, Christopher A;

    2011-01-01

    Clinical and experimental results have revealed a fundamental role of calcitonin gene-related peptide (CGRP) in primary headaches. CGRP is widely expressed in neurons both in the central nervous system (CNS) and in peripheral sensory nerves. In the CNS there is a wide distribution of CGRP...... modifying protein type 1 (RAMP1) have been developed. In the present study we therefore examined immunohistochemically the distribution of CGRP and its receptor components in the cerebellum. CGRP immunoreactivity was only found intracellularly in the cerebellar Purkinje cell bodies, whereas CLR and RAMP1...... were detected on the surface of the Purkinje cell bodies and in their processes. The elaborate dendritic tree of Purkinje cell fibers was distinctly visualized with the RAMP1 antibody. In addition, profoundly stained fibers spanning from the molecular layer into the medulla was observed with the RAMP1...

  20. Leiurotoxin I (scyllatoxin), a peptide ligand for Ca2(+)-activated K+ channels. Chemical synthesis, radiolabeling, and receptor characterization

    International Nuclear Information System (INIS)

    Leiurotoxin I (scyllatoxin) is a 31-amino acid polypeptide from the venom of the scorpion Leiurus quinquestriatus hebraeus which has been previously isolated and sequenced by others. This paper reports (i) the total synthesis of this scorpion neurotoxin as well as some aspects of its structure-function relationships; (ii) the synthesis of the analog [Tyr2]leiurotoxin I (scyllatoxin) that has been monoiodinated at high specific radioactivity (2000 Ci/mmol) and has served for the characterization of the properties of 125I-[Tyr2]leiurotoxin I binding sites (Kd = 80 pM, molecular mass of 27 and 57 kDa for two polypeptides in the leiurotoxin I binding protein); (iii) the similarity of physiological actions between leiurotoxin I and apamin. Both toxins contract Taenia coli previously relaxed with epinephrine, both toxins block the after-hyperpolarization due to Ca2(+)-activated K+ channel activity in muscle cells in culture; (iv) the probable identity of binding sites for apamin and leiurotoxin I. In spite of a different chemical structure apamin competitively inhibits 125I-[Tyr2] leiurotoxin I binding and vice versa. Moreover, the peculiar effects of K+ on 125I-[Tyr2]leiurotoxin I binding are identical to those previously observed for 125I-apamin binding

  1. Leiurotoxin I (scyllatoxin), a peptide ligand for Ca2(+)-activated K+ channels. Chemical synthesis, radiolabeling, and receptor characterization

    Energy Technology Data Exchange (ETDEWEB)

    Auguste, P.; Hugues, M.; Grave, B.; Gesquiere, J.C.; Maes, P.; Tartar, A.; Romey, G.; Schweitz, H.; Lazdunski, M. (Institut de Pharmacologie du Centre National de la Recherche Scientifique, Valbonne (France))

    1990-03-15

    Leiurotoxin I (scyllatoxin) is a 31-amino acid polypeptide from the venom of the scorpion Leiurus quinquestriatus hebraeus which has been previously isolated and sequenced by others. This paper reports (i) the total synthesis of this scorpion neurotoxin as well as some aspects of its structure-function relationships; (ii) the synthesis of the analog (Tyr2)leiurotoxin I (scyllatoxin) that has been monoiodinated at high specific radioactivity (2000 Ci/mmol) and has served for the characterization of the properties of {sup 125}I-(Tyr2)leiurotoxin I binding sites (Kd = 80 pM, molecular mass of 27 and 57 kDa for two polypeptides in the leiurotoxin I binding protein); (iii) the similarity of physiological actions between leiurotoxin I and apamin. Both toxins contract Taenia coli previously relaxed with epinephrine, both toxins block the after-hyperpolarization due to Ca2(+)-activated K+ channel activity in muscle cells in culture; (iv) the probable identity of binding sites for apamin and leiurotoxin I. In spite of a different chemical structure apamin competitively inhibits {sup 125}I-(Tyr2) leiurotoxin I binding and vice versa. Moreover, the peculiar effects of K+ on {sup 125}I-(Tyr2)leiurotoxin I binding are identical to those previously observed for {sup 125}I-apamin binding.

  2. Preparation, Biodegradation of Coconut Oil Driven Chemically Modified Bovine Serum Albumin Microparticles of Encapsulated Cicer arietinum Amylase and Study of Their Application in Washing Detergents

    OpenAIRE

    Kirti Rani; Vartika Mehta

    2014-01-01

    In present work, Cicer arietinum amylase was encapsulated by emulsification through covalent coupling by glutaraldehyde into chemically modified bovine serum albumin. Biodegradation of coconut oil driven emulsified bovine serum albumin encapsulated Cicer arietinum amylase was carried out by the alkaline protease for its controlled and sustained release of encapsulated enzyme from prepared microparticles of encapsulated Cicer arietinum amylase and its stability increased up to 6 months as comp...

  3. A study comparing chemical peeling using modified jessner′s solution and 15% trichloroacetic acid versus 15% trichloroacetic acid in the treatment of melasma

    OpenAIRE

    Safoury Omar; Zaki Nagla; El Nabarawy Eman; Farag Eman

    2009-01-01

    Background: Melasma is a symmetric progressive hyperpigmentation of the facial skin that occurs in all races but has a predilection for darker skin phenotypes. Depigmenting agents, laser and chemical peeling as classic Jessner′s solution, modified Jessner′s solution and trichloroacetic acid have been used alone and in combination in the treatment of melasma. Objectives: The aim of the study was to compare the therapeutic effect of combined 15% Trichloroacetic acid (TCA...

  4. Review of long-term adverse effects associated with the use of chemically-modified animal and nonanimal source hyaluronic acid dermal fillers

    OpenAIRE

    Edwards, Paul

    2008-01-01

    Paul C Edwards1, John E Fantasia21Associate Professor (Clinical), Department of Periodontics and Oral Medicine, Pathology and Oncology, University of Michigan School of Dentistry, Ann Arbor MI, USA; 2Chief, Division of Oral Pathology, Department of Dental Medicine, Long Island Jewish Medical Center, New Hyde Park, NY, USAAbstract: Although only recently introduced, chemically-modified hyaluronic acid dermal fillers have gained widespread acceptance as “redefining” dermal f...

  5. Review of long-term adverse effects associated with the use of chemically-modified animal and nonanimal source hyaluronic acid dermal fillers

    OpenAIRE

    Edwards, Paul C.; John E Fantasia

    2007-01-01

    Paul C Edwards1, John E Fantasia21Associate Professor (Clinical), Department of Periodontics and Oral Medicine, Pathology and Oncology, University of Michigan School of Dentistry, Ann Arbor MI, USA; 2Chief, Division of Oral Pathology, Department of Dental Medicine, Long Island Jewish Medical Center, New Hyde Park, NY, USAAbstract: Although only recently introduced, chemically-modified hyaluronic acid dermal fillers have gained widespread acceptance as “redefining” dermal f...

  6. Peptide Nucleic Acids Complexes of Two Peptide Nucleic Acid Strands and One

    DEFF Research Database (Denmark)

    1999-01-01

    Peptide nucleic acids and analogues of peptide nucleic acids are used to form duplex, triplex, and other structures with nucleic acids and to modify nucleic acids. The peptide nucleic acids and analogues thereof also are used to modulate protein activity through, for example, transcription arrest...

  7. Preparation, Biodegradation of Coconut Oil Driven Chemically Modified Bovine Serum Albumin Microparticles of Encapsulated Cicer arietinum Amylase and Study of Their Application in Washing Detergents

    Directory of Open Access Journals (Sweden)

    Kirti Rani

    2014-10-01

    Full Text Available In present work, Cicer arietinum amylase was encapsulated by emulsification through covalent coupling by glutaraldehyde into chemically modified bovine serum albumin. Biodegradation of coconut oil driven emulsified bovine serum albumin encapsulated Cicer arietinum amylase was carried out by the alkaline protease for its controlled and sustained release of encapsulated enzyme from prepared microparticles of encapsulated Cicer arietinum amylase and its stability increased up to 6 months as compared to free enzyme. Its biodegradation was carried out by the using different concentration of alkaline protease (5U, 10U, 15U, 20U, 25U, 30U, 35U, 40U. Further, this coconut oil driven chemically modified bovine serum albumin microparticles of encapsulated Cicer arietinum amylase with alkaline protease were used with detergents for washing of stained cloths which have rust, gel pen ink, grease and chocolate strains. These chosen strains are very commonly present on uniforms of school going children which are very tough upon drying, hence, not to be easily vanish with well known brand detergents upon in one wash. But, the mixture solution of coconut oil driven chemically modified bovine serum albumin microparticles of encapsulated Cicer arietinum amylase along with alkaline protease were used with detergents powder for washing of these dry tough strains (rust, gel pen ink, grease and chocolate strains leads to vanishing these strains very fast with absolute clear results were found as compared to results of washing of stained cloths with detergents only.

  8. Polyethylene glycol–polylactic acid nanoparticles modified with cysteine–arginine–glutamic acid–lysine–alanine fibrin-homing peptide for glioblastoma therapy by enhanced retention effect

    Directory of Open Access Journals (Sweden)

    Wu J

    2014-11-01

    Full Text Available Junzhu Wu,1,2,* Jingjing Zhao,1,3,* Bo Zhang,1 Yong Qian,1 Huile Gao,1 Yuan Yu,1 Yan Wei,1 Zhi Yang,1 Xinguo Jiang,1 Zhiqing Pang1 1Key Laboratory of Smart Drug Delivery, Ministry of Education, Department of Pharmaceutics, School of Pharmacy, Fudan University, Shanghai, 2School of Pharmacy, Dali University, Xiaguan, 3School of Pharmacy, China Pharmaceutical University, Nanjing, People’s Republic of China *These authors contributed equally to this work Abstract: For a nanoparticulate drug-delivery system, crucial challenges in brain-glioblastoma therapy are its poor penetration and retention in the glioblastoma parenchyma. As a prevailing component in the extracellular matrix of many solid tumors, fibrin plays a critical role in the maintenance of glioblastoma morphology and glioblastoma cell differentiation and proliferation. We developed a new drug-delivery system by conjugating polyethylene glycol–polylactic acid nanoparticles (NPs with cysteine–arginine–glutamic acid–lysine–alanine (CREKA; TNPs, a peptide with special affinity for fibrin, to mediate glioblastoma-homing and prolong NP retention at the tumor site. In vitro binding tests indicated that CREKA significantly enhanced specific binding of NPs with fibrin. In vivo fluorescence imaging of glioblastoma-bearing nude mice, ex vivo brain imaging, and glioblastoma distribution demonstrated that TNPs had higher accumulation and longer retention in the glioblastoma site over unmodified NPs. Furthermore, pharmacodynamic results showed that paclitaxel-loaded TNPs significantly prolonged the median survival time of intracranial U87 glioblastoma-bearing nude mice compared with controls, Taxol, and NPs. These findings suggested that TNPs were able to target the glioblastoma and enhance retention, which is a valuable strategy for tumor therapy. Keywords: CREKA peptide, nanoparticles, retention effect, paclitaxel, glioblastoma

  9. Low-Molecular Weight Polyethylenimine Modified with Pluronic 123 and RGD- or Chimeric RGD-NLS Peptide: Characteristics and Transfection Efficacy of Their Complexes with Plasmid DNA.

    Science.gov (United States)

    Hu, Jing; Zhao, Wenfang; Liu, Kehai; Yu, Qian; Mao, Yuan; Lu, Zeyu; Zhang, Yaguang; Zhu, Manman

    2016-01-01

    To solve the problem of transfection efficiency vs. cytotoxicity and tumor-targeting ability when polyethylenimine (PEI) was used as a nonviral gene delivery vector, new degradable PEI polymers were synthesized via cross-linking low-molecular-weight PEI with Pluronic P123 and then further coupled with a targeting peptide R4 (RGD) and a bifunctional R11 (RGD-NLS), which were termed as P123-PEI-R4 and P123-PEI-R11, respectively. Agarose gel electrophoresis showed that both P123-PEI-R4 and P123-PEI-R11 efficaciously condense plasmid DNA at a polymer-to-pDNA w/w ratio of 3.0 and 0.4, respectively. The polyplexes were stable in the presence of serum and could protect plasmid DNA against DNaseI. They had uniform spherical nanoparticles with appropriate sizes around 100-280 nm and zeta-potentials about +40 mV. Furthermore, in vitro experiments showed that these polyplexes had lower cytotoxicity at any concentration compared with PEI 25 kDa, thus giving promise to high transfection efficiency as compared with another P123-PEI derivate conjugated with trifunctional peptide RGD-TAT-NLS (P123-PEI-R18). More importantly, compared with the other polymers, P123-PEI-R11 showed the highest transfection efficiency with relatively lower cytotoxicity at any concentration, indicating that the new synthetic polymer P123-PEI-R11 could be used as a safe and efficient gene deliver vector. PMID:27213305

  10. Orientation Preferences of Backbone Secondary Amide Functional Groups in Peptide Nucleic Acid Complexes: Quantum Chemical Calculations Reveal an Intrinsic Preference of Cationic D-Amino Acid-Based Chiral PNA Analogues for the P-form

    OpenAIRE

    Topham, Christopher M.; Smith, Jeremy C.

    2006-01-01

    Geometric descriptions of nonideal interresidue hydrogen bonding and backbone-base water bridging in the minor groove are established in terms of polyamide backbone carbonyl group orientation from analyses of residue junction conformers in experimentally determined peptide nucleic acid (PNA) complexes. Two types of interresidue hydrogen bonding are identified in PNA conformers in heteroduplexes with nucleic acids that adopt A-like basepair stacking. Quantum chemical calculations on the bindin...

  11. Endothelialization of polyurethanes: Surface silanization and immobilization of REDV peptide.

    Science.gov (United States)

    Butruk-Raszeja, Beata A; Dresler, Magdalena S; Kuźmińska, Aleksandra; Ciach, Tomasz

    2016-08-01

    The paper presents method for chemical immobilization of arginine-glutamic acid-aspartic acid-valine (REDV) peptide on polyurethane surface. The peptide has been covalently bonded using silanes as a spacer molecules. The aim of this work was to investigate the proposed modification process and assess its biological effectiveness, especially in contact with blood and endothelial cells. Physicochemical properties were examined in terms of wettability, atomic composition and density of introduced functional groups and peptide molecules. Experiments with blood showed that material coating reduced number of surface-adhered platelets and fibrinogen molecules. In contrast to polyurethane (PU), there were no blood components deposited on REDV-modified materials (PU-REDV); fibrinogen adsorption on PU-REDV surface has been strongly reduced compared to PU. Analysis of cell adhesion after 1, 2, 3, 4, and 5 days of culture showed a significant increase of the cell-coated area on PU-REDV compared to PU. However, an intense cell growth appeared also on the control surface modified without the addition of REDV. Thus, the positive effect of REDV peptide on the adhesion of HUVEC could not be unequivocally confirmed. PMID:27110909

  12. Determination of antimony in sediments and soils by slurry sampling graphite furnace atomic absorption spectrometry using a permanent chemical modifier

    Energy Technology Data Exchange (ETDEWEB)

    Dobrowolski, Ryszard, E-mail: rdobrow@poczta.umcs.lublin.pl; Adamczyk, Agnieszka; Otto, Magdalena; Dobrzynska, Joanna

    2011-07-15

    For comparison of action of mixed permanent modifiers Ir/Nb and Ir/W, the influence of the amounts of modifier components was studied and the atomic absorption pyrolysis and atomization curves were determined with different modifiers. The optimum amounts of modifier components were 30 {mu}g Ir and 40 {mu}g of Nb that were deposited onto the L'vov platform in advance to analytical measurements. The long-term performance of the Ir and Nb permanent modifiers was derived from the investigations by scanning electron microscopy and energy dispersive X-ray spectrometry. The soil and sediment slurries were prepared in 4% hydrofluoric acid and 6% suspension of polytetrafluoroethylene in order to remove the high concentration of silica during the pyrolysis step of 900 deg. C. The calibration was made by using aqueous standards. The analysis of certified reference materials confirmed the accuracy and reliability of the proposed analytical approach. The precision of Sb determination was characterized with less than 6% RSD.

  13. Biomimetic peptide nanosensors.

    Science.gov (United States)

    Cui, Yue; Kim, Sang N; Naik, Rajesh R; McAlpine, Michael C

    2012-05-15

    The development of a miniaturized sensing platform tailored for sensitive and selective detection of a variety of biochemical analytes could offer transformative fundamental and technological opportunities. Due to their high surface-to-volume ratios, nanoscale materials are extremely sensitive sensors. Likewise, peptides represent robust substrates for selective recognition due to the potential for broad chemical diversity within their relatively compact size. Here we explore the possibilities of linking peptides to nanosensors for the selective detection of biochemical targets. Such systems raise a number of interesting fundamental challenges: What are the peptide sequences, and how can rational design be used to derive selective binders? What nanomaterials should be used, and what are some strategies for assembling hybrid nanosensors? What role does molecular modeling play in elucidating response mechanisms? What is the resulting performance of these sensors, in terms of sensitivity, selectivity, and response time? What are some potential applications? This Account will highlight our early attempts to address these research challenges. Specifically, we use natural peptide sequences or sequences identified from phage display as capture elements. The sensors are based on a variety of nanomaterials including nanowires, graphene, and carbon nanotubes. We couple peptides to the nanomaterial surfaces via traditional surface functionalization methods or self-assembly. Molecular modeling provides detailed insights into the hybrid nanostructure, as well as the sensor detection mechanisms. The peptide nanosensors can distinguish chemically camouflaged mixtures of vapors and detect chemical warfare agents with sensitivities as low as parts-per-billion levels. Finally, we anticipate future uses of this technology in biomedicine: for example, devices based on these sensors could detect disease from the molecular components in human breath. Overall, these results provide a

  14. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  15. Peroxide-Dependent Analyte Conversion by the Heme Prosthetic Group, the Heme Peptide “Microperoxidase-11” and Cytochrome c on Chitosan Capped Gold Nanoparticles Modified Electrodes

    Directory of Open Access Journals (Sweden)

    Frieder W. Scheller

    2012-05-01

    Full Text Available In view of the role ascribed to the peroxidatic activity of degradation products of cytochrome c (cyt c in the processes of apoptosis, we investigate the catalytic potential of heme and of the cyt c derived heme peptide MP-11 to catalyse the cathodic reduction of hydrogen peroxide and to oxidize aromatic compounds. In order to check whether cyt c has an enzymatic activity in the native state where the protein matrix should suppress the inherent peroxidatic activity of its heme prosthetic group, we applied a biocompatible immobilization matrix and very low concentrations of the co-substrate H2O2. The biocatalysts were entrapped on the surface of a glassy carbon electrode in a biocompatible chitosan layer which contained gold nanoparticles. The electrochemical signal for the peroxide reduction is generated by the redox conversion of the heme group, whilst a reaction product of the substrate oxidation is cathodically reduced in the substrate indication. The catalytic efficiency of microperoxidase-11 is sufficient for sensors indicating HRP substrates, e.g., p-aminophenol, paracetamol and catechol, but also the hydroxylation of aniline and dehalogenation of 4-fluoroaniline. The lower limit of detection for p-aminophenol is comparable to previously published papers with different enzyme systems. The peroxidatic activity of cyt c immobilized in the chitosan layer for catechol was found to be below 1 per mill and for p-aminophenol about 3% as compared with that of heme or MP-11.

  16. Investigation of chemical modifiers for sulfur determination in diesel fuel samples by high-resolution continuum source graphite furnace molecular absorption spectrometry using direct analysis

    Science.gov (United States)

    Huber, Charles S.; Vale, Maria Goreti R.; Welz, Bernhard; Andrade, Jailson B.; Dessuy, Morgana B.

    2015-06-01

    High-resolution continuum source graphite furnace molecular absorption spectrometry has been applied for sulfur determination in diesel fuel. The sharp rotational lines of the carbon monosulfide molecule (formed during the vaporization step) were used to measure the absorbance. The analytical line at 258.056 nm was monitored using the sum of three pixels. Different chemical modifiers were investigated and the mixture of palladium and magnesium was used as chemical modifier in combination with iridium as permanent modifier. L-Cysteine was chosen as sulfur standard and the calibration was done against aqueous standard solutions. The proposed method was applied for the analyses of four diesel samples: two S10 samples and two S500 samples. The trueness of the method was checked with a certified reference material (CRM) of sulfur in diesel fuel (NIST 2724b). Accurate results, for samples and CRM, were achieved after a dilution with propan-1-ol. The following figures of merit were obtained: characteristic mass of 17 ± 3 ng, limit of detection and limit of quantification of 1.4 mg kg- 1 and 4.7 mg kg- 1, respectively.

  17. Chemically modified polymeric resins for separation of cations, organic acids, and small polar moleculea by high performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.B.

    1993-07-01

    This thesis is divided into 4 parts: a review, ion chromatography of metal cations on carboxylic resins, separation of hydrophilic organic acids and small polar compounds on macroporous resin columns, and use of eluent modifiers for liquid chromatographic separation of carboxylic acids using conductivity detection.

  18. Enzymatically hydrolysed, acetylated and dually modified corn starch: physico-chemical, rheological and nutritional properties and effects on cake quality.

    Science.gov (United States)

    Sahnoun, Mouna; Ismail, Nouha; Kammoun, Radhouane

    2016-01-01

    Corn starch was treated by enzymatic hydrolysis with Aspergillus oryzae S2 α-amylase, acetylation with vinyl acetate, and dual modification. The dual modified starch displayed a higher substitution degree than the acetylated starch and lower reducing sugar content than the hydrolysed starch. The results revealed that the cooling viscosity and amylose content of those products decrease (P oil absorption capacity was observed for the acetylated starch and, which was less pronounced for the enzymatically hydrolysed starch but more pronounced for the enzymatically hydrolysed acetylated product. The latter product underwent an increase in resistant starch content, which is induced by a rise in hydrolysis time to attain about 67 % after 1 h of reaction. The modified starch samples were added to cake formulations at 5 and 10 % concentrations on a wheat flour basis and compared to native starch. The results revealed that when applied at 5 % concentrations, the modified starches reduced the hardness, cohesion, adhesion and chewiness of baked cakes and enhanced their elasticity, volume, height, crust color, and appearance as compared to native starch. These effects were more pronounced for the cake incorporating the dually modified starch. PMID:26787967

  19. Comparison of Fe-Al-modified natural materials by an electrochemical method and chemical precipitation for the adsorption of F(-) and As(V).

    Science.gov (United States)

    Vázquez Mejía, G; Martínez-Miranda, V; Fall, C; Linares-Hernández, I; Solache-Ríos, M

    2016-03-01

    The adsorption of fluoride and arsenic ions by modified natural materials may have an impact on the removal of F(-) and As(V) from waters. In this work, a zeolitic material and pozzolan (commonly known as pumicite) were modified with aluminium an iron by an electrochemical method and chemical precipitation, respectively. The adsorbents were characterized by X-ray diffraction, scanning electron microscopy with energy X-ray disperse spectroscopy analysis and the point of zero charge (pHzpc). F(-) and As(V) adsorption properties of both materials were investigated. Adsorption kinetic data were best fitted to pseudo-second-order model and equilibrium data to the Langmuir isotherm model. The highest F(-) and As(V) sorption capacities were obtained for modified zeolitic (0.866 mg/g) and pozzolan (3.35 mg/g) materials, respectively, with initial F(-) or As(V) concentrations of 10 mg/L. It was found that the unmodified materials did not show either adsorption of F(-) ions or As(V), which indicated that Al and Fe in the adsorbents are responsible for the adsorption of these ions. In general, both modified materials show similar capacities for the adsorption of F(-) and As(V). PMID:26362939

  20. A study comparing chemical peeling using modified jessner′s solution and 15% trichloroacetic acid versus 15% trichloroacetic acid in the treatment of melasma

    Directory of Open Access Journals (Sweden)

    Safoury Omar

    2009-01-01

    Full Text Available Background: Melasma is a symmetric progressive hyperpigmentation of the facial skin that occurs in all races but has a predilection for darker skin phenotypes. Depigmenting agents, laser and chemical peeling as classic Jessner′s solution, modified Jessner′s solution and trichloroacetic acid have been used alone and in combination in the treatment of melasma. Objectives: The aim of the study was to compare the therapeutic effect of combined 15% Trichloroacetic acid (TCA and modified Jessner′s solution with 15% TCA on melasma. Materials and Methods: Twenty married females with melasma (epidermal type, with a mean age of 38.25 years, were included in this study. All were of skin type III or IV. Fifteen percent TCA was applied to the whole face, with the exception of the left malar area to which combined TCA 15% and modified Jessner′s solution was applied. Results: Our results revealed statistically highly significant difference between MASI Score (Melasma Area and Severity Index between the right malar area and the left malar area. Conclusion: Modified Jessner′s solution proved to be useful as an adjuvant treatment with TCA in the treatment of melasma, improving the results and minimizing postinflammatory hyperpigmentation.

  1. Direct determination of Cd and Pb in human urine by GFAAS with deuterium-lamp background correction using different chemical modifiers

    International Nuclear Information System (INIS)

    Several authors have contributed to the elaboration of methodology for direct determination of Cd and Pb in urine by graphite furnace atomic absorption spectrometry (GFAAS). In the proposed approaches, Zeeman background correction systems were predominantly used, without paying much attention to the selection of an appropriate chemical modifier. However, systematic studies on eleven recommended and less commonly used modifiers have resulted in optimization of atomization conditions, so that accurate analysis also with the use of D2-lamp background correction became possible. This was confirmed by comparative measurements using both background correction systems. For determination of Cd in urine, NH4F has been selected resulting in the lowest limit of detection (LOD): 0.07 μg L-1. NH4F promotes efficient atomization at low temperatures and suppresses chloride interference effect. Pd + Sr (nitrate) has been selected as the most adequate modifier for determination of Pb. Its presence raised the maximum tolerable pyrolysis temperature up to 1200oC, which resulted in the maximum reduction of the background signal and the lowest LOD of 1.5 mg L-1 for Pb (10 μL aliquots of dispensed urine). Applying the above modifiers to the analysis of standards and samples, direct aqueous calibration for accurate analysis of diluted and acidified urine samples became possible. Accuracy of the analysis was verified by the use of commercially available quality control reference materials. (authors)

  2. In Vitro and in Vivo Characterization of MOD-4023, a Long-Acting Carboxy-Terminal Peptide (CTP)-Modified Human Growth Hormone.

    Science.gov (United States)

    Hershkovitz, Oren; Bar-Ilan, Ahuva; Guy, Rachel; Felikman, Yana; Moschcovich, Laura; Hwa, Vivian; Rosenfeld, Ron G; Fima, Eyal; Hart, Gili

    2016-02-01

    MOD-4023 is a novel long-acting version of human growth hormone (hGH), containing the carboxy-terminal peptide (CTP) of human chorionic gonadotropin (hCG). MOD-4023 is being developed as a treatment for adults and children with growth hormone deficiency (GHD), which would require fewer injections than currently available GH formulations and thus reduce patient discomfort and increase compliance. This study characterizes MOD-4023's binding affinities for the growth hormone receptor, as well as the pharmacokinetic and pharmacodynamics, toxicology, and safety profiles of repeated dosing of MOD-4023 in Sprague-Dawley rats and Rhesus monkeys. Although MOD-4023 exhibited reduced in vitro potency and lower affinity to the GH receptor than recombinant hGH (rhGH), administration of MOD-4023 every 5 days in rats and monkeys resulted in exposure comparable to daily rhGH, and the serum half-life of MOD-4023 was significantly longer. Repeated administration of MOD-4023 led to elevated levels of insulin-like growth factor 1 (IGF-1), and twice-weekly injections of MOD-4023 resulted in larger increase in weight gain with fewer injections and a lower accumulative hGH dose. Thus, the increased half-life of MOD-4023 in comparison to hGH may increase the frequency of protein-receptor interactions and compensate for its decreased in vitro potency. MOD-4023 was found to be well-tolerated in rats and monkeys, with minimal adverse events, suggesting an acceptable safety profile. These results provide a basis for the continued clinical development of MOD-4023 as a novel treatment of GHD in children and adults. PMID:26713839

  3. A surface charge-switchable and folate modified system for co-delivery of proapoptosis peptide and p53 plasmid in cancer therapy.

    Science.gov (United States)

    Chen, Si; Rong, Lei; Lei, Qi; Cao, Peng-Xi; Qin, Si-Yong; Zheng, Di-Wei; Jia, Hui-Zhen; Zhu, Jing-Yi; Cheng, Si-Xue; Zhuo, Ren-Xi; Zhang, Xian-Zheng

    2016-01-01

    To improve the tumor therapeutic efficiency and reduce undesirable side effects, ternary FK/p53/PEG-PLL(DA) complexes with a detachable surface shielding layer were designed. The FK/p53/PEG-PLL(DA) complexes were fabricated by coating the folate incorporated positively charged FK/p53 complexes with charge-switchable PEG-shield (PEG-PLL(DA)) through electrostatic interaction. At the physiological pH 7.4 in the bloodstream, PEG-PLL(DA) could extend the circulating time by shielding the positively charged FK/p53 complexes. After the accumulation of the FK/p53/PEG-PLL(DA) complexes in tumor sites, tumor-acidity-triggered charge switch led to the detachment of PEG-PLL(DA) from the FK/p53 complexes, and resulted in efficient tumor cell entry by folate-mediated uptake and electrostatic attraction. Stimulated by the high content glutathione (GSH) in cytoplasm, the cleavage of disulfide bond resulted in the liberation of proapoptosis peptide C-KLA(TPP) and the p53 gene, which exerted the combined tumor therapy by regulating both intrinsic and extrinsic apoptotic pathways. Both in vitro and in vivo studies confirmed that the ternary detachable complexes FK/p53/PEG-PLL(DA) could enhance antitumor efficacy and reduce adverse effects to normal cells. These findings indicate that the tumor-triggered decomplexation of FK/p53/PEG-PLL(DA) supplies a useful strategy for targeting delivery of different therapeutic agents in synergetic anticancer therapy. PMID:26599622

  4. The Function and Development of Soybean Peptides

    Institute of Scientific and Technical Information of China (English)

    Yang Caiyan; Song Junmei

    2009-01-01

    Soybean peptides are small molecules hydrolyzed soy protein,from three to six amino acid composition of the peptide mixture,in 1000Da molecular weight below.Because it has a lot of good physical and chemical properties and physiological functions,in many areas has been widely used.This paper reviews the soybean peptide physical and chemical characteristics,physiological functions,technology and applications in the food industry.

  5. Electron transfer modifies chemical properties of C70 fullerene surface: an ab initio molecular dynamics study of C70O3 molozonides doped with light atoms

    OpenAIRE

    Morrison, Carole; Bil, Andrzej; Hutter, Jurg

    2014-01-01

    Light metal atoms such as Li, K (electronic state 2S 1/2) or Ca (1S0) encapsulated in a C 70 cage considerably modifies the chemical properties of the fullerene surface due to metal-to-cage electron transfer. H-doped and anion ozonide systems were also considered to validate the electron transfer hypothesis. The relative stabilities of the eight isomers of the C 70O3 molozonide series at room temperature depend on the identity of the endohedral guest, as was the preferred channel for thermal ...

  6. Investigation of chemical modifiers for the determination of lead in fertilizers and limestone using graphite furnace atomic absorption spectrometry with Zeeman-effect background correction and slurry sampling

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Aline R. [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq–INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Becker, Emilene M.; Dessuy, Morgana B. [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Vale, Maria Goreti R., E-mail: mgrvale@ufrgs.br [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq–INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Welz, Bernhard [Instituto Nacional de Ciência e Tecnologia do CNPq–INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil)

    2014-02-01

    In this work, chemical modifiers in solution (Pd/Mg, NH{sub 4}H{sub 2}PO{sub 4} and NH{sub 4}NO{sub 3}/Pd) were compared with permanent modifiers (Ir and Ru) for the determination of lead in fertilizer and limestone samples using slurry sampling and graphite furnace atomic absorption spectrometry with Zeeman-effect background correction. The analytical line at 283.3 nm was used due to some spectral interference observed at 217.0 nm. The NH{sub 4}H{sub 2}PO{sub 4} was abandoned due to severe spectral interference even at the 283.3-nm line. For Pd/Mg and NH{sub 4}NO{sub 3}/Pd the optimum pyrolysis and atomization temperatures were 900 °C and 1900 °C, respectively. For Ru and Ir, the integrated absorbance signal was stable up to pyrolysis temperatures of 700 °C and 900 °C, respectively, and up to atomization temperature of 1700 °C. The limit of detection (LOD) was 17 ng g{sup −1} using Pd/Mg and 29 ng g{sup −1} using NH{sub 4}NO{sub 3}/Pd. Among the permanent modifiers investigated, the LOD was 22 ng g{sup −1} Pb for Ir and 10 ng g{sup −1} Pb for Ru. The accuracy of the method was evaluated using the certified reference material NIST SRM 695. Although Ru provided lower LOD, which can be attributed to a lower blank signal, only the modifiers in solution showed concordant values of Pb concentration for the NIST SRM 695 and the most of analyzed samples. Moreover, the Pd/Mg modifier provided the highest sensitivity and for this reason it is more suitable for the determination of Pb in fertilizers samples in slurry; besides this it presented a better signal-to-noise ratio than NH{sub 4}NO{sub 3}/Pd. - Highlights: • Lead has been determined in fertilizers using slurry sampling GF AAS. • The mixture of palladium and magnesium nitrates was found to be the ideal chemical modifier. • Calibration could be carried out against aqueous standard solutions. • The proposed method is much faster than the EPA method, which includes sample digestion.

  7. Investigation of chemical modifiers for the determination of lead in fertilizers and limestone using graphite furnace atomic absorption spectrometry with Zeeman-effect background correction and slurry sampling

    International Nuclear Information System (INIS)

    In this work, chemical modifiers in solution (Pd/Mg, NH4H2PO4 and NH4NO3/Pd) were compared with permanent modifiers (Ir and Ru) for the determination of lead in fertilizer and limestone samples using slurry sampling and graphite furnace atomic absorption spectrometry with Zeeman-effect background correction. The analytical line at 283.3 nm was used due to some spectral interference observed at 217.0 nm. The NH4H2PO4 was abandoned due to severe spectral interference even at the 283.3-nm line. For Pd/Mg and NH4NO3/Pd the optimum pyrolysis and atomization temperatures were 900 °C and 1900 °C, respectively. For Ru and Ir, the integrated absorbance signal was stable up to pyrolysis temperatures of 700 °C and 900 °C, respectively, and up to atomization temperature of 1700 °C. The limit of detection (LOD) was 17 ng g−1 using Pd/Mg and 29 ng g−1 using NH4NO3/Pd. Among the permanent modifiers investigated, the LOD was 22 ng g−1 Pb for Ir and 10 ng g−1 Pb for Ru. The accuracy of the method was evaluated using the certified reference material NIST SRM 695. Although Ru provided lower LOD, which can be attributed to a lower blank signal, only the modifiers in solution showed concordant values of Pb concentration for the NIST SRM 695 and the most of analyzed samples. Moreover, the Pd/Mg modifier provided the highest sensitivity and for this reason it is more suitable for the determination of Pb in fertilizers samples in slurry; besides this it presented a better signal-to-noise ratio than NH4NO3/Pd. - Highlights: • Lead has been determined in fertilizers using slurry sampling GF AAS. • The mixture of palladium and magnesium nitrates was found to be the ideal chemical modifier. • Calibration could be carried out against aqueous standard solutions. • The proposed method is much faster than the EPA method, which includes sample digestion

  8. Novel conjugates of peptides and conjugated polymers for optoelectronics and neural interfaces

    Science.gov (United States)

    Bhagwat, Nandita

    Peptide-polymer conjugates are a novel class of hybrid materials that take advantage of each individual component giving the opportunity to generate materials with unique physical, chemical, mechanical, optical, and electronic properties. In this dissertation peptide-polymer conjugates for two different applications are discussed. The first set of peptide-polymer conjugates were developed as templates to study the intermolecular interactions between electroactive molecules by manipulating the intermolecular distances at nano-scale level. A PEGylated, alpha-helical peptide template was employed to effectively display an array of organic chromophores (oxadiazole containing phenylenevinylene oligomers, Oxa-PPV). Three Oxa-PPV chromophores were strategically positioned on each template, at distances ranging from 6 to 17 A from each other, as dictated by the chemical and structural properties of the peptide. The Oxa-PPV modified PEGylated helical peptides (produced via Heck coupling strategies) were characterized by a variety of spectroscopic methods. Electronic contributions from multiple pairs of chromophores on a scaffold were detectable; the number and relative positioning of the chromophores dictated the absorbance and emission maxima, thus confirming the utility of these polymer--peptide templates for complex presentation of organic chromophores. The rest of the thesis is focused on using poly(3,4-alkylenedioxythiophene) based conjugated polymers as coatings for neural electrodes. This thiophene derivative is of considerable current interest for functionalizing the surfaces of a wide variety of devices including implantable biomedical electronics, specifically neural bio-electrodes. Toward these ends, copolymer films of 3,4-ethylenedioxythiophene (EDOT) with a carboxylic acid functional EDOT (EDOTacid) were electrochemically deposited and characterized as a systematic function of the EDOTacid content (0, 25, 50, 75, and 100%). The chemical surface characterization

  9. Serum low density lipoprotein of alcoholic patients is chemically modified in vivo and induces apolipoprotein E synthesis by macrophages.

    OpenAIRE

    Lin, R C; Dai, J; Lumeng, L; Zhang, M Y

    1995-01-01

    This work was carried out to investigate the effect of alcohol drinking on serum LDL. Agarose gel electrophoresis showed that LDL samples from alcoholic patients without serious liver disease were more negatively charged and moved faster toward the cathode than LDL from nondrinking control subjects. Rabbit antibodies raised by using keyhole limpet hemocyanin modified in vitro by 4-hydroxynonenal or by acetaldehyde as immunogens reacted more strongly with patients' LDL than with control LDL, i...

  10. Assessment of antimicrobial activity of polyazolidinammonium modified by iodine hydrate ions depending on its physical and chemical characteristics.

    OpenAIRE

    Vakaraeva M.M.; Uljanov V.Yu.; Nechaeva O.V.; Luneva I.0.; Tikhomirova E.l.; Shapoval O.G.; Zayarskiy D.A.

    2015-01-01

    Aim: to study antimicrobial activity of variants of polymeric compound polyazolidinammonium modified by iodine hydrate-ions (PAAG-M), depending on the polymeric chain length and concentration of the iodine hydrate-ions against standard strains of gram-positive and gram-negative bacteria as well as microscopic fungi. Materials and methods. Minimum inhibitory concentrations of all variants of the polymeric compound for tested microbial strains have been determined by using serial dilution metho...

  11. Antimicrobial Peptides from Plants

    Science.gov (United States)

    Tam, James P.; Wang, Shujing; Wong, Ka H.; Tan, Wei Liang

    2015-01-01

    Plant antimicrobial peptides (AMPs) have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs) of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic), lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms. PMID:26580629

  12. Antimicrobial Peptides from Plants

    Directory of Open Access Journals (Sweden)

    James P. Tam

    2015-11-01

    Full Text Available Plant antimicrobial peptides (AMPs have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic, lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms.

  13. Study of the roles of chemical modifiers in determining boron using graphite furnace atomic absorption spectrometry and optimization of the temperature profile during atomization

    International Nuclear Information System (INIS)

    The measurement conditions for determining boron using graphite furnace–atomic absorption spectrometry (GF-AAS) were investigated. Differences in the boron absorbance profiles were found using three different commercially available GF-AAS instruments when the graphite atomizers in them were not tuned. The boron absorbances found with and without adjusting the graphite atomizers suggested that achieving an adequate absorbance for the determination of boron requires a sharp temperature profile that overshoots the target temperature during the atomization process. Chemical modifiers that could improve the boron absorbance without the need for using coating agents were tested. Calcium carbonate improved the boron absorbance but did not suppress variability in the peak height. Improvement of boron absorbance was comparatively less using iron nitrate or copper nitrate than using calcium carbonate, but variability in the peak height was clearly suppressed using iron nitrate or copper nitrate. The limit of detection was 0.0026 mg L−1 when iron nitrate was used. It appears that iron nitrate is a useful new chemical modifier for the quick and simple determination of boron using GF-AAS. (author)

  14. Microwave-assisted catalytic fast pyrolysis of biomass for bio-oil production using chemical vapor deposition modified HZSM-5 catalyst.

    Science.gov (United States)

    Zhang, Bo; Zhong, Zhaoping; Chen, Paul; Ruan, Roger

    2015-12-01

    Chemical vapor deposition with tetra-ethyl-orthosilicate as the modifier was applied to deposit the external acid sites of HZSM-5, and the modified HZSM-5 samples were used for the microwave-assisted catalytic fast pyrolysis (MACFP) of biomass for bio-oil production. The experimental results showed that the external acid sites of HZSM-5 decreased significantly when SiO2 deposited amount increased from 0% to 5.9%. For product distribution, the coke yield decreased, the oil fraction yield decreased at first and then increased, and the yields of water and gas first increased and then decreased over the range of SiO2 deposited amount studied. For chemical compositions in oil fraction, the relative contents of aliphatic hydrocarbons, aromatic hydrocarbons and oxygen-containing aromatic compounds first increased to maximum values and then decreased, while the relative content of oxygen-containing aliphatic compounds first decreased and then increased with increasing SiO2 deposited amount. PMID:26318925

  15. Fixation of laccase enzyme into polypyrrole, assisted by chemical interaction with modified magnetite nanoparticles: A facile route to synthesize stable electroactive bionanocomposite catalysts

    International Nuclear Information System (INIS)

    Highlights: • Chemically immobilized laccase enzyme on magnetite nanoparticles is presented. • Modified nanoparticles were entrapped in conducting polymer matrix. • Bio-electrocatalytic effect was evidenced in the oxygen reduction reaction. • The method may serve as a general platform for enzyme incorporation. • New avenue for conducting polymer based biocatalytic electrodes. - Abstract: Effective bio-electrocatalysts require stable immobilization of sufficient amounts of the bioactive component. In this study, a novel and efficient method for specific binding of laccase enzyme onto magnetite nanoparticles (NPs) is presented. The interaction between the chemically modified magnetite NPs and the enzyme was evidenced by both infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). Subsequently, the enzyme-coated magnetite NPs were successfully incorporated into polypyrrole (PPy) matrix during galvanostatic electropolymerization. The encapsulation of laccase covered NPs was proved by EQCN, TEM, and FT-IR spectroscopy; whereas the electrochemical behaviour of the formed bionanocomposite was characterized by cyclic voltammetry. In oxygen saturated solution a cathodic charge surplus was observed, related to the electrochemical reduction of oxygen. This surplus was two times higher in the case of the laccase containing layer compared to its only magnetite containing counterpart. Kinetic aspects of the oxygen reduction reaction (ORR) on the laccase containing films were investigated by hydrodynamic voltammetry, and the four-electron route was found to be exclusive, which is promising from the fuel cell perspective. Such synergistic combination of inorganic NPs and enzymes may open new avenues in the application of these bio-nanocomposite materials

  16. Electrochemical properties of the hexacyanoferrate(II)–ruthenium(III) complex immobilized on silica gel surface chemically modified with zirconium(IV) oxide

    Energy Technology Data Exchange (ETDEWEB)

    Panice, Lucimara B.; Oliveira, Elisangela A. de; Filho, Ricardo A.D. Molin; Oliveira, Daniela P. de [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil); Lazarin, Angélica M., E-mail: amlazarin2@uem.br [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil); Andreotti, Elza I.S.; Sernaglia, Rosana L. [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil); Gushikem, Yoshitaka [Instituto de Química, Universidade Estadual de Campinas, Caixa Postal 6154, 13084-971 Campinas, São Paulo (Brazil)

    2014-10-15

    Highlights: • The cyano-bridged mixed valence ruthenium composite material was synthesized. • This newly synthesized compound was incorporated into a carbon paste electrode. • The electrode did not show significant changes in response after six months of use. • The modified electrode is very stable and reproducible. • The electrode sensor was successfully applied for ascorbic acid determination. - Abstract: The chemically modified silica gel with zirconium(IV) oxide was used to immobilize the [Fe(CN){sub 6}]{sup 4−} complex ion initially. The reaction of this material with [Ru(edta)H{sub 2}O]{sup −} complex ion formed the immobilized cyano-bridged mixed valence ruthenium complex, (≡Zr){sub 5}[(edta)RuNCFe(CN){sub 5}]. This material was incorporated into a carbon paste electrode and, its electrochemical properties were investigated. However, for an ascorbic acid solution, an enhancement of the anodic peak current was detected due to electrocatalytic oxidation. The electrode presented the same response for at least 150 successive measurements, with a good repeatability. The modified electrode is very stable and reproducible. The sensor was applied for ascorbic acid determination in pharmaceutical preparation with success.

  17. Electrochemical properties of the hexacyanoferrate(II)–ruthenium(III) complex immobilized on silica gel surface chemically modified with zirconium(IV) oxide

    International Nuclear Information System (INIS)

    Highlights: • The cyano-bridged mixed valence ruthenium composite material was synthesized. • This newly synthesized compound was incorporated into a carbon paste electrode. • The electrode did not show significant changes in response after six months of use. • The modified electrode is very stable and reproducible. • The electrode sensor was successfully applied for ascorbic acid determination. - Abstract: The chemically modified silica gel with zirconium(IV) oxide was used to immobilize the [Fe(CN)6]4− complex ion initially. The reaction of this material with [Ru(edta)H2O]− complex ion formed the immobilized cyano-bridged mixed valence ruthenium complex, (≡Zr)5[(edta)RuNCFe(CN)5]. This material was incorporated into a carbon paste electrode and, its electrochemical properties were investigated. However, for an ascorbic acid solution, an enhancement of the anodic peak current was detected due to electrocatalytic oxidation. The electrode presented the same response for at least 150 successive measurements, with a good repeatability. The modified electrode is very stable and reproducible. The sensor was applied for ascorbic acid determination in pharmaceutical preparation with success

  18. Natural and synthetic peptides with antifungal activity.

    Science.gov (United States)

    Ciociola, Tecla; Giovati, Laura; Conti, Stefania; Magliani, Walter; Santinoli, Claudia; Polonelli, Luciano

    2016-08-01

    In recent years, the increase of invasive fungal infections and the emergence of antifungal resistance stressed the need for new antifungal drugs. Peptides have shown to be good candidates for the development of alternative antimicrobial agents through high-throughput screening, and subsequent optimization according to a rational approach. This review presents a brief overview on antifungal natural peptides of different sources (animals, plants, micro-organisms), peptide fragments derived by proteolytic cleavage of precursor physiological proteins (cryptides), synthetic unnatural peptides and peptide derivatives. Antifungal peptides are schematically reported based on their structure, antifungal spectrum and reported effects. Natural or synthetic peptides and their modified derivatives may represent the basis for new compounds active against fungal infections. PMID:27502155

  19. Chemical modification of poly(ethylene terephthalate) and immobilization of the selected enzymes on the modified film

    International Nuclear Information System (INIS)

    Poly(ethylene terephthalate) (PET) film was modified by reaction with hydrazine (HD), ethylenediamine (EDA), 1,2-diaminopropane (1,2-DAP) and 1,3-diaminopropane (1,3-DAP). The maximal amount of amine functionalities introduced in the chosen conditions on the surface was found as 0.07, 3.35, 0.76 and 1.99 nmol cm-2 for HD, EDA, 1,2-DAP and 1,3-DAP respectively. During the modification process etching of the sample and an increase of stiffness takes place. FTIR-ATR spectra prove that the surface chemistry after modification in amine solution is very complex. The lack of clear correlation between the surface tension and surface concentration of amine functionalities seems to confirm that. For immobilization purpose invertase, laccase and tyrosinase were used. The amount of covalently attached proteins at first increases with the increase of surface concentration of amine groups but after reaching a certain level of amine groups, decrease of the immobilization level was observed. All enzymes tested showed highest activity for a moderate level of aminolysis and this activity had the highest values for EDA-modified PET.

  20. Chemical modification of poly(ethylene terephthalate) and immobilization of the selected enzymes on the modified film

    Energy Technology Data Exchange (ETDEWEB)

    Irena, Gancarz, E-mail: irena.gancarz@pwr.wroc.pl [Department of Chemistry, Wroclaw University of Technology, 50-370 Wroclaw (Poland); Jolanta, Bryjak; Karolina, Zynek [Department of Chemistry, Wroclaw University of Technology, 50-370 Wroclaw (Poland)

    2009-07-15

    Poly(ethylene terephthalate) (PET) film was modified by reaction with hydrazine (HD), ethylenediamine (EDA), 1,2-diaminopropane (1,2-DAP) and 1,3-diaminopropane (1,3-DAP). The maximal amount of amine functionalities introduced in the chosen conditions on the surface was found as 0.07, 3.35, 0.76 and 1.99 nmol cm{sup -2} for HD, EDA, 1,2-DAP and 1,3-DAP respectively. During the modification process etching of the sample and an increase of stiffness takes place. FTIR-ATR spectra prove that the surface chemistry after modification in amine solution is very complex. The lack of clear correlation between the surface tension and surface concentration of amine functionalities seems to confirm that. For immobilization purpose invertase, laccase and tyrosinase were used. The amount of covalently attached proteins at first increases with the increase of surface concentration of amine groups but after reaching a certain level of amine groups, decrease of the immobilization level was observed. All enzymes tested showed highest activity for a moderate level of aminolysis and this activity had the highest values for EDA-modified PET.

  1. Chemical modification of poly(ethylene terephthalate) and immobilization of the selected enzymes on the modified film

    Science.gov (United States)

    Irena, Gancarz; Jolanta, Bryjak; Karolina, Zynek

    2009-07-01

    Poly(ethylene terephthalate) (PET) film was modified by reaction with hydrazine (HD), ethylenediamine (EDA), 1,2-diaminopropane (1,2-DAP) and 1,3-diaminopropane (1,3-DAP). The maximal amount of amine functionalities introduced in the chosen conditions on the surface was found as 0.07, 3.35, 0.76 and 1.99 nmol cm -2 for HD, EDA, 1,2-DAP and 1,3-DAP respectively. During the modification process etching of the sample and an increase of stiffness takes place. FTIR-ATR spectra prove that the surface chemistry after modification in amine solution is very complex. The lack of clear correlation between the surface tension and surface concentration of amine functionalities seems to confirm that. For immobilization purpose invertase, laccase and tyrosinase were used. The amount of covalently attached proteins at first increases with the increase of surface concentration of amine groups but after reaching a certain level of amine groups, decrease of the immobilization level was observed. All enzymes tested showed highest activity for a moderate level of aminolysis and this activity had the highest values for EDA-modified PET.

  2. Electrochemical behavior of folic acid at calixarene based chemically modified electrodes and its determination by adsorptive stripping voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Vaze, Vishwanath D. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India); Srivastava, Ashwini K. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India)], E-mail: aksrivastava@chem.mu.ac.in

    2007-12-31

    Voltammetric behavior of folic acid at plain carbon paste electrode and electrode modified with calixarenes has been studied. Two peaks for irreversible oxidation were observed. Out of the three calixarenes chosen for modification of the electrodes, p-tert-butyl-calix[6]arene modified electrode (CME-6) was found to have better sensitivity for folic acid. Chronocoulometric and differential pulse voltammetric studies reveal that folic acid can assemble at CME-6 to form a monolayer whose electron transfer rate is 0.00273 s{sup -1} with 2-electron/2-proton transfer for the peak at +0.71 V against SCE. An adsorption equilibrium constant of 5 x 10{sup 3} l/mol for maximum surface coverage of 2.89 x 10{sup -10} mol/cm{sup 2} was obtained. The current is found to be rectilinear with concentration by differential pulse voltammetry. However, linearity in the lower range of concentration 8.79 x 10{sup -12} M to 1.93 x 10{sup -9} M with correlation coefficient of 0.9920 was achieved by adsorptive stripping voltammetry. The limit of detection obtained was found to be 1.24 x 10{sup -12} M. This method was used for the determination of folic acid in a variety of samples, viz. serum, asparagus, spinach, oranges and multivitamin preparations.

  3. Stereo-separations of Peptides by Capillary Electrophoresis and Chromatography

    OpenAIRE

    sprotocols

    2014-01-01

    Authors: Afzal Hussain, Iqbal Hussain, Mohamed F. Al-Ajmi & Imran Ali ### Abstract Small peptides (di-, tri-, tetra- penta- hexa etc. and peptides) control many chemical and biological processes. The biological importance of stereomers of peptides is of great value. The stereo-separations of peptides are gaining importance in biological and medicinal sciences and pharmaceutical industries. There is a great need of experimental protocols of stereo-separations of peptides. The vario...

  4. Novel epoxy-silicone thermolytic transparent packaging adhesives chemical modified by ZnO nanowires for HB LEDs

    International Nuclear Information System (INIS)

    A novel high transparent thermolytic epoxy-silicone for high-brightness light-emitting diode (HB-LED) is introduced, which was synthesized by polymerization using silicone matrix via diglycidyl ether bisphenol-A epoxy resin (DGEBA) as reinforcing agent, and filling ZnO nanowires to modify thermal conductivity and control refractive index of the hybrid material. The interactions of ZnO nanowires with polymers are mediated by the ligands attached to the nanoparticles. Thus, the ligands markedly influence the properties of ZnO nanowires/epoxy-silicone composites. The refractive indices of the prepared hybrid adhesives can be tuned by the ZnO nanowires from 1.4711 to 1.5605. Light transmittance can be increased by 20% from 80 to 95%. The thermal conductivity of the transparent packaging adhesives is 0.89-0.90 W/mK.

  5. Novel epoxy-silicone thermolytic transparent packaging adhesives chemical modified by ZnO nanowires for HB LEDs

    Energy Technology Data Exchange (ETDEWEB)

    He Ying, E-mail: yinghe@staff.shu.edu.c [Shanghai University, Department of Polymer Materials, School of Materials Science and Engineering (China); Wang Junan [Shanghai University, Institute of Materials, School of Materials Science and Engineering (China); Pei Changlong; Song Jizhong; Zhu Di; Chen Jie [Shanghai University, Department of Polymer Materials, School of Materials Science and Engineering (China)

    2010-10-15

    A novel high transparent thermolytic epoxy-silicone for high-brightness light-emitting diode (HB-LED) is introduced, which was synthesized by polymerization using silicone matrix via diglycidyl ether bisphenol-A epoxy resin (DGEBA) as reinforcing agent, and filling ZnO nanowires to modify thermal conductivity and control refractive index of the hybrid material. The interactions of ZnO nanowires with polymers are mediated by the ligands attached to the nanoparticles. Thus, the ligands markedly influence the properties of ZnO nanowires/epoxy-silicone composites. The refractive indices of the prepared hybrid adhesives can be tuned by the ZnO nanowires from 1.4711 to 1.5605. Light transmittance can be increased by 20% from 80 to 95%. The thermal conductivity of the transparent packaging adhesives is 0.89-0.90 W/mK.

  6. Selective catalytic conversion of ethanol to basic chemicals over phosphorus-modified H-ZSM-5 zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Danilina, N.; Reschetilowski, W. [Technische Univ. Dresden (Germany). Inst. fuer Technische Chemie; Toufar, H. [TRICAT Zeolites, Bitterfeld (Germany)

    2006-07-01

    The activity and selectivity of unmodified and phosphorus-modified H-ZSM-5 zeolites (Si/Al = 11) in the conversion of ethanol was studied. The post-synthesis modification of H-ZSM-5 was done using phosphoric acid; the phosphorus loading was varied between 0.33 and 1.3 wt.-%. The catalytic tests were performed at 450 C and under atmospheric pressure in a plug-flow reactor. All catalyst samples were characterized with XRD, AAS, EDX, IR, and 31P MAS NMR. The acidic properties were determined with in situ FTIR measurements of temperature-programmed ammonia-desorption. The incorporation of phosphorus in H-ZSM-5 zeolites by post-synthesis modification leads to highly active and selective catalysts for the conversion of ethanol to aromatics. The conversion of ethanol increases to up to 100 % and the selectivity to aromatics to maximally 80 wt.-%. (orig.)

  7. Nano-hydroxyapatite colloid suspension coated on chemically modified porous silicon by cathodic bias: a suitable surface for cell culture

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Alejandra [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Gonzalez, Jerson [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Garcia-Pineres, Alfonso [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Investigacion en Biologia Celular y Molecular (CIBCM), Universidad de Costa Rica, 2060 (Costa Rica); Montero, Mavis L. [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Centro de Ciencia e Ingenieria en Materiales (CICIMA), Universidad de Costa Rica, 2060 (Costa Rica)

    2011-06-15

    The properties of porous silicon make it an interesting material for biological applications. However, porous silicon is not an appropriate surface for cell growth. Surface modification is an alternative that could afford a bioactive material. In this work, we report a method to yield materials by modification of the porous silicon surface with hydroxyapatite of nanometric dimensions, produced using an electrochemical process and coated on macroporous silicon substrates by cathodic bias. The chemical nature of the calcium phosphate deposited on the substrates after the experimental process and the amount of cell growth on these surfaces were characterized. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Cleaving Double-Stranded DNA with Peptide Nucleic Acids

    DEFF Research Database (Denmark)

    1997-01-01

    Peptide nucleic acids and analogues of peptide nucleic acids are used to form duplex, triplex, and other structures with nucleic acids and to modify nucleic acids. The peptide nucleic acids and analogues thereof also are used to modulate protein activity through, for example, transcription arrest...

  9. Isolation, chemical and functional characterization of several new K(+)-channel blocking peptides from the venom of the scorpion Centruroides tecomanus.

    Science.gov (United States)

    Olamendi-Portugal, Timoteo; Bartok, Adam; Zamudio-Zuñiga, Fernando; Balajthy, Andras; Becerril, Baltazar; Panyi, Gyorgy; Possani, Lourival D

    2016-06-01

    Six new peptides were isolated from the venom of the Mexican scorpion Centruroides tecomanus; their primary structures were determined and the effects on ion channels were verified by patch-clamp experiments. Four are K(+)-channel blockers of the α-KTx family, containing 32 to 39 amino acid residues, cross-linked by three disulfide bonds. They all block Kv1.2 in nanomolar concentrations and show various degree of selectivity over Kv1.1, Kv1.3, Shaker and KCa3.1 channels. One peptide has 42 amino acids cross-linked by four disulfides; it blocks ERG-channels and belongs to the γ-KTx family. The sixth peptide has only 32 amino acid residues, three disulfide bonds and has no effect on the ion-channels assayed. It also does not have antimicrobial activity. Systematic numbers were assigned (time of elution on HPLC): α-KTx 10.4 (time 24.1); α-KTx 2.15 (time 26.2); α-KTx 2.16 (time 23.8); α-KTx 2.17 (time 26.7) and γ-KTx 1.9 (elution time 29.6). A partial proteomic analysis of the short chain basic peptides of this venom, which elutes on carboxy-methyl-cellulose column fractionation, is included. The pharmacological properties of the peptides described in this study may provide valuable tools for understanding the structure-function relationship of K(+) channel blocking scorpion toxins. PMID:26921461

  10. Application of Nafion/Cobalt Hexacyanoferrate Chemically Modified Electrodes for the Determination of Electroinactive Cations by Ion Chromatography

    Institute of Scientific and Technical Information of China (English)

    徐继明; 鲜跃仲; 等

    2002-01-01

    An amperometric detector based on the chemical modification of Nafion and cobalt(Ⅱ) hexacyanoferrate(Ⅱ,Ⅲ)thin film (Nafion /Co-CN-Fe) onto a glassy carbon(GC) electrode was firstly developed for the determination of electroinactive cations (Li+,Na+,K+,Rb+,Cs+,and NH4+)in single column ion cgrinatography,A set of well-defined peaks of electroinactive cation was obtained ,The relative standard deviations (RSDs) of chromatographic peak height(nA) for these cations were all below 3.8% .The cations were detected convenivently in the linear concentration ragne of 6.0×10-6--5.0×10-3 mol/L and their correlation coefficients were all above 0.99 .The detection limits of the cations were 9.2×107 mol/L for K+,7.8×107mol/L for Rb+,6.2×107mol/L for Cs+ and 6.2×106mol/L for NH4+ ,at a signal-noise ratio of 3. The method was quick,sensitive,simple and was successfully applied to the analysis of rainwater samples,The electrode was stable for a 2 week period of operation with no evidence of chemical of mechanical deterioration.

  11. Radium removal from aqueous solutions by adsorption on non-treated and chemically modified biomass by-product

    International Nuclear Information System (INIS)

    The adsorption efficiency of a biomass by-product (olive cake) regarding the removal of radium (226Ra) from aqueous solutions has been investigated prior and after its chemical treatment. The chemical treatment of the biomass by-product included phosphorylation and MnO2-coating. The separation/removal efficiency has been studied as a function of pH, salinity (NaCl) and calcium ion concentration (Ca2+) in solution. Evaluation of the experimental data shows clearly that the phosphorylated biomass by-product presents the highest adsorption capacity and efficiency followed by the MnO2-coated material and the non-treated biomass by-product. However, regarding the effect of salinity and the presence of competitive cations (e.g. Ca2+) on the adsorption/removal efficiency, the MnO2-coated material shows the lowest decline in efficiency (only 2 % of the relative adsorption efficiency) followed by the non-treated and the phosphorylated biomass by-product. The results of the present study indicate that depending on the physicochemical characteristics of the radium-contaminated water, all three types of the biomass by-product could be effectively used for the treatment of radium-contaminated waters. Nevertheless, the MnO2-coated material is expected to be the most effective adsorbent and an alternative to MnO2 resins for the treatment of environmentally relevant waters. (author)

  12. Radiopharmaceutical development of radiolabelled peptides

    Energy Technology Data Exchange (ETDEWEB)

    Fani, Melpomeni; Maecke, Helmut R. [University Hospital Freiburg, Department of Nuclear Medicine, Freiburg (Germany)

    2012-02-15

    Receptor targeting with radiolabelled peptides has become very important in nuclear medicine and oncology in the past few years. The overexpression of many peptide receptors in numerous cancers, compared to their relatively low density in physiological organs, represents the molecular basis for in vivo imaging and targeted radionuclide therapy with radiolabelled peptide-based probes. The prototypes are analogs of somatostatin which are routinely used in the clinic. More recent developments include somatostatin analogs with a broader receptor subtype profile or with antagonistic properties. Many other peptide families such as bombesin, cholecystokinin/gastrin, glucagon-like peptide-1 (GLP-1)/exendin, arginine-glycine-aspartic acid (RGD) etc. have been explored during the last few years and quite a number of potential radiolabelled probes have been derived from them. On the other hand, a variety of strategies and optimized protocols for efficient labelling of peptides with clinically relevant radionuclides such as {sup 99m}Tc, M{sup 3+} radiometals ({sup 111}In, {sup 86/90}Y, {sup 177}Lu, {sup 67/68}Ga), {sup 64/67}Cu, {sup 18}F or radioisotopes of iodine have been developed. The labelling approaches include direct labelling, the use of bifunctional chelators or prosthetic groups. The choice of the labelling approach is driven by the nature and the chemical properties of the radionuclide. Additionally, chemical strategies, including modification of the amino acid sequence and introduction of linkers/spacers with different characteristics, have been explored for the improvement of the overall performance of the radiopeptides, e.g. metabolic stability and pharmacokinetics. Herein, we discuss the development of peptides as radiopharmaceuticals starting from the choice of the labelling method and the conditions to the design and optimization of the peptide probe, as well as some recent developments, focusing on a selected list of peptide families, including somatostatin

  13. Assessment of antimicrobial activity of polyazolidinammonium modified by iodine hydrate ions depending on its physical and chemical characteristics.

    Directory of Open Access Journals (Sweden)

    Vakaraeva M.M.

    2015-09-01

    Full Text Available Aim: to study antimicrobial activity of variants of polymeric compound polyazolidinammonium modified by iodine hydrate-ions (PAAG-M, depending on the polymeric chain length and concentration of the iodine hydrate-ions against standard strains of gram-positive and gram-negative bacteria as well as microscopic fungi. Materials and methods. Minimum inhibitory concentrations of all variants of the polymeric compound for tested microbial strains have been determined by using serial dilution method. Results. High sensitivity of Eschehchia coli 113-13 and Pseudomonas aeruginosa ATCC 27853 was shown to the variants of PAAG-M with molecular weight <100 and 100-200 kD. Staphylococcus aureus 209 P was more sensitive to the variants with molecular weight 200-350 and 400-500 kD. Direct relation of sensitivity was demonstrated for all microbial strains on the increase of iodine hydrate-ions concentration in the polymeric compound. Standard strain Candida albicans 13108 was sensitive to variants of the polymer with maximum iodine hydrate-ions concentration. Conclusion. The received results allow to carry out a choice of the most effective chemotherapeutic antimicrobic preparations depending on biological properties of the activator of infectious process.

  14. The Role of Genotypes That Modify the Toxicity of Chemical Mutagens in the Risk for Myeloproliferative Neoplasms

    Directory of Open Access Journals (Sweden)

    Carol Ann Gross-Davis

    2015-02-01

    Full Text Available Background: The etiology of myeloproliferative neoplasms (MPN (polycythemia vera; essential thrombocythemia; primary myelofibrosis is unknown, however they are associated with a somatic mutation—JAK2 V617F—suggesting a potential role for environmental mutagens. Methods: We conducted a population-based case-control study in three rural Pennsylvania counties of persons born 1921–1968 and residing in the area between 2000–2008. Twenty seven MPN cases and 292 controls were recruited through random digit dialing. Subjects were genotyped and odds ratios estimated for a select set of polymorphisms in environmentally sensitive genes that might implicate specific environmental mutagens if found to be associated with a disease. Results: The presence of NAT2 slow acetylator genotype, and CYP1A2, GSTA1, and GSTM3 variants were associated with an average 3–5 fold increased risk. Conclusions: Exposures, such as to aromatic compounds, whose toxicity is modified by genotypes associated with outcome in our analysis may play a role in the environmental etiology of MPNs.

  15. Long-Term Performance of Chemically and Physically Modified Activated Carbons in Air Cathodes of Microbial Fuel Cells

    KAUST Repository

    Zhang, Xiaoyuan

    2014-07-31

    © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Activated carbon (AC) is a low-cost and effective catalyst for oxygen reduction in air cathodes of microbial fuel cells (MFCs), but its performance must be maintained over time. AC was modified by three methods: 1)pyrolysis with iron ethylenediaminetetraacetic acid (AC-Fe), 2)heat treatment (AC-heat), and 3)mixing with carbon black (AC-CB). The maximum power densities after one month with these AC cathodes were 35% higher with AC-Fe (1410±50mW m-2) and AC-heat (1400±20mW m-2), and 16% higher with AC-CB (1210±30mW m-2) than for plain AC (1040±20mW m-2), versus 1270±50mW m-2 for a Pt control. After 16months, the Pt cathodes produced only 250±10mW m-2. However, the AC-heat and AC-CB cathodes still produced 960-970mW m-2, whereas plain AC produced 860±60mW m-2. The performance of the AC cathodes was restored to >85% of the initial maximum power densities by cleaning with a weak acid solution. Based on cost considerations among the AC materials, AC-CB appears to be the best choice for long-term performance.

  16. Convenient and scalable synthesis of fmoc-protected Peptide nucleic Acid backbone.

    Science.gov (United States)

    Feagin, Trevor A; Shah, Nirmal I; Heemstra, Jennifer M

    2012-01-01

    The peptide nucleic acid backbone Fmoc-AEG-OBn has been synthesized via a scalable and cost-effective route. Ethylenediamine is mono-Boc protected, then alkylated with benzyl bromoacetate. The Boc group is removed and replaced with an Fmoc group. The synthesis was performed starting with 50 g of Boc anhydride to give 31 g of product in 32% overall yield. The Fmoc-protected PNA backbone is a key intermediate in the synthesis of nucleobase-modified PNA monomers. Thus, improved access to this molecule is anticipated to facilitate future investigations into the chemical properties and applications of nucleobase-modified PNA. PMID:22848796

  17. Bio-compatibility, surface and chemical characterization of glow discharge plasma modified ZnO nanocomposite polycarbonate

    International Nuclear Information System (INIS)

    Bio compatibility is an important issue for synthesis of biomedical devices, which can be tested by bioadoptability and creations of active site to enhance the bacterial/cell growth in biomedical devices. Hence a systematic study was carried out to characterize the effects of Nitrogen ion plasma for creations of active site in nano composite polymer membrane. Nano particles of ZnO are synthesized by chemical root, using solution casting nano composite polymeric membranes were prepared and treated with Nitrogen ion plasma. These membranes were characterized by different technique such as optical microscopy, SEM- Scanning electron microscope, optical transmittance, Fourier transform infrared spectroscopy. Then biocompatibility for membranes was tested by testing of bio-adoptability of membrane

  18. Metalorganic chemical vapor deposition of anatase titanium dioxide on Si: Modifying the interface by pre-oxidation

    Science.gov (United States)

    Sandell, A.; Andersson, M. P.; Johansson, M. K.-J.; Karlsson, P. G.; Alfredsson, Y.; Schnadt, J.; Siegbahn, H.; Uvdal, P.

    2003-04-01

    The formation of TiO 2 films on clean and pre-oxidized Si(1 1 1) through chemical vapor deposition of titanium(IV) isopropoxide (TTIP) in ultra-high vacuum has been examined by synchrotron radiation photoelectron spectroscopy, X-ray absorption spectroscopy (XAS) and scanning tunneling microscopy. In both cases, TTIP deposition at 500 °C eventually results in an anatase TiO 2 film with a carbon-free surface and the surface morphology of the anatase films is very similar. By using a novel way of combining photoemission and XAS data, it is demonstrated that the two situations have substantially different interfacial properties. Pre-oxidation of the surface at 500 °C passivates the surface so that the thickness of the amorphous TiSi xO y interface layer decreases from 30-35 to 15-25 Å and eliminates the formation of interfacial carbon completely.

  19. Effect of calf feeding regimes and diet EDTA on physico-chemical characteristics of veal stored under modified atmospheres.

    Science.gov (United States)

    Gariépy, C; Delaquis, P J; Pommier, S; De Passillé, A M; Fortin, J; Lapierre, H

    1998-05-01

    Physico-chemical characteristics of veal from 30 calves allotted to five different rations with respect to iron bioavailability were evaluated at packaging and after 2 and 4 weeks of storage under both 100% CO(2) and 100% N(2). The five diets were 'Milk', 'Grain', 'Mix' (combination of Milk and Grain) and 'Mix + EDTA' and 'Grain + EDTA' where 15 mg EDTA were added per mg Fe in the feed concentrate. Diet EDTA was generally more influential on veal quality than storage treatments. The chelator caused an unexpected pH drop in veal stored four weeks irrespective of storage conditions (p ≤ 0.05). However, the colour, texture and flavour of meat from animals fed EDTA in the Grain- and Mix-ration was equivalent to that of Milk-fed veal (p ≤ 0.05). The EDTA treatments also improved the appearance of veal under anoxic atmospheres. Upon storage however, the chelator increased veal drip losses (p ≤ 0.05) and also cooking losses from Grain-fed calves (p ≤ 0.05). Packaging under CO(2) decreased pH (p ≤ 0.05) and increased drip losses (p ≤ 0.05) but did not alter other physico-chemical parameters. Dietary treatments had no effect on shear forces (p > 0.05) which decreased after two weeks in storage (p ≤ 0.05) independent of gas atmospheres. Overall, the quality characteristics of pale veal were obtained following addition of EDTA in Grain- and Mix-fed animals and were maintained in storage. This approach looks promising for the veal industry but warrants further research. PMID:22063188

  20. Review of long-term adverse effects associated with the use of chemically-modified animal and nonanimal source hyaluronic acid dermal fillers

    Directory of Open Access Journals (Sweden)

    Paul C Edwards

    2007-01-01

    Full Text Available Paul C Edwards1, John E Fantasia21Associate Professor (Clinical, Department of Periodontics and Oral Medicine, Pathology and Oncology, University of Michigan School of Dentistry, Ann Arbor MI, USA; 2Chief, Division of Oral Pathology, Department of Dental Medicine, Long Island Jewish Medical Center, New Hyde Park, NY, USAAbstract: Although only recently introduced, chemically-modified hyaluronic acid dermal fillers have gained widespread acceptance as “redefining” dermal fillers in the fields of dermatology and cosmetic facial surgery. Although hyaluronic acid-based dermal fillers have a low overall incidence of long term side effects, occasional adverse outcomes, ranging from chronic lymphoplasmacytic inflammatory reactions to classic foreign body-type granulomatous reactions have been documented. These long-term adverse events are reviewed.Keywords: hyaluronic acid, Restylane®, Hylaform®, injectable dermal filler, foreign body reaction, granuloma

  1. Electron transfer modifies chemical properties of C70 fullerene surface: An ab initio molecular dynamics study of C70O3 molozonides doped with light atoms

    Science.gov (United States)

    Bil, Andrzej; Hutter, Jürg; Morrison, Carole A.

    2014-06-01

    Light metal atoms such as Li, K (electronic state 2S1/2) or Ca (1S0) encapsulated in a C70 cage considerably modifies the chemical properties of the fullerene surface due to metal-to-cage electron transfer. H-doped and anion ozonide systems were also considered to validate the electron transfer hypothesis. The relative stabilities of the eight isomers of the C70O3 molozonide series at room temperature depend on the identity of the endohedral guest, as was the preferred channel for thermal decomposition. No electron transfer was observed for the complex N@C70 where the fullerene acts as an inert container for the 4S3/2 radical.

  2. Determination of vanadium(V) by direct automatic potentiometric titration with EDTA using a chemically modified electrode as a potentiometric sensor.

    Science.gov (United States)

    Quintar, S E; Santagata, J P; Cortinez, V A

    2005-10-15

    A chemically modified electrode (CME) was prepared and studied as a potentiometric sensor for the end-point detection in the automatic titration of vanadium(V) with EDTA. The CME was constructed with a paste prepared by mixing spectral-grade graphite powder, Nujol oil and N-2-naphthoyl-N-p-tolylhydroxamic acid (NTHA). Buffer systems, pH effects and the concentration range were studied. Interference ions were separated by applying a liquid-liquid extraction procedure. The CME did not require any special conditioning before using. The electrode was constructed with very inexpensive materials and was easily made. It could be continuously used, at least two months without removing the paste. Automatic potentiometric titration curves were obtained for V(V) within 5 x 10(-5) to 2 x 10(-3)M with acceptable accuracy and precision. The developed method was applied to V(V) determination in alloys for hip prosthesis. PMID:18970248

  3. Low temperature deposition and effect of plasma power on tin oxide thin films prepared by modified plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    This work presents low temperature (200 and 300 deg. C) thin film deposition of tin oxide (SnO2) using modified plasma enhanced chemical vapor deposition as a function of radio frequency power (100 - 500 W). Stannic chloride (SnCl4) was used as precursor and oxygen (O2, 300 SCCM) as reactant gas. Fine granular morphology was observed with tetragonal rutile structure grown along the [110] direction, at all the deposition conditions. Higher plasma power resulted in smoother morphology, improved crystallinity, and enhanced conductivity. Electrical resistivity value of as low as ∼0.01 Ω cm was obtained at the deposition temperature of 300 deg. C and 250 W of plasma power

  4. Extracellular biosynthesis of gadolinium oxide (Gd2O3 nanoparticles, their biodistribution and bioconjugation with the chemically modified anticancer drug taxol

    Directory of Open Access Journals (Sweden)

    Shadab Ali Khan

    2014-03-01

    Full Text Available As a part of our programme to develop nanobioconjugates for the treatment of cancer, we first synthesized extracellular, protein-capped, highly stable and well-dispersed gadolinium oxide (Gd2O3 nanoparticles by using thermophilic fungus Humicola sp. The biodistribution of the nanoparticles in rats was checked by radiolabelling with Tc-99m. Finally, these nanoparticles were bioconjugated with the chemically modified anticancer drug taxol with the aim of characterizing the role of this bioconjugate in the treatment of cancer. The biosynthesized Gd2O3 nanoparticles were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM, X-ray diffraction (XRD and X-ray photoemission spectroscopy (XPS. The Gd2O3–taxol bioconjugate was confirmed by UV–vis spectroscopy and fluorescence microscopy and was purified by using high performance liquid chromatography (HPLC.

  5. Fatigue behavior of Ti-6Al-4V alloy in saline solution with the surface modified at a micro- and nanoscale by chemical treatment.

    Science.gov (United States)

    Claros, Cesar Adolfo Escobar; Oliveira, Diego Pedreira; Campanelli, Leonardo Contri; Pereira da Silva, Paulo Sergio Carvalho; Bolfarini, Claudemiro

    2016-10-01

    This work evaluated the influence of the surface modification using acid etching combined with alkaline treatment on the fatigue strength of Ti-6Al-4V ELI alloy. The topography developed by chemical surface treatments (CST) was examined by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Increased roughness and effective surface area were investigated and compared with the Ti-6Al-4V samples without modification. Surface composition was analyzed by energy dispersive X-ray spectroscopy (EDS). Axial fatigue resistance of polished and modified surfaces was determined by stepwise load increase tests and staircase test method. Light microscopy and SEM were employed to examine the fracture surface of the tested specimens. According to the results, a similar fatigue behavior was found and a negligible difference in the fatigue crack nucleation was observed for the Ti-6Al-4V with CST in comparison to the samples without treatment. PMID:27287139

  6. Design, synthesis and biological activity of new polyenolic inhibitors of matrix metalloproteinases: a focus on chemically-modified curcumins.

    Science.gov (United States)

    Zhang, Yu; Gu, Ying; Lee, Hsi-Ming; Hambardjieva, Elena; Vranková, Kveta; Golub, Lorne M; Johnson, Francis

    2012-01-01

    Matrix metalloproteinases (MMPs) are essential for the degradation and turnover of components of the extracellular matrix (ECM) and, when pathologically elevated, mediate connective tissue loss (including bone destruction) in various inflammatory and other diseases. Tetracyclines (TCs) are known inhibitors of mammalian-derived MMPs, and non-antibiotic formulations of Doxycycline are FDA-approved to treat periodontitis and the chronic inflammatory skin disease, rosacea. Because the C-11/ C-12 diketonic moiety of the tetracyclines is primarily responsible, through zinc-binding, for MMP inhibition, we have uniquely modified curcumin as a "core" molecule, since it contains a similar enolic system and is known to have beneficial effects in diseases where connective-tissue loss occurs. Specifically we have developed new congeners which exhibit improved zinc-binding and solubility, and potent reduction of excessive MMP levels and activity. We now describe a series of curcuminoid bi- and tri-carbonylmethanes in which all of these properties are substantially improved. An N-phenylaminocarbonyl derivative of bis-demethoxycurcumin (CMC2.24) was selected as the "lead" substance because it showed superior potency in vitro (i.e., the lowest IC(50)) against a series of neutral proteases (MMPs) associated with tissue erosion. Moreover, CMC2.24 administered to diabetic rats orally (30mg/kg), reduced the secretion of pathologically-excessive levels of MMP-9 to normal in cultured peritoneal macrophages with no evidence of toxicity. Thus, this (and other similar novel) compound(s) may be useful in various diseases of connective-tissue loss. PMID:22830350

  7. Chitosan hydrolysis using chitosan decomposition enzyme chemically modified by polyalkylene oxide - maleic anhydride copolymers; Poriarukirenoshido, musui marein kankyojugotai ni yotte kagaku shushoku shita kitosan bunkai koso wo mochiita kitosan kasui bunkai

    Energy Technology Data Exchange (ETDEWEB)

    Araya, Yoshitsune; Kajiuchi, Toshio; Hinode, Hirofumi; Haku, Tatsuto

    1999-01-05

    Pectinase on the market, which has chitosan hydrolysis activation, was chemically modified using two polyalkylene oxides - maleic anhydride copolymers of different hydrophilicity; the effect of the chemical modification of enzymes on the chitosan hydrolysis characteristics was experimentally investigated. As the characteristics, the initial activation of enzymes, the dynamics constant based on the Michaelis-Menten mechanism, thermal stability, and the variation of generating, reduced sugar quantities with time by the hydrolysis reaction were investigated. The result clarified that the hydrophilicity of modifiers and the modification rate of enzymes affected greatly the above enzymes characteristics. The initial activation of highly chemically modified enzymes was low regardless of the hydrophilicity of modifiers. It was confirmed that the Michaelis-Menten constant decreased, i.e. the affinity of modified enzymes and substrate increased, and that the thermal stability rose at 40 degrees C. It was also known that the chitosan hydrolysis reaction continued for a longer time when the modified enzyme was used. The above enzyme characteristics improved greatly when the modification rate raised using the hydrophilic modifier AKM-1510, polyalkylene oxide chain of which consists of only ethylene oxide. (translated by NEDO)

  8. Characterization of bioactive RGD peptide immobilized onto poly(acrylic acid) thin films by plasma polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Hyun Suk; Ko, Yeong Mu; Shim, Jae Won [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, Gwangju (Korea, Republic of); Lim, Yun Kyong; Kook, Joong-Ki [Department of Oral Biochemistry, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Cho, Dong-Lyun [School of Applied Chemical Engineering and Center for Functional Nano Fine Chemicals, Chonnam National University, Gwangju (Korea, Republic of); Kim, Byung Hoon, E-mail: kim5055@chosun.ac.kr [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, Gwangju (Korea, Republic of)

    2010-11-01

    Plasma surface modification can be used to improve the surface properties of commercial pure Ti by creating functional groups to produce bioactive materials with different surface topography. In this study, a titanium surface was modified with acrylic acid (AA) using a plasma treatment and immobilized with bioactive arginine-glycine-aspartic acid (RGD) peptide, which may accelerate the tissue integration of bone implants. Both terminals containing the -NH{sub 2} of RGD peptide sequence and -COOH of poly(acrylic acid) (PAA) thin film were combined with a covalent bond in the presence of 1-ethyl-3-3-dimethylaminopropyl carbodiimide (EDC). The chemical structure and morphology of AA film and RGD immobilized surface were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All chemical analysis showed full coverage of the Ti substrate with the PAA thin film containing COOH groups and the RGD peptide. The MC3T3-E1 cells were cultured on each specimen, and the cell alkaline phosphatase (ALP) activity were examined. The surface-immobilized RGD peptide has a significantly increased the ALP activity of MC3T3-E1 cells. These results suggest that the RGD peptide immobilization on the titanium surface has an effect on osteoblastic differentiation of MC3T3-E1 cells and potential use in osteo-conductive bone implants.

  9. Characterization of bioactive RGD peptide immobilized onto poly(acrylic acid) thin films by plasma polymerization

    International Nuclear Information System (INIS)

    Plasma surface modification can be used to improve the surface properties of commercial pure Ti by creating functional groups to produce bioactive materials with different surface topography. In this study, a titanium surface was modified with acrylic acid (AA) using a plasma treatment and immobilized with bioactive arginine-glycine-aspartic acid (RGD) peptide, which may accelerate the tissue integration of bone implants. Both terminals containing the -NH2 of RGD peptide sequence and -COOH of poly(acrylic acid) (PAA) thin film were combined with a covalent bond in the presence of 1-ethyl-3-3-dimethylaminopropyl carbodiimide (EDC). The chemical structure and morphology of AA film and RGD immobilized surface were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All chemical analysis showed full coverage of the Ti substrate with the PAA thin film containing COOH groups and the RGD peptide. The MC3T3-E1 cells were cultured on each specimen, and the cell alkaline phosphatase (ALP) activity were examined. The surface-immobilized RGD peptide has a significantly increased the ALP activity of MC3T3-E1 cells. These results suggest that the RGD peptide immobilization on the titanium surface has an effect on osteoblastic differentiation of MC3T3-E1 cells and potential use in osteo-conductive bone implants.

  10. Characterization of bioactive RGD peptide immobilized onto poly(acrylic acid) thin films by plasma polymerization

    Science.gov (United States)

    Seo, Hyun Suk; Ko, Yeong Mu; Shim, Jae Won; Lim, Yun Kyong; Kook, Joong-Ki; Cho, Dong-Lyun; Kim, Byung Hoon

    2010-11-01

    Plasma surface modification can be used to improve the surface properties of commercial pure Ti by creating functional groups to produce bioactive materials with different surface topography. In this study, a titanium surface was modified with acrylic acid (AA) using a plasma treatment and immobilized with bioactive arginine-glycine-aspartic acid (RGD) peptide, which may accelerate the tissue integration of bone implants. Both terminals containing the -NH2 of RGD peptide sequence and -COOH of poly(acrylic acid) (PAA) thin film were combined with a covalent bond in the presence of 1-ethyl-3-3-dimethylaminopropyl carbodiimide (EDC). The chemical structure and morphology of AA film and RGD immobilized surface were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All chemical analysis showed full coverage of the Ti substrate with the PAA thin film containing COOH groups and the RGD peptide. The MC3T3-E1 cells were cultured on each specimen, and the cell alkaline phosphatase (ALP) activity were examined. The surface-immobilized RGD peptide has a significantly increased the ALP activity of MC3T3-E1 cells. These results suggest that the RGD peptide immobilization on the titanium surface has an effect on osteoblastic differentiation of MC3T3-E1 cells and potential use in osteo-conductive bone implants.

  11. Cysteine-10 on 17 β -Hydroxysteroid Dehydrogenase 1 Has Stabilizing Interactions in the Cofactor Binding Region and Renders Sensitivity to Sulfhydryl Modifying Chemicals.

    Science.gov (United States)

    Nashev, Lyubomir G; Atanasov, Atanas G; Baker, Michael E; Odermatt, Alex

    2013-01-01

    17 β -Hydroxysteroid dehydrogenase type 1 (17 β -HSD1) catalyzes the conversion of estrone to the potent estrogen estradiol. 17 β -HSD1 is highly expressed in breast and ovary tissues and represents a prognostic marker for the tumor progression and survival of patients with breast cancer and other estrogen-dependent tumors. Therefore, the enzyme is considered a promising drug target against estrogen-dependent cancers. For the development of novel inhibitors, an improved understanding of the structure-function relationships is essential. In the present study, we examined the role of a cysteine residue, Cys(10), in the Rossmann-fold NADPH binding region, for 17 β -HSD1 function and tested the sensitivity towards sulfhydryl modifying chemicals. 3D structure modeling revealed important interactions of Cys(10) with residues involved in the stabilization of amino acids of the NADPH binding pocket. Analysis of enzyme activity revealed that 17 β -HSD1 was irreversibly inhibited by the sulfhydryl modifying agents N-ethylmaleimide (NEM) and dithiocarbamates. Preincubation with increasing concentrations of NADPH protected 17 β -HSD1 from inhibition by these chemicals. Cys(10)Ser mutant 17 β -HSD1 was partially protected from inhibition by NEM and dithiocarbamates, emphasizing the importance of Cys(10) in the cofactor binding region. Substitution of Cys(10) with serine resulted in a decreased protein half-life, without significantly altering kinetic properties. Despite the fact that Cys(10) on 17 β -HSD1 seems to have limited potential as a target for new enzyme inhibitors, the present study provides new insight into the structure-function relationships of this enzyme. PMID:24348564

  12. Cysteine-10 on 17β-Hydroxysteroid Dehydrogenase 1 Has Stabilizing Interactions in the Cofactor Binding Region and Renders Sensitivity to Sulfhydryl Modifying Chemicals

    Directory of Open Access Journals (Sweden)

    Lyubomir G. Nashev

    2013-01-01

    Full Text Available 17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1 catalyzes the conversion of estrone to the potent estrogen estradiol. 17β-HSD1 is highly expressed in breast and ovary tissues and represents a prognostic marker for the tumor progression and survival of patients with breast cancer and other estrogen-dependent tumors. Therefore, the enzyme is considered a promising drug target against estrogen-dependent cancers. For the development of novel inhibitors, an improved understanding of the structure-function relationships is essential. In the present study, we examined the role of a cysteine residue, Cys10, in the Rossmann-fold NADPH binding region, for 17β-HSD1 function and tested the sensitivity towards sulfhydryl modifying chemicals. 3D structure modeling revealed important interactions of Cys10 with residues involved in the stabilization of amino acids of the NADPH binding pocket. Analysis of enzyme activity revealed that 17β-HSD1 was irreversibly inhibited by the sulfhydryl modifying agents N-ethylmaleimide (NEM and dithiocarbamates. Preincubation with increasing concentrations of NADPH protected 17β-HSD1 from inhibition by these chemicals. Cys10Ser mutant 17β-HSD1 was partially protected from inhibition by NEM and dithiocarbamates, emphasizing the importance of Cys10 in the cofactor binding region. Substitution of Cys10 with serine resulted in a decreased protein half-life, without significantly altering kinetic properties. Despite the fact that Cys10 on 17β-HSD1 seems to have limited potential as a target for new enzyme inhibitors, the present study provides new insight into the structure-function relationships of this enzyme.

  13. Chemical synthesis of the 5-taurinomethyl(-2-thio)uridine modified anticodon arm of the human mitochondrial tRNA(Leu(UUR)) and tRNA(Lys).

    Science.gov (United States)

    Leszczynska, Grazyna; Leonczak, Piotr; Wozniak, Karolina; Malkiewicz, Andrzej

    2014-06-01

    5-Taurinomethyluridine (τm(5)U) and 5-taurinomethyl-2-thiouridine (τm(5)s(2)U) are located at the wobble position of human mitochondrial (hmt) tRNA(Leu(UUR)) and tRNA(Lys), respectively. Both hypermodified units restrict decoding of the third codon letter to A and G. Pathogenic mutations in the genes encoding hmt-tRNA(Leu(UUR)) and hmt-tRNA(Lys) are responsible for the loss of the discussed modifications and, as a consequence, for the occurrence of severe mitochondrial dysfunctions (MELAS, MERRF). Synthetic oligoribonucleotides bearing modified nucleosides are a versatile tool for studying mechanisms of genetic message translation and accompanying pathologies at nucleoside resolution. In this paper, we present site-specific chemical incorporation of τm(5)U and τm(5)s(2)U into 17-mers related to the sequence of the anticodon arms hmt-tRNA(Leu(UUR)) and hmt-tRNA(Lys), respectively employing phosphoramidite chemistry on CPG support. Selected protecting groups for the sulfonic acid (4-(tert-butyldiphenylsilanyloxy)-2,2-dimethylbutyl) and the exoamine function (-C(O)CF3) are compatible with the blockage of the canonical monomeric units. The synthesis of τm(5)s(2)U-modified RNA fragment was performed under conditions eliminating the formation of side products of 2-thiocarbonyl group oxidation and/or oxidative desulphurization. The structure of the final oligomers was confirmed by mass spectroscopy and enzymatic cleavage data. PMID:24757169

  14. Effects of copper precursor concentration on the growth of cupric oxide nanorods for photoelectrode using a modified chemical bath deposition method

    International Nuclear Information System (INIS)

    Highlights: • CuO nanorod photoelectrodes were prepared by modified CBD method. • The CuO nanorods were vertically grown with a high growth rate. • Effects of precursor concentration on the CuO nanorods were investigated. - Abstract: In this study, vertically aligned CuO nanorods were grown using a modified chemical bath deposition method with various copper precursor concentrations. The morphological, structural, optical and photoelectrochemical properties of the synthesized CuO samples were characterized using a field-emission scanning electron microscope, an X-ray diffractometer, a UV–visible spectrometer and a three-electrode potentiostat, respectively. The growth rates of the samples varied from 4.3 to 500 nm/min with the varying precursor concentrations. The vertically well-grown CuO nanorods exhibited one-dimensional growth along the (0 2 0) plane. We obtained a maximum photocurrent density of −1.05 mA/cm2 at −0.6 V (vs. SCE) from the CuO nanorod photoelectrode grown using the 10 mM copper precursor concentration

  15. Effects of copper precursor concentration on the growth of cupric oxide nanorods for photoelectrode using a modified chemical bath deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Hee-bong [Department of Nano Science and Engineering, High Safety Vehicle Core Technology Research Center, Inje University, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, Hyukhyun, E-mail: hhryu@inje.ac.kr [Department of Nano Science and Engineering, High Safety Vehicle Core Technology Research Center, Inje University, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Lee, Won-Jae [Department of Materials and Components Engineering, Dong-Eui University, Busan 614-714 (Korea, Republic of)

    2015-01-25

    Highlights: • CuO nanorod photoelectrodes were prepared by modified CBD method. • The CuO nanorods were vertically grown with a high growth rate. • Effects of precursor concentration on the CuO nanorods were investigated. - Abstract: In this study, vertically aligned CuO nanorods were grown using a modified chemical bath deposition method with various copper precursor concentrations. The morphological, structural, optical and photoelectrochemical properties of the synthesized CuO samples were characterized using a field-emission scanning electron microscope, an X-ray diffractometer, a UV–visible spectrometer and a three-electrode potentiostat, respectively. The growth rates of the samples varied from 4.3 to 500 nm/min with the varying precursor concentrations. The vertically well-grown CuO nanorods exhibited one-dimensional growth along the (0 2 0) plane. We obtained a maximum photocurrent density of −1.05 mA/cm{sup 2} at −0.6 V (vs. SCE) from the CuO nanorod photoelectrode grown using the 10 mM copper precursor concentration.

  16. Inhibition of Henipavirus fusion and infection by heptad-derived peptides of the Nipah virus fusion glycoprotein

    Directory of Open Access Journals (Sweden)

    Eaton Bryan T

    2005-07-01

    Full Text Available Abstract Background The recent emergence of four new members of the paramyxovirus family has heightened the awareness of and re-energized research on new and emerging diseases. In particular, the high mortality and person to person transmission associated with the most recent Nipah virus outbreaks, as well as the very recent re-emergence of Hendra virus, has confirmed the importance of developing effective therapeutic interventions. We have previously shown that peptides corresponding to the C-terminal heptad repeat (HR-2 of the fusion envelope glycoprotein of Hendra virus and Nipah virus were potent inhibitors of both Hendra virus and Nipah virus-mediated membrane fusion using recombinant expression systems. In the current study, we have developed shorter, second generation HR-2 peptides which include a capped peptide via amidation and acetylation and two poly(ethylene glycol-linked (PEGylated peptides, one with the PEG moity at the C-terminus and the other at the N-terminus. Here, we have evaluated these peptides as well as the corresponding scrambled peptide controls in Nipah virus and Hendra virus-mediated membrane fusion and against infection by live virus in vitro. Results Unlike their predecessors, the second generation HR-2 peptides exhibited high solubility and improved synthesis yields. Importantly, both Nipah virus and Hendra virus-mediated fusion as well as live virus infection were potently inhibited by both capped and PEGylated peptides with IC50 concentrations similar to the original HR-2 peptides, whereas the scrambled modified peptides had no inhibitory effect. These data also indicate that these chemical modifications did not alter the functional properties of the peptides as inhibitors. Conclusion Nipah virus and Hendra virus infection in vitro can be potently blocked by specific HR-2 peptides. The improved synthesis and solubility characteristics of the second generation HR-2 peptides will facilitate peptide synthesis for pre

  17. Metal modified graphite. An innovative material for systems converting electro-chemical energy; Metallmodifizierter Graphit. Ein innovativer Werkstoff fuer Systeme zur elektrochemischen Energieumwandlung

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Peter

    2007-07-23

    The work deals with metal modification of graphite electrodes in a water-acid electrolyte solution. The target is to improve the catalytic properties of graphite electrodes as they are applied in redox storage batteries for storing electric energy. Different carbon and graphite materials were used and coated electro-chemically with different metals. After being coated with metal the graphite and carbon electrodes were investigated in terms of changing their catalytic properties by means of impedance measurements. It was shown, a metal coating without a prior activation with electro-chemical oxidation-reduction cycles only results in a low or zero increase of the catalytic properties. Investigations at the electrode material glass carbon showed, a prior activation of the electrode surface by means of electro-chemical oxidation-reduction cycles decreases the penetration resistance. The activation of the glass carbon surface prior to the surface coating with metal is favourable to the electro-chemical properties of the metal-modified electrode. All carbon types, which were used in this work, could be activated at a different level by means of electro-chemical oxidation-reduction cycles depending on the carbon type. The investigations further showed that the edge levels of the carbon were activated by means of the electro-chemical oxidation-reduction cycles. The metal precipitation favourably occurs at the activated positions. (orig.) [German] Die Arbeit befasst sich mit der Metallmodifizierung von Graphitelektroden in waessriger saurer Elektrolytloesung. Ziel ist es die katalytischen Eigenschaften von Graphitelektroden wie sie in Redoxspeicherbatterien zur Speicherung von elektrischer Energie eingesetzt werden zu verbessern. Fuer die Untersuchungen wurden unterschiedliche Kohlenstoff und Graphitmaterialien eingesetzt, die elektrochemisch mit verschiedenen Metallen belegt wurden. Die Graphit- und Kohlenstoffelektroden wurden nach der Metallbelegung durch

  18. A novel minor groove binding reagent designed to serve as a "truck" to carry DNA modifying moieties into the major groove.

    Science.gov (United States)

    Xue, T; Browne, K A; Bruice, T C

    1995-01-01

    A site selective DNA minor groove binding tripyrrole peptide has been synthesized as a "truck" to place chemical functionalities into the major groove which are capable of physically modifying DNA, acting as catalysts to hydrolyze DNA, or effectively protecting DNA from various DNA modifying enzymes. The equilibrium dissociation constants for the binding of this peptide to an A3T3 dsDNA binding site have been determined to be nanomolar, and they are compared to the constants for other minor groove binding agents. PMID:7711109

  19. Boron Nitride Nanosheets (BNNSs) Chemically Modified by "Grafting-From" Polymerization of Poly(caprolactone) for Thermally Conductive Polymer Composites.

    Science.gov (United States)

    Lee, Jinseong; Jung, Haejong; Yu, Seunggun; Man Cho, Suk; Tiwari, Vimal K; Babu Velusamy, Dhinesh; Park, Cheolmin

    2016-07-01

    To meet the growing demand for rapid heat dissipation in electronic devices to ensure their reliable performance with a high level of safety, many polymer composites with thermally conductive but electrically insulating 2D boron nitride nanosheets (BNNSs) are being developed. Here we present an efficient way to enhance the thermal conductivity (TC) of a polymer composite by means of "grafting-from" polymerization of a poly(caprolactone) (PCL) onto BNNSs. The BNNSs, which were exfoliated from bulk BN by means of ultra-sonication, were prepared by means of radical oxidation. These oxidized BNNSs (oxi-BNNSs) were employed as initiators for subsequent ring-opening polymerization of PCL, which successfully resulted in PCL chemically grafted onto BNNSs (PCL-g-BNNSs). The excellent dispersion of PCL-g-BNNSs in common solvents allowed us to readily fabricate a polymer composite that contained PCL-g-BNNSs embedded in a PCL matrix, and the composite showed TC values that were five and nine times greater in the out-of-plane and in-plane mode, respectively, than those of pristine PCL. PMID:27283727

  20. Prostaglandins can modify gamma-radiation and chemical induced cytotoxicity and genetic damage in vitro and in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Das, U.N.; Ramadevi, G.; Rao, K.P.; Rao, M.S. (Nizam' s Institute of Medical Sciences, Hyderabad (India))

    1989-12-01

    The effect of prostaglandin E1, E2, and F2 alpha on gamma-radiation, benzo(a)pyrene and diphenylhydantoin-induced cytotoxicity in vivo and genotoxicity in vitro was investigated. Prostaglandin E1 prevented both cytotoxic and genotoxic actions of all the three agents, where as both PGE2 and PGF2 alpha were ineffective. In fact, it was seen that both PGE2 and PGF2 alpha are genotoxic by themselves. Gamma-linolenic acid and dihomogamma-linolenic acid, the precursor of PGE1 were also as protective as that of PGE1, where as arachidonic acid, the precursor of 2 series PGs, has genotoxic actions to human lymphocytes in vitro. These results suggest that prostaglandins and their precursors can determine the susceptibility of cells to cytotoxic and genotoxic actions of chemicals and radiation. This study is particularly interesting since, it is known that some tumor cells contain excess of PGE2 and PGF2 alpha and many carcinogens can augment the synthesis of 2 series of PGs.

  1. Prostaglandins can modify gamma-radiation and chemical induced cytotoxicity and genetic damage in vitro and in vivo

    International Nuclear Information System (INIS)

    The effect of prostaglandin E1, E2, and F2 alpha on gamma-radiation, benzo(a)pyrene and diphenylhydantoin-induced cytotoxicity in vivo and genotoxicity in vitro was investigated. Prostaglandin E1 prevented both cytotoxic and genotoxic actions of all the three agents, where as both PGE2 and PGF2 alpha were ineffective. In fact, it was seen that both PGE2 and PGF2 alpha are genotoxic by themselves. Gamma-linolenic acid and dihomogamma-linolenic acid, the precursor of PGE1 were also as protective as that of PGE1, where as arachidonic acid, the precursor of 2 series PGs, has genotoxic actions to human lymphocytes in vitro. These results suggest that prostaglandins and their precursors can determine the susceptibility of cells to cytotoxic and genotoxic actions of chemicals and radiation. This study is particularly interesting since, it is known that some tumor cells contain excess of PGE2 and PGF2 alpha and many carcinogens can augment the synthesis of 2 series of PGs

  2. The synthesis and coupling of photoreactive collagen-based peptides to restore integrin reactivity to an inert substrate, chemically-crosslinked collagen.

    Science.gov (United States)

    Malcor, Jean-Daniel; Bax, Daniel; Hamaia, Samir W; Davidenko, Natalia; Best, Serena M; Cameron, Ruth E; Farndale, Richard W; Bihan, Dominique

    2016-04-01

    Collagen is frequently advocated as a scaffold for use in regenerative medicine. Increasing the mechanical stability of a collagen scaffold is widely achieved by cross-linking using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). However, this treatment consumes the carboxylate-containing amino acid sidechains that are crucial for recognition by the cell-surface integrins, abolishing cell adhesion. Here, we restore cell reactivity to a cross-linked type I collagen film by covalently linking synthetic triple-helical peptides (THPs), mimicking the structure of collagen. These THPs are ligands containing an active cell-recognition motif, GFOGER, a high-affinity binding site for the collagen-binding integrins. We end-stapled peptide strands containing GFOGER by coupling a short diglutamate-containing peptide to their N-terminus, improving the thermal stability of the resulting THP. A photoreactive Diazirine group was grafted onto the end-stapled THP to allow covalent linkage to the collagen film upon UV activation. Such GFOGER-derivatized collagen films showed restored affinity for the ligand-binding I domain of integrin α2β1, and increased integrin-dependent cell attachment and spreading of HT1080 and Rugli cell lines, expressing integrins α2β1 and α1β1, respectively. The method we describe has wide application, beyond collagen films or scaffolds, since the photoreactive diazirine will react with many organic carbon skeletons. PMID:26854392

  3. Post-Translational Modifications in Secreted Peptide Hormones in Plants

    OpenAIRE

    Matsubayashi, Yoshikatsu

    2010-01-01

    More than a dozen secreted peptides are now recognized as important hormones that coordinate and specify cellular functions in plants. Recent evidence has shown that secreted peptide hormones often undergo post-translational modification and proteolytic processing, which are critical for their function. Such ‘small post-translationally modified peptide hormones’ constitute one of the largest groups of peptide hormones in plants. This short review highlights recent progress in research on post...

  4. New dendrimer - Peptide host - Guest complexes: Towards dendrimers as peptide carriers

    DEFF Research Database (Denmark)

    Boas, Ulrik; Sontjens, S.H.M.; Jensen, Knud Jørgen; Christensen, J.B.; Meijer, E.W.

    2002-01-01

    Adamantyl urea and adamantyl thiourea modified poly(propylene imine) dendrimers act as hosts for N-terminal tert-butoxycarbonyl (Boc)-protected peptides and form chloroform-soluble complexes. investigations with NMR spectroscopy show that the peptide is bound to the dendrimer by ionic interactions...

  5. Chemo-enzymatic peptide synthesis : bioprocess engineering aspects

    OpenAIRE

    Vossenberg, P.

    2012-01-01

      Peptides, in particular oligopeptides, play an important role in the fields of health care, nutrition and cosmetics. Chemical synthesis is currently the most mature technique for the synthesis of peptides that range in length from 5 to 80 amino acids. Chemical synthesis is, however, expected to be more and more combined with enzyme-catalyzed synthesis, resulting in chemo-enzymatic approaches towards peptide synthesis. The racemization that hampers chemical synthesis can be prevented by...

  6. Construction of Lasso Peptide Fusion Proteins.

    Science.gov (United States)

    Zong, Chuhan; Maksimov, Mikhail O; Link, A James

    2016-01-15

    Lasso peptides are a family of ribosomally synthesized and post-translationally modified peptides (RiPPs) typified by an isopeptide-bonded macrocycle between the peptide N-terminus and an aspartate or glutamate side chain. The C-terminal portion of the peptide threads through the N-terminal macrocycle to give the characteristic lasso fold. Because of the inherent stability, both proteolytic and often thermal, of lasso peptides, we became interested in whether proteins could be fused to the free C-terminus of lasso peptides. Here, we demonstrate fusion of two model proteins, the artificial leucine zipper A1 and the superfolder variant of GFP, to the C-terminus of the lasso peptide astexin-1. Successful lasso cyclization of the N-terminus of these fusion proteins requires a flexible linker in between the C-terminus of the lasso peptide and the N-terminus of the protein of interest. The ability to fuse lasso peptides to a protein of interest is an important step toward phage and bacterial display systems for the high-throughput screening of lasso peptide libraries for new functions. PMID:26492187

  7. Modified spectrophotometric method for assay of angiotensin I-converting enzyme inhibitory activity of food derived peptides%改进的分光光度计法测定食源性多肽血管紧张素转化酶的抑制活性

    Institute of Scientific and Technical Information of China (English)

    高丹丹; 曹郁生; 麦曦

    2011-01-01

    在传统检测食源性多肽血管紧张素转化酶(ACE)抑制肽体外活性方法的基础上,结合纸层析测定马尿酸的方法对其进行改进,建立了一种新的分光光度法用于测定样品中ACE的抑制活性.结果表明:该方法确定的显色反应吸收波长为459 nm;最佳显色温度为40℃;最佳显色时间为30 min;最佳显色剂质量分数为0.5%;用卡托普利和有ACE抑制活性的棉籽蛋白肽作为样品进行检测验证,结果表明,此方法简便、灵敏、准确、重复性好,可用于筛选食源性ACE抑制肽.%A modified spectrophotometric assay was developed for determination of angiotensin I-converting enzyme (ACE) inhibitory activity of peptides derived from plant protein, which was based on the classical paper chromatography determination of hippuric acid (HA) content in the urine. By using the modified method, the maximum absorbance of HA was measured at 459 nm, and the optimum chromogenic reaction conditions were as follows: temperature of 40 ℃, time for 30 min, and the DAB concentration of 0. 5%. Captopril and cottonseed protein peptides showing antihypertensive activity as inhibitors of ACE were detected by this modified spectrophotometric assay. The result showed that the modified method was proved to be convenient, sensitive, accurate and reproducible, and it could be used for the screening of ACE inhibitory peptides derived from food proteins.

  8. Effects of the modified atmosphere and irradiation on the microbiological, physical-chemical and sensory characteristics of the 'minas frescal' cheese

    International Nuclear Information System (INIS)

    The experiment was divided into two parts. Initially, it was studied the 'Minas Frescal' cheeses packed under atmospheric air, modified atmosphere of 70% CO2 and 30% N2 (ATM) and vacuum. Second the cheeses packed under these three treatments had been radiated by doses of 2 KGy. In the two parts of the experiment, it was analyzed the microbial evolution and, the sensory and physical-chemical characteristics of the cheeses under the different treatments during a 4 deg C-storage. In the first phase of the experiment it was verified that the ATM and the vacuum decreased the intensity of the total population growth of aerobic mesophilic and psychotropic and had reduced the population of Staphylococcus positive coagulase, but they had not been efficient controlling the total coliforms and Escherichia coli, while in control all the populations had continuously grown, according to the sensory characteristics of the cheeses, color, odor and appearance. These characteristics were kept the same during the 40 days of storage, and the control decreased the acceptability levels gradually, being rejected in the 17th day. In the second part of the experiment, it was observed that a 2KGy-irradiation over the 'Minas Frescal' cheeses reduced the populations of aerobic mesophilic, aerobic and anaerobic psychotropic, Staphylococcus positive coagulase, total coliforms and Escherichia coli. The ATM and vacuum treatments were very efficient therefore they prevented the growth of these microorganisms during the storage, while in control, the aerobic mesophilic and psychotropic population grew during the storage. According to sensory aspects, the ATM treatment was the most efficient one, because it kept the appearance, texture and flavor for more than 43 days while the vacuum kept for 36 days and the control for only 8 days. The use of the irradiation with modified atmosphere and low temperatures of storage increased the shelf life of the cheeses, hindering the growth of the microbial

  9. Automated solid-phase peptide synthesis to obtain therapeutic peptides

    Directory of Open Access Journals (Sweden)

    Veronika Mäde

    2014-05-01

    Full Text Available The great versatility and the inherent high affinities of peptides for their respective targets have led to tremendous progress for therapeutic applications in the last years. In order to increase the drugability of these frequently unstable and rapidly cleared molecules, chemical modifications are of great interest. Automated solid-phase peptide synthesis (SPPS offers a suitable technology to produce chemically engineered peptides. This review concentrates on the application of SPPS by Fmoc/t-Bu protecting-group strategy, which is most commonly used. Critical issues and suggestions for the synthesis are covered. The development of automated methods from conventional to essentially improved microwave-assisted instruments is discussed. In order to improve pharmacokinetic properties of peptides, lipidation and PEGylation are described as covalent conjugation methods, which can be applied by a combination of automated and manual synthesis approaches. The synthesis and application of SPPS is described for neuropeptide Y receptor analogs as an example for bioactive hormones. The applied strategies represent innovative and potent methods for the development of novel peptide drug candidates that can be manufactured with optimized automated synthesis technologies.

  10. Chemically modified carbon paste and membrane sensors for the determination of benzethonium chloride and some anionic surfactants (SLES, SDS, and LABSA): Characterization using SEM and AFM.

    Science.gov (United States)

    Issa, Yousry M; Mohamed, Sabrein H; Baset, Mohamed Abd-El

    2016-08-01

    Chemically modified carbon-paste (CMCP) and membrane- sensors based on incorporating benzothonium-tetraphenylborate (BT-TPB) were constructed for the analysis of benzethonium chloride, and some other surfactants such as sodium lauryl ether sulphate (SLES), sodium dodecyl sulphate (SDS), and linear alkylbenzene sulphonic acid (LABSA). All sensors showed good sensitivity and reverse wide linearity over a concentration range of 5.97×10(-7) to 1.00×10(-3) and 5.96×10(-7) to 3.03×10(-3)molL(-1) with limit of detection of 3.92×10(-7)and 3.40×10(-7)molL(-1) for membrane and chemically modified carbon paste sensors, respectively, with respect to benzethonium chloride (BT.Cl). They could be used over a wide pH range of 2.0-10.0. The thermal coefficients of membrane and CMCP sensors are 5.40×10(-4), 1.17×10(-4)V/°C, respectively. The sensors indicated a wide selectivity over different inorganic cations. The effect of soaking on the surface morphology of the membrane sensor was studied using EDX-SEM and AFM techniques. The response time was <10s The freshly prepared, exhausted membrane, and CMCP sensors were successfully applied for the potentiometric determination of the pure BT.Cl solution. They were also used for the determination of its pharmaceutical formulation Dermoplast(®) antibacterial spray (20% benzocaine+0.2% benzethonium chloride) with recovery values ranging from 97.54±1.70 to 101.25±1.12 and from 96.32±2.49 to 101.23±2.15%. The second goal of these sensors is the potentiometric determination of different surfactants such as SLES, SDS, and LABSA with good recovery values using BT.Cl as a titrant in their pure forms, and in samples containing one of them (shampoo, Touri(®) dishwashing liquid, and waste water). The statistical analysis of the obtained data was studied. PMID:27216669

  11. Effect of modified atmosphere and vacuum packaging on selected chemical parameters of rainbow trout (Oncorhynchus mykiss and carp (Cyprinus carpio cuts freshness

    Directory of Open Access Journals (Sweden)

    Babić Jelena A.

    2014-01-01

    Full Text Available The purpose of food packing in modified atmosphere is to extend its sustainability by preventing both biochemical processes and growth of spoilage bacteria. Gases or their mixtures which are mostly used in the modified atmosphere food packing technology are carbon-dioxide (CO2, oxygen (O2 and nitrogen (N2. The aim of our research was to examine the influence of packaging in modified atmosphere and vacuum on the total volatile basic nitrogen (TVB-N content and pH in muscle of rainbow trout (Oncorhynchus mykiss and common carp (Cyprinus carpio, as well as to determine the most suitable gas mixtures for packing of these freshwater species. Three sample groups of trout and carp cuts were investigated. The first two groups were packaged in modified atmosphere with different gas ratios: 60%CO2+40%N2 (I group and 40%CO2+60%N2 (II group, whereas the samples from third, control group, (III group were vacuum packaged. During trials samples were stored in refrigerator at +3°C. Determination of TVB-N and pH was performed on 1st, 7th and 14th day of storage. The obtained results indicate that the investigated mixtures of gases and vacuum as well had a significant influence on the values of TVB-N in trout and carp cuts samples. The lowest increase in TVB-N was established in trout and carp cuts samples from the group I, whereas the highest increase was established in samples from group III. Statistical significant difference (p < 0,001 between the average values of TVB-N for trout (I group: 18,17 ± 0,93; II group: 20,90 ± 0,81 and III group: 36,18 ± 2,65 mg N/100 g and carp cuts (I group: 26,74 ± 1,48; II group: 30,02 ± 0,31 and III group: 35,10 ± 1,75 mg N/100 g was established on 14th day. The lowest pH value was established in samples packaged in modified atmosphere with 60% CO2 +40% N2 (I group. On 14th day of testing the obtained value was 6,15 ± 0,09 for trout and 5,94 ± 1,11 for carp samples. Increase in pH value in trout samples packed in

  12. Challenges in Optimizing a Prostate Carcinoma Binding Peptide, Identified through the Phage Display Technology

    Directory of Open Access Journals (Sweden)

    Jürgen Debus

    2011-02-01

    Full Text Available The transfer of peptides identified through the phage display technology to clinical applications is difficult. Major drawbacks are the metabolic degradation and label instability. The aim of our work is the optimization of DUP-1, a peptide which was identified by phage display to specifically target human prostate carcinoma. To investigate the influence of chelate conjugation, DOTA was coupled to DUP-1 and labeling was performed with 111In. To improve serum stability cyclization of DUP-1 and targeted D-amino acid substitution were carried out. Alanine scanning was performed for identification of the binding site and based on the results peptide fragments were chemically synthesized. The properties of modified ligands were investigated in in vitro binding and competition assays. In vivo biodistribution studies were carried out in mice, carrying human prostate tumors subcutaneously. DOTA conjugation resulted in different cellular binding kinetics, rapid in vivo renal clearance and increased tumor-to-organ ratios. Cyclization and D-amino acid substitution increased the metabolic stability but led to binding affinity decrease. Fragment investigation indicated that the sequence NRAQDY might be significant for target-binding. Our results demonstrate challenges in optimizing peptides, identified through phage display libraries, and show that careful investigation of modified derivatives is necessary in order to improve their characteristics.

  13. A Novel Chemically Modified Curcumin “Normalizes” Wound-Healing in Rats with Experimentally Induced Type I Diabetes: Initial Studies

    Science.gov (United States)

    Zhang, Yazhou; McClain, Steve A.; Lee, Hsi-Ming; Elburki, Muna S.; Yu, Huiwen; Gu, Ying; Zhang, Yu; Wolff, Mark; Johnson, Francis; Golub, Lorne M.

    2016-01-01

    Introduction. Impaired wound-healing in diabetics can lead to life-threatening complications, such as limb amputation, associated in part with excessive matrix metalloproteinase- (MMP-) mediated degradation of collagen and other matrix constituents. In the current study, a novel triketonic chemically modified curcumin, CMC2.24, was tested for efficacy in healing of standardized skin wounds in streptozotocin-induced diabetic rats. Initially, CMC2.24 was daily applied topically at 1% or 3% concentrations or administered systemically (oral intubation; 30 mg/kg); controls received vehicle treatment only. Over 7 days, the diabetics exhibited impaired wound closure, assessed by gross and histologic measurements, compared to the nondiabetic controls. All drug treatments significantly improved wound closure with efficacy ratings as follows: 1% 2.24 > systemic 2.24 > 3% 2.24 with no effect on the severe hyperglycemia. In subsequent experiments, 1% CMC2.24 “normalized” wound-healing in the diabetics, whereas 1% curcumin was no more effective than 0.25% CMC2.24, and the latter remained 34% worse than normal. MMP-8 was increased 10-fold in the diabetic wounds and topically applied 1% (but not 0.25%) CMC2.24 significantly reduced this excessive collagenase-2; MMP-13/collagenase-3 did not show significant changes. Additional studies indicated efficacy of 1% CMC2.24 over more prolonged periods of time up to 30 days.

  14. Modified DLC coatings prepared in a large-scale reactor by dual microwave/pulsed-DC plasma-activated chemical vapour deposition

    International Nuclear Information System (INIS)

    Diamond-Like Carbon (DLC) films find abundant applications as hard and protective coatings due to their excellent mechanical and tribological performances. The addition of new elements to the amorphous DLC matrix tunes the properties of this material, leading to an extension of its scope of applications. In order to scale up their production to a large plasma reactor, DLC films modified by silicon and oxygen additions have been grown in an industrial plant of 1m3 by means of pulsed-DC plasma-activated chemical vapour deposition (PACVD). The use of an additional microwave (MW) source has intensified the glow discharge, partly by electron cyclotron resonance (ECR), accelerating therefore the deposition process. Hence, acetylene, tetramethylsilane (TMS) and hexamethyldisiloxane (HMDSO) constituted the respective gas precursors for the deposition of a-C:H (DLC), a-C:H:Si and a-C:H:Si:O films by dual MW/pulsed-DC PACVD. This work presents systematic studies of the deposition rate, hardness, adhesion, abrasive wear and water contact angle aimed to optimize the technological parameters of deposition: gas pressure, relative gas flow of the monomers and input power. This study has been completed with measures of the atomic composition of the samples. Deposition rates around 1 μm/h, typical for standard processes held in the large reactor, were increased about by a factor 10 when the ionization source has been operated in ECR mode

  15. Soft chemical synthesis of carbon-modified Ti3+ self-doped hierarchical porous TiO2 with enhanced photocatalysis

    Science.gov (United States)

    Zhao, Chunxia; Wang, Zongsheng; Chen, Wen; Song, Yanbao; Chen, Xuehua; Xie, Tao

    2016-03-01

    Carbon-modified Ti3+ self-doped hierarchical porous titanium dioxides were synthesized by one-step soft chemical method. The contents of carbon and Ti3+ of the catalysts were tuned through a facile heat treatment. The prepared photocatalysts possess well-packed uniform macropores with the size of ˜200nm, mesoporous structure with the pore size of 5.9-6.8nm, and the specific surface area of 50-200m2/g. The results illustrate the carbon combined with TiO2 via the interfacial C‑O‑Ti bonds and the rich existence of Ti3+. The catalyst with 18wt.% carbon content exhibits a degradation ratio of crystal violet up to 97.5%. The enhanced photocatalysis is ascribed to the synergistic effect of carbon and Ti3+. The interfacial C‑O‑Ti bonds act as the pathway to transfer excited electrons and the Ti3+ can trap the electrons to hinder the recombination of electrons and holes.

  16. Photoluminescence and chemical properties of ZnS:Mn2+ nanocrystal powder synthesized in the AOT reverse micelles modified with lauryl phosphate

    International Nuclear Information System (INIS)

    A transparent colloidal solution of the ZnS:Mn2+ nanocrystal was prepared in hybrid reverse micelles comprising two kinds of surfactants: sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and lauryl phosphate (HLP). Then, the powdered sample was obtained from the colloidal solution by coagulation of these micelles. Modification of HLP surfactant increases the photoluminescence (PL) intensity due to the d-d transition of Mn2+ ions for both of the colloidal solution and the powder. FT-IR spectra and energy dispersive X-ray analysis (EDX) data reveal that HLP modifies ZnS:Mn2+ nanocrystals more preferentially than AOT. The detailed investigation on chemical interaction between HLP molecules and ZnS nanocrystals with and without Mn2+ is performed by solid-state nuclear magnetic resonance (NMR) techniques of 31P inversion recovery and 1H →31P cross-polarization (CP) in a magnetic field of 11.7 T using magic angle spinning (MAS) at a high spinning rate of 19 and 28 kHz, respectively. These NMR results suggest that most of HLP molecules strongly interact with nanocrystals through coordination bonds and/or hydrogen bonds

  17. Biofouling-resistant ceragenin-modified materials and structures for water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Michael; Altman, Susan J.; Jones, Howland D. T.; Savage, Paul B.

    2013-09-10

    This invention relates to methods for chemically grafting and attaching ceragenin molecules to polymer substrates; methods for synthesizing ceragenin-containing copolymers; methods for making ceragenin-modified water treatment membranes and spacers; and methods of treating contaminated water using ceragenin-modified treatment membranes and spacers. Ceragenins are synthetically produced antimicrobial peptide mimics that display broad-spectrum bactericidal activity. Alkene-functionalized ceragenins (e.g., acrylamide-functionalized ceragenins) can be attached to polyamide reverse osmosis membranes using amine-linking, amide-linking, UV-grafting, or silane-coating methods. In addition, silane-functionalized ceragenins can be directly attached to polymer surfaces that have free hydroxyls.

  18. Dietary fiber, gut peptides, and adipocytokines

    OpenAIRE

    Sánchez, David; Miguel, Marta; Aleixandre, Amaya

    2012-01-01

    The consumption of dietary fiber (DF) has increased since it was related to the prevention of a range of illnesses and pathological conditions. DF can modify some gut hormones that regulate satiety and energy intake, thus also affecting lipid metabolism and energy expenditure. Among these gut hormones are ghrelin, glucagon-like peptide 1, peptide YY, and cholecystokinin. Adipose tissue is known to express and secrete a variety of products known as >adipocytokines,> which are also affected by ...

  19. Diagnostic and immunoprophylactic applications of synthetic peptides in veterinary microbiology

    Directory of Open Access Journals (Sweden)

    Saravanan Paramasivam

    2009-10-01

    Full Text Available Chemically synthesized peptides are considered as potential reagents for various applications in biological sciences. They mimic naturally occurring peptides or segments of proteins and have emerged as diagnostic reagents and safe immunogens in animal science. Carefully selected peptides resembling authentic epitopes serve as synthetic antigens in diagnostic tests. Synthetic peptide-based vaccines can elicit antibodies against animal pathogens. The early use of synthetic peptides as a vaccine for foot-and-mouth disease stimulated interest in the development of peptide-based diagnostics and immunoprophylactics. The development of a peptide vaccine for canine parvovirus confirmed the usefulness of peptides as immunoprophylactics. Recently, the advent of the technology for the development of multiple antigenic peptides (MAPs has provided a well-defined method for the production of highly immunogenic peptides and anti-peptide antibodies. Antibodies raised against major epitopes can be used in the detection of the native antigen (virus in the enzyme-linked immunosorbent assay (ELISA and other tests, vindicating the usefulness of peptides for safe, chemically defined, non-infectious diagnostics and immunoprophylactics. This article focuses on the methods for selecting and preparing peptides for the predicted epitopes, their characterization and use, and the application of MAPs.

  20. Synthesis and In Vitro Testing of New Potent Polyacridine-Melittin Gene Delivery Peptides

    OpenAIRE

    Baumhover, Nicholas J.; Anderson, Kevin; Fernandez, Christian A.; Rice, Kevin G.

    2010-01-01

    The combination of a polyacridine peptide modified with a melittin fusogenic peptide results in a potent gene transfer agent. Polyacridine peptides of the general formula (Acr-X)n-Cys were prepared by solid phase peptide synthesis, where Acr is Lys modified on its ε-amine with acridine, X is Arg, Leu or Lys and n is 2, 3 or 4 repeats. The Cys residue was modified by either a maleimide-melittin or a thiolpyridine-Cys-melittin fusogenic peptide resulting in reducible or non-reducible polyacridi...

  1. An Interplay between Electrostatic and Polar Interactions in Peptide Hydrogels

    OpenAIRE

    Joyner, Katherine; Taraban, Marc B; Feng, Yue; Yu, Y. Bruce

    2013-01-01

    Inherent chemical programmability available in peptide-based hydrogels has allowed diversity in the development of these materials for use in biomedical applications. Within the 20 natural amino acids, a range of chemical moieties are present. Here we used a mixing-induced self-assembly of two oppositely charged peptide modules to form a peptide-based hydrogel. To investigate electrostatic and polar interactions on the hydrogel, we replace amino acids from the negatively charged acidic glutam...

  2. Chemo-enzymatic peptide synthesis : bioprocess engineering aspects

    NARCIS (Netherlands)

    Vossenberg, P.

    2012-01-01

      Peptides, in particular oligopeptides, play an important role in the fields of health care, nutrition and cosmetics. Chemical synthesis is currently the most mature technique for the synthesis of peptides that range in length from 5 to 80 amino acids. Chemical synthesis is, however, expected

  3. Orientation Preferences of Backbone Secondary Amide Functional Groups in Peptide Nucleic Acid Complexes: Quantum Chemical Calculations Reveal an Intrinsic Preference of Cationic D-Amino Acid-Based Chiral PNA Analogues for the P-form

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jeremy C [ORNL; Topham, Christopher [University of Heidelberg

    2007-01-01

    Geometric descriptions of nonideal interresidue hydrogen bonding and backbone-base water bridging in the minor groove are established in terms of polyamide backbone carbonyl group orientation from analyses of residue junction conformers in experimentally determined peptide nucleic acid (PNA) complexes. Two types of interresidue hydrogen bonding are identified in PNA conformers in heteroduplexes with nucleic acids that adopt A-like base pair stacking. Quantum chemical calculations on the binding of a water molecule to an O2 base atom in glycine-based PNA thymine dimers indicate that junctions modeled with P-form backbone conformations are lower in energy than a dimer comprising the predominant conformation observed in A-like helices. It is further shown in model systems that PNA analogs based on D-lysine are better able to preorganize in a conformation exclusive to P-form helices than is glycine-based PNA. An intrinsic preference for this conformation is also exhibited by positively charged chiral PNA dimers carrying 3-amino-D-alanine or 4-aza-D-leucine residue units that provide for additional rigidity by side-chain hydrogen bonding to the backbone carbonyl oxygen. Structural modifications stabilizing P-form helices may obviate the need for large heterocycles to target DNA pyrimidine bases via PNADNA-PNA triplex formation. Quantum chemical modeling methods are used to propose candidate PNA Hoogsteen strand designs.

  4. Orientation preferences of backbone secondary amide functional groups in peptide nucleic acid complexes: quantum chemical calculations reveal an intrinsic preference of cationic D-amino acid-based chiral PNA analogues for the P-form.

    Science.gov (United States)

    Topham, Christopher M; Smith, Jeremy C

    2007-02-01

    Geometric descriptions of nonideal interresidue hydrogen bonding and backbone-base water bridging in the minor groove are established in terms of polyamide backbone carbonyl group orientation from analyses of residue junction conformers in experimentally determined peptide nucleic acid (PNA) complexes. Two types of interresidue hydrogen bonding are identified in PNA conformers in heteroduplexes with nucleic acids that adopt A-like basepair stacking. Quantum chemical calculations on the binding of a water molecule to an O2 base atom in glycine-based PNA thymine dimers indicate that junctions modeled with P-form backbone conformations are lower in energy than a dimer comprising the predominant conformation observed in A-like helices. It is further shown in model systems that PNA analogs based on D-lysine are better able to preorganize in a conformation exclusive to P-form helices than is glycine-based PNA. An intrinsic preference for this conformation is also exhibited by positively charged chiral PNA dimers carrying 3-amino-D-alanine or 4-aza-D-leucine residue units that provide for additional rigidity by side-chain hydrogen bonding to the backbone carbonyl oxygen. Structural modifications stabilizing P-form helices may obviate the need for large heterocycles to target DNA pyrimidine bases via PNA.DNA-PNA triplex formation. Quantum chemical modeling methods are used to propose candidate PNA Hoogsteen strand designs. PMID:17071666

  5. Selective extraction of U(VI), Th(IV), and La(III) from acidic matrix solutions and environmental samples using chemically modified Amberlite XAD-16 resin

    International Nuclear Information System (INIS)

    A new grafted polymer has been developed by the chemical modification of Amberlite XAD-16 (AXAD-16) polymeric matrix with [(2-dihydroxyarsinoylphenylamino)methyl]phosphonic acid (AXAD-16-AsP). The modified polymer was characterized by a combination of 13C CPMAS and 31P solid-state NMR, Fourier transform-NIR-FIR-Raman spectroscopy, CHNPS elemental analysis, and thermogravimetric analysis (TGA). The distribution studies for the extraction of U(VI), Th(IV), and La(III) from acidic solutions were performed using an AXAD-16-AsP-packed chromatographic column. The influences of various physiochemical parameters on analyte recovery were optimized by both static and dynamic methods. Accordingly, even under high acidities (>4 M), good distribution ratio (D) values (102-104) were achieved for all the analytes. Metal ion desorption was effective using 1 mol L-1 (NH4)2CO3. From kinetic studies, a time duration of -1 for U(VI); 0.47, 0.39, and 1.40 mmol g-1 for Th(IV); and 1.44, 1.48, and 1.12 mmol g-1 for La(III), in the presence of 2 mol L-1 HNO3, 2 mol L-1 HCl, and under pH conditions, respectively. The analyte selectivity of the grafted polymer was tested in terms of interfering species tolerance studies. The system showed an enrichment factor of 365, 300, and 270 for U(VI), Th(IV), and La(III), and the limit of analyte detection was in the range of 18-23 ng mL-1. The practical applicability of the polymer was tested with synthetic nuclear spent fuel and seawater mixtures, natural water, and geological samples. The RSD of the total analytical procedure was within 4.9%, thus confirming the reliability of the developed method. (orig.)

  6. Hybrid molecularly imprinted poly(methacrylic acid-TRIM)-silica chemically modified with (3-glycidyloxypropyl)trimethoxysilane for the extraction of folic acid in aqueous medium.

    Science.gov (United States)

    de Oliveira, Fernanda Midori; Segatelli, Mariana Gava; Tarley, César Ricardo Teixeira

    2016-02-01

    In the present study a hybrid molecularly imprinted poly(methacrylic acid-trimethylolpropane trimethacrylate)-silica (MIP) was synthesized and modified with (3-glycidyloxypropyl)trimethoxysilane (GPTMS) with posterior opening of epoxy ring to provide hydrophilic properties of material in the extraction of folic acid from aqueous medium. The chemical and structural aggregates of hybrid material were characterized by means of Fourier Transform Infrared (FT-IR), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Thermogravimetric analysis (TGA) and textural data. Selectivity data of MIP were compared to non-imprinted polymer (NIP) through competitive sorption studies in the presence of caffeine, paracetamol or 4-aminobenzamide yielding relative selectivity coefficients (k′) higher than one unit, thus confirming the selective character of MIP even in the presence of structurally smaller compounds than the folic acid. The lower hydrophobic sorption by bovine serum albumin (BSA) in the MIP as compared to unmodified MIP proves the hydrophilicity of polymer surface by using GPTMS with opening ring. Under acid medium(pH 1.5) the sorption of folic acid onto MIP from batch experiments was higher than the one achieved for NIP. Equilibrium sorption of folic acid was reached at 120 min for MIP, NIP and MIP without GPTMS and kinetic sorption data were well described by pseudo-second-order, Elovich and intraparticle diffusion models. Thus, these results indicate the existence of different binding energy sites in the polymers and a complex mechanism consisting of both surface sorption and intraparticle transport of folic acid within the pores of polymers. PMID:26652418

  7. Salt-resistant short antimicrobial peptides.

    Science.gov (United States)

    Mohanram, Harini; Bhattacharjya, Surajit

    2016-05-01

    Antimicrobial peptides (AMPs) are promising leads for the development of antibiotics against drug resistant bacterial pathogens. However, in vivo applications of AMPs remain obscure due to salt and serum mediated inactivation. The high cost of chemical synthesis of AMPs also impedes potential clinical application. Consequently, short AMPs resistant toward salt and serum inactivation are desirable for the development of peptide antibiotics. In this work, we designed a 12-residue amphipathic helical peptide RR12 (R-R-L-I-R-L-I-L-R-L-L-R-amide) and two Trp containing analogs of RR12 namely RR12Wpolar (R-R-L-I-W-L-I-L-R-L-L-R-amide), and RR12Whydro (R-R-L-I-R-L-W-L-R-L-L-R-amide). Designed peptides demonstrated potent antibacterial activity; MIC ranging from 2 to 8 μM, in the presence of sodium chloride (150 mM and 300 mM). Antibacterial activity of these peptides was also detected in the presence of human serum. Designed peptides, in particular RR12 and RR12Whydro, were only poorly hemolytic. As a mode of action; these peptides demonstrated efficient permeabilization of bacterial cell membrane and lysis of cell structure. We further investigated interactions of the designed peptides with lipopolysaccharide (LPS), the major component of the outer membrane permeability barrier of Gram-negative bacteria. Designed peptides adopted helical conformations in complex with LPS. Binding of peptides with LPS has yielded dissociation the aggregated structures of LPS. Collectively, these designed peptides hold ability to be developed for salt-resistant antimicrobial compounds. Most importantly, current work provides insights for designing salt-resistant antimicrobial peptides. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 345-356, 2016. PMID:26849911

  8. Human peptide transporters

    DEFF Research Database (Denmark)

    Nielsen, Carsten Uhd; Brodin, Birger; Jørgensen, Flemming Steen;

    2002-01-01

    Peptide transporters are epithelial solute carriers. Their functional role has been characterised in the small intestine and proximal tubules, where they are involved in absorption of dietary peptides and peptide reabsorption, respectively. Currently, two peptide transporters, PepT1 and PepT2, wh...

  9. Comparison of palladium chemical modifiers for the determination of selenium in plasma by Zeeman-effect background corrected electrothermal atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Jons, O.

    1997-01-01

    former species, It was not possible to stabilize trimethylselenonium to the same extent with this modifier, Peak shapes and appearance times of the atomization signals were equal for the four selenium species with this modifier, The addition of 20 mu g of palladium was used for the analysis of the serum...

  10. Lasso peptides: an intriguing class of bacterial natural products.

    Science.gov (United States)

    Hegemann, Julian D; Zimmermann, Marcel; Xie, Xiulan; Marahiel, Mohamed A

    2015-07-21

    Natural products of peptidic origin often represent a rich source of medically relevant compounds. The synthesis of such polypeptides in nature is either initiated by deciphering the genetic code on the ribosome during the translation process or driven by ribosome-independent processes. In the latter case, highly modified bioactive peptides are assembled by multimodular enzymes designated as nonribosomal peptide synthetases (NRPS) that act as a protein-template to generate chemically diverse peptides. On the other hand, the ribosome-dependent strategy, although relying strictly on the 20-22 proteinogenic amino acids, generates structural diversity by extensive post-translational-modification. This strategy seems to be highly distributed in all kingdoms of life. One example for this is the lasso peptides, which are an emerging class of ribosomally assembled and post-translationally modified peptides (RiPPs) from bacteria that were first described in 1991. A wide range of interesting biological activities are known for these compounds, including antimicrobial, enzyme inhibitory, and receptor antagonistic activities. Since 2008, genome mining approaches allowed the targeted isolation and characterization of such molecules and helped to better understand this compound class and their biosynthesis. Their defining structural feature is a macrolactam ring that is threaded by the C-terminal tail and held in position by sterically demanding residues above and below the ring, resulting in a unique topology that is reminiscent of a lariat knot. The ring closure is achieved by an isopeptide bond formed between the N-terminal α-amino group of a glycine, alanine, serine, or cysteine and the carboxylic acid side chain of an aspartate or glutamate, which can be located at positions 7, 8, or 9 of the amino acid sequence. In this Account, we discuss the newest findings about these compounds, their biosynthesis, and their physicochemical properties. This includes the suggested

  11. Evolution of antimicrobial peptides to self-assembled peptides for biomaterial applications.

    Science.gov (United States)

    McCloskey, Alice P; Gilmore, Brendan F; Laverty, Garry

    2014-01-01

    Biomaterial-related infections are a persistent burden on patient health, recovery, mortality and healthcare budgets. Self-assembled antimicrobial peptides have evolved from the area of antimicrobial peptides. Peptides serve as important weapons in nature, and increasingly medicine, for combating microbial infection and biofilms. Self-assembled peptides harness a "bottom-up" approach, whereby the primary peptide sequence may be modified with natural and unnatural amino acids to produce an inherently antimicrobial hydrogel. Gelation may be tailored to occur in the presence of physiological and infective indicators (e.g. pH, enzymes) and therefore allow local, targeted antimicrobial therapy at the site of infection. Peptides demonstrate inherent biocompatibility, antimicrobial activity, biodegradability and numerous functional groups. They are therefore prime candidates for the production of polymeric molecules that have the potential to be conjugated to biomaterials with precision. Non-native chemistries and functional groups are easily incorporated into the peptide backbone allowing peptide hydrogels to be tailored to specific functional requirements. This article reviews an area of increasing interest, namely self-assembled peptides and their potential therapeutic applications as innovative hydrogels and biomaterials in the prevention of biofilm-related infection. PMID:25436505

  12. Peptide-Loaded Solid Lipid Nanoparticles Prepared through Coacervation Technique

    Directory of Open Access Journals (Sweden)

    Marina Gallarate

    2011-01-01

    Full Text Available Stearic acid solid lipid nanoparticles were prepared according to a new technique, called coacervation. The main goal of this experimental work was the entrapment of peptide drugs into SLN, which is a difficult task, since their chemical characteristics (molecular weight, hydrophilicity, and stability hamper peptide-containing formulations. Insulin and leuprolide, chosen as model peptide drugs, were encapsulated within nanoparticles after hydrophobic ion pairing with anionic surfactants. Peptide integrity was maintained after encapsulation, and nanoparticles can act in vitro as a sustained release system for peptide.

  13. The influence of surface microstructure and chemical composition on corrosion behaviour in fuel-grade bio-ethanol of low-alloy steel modified by plasma nitro-carburizing and post-oxidizing

    International Nuclear Information System (INIS)

    The interaction of bio-ethanol on steel surfaces modified by plasma-assisted diffusion technologies is studied for the first time. The influence of surface microstructure and chemical composition on corrosion behaviour of AISI 4140 low-alloy steel in fuel-grade bio-ethanol was investigated. The steel surfaces were modified by plasma nitro-carburizing followed plasma oxidizing. X-ray diffraction, scanning electron microscopy, optical microscopy, X-ray dispersive spectroscopy, and glow-discharge optical emission spectroscopy were used to characterize the modified surface before and after immersion tests in bio-ethanol up to 77 days. The main corrosion mechanism is pit formation. The pit density and pit size were measured in order to quantify the corrosion resistance which was found to depend more strongly on microstructure and morphology of the oxide layer than on its thickness. The best corrosion protection was observed for samples post-oxidized at 480 °C and 90 min.

  14. Effect of modified atmosphere packaging on the course of physical and chemical changes in chilled muscle tissue of silver carp (Hypophthalmichthys molitrix, V.).

    Science.gov (United States)

    Jezek, F; Buchtová, H

    2012-01-01

    The effect of two types of modified atmosphere (MA1: 69% N2, 25% CO2, 5% O2, 1% CO; MA2: 70% N2, 30% CO2) on changes in physical and chemical parameters (pH, a(w)--water activity, TVBN - total volatile basic nitrogen, TMA - trimethylamine, FFA - free fatty acids, PV - peroxide value, TBA--thiobarbituric acid) in muscle tissues of the silver carp was monitored in the study. The samples were stored at temperatures +2 +/- 2 degrees C for 18 days. Changes in gas volumes (CO2 and O2) in MAs were also monitored. CO2 levels increased in MA1 but decreased in MA2. At the end of 18 days of storage, a significantly (P MA1, in contrast to samples packaged under MA2 where water activity values showed considerable fluctuation. Variations in pH values in the two types of MA showed similar trends. Sample pH gradually decreased until day 9 of storage. On day 11, muscle tissue pH increased markedly and then began to decrease again. The overall decrease in pH values was more profound in samples packaged under MA1. TVBN and TMA levels in samples packaged under the two types of MAs remained almost identical until day 9 of the experiment. Later, however, significantly (P MA1. FFA concentrations in silver carp samples in MA1 were significantly lower (P MA1 starting on day 9. Maximum TBA values in MA1 and MA2 were observed on days 14 and 18 of the experiment, respectively. From the course of proteolytic and oxidative changes point of view, the more appropriate combination of gases for silver carp storage seems to be the mixture of 70% N2 and 30% CO2 (MA2), which allows for muscle storage of up to 9 days. We recommend TVBN as a suitable indicator of freshness, and TBA assay as a suitable indicator of the extent of oxidative processes. PMID:23214362

  15. Efficient generation of volatile species for cadmium analysis in seafood and rice samples by a modified chemical vapor generation system coupled with atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xin-an, E-mail: 13087641@qq.com; Chi, Miao-bin, E-mail: 1161306667@qq.com; Wang, Qing-qing, E-mail: wangqq8812@163.com; Zhang, Wang-bing, E-mail: ahutwbzh@163.com

    2015-04-15

    Highlights: • We develop a modified chemical vapor generation method coupled with AFS for the determination of cadmium. • The response of Cd could be increased at least four-fold compared to conventional thiourea and Co(II) system. • A simple mixing sequences experiment is designed to study the reaction mechanism. • The interference of transition metal ions can be easily eliminated by adding DDTC. • The method is successfully applied in seafood samples and rice samples. - Abstract: A vapor generation procedure to determine Cd by atomic fluorescence spectrometry (AFS) has been established. Volatile species of Cd are generated by following reaction of acidified sample containing Fe(II) and L-cysteine (Cys) with sodium tetrahydroborate (NaBH{sub 4}). The presence of 5 mg L{sup −1} Fe(II) and 0.05% m/v Cys improves the efficiency of Cd vapor generation substantially about four-fold compared with conventional thiourea and Co(II) system. Three experiments with different mixing sequences and reaction times are designed to study the reaction mechanism. The results document that the stability of Cd(II)–Cys complexes is better than Cys–THB complexes (THB means NaBH{sub 4}) while the Cys–THB complexes have more contribution to improve the Cd vapor generation efficiency than Cd(II)–Cys complexes. Meanwhile, the adding of Fe(II) can catalyze the Cd vapor generation. Under the optimized conditions, the detection limit of Cd is 0.012 μg L{sup −1}; relative standard deviations vary between 0.8% and 5.5% for replicate measurements of the standard solution. In the presence of 0.01% DDTC, Cu(II), Pb(II) and Zn(II) have no significant influence up to 5 mg L{sup −1}, 10 mg L{sup −1}and 10 mg L{sup −1}, respectively. The accuracy of the method is verified through analysis of the certificated reference materials and the proposed method has been applied in the determination of Cd in seafood and rice samples.

  16. Efficient generation of volatile species for cadmium analysis in seafood and rice samples by a modified chemical vapor generation system coupled with atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    Highlights: • We develop a modified chemical vapor generation method coupled with AFS for the determination of cadmium. • The response of Cd could be increased at least four-fold compared to conventional thiourea and Co(II) system. • A simple mixing sequences experiment is designed to study the reaction mechanism. • The interference of transition metal ions can be easily eliminated by adding DDTC. • The method is successfully applied in seafood samples and rice samples. - Abstract: A vapor generation procedure to determine Cd by atomic fluorescence spectrometry (AFS) has been established. Volatile species of Cd are generated by following reaction of acidified sample containing Fe(II) and L-cysteine (Cys) with sodium tetrahydroborate (NaBH4). The presence of 5 mg L−1 Fe(II) and 0.05% m/v Cys improves the efficiency of Cd vapor generation substantially about four-fold compared with conventional thiourea and Co(II) system. Three experiments with different mixing sequences and reaction times are designed to study the reaction mechanism. The results document that the stability of Cd(II)–Cys complexes is better than Cys–THB complexes (THB means NaBH4) while the Cys–THB complexes have more contribution to improve the Cd vapor generation efficiency than Cd(II)–Cys complexes. Meanwhile, the adding of Fe(II) can catalyze the Cd vapor generation. Under the optimized conditions, the detection limit of Cd is 0.012 μg L−1; relative standard deviations vary between 0.8% and 5.5% for replicate measurements of the standard solution. In the presence of 0.01% DDTC, Cu(II), Pb(II) and Zn(II) have no significant influence up to 5 mg L−1, 10 mg L−1and 10 mg L−1, respectively. The accuracy of the method is verified through analysis of the certificated reference materials and the proposed method has been applied in the determination of Cd in seafood and rice samples

  17. Novel Method for Radiolabeling and Dimerizing Thiolated Peptides Using (18)F-Hexafluorobenzene.

    Science.gov (United States)

    Jacobson, Orit; Yan, Xuefeng; Ma, Ying; Niu, Gang; Kiesewetter, Dale O; Chen, Xiaoyuan

    2015-10-21

    Hexafluorobenzene (HFB) reacts with free thiols to produce a unique and selective perfluoroaromatic linkage between two sulfurs. We modified this chemical reaction to produce dimeric (18)F-RGD-tetrafluorobenzene (TFB)-RGD, an integrin αvβ3 receptor ligand. (18)F-HFB was prepared by a fluorine exchange reaction using K(18)F/K2.2.2 at room temperature. The automated radiofluorination was optimized to minimize the amount of HFB precursor and, thus, maximize the specific activity. (18)F-HFB was isolated by distillation and subsequently reacted with thiolated c(RGDfk) peptide under basic and reducing conditions. The resulting (18)F-RGD-TFB-RGD demonstrated integrin receptor specific binding, cellular uptake, and in vivo tumor accumulation.(18)F-HFB can be efficiently incorporated into thiol-containing peptides at room temperature to provide novel imaging agents. PMID:26086295

  18. Engineering Biosynthesis of Non-ribosomal Peptides and Polyketides by Directed Evolution.

    Science.gov (United States)

    Rui, Zhe; Zhang, Wenjun

    2016-01-01

    Non-ribosomal peptides (NRPs) and polyketides (PKs) play key roles in pharmaceutical industry due to their promising biological activities. The structural complexity of NRPs and PKs, however, creates significant synthetic challenges for producing these natural products and their analogues by purely chemical means. Alternatively, difficult syntheses can be achieved by using biosynthetic enzymes with improved efficiency and altered selectivity that are acquired from directed evolution. Key to the successful directed evolution is the methodology of screening/selection. This review summarizes the screening/selection strategies that have been employed to improve or modify the functions of non-ribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs), in the hope of triggering the wide adoption of the directed evolution approaches in the engineered biosynthesis of NRPs and PKs for drug discovery. PMID:26456467

  19. Solid-phase peptide quantitation assay using labeled monoclonal antibody and glutaraldehyde fixation

    International Nuclear Information System (INIS)

    A solid-phase radioimmunoassay utilizing iodinated peptide-specific monoclonal antibody as a detection system instead of labeled peptide has been developed. Regional specific monoclonal antibodies to either gastrin-releasing peptide or gastrin were used as models to validate the general application of our modified assay. Conditions for radioactive labeling of the monoclonal antibody were determined to minimize oxidant damage, which compromises the sensitivity of other reported peptide quantitation assays. Pretreatment of 96-well polyvinyl chloride test plates with a 5% glutaraldehyde solution resulted in consistent retention of sufficient target peptide on the solid-phase matrix to allow precise quantitation. This quantitative method is completed within 1 h of peptide solid phasing. Pretreatment of assay plates with glutaraldehyde increased binding of target peptide and maximized antibody binding by optimizing antigen presentation. The hypothesis that glutaraldehyde affects both peptide binding to the plate and orientation of the peptide was confirmed by analysis of several peptide analogs. These studies indicate that peptide binding was mediated through a free amino group leaving the carboxy-terminal portion of the target peptide accessible for antibody binding. It was observed that the length of the peptide also affects the amount of monoclonal antibody that will bind. Under the optimal conditions, results from quantitation of gastrin-releasing peptide in relevant samples agree well with those from previously reported techniques. Thus, we report here a modified microplate assay which may be generally applied for the rapid and sensitive quantitation of peptide hormones

  20. Peptide-Carrier Conjugation

    DEFF Research Database (Denmark)

    Hansen, Paul Robert

    To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined.......To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined....