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Sample records for amphiphilic octenyl succinic

  1. Preparation and structural characterisation of novel and versatile amphiphilic octenyl succinic anhydride-modified hyaluronic acid derivatives

    DEFF Research Database (Denmark)

    Eenschooten, Corinne Diane; Guillaumie, Fanny; Kontogeorgis, Georgios;

    2010-01-01

    The purpose of the present study was to prepare amphiphilic hyaluronic acid (HA) derivatives and to study the influence of a selection of reaction parameters on the degree of substitution (DS) of the derivatives. Octenyl succinic anhydride (OSA)–modified HA (OSA–HA) derivatives were prepared and...

  2. Phytoglycogen octenyl succinate, an amphiphilic carbohydrate nanoparticle, and epsilon-polylysine to improve lipid oxidative stability of emulsions.

    Science.gov (United States)

    Scheffler, Siqi L; Wang, Xue; Huang, Lei; San-Martin Gonzalez, Fernanda; Yao, Yuan

    2010-01-13

    Phytoglycogen octenyl succinate (PG-OS) and epsilon-polylysine (EPL) were used to form oil-in-water emulsions with enhanced lipid oxidative stability. PG-OS is an amphiphilic carbohydrate nanoparticle prepared using octenyl succinate (OS) substitution of phytoglycogen (PG). PG-OS had a dispersed molecular density nearly 20 times that of waxy corn starch octenyl succinate (WCS-OS). Fish oil-in-water emulsions were prepared using PG-OS, WCS-OS, and Tween 20, stored at 55 degrees C for 6 days, and monitored for the accumulation of hydroperoxide and thiobarbituric acid reactive substances (TBARS). The result indicated that PG-OS may lead to high lipid oxidative stability, and that the addition of EPL may further improve the oxidative stability of emulsions. To address the interaction between PG-OS and EPL, zeta-potential was determined for various systems. The results indicated a possible formation of an interfacial complex layer comprising both PG-OS and EPL. This complex layer may provide both physical and electrostatic barriers against pro-oxidative compounds. PMID:19928899

  3. Nano-encapsulation of coenzyme Q10 using octenyl succinic anhydride modified starch

    Science.gov (United States)

    Octenyl succinic anhydride modified starch (OSA-ST) was used to encapsulate Coenzyme Q10 (CoQ10). CoQ10 was dissolved in rice bran oil (RBO), and incorporated into an aqueous OSA-ST solution. High pressure homogenization (HPH) of the mixture was conducted at 170 MPa for 5-6 cycles. The resulting ...

  4. Preparation and Characterization of Octenyl Succinic Anhydride Modified Taro Starch Nanoparticles

    OpenAIRE

    Jiang, Suisui; Dai, Lei; Qin, Yang; Xiong, Liu; Sun, Qingjie

    2016-01-01

    The polar surface and hydrophilicity of starch nanoparticles (SNPs) result in their poor dispersibility in nonpolar solvent and poor compatibility with hydrophobic polymers, which limited the application in hydrophobic system. To improve their hydrophobicity, SNPs prepared through self-assembly of short chain amylose debranched from cooked taro starch, were modified by octenyl succinic anhydride (OSA). Size via dynamic light scattering of OSA-SNPs increased compared with SNPs. Fourier transfo...

  5. Synthesis and paste properties of octenyl succinic anhydride modified early Indica rice starch*

    OpenAIRE

    Song, Xiao-Yan; Chen, Qi-he; Ruan, Hui; He, Guo-qing; Xu, Qiong

    2006-01-01

    Octenyl succinic anhydride (OSA) modified early Indica rice starch was prepared in aqueous slurry systems using response surface methodology. The paste properties of the OSA starch were also investigated. Results indicated that the suitable parameters for the preparation of OSA starch from early Indica rice starch were as follows: reaction period 4 h, reaction temperature 33.4 °C, pH of reaction system 8.4, concentration of starch slurry 36.8% (in proportion to water, w/w), amount of OSA 3% (...

  6. Preparation and Characterization of Octenyl Succinic Anhydride Modified Taro Starch Nanoparticles.

    Science.gov (United States)

    Jiang, Suisui; Dai, Lei; Qin, Yang; Xiong, Liu; Sun, Qingjie

    2016-01-01

    The polar surface and hydrophilicity of starch nanoparticles (SNPs) result in their poor dispersibility in nonpolar solvent and poor compatibility with hydrophobic polymers, which limited the application in hydrophobic system. To improve their hydrophobicity, SNPs prepared through self-assembly of short chain amylose debranched from cooked taro starch, were modified by octenyl succinic anhydride (OSA). Size via dynamic light scattering of OSA-SNPs increased compared with SNPs. Fourier transform infrared spectroscopy data indicated the OSA-SNPs had a new absorption peak at 1727 cm-1, which was the characteristic peak of carbonyl, indicating the formation of the ester bond. The dispersibility of the modified SNPs in the mixture of water with nonpolar solvent increased with increasing of degree of substitution (DS). OSA-SNPs appear to be a potential agent to stabilize the oil-water systems. PMID:26918568

  7. Preparation and Characterization of Octenyl Succinic Anhydride Modified Taro Starch Nanoparticles.

    Directory of Open Access Journals (Sweden)

    Suisui Jiang

    Full Text Available The polar surface and hydrophilicity of starch nanoparticles (SNPs result in their poor dispersibility in nonpolar solvent and poor compatibility with hydrophobic polymers, which limited the application in hydrophobic system. To improve their hydrophobicity, SNPs prepared through self-assembly of short chain amylose debranched from cooked taro starch, were modified by octenyl succinic anhydride (OSA. Size via dynamic light scattering of OSA-SNPs increased compared with SNPs. Fourier transform infrared spectroscopy data indicated the OSA-SNPs had a new absorption peak at 1727 cm-1, which was the characteristic peak of carbonyl, indicating the formation of the ester bond. The dispersibility of the modified SNPs in the mixture of water with nonpolar solvent increased with increasing of degree of substitution (DS. OSA-SNPs appear to be a potential agent to stabilize the oil-water systems.

  8. Ionic liquids as novel solvents for biosynthesis of octenyl succinic anhydride-modified waxy maize starch.

    Science.gov (United States)

    Li, Dandan; Zhang, Xiwen; Tian, Yaoqi

    2016-05-01

    Biosynthesis of octenyl succinic anhydride (OSA) starch was investigated using ionic liquids (ILs) as reaction media. Waxy maize starch was pretreated in 1-butyl-3-methylimidazolium chlorine and then esterified with OSA in 1-octyl-3-methylimidazolium nitrate by using Novozyme 435 as catalyst. The degree of substitution of OSA starch reached 0.0130 with 5 wt% starch concentration and 1 wt% lipase dosage based on ILs weight at 50 °C for 3h. The formation of OSA starch was confirmed by fourier transform infrared spectroscopy. Scanning electron microscopy and X-ray diffraction revealed that the morphology and crystal structure of starch were significantly destroyed. Thermogravimetric analysis showed that esterification decreased the thermal stability of starch. The successful lipase-catalyzed synthesis of OSA starch in ILs suggests that ILs are potential replacement of traditional organic solvents for starch ester biosynthesis. PMID:26797225

  9. Synthesis and paste properties of octenyl succinic anhydride modified early Indica rice starch

    Institute of Scientific and Technical Information of China (English)

    SONG Xiao-yan; CHEN Qi-he; RUAN Hui; HE Guo-qing; XU Qiong

    2006-01-01

    Octenyl succinic anhydride (OSA) modified early Indica rice starch was prepared in aqueous slurry systems using response surface methodology. The paste properties of the OSA starch were also investigated. Results indicated that the suitable parameters for the preparation of OSA starch from early Indica rice starch were as follows: reaction period 4 h, reaction temperature 33.4 ℃, pH of reaction system 8.4, concentration of starch slurry 36.8% (in proportion to water, w/w), amount of OSA 3% (in proportion to starch, w/w). The degree of substitution was 0.0188 and the reaction efficiency was 81.0%. The results of paste properties showed that with increased OSA modification, the starch derivatives had higher paste clarity, decreased retrogradation and better freeze-thaw stability.

  10. Slowly digestible waxy maize starch prepared by octenyl succinic anhydride esterification and heat-moisture treatment: glycemic response and mechanism.

    Science.gov (United States)

    He, Jinhua; Liu, Jie; Zhang, Genyi

    2008-01-01

    The mechanism and molecular structure of the slowly digestible waxy maize starch prepared by octenyl succinic anhydride (OSA) esterification and heat-moisture treatment were investigated. The in vitro Englyst test showed a proportion of 28.3% slowly digestible starch (SDS) when waxy maize starch was esterified with 3% OSA (starch weight based, and it is named OSA-starch), and a highest SDS content of 42.8% was obtained after OSA-starch (10% moisture) was further heated at 120 degrees C for 4 h (named HOSA-starch). The in vivo glycemic response of HOSA-starch, which showed a delayed appearance of blood glucose peak and a significant reduction (32.2%) of the peak glucose concentration, further confirmed its slow digestion property. Amylopectin debranching analysis revealed HOSA-starch had the highest resistance to debranching enzymes of isoamylase and pullulanase, and a simultaneous decrease of K m and V m (enzyme kinetics) was also shown when HOSA-starch was digested by either alpha-amylase or amyloglucosidase, indicating that the slow digestion of HOSA-starch resulted from an uncompetitive inhibition of enzyme activity during digestion. Size exclusion chromatography analysis of HOSA-starch showed fragmented amylopectin molecules with more nonreducing ends that are favorable for RS conversion to SDS by the action of amyloglucosidase in the Englyst test. Further solubility analysis indicates that the water-insolubility of HOSA-starch is caused by OSA-mediated cross-linking of amylopectin and the hydrophobic interaction between OSA-modified starch molecules. The water-insolubility of HOSA-starch would decrease its enzyme accessibility, and the digestion products with attached OSA molecules might also directly act as the uncompetitive inhibitor to reduce the enzyme activity leading to a slow digestion of HOSA-starch. PMID:18067261

  11. Preparation and characterization of single and dual propylene oxide and octenyl succinic anhydride modified starch carriers for the microencapsulation of essential oils.

    Science.gov (United States)

    Baranauskienė, Renata; Rutkaitė, Ramunė; Pečiulytė, Laura; Kazernavičiūtė, Rita; Venskutonis, Petras Rimantas

    2016-08-10

    Hydroxypropylation with propylene oxide followed by esterification with octenyl succinic anhydride (OSA) was used to produce modified potato starch derivatives suitable for the encapsulation of essential oils. Caraway essential oil (EO) was encapsulated by spray-drying into enzymatically hydrolyzed dual/single modified and native starches. The EO microencapsulation efficiency in different modified starches, the retention of volatile aroma compounds, the emulsion particle size and the microstructure of the spray-dried encapsulated powdered products, as well as the compositional aroma changes taking place during the processing and storage for up to 8 months have been estimated. The increase of OSA content from 0.97 to 2.52% in the P-native structure and from 0.91% to 2.66% in P-HP resulted in the significant increase in the encapsulating capacity, evaluated as a percentage of the total EO retained, from 61.6 to 88.0% and 73.8% to 84.0%, respectively. However, the compositional changes of the microencapsulated caraway EO constituents were not remarkable. Additionally, the effect of pure and encapsulated caraway EO products on the oxidative stability of commercial rapeseed oil and mayonnaise was evaluated using the instrumental Oxipres method and it was shown that they were more effective in emulsion type products by the up to 1.8-fold increase in the oxidative stability of mayonnaise. PMID:27465989

  12. Novel self-associative and multiphase nanostructured soft carriers based on amphiphilic hyaluronic acid derivatives

    DEFF Research Database (Denmark)

    Eenschooten, Corinne; Vaccaro, Andrea; Delie, Florence;

    2012-01-01

    The purpose of the present study was to investigate the physicochemical properties in aqueous media of amphiphilic hyaluronic acid (HA) derivatives obtained by reaction of HA’s hydroxyl groups with octenyl succinic anhydride (OSA). The self-associative properties of the resulting octenyl succinic...... anhydridemodified hyaluronic acid (OSA-HA) derivatives were studied by fluorescence spectroscopy using Nile Red as fluorophore. The morphology, size and surface charge of the OSA-HA assemblies were determined by transmission electron microscopy, dynamic light scattering and by measuring their electrophoretic...

  13. Study on the properties of cassava hydroxypropyl and octenyl succinic anhydride compound modified starch%木薯羟丙基化辛烯基琥珀酸酯化复合改性淀粉的性质研究

    Institute of Scientific and Technical Information of China (English)

    雷欣欣; 张本山; 周雪

    2012-01-01

    以木薯淀粉为原料制备木薯羟丙基化辛烯基琥珀酸酯化复合改性淀粉,采用傅里叶变换红外谱仪、扫描电镜、X射线衍射仪和Brabender黏度仪等对木薯羟丙基化辛烯基琥珀酸酯化复合改性淀粉的物化性质进行了测定和分析.并与木薯原淀粉和木薯辛烯基琥珀酸淀粉酯进行对比。结果表明,木薯淀粉经复合改性后,在1550-1610cm-1出现新的吸收峰.与原木薯淀粉和木薯SSOS相比,在940、880、730、570cm-1处呈现较弱的吸收峰;复合改性后颗粒表面受损严重.颗粒的形状也发生明显改变,但晶体类型没有发生改变;乳化性能和透明度得到提高;起糊温度、峰值温度降低.糊粘度增大;与单一的辛烯基琥珀酸酯化改性淀粉相比,热糊稳定性升高,凝沉性增强。%The cassava starch was used to prepare cassava hydroxypropyl and octenyl succinic anhydride compound modified starch. The physical properties of cassava hydroxypropyl and octenyl succinic anhydride compound modified starch were investigated by Fourier transform infrared spectrometer(FT-IR),Scanning electron microscop,X-ray diffraction(XRD),Brabender viscometer and so on with the comparison of the native cassava starch and octenyl succinic anhydride(OSA)-modified cassava starch. The results indicated that the FT-IR spectrum of compound modified cassava starch showed new absorption peaks at 1550-1610cm-1. and weaken absorption peak at the 940,880,730 and 570cm-1,compared with the native cassava starch and OSA- modified cassava starch. The starch granule exhibited rougher surface,more irregular shape significantly but the crystalline was not changed. The product showed good emulsifiability and transparency. That gelatinization temperature and the peak temperature all decreased,and paste viscosity was higher as well.The setback capacity was weaker,and hot paste stability increased,compared with single octenyl succinic anhydride

  14. Polymeric micelles of amphiphilic graft copolymer of α-tocopherol succinate-g-carboxymethyl chitosan for tamoxifen delivery: Synthesis, characterization and in vivo pharmacokinetic study.

    Science.gov (United States)

    Jena, Sunil K; Sangamwar, Abhay T

    2016-10-20

    Novel amphiphilic graft copolymers were prepared from low molecular weight carboxymethyl chitosan (LMW Cmc) and α-tocopherol succinate (TS) via an amidation reaction and confirmed by (1)H NMR and IR spectroscopy. These graft copolymers are self-assembled to nanosized core-shell-structural micelles in an aqueous milieu. The critical micelle concentration (CMC) decreased with an increasing substitution of TS on LMW Cmc, which ranged from 7.94×10(-8) to 1.58×10(-6)g/mL. Cmc-TS4.5 (Cmc-TS with a charged molar ratio of TS to glucosamine units of Cmc∼4.5) was shown maximum TMX loading up to 8.08±0.98%. Both blank and TMX-loaded PM's of Cmc-TS4.5 exhibit spherical shape with particle size below 200nm. An in vitro release study in simulated gastric and intestinal fluid demonstrated that TMX release from TMX-PM4.5 (TMX-PMs prepared with amphiphilic polymer Cmc-TS4.5, and the weight ratio of Cmc-TS4.5 to TMX was 8:1) was slow and pH dependent. In vivo oral absorption study revealed Cmc-TS4.5 based PM's permeated the epithelial barrier via the paracellular route without causing any intestinal damage. In vivo toxicity study demonstrated the safety of PM's after oral administration. Compared to tamoxifen control, TMX-PM4.5 dosed to fasted female Sprague Dawley rats showed a 1.9 fold increase in AUC0-72h. Thus, the results suggested that Cmc-TS micelles are a promising carrier for TMX delivery. PMID:27474667

  15. The Succinated Proteome

    Energy Technology Data Exchange (ETDEWEB)

    Merkley, Eric D.; Metz, Thomas O.; Smith, Richard D.; Baynes, John; Frizell, Norma

    2014-03-30

    Succination is a chemical modification of cysteine in protein by the Krebs cycle intermediate, fumarate, yielding S-(2-succino)cysteine (2SC). Intracellular fumarate concentration and succination of proteins are increased by hyperpolarization of the inner mitochondrial membrane, in concert with mitochondrial, endoplasmic reticulum (ER) and oxidative stress in adipocytes grown in high glucose medium and in adipose tissue in obesity and diabetes. Increased succination of proteins is also detected in the kidney of a fumarase conditional knock-out mouse which develops renal tumors. Keap1, the gatekeeper of the antioxidant response, was identified as a major succinated protein in renal cancer cells, suggesting that succination may play a role in activation of the antioxidant response. A wide range of proteins is subject to succination, including enzymes, adipokines, cytoskeletal proteins and ER chaperones with functional cysteine residues. There is also significant overlap between succinated and glutathionylated proteins, and with proteins containing cysteine residues that are readily oxidized to the sulfenic (cysteic) acid. Succination of adipocyte proteins is inhibited by uncouplers, which discharge the mitochondrial membrane potential (Δψm) and by ER stress inhibitors. 2SC serves as a biomarker of mitochondrial stress or dysfunction in chronic diseases, such as obesity, diabetes and cancer, and recent studies suggest that succination is a mechanistic link between mitochondrial dysfunction, oxidative and ER stress, and cellular progression toward apoptosis. In this article, we review the history of the succinated proteome and the challenges associated with measuring this non-enzymatic post-translational modification of proteins by proteomics approaches.

  16. Succinic anhydrides from epoxides

    Energy Technology Data Exchange (ETDEWEB)

    Coates, Geoffrey W.; Rowley, John M.

    2013-07-09

    Catalysts and methods for the double carbonylation of epoxides are disclosed. Each epoxide molecule reacts with two molecules of carbon monoxide to produce a succinic anhydride. The reaction is facilitated by catalysts combining a Lewis acidic species with a transition metal carbonyl complex. The double carbonylation is achieved in single process by using reaction conditions under which both carbonylation reactions occur without the necessity of isolating or purifying the product of the first carbonylation.

  17. Succinic anhydrides from epoxides

    Energy Technology Data Exchange (ETDEWEB)

    Coates, Geoffrey W; Rowley, John M

    2014-12-30

    Catalysts and methods for the double carbonylation of epoxides are disclosed. Each epoxide molecule reacts with two molecules of carbon monoxide to produce a succinic anhydride. The reaction is facilitated by catalysts combining a Lewis acidic species with a transition metal carbonyl complex. The double carbonylation is achieved in single process by using reaction conditions under which both carbonylation reactions occur without the necessity of isolating or purifying the product of the first carbonylation.

  18. Synthesis of carbon-14 labeled doxylamine succinate

    International Nuclear Information System (INIS)

    Doxylamine succinate, N,N-dimethyl-2-[1-phenyl-1-(2-pyridinyl)-ethoxy]ethanamine succinate is an antihistamine used primarily as a sedative. Carbon-14 labeled doxylamine succinate, required for toxicological studies, was synthesized in two steps starting from 2-benzoyl pyridine. (author)

  19. Amphiphilic hyaluronic acid derivatives toward the design of micelles for the sustained delivery of hydrophobic drugs.

    Science.gov (United States)

    Mayol, Laura; Biondi, Marco; Russo, Luisa; Malle, Birgitte M; Schwach-Abdellaoui, Khadija; Borzacchiello, Assunta

    2014-02-15

    The idea of this study was to combine hyaluronic acid (HA) viscosupplementation and a local/controlled delivery of a hydrophobic anti-inflammatory drug. To this aim, we investigated the ability of an octenyl succinic anhydride (OSA) modified HA (OSA-HA), to act as a solubility enhancer and as a platform for slow release of hydrophobic drug(s). This novel HA derivative could act as a viscosupplementation agent and, for this reason, a rheological study was conducted along with calorimetric analysis. Differential scanning calorimetry (DSC) results revealed that the ability of HA to sequester water is enhanced by the introduction of lipophilic functions within HA molecules, resulting in a decrease of the fraction of free water able to freeze compared to the unmodified HA. Moreover, OSA-HA solutions appear to be an appropriate tool to be used in viscosupplementation therapy owing to their suitable viscoelastic features. Our results indicate that OSA-HA is able to self-assemble into micelles, load a hydrophobic drug and release the active molecule with controlled kinetics. In particular, the analysis of release profiles showed that, in all cases, drug diffusion into the gel is faster compared to gel/drug dissolution, being the dissolution contribution more relevant as the OSA-HA concentration increases. PMID:24507262

  20. Production of Succinic Acid for Lignocellulosic Hydrolysates

    Energy Technology Data Exchange (ETDEWEB)

    Davison, B.H.; Nghiem, J.

    2002-06-01

    The purpose of this Cooperative Research and Development Agreement (CRADA) is to add and test new metabolic activities to existing microbial catalysts for the production of succinic acid from renewables. In particular, they seek to add to the existing organism the ability to utilize xylose efficiently and simultaneously with glucose in mixtures of sugars or to add succinic acid production to another strain and to test the value of this new capability for production of succinic acid from industrial lignocellulosic hydrolyasates. The Contractors and Participant are hereinafter jointly referred to as the 'Parties'. Research to date in succinic acid fermentation, separation and genetic engineering has resulted in a potentially economical process based on the use of an Escherichia coli strain AFP111 with suitable characteristics for the production of succinic acid from glucose. Economic analysis has shown that higher value commodity chemicals can be economically produced from succinic acid based on repliminary laboratory findings and predicted catalytic parameters. The initial target markets include succinic acid itself, succinate salts, esters and other derivatives for use as deicers, solvents and acidulants. The other commodity products from the succinic acid platform include 1,4-butanediol, {gamma}-butyrolactone, 2-pyrrolidinone and N-methyl pyrrolidinone. Current economic analyses indicate that this platform is competitive with existing petrochemical routes, especially for the succinic acid and derivatives. The report presents the planned CRADA objectives followed by the results. The results section has a combined biocatalysis and fermentation section and a commercialization section. This is a nonproprietary report; additional proprietary information may be made available subject to acceptance of the appropriate proprietary information agreements.

  1. Amphiphiles for protein solubilization and stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Gellman, Samuel Helmer; Chae, Pil Seok; Laible, Phillip D; Wander, Marc J

    2014-11-04

    The invention provides amphiphiles for manipulating membrane proteins. The amphiphiles can feature carbohydrate-derived hydrophilic groups and branchpoints in the hydrophilic moiety and/or in a lipophilic moiety. Such amphiphiles are useful as detergents for solubilization and stabilization of membrane proteins, including photosynthetic protein superassemblies obtained from bacterial membranes.

  2. Amphiphiles for protein solubilization and stabilization

    Science.gov (United States)

    Gellman, Samuel Helmer; Chae, Pil Seok; Laible, Philip D.; Wander, Marc J.

    2012-09-11

    The invention provides amphiphiles for manipulating membrane proteins. The amphiphiles can feature carbohydrate-derived hydrophilic groups and branchpoints in the hydrophilic moiety and/or in a lipophilic moiety. Such amphiphiles are useful as detergents for solubilization and stabilization of membrane proteins, including photosynthetic protein superassemblies obtained from bacterial membranes.

  3. Role of succinic acid in chemical evolution

    Science.gov (United States)

    Negron-Mendoza, A.; Ponnamperuma, C.

    1982-01-01

    Succinic acid is converted into other carboxylic acids by ionizing radiation. The results obtained have been correlated with the ready formation of this compound in prebiotic experiments. Its role in biological systems may be related to its prebiotic occurrence.

  4. Crystal structure of the bis(cyclohexylammonium succinate succinic acid salt adduct

    Directory of Open Access Journals (Sweden)

    Modou Sarr

    2015-08-01

    Full Text Available The crystal structure of the title salt adduct, 2C6H14N+·C4H4O42−·C4H6O4, consists of two cyclohexylammonium cations, one succcinate dianion and one neutral succinic acid molecule. Succinate dianions and succinic acid molecules are self-assembled head-to-tail through O—H...O hydrogen bonds and adopt a syn–syn configuration, leading to a strand-like arrangement along [101]. The cyclohexylammonium cations have a chair conformation and act as multidentate hydrogen-bond donors linking adjacent strands through intermolecular N—H...O interactions to both the succinate and the succinic acid components. This results in two-dimensional supramolecular layered structures lying parallel to (010.

  5. Microbiota-Produced Succinate Improves Glucose Homeostasis via Intestinal Gluconeogenesis.

    Science.gov (United States)

    De Vadder, Filipe; Kovatcheva-Datchary, Petia; Zitoun, Carine; Duchampt, Adeline; Bäckhed, Fredrik; Mithieux, Gilles

    2016-07-12

    Beneficial effects of dietary fiber on glucose and energy homeostasis have long been described, focusing mostly on the production of short-chain fatty acids by the gut commensal bacteria. However, bacterial fermentation of dietary fiber also produces large amounts of succinate and, to date, no study has focused on the role of succinate on host metabolism. Here, we fed mice a fiber-rich diet and found that succinate was the most abundant carboxylic acid in the cecum. Dietary succinate was identified as a substrate for intestinal gluconeogenesis (IGN), a process that improves glucose homeostasis. Accordingly, dietary succinate improved glucose and insulin tolerance in wild-type mice, but those effects were absent in mice deficient in IGN. Conventional mice colonized with the succinate producer Prevotella copri exhibited metabolic benefits, which could be related to succinate-activated IGN. Thus, microbiota-produced succinate is a previously unsuspected bacterial metabolite improving glycemic control through activation of IGN. PMID:27411015

  6. 2-Amino-5-bromopyridinium hydrogen succinate

    Directory of Open Access Journals (Sweden)

    Hoong-Kun Fun

    2010-03-01

    Full Text Available In the title compound, C5H6BrN2+·C4H5O4−, the pyridine N atom of the 2-amino-5-bromopyridine molecule is protonated. The protonated N atom and the amino group are linked via N—H...O hydrogen bonds to the carboxylate O atoms of the singly deprotonated succinate anion. The hydrogen succinate anions are linked via O—H...O hydrogen bonds. A weak intermolecular C—H...O hydrogen bond is also observed.

  7. Tandem Facial Amphiphiles for Membrane Protein Stabilization

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Gotfryd, Kamil; Pacyna, Jennifer; Miercke, Larry J W; Rasmussen, Søren G F; Robbins, Rebecca A; Rana, Rohini R; Løland, Claus Juul; Kobilka, Brian; Stroud, Robert; Byrne, Bernadette; Gether, Ulrik; Gellman, Samuel H

    2010-01-01

    We describe a new type of synthetic amphiphile that is intended to support biochemical characterization of intrinsic membrane proteins. Members of this new family displayed favorable behavior with four of five membrane proteins tested, and these amphiphiles formed relatively small micelles....

  8. 21 CFR 520.784 - Doxylamine succinate tablets.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Doxylamine succinate tablets. 520.784 Section 520.784 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... succinate tablets. (a) Specifications. The drug is in tablet form and contains doxylamine succinate as...

  9. The effect of alpha-tocopheryl succinate on succinate respiration in rat liver mitochondria

    Czech Academy of Sciences Publication Activity Database

    Sobotka, O.; Drahota, Zdeněk; Kučera, O.; Endlicher, R.; Rauchová, Hana; Červinková, Z.

    2015-01-01

    Roč. 64, Suppl.5 (2015), S609-S615. ISSN 0862-8408 Institutional support: RVO:67985823 Keywords : tocopheryl succinate * Complex II * liver * mitochondria * homogenate * hepatocytes Subject RIV: ED - Physiology Impact factor: 1.293, year: 2014

  10. Amphiphilic Soft Janus Particles as Interfacial Stabilizers

    Science.gov (United States)

    Wang, Wenda; Niu, Sunny; Sosa, Chris; Prud'Homme, Robert; Priestley, Rodney; Priestley Polymer group Team; Prud'homme Research Group Team

    Janus particles, which incorporate two or more ``faces'' with different chemical functionality, have attracted great attention in scientific research. Amphiphilic Janus particles have two faces with distinctly different hydrophobicity. This can be thought of as colloidal surfactants. Theoretical studies on the stabilization of emulsions using Janus particles have confirmed higher efficiency. Herein we synthesize the narrow distributed amphiphilic polymeric Janus particles via Precipitation-Induced Self-Assembly (PISA). The efficiency of the amphiphilic Janus particles are tested on different oil/water systems. Biocompatible polymers can also be used on this strategy and may potentially have wide application for food emulsion, cosmetics and personal products.

  11. Effect of starch sodium octenyl succinate on the stability of peanut butter%辛烯基琥珀酸淀粉钠对花生酱稳定性的影响

    Institute of Scientific and Technical Information of China (English)

    安昕; 李凌峰; 郇延军

    2014-01-01

    采用正交实验分析法对花生酱的稳定性工艺进行优化,研究了辛烯基琥珀酸淀粉钠用量、原浆与水比例、匀浆速度及时间对花生酱离心乳析率、离心沉淀率的影响,并进行了花生酱储存稳定性和感官特性的比较.实验结果表明:原浆与水比例为1∶1、辛烯基琥珀酸淀粉钠用量为8%、匀浆速度为900r/min、匀浆时间为3min时,制得的花生酱的离心乳析率和离心沉淀率最低,分别为0.92%和1.60%.相较原浆具有更好的稳定性与更高的感官评价得分,且粘度也最接近花生原浆.

  12. TREATMENT OF CHRONIC HEART FAILURE: FOCUS ON METOPROLOL SUCCINATE

    OpenAIRE

    2015-01-01

    Advantages of metoprolol succinate in patients with chronic heart failure (CHF) are covered. Results of MERIT-HF study are taken as the main evidences. Patterns of the metoprolol succinate use in the treatment of different categories of patients with CHF (women, the elderly , severe CHF forms, CHF with concomitant hypertension or diabetes) are considered.

  13. TREATMENT OF CHRONIC HEART FAILURE: FOCUS ON METOPROLOL SUCCINATE

    Directory of Open Access Journals (Sweden)

    O. D. Ostroumova

    2015-12-01

    Full Text Available Advantages of metoprolol succinate in patients with chronic heart failure (CHF are covered. Results of MERIT-HF study are taken as the main evidences. Patterns of the metoprolol succinate use in the treatment of different categories of patients with CHF (women, the elderly , severe CHF forms, CHF with concomitant hypertension or diabetes are considered.

  14. Materials and methods for efficient succinate and malate production

    Science.gov (United States)

    Jantama, Kaemwich; Haupt, Mark John; Zhang, Xueli; Moore, Jonathan C; Shanmugam, Keelnatham T; Ingram, Lonnie O'Neal

    2014-04-08

    Genetically engineered microorganisms have been constructed to produce succinate and malate in mineral salt media in pH-controlled batch fermentations without the addition of plasmids or foreign genes. The subject invention also provides methods of producing succinate and malate comprising the culture of genetically modified microorganisms.

  15. Nanostructured assemblies from amphiphilic ABC multiblock polymers

    Science.gov (United States)

    Hillmyer, Marc A.

    2012-02-01

    Amphiphilic AB diblock copolymers containing a water compatible segment can self-assemble in aqueous media to give supramolecular structures that include simple spherical micelles and macromolecular vesicles termed polymersomes. Amphiphilic ABA triblocks with hydrophobic end blocks can adopt analogous structures but can also form gels at high polymer concentrations. The structural and chemical diversity demonstrated in block copolymer micelles and gels makes them attractive for applications ranging from drug delivery to personal care products to nanoreactors. The inclusion of a third block in amphiphilic ABC triblock systems can lead to a much wider array of self-assembled structures that depend not only on composition but also on block sequence, architecture and incompatibility considerations. I will present our recent efforts on tuning micelle and gel structure and behavior using controlled architecture ABC triblocks. The combination of diverse polymer segments into a single macromolecule is a powerful method for development of self-assembled structures with both new form and new function.

  16. Prediction on amphiphilicity of hypocrellin derivatives

    Institute of Scientific and Technical Information of China (English)

    谢杰; 马江华; 赵井泉

    2002-01-01

    Hypocrellins are most suitable for photodynamic therapy (PDT) of the diseases occurring in the superficial layer, such as microvascular diseases, because of their special absorption spectral properties. However, hypocrellins and most of their derivatives are basically lipophilic, while the hydrophilic derivatives lose the PDT activity in vivo. Therefore, the key problem for practical application of PDT of microvascular diseases focuses on finding the derivatives which possess optimized amphiphilicity. Herein, we developed a theoretical method to estimate the amphi-philicity of a molecule by the calculated average polarity. Compared with the experimentally measured results, the method is proved to be applicable. Based on the computation and available experimental results, it can be concluded that the derivative must have the polarities around C.22 for optimized amphiphilicity.

  17. Prediction on amphiphilicity of hypocrellin derivatives

    Institute of Scientific and Technical Information of China (English)

    谢杰; 马江华; 赵井泉

    2002-01-01

    Hypocrellins are most suitable for photodynamic therapy (PDT) of the diseases occurring in the superficial layer, such as microvascular diseases, because of their special absorption spectral properties. However, hypocrellins and most of their derivatives are basically lipophilic, while the hydrophilic derivatives lose the PDT activity in vivo. Therefore, the key problem for practical application of PDT of microvascular diseases focuses on finding the derivatives which possess optimized amphiphilicity. Herein, we developed a theoretical method to estimate the amphiphilicity of a molecule by the calculated average polarity. Compared with the experimentally measured results, the method is proved to be applicable. Based on the computation and available experimental results, it can be concluded that the derivative must have the polarities around 0.22 for optimized amphiphilicity.

  18. Novel Tripod Amphiphiles for Membrane Protein Analysis

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Kruse, Andrew C; Gotfryd, Kamil; Rana, Rohini R; Cho, Kyung Ho; Rasmussen, Søren G F; Bae, Hyoung Eun; Chandra, Richa; Gether, Ulrik; Guan, Lan; Kobilka, Brian K; Loland, Claus J; Byrne, Bernadette; Gellman, Samuel H

    2013-01-01

    Integral membrane proteins play central roles in controlling the flow of information and molecules across membranes. Our understanding of membrane protein structures and functions, however, is seriously limited, mainly due to difficulties in handling and analysing these proteins in aqueous solution....... The use of a detergent or other amphipathic agents is required to overcome the intrinsic incompatibility between the large lipophilic surfaces displayed by the membrane proteins in their native forms and the polar solvent molecules. Here, we introduce new tripod amphiphiles displaying favourable...... behaviours toward several membrane protein systems, leading to an enhanced protein solubilisation and stabilisation compared to both conventional detergents and previously described tripod amphiphiles....

  19. Rheological properties of dough and quality of bread supplemented with emulsifying polysaccharides

    OpenAIRE

    Dapčević-Hadnađev Tamara; Dokić Ljubica; Pojić Milica; Hadnađev Miroslav; Torbica Aleksandra; Rakita Slađana

    2014-01-01

    The aim of present study was to evaluate the effects of emulsifying starches used as additives in breadmaking. In order to achieve this, the partial replacement (5-10%) of wheat flour with starch sodium octenyl succinate (OSA starch), pregelatinized starch sodium octenyl succinate (Pregel OSA starch) and hydrolyzed spray-dried starch sodium octenyl succinate (Hydrol OSA starch) was performed. The quality characteristics of obtained bread were compared to co...

  20. Peptide Amphiphiles in Corneal Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Martina Miotto

    2015-08-01

    Full Text Available The increasing interest in effort towards creating alternative therapies have led to exciting breakthroughs in the attempt to bio-fabricate and engineer live tissues. This has been particularly evident in the development of new approaches applied to reconstruct corneal tissue. The need for tissue-engineered corneas is largely a response to the shortage of donor tissue and the lack of suitable alternative biological scaffolds preventing the treatment of millions of blind people worldwide. This review is focused on recent developments in corneal tissue engineering, specifically on the use of self-assembling peptide amphiphiles for this purpose. Recently, peptide amphiphiles have generated great interest as therapeutic molecules, both in vitro and in vivo. Here we introduce this rapidly developing field, and examine innovative applications of peptide amphiphiles to create natural bio-prosthetic corneal tissue in vitro. The advantages of peptide amphiphiles over other biomaterials, namely their wide range of functions and applications, versatility, and transferability are also discussed to better understand how these fascinating molecules can help solve current challenges in corneal regeneration.

  1. Designing new symmetrical facial oligothiophene amphiphiles

    NARCIS (Netherlands)

    Janeliunas, Dainius; Eelkema, Rienk; Nieto-Ortega, Belén; Ramírez Aguilar, Francisco J; López Navarrete, Juan T; van der Mee, Lars; Stuart, Marc C A; Casado, Juan; van Esch, Jan H

    2013-01-01

    In this study we designed a new class of symmetrical facial oligothiophene amphiphiles, which could be obtained in fewer steps than for previously reported analogues, but still possess the specific substituent sequence to control their backbone curvature. This novel design allows the late-stage intr

  2. Bola-amphiphile self-assembly

    DEFF Research Database (Denmark)

    Svaneborg, Carsten

    2012-01-01

    Bola-amphiphiles are rod-like molecules where both ends of the molecule likes contact with water, while the central part of the molecule dislikes contact with water. What do such molecules do when they are dissolved in water? They self-assemble into micelles. This is a Dissipartive particle dynam...

  3. Fluctuations and structure of amphiphilic films

    International Nuclear Information System (INIS)

    This thesis is divided in three parts.The first part exposes in a theoretical point of view, how the fluctuations spectrum of an amphiphilic film is governed by its properties and its bidimensional characteristics.The measurements of fluctuations spectra of an interface are accessible with the measurement of intensity that interface diffuses out of the specular angle, we present in the second chapter the principles of the X rays diffusion by a real interface and see how the diffuse diffusion experiments allow to determine the fluctuations spectrum of an amphiphilic film. The second part is devoted to the different experimental techniques that have allowed to realize the study of fluctuation as well as the structural study.The third part is devoted to experimental results concerning the measurements of fluctuations spectra and to the study of the structure of amphiphilic films. We show that it is possible by using an intense source of X rays (ESRF: European Synchrotron Radiation Facility) to measure the water and amphiphilic films fluctuations spectra until molecular scales. The last chapter is devoted to the structural study and film fluctuations made of di-acetylenic molecules. (N.C.)

  4. Biodegradable polyesters based on succinic acid

    Directory of Open Access Journals (Sweden)

    Nikolić Marija S.

    2003-01-01

    Full Text Available Two series of aliphatic polyesters based on succinic acid were synthesized by copolymerization with adipic acid for the first series of saturated polyesters, and with fumaric acid for the second series. Polyesters were prepared starting from the corresponding dimethyl esters and 1,4-butanediol by melt transesterification in the presence of a highly effective catalyst tetra-n-butyl-titanate, Ti(0Bu4. The molecular structure and composition of the copolyesters was determined by 1H NMR spectroscopy. The effect of copolymer composition on the physical and thermal properties of these random polyesters were investigated using differential scanning calorimetry. The degree of crystallinity was determined by DSC and wide angle X-ray. The degrees of crystallinity of the saturated and unsaturated copolyesters were generally reduced with respect to poly(butylene succinate, PBS. The melting temperatures of the saturated polyesters were lower, while the melting temperatures of the unsaturated copolyesters were higher than the melting temperature of PBS. The biodegradability of the polyesters was investigated by enzymatic degradation tests. The enzymatic degradation tests were performed in a buffer solution with Candida cylindracea lipase and for the unsaturated polyesters with Rhizopus arrhizus lipase. The extent of biodegradation was quantified as the weight loss of polyester films. Also the surface of the polyester films after degradation was observed using optical microscopy. It could be concluded that the biodegradability depended strongly on the degree of crystallinity, but also on the flexibility of the chain backbone. The highest biodegradation was observed for copolyesters containing 50 mol.% of adipic acid units, and in the series of unsaturated polyesters for copolyesters containing 5 and 10 mol.% of fumarate units. Although the degree of crystallinity of the unsaturated polyesters decreased slightly with increasing unsaturation, the biodegradation

  5. FORMULATION AND EVALUATION OF METAPROLOL SUCCINATE EXTENDED RELEASE PELLETS

    OpenAIRE

    Ahishek Perumalla; Manivannan, R.; Nelluri Rama Rao; M. Radhakrishna; Devareddy Sandeep

    2012-01-01

    The aim and of the present study is to develop a pharmaceutically stable and quality improved formulation of Metoprolol succinate extended release pellets. To achieve this goal various prototype formulation trials were formulated and the evaluated with respect to the various quality controls such as dissolution, assay and stability studies will be under taken. Metoprolol succinate is used in the treatment of hyper tension, angina pectoris (chest pain) and myocardial infarction. The study was...

  6. Hydroxypropyl Methylcellulose Acetate Succinate: Potential Drug–Excipient Incompatibility

    OpenAIRE

    Dong, Zedong; Choi, Duk Soon

    2008-01-01

    The stability of hydroxypropyl methylcellulose acetate succinate (HPMC-AS) and its potential incompatibility with active pharmaceutical ingredients (API) carrying hydroxyl group(s) were investigated in this research. HPMC-AS may undergo hydrolysis under harsh processing conditions with the generation of succinic acid and acetic acid, which can form ester bond(s) with the hydroxyl group(s) in API. In this case, the hot-melt extrusion (HME) product prepared from HPMC-AS and our model compound (...

  7. Economical succinic acid production from cane molasses by Actinobacillus succinogenes.

    Science.gov (United States)

    Liu, Yu-Peng; Zheng, Pu; Sun, Zhi-Hao; Ni, Ye; Dong, Jin-Jun; Zhu, Lei-Lei

    2008-04-01

    In this work, production of succinic acid by Actinobacillus succinogenes CGMCC1593 using cane molasses as a low cost carbon source was developed. In anaerobic bottles fermentation, succinic acid concentration of 50.6+/-0.9 g l(-1) was attained at 60 h using an optimum medium containing molasses pretreated with sulfuric acid, resulting in a succinic acid yield of 79.5+/-1.1% and sugar utilization of 97.1+/-0.6%. When batch fermentation was carried out in a 5-l stirred bioreactor with pretreated molasses, 46.4 g l(-1) of succinic acid was attained at 48 h and faster cells growth was also observed. Fed batch fermentation was performed to minimize the substrate (sugar) inhibition effect, giving 55.2 g l(-1) of succinic acid and 1.15 g l(-1)h(-1) of productivity at 48 h. The present study suggests that the inexpensive cane molasses could be utilized for the economical and efficient production of succinic acid by A. succinogenes. PMID:17532626

  8. Foams Stabilized by Tricationic Amphiphilic Surfactants

    OpenAIRE

    Heerschap, Seth; Marafino, John N.; McKenna, Kristin; Caran, Kevin L.; Feitosa, Klebert

    2015-01-01

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. Novel surfactant architectures with multi-cephalic and multi-tailed molecules have reportedly enhanced their anti-bacterial activity in connection with tail length and the nature of the head group, but their ability to produce and stabilize foam is mostly unknown. Here we report on experiments with tris-cationic, triple-headed, double- a...

  9. Solid lipid nanoparticles from amphiphilic calixpyrroles

    OpenAIRE

    Helttunen, Kaisa; Galán, Albano; Ballester, Pablo; Bergenholtz, Johan; Nissinen, Maija

    2016-01-01

    Hypothesis Macrocyclic amphiphiles form interesting self-assembling structures, including solid lipid nanoparticles, which have potential applications in drug encapsulation. Aryl-extended calixpyrroles, which act as anion binding hosts, are expected to form solid lipid nanoparticles, even though the alkyl chains have unusual perpendicular geometry with respect to the hydrophilic head group. The preparation conditions and the alkyl chain length should affect the size and stability of the p...

  10. Amphiphilic Fullerenes for Biomedical and Optoelectronical Applications

    OpenAIRE

    Witte, Patrick

    2009-01-01

    Fullerenes have an enormous potential in applications to physics and biology. Specifically [60]fullerene with its unique electronic, optical and structural properties has attracted considerable attention for its application in biomedical materials and optoelectronic devices. In this context the selective functionalization of C60, which allows to combine the parent properties with new attributes like water-solubility or amphiphilicity is still a challenging topic for the synthetic chemist. In ...

  11. Prebiotic Lipidic Amphiphiles and Condensing Agents on the Early Earth

    OpenAIRE

    Michele Fiore; Peter Strazewski

    2016-01-01

    It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of ...

  12. Recent advances in production of succinic acid from lignocellulosic biomass.

    Science.gov (United States)

    Akhtar, Junaid; Idris, Ani; Abd Aziz, Ramlan

    2014-02-01

    Production of succinic acid via separate enzymatic hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) are alternatives and are environmentally friendly processes. These processes have attained considerable positions in the industry with their own share of challenges and problems. The high-value succinic acid is extensively used in chemical, food, pharmaceutical, leather and textile industries and can be efficiently produced via several methods. Previously, succinic acid production via chemical synthesis from petrochemical or refined sugar has been the focus of interest of most reviewers. However, these expensive substrates have been recently replaced by alternative sustainable raw materials such as lignocellulosic biomass, which is cheap and abundantly available. Thus, this review focuses on succinic acid production utilizing lignocellulosic material as a potential substrate for SSF and SHF. SSF is an economical single-step process which can be a substitute for SHF - a two-step process where biomass is hydrolyzed in the first step and fermented in the second step. SSF of lignocellulosic biomass under optimum temperature and pH conditions results in the controlled release of sugar and simultaneous conversion into succinic acid by specific microorganisms, reducing reaction time and costs and increasing productivity. In addition, main process parameters which influence SHF and SSF processes such as batch and fed-batch fermentation conditions using different microbial strains are discussed in detail. PMID:24292125

  13. Water Diffusion Dependence on Amphiphilic Block Design in (Amphiphilic-Hydrophobic) Diblock Copolymer Membranes.

    Science.gov (United States)

    Dorenbos, Gert

    2016-06-30

    Polyelectrolyte membranes (PEMs) are applied in polyelectrolyte fuel cells (PEFC). The proton conductive pathways within PEMs are provided by nanometer-sized water containing pores. Large-scale application of PEFC requires the production of low-cost membranes with high proton conductivity and therefore good connected pore networks. Pore network formation within four alternative model diblock (hydrophobic_amphiphilic) copolymers in the presence of water is studied by dissipative particle dynamics. Each hydrophobic block contains 50 consecutively connected hydrophobic (A) fragments, and amphiphilic blocks contain 40 hydrophobic A beads and 10 hydrophilic C beads. For one amphiphilic block the C beads are distributed uniformly along the backbone. For the other architectures C beads are located at the end of the side chains attached at regular intervals along the backbone. Water diffusion through the pores is modeled by Monte Carlo tracer diffusion through mapped morphologies. Diffusion is highest for the grafted architectures and increases with increase of length of the side chains. A consistent picture emerges in which diffusion strongly increases with the value of ⟨Nbond⟩ within the amphiphilic block, where ⟨Nbond⟩ is the average number of bonds between hydrophobic A beads and the nearest C bead. PMID:27266679

  14. Incorporation of Amphiphilic Cyclodextrins into Liposomes as Artificial Receptor Units

    NARCIS (Netherlands)

    Kauscher, Ulrike; Stuart, Marc C. A.; Druecker, Patrick; Galla, Hans-Joachim; Ravoo, Bart Jan

    2013-01-01

    In this article, we describe the introduction of amphiphilic beta-cyclodextrins into liposomes to act as artificial receptor units. Using dynamic light scattering, dye encapsulation, and cryogenic transmission electron microscopy, we show that amphiphilic beta-cyclodextrins can be mixed in any propo

  15. Glucose-neopentyl glycol (GNG) amphiphiles for membrane protein study

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Rana, Rohini R; Gotfryd, Kamil; Rasmussen, Søren G F; Kruse, Andrew C; Cho, Kyung Ho; Capaldi, Stefano; Carlsson, Emil; Kobilka, Brian; Loland, Claus J; Gether, Ulrik; Banerjee, Surajit; Byrne, Bernadette; Lee, John K; Gellman, Samuel H

    2013-01-01

    The development of a new class of surfactants for membrane protein manipulation, "GNG amphiphiles", is reported. These amphiphiles display promising behavior for membrane proteins, as demonstrated recently by the high resolution structure of a sodium-pumping pyrophosphatase reported by Kellosalo et...

  16. DESIGN, DEVELOPMENT AND EVALUATION OF SUMATRIPTAN SUCCINATE TRANSDERMAL PATCHES

    Directory of Open Access Journals (Sweden)

    Gururaj S. Kulkarni* and D. Narasinha Reddy

    2012-06-01

    Full Text Available Most of the therapeutic agents are recommended through an oral route, but oral route has disadvantages like first pass metabolism, liver toxicity, etc, due to gastrointestinal pH. This leads poor bioavailability of drugs, which are not stable in G.I pH. To overcome this problem, increase the bioiavailibility, reduce the dose and dose dumping Transdermal delivery system is better option as novel drug delivery system, which bypass the hepatic first pass metabolism, and avoid drug degradation due to systemic absorption of the drug. Minimize plasma level fluctuations and extend the drug activity besides improving patient compliance. Sumatriptan succinate is a selective 5-hydroxytryptamine receptor subtype agonist. Sumatriptan succinate is chemically designated as 3-[2-(dimethylaminoethyl]-N-methyl-indole-5-methanesulfonamide succinate. Sumatriptan succinate is a white to off-white powder that is readily soluble in water. Oral administration of Sumatriptan succinate suffers from poorbioavailability, partly due to presystemic metabolism- some of it gets broken down in the stomach and bloodstream before it reaches the target arteries. Sumatriptan is metabolized primarily by monoamine oxidase A into an indole acetic acid analogue, part of which is further conjugated with glucuronic acid. These metabolites excreted in the urine and bile. Only about 3% of the active drug may be recovered unchanged. Because of this the bioavailability is only 15% with half life is 2.5 hrs. In this work, the effort has done to improve bioavailability of the sumatriptan succinate by transdermal patches dosage form by using polymers HPMCK4M, carbopol934 and Dibutylpthalate as used as plasticizers.

  17. Mutant E. coli strain with increased succinic acid production

    Science.gov (United States)

    Donnelly, Mark; Millard, Cynthia S.; Stols, Lucy

    2001-09-25

    A method for isolating succinic acid producing bacteria is provided comprising increasing the biomass of an organism which lacks the ability to catabolize pyruvate, and then subjecting the biomass to glucose-rich medium in an anaerobic environment to enable pyruvate-catabolizing mutants to grow. The invention also provides for a mutant that produces high amounts of succinic acid, which has been derived from a parent which lacked the genes for pyruvate formate lyase and lactate dehydrogenase, and which belongs to the E.coli Group of Bacteria.

  18. Vitamin E succinate-conjugated F68 micelles for mitoxantrone delivery in enhancing anticancer activity

    Science.gov (United States)

    Liu, Yuling; Xu, Yingqi; Wu, Minghui; Fan, Lijiao; He, Chengwei; Wan, Jian-Bo; Li, Peng; Chen, Meiwan; Li, Hui

    2016-01-01

    Mitoxantrone (MIT) is a chemotherapeutic agent with promising anticancer efficacy. In this study, Pluronic F68-vitamine E succinate (F68-VES) amphiphilic polymer micelles were developed for delivering MIT and enhancing its anticancer activity. MIT-loaded F68–VES (F68–VES/MIT) micelles were prepared via the solvent evaporation method with self-assembly under aqueous conditions. F68–VES/MIT micelles were found to be of optimal particle size with the narrow size distribution. Transmission electron microscopy images of F68–VES/MIT micelles showed homogeneous spherical shapes and smooth surfaces. F68–VES micelles had a low critical micelle concentration value of 3.311 mg/L, as well as high encapsulation efficiency and drug loading. Moreover, F68–VES/MIT micelles were stable in the presence of fetal bovine serum for 24 hours and maintained sustained drug release in vitro. Remarkably, the half maximal inhibitory concentration (IC50) value of F68–VES/MIT micelles was lower than that of free MIT in both MDA-MB-231 and MCF-7 cells (two human breast cancer cell lines). In addition, compared with free MIT, there was an increased trend of apoptosis and cellular uptake of F68–VES/MIT micelles in MDA-MB-231 cells. Taken together, these results indicated that F68–VES polymer micelles were able to effectively deliver MIT and largely improve its potency in cancer therapy. PMID:27471384

  19. Aqueous Foam Stabilized by Tricationic Amphiphilic Surfactants

    Science.gov (United States)

    Heerschap, Seth; Marafino, John; McKenna, Kristin; Caran, Kevin; Feitosa, Klebert; Kevin Caran's Research Group Collaboration

    2015-03-01

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. The development of novel architectures with multi-cephalic/tailed molecules have enhanced their anti-bacterial activity in connection with tail length and the nature of the head group. Here we report on the foamability of two triple head double, tail cationic surfactants (M-1,14,14, M-P, 14,14) and a triple head single tail cationic surfactant (M-1,1,14) and compare them with commercially available single headed, single tailed anionic and cationic surfactants (SDS,CTAB and DTAB). The results show that bubble rupture rate decrease with the length of the carbon chain irrespective of head structure. The growth rate of bubbles with short tailed surfactants (SDS) and longer, single tailed tricationic surfactants (M-1,1,14) was shown to be twice as high as those with longer tailed surfactants (CTAB, M-P,14,14, M-1,14,14). This fact was related to the size variation of bubbles, where the foams made with short tail surfactants exhibited higher polydispersivity than those with short tails. This suggests that foams with tricationic amphiphilics are closed linked to their tail length and generally insensitive to their head structure.

  20. Amphiphile nanoarchitectonics: from basic physical chemistry to advanced applications

    Energy Technology Data Exchange (ETDEWEB)

    Ramanathan, Nathan Muruganathan [ORNL; Shrestha, Lok Kumar [International Center for Materials Nanoarchitectonics (MANA); Mori, Taizo [International Center for Materials Nanoarchitectonics (MANA); Ji, Dr. Qingmin [National Institute for Materials Science, Tsukuba, Japan; Hill, Dr. Jonathan P [National Institute for Materials Science, Tsukuba, Japan; Ariga, Katsuhiko [National Institute for Materials Science, Tsukuba, Japan

    2013-01-01

    Amphiphiles, either synthetic or natural, are structurally simple molecules with the unprecedented capacity to self-assemble into complex, hierarchical geometries in nanospace. Effective self-assembly processes of amphiphiles are often used to mimic biological systems, such as, assembly of lipids and proteins, which has paved a way for bottom-up nanotechnology with bio-like advanced functions. Recent developments on nanostructure formation combine simple processes of assembly with the more advanced concept of nanoarchitectonics. In this pespective, we summarize research on self-assembly of amphiphilic molecules such as lipids, surfactants or block copolymers that are a focus of interest for many colloid, polymer, and materials scientists and which have become increasingly important in emerging nanotechnology. Because the fundamental science of amphiphiles was initially developed for their solution assembly then transferred to assemblies on surfaces as a development of nanotechnological technique, this perspective attempts to mirro this development by introducing solution systems and progressing to interfacial systems, which are roughly categorized as (i) basic properties of amphiphiles, (ii) self-assembly of amphiphiles in bulk phases, (iii) assembly on static surfaces, (iv) assembly at dynamic interfaces, and (v) advanced topics from simulation to application. This progression also represents the evolution of amphiphile science and technology from simple assemblies to advanced assemblies to nanoarchitectonics.

  1. Biophysical properties of phenyl succinic acid derivatised hyaluronic acid

    DEFF Research Database (Denmark)

    Neves-Petersen, Maria Teresa; Klitgaard, Søren; Skovsen, Esben;

    2010-01-01

    Modification of hyaluronic acid (HA) with aryl succinic anhydrides results in new biomedical properties of HA as compared to non-modified HA, such as more efficient skin penetration, stronger binding to the skin, and the ability to blend with hydrophobic materials. In the present study, hyaluronic...

  2. FORMULATION AND EVALUATION OF METAPROLOL SUCCINATE EXTENDED RELEASE PELLETS

    Directory of Open Access Journals (Sweden)

    Ahishek Perumalla

    2012-11-01

    Full Text Available The aim and of the present study is to develop a pharmaceutically stable and quality improved formulation of Metoprolol succinate extended release pellets. To achieve this goal various prototype formulation trials were formulated and the evaluated with respect to the various quality controls such as dissolution, assay and stability studies will be under taken. Metoprolol succinate is used in the treatment of hyper tension, angina pectoris (chest pain and myocardial infarction. The study was undertaken with an aim to formulate Metoprolol succinate extended release pellets. The optimized batch MSER CF7 is made up of 7% wetting agent and 4.5% binder. The evaluation tests that were conducted for the pellets also showed satisfactory results.The best trial was optimized by comparing the drug release profile with the innovator and the MSER F7 showed better results compared to the other formulations and the evaluation studies were conducted for the MSER F7. It showed good results in formulation of stable dose.The pellets were evaluated for the flow properties, sieve analysis and accelerated stability studies for 3months. The pellets showed good flow properties and also showed uniform size which indicates uniform coating.Finally we concluded that the Metoprolol succinate pellets MSER F7 are prepared and these showed good physico-chemical properties and the dissolution results showed satisfactory results when compared with the innovator drug.

  3. Novel amphiphilic networks for biological use

    Czech Academy of Sciences Publication Activity Database

    Toman, Luděk; Janata, Miroslav; Spěváček, Jiří; Sikora, Antonín; Pleštil, Josef; Michálek, Jiří; Dvořánková, B.; Vlček, Petr; Látalová, Petra; Masař, Bohumil

    Prague: Czech Society for New Materials and Technologies, 2005. Poster Session II. [European Congress on Advanced Materials and Processes. 5.9.2005-8.9.2005, Prague] R&D Projects: GA ČR GA203/04/1050 Keywords : polyisobutylene * poly(2-hydroxyethyl methacrylate) * amphiphilic networks Subject RIV: CD - Macromolecular Chemistry http://webdb.dgm.de/dgm_lit/prg/FMPro?-db=w%5fprogram&- format =prog%5fpaper%5fresults.htm&-lay=standard&TB=%3d%3d688&tgb%5fsymposium%5fund%5fnr=B14%20Engineering%20and%20Design%20of%20Biomedical%20Materials&-max=20&-skip=20&-token.0=688&-token.1=B14%20Engineering%20and%20Design%20of%20Biomedical%20Materials&-find=

  4. Phase behavior of an amphiphilic fluid.

    Science.gov (United States)

    Schoen, Martin; Giura, Stefano; Klapp, Sabine H L

    2014-01-01

    We invoke mean-field density functional theory (DFT) to investigate the phase behavior of an amphiphilic fluid composed of a hard-sphere core plus a superimposed anisometric Lennard-Jones perturbation. The orientation dependence of the interactions consists of a contribution analogous to the interaction potential between a pair of "spins" in the classical, three-dimensional Heisenberg fluid and another one reminiscent of the interaction between (electric or magnetic) point dipoles. At fixed orientation both contributions are short-range in nature decaying as r-6 (r being the separation between the centers of mass of a pair of amphiphiles). Based upon two mean-field-like approximations for the pair correlation function that differ in the degree of sophistication we derive expressions for the phase boundaries between various isotropic and polar phases that we solve numerically by the Newton-Raphson method. For sufficiently strong coupling between the Heisenberg "spins" both mean-field approximations generate three topologically different and generic types of phase diagrams that are observed in agreement with earlier work [see, for example, Tavares et al., Phys. Rev. E 52, 1915 (1995)]. Whereas the dipolar contribution alone is incapable of stabilizing polar phases on account of its short-range nature it is nevertheless important for details of the phase diagram such as location of the gas-isotropic liquid critical point, triple, and tricritical points. By tuning the dipolar coupling constant suitably one may, in fact, switch between topologically different phase diagrams. Employing also Monte Carlo simulations in the isothermal-isobaric ensemble the general topology of the DFT phase diagrams is confirmed. PMID:24580230

  5. Facially amphiphilic thiol capped gold and silver nanoparticles

    Indian Academy of Sciences (India)

    Shreedhar Bhata; Uday Maitra

    2008-11-01

    A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article.

  6. Facially amphiphilic thiol capped gold and silver nanoparticles

    OpenAIRE

    Bhat, Shreedhar; Maitra, Uday

    2008-01-01

    A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article.

  7. Rational design of purely peptidic amphiphiles for drug delivery applications

    OpenAIRE

    Bruyn Ouboter, Dirk de

    2011-01-01

    A broad range of new properties is emerging from supramolecular aggregates. Self-assembled structures of purely peptidic amphiphiles exploit these properties to produce biocompatible, biodegradable, smart materials for drug administration. This thesis explores the design, synthesis, purification, characterization of purely peptidic amphiphiles, and evaluates potential applications. The first chapter provides a general introduction to the field of self-assembly, and of drug delivery as com...

  8. Wetting in mixtures of water, nonionic amphiphiles, and nonpolar solvents

    Science.gov (United States)

    Kahlweit, M.; Busse, G.

    1989-07-01

    As is well known, medium- and long-chain alkanes do not spread across H2O-air interfaces, but shape a lens. In this paper it is shown that the same holds for the upper amphiphile-rich phase in binary H2O-amphiphile mixtures with medium- and long-chain nonionic amphiphiles that show a (closed) miscibility gap with water. This finding is somewhat unexpected because surfactants form monolayers at H2O-air interfaces which should facilitate the spreading of the amphiphile-rich phase. This wetting behavior corresponds to that in ternary H2O-oil-nonionic amphiphile mixtures with a three-phase body, in which the middle amphiphile-rich phase does not spread across the H2O-oil interface. The results may stimulate further studies on critical-point wetting [for a recent review see, e.g., S. Dietrich, in Phase Transitions and Critical Phenomena, edited by C. Domb and J. L. Lebowitz (Academic, London, 1988), Vol. 12, p. 1.], and may also help clarifying the properties of microemulsions [for a recent review see, e.g., M. Kahlweit, R. Strey, P. Firman, D. Haase, J. Jen, and R. Schomäcker, Langmuir 4, 499 (1988)].

  9. Succinate dehydrogenase subunit D and succinate dehydrogenase subunit B mutation analysis in canine phaeochromocytoma and paraganglioma.

    Science.gov (United States)

    Holt, D E; Henthorn, P; Howell, V M; Robinson, B G; Benn, D E

    2014-07-01

    Phaeochromocytomas (PCs) are tumours of the adrenal medulla chromaffin cells. Paragangliomas (PGLs) arise in sympathetic ganglia (previously called extra-adrenal PCs) or in non-chromaffin parasympathetic ganglia cells that are usually non-secretory. Parenchymal cells from these tumours have a common embryological origin from neural crest ectoderm. Several case series of canine PCs and PGLs have been published and a link between the increased incidence of chemoreceptor neoplasia in brachycephalic dog breeds and chronic hypoxia has been postulated. A similar link to hypoxia in man led to the identification of germline heterozygous mutations in the gene encoding succinate dehydrogenase subunit D (SDHD) and subsequently SDHA, SDHB and SDHC in similar tumours. We investigated canine PCs (n = 6) and PGLs (n = 2) for SDHD and SDHB mutations and in one PGL found a somatic SDHD mutation c.365A>G (p.Lys122Arg) in exon 4, which was not present in normal tissue from this brachycephalic dog. Two PCs were heterozygous for both c.365A>G (p.Lys122Arg) mutation and an exon 3 silent variant c.291G>A. We also identified the heterozygous SDHB exon 2 mutation c.113G>A (p.Arg38Gln) in a PC. These results illustrate that genetic mutations may underlie tumourigenesis in canine PCs and PGLs. The spontaneous nature of these canine diseases and possible association of PGLs with hypoxia in brachycephalic breeds may make them an attractive model for studying the corresponding human tumours. PMID:24813157

  10. A novel organic nonlinear optical crystal: Creatininium succinate

    International Nuclear Information System (INIS)

    A novel organic material complex of creatininium succinate (CS) has been synthesized and single crystals were grown by the reaction of creatinine and succinic acid from aqueous solution by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated using single crystal X-ray diffraction analysis and the structure was refined by least-squares method to R = 0.027 for 1840 reflections. FT-IR spectral investigation has been carried out to identify the various functional groups in the title compound. UV–Vis transmission was carried out which shows the crystal has a good optical transmittance in the visible region with lower cutoff wavelength around 220 nm. Nonlinear optical property of the crystal was confirmed by Kurtz-Perry powder technique

  11. Internal electron transfer within mitochondrial succinate-cytochrome C reductase

    International Nuclear Information System (INIS)

    Internal electron transfer within succinate-cytochrome C reductase from pigeon breast muscle mitochondria was followed by the pulse radiolytic technique. The electron equivalent is transferred from an unknown donor to b type cytochrome(s), in a first order process with a rate constant of: 660 +- 150s-1. This process might be the rate determining step of electron transfer in mitochondria, since it is similar in rate to the turnover number of the mitochondrial respiratory chain

  12. Molecular properties of succinate dehydrogenase isolated from Micrococcus luteus (lysodeikticus).

    OpenAIRE

    Crowe, B A; Owen, P.(Imperial College London, London, United Kingdom)

    1983-01-01

    Succinate dehydrogenase (EC 1.3.99.1) of Micrococcus luteus was selectively precipitated from Triton X-100-solubilized membranes by using specific antiserum. The precipitated enzyme contained equimolar amounts of four polypeptides with apparent molecular weights of 72,000, 30,000, 17,000, and 15,000. The 72,000 polypeptide possessed a covalently bound flavin prosthetic group and appeared to be strongly antigenic as judged by immunoprinting experiments. Low-temperature absorption spectroscopy ...

  13. Visual evoked potentials in succinate semialdehyde dehydrogenase (SSADH) Deficiency

    OpenAIRE

    Di Rosa, G.; Malaspina, P; P. Blasi(INAF Arcetri); Dionisi-Vici, C.; Rizzo, C; Tortorella, G; Crutchfield, S. R.; Gibson, K. M.

    2009-01-01

    In mammals, increased GABA in the central nervous system has been associated with abnormalities of visual evoked potentials (VEPs), predominantly manifested as increased latency of the major positive component P100. Accordingly, we hypothesized that patients with a defect in GABA metabolism, succinate semialdehyde dehydrogenase (SSADH) deficiency (in whom supraphysiological levels of GABA accumulate), would manifest VEP anomalies. We evaluated VEPs on two patients with confirmed SSADH deficie...

  14. Cell-permeable succinate prodrugs bypass mitochondrial complex I deficiency.

    Science.gov (United States)

    Ehinger, Johannes K; Piel, Sarah; Ford, Rhonan; Karlsson, Michael; Sjövall, Fredrik; Frostner, Eleonor Åsander; Morota, Saori; Taylor, Robert W; Turnbull, Doug M; Cornell, Clive; Moss, Steven J; Metzsch, Carsten; Hansson, Magnus J; Fliri, Hans; Elmér, Eskil

    2016-01-01

    Mitochondrial complex I (CI) deficiency is the most prevalent defect in the respiratory chain in paediatric mitochondrial disease. This heterogeneous group of diseases includes serious or fatal neurological presentations such as Leigh syndrome and there are very limited evidence-based treatment options available. Here we describe that cell membrane-permeable prodrugs of the complex II substrate succinate increase ATP-linked mitochondrial respiration in CI-deficient human blood cells, fibroblasts and heart fibres. Lactate accumulation in platelets due to rotenone-induced CI inhibition is reversed and rotenone-induced increase in lactate:pyruvate ratio in white blood cells is alleviated. Metabolomic analyses demonstrate delivery and metabolism of [(13)C]succinate. In Leigh syndrome patient fibroblasts, with a recessive NDUFS2 mutation, respiration and spare respiratory capacity are increased by prodrug administration. We conclude that prodrug-delivered succinate bypasses CI and supports electron transport, membrane potential and ATP production. This strategy offers a potential future therapy for metabolic decompensation due to mitochondrial CI dysfunction. PMID:27502960

  15. Interfacial adsorption and aggregation of amphiphilic proteins

    Science.gov (United States)

    Cheung, David

    2012-02-01

    The adsorption and aggregation on liquid interfaces of proteins is important in many biological contexts, such as the formation of aerial structures, immune response, and catalysis. Likewise the adsorption of proteins onto interfaces has applications in food technology, drug delivery, and in personal care products. As such there has been much interest in the study of a wide range of biomolecules at liquid interfaces. One class of proteins that has attracted particular attention are hydrophobins, small, fungal proteins with a distinct, amphiphilic surface structure. This makes these proteins highly surface active and they recently attracted much interest. In order to understand their potential applications a microscopic description of their interfacial and self-assembly is necessary and molecular simulation provides a powerful tool for providing this. In this presentation I will describe some recent work using coarse-grained molecular dynamics simulations to study the interfacial and aggregation behaviour of hydrophobins. Specifically this will present the calculation of their adsorption strength at oil-water and air-water interfaces, investigate the stability of hydrophobin aggregates in solution and their interaction with surfactants.

  16. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment.

    Science.gov (United States)

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C; Anand, Atul; Cederkvist, Luise; Petersen, Nikolaj H T; Nylandsted, Jesper; Stenvang, Jan; Mellemgaard, Anders; Østerlind, Kell; Friis, Søren; Jäättelä, Marja

    2016-07-01

    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy. PMID:27333030

  17. Succinic acid production with metabolically engineered E. coli recovered from two-stage fermentation.

    Science.gov (United States)

    Ma, Jiang-Feng; Jiang, Min; Chen, Ke-Quan; Xu, Bing; Liu, Shu-Wen; Wei, Ping; Ying, Han-Jie

    2010-10-01

    Escherichia coli AFP111 cells recovered from spent two-stage fermentation broth were investigated for additional production of succinic acid under anaerobic conditions. Recovered cells produced succinic acid in an aqueous environment with no nutrient supplementation except for glucose and MgCO(3). In addition, initial glucose concentration and cell density had a significant influence on succinic acid mass yield and productivity. Although the final concentration of succinic acid from recovered cells was lower than from two-stage fermentation, an average succinic acid mass yield of 0.85 g/g was achieved with an average productivity of 1.81 g/l h after three rounds of recycling, which was comparable to two-stage fermentation. These results suggested that recovered cells might be reused for the efficient production of succinic acid. PMID:20495946

  18. Synthesis and characterization of novel poly(butylene succinate-co-2-methyl-1,3-propylene succinates

    Directory of Open Access Journals (Sweden)

    2011-04-01

    Full Text Available Poly(butylene succinate (PBSu, poly(2-methyl-1,3-propylene succinate (PMPSu, and PBSu-rich copolyesters were synthesized using an effective catalyst, titanium tetraisopropoxide. Measurements of intrinsic viscosity (1.20–1.28 dl/g and gel permeation chromatography demonstrated the success of the preparation of polyesters with high molecular weights. The compositions of the copolyesters were determined in three approaches from 1H and 13C NMR (nuclear magnetic resonance analyses, and good agreement between the results was obtained. The distributions of the comonomers were found to be random from the spectra of carbonyl carbon. Their thermal properties were elucidated using a differential scanning calorimeter and a thermogravimetric analyzer. No marked difference exists among the thermal stabilities of these polyesters. However, the window between the glass transition and the melting temperatures becomes narrower with the increase in the concentration of 2-methyl-1,3-propylene succinate in the copolymers. Additionally, the cold crystallization ability decreases considerably. Finally, PMPSu is an amorphous homopolymer. Wide-angle X-ray diffractograms of isothermally crystallized copolyesters also follow the same trend.

  19. FORMULATION AND EVALUATION OF CONTROLLED POROSITY OSMOTIC DRUG DELIVERY SYSTEM OF METOPROLOL SUCCINATE

    OpenAIRE

    Hardik Patel* and M. M. Patel

    2012-01-01

    Controlled porosity osmotic tablet of metoprolol succinate prepared and evaluated in this study. Metoprolol succinate is very high soluble drug, so complete drug release obtained very fast. It is difficult to formulate osmotic tablet of Metoprolol succinate which gives drug release up to 24 hr at zero order. To get desired dissolution profile various formulation parameters like osmogen concentration, level of weight gain and level of pore former concentration were studied. Hypromellose was ad...

  20. Design of nanostructures based on aromatic peptide amphiphiles.

    Science.gov (United States)

    Fleming, Scott; Ulijn, Rein V

    2014-12-01

    Aromatic peptide amphiphiles are gaining popularity as building blocks for the bottom-up fabrication of nanomaterials, including gels. These materials combine the simplicity of small molecules with the versatility of peptides, with a range of applications proposed in biomedicine, nanotechnology, food science, cosmetics, etc. Despite their simplicity, a wide range of self-assembly behaviours have been described. Due to varying conditions and protocols used, care should be taken when attempting to directly compare results from the literature. In this review, we rationalise the structural features which govern the self-assembly of aromatic peptide amphiphiles by focusing on four segments, (i) the N-terminal aromatic component, (ii) linker segment, (iii) peptide sequence, and (iv) C-terminus. It is clear that the molecular structure of these components significantly influences the self-assembly process and resultant supramolecular architectures. A number of modes of assembly have been proposed, including parallel, antiparallel, and interlocked antiparallel stacking conformations. In addition, the co-assembly arrangements of aromatic peptide amphiphiles are reviewed. Overall, this review elucidates the structural trends and design rules that underpin the field of aromatic peptide amphiphile assembly, paving the way to a more rational design of nanomaterials based on aromatic peptide amphiphiles. PMID:25199102

  1. Magnetic Amphiphilic Composites Applied for the Treatment of Biodiesel Wastewaters

    Directory of Open Access Journals (Sweden)

    Bruno R. S. Lemos

    2012-05-01

    Full Text Available In this work, new magnetic amphiphilic composites were prepared by chemical vapor deposition with ethanol on the surface of hydrophilic natural chrysotile matrix containing Fe catalyst. XRD, Raman, Mössbauer and SEM analyses suggest the formation of a complex nanostructured material composed of hydrophobic carbon nanotubes/nanofibers grown on the hydrophilic surface of the MgSi fiber mineral and the presence of Fe metallic nanoparticles coated by carbon. These nanostructured particles show amphiphilic properties and interact very well with both oil and aqueous phases. When added to emulsions the amphiphilic particles locate on the oil/water interface and, under a magnetic field, the oil droplets collapsed leading to the separation of the aqueous and oil phases. Preliminary work showed excellent results on the use of these particles to break wastewater emulsions in the biodiesel process.

  2. Synthesis of silver nanoparticles in melts of amphiphilic polyesters

    International Nuclear Information System (INIS)

    The current work presents a one-step procedure for the synthesis of amphiphilic silver nanoparticles suitable for production of silver-filled polymeric materials. This solvent free synthesis via reduction of Tollens’ reagent as silver precursor in melts of amphiphilic polyesters consisting of hydrophilic poly(ethylene glycol) blocks and hydrophobic alkyl chains allows the production of silver nanoparticles without any by-product formation. This makes them especially interesting for the production of medical devices with antimicrobial properties. In this article the influences of the chain length of the hydrophobic block in the amphiphilic polyesters and the process temperature on the particle size distribution (PSD) and the stability of the particles against agglomeration are discussed. According to the results of spectroscopic and viscosimetric investigations the silver precursor is reduced to elemental silver nanoparticles by a single electron transfer process from the poly(ethylene glycol) chain to the silver ion. (paper)

  3. Non-isothermal crystallization kinetics and characterization of biodegradable poly(butylene succinate-co-neopentyl glycol succinate) copolyesters.

    Science.gov (United States)

    Xie, Wen-Jie; Zhou, Xiao-Ming

    2015-01-01

    Both biodegradable aliphatic neat poly(butylene succinate) (PBS) and poly(butylene succinate-co-neopentyl glycol succinate) (P(BS-co-NPGS)) copolyesters with different 1,4-butanediol/neopentyl glycol ratios were synthesized through a two-step process of transesterification and polycondensation using stannous chloride and 4-Methylbenzenesulfonic acid as the co-catalysts. The structure, non-isothermal crystallization behavior, crystalline morphology and crystal structure of neat PBS and P(BS-co-NPGS) copolyesters were characterized by (1)H NMR, differential scanning calorimetry (DSC), polarized optical microscope (POM) and wide angle X-ray diffraction (WAXD), respectively. The Avrami equation modified by Jeziorny and Mo's method was employed to describe the non-isothermal crystallization kinetics of the neat PBS and its copolyesters. The modified Avrami equation could adequately describe the primary stage of non-isothermal crystallization kinetics of the neat PBS and its copolyesters. Mo's method provided a fairly satisfactory description of the non-isothermal crystallization of neat PBS and its copolyesters. Interestingly, the values of 1/t1/2, Zc and F(T) obtained by the modified Avrami equation and Mo's method analysis indicated that the crystallization rate increased first and then decreased with an increase of NPGS content compared that of neat PBS, whereas the crystallization mechanism almost kept unchanged. The results of tensile testing showed that the ductility of PBS was largely improved by incorporating NPGS units. The elongation at break increased remarkably with increasing NPGS content. In particular, the sample with 20% NPGS content showed around 548% elongation at break. PMID:25491999

  4. 21 CFR 172.765 - Succistearin (stearoyl propylene glycol hydrogen succinate).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Succistearin (stearoyl propylene glycol hydrogen succinate). 172.765 Section 172.765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... propylene glycol hydrogen succinate). The food additive succistearin (stearoyl propylene glycol...

  5. Succinate-CoA ligase deficiency due to mutations in SUCLA2 and SUCLG1

    DEFF Research Database (Denmark)

    Carrozzo, Rosalba; Verrigni, Daniela; Rasmussen, Magnhild; de Coo, Rene; Amartino, Hernan; Bianchi, Marzia; Buhas, Daniela; Mesli, Samir; Naess, Karin; Born, Alfred Peter; Woldseth, Berit; Prontera, Paolo; Batbayli, Mustafa; Ravn, Kirstine; Joensen, Fróði; Cordelli, Duccio M; Santorelli, Filippo Maria; Tulinius, Mar; Darin, Niklas; Duno, Morten; Jouvencel, Philippe; Burlina, Alberto; Stangoni, Gabriela; Bertini, Enrico; Redonnet-Vernhet, Isabelle; Wibrand, Flemming; Dionisi-Vici, Carlo; Uusimaa, Johanna; Vieira, Paivi; Osorio, Andrés Nascimento; McFarland, Robert; Taylor, Robert W; Holme, Elisabeth; Ostergaard, Elsebet

    2016-01-01

    BACKGROUND: The encephalomyopathic mtDNA depletion syndrome with methylmalonic aciduria is associated with deficiency of succinate-CoA ligase, caused by mutations in SUCLA2 or SUCLG1. We report here 25 new patients with succinate-CoA ligase deficiency, and review the clinical and molecular findin...

  6. Metabolic evolution of energy-conserving pathways for succinate production in Escherichia coli

    OpenAIRE

    Zhang, Xueli; Jantama, Kaemwich; Moore, Jonathan C.; Jarboe, Laura R.; Shanmugam, Keelnatham T.; Lonnie O. Ingram

    2009-01-01

    During metabolic evolution to improve succinate production in Escherichia coli strains, significant changes in cellular metabolism were acquired that increased energy efficiency in two respects. The energy-conserving phosphoenolpyruvate (PEP) carboxykinase (pck), which normally functions in the reverse direction (gluconeogenesis; glucose repressed) during the oxidative metabolism of organic acids, evolved to become the major carboxylation pathway for succinate production. Both PCK enzyme acti...

  7. Structural basis for the binding of succinate to succinyl-CoA synthetase.

    Science.gov (United States)

    Huang, Ji; Fraser, Marie E

    2016-08-01

    Succinyl-CoA synthetase catalyzes the only step in the citric acid cycle that provides substrate-level phosphorylation. Although the binding sites for the substrates CoA, phosphate, and the nucleotides ADP and ATP or GDP and GTP have been identified, the binding site for succinate has not. To determine this binding site, pig GTP-specific succinyl-CoA synthetase was crystallized in the presence of succinate, magnesium ions and CoA, and the structure of the complex was determined by X-ray crystallography to 2.2 Å resolution. Succinate binds in the carboxy-terminal domain of the β-subunit. The succinate-binding site is near both the active-site histidine residue that is phosphorylated in the reaction and the free thiol of CoA. The carboxy-terminal domain rearranges when succinate binds, burying this active site. However, succinate is not in position for transfer of the phosphoryl group from phosphohistidine. Here, it is proposed that when the active-site histidine residue has been phosphorylated by GTP, the phosphohistidine displaces phosphate and triggers the movement of the carboxylate of succinate into position to be phosphorylated. The structure shows why succinyl-CoA synthetase is specific for succinate and does not react appreciably with citrate nor with the other C4-dicarboxylic acids of the citric acid cycle, fumarate and oxaloacetate, but shows some activity with L-malate. PMID:27487822

  8. Development and evaluation of vitamin E d-α-tocopheryl polyethylene glycol 1000 succinate-mixed polymeric phospholipid micelles of berberine as an anticancer nanopharmaceutical

    Science.gov (United States)

    Shen, Roger; Kim, Jane J; Yao, Mingyi; Elbayoumi, Tamer A

    2016-01-01

    Berberine (Brb) is an active alkaloid occurring in various common plant species, with well-recognized potential for cancer therapy. Brb not only augments the efficacy of antineoplastic chemotherapy and radiotherapy but also exhibits direct antimitotic and proapoptotic actions, along with distinct antiangiogenic and antimetastatic activities in a variety of tumors. Despite its low systemic toxicity, several pharmaceutical challenges limit the application of Brb in cancer therapy (ie, extremely low solubility and permeability, very poor pharmacokinetics (PKs), and oral bioavailability). Among lipid-based nanocarriers investigated recently for Brb, stealth amphiphilic micelles of polymeric phospholipid conjugates were studied here as a promising strategy to improve Brb delivery to tumors. Specifically, physicochemically stable micelles made of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol)-2000] (PEG-PE) mixed with d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) (PEG-succinate ester of vitamin E), in a 3:1 M ratio, increased Brb solubilization by 300%. Our PEG-PE/TPGS-mixed micelles firmly retained the incorporated Brb, displaying extended-release profile in simulated media, with up to 30-fold projected improvement in simulated PKs of Brb. Owing to the markedly better uptake of Brb-containing mixed micelles in vitro, our Brb-mixed micelles nanoformulation significantly amplified apoptosis and overall cytotoxic effectiveness against monolayer and spheroid cultures of human prostate carcinomas (16- to 18-fold lower half-maximal inhibitory concentration values in PC3 and LNPaC, respectively), compared to free Brb. Mixed PEG-PE/TPGS micelles represent a promising delivery platform for the sparingly soluble anticancer agent, Brb, encouraging further pharmaceutical development of this drug for cancer therapy. PMID:27217747

  9. Paclitaxel-loaded poly(glycolide-co-ε-caprolactone-b-D-α-tocopheryl polyethylene glycol 2000 succinate nanoparticles for lung cancer therapy

    Directory of Open Access Journals (Sweden)

    Zhao TJ

    2013-05-01

    Full Text Available Tiejun Zhao,1 Hezhong Chen,1 Yuchao Dong,2 Jiajun Zhang,1 Haidong Huang,2 Ji Zhu,1 Wei Zhang21Institute of Cardiothoracic Surgery, 2Respiratory Department, Changhai Hospital, Shanghai, People's Republic of ChinaAbstract: In order to improve the therapeutic efficacy and minimize the side effects of lung cancer chemotherapy, the formulation of paclitaxel-loaded poly(glycolide-co-ε-caprolactone-b-D-α-tocopheryl polyethylene glycol 2000 succinate nanoparticles (PTX-loaded [PGA-co-PCL]-b-TPGS2k NPs was prepared. The novel amphiphilic copolymer (PGA-co-PCL-b-TPGS2k was synthesized by ring-opening polymerization and characterized by proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. The PTX-loaded (PGA-co-PCL-b -TPGS2k NPs were characterized in terms of size, size distribution, zeta potential, drug encapsulation, surface morphology, and drug release. In vitro cellular uptakes of NPs were investigated with confocal laser scanning microscopy, indicating the coumarin 6-loaded (PGA-co-PCL-b -TPGS2k NPs could be internalized by human lung cancer A-549 cells. The antitumor effect of PTX-loaded NPs was evaluated, both in vitro and in vivo, on an A-549 cell tumor-bearing mouse model via intratumoral injection. The commercial PTX formulation Taxol was chosen as the reference. Experimental results showed that the PTX-loaded NPs possessed higher cytotoxicity and could effectively inhibit the growth of tumor. All the results suggested that amphiphilic copolymer (PGA-co-PCL-b -TPGS2k could act as a potential biological material for nanoformulation in the treatment of lung cancer.Keywords: (PGA-co-PCL-b TPGS2k, paclitaxel, nanoparticles, drug delivery, lung cancer

  10. Synthesis and characterization of birch wood xylan succinoylated in 1-n-butyl-3-methylimidazolium chloride

    DEFF Research Database (Denmark)

    Hansen, Natanya Majbritt Louie; Plackett, David

    2011-01-01

    The chemical modification of birch wood xylan was undertaken in the ionic liquid 1-n-butyl-3-methylimidazolium chloride (C4mimCl) using three different long-chain succinic anhydrides: n-octenyl succinic anhydride (n-OSA), n-dodecenyl succinic anhydride (n-DDSA) and n-octadecenyl succinic anhydrid...

  11. Succinate production from CO2-grown microalgal biomass as carbon source using engineered Corynebacterium glutamicum through consolidated bioprocessing

    OpenAIRE

    Lee, Jungseok; Sim, Sang Jun; Bott, Michael; Um, Youngsoon; Oh, Min-Kyu; Woo, Han Min

    2014-01-01

    The potential for production of chemicals from microalgal biomass has been considered as an alternative route for CO2 mitigation and establishment of biorefineries. This study presents the development of consolidated bioprocessing for succinate production from microalgal biomass using engineered Corynebacterium glutamicum. Starch-degrading and succinate-producing C. glutamicum strains produced succinate (0.16 g succinate/g total carbon source) from a mixture of starch and glucose as a model m...

  12. Succinic semialdehyde as a substrate for the formation of gamma-aminobutyric acid

    Energy Technology Data Exchange (ETDEWEB)

    van Bemmelen, F.J.; Schouten, M.J.; Fekkes, D.; Bruinvels, J.

    1985-11-01

    The conversion of succinic semialdehyde into gamma-aminobutyric acid (GABA) by GABA-transaminase was measured in rat brain homogenate in the presence of different concentrations of the cosubstrate glutamate. The calculated kinetic parameters of succinic semialdehyde for GABA-transaminase were a limiting Km value of 168 microM and a limiting Vmax value of 38 mumol g-1 h-1. Combination with previously obtained data for the conversion of GABA into succinic semialdehyde revealed a kEq value of 0.04, indicating that equilibrium of GABA-transaminase is biased toward the formation of GABA. The increased formation of GABA in the presence of succinic semialdehyde was not due to an increased conversion of glutamate into GABA by glutamic acid decarboxylase. Therefore these results indicate that succinic semialdehyde can act as a precursor for GABA synthesis.

  13. Succinic semialdehyde as a substrate for the formation of gamma-aminobutyric acid.

    Science.gov (United States)

    van Bemmelen, F J; Schouten, M J; Fekkes, D; Bruinvels, J

    1985-11-01

    The conversion of succinic semialdehyde into gamma-aminobutyric acid (GABA) by GABA-transaminase was measured in rat brain homogenate in the presence of different concentrations of the cosubstrate glutamate. The calculated kinetic parameters of succinic semialdehyde for GABA-transaminase were a limiting Km value of 168 microM and a limiting Vmax value of 38 mumol g-1 h-1. Combination with previously obtained data for the conversion of GABA into succinic semialdehyde revealed a kEq value of 0.04, indicating that equilibrium of GABA-transaminase is biased toward the formation of GABA. The increased formation of GABA in the presence of succinic semialdehyde was not due to an increased conversion of glutamate into GABA by glutamic acid decarboxylase. Therefore these results indicate that succinic semialdehyde can act as a precursor for GABA synthesis. PMID:2864395

  14. Simultaneous saccharification and fermentation of cassava to succinic acid by Escherichia coli NZN111.

    Science.gov (United States)

    Chen, Cuixia; Ding, Shaopeng; Wang, Dezheng; Li, Zhimin; Ye, Qin

    2014-07-01

    In this study, the production of succinic acid from cassava starch and raw cassava instead of glucose by Escherichia coli NZN111 was investigated. During the two-stage fermentation, simultaneous saccharification and fermentation (SSF) was applied in the anaerobic stage. The results showed that both the productivity and specific productivity in the process conducted at 40°C were higher than those in the cultivation conducted at 37°C. The yield of succinic acid based on the amount of added starch reached the highest level 0.86 g/g and cassava starch was almost totally hydrolyzed in the SSF process. With the improved cell density, 127.13 g/L of succinic acid was obtained. When the liquefied crude cassava powder was used directly in SSF, 106.17 g/L of succinic acid was formed. The result showed that crude cassava powder could be another cheap raw material for succinic acid formation. PMID:24787322

  15. Thermochemical pretreatments for enhancing succinic acid production from industrial hemp (Cannabis sativa L.).

    Science.gov (United States)

    Gunnarsson, Ingólfur B; Kuglarz, Mariusz; Karakashev, Dimitar; Angelidaki, Irini

    2015-04-01

    The aim of this study was to develop an efficient thermochemical method for treatment of industrial hemp biomass, in order to increase its bioconversion to succinic acid. Industrial hemp was subjected to various thermochemical pretreatments using 0-3% H2SO4, NaOH or H2O2 at 121-180°C prior to enzymatic hydrolysis. The influence of the different pretreatments on hydrolysis and succinic acid production by Actinobacillus succinogenes 130Z was investigated in batch mode, using anaerobic bottles and bioreactors. Enzymatic hydrolysis and fermentation of hemp material pretreated with 3% H2O2 resulted in the highest overall sugar yield (73.5%), maximum succinic acid titer (21.9 g L(-1)), as well as the highest succinic acid yield (83%). Results obtained clearly demonstrated the impact of different pretreatments on the bioconversion efficiency of industrial hemp into succinic acid. PMID:25682224

  16. Microphase separation of diblock copolymers with amphiphilic segment

    NARCIS (Netherlands)

    Kriksin, Yury A.; Khalatur, Pavel G.; Erukhimovich, Igor Ya.; ten Brinke, Gerrit; Khokhlov, Alexei R.

    2009-01-01

    We present a statistical mechanical approach for predicting the self-assembled morphologies of amphiphilic diblock copolymers in the melt. We introduce two conformationally asymmetric linear copolymer models with a local structural asymmetry, one of a "comb-tail'' type and another that we call "cont

  17. Surface, Interfacial and Tribological Properties of Cereal-based Amphiphiles

    Science.gov (United States)

    Starch, protein and oil are the major components of most cereals such as corn and soybean. These components, with or without further chemical modification, display a number of important amphiphilic characteristics that are of interest in a number of applications. Cereal-based oils have polar compo...

  18. Supramolecular barrels from amphiphilic rigid-flexible macrocycles

    Science.gov (United States)

    Yang, Won-Young; Ahn, Jong-Hyun; Yoo, Yong-Sik; Oh, Nam-Keun; Lee, Myongsoo

    2005-05-01

    Precise control of supramolecular objects requires the rational design of molecular components, because the information determining their specific assembly should be encoded in their molecular architecture. In this context, diverse self-assembling molecules including liquid crystals, dendrimers, block copolymers, hydrogen-bonded complexes and rigid macrocycles are being created as a means of manipulating supramolecular structure. Incorporation of a stiff rod-like building block into an amphiphilic molecular architecture leads to another class of self-assembling molecules. Aggregation of rod building blocks can generate various nanoscale objects including bundles, ribbons, tubules and vesicles, depending on the molecular structure and/or the presence of a selective solvent. We present here an unusual example of supramolecular barrels in the solid and in aqueous solution, based on the self-assembly of amphiphilic rigid-flexible macrocycles driven by non-covalent interactions. Preliminary experiments show that these amphiphilic macrocycles are membrane-active. The amphiphilic macrocycles might thus lead to an excellent model system for exploring biological processes in supramolecular materials.

  19. Cationic amphiphilic non-hemolytic polyacrylates with superior antibacterial activity.

    Science.gov (United States)

    Punia, Ashish; He, Edward; Lee, Kevin; Banerjee, Probal; Yang, Nan-Loh

    2014-07-01

    Acrylic copolymers with appropriate compositions of counits having cationic charge with 2-carbon and 6-carbon spacer arms can show superior antibacterial activities with concomitant very low hemolytic effect. These amphiphilic copolymers represent one of the most promising synthetic polymer antibacterial systems reported. PMID:24854366

  20. Blends of Amphiphilic, Hyperbranched Polyesters and Different Polyolefins

    NARCIS (Netherlands)

    Schmaljohann, D.; Pötschke, P.; Hässler, R.; Voit, B.I.; Froehling, P.E.; Mostert, B.; Loontjens, J.A.

    1999-01-01

    A hyperbranched polyester based on 3,5-dihydroxybenzoic acid was completely modified with dodecanoyl chloride to result in an amphiphilic, globular polymer, which has a polar core and a nonpolar outer sphere with the ability both to incorporate an organic dye and to interact with a nonpolar matrix.

  1. Langmuir monolayer formation of metal complexes from polymerizable amphiphilic ligands

    NARCIS (Netherlands)

    Werkman, PJ; Schouten, AJ

    1996-01-01

    The monolayer behaviour of 4-(10,12-pentacosadiynoicamidomethyl)-pyridine at the air-water interface was studied by measuring the surface pressure-area isotherms. The amphiphile formed stable monolayers with a clear liquid-expanded (LE) to liquid-condensed phase transition at various temperatures. U

  2. Effects of perfluorinated amphiphiles on backward swimming in Paramecium caudatum

    International Nuclear Information System (INIS)

    PFOS and PFOA are ubiquitous contaminants in the environment. We investigated the effects of fluorochemicals on calcium currents in Paramecium caudatum using its behavioral changes. Negatively charged amphiphiles prolonged backward swimming (BWS) of Paramecium. PFOS significantly prolonged BWS, while PFOA was less potent (EC5: 29.8 ± 4.1 and 424.1 ± 124.0 μM, respectively). The BWS prolongation was blocked by cadmium, indicating that the cellular calcium conductance had been modified. The positively charged amphiphile FOSAPrTMA shortened BWS (EC5: 19.1 ± 17.3). Nonionic amphiphiles did not affect BWS. The longer-chain perfluorinated carboxylates PFNA and PFDA were more potent than PFOA (EC5: 98.7 ± 20.1 and 60.4 ± 10.1 μM, respectively). However, 1,8-perfluorooctanedioic acid and 1,10-perfluorodecanedioic acid did not prolong BWS. The critical micelle concentration (CMC) and BWS prolongation for negatively charged amphiphiles showed a clear correlation (r 2 = 0.8008, p < 0.001). In summary, several perfluorochemicals and PFOS and PFOA had similar effects in Paramecium, while chain length, CMC, and electric charge were major determinants of BWS duration

  3. Preparation and Characterization of Amphiphilic Triblock Terpolymer-Based Nanofibers as Antifouling Biomaterials

    KAUST Repository

    Cho, Youngjin

    2012-05-14

    Antifouling surfaces are critical for the good performance of functional materials in various applications including water filtration, medical implants, and biosensors. In this study, we synthesized amphiphilic triblock terpolymers (tri-BCPs, coded as KB) and fabricated amphiphilic nanofibers by electrospinning of solutions prepared by mixing the KB with poly(lactic acid) (PLA) polymer. The resulting fibers with amphiphilic polymer groups exhibited superior antifouling performance to the fibers without such groups. The adsorption of bovine serum albumin (BSA) on the amphiphilic fibers was about 10-fold less than that on the control surfaces from PLA and PET fibers. With the increase of the KB content in the amphiphilic fibers, the resistance to adsorption of BSA was increased. BSA was released more easily from the surface of the amphiphilic fibers than from the surface of hydrophobic PLA or PET fibers. We have also investigated the structural conformation of KB in fibers before and after annealing by contact angle measurements, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and coarse-grained molecular dynamics (CGMD) simulation to probe the effect of amphiphilic chain conformation on antifouling. The results reveal that the amphiphilic KB was evenly distributed within as-spun hybrid fibers, while migrated toward the core from the fiber surface during thermal treatment, leading to the reduction in antifouling. This suggests that the antifouling effect of the amphiphilic fibers is greatly influenced by the arrangement of amphiphilic groups in the fibers. © 2012 American Chemical Society.

  4. Succinic Acid Production from Lignocellulosic Hydrolysate by Basfia succiniciproducens

    Energy Technology Data Exchange (ETDEWEB)

    Salvachua, Davinia; Smith, Holly; John, Peter C.; Mohagheghi, Ali; Peterson, Darren J.; Black, Brenna A.; Dowe, Nancy; Beckham, Gregg T.

    2016-08-01

    The production of chemicals alongside fuels will be essential to enhance the feasibility of lignocellulosic biorefineries. Succinic acid (SA), a naturally occurring C4-diacid, is a primary intermediate of the tricarboxylic acid cycle and a promising building block chemical that has received significant industrial attention. Basfia succiniciproducens is a relatively unexplored SA-producing bacterium with advantageous features such as broad substrate utilization, genetic tractability, and facultative anaerobic metabolism. Here B. succiniciproducens is evaluated in high xylose-content hydrolysates from corn stover and different synthetic media in batch fermentation. SA titers in hydrolysate at an initial sugar concentration of 60 g/L reached up to 30 g/L, with metabolic yields of 0.69 g/g, and an overall productivity of 0.43 g/L/h. These results demonstrate that B. succiniciproducens may be an attractive platform organism for bio-SA production from biomass hydrolysates.

  5. Enhanced performance of alkylated graphene reinforced polybutylene succinate nanocomposite

    Science.gov (United States)

    Abidin, A. S. Zainal; Yusoh, K.; Jamari, S. S.; Abdullah, A. H.; Ismail, Z.

    2016-07-01

    Polybutylene succinate (PBS) was being grafted with octadecylamine-functionalized graphene oxide (GO-ODA) to produce novel PBS/GO-ODA nanocomposites by solution blending technique. Alkylated graphene oxide has superhydrophobic surface thus improved the affinity of the filler with low polar polymer such as PBS. The structure and compatibility of the filler and nanocomposites were being characterized using Fourier transform infrared spectroscopy (FTIR), Universal tensile machine (UTM) and thermogravimetric analysis (TGA). Enhancement of tensile strength and Young's modulus by 30% and 165% respectively was achieved with cooperation of 0.5% GO-ODA loading. The functionalization of GO-ODA in PBS matrix leads to the improvement in the nanocomposites properties.

  6. Succinic acid production from lignocellulosic hydrolysate by Basfia succiniciproducens.

    Science.gov (United States)

    Salvachúa, Davinia; Smith, Holly; St John, Peter C; Mohagheghi, Ali; Peterson, Darren J; Black, Brenna A; Dowe, Nancy; Beckham, Gregg T

    2016-08-01

    The production of chemicals alongside fuels will be essential to enhance the feasibility of lignocellulosic biorefineries. Succinic acid (SA), a naturally occurring C4-diacid, is a primary intermediate of the tricarboxylic acid cycle and a promising building block chemical that has received significant industrial attention. Basfia succiniciproducens is a relatively unexplored SA-producing bacterium with advantageous features such as broad substrate utilization, genetic tractability, and facultative anaerobic metabolism. Here B. succiniciproducens is evaluated in high xylose-content hydrolysates from corn stover and different synthetic media in batch fermentation. SA titers in hydrolysate at an initial sugar concentration of 60g/L reached up to 30g/L, with metabolic yields of 0.69g/g, and an overall productivity of 0.43g/L/h. These results demonstrate that B. succiniciproducens may be an attractive platform organism for bio-SA production from biomass hydrolysates. PMID:27179951

  7. Cardiac-specific succinate dehydrogenase deficiency in Barth syndrome.

    Science.gov (United States)

    Dudek, Jan; Cheng, I-Fen; Chowdhury, Arpita; Wozny, Katharina; Balleininger, Martina; Reinhold, Robert; Grunau, Silke; Callegari, Sylvie; Toischer, Karl; Wanders, Ronald Ja; Hasenfuß, Gerd; Brügger, Britta; Guan, Kaomei; Rehling, Peter

    2015-01-01

    Barth syndrome (BTHS) is a cardiomyopathy caused by the loss of tafazzin, a mitochondrial acyltransferase involved in the maturation of the glycerophospholipid cardiolipin. It has remained enigmatic as to why a systemic loss of cardiolipin leads to cardiomyopathy. Using a genetic ablation of tafazzin function in the BTHS mouse model, we identified severe structural changes in respiratory chain supercomplexes at a pre-onset stage of the disease. This reorganization of supercomplexes was specific to cardiac tissue and could be recapitulated in cardiomyocytes derived from BTHS patients. Moreover, our analyses demonstrate a cardiac-specific loss of succinate dehydrogenase (SDH), an enzyme linking the respiratory chain with the tricarboxylic acid cycle. As a similar defect of SDH is apparent in patient cell-derived cardiomyocytes, we conclude that these defects represent a molecular basis for the cardiac pathology in Barth syndrome. PMID:26697888

  8. Formulation and evaluation of nasal mucoadhesive microspheres of sumatriptan succinate.

    Science.gov (United States)

    Jain, Snehal A; Chauk, Dheeraj S; Mahajan, Hitendra S; Tekade, Avinash R; Gattani, Surendra G

    2009-12-01

    The purpose of present research work was to develop mucoadhesive microspheres for nasal delivery with the aim to avoid hepatic first-pass metabolism, improve therapeutic efficacy and enhance residence time. For the treatment of migraine, hydroxypropyl methylcellulose (HPMC) K4M and K15M based microspheres containing sumatriptan succinate (SS) were prepared by spray-drying technique. The microspheres were evaluated with respect to the yield, particle size, incorporation efficiency, swelling property, in vitro mucoadhesion, in vitro drug release, histological study and stability. Microspheres were characterized by differential scanning calorimetry, scanning electron microscopy and X-ray diffraction study. It was found that the particle size, swelling ability and incorporation efficiency of microspheres increases with increasing drug-to-polymer ratio. HPMC-based microspheres show adequate mucoadhesion and do not have any destructive effect on nasal mucosa. On the basis of these results, SS microspheres based on HPMC may be considered as a promising nasal delivery system. PMID:19888880

  9. The succinate receptor as a novel therapeutic target for oxidative and metabolic stress-related conditions.

    Directory of Open Access Journals (Sweden)

    Ana Carolina eAriza

    2012-02-01

    Full Text Available The succinate receptor (also known as GPR91 is a G protein-coupled receptor that is closely related to the family of P2Y purinoreceptors. It is expressed in a variety of tissues, including blood cells, adipose tissue, the liver, retina and kidney. In these tissues, this receptor and its ligand succinate have recently emerged as novel mediators in local stress situations, including ischemia, hypoxia, toxicity and hyperglycemia. Amongst others, the succinate receptor is involved in recruitment of immune cells to transplanted tissues. Moreover, it was shown to play a key role in the development of diabetic retinopathy. However, most prominently, the role of locally increased succinate levels and succinate receptor activation in the kidney, stimulating the systemic and local renin-angiotensin system, starts to unfold: The succinate receptor is a key mediator in the development of hypertension and possibly fibrosis in diabetes mellitus and metabolic syndrome. This makes the succinate receptor a promising drug target to counteract or prevent cardiovascular and fibrotic defects in these expanding disorders. Recent development of SUCNR1-specific antagonists opens novel possibilities for research in models for these disorders and may eventually provide novel opportunities for the treatment of patients.

  10. A method for determining thermophysical properties of organic material in aqueous solutions: Succinic acid

    Science.gov (United States)

    Riipinen, I.; Svenningsson, B.; Bilde, M.; Gaman, A.; Lehtinen, K. E. J.; Kulmala, M.

    2006-12-01

    A method for determining evaporation rates and thermodynamic properties of aqueous solution droplets is introduced. The method combines evaporation rate measurements using modified TDMA technique with data evaluation using an accurate evaporation model. The first set of data has been collected and evaluated for succinic acid aqueous solution droplets. Evaporation rates of succinic acid solution droplets have been measured using a TDMA system at controlled relative humidity (65%) and temperature (298 K). A temperature-dependent expression for the saturation vapour pressure of pure liquid phase succinic acid at atmospheric temperatures has been derived by analysing the evaporation rate data with a numerical model. The obtained saturation vapour pressure of liquid phase succinic acid is ln( p) = 118.41 - 16204.8/ T - 12.452ln( T). The vapour pressure is in unit of Pascal and the temperature in Kelvin. A linear expression for the enthalpy of vaporization for liquid state succinic acid is also presented. According to the results presented in the following, a literature expression for the vapour pressure of liquid phase succinic acid defined for temperatures higher than 461 K [Yaws, C.L., 2003. Yaws' Handbook of Thermodynamic and Physical Properties of Chemical Compounds, Knovel] can be extrapolated to atmospheric temperatures with very good accuracy. The results also suggest that at 298 K the mass accommodation coefficient of succinic acid is unity or very close to unity.

  11. Effects of dissolved CO2 levels on the growth of Mannheimia succiniciproducens and succinic acid production.

    Science.gov (United States)

    Song, Hyohak; Lee, Jeong Wook; Choi, Sol; You, Jong Kyun; Hong, Won Hi; Lee, Sang Yup

    2007-12-15

    A capnophilic rumen bacterium Mannheimia succiniciproducens produces succinic acid as a major fermentation end product under CO(2)-rich anaerobic condition. Since succinic acid is produced by carboxylation of C3 compounds during the fermentation, intracellular CO(2) availability is important for efficient succinic acid formation. Here, we investigated the metabolic responses of M. succiniciproducens to the different dissolved CO(2) concentrations (0-260 mM). Cell growth was severely suppressed when the dissolved CO(2) concentration was below 8.74 mM. On the other hand, cell growth and succinic acid production increased proportionally as the dissolved CO(2) concentration increased from 8.74 to 141 mM. The yields of biomass and succinic acid on glucose obtained at the dissolved CO(2) concentration of 141 mM were 1.49 and 1.52 times higher, respectively, than those obtained at the dissolved CO(2) concentration of 8.74 mM. It was also found that the additional CO(2) source provided in the form of NaHCO(3), MgCO(3), or CaCO(3) had positive effects on cell growth and succinic acid production. However, growth inhibition was observed when excessive bicarbonate salts were added. By the comparison of the activities of key enzymes, it was found that PEP carboxylation by PEP carboxykinase (PckA) is the most important for succinic acid production as well as the growth of M. succiniciproducens by providing additional ATP. PMID:17570706

  12. ATP-Based Ratio Regulation of Glucose and Xylose Improved Succinate Production

    Science.gov (United States)

    Zhang, Fengyu; Li, Jiaojiao; Liu, Huaiwei; Liang, Quanfeng; Qi, Qingsheng

    2016-01-01

    We previously engineered E. coli YL104H to efficiently produce succinate from glucose. Furthermore, the present study proved that YL104H could also co-utilize xylose and glucose for succinate production. However, anaerobic succinate accumulation using xylose as the sole carbon source failed, probably because of an insufficient supply of energy. By analyzing the ATP generation under anaerobic conditions in the presence of glucose or xylose, we indicated that succinate production was affected by the intracellular ATP level, which can be simply regulated by the substrate ratio of xylose to glucose. This finding was confirmed by succinate production using an artificial mixture containing different xylose to glucose ratios. Using xylose mother liquor, a waste containing both glucose and xylose derived from xylitol production, a final succinate titer of 61.66 g/L with an overall productivity of 0.95 g/L/h was achieved, indicating that the regulation of the intracellular ATP level may be a useful and efficient strategy for succinate production and can be extended to other anaerobic processes. PMID:27315279

  13. ATP-Based Ratio Regulation of Glucose and Xylose Improved Succinate Production.

    Science.gov (United States)

    Zhang, Fengyu; Li, Jiaojiao; Liu, Huaiwei; Liang, Quanfeng; Qi, Qingsheng

    2016-01-01

    We previously engineered E. coli YL104H to efficiently produce succinate from glucose. Furthermore, the present study proved that YL104H could also co-utilize xylose and glucose for succinate production. However, anaerobic succinate accumulation using xylose as the sole carbon source failed, probably because of an insufficient supply of energy. By analyzing the ATP generation under anaerobic conditions in the presence of glucose or xylose, we indicated that succinate production was affected by the intracellular ATP level, which can be simply regulated by the substrate ratio of xylose to glucose. This finding was confirmed by succinate production using an artificial mixture containing different xylose to glucose ratios. Using xylose mother liquor, a waste containing both glucose and xylose derived from xylitol production, a final succinate titer of 61.66 g/L with an overall productivity of 0.95 g/L/h was achieved, indicating that the regulation of the intracellular ATP level may be a useful and efficient strategy for succinate production and can be extended to other anaerobic processes. PMID:27315279

  14. STUDYING PSYCHOIMMUNOMODULATING EFFECT OF SUCCINATE PHENOTROPIL IN EXPERIMENTAL MODEL

    Directory of Open Access Journals (Sweden)

    M. A. Samotrueva

    2014-07-01

    Full Text Available Аbstract.  Psychoimmunomodulating  properties  of  phenotropil  succinate,  a  new  phenotropil  derivative,  were  studied in  a model of cyclophosphamide-induced    immunodepression and  lypopolysaccharideinduced  immune  stress,  following  intraperitoneal  injections  of  the  drug  at  different  schedules  (from  a  single  injection  up  to  a  7-day  course,  and  at  varying  doses  (25  mg/kg,  50  mg/kg,  and  100  mg/kg.  It  was  found  that the  studied  substance  shows  a  clear  ability  to  eliminate  disorders  of  various  immune  compartments.  Moreover,  phenotropil  succinate  was  able  to  restore  behavioral  reactions  in  “Suоk-test”.  These  results  provide  evidence for  development  of  this  substance  aimed  for  correction  of  neuroimmune  disturbances.  (Med.  Immunol.,  2011,  vol.  13,  N  1,  pp  55-60

  15. Interaction of Palmitic Acid with Metoprolol Succinate at the Binding Sites of Bovine Serum Albumin

    Directory of Open Access Journals (Sweden)

    Mashiur Rahman

    2014-12-01

    Full Text Available Purpose: The aim of this study was to characterize the binding profile as well as to notify the interaction of palmitic acid with metoprolol succinate at its binding site on albumin. Methods: The binding of metoprolol succinate to bovine serum albumin (BSA was studied by equilibrium dialysis method (ED at 27°C and pH 7.4, in order to have an insight in the binding chemistry of the drug to BSA in presence and absence of palmitic acid. The study was carried out using ranitidine as site-1 and diazepam as site-2 specific probe. Results: Different analysis of binding of metoprolol succinate to bovine serum albumin suggested two sets of association constants: high affinity association constant (k1 = 11.0 x 105 M-1 with low capacity (n1 = 2 and low affinity association (k2 = 4.0×105 M-1 constant with high capacity (n2 = 8 at pH 7.4 and 27°C. During concurrent administration of palmitic acid and metoprolol succinate in presence or absence of ranitidine or diazepam, it was found that palmitic acid displaced metoprolol succinate from its binding site on BSA resulting reduced binding of metoprolol succinate to BSA. The increment in free fraction of metoprolol succinate was from 26.27% to 55.08% upon the addition of increased concentration of palmitic acid at a concentration of 0×10-5 M to 16×10-5 M. In presence of ranitidine and diazepam, palmitic acid further increases the free fraction of metoprolol succinate from 33.05% to 66.95% and 40.68% to 72.88%, respectively. Conclusion: This data provided the evidence of interaction at higher concentration of palmitic acid at the binding sites on BSA, which might change the pharmacokinetic properties of metoprolol succinate.

  16. Non-isothermal crystallization kinetics and characterization of biodegradable poly(butylene succinate-co-neopentyl glycol succinate) copolyesters

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Wen-Jie; Zhou, Xiao-Ming, E-mail: xiaomingzhou@tust.edu.cn

    2015-01-01

    Both biodegradable aliphatic neat poly(butylene succinate) (PBS) and poly(butylene succinate-co-neopentyl glycol succinate) (P(BS-co-NPGS)) copolyesters with different 1,4-butanediol/neopentyl glycol ratios were synthesized through a two-step process of transesterification and polycondensation using stannous chloride and 4-Methylbenzenesulfonic acid as the co-catalysts. The structure, non-isothermal crystallization behavior, crystalline morphology and crystal structure of neat PBS and P(BS-co-NPGS) copolyesters were characterized by {sup 1}H NMR, differential scanning calorimetry (DSC), polarized optical microscope (POM) and wide angle X-ray diffraction (WAXD), respectively. The Avrami equation modified by Jeziorny and Mo's method was employed to describe the non-isothermal crystallization kinetics of the neat PBS and its copolyesters. The modified Avrami equation could adequately describe the primary stage of non-isothermal crystallization kinetics of the neat PBS and its copolyesters. Mo's method provided a fairly satisfactory description of the non-isothermal crystallization of neat PBS and its copolyesters. Interestingly, the values of 1/t{sub 1/2}, Z{sub c} and F(T) obtained by the modified Avrami equation and Mo's method analysis indicated that the crystallization rate increased first and then decreased with an increase of NPGS content compared that of neat PBS, whereas the crystallization mechanism almost kept unchanged. The results of tensile testing showed that the ductility of PBS was largely improved by incorporating NPGS units. The elongation at break increased remarkably with increasing NPGS content. In particular, the sample with 20% NPGS content showed around 548% elongation at break. - Highlights: • The incorporation of NPGS units reduced the spherulite size of BS unit. • The existence of NPGS units did not change the crystal structure of BS unit. • The NPGS units incorporated in PBS could significantly improve the ductility of

  17. Succinic acid production from xylose mother liquor by recombinant Escherichia coli strain

    OpenAIRE

    Wang, Honghui; Pan, Jiachuan; Wang, Jing; Wang, Nan; Jie ZHANG; Li, Qiang; Wang, Dan; Zhou, Xiaohua

    2014-01-01

    Succinic acid (1,4-butanedioic acid) is identified as one of important building-block chemicals. Xylose mother liquor is an abundant industrial residue in xylitol biorefining industry. In this study, xylose mother liquor was utilized to produce succinic acid by recombinant Escherichia coli strain SD121, and the response surface methodology was used to optimize the fermentation media. The optimal conditions of succinic acid fermentation were as follows: 82.62 g L−1 total initial sugars, 42.27 ...

  18. Synthesis, characterization and comparative evaluation of phenoxy ring containing long chain gemini imidazolium and pyridinium amphiphiles.

    Science.gov (United States)

    Bhadani, Avinash; Kataria, Hardeep; Singh, Sukhprit

    2011-09-01

    Two series of phenoxy ring containing long chain imidazolium and pyridinium based gemini amphiphiles have been synthesized from renewable cardanol oil having different spacers (i. e. -S-(CH(2))(n)-S-, where n is 2, 3, 4 & 6). Critical micelle concentration (cmc) of these new gemini amphiphiles has been determined by conductivity method. Further, these new cationic amphiphiles have been evaluated for their DNA binding capability by agarose gel electrophoresis, ethidium bromide exclusion experiments and transmission electron microscopy (TEM). The cytotoxicity of these new amphiphiles have been evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Comparative studies of these phenoxy ring containing long chain gemini imidazolium amphiphiles and their pyridinium analogues depicted low cmc values of the later but greater DNA interaction capability and low cytotoxicity of the former series of amphiphiles. PMID:21676409

  19. Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles

    Science.gov (United States)

    Qiu, Huibin; Hudson, Zachary M.; Winnik, Mitchell A.; Manners, Ian

    2015-03-01

    Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but on a longer length scale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side by side or end to end in nonsolvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and one-dimensional (1D) or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicrometer-length scale, features that are generally only found in natural materials.

  20. Stealth Amphiphiles: Self-Assembly of Polyhedral Boron Clusters.

    Science.gov (United States)

    Ďorďovič, Vladimír; Tošner, Zdeněk; Uchman, Mariusz; Zhigunov, Alexander; Reza, Mehedi; Ruokolainen, Janne; Pramanik, Goutam; Cígler, Petr; Kalíková, Květa; Gradzielski, Michael; Matějíček, Pavel

    2016-07-01

    This is the first experimental evidence that both self-assembly and surface activity are common features of all water-soluble boron cluster compounds. The solution behavior of anionic polyhedral boranes (sodium decaborate, sodium dodecaborate, and sodium mercaptododecaborate), carboranes (potassium 1-carba-dodecaborate), and metallacarboranes {sodium [cobalt bis(1,2-dicarbollide)]} was extensively studied, and it is evident that all the anionic boron clusters form multimolecular aggregates in water. However, the mechanism of aggregation is dependent on size and polarity. The series of studied clusters spans from a small hydrophilic decaborate-resembling hydrotrope to a bulky hydrophobic cobalt bis(dicarbollide) behaving like a classical surfactant. Despite their pristine structure resembling Platonic solids, the nature of anionic boron cluster compounds is inherently amphiphilic-they are stealth amphiphiles. PMID:27287067

  1. Molecular dynamics simulation of micellar shape transition in amphiphilic solutions

    International Nuclear Information System (INIS)

    The micellar shape transition in amphiphilic solutions is studied by coarse-grained molecular dynamics simulations of rigid amphiphilic molecules with explicit solvent molecules. Our simulations show that the dominant micellar shape changes from disc to cylinder, and then to sphere as the hydrophilic interaction increases. We find that, as the hydrophilic interaction increases, the potential energy decreases monotonically even during the micellar shape transition, whereas the slope of the potential energy decreases in a stepwise manner in relation to the micellar shape transition. We also ascertained that there exists a wide coexistence region in the intensity of the hydrophilic interaction between a cylinder and a sphere, whereas the coexistence region between a cylinder and a disc is very narrow. (author)

  2. Prebiotic Lipidic Amphiphiles and Condensing Agents on the Early Earth.

    Science.gov (United States)

    Fiore, Michele; Strazewski, Peter

    2016-01-01

    It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of vesicles that, in principle, could have compartmented first biological processes on early Earth, including the emergence of self-replicating systems. For a competitive selection of the best performing molecular replicators to become operative, some kind of bounded units capable of harboring them are indispensable. Without the competition between dynamic populations of different compartments, life itself could not be distinguished from an otherwise disparate array or network of molecular interactions. In this review, we describe experiments that demonstrate how different prebiotically-available building blocks can become precursors of phospholipids that form vesicles. We discuss the experimental conditions that resemble plausibly those of the early Earth (or elsewhere) and consider the analytical methods that were used to characterize synthetic products. Two brief sections focus on phosphorylating agents, catalysts and coupling agents with particular attention given to their geochemical context. In Section 5, we describe how condensing agents such as cyanamide and urea can promote the abiotic synthesis of phospholipids. We conclude the review by reflecting on future studies of phospholipid compartments, particularly, on evolvable chemical systems that include giant vesicles composed of different lipidic amphiphiles. PMID:27043635

  3. Prebiotic Lipidic Amphiphiles and Condensing Agents on the Early Earth

    Directory of Open Access Journals (Sweden)

    Michele Fiore

    2016-03-01

    Full Text Available It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of vesicles that, in principle, could have compartmented first biological processes on early Earth, including the emergence of self-replicating systems. For a competitive selection of the best performing molecular replicators to become operative, some kind of bounded units capable of harboring them are indispensable. Without the competition between dynamic populations of different compartments, life itself could not be distinguished from an otherwise disparate array or network of molecular interactions. In this review, we describe experiments that demonstrate how different prebiotically-available building blocks can become precursors of phospholipids that form vesicles. We discuss the experimental conditions that resemble plausibly those of the early Earth (or elsewhere and consider the analytical methods that were used to characterize synthetic products. Two brief sections focus on phosphorylating agents, catalysts and coupling agents with particular attention given to their geochemical context. In Section 5, we describe how condensing agents such as cyanamide and urea can promote the abiotic synthesis of phospholipids. We conclude the review by reflecting on future studies of phospholipid compartments, particularly, on evolvable chemical systems that include giant vesicles composed of different lipidic amphiphiles.

  4. A defect mediated lamellar to isotropic transition of amphiphile bilayers

    OpenAIRE

    Pal, Antara; Pabst, Georg; Raghunathan, V. A.

    2011-01-01

    We report the observation of a novel isotropic phase of amphiphile bilayers in a mixed system consisting of the ionic surfactant, sodium docecylsulphate (SDS), and the organic salt p-toludine hydrochloride (PTHC). This system forms a collapsed lamellar ($L_\\alpha$) phase over a wide range of water content, which transforms into an isotropic phase on heating. This transition is not observed in samples without excess water, where the $L_\\alpha$ phase is stable at higher temperatures. Our observ...

  5. Hydration of an amphiphilic excipient, Gelucire 44/14

    OpenAIRE

    Svensson, Anna; Neves, Carole; Cabane, Bernard

    2004-01-01

    The hydration behavior of an amphiphilic excipient, Gelucire 44/14, has been investigated. Two types of hydration processes were studied: one with increasing humidity to investigate the conditions during storage, and one with increasing water contents to study the behavior during dissolution. In addition, the main components of the excipient were investigated separately. These were polyethylene glycol (PEG), PEG monolaurate and PEG dilaurate (PEG esters), trilaurin (glyceride) and glycerol. T...

  6. The lamellar-to-isotropic transition in ternary amphiphilic systems

    OpenAIRE

    Schwarz, U. S.; Swamy, K.; Gompper, G.

    1996-01-01

    We study the dependence of the phase behavior of ternary amphiphilic systems on composition and temperature. Our analysis is based on a curvature elastic model of the surfactant film with sufficiently large spontaneous curvature and sufficiently negative saddle-splay modulus that the stable phases are the lamellar phase and a droplet microemulsion. In addition to the curvature energy, we consider the contributions to the free energy of the long-ranged van der Waals interaction and of the undu...

  7. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    OpenAIRE

    Shrestha, Sanjib K.; Cheng-Wei T Chang; Meissner, Nicole; Oblad, John; Shrestha, Jaya P.; Sorensen, Kevin N.; Michelle M. Grilley; Jon Y Takemoto

    2014-01-01

    K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20′s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were de...

  8. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    OpenAIRE

    Shrestha, Sanjib K.; Cheng-Wei Tom Chang; Nicole eMeissner; John eOblad; Shrestha, Jaya P.; Sorensen, Kevin N.; Michelle M. Grilley; Jon Y Takemoto

    2014-01-01

    K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20’s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were d...

  9. Relation between structure and organisation properties of new amphiphilic cyclodextrins

    International Nuclear Information System (INIS)

    Since a number of years, special attention and efforts have been made to prepare amphiphilic cyclodextrins (CDs) with the objective to use them to obtain supramolecular assemblies as such or in the presence of preformed lipidic structures. The aim of these investigation is in both cases to combine the size specificity of cyclodextrins for guests and the transport properties of phospho-lipidic structures. The final objects could be of importance to transport or target biologically relevant molecules such as drugs using new galenic formulations. In a first step, a new family of amphiphilic CDs was prepared from a pure phospholipids (DMPE) onto cyclodextrins or methylated derivatives through a spacing arm. The afforded compounds (phospholipidyl-cyclodextrins) were fully characterized by high field NMR and high resolution mass spectrometry. The methylated derivatives were shown to self-organize in water with low CMC to form fluctuating micellar fibers retaining the inclusion capacity of the cyclodextrin cavities. The interactions of these compounds with membrane systems were investigated as black films using X-ray reflectivity and by evaluation of their detergent power towards model DMPC liposomes. Their ability to cross over the Blood Brain Barrier was evidenced by a new approach making use of novel immuno-enzymatic assays. In a second step, a new class of amphiphilic cyclodextrins was considered (peptidolipidyl-cyclodextrins). Although they are structurally similar to phospholipidyl-CDs, their preparation overcomes the tedious steps of the later and lead to a considerable versatility in terms of the number of possible molecules to be prepared. Moreover, the stability problems encountered with phospholipids are avoided. Several examples have been prepared, fully characterized and their organization properties investigated by the determination of CMC and by deuterium NMR on a pure and homogeneous mixed peptidolipidyl-CD / DMPC lamellar phase. This novel class of

  10. From Vesicles to Protocells: The Roles of Amphiphilic Molecules

    OpenAIRE

    Yuka Sakuma; Masayuki Imai

    2015-01-01

    It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhes...

  11. Purely peptidic amphiphiles : understanding and controlling their self-assembled structures

    OpenAIRE

    Schuster, Thomas Bernhard

    2011-01-01

    Amphiphilic molecules spontaneously self-assemble into a variety of structures in solution. The term amphiphilic indicates that one part of the molecule is attracted to the solvent, while the other is not. Interactions such as between solute-solvent and solute-solute thus determine the organization. Understanding the self-assembly means understanding those interactions and their driving forces. In the first chapter an overview of the self-organization of amphiphilic molecules into supermolecu...

  12. Supramolecular Packing Controls H₂ Photocatalysis in Chromophore Amphiphile Hydrogels.

    Science.gov (United States)

    Weingarten, Adam S; Kazantsev, Roman V; Palmer, Liam C; Fairfield, Daniel J; Koltonow, Andrew R; Stupp, Samuel I

    2015-12-01

    Light harvesting supramolecular assemblies are potentially useful structures as components of solar-to-fuel conversion materials. The development of these functional constructs requires an understanding of optimal packing modes for chromophores. We investigated here assembly in water and the photocatalytic function of perylene monoimide chromophore amphiphiles with different alkyl linker lengths separating their hydrophobic core and the hydrophilic carboxylate headgroup. We found that these chromophore amphiphiles (CAs) self-assemble into charged nanostructures of increasing aspect ratio as the linker length is increased. The addition of salt to screen the charged nanostructures induced the formation of hydrogels and led to internal crystallization within some of the nanostructures. For linker lengths up to seven methylenes, the CAs were found to pack into 2D crystalline unit cells within ribbon-shaped nanostructures, whereas the nine methylene CAs assembled into long nanofibers without crystalline molecular packing. At the same time, the different molecular packing arrangements after charge screening led to different absorbance spectra, despite the identical electronic properties of all PMI amphiphiles. While the crystalline CAs formed electronically coupled H-aggregates, only CAs with intermediate linker lengths showed evidence of high intermolecular orbital overlap. Photocatalytic hydrogen production using a nickel-based catalyst was observed in all hydrogels, with the highest turnovers observed for CA gels having intermediate linker lengths. We conclude that the improved photocatalytic performance of the hydrogels formed by supramolecular assemblies of the intermediate linker CA molecules likely arises from improved exciton splitting efficiencies due to their higher orbital overlap. PMID:26593389

  13. Separation and Concentration of Succinic Adic from Multicomponent Aqueous Solutions by Nanofiltration Technique

    Directory of Open Access Journals (Sweden)

    Antczak Jerzy

    2014-06-01

    Full Text Available This paper applies the determined suitability of nanofiltration (NF membrane separation for selective isolation and concentration of succinic acid from aqueous solutions which are post-fermentation multicomponent fluids. The study analyzed the influence of concentration and the pH of the separated solutions on the efficiency and selectivity of NF process that runs in a module equipped with a ceramic membrane. Moreover, the effect of applied trans-membrane pressure on the retention of succinic acid and sodium succinate has been studied. The investigations have shown that in the used NF module the retention of succinic acid salt is equal almost 50% in the case of a three-component model solution, although the degree of retention depends on both the transmembrane pressure and the initial concentration of separated salt.

  14. Industrial Systems Biology of Saccharomyces cerevisiae Enables Novel Succinic Acid Cell Factory

    DEFF Research Database (Denmark)

    Otero, José Manuel; Cimini, Donatella; Patil, Kiran Raosaheb;

    2013-01-01

    Saccharomyces cerevisiae is the most well characterized eukaryote, the preferred microbial cell factory for the largest industrial biotechnology product (bioethanol), and a robust commerically compatible scaffold to be exploitted for diverse chemical production. Succinic acid is a highly sought...... production. Glycine and serine, both essential amino acids required for biomass formation, are formed from both glycolytic and TCA cycle intermediates. Succinate formation results from the isocitrate lyase catalyzed conversion of isocitrate, and from the α-keto-glutarate dehydrogenase catalyzed conversion of...... genetic targets for either over-expression or interruption of succinate producing or consuming pathways, respectively, do not lead to increased succinate. Rather, we demonstrate how systems biology tools coupled with directed evolution and selection allows non-intuitive, rapid and substantial re...

  15. Unconventional biomasses as feedstocks for production of biofuels and succinic acid in a biorefinery concept

    DEFF Research Database (Denmark)

    Gunnarsson, Ingólfur Bragi

    utilization of this feedstock could potentially lower the costs for succinic acid production. The biochemical methane potential of L. digitata, post hydrolysis solid residue (PHSR) and fermentation broth after succinic acid fermentation was also determined. In a biorefinery, biogas production is important for...... amounted up to 10.0 g L-1. However, the production of succinic acid from this type of hydrolysate resulted in much higher product titer and substrate utilization compared to ethanol fermentation, partially because A. succinogenes is able to ferment both glucose and xylose into succinic acid. Jerusalem...... energy recovery as well as for minimizing waste and generating an additional product in the form of fertilizer. Energy recovery of PHSR and fermentation broth through anaerobic digestion corresponded to 298 and 285 NmL CH4 g-1 VSadded, respectively. To further increase the integration of the different...

  16. Self-assembly of amphiphilic molecules:A review on the recent computer simulation results

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We provided a short review on the recent progresses in computer simulations of adsorption and self-assembly of amphiphilic molecules.Owing to the extensive applications of amphiphilic molecules,it is very important to understand thoroughly the effects of the detailed chemistry,solid surfaces and the degree of confinement on the aggregate morphologies and kinetics of self-assembly for amphiphilic systems.In this review we paid special attention on(i) morphologies of adsorbed surfactants on solid surfaces,(ii) self-assembly in confined systems,and(iii) kinetic processes involving amphiphilic molecules.

  17. Industrial systems biology of Saccharomyces cerevisiae enables novel succinic acid cell factory.

    Directory of Open Access Journals (Sweden)

    José Manuel Otero

    Full Text Available Saccharomyces cerevisiae is the most well characterized eukaryote, the preferred microbial cell factory for the largest industrial biotechnology product (bioethanol, and a robust commerically compatible scaffold to be exploitted for diverse chemical production. Succinic acid is a highly sought after added-value chemical for which there is no native pre-disposition for production and accmulation in S. cerevisiae. The genome-scale metabolic network reconstruction of S. cerevisiae enabled in silico gene deletion predictions using an evolutionary programming method to couple biomass and succinate production. Glycine and serine, both essential amino acids required for biomass formation, are formed from both glycolytic and TCA cycle intermediates. Succinate formation results from the isocitrate lyase catalyzed conversion of isocitrate, and from the α-keto-glutarate dehydrogenase catalyzed conversion of α-keto-glutarate. Succinate is subsequently depleted by the succinate dehydrogenase complex. The metabolic engineering strategy identified included deletion of the primary succinate consuming reaction, Sdh3p, and interruption of glycolysis derived serine by deletion of 3-phosphoglycerate dehydrogenase, Ser3p/Ser33p. Pursuing these targets, a multi-gene deletion strain was constructed, and directed evolution with selection used to identify a succinate producing mutant. Physiological characterization coupled with integrated data analysis of transcriptome data in the metabolically engineered strain were used to identify 2(nd-round metabolic engineering targets. The resulting strain represents a 30-fold improvement in succinate titer, and a 43-fold improvement in succinate yield on biomass, with only a 2.8-fold decrease in the specific growth rate compared to the reference strain. Intuitive genetic targets for either over-expression or interruption of succinate producing or consuming pathways, respectively, do not lead to increased succinate. Rather, we

  18. Differential labeling of the subunits of respiratory complex III with [3H]succinic anhydride, [14C]succinic anhydride, and p-diazobenzene-[35S]sulfonate

    International Nuclear Information System (INIS)

    Exposure of antimycin-treated Complex III (ubiquinol-cytochrome c reductase) purified from bovine heart mitochondria to [3H]succinic anhydride plus [35S]p-diazobenzenesulfonate (DABS) resulted in somewhat uniform relative labeling of the eight measured subunits of the complex by [3H]succinic anhydride. In contrast, relative labeling by [35S]DABS was similar to [3H]succinic anhydride for the subunits of high molecular mass, i.e., core proteins, cytochromes, and the iron-sulfur protein, but greatly reduced for the polypeptides of molecular mass below 15 kDa. With Complex II depleted in the iron-sulfur protein the relative labeling of core protein I by exposure of the complex to [3H]succinic anhydride was significantly enhanced, whereas labeling of the polypeptides represented by SDS-PAGE bands 7 and 8 was significantly inhibited. Dual labeling of the subunits of Complex III by 14C- and 3H-labeled succinic anhydride before and after dissociation of the complex by sodium dodecyl sulfate, respectively, was measured with the complex in its oxidized, reduced, and antimycin-inhibited states. Subunits observed to be most accessible or reactive to succinic anhydride were core protein II, the iron-sulfur protein, and polypeptides of SDS-PAGE bands 7,8, and 9. Two additional polypeptides of molecular masses 23 and 12kDa, not normally resolved by gel-electrophoresis, were detected. Reduction of the complex resulted in a significant change of 14C/3H labeling ratio of core protein only, whereas treatment of the complex with antimycin resulted in decreases in 14C/3H labeling ratios of core proteins I and II, cytochrome c1, and a polypeptide of molecular mass 13kDa identified as an antimycin-binding protein

  19. Effect of Growth Phase Feeding Strategies on Succinate Production by Metabolically Engineered Escherichia coli▿

    OpenAIRE

    Jiang, Min; Liu, Shu-wen; Ma, Jiang-feng; Chen, Ke-quan; Yu, Li; Yue, Fang-fang; Xu, Bing; WEI, PING

    2009-01-01

    Aerobic growth conditions significantly influenced anaerobic succinate production in two-stage fermentation by Escherichia coli AFP111 with knockouts in rpoS, pflAB, ldhA, and ptsG genes. At a low cell growth rate limited by glucose, enzymes involved in the reductive arm of the tricarboxylic acid cycle and the glyoxylate shunt showed elevated activities, providing AFP111 with intracellular redox balance and increased succinic acid yield and productivity.

  20. Absorbance correction method for estimation of telmisartan and metoprolol succinate in combined tablet dosage forms

    OpenAIRE

    Patel, Komal; Patel, Amit; Dave, Jayant; Patel, Chaganbhai

    2012-01-01

    Aim and Background: The present manuscript describes simple, sensitive, rapid, accurate, precise and economical spectrophotometric method for the simultaneous determination of telmisartan and metoprolol succinate in combined tablet dosage form. Materials and Methods: The method is based on the absorbance correction equations for analysis of both the drugs using methanol as solvent. Telmisartan has absorbance maxima at 296 nm and metoprolol succinate has absorbance maxima at 223 nm in methanol...

  1. FORMULATION AND EVALUATION OF METOPROLOL SUCCINATE CONTROLLED RELEASE TABLETS USING NATURAL AND SYNTHETIC POLYMER

    OpenAIRE

    A. Sathyaraj

    2012-01-01

    The objective of the present study to develop controlled release tablets of Metoprolol succinate using Natural polymer, guar gum and synthetic polymer, carbopol as a rate controlling polymers.. It was also desired to study the effect of polymer concentration. Metoprolol succinate, β1- selective adrenergic receptor- blocking agent used in the management of hypertension, angina pectoris, cardiac arrthymias, myocardial infarction, heart failure, hyperthyroidism and in the prophylactic treatment ...

  2. Succinic acid in aqueous solution : connecting microscopic surface composition and macroscopic surface tension

    OpenAIRE

    Werner, Josephina; Julin, Jan; Dalirian, Maryam; Prisle, Nønne; Öhrwall, Gunnar; Persson, Ingmar; Björneholm, Olle; Riipinen, Ilona

    2014-01-01

    The water vapor interface of aqueous solutions of succinic acid, where pH values and bulk concentrations were varied, has been studied using surface sensitive X-ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulations. It was found that succinic acid has a considerably higher propensity to reside in the aqueous surface region than its deprotonated form, which is effectively depleted from the surface due to the two strongly hydrated carboxylate groups. From both XPS experim...

  3. Carbon dioxide metabolism by Actinomyces viscosus: pathways for succinate and aspartate production.

    OpenAIRE

    Brown, A T; Breeding, L C

    1980-01-01

    14C-labeled bicarbonate was incorporated into trichloroacetic acid-insoluble material by cell suspensions of A. viscosus strain M100 and also into the four-carbon fermentation product, succinate, but not into the three-carbon fermentation product, lactate. The initial step in the conversion of 14C-labeled bicarbonate into both trichloroacetic acid-insoluble material and succinate was catalyzed by the enzyme phosphoenolypyruvate carboxylase, which served to convert the glycolytic intermediate,...

  4. Production of succinic acid from oil palm empty fruit bunch cellulose using Actinobacillus succinogenes

    Science.gov (United States)

    Pasma, Satriani Aga; Daik, Rusli; Maskat, Mohamad Yusof

    2013-11-01

    Succinic acid is a common metabolite in plants, animals and microorganisms. It has been used widely in agricultural, food and pharmaceutical industries. Enzymatic hydrolysate glucose from oil palm empty fruit bunch (OPEFB) cellulose was used as a substrate for succinic acid production using Actinobacillus succinogenes. Using cellulose extraction from OPEFB can enhance the production of glucose as a main substrate for succinic acid production. The highest concentration of glucose produced from enzymatic hydrolysis is 167 mg/mL and the sugar recovery is 0.73 g/g of OPEFB. By optimizing the culture medium for succinic acid fermentation with enzymatic hydrolysate of OPEFB cellulose, the nitrogen sources could be reduced to just only 2.5 g yeast extract and 2.5 g corn step liquor. Batch fermentation was carried out using enzymatic hydrolysate of OPEFB cellulose with yeast extract, corn steep liquor and the salts mixture, 23.5 g/L succinic acid was obtained with consumption of 72 g/L glucose in enzymatic hydrolysate of OPEFB cellulose at 38 hours and 37°C. This study suggests that enzymatic hydrolysate of OPEFB cellulose maybe an alternative substrate for the efficient production of succinic acid by Actinobacillus succinogenes.

  5. Metoprolol succinate extended release/hydrochlorothiazide combination tablets

    Directory of Open Access Journals (Sweden)

    James W Hainer

    2007-07-01

    Full Text Available James W Hainer, Jennifer SuggAstraZeneca LP, Wilmington, DE, USAAbstract: Lowering elevated blood pressure (BP with drug therapy reduces the risk for catastrophic fatal and nonfatal cardiovascular events such as stroke and myocardial infarction. Given the heterogeneity of hypertension as a disease, the marked variability in an individual patient’s BP response, and low response rates with monotherapy, expert groups such as the Joint National Committee (JNC emphasize the value of combination antihypertensive regimens, noting that combinations, usually of different classes, have additive antihypertensive effects. Metoprolol succinate extended-release tablet is a beta-1 (cardio-selective adrenoceptor-blocking agent formulated to provide controlled and predictable release of metoprolol. Hydrochlorothiazide (HCT is a well-established diuretic and antihypertensive agent, which promotes natruresis by acting on the distal renal tubule. The pharmacokinetics, efficacy, and safety/tolerability of the antihypertensive combination tablet, metoprolol extended release hydrochlorothiazide, essentially reflect the well-described independent characteristics of each of the component agents. Not only is the combination product more effective than monotherapy with the individual components but the combination product allows a low-dose multidrug regimen as an alternative to high-dose monotherapy, thereby, minimizing the likelihood of dose-related side-effects.Keywords: antihypertensive, blood pressure, cardiovascular disease, combination product

  6. Ternary solution of sodium chloride, succinic acid and water; surface tension and its influence on cloud droplet activation

    OpenAIRE

    J. Vanhanen; Hyvärinen, A.-P.; Anttila, T.; T. Raatikainen; Viisanen, Y; H. Lihavainen

    2008-01-01

    Surface tension of ternary solution of sodium chloride, succinic acid and water was measured as a function of both composition and temperature by using the capillary rise technique. Both sodium chloride and succinic acid are found in atmospheric aerosols, the former being main constituent of marine aerosol. Succinic acid was found to decrease the surface tension of water already at very low concentrations. Sodium chloride increased the surface tension linearly as a function of the concentrati...

  7. Ternary solution of sodium chloride, succinic acid and water ? surface tension and its influence on cloud droplet activation

    OpenAIRE

    H. Lihavainen; Viisanen, Y; Anttila, T.; A.-P. Hyvärinen; J. Vanhanen

    2008-01-01

    Surface tension of ternary solution of sodium chloride, succinic acid and water was measured as a function of both composition and temperature by using the capillary rise technique. Both sodium chloride and succinic acid are found in atmospheric aerosols, the former being main constituent of marine aerosol. Succinic acid was found to decrease the surface tension of water already at very low concentrations. Sodium chloride increased the surface tension linearly as a function of the concentrati...

  8. Phosphate bioisostere containing amphiphiles: a novel class of squaramide-based lipids.

    Science.gov (United States)

    Saha, Abhishek; Panda, Subhankar; Paul, Saurav; Manna, Debasis

    2016-07-19

    We describe a novel class of amphiphiles with squaramide moiety as a phosphate bioisostere. Most synthesized squaramide-based amphiphiles have the favorable physicochemical properties of lipids, such as: formation of stable liposomes or giant unilamellar vesicles in aqueous solution, high phase-transition temperature, low vesicle leakage and phospholipase resistance properties. PMID:27377058

  9. Synthesis nad properties of amphiphilic block copolymers containing poly 5-vinyltetrazoline or methyl-4-vinylpyridinium iodide

    Czech Academy of Sciences Publication Activity Database

    Gromadzki, D.; Janata, Miroslav; Lokaj, Jan; Štěpánek, Petr

    Arcachon: European Science Foundation Collaborative Research, 2005. P2. [Self-Assembled Structures of Amphiphilic Ionic Copolymers in Solutions and Interfaces. 11.5.2005-14.5.2005, Arcachon] Institutional research plan: CEZ:AV0Z40500505 Keywords : amphiphilic block copolymers Subject RIV: CD - Macromolecular Chemistry

  10. Stable Vesicles Composed of Mono- or Dicarboxylic Fatty Acids and Trimethylammonium Amphiphiles

    DEFF Research Database (Denmark)

    Caschera, Filippo; Bernardino de la Serna, Jorge; Löffler, Philipp M. G.;

    2011-01-01

    vesicles were shown to be more stable than those formed by pure fatty acids. Those containing bola-amphiphile even showed encapsulation of a small hydrophilic solute (8-hydroxypyrene-1,3,6-trisulfonic-acid) suggesting a denser packing of the amphiphiles. Compression and kinetics analysis of monolayers...

  11. Liquid-solid extraction of metallic cations by cationic amphiphiles

    International Nuclear Information System (INIS)

    In the field of selective metal ion separation, liquid-liquid extraction is usually conducted through an emulsion mixing of hydrophobic complexants dispersed in an organic phase and acidic water containing the ionic species. Recently, it has been shown that amphiphilic complexants could influence strongly extraction efficiency by enhancing the interfacial interaction between the metal ion in the aqueous and the complexant in the organic phase. Moreover, these amphiphiles can also substitute the organic phase if an appropriate aliphatic chain is chosen. The dispersion of such amphiphilic complexants in an aqueous solution of salt mixtures is not only attractive for studying specific interactions but also to better the understanding of complex formation in aqueous solution of multivalent metal ions, such as lanthanides and actinides. This understanding is of potential interest for a broad range of industries including purification of rare earth metals and pollute treatment e.g. of fission byproducts. This principle can also be applied to liquid-solid extraction, where the final state of the separation is a solid phase containing the selectively extracted ions. Indeed, a novel solid-liquid extraction method exploits the selective precipitation of metal ions from an aqueous salt mixture using a cationic surfactant, below its Krafft point (temperature below which the long aliphatic chains of surfactant crystallize). This technique has been proven to be highly efficient for the separation of actinides and heavy metal using long chain ammonium or pyridinium amphiphiles. The most important point in this process is the recognition of cationic metal ions by cationic surfactants. By computing the free energy of the polar head group per micelle as a function of the different counter-anions, we have demonstrated for the first time that different interactions exist between the micellar surface and the ions. These interactions depend on the nature of the cation but also on

  12. Electrochemical redox responsive polymeric micelles formed from amphiphilic supramolecular brushes.

    Science.gov (United States)

    Feng, Anchao; Yan, Qiang; Zhang, Huijuan; Peng, Liao; Yuan, Jinying

    2014-05-11

    The end-decorated homopolymer poly(ε-caprolactone)-ferrocene threaded onto a β-cyclodextrin-functionalized main-chain polymer can form a class of amphiphilic noncovalent graft copolymers based on the host-guest interactions of the terminal groups on the side chains. These new supramolecular polymer brushes can further self-assemble into micellar aggregates that exhibit reversible assembly and disassembly behavior under an electrochemical redox trigger, which opens up a new route to building dynamic block copolymer topologies. PMID:24681929

  13. From vesicles to protocells: the roles of amphiphilic molecules.

    Science.gov (United States)

    Sakuma, Yuka; Imai, Masayuki

    2015-01-01

    It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures) and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life. PMID:25738256

  14. Identification of new members within suites of amphiphilic marine siderophores

    OpenAIRE

    Vraspir, Julia M.; Holt, Pamela D.; Butler, Alison

    2010-01-01

    Marine bacterial isolates Vibrio sp. HC0601C5 and Halomonas meridiana str. HC4321C1 were isolated off the coast of southern California and were found to produce an expanded suite of previously identified amphiphilic siderophores. Specifically two new members of the amphibactin family, amphibactins S and T, which have a C14:1 ω-7 fatty acid and a saturated C12 fatty acid, respectively, were produced by Vibrio sp. HC0601C5. These siderophores are produced in addition to a number of previously d...

  15. From Vesicles to Protocells: The Roles of Amphiphilic Molecules

    Directory of Open Access Journals (Sweden)

    Yuka Sakuma

    2015-03-01

    Full Text Available It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life.

  16. Preparation of biodegradable porous poly(butylene succinate microspheres

    Directory of Open Access Journals (Sweden)

    Pepić Dragana

    2008-01-01

    Full Text Available The aim of this study was to determine the optimal conditions for the fabrication of porous microspheres based on poly(butylene succinate, PBS. The biodegradable non-porous PBS microspheres were prepared by the oil-in-water (o/w emulsion solvent evaporation method using poly(vinyl alcohol, PVA, as the surfactant. Fabrication conditions, such as stirring rate, organic/aqueous ratio, PBS concentration and surfactant (PVA concentration, which have an important influence on both the particle size and the morphology of the microspheres, were varied. Scanning electron microscopy, SEM, observations confirmed the size, size distribution and surface morphology of the microspheres. The optimal conditions for the preparation of the non-porous microspheres were found to be: concentration the PBS solution, 10 mass%; PVA concentration, 1 mass%; the organic/ aqueous ratio CHCl3/H2O = 1/20 and stirring rate 800 rpm. Porous PBS microspheres were fabricated under the optimal conditions using various amounts of hexane and poly(ethylene oxide, PEO, as porogens. The influence of the amount of porogen on the pore size and the particle size was investigated using SEM and the apparent density. The microspheres exhibited various porosities and the pore sizes. The average particle size of the microspheres with PEO as the porogen was from 100 to 122μm and that of the microspheres with hexane as the porogen was from 87 to 97μm. The apparent density of the porous microspheres with PEO as the porogen, from 0.16 to 0.23 g/cm3, was much smaller than the non-porous microspheres, 0.40 g/cm3. In the in vitro degradation experiments, the porous microspheres were incubated in phosphate buffer solution (pH 7 at 37°C. After incubating for one month, the microspheres showed significant extent of the hydrolytic degradation of the porous PBS microspheres.

  17. Urinary Bladder Paragangliomas: Analysis of Succinate Dehydrogenase and Outcome.

    Science.gov (United States)

    Gupta, Sounak; Zhang, Jun; Rivera, Michael; Erickson, Lori A

    2016-09-01

    Paragangliomas of the urinary bladder can arise sporadically or as a part of hereditary syndromes including those with underlying mutations in the succinate dehydrogenase (SDH) genes, which serve as tumor suppressors. SDH deficiency can be screened for by absence of immunohistochemical detection of SDHB. In this study of 11 cases, clinical follow-up was available for 9/11 cases. The cases were reviewed and graded based on the grading system for adrenal pheochromocytomas and paragangliomas (GAPP) criteria. Immunohistochemistry was performed for Ki67 and SDHB. Proliferative index was calculated by quantification of Ki67-positive cells at hot spots. The medical record was accessed for documentation of germline SDH mutations. Urinary bladder paragangliomas had a female predilection (8/11 cases), and 5/11 cases exhibited metastatic behavior. Patients with metastatic disease tended to be younger (mean age 43 vs 49 years), have larger lesions (5.8 vs 1.5 cm), and presented with catecholamine excess (4/4 vs 2/6 patients with non-metastatic lesions). Patients with metastatic disease had a higher mean Ki67 proliferation rate (4.9 vs 1.3 %) and GAPP score (mean of 5.8 vs 3.8) (p = 0.01). IHC for SDHB expression revealed loss of expression in 2/6 cases of non-metastatic paragangliomas compared to 4/5 patients with metastatic paragangliomas. Interestingly, of these four patients, two had a documented mutation of SDHB, one patient had a SDHC mutation, and another patient had a history of familial disease without mutation analysis being performed. Our study, suggests that SDH loss was suggestive of metastatic behavior in addition to younger age at diagnosis, larger tumor size, and higher Ki67 proliferation rate and catecholamine type. PMID:27262318

  18. Significance of CO2 donor on the production of succinic acid by Actinobacillus succinogenes ATCC 55618

    Directory of Open Access Journals (Sweden)

    Zou Wei

    2011-10-01

    Full Text Available Abstract Background Succinic acid is a building-block chemical which could be used as the precursor of many industrial products. The dissolved CO2 concentration in the fermentation broth could strongly regulate the metabolic flux of carbon and the activity of phosphoenolpyruvate (PEP carboxykinase, which are the important committed steps for the biosynthesis of succinic acid by Actinobacillus succinogenes. Previous reports showed that succinic acid production could be promoted by regulating the supply of CO2 donor in the fermentation broth. Therefore, the effects of dissolved CO2 concentration and MgCO3 on the fermentation process should be investigated. In this article, we studied the impacts of gaseous CO2 partial pressure, dissolved CO2 concentration, and the addition amount of MgCO3 on succinic acid production by Actinobacillus succinogenes ATCC 55618. We also demonstrated that gaseous CO2 could be removed when MgCO3 was fully supplied. Results An effective CO2 quantitative mathematical model was developed to calculate the dissolved CO2 concentration in the fermentation broth. The highest succinic acid production of 61.92 g/L was obtained at 159.22 mM dissolved CO2 concentration, which was supplied by 40 g/L MgCO3 at the CO2 partial pressure of 101.33 kPa. When MgCO3 was used as the only CO2 donor, a maximal succinic acid production of 56.1 g/L was obtained, which was just decreased by 7.03% compared with that obtained under the supply of gaseous CO2 and MgCO3. Conclusions Besides the high dissolved CO2 concentration, the excessive addition of MgCO3 was beneficial to promote the succinic acid synthesis. This was the first report investigating the replaceable of gaseous CO2 in the fermentation of succinic acid. The results obtained in this study may be useful for reducing the cost of succinic acid fermentation process.

  19. Genotoxicity of meso-2,3-dimercapto succinic acid-coated silver sulfide quantum dot

    Directory of Open Access Journals (Sweden)

    Deniz Özkan Vardar

    2015-06-01

    Full Text Available Nanotecnology products have been used in wide applications in chemistry, electronics, energy generation, and medicine. Despite significant interest in developing quantum dots (QDs for biomedical applications, many researchers are convinced that QDs will never be used for the treatment of patients because of their potential toxicity. In various in vitro cell culture studies, the cytotoxic properties of some QD have been demonstrated and they have been suggested to be toxic in humans. In this study, the cytotoxic properties of Ag2S-(Meso-2,3-Dimercapto Succinic acid nanomaterials in V79 cells (Chinese lung fibroblast cell line were determined by MTT assay. The genotoxic effects of Ag2S-(Meso-2,3-Dimercapto Succinic acid were evaluated by the alkaline single cell gel electrophoresis. The cells were treated with Ag2S-(Meso-2,3-Dimercapto Succinic acid at the concentrations of 5- 2000 µg/ml. No cytotoxic effect of Ag2S-(Meso-2,3-Dimercapto Succinic acid at all concentrations studied was observed. No significant increases in DNA damage were found at the studied concentrations when compared to negative control in V79 cells. In conclusion, further in vitro and in vivo studies are required to determine the safety doses of Ag2S-(Meso-2,3-Dimercapto Succinic acid.

  20. Doxofylline and methylprednisolone sodium succinate are stable and compatible under normal injection conditions.

    Science.gov (United States)

    Xu, Fan; Feng, Enfu; Su, Li; Xu, Guili

    2013-03-01

    To assess the physical compatibility and chemical stability of doxofylline with methylprednisolone sodium succinate in 0.9% sodium chloride or 5% dextrose injection for intravenous infusion. Twenty mL doxofylline solution (0.74 mg/mL) and 1 mL methylprednisolone sodium succinate solution (0.15 mg/mL) were added into 250 mL polyolefin bags containing 5% dextrose injection or 0.9% sodium chloride injection, and stored for 24 h at 20-25(°)C. Chemical compatibility was measured with high-performance liquid chromatography (HPLC), and physical compatibility was determined visually. The results showed that samples were clear and colorless when viewed in normal fluorescent room light. The pH value exhibited little change. The particulate content of > 25 μm was low and within the specification limit. The particulate content of > 10 μm decreased over time and was similar to the control solution. Analysis of chemical stability revealed that doxofylline is stable with methylprednisolone sodium succinate for up to 24 h, and the degradation of methylprednisolone sodium succinate is unrelated to doxofylline, but is closely related to the pH value of the solution. Doxofylline and methylprednisolone sodium succinate did not affect the stability of each other. PMID:23455194

  1. Optimization of succinic acid fermentation with Actinobacillus succinogenes by response surface methodology (RSM)

    Institute of Scientific and Technical Information of China (English)

    Yun-jian ZHANG; Qiang LI; Yu-xiu ZHANG; Dan WANG; Jian-min XING

    2012-01-01

    Succinic acid is considered as an important platform chemical.Succinic acid fermentation with Actinobacillus succinogenes strain BE-1 was optimized by central composite design (CCD) using a response surface methodology (RSM).The optimized production of succinic acid was predicted and the interactive effects between glucose,yeast extract,and magnesium carbonate were investigated.As a result,a model for predicting the concentration of succinic acid production was developed.The accuracy of the model was confirmed by the analysis of variance (ANOVA),and the validity was further proved by verification experiments showing that percentage errors between actual and predicted values varied from 3.02% to 6.38%.In addition,it was observed that the interactive effect between yeast extract and magnesium carbonate was statistically significant.In conclusion,RSM is an effective and useful method for optimizing the medium components and investigating the interactive effects,and can provide valuable information for succinic acid scale-up fermentation using A.succinogenes strain BE-1.

  2. FORMULATION AND EVALUATION OF CONTROLLED POROSITY OSMOTIC DRUG DELIVERY SYSTEM OF METOPROLOL SUCCINATE

    Directory of Open Access Journals (Sweden)

    Hardik Patel* and M. M. Patel

    2012-06-01

    Full Text Available Controlled porosity osmotic tablet of metoprolol succinate prepared and evaluated in this study. Metoprolol succinate is very high soluble drug, so complete drug release obtained very fast. It is difficult to formulate osmotic tablet of Metoprolol succinate which gives drug release up to 24 hr at zero order. To get desired dissolution profile various formulation parameters like osmogen concentration, level of weight gain and level of pore former concentration were studied. Hypromellose was added as release retardant to reduce its dissolution rate and get drug release up to 24 hr at zero order. As concentration of release retardant increases, dissolution rate decreases. Final optimized formulation with hypromellose was studied for effect of pH of dissolution media, agitation intensity and osmotic pressure of dissolution media. There is no effect of above variables on dissolution confirms that prepared metoprolol succinate tablet gives drug release with osmotic mechanism. Final optimized formulation complies with the USP criteria for the dissolution of metoprolol succinate extended release tablet.

  3. Pretreatment of spent sulphite liquor via ultrafiltration and nanofiltration for bio-based succinic acid production.

    Science.gov (United States)

    Pateraki, Chrysanthi; Ladakis, Dimitrios; Stragier, Lutgart; Verstraete, Willy; Kookos, Ioannis; Papanikolaou, Seraphim; Koutinas, Apostolis

    2016-09-10

    Ultrafiltration and nanofiltration of spent sulphite liquor (SSL) has been employed to evaluate the simultaneous production of lignosulphonates and bio-based succinic acid using the bacterial strains Actinobacillus succinogenes and Basfia succiniciproducens. Ultrafiltration with membranes of 10, 5 and 3kDa molecular weight cut-off results in significant losses of lignosulphonates (26-50%) in the permeate stream, while nanofiltration using membrane with 500Da molecular weight cut-off results in high retention yields of lignosulphonates (95.6%) in the retentate stream. Fed-batch bioreactor cultures using permeates from ultrafiltrated SSL resulted in similar succinic acid concentration (27.5g/L) and productivity (0.4g/L/h) by both strains. When permeates from nanofiltrated SSL were used, the strain B. succiniciproducens showed the highest succinic acid concentration (33.8g/L), yield (0.58g per g of consumed sugars) and productivity (0.48g/L/h). The nanofiltration of 1t of thick spent sulphite liquor could lead to the production of 306.3kg of lignosulphonates and 52.7kg of succinic acid, whereas the ultrafiltration of 1t of thick spent sulphite liquor using a 3kDa membrane could result in the production of 237kg of lignosulphonates and 71.8kg of succinic acid when B. succiniproducens is used in both cases. PMID:27374402

  4. Succinate-dependent energy generation and pyruvate dehydrogenase complex activity in isolated Ascaris suum mitochondria

    International Nuclear Information System (INIS)

    Body wall muscle from the parasitic nematode, Ascaris suum, contain unique anaerobic mitochondria that preferentially utilize fumarate and branched-chain enoyl CoA's as terminal electron acceptors instead of oxygen. While electron transport in these organelles is well characterized, the role of oxygen in succinate-dependent phosphorylation is still not clearly defined. Therefore, the present study was designed to more fully characterize succinate metabolism in these organelles as well as the in vitro regulation of a key mitochondrial enzyme, the pyruvate dehydrogenase complex (PDC). In the absence of added adenine nucleotides, incubations in succinate resulted in substantial elevations in intramitochrondrial ATP levels, but ATP/ADP ratios were considerably higher in incubations with malate. The stimulation of phosphorylation in aerobic incubations with succinate was rotenone sensitive and appears to be Site I dependent. Increase substrate level phosphorylation, coupled to propionate formation, or additional sites of electron-transport associated ATP synthesis were not significant. Under aerobic conditions, 14CO2 evolution from 1,4-[14C]succinate was stimulated and NADH/NAD+ ratios were elevated, but the formation of 14C propionate was unchanged

  5. Succinate-dependent energy generation and pyruvate dehydrogenase complex activity in isolated Ascaris suum mitochondria

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, T.A.

    1988-01-01

    Body wall muscle from the parasitic nematode, Ascaris suum, contain unique anaerobic mitochondria that preferentially utilize fumarate and branched-chain enoyl CoA's as terminal electron acceptors instead of oxygen. While electron transport in these organelles is well characterized, the role of oxygen in succinate-dependent phosphorylation is still not clearly defined. Therefore, the present study was designed to more fully characterize succinate metabolism in these organelles as well as the in vitro regulation of a key mitochondrial enzyme, the pyruvate dehydrogenase complex (PDC). In the absence of added adenine nucleotides, incubations in succinate resulted in substantial elevations in intramitochrondrial ATP levels, but ATP/ADP ratios were considerably higher in incubations with malate. The stimulation of phosphorylation in aerobic incubations with succinate was rotenone sensitive and appears to be Site I dependent. Increase substrate level phosphorylation, coupled to propionate formation, or additional sites of electron-transport associated ATP synthesis were not significant. Under aerobic conditions, {sup 14}CO{sub 2} evolution from 1,4-({sup 14}C)succinate was stimulated and NADH/NAD{sup +} ratios were elevated, but the formation of {sup 14}C propionate was unchanged.

  6. Development and evaluation of vitamin E D-α-tocopheryl polyethylene glycol 1000 succinate-mixed polymeric phospholipid micelles of berberine as an anticancer nanopharmaceutical

    Directory of Open Access Journals (Sweden)

    Shen R

    2016-04-01

    Full Text Available Roger Shen,1 Jane J Kim,2 Mingyi Yao,2,3 Tamer A Elbayoumi2,3 1Department of Family Medicine, Northeastern Health Systems-Tahlequah City Hospital, Tahlequah, OK, USA; 2Department of Pharmaceutical Sciences, College of Pharmacy-Glendale, Midwestern University, 3Nanomedicine Center of Excellence in Translational Nanomedicine, Midwestern University, Glendale, AZ, USA Abstract: Berberine (Brb is an active alkaloid occurring in various common plant species, with well-recognized potential for cancer therapy. Brb not only augments the efficacy of antineoplastic chemotherapy and radiotherapy but also exhibits direct antimitotic and proapoptotic actions, along with distinct antiangiogenic and antimetastatic activities in a variety of tumors. Despite its low systemic toxicity, several pharmaceutical challenges limit the application of Brb in cancer therapy (ie, extremely low solubility and permeability, very poor pharmacokinetics (PKs, and oral bioavailability. Among lipid-based nanocarriers investigated recently for Brb, stealth amphiphilic micelles of polymeric phospholipid conjugates were studied here as a promising strategy to improve Brb delivery to tumors. Specifically, physicochemically stable micelles made of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol-2000] (PEG-PE mixed with D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS (PEG-succinate ester of vitamin E, in a 3:1 M ratio, increased Brb solubilization by 300%. Our PEG-PE/TPGS-mixed micelles firmly retained the incorporated Brb, displaying extended-release profile in simulated media, with up to 30-fold projected improvement in simulated PKs of Brb. Owing to the markedly better uptake of Brb-containing mixed micelles in vitro, our Brb-mixed micelles nanoformulation significantly amplified apoptosis and overall cytotoxic effectiveness against monolayer and spheroid cultures of human prostate carcinomas (16- to 18-fold lower half-maximal inhibitory

  7. Nanostructured Amphiphilic Star-Hyperbranched Block Copolymers for Drug Delivery.

    Science.gov (United States)

    Seleci, Muharrem; Seleci, Didem Ag; Ciftci, Mustafa; Demirkol, Dilek Odaci; Stahl, Frank; Timur, Suna; Scheper, Thomas; Yagci, Yusuf

    2015-04-21

    A robust drug delivery system based on nanosized amphiphilic star-hyperbranched block copolymer, namely, poly(methyl methacrylate-block-poly(hydroxylethyl methacrylate) (PMMA-b-PHEMA) is described. PMMA-b-PHEMA was prepared by sequential visible light induced self-condensing vinyl polymerization (SCVP) and conventional vinyl polymerization. All of the synthesis and characterization details of the conjugates are reported. To accomplish tumor cell targeting property, initially cell-targeting (arginylglycylaspactic acid; RGD) and penetrating peptides (Cys-TAT) were binding to each other via the well-known EDC/NHS chemistry. Then, the resulting peptide was further incorporated to the surface of the amphiphilic hyperbranched copolymer via a coupling reaction between the thiol (-SH) group of the peptide and the hydroxyl group of copolymer by using N-(p-maleinimidophenyl) isocyanate as a heterolinker. The drug release property and targeting effect of the anticancer drug (doxorobucin; DOX) loaded nanostructures to two different cell lines were evaluated in vitro. U87 and MCF-7 were chosen as integrin αvβ3 receptor positive and negative cells for the comparison of the targeting efficiency, respectively. The data showed that drug-loaded copolymers exhibited enhanced cell inhibition toward U87 cells in compared to MCF-7 cells because targeting increased the cytotoxicity of drug-loaded copolymers against integrin αvβ3 receptor expressing tumor cells. PMID:25816726

  8. Preparation and Properties of Vesicles from Condensable Amphiphilic Amino Acids

    Institute of Scientific and Technical Information of China (English)

    熊向源; 何巍; 李子臣; 李福绵

    2001-01-01

    Three double-chain amphiphiles with amino acid groups as hydrphilic moiety were synthesized. These amphiphiles can be easily dispersed in buffer solution to form transparent dispersion. Examination of the dispersion by transmission electron microscopy (TEM) showed the formation of stable vesicular aggregates, which was also confirmed by the ability to encapsulate water-soluble dyes. Since amino acid groups are located on the surface of the vesicles, water-soluble carbodiimide can induce the condensation of these groups to form peptide. The phase transition temperatures of these vesicles were estimated by differential scanning calorimetry (DSC), and a decrease of phase transition temperature was observed after polycondensation due to the disturbance of the ordered arrangement of the hydrophobic chains. The leakage rate of the vesicles before and after condensation was studied by monitoring the increase of fluorescence intensity of water-soluble dye. These vesicles belong to the least permeable ones and the leakage rate can be controlled by varying the degree of condensation or the temperature.

  9. Lipophosphoramidate-based bipolar amphiphiles: their syntheses and transfection properties.

    Science.gov (United States)

    Berchel, Mathieu; Le Gall, Tony; Lozach, Olivier; Haelters, Jean-Pierre; Montier, Tristan; Jaffrès, Paul-Alain

    2016-03-14

    Six new cationic bolaamphiphiles (also called bipolar amphiphiles, bolaform amphiphiles, or bolalipids) were readily prepared by a thiol-ene click reaction that engaged a mercapto-alcohol (mercapto-ethanol or mercapto-hexanol) and a cationic based lipophosphoramidate. The cationic lipophosphoramidates contain two lipid chains that end in an alkene group and a selected cationic polar head group (trimethylammonium, dimethyl hydroxyethyl ammonium, or methylimidazolium). These compounds were formulated in water (with or without DOPE as a colipid) to produce supramolecular aggregates. These aggregates, before (i.e. bolasomes) and after (i.e. bolaplexes) mixing with plasmid DNA (pDNA) at various charge ratios, were characterized with regard to their sizes and zeta potentials. In the case of bolasomes, the suspensions were unstable since precipitation occurred after only a few hours at room temperature. On the other hand, bolaplex formulations exhibited clearly a better colloidal stability. Then, the gene delivery properties of the cationic bolasomes were investigated using two human-derived epithelial cell lines (A549 and 16HBE). Compared to the commercially available lipofection reagent (Lipofectamine), most of the cationic bolaamphiphiles were able to efficiently transfect these cells when they were formulated with DOPE in a 1 : 1 molar ratio. We report herein that bolaamphiphiles possessing a trimethylammonium or a dimethyl hydroxyethyl ammonium head group were the most efficient in terms of transfection efficiency while exhibiting no significant cytotoxicity. PMID:26864681

  10. Amphiphilic silver particles for conductive inks with controlled wetting behavior

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Bok Yeop, E-mail: byahn@seas.harvard.edu [Wyss Institute for Biologically Inspired Engineering at Harvard University, Cambridge, MA 02138 (United States); Lewis, Jennifer A. [Wyss Institute for Biologically Inspired Engineering at Harvard University, Cambridge, MA 02138 (United States); Harvard School of Engineering and Applied Science, Cambridge, MA 02138 (United States)

    2014-12-15

    Silver inks find applications in printed electronics as conductive electrodes. Amphiphilic silver microparticles are prepared by modifying PAA-capped particles with functional amines via an amidation reaction. These modified silver particles can be dispersed in a wide variety of solvents ranging from water (ε = 80.4) to lipophilic alcohols (ε = 3–17) to yield conductive inks with tunable wettability. Using these inks, we have demonstrated aerosol jet printing of conductive silver patterns (36 μm wide, 1.2 μm thick) on Kapton. Electrical resistivity of 3.7 μΩ cm is obtained after thermal annealing at 225 °C for 5 min. Similar electrical resistivity (3.9 μΩ cm) is achieved after photonic annealing as short as 1 ms at 1.4 KV. - Highlights: • Synthesis of amphiphilic silver particles. • Surface modification of silver particles by amidation. • Dispersion, contact angle, surface tension of silver inks. • Aerosol jet printing of silver inks on polyimide. • Conductivity by thermal and photonical annealing.

  11. Amphiphilic silver particles for conductive inks with controlled wetting behavior

    International Nuclear Information System (INIS)

    Silver inks find applications in printed electronics as conductive electrodes. Amphiphilic silver microparticles are prepared by modifying PAA-capped particles with functional amines via an amidation reaction. These modified silver particles can be dispersed in a wide variety of solvents ranging from water (ε = 80.4) to lipophilic alcohols (ε = 3–17) to yield conductive inks with tunable wettability. Using these inks, we have demonstrated aerosol jet printing of conductive silver patterns (36 μm wide, 1.2 μm thick) on Kapton. Electrical resistivity of 3.7 μΩ cm is obtained after thermal annealing at 225 °C for 5 min. Similar electrical resistivity (3.9 μΩ cm) is achieved after photonic annealing as short as 1 ms at 1.4 KV. - Highlights: • Synthesis of amphiphilic silver particles. • Surface modification of silver particles by amidation. • Dispersion, contact angle, surface tension of silver inks. • Aerosol jet printing of silver inks on polyimide. • Conductivity by thermal and photonical annealing

  12. PREPARATION OF STARCH SUCCINATE WITH INTERMEDIATE DS BY AQUEOUS SLURRY REACTION

    Institute of Scientific and Technical Information of China (English)

    ZHUChangying; WANGBin; 等

    2001-01-01

    The succinylation of cornstarch by slurry reaction has been studied using sodium hydroxide as catalyst.Several reaction parameters affecting the succinylation were investigated including the concentration of starch in water,the ratio of succinic anhydride to starch,the reaction time and the reaction temperature,The favorable conditions for an intermediate degree of substitution(DS) and reasonably high reaction efficiency(RE) are pH 8.5-9.0,50% starch by weight to water.succinic anhydride to starch 1/1(w/w),reaction time 4h,reaction temperature 30℃ .Under these conditions,the DS of 0.45 and RE of 28% were achieved.The addition of an adequate amount of crosslinking agent imparted starch succinate water absorbency.

  13. PREPARATION OF STARCH SUCCINATE WITH INTERMEDIATE DS BY AQUEOUS SLURRY REACTION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The succinylation of cornstarch by slurry reaction has been studied using sodium hydroxide as catalyst. Several reaction parameters afJecting the succinylation were investigated including the concentration of starch in water, the ratio of succinic anhydride to starch, the reaction time and the reaction temperature. The favorable conditions for an intermediate degree of substitution (DS) and reasonably high reaction efficiency (RE) are pH 8.5~9.0, 50% starch by weight to water, succinic anhydride to starch I/I (w/w), reaction time 4h, reaction temperature 30 ℃Under these conditions, the DS of 0.45 and RE of 28% were achieved. The addition of an adequate amount of crosslinking agent imparted starch succinate water absorbency.

  14. Secondary isotope effects in intramolecular catalysis. Mono-p-bromophenyl succinate hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Gandour, R.D.; Stella, V.J.; Coyne, M.; Schowen, R.L.; Icaza, E.A.

    1978-04-28

    Kinetic isotope effects have been measured for the intramolecular nucleophilic carboxylate-catalyzed hydrolysis, k/sub s/, of mono-p-bromophenyl succinate and mono-p-bromophenyl succinate-d/sub 4/. The resulting isotope effect, k/sub s//sup h/sub 4///k/sub s//sup d/sub 4//, equals 1.035, a normal effect. This is contrary to what is expected for acyl transfer reactions where the transition-state structure resembles a tetrahedral intermediate. However, the direction of the isotope effect is in agreement with a transition-state structure resembling succinic anhydride. Combining this result with previous kinetic and structural studies, a detailed transition-state structure for the hydrolysis reaction is proposed. 31 references, 2 tables.

  15. DEVELOPMENT AND VALIDATION OF ANALYTICAL METHOD FOR ESTIMATION OF CILNIDIPINE AND METOPROLOL SUCCINATE

    Directory of Open Access Journals (Sweden)

    Mo.Salauddin A Shaikh

    2015-07-01

    Full Text Available A simple, specific, accurate and precise reversed phase high performance liquid chromatographic method was developed and validated for the simultaneous estimation of Cilnidipine and Metoprolol Succinate, using a Cosmosil C18 (250 х 4.6 mm i.d. column and a mobile phase composed of 0.05M potassium dihydrogen phosphate buffer: Methanol (70:30 pH 3.5 adjusted with ophosphoric acid and at flow rate of 1.0 ml/min. The retention times of Cilnidipine and Metoprolol Succinate were found to be 3.493 min and 5.960 min, respectively. Linearity was established for Cilnidipine and Metoprolol Succinate in the range of 12.5-37.5 μg/ml and 2.5-7.5 μg/ml, respectively. The percentage recoveries of Cilnidipine and Metoprolol Succinate were found to be in the range of 100.13-100.40 % and 99.24-100.29 %, respectively. The correlation coefficients for both components were found to be 0.999. The developed methods were validated according to ICH guidelines and values of linearity, accuracy, precision and other analysis were found to be in good accordance with the prescribed values. This method can be successfully employed for simultaneous quantitative analysis of Cilnidipine and Metoprolol Succinate in its dosage form. The developed HPLC method was subjected to stability indicating studies for marketed formulation. Interfering peak from degraded products or solvent did not interfere with estimation of drugs and the developed method was found to be specific for estimation of Cilnidipine and Metoprolol Succinate.

  16. Electron paramagnetic resonance study of amphiphiles partitioning behavior in desiccation-tolerant moss during dehydration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Desiccation tolerance is a crucial characteristic for desert moss surviving in arid regions. Desiccation procedure always induces amphiphiles transferring from the polar cytoplasm into lipid bodies. The behavior of amphiphiles transferring can contribute to the enhancement of desiccation tolerance and the reduction of plasma membrane integrity simultaneously. The effects of amphiphiles partitioning into the lipid phase during water loss has been studied for pollen and seeds using electron paramagnetic resonance (EPR) spectroscopy. However, desiccation-tolerant high plants occur among mosses, several angiosperms and higher plants seeds or pollens. They have different strategies for survival in dehydration and rehydration. A desiccation-tolerant moss Tortula desertorurn was used to investigate the behaviors of amphiphilic molecules during drying by spin label technology. There are small amount of amphiphilic probes partitioning into membrane during moss leaves dehydration, comparing with that in higher plants. Cytoplasm viscosity changed from 1.14 into glass state only dehydration less than 60 min. Moss leaves lost plasma membrane integrity slightly,from 0.115 to 0.237, occurred simultaneously with amphiphiles partition. The results showed the more advantages of mosses than higher plants in adapting fast dehydration. We propose that EPR spin label is feasible for studying the amphiphiles partitioning mechanisms in membrane protection and damage for desiccation-tolerant mosses.(C) 2007 Yan Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  17. Synthesis of Polymerizable Amphiphiles with Systematic Variation of Critical Packing Parameters

    Institute of Scientific and Technical Information of China (English)

    M. H. Li; W. L. Yang; J. Qian; C. C. Wang; S. K. Fu

    2005-01-01

    @@ 1Introduction An amphiphile is a molecule composed of hydrophilic part and hydrophobic part, which are incompatible and tend to separate from each other. The tendency of separation is often promoted by addition of water and sometimes also oil. Under balanced conditions the mixtures form macroscopically homogeneous phases, including isotropic solution phases and liquid crystalline phases. Correlation of the amphiphile structure with its preferred phases could be understood with a simple geometric model[1], which defines a dimensionless Critical Packing Parameter (CPP) to describe the relative bulkiness of the hydrophobic part and the hydrophilic part in an amphiphile. With CPP increasing from a small value to a high value the amphiphile changes from hydrophilic to hydrophobic, its preferred phase structure from direct structures via lamellar structure to reverse structures. This model provides a basis for the molecular design of amphiphiles. To immobilize the microstructure of the phases formed by amphiphiles is a challenge for current material chemists. Techniques of both inorganic polymerization[2] and organic polymerization[3] have been developed. With organic polymerization the molecular design of polymerizable amphiphiles is critical for the successful immobilization of the vulnerable precursor microstructures.

  18. Synthesis of tocopheryl succinate phospholipid conjugates and monitoring of phospholipase A2 activity

    DEFF Research Database (Denmark)

    Pedersen, Palle Jacob; Viart, Helene Marie-France; Melander, Fredrik;

    2012-01-01

    Tocopheryl succinates (TOSs) are, in contrast to tocopherols, highly cytotoxic against many cancer cells. In this study the enzyme activity of secretory phospholipase A2 towards various succinate-phospholipid conjugates has been investigated. The synthesis of six novel phospholipids is described,...

  19. Regulation of fructose uptake and catabolism by succinate in Azospirillum brasilense.

    OpenAIRE

    Mukherjee, A; S. Ghosh

    1987-01-01

    Fructose uptake and catabolism in Azospirillum brasilense is dependent on three fructose-inducible enzymes (fru-enzymes): (i) enzyme I and (ii) enzyme II of the phosphoenolpyruvate:fructose phosphotransferase system and (iii) 1-phosphofructokinase. In minimal medium containing 3.7 mM succinate and 22 mM fructose as sources of carbon, growth of A. brasilense was diauxic, succinate being utilized in the first phase of growth and fructose in the second phase with a lag period between the two gro...

  20. Interaction of Palmitic Acid with Metoprolol Succinate at the Binding Sites of Bovine Serum Albumin

    OpenAIRE

    Mashiur Rahman; Farzana Prianka; Mohammad Shohel; Md. Abdul Mazid

    2014-01-01

    Purpose: The aim of this study was to characterize the binding profile as well as to notify the interaction of palmitic acid with metoprolol succinate at its binding site on albumin. Methods: The binding of metoprolol succinate to bovine serum albumin (BSA) was studied by equilibrium dialysis method (ED) at 27°C and pH 7.4, in order to have an insight in the binding chemistry of the drug to BSA in presence and absence of palmitic acid. The study was carried out using ranitidine as site-1 a...

  1. Effect of vitamin E succinate on inflammatory cytokines induced by high-intensity interval training

    OpenAIRE

    Hadi Sarir; Ghodsieh Emdadifard; Homayoun Farhangfar; Hossein TaheriChadorneshin

    2015-01-01

    Aim and Scope: The anti-inflammatory effect of vitamin E under moderate exercises has been evaluated. However, the effect of vitamin E succinate, which has more potent anti-inflammatory effect than other isomers of vitamin E has not been evaluated. Therefore, the aim of the present study was to evaluate the effects of vitamin E succinate on tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) production induced by high-intensity interval training (HIIT). Materials and Methods: In the ...

  2. Poly(butylene succinate) and its copolymers: research, development and industrialization.

    Science.gov (United States)

    Xu, Jun; Guo, Bao-Hua

    2010-11-01

    Poly(butylene succinate) (PBS) and its copolymers are a family of biodegradable polymers with excellent biodegradability, thermoplastic processability and balanced mechanical properties. In this article, production of the monomers succinic acid and butanediol, synthesis, processing and properties of PBS and its copolymers are reviewed. The physical properties and biodegradation rate of PBS materials can be varied in a wide range through copolymerization with different types and various contents of monomers. PBS has a wide temperature window for thermoplastic processing, which makes the resin suitable for extrusion, injection molding, thermoforming and film blowing. Finally, we summarized industrialization and applications of PBS. PMID:21058317

  3. Where surface physics and fluid dynamics meet: rupture of an amphiphile layer by fluid flow

    OpenAIRE

    Bandi, Mahesh; Goldburg, Walter; Cressman Jr., John; Kellay, Hamid

    2006-01-01

    We investigate the fluctuating pattern created by a jet of fluid impingent upon an amphiphile-covered surface. This microscopically thin layer is initially covered with 50 $\\mu$m floating particles so that the layer can be visualized. A vertical jet of water located below the surface and directed upward drives a hole in this layer. The hole is particle-free and is surrounded by the particle-laden amphiphile region. The jet ruptures the amphiphile layer creating a particle-free region that is ...

  4. Cucurbit[7]uriI-Based Vesicles Formed by Self-assembly of Supramolecular Amphiphiles

    Institute of Scientific and Technical Information of China (English)

    李佳锡; 周黎鹏; 罗全; 王永国; 张春秋; 卢伟; 徐家云; 刘俊秋

    2012-01-01

    Cucurbituril (CB), a well-known macrocyclic cavitand, has been used extensively to construct supramolecular aggregates. Based on host-guest intertactions, an adamantanyl derivative guest molecule was designed and syn- thesized to prepare a supramolecular amphiphile with cucurbit[7]uril. In aqueous solution, the cucurbit[7]uril based supramolecular amphiphiles self-assemble into well-defined vesicles, and their disassembly can be achieved by addition of excess competitive agent 1-adamantanamine hydrochloride. This vesicle functions as a new nanocapsule to encapsulate molecules within its hollow cavity. Through competitive disassembly of supramolecular amphiphiles, the vesicles behave as a novel drug delivery carrier.

  5. Amphiphile replacement on carbon nanotube surfaces: Effect of aromatic groups on the interaction strength

    Energy Technology Data Exchange (ETDEWEB)

    Bluemmel, Pascal; Setaro, Antonio; Reich, Stephanie [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Popeney, Chris S.; Trappmann, Britta; Haag, Rainer [Institut fuer Chemie und Biochemie, Freie Universitaet Berlin, Takustrasse 3, 14195 Berlin (Germany)

    2011-11-15

    Carbon nanotubes (CNTs) were solubilized using akyl/polyglycerol amphiphiles. Similar cosurfactants, bearing different aromatic moieties between head and tail, were added to these samples. The interaction strength between these amphiphiles and CNTs changes depending on the inserted aromatic moieties. The insertion of a phenyl ring allows the amphiphile to replace the starting one indicating a higher interaction strength, while the insertion of a triazol pentagon does not, suggesting that the interaction strength is lower. The replacement was monitored via PLE mapping. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Large-scale dissipative particle dynamics simulations of self-assembly amphiphilic systems†

    Science.gov (United States)

    Li, Xuejin; Tang, Yu-Hang

    2014-01-01

    We present large-scale simulation results on the self-assembly of amphiphilic systems in bulk solution and under soft confinement. Self-assembled unilamellar and multilamellar vesicles are formed from amphiphilic molecules in bulk solution. The system is simulated by placing amphiphilic molecules inside large unilamellar vesicles (LUVs) and the dynamic soft confinement-induced self-assembled vesicles are investigated. Moreover, the self-assembly of sickle hemoglobin (HbS) is simulated in a crowded and fluctuating intracellular space and our results demonstrate that the HbS self-assemble into polymer fibers causing the LUV shape to be distorted. PMID:24938634

  7. Syntheses, Characterization, Physical and Biological Properties of Long-chain, Water-soluble, Dendritic Amphiphiles

    OpenAIRE

    Williams, André Arvin

    2008-01-01

    In this project, we have designed and synthesized a new series of long-chain, water-soluble, dendritic, anionic amphiphiles [3CAmn, RCONHC(CH2CH2COOH)3, R= CnH2n+1] to alleviate the low aqueous solubility of fatty acids. The dendritic-tricarboxlyato headgroup improves aqueous solubility and allows us to measure the intrinsic biological activity of our amphiphiles without the potential hindrance of low aqueous solubility. The aqueous solubilities of the anionic amphiphiles have been measured...

  8. Surfactant Behavior of Amphiphilic Polymer-Tethered Nanoparticles.

    Science.gov (United States)

    Zhang, Yue; Zhao, Hanying

    2016-04-19

    In recent years, an emerging research area has been the surfactant behavior of polymer-tethered nanoparticles. In this feature article, we have provided a general introduction to the synthesis, self-assembly, and interfacial activity of polymer-tethered inorganic nanoparticles, polymer-tethered organic nanoparticles, and polymer-tethered natural nanoparticles. In addition, applications of the polymer-tethered nanoparticles in colloidal and materials science are briefly reviewed. All research demonstrates that amphiphilic polymer-tethered nanoparticles exhibit surfactant behavior and can be used as elemental building blocks for the fabrication of advanced structures by the self-assembly approach. The polymer-tethered nanoparticles provide new opportunities to engineer materials and biomaterials possessing specific functionality and physical properties. PMID:27018567

  9. Nanocapsules templated on liquid cores stabilized by graft amphiphilic polyelectrolytes

    Science.gov (United States)

    Szafraniec, Joanna; Janik, Małgorzata; Odrobińska, Joanna; Zapotoczny, Szczepan

    2015-03-01

    A surfactant-free method of preparation of nanocapsules templated on liquid cores using amphiphilic graft polyelectrolytes was developed. A model photoactive copolymer, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate) with grafted poly(vinylnaphthalene) chains (PAMPS-graft-PVN) was used to stabilize toluene droplets in an aqueous emulsion. The macromolecules, due to their amphiphilic character and the presence of strong ionic groups, tend to undergo intramolecular aggregation in water but at the water-oil interface less compact conformation is preferred with PVN grafts anchoring in the oil phase and the charged PAMPS main chains residing in the aqueous phase, thus stabilizing the nanoemulsion droplets. Formation of such nanocapsules was confirmed by dynamic light scattering measurements as well as SEM and cryo-TEM imaging. Grafting density and content of the chromophores in the graft copolymers were varied in order to achieve high stability of the coated nanodroplets. It was shown that the capsules are better stabilized by the copolymers with many short hydrophobic grafts than with fewer but longer ones. Use of photoactive polyelectrolytes enabled spectroscopic investigation of the relationship between conformation of the macromolecules and stabilization of the oil-core nanocapsules. Long-term stability of the nanocapsules was achieved and further increased by multilayer shell formation using polyelectrolytes deposited via the layer-by-layer approach. The obtained capsules served as efficient nanocontainers for a hydrophobic fluorescent probe. The proposed strategy of nanocapsule preparation may be easily extended to biologically relevant polymers and applied to fabricate liquid core nanodelivery systems without the need of using low molecular weight additives which may have adverse effects in numerous biomedical applications.A surfactant-free method of preparation of nanocapsules templated on liquid cores using amphiphilic graft polyelectrolytes was developed

  10. [Study of novel artificial lung surfactants incorporating partially fluorinated amphiphiles].

    Science.gov (United States)

    Nakahara, Hiromichi

    2012-01-01

    Lung surfactants (LS), a complex of ∼90 wt% lipids (mainly dipalmitoylphosphatidylcholine or DPPC) and ∼10 wt% surfactant proteins (SP-A, -B, -C, and -D), adsorb to an air-alveolar fluid interface and then lower its surface tension down to near zero during expiration. Intratracheal instillation of exogenous LS preparations can effectively compensate for surfactant deficiency in premature infants with respiratory distress syndrome (RDS). Surfacten® (Mitsubishi Tanabe Pharma Corporation, Osaka, Japan), a modified bovine lung extract and an effective surfactant replacement in treatment for RDS patients, is supplemented with DPPC, palmitic acid, and tripalmitin. For the premature infants suffering from RDS, instillation of Surfacten® leads to a dramatic improvement in lung function and compliance. Herein, the author reviews potential use of newly designed preparations containing a mimicking peptide of SP-B and also introduces the current research on the preparations incorporated with partially fluorinated amphiphiles to improve their efficacy. PMID:22790027

  11. Rational Design of Pathogen-Mimicking Amphiphilic Materials as Nanoadjuvants

    Science.gov (United States)

    Ulery, Bret D.; Petersen, Latrisha K.; Phanse, Yashdeep; Kong, Chang Sun; Broderick, Scott R.; Kumar, Devender; Ramer-Tait, Amanda E.; Carrillo-Conde, Brenda; Rajan, Krishna; Wannemuehler, Michael J.; Bellaire, Bryan H.; Metzger, Dennis W.; Narasimhan, Balaji

    2011-12-01

    An opportunity exists today for cross-cutting research utilizing advances in materials science, immunology, microbial pathogenesis, and computational analysis to effectively design the next generation of adjuvants and vaccines. This study integrates these advances into a bottom-up approach for the molecular design of nanoadjuvants capable of mimicking the immune response induced by a natural infection but without the toxic side effects. Biodegradable amphiphilic polyanhydrides possess the unique ability to mimic pathogens and pathogen associated molecular patterns with respect to persisting within and activating immune cells, respectively. The molecular properties responsible for the pathogen-mimicking abilities of these materials have been identified. The value of using polyanhydride nanovaccines was demonstrated by the induction of long-lived protection against a lethal challenge of Yersinia pestis following a single administration ten months earlier. This approach has the tantalizing potential to catalyze the development of next generation vaccines against diseases caused by emerging and re-emerging pathogens.

  12. Structure and reactivity in amphiphile-water micelles

    International Nuclear Information System (INIS)

    Following a review of the general properties of micelles, this report contains two parts: - A structural study of octylphosphate micelles. Important structural changes have been evidenced by mean of small angle neutron scattering as the electrical charge of the interface is varied. The NMR relaxation study of the conformation of the hydrocarbon chains has shown that the micellar core is disordered in contrast with the interface which is rather structured. The diffusion motions in the interface and the segmental motions of the chains are fast. - Studies on the reactivity in micelles have been carried out. A large micellar effect on the complexation of transition ions by amphiphilic ligands is evidenced. The problem of solute localization in micelles is developed with few examples. (author)

  13. Amphiphilic siderophore production by oil-associating microbes.

    Science.gov (United States)

    Kem, Michelle P; Zane, Hannah K; Springer, Stephen D; Gauglitz, Julia M; Butler, Alison

    2014-06-01

    The Deepwater Horizon oil spill in 2010 released an unprecedented amount of oil into the ocean waters of the Gulf of Mexico. As a consequence, bioremediation by oil-degrading microbes has been a topic of increased focus. One factor limiting the rate of hydrocarbon degradation by microbial communities is the availability of necessary nutrients, including iron. The siderophores produced from two Vibrio spp. isolated from the Gulf of Mexico following the Deepwater Horizon oil spill, along with the well-studied oil-degrading microbe, Alcanivorax borkumensis SK2, are studied under iron-limiting conditions. Here we report the amphiphilic amphibactin siderophores produced by the oil-associated bacteria, Vibrio sp. S1B, Vibrio sp. S2A and Alcanivorax borkumensis SK2. These findings provide insight into oil-associating microbial iron acquisition. PMID:24663669

  14. Aminoglycoside-derived amphiphilic nanoparticles for molecular delivery.

    Science.gov (United States)

    Miryala, Bhavani; Godeshala, Sudhakar; Grandhi, Taraka Sai Pavan; Christensen, Matthew D; Tian, Yanqing; Rege, Kaushal

    2016-10-01

    The development of effective drug carriers can lead to improved outcomes in a variety of disease conditions. Aminoglycosides have been used as antibacterial therapeutics, and are attractive as monomers for the development of polymeric materials in various applications. Here, we describe the development of novel aminoglycoside-derived amphiphilic nanoparticles for drug delivery, with an eye towards ablation of cancer cells. The aminoglycoside paromomycin was first cross-linked with resorcinol diglycidyl ether leading to the formation of a poly (amino ether), PAE. PAE molecules were further derivatized with methoxy-terminated poly(ethylene glycol) or mPEG resulting in the formation of mPEG-PAE polymer, which self-assembled to form nanoparticles. Formation of the mPEG-PAE amphiphile was characterized using (1)H NMR, (13)C NMR, gel permeation chromatography (GPC) and FTIR spectroscopy. Self-assembly of the polymer into nanoparticles was characterized using dynamic light scattering, zeta potential analyses, atomic force microscopy (AFM) and the pyrene fluorescence assay. mPEG-PAE nanoparticles were able to carry significant amounts of doxorubicin (DOX), presumably by means of hydrophobic interactions between the drug and the core. Cell-based studies indicated that mPEG-PAE nanoparticles, loaded with doxorubicin, were able to induce significant loss in viabilities of PC3 human prostate cancer, MDA-MB-231 human breast cancer, and MB49 murine bladder cancer cells; empty nanoparticles resulted in negligible losses of cell viability under the conditions investigated. Taken together, our results indicate that the mPEG-PAE nanoparticle platform is attractive for drug delivery in different applications, including cancer. PMID:27472455

  15. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    Directory of Open Access Journals (Sweden)

    Sanjib K. Shrestha

    2014-12-01

    Full Text Available K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20’s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were determined. Effects on Cryptococcus neoformans H-99 infectivity were determined with a preventive murine lung infection model. The antifungal mechanism of action was studied using intact fungal cells, yeast lipid mutants, and small unilamellar lipid vesicles. K20 exhibited broad-spectrum in vitro antifungal activities but not antibacterial activities. Pulmonary, single dose-administration of K20 reduced C. neoformans lung infection rates 4-fold compared to controls. Hemolysis and half-maximal cytotoxicities of mammalian cells occurred at concentrations that were 10 to 32-fold higher than fungicidal MICs. With fluorescein isothiocyanate, 20 to 25 mg/L K20 caused staining of >95% of C. neoformans and Fusarium graminearum cells and at 31.3 mg/L caused rapid leakage (30 to 80% in 15 min of calcein from preloaded small unilamellar lipid vesicles. K20 appears to be a broad-spectrum fungicide, capable of reducing the infectivity of C. neoformans, and exhibits low hemolytic activity and mammalian cell toxicity. It perturbs the plasma membrane by mechanisms that are lipid modulated. K20 is a novel amphiphilic aminoglycoside amenable to scalable production and a potential lead antifungal for therapeutic and crop protection applications.

  16. Nanocapsules templated on liquid cores stabilized by graft amphiphilic polyelectrolytes.

    Science.gov (United States)

    Szafraniec, Joanna; Janik, Małgorzata; Odrobińska, Joanna; Zapotoczny, Szczepan

    2015-03-12

    A surfactant-free method of preparation of nanocapsules templated on liquid cores using amphiphilic graft polyelectrolytes was developed. A model photoactive copolymer, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate) with grafted poly(vinylnaphthalene) chains (PAMPS-graft-PVN) was used to stabilize toluene droplets in an aqueous emulsion. The macromolecules, due to their amphiphilic character and the presence of strong ionic groups, tend to undergo intramolecular aggregation in water but at the water-oil interface less compact conformation is preferred with PVN grafts anchoring in the oil phase and the charged PAMPS main chains residing in the aqueous phase, thus stabilizing the nanoemulsion droplets. Formation of such nanocapsules was confirmed by dynamic light scattering measurements as well as SEM and cryo-TEM imaging. Grafting density and content of the chromophores in the graft copolymers were varied in order to achieve high stability of the coated nanodroplets. It was shown that the capsules are better stabilized by the copolymers with many short hydrophobic grafts than with fewer but longer ones. Use of photoactive polyelectrolytes enabled spectroscopic investigation of the relationship between conformation of the macromolecules and stabilization of the oil-core nanocapsules. Long-term stability of the nanocapsules was achieved and further increased by multilayer shell formation using polyelectrolytes deposited via the layer-by-layer approach. The obtained capsules served as efficient nanocontainers for a hydrophobic fluorescent probe. The proposed strategy of nanocapsule preparation may be easily extended to biologically relevant polymers and applied to fabricate liquid core nanodelivery systems without the need of using low molecular weight additives which may have adverse effects in numerous biomedical applications. PMID:25737427

  17. Globules of annealed amphiphilic copolymers: Surface structure and interactions

    Science.gov (United States)

    Jarkova, E.; Johner, A.; Maresov, E. A.; Semenov, A. N.

    2006-12-01

    A mean-field theory of globules of random amphiphilic copolymers in selective solvents is developed for the case of an annealed copolymer sequence: each unit can be in one of two states, H (insoluble) or P (soluble or less insoluble). The study is focussed on the regime when H and P units tend to form long blocks, and when P units dominate in the dilute phase, but are rare in the globule core. A first-order coil-to-globule transition is predicted at some T = Tcg. The globule core density at the transition point increases as the affinity of P units to the solvent, tildeɛ, is increased. Two collapse transitions, coil → “loose” globule and “loose” globule → “dense” globule, are predicted if tildeɛ is high enough and P units are marginally soluble or weakly insoluble. H and P concentration profiles near the globule surface are obtained and analyzed in detail. It is shown that the surface excess of P units rises as tildeɛ is increased. The surface tension decreases in parallel. Considering the interaction between close enough surfaces of two globules, we show that they always attract each other at a complete equilibrium. It is pointed out, however, that such equilibrium may be difficult to reach, so that partially equilibrium structures (defined by the condition that a chain forming one globule does not penetrate into the core of the other globule) are relevant. It is shown that at such partial equilibrium the interaction is repulsive, so the globules may be stabilized from aggregation. The strongest repulsion is predicted at the coil-to-globule transition point Tcg: the repulsion force decreases with the distance between the surfaces according to a power law. In the general case (apart from Tcg) the force vs. distance decay becomes exponential; the decay length ξ diverges as T → Tcg. The developed theory explains certain anomalous properties observed for globules of amphiphilic homopolymers.

  18. Non-Surface Activity of Cationic Amphiphilic Diblock Copolymers

    International Nuclear Information System (INIS)

    Cationic amphiphilic diblock copolymers containing quaternized poly (2-vinylpyridine) chain as a hydrophilic segment (PIp-b-PNMe2VP) were synthesized by living anionic polymerization. By IR measurement, we confirmed the quaternization of the polymer (PIp-b-PNMe2VP), and determined the degree of quaternization by conductometric titration. The surface tension experiment showed that the polymers are non-surface active in nature. The foam formation of the polymer solutions was also investigated with or without added salt. Almost no foam formation behavior was observed without added salt, while a little foam was observed in the presence of 1M NaCl. The critical micelle concentration (cmc) of the diblock copolymers with 3 different chain lengths was measured by the static light scattering method. The cmc values obtained in this study were much lower than the values obtained for anionic non-surface active diblock polymers studied previously. The hydrodynamic radii of the polymer micelle increased slightly in the presence of 1 M NaCl. The transmission electron microscopic images revealed spherical micelles in pure water. In the presence of salt, the cmc values increased as was the case for anionic polymers, which is unlike conventional surfactant systems but consistent with non-surface active anionic block copolymers. The microviscosity of the micelle core was evaluated using Coumarin-153 as a fluorescent anisotropy probe using steady-sate fluorescence depolarization. Non-surface activity has been proved to be universal for ionic amphiphilic block copolymers both for anionic and cationic. Hence, the origin of non-surface activity is not the charged state of water surface itself, but should be an image charge repulsion at the air/water interface.

  19. [Determination of succinic acid in desvenlafaxine succinate by high performance ion-exclusion chromatography and high performance ion-exchange chromatography].

    Science.gov (United States)

    Zong, Yanping; Li, Jinghua; Sun, Wei; Liu, Guixia; Lu, Jinghua; Shan, Guangzhi

    2016-02-01

    New methods were developed for the determination of succinic acid in desvenlafaxine succinate (DVS) by high performance ion-exclusion chromatography (HPIEC) and high performance ion-exchange chromatography (HPIC). HPIEC and HPIC methods were used separately to determinate the succinic acid in DVS. With HPIEC, the sample was diluted with 2. 50 x 10(-3) mol/L sulfuric acid solution and filtrated by 0. 22 µm polyether sulfone filter membrane, and then analyzed by HPIEC directly without any further pretreatment. The analytical column was Phenomenex Rezex ROA-organic Acid H+(8%) (300 mmx7. 8 mm). The mobile phase was 2. 50x10(-3) mol/L sulfuric acid solution at the flow rate of 0. 5 mL/min. The column temperature was set at 40 °C, and the detection wavelength was 210 nm. The injection volume was 10 KL. The assay was quantified by external standard method. With HPIC, the sample was diluted with ultrapure water and filtrated by 0. 22 µm polyether sulfone filter membrane, and then analyzed by HPIC directly without any further pretreatment. The analytical column was Dionex IonPac AS11-HC (250 mm x 4 mm) with a guard column IonPacAG11-HC (50 mm x 4 mm). Isocratic KOH elute generator was used at the flow rate of 1. 0 mL/min. The detection was performed by a Dionex suppressed (DIONEX AERS 500 4-mm) conductivity detector. The injection volume was 10 µL. The content computation was performed with peak area external reference method. The results of HPIEC method for succinic acid were 28. 8%, 28. 9% and 28. 9%, while the results of HPIEC method were 28. 2%, 28. 6% and 28. 6%. The results of HPIEC and HPIC methods were not significantly different. The two methods can both be used to determine the contents of succinic acid in DVS. The surveillance analytical method should be chosen according to the situation. PMID:27382725

  20. H2-dependent anaerobic growth of Escherichia coli on L-malate: succinate formation.

    Science.gov (United States)

    Macy, J; Kulla, H; Gottschalk, G

    1976-02-01

    Escherichia coli grew anaerobically on L-malate only in the presence of H2; 91% of the L-malate utilized was converted to succinate. Anaerobically isolated membrane vesicles catalyzed the reduction of fumarate with H2 and contained a b-type cytochrome. Cytochrome c552 was present in the "periplasmic space." PMID:1107323

  1. Immunolocalization of succinate dehydrogenase in the esophagus epithelium of domesticated mammals

    OpenAIRE

    Meyer, W.; Kacza, J.; I. N. Hornickel; Schoennagel, B.

    2013-01-01

    Using immunohistochemistry and transmission electron microscopy (TEM), the esophagus epithelia of seven domesticated mammals (horse, cattle, goat, pig, dog, laboratory rat, cat) of three nutrition groups (herbivorous, omnivorous, carnivorous) were studied to get first information about energy generation, as demonstrated by succinate dehydrogenase (SDH) activities. Distinct reaction intensities could be observed in all esophageal cell layers of the different species studied reflecting moderate...

  2. A complete industrial system for economical succinic acid production by Actinobacillus succinogenes.

    Science.gov (United States)

    Li, Jian; Zheng, Xiao-Yu; Fang, Xiao-Jiang; Liu, Shu-Wen; Chen, Ke-Quan; Jiang, Min; Wei, Ping; Ouyang, Ping-Kai

    2011-05-01

    An industrial fermentation system using lignocellulosic hydrolysate, waste yeast hydrolysate, and mixed alkali to achieve high-yield, economical succinic acid production by Actinobacillus succinogenes was developed. Lignocellulosic hydrolysate and waste yeast hydrolysate were used efficiently as carbon sources and nitrogen source instead of the expensive glucose and yeast extract. Moreover, as a novel method for regulating pH mixed alkalis (Mg(OH)(2) and NaOH) were first used to replace the expensive MgCO(3) for succinic acid production. Using the three aforementioned substitutions, the total fermentation cost decreased by 55.9%, and 56.4 g/L succinic acid with yield of 0.73 g/g was obtained, which are almost the same production level as fermentation with glucose, yeast extract and MgCO(3). Therefore, the cheap carbon and nitrogen sources, as well as the mixed alkaline neutralize could be efficiently used instead of expensive composition for industrial succinic acid production. PMID:21470857

  3. Coordination compounds of succinate some 3d-metals with thiosemicarbazone furfurol

    International Nuclear Information System (INIS)

    In article the results of synthesis and investigations of the Ni (II), Co (II), Cu (II) and Zn succinates with thiosemicarbazone furfurol complexes were shown. The consistence, individuality, the pattern of coordination of apical ligand and the thermal behavior of obtained complexes were established. (author)

  4. Methods for upgrading of a fuel gas and succinic acid production

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention provides methods of upgrading of a CO2-containing fuel gas comprising the use of anaerobic succinic acid-producing microorganisms. Thus, the present invention provides a method for simultaneous upgrading of a CO2-containing fuel gas and biosuccinic acid production....

  5. Thermochemical pretreatments for enhancing succinic acid production from industrial hemp (Cannabis sativa L.)

    DEFF Research Database (Denmark)

    Gunnarsson, Ingólfur Bragi; Kuglarz, Mariusz; Karakashev, Dimitar Borisov;

    2015-01-01

    The aim of this study was to develop an efficient thermochemical method for treatment of industrial hemp biomass, in order to increase its bioconversion to succinic acid. Industrial hemp was subjected to various thermochemical pretreatments using 0-3% H2SO4, NaOH or H2O2 at 121-180°C prior to enz...

  6. Bio-oil based biorefinery strategy for the production of succinic acid

    DEFF Research Database (Denmark)

    Wang, Caixia; Thygesen, Anders; Liu, Yilan;

    2013-01-01

    Background: Succinic acid is one of the key platform chemicals which can be produced via biotechnology process instead of petrochemical process. Biomass derived bio-oil have been investigated intensively as an alternative of diesel and gasoline fuels. Bio-oil could be fractionized into organic...

  7. Metabolic engineering of Saccharomyces cerevisiae microbial cell factories for succinic acid production

    DEFF Research Database (Denmark)

    Otero, José Manuel; Olsson, Lisbeth; Nielsen, Jens

    2007-01-01

    for further conversion to precursor molecules such as tetrahydrofuran, 1,4-butanediol, and butyrolactone. Succinic acid has the potential to become a commodity chemical, with world-wide annual demand exceeding $2 billion USD and over 160 million kg currently produced from petrochemical conversion of...

  8. Integration of Succinic Acid Production in a Dry Mill Ethanol Facility

    Energy Technology Data Exchange (ETDEWEB)

    None

    2006-08-01

    This project seeks to address both issues for a dry mill ethanol biorefinery by lowering the cost of sugars with the development of an advanced pretreatment process, improving the economics of succinic acid (SA), and developing a model of an ethanol dry mill to evaluate the impact of adding different products and processes to a dry mill.

  9. Succinic Acid as a Byproduct in a Corn-based Ethanol Biorefinery

    Energy Technology Data Exchange (ETDEWEB)

    MBI International

    2007-12-31

    MBI endeavored to develop a process for succinic acid production suitable for integration into a corn-based ethanol biorefinery. The project investigated the fermentative production of succinic acid using byproducts of corn mill operations. The fermentation process was attuned to include raw starch, endosperm, as the sugar source. A clean-not-sterile process was established to treat the endosperm and release the monomeric sugars. We developed the fermentation process to utilize a byproduct of corn ethanol fermentations, thin stillage, as the source of complex nitrogen and vitamin components needed to support succinic acid production in A. succinogenes. Further supplementations were eliminated without lowering titers and yields and a productivity above 0.6 g l-1 hr-1was achieved. Strain development was accomplished through generation of a recombinant strain that increased yields of succinic acid production. Isolation of additional strains with improved features was also pursued and frozen stocks were prepared from enriched, characterized cultures. Two recovery processes were evaluated at pilot scale and data obtained was incorporated into our economic analyses.

  10. Inhibition of mitochondrial glycerol-3-phosphate dehydrogenase by alpha-tocopheryl succinate

    Czech Academy of Sciences Publication Activity Database

    Rauchová, Hana; Vokurková, Martina; Drahota, Zdeněk

    2014-01-01

    Roč. 53, AUG (2014), s. 409-413. ISSN 1357-2725 R&D Projects: GA ČR(CZ) GAP304/12/0259 Institutional support: RVO:67985823 Keywords : brown adipose tissue mitochondria * oxygen consumption * glycerol-3-phosphate * succinate * reactive oxygen species Subject RIV: ED - Physiology Impact factor: 4.046, year: 2014

  11. Inhibition of Salmonella Typhimurium by Anaerobic Cecal Bacteria in Media Supplemented with Lactate and Succinate

    Science.gov (United States)

    The ability of anaerobic cecal microflora of broilers to inhibit growth of Salmonella Typhimurium in media supplemented with lactate and succinate was examined. Cecal cultures were prepared by collecting ceca of processed broilers from a commercial processing facility, inoculating broth media with 1...

  12. Controlling morphology and dynamics of nano-scale assemblies of amphiphilic copolymers in aqueous environment

    Czech Academy of Sciences Publication Activity Database

    Borisova, O. V.; Billon, L.; Grassl, B.; Štěpánek, Petr; Bakaeva, Zulfiya; Zaremski, M.; Zhulina, E. B.; Borisov, O. V.

    Pisa : European Polymer Federation, 2013. O3-7. [European Polymer Congress - EPF 2013. 16.06.2013-21.06.2013, Pisa] Institutional support: RVO:61389013 Keywords : nanoparticles * amphiphilic copolymers Subject RIV: CD - Macromolecular Chemistry

  13. Exploring single chain amphiphile self-assembly and their possible roles in light transduction

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain

    2011-01-01

    Self-assembled structures of single-chain amphiphiles have been used as hosts for biochemical, and chemical reactions. Their use as models for protocells (i.e., precursors to the first biological cells) has been extensively researched by various groups because the availability of single chain...... amphiphiles on the early Earth seems reasonably well-documented either by exo-terrestrial delivery or endogeneous syntheses, a fact that singles them out as potential building blocks of primitive membranes. These studies have highlighted two important aspects of the self-assembly of single chain amphiphiles......: the medium composition in terms of ionic strengths and the medium physical parameters, such as temperature, significantly influence the formation of structures, as well as their subsequent stability. In addition, membranes composed of a single amphiphile type seem to be implausible as no potential...

  14. Amphiphilic oligoethyleneimine-β-cyclodextrin "click" clusters for enhanced DNA delivery.

    Science.gov (United States)

    Martínez, Álvaro; Bienvenu, Céline; Jiménez Blanco, José L; Vierling, Pierre; Mellet, Carmen Ortiz; García Fernández, José M; Di Giorgio, Christophe

    2013-08-16

    Monodisperse amphiphilic oligoethyleneimine (OEI)-β-cyclodextrin (βCD) clusters have been prepared, and their potential as gene delivery systems has been evaluated in comparison with a nonamphiphilic congener. The general prototype incorporates tetraethyleneimine segments linked to the primary rim of βCD through either triazolyl or thioureidocysteaminyl connectors. Transfection efficiency data for the corresponding CD:pDNA nanocomplexes (CDplexes) in BNL-CL2 murine hepatocytes evidenced the strong beneficial effect of facial amphiphilicity. PMID:23859761

  15. Self-assembly of a peptide amphiphile: transition from nanotape fibrils to micelles

    OpenAIRE

    Miravet Celades, Juan Felipe; Escuder Gil, Beatriu; Segarra Maset, María Dolores; Tena Solsona, Marta; Hamley, Ian W.; Dehsorkhi, Ashkan; Castelletto, Valeria

    2013-01-01

    A thermal transition is observed in the peptide amphiphile C16-KTTKS (TFA salt) from nanotapes at 20 °C to micelles at higher temperature (the transition temperature depending on concentration). The formation of extended nanotapes by the acetate salt of this peptide amphiphile, which incorporates a pentapeptide from type I procollagen, has been studied previously [V. Castelletto et al., Chem. Commun., 2010, 46, 9185]. Here, proton NMR and SAXS provide evidence for the TFA salt spherical micel...

  16. Self-assembly of a peptide amphiphile: transition from nanotape fibrils to micelles

    OpenAIRE

    Miravet, Juan F.; Escuder, Beatriu; Segarra-Maset, Maria Dolores; Tena-Solsona, Marta; Hamley, Ian W.; Dehsorkhi, Ashkan; Castelletto, Valeria

    2013-01-01

    A thermal transition is observed in the peptide amphiphile C16-KTTKS (TFA salt) from nanotapes at 20 degrees C to micelles at higher temperature (the transition temperature depending on concentration). The formation of extended nanotapes by the acetate salt of this peptide amphiphile, which incorporates a pentapeptide from type I procollagen, has been studied previously [V. Castelletto et al., Chem. Commun., 2010, 46, 9185]. Here, proton NMR and SAXS provide evidence for the TFA salt spherica...

  17. Synthesis and aggregation properties of amphiphilic mono and bisadducts of fullerene in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Pu Zhang; Zhi Xin Guo; Shuang Lv

    2008-01-01

    New amphiphilic[60]fullerene monoadduet TPF and bisadducts BTPF were synthesized and well-characterized. Their aggregation properties in aqueous solution was investigated by UV-vis and TEM methods. In aqueous solution, monoadduct TPF forms irregularly shaped and some rod-like aggregates, whereas bisadducts BTPF gives spherical aggregates with diameters of 50-150 nm. It indicated that the aggregation properties of amphiphilic fullerene derivatives depend on the number of hydrophilic appendage on the C60 cage.

  18. Long-Circulating 15 nm Micelles Based on Amphiphilic 3-Helix Peptide-PEG Conjugates

    OpenAIRE

    Dong, He; Dube, Nikhil; Shu, Jessica Y.; Seo, Jai W.; Mahakian, Lisa M; Ferrara, Katherine W.; Xu, Ting

    2012-01-01

    Generating stable, multi-functional organic nanocarriers will have a significant impact on drug formulation. However, it remains a significant challenge to generate organic nanocarriers with a long circulation half-life, effective tumor penetration and efficient clearance of metabolites. We have advanced this goal by designing a new family of amphiphiles based on coiled-coil 3-helix bundle forming peptide-poly(ethylene glycol) conjugates. The amphiphiles self-assemble into monodisperse micell...

  19. CLINICAL AND ECONOMICAL ASSESSMENTS OF METOPROLOL TARTRATE/SUCCINATE USAGE IN PATIENTS WITH ISCHEMIC HEART DISEASE

    Directory of Open Access Journals (Sweden)

    M. V. Soura

    2016-01-01

    Full Text Available Clinical and clinicoeconomical studies review is presented as well as results of author’s comparative cost analysis on metoprolol tartrate (Betaloc and metoprolol succinate (Betaloc ZOK usage in patients with ischemic heart disease. Efficacy of metoprolol therapy is proven in randomized clinical studies in patients with angina and myocardial infarction (MI. In angina patients metoprolol prevents cardiac attacks, MI, reduces nitroglycerine consumption, increases exercise tolerability, prolongs the exercise time before ST segment depression (succinate better than tartrate, decrease of angina intensity. In MI patients metoprolol therapy reduces mortality, sudden death, recurring MI and the rate of early post MI angina attacks. Nowadays metoprolol is the only β-blocker having indication on secondary MI prevention. Besides for the present metoprolol succinate is the only β-blocker with proven direct antisclerosis effect. According to Swedish clinicoeconomical study in patients after MI secondary prevention with metoprolol therapy saves the costs in comparison with placebo. American clinicoeconomical model of metoprolol and atenolol usage in all patients with MI could result in significant reduction in mortality and recurring MI rate, prolong the life and improve its quality, save financial resources. The cost of monthly treatment of angina patient with metoprolol tartrate (Betaloc and metoprolol succinate (Betaloc ZOK is 135 and 354 rubles, respectively. The price range of comparative β-blockers in ascending order is the following: atenolol (Atenolol Nicomed → metoprolol tartrate (Betaloc → metoprolol succinate (Betaloc ZOK → bisoprolol (Concor → nebivolol (Nebilet. In conclusion, metoprolol therapy is the one of mostly economically reasonable approach.

  20. Amphiphile self-assemblies in supercritical CO2 and ionic liquids.

    Science.gov (United States)

    Zhang, Jianling; Peng, Li; Han, Buxing

    2014-08-28

    Supercritical (sc) CO2 and ionic liquids (ILs) are very attractive green solvents with tunable properties. Using scCO2 and ILs as alternatives of conventional solvents (water and oil) for forming amphiphile self-assemblies has many advantages. For example, the properties and structures of the amphiphile self-assemblies in these solvents can be easily modulated by tuning the properties of solvents; scCO2 has excellent solvation power and mass-transfer characteristics; ILs can dissolve both organic and inorganic substances and their properties are designable to satisfy the requirements of various applications. Therefore, the amphiphile self-assemblies in scCO2 and ILs have attracted considerable attention in recent years. This review describes the advances of using scCO2 or/and ILs as amphiphile self-assembly media in the last decade. The amphiphile self-assemblies in scCO2 and ILs are first reviewed, followed by the discussion on combination of scCO2 and ILs in creating microemulsions or emulsions. Some future directions on the amphiphile self-assemblies in scCO2 and ILs are highlighted. PMID:25000970

  1. Solubility of α-Tocopheryl Succinate in Supercritical Carbon Dioxide Using Offline HPLC-MS/MS Analysis

    OpenAIRE

    Hybertson, Brooks M.

    2007-01-01

    The solubility of the vitamin E-related compound α-tocopheryl succinate in supercritical carbon dioxide was measured at pressures ranging from (15.0 to 30.0) MPa and temperatures of (40 and 50) °C using a simple microsampling type apparatus with a 100.5 μL sample loop to remove aliquots and collect them in ethanol for off line analysis. α-Tocopheryl succinate concentrations in the collected samples were measured using HPLC-MS/MS analysis. The solubility of α-tocopheryl succinate in supercriti...

  2. Synthesis of antibacterial amphiphilic elastomer based on polystyrene-block-polyisoprene-block-polystyrene via thiol-ene addition

    International Nuclear Information System (INIS)

    A new type of amphiphilic antibacterial elastomer has been described. Thermoplastic elastomer, polystyrene–block-polyisoprene–block-polystyrene (PS–b-PI–b-PS) triblock copolymer was functionalized in toluene solution by free radical mercaptan addition in order to obtain an amphiphilic antibacterial elastomer. Thiol terminated PEG was grafted through the double bonds of PS–b-PI–b-PS via free radical thiol-ene coupling reaction. The antibacterial properties of the amphiphilic graft copolymers were observed. The original and the modified polymers were used to create microfibers in an electro-spinning process. Topology of the electrospun micro/nanofibers were studied by using scanning electron microscopy (SEM). The chemical structures of the amphiphilic comb type graft copolymers were elucidated by the combination of elemental analysis, 1H NMR, 13C NMR, GPC and FTIR. - Graphical abstract: Double bonds of polyisoprene units in polystyrene–block-polyisoprene–block-polystyrene triblock copolymer were partially capped with PEG containing mercapto end group via thiol-ene addition in order to obtain antibacterial amphiphilic elastomer. Nano fibers from amphiphilic graft polymers solution were produced by electrospinning. The PEG grafted copolymer inhibits very effectively bacterial growth. Highlights: ► A commercial synthetic elastomer was grafted with PEG to obtain amphiphilic elastomer. ► Amphiphilic elastomer shows antibacterial properties. ► Electrospun micro fibers of the amphiphilic elastomer tend to globular formation

  3. Combinatorial optimization of CO2 transport and fixation to improve succinate production by promoter engineering.

    Science.gov (United States)

    Yu, Jun-Han; Zhu, Li-Wen; Xia, Shi-Tao; Li, Hong-Mei; Tang, Ya-Ling; Liang, Xin-Hua; Chen, Tao; Tang, Ya-Jie

    2016-07-01

    To balance the flux of an engineered metabolic pathway to achieve high yield of target product is a major challenge in metabolic engineering. In previous work, the collaborative regulation of CO2 transport and fixation was investigated with co-overexpressing exogenous genes regulating both CO2 transport (sbtA and bicA) and PEP carboxylation (phosphoenolpyruvate (PEP) carboxylase (ppc) and carboxykinase (pck)) under trc promoter in Escherichia coli for succinate biosynthesis. For balancing metabolic flux to maximize succinate titer, a combinatorial optimization strategy to fine-tuning CO2 transport and fixation process was implemented by promoter engineering in this study. Firstly, based on the energy matrix a synthetic promoter library containing 20 rationally designed promoters with strengths ranging from 0.8% to 100% compared with the widely used trc promoter was generated. Evaluations of rfp and cat reporter genes provided evidence that the synthetic promoters were stably and had certain applicability. Secondly, four designed promoters with different strengths were used for combinatorial assembly of single CO2 transport gene (sbtA or bicA) and single CO2 fixation gene (ppc or pck) expression. Three combinations, such as Tang1519 (P4 -bicA + pP19 -pck), Tang1522 (P4 -sbtA + P4 -ppc), Tang1523 (P4 -sbtA + P17 -ppc) with a more than 10% increase in succinate production were screened in bioreactor. Finally, based on the above results, co-expression of the four transport and fixation genes were further investigated. Co-expression of sbtA, bicA, and ppc with weak promoter P4 and pck with strong promoter P19 (AFP111/pT-P4 -bicA-P4 -sbtA + pACYC-P19 -pck-P4 -ppc) provided the best succinate production among all the combinations. The highest succinate production of 89.4 g/L was 37.5% higher than that obtained with empty vector control. This work significantly enhanced succinate production through combinatorial optimization of CO2 transport and fixation

  4. Comments on recently published "L-threonine phthalate" and pure and doped "L-lysinium succinate" crystals

    Science.gov (United States)

    Petrosyan, A. M.

    2016-04-01

    It is shown that the recently published papers on "L-threonine phthalate" (Theras et al. (2015) [2]) and pure and doped "L-lysinium succinate" (Kalaivani et al. (2015) [11,16]) misidentified the targeted compounds.

  5. RRR-α-tocopheryl succinate inhibits human gastric cancer SGC-7901 cell growth by inducing apoptosis and DNA synthesis arrest

    OpenAIRE

    Wu, Kun; ZHAO Yan; Liu, Bai-He; Li, Yao; Liu, Fang; Guo, Jian; Yu, Wei-Ping

    2002-01-01

    AIM: To investigate the effects of growth inhibition of human gastric cancer SGC-7901 cell with RRR-α-tocopheryl succinate (VES), a derivative of natural Vitamin E, via inducing apoptosis and DNA synthesis arrest.

  6. Supramolecular micellar nanoaggregates based on a novel chitosan/vitamin E succinate copolymer for paclitaxel selective delivery

    Directory of Open Access Journals (Sweden)

    Lian H

    2011-12-01

    Full Text Available He Lian1, Jin Sun1, Yan Ping Yu1, Yan Hua Liu2, Wen Cao1, Yong Jun Wang1, Ying Hua Sun1, Si Ling Wang1, Zhong Gui He11School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, 2Department of Pharmaceutics, School of Pharmacy, Ningxia Medical University, Ningxia, People's Republic of ChinaBackground: Nowadays, many cytotoxic anticancer drugs exhibit low solubility and poor tumor selectivity, which means that the drug formulation is very important. For example, in the case of paclitaxel (PTX, Cremophor EL® (BASF, Ludwigshafen, Germany needs to be used as a solubilizer in its clinical formulation (Taxol®, Bristol-Myers Squibb, New York, NY, although it can cause serious side effects. Nanomicellar systems are promising carriers to resolve the above problems, and the polymer chosen is the key element.Methods: In this study, a novel amphiphilic chitosan/vitamin E succinate (CS-VES copolymer was successfully synthesized for self-assembling polymeric micelles. Proton nuclear magnetic resonance spectroscopy and infrared were used to characterize the molecular structure of the copolymer. The PTX-loaded CS-VES polymeric micelles (PTX-micelles were characterized by dynamic light scattering, transmission electron microscopy, X-ray diffraction, and differential scanning calorimetry.Results: The critical micelle concentration of CS-VES was about 12.6 µg/mL, with the degree of amino group substitution being 20.4%. PTX-micelles were prepared by a nanoprecipitation/dispersion technique without any surfactant being involved. PTX-micelles exhibited a drug loading as high as 21.37% and an encapsulation efficiency of 81.12%, with a particle size ranging from 326.3 to 380.8 nm and a zeta potential of +20 mV. In vitro release study showed a near zero-order sustained release, with 51.06%, 50.88%, and 44.35% of the PTX in the micelles being released up to 168 hours at three drug loadings of 7.52%, 14.09%, and 21.37%, respectively. The cellular uptake

  7. Modification of nanofibrillated cellulose using amphiphilic block-structured galactoglucomannans.

    Science.gov (United States)

    Lozhechnikova, Alina; Dax, Daniel; Vartiainen, Jari; Willför, Stefan; Xu, Chunlin; Österberg, Monika

    2014-09-22

    Nanofibrillated cellulose (NFC) and hemicelluloses have shown to be highly promising renewable components both as barrier materials and in novel biocomposites. However, the hydrophilic nature of these materials restricts their use in some applications. In this work, the usability of modified O-acetyl galactoglucomannan (GGM) for modification of NFC surface properties was studied. Four GGM-block-structured, amphiphilic derivatives were synthesized using either fatty acids or polydimethylsiloxane as hydrophobic tails. The adsorption of these GGM derivatives was consecutively examined in aqueous solution using a quartz crystal microbalance with dissipation monitoring (QCM-D). It was found that the hydrophobic tails did not hinder adsorption of the GGM derivatives to cellulose, which was concluded to be due to the presence of the native GGM-block with high affinity to cellulose. The layer properties of the adsorbed block-co-polymers were discussed and evaluated. Self-standing NFC films were further prepared and coated with the GGM derivatives and the effect of the surface modification on wetting properties and oxygen permeability (OP) of the modified films was assessed. PMID:24906743

  8. Effect of Amphiphiles on the Rheology of Triglyceride Networks

    Science.gov (United States)

    Seth, Jyoti

    2014-11-01

    Networks of aggregated crystallites form the structural backbone of many products from the food, cosmetic and pharmaceutical industries. Such materials are generally formulated by cooling a saturated solution to yield the desired solid fraction. Crystal nucleation and growth followed by aggregation leads to formation of a space percolating fractal-network. It is understood that microstructural hierarchy and particle-particle interactions determine material behavior during processing, storage and use. In this talk, rheology of suspensions of triglycerides (TAG, like tristearin) will be explored. TAGs exhibit a rich assortment of polymorphs and form suspensions that are evidently sensitive to surface modifying additives like surfactants and polymers. Here, a theoretical framework will be presented for suspensions containing TAG crystals interacting via pairwise potentials. The work builds on existing models of fractal aggregates to understand microstructure and its correlation with material rheology. Effect of amphiphilic additives is derived through variation of particle-particle interactions. Theoretical predictions for storage modulus will be compared against experimental observations and data from the literature and micro structural predictions against microscopy. Such a theory may serve as a step towards predicting short and long-term behavior of aggregated suspensions formulated via crystallization.

  9. Amphiphilic self-assembly of alkanols in protic ionic liquids.

    Science.gov (United States)

    Jiang, Haihui Joy; FitzGerald, Paul A; Dolan, Andrew; Atkin, Rob; Warr, Gregory G

    2014-08-21

    Strong cohesive forces in protic ionic liquids (PILs) can induce a liquid nanostructure consisting of segregated polar and apolar domains. Small-angle X-ray scattering has shown that these forces can also induce medium chain length n-alkanols to self-assemble into micelle- and microemulsion-like structures in ethylammonium (EA(+)) and propylammonium (PA(+)) PILs, in contrast to their immiscibility with both water and ethanolammonium (EtA(+)) PILs. These binary mixtures are structured on two distinct length scales: one associated with the self-assembled n-alkanol aggregates and the other with the underlying liquid nanostructure. This suggests that EA(+) and PA(+) enable n-alkanol aggregation by acting as cosurfactants, which EtA(+) cannot do because its terminating hydroxyl renders the cation nonamphiphilic. The primary determining factor for miscibility and self-assembly is the ratio of alkyl chain lengths of the alkanol and PIL cation, modulated by the anion type. These results show how ILs can support the self-assembly of nontraditional amphiphiles and enable the creation of new forms of soft matter. PMID:25068766

  10. Perfluorocyclobutyl-containing Amphiphilic Block Copolymers Synthesized by RAFT Polymerization

    Institute of Scientific and Technical Information of China (English)

    LI, Yongjun; ZHANG, Sen; FENG, Chun; ZHANG, Yaqin; LI, Qingnuan; LI, Wenxin; HUANG, Xiaoyu

    2009-01-01

    Amphiphilic block copolymers containing hydrophobic perfluorocyclobutyl-based (PFCB) polyacrylate and hydrophilic poly(ethylene glycol) (PEG) segments were prepared via reversible addition-fragmentation chain transfer (RAP-T) polymerization. The PFCB-containing acrylate monomer, p-(2-(p-tolyloxy)perfluorocyclobutoxy)phenyl acrylate, was first synthesized from commercially available compounds in good yields, and this kind of acrylate monomer can be homopolymerized by free radical polymerization or RAFT polymerization. Kinetic study showed the 2,2'-azobis(isobutyronitrile) (AIBN) initiated and cumyl dithiobenzoate (CDB) mediated RAFT polymerization was in a living fashion, as suggested by the fact that the number-average molecular weights (M_n) increased linearly with the conversions of the monomer, while the polydispersity indices kept less than 1.10. The block polymers with narrow molecular weight distributions (M_w/M_n≤1.21) were prepared through RAFT polymerization using PEG monomethyl ether capped with 4-cyanopentanoic acid dithiobenzoate end group as the macro chain transfer agent (mPEG-CTA). The length of the hydrophobic segment can be tuned by the feed ratio of the PFCB-based acrylate monomer and the extending of the polymerization time. The micellization behavior of the block copolymers in aqueous media was investigated by the fluorescence probe technique.

  11. Tissue Regeneration through Self-Assembled Peptide Amphiphile Nanofibers

    Directory of Open Access Journals (Sweden)

    Hossein Hosseinkhani

    2006-01-01

    Full Text Available Introduction: In the present study, we hypothesized that a novelapproach to promote vascularization would be to create injectablethree dimensional (3-D scaffolds within growth factor that enhancethe sustained release of growth factor and induce the angiogenesis.Material and Methods: We demonstrate that a 3-D scaffold can beformed by mixing of peptide-amphiphile (PA aqueous solution withhepatocyte growth factor (HGF solution. PA was synthesized bystandard solid phase chemistry that ends with the alkylation of theNH2 terminus of the peptide. The sequence of arginine-glycineasparticacid (RGD was included in peptide design as well. A 3-Dnetwork of nanofibers was formed by mixing HGF suspensions withdilute aqueous solution of PA.Results: Scanning electron microscopy (SEM examination revealedthe formation of fibrous assemblies with an extremely high aspectratio and high surface areas with mean diameter of less than 200 nm.In vitro HGF release profile of 3-D nanofibers was investigated whileangiogenesis induced by the released HGF was being assessed. Invivo potential ability of PA nanofibers to induce angiogenesis wasassessed through subcutaneous injection of PA solution, HGFsolution, and PA in combination with HGF solutions. Injection of PAwith HGF induced significant angiogenesis around the injected site,in marked contrast to HGF injection alone and PA injection alone.Conclusion: The combination of HGF-induced angiogenesis is apromising procedure to improve tissue regeneration.

  12. Function of Amphiphilic Biomolecular Machines: Elastic Protein-based Polymers

    Science.gov (United States)

    Urry, Dan W.

    2000-03-01

    Elastic protein-based polymers function as biomolecular machines due to inverse temperature transitions of hydrophobic folding and assembly. The transitions occur either on raising the temperature from below to above the transition temperature, Tt, or on isothermally lowering Tt from above to below an operating temperature. The inverse temperature transition involves a decrease in entropy of the polymer component of the system on raising the temperature and a larger increase in solvent entropy on hydrophobic association. Tt depends on the quantity of hydrophobic hydration that undergoes transition to bulk water. Designed amphiphilic polymers perform free energy transductions involving the intensive variables of mechanical force, pressure, temperature, chemical potential, electrochemical potential and electromagnetic radiation and define a set of five axioms for their function as machines. The physical basis for these diverse energy conversions is competition for hydration between apolar (hydrophobic) and polar (e.g., charged) moieties. The effectiveness of these Tt-type entropic elastic protein-based machines is due to repeating peptide sequences that form regular, dynamic repeating structures and exhibit damping of backbone torsional oscillations on extension.

  13. Membrane deformation controlled by monolayer composition of embedded amphiphilic nanoparticles

    Science.gov (United States)

    van Lehn, Reid; Alexander-Katz, Alfredo

    2014-03-01

    In recent work, we have shown that charged, amphiphilic nanoparticles (NPs) can spontaneously insert into lipid bilayers, embedding the NP in a conformation resembling a transmembrane protein. Many embedded membrane proteins exert an influence on surrounding lipids that lead to deformation and membrane-mediated interactions that may be essential for function. Similarly, embedded NPs will also induce membrane deformations related to the same physicochemical forces. Unlike many transmembrane proteins, however, the highly charged NPs may exert preferential interactions on surrounding lipid head groups. In this work, we use atomistic molecular dynamics simulations to show that the membrane around embedded particles may experience local thinning, head group reorientation, and an increase in lipid density depending on the size and surface composition of the NP. We quantify the extent of these deformations and illustrate the complex interplay between lipid tail group and head group interactions that go beyond pure thickness deformations that may be expected from coarse-grained or continuum models. This work thus suggests guidelines for the design of particles that spontaneously partition into lipid bilayers and influence local membrane mechanical properties in a targeted manner.

  14. Synthesis and Bioactivities of Kanamycin B-Derived Cationic Amphiphiles.

    Science.gov (United States)

    Fosso, Marina Y; Shrestha, Sanjib K; Green, Keith D; Garneau-Tsodikova, Sylvie

    2015-12-10

    Cationic amphiphiles derived from aminoglycosides (AGs) have been shown to exhibit enhanced antimicrobial activity. Through the attachment of hydrophobic residues such as linear alkyl chains on the AG backbone, interesting antibacterial and antifungal agents with a novel mechanism of action have been developed. Herein, we report the design and synthesis of seven kanamycin B (KANB) derivatives. Their antibacterial and antifungal activities, along with resistance/enzymatic, hemolytic, and cytotoxicity assays were also studied. Two of these compounds, with a C12 and C14 aliphatic chain attached at the 6″-position of KANB through a thioether linkage, exhibited good antibacterial and antifungal activity, were poorer substrates than KANB for several AG-modifying enzymes, and could delay the development of resistance in bacteria and fungi. Also, they were both relatively less hemolytic than the known membrane targeting antibiotic gramicidin and the known antifungal agent amphotericin B and were not toxic at their antifungal MIC values. Their oxidation to sulfones was also demonstrated to have no effect on their activities. Moreover, they both acted synergistically with posaconazole, an azole currently used in the treatment of human fungal infections. PMID:26592740

  15. Synthesis, aggregation, and chiroptical properties of chiral, amphiphilic dendrimers.

    Science.gov (United States)

    Laufersweiler, M J; Rohde, J M; Chaumette, J L; Sarazin, D; Parquette, J R

    2001-09-21

    The syntheses of amphiphilic dendrimers based on 3,5-dihydroxybenzyl alcohol containing tri- or tetrafunctional chiral central cores and allyl ester termini are described. Water solubility is imparted to the dendrimers via a palladium-catalyzed deprotection of the peripheral allyl esters. This method affords complete deprotection of the carboxylate surface because, in contrast to the basic hydrolysis of methyl ester termini, the solubility of partially hydrolyzed intermediates is maintained throughout the course of the deprotection, thereby avoiding precipitation during the reaction. Chiroptical analysis indicates that the structure of the dendrimers collapses in water, resulting in an increased steric effect upon the central core that is manifested by lower optical rotatory power. However, contributions to the chiroptical properties from the dendron branch segments were not evident in water or organic media, suggesting that chiral substructures were not developing in the branch segments of the dendrimers. Multiangle light scattering studies revealed that the dendrimers experienced significant aggregation in aqueous media that decreased at higher generations. This behavior could be rationalized by a change in conformational preference from a disklike conformation at low generations to a more globular conformation at higher generations. PMID:11559197

  16. Optimization of hypocrellin B derivative amphiphilicity and biological activity

    Institute of Scientific and Technical Information of China (English)

    LIU Xin; XIE Jie; ZHANG LuYong; CHEN HongXia; GU Ying; ZHAO JingQuan

    2009-01-01

    To satisfy the dual requirements of the fluent transportation in blood and the affinity to the target tissues of vascular diseases, hypocrellin derivatives with optimized amphiphilicity are expected. In this work, 3-amino-1-propanesulfonic acid and 4-amino-1-butanesulfonic acid substituted hypocrellin B,named compounds 1 and 2, were designed, synthesized in high yields and characterized. Besides greatly strengthened red absorption, the maximum solubility of compound 2 in phosphate buffered saline (PBS) is 4.2 mg/mL which is just enough to prepare an aqueous solution for intravenous injection in clinically acceptable concentration, while the partition coefficient between n-octanol and PBS,5.6, benefits the cell-uptake and biological activity as well. Furthermore, EPR measurements reveal that the photosensitization activities of the two compounds to generate semiquinone anion radicals, superoxide anion radicals and singlet oxygen are a little bit higher than those of taurine substituted hypocrellin B (THB), but the photodynamic activities to human lung cancer A549 cells are several times that of THB, mainly due to increases in lipophilicity and cell-uptake.

  17. Highly Branched Pentasaccharide-Bearing Amphiphiles for Membrane Protein Studies.

    Science.gov (United States)

    Ehsan, Muhammad; Du, Yang; Scull, Nicola J; Tikhonova, Elena; Tarrasch, Jeffrey; Mortensen, Jonas S; Loland, Claus J; Skiniotis, Georgios; Guan, Lan; Byrne, Bernadette; Kobilka, Brian K; Chae, Pil Seok

    2016-03-23

    Detergents are essential tools for membrane protein manipulation. Micelles formed by detergent molecules have the ability to encapsulate the hydrophobic domains of membrane proteins. The resulting protein-detergent complexes (PDCs) are compatible with the polar environments of aqueous media, making structural and functional analysis feasible. Although a number of novel agents have been developed to overcome the limitations of conventional detergents, most have traditional head groups such as glucoside or maltoside. In this study, we introduce a class of amphiphiles, the PSA/Es with a novel highly branched pentasaccharide hydrophilic group. The PSA/Es conferred markedly increased stability to a diverse range of membrane proteins compared to conventional detergents, indicating a positive role for the new hydrophilic group in maintaining the native protein integrity. In addition, PDCs formed by PSA/Es were smaller and more suitable for electron microscopic analysis than those formed by DDM, indicating that the new agents have significant potential for the structure-function studies of membrane proteins. PMID:26966956

  18. Amphiphilic Polymer Micellar Disruption Based on Main-Chain Photodegradation.

    Science.gov (United States)

    Tian, Min; Cheng, Ruidong; Zhang, Jun; Liu, Zhaotie; Liu, Zhongwen; Jiang, Jinqiang

    2016-01-12

    The amphiphilic block copolymer poly(ethylene oxide)-b-poly(N,N'-dihydroxypyromellitimide-hexamethylene diisocyanate) (PEO-b-PNH) with photocleavable N-O urethanes has been prepared to investigate the photodegradation of the hydrophobic main chain and therefore the disruption of copolymer micelles. Measurements of absorption and emission spectra, optical transmittance, DLS analysis, and TEM observations were applied. It was shown that PEO-b-PNH could self-assemble into flower compound micelles in water. The photodegradation of the hydrophobic polyurethane within the micellar core upon irradiation with 365 nm light could be conveniently controlled by changing the irradiation intensity; furthermore, complete micellar disruption could be achieved when 42% of N-O urethanes were photocleaved. By using DOX as the hydrophobic guest, the drug release profile showed a linear leakage of DOX out of the swelling polymer micelles in the initial stage and thereafter a much more quick exponential decay of DOX precipitation because of the micellar disruption upon further irradiation. The diffusion experiment of the leaked DOX into buffer solution (pH 7.4) showed that the DOX leakage could be prominently accelerated by a very short time of 365 nm irradiation, indicating that the N-O photocleavage can serve as a "turn-on" switch for the release of DOX in aqueous media. PMID:26641733

  19. DEVELOPMENT AND VALIDATION OF SPECTROPHOTOMETRIC METHODS FOR SIMULTANEOUS ESTIMATION OF METOPROLOL SUCCINATE AND TELMISARTAN IN COMBINED PHARMACEUTICAL FORMULATION

    OpenAIRE

    Mayur Modi*, Rikin Shah and R.C. Mashru

    2012-01-01

    Four simple, rapid, precise, economical and accurate spectrophotometric methods have been developed for simultaneous analysis of Metoprolol succinate and Telmisartan in their combined dosage form. Method 1, First derivative simultaneous equation method (Vierodt’s method). It employs formation and solving of simultaneous equation using two wavelengths 230.2 nm (λmax of Metoprolol succinate) and 237 nm (λmax of Telmisartan) in first derivative spectra. Method 2, First derivative Q-Absorbance eq...

  20. Liquid–liquid extraction of gallium(III with n-octylaniline from succinate media

    Directory of Open Access Journals (Sweden)

    T. N. SHILMKAR

    2005-06-01

    Full Text Available The distribution equilibrium of gallium(III between n-octylaniline dissolved in toluene and acidic aqueous succinate media has been investigated as a function of the concentration of extractant in the organic phase and concentration of hydrogen ions and gallium(III ions in the aqueous phase. The stoichiometry of the extracted species was determined on the basis of slope analysis.Gallium(III is extracted by the anion exchange mechanism as [RNH3+Ga(succinate2]org. The temperature dependence of the extraction equilibria was examined by the temperature variationmethod. The extraction process is favoured with increasing temperature. It was found that a large number of cations and anions have a high tolerance limit. The selectivity of the extraction is increased by the use of suitable masking agents. The method affords the binary separation of gallium(III from associated elements and was further extended to the analysis of a synthetic mixture.

  1. FORMULATION AND EVALUATION OF METOPROLOL SUCCINATE CONTROLLED RELEASE TABLETS USING NATURAL AND SYNTHETIC POLYMER

    Directory of Open Access Journals (Sweden)

    A. Sathyaraj

    2012-01-01

    Full Text Available The objective of the present study to develop controlled release tablets of Metoprolol succinate using Natural polymer, guar gum and synthetic polymer, carbopol as a rate controlling polymers.. It was also desired to study the effect of polymer concentration. Metoprolol succinate, β1- selective adrenergic receptor- blocking agent used in the management of hypertension, angina pectoris, cardiac arrthymias, myocardial infarction, heart failure, hyperthyroidism and in the prophylactic treatment of migraine. The half-life of drug is relatively short approximately 4-6 hrs and in normal course of therapy drug administration is required every 4-6 hrs, thus warrants the use of controlled release formulation for prolong action and to improve patient compliance. In the present investigation Natural polymer, guar gum and synthetic polymer, carbopol have been selected as matrix forming materials for the drug. The formulations are made by employing the conventional wet granulation method, to achieve prolonged release of medicaments.

  2. Reactive processing of maleic anhydride-grafted poly(butylene succinate and the compatibilizing effect on poly(butylene succinate nanocomposites

    Directory of Open Access Journals (Sweden)

    Z. A. Mohd Ishak

    2013-04-01

    Full Text Available In this study, maleic anhydride-grafted poly(butylene succinate (PBS-g-MA was synthesized via reactive meltgrafting process using different initiator contents. The grafting efficiency was increased with the initiator content, manifested by the higher degree of grafting in PBS-g-MA. The grafting reaction was confirmed through Fourier transform infrared (FTIR spectroscopy and nuclear magnetic resonance (NMR spectroscopy. Then, PBS-g-MA was incorporated into organo-montmorillonite (OMMT filled poly(butylene succinate (PBS nanocomposites as compatibilizer. Mechanical properties of PBS nanocomposites were enhanced after compatibilized with PBS-g-MA, due to the better dispersion of OMMT in PBS matrix and the improved filler-matrix interfacial interactions. This was verifiable through X-ray diffraction (XRD, transmission electron microscopy (TEM and scanning electron microscopy (SEM. Differential scanning calorimetry (DSC showed that the degree of crystallinity and melting temperature increased after addition of PBS-g-MA. However, the presence of PBS-g-MA did not favor the thermal stability of the nanocomposites, as reported in the thermogravimetry (TGA.

  3. Actinobacillus succinogenes ATCC 55618 fermentation medium optimization for the production of succinic acid by response surface methodology.

    Science.gov (United States)

    Zhu, Li-Wen; Wang, Cheng-Cheng; Liu, Rui-Sang; Li, Hong-Mei; Wan, Duan-Ji; Tang, Ya-Jie

    2012-01-01

    As a potential intermediary feedstock, succinic acid takes an important place in bulk chemical productions. For the first time, a method combining Plackett-Burman design (PBD), steepest ascent method (SA), and Box-Behnken design (BBD) was developed to optimize Actinobacillus succinogenes ATCC 55618 fermentation medium. First, glucose, yeast extract, and MgCO(3) were identified to be key medium components by PBD. Second, preliminary optimization was run by SA method to access the optimal region of the key medium components. Finally, the responses, that is, the production of succinic acid, were optimized simultaneously by using BBD, and the optimal concentration was located to be 84.6 g L(-1) of glucose, 14.5 g L(-1) of yeast extract, and 64.7 g L(-1) of MgCO(3). Verification experiment indicated that the maximal succinic acid production of 52.7 ± 0.8 g L(-1) was obtained under the identified optimal conditions. The result agreed with the predicted value well. Compared with that of the basic medium, the production of succinic acid and yield of succinic acid against glucose were enhanced by 67.3% and 111.1%, respectively. The results obtained in this study may be useful for the industrial commercial production of succinic acid. PMID:23093852

  4. Comparsion of the Effects of Succinate and NADH on Postmortem Metmyoglobin Redcutase Activity and Beef Colour Stability

    Institute of Scientific and Technical Information of China (English)

    GAO Xiao-guang; WANG Zhen-yu; TANG Meng-tian; MA Chang-wei; DAI Rui-tong

    2014-01-01

    In two experiments, the effects of succinate and NADH (reduced nicotinamide adenine dinucleotide) on metmyoglobin reductase activity and electron transport chain-linked metmyoglobin reduction were investigated and compared. In experiment 1, metmyoglobin (MetMb), substrate and inhibitors were incubated with mitochondria. Comparsion of the effects of succinate and NADH on MetMb reduction was investigated. The MetMb percentage in sample treated with 8 mol L-1 succinate decreased by about 69%after 3 h incubation, and the effect was inhibited by the addition of 10 mol L-1 electron transfer chain complex II inhibitor malonic acid;the MetMb percentage in samples treated with 2 mol L-1 NADH decreased by 56%and the effect was inhibited by the addition of 0.02 mol L-1 electron transport chain complex I inhibitor rotenone. These results indicated that electron transport chain played an important role in MetMb reduction. Both complex II and complex I take part in the MetMb reduction in mitochondria through different pathways. NADH-MetMb reduction system was less stable than succinate-MetMb system. In experiment 2, the beef longissimus dorsi muscle was blended with different concentrations of succinate or NADH. Enhancing patties with higher concentration of succinate or NADH improved colour stability in vacuum packaged samples (P<0.05). These results veriifed that mitochondria electron transport chain is related to the MetMb reduction in meat system.

  5. Development and Validation of First Order Derivative Spectrophotometric method for simultaneous estimation of Nifedipine and Metoprolol Succinate in Synthetic Mixture

    Directory of Open Access Journals (Sweden)

    Sojitra Rajanit

    2015-02-01

    Full Text Available The present manuscript describe simple, sensitive, rapid, accurate, precise and economical first derivative spectrophotometric method for the simultaneous determination of Nifedipine (NIFand Metoprolol Succinate (METin synthetic mixture. The derivative spectrophotometric method was based on the determination of both the drugs at their respective zero crossing point (ZCP. The first order derivative spectra was obtained in methanol and the determinations were made at 283.80 nm (ZCP of nifedipine for metoprolol succinate and 242.60 nm (ZCP of metoprolol succinate for nifedipine. The linearity was obtained in the concentration range of succinate 5-25 μg/ml for nifedipine and 25-125μg/ml for metoprolol. The mean recovery was 99.64 and 99.41 for Nifedipine and Metoprolol succinate, respectively. The method was found to be simple, sensitive, accurate and precise and was applicable for the simultaneous determination of Nifedipine and Metoprolol succinate in synthetic mixture. The results of analysis have been validated statistically and by recovery studies.

  6. Alpha-Tocopheryl succinate causes mitochondrial permeabilization by preferential formation of Bak channels

    Czech Academy of Sciences Publication Activity Database

    Procházka, L.; Dong, L.F.; Vališ, Karel; Freeman, R.; Ralph, S.J.; Turánek, J.; Neužil, Jiří

    2010-01-01

    Roč. 15, č. 7 (2010), s. 782-794. ISSN 1360-8185 R&D Projects: GA AV ČR(CZ) KAN200520703; GA AV ČR(CZ) IAA500520702; GA AV ČR(CZ) IAA500520602 Institutional research plan: CEZ:AV0Z50520701 Keywords : Vitamin E succinate * apoptosis * Noxa-Bak Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.397, year: 2010

  7. The H+/O ratio of proton translocation linked to the oxidation of succinate by mitochondria.

    Science.gov (United States)

    Krab, K; Soos, J; Wikström, M

    1984-12-10

    In a recent communication Lehninger and co-workers (Costa, L.E., Reynaferje, B., and Lehninger, A.L. (1984) J. Biol. Chem. 259, 4802-4811) reported values approaching 8 for the H+/O ratio of vectorial proton ejection from rat liver mitochondria respiring with succinate. Here we present a rigorous analysis of these measurements which reveals that they may significantly overestimate the true H+/O stoicheiometry. PMID:6096164

  8. Volatility of NH3 from internally mixed sodium succinate-NH4SO4 particles

    Science.gov (United States)

    Wang, Na; Zhang, Yunhong

    2016-04-01

    Contributing the complicacy of atmospheric constituents, aerosol particles may undergo complicated heterogeneous reactions that have profound consequences on their hygroscopic properties and volatility. Ammonia (NH3) is a ubiquitous trace atmospheric gas in the troposphere and has negative effects on human health and climate forcing of ambient aerosols. In addition, atmospheric cycle of NH3 is complex in atmosphere, therefore it necessary to get insights to the complexity of gas-to-aerosol NH3 partitioning, which results in large uncertainties in the sources and distributions of NH3. By using in-situ Fourier transform infrared spectroscopy and attenuated total reflection (FTIR-ATR), we report here the volatility of NH3 from the laboratory generated sodium succinate with ammonium sulfate ((NH4)2SO4) at a 1:1 molar ratio as well as its effect on the hygroscopicity of the mixtures. The loss of the NH4+ peak at 1451cm‑1 and the formation of peaks at 1718 and 1134 cm‑1 due to C = O stretching asymmetric vibration of -COOH and ν3 (SO42‑) stretching of sodium sulfate indicate that sodium succinate reacts with (NH4)2SO4, releasing NH3 and forming succinic acid and sodium sulfate on dehydration process. The formation of less hygroscopic succinic acid and volatility of NH3 in mixtures leads to a significant decrease in the total water content. To the best of our knowledge, this is the first report of the reaction between (NH4)2SO4 and dicarboxylate salts, which may represent an important particle-gas partitioning for ammonia and thus elucidate another underlying ammonia cycle in atmosphere. These results could be helpful to understand the mutual transformation process of dicarboxylic acids and dicarboxylate salts.

  9. Health expenditure comparison of extended-release metoprolol succinate and immediate-release metoprolol tartarate

    OpenAIRE

    Vaidya V; Patel P

    2012-01-01

    Varun Vaidya, Pranav PatelCollege of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USABackground: Metoprolol, a selective beta-1 blocker, is available in two different salt forms in the market – metoprolol succinate (MS) and metoprolol tartarate (MT). Both the formulations are Food and Drug Administration approved for the treatment of hypertension. Several studies have shown similar efficacies between the two salts; however, they differ in their pharmacokin...

  10. CLINICAL AND ECONOMICAL ASSESSMENTS OF METOPROLOL TARTRATE/SUCCINATE USAGE IN PATIENTS WITH ISCHEMIC HEART DISEASE

    OpenAIRE

    M. V. Soura

    2016-01-01

    Clinical and clinicoeconomical studies review is presented as well as results of author’s comparative cost analysis on metoprolol tartrate (Betaloc) and metoprolol succinate (Betaloc ZOK) usage in patients with ischemic heart disease. Efficacy of metoprolol therapy is proven in randomized clinical studies in patients with angina and myocardial infarction (MI). In angina patients metoprolol prevents cardiac attacks, MI, reduces nitroglycerine consumption, increases exercise tolerability, prolo...

  11. FORMULATION AND EVALUATION OF SUSTAINED RELEASE LIQUISOLID TABLETS OF METOPROLOL SUCCINATE

    Directory of Open Access Journals (Sweden)

    Jarag Ravindra Jagannath

    2013-03-01

    Full Text Available Liquisolid technique is the novel concept of drug delivery via the oral route. This technique is applied to poorly water soluble, water insoluble or liphophilic drugs. According to the new formulation method of liquisolid compacts, liquid medications such as solutions or suspensions of water insoluble drugs in suitable non-volatile vehicles can be converted into acceptably flowing and compressible powders by blending with selected powder excipients. The present research endeavor is directed towards the development of liquisolid compact for the production of sustained release tablet of water-soluble Metoprolol succinate. Liquisolid compacts were prepared by using Tween 80 as the liquid vehicle or non-volatile solvent, Avicel PH 102 as absorbing carrier and Aerosil 200 as adsorbing coating material. The prepare dliquisolid systems were evaluated for their micromeretic properties and possible drug-excipients interactions. P-XRD analysis confirmed that no change in crystallinity of Metoprolol succinate Liquisolid compacts. The DSC and IR spectra analysis study ruled out no any significant interaction between the drug and excipients used in preparation of Metoprolol succinate Liquisolid compacts. The tableting properties were falling within acceptable limits. The in vitro dissolution study confirmed reduction in drug release from Liquisolid compacts compared to conventional matrix tablet, in-vivo study was carried out to check the plasma drug concentration. Tween 80 has plasticizer effect by which it can reduce the glass transition temperature of polymer and impart flexibility in sustaining the release of drug from liquisolid matrices. The results showed that wet granulation had a remarkable impact on the release rate of Metoprolol succinate from liquisolid compacts, reducing the release rate of drug from liquisolid compacts.

  12. FORMULATION AND RELEASE CHARACTERISTICS OF HPMC MATRIX TABLETS OF METOPROLOL SUCCINATE

    OpenAIRE

    Sobhita Rani P et al.

    2012-01-01

    The objective of this study was to design and evaluate oral sustained drug delivery system for Metoprolol succinate using pH sensitive polymer HPMC and sodium alginate and to evaluate its efficacy in reducing the hypertension. The drug filler blend was mixed with various concentrations of hydrophilic polymers such as HPMC, sodium alginate and combination of both the matrixing agents. The tablets were prepared by wet granulation method. Matrix tablets were evaluated for weight variation, conte...

  13. DEVELOPMENT AND IN-VITRO EVALUATION OF METOPROLOL SUCCINATE CONTROLLED POROSITY OSMOTIC PUMP TABLETS

    OpenAIRE

    Veeramalla Anil Kumar; Madishetty Vamshikrishna; Indarapu Rajendra Prasad; Gudikandula Raj Kumar; Kadari Srinivas

    2013-01-01

    In the present research work, attempts were made to develop and evaluate Sustained release formulation of Metoprolol succinate based on osmotic technology.As Metoprolol is a short acting drug, developed formulation provides the advantages of controlled release formulations. The developed formulation provides advantages of less steps of manufacturing procedure, no need of laser drilling, and economical. All of these made the procedure easily amenable to mass production using conventional table...

  14. 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 ...

  15. Effect of vitamin E succinate on inflammatory cytokines induced by high-intensity interval training

    Directory of Open Access Journals (Sweden)

    Hadi Sarir

    2015-01-01

    Full Text Available Aim and Scope: The anti-inflammatory effect of vitamin E under moderate exercises has been evaluated. However, the effect of vitamin E succinate, which has more potent anti-inflammatory effect than other isomers of vitamin E has not been evaluated. Therefore, the aim of the present study was to evaluate the effects of vitamin E succinate on tumor necrosis factor alpha (TNF-a and interleukin-6 (IL-6 production induced by high-intensity interval training (HIIT. Materials and Methods: In the present study, 24 rats were randomly divided into control (C, supplementation (S, HIIT, and HIIT + supplementation (HIIT+S groups. HIIT training protocol on a treadmill (at a speed of 40-54 m/min and vitamin E succinate supplementation (60 mg/kg/day was conducted for 6 weeks. Results: Serum IL-6 in the HIIT group significantly increased compared with the C group (350.42 ± 123.31 pg/mL vs 158.60 ± 41.96 pg/mL; P = 0.002. Also, serum TNF-a concentrations significantly enhanced (718.15 ± 133.42 pg/mL vs 350.87 ± 64.93 pg/mL; P = 0.001 in the HIIT group compared with the C group. Treatment of the training group with vitamin E numerically reduced IL-6 and TNF-a when compared with the HIIT group (217.31 ± 29.21 and 510.23 ± 217.88, respectively, P > 0.05. However, no significant changes were observed in serum TNF-a (P = 0.31 and IL-6 (P = 0.52 concentrations in the HIIT + S group compared with the C group. Conclusion: HIIT-induced IL-6 and TNF-α decreased by administration of Vitamin E succinate.

  16. Efficacy of Vigabatrin Intervention in a Mild Phenotypic Expression of Succinic Semialdehyde Dehydrogenase Deficiency

    OpenAIRE

    Casarano, M.; Alessandrì, M G.; Salomons, G.S.; E. Moretti; Jakobs, C.; Gibson, K. M.; G. Cioni; Battini, R.

    2011-01-01

    We report a patient with succinic semialdehyde dehydrogenase deficiency who presented a mild phenotype including developmental language delay, in association with the typical elevations of 4-hydroxybutyric acid (GHB) in biological fluids and MRI alterations. Two pathogenic mutations were identified one transversion (c.278 G>T) in exon 1 and another (c.1557 T>G) in exon 10. Both parents are carriers of one of the mutations, confirming compound-heterozygosity in their affected child. To reduce ...

  17. Effect of hydrophilic and hydrophobic polymers on release kinetics of metoprolol succinate extended release tablets

    OpenAIRE

    2011-01-01

    The purpose of the present work is to design and evaluate extended release matrix tablets of metoprolol succinate to reduce the dosing frequency and to improve patient compliance. The matrix tablets were prepared by the combination of hydrophilic and hydrophobic polymers, using methocel 10000 Cps in combination with ethyl cellulose 7 Cps, Eudragit® RS100, Eudragit® S100, and Eudragit® L100.The tablets were prepared by direct compression technique. Prepared formulations were evaluated for vari...

  18. Mutations in sdh (succinate dehydrogenase genes) alter the thiamine requirement of Salmonella typhimurium.

    OpenAIRE

    Enos-Berlage, J L; Downs, D. M.

    1997-01-01

    Mutants lacking the first enzyme in de novo purine synthesis (PurF) can synthesize thiamine if increased levels of pantothenate are present in the culture medium (J. L. Enos-Berlage and D. M. Downs, J. Bacteriol. 178:1476-1479, 1996). Derivatives of purF mutants that no longer required pantothenate for thiamine-independent growth were isolated. Analysis of these mutants demonstrated that they were defective in succinate dehydrogenase (Sdh), an enzyme of the tricarboxylic acid cycle. Results o...

  19. Study and modification of poly(butylene succinate) properties, a biobased and biodegradable polyester

    OpenAIRE

    Freyermouth, Floriane

    2014-01-01

    Within the frame of sustainable development, biobased and biodegradable polymers are going to play an important role according to economic and environmental perspectives. The polyolefins currently used in packaging and automotive industries will be replaced by biomaterials. The poly(butylene succinate), an “old” aliphatic polyester, has recently regained interest thanks to its biobased and biodegradable potential and mechanical properties similar to polyolefins. However, this polyester is ver...

  20. Self-assembly of ssDNA-amphiphiles into micelles, nanotapes and nanotubes

    Science.gov (United States)

    Pearce, Timothy R.

    The field of DNA nanotechnology utilizes DNA as a construction material to create functional supramolecular and multi-dimensional structures like two-dimensional periodic lattices and three-dimensional polyhedrons with order on the nanometer scale for many nanotechnology applications including molecular templating, nanosensors, and drug delivery. Single-stranded DNA (ssDNA) is often used to create these nanostructures as the DNA bases provide an intrinsic molecular code that can be exploited to allow for the programmed assembly of structures based upon Watson-Crick base-pairing. However, engineering these complex structures from biopolymers alone requires careful design to ensure that the intrinsic forces responsible for organizing the materials can produce the desired structures. Additional control over supramolecular assembly can be achieved by chemically modifying the ssDNA with hydrophobic moieties to create amphiphilic molecules, which adds the hydrophobic interaction to the list of contributing forces that drive the self-assembly process. We first explored the self-assembly behavior of a set of ssDNA aptamer-amphiphiles composed of the same hydrophobic tail and hydrophilic ssDNA aptamer headgroup but with different spacer molecules linking these groups together. Through the use of cryo-transmission electron microscopy (cryo-TEM), small angle x-ray scattering (SAXS), and circular dichroism (CD) we show that the aptamer-amphiphiles can assemble into a variety of structures depending on the spacer used. We demonstrated, for the first time, the creation of self-assembled aptamer-amphiphile nanotape structures and show that the choice of the spacer used in the design of aptamer-amphiphiles can influence their supramolecular self-assembly as well as the secondary structure of the aptamer headgroup. We next explored the role of the ssDNA headgroup on the amphiphile self-assembly behavior by designing amphiphiles with headgroups of multiple lengths and nucleotides

  1. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Purdy Drew, Kirstin R.; Sanders, Lori K.; Culumber, Zachary W.; Zribi, Olena; Wong, Gerard C.L.; (UIUC)

    2009-06-17

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

  2. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Drew, K.R.Purdy; Sanders, L.K.; Culumber, Z.W.; Zribi, O.; Wong, G.C.L.

    2009-05-21

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

  3. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    International Nuclear Information System (INIS)

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers

  4. Fluorinated amphiphiles control the insertion of α-hemolysin pores into lipid bilayers.

    Science.gov (United States)

    Raychaudhuri, Pinky; Li, Qiuhong; Mason, Amy; Mikhailova, Ellina; Heron, Andrew J; Bayley, Hagan

    2011-03-15

    The insertion of fully folded and assembled ion channels and pores into planar lipid bilayers for electrical recording has been facilitated by the use of conventional detergents at a final concentration below the critical micelle concentration (CMC). After the desired number of channels or pores (often one) has been incorporated into a bilayer, it is important to prevent further insertion events, which is often done by awkward techniques such as perfusion. Here, we show that the addition of single-chain fluorinated amphiphiles (F-amphiphiles) with zwitterionic, simple neutral, and neutral oligomeric headgroups at a concentration above the CMC prevents the further insertion of staphylococcal α-hemolysin pores, MspA pores, and Kcv potassium channels into lipid bilayers. We found the commercially available F(6)FC (fluorinated fos-choline with a C(6)F(13)C(2)H(4) chain) to be the least perturbing and most effective agent for this purpose. Bilayers are known to be resistant to F-amphiphiles, which in this case we suppose sequester the pores and channels within amphiphile aggregates. We suggest that F-amphiphiles might be useful in the fabrication of bilayer arrays for nanopore sensor devices and the rapid screening of membrane proteins. PMID:21275394

  5. Water-inducing molecular self-assembly of amphiphilic molecules into nanofibers

    International Nuclear Information System (INIS)

    Graphical abstract: TPDP nanofibers with smooth surfaces can be obtained by reprecipitation method using ethanol as good solvent and water as poor solvent. In the self-assembly process, during the water adding to the amphiphilic molecules’ saturated solution, the amphiphilic molecules firstly assembled into needle-like small rods. With an increase in the self-assembled time, a large number of the nanofibers are produced. The assembly behavior was revealed in the course of direct in situ monitoring of its growth with optical microscopy. Highlights: ► 2,3,6,7-Tetramethoxy-9,10-di(4-pyridyl)-9,10-dihydroanthracen (TPDP) was synthesized. ► TPDP nanofibers can be obtained by reprecipitation method. ► The assembly behavior was revealed in situ monitoring with optical microscopy. -- Abstract: We present investigations on the microcosmic self-assembly process of new synthesized amphiphilic TPDP molecules. It can be seen that pure TPDP nanofibers with smooth surfaces can be obtained by reprecipitation method using ethanol as good solvent and water as poor solvent. In the self-assembly process, during the water adding to the amphiphilic molecules’ saturated solution, the amphiphilic molecules firstly assembled into needle-like small rods. With an increase in the self-assembled time, a large number of the nanofibers are produced. The assembly behavior was revealed in the course of direct in situ monitoring of its growth with optical microscopy. Field emission scanning electron microscopy was adopted to characterize the morphologies of the products.

  6. Efficient and repeated production of succinic acid by turning sugarcane bagasse into sugar and support.

    Science.gov (United States)

    Chen, Pengcheng; Tao, Shengtao; Zheng, Pu

    2016-07-01

    Here we reported an endeavor in making full use of sugarcane bagasse for biological production of succinic acid. Through NaOH pre-treatment and multi-enzyme hydrolysis, a reducing sugar solution mainly composed of glucose and xylose was obtained from the sugarcane bagasse. By optimizing portions of cellulase, xylanase, β-glucanase and pectinase in the multi-enzyme "cocktail", the hydrolysis percentage of the total cellulose in pre-treated sugarcane bagasse can be as high as 88.5%. A. succinogenes CCTCC M2012036 was used for converting reducing sugars into succinic acid in a 3-L bioreactor with a sugar-fed strategy to prevent cell growth limitation. Importantly, cells were found to be adaptive on the sugarcane bagasse residue, offering possibilities of repeated batch fermentation and replacement for MgCO3 with soluble NaHCO3 in pH modulation. Three cycles of fermentation without activity loss were realized with the average succinic acid yield and productivity to be 80.5% and 1.65g·L(-1)·h(-1). PMID:27035471

  7. Aqueous Phase Photo-Oxidation of Succinic Acid: Changes in Hygroscopic Properties and Reaction Products

    Science.gov (United States)

    Hudson, P. K.; Ninokawa, A.; Hofstra, J.; de Lijser, P.

    2013-12-01

    Atmospheric aerosol particles have been identified as important factors in understanding climate change. The extent to which aerosols affect climate is determined, in part, by hygroscopic properties which can change as a result of atmospheric processing. Dicarboxylic acids, components of atmospheric aerosol, have a wide range of hygroscopic properties and can undergo oxidation and photolysis reactions in the atmosphere. In this study, the hygroscopic properties of succinic acid aerosol, a non-hygroscopic four carbon dicarboxylic acid, were measured with a humidified tandem differential mobility analyzer (HTDMA) and compared to reaction products resulting from the aqueous phase photo-oxidation reaction of hydrogen peroxide and succinic acid. Reaction products were determined and quantified using gas chromatography-flame ionization detection (GC-FID) and GC-mass spectrometry (GC-MS) as a function of hydrogen peroxide:succinic acid concentration ratio and photolysis time. Although reaction products include larger non-hygroscopic dicarboxylic acids (e.g. adipic acid) and smaller hygroscopic dicarboxylic acids (e.g. malonic and oxalic acids), comparison of hygroscopic growth curves to Zdanovskii-Stokes-Robinson (ZSR) predictions suggests that the hygroscopic properties of many of the product mixtures are largely independent of the hygroscopicity of the individual components. This study provides a framework for future investigations to fully understand and predict the role of chemical reactions in altering atmospheric conditions that affect climate.

  8. Synthesis, Characterization and Biological Evaluation of Succinate Prodrugs of Curcuminoids for Colon Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Pornchai Rojsitthisak

    2011-02-01

    Full Text Available A novel series of succinyl derivatives of three curcuminoids were synthesized as potential prodrugs. Symmetrical (curcumin and bisdesmethoxycurcumin and unsymmetrical (desmethoxycurcumin curcuminoids were prepared through aldol condensation of 2,4-pentanedione with different benzaldehydes. Esterification of these compounds with a methyl or ethyl ester of succinyl chloride gave the corresponding succinate prodrugs in excellent yields. Anticolon cancer activity of the compounds was evaluated using Caco-2 cells. The succinate prodrugs had IC50 values in the 1.8–9.6 ��M range, compared to IC50 values of 3.3–4.9 μM for the parent compounds. Curcumin diethyl disuccinate exhibited the highest potency and was chosen for stability studies. Hydrolysis of this compound in phosphate buffer at pH 7.4 and in human plasma followed pseudo first-order kinetics. In phosphate buffer, the kobs and t1/2 for hydrolysis indicated that the compound was much more stable than curcumin. In human plasma, this compound was able to release curcumin, therefore our results suggest that succinate prodrugs of curcuminoids are stable in phosphate buffer, release the parent curcumin derivatives readily in human plasma, and show anti-colon cancer activity.

  9. Modeling conformational redox-switch modulation of human succinic semialdehyde dehydrogenase.

    Science.gov (United States)

    Tamazian, Gaik; Ho Chang, Jeong; Knyazev, Sergey; Stepanov, Eugene; Kim, Kyung-Jin; Porozov, Yuri

    2015-12-01

    Succinic semialdehyde dehydrogenase (SSADH) converts succinic semialdehyde (SSA) to succinic acid in the mitochondrial matrix and is involved in the metabolism of the inhibitory neurotransmitter γ-aminobutyric acid (GABA). The molecular structure of human SSADH revealed the intrinsic regulatory mechanism--redox-switch modulation--by which large conformational changes are brought about in the catalytic loop through disulfide bonding. The crystal structures revealed two SSADH conformations, and computational modeling of transformation between them can provide substantial insights into detailed dynamic redox modulation. On the basis of these two clear crystal structures, we modeled the conformational motion between these structures in silico. For that purpose, we proposed and used a geometry-based coarse-grained mathematical model of long-range protein motion and the related modeling algorithm. The algorithm is based on solving the special optimization problem, which is similar to the classical Monge-Kantorovich mass transportation problem. The modeled transformation was supported by another morphing method based on a completely different framework. The result of the modeling facilitates better interpretation and understanding of the SSADH biological role. PMID:26422261

  10. Out of plane distortions of the heme b of Escherichia coli succinate dehydrogenase.

    Directory of Open Access Journals (Sweden)

    Quang M Tran

    Full Text Available The role of the heme b in Escherichia coli succinate dehydrogenase is highly ambiguous and its role in catalysis is questionable. To examine whether heme reduction is an essential step of the catalytic mechanism, we generated a series of site-directed mutations around the heme binding pocket, creating a library of variants with a stepwise decrease in the midpoint potential of the heme from the wild-type value of +20 mV down to -80 mV. This difference in midpoint potential is enough to alter the reactivity of the heme towards succinate and thus its redox state under turnover conditions. Our results show both the steady state succinate oxidase and fumarate reductase catalytic activity of the enzyme are not a function of the redox potential of the heme. As well, lower heme potential did not cause an increase in the rate of superoxide production both in vitro and in vivo. The electron paramagnetic resonance (EPR spectrum of the heme in the wild-type enzyme is a combination of two distinct signals. We link EPR spectra to structure, showing that one of the signals likely arises from an out-of-plane distortion of the heme, a saddled conformation, while the second signal originates from a more planar orientation of the porphyrin ring.

  11. Integrated production of cellulosic bioethanol and succinic acid from industrial hemp in a biorefinery concept.

    Science.gov (United States)

    Kuglarz, Mariusz; Alvarado-Morales, Merlin; Karakashev, Dimitar; Angelidaki, Irini

    2016-01-01

    The aim of this study was to develop integrated biofuel (cellulosic bioethanol) and biochemical (succinic acid) production from industrial hemp (Cannabis sativa L.) in a biorefinery concept. Two types of pretreatments were studied (dilute-acid and alkaline oxidative method). High cellulose recovery (>95%) as well as significant hemicelluloses solubilization (49-59%) after acid-based method and lignin solubilization (35-41%) after alkaline H2O2 method were registered. Alkaline pretreatment showed to be superior over the acid-based method with respect to the rate of enzymatic hydrolysis and ethanol productivity. With respect to succinic acid production, the highest productivity was obtained after liquid fraction fermentation originated from steam treatment with 1.5% of acid. The mass balance calculations clearly showed that 149kg of EtOH and 115kg of succinic acid can be obtained per 1ton of dry hemp. Results obtained in this study clearly document the potential of industrial hemp for a biorefinery. PMID:26551652

  12. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    Giuseppina Raffaini

    2015-12-01

    Full Text Available Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a “bottom up” approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD, which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties.

  13. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations.

    Science.gov (United States)

    Raffaini, Giuseppina; Mazzaglia, Antonino; Ganazzoli, Fabio

    2015-01-01

    Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a "bottom up" approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD), which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties. PMID:26734094

  14. Synthesis of Dumbbell-shaped Hyperbranched Amphiphilic Block Copolymer by Controlled Atom Transfer Radical Polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Kyoung; An, Sung Guk; Cho, Chang Gi [Center for Advanced Functional Polymers, Department of Fiber and Polymer Science, Hanyang University, Seoul (Korea); Noh, Si Tae [Department of Chemical Engineering, Hanyang University, Ansan (Korea)

    2001-04-01

    Amphiphilic block copolymers containing hydrophilic ethylene glycol core and hyperbranched polystyrene (PS) arm were synthesized by atom transfer radical polymerization using hydrophilic macroinitiator and p-chloromethyl styrene (CMS) as AB type monomer. Hydrophilic poly(ethylene glycol)(PEG) macroinitiators with difuntional groups were synthesized by reacting PEG and 2-bromopropionyl bromide. The chemical structure, molecular weight, and polydispersity index of the amphiphilic block copolymer were characterized by {sup 1}H-NMR spectroscopy and GPC analysis. The molecular weight increased as the reaction time increased. Polydispersity index of the obtained polymer was relatively narrow (below 1.39). To control chain density of the hyperbranched PS, styrene and CMS were copolymerized. It was found that amphiphilic block copolymer molecule underwent conformational change in different solvents based on the result for {sup 1}H-NMR spectroscopic analysis. 29 refs., 8 figs., 2 tabs.

  15. Maltose-neopentyl glycol (MNG) amphiphiles for solubilization, stabilization and crystallization of membrane proteins

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Rasmussen, Søren G F; Rana, Rohini R; Gotfryd, Kamil; Chandra, Richa; Goren, Michael A; Kruse, Andrew C; Nurva, Shailika; Løland, Claus Juul; Pierre, Yves; Drew, David; Popot, Jean-Luc; Picot, Daniel; Fox, Brian G; Guan, Lan; Gether, Ulrik; Byrne, Bernadette; Kobilka, Brian; Gellman, Samuel H

    2010-01-01

    The understanding of integral membrane protein (IMP) structure and function is hampered by the difficulty of handling these proteins. Aqueous solubilization, necessary for many types of biophysical analysis, generally requires a detergent to shield the large lipophilic surfaces of native IMPs. Many...... family show favorable behavior relative to conventional detergents, as manifested in multiple membrane protein systems, leading to enhanced structural stability and successful crystallization. MNG amphiphiles are promising tools for membrane protein science because of the ease with which they may be...... proteins remain difficult to study owing to a lack of suitable detergents. We introduce a class of amphiphiles, each built around a central quaternary carbon atom derived from neopentyl glycol, with hydrophilic groups derived from maltose. Representatives of this maltose-neopentyl glycol (MNG) amphiphile...

  16. Mixtures of ions and amphiphilic molecules in slit-like pores: A density functional approach

    Energy Technology Data Exchange (ETDEWEB)

    Pizio, O., E-mail: pizio@unam.mx [Instituto de Química, Universidad Nacional Autonoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México, D. F. (Mexico); Rżysko, W., E-mail: wojtekrzysko@gmail.com; Sokołowski, S., E-mail: stefan.sokolowski@gmail.com [Department for the Modeling of Physico-Chemical Processes, Maria Curie-Skłodowska University, 20-031 Lublin (Poland); Sokołowska, Z., E-mail: sokolows@ipan.lublin.pl [Institute of Agrophysics, Polish Academy of Sciences, Doś wiadczalna 4, 20-290 Lublin (Poland)

    2015-04-28

    We investigate microscopic structure and thermodynamic properties of a mixture that contains amphiphilic molecules and charged hard spheres confined in slit-like pores with uncharged hard walls. The model and the density functional approach are the same as described in details in our previous work [Pizio et al., J. Chem. Phys. 140, 174706 (2014)]. Our principal focus is in exploring the effects brought by the presence of ions on the structure of confined amphiphilic particles. We have found that for some cases of anisotropic interactions, the change of the structure of confined fluids occurs via the first-order transitions. Moreover, if anions and cations are attracted by different hemispheres of amphiphiles, a charge at the walls appears at the zero value of the wall electrostatic potential. For a given thermodynamic state, this charge is an oscillating function of the pore width.

  17. Amphiphile regulation of ion channel function by changes in the bilayer spring constant

    DEFF Research Database (Denmark)

    Lundbæk, Jens August; Koeppe, R.E.; Andersen, Oluf Sten

    2010-01-01

    predicted from measurements of isolated changes in such properties. Thus, the bilayer contribution to the promiscuous regulation of membrane proteins by drugs and other amphiphiles remains unknown. To overcome this problem, we use gramicidin A (gA) channels as molecular force probes to measure the net...... altering the energetic cost (Delta G(bilayer)) of bilayer deformations associated with protein conformational changes that involve the protein-bilayer interface. But amphiphiles have complex effects on the physical properties of lipid bilayers, meaning that the net change in Delta G(bilayer) cannot be......-dependent sodium channels in living cells. The use of gA channels as molecular force probes provides a tool for quantitative, predictive studies of bilayer-mediated regulation of membrane protein function by amphiphiles....

  18. Biomimetic Self-Templated Hierarchical Structures of Collagen-Like Peptide Amphiphiles.

    Science.gov (United States)

    Jin, Hyo-Eon; Jang, Jaein; Chung, Jinhyo; Lee, Hee Jung; Wang, Eddie; Lee, Seung-Wuk; Chung, Woo-Jae

    2015-10-14

    Developing hierarchically structured biomaterials with tunable chemical and physical properties like those found in nature is critically important to regenerative medicine and studies on tissue morphogenesis. Despite advances in materials synthesis and assembly processes, our ability to control hierarchical assembly using fibrillar biomolecules remains limited. Here, we developed a bioinspired approach to create collagen-like materials through directed evolutionary screening and directed self-assembly. We first synthesized peptide amphiphiles by coupling phage display-identified collagen-like peptides to long-chain fatty acids. We then assembled the amphiphiles into diverse, hierarchically organized, nanofibrous structures using directed self-assembly based on liquid crystal flow and its controlled deposition. The resulting structures sustained and directed the growth of bone cells and hydroxyapatite biominerals. We believe these self-assembling collagen-like amphiphiles could prove useful in the structural design of tissue regenerating materials. PMID:26392232

  19. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

    Science.gov (United States)

    Mazzaglia, Antonino; Ganazzoli, Fabio

    2015-01-01

    Summary Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a “bottom up” approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD), which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties. PMID:26734094

  20. Nanoaggregates of biodegradable amphiphilic random polycations for delivering water-insoluble drugs.

    Science.gov (United States)

    Nottelet, Benjamin; Patterer, Manuela; François, Benjamin; Schott, Marc-Alexandre; Domurado, Martine; Garric, Xavier; Domurado, Dominique; Coudane, Jean

    2012-05-14

    Cationic amphiphilic random copolyesters were obtained by copolymerization of 5-Z-amino-δ-valerolactone and ε-caprolactone. The amino content of the final copolymers was controlled by the polymerization feed ratio and was in the range 10 to 100%. Copolymers solubility and aggregation behavior was assessed by conductometric and zeta potential analyses. A critical aggregation concentration of ca. 0.05% (w/v) was found for all water-soluble copolymers that formed nanoaggregates. Two populations were found to be present in equilibrium with hydrodynamic diameters in the range of 30-50 and 100-250 nm. The capacity to use the amphiphilic and cationic character of the nanoaggregates to encapsulate highly hydrophobic compounds was further investigated. Finally, copolymers hemo- and cytocompatibility were evaluated by hemagglutination, hemolysis, and cells proliferation tests. The results showed that the proposed cationic amphiphilic random copolyesters are biocompatible. PMID:22458377

  1. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles

    International Nuclear Information System (INIS)

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n′) motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n′-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings

  2. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hung-Yu; Sheng, Yu-Jane, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan (China); Tu, Sheng-Hung [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan (China); Tsao, Heng-Kwong, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical and Materials Engineering and Department of Physics, National Central University, Jhongli 320, Taiwan (China)

    2014-08-07

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n{sup ′}) motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n{sup ′}-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings.

  3. Self-assembly mechanisms of nanofibers from peptide amphiphiles in solution and on substrate surfaces

    Science.gov (United States)

    Liao, Hsien-Shun; Lin, Jing; Liu, Yang; Huang, Peng; Jin, Albert; Chen, Xiaoyuan

    2016-08-01

    We report the investigation of the self-assembly mechanism of nanofibers, using a small peptide amphiphile (NapFFKYp) as a model. Combining experimental and simulation methods, we identify the self-assembly pathways in the solution and on the substrates, respectively. In the solution, peptide amphiphiles undergo the nucleation process to grow into nanofibers. The nanofibers can further twist into high-ordered nanofibers with aging. On the substrates, peptide amphiphiles form nanofibers and nanosheet structures simultaneously. This surface-induced nanosheet consists of rod-like structures, and its thickness is substrate-dependent. Most intriguingly, water can transform the nanosheet into the nanofiber. Molecular dynamic simulation suggests that hydrophobic and ion-ion interactions are dominant forces during the self-assembly process.We report the investigation of the self-assembly mechanism of nanofibers, using a small peptide amphiphile (NapFFKYp) as a model. Combining experimental and simulation methods, we identify the self-assembly pathways in the solution and on the substrates, respectively. In the solution, peptide amphiphiles undergo the nucleation process to grow into nanofibers. The nanofibers can further twist into high-ordered nanofibers with aging. On the substrates, peptide amphiphiles form nanofibers and nanosheet structures simultaneously. This surface-induced nanosheet consists of rod-like structures, and its thickness is substrate-dependent. Most intriguingly, water can transform the nanosheet into the nanofiber. Molecular dynamic simulation suggests that hydrophobic and ion-ion interactions are dominant forces during the self-assembly process. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr04672j

  4. Significance of CO2 donor on the production of succinic acid by Actinobacillus succinogenes ATCC 55618

    OpenAIRE

    Zou Wei; Zhu Li-Wen; Li Hong-Mei; Tang Ya-Jie

    2011-01-01

    Abstract Background Succinic acid is a building-block chemical which could be used as the precursor of many industrial products. The dissolved CO2 concentration in the fermentation broth could strongly regulate the metabolic flux of carbon and the activity of phosphoenolpyruvate (PEP) carboxykinase, which are the important committed steps for the biosynthesis of succinic acid by Actinobacillus succinogenes. Previous reports showed that succinic acid production could be promoted by regulating ...

  5. Gold Nanoparticles Protected with Thiol-Derivatized Amphiphilic Poly( -caprolactone)-b-poly(acrylic acid)

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Hvilsted, Søren

    2008-01-01

    Amphiphilic poly(c-caprolactone)-b-poly(acrylic acid) (HS-PCL-b-PAA) bearing thiol functionality at the PCL terminal has been synthesized by a combination of ring-opening polymerization (ROP) of c-caprolactone (c-CL), esterification of hydroxy chain end with protected mercaptoacetic acid, subsequ......Amphiphilic poly(c-caprolactone)-b-poly(acrylic acid) (HS-PCL-b-PAA) bearing thiol functionality at the PCL terminal has been synthesized by a combination of ring-opening polymerization (ROP) of c-caprolactone (c-CL), esterification of hydroxy chain end with protected mercaptoacetic acid...

  6. Model-driven in Silico glpC Gene Knockout Predicts Increased Succinate Production from Glycerol in Escherichia Coli

    Directory of Open Access Journals (Sweden)

    Bashir Sajo Mienda

    2015-04-01

    Full Text Available Metabolic engineered targeting for increased succinate production in Escherichia coli using glycerol as a low cost carbon source has attracted global attention in recent years. Succinate production in engineered E. coli has progressed significantly using an experimental trial and error approach. The use of a model-guided, targeted metabolic gene knockout prediction for increased succinate production from glycerol under anaerobic conditions in E. coli still remains largely underexplored. In this study, we applied a model-driven, targeted glpC/b2243 in silico metabolic gene knockout using E. coli genome scale model iJO1366 under the OptFlux software platform with the aim of predicting high succinate flux. The results indicated that the mutant model lacking the glpC/b2243 gene will demonstrate increased succinate flux that is 30% higher than its wild-type control model. We can hypothesize that an additional NADH molecule was generated following the deletion of the gene and/or the alternatively preferred GldA-DhaKLM fermentative route for glycerol metabolism in E. coli may have been activated. Although the exact metabolic mechanism involved in increasing the succinate flux still remains obscure; the current study informs other studies that a model-driven, metabolic glpC/b2243 gene knockout could be applicable in filling our knowledge gap using a comprehensive experimental inquiry in the future; leading to a better understanding of the underlying metabolic function of this gene in relation to succinate production in E. coli from glycerol.

  7. Amphiphilic semi-interpenetrating polymer networks using pulverized rubber

    Science.gov (United States)

    Shahidi, Nima

    Scrap rubber materials provide a significant challenge to either reuse or safe disposal. Every year, millions of tires are discarded to landfills in the United States, consuming a staggering amount of land space, creating a high risk for large fires, breeding mosquitoes that spread diseases, and wasting the planet's natural resources. This situation cannot be sustained. The challenge of reusing scrap rubber materials is mainly due to the crosslinked structure of vulcanized rubber that prevent them from melting and further processing for reuse. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. The production of fine rubber particles is generally accomplished through the use of a cryogenic process that is costly. Therefore, development of a cost effective technology that utilizes a large quantity of the scrap rubber materials to produce high value added materials is an essential element in maintaining a sustainable solution to rubber recycling. In this research, a cost effective pulverization process, solid state shear extrusion (SSSE), was modified and used for continuous pulverization of the rubber into fine particles. In the modified SSSE process, pulverization takes place at high compressive shear forces and a controlled temperature. Furthermore, an innovative particle modification process was developed to enhance the chemical structure and surface properties of the rubber particles for manufacturing of high value added products. Modification of rubber particles was accomplished through the polymerization of a hydrophilic monomer mixture within the intermolecular structure of the hydrophobic rubber particles. The resulting composite particles are considered as amphiphilic particulate phase semi-interpenetrating polymer networks (PPSIPNs). The modified rubber particles are water dispersible and suitable for use in a variety of aqueous media

  8. Neurobioactive peptide amphiphile nanofiber scaffolds for spinal cord repair

    Science.gov (United States)

    Niece, Krista Lynne

    This thesis describes a set of peptide amphiphiles (PAs) designed for spinal cord repair (SCI). These PAs self: assemble under physiological conditions into nanofibers that cause macroscopic gelation. Hydrogen bonding, hydrophobicity, and electrostatics, which control the self-assembly, are compared throughout this thesis. PA performance is explored from a materials science and a bioengineering perspective. The salt-triggered gelation of three PAs with similar charge distributions, each bearing the neurite-outgrowth-promoting laminin-1 epitope IKVAV, is studied by rheology in Chapter 2. Stiffer, more hydrophilic PAs gel more slowly, as verified by testing analogous PAs bearing the fibronectin epitope RGD. Circular dichroism (CD) and turbidity suggest a nucleated self-assembly mechanism that depends on preexisting aggregates. Slowing gelation assists PA injection into the mouse spinal cord. Mouse neural progenitor cell (mNPC) studies with the IKVAV-PAs show cell survival, neurite outgrowth and selective neuronal differentiation, which may improve SCI repair by preventing glial scarring. Two PAs containing another laminin-1 epitope, YIGSR, are described in Chapter 3. In a negatively charged YIGSR-bearing PA (YIGSR-PA), mNPCs behave as in the IKVAV-bearing PAs, but grow longer neurites possibly due to epitope signaling. A positively charged YIGSR-bearing PA (Pos-YIGSR-PA) does not support mNPC survival. P19 cell line studies and zeta-potential measurements show that cell death is due to the PA substrate's surface charge and is specific to mNPCs. Mixed IKVAV-PA/YIGSR-PA scaffolds show averaging of cell behavior, while IKVAV-PA/Pos-YIGSR-PA mixtures fail to rescue cell viability. These dual-epitope scaffolds are studied in Chapter 4 by nuclear magnetic resonance (NMR) and CD. The like-charged mixture is composed of single-component fibers forming an interpenetrating network (IPN). The oppositely charged mixture is composed of mixed fibers, as predicted from simulation

  9. Resilient self-assembling hydrogels from block copolypeptide amphiphiles

    Science.gov (United States)

    Nowak, Andrew Paul

    The ability to produce well defined synthetic polypeptides has been greatly improved by the discovery of transition metal species that mediate the controlled polymerization of N-carboxyanhydrides (NCAs). These metal species create a living polymerization system by producing control over chain length, low polydispersities, and the ability to form complex block architectures. We have applied this system to the synthesis of block copolypeptide amphiphiles. Initial block copolymers synthesized were composed of hydrophilic, cationic poly(L-Lysine) combined with hydrophobic, alpha-helical poly(L-Leucine). These Lysine- block-Leucine copolypeptides were found to form stiff, clear hydrogels at low concentration (˜1 wt%) in low ionic strength water. Based on this unexpected result we used the flexibility of our transition metal polymerization chemistry to better understand the nature and mechanisms of gel formation in these materials. Systematic changes to the original Lysine-block-Leucine copolypeptides were made by altering overall chain size, relative block length, polyelectrolyte charge, and hydrophobic secondary structure. Rheological characterization revealed that the strength of these hydrogels was primarily dependent on degree of polymerization, relative block length, and a well ordered secondary structure in the hydrophobic segment. The Lysine-block-Leucine hydrogels were formed by direct addition of water to dry polypeptide material which swelled to homogeneously fill the entire volume of liquid with no special processing. CryoTEM showed a percolating cellular network at ˜100nm that appears to be comprised of both membranes and fibers. Larger length scales studied with Laser Scanning Confocal Microscopy revealed a spontaneously formed microporous network with large (˜10mum) water rich voids. These hydrogels also displayed interesting mechanical properties including rapid recovery of solid like behavior after being sheared to a liquid and mechanical stability

  10. Preparation and performance of hydroxypropyl methylcellulose esters of substituted succinates for in vitro supersaturation of a crystalline hydrophobic drug.

    Science.gov (United States)

    Yin, Ligeng; Hillmyer, Marc A

    2014-01-01

    We prepared hydroxypropyl methylcellulose (HPMC) esters of substituted succinates and examined their performance for improving the aqueous solubility of crystalline hydrophobic drugs in spray-dried dispersions (SDDs). From one HPMC, we synthesized five HPMC esters using various monosubstituted succinic anhydrides. These HPMC esters along with a commercial HPMC acetate succinate (HPMCAS) were spray-dried from solutions with phenytoin. The SDDs with different matrices at 10 wt % loading had very similar bulk properties with a minimal amount of detectable crystalline phenytoin as revealed by scanning electron microscopy (SEM), powder X-ray diffraction (powder XRD), and differential scanning calorimetry (DSC). In solution, while the SDD with HPMCAS was very effective at achieving high levels of phenytoin supersaturation initially, it was not competent at maintaining such supersaturation due to the rapid crystallization of the dissolved phenytoin. Alternatively, SDDs with several synthesized HPMC esters of substituted succinates not only achieved rather high initial supersaturation but also maintained high concentrations for extended time (i.e., 1.5 h and longer). Such maintenance was largely ascribed to the inhibition of phenytoin nucleation. Structure-property relationships were established, and the most successful systems contained a high degree of substitution and a combination of a thioether with neighboring weak electron-withdrawing groups in the substituted succinic anhydrides. The effective maintenance of supersaturated solutions was only found in SDDs with rather low drug loadings, which indicates the significance of sufficiently high concentrations of polymer additives in the dissolution media. PMID:24320108

  11. Performance analyses of a neutralizing agent combination strategy for the production of succinic acid by Actinobacillus succinogenes ATCC 55618.

    Science.gov (United States)

    Wang, Cheng-Cheng; Zhu, Li-Wen; Li, Hong-Mei; Tang, Ya-Jie

    2012-05-01

    A neutralizing agent combination strategy was developed to enhance the succinic acid production by Actinobacillus succinogenes ATCC 55618. First, a maximal succinic acid production of 48.2 g/L was obtained at a culture pH of 7.5. Second, NaOH and KOH were screened to identify the optimal neutralizing agent for pH control. However, the production of succinic acid did not increase, and severe cell flocculation was observed due to a high concentration of metal ions when only one neutralizing agent was used to control pH. Finally, a neutralizing agent combination strategy was developed with a supply of neutralizing agents with OH(-) and carbonate. The cell flocculation was eliminated, and a maximum succinic acid production of 59.2 g/L was obtained with 5 M NaOH and 40 g/L of MgCO(3); this production was 27.9% higher than that obtained with NaOH alone. The results obtained in this study may be useful for the large-scale industrial production of succinic acid. PMID:22002101

  12. Cytoplasm-to-myonucleus ratios and succinate dehydrogenase activities in adult rat slow and fast muscle fibers

    Science.gov (United States)

    Tseng, B. S.; Kasper, C. E.; Edgerton, V. R.

    1994-01-01

    The relationship between myonuclear number, cellular size, succinate dehydrogenase activity, and myosin type was examined in single fiber segments (n = 54; 9 +/- 3 mm long) mechanically dissected from soleus and plantaris muscles of adult rats. One end of each fiber segment was stained for DNA before quantitative photometric analysis of succinate dehydrogenase activity; the other end was double immunolabeled with fast and slow myosin heavy chain monoclonal antibodies. Mean +/- S.D. cytoplasmic volume/myonucleus ratio was higher in fast and slow plantaris fibers (112 +/- 69 vs. 34 +/- 21 x 10(3) microns3) than fast and slow soleus fibers (40 +/- 20 vs. 30 +/- 14 x 10(3) microns3), respectively. Slow fibers always had small volumes/myonucleus, regardless of fiber diameter, succinate dehydrogenase activity, or muscle of origin. In contrast, smaller diameter (fibers with high succinate dehydrogenase activity appeared to have low volumes/myonucleus while larger diameter (> 70 microns) fast fibers with low succinate dehydrogenase activity always had large volume/myonucleus. Slow soleus fibers had significantly greater numbers of myonuclei/mm than did either fast soleus or fast plantaris fibers (116 +/- 51 vs. 55 +/- 22 and 44 +/- 23), respectively. These data suggest that the myonuclear domain is more limited in slow than fast fibers and in the fibers with a high, compared to a low, oxidative metabolic capability.

  13. DEVELOPMENT AND VALIDATION OF HPTLC METHOD FOR SIMULTANEOUS DETERMINATION OF METOPROLOL SUCCINATE AND ATORVASTATIN CALCIUM IN A PHARMACEUTICAL DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    Ginoya Charmi G.

    2013-02-01

    Full Text Available A new, simple, precise, accurate and selective high performance thin-layer chromatographic (HPTLC method has been developed and validated for the simultaneous determination of Metoprolol succinate and Atorvastatin calcium in a marketed formulation. Chromatographic separation was carried out on Merck TLC aluminium sheets of silica gel 60F254 using Acetonitrile: Methanol: Ethyl acetate: Glacial acetic acid (2: 4: 4: 0.06 % v/v/v/v as mobile phase followed by densitometric analysis at 223 nm. This system was found to give compact spots for Metoprolol succinate (Rf value of 0.32 ± 0.005 and Atorvastatin calcium (Rf value of 0.77 ± 0.004. The method was validated in terms of linearity, accuracy, precision, limit of detection, limit of quantification and specificity in accordance with International Conference on Harmonization (ICH guidelines. The calibration curve was found to be linear between 500 to 3000 and 200 to 1200 ng/spot for Metoprolol succinate and Atorvastatin calcium, respectively with significantly high value of correlation coefficient (r2 > 0.99. The limits of detection and quantitation were found to be 0.8432 and 2.5553 ng/spot, respectively for Metoprolol succinate and 27.8428 and 84.3662 ng/spot, respectively for Atorvastatin calcium. The proposed method was found to be accurate, precise, reproducible, specific and sensitive and can be applicable for the simultaneous determination of Metoprolol succinate and Atorvastatin calcium in marketed formulation.

  14. Equilibrium of Extraction of Succinic,Malic,Maleic and Fumaric Acids with Trioctylamine

    Institute of Scientific and Technical Information of China (English)

    LIZhenyu; QINWei; 等

    2002-01-01

    Extraction equilibrium features of succinic acid,malic acid,maleic acid and fumaric acid were investigated systematically with trioctylamine (TOA) in chloroform,4-methyl-2-pentanone (MIBK) and 1-octanol.Fourier transform-infrared(FTIR) spectroscopic analysis of organic samples loaded with the acid show that amine forms 1:1 complex of ion-pair association with succinic acid,malic acid and maleic acid,and 1:1,2:1 complex of ion-pair association with fumaric acid.It is proposed that the complex forms depend on the second dissociation constant of the dibasic acid,pKa2.Results of equilibrium experiments show that diluents affects extraction behavior,and depend on the solute concentration.Protic diluents,chloroform and 1-octanol,are more effective than the others when the equilibrium solute concentration.Protic diluents,chloroform and 1-octanol,are more effective tthan the others when the equilibrium solute concentration is lower than 1:1 stoichiometry of TOA to acid,otherwise the extraction ability shows that MIBK>1-octanol>chloroform for malic and maleic acids,and 1-octanol>MIBK>chloroform for succinic acid.Overloading(Solute concentration in organic phase is lager than TOA concentration) appears for all of the studied acids, and the sequence of overloading amount is the same as that of distribution constant of diluent.The results show that the sequence of extraction ability of different acid is the same as that of acidity at low equilibrium solute concentrations,while it is the same as the sequence of hydrophobicity at high equilibrium concentrations.

  15. PARTITION-OPTIMIZED SINGLE EMULSION PARTICLES IMPROVE SUSTAINED RELEASE OF AMPHIPHILIC BUMPED KINASE INHIBITORS TO CONTROL MALARIA TRANSMISSION

    Directory of Open Access Journals (Sweden)

    Christina Yacoob

    2015-11-01

    Full Text Available Amphiphilic molecules are challenging to be incorporatedinto polymeric particles for sustained release due to their significant solubility in both water and organic solvent used in the fabrication process. Here, we investigated an extensive panel of fabrication methods for the incorporation and release of amphiphilic molecules, in particular, novel amphiphilic bumped kinase inhibitors (BKIs. Previously, BKIswere shown to reduce malaria transmission by blocking of gametocyte exflagellation. Prolonged BKI bioavailability for effective transmission blocking is crucial since infectious gametocytes circulate for several weeks inthe mammalian host, well beyond the half-life of BKIs. So far, delivery systems for sustained release of those BKIs have not been successfully formulated yet. Here we demonstrate that out of several delivery vehicles the partition-optimized single emulsion particles are the ideal system for incorporation and sustained release of amphiphilic BKIs. They increased the incorporation greater than 90% through optimized partitioning of amphiphilic molecules to the polymer phase and sustained release of BKIs up to several weeks with a reduction in the initial burst release. Overall this work provides a method for the incorporation and sustained release of amphiphilic BKIs, and can be adapted for other amphiphilic molecules.

  16. Preparation of Vesicles and Nanoparticles of Amphiphilic Cyclodextrins Containing Labile Disulfide Bonds

    NARCIS (Netherlands)

    Nolan, Darren; Darcy, Raphael; Ravoo, Bart Jan

    2003-01-01

    Amphiphilic cyclodextrin derivatives were prepared in which a disulfide bond connects the hydrophobic substituents to the macrocycle. These compounds were obtained by 1,3-dicyclohexylcarbodiimide-mediated coupling reactions of heptakis(6-amino-6-deoxy)-B-cyclodextrins and disulfide-containing carbox

  17. Bilayer vesicles of amphiphilic cyclodextrines: host membranes that recognize guest molecules

    NARCIS (Netherlands)

    Falvey, P.; Lim, C.W.; Darcy, R.; Revermann, T.; Karst, U.; Marcelis, A.T.M.; Coleman, A.W.; Reinhoudt, D.N.; Ravoo, B.J.

    2005-01-01

    A family of amphiphilic cyclodextrins (6, 7) has been prepared through 6-S-alkylation (alkyl=n-dodecyl and n-hexadecyl) of the primary side and 2-O-PEGylation of the secondary side of alpha-, beta-, and gamma-cyclodextrins (PEG=poly(ethylene glycol)). These cyclodextrins form nonionic bilayer vesicl

  18. Unimolecular micelles of amphiphilic cyclodextrin-core star-like block copolymers for anticancer drug delivery.

    Science.gov (United States)

    Xu, Zhigang; Liu, Shiying; Liu, Hui; Yang, Cangjie; Kang, Yuejun; Wang, Mingfeng

    2015-11-11

    Well-defined star-like amphiphilic polymers composed of a β-cyclodextrin core, from which 21 hydrophobic poly(lactic acid) arms and hydrophilic poly(ethylene glycol) arms are grafted sequentially, form robust and uniform unimolecular micelles that are biocompatible and efficient in the delivery of anticancer drugs. PMID:26121632

  19. Bilayer Vesicles of Amphiphilic Cyclodextrins: Host Membranes That Recognize Guest Molecules

    NARCIS (Netherlands)

    Falvey, Patrick; Lim, Choon Woo; Darcy, Raphael; Revermann, Tobias; Karst, Uwe; Giesbers, Marcel; Marcelis, Antonius T.M.; Lazar, Adina; Coleman, Anthony W.; Reinhoudt, David N.; Ravoo, Bart Jan

    2005-01-01

    A family of amphiphilic cyclodextrins (6, 7) has been prepared through 6-S-alkylation (alkyl=n-dodecyl and n-hexadecyl) of the primary side and 2-O-PEGylation of the secondary side of a-, B-, and Y-cyclodextrins (PEG=poly(ethylene glycol)). These cyclodextrins form nonionic bilayer vesicles in aqueo

  20. New carbon-carbon linked amphiphilic carboranyl-porphyrins as boron neutron capture agents

    International Nuclear Information System (INIS)

    Novel amphiphilic carboranyl-porphyrins have been synthesized for Boron Neutron Capture Therapy (BNCT). These compounds have carbon-carbon bonds between the carborane residues and the porphyrin meso-phenyl groups, and contain 28-31% boron by weight . (author)

  1. Tunable Hydrophobicity in DNA Micelles : Design, Synthesis, and Characterization of a New Family of DNA Amphiphiles

    NARCIS (Netherlands)

    Anaya, Milena; Kwak, Minseok; Musser, Andrew J.; Muellen, Klaus; Herrmann, Andreas; Müllen, Klaus

    2010-01-01

    This work describes the synthesis and characterization of a new family of DNA amphiphiles containing modified nucleobases. The hydrophobicity was imparted by the introduction of a dodec-1-yne chain at the 5-position of the uracil base, which allowed precise and simple tuning of the hydrophobic prope

  2. The encapsulation of an amphiphile into polystyrene microspheres of narrow size distribution

    Directory of Open Access Journals (Sweden)

    Pellach Michal

    2011-12-01

    Full Text Available Abstract Encapsulation of compounds into nano- or microsized organic particles of narrow size distribution is of increasing importance in fields of advanced imaging and diagnostic techniques and drug delivery systems. The main technology currently used for encapsulation of molecules within uniform template particles while retaining their size distribution is based on particle swelling methodology, involving penetration of emulsion droplets into the particles. The swelling method, however, is efficient for encapsulation only of hydrophobic compounds within hydrophobic template particles. In order to be encapsulated, the molecules must favor the hydrophobic phase of an organic/aqueous biphasic system, which is not easily achieved for molecules of amphiphilic character. The following work overcomes this difficulty by presenting a new method for encapsulation of amphiphilic molecules within uniform hydrophobic particles. We use hydrogen bonding of acid and base, combined with a pseudo salting out effect, for the entrapment of the amphiphile in the organic phase of a biphasic system. Following the entrapment in the organic phase, we demonstrated, using fluorescein and (antibiotic tetracycline as model molecules, that the swelling method usually used only for hydrophobes can be expanded and applied to amphiphilic molecules.

  3. Photostability of quantum dots with amphiphilic polymer-based passivation strategies

    International Nuclear Information System (INIS)

    Quantum dots (QDs) have many appealing properties for biological fluorescence imaging, but exhibit photostabilities that are dependent upon surface passivation to minimize susceptibility to oxygen and light. Here, through spectroscopy and imaging techniques, we compare the photostability of micelle-encapsulated QDs with QDs passivated with either crosslinked amphiphilic polymers or crosslink-free amphiphilic polymers. Both crosslinked and crosslink-free amphiphilic polymer passivation strategies produced QDs with high photoluminescence stability for exposure to light under ambient conditions. In contrast, micelle encapsulation resulted in QDs with photoluminescence emission levels that were highly sensitive to both light exposure and oxygen, exhibiting a reduction of up to 70% in photoluminescence intensity within twenty minutes of exposure. With the addition of reducing agents, the photoluminescence level of the micelle-encapsulated QDs was significantly stabilized. We conclude that amphiphilic polymers provide coatings with considerably higher integrity and stability than micelle encapsulation, reducing the QDs' sensitivities to oxygen and light, both of which are relevant factors in biological imaging applications

  4. Gold Nanoparticles Protected with Thiol-Derivatized Amphiphilic Poly(epsilon-caprolactone)-b-poly(acrylic acid)

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Hvilsted, Søren

    2009-01-01

    Amphiphilic poly(epsilon-caprolactone)-b-poly(acrylic acid) (HS-PCL-b-PAA) with a thiol functionality in the PCL terminal has been prepared in a novel synthetic cascade. Initially, living anionic ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) employing the difunctional...

  5. Anti-Biofouling Properties of Comblike Block Copolymers with Amphiphilic Side Chains

    International Nuclear Information System (INIS)

    Surfaces of novel block copolymers with amphiphilic side chains were studied for their ability to influence the adhesion of marine organisms. The surface-active polymer, obtained by grafting fluorinated molecules with hydrophobic and hydrophilic blocks to a block copolymer precursor, showed interesting bioadhesion properties. Two different algal species, one of which adhered strongly to hydrophobic surfaces, and the other, to hydrophilic surfaces, showed notably weak adhesion to the amphiphilic surfaces. Both organisms are known to secrete adhesive macromolecules, with apparently different wetting characteristics, to attach to underwater surfaces. The ability of the amphiphilic surface to undergo an environment-dependent transformation in surface chemistry when in contact with the extracellular polymeric substances is a possible reason for its antifouling nature. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) was used, in a new approach based on angle-resolved X-ray photoelectron spectroscopy (XPS), to determine the variation in chemical composition within the top few nanometers of the surface and also to study the surface segregation of the amphiphilic block. A mathematical model to extract depth-profile information from the normalized NEXAFS partial electron yield is developed

  6. Stimuli-responsive nano-structures of amphiphilic ionic block- and gradient copolymers

    Czech Academy of Sciences Publication Activity Database

    Borisov, O.; Billon, L.; Borisova, O.; Štěpánek, Petr; Bakaeva, Zulfiya; Zhulina, E.

    Prague : Institute of Macromolecular Chemistry AS CR, 2014. s. 179. ISBN 978-80-85009-80-4. [Frontiers of Polymer Colloids: From Synthesis to Macro-Scale and Nano-Scale Applications. Prague Meeting on Macromolecules /78./. 20.07.2014-24.07.2014, Prague] Institutional support: RVO:61389013 Keywords : amphiphilic ionic copolymers * gradient copolymers Subject RIV: CD - Macromolecular Chemistry

  7. Synthesis, Characterization, and Aqueous Lubricating Properties of Amphiphilic Graft Copolymers Comprising 2-Methoxyethyl Acrylate

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Røn, Troels; Jankova Atanasova, Katja; Hvilsted, Søren; Lee, Seunghwan

    2014-01-01

    Amphiphilic anionic and cationic graft copolymers possessing poly(2-hydroxyethyl methacrylate) (PHEMA) backbone and poly(methacrylic acid), poly(2-methoxyethyl acrylate-co-methacrylic acid), and poly(2-methoxyethyl acrylate-co-2-(dimethylamino)ethyl methacrylate) grafts are constructed by merging...

  8. Synthesis of Novel Amphiphilic Azobenzenes and X-ray Scattering Studies of Their Langmuir Monolayers

    DEFF Research Database (Denmark)

    Sørensen, Thomas Just; Kjær, Kristian; Breiby, Dag Werner;

    2008-01-01

    air-water interface, the amphiphilic azobenzenes form noncrystalline but stable Langmuir films that display an unusual reversible monolayer collapse close to 35 mN/m. The structures and phase transitions were studied by X-ray reflectivity (XR) and grazing-incidence X-ray diffraction, both utilizing...

  9. Mitochondrially Targeted Vitamin E Succinate Modulates Expression of Mitochondrial DNA Transcripts and Mitochondrial Biogenesis

    Czech Academy of Sciences Publication Activity Database

    Truksa, Jaroslav; Dong, L.F.; Rohlena, Jakub; Stursa, J.; Vondrusová, Magdaléna; Goodwin, J.; Nguyen, M.; Klučková, Katarína; Rychtarčíková, Zuzana; Lettlová, Sandra; Spáčilová, Jana; Stapelberg, M.; Zoratti, M.; Neužil, Jiří

    2015-01-01

    Roč. 22, č. 11 (2015), s. 883-900. ISSN 1523-0864 R&D Projects: GA ČR GAP301/10/1937; GA AV ČR KAN200520703; GA ČR GAP305/12/1708; GA ČR GAP301/12/1851; GA MŠk(CZ) ED1.1.00/02.0109 Institutional research plan: CEZ:AV0Z50520701 Institutional support: RVO:86652036 Keywords : ALPHA-TOCOPHERYL SUCCINATE * ELECTRON-TRANSPORT CHAIN * RESPIRATORY COMPLEX-II Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.407, year: 2014

  10. Evidence of redox imbalance in a patient with succinic semialdehyde dehydrogenase deficiency

    Directory of Open Access Journals (Sweden)

    Anna-Kaisa Niemi

    2014-01-01

    Full Text Available The pathophysiology of succinic semialdehyde dehydrogenase (SSADH deficiency is not completely understood. Oxidative stress, mitochondrial pathology, and low reduced glutathione levels have been demonstrated in mice, but no studies have been reported in humans. We report on a patient with SSADH deficiency in whom we found low levels of blood reduced glutathione (GSH, and elevations of dicarboxylic acids in urine, suggestive of possible redox imbalance and/or mitochondrial dysfunction. Thus, targeting the oxidative stress axis may be a potential therapeutic approach if our findings are confirmed in other patients.

  11. Polarographic study of dioxo-uranium(VI)-8-hydroxyquinoline-succinate system and thermodynamic parameters

    International Nuclear Information System (INIS)

    The dioxo-uranium(VI)-8-hydroxyquinoline-succinate system has been studied polarographically at constant ionic strength (μ = 0.6 M KCl) in aqueous alcohol (7:3) at different temperatures. The reduction of the simple and mixed complexes is reversible and diffusion controlled. The DeFord-Hume and Schaap-McMaster methods have been applied in the determination of composition and stability constants of the simple and mixed complexes respectively. The thermodynamic parameters ΔG, ΔH and ΔS have also been calculated. (author)

  12. Ercella succinigenes gen. nov., sp. nov., ananaerobic succinate-producing bacterium

    OpenAIRE

    Van Gelder, A.H.; Sousa, D.Z.; Rijpstra, W.I.C.; J. S. Sinninghe Damsté; Stams, A. J. M.; Sánchez-Andrea, I.

    2014-01-01

    A novel anaerobic succinate-producing bacterium, strain ZWBT, was isolated from sludge collected from a biogas desulfurization bioreactor (Eerbeek, The Netherlands). Cells were non-spore forming, motile, slightly curved rods (0.4 to 0.5 µm in diameter and 2 to 3 µm in length), and stained Gram-negative. The temperature range for growth was 25 to 40°C, with an optimum at 37°C. The pH range for growth was 7.0 to 9.0, with an optimum at pH 7.5. Strain ZWBT ferments glycerol and several carbohydr...

  13. Analysis of Gas Permeability Characteristics of Poly(Lactic Acid)/Poly(Butylene Succinate) Nanocomposites

    OpenAIRE

    Amita Bhatia; Rahul K Gupta; Bhattacharya, Sati N.; Hyoung Jin Choi

    2012-01-01

    Gas permeability and morphological properties of nanocomposites prepared by the mixing of poly(lactic acid) (PLA), poly(butylene succinate) (PBS), and clay was investigated. While the composition of PLA and PBS polymers was fixed as 80% and 20% by weight, respectively, for all the nanocomposites, clay contents varied from 1 to 10 wt%. From the morphological studies using both wide angle X-ray diffraction and transmission electron microscopy, the nanocomposite having 1 wt% of clay was consider...

  14. Challenges in Catalytic Manufacture of Renewable Pyrrolidinones from Fermentation Derived Succinate

    Energy Technology Data Exchange (ETDEWEB)

    White, James F.; Holladay, Johnathan E.; Zacher, Alan H.; Frye, John G.; Werpy, Todd A.

    2014-09-05

    Fermentation derived succinic acid ammonium salt is an ideal precursor for manufacture of renewable N-methyl pyrrolidinone (NMP) or 2-pyrrolidinone (2P) via heterogeneous catalysis. However, there are many challenges to making this a practical reality. Chief among the challenges is avoiding catalyst poisoning by fermentation by- and co-products. Battelle / Pacific Northwest National Laboratory (PNNL) have developed an economically effective technology strategy for this purpose. The technology is a combination of purely thermal processing, followed by simple catalytic hydrogenation that together avoids catalyst poisoning from fermentation impurities and provides high selectivity and yields of NMP or 2P.

  15. Structural properties of aqueous metoprolol succinate solutions. Density, viscosity, and refractive index at 311 K

    Science.gov (United States)

    Deosarkar, S. D.; Kalyankar, T. M.

    2013-06-01

    Density, viscosity and refractive index of aqueous solutions of metoprolol succinate of different concentrations (0.005-0.05 mol dm-3) were measured at 38°C. Apparent molar volume of resultant solutions were calculated and fitted to the Masson's equation and apparent molar volume at infinite dilution was determined graphically. Viscosity data of solutions has been fitted to the Jone-Dole equation and viscosity A- and B-coefficients were determined graphically. Physicochemical data obtained were discussed in terms of molecular interactions.

  16. EFFECT OF PROCESSING AND POLYMER VARIABLES ON INVITRO RELEASE OF METOPROLOL SUCCINATE EXTENDED RELEASE TABLETS

    OpenAIRE

    N. N. Rajendran et al.

    2011-01-01

    The present study was aimed to develop an extended release tablet of Metoprolol Succinate for the treatment of hypertension. Four extended release formulations F1-F4 were developed using varying proportions of Hydroxyl propyl methyl cellulose K100M, Sodium carboxy methyl cellulose and Eudragit L30 D55 by wet granulation. Five extended release formulations F5-F9 containing HPMC K100M and HPMC 5cps in varying concentration were developed by direct compression. The physico-chemical and in-vitro...

  17. POLYSACCHARIDE GUM (KONDAGOGU GUM) MATRIX TABLETS FOR ORAL SUSTAINED DELIVERY OF METOPROLOL SUCCINATE

    OpenAIRE

    N. Aswani; Vinay, S.; T. M. Pramod Kumar; Valluru Ravi; N Srujana

    2011-01-01

    The present study has been undertaken to develop a sustained-release tablet dosage form for metoprolol succinate using kondagugu gum as the rate-controlling polymer. The prepared tablets were coated will shellac as an enteric coat polymer and evaluated for tablet properties. In vitro release studies of prepared tablets were carried out for 2 hrs in pH 1.2 HCl buffer and 22 hrs in pH 6.8phosphate buffer. In addition, swelling, kinetics of drug release from the matrices and stability of the tab...

  18. Radiation-induced alterations in succinate dehydrogenase activity in the muscle of pigeon

    International Nuclear Information System (INIS)

    The histochemical changes in succinate dehydrogenase were investigated in pectoralis major muscle of pigeon exposed to sub-lethal dose (400 rad) of γ-irradiation. Biochemical study was also carried out after 200, 300 and 400 rad of irradiation. In the present study the overall decrease in enzyme activity could be due to the structural and/or functional damage to mitochondria after treatment of pigeon to different sub-lethal doses of γ-irradiation. The significance of these results has been discussed with special reference to oxidative metabolism. (author)

  19. Integrated production of cellulosic bioethanol and succinic acid from industrial hemp in a biorefinery concept

    DEFF Research Database (Denmark)

    Kuglarz, Mariusz; Alvarado-Morales, Merlin; Karakashev, Dimitar Borisov;

    2016-01-01

    The aim of this study was to develop integrated biofuel (cellulosic bioethanol) and biochemical (succinic acid) production from industrial hemp (Cannabis sativa L.) in a biorefinery concept. Two types of pretreatments were studied (dilute-acid and alkaline oxidative method). High cellulose recovery...... (> 95%) as well as significant hemicelluloses solubilization (49-59%) after acid-based method and lignin solubilization (35-41%) after alkaline H2O2 method were registered. Alkaline pretreatment showed to be superior over the acid-based method with respect to the rate of enzymatic hydrolysis and ethanol...

  20. Adsorption of alkenyl succinic anhydride from solutions in carbon tetrachloride on a fine magnetite surface

    Science.gov (United States)

    Balmasova, O. V.; Ramazanova, A. G.; Korolev, V. V.

    2016-06-01

    The adsorption of alkenyl succinic anhydride from a solution in carbon tetrachloride on a fine magnetite surface at a temperature of 298.15 K is studied using fine magnetite, which forms the basis of magnetic fluids, as the adsorbent. An adsorption isotherm is recorded and interpreted in terms of the theory of the volume filling of micropores (TVFM). Adsorption process parameters are calculated on the basis of the isotherm. It is shown that at low equilibrium concentrations, the experimental adsorption isotherm is linear in the TVFM equation coordinates.

  1. Fabrication of Modified Release Tablet Formulation of Metoprolol Succinate using Hydroxypropyl Methylcellulose and Xanthan Gum

    OpenAIRE

    Gohel, Mukesh C.; Parikh, Rajesh K.; Nagori, Stavan A.; Jena, Dillip G.

    2009-01-01

    The present investigation was undertaken to fabricate modified release tablet of metoprolol succinate using hydroxypropyl methylcellulose (HPMC) and xanthan gum as a matrixing agent. A 32 full factorial design was employed for the optimization of formulation. The percentage drug released at a given time (Y60, Y240 and Y720) and the time required for a given percentage of drug to be released (t50%) were selected as dependent variables. The in vitro drug dissolution study was carried out in pH ...

  2. [Age-related Peculiarities of Succinate Effect on Induced Lipid Peroxidation in Rat Liver Mitochondria].

    Science.gov (United States)

    Grishina, E V; Khaustova, Ya V; Vasilieva, A A; Mayevsky, E I

    2015-01-01

    The antioxidant effect of succinate and 3-hydroxybutyrate oxidation on the kinetics of lipid peroxidation induced by ATP-Fe2+ complex in isolated rat liver mitochondria of old (1.0-1.5 years) and young (3 months) male rats was investigated. The rate of induced lipid peroxidation V(LPO) in rat liver mitochondria and the half-time of oxygen consumption Δt50, which included the lag period and the initiation. phase, was recorded polarographically. Without exogenous oxidative-substrates V(LPO) was slightly higher in mitochondria of old animals, but the onset of lipid peroxidation cascade was significantly earlier than in young animals. Incubation of mitochondria with 5mM succinate for 1 min inhibited V(LPO) by 15% in young animals and by 35% in old animals. However, only in mitochondria of old animals Δt50 increased by 19% as compared to lipid peroxidation without substrates. V(LPO) in mitochondria of young animals did not significantly change during 3-hydroxybutyrate oxidation, while in mitochondria of old animals it was reduced by 19% with a slight increase in Δt50. To simulate age-dependent dysfunction we damaged isolated mitochondria by a series of freeze-thaw cycles, which caused a significant increase of V(LPO) of.both age groups. Succinate oxidation inhibited V(LPO) in damaged mitochondria in all cases by 56%, as compared to V(LPO) without oxidative substrates and extended At50 twofold in mitochondria of young animals. Oxidation of 3-hydroxybutyrate had no effect on V(LPO) in damaged mitochondria regardless of animal, age and extended Δt50 by 48% in mitochondria of young animals. Thus, the antioxidant effect of succinate oxidation can prevent lipid peroxidation damage and may exhibit geroprotective action at the level of aging mitochondria. Therefore, the antioxidant effect is due to the process of substrate oxidation in the respiratory chain but not because of an interaction of their structures with membrane lipids per se. PMID:26394470

  3. Extraction and separation of mercury(II from succinate media with high molecular weight amine as an extractant

    Directory of Open Access Journals (Sweden)

    Chandrashekhar P. Mane

    2015-01-01

    Full Text Available The extraction of mercury(II from succinate solutions by 2-octylaminopyridine (2-OAP has been studied by metal distribution measurements. The optimum extraction conditions were determined from a critical study of effects of pH, sodium succinate concentration and 2-octylaminopyridine concentration. The probable composition of the species has been deduced from log–log plots. The extraction reaction proceeds with ion-pair formation and the stoichiometry of extracted species was found to be [(2OAPH+2 Hg(Succinate22−](org. The method has been used to separate mercury(II from commonly associated elements. The method has been further extended to separate and to estimate mercury in synthetic mixtures and real samples.

  4. Enhancing the protein resistance of silicone via surface-restructuring PEO-silane amphiphiles with variable PEO length

    OpenAIRE

    Rufin, M. A.; Gruetzner, J. A.; Hurley, M. J.; Hawkins, M. L.; Raymond, E. S.; Raymond, J. E.; Grunlan, M. A.

    2015-01-01

    Silicones with superior protein resistance were produced by bulk-modification with poly(ethylene oxide) (PEO)-silane amphiphiles that demonstrated a higher capacity to restructure to the surface-water interface versus conventional non-amphiphilic PEO-silanes. The PEO-silane amphiphiles were prepared with a single siloxane tether length but variable PEO segment lengths: α-(EtO)3Si(CH2)2-oligodimethylsiloxane13-block-poly(ethylene oxide)n-OCH3 (n = 3, 8, and 16). Conventional PEO-silane analogu...

  5. NEW ANALYTICAL METHODS AND THEIR VALIDATION FOR THE ESTIMATION OF METOPROLOL SUCCINATE IN BULK AND MARKETED FORMULATION

    Directory of Open Access Journals (Sweden)

    Viral Bechara

    2015-02-01

    Full Text Available Metoprolol succinate is cardiovascular agent. Mainly used for the treatment of hypertension, heart failure, and cardiovascular diseases. Purpose: Analytical methods are required to characterize drug substances and drug products composition during all phases of pharmaceutical development. Development of methods to achieve the final goal of ensuring the quality of drug substances and drug products must be implemented in conjunction with an understanding of the chemical behavior and physicochemical properties of the drug substance. This determination requires highly sophisticated instruments and methods like HPLC, HPTLC and Spectrophotometer. Hence there was a need for the development of newer, simple, sensitive, rapid, accurate and reproducible analytical methods for the routine estimation of metoprolol succinate in bulk and pharmaceutical dosage form. Methods: The present work describes two new spectrophotometric methods for the determination of metoprolol succinate in bulk and marketed formulations. Method A is based on oxidation reaction. Metoprolol succinate in presence of acidic medium reacts with excess amount of chloramine-T and remaining chloramine-T react with malachite green to produce orange colour chromogen which showed λmax at 516 nm. In Method B, the drug was diazotised with sodium nitrite in presence of hydrochloric acid and then it was coupled with β-naphthol in alkaline medium. Which produce red colour chromogen which showed λmax at 688 nm. Results: The linearity was found in concentration range of 5-30μg/ml for both method A and method B. The correlation coefficient was found to be 0.9983 and 0.9993 for method A and method B respectively. The methods were validated as per ICH guidelines. The LOD and LOQ for estimation of Metoprolol succinate were found as 0.0773, 0.2343 for method A and 0.0667, 0.2021 for method B respectively. Conclusion: Proposed methods were successfully applied for the quantitative estimation of

  6. Activation of glyoxylate pathway without the activation of its related gene in succinate-producing engineered Escherichia coli.

    Science.gov (United States)

    Zhu, Li-Wen; Li, Xiao-Hong; Zhang, Lei; Li, Hong-Mei; Liu, Jian-Hua; Yuan, Zhan-Peng; Chen, Tao; Tang, Ya-Jie

    2013-11-01

    For the first time, glyoxylate pathway in the biosynthesis of succinate was activated without the genetic manipulations of any gene related with glyoxylate pathway. Furthermore, the inactivation of succinate biosynthesis by-products genes encoding acetate kinase (ackA) and phosphotransacetylase (pta) was proven to be the key factor to activate glyoxylate pathway in the metabolically engineered Escherichia coli under anaerobic conditions. In order to enhance the succinate biosynthesis specifically, the genes (i.e., ldhA, ptsG, ackA-pta, focA-pflB, adhE) that disrupt by-products biosynthesis pathways were combinatorially deleted, while the E. coli malate dehydrogenase (MDH) was overexpression. The highest succinate production of 150.78 mM was obtained with YJ003 (ΔldhA, ptsG, ackA-pta), which were 5-folds higher than that obtained with wild type control strain DY329 (25.13 mM). For further understand the metabolic response as a result of several genetic manipulations, an anaerobic stoichiometric model that takes into account the glyoxylate pathway have successfully been implemented to estimate the intracellular fluxes in various recombinant E. coli. The fraction to the glyoxylate pathway from OAA in DY329 was 0 and 31% in YJ003, which indicated that even without the absence of the iclR mutation; the glyoxylate pathway was also activated by deleting the by-products biosynthetic genes, and to be responsible for the higher succinate yields. For further strengthen glyoxylate pathway, a two-stage fed-batch fermentation process was developed by using a 600 g l(-1) glucose feed to achieve a cell growth rate of 0.07 h(-1) in aerobic fermentation, and using a 750 g l(-1) glucose feed to maintain the residual glucose concentration around 40 g l(-1) when its residual level decreased to 10gl(-1) in anaerobic fermentation. The best mutant strain YJ003/pTrc99A-mdh produces final succinate concentration of 274 mM by fed-batch culture, which was 10-folds higher than that obtained

  7. Structure Determination and Characterization of the Vitamin B6 Degradative Enzyme 2-(Acetamidomethylene)succinate Hydrolase†‡

    OpenAIRE

    McCulloch, Kathryn M.; Mukherjee, Tathagata; Begley, Tadhg P.; Ealick, Steven E.

    2010-01-01

    The gene identification and kinetic characterization of E-2-(acetamidomethylene)succinate (E-2AMS) hydrolase has recently been described. This enzyme catalyzes the final reaction in the degradation of vitamin B6 and produces succinic semialdehyde, acetate, ammonia, and carbon dioxide from E-2AMS. The structure of E-2AMS hydrolase was determined to 2.3 Å using SAD phasing. E-2AMS hydrolase is a member of the α/β hydrolase superfamily and utilizes a serine/histidine/aspartic acid catalytic tria...

  8. Structure and reactions in some amphiphilic association systems

    Science.gov (United States)

    Guo, Rong

    1999-06-01

    surfactant CTAB system with various co-surfactants: n-pentanol, n-octanol, n-valeric acid, and n-caproic acid, but not in SDS or Triton X-100 systems. Presence of VC stabilizes both W/O and O/W microemulsions but destabilizes the lamellar liquid crystalline phase. Hence, the "phase transition" from the lamellar liquid crystalline phase to the isotropic phase of O/W, W/O and bicontinuous structure phase occurs with the addition of VC. The hydrotropic action of VC has been used in sunscreens to increase the solubility of sunscreen E 557. The UV absorption spectra of E557 in various media surprisingly had a dependence on the colloid structure. A new method, the preparation of water-soluble nanoparticles, has been found by employing the effect of the penetration of solvent from water layer to amphiphilic layer in lamellar liquid crystals on the solubility of inorganic salts. Water-insoluble nanoparticles have been synthesized by the reaction of two water-soluble inorganic salts in the lamellar liquid crystal. The particle size is less than 10nm and can be controlled by the thickness of the solvent layer in the lamellar liquid crystal. The lamellar liquid crystalline phase of the Triton X-100/decanol/water system has been chosen as a medium because of its large lamellar liquid crystal region and its stability when inorganic salts are added.

  9. Freeze drying: exploring potential in development of orodispersible tablets of sumatriptan succinate.

    Science.gov (United States)

    Gugulothu, Dalapathi; Desai, Preshita; Pandharipande, Pranav; Patravale, Vandana

    2015-03-01

    The present investigation is aimed at development and characterization of sumatriptan succinate orodispersible tablets (ODTs) prepared by freeze drying technology. The tablet excipients were screened and the composition was optimized based on parameters which involved general appearance, tablet size and shape, uniformity of weight, mechanical properties, surface pH, moisture analysis, drug content, wetting time, in vitro and in vivo disintegration time. Furthermore, fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron micrograph of cross-section of the tablet and in vitro dissolution studies were performed. Studies revealed that formulation containing gelatin-mannitol (3.75% w/v and 3.5% w/v, respectively) with camphor as a volatile pore forming agent exhibited superior properties with disintegration time of less than 10 s. Furthermore, in vitro release studies revealed 90% release of drug from developed dosage form within 10 min, thus suggesting rapid drug dissolution followed by faster onset of action, which forms a strong rationale for development of ODTs of sumatriptan succinate. The developed technology is simple, which involves few steps and can be easily scaled up. Thus, it holds enormous potential for commercial exploitation. PMID:24384027

  10. Study on fluorescence properties of carbogenic nanoparticles and their application for the determination of ferrous succinate

    Energy Technology Data Exchange (ETDEWEB)

    Sun Wen [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Du Yingxiang, E-mail: du_yingxiang@126.co [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China) and Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, Nanjing 210009 (China) and Key Laboratory of Modern Chinese Medicines, Ministry of Education, China Pharmaceutical University, Nanjing 210009 (China); Wang Yunqing [Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China)

    2010-08-15

    A new type of fluorescent nanomaterial named carbogenic nanoparticles (NPs) has drawn considerable attention recently. In this study, we adopted a direct and simple synthetic method to produce the carbogenic NPs and investigated the fluorescence properties of the as-prepared carbogenic NPs in detail. It was found that the fluorescence of carbogenic NPs was stable with the variance of environmental conditions such as pH, temperature and UV irradiation. More interestingly, we found carbogenic NPs exhibited high selectivity and sensitivity towards ferric ions. Under optimum conditions, a good linear relationship could be obtained between the fluorescence intensity and concentration of ferric ions in the range of 5.0x10{sup -5}-5.0x10{sup -4} mol L{sup -1}, and the limit of detection is 11.2 {mu}mol L{sup -1}. Based on the fluorescence quenching of carbogenic NPs, a rapid and specific quantitative method was proposed for the determination of ferrous succinate. The content of ferrous succinate in commercial tablets determined by the present method was agreed with the spectrophotometric method results and the reproducibility and the recovery of the proposed method were satisfactory.

  11. Study on fluorescence properties of carbogenic nanoparticles and their application for the determination of ferrous succinate

    International Nuclear Information System (INIS)

    A new type of fluorescent nanomaterial named carbogenic nanoparticles (NPs) has drawn considerable attention recently. In this study, we adopted a direct and simple synthetic method to produce the carbogenic NPs and investigated the fluorescence properties of the as-prepared carbogenic NPs in detail. It was found that the fluorescence of carbogenic NPs was stable with the variance of environmental conditions such as pH, temperature and UV irradiation. More interestingly, we found carbogenic NPs exhibited high selectivity and sensitivity towards ferric ions. Under optimum conditions, a good linear relationship could be obtained between the fluorescence intensity and concentration of ferric ions in the range of 5.0x10-5-5.0x10-4 mol L-1, and the limit of detection is 11.2 μmol L-1. Based on the fluorescence quenching of carbogenic NPs, a rapid and specific quantitative method was proposed for the determination of ferrous succinate. The content of ferrous succinate in commercial tablets determined by the present method was agreed with the spectrophotometric method results and the reproducibility and the recovery of the proposed method were satisfactory.

  12. Crystallization and degradation behaviors of poly(butylene succinate)/poly(Z-L-lysine) composites

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Licheng; Hu, Jun; Ye, Suwen; Wei, Junchao, E-mail: weijunchao@ncu.edu.cn; Chen, Yiwang

    2014-01-10

    Highlights: • A new biodegradable poly(butylene succinate) (PBS)/poly(Z-L-lysine) (PZlys) composites were successfully prepared through physical blend. • PZlys may greatly affected the crystallization behaviors of PBS without changing its crystalline structure. • The degradation speed of PBS may be greatly accelerated by introduction of PZlys in PBS matrix. - Abstract: A new type of biodegradable poly(butylene succinate) (PBS)/poly(Z-L-lysine) (PZlys) composites were prepared. The crystallization behaviors were investigated by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM) and the results showed that PZlys can restrict the crystallization of PBS, the crystallization speed of PBS/PZlys were slower than that of PBS, and the crystallization degree of the composites were smaller than that of PBS. However, the WAXD results showed that the incorporation of PZlys did not change the crystalline structure of PBS. The in vitro degradation experiments demonstrated that the degradation speed of the composites were faster than that of PBS. Moreover, the mechanical properties of the composites showed that the composites with a proper composition (for example, 80/20) can keep the mechanical properties of PBS without evident difference, which implied that the composites might be potentially useful as biodegradable materials.

  13. Crystallization and degradation behaviors of poly(butylene succinate)/poly(Z-L-lysine) composites

    International Nuclear Information System (INIS)

    Highlights: • A new biodegradable poly(butylene succinate) (PBS)/poly(Z-L-lysine) (PZlys) composites were successfully prepared through physical blend. • PZlys may greatly affected the crystallization behaviors of PBS without changing its crystalline structure. • The degradation speed of PBS may be greatly accelerated by introduction of PZlys in PBS matrix. - Abstract: A new type of biodegradable poly(butylene succinate) (PBS)/poly(Z-L-lysine) (PZlys) composites were prepared. The crystallization behaviors were investigated by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM) and the results showed that PZlys can restrict the crystallization of PBS, the crystallization speed of PBS/PZlys were slower than that of PBS, and the crystallization degree of the composites were smaller than that of PBS. However, the WAXD results showed that the incorporation of PZlys did not change the crystalline structure of PBS. The in vitro degradation experiments demonstrated that the degradation speed of the composites were faster than that of PBS. Moreover, the mechanical properties of the composites showed that the composites with a proper composition (for example, 80/20) can keep the mechanical properties of PBS without evident difference, which implied that the composites might be potentially useful as biodegradable materials

  14. Ercella succinigenes gen. nov., sp. nov., an anaerobic succinate-producing bacterium.

    Science.gov (United States)

    van Gelder, Antonie H; Sousa, Diana Z; Rijpstra, W Irene C; Damsté, Jaap S Sinninghe; Stams, Alfons J M; Sánchez-Andrea, Irene

    2014-07-01

    A novel anaerobic succinate-producing bacterium, strain ZWB(T), was isolated from sludge collected from a biogas desulfurization bioreactor (Eerbeek, the Netherlands). Cells were non-spore-forming, motile, slightly curved rods (0.4-0.5 µm in diameter and 2-3 µm in length), and stained Gram-negative. The temperature range for growth was 25-40 °C, with an optimum at 37 °C. The pH range for growth was 7.0-9.0, with an optimum at pH 7.5. Strain ZWB(T) was able to ferment glycerol and several carbohydrates mainly to H2, succinate and acetate. Sulfur and fumarate could be used as electron acceptors by strain ZWB(T). The G+C content of the genomic DNA was 37.6 mol%. The most abundant fatty acids were iso-C14 : 0 and iso-C16 : 0 DMA. On the basis of 16S rRNA gene sequence similarity, strain ZWB(T) belongs to the family Ruminococcaceae and it is distantly related to Saccharofermentans acetigenes JCM 14006(T) (92.1%). Based on the physiological features and phylogenetic analysis, strain ZWB(T) represents a novel species of a new genus, for which the name Ercella succinigenes gen. nov., sp. nov. is proposed. The type strain of Ercella succinigenes is ZWB(T) ( = DSM 27333(T) = JCM 19283(T)). PMID:24776531

  15. Precursors for sergeant-and-soldiers experiments: dimethyl succinic acid on Cu(110)

    Energy Technology Data Exchange (ETDEWEB)

    Karageorgaki, Chrysanthi; Roth, Christian; Parschau, Manfred; Ernst, Karl-Heinz [EMPA, Swiss Federal Laboratories for Materials Science and Technology, Duebendorf (Switzerland)

    2011-07-01

    In order to better understand chiral recognition at the molecular level, we are currently studying interactions between different chiral butanedioc acids, like tartaric acid (TA), malic acid (MA) and 2,3-dimethyl succinic acid (DMSU) as well as achiral analogues like succinic acid (SU), meso-TA and meso-DMSU on metal surfaces. This led to first a observation of chiral amplification 2D crystals via the so-called ''sergeant-and soldiers effect''. In order to discriminate if through-substrate or lateral hydrogen bonding dominates the chiral recognition at surfaces, we currently synthesize chiral DMSU, i.e., replacing the hydroxyl groups of TA by methyl. Here we present LEED, XPS, TPD and RAIRS results of achiral meso-DMSU (HOOC-CH(CH{sub 3})-CH(CH{sub 3})-COOH) on Cu(110). Besides coverage-dependent ''surface-explosion'' decomposition chemistry and ordered C{sub 2}-symmetric structures, DMSU spontaneously undergoes symmetry breaking, observed as superposition of mirror domains in LEED, which makes this system indeed interesting for doping experiments with chiral DMSU.

  16. EFFECT OF PROCESSING AND POLYMER VARIABLES ON INVITRO RELEASE OF METOPROLOL SUCCINATE EXTENDED RELEASE TABLETS

    Directory of Open Access Journals (Sweden)

    N. N. Rajendran et al.

    2011-12-01

    Full Text Available The present study was aimed to develop an extended release tablet of Metoprolol Succinate for the treatment of hypertension. Four extended release formulations F1-F4 were developed using varying proportions of Hydroxyl propyl methyl cellulose K100M, Sodium carboxy methyl cellulose and Eudragit L30 D55 by wet granulation. Five extended release formulations F5-F9 containing HPMC K100M and HPMC 5cps in varying concentration were developed by direct compression. The physico-chemical and in-vitro release characteristics of all the formulations were investigated and compared. Two formulations, F7 and F8 have shown not more 25% drug release in 1st h, 20-40% drug release at 4th h, 40-60% drug release at 8th h and not less than 80% at 20th h and the release pattern conform with USP specification for 24 h extended release formulation. It can be conclusively stated that optimum concentration of HPMC K100M (58-65% by direct compression method can yield an extended release of Metoprolol succinate for 24 hours.

  17. FORMULATION AND EVALUATION OF METOPROLOL SUCCINATE PULSATILE DRUG DELIVERY SYSTEM FOR CHRONO BIOLOGICAL DISORDER: ANTI HYPERTENSION

    Directory of Open Access Journals (Sweden)

    A. Anil Kumar et al

    2012-10-01

    Full Text Available The objective of the present study was to develop and evaluate an oral pulsatile drug delivery system to mimic the circadian rhythm of the disease by releasing the drug with a distinct predetermined log time of 5 hrs (+ 0.25 hrs. The basic design of the pulse in cap formulation of metoprolol provides time controlled release to treat the nocturnal symptoms of hypertension and angina pectoris. The pulsincap formulation of Metoprolol provides time controlled release to treat the nocturnal symptoms of hypertension and angina pectoris. If the formulation is administered in the night at 10.00 pm symptoms that are experienced in early morning hours could be avoided. In the present study, polymer such as Guargum selected for colon targeting of Metoprolol succinate. Metoprolol succinate granules were prepared using these polymers to prolong and target to the colon. Granules were prepared by wet granulation technique using different polymers in different ratios. These granules filled into the formaldehyde treated capsules and plugged with optimized HPMC plug, to maintain the 5hr lag time. Finally capsules are enteric coated with enteric coating polymers and conducted dissolution studies with different pH mediums.

  18. Saturation transfer difference NMR studies on substrates and inhibitors of succinic semialdehyde dehydrogenases

    International Nuclear Information System (INIS)

    Saturation transfer difference (STD) NMR experiments on Escherichia coli and Drosophila melanogaster succinic semialdehyde dehydrogenase (SSADH, EC1.2.1.24) suggest that only the aldehyde forms and not the gem-diol forms of the specific substrate succinic semialdehyde (SSA), of selected aldehyde substrates, and of the inhibitor 3-tolualdehyde bind to these enzymes. Site-directed mutagenesis of the active site cysteine311 to alanine in D. melanogaster SSADH leads to an inactive product binding both SSA aldehyde and gem-diol. Thus, the residue cysteine311 is crucial for their discrimination. STD experiments on SSADH and NAD+/NADP+ indicate differential affinity in agreement with the respective cosubstrate properties. Epitope mapping by STD points to a strong interaction of the NAD+/NADP+ adenine H2 proton with SSADH. Adenine H8, nicotinamide H2, H4, and H6 also show STD signals. Saturation transfer to the ribose moieties is limited to the anomeric protons of E. coli SSADH suggesting that the NAD+/NADP+ adenine and nicotinamide, but not the ribose moieties are important for the binding of the coenzymes

  19. Conformation of succinic acid: its pH dependence by Licry-NMR analysis

    Science.gov (United States)

    Chidichimo, G.; Formoso, P.; Golemme, A.; Imbardelli, D.

    The conformations of fully protonated (H2SA), fully deprotonated (SA=) and monoprotonated (HSA-) succinic acid have been investigated by means of nuclear magnetic resonance spectroscopy in liquid crystal mesophases (Licry-NMR). H-H and 13C-H direct dipolar couplings have been determined by measuring 1H-NMR and 13C-NMR spectra from quaternary nematic-lyotropic solutions of myristyltrimethylammonium bromide (MTAB), decanol, deuterated water and succinic acid (in each of its three different protonated forms). Direct dipolar couplings have been used to investigate the conformational equilibrium of the molecule in its three different protonation forms. Data could be interpreted in terms of a single conformation for each of the investigated forms. The dihedral angle between the H3-C5'-C5 and the C5'-C5-H1 planes gradually increases when going from the fully protonated H2SA species to the SA= ions. Our findings are different from those obtained by other authors by analysis of Jij couplings. In that case an equilibrium conformation between the gauche and trans conformers had been obtained.

  20. Crystallization and melting behavior of poly (ethylene succinate) in presence of graphene nanoplatelets

    International Nuclear Information System (INIS)

    Highlights: • Poly (ethylene succinate)/graphene nanocomposites were characterized in this work. • Dynamic and isothermal crystallization rates were enhanced upon graphene addition. • Overall crystallinity and melting remained almost unchanged in presence of graphene. • Graphene changed crystal perfection and its effect was found concentration-dependent. - Abstract: In this study, poly (ethylene succinate)/graphene nanoplatelets composites were prepared via solution casting method in different compositions and analyzed via differential scanning calorimetry. Crystallization and melting characteristics in both dynamic (non-isothermal) and isothermal modes were investigated at various cooling rates and isothermal temperatures. It was confirmed that graphene, while being incompatible with the matrix polymer, could act as nucleating agent so that hot (melt) crystallization rates, intensities, and positions were increased in the dynamic mode. However, the overall crystallinity remained almost unchanged. Cold crystallization was also decreased to lower temperatures on graphene addition; however its enthalpy was also reduced. Similar findings were observed for the isothermal mode, but to a lesser extent. The presence of graphene changed the perfection of crystals as their thermodynamic stability against heating and recrystallization behavior varied

  1. Photophysical and photochemical studies of a novel amphiphilic zinc phthalocyanine and its interaction with calf thymus DNA

    Science.gov (United States)

    Yuan, Linxin; Gui, Li; Wang, Yue; Zhang, Quanquan; Zhou, Lin; Wei, Shaohua

    2016-04-01

    β-tetra (aminophenoxy) sulfonic substituted zinc phthalocyanines (SNZnPc), a novel amphiphilic zinc phthalocyanine (Pc), was synthesized. The photophysical, photochemical, and photobiology properties were studied. Results indicated that the synthesized SNZnPc has good amphiphilic property and high reactive oxygen species (ROSs) generation ability. Furthermore, SNZnPc has strong affinity to calf thymus DNA (CT-DNA) through intercalation ways and can effectively cleavage CT-DNA after irradiation by light with appropriate wavelength.

  2. Synthesis of a new generation of amphiphiles with multi-cryptand headgroups: A comparative study at air–water interface

    Indian Academy of Sciences (India)

    B Sarkar; R K Gupta; R A Singh; P K Bharadwaj

    2008-06-01

    A laterally non-symmetric aza cryptand has been derivatized with two hydrophobic chains to afford amphiphiles with one cryptand headgroup and two hydrophobic tails. Three such units readily attach to 1,3,5-benzenetricarbonyl trichloride, to form a new generation of amphiphilic molecules with three cryptand headgroups and six hydrophobic chains. These molecules are studied at the air–water interface in a Langmuir trough. They readily form LB-films on a number of substrates that are characterized.

  3. Single-chain crosslinked star polymers via intramolecular crosslinking of self-folding amphiphilic copolymers in water

    OpenAIRE

    Terashima, Takaya; Sugita, Takanori; Sawamoto, Mitsuo

    2015-01-01

    Single-chain crosslinked star polymers with multiple hydrophilic short arms and a hydrophobic core were created as novel microgel star polymers of single polymer chains. The synthetic process involves the intramolecular crosslinking of self-folding amphiphilic random copolymers in water. For this process, amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic olefin pendants were synthesized by ruthenium-catalyzed living radical copolymerization of PEG m...

  4. Rheological properties of dough and quality of bread supplemented with emulsifying polysaccharides

    Directory of Open Access Journals (Sweden)

    Dapčević-Hadnađev Tamara

    2014-01-01

    Full Text Available The aim of present study was to evaluate the effects of emulsifying starches used as additives in breadmaking. In order to achieve this, the partial replacement (5-10% of wheat flour with starch sodium octenyl succinate (OSA starch, pregelatinized starch sodium octenyl succinate (Pregel OSA starch and hydrolyzed spray-dried starch sodium octenyl succinate (Hydrol OSA starch was performed. The quality characteristics of obtained bread were compared to control wheat flour bread and bread containing 0.5% hydroxypropyl methylcellulose (HPMC. The obtained results indicated that addition of Pregel and OSA starches influenced the increase in water absorption, whilst addition of Hydrol OSA starch exhibited the opposite effect. Moreover, the addition of all chosen starches influenced the decrease in dough stability. On the other hand, the positive effects of implementation of emulsifying starches on specific volume and texture were observed, where Pregel OSA and OSA starch have expressed the highest effect.

  5. Adsorption of phthalic acid esters (PAEs) by amphiphilic polypropylene nonwoven from aqueous solution: The study of hydrophilic and hydrophobic microdomain

    International Nuclear Information System (INIS)

    Highlights: • Amphiphilic PP-g-GMA-OA nonwoven was prepared and characterized. • Synergy between hydrophilic and hydrophobic microdomain was elucidated. • The effects of hydrophilic microdomain on diffusion resistance and energy barrier were elucidated. • Adsorbent material with amphiphilic structures showed faster adsorption rate and lager adsorption capacity. - Abstract: A kind of amphiphilic polypropylene nonwoven with hydrophilic and hydrophobic microdomain was prepared through electron beam induced graft polymerization and subsequent ring opening reaction and then utilized in the adsorption of phthalic acid esters (PAEs). To elucidate the superiority of such amphiphilic microdomain, a unique structure without hydrophilic part was constructed as comparison. In addition, the adsorption behaviors including adsorption kinetics, isotherms and pH effect were systematically investigated. The result indicated that the amphiphilic structure and the synergy between hydrophilic and hydrophobic microdomain could considerably improve the adsorption capacities, rate and affinity. Particularly the existence of hydrophilic microdomain could reduce the diffusion resistance and energy barrier in the adsorption process. These adsorption results showed that the amphiphilic PP nonwoven have the potential to be used in environmental application

  6. Adsorption of phthalic acid esters (PAEs) by amphiphilic polypropylene nonwoven from aqueous solution: The study of hydrophilic and hydrophobic microdomain

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiangyu [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300387 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Wei, Junfu, E-mail: weijunfu1963@163.com [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300387 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Zhang, Huan; Liu, Kai; Wang, Han [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300387 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

    2014-05-01

    Highlights: • Amphiphilic PP-g-GMA-OA nonwoven was prepared and characterized. • Synergy between hydrophilic and hydrophobic microdomain was elucidated. • The effects of hydrophilic microdomain on diffusion resistance and energy barrier were elucidated. • Adsorbent material with amphiphilic structures showed faster adsorption rate and lager adsorption capacity. - Abstract: A kind of amphiphilic polypropylene nonwoven with hydrophilic and hydrophobic microdomain was prepared through electron beam induced graft polymerization and subsequent ring opening reaction and then utilized in the adsorption of phthalic acid esters (PAEs). To elucidate the superiority of such amphiphilic microdomain, a unique structure without hydrophilic part was constructed as comparison. In addition, the adsorption behaviors including adsorption kinetics, isotherms and pH effect were systematically investigated. The result indicated that the amphiphilic structure and the synergy between hydrophilic and hydrophobic microdomain could considerably improve the adsorption capacities, rate and affinity. Particularly the existence of hydrophilic microdomain could reduce the diffusion resistance and energy barrier in the adsorption process. These adsorption results showed that the amphiphilic PP nonwoven have the potential to be used in environmental application.

  7. Mitochondrially targeted vitamin E succinate efficiently kills breast tumour-initiating cells in a complex II-dependent manner

    Czech Academy of Sciences Publication Activity Database

    Yan, B.; Stantic, M.; Zobalová, Renata; Bezawork-Geleta, A.; Stapelberg, M.; Stursa, J.; Prokopová, Kateřina; Dong, L.; Neužil, Jiří

    2015-01-01

    Roč. 15, č. 401 (2015). ISSN 1471-2407 R&D Projects: GA MZd NT14078; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:86652036 Keywords : Tumour-initiating cells * Mitochondrially targeted vitamin E succinate * Complex II Subject RIV: FD - Oncology ; Hematology Impact factor: 3.362, year: 2014

  8. Utilization of CO2 fixating bacterium Actinobacillus succinogenes 130Z for simultaneous biogas upgrading and bio-succinic acid production

    DEFF Research Database (Denmark)

    Gunnarsson, Ingólfur Bragi; Alvarado-Morales, Merlin; Angelidaki, Irini

    2014-01-01

    Biogas is an attractive renewable energy carrier. However, it contains CO2 which limits certain applications of biogas. Here we report a novel approach for removing CO2 from biogas and capturing it as a biochemical through a biological process. This approach entails converting CO2 into bio-succin...

  9. Linkage and radiation hybrid mapping of the porcine gene for subunit C of succinate dehydrogenase complex (SDHC)

    Czech Academy of Sciences Publication Activity Database

    Stratil, Antonín; Reiner, G.; Peelman, L. J.; Poucke, M.; Geldermann, H.

    2001-01-01

    Roč. 32, č. 2 (2001), s. 110-112. ISSN 0268-9146 R&D Projects: GA AV ČR KSK5052113; GA ČR GA523/00/0669 Keywords : succinate dehydrogenase complex Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.020, year: 2001

  10. Bid integrates intrinsic and extrinsic signaling in apoptosis induced by alpha-tocopheryl succinate in human gastric carcinoma cells

    Czech Academy of Sciences Publication Activity Database

    Zhao, Y.; Li, R.; Xia, W.; Neužil, Jiří; Lu, Y.; Zhang, H.; Zhao, X.; Zhang, X.; Sun, C.; Wu, K.

    2010-01-01

    Roč. 288, č. 1 (2010), s. 42-49. ISSN 0304-3835 R&D Projects: GA ČR(CZ) GA204/08/0811 Institutional research plan: CEZ:AV0Z50520701 Keywords : Alpha-tocopheryl succinate * signaling * apoptosis Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.864, year: 2010

  11. Characterization of Fe3O4/P(St-MPEO) Amphiphilic Magnetic Polymer Microspheres

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Amphiphilic magnetic microspheres consisting of styrene and poly(ethylene oxide) macromonomer(MPEO) were prepared by dispersion copolymerization in the presence of Fe3O4 magnetic fluid in an ethanol/water medium. The sizes of the magnetic microspheres and their distribution were characterized by means of scanning electron microscopy(SEM). The surface morphology and the average surface roughness of the microspheres were investigated by virtue of atomic force microscopy(AFM). It was found that the microspheres exhibit microscopic phase-separate and the mean square surface roughness of the microspheres increases with increasing MPEO used in the copolymerization. The amphiphilic magnetic microspheres containing 0.4-3.5 mg/g hydroxyl groups could be prepared from MPEO with different concentrations and styrene.

  12. Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene.

    Science.gov (United States)

    Lumholdt, Ludmilla; Fourmentin, Sophie; Nielsen, Thorbjørn T; Larsen, Kim L

    2014-01-01

    Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances) were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixture containing multiple pollutants. The volatile organic compounds are known to form stable inclusion complexes with cyclodextrins. Six different amphiphilic cyclodextrin derivatives were synthesised in order to elucidate whether or not the uptake abilities of the coating depend on the structure of the derivative. Headspace gas chromatography was used for quantification of the uptake exploiting the volatile nature of benzene and its derivatives. The capacity was shown to increase beyond the expected stoichiometries of guest-host complexes with ratios of up to 16:1. PMID:25550739

  13. Micelle assembly. Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles.

    Science.gov (United States)

    Qiu, Huibin; Hudson, Zachary M; Winnik, Mitchell A; Manners, Ian

    2015-03-20

    Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but on a longer length scale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side by side or end to end in nonsolvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and one-dimensional (1D) or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicrometer-length scale, features that are generally only found in natural materials. PMID:25792323

  14. Trapping of polycyclic aromatic hydrocarbons by amphiphilic cyclodextrin functionalized polypropylene nonwovens

    DEFF Research Database (Denmark)

    Lumholdt, Ludmilla; Nielsen, Ronnie Bo Højstrup; Larsen, Kim Lambertsen

    Recently, there has been an augmented focus on the increasing amount of pesticides, drug residues and endocrine disruptors present in waste and drinking water1. These pollutants represent a challenge in water purification since they may be hazardous to human health even in low doses2. Cyclodextrins...... textile fibers. In this study we present the ability of amphiphilic CD coated polypropylene nonwovens to trap 8 different polycyclic aromatic hydrocarbons/endocrine disruptors from aqueous solutions thus demonstrating the potential of using the amphiphilic cyclodextrins for water purification....... (CDs) are known to be able to form inclusion complexes with a large range of the unwanted pollutantse.g. 3 but in order to utilise this ability to purify water, the CDs must be immobilised on a surface, for instance, a membrane filter. We have developed a simple and fast method for the...

  15. Reverse self-assemblies based on amphiphilic polyphosphazenes for encapsulation of water-soluble molecules

    International Nuclear Information System (INIS)

    A novel series of amphiphilic polyphosphazenes (PNIPAm/AA-PPP) containing hydrophilic oligo-(N-isopropylacrylamide) (oligo-NIPAm) and various hydrophobic aliphatic amines as co-substitutes was synthesized via a two-step substitution reaction. The extraction and solubilization of water-soluble substances such as fluorescein sodium and trypan blue from an aqueous phase into the chloroform phase were supposed to result from the formation of polyphosphazene reverse self-assemblies in the organic phase. A field emission scanning electronic microscope was adopted to characterize the morphology of reverse assemblies in chloroform. Additionally, a significant improvement of encapsulation and release profiles of water-soluble substances was found for poly(lactic-co-glycolic acid) (PLGA) microparticles in the presence of amphiphilic copolymers, which was associated with the chemical structure of copolymers as well as the content of copolymer in the microparticles

  16. Reverse self-assemblies based on amphiphilic polyphosphazenes for encapsulation of water-soluble molecules

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Liyan [College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058 (China); Zhang Jianxiang [College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058 (China); Yan Meiqiu [College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058 (China); Jin Yi [College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058 (China); Zhu Kangjie [Institute of Polymer Science, Zhejiang University, Hangzhou 310027 (China)

    2007-11-28

    A novel series of amphiphilic polyphosphazenes (PNIPAm/AA-PPP) containing hydrophilic oligo-(N-isopropylacrylamide) (oligo-NIPAm) and various hydrophobic aliphatic amines as co-substitutes was synthesized via a two-step substitution reaction. The extraction and solubilization of water-soluble substances such as fluorescein sodium and trypan blue from an aqueous phase into the chloroform phase were supposed to result from the formation of polyphosphazene reverse self-assemblies in the organic phase. A field emission scanning electronic microscope was adopted to characterize the morphology of reverse assemblies in chloroform. Additionally, a significant improvement of encapsulation and release profiles of water-soluble substances was found for poly(lactic-co-glycolic acid) (PLGA) microparticles in the presence of amphiphilic copolymers, which was associated with the chemical structure of copolymers as well as the content of copolymer in the microparticles.

  17. AMPHIPHILIC STAR-BLOCK COPOLYMERS BY IODIDE-MEDIATED RADICAL POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Amphiphilic star-block copolymers composed of polystyrene and poly(acrylic acid) were synthesized by iodidemediated radical polymerization. Firstly, free radical polymerization of styrene was carried out with AIBN as initiator and 1,1,1-trimethyolpropane tri(2-iodoisobutyrate) as chain transfer agent, giving iodine atom ended star-shaped polystyrene with three arm chains, R(polystyrene)3. Secondly, tert-butyl acrylate was polymerization using polystyrene obtained as macro-chain transfer agent, and star-block copolymer, R(polystyrene-b-poly(tert-butyl acrylate))3 with controlled molecular weight was obtained. Finally, amphiphilic star-block copolymer, R(polystyrene-b-poly(acrylic acid))3 was obtained by hydrolysis of R(polystyrene-b-poly(tert-butyl acrylate))3 under acidic condition.

  18. Super-resolution microscopy reveals structural diversity in molecular exchange among peptide amphiphile nanofibres

    Science.gov (United States)

    da Silva, Ricardo M. P.; van der Zwaag, Daan; Albertazzi, Lorenzo; Lee, Sungsoo S.; Meijer, E. W.; Stupp, Samuel I.

    2016-05-01

    The dynamic behaviour of supramolecular systems is an important dimension of their potential functions. Here, we report on the use of stochastic optical reconstruction microscopy to study the molecular exchange of peptide amphiphile nanofibres, supramolecular systems known to have important biomedical functions. Solutions of nanofibres labelled with different dyes (Cy3 and Cy5) were mixed, and the distribution of dyes inserting into initially single-colour nanofibres was quantified using correlative image analysis. Our observations are consistent with an exchange mechanism involving monomers or small clusters of molecules inserting randomly into a fibre. Different exchange rates are observed within the same fibre, suggesting that local cohesive structures exist on the basis of β-sheet discontinuous domains. The results reported here show that peptide amphiphile supramolecular systems can be dynamic and that their intermolecular interactions affect exchange patterns. This information can be used to generate useful aggregate morphologies for improved biomedical function.

  19. Imaging Pseudomonas aeruginosa Biofilm Extracellular Polymer Scaffolds with Amphiphilic Carbon Dots.

    Science.gov (United States)

    Ritenberg, Margarita; Nandi, Sukhendu; Kolusheva, Sofiya; Dandela, Rambabu; Meijler, Michael M; Jelinek, Raz

    2016-05-20

    Biofilm formation is a critical facet of pathogenesis and resilience of human, animal, and plant bacteria. Extracellular polymeric substances (EPS) constitute the physical scaffolding for bacterial biofilms and thus play central roles in their development and virulence. We show that newly synthesized amphiphilic fluorescent carbon dots (C-dots) readily bind to the EPS scaffold of Pseudomonas aeruginosa, a major biofilm-forming pathogen, resulting in unprecedented microscopic visualization of the EPS structural features. Fluorescence microscopy analysis utilizing the C-dots reveals that the P. aeruginosa EPS matrix exhibits a remarkable dendritic morphology. The experiments further illuminate the growth kinetics of the EPS and the effect of external factors such as temperature. We also show that the amphiphilic C-dot platform enabled screening of substances disrupting biofilm development, specifically quorum sensing inhibitors. PMID:26882175

  20. REVIEWS OF TOPICAL PROBLEMS: Supermolecular liquid-crystalline structures in solutions of amphiphilic molecules

    Science.gov (United States)

    Vedenov, A. A.; Levchenko, E. B.

    1983-09-01

    This paper reviews the physical properties of liquid-crystalline phases arising in solutions containing molecules of amphiphilic substances. The basic characteristics of micelle formation in dilute solutions, models of sphere-disk or sphere-cylinder structural transformations, as well as phase transitions related to the appearance of lyotropic mesophases in the system, including nematic, lamellar, hexagonal, and others, are examined. The results of experimental and theoretical investigation of "solvation" forces acting between micelles in the solvent, as well as recently studied models of swelling of lamellar phases are presented. The phenomena occurring near the inversion point of microemulsions in amphiphile-oil-water systems are examined briefly. The role of liquid-crystalline ordering in some biological systems is discussed.

  1. Amphiphilic block copolymers in oil-water-surfactant mixtures: efficiency boosting, structure, phase behaviour and mechanism

    Science.gov (United States)

    Gompper, G.; Richter, D.; Strey, R.

    2001-10-01

    The effect of amphiphilic block copolymers on the phase behaviour and structure of ternary microemulsions in water, oil and non-ionic surfactant mixtures is reviewed. Recent experiments have revealed that the addition of small amounts of polyethylenepropylene-polyethyleneoxide block copolymer to the ternary systems leads to a dramatic increase in the volumes of oil and water solubilized into a bicontinuous microemulsion for a given surfactant volume fraction. While phase diagrams directly show the power of the amphiphilic block copolymers as efficiency boosters, the theoretical analysis in terms of bending energy discloses the mechanism for the efficiency boosting as due to the variation of the surfactant film curvature elasticity by tethered polymers in the form of mushrooms at the interface. Neutron scattering experiments employing a high-precision two-dimensional contrast variation technique confirm this picture and demonstrate that the polymer molecules uniformly decorate the surfactant film.

  2. Replication of simulated prebiotic amphiphile vesicles controlled by experimental lipid physicochemical properties

    International Nuclear Information System (INIS)

    We present a new embodiment of the graded autocatalysis replication domain (GARD) for the growth, replication and evolution of lipid vesicles based on a semi-empirical foundation using experimentally measured kinetic values of selected extant lipid species. Extensive simulations using this formalism elucidated the details of the dependence of the replication and properties of the vesicles on the physicochemical properties and concentrations of the lipids, both in the environment and in the vesicle. As expected, the overall concentration and number of amphiphilic components strongly affect average replication time. Furthermore, variations in acyl chain length and unsaturation of vesicles also influence replication rate, as do the relative concentrations of individual lipid types. Understanding of the dependence of replication rates on physicochemical parameters opens a new direction in the study of prebiotic vesicles and lays the groundwork for future studies involving the competition between lipid vesicles for available amphiphilic monomers

  3. A V-shaped polyaromatic amphiphile: solubilization of various nanocarbons in water and enhanced photostability.

    Science.gov (United States)

    Kondo, Kei; Akita, Munetaka; Nakagawa, Takafumi; Matsuo, Yutaka; Yoshizawa, Michito

    2015-09-01

    Nanocarbons are synthetic carbon-rich compounds with polyaromatic frameworks that have lately attracted attention as emerging functional materials. However, their extreme hydrophobicity and aggregation peculiarity, besides their shape and size diversities, precluded their study in solution, especially in "green" water. More convenient and general solubilizing methods of nanocarbon frameworks are required by using non-covalent supramolecular interactions. Here we report a protocol for solubilizing a wide range of nanocarbons, that is, fullerenes (C60 , C70 , C84 , and C120 ), polyarenes (tetracene, pentacene, perylene, coronene, and hexabenzocoronene), and carbon nanotubes (single-walled and multi-walled CNTs), in water through manual grinding with V-shaped polyaromatic amphiphiles. The obtained aqueous nanocomposites are composed of nanocarbons encircled by the polyaromatic frameworks of the amphiphiles through multiple aromatic-aromatic interactions. Notably, the encapsulated photosensitive nanocarbons, such as tetracene, pentacene, and fullerene dimer, exhibit unusual stability toward UV/Vis light. PMID:26224472

  4. Synthesis of an amphiphilic dendrimer-like block copolymer and its application on drug delivery

    KAUST Repository

    Wang, Shuaipeng

    2014-10-27

    Dendrimer-like amphiphilic copolymer is a kind of three-dimensional spherical structure polymer. An amphiphilic dendrimer-like diblock copolymer, PEEGE-G2-b-PEO(OH)12, constituted of a hydrophobic poly(ethoxyethyl glycidol ether) inner core and a hydrophilic poly(ethylene oxide) outer layer, has been successfully synthesized by the living anionic ring-opening polymerization method. The intermediates and targeted products were characterized with 1H NMR spectroscopy and gel permeation chromatography. The application on drug delivery of dendrimer-like diblock copolymer PEEGE-G2-b-PEO(OH)12 using DOX as a model drug was also studied. The drug loading content and encapsulation efficiency were found at 13.07% and 45.75%, respectively. In vitro release experiment results indicated that the drug-loaded micelles exhibited a sustained release behavior under acidic media.

  5. Novel Xylene-Linked Maltoside Amphiphiles (XMAs) for Membrane Protein Stabilisation

    DEFF Research Database (Denmark)

    Cho, Kyung Ho; Du, Yang; Scull, Nicola J; Hariharan, Parameswaran; Gotfryd, Kamil; Loland, Claus J; Guan, Lan; Byrne, Bernadette; Kobilka, Brian K; Chae, Pil Seok

    2015-01-01

    . Conventional detergents are commonly used for membrane protein manipulation, but membrane proteins surrounded by these agents often undergo denaturation and aggregation. In this study, a novel class of maltoside-bearing amphiphiles, with a xylene linker in the central region, designated xylene-linked maltoside......Membrane proteins are key functional players in biological systems. These biomacromolecules contain both hydrophilic and hydrophobic regions and thus amphipathic molecules are necessary to extract membrane proteins from their native lipid environments and stabilise them in aqueous solutions...... amphiphiles (XMAs) was developed. When these novel agents were evaluated with a number of membrane proteins, it was found that XMA-4 and XMA-5 have particularly favourable efficacy with respect to membrane protein stabilisation, indicating that these agents hold significant potential for membrane protein...

  6. Amphiphilic block copolymers as efficiency boosters in microemulsions a SANS investigation of the role of polymers

    CERN Document Server

    Endo, H; Mihailescu, M; Monkenbusch, M; Gompper, G; Richter, D; Jakobs, B; Sottmann, T; Strey, R

    2002-01-01

    The effect of amphiphilic block copolymers on ternary microemulsions (water, oil and non-ionic surfactant) is investigated. Small amounts of PEP-PEO block copolymer lead to a dramatic expansion of the one-phase region where water and oil can be solubilized by the mediation of surfactant molecules. Small-angle neutron-scattering experiments employing a high-precision two-dimensional contrast-variation technique demonstrate that the polymer is distributed uniformly on the surfactant membrane, where it modifies the membrane curvature elasticity. Furthermore, a new approach to determine the bending rigidity of an amphiphilic membrane is proposed, which is precise enough to measure the logarithmic scale dependence of the bending rigidity and its universal prefactor in bicontinuous microemulsions. (orig.)

  7. Development and validation of HPTLC method for simultaneous determination of amlodipine besylate and metoprolol succinate in bulk and tablets

    Directory of Open Access Journals (Sweden)

    P S Jain

    2012-01-01

    Full Text Available A simple, selective, precise high-performance thin-layer chromatographic method for simultaneous determination of amlodipine besylate and metoprolol succinate in bulk and pharmaceutical combined dosage form was developed and validated. The method employed HPTLC aluminum plates precoated with silica gel 60F-254 (10×10 as the stationary phase. The solvent system consisted of toluene:ethyl acetate:methanol:triethylamine (4:1:1:0.4 v/v/v. The system was found to give a compact spot for amlodipine besylate (R f = 0.39±0.02 and metoprolol succinate (R f = 0.59±0.02. Densitometric analysis of amlodipine besylate and metoprolol succinate was carried out in the absorbance mode at 254 nm. Linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.9990±0.0013 with respect to peak area in the concentration range 400-1400 ng per spot for amlodipine besylate and r2 = 0.9993±0.0013 with respect to peak area in the concentration range 3800-13300 ng per spot for metoprolol succinate. The method was validated for precision, recovery and robustness. The limits of detection and quantitation were 39.99 and 121.20 ng per spot for amlodipine besylate and 234.31 and 710.03 ng per spot for metoprolol succinate, respectively. Statistical analysis proved that the method is selective, precise and accurate for the estimation of amlodipine and metoprolol.

  8. ANIONIC SYNTHESIS OF A "CLICKABLE" MIDDLE-CHAIN AZIDEFUNCTIONALIZED POLYSTYRENE AND ITS APPLICATION IN SHAPE AMPHIPHILES

    Institute of Scientific and Technical Information of China (English)

    Kan Yue; Jinlin He; Chang Liu; Mingjun Huang; Xue-Hui Dong; Kai Guo; Peihong Ni

    2013-01-01

    "Click chemistry" is,by definition,a general functionalization methodology (GFM) and its marriage with living anionic polymerization is particularly powerful in precise macromolecular synthesis.This paper reports the synthesis of a "clickable" middle-chain azide-functionalized polystyrene (mPS-N3) by anionic polymerization and its application in the preparation of novel shape amphiphiles based on polyhedral oligomeric silsesquioxane (POSS).The mPS-N3 was synthesized by coupling living poly(styryl)lithium chains (PSLi) with 3-chloropropylmethyldichlorosilane and subsequent nucleophilic substitution of the chloro group in the presence of sodium azide.Excess PSLi was end-capped with ethylene oxide to facilitate its removal by flash chromatography.The mPS-N3 was then derived into a giant lipid-like shape amphiphile in two steps following a sequential "click" strategy.The copper(I)-catalyzed azide-alkyne cycloaddition between mPS-N3 and alkyne-functionalized vinyl-substituted POSS derivative (VPOSS-alkyne) ensured quantitative ligation to give polystyrene with VPOSS tethered at the middle of the chain (mPS-VPOSS).The thiol-ene reaction with 1-thioglycerol transforms the vinyl groups on the POSS periphery to hydroxyls,resulting in an amphiphilic shape amphiphile,mPS-DPOSS.This synthetic approach is highly efficient and modular.It demonstrates the "click" philosophy of facile complex molecule construction from a library of simple building blocks and also suggests that mPS-N3 can be used as a versatile "clickable" motif in polymer science for the precise synthesis of complex macromolecules.

  9. Novel Amphiphilic copolymers and design of smart nanoparticule for triggered drug delivery systems

    OpenAIRE

    Cajot, Sébastien; Jérôme, Christine

    2009-01-01

    Over the last decade, polymer micelles attracted an increasing interest in drug pharmaceutical research because they could be used as efficient drug delivery systems. Micelles of amphiphilic block copolymers are supramolecular core-shell type assemblies of tens of nanometers in diameter. In principle, the micelles core is usually constructed with biodegradable hydrophobic polymers such as aliphatic polyesters, e.g. poly(epsilon-caprolactone) (PCL), which serves as a reservoir for the inc...

  10. Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene

    OpenAIRE

    Ludmilla Lumholdt; Sophie Fourmentin; Nielsen, Thorbjørn T; Larsen, Kim L.

    2014-01-01

    Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances) were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixt...

  11. Hybrid biomimetic scaffold composed of electrospun polycaprolactone nanofibers and self-assembled peptide amphiphile nanofibers

    OpenAIRE

    Tambralli, Ajay; Blakeney, Bryan; Anderson, Joel; Kushwaha, Meenakshi; Andukuri, Adinarayana; Dean, Derrick; Jun, Ho-Wook

    2009-01-01

    Nanofibrous electrospun poly (ε-caprolactone) (ePCL) scaffolds have inherent structural advantages, but lack of bioactivity has limited their usefulness in biomedical applications. Thus, here we report the development of a hybrid, nanostructured, extracellular matrix (ECM) mimicking scaffold by a combination of ePCL nanofibers and self-assembled peptide amphiphile (PA) nanofibers. The PAs have ECM mimicking characteristics including a cell adhesive ligand (RGDS) and matrix metalloproteinase-2...

  12. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion

    OpenAIRE

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible add...

  13. Structure of adsorption layers of amphiphilic copolymers on inorganic or organic particle surfaces

    OpenAIRE

    Bulychev, Nikolay; Dervaux, Bart; Dimberger, Klaus; Zubov, Vitali; Du Prez, Filip; Eisenbach, Claus D

    2010-01-01

    The structure of adsorption layers of amphiphilic block and block-like copolymers of poly(isobornyl acrylate) and poly(acrylic acid) on the surface of hydrophilic titanium dioxide and hydrophobic copper phthalocyanine (CuPc) pigments in an aqueous studied by the electrokinetic sonic amplitude (ESA) method. The electroacoustic behaviour of the polyelectrolyte block copolymer-coated particles could be described in the context of the polymer gel layer theory. The polymer layer around the particl...

  14. Aggregate of Amphiphilic Block Copolymer as a Pseudo-Stationary Phase in Capillary Electrophoresis

    OpenAIRE

    Nakamura, Tohru; OHKI, Akira; Mishiro, Masaki; Tsuyashima, Osamu; Maeda, Shigeru; ナカムラ, トオル; オオキ, アキラ; ミシロ, マサキ; ツヤシマ, オサム; マエダ, シゲル; 中村, 透; 大木, 章; 艶島, 修; 前田, 滋

    1999-01-01

    The use of an aggregate of amphiphilic block copolymer 1, which consists of poly[(N-acetylimino)ethylene] and poly[(N-pentanoylimino)ethylene], for a pseudo-stationary phase in capillary electrophoresis has been examined. From gel-filtration chromatography, the aggregate from 1 (1-AG) was found to incorporate phenol. When the running solution contains 1-AG and sodium dodecyl sulfate (SDS), the electrophoretic mobility becomes nearly zero. Thus, it is found that when 1-AG and SDS are added to ...

  15. Dynamic Ordering Transitions of Liquid Crystals Driven by Interfacial Complexes Formed Between Polyanions and Amphiphilic Polyamines

    OpenAIRE

    Kinsinger, Michael I.; Buck, Maren E.; de Campos, Fernando; Lynn, David M.; Abbott, Nicholas L.

    2008-01-01

    We report the design of an amphiphilic polyamine based on poly(2-alkenyl azlactone) (polymer 1) that strongly couples the formation of polyelectrolyte complexes at aqueous/liquid crystal (LC) interfaces to ordering transitions in the LC. We demonstrate that the addition of a strong anionic polyelectrolyte to aqueous solutions in contact with polymer 1-laden LC interfaces (prepared by Langmuir-Schaefer transfer of monolayers of polymer 1 onto micrometer-thick films of nematic LC) triggers orde...

  16. Amphiphilic zein hydrolysate as a novel nano-delivery vehicle for curcumin.

    Science.gov (United States)

    Wang, Yong-Hui; Wang, Jin-Mei; Yang, Xiao-Quan; Guo, Jian; Lin, Yuan

    2015-08-01

    In this paper, we developed amphiphilic zein hydrolysate (ZH) as a novel delivery vehicle, which could be used for preparing curcumin (Cur) nanocomplexes. These ZH-Cur nanocomplexes exhibited spherical morphology with a monodisperse size distribution (oil-water interface, as confirmed by micelle formation and dynamic interfacial adsorption respectively. Fluorescence titration and FTIR results indicated the existence of strong hydrophobic interactions between ZH and Cur, which was responsible for the complexation. PMID:26134524

  17. Novel amphiphilic diblock copolymers by RAFT-polymerization, their self-organization and surfactant properties

    OpenAIRE

    Garnier, Sébastien

    2006-01-01

    The Reversible Addition Fragmentation Chain Transfer (RAFT) process using the new RAFT agent benzyldithiophenyl acetate is shown to be a powerful polymerization tool to synthesize novel well-defined amphiphilic diblock copolymers composed of the constant hydrophobic block poly(butyl acrylate) and of 6 different hydrophilic blocks with various polarities, namely a series of non-ionic, non-ionic comb-like, anionic and cationic hydrophilic blocks. The controlled character of the polymerizations ...

  18. Comparison of Facially Amphiphilic versus Segregated Monomers in the Design of Antibacterial Copolymers

    OpenAIRE

    Gabriel, Gregory J.; Maegerlein, Janet A.; Nelson, Christopher F.; Dabkowski, Jeffrey M.; Eren, Tarik; Nüsslein, Klaus; Tew, Gregory N.

    2009-01-01

    A direct comparison of two strategies for designing antimicrobial polymers is presented. Previously, we published several reports on the use of facially amphiphilic (FA) monomers which led to polynorbornenes with excellent antimicrobial activities and selectivities. Our polymers obtained by copolymerization of structurally similar segregated monomers, in which cationic and non-polar moieties reside on separate repeat units, led to polymers with less pronounced activities. A wide range of poly...

  19. Extracellular matrix formation in self-assembled minimalistic bioactive hydrogels based on aromatic peptide amphiphiles

    OpenAIRE

    ZHOU, MI; Ulijn, Rein V.; Gough, Julie E

    2014-01-01

    The hitherto inconsistency in clinical performance for engineered skin drives the current development of novel cell-scaffolding materials; one challenge is to only extract essential characteristics from the complex native ECM (extracellular matrix) and incorporate them into a scaffold with minimal complexity to support normal cell functions. This study involved small-molecule-based bioactive hydrogels produced by the co-assembly of two aromatic peptide amphiphiles: Fmoc-FF (Fluorenylmethoxyca...

  20. Non-ionic amphiphilic block copolymers by RAFT-polymerization and their self-organization

    OpenAIRE

    Garnier, Sébastien; Laschewsky, André

    2006-01-01

    Water-soluble, amphiphilic diblock copolymers were synthesized by reversible addition fragmentation chain transfer polymerization. They consist of poly(butyl acrylate) as hydrophobic block with a low glass transition temperature and three different nonionic water-soluble blocks, namely, the classical hydrophilic block poly(dimethylacrylamide), the strongly hydrophilic poly(acryloyloxyethyl methylsulfoxide), and the thermally sensitive poly(N-acryloylpyrrolidine). Aqueous micellar solutions of...

  1. A comparative study of the physicochemical properties of perfluorinated and hydrogenated amphiphiles.

    Science.gov (United States)

    Blanco, Elena; González-Pérez, Alfredo; Ruso, Juan M; Pedrido, Rosa; Prieto, Gerardo; Sarmiento, Félix

    2005-08-01

    In this work we studied and compared the physicochemical properties of perfluorinated (sodium perfluoroheptanoate, C7FONa, and perfluorooctanoate, C8FONa) and hydrogenated (sodium octanoate, C8HONa, decanoate, C10HONa, and dodecanoate, C12HONa) amphiphiles. First, we determined their Krafft points to study the solubility and appropriate temperature range of micellization of these compounds. The critical micelle concentration (cmc) and ionization degree of micellization (beta) as a function of temperature (T) were estimated from conductivity data. Plots of cmc vs T appear to follow the typical U-shaped curve with a minimum T(min). The results show that the surfactants with CF2/CH2 ratio of 1.5 between alkyl chains (C12HONa-C8FONa and C10HONa-C7FONa) have nearly the same minimum value for cmc against temperature. The comparison between the cmc of hydrogenated amphiphiles and the corresponding perfluorinated amphiphiles must be done at this point. Thermodynamic functions of micellization were obtained by applying different theoretical models and choosing the one that best fit our experimental data. Although perfluorinated and hydrogenated amphiphiles present similar thermodynamic behavior, we have found a variation of 1.3 to 1.7 in the CF2/CH2 ratio, which did not remain constant with temperature. In the second part of this study the apparent molar volumes and adiabatic compressibilities were determined from density and ultrasound velocity measurements. Apparent molar volumes at infinite dilution presented the ratio 1.5 between alkyl chains again. However, apparent molar volumes upon micellization for sodium perfluoroheptanoate indicated a different aggregation pattern. PMID:15927586

  2. Screening Nylon-3 Polymers, a New Class of Cationic Amphiphiles, for siRNA Delivery

    OpenAIRE

    Nadithe, Venkatareddy; Liu, Runhui; Killinger, Bryan A.; Movassaghian, Sara; Kim, Na Hyung; Moszczynska, Anna B.; Masters, Kristyn S.; Gellman, Samuel H.; Merkel, Olivia M

    2014-01-01

    Amphiphilic nucleic acid carriers have attracted strong interest. Three groups of nylon-3 copolymers (poly-β-peptides) possessing different cationic/hydrophobic content were evaluated as siRNA delivery agents in this study. Their ability to condense siRNA was determined in SYBR Gold assays. Their cytotoxicity was tested by MTT assays, their efficiency of delivering Alexa Fluor-488-labeled siRNA intracellularly in the presence and absence of uptake inhibitors was assessed by flow cytometry, an...

  3. Carboxymethyl chitosan-graft-phosphatidylethanolamine : amphiphilic matrices for controlled drug delivery

    OpenAIRE

    Prabaharan, M.; Reis, R. L.; Mano, J. F.

    2007-01-01

    Modified carboxymethyl chitosan (CMC) containing phosphatidylethanolamine (PEA) groups were synthesized by a 1- ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)-mediated coupling reaction. The structure of the modified CMC exhibiting an amphiphilic character was analysed by FT-IR and 1H NMR. CMC-g-PEA beads were prepared with sodium tripolyphosphate (TPP) by ionic-crosslinking. The beads sizes were in range from 800 to 1200 lm and encapsulation efficiencies of drug were more than...

  4. Synthesis and self-assembly of multiple thermoresponsive amphiphilic block copolymers

    OpenAIRE

    Weiß, Jan

    2011-01-01

    In the present thesis, the self-assembly of multi thermoresponsive block copolymers in dilute aqueous solution was investigated by a combination of turbidimetry, dynamic light scattering, TEM measurements, NMR as well as fluorescence spectroscopy. The successive conversion of such block copolymers from a hydrophilic into a hydrophobic state includes intermediate amphiphilic states with a variable hydrophilic-to-lipophilic balance. As a result, the self-organization is not following an all-or-...

  5. Mineralization of Peptide Amphiphiles Nanofibers and its Effect on Differentiation of Human Mesenchymal Stem Cells

    OpenAIRE

    Sargeant, Timothy D; Aparicio, Conrado; Goldberger, Josh; Cui, Honggang; Stupp, Samuel I.

    2012-01-01

    One of the important targets in regenerative medicine is to design resorbable materials that can promote formation of new bone in large skeletal defects. One approach to this challenge is to use a bioactive and biodegradable organic matrix that can promote cellular adhesion and direct differentiation. We studied here matrices composed of peptide amphiphiles (PAs) that self-assemble into nanofibers and create self-supporting gels in cell culture conditions. The bioactivity of PAs was designed ...

  6. Effect of peptide secondary structure on peptide amphiphile supramolecular structure and interactions

    OpenAIRE

    Missirlis, Dimitris; Chworos, Arkadiusz; Fu, Caroline J; Khant, Htet A.; Krogstad, Daniel V.; Tirrell, Matthew

    2011-01-01

    Bottom-up fabrication of self-assembled nanomaterials requires control over forces and interactions between building blocks. We here report on the formation and architecture of supramolecular structures constructed from two different peptide amphiphiles. Inclusion of four alanines between a 16-mer peptide and a 16-carbon long aliphatic tail resulted in a secondary structure shift of the peptide headgroups from alpha helices to beta sheets. A concomitant shift in self-assembled morphology from...

  7. Enhanced cycling performance of lithium metal secondary batteries with succinic anhydride as an electrolyte additive

    International Nuclear Information System (INIS)

    The effect of succinic anhydride (SA) as an electrolyte additive on the cycling performance of Li electrode is discussed. As the SA content in the electrolyte increased from 2 to 5 to 10 wt%, the capacity retention of LiCoO2/Li cell is greatly improved owing to the modification of the solid electrolyte interphase (SEI) layer and the suppression of dendrite growth on the Li electrode. In particular, when 10 wt% SA is introduced into the electrolyte, the Li electrode thickness increases only about 45 μm (from 100 to 145 μm) after 40 cycles, whereas an increase of about 210 μm occurs without SA. This amazing enhancement in cycling performance is also augmented by a much smaller increase in the bulk resistance of the LiCoO2/Li cell after cycling with 10 wt% SA

  8. Succinic acid production from duckweed (Landoltia punctata) hydrolysate by batch fermentation of Actinobacillus succinogenes GXAS137.

    Science.gov (United States)

    Shen, Naikun; Wang, Qingyan; Zhu, Jing; Qin, Yan; Liao, Siming; Li, Yi; Zhu, Qixia; Jin, Yanling; Du, Liqin; Huang, Ribo

    2016-07-01

    Duckweed is potentially an ideal succinic acid (SA) feedstock due to its high proportion of starch and low lignin content. Pretreatment methods, substrate content and nitrogen source were investigated to enhance the bioconversion of duckweed to SA and to reduce the costs of production. Results showed that acid hydrolysis was an effective pretreatment method because of its high SA yield. The optimum substrate concentration was 140g/L. The optimum substrate concentration was 140g/L. Corn steep liquor powder could be considered a feasible and inexpensive alternative to yeast extract as a nitrogen source. Approximately 57.85g/L of SA was produced when batch fermentation was conducted in a 1.3L stirred bioreactor. Therefore, inexpensive duckweed can be a promising feedstock for the economical and efficient production of SA through fermentation by Actinobacillus succinogenes GXAS137. PMID:27023386

  9. Immunolocalization of succinate dehydrogenase in the esophagus epithelium of domesticated mammals

    Directory of Open Access Journals (Sweden)

    W. Meyer

    2013-05-01

    Full Text Available Using immunohistochemistry and transmission electron microscopy (TEM, the esophagus epithelia of seven domesticated mammals (horse, cattle, goat, pig, dog, laboratory rat, cat of three nutrition groups (herbivorous, omnivorous, carnivorous were studied to get first information about energy generation, as demonstrated by succinate dehydrogenase (SDH activities. Distinct reaction intensities could be observed in all esophageal cell layers of the different species studied reflecting moderate to strong metabolic activities. The generally strong staining in the stratum basale indicated that new cells are continuously produced. The latter feature was confirmed by a thick, and in the horse generally highly active stratum spinosum. Only in the pig, reaction intensity variations occurred, obviously related to differences in physical feed quality or restricted feed allocation. The immunohistochemical results were corroborated by the presence of intact mitochondria in the esophageal cells of all species and nutrition types studied, except for the horse. Possible relationships between SDH reaction intensities and feed structure, mass or consistency are discussed.

  10. Discovery of Potent Succinate-Ubiquinone Oxidoreductase Inhibitors via Pharmacophore-linked Fragment Virtual Screening Approach.

    Science.gov (United States)

    Xiong, Li; Zhu, Xiao-Lei; Gao, Hua-Wei; Fu, Yu; Hu, Sheng-Quan; Jiang, Li-Na; Yang, Wen-Chao; Yang, Guang-Fu

    2016-06-22

    Succinate-ubiquinone oxidoreductase (SQR) is an attractive target for fungicide discovery. Herein, we report the discovery of novel SQR inhibitors using a pharmacophore-linked fragment virtual screening approach, a new drug design method developed in our laboratory. Among newly designed compounds, compound 9s was identified as the most potent inhibitor with a Ki value of 34 nM against porcine SQR, displaying approximately 10-fold higher potency than that of the commercial control penthiopyrad. Further inhibitory kinetics studies revealed that compound 9s is a noncompetitive inhibitor with respect to the substrate cytochrome c and DCIP. Interestingly, compounds 8a, 9h, 9j, and 9k exhibited good in vivo preventive effects against Rhizoctonia solani. The results obtained from molecular modeling showed that the orientation of the R(2) group had a significant effect on binding with the protein. PMID:27225833

  11. Synthesis, characterization and thermal behavior of solid state compounds of heavy trivalent lanthanide succinates

    International Nuclear Information System (INIS)

    Highlights: ► Thermal stability of compounds was investigated. ► Determination of the gaseous products released. ► The results also provided information concerning the denticity of the ligand. - Abstract: Solid-state Ln–L compounds, where Ln stands for heavy trivalent lanthanides or yttrium(III) (Tb–Lu, Y) and L is succinate, have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), infrared spectroscopy, TG-DTA coupled to FTIR, elemental analysis, X-ray powder diffractometry and complexometry were used to characterize and study the thermal behavior of these compounds. For the terbium to thulium and yttrium compounds, the dehydration, as well the thermal decomposition of the anhydrous compound occurs in two consecutive steps, while ytterbium and lutetium the dehydration occurs in a single step. The results also led to information about the ligand's denticity, thermal stability and thermal decomposition of these compounds

  12. Eye Findings on Vigabatrin and Taurine Treatment in Two Patients with Succinic Semialdehyde Dehydrogenase Deficiency.

    Science.gov (United States)

    Horvath, Gabriella-Ana; Hukin, Juliette; Stockler-Ipsiroglu, Sylvia G; Aroichane, Maryam

    2016-08-01

    We describe for the first time two patients with succinic semialdehyde dehydrogenase (SSADH) deficiency, who were found to have abnormal electroretinogram (ERG) examinations at baseline, or 6 months after vigabatrin treatment was started. This was somewhat reversible with L-taurine treatment, or minimally progressive. The mechanism of injury to the retina may be induced by elevations of γ-aminobutyric acid causing peripheral photoreceptor and ganglion cell damage, and this can be exacerbated by the use of vigabatrin. The use of taurine supplementation in tandem with vigabatrin may allow reversal of retinopathy and mitigate or slow down further deterioration. Further prospective clinical trials are required to evaluate this further. We recommend starting L-taurine therapy together with vigabatrin if a trial of vigabatrin is commenced in a patient with SSADH deficiency. Close monitoring of visual fields or ERG is also recommended at baseline and during vigabatrin therapy. PMID:27104484

  13. Hydrocortisone sodium succinate suppressed production of interleukin-10 by human peripheral blood mononuclear cells: clinical significance.

    Directory of Open Access Journals (Sweden)

    Kohka H

    1999-02-01

    Full Text Available Corticoids are well known for their immunosuppressive properties. Interleukin-10 (IL-10 is an intrinsic antiinflammatory peptide in immune diseases, originally identified as cytokine synthesis inhibitory factor. We examined the effect of hydrocortisone sodium succinate (HSS on the production of IL-10 by human peripheral blood mononuclear cells (PBMCs. PBMCs from healthy volunteers and cancer-burden patients were preincubated separately with or without HSS for 1 h, then stimulated with 5 microg/ml lipopolysaccharide (LPS. Production of IL-10 by human PBMCs was detected with LPS stimulation and its production was higher in cancer-burden patients than in normal volunteers, although this was not statistically significant. HSS suppressed production of IL-10 by LPS-stimulated PBMCs in a dose-dependent manner both in normal volunteers and in cancer-burden patients. These results indicate that, in addition to their antiinflammatory properties, corticoids act to restore the immunosuppressive states even in cancer-burden states.

  14. Growth, characterization and dielectric property studies of gel grown barium succinate single crystals

    Indian Academy of Sciences (India)

    M P Binitha; P P Pradyumnan

    2014-05-01

    Single crystals of barium succinate (BaC4H4O4) were grown in silica gel medium using controlled chemical reaction method. Plate-like single crystals of size up to 3 × 2 × 0.2 mm3 was obtained. Single crystal X-ray diffraction (XRD) studies confirmed that structure of the title compound is tetragonal. Powder X-ray diffraction (PXRD) pattern of the grown crystal and the Fourier transform infrared (FT–IR) spectrum in the range 400–4000 cm-1 are recorded. The vibrational bands corresponding to different functional groups are assigned. Thermal stability of the grown crystals is confirmed by differential scanning calorimetry (DSC). Dielectric constant and dielectric loss have been calculated and discussed as a function of frequency at different temperatures.

  15. Preparation of nanocomposites based on poly(Butylene Succinate) and montmorillonite organoclay via in situ polymerization

    International Nuclear Information System (INIS)

    Nanocomposites based on poly(butylene succinate) (PBS) and organophilic montmorillonite were synthesized via in situ polymerization using three different clay compositions (4, 6 and 8 wt%). The products were characterized by several different techniques. X-ray diffraction was useful to confirm the increase of the interlayer spacing of the clay due to the presence of the polymer chains among layers. Thermal analysis indicated that the polymerization method chosen led to materials with lower thermal stability compared to the pure PBS, due to the difficulty of chain growth in the presence of the clay. Low-field NMR technique was used to assess clay dispersion in the polymer, with exfoliated structures predominating in the nanocomposites. (author)

  16. FORMULATION AND RELEASE CHARACTERISTICS OF HPMC MATRIX TABLETS OF METOPROLOL SUCCINATE

    Directory of Open Access Journals (Sweden)

    Sobhita Rani P et al.

    2012-04-01

    Full Text Available The objective of this study was to design and evaluate oral sustained drug delivery system for Metoprolol succinate using pH sensitive polymer HPMC and sodium alginate and to evaluate its efficacy in reducing the hypertension. The drug filler blend was mixed with various concentrations of hydrophilic polymers such as HPMC, sodium alginate and combination of both the matrixing agents. The tablets were prepared by wet granulation method. Matrix tablets were evaluated for weight variation, content uniformity, friability, hardness, thickness, swelling index, and in vitro dissolution. The assays of different formulations were determined and the drug content was found between 85-115%. The weight variation was observed to be within the prescribed limits for each formulation. In-Vitro drug release studies carried out with different formulation tablets in 0.1N Hcl for 2hrs, pH 6.8 phosphate buffer for 12hrs. Up to 2 hr study the formulation shows low release in gastric medium (0.1N Hcl. From the 2 hr up to 12 hr study percentage of drug release was increased in intestinal fluid (pH 6.8 buffer. In these studies, the F1, F3 and F5 formulations showed the better drug release in compared to others. By swelling index it was concluded that the tablet shows matrix type of release in the intestine. These formulations follow zero order release kinetics known by Higuchi plot. The matrix formulation F1, F3 and F5 showed sustained release of Metoprolol succinate by the diffusion mechanism. Studies reveal that HPMC, sodium alginate sustained release matrix tablets can drive and make available the intact drug for local action for hypertension treatment.

  17. Identification of succinic semialdehyde reductases from Geobacter: expression, purification, crystallization, preliminary functional, and crystallographic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanfeng; Gao, Xiaoli; Zheng, Yi; Garavito, R. Michael (MSU)

    2012-04-30

    Succinic semialdehyde reductase (SSAR) is an important enzyme involved in {gamma}-aminobutyrate (GABA) metabolism. By converting succinic semialdehyde (SSA) to {gamma}-hydroxybutyrate (GHB), the SSAR facilitates an alternative pathway for GABA degradation. In this study, we identified SSARs from Geobacter sulfurreducens and Geobacter metallireducens (GsSSAR and GmSSAR, respectively). The enzymes were over-expressed in Escherichia coli and purified to near homogeneity. Both GsSSAR and GmSSAR showed the activity of reducing SSA using nicotinamide adenine dinucleotide phosphate as a co-factor. The oligomeric sizes of GsSSAR and GmSSAR, as determined by analytical size exclusion chromatography, suggest that the enzymes presumably exist as tetramers in solution. The recombinant GsSSAR and GmSSAR crystallized in the presence of NADP{sup +}, and the resulting crystals diffracted to 1.89 {angstrom} (GsSSAR) and 2.25 {angstrom} (GmSSAR) resolution. The GsSSAR and GmSSAR crystals belong to the space groups P2{sub 1}22{sub 1} (a = 99.61 {angstrom}, b = 147.49 {angstrom}, c = 182.47 {angstrom}) and P1 (a = 75.97 {angstrom}, b = 79.14 {angstrom}, c = 95.47 {angstrom}, {alpha} = 82.15{sup o}, {beta} = 88.80{sup o}, {gamma} = 87.66{sup o}), respectively. Preliminary crystallographic data analysis suggests the presence of eight protein monomers in the asymmetric units for both GsSSAR and GmSSAR.

  18. Hygroscopic growth and droplet activation of soot particles: uncoated, succinic or sulfuric acid coated

    Directory of Open Access Journals (Sweden)

    S. Henning

    2012-05-01

    Full Text Available The hygroscopic growth and droplet activation of uncoated soot particles and such coated with succinic acid and sulfuric acid were investigated during the IN-11 campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA facility. A GFG-1000 soot generator applying either nitrogen or argon as carrier gas and a miniCAST soot generator were utilized to generate soot particles. Different organic carbon (OC to black carbon (BC ratios were adjusted for the CAST-soot by varying the fuel to air ratio. The hygroscopic growth was investigated by means of the mobile Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile and two different Hygroscopicity Tandem Differential Mobility Analyzers (HTDMA, VHTDMA. Two Cloud Condensation Nucleus Counter (CCNC were applied to measure the activation of the particles. For the untreated soot particles neither hygroscopic growth nor activation was observed at a supersaturation of 1%, with exception of a partial activation of GFG-soot generated with argon as carrier gas. Coatings of succinic acid lead to a detectable hygroscopic growth of GFG-soot and enhanced the activated fraction of GFG- (carrier gas: argon and CAST-soot, whereas no hygroscopic growth of the coated CAST-soot was found. Sulfuric acid coatings led to an OC-content dependent hygroscopic growth of CAST-soot. Such a dependence was not observed for activation measurements. Coating with sulfuric acid decreased the amount of Polycyclic Aromatic Hydrocarbons (PAH, which were detected by AMS-measurements in the CAST-soot, and increased the amount of substances with lower molecular weight than the initial PAHs. We assume that these reaction products increased the hygroscopicity of the coated particles in addition to the coating substance itself.

  19. Hygroscopic growth and droplet activation of soot particles: uncoated, succinic or sulfuric acid coated

    Directory of Open Access Journals (Sweden)

    S. Henning

    2011-10-01

    Full Text Available The hygroscopic growth and droplet activation of uncoated soot particles and such coated with succinic acid and sulfuric acid were investigated during the IN-11 campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA facility. A GFG-1000 soot generator applying nitrogen, respectively argon as carrier gas and a miniCAST soot generator were utilized to generate soot particles. Different organic carbon (OC to black carbon (BC ratios were adjusted for the CAST-soot by varying the fuel to air ratio. The hygroscopic growth was investigated by means of the mobile Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile and two different Hygroscopicity Tandem Differential Mobility Analyzers (HTDMA, VHTDMA. Two Cloud Condensation Nucleus Counter (CCNC were applied to measure the activation of the particles. For the untreated soot particles neither hygroscopic growth nor activation was observed, with exception of a partial activation of GFG-soot generated with argon as carrier gas. Coatings of succinic acid lead to a detectable hygroscopic growth of GFG-soot and enhanced the activated fraction of GFG- (carrier gas: argon and CAST-soot, whereas no hygroscopic growth of the coated CAST-soot was found. Sulfuric acid coatings lead to an OC-content dependent hygroscopic growth of CAST-soot. Such a dependence was not observed for activation measurements. Coating with sulfuric acid decreased the amount of Polycyclic Aromatic Hydrocarbons (PAH, which were detected by AMS-measurements in the CAST-soot, and increased the amount of substances with lower molecular weight than the initial PAHs. We assume, that these reaction products increased the hygroscopicity of the coated particles in addition to the coating substance itself.

  20. Mechanical and thermal properties of basalt fiber reinforced poly(butylene succinate) composites

    International Nuclear Information System (INIS)

    Highlights: ► Novel basalt fiber-reinforced biodegradable poly(butylene succinate) composites have been successfully fabricated with various fiber loadings. ► The tensile and flexural properties of the PBS matrix resin are improved significantly by increasing the fiber loading in the composites. ► The impact strength of the BF/PBS composite decreases with the addition fibers primarily and increases with increasing fiber loading due to energy dissipation when the fibers are pulled out. ► Heat deflection temperature tests clearly show that the HDT of the basalt fiber reinforced PBS composites is significantly higher than the HDT of the PBS resin. - Abstract: Basalt fiber (BF) reinforced poly(butylene succinate) (PBS) composites have been fabricated with different fiber contents by a injection molding method and their tensile, flexural and impact properties, as well as thermal stability have been investigated. The tensile and flexural properties of the PBS matrix resin are improved markedly by increasing the fiber contents in the composites. The values are relatively higher than the natural fiber/PP systems reported earlier by other research groups. The heat deflection temperature (HDT) and Vicat softening temperature (VST) of the composites are significantly higher than those of the neat PBS resin. Scanning electron microscopy (SEM) conducted on the fracture surfaces of the composites reveals superior interfacial linkage between the basalt fibers and PBS matrix. The results suggest that the BF/PBS composites may be a potential candidate of PP or PP composites to manufacturing some daily commodities to solve the “white pollution” in environmental management.

  1. Succinate overproduction: A case study of computational strain design using a comprehensive Escherichia coli kinetic model

    Directory of Open Access Journals (Sweden)

    Ali eKhodayari

    2015-01-01

    Full Text Available Computational strain design prediction accuracy has been the focus for many recent efforts through the selective integration of kinetic information into metabolic models. In general, kinetic model prediction quality is determined by the range and scope of genetic and/or environmental perturbations used during parameterization. In this effort, we apply the k-OptForce procedure on a kinetic model of E. coli core metabolism constructed using the Ensemble Modeling (EM method and parameterized using multiple mutant strains data under aerobic respiration with glucose as the carbon source. Minimal interventions are identified that improve succinate yield under both aerobic and anaerobic conditions to test the fidelity of model predictions under both genetic and environmental perturbations. Under aerobic condition, k-OptForce identifies interventions that match existing experimental strategies pointing at a number of unexplored flux redirections such as routing glyoxylate flux through the glycerate metabolism to improve succinate yield. Many of the identified interventions rely on the kinetic descriptions and would not be discoverable by a purely stoichiometric description. In contrast, under fermentative (anaerobic conditions, k-OptForce fails to identify key interventions including up-regulation of anaplerotic reactions and elimination of competitive fermentative products. This is due to the fact that the pathways activated under anaerobic conditions were not properly parameterized as only aerobic flux data were used in the model construction. This study shed light on the importance of condition-specific model parameterization and provides insight onto how to augment kinetic models so as to correctly respond to multiple environmental perturbations.

  2. Targeting succinate:ubiquinone reductase potentiates the efficacy of anticancer therapy.

    Science.gov (United States)

    Kruspig, Björn; Valter, Kadri; Skender, Belma; Zhivotovsky, Boris; Gogvadze, Vladimir

    2016-08-01

    Mitochondria play a pivotal role in apoptosis: permeabilization of the outer mitochondrial membrane and the release of pro-apoptotic proteins from the intermembrane space of mitochondria are regarded as the key event in apoptosis induction. Here we demonstrate how non-toxic doses of the mitochondrial Complex II inhibitor thenoyltrifluoroacetone (TTFA), which specifically inhibits the ubiquinone-binding site of succinate dehydrogenase (SDH), synergistically stimulated cell death, induced by harmless doses of cisplatin in a panel of chemoresistant neuroblastoma cell lines. Apoptotic cell death was confirmed by cytochrome c release from the mitochondria, cleavage of poly ADP-ribose polymerase, processing of caspase-3, which is an important executive enzyme in apoptosis, and caspase-3-like activity. Methyl malonate, an inhibitor of the SDHA subunit partially reversed apoptosis stimulated by TTFA in SK-N-BE(2) neuroblastoma cells (NB), indicating that sensitization requires oxidation of succinate. In contrast, in IMR-32 NB cells, the same concentrations of TTFA markedly suppressed cisplatin-induced apoptosis. Comparison of oxygen consumption in cisplatin-resistant SK-N-BE(2) and cisplatin-sensitive IMR-32 cells clearly demonstrated impaired Complex II activity in IMR-32 cells. We also found that in SK-N-BE(2) cells co-treatment with cisplatin and TTFA markedly stimulated formation of reactive oxygen species (ROS), whereas in IMR cells, cisplatin-mediated ROS production was attenuated by TTFA, which explains apoptosis suppression in these cells. Thus, functionally active SDH is a prerequisite for the ROS-mediated sensitization to treatment by TTFA. PMID:27140478

  3. Biodegradable mesoporous calcium–magnesium silicate-polybutylene succinate scaffolds for osseous tissue engineering

    Directory of Open Access Journals (Sweden)

    Zhang X

    2015-10-01

    Full Text Available Xinxin Zhang,1,2,* Chi Zhang,3,* Wei Xu,1,* Biao Zhong,3 Feng Lin,3 Jian Zhang,3 Quanxiang Wang,4 Jiajin Ji,4 Jie Wei,4 Yang Zhang1 1TongRen Hospital, School of Medicine, Shanghai Jiao Tong University, 2Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 3Shanghai Sixth People’s Hospital, Shanghai Jiao Tong University, 4Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: The structural features of bone engineering scaffolds are expected to exhibit osteoinductive behavior and promote cell adhesion, proliferation, and differentiation. In the present study, we employed synthesized ordered mesoporous calcium–magnesium silicate (om-CMS and polybutylene succinate (PBSu to develop a novel scaffold with potential applications in osseous tissue engineering. The characteristics, in vitro bioactivity of om-CMS/PBSu scaffold, as well as the cellular responses of MC3T3-E1 cells to the composite were investigated. Our results showed that the om-CMS/PBSu scaffold possesses a large surface area and highly ordered channel pores, resulting in improved degradation and biocompatibility compared to the PBSu scaffold. Moreover, the om-CMS/PBSu scaffold exhibited significantly higher bioactivity and induced apatite formation on its surface after immersion in the simulated body fluid. In addition, the om-CMS/PBSu scaffold provided a high surface area for cell attachment and released Ca, Mg, and Si ions to stimulate osteoblast proliferation. The unique surface characteristics and higher biological efficacy of the om-CMS/PBSu scaffold suggest that it has great potential for being developed into a system that can be employed in osseous tissue engineering. Keywords: bone repair, polybutylene succinate, calcium–magnesium silicate, ordered mesoporous, proliferation

  4. Mechanical and thermal properties of basalt fiber reinforced poly(butylene succinate) composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yihe, E-mail: zyh@cugb.edu.cn [State Key Laboratory of Geological Processes and Mineral Resources, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Yu Chunxiao [State Key Laboratory of Geological Processes and Mineral Resources, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Lv Fengzhu [State Key Laboratory of Geological Processes and Mineral Resources, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China); Zhang Changan; Ji Junhui [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100101 (China); Zhang Rui [State Key Laboratory of Geological Processes and Mineral Resources, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China); Wang Heli [School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Novel basalt fiber-reinforced biodegradable poly(butylene succinate) composites have been successfully fabricated with various fiber loadings. Black-Right-Pointing-Pointer The tensile and flexural properties of the PBS matrix resin are improved significantly by increasing the fiber loading in the composites. Black-Right-Pointing-Pointer The impact strength of the BF/PBS composite decreases with the addition fibers primarily and increases with increasing fiber loading due to energy dissipation when the fibers are pulled out. Black-Right-Pointing-Pointer Heat deflection temperature tests clearly show that the HDT of the basalt fiber reinforced PBS composites is significantly higher than the HDT of the PBS resin. - Abstract: Basalt fiber (BF) reinforced poly(butylene succinate) (PBS) composites have been fabricated with different fiber contents by a injection molding method and their tensile, flexural and impact properties, as well as thermal stability have been investigated. The tensile and flexural properties of the PBS matrix resin are improved markedly by increasing the fiber contents in the composites. The values are relatively higher than the natural fiber/PP systems reported earlier by other research groups. The heat deflection temperature (HDT) and Vicat softening temperature (VST) of the composites are significantly higher than those of the neat PBS resin. Scanning electron microscopy (SEM) conducted on the fracture surfaces of the composites reveals superior interfacial linkage between the basalt fibers and PBS matrix. The results suggest that the BF/PBS composites may be a potential candidate of PP or PP composites to manufacturing some daily commodities to solve the 'white pollution' in environmental management.

  5. Micellar interactions in water-AOT based droplet microemulsions containing hydrophilic and amphiphilic polymers

    Science.gov (United States)

    Appel, Markus; Spehr, Tinka Luise; Wipf, Robert; Moers, Christian; Frey, Holger; Stühn, Bernd

    2013-11-01

    We investigate the influence of addition of hydrophilic and amphiphilic polymer on percolation behavior and micellar interactions in AOT-based water-in-oil droplet microemulsions. We focus on two series of samples having constant molar water to surfactant ratio W = 20 and constant droplet volume fraction Φ = 30%, respectively. From dielectric spectroscopy experiments, we extract the bending rigidity of the surfactant shell by percolation temperature measurements. Depending on droplet size, we find stabilization and destabilization of the surfactant shell upon addition of hydrophilic poly(ethylene glycol) (PEG) (Mn = 3100 g mol-1) and amphiphilic poly(styrene)-b-poly(ethylene glycol) copolymer with comparable length of the hydrophilic block. Complementary small angle X-ray scattering experiments corroborate the finding of stabilization for smaller droplets and destabilization of larger droplets. Subsequent analysis of dielectric spectra enables us to extract detailed information about micellar interactions and clustering by evaluating the dielectric high frequency shell relaxation. We interpret the observed results as a possible modification of the inter-droplet charge transfer efficiency by addition of PEG polymer, while the amphiphilic polymer shows a comparable, but dampened effect.

  6. Ultrasound-driven secondary self-assembly of amphiphilic β-cyclodextrin dimers.

    Science.gov (United States)

    Zhang, Hai-tao; Fan, Xiao-dong; Tian, Wei; Suo, Rong-tian; Yang, Zhen; Bai, Yang; Zhang, Wan-bin

    2015-03-23

    The controlled secondary self-assembly of amphiphilic molecules in solution is theoretically and practically significant in amphiphilic molecular applications. An amphiphilic β-cyclodextrin (β-CD) dimer, namely LA-(CD)2 , has been synthesized, wherein one lithocholic acid (LA) unit is hydrophobic and two β-CD units are hydrophilic. In an aqueous solution at room temperature, LA-(CD)2 self-assembles into spherical micelles without ultrasonication. The primary micelles dissociates and then secondarily form self-assemblies with branched structures under ultrasonication. The branched aggregates revert to primary micelles at high temperature. The ultrasound-driven secondary self-assembly is confirmed by transmission electron microscopy, dynamic light scattering, (1) H NMR spectroscopy, and Cu(2+) -responsive experiments. Furthermore, 2D NOESY NMR and UV/Vis spectroscopy results indicate that the formation of the primary micelles is driven by hydrophilic-hydrophobic interactions, whereas host-guest interactions promote the formation of the secondary assemblies. Additionally, ultrasonication is shown to be able to effectively destroy the primary hydrophilic-hydrophobic balances while enhancing the host-guest interaction between the LA and β-CD moieties at room temperature. PMID:25581876

  7. The effect of amphiphilic siloxane oligomers on fibroblast and keratinocyte proliferation and apoptosis.

    Science.gov (United States)

    Lynam, Emily C; Xie, Yan; Loli, Bree; Dargaville, Tim R; Leavesley, David I; George, Graeme A; Upton, Zee

    2010-11-01

    The formation of hypertrophic scars (HSF) is a frequent medical outcome of wound repair and often requires further therapy with treatments such as silicone gel sheets (SGS) or apoptosis-inducing agents, including bleomycin. Although widely used, knowledge regarding SGS and their mode of action is limited. Preliminary research has shown that small amounts of amphiphilic silicone present in SGS have the ability to move into skin during treatment. We demonstrate herein that a commercially available analogue of these amphiphilic siloxane species, the rake copolymer GP226, decreases collagen synthesis on exposure to cultures of fibroblasts derived from HSF. By size exclusion chromatography, GP226 was found to be a mixture of siloxane species, containing five fractions of different molecular weight. By studies of collagen production, cell viability and proliferation, it was revealed that a low molecular weight fraction (fraction IV) was the most active, reducing the number of viable cells present after treatment and thereby reducing collagen production as a result. On exposure of fraction IV to human keratinocytes, viability and proliferation were also significantly affected. HSF undergoing apoptosis after application of fraction IV were also detected via real-time microscopy and by using the TUNEL assay. Taken together, these data suggests that these amphiphilic siloxanes could be potential non-invasive substitutes to apoptotic-inducing chemical agents that are currently used as scar treatments. PMID:20725963

  8. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion.

    Science.gov (United States)

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible addition-fragment transfer (RAFT) polymerization, was confirmed by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). While the hydrophilic PMOEP block within the amphiphilic block copolymer strongly binds to the enamel surface, the PMMA block forms a hydrophobic shell to prevent acid attack on tooth enamel, thus preventing/reducing acid erosion. The polymer treatment not only effectively decreased the mineral loss of hydroxyapatite (HAP) by 36-46% compared to the untreated control, but also protected the surface morphology of the enamel specimen following exposure to acid. Additionally, experimental results confirmed that low pH values and high polymer concentrations facilitate polymer binding. Thus, the preliminary data suggests that this new amphiphilic diblock copolymer has the potential to be used as a non-fluoride ingredient for mouth-rinse or toothpaste to prevent/reduce tooth erosion. PMID:25419457

  9. Intrinsically disordered amphiphilic peptides as potential targets in drug delivery vehicles.

    Science.gov (United States)

    Vincenzi, Marian; Accardo, Antonella; Costantini, Susan; Scala, Stefania; Portella, Luigi; Trotta, Annamaria; Ronga, Luisa; Guillon, Jean; Leone, Marilisa; Colonna, Giovanni; Rossi, Filomena; Tesauro, Diego

    2015-11-01

    Intrinsically disordered proteins/peptides play a crucial role in many physiological and pathological events and may assume a precise conformation upon binding to a specific target. Recently, we have described the conformational and functional properties of two linear ester peptides provided with the following sequences: Y-G-E-C-P-C-K-OAllyl (PepK) and Y-G-E-C-P-C-E-OAllyl (PepE). Both peptides are characterized by the presence of the "CPC" motif together with a few amino acids able to promote disorder. The CPC sequence is a binding motif for the CXCR4 receptor that represents a well-known target for cancer therapies. In this paper, we report on synthetic amphiphilic peptides that consist of lipophilic derivatives of PepE and PepK bearing two stearic alkyl chains and/or an ethoxylic spacer. These peptide amphiphiles form stable supramolecular aggregates; they present conformational features that are typical of intrinsically disordered molecules as shown by CD spectroscopy. Solution fluorescence and DLS studies have been performed to evaluate Critical Micellar Concentrations and the dimension of supramolecular aggregates. Moreover, preliminary in vitro cell-based assays have been conducted to investigate the molecular recognition processes involving the CXCR4 receptor. In the end, the results obtained have been compared with the previous data generated by the corresponding non-amphiphilic peptides (PepE and PepK). PMID:26263446

  10. Self-Assembly of Discrete Metal Complexes in Aqueous Solution via Block Copolypeptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Timothy J. Deming

    2013-01-01

    Full Text Available The integration of discrete metal complexes has been attracting significant interest due to the potential of these materials for soft metal-metal interactions and supramolecular assembly. Additionally, block copolypeptide amphiphiles have been investigated concerning their capacity for self-assembly into structures such as nanoparticles, nanosheets and nanofibers. In this study, we combined these two concepts by investigating the self-assembly of discrete metal complexes in aqueous solution using block copolypeptides. Normally, discrete metal complexes such as [Au(CN2]−, when molecularly dispersed in water, cannot interact with one another. Our results demonstrated, however, that the addition of block copolypeptide amphiphiles such as K183L19 to [Au(CN2]− solutions induced one-dimensional integration of the discrete metal complex, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Transmission electron microscopy (TEM showed a fibrous nanostructure with lengths and widths of approximately 100 and 20 nm, respectively, which grew to form advanced nanoarchitectures, including those resembling the weave patterns of Waraji (traditional Japanese straw sandals. This concept of combining block copolypeptide amphiphiles with discrete coordination compounds allows the design of flexible and functional supramolecular coordination systems in water.

  11. Nanostructure protein repellant amphiphilic copolymer coatings with optimized surface energy by Inductively Excited Low Pressure Plasma.

    Science.gov (United States)

    Bhatt, Sudhir; Pulpytel, Jérome; Ceccone, Giacomo; Lisboa, Patricia; Rossi, François; Kumar, Virendra; Arefi-Khonsari, Farzaneh

    2011-12-01

    Statistically designed amphiphilic copolymer coatings were deposited onto Thermanox, Si wafer, and quartz crystal microbalance (QCM) substrates via Plasma Enhanced Chemical Vapor Deposition of 1H,1H,2H,2H-perfluorodecyl acrylate and diethylene glycol vinyl ether in an Inductively Excited Low Pressure Plasma reactor. Plasma deposited amphiphilic coatings were characterized by Field Emission Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Atomic Force Microscopy, and Water Contact Angle techniques. The surface energy of the coatings can be adjusted between 12 and 70 mJ/m(2). The roughness of the coatings can be tailored depending on the plasma mode used. A very smooth coating was deposited with a CW (continuous wave) power, whereas a rougher surface with R(a) in the range of 2 to 12 nm was deposited with the PW (pulsed wave) mode. The nanometer scale roughness of amphiphilic PFDA-co-DEGVE coatings was found to be in the range of the size of the two proteins namely BSA and lysozyme used to examine for the antifouling properties of the surfaces. The results show that the statistically designed surfaces, presenting a surface energy around 25 mJ/m(2), present no adhesion with respect to both proteins measured by QCM. PMID:22029599

  12. New Amphiphilic Polypyridyl Ruthenium(Ⅱ) Sensitizer and Its Application in Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    KONG Fan-Tai; DAI Song-Yuan; WANG Kong-Jia

    2007-01-01

    Amphiphilic polypyridyl ruthenium(Ⅱ) complex cis-di(isothiocyanato)(4,4'-di-tert-butyl-2,2'-bipyridyl)(4,4'-dicarboxy-2,2'-bipyridyl)ruthenium(Ⅱ) (K005) has been synthesized and characterized by cyclic voltammetry, 1H NMR, UV-Vis, and FT-IR spectroscopies. The sensitizer sensitizes TiO2 over a notably broad spectral range due to its intense metal-to-ligand charge-transfer (MLCT) bands at 537 and 418 nm. The photophysical and photochemical studies of K005 were contrasted with those of cis-Ru(dcbpy)2(NCS)2, known as the N3 dye, and the amphiphilic ruthenium(Ⅱ) dye Z907. A reversible couple at E1/2=0.725 V vs. saturated calomel electrode (SCE) with a separation of 0.08 V between the anodic and cathodic peaks, was observed due to the RuⅡ/Ⅲ couple by cyclic voltammetry.Furthermore, this amphiphilic ruthenium complex was successfully used as sensitizers for dye-sensitized solar cells with the efficiency of 3.72% at the 100 mW·cm-2 irradiance of air mass 1.5 simulated sunlight without optimization of TiO2 films and the electrolyte.

  13. A Phytic Acid Induced Super-Amphiphilic Multifunctional 3D Graphene-Based Foam.

    Science.gov (United States)

    Song, Xinhong; Chen, Yiying; Rong, Mingcong; Xie, Zhaoxiong; Zhao, Tingting; Wang, Yiru; Chen, Xi; Wolfbeis, Otto S

    2016-03-14

    Surfaces with super-amphiphilicity have attracted tremendous interest for fundamental and applied research owing to their special affinity to both oil and water. It is generally believed that 3D graphenes are monoliths with strongly hydrophobic surfaces. Herein, we demonstrate the preparation of a 3D super-amphiphilic (that is, highly hydrophilic and oleophilic) graphene-based assembly in a single-step using phytic acid acting as both a gelator and as a dopant. The product shows both hydrophilic and oleophilic intelligence, and this overcomes the drawbacks of presently known hydrophobic 3D graphene assemblies. It can absorb water and oils alike. The utility of the new material was demonstrated by designing a heterogeneous catalytic system through incorporation of a zeolite into its amphiphilic 3D scaffold. The resulting bulk network was shown to enable efficient epoxidation of alkenes without prior addition of a co-solvent or stirring. This catalyst also can be recovered and re-used, thereby providing a clean catalytic process with simplified work-up. PMID:26890034

  14. The search for new amphiphiles: synthesis of a modular, high-throughput library

    Directory of Open Access Journals (Sweden)

    George C. Feast

    2014-07-01

    Full Text Available Amphiphilic compounds are used in a variety of applications due to their lyotropic liquid-crystalline phase formation, however only a limited number of compounds, in a potentially limitless field, are currently in use. A library of organic amphiphilic compounds was synthesised consisting of glucose, galactose, lactose, xylose and mannose head groups and double and triple-chain hydrophobic tails. A modular, high-throughput approach was developed, whereby head and tail components were conjugated using the copper-catalysed azide–alkyne cycloaddition (CuAAC reaction. The tails were synthesised from two core alkyne-tethered intermediates, which were subsequently functionalised with hydrocarbon chains varying in length and degree of unsaturation and branching, while the five sugar head groups were selected with ranging substitution patterns and anomeric linkages. A library of 80 amphiphiles was subsequently produced, using a 24-vial array, with the majority formed in very good to excellent yields. A preliminary assessment of the liquid-crystalline phase behaviour is also presented.

  15. Peptide-based gemini amphiphiles: phase behavior and rheology of wormlike micelles.

    Science.gov (United States)

    Shrestha, Rekha Goswami; Nomura, Kazuyuki; Yamamoto, Masashi; Yamawaki, Yukio; Tamura, Yoshinaga; Sakai, Kenichi; Sakamoto, Kazutami; Sakai, Hideki; Abe, Masahiko

    2012-11-01

    Aqueous binary phase behavior of a peptide-based gemini amphiphile with glutamic acid and lysine as spacer group, acylglutamyllysilacylglutamate (m-GLG-m where m = 12, 14, and 16), has been reported over a wide range of concentration and temperature. Lauroylglutamyllysillauroylglutamate, 12-GLG-12, self-assembles into spherical micelles above critical micelle concentration (CMC). The micellar region extends up to 32 wt %, and an ordering of spherical micelles into micellar cubic phase, I(1), takes place at 33 wt % at 25 °C. The phase transition, I(1) - hexagonal liquid crystal, (H(1)) - lamellar liquid crystal, (L(α)) has been observed with further increase in concentration; moreover, mixed phases are also observed between the pure liquid crystal domains. Similar phases were observed with 16-GLG-16 above 50 °C (Krafft temperature). The partial ternary phase behavior shows that the micellar solutions of m-GLG-m can solubilize a large amount of cationic amphiphile, alkyltrimethylammonium bromide, C(n)TAB, (where n = 14 (TTAB) and 16 (CTAB)) at 25 °C. An addition of C(n)TAB to the aqueous solutions of 16-GLG-16 in a dilute region forms a transparent solution of viscoelastic wormlike micelles at very low concentration (0.25 wt %) even at ambient condition. A mixture of oppositely charged amphiphiles, m-GLG-m and C(n)TAB, exhibits synergism as a result the amphiphile layer curvature, becomes less positive, and favors the transition from sphere to rod to transient networks (wormlike micelles). The gemini amphiphile, 16-GLG-16, forms wormlike micelles at relatively low concentrations compared to others reported so far. Viscosity increases by six orders of magnitude compared to that of pure solvent. The hydrophobic chain length of m-GLG-m and coamphiphile affects the rheology; the maximum viscosity achieved with 16-GLG-16/H(2)O/CTAB is higher than that of 14-GLG-14/H(2)O/CTAB, 12-GLG-12/H(2)O/CTAB, and 16-GLG-16/H(2)O/TTAB systems. These temperature-sensitive systems

  16. The H+/O ratio of proton translocation linked to the oxidation of succinate by mitochondria. Reply to a commentary.

    Science.gov (United States)

    Lehninger, A L; Reynafarje, B; Hendler, R W; Shrager, R I

    1985-11-18

    Costa, L.E., Reynafarje, B. and Lehninger, A.L. [(1984) J. Biol. Chem. 259, 4802-4811] have reported 'second-generation' measurements of the H+/O ratio approaching 8.0 for vectorial H+ translocation coupled to succinate oxidation by rat liver mitochondria. In a Commentary in this Journal [Krab, K., Soos, J. and Wikström, M. (1984) FEBS Lett. 178, 187-192] it was concluded that the measurements of Costa et al. significantly overestimated the true H+/O stoichiometry. It is shown here that the mathematical simulation on which Krab et al. based this claim is faulty and that data reported by Costa et al. had already excluded the criticism advanced by Krab et al. Also reported are new data, obtained under conditions in which the arguments of Krab et al. are irrelevant, which confirm that the H+/O ratio for succinate oxidation extrapolated to level flow is close to 8. PMID:4065321

  17. Laminaria digitata as a potential carbon source for succinic acid and bioenergy production in a biorefinery perspective

    DEFF Research Database (Denmark)

    Alvarado-Morales, Merlin; Gunnarsson, Ingólfur Bragi; Fotidis, Ioannis;

    2015-01-01

    corresponded to 298 and 285 NmL CH4 g− 1 VSadded, respectively. PHSR could potentially be used for: dietary food additive, fish feed, bioenergy production and added value products. This study opens possibility to conceive different biorefinery scenarios in which the efficient use of the macroalgal biomass......A novel biorefinery concept utilizing macroalgae Laminaria digitata to produce succinic acid, and direct the process residues for feed and energy production, is investigated in the present study. Enzymatic hydrolysis was performed at high solid loading (25% w v− 1) resulting in solubilization of...... the carbohydrates to soluble sugars, which accumulated in the liquid hydrolysate. The overall sugar recovery in the macroalgae hydrolysate was 78.23%. Actinobacillus succinogenes 130Z was able to ferment macroalgae hydrolysate to succinic acid with a yield of 86.49% (g g− 1 of total sugars) and an...

  18. Structure Determination and Characterization of the Vitamin B[superscript 6] Degradative Enzyme (E)-2-(Acetamidomethylene)succinate Hydrolase

    Energy Technology Data Exchange (ETDEWEB)

    McCulloch, Kathryn M.; Mukherjee, Tathagata; Begley, Tadhg P.; Ealick, Steven E. (Cornell); (TAM)

    2010-06-22

    The gene identification and kinetic characterization of (E)-2-(acetamidomethylene)succinate (E-2AMS) hydrolase has recently been described. This enzyme catalyzes the final reaction in the degradation of vitamin B{sub 6} and produces succinic semialdehyde, acetate, ammonia, and carbon dioxide from E-2AMS. The structure of E-2AMS hydrolase was determined to 2.3 {angstrom} using SAD phasing. E-2AMS hydrolase is a member of the {alpha}/{beta} hydrolase superfamily and utilizes a serine/histidine/aspartic acid catalytic triad. Mutation of either the nucleophilic serine or the aspartate resulted in inactive enzyme. Mutation of an additional serine residue in the active site causes the enzyme to be unstable and is likely structurally important. The structure also provides insight into the mechanism of hydrolysis of E-2AMS and identifies several potential catalytically important residues.

  19. Absorbance Correction Method for Simultaneous Estimation of Nifedipine and Metoprolol Succinate in Their Synthetic Mixture Using From Spectrophotometry

    Directory of Open Access Journals (Sweden)

    Sojitra Rajanit

    2015-03-01

    Full Text Available A new simple, economical, precise and accurate method are described for the simultaneous determination of Nifedipine (NIF and Metoprolol Succinate (MET in combined tablet dosage form. The proposed method was applied for the determination of Nifedipine and Metoprolol Succinate in synthetic mixture, for determination of sampling wavelength, 10μg/ml of each of NIF and MET were scanned in 200-400 nm range and sampling wavelengths were 313nm for NIF and 275.40nm for MET are selected for development and validation of absorption correction method. For this method linearity observed in the range of 5-25μg/ml for NIF and 25- 125μg/ml for MET, and in their pharmaceutical formulation with mean percentage recoveries 100.68 and 100.33, respectively. The method was validated according to ICH guidelines and can be applied for routine quality control testing.

  20. Polymer blends of polylactic acid (PLA) and polybutylene succinate-adipate

    Science.gov (United States)

    Ma, Wenguang

    A series of blends consisting of polylactic acid (PLA) and aliphatic succinate polyester (BionolleRTM #3000) had been prepared and investigated. The results of mechanical property investigations showed that using 20 wt% Bionolle#3000 can significantly increase the toughness of PLA. BionolleRTM #3000 also reduces the physical aging rate of PLA so blends remain tough longer. Conversely, the stiffness of BionolleRTM #3000 can be significantly increased by blending in PLA. DMA and DSC results show that PLA/BionolleRTM 3000 blends are not thermodynamically miscible, but are compatible blends. Studies have also been performed to determine the amount and rate of aerobic biodegradation of PLA/aliphatic succinate polyester blends in biologically active composting, enzymatic, and soil environments. The changes in molecular weight, molecular structure and thermal properties in the composting environment were also studied by GPC, NMR and DSC analyses. The research results showed BionolleRTM #3000 had a high degradation rate, while PLA had a low degradation rate. PLA/BionolleRTM #3000 blends had moderate degradation rates that increased with BionolleRTM #3000 content. The melt flow behavior of PLA/BionolleRTM #3000 blends has been studied by capillary rheometry. The relationship of the blends' viscosity with their composition, shear stress, shear rate, and temperature has been investigated. Power law index and activation energy of PLA, BionolleRTM #3000 and their blends have been calculated. The experimental and theoretical data can let us understand the processability of PLA/BionolleRTM #3000 blends. A scanning electron microscope (SEM) was used to investigate the morphological structure of the PLA/BionolleRTM #3000 blends. Micrographs of the samples made from different methods (blown film, extrudate and compression molding sheet) were taken; their differences in morphology were compared. For comparison, the micrographs of blend PLA/BionolleRTM #6000 was also studied. The

  1. A hybrid of ant colony optimization and minimization of metabolic adjustment to improve the production of succinic acid in Escherichia coli.

    Science.gov (United States)

    Chong, Shiue Kee; Mohamad, Mohd Saberi; Mohamed Salleh, Abdul Hakim; Choon, Yee Wen; Chong, Chuii Khim; Deris, Safaai

    2014-06-01

    This paper presents a study on gene knockout strategies to identify candidate genes to be knocked out for improving the production of succinic acid in Escherichia coli. Succinic acid is widely used as a precursor for many chemicals, for example production of antibiotics, therapeutic proteins and food. However, the chemical syntheses of succinic acid using the traditional methods usually result in the production that is far below their theoretical maximums. In silico gene knockout strategies are commonly implemented to delete the gene in E. coli to overcome this problem. In this paper, a hybrid of Ant Colony Optimization (ACO) and Minimization of Metabolic Adjustment (MoMA) is proposed to identify gene knockout strategies to improve the production of succinic acid in E. coli. As a result, the hybrid algorithm generated a list of knockout genes, succinic acid production rate and growth rate for E. coli after gene knockout. The results of the hybrid algorithm were compared with the previous methods, OptKnock and MOMAKnock. It was found that the hybrid algorithm performed better than OptKnock and MOMAKnock in terms of the production rate. The information from the results produced from the hybrid algorithm can be used in wet laboratory experiments to increase the production of succinic acid in E. coli. PMID:24763079

  2. Evaluation of the efficacyof aminolevulinic acid-dependent photodynamic therapy on melanoma cancer cells treated with tocopherol succinate (in-vitro

    Directory of Open Access Journals (Sweden)

    Homa Kouchesfahani

    2012-01-01

    Full Text Available Background: Photodynamic therapy (PDT using 5-aminolevulinic acid (ALA to produce an intracellular photo-sensitizer, a protoporphyrin molecule IX (PPIX which absorbs light and targets cells, is a promising cancer treatment. Unfortunately, treatment failures are still a common occurrence when ALA is used. In this study, in order to enhance the efficacy of ALA-dependent photodynamic therapy, the effects of photodynamic therapy on melanoma cancer cells were studied after treating them with tocopherol succinate.Materials and Methods: In this experimental study melanoma cells were cultured in RPMI 1640 medium for 24 h. then, cells were treated with tocopherol succinate (6μm/ml. After 48 and 72 hours, the mediums were replaced by serum-free medium in the darkness, with ALA, 0.1mg/ml and then cells incubated for 4h. After that, cells were irradiated by using Nd: YAG laser (532 nm. After 24h, cell survival was measured by the MTT assay.Results: Twenty-four hours after PDT, among compared groups, pretreated cells with tocopherol succinate showed significant lower cell viability than control group. Conclusion: Induction of differentiation by using tocopherol succinate augmented intracellular PPIX accumulation in cells treated with ALA. Therefore phototoxic cell death after exposure to 532nm light enhances significantly in tocopherol succinate-pretreated cells. This study suggests that tocopherol succinate may act as a biological enhancer of ALA based photodynamic therapy

  3. Direct measurement of the initial proton extrusion to oxygen uptake ratio accompanying succinate oxidation by rat liver mitochondria.

    OpenAIRE

    Setty, O H; Shrager, R I; Bunow, B.; Reynafarje, B; Lehninger, A L; Hendler, R W

    1986-01-01

    The problem of obtaining very early ratios for the H+/O stoichiometry accompanying succinate oxidation by rat liver mitochondria was attacked using new techniques for direct measurement rather than extrapolations based on data obtained after mixing and the recovery of the electrode from initial injection of O2. Respiration was quickly initiated in a thoroughly mixed O2-containing suspension of mitochondria under a CO atmosphere by photolysis of the CO-cytochrome c oxidase complex-. Fast respo...

  4. Solution viscosity – molar mass relationships for poly(butylene succinate) and discussion on molar mass analysis

    OpenAIRE

    Q. Charlier; Girard, E; F. Freyermouth; M. Vandesteene; N. Jacquel; C. Ladaviere; Rousseau, A.; F. Fenouillot

    2015-01-01

    Poly(butylene succinate) (PBS) is currently developing due to its biodegradability and the similarity of its mechanical properties to those of polyolefins. Relationships between the number average molar mass, Mn, and solution viscosity such as [η] and ηred were derived for this aliphatic polyester. Mn values were determined by end-group analysis and size exclusion chromatography (SEC). Mark-Houwink-Sakurada (MHS) parameters were proposed in two solvents and for the different molar masses and ...

  5. Development and Validation of First Order Derivative Spectrophotometric method for simultaneous estimation of Nifedipine and Metoprolol Succinate in Synthetic Mixture

    OpenAIRE

    Sojitra Rajanit; Virani Paras; HashumatiRaj

    2015-01-01

    The present manuscript describe simple, sensitive, rapid, accurate, precise and economical first derivative spectrophotometric method for the simultaneous determination of Nifedipine (NIF)and Metoprolol Succinate (MET)in synthetic mixture. The derivative spectrophotometric method was based on the determination of both the drugs at their respective zero crossing point (ZCP). The first order derivative spectra was obtained in methanol and the determinations were made at 283.80 nm (ZCP of nifedi...

  6. DEVELOPMENT AND VALIDATION OF HPTLC METHOD FOR SIMULTANEOUS DETERMINATION OF METOPROLOL SUCCINATE AND ATORVASTATIN CALCIUM IN A PHARMACEUTICAL DOSAGE FORM

    OpenAIRE

    Ginoya Charmi G.; Dinesh V. Thakkar

    2013-01-01

    A new, simple, precise, accurate and selective high performance thin-layer chromatographic (HPTLC) method has been developed and validated for the simultaneous determination of Metoprolol succinate and Atorvastatin calcium in a marketed formulation. Chromatographic separation was carried out on Merck TLC aluminium sheets of silica gel 60F254 using Acetonitrile: Methanol: Ethyl acetate: Glacial acetic acid (2: 4: 4: 0.06 % v/v/v/v) as mobile phase followed by densitometric analysis at 223 nm. ...

  7. FORMULATION AND IN VITRO EVALUATION OF METOPROLOL SUCCINATE FLOATING TABLETS BY USING TWO VISCOSITY GRADE OF HPMC

    OpenAIRE

    Shubhrajit Mantry et al

    2012-01-01

    Metoprolol is a beta1-selective (cardio selective) adrenergic receptor blocking agent used in the treatment of Hypertension. The purpose of this investigation is to improve bioavailability by preparing a gastroretentive drug delivery system. Floating tablets of Metoprolol Succinate were prepared by employing two different grades of HPMC K4M and HPMC E15M in different concentrations by effervescent granulation technique. These grades of HPMC K4M and HPMC E15M were evaluated for their gel formi...

  8. Preparation and optimization of sustained release matrix tablets of metoprolol succinate and taro gum using response surface methodology

    OpenAIRE

    Soumya, M.; Y. A. Chowdary; V. Naga Swapna; N. D. Prathyusha; R. Geethika; B. Jyostna; K. Sai Krishna Mohan

    2014-01-01

    In the present study, an effort was made to formulate and evaluate matrix tablets of tarogum utilizing metaprolol succinate as the model drug. 3 2 full optimization procedure was adopted where two factors are studied at three levels. The amount of taro gum (X1) and polyvinylpyrrolidone (PVP) K30 (X2) were selected as independent variables. The time required for 90% of drug release was selected as the dependent variable. Tablets were prepared by direct compression and were evaluated for variou...

  9. Activation of Astroglial Calcium Signaling by Endogenous Metabolites Succinate and Gamma-Hydroxybutyrate in the Nucleus Accumbens

    OpenAIRE

    Molnár, Tünde; Héja, László; Emri, Zsuzsa; Simon, Ágnes; Nyitrai, Gabriella; Pál, Ildikó; Kardos, Julianna

    2011-01-01

    Accumulating evidence suggests that different energy metabolites play a role not only in neuronal but also in glial signaling. Recently, astroglial Ca2+ transients evoked by the major citric acid cycle metabolite succinate (SUC) and gamma-hydroxybutyrate (GHB) that enters the citric acid cycle via SUC have been described in the brain reward area, the nucleus accumbens (NAc). Cells responding to SUC by Ca2+ transient constitute a subset of ATP-responsive astrocytes that are activated in a neur...

  10. Activation of astroglial calcium signaling by endogenous metabolites succinate and gamma-hydroxybutyrate in the nucleus accumbens

    OpenAIRE

    Zsuzsa Emri; Julianna Kardos

    2011-01-01

    Accumulating evidence suggests that different energy metabolites play a role not only in neuronal but also in glial signalling. Recently, astroglial Ca2+ transients evoked by the major citric acid cycle metabolite succinate (SUC) and gamma-hydroxybutyrate (GHB) that enters the citric acid cycle via SUC have been described in the brain reward area, the nucleus accumbens (NAc). Cells responding to SUC by Ca2+ transient constitute a subset of ATP-responsive astrocytes that are activated in a neu...

  11. Poly(lactide)-g-poly(butylene succinate-co-adipate) with High Crystallization Capacity and Migration Resistance

    OpenAIRE

    Xi Yang; Huan Xu; Karin Odelius; Minna Hakkarainen

    2016-01-01

    Plasticized polylactide (PLA) with increased crystallization ability and prolonged life-span in practical applications due to the minimal plasticizer migration was prepared. Branched plasticized PLA was successfully obtained by coupling poly(butylene succinate-co-adipate) (PBSA) to crotonic acid (CA) functionalized PLA. The plasticization behavior of PBSA coupled PLA (PLA-CA-PBSA) and its counterpart PBSA blended PLA (PLA/PBSA) were fully elucidated. For both PLA-CA-PBSA and PLA/PBSA, a decre...

  12. S-nitrosylation of the Mitochondrial Chaperone TRAP1 Sensitizes Hepatocellular Carcinoma Cells to Inhibitors of Succinate Dehydrogenase

    DEFF Research Database (Denmark)

    Rizza, Salvatore; Montagna, Costanza; Cardaci, Simone;

    2016-01-01

    . We find that hepatocyte GSNOR deficiency is characterized by mitochondrial alteration and by marked increases in succinate dehydrogenase (SDH) levels and activity. We find that this depends on the selective S-nitrosylation of Cys(501) in the mitochondrial chaperone TRAP1, which mediates its......-nitrosylation in HCC, a novel molecular target in SDH, and a first-in-class therapy to treat the disease. Cancer Res; 76(14); 1-13. ©2016 AACR....

  13. Synthesis and characterization of poly(3-thiophene methyl acetate)/poly(tetramethylene succinate) nanomembranes. Biocompatibility and biodegradability assays

    OpenAIRE

    Pérez Madrigal, Maria del Mar

    2011-01-01

    The present study reports the fabrication of free-standing nanomembranes with semiconducting and biodegradable properties. Nanomembranes have been prepared by spin-coating mixtures of a semiconducting polythiophene derivative, poly(3-thiophene methyl acetate), and a biodegradable polyester, poly(tetramethylene succinate). Both the roughness and thickness of the nanomembranes, which ranged from 3 to 20 nm and from 20 to 80 nm, respectively, were precisely controlled through the spin-coater ...

  14. Construction of amphiphilic segments on polypropylene nonwoven surface and its application in removal of endocrine disrupting compounds (EDCs) from aqueous solution

    International Nuclear Information System (INIS)

    Highlights: • The amphiphilic segments on polypropylene nonwoven surface were constructed successfully. • The adsorption behavior for EDCs of the amphiphilic adsorption materials was systematically studied. • The novel amphiphilic adsorption materials have broad application prospects in EDCs removal from aqueous solution. - Abstract: The amphiphilic segments on polypropylene nonwoven (PP nonwoven) surface were constructed using the ultraviolet (UV) irradiation graft polymerization for the removal of endocrine disrupting compounds (EDCs) with different polarity from aqueous solution. The stearyl acrylate (SA) as hydrophobic functional monomer was introduced onto the surface of PP nonwoven fabric at first stage and then the hydroxyethyl acrylate (HEA) as hydrophilic functional monomer was introduced subsequently. The effect of functional monomer concentration and UV irradiation time on grafting ratio was studied and discussed. The novel amphiphilic structure was designed and constructed based on adsorption capacity for the target micropollutants. The structure and composition of the amphiphilic adsorption materials were characterized by Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle (CA). The adsorption behaviors for EDCs of the amphiphilic adsorption materials were studied and the results indicated that the adsorption capacity and adsorption rate were superior to single SA grafted PP nonwoven (PP-g-SA) and single HEA grafted PP nonwoven (PP-g-HEA). The novel amphiphilic adsorption material was efficient for the removal of EDCs with different polarity and could be utilized as a potential adsorption material for removing EDCs from aqueous solution

  15. Tipping the Scale from Disorder to Alpha-helix: Folding of Amphiphilic Peptides in the Presence of Macroscopic and Molecular Interfaces

    OpenAIRE

    Cahit Dalgicdir; Christoph Globisch; Christine Peter; Mehmet Sayar

    2015-01-01

    RESEARCH ARTICLE Tipping the Scale from Disorder to Alpha-helix: Folding of Amphiphilic Peptides in the Presence of Macroscopic and Molecular Interfaces Cahit Dalgicdir1, Christoph Globisch2, Christine Peter2*, Mehmet Sayar1* 1 College of Engineering, Koç University, Istanbul, Turkey, 2 Theoretical Chemistry, University of Konstanz, Konstanz, Germany * (CP); (MS) Abstract Secondary amphiphilicity is inherent to the...

  16. Construction of amphiphilic segments on polypropylene nonwoven surface and its application in removal of endocrine disrupting compounds (EDCs) from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kai [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Wei, Junfu, E-mail: junfuwei1963@163.com [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Zhou, Xiangyu [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Liu, Nana [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China)

    2015-05-15

    Highlights: • The amphiphilic segments on polypropylene nonwoven surface were constructed successfully. • The adsorption behavior for EDCs of the amphiphilic adsorption materials was systematically studied. • The novel amphiphilic adsorption materials have broad application prospects in EDCs removal from aqueous solution. - Abstract: The amphiphilic segments on polypropylene nonwoven (PP nonwoven) surface were constructed using the ultraviolet (UV) irradiation graft polymerization for the removal of endocrine disrupting compounds (EDCs) with different polarity from aqueous solution. The stearyl acrylate (SA) as hydrophobic functional monomer was introduced onto the surface of PP nonwoven fabric at first stage and then the hydroxyethyl acrylate (HEA) as hydrophilic functional monomer was introduced subsequently. The effect of functional monomer concentration and UV irradiation time on grafting ratio was studied and discussed. The novel amphiphilic structure was designed and constructed based on adsorption capacity for the target micropollutants. The structure and composition of the amphiphilic adsorption materials were characterized by Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle (CA). The adsorption behaviors for EDCs of the amphiphilic adsorption materials were studied and the results indicated that the adsorption capacity and adsorption rate were superior to single SA grafted PP nonwoven (PP-g-SA) and single HEA grafted PP nonwoven (PP-g-HEA). The novel amphiphilic adsorption material was efficient for the removal of EDCs with different polarity and could be utilized as a potential adsorption material for removing EDCs from aqueous solution.

  17. Bagasse hydrolyzates from Agave tequilana as substrates for succinic acid production by Actinobacillus succinogenes in batch and repeated batch reactor.

    Science.gov (United States)

    Corona-González, Rosa Isela; Varela-Almanza, Karla María; Arriola-Guevara, Enrique; Martínez-Gómez, Álvaro de Jesús; Pelayo-Ortiz, Carlos; Toriz, Guillermo

    2016-04-01

    The aim of this work was to obtain fermentable sugars by enzymatic or acid hydrolyses of Agave tequilana Weber bagasse in order to produce succinic acid with Actinobacillus succinogenes. Hydrolyses were carried out with mineral acids (sulfuric and hydrochloric acids) or a commercial cellulolytic enzyme, and were optimized statistically by a response surface methodology, having as factors the concentration of acid/enzyme and time of hydrolysis. The concentration of sugars obtained at optimal conditions for each hydrolysis were 21.7, 22.4y 19.8g/L for H2SO4, HCl and the enzymatic preparation respectively. Concerning succinic acid production, the enzymatic hydrolyzates resulted in the highest yield (0.446g/g) and productivity (0.57g/Lh) using A. succinogenes in a batch reactor system. Repeated batch fermentation with immobilized A. succinogenes in agar and with the enzymatic hydrolyzates resulted in a maximum concentration of succinic acid of 33.6g/L from 87.2g/L monosaccharides after 5 cycles in 40h, obtaining a productivity of 1.32g/Lh. PMID:26802183

  18. Self-assembly behavior of a linear-star supramolecular amphiphile based on host-guest complexation.

    Science.gov (United States)

    Wang, Juan; Wang, Xing; Yang, Fei; Shen, Hong; You, Yezi; Wu, Decheng

    2014-11-01

    A star polymer, β-cyclodextrin-poly(l-lactide) (β-CD-PLLA), and a linear polymer, azobenzene-poly(ethylene glycol) (Azo-PEG), could self-assemble into a supramolecular amphiphilic copolymer (β-CD-PLLA@Azo-PEG) based on the host-guest interaction between β-CD and azobenzene moieties. This linear-star supramolecular amphiphilic copolymer further self-assembled into a variety of morphologies, including sphere-like micelle, carambola-like micelle, naan-like micelle, shuttle-like lamellae, tube-like fiber, and random curled-up lamellae, by tuning the length of hydrophilic or hydrophobic chains. The variation of morphology was closely related to the topological structure and block ratio of the supramolecular amphiphiles. These self-assembly structures could disassemble upon an ultraviolet (UV) light irradiation. PMID:25310380

  19. Synthesis of Thermoresponsive Amphiphilic Polyurethane Gel as a New Cell Printing Material near Body Temperature.

    Science.gov (United States)

    Tsai, Yi-Chun; Li, Suming; Hu, Shiaw-Guang; Chang, Wen-Chi; Jeng, U-Ser; Hsu, Shan-hui

    2015-12-23

    Waterborne polyurethane (PU) based on poly(ε-caprolactone) (PCL) diol and a second oligodiol containing amphiphilic blocks was synthesized in this study. The microstructure was characterized by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and rheological measurement of the PU dispersion. The surface hydrophilicity measurement, infrared spectroscopy, wide-angle X-ray diffraction, mechanical and thermal analyses were conducted in solid state. It was observed that the presence of a small amount of amphiphilic blocks in the soft segment resulted in significant changes in microstructure. When 90 mol % PCL diol and 10 mol % amphiphilic blocks of poly(l-lactide)-poly(ethylene oxide) (PLLA-PEO) diol were used as the soft segment, the synthesized PU had a water contact angle of ∼24° and degree of crystallinity of ∼14%. The dispersion had a low viscosity below room temperature. As the temperature was raised to body temperature (37 °C), the dispersion rapidly (∼170 s) underwent sol-gel transition with excellent gel modulus (G' ≈ 6.5 kPa) in 20 min. PU dispersions with a solid content of 25-30% could be easily mixed with cells in sol state, extruded by a 3D printer, and deposited layer by layer as a gel. Cells remained alive and proliferating in the printed hydrogel scaffold. We expect that the development of novel thermoresponsive PU system can be used as smart injectable hydrogel and applied as a new type of bio-3D printing ink. PMID:26651013

  20. Effects of amphiphilic agent on thermal conductivity of boron nitride/poly(vinyl butyral) composites

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Hong Jun [Department of Materials Engineering, Kyonggi University, Suwon (Korea, Republic of); Cha, Sang-Ho [Department of Chemical Engineering, Kyonggi University, Suwon (Korea, Republic of); Lee, Woo Sung [Electronic Materials and Device Research Center, Korea Electronics Technology Institute, Seongnam (Korea, Republic of); Kim, Eung Soo, E-mail: eskim@kyonggi.ac.kr [Department of Materials Engineering, Kyonggi University, Suwon (Korea, Republic of)

    2014-09-10

    Highlights: • The platelet BN particles were oriented in poly(vinyl butyral) (PVB) matrix by tape-casting process. • The degree of BN orientation was estimated from XRD patterns of BN/PVB composites. • Surface treatment of BN with amphiphilic agent was confirmed by FT-IR and elemental analysis. • The BN/PVB composites with in-plane oriented 8-μm-sized BN particles showed a higher thermal conductivity than the other composites. - Abstract: Dependence of thermal conductivity of boron nitride (BN)/poly(vinyl butyral) (PVB) composites on the orientation and particle size of BN with an amphiphilic agent was investigated. The platelet BN particles were oriented in the polymer matrix by physical processes such as tape-casting process. A comparison of the thermal conductivity of the specimens with that of pristine BN showed that the BN/PVB composite treated with amphiphilic agents such as C{sub 14}H{sub 6}O{sub 8} and C{sub 27}H{sub 27}N{sub 3}O{sub 2} showed a higher thermal conductivity than the PVB composite with pristine BN. It was also found that the thermal conductivity of the C{sub 14}H{sub 6}O{sub 8}-treated BN/PVB composite was higher than that of the C{sub 27}H{sub 27}N{sub 3}O{sub 2}-treated composite due to the good dispersion and interfacial adhesion with C{sub 14}H{sub 6}O{sub 8}. Also, the thermal conductivity of the composite with an in-plane orientation of 8-μm-sized BN was higher than that of the composites with different particles sizes because of the improvement in the high degree of orientation.

  1. Structural transformation of peptide amphiphile self-assembly induced by headgroup charge and size regulation

    Science.gov (United States)

    Gao, Changrui; Bedzyk, Michael; Olvera, Monica; Kewalramani, Sumit; Palmer, Liam

    The ability to control the nano and the meso-scale architecture of molecular assemblies is one of the major challenges in nanoscience. Significantly, structural transformations of amphiphilic aggregates induced by variations in environmental conditions have attracted attention due to their biotechnological relevance. Here, we study the assembly in aqueous solution for a modular series of peptide amphiphiles with 3, 2 or 1 lysine groups conjugated to a C16 carbon tail (C16K3, C16K2 and C16K1) . This system design allow us to probe how the equilibrium structure of the self-assembly can be tuned by controlling the coupling between steric (via choice of headgroup: K3, K2, or K1) and electrostatic (via solution pH) interactions. Solution small- and wide-angle X-ray scattering (SAXS/WAXS) and transmission electron microscopy (TEM) studies reveal that depending on pH and number of lysines in the lipid headgroup, amphiphiles can assemble into a range of structures: spherical micelles, bilayer ribbons and vesicles. We also perform detailed phase space mapping of pH-and headgroup size dependency of the structures of assembly over 0.1-100 nm length scales via SAXS/WAXS. The experimental results in conjunction with molecular dynamics (MD) simulations deduce quantitative relations between pH-dependent molecular charges, steric constraints and self-assembly morphologies, which is significant for developing experimental routes to obtain assembly structures with specific nano- and meso-scale features through controlled external stimuli.

  2. A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion

    Directory of Open Access Journals (Sweden)

    William Gibbons

    2013-04-01

    Full Text Available One of the concerns for economical production of ethanol from biomass is the large volume and high cost of the cellulolytic enzymes used to convert biomass into fermentable sugars. The presence of acetyl groups in hemicellulose and lignin in plant cell walls reduces accessibility of biomass to the enzymes and makes conversion a slow process. In addition to low enzyme accessibility, a rapid deactivation of cellulases during biomass hydrolysis can be another factor contributing to the low sugar recovery. As of now, the economical reduction in lignin content of the biomass is considered a bottleneck, and raises issues for several reasons. The presence of lignin in biomass reduces the swelling of cellulose fibrils and accessibility of enzyme to carbohydrate polymers. It also causes an irreversible adsorption of the cellulolytic enzymes that prevents effective enzyme activity and recycling. Amphiphiles, such as surfactants and proteins have been found to improve enzyme activity by several mechanisms of action that are not yet fully understood. Reduction in irreversible adsorption of enzyme to non-specific sites, reduction in viscosity of liquid and surface tension and consequently reduced contact of enzyme with air-liquid interface, and modifications in biomass chemical structure are some of the benefits derived from surface active molecules. Application of some of these amphiphiles could potentially reduce the capital and operating costs of bioethanol production by reducing fermentation time and the amount of enzyme used for saccharification of biomass. In this review article, the benefit of applying amphiphiles at various stages of ethanol production (i.e., pretreatment, hydrolysis and hydrolysis-fermentation is reviewed and the proposed mechanisms of actions are described.

  3. Plasmonic Vesicles of Amphiphilic Nanocrystals: Optically Active Multifunctional Platform for Cancer Diagnosis and Therapy.

    Science.gov (United States)

    Song, Jibin; Huang, Peng; Duan, Hongwei; Chen, Xiaoyuan

    2015-09-15

    Vesicular structures with compartmentalized, water-filled cavities, such as liposomes of natural and synthetic amphiphiles, have tremendous potential applications in nanomedicine. When block copolymers self-assemble, the result is polymersomes with tailored structural properties and built-in releasing mechanisms, controlled by stimuli-responsive polymer building blocks. More recently, chemists are becoming interested in multifunctional hybrid vesicles containing inorganic nanocrystals with unique optical, electronic, and magnetic properties. In this Account, we review our recent progress in assembling amphiphilic plasmonic nanostructures to create a new class of multifunctional hybrid vesicles and applying them towards cancer diagnosis and therapy. Localized surface plasmon resonance (LSPR) gives plasmonic nanomaterials a unique set of optical properties that are potentially useful for both biosensing and nanomedicine. For instance, the strong light scattering at their LSPR wavelength opens up the applications of plasmonic nanostructures in single particle plasmonic imaging. Their superior photothermal conversion properties, on the other hand, make them excellent transducers for photothermal ablation and contrast agents for photoacoustic imaging. Of particular note for ultrasensitive detection is that the confined electromagnetic field resulting from excitation of LSPR can give rise to highly efficient surface enhanced Raman scattering (SERS) for molecules in close proximity. We have explored several ways to combine well-defined plasmonic nanocrystals with amphiphilic polymer brushes of diverse chemical functionalities. In multiple systems, we have shown that the polymer grafts impart amphiphilicity-driven self-assembly to the hybrid nanoparticles. This has allowed us to synthesize well-defined vesicles in which we have embedded plasmonic nanocrystals in the shell of collapsed hydrophobic polymers. The hydrophilic brushes extend into external and interior aqueous

  4. Two-dimensional crystallography of amphiphilic molecules at the air-water interface

    DEFF Research Database (Denmark)

    Jacquemain, D.; Grayer Wolf, S.; Leveiller, F.; Deutsch, M.; Kjær, K.; Als-Nielsen, J.; Lahav, M.; Leiserowitz, L.

    1992-01-01

    review recent results obtained from them for Langmuir films. The methods have been successfully applied in the elucidation of the structure of crystalline aggregates of amphiphilic molecules such as alcohols, carboxylic acids and their salts, alpha-amino acids, and phospholipids at the water surface. In...... solute species. Examples are given where singly or doubly charged ions bound to the two-dimensional (2D) crystal form either an ordered or diffuse counterionic layer. Finally, the surface diffraction methods provide data on transfer of structural information from 2D clusters to 3D single crystals, which...... had been successfully accomplished by epitaxial-like crystallization both in organic and inorganic crystals....

  5. Control of structure and growth of polymorphic crystalline thin films of amphiphilic molecules on liquid surfaces

    DEFF Research Database (Denmark)

    Weinbach, S.P.; Kjær, K.; Bouwman, W.G.;

    1994-01-01

    The spontaneous formation and coexistence of crystalline polymorphic trilayer domains in amphiphilic films at air-liquid interfaces is demonstrated by grazing incidence synchrotron x-ray diffraction. These polymorphic crystallites may serve as models for the early stages of crystal nucleation and...... growth, helping to elucidate the manner in which additives influence the progress of crystal nucleation, growth, and polymorphism and suggesting ways of selectively generating and controlling multilayers on liquid surfaces. Auxiliary molecules have been designed to selectively inhibit development of the...

  6. Self-assembling Behavior of Amphiphilic Copolymer Containing Cross-linked Hydrophilic Block in Ethanol

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The self-assembly behavior of the amphiphilic block copolymer poly( methyl methacrylate)-block-poly( lead dimethacrylate) (PMMA-b-PLDMA) with cross-linked hydrophilic block (PLDMA) in ethanol was investigated. The results show that the size and morphology of the resulting micelle or micellar aggregates are ascribed to the content of ethanol and the nature of the solvent mixture. PbS nanoparticles were formed in the micelle by in situ reaction with H2S gas. The morphology and size of the self-assembly objects were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  7. A spectroscopic method to estimate the binding potency of amphiphile assemblies

    Czech Academy of Sciences Publication Activity Database

    Gauger, D. R.; Andrushchenko, Valery; Bouř, Petr; Pohle, W.

    2010-01-01

    Roč. 398, č. 2 (2010), s. 1109-1123. ISSN 1618-2642 R&D Projects: GA ČR GA203/06/0420; GA ČR GA202/07/0732; GA ČR GAP208/10/0559; GA AV ČR IAA400550702; GA AV ČR IAA400550701 Institutional research plan: CEZ:AV0Z40550506 Keywords : miccels * amphiphile assemblies * molecular dynamics * infrared spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.841, year: 2010

  8. Theoretical estimation of the critical packing parameter of amphiphilic self-assembled aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, Rabah A., E-mail: rakhalil64@yahoo.com; Zarari, Al-hakam A.

    2014-11-01

    Graphical abstract: - Highlights: • Critical packing parameter (p) is an important property for self-assembled aggregate. • Up to date, the estimation of p is regarded as hypothetical rather than empirical. • The results announce the possibility of predicting p theoretically using DFT method. • Possibility of employing the evaluation of p through computational chemistry software. • Valuable thermodynamic information about the self-assembly may be obtained from determined p. - Abstract: The estimating of critical packing parameter (p) of amphiphilic compounds is considered as a hypothetical rather than an empirical. Consequently, an attempt has been made for determining such a dimensionless parameter for homologous series of sodium p-n-alkyl benzoates (n = 0–8) hydrotropes using quantum mechanical calculations that depend on density functional theory (DFT). The calculations were based on the following well-defined model, p = v/a{sub 0}l{sub c}, where v is the volume of the hydrotrope tail, a{sub 0} is the effective head group area and l{sub c} is the length of the extended hydrotrope tail. It was found that the magnitude of both v and l{sub c} parameters can be estimated directly from quantum mechanical calculations. While the investigations found that the a{sub 0} parameter is parallel to the Connolly solvent accessible surface area (C{sub sa}) which could also be determined through theoretical computations. The obtained results were in good agreement with published data using small angle neutron scattering (SANS) technique. Hence, the theoretical model for predicting p of amphiphilic at critical micelle- or aggregation-concentration (cmc or cac) is p = v/C{sub sa}l{sub c}. An apparent success was observed through applying this simple model to some randomly selected surfactants. It has been concluded that the theoretical calculations that based on quantum mechanical (DFT) method can be considered as a powerful tool for estimating the critical packing

  9. Macroscopic alignment of graphene stacks by Langmuir-Blodgett deposition of amphiphilic hexabenzocoronenes

    DEFF Research Database (Denmark)

    Laursen, B.W.; Nørgaard, K.; Reitzel, N.;

    2004-01-01

    e present structural studies of Langmuir V and Langmuir-Blodgett (LB) films of new amphiphilic hexa-peri-hexabenzocoronene (HBC) discotics, carrying five branched alkyl side chains and one polar group. The polar group is either a carboxylic acid moiety or an electron acceptor moiety (anthraquinone...... tilted relative to the water surface. The intercolumnar distance is 20 A. The HBCs are confined to a layer lying on top of the layer of polar groups that are in contact with the water subphase. Efficient transfer of the monolayer of the anthraquinone-substituted HBC derivative to hydrophobic quartz...

  10. Small angle neutron scattering study of the micelle structure of amphiphilic block copolymers

    International Nuclear Information System (INIS)

    The amphiphilic block copolymers of vinyl ether were prepared by living cationic polymerization. The partially deuterated copolymers for SANS experiments were especially synthesized by introducing deuterated phenyl units in the hydrophobic chain. SANS measurements were performed for aqueous solutions of these copolymers by changing H2O/D2O ratios. The SANS profiles indicate that the micelles in the present system exhibit a core-shell structure and that the size and shape of micelles are largely dependent on the length of hydrophobic chain. The micelle of shorter hydrophobic chain was found to be nearly spherical, whereas the micelle of longer hydrophobic chain was confirmed to have an ellipsoidal shape

  11. Synthesis, Characterization, Critical Micelle Concentration and Biological Activity of two-Headed Amphiphiles

    OpenAIRE

    Actis, Marcelo

    2008-01-01

    In this project, we synthesized a new homologous series of five long-chain, two-headed amphiphiles [2CAm13, 2CAm15, 2CAm17, 2CAm19, 2CAm21; CH3(CH2)n-1CONHC(CH3)(CH2CH2COOH)2, n = 13, 15, 17, 19, 21]. The synthesis of the 2CAmn series was accomplished in four steps. The first step involves a reaction of nitroethane and two equivalents of tert-butyl acrylate to create the nitrodiester synthon [O2NC(CH3)(CH2CH2COOtBu)2] by successive Michael additions. The second step in the synthesi...

  12. Amphiphilic copolymer coated upconversion nanoparticles for near-infrared light-triggered dual anticancer treatment

    Science.gov (United States)

    Yang, Shun; Li, Najun; Liu, Zhuang; Sha, Wenwei; Chen, Dongyun; Xu, Qingfeng; Lu, Jianmei

    2014-11-01

    The light-triggered controlled release of anticancer drugs accompanied with NIR-responsive photodynamic therapy was prepared via a self-assembly process. Firstly, Mn2+-doped upconversion nanoparticles (UCNPs) were coated with a mesoporous silica shell and modified with photosensitizer (Chlorin e6) and long alkyl chains. And then the NIR light-responsive amphiphilic copolymer containing 9,10-dialkoxyanthracene groups was synthesized and then coated as the outermost layer. Upon irradiation with a 980 nm laser, the CCUCNPs@PM would absorb and then convert the NIR light to higher-energy visible red light (660 nm) via the UCNPs-based core, which could excite Chlorin e6 (Ce-6) to produce singlet oxygen (1O2). Then the 1O2-sensitive dialkoxyanthracene group in the amphiphilic copolymer would be degraded and detach from the surface of the CCUCNPs@PM, followed by the controlled release of the pre-loaded drugs and the photodynamic therapy for cancer cells caused by the excess 1O2. In vitro and in vivo experiments also demonstrated that the drug-loaded CCUCNPs@PM possessed better therapeutic efficacy compared with vacant ones. Therefore, the NIR light-controlled chemotherapy and photodynamic therapy could be realized simultaneously by CCUCNPs@PM.The light-triggered controlled release of anticancer drugs accompanied with NIR-responsive photodynamic therapy was prepared via a self-assembly process. Firstly, Mn2+-doped upconversion nanoparticles (UCNPs) were coated with a mesoporous silica shell and modified with photosensitizer (Chlorin e6) and long alkyl chains. And then the NIR light-responsive amphiphilic copolymer containing 9,10-dialkoxyanthracene groups was synthesized and then coated as the outermost layer. Upon irradiation with a 980 nm laser, the CCUCNPs@PM would absorb and then convert the NIR light to higher-energy visible red light (660 nm) via the UCNPs-based core, which could excite Chlorin e6 (Ce-6) to produce singlet oxygen (1O2). Then the 1O2-sensitive

  13. Effect of N-terminal amphiphilic peptide region on aggregation of ovalbumin

    International Nuclear Information System (INIS)

    Aggregation of protein is widely observed in our daily life. For example, cooking is manipulation of protein state. Main cause of various human diseases such as Alzheimer’s and Parkinson’s diseases is also considered to be aggregation of protein. One of model proteins is ovalbumin (OVA), which is a major protein in egg white. An OVA aqueous solution aggregates at high temperature and forms gel like sunny-side up above the threshold concentration. This phenomenon has been researched thoroughly from the viewpoint of turbidity, rheology, spectroscopy, scattering and so on. Then we, as chemists, think the next step for this research is manipulation of the aggregation state by modifying the chemical structure. Kawachi et al. concentrated on the N-terminal amphiphilic peptide region (pN1-22) and proved that this peptide region enhances the strength of OVA gel from the viewpoint of rheology. In contrast, aggregation ability of OVA without this peptide region (pOVA) is dramatically reduced. We assume that the reason for this phenomenon originates from the amphiphilic nature of the peptide. The aim of this research is to clarify the role of pN1-22 and the relationship between the microscopic chemical structure and the macroscopic physical properties. To clarify the mesoscopic structure, we conducted a SANS measurement at GP-SANS, High Flux Isotope Reactor at ORNL. Samples are solutions or gels of OVA, pOVA, peptide and their mixture with various concentrations before and after heating. pH of samples was set to 7, which is common condition for the application of OVA and their derivatives. We observed a strong upturn at low-q region in SANS curves for pOVA solutions/gels after heating. This behavior is similar to a phase separation of well-known poly(N-isopropylacrylamide) (PNIPA) solutions. From this result, we can see that the lack of amphiphilic peptide region makes the OVA solute unstable and promotes aggregation. In contrast to this, addition of amphiphilic peptide

  14. Lattice-Gas Simulations of Ternary Amphiphilic Fluid Flow in Porous Media

    CERN Document Server

    Coveney, P V; Wilson, J L; Fowler, P W; Al-Mushadani, O; Boghosian, B M

    1998-01-01

    We develop our existing two-dimensional lattice-gas model to simulate the flow of single-phase, binary-immiscible and ternary-amphiphilic fluids. This involves the inclusion of fixed obstacles on the lattice, together with the inclusion of ``no-slip'' boundary conditions. Here we report on preliminary applications of this model to the flow of such fluids within model porous media. We also construct fluid invasion boundary conditions, and the effects of invading aqueous solutions of surfactant on oil-saturated rock during imbibition and drainage are described.

  15. Water-repellent textile via decorating fibers with amphiphilic Janus particles.

    Science.gov (United States)

    Synytska, Alla; Khanum, Rina; Ionov, Leonid; Cherif, Chokri; Bellmann, C

    2011-04-01

    We investigated morphology and wetting properties of textiles modified by chemically immobilized amphiphilic micrometer and submicrometer large Janus particles. The Janus particles bind by their reactive side to the textile surface, while their hydrophobic side faces the environment. It was found that the character of immobilization of the Janus particles on textile depends on their size: larger particles bind between fibers, while smaller ones bind to the fiber surface. In both cases, immobilization of Janus particles results in the hydrophobization of the hydrophilic textile surface. Finally, we demonstrated that submicrometer large Janus particles are very efficient for the design of water-repellent textiles. PMID:21366338

  16. Mobilization and biodegradation of 2-methylnaphthalene by amphiphilic polyurethane nano-particle.

    Science.gov (United States)

    Kim, Young-Bum; Kim, Ju-Young; Kim, Eun-ki

    2009-10-01

    Amphiphilic polyurethane (APU) nano-particle enhanced the mobilization of 2-methylnaphthalene (2-MNPT) in soil. Significant increase in the solubility of 2-MNPT was achieved. The molar solubilization ratio was 0.4 (mole 2-MNPT/mole APU). Simple precipitation of APU particle by 2 N CaCl(2) recovered 95% of APU particle and 92% of 2-MNPT simultaneously. Also, 2-MNPT, which was entrapped inside the APU particle, was directly degraded by Acinetobacter sp. as same efficiency as without APU particle. These results showed the potentials of APU particle in the mobilization and biodegradation of hydrophobic compounds from soil. PMID:19214790

  17. The degradation and adsorption behaviors of enzyme on poly(butylene succinate) single crystals.

    Science.gov (United States)

    Jiang, Xi; Yang, Ju-Ping; Wang, Xiao-Hong; Zhou, Jian-Jun; Li, Lin

    2009-12-01

    The enzymatic degradation behavior of poly(butylene succinate) (PBS) single crystals with a lipase from Pseudomonas cepacia (lipase PS) is monitored using atomic force microscopy (AFM) in phosphate buffer at pH 6.8 and 40 degrees C. In-situ AFM results show that enzymatic degradation of the single crystal starts from the crystal edges rather than the chain-folded surfaces and the lamellar thickness remains constant during the whole degradation process. Total internal reflection fluorescence microscopy (TIRFM) is used for the first time to study the adsorption behavior of lipase onto the PBS crystal surface. The results clearly show that the enzyme molecules preferentially adsorb on the lateral surfaces of the single crystal but not on the chain-folded surfaces. AFM force-distance curve measurements and force-volume imaging obtained using a lipase-immobilized AFM tip show that small and large adhesive forces exist in the flat-on and edge-on areas of a PBS banded spherulite, respectively, which correspond to the chain-folded surface and lateral edges of a single crystal. PMID:19953521

  18. A study on reactive blending of (poly lactic acid) and poly (butylene succinate co adipate)

    Science.gov (United States)

    Bureepukdee, C.; Suttiruengwong, S.; Seadan, M.

    2015-07-01

    This research aims to study the blending of Polylactic acid (PLA) and Polybutylene succinate co adipate (PBSA) in order to understand the role of peroxide in free radical reaction on the compatibilization between these two biodegradable polyesters. Various ratios of PLA/PBSA blends with and without reactive agents were prepared in the twin screw extruder. Two types of peroxides, Di (tert-butylperoxyisopropyl) benzene (DTBP) and 2, 5-Dimethyl-2, 5-(t-butylperoxy) hexane (DTBH), were used with various concentrations to compare. From the torques measurement, DTBP was more reactive with PLA and PBSA than DTBH. PLA and PBSA 80:20, 60:40, 50:50, 40:60, and 20:80% by weight were melt-blended in a twin screw extruder. The reactive polymer blends were also prepared for the same ratios of the blends with addition of 0.08 and 0.1 phr of DTBP. The mechanical, thermal, rheological, and morphological properties were investigated. The impact strengths of the non-reactive blend increased with the increasing in PBSA content. The optimal impact strength was obtained at 40%wt of PBSA with 0.1 phr of DTBP. Adding 0.08 and 0.1 phr of DTBP led to the co continuous phase morphology of PLA/PBSA blends. The per cent crystallinity of PLA increased when blended with PBSA. PBSA might induce the crystallization of PLA.

  19. Tabletability assessment of conventional formulations containing Vitamin E tocopheryl polyethylene glycol succinate.

    Science.gov (United States)

    Jin, Feiyan; Tatavarti, Aditya

    2010-04-15

    Vitamin E tocopheryl polyethylene glycol succinate (TPGS) is known to enhance the bioavailability of poorly water-soluble drugs via solubility and permeability enhancement. Few studies have evaluated feasibility of formulating TPGS in conventional solid dosage forms such as tablets due to processing challenges resulting from its waxy nature and low melting point (approximately 37 degrees C). The objective of this study is to systematically investigate the tabletability of conventional high shear wet granulation (WG) formulations incorporated with Vitamin E TPGS. Impact of critical formulation variables such as levels of TPGS, hydroxypropyl cellulose (binder) and Prosolv (extragranular filler) on product quality attributes was studied using a full factorial experimental design. The potential influence of temperature elevation during processing was assessed through a heated die fitted onto a compaction simulator. Bilayer tabletability of the TPGS formulation was also assessed in combination with a secondary non-TPGS formulation. TPGS levels significantly impacted tensile strength (TS), disintegration time and dissolution. Heat sensitivity studies indicated that TS reduction upon exposure to heat was minimized by higher levels of extragranular fillers. Acceptable interfacial strength of bilayer tablets was achieved and tablets could be coated without the need for hydroalcoholic solutions. The study demonstrates preliminary feasibility to develop monolithic and bilayer coated tablet formulations containing up to 10% (w/w) TPGS for the given compound and drug load. Further studies are required to validate these findings at larger scales. PMID:20083178

  20. Succinate Dehydrogenase B Subunit Immunohistochemical Expression Predicts Aggressiveness in Well Differentiated Neuroendocrine Tumors of the Ileum

    International Nuclear Information System (INIS)

    Immunohistochemical loss of the succinate dehydrogenase subunit B (SDHB) has recently been reported as a surrogate biomarker of malignancy in sporadic and familial pheocromocytomas and paragangliomas through the activation of hypoxia pathways. However, data on the prevalence and the clinical implications of SDHB immunoreactivity in ileal neuroendocrine tumors are still lacking. Thirty-one consecutive, advanced primary midgut neuroendocrine tumors and related lymph node or liver metastases from 24 males and seven females were immunohistochemically assessed for SDHB. All patients were G1 tumors (Ki-67 labeling index ≤2%). SDHB immunohistochemistry results were expressed as immunostaining intensity and scored as low or strong according to the internal control represented by normal intestinal cells. Strong positivity for SDHB, with granular cytoplasmatic reactivity, was found in 77% of primary tumors (T), whilst low SDHB expression was detected in 90% of metastases (M). The combined analysis (T+M) confirmed the loss of SDHB expression in 82% of metastases compared to 18% of primary tumors. SDHB expression was inversely correlated with Ki-67 labeling index, which accounted for 1.54% in metastastic sites and 0.7% in primary tumors. A correlation between SDHB expression loss, increased Ki-67 labeling index and biological aggressiveness was shown in advanced midgut neuroendocrine tumors, suggesting a role of tumor suppressor gene

  1. Non-isothermal melt crystallization of poly(tetramethylene succinate) under high pressure: Characterization and kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Rohindra, David [Graduate School of Engineering, Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-S8-33, O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); School of Biological and Chemical Sciences, Faculty of Science, Technology and Environment, The University of the South Pacific, Suva (Fiji); Kuboyama, Keiichi [Graduate School of Engineering, Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-S8-33, O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Ougizawa, Toshiaki, E-mail: tougizawa@op.titech.ac.jp [Graduate School of Engineering, Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-S8-33, O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2012-10-10

    Highlights: Black-Right-Pointing-Pointer Non-isothermal crystallization of PTMS under high pressure is reported. Black-Right-Pointing-Pointer Nucleation pattern analyzed using Ozawa model. Black-Right-Pointing-Pointer Crystallization and nucleation behavior changed above 300 MPa. - Abstract: The non-isothermal melt crystallization behavior (characterization and kinetics) of poly(tetramethylene succinate) (PTMS) under high pressure was investigated using high pressure differential thermal analysis (HP-DTA). Wide angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and density measurement were used to study the crystal structure, the melting temperature and the morphology of the samples crystallized under various pressures. No new crystal structure or formation of extended chain crystals were found in the pressure crystallized samples. Optical micrographs revealed nucleation density decreased and spherulite morphology changed (presence of banding pattern) above 300 MPa. DTA crystallization curves showed a single exothermic peak at all pressures which shifted to higher temperatures with increasing pressure and became broad above 300 MPa. The kinetics was studied using the Ozawa model. A change in the nucleation pattern was predicted from the Ozawa exponent, instantaneous at low pressures and sporadic above 300 MPa. From kinetic and morphological results it was found that a critical pressure region existed around 300 MPa.

  2. Thermal and Mechanical Properties of Poly(butylene succinate Films Reinforced with Silica

    Directory of Open Access Journals (Sweden)

    Sangviroon Nanthaporn

    2015-01-01

    Full Text Available In recent year, bioplastics have become more popular resulting from the growing concerns on environmental issues and the rising fossil fuel price. However, their applications were limited by its mechanical and thermal properties. The aim of this research is thus to improve mechanical and thermal properties of PBS bioplastic films by reinforcing with silica. Due to the poor interfacial interaction between the PBS matrix and silica, glycidyl methacrylate grafted poly(butylene succinate (PBS-g-GMA was used as a compatibilizer in order to improve the interaction between bioplastic films and filler. PBS-g-GMA was prepared in a twin-screw extruder and analyzed by the FTIR spectrometer. PBS and silica were then mixed in a twin-screw extruder and processed into films by a chill-roll cast extruder. The effects of silica loading on thermal and mechanical properties of the prepared bioplastic films were investigated. It was found that the mechanical properties of PBS/silica composite films were improved when 1%wt of silica was added. However, the mechanical properties decreased with increasing silica loading due to the agglomeration of silica particles. The results also show that the silica/PBS films with PBS-g-GMA possessed improved mechanical properties over the films without the compatibilizer.

  3. Stoichiometry of mitochondrial H+ translocation coupled to succinate oxidation at level flow.

    Science.gov (United States)

    Costa, L E; Reynafarje, B; Lehninger, A L

    1984-04-25

    The mechanistic stoichiometry of vectorial H+ translocation coupled to succinate oxidation by rat liver mitochondria in the presence of a permeant cation has been determined under level flow conditions with a membraneless fast responding O2 electrode kinetically matched with a glass pH electrode. The reactions were initiated by rapid injection of O2 into the anaerobically preincubated test system under conditions in which interfering H+ backflow was minimized. The rates of O2 uptake and H+ ejection, obtained from computer-fitted regression lines, were monotonic and first order over 75% of the course of O2 consumption. Extrapolation of the observed rates to zero time, at which zero delta mu H+ and thus level flow prevails, yielded vectorial H+/O flow ratios above 7 and closely approaching 8. The mitochondria undergo no irreversible change and give identical H+/O ratios on repeated tests. In a further refinement, the lower and upper limits of the mechanistic H+/O ratio were determined to be 7.55 and 8.56, respectively, from plots of the rates of O2 uptake versus H+ ejection at increasing malonate and increasing valinomycin concentrations, respectively. It is therefore concluded that the mechanistic H+/O ratio for energy-conserving sites 2 + 3 is 8, in confirmation of earlier measurements. KCl concentration is critical for maximal observed H+/O ratios. Optimum conditions and possible errors in determination of mechanistic H+/O translocation ratios are discussed. PMID:6232269

  4. DEVELOPMENT AND IN-VITRO EVALUATION OF METOPROLOL SUCCINATE CONTROLLED POROSITY OSMOTIC PUMP TABLETS

    Directory of Open Access Journals (Sweden)

    Veeramalla Anil Kumar

    2013-04-01

    Full Text Available In the present research work, attempts were made to develop and evaluate Sustained release formulation of Metoprolol succinate based on osmotic technology.As Metoprolol is a short acting drug, developed formulation provides the advantages of controlled release formulations. The developed formulation provides advantages of less steps of manufacturing procedure, no need of laser drilling, and economical. All of these made the procedure easily amenable to mass production using conventional tablet machines. Metoprolol 50mg core formulation was prepared using osmogents and coated with different coating formulae to optimize film former (cellulose acetate: pore former (sorbitol ratio. The effect of different formulation variables namely, membrane weight gain, and amount of pore former in the membrane, were studied. Metoprolol release was inversely proportional to the membrane weight (coating thickness but directly related to the initial amount of pore former (sorbitol in the membrane. All polymers and excipients used in optimized formula were found to be compatible with the drug and it was confirmed by FT-IR studies. Drug release from the developed formulations was independent of pH and agitational intensity. The drug release from formulation was proved as dependent on osmotic pressure only. The number of pores was directly proportional to the amount of pore former in the membrane. The manufactured formulations were stable after 45 days of accelerated stability studies.

  5. Phase Transformation of Adefovir Dipivoxil/Succinic Acid Cocrystals Regulated by Polymeric Additives

    Directory of Open Access Journals (Sweden)

    Sungyup Jung

    2013-12-01

    Full Text Available The polymorphic phase transformation in the cocrystallization of adefovir dipivoxil (AD and succinic acid (SUC was investigated. Inspired by biological and biomimetic crystallization, polymeric additives were utilized to control the phase transformation. With addition of poly(acrylic acid, the metastable phase newly identified through the analysis of X-ray diffraction was clearly isolated from the previously reported stable form. Without additives, mixed phases were obtained even at the early stage of cocrystallization. Also, infrared spectroscopy analysis verified the alteration of the hydrogen bonding that was mainly responsible for the cocrystal formation between AD and SUC. The hydrogen bonding in the metastable phase was relatively stronger than that in the stable form, which indicated the locally strong AD/SUC coupling in the initial stage of cocrystallization followed by the overall stabilization during the phase transformation. The stronger hydrogen bonding could be responsible for the faster nucleation of the initially observed metastable phase. The present study demonstrated that the polymeric additives could function as effective regulators for the polymorph-selective cocrystallization.

  6. Human brain aldehyde reductases: relationship to succinic semialdehyde reductase and aldose reductase.

    Science.gov (United States)

    Hoffman, P L; Wermuth, B; von Wartburg, J P

    1980-08-01

    Human brain contains multiple forms of aldehyde-reducing enzymes. One major form (AR3), as previously shown, has properties that indicate its identity with NADPH-dependent aldehyde reductase isolated from brain and other organs of various species; i.e., low molecular weight, use of NADPH as the preferred cofactor, and sensitivity to inhibition by barbiturates. A second form of aldehyde reductase ("SSA reductase") specifically reduces succinic semialdehyde (SSA) to produce gamma-hydroxybutyrate. This enzyme form has a higher molecular weight than AR3, and uses NADH as well as NADPH as cofactor. SSA reductase was not inhibited by pyrazole, oxalate, or barbiturates, and the only effective inhibitor found was the flavonoid quercetine. Although AR3 can also reduce SSA, the relative specificity of SSA reductase may enhance its in vivo role. A third form of human brain aldehyde reductase, AR2, appears to be comparable to aldose reductases characterized in several species, on the basis of its activity pattern with various sugar aldehydes and its response to characteristic inhibitors and activators, as well as kinetic parameters. This enzyme is also the most active in reducing the aldehyde derivatives of biogenic amines. These studies suggest that the various forms of human brain aldehyde reductases may have specific physiological functions. PMID:6778961

  7. NONISOTHERMAL CRYSTALLIZATION AND MORPHOLOGY OF POLY(BUTYLENE SUCCINATE)/LAYERED DOUBLE HYDROXIDE NANOCOMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Mei-qiu Zhan; Guang-yi Chen; Zhi-yong Wei; Yu-mei Shi; Wan-xi Zhang

    2013-01-01

    Biodegradable poly(butylene succinate) (PBS) and layered double hydroxide (LDH) nanocomposites were prepared via melt blending in a twin-screw extruder.The morphology and dispersion of LDH nanoparticles within PBS matrix were characterized by transmission electron microscopy (TEM),which showed that LDH nanoparticles were found to be well distributed at the nanometer level.The nonisothermal crystallization behavior of nanocomposites was extensively studied using differential scanning calorimetry (DSC) technique at various cooling rates.The crystallization rate of PBS was accelerated by the addition of LDH due to its heterogeneous nucleation effect; however,the crystallization mechanism and crystal structure of PBS remained almost unchanged.In kinetics analysis of nonisothermal crystallization,the Ozawa approach failed to describe the crystallization behavior of PBS/LDH nanocomposites,whereas both the modified Avrami model and the Mo method well represented the crystallization behavior of nanocomposites.The effective activation energy was estimated as a function of the relative degree of crystallinity using the isoconversional analysis.The subsequent melting behavior of PBS and PBS/LDH nanocomposites was observed to be dependent on the cooling rate.The POM showed that the small and less perfect crystals were formed in nanocomposites.

  8. Bone Formation from Porcine Dental Germ Stem Cells on Surface Modified Polybutylene Succinate Scaffolds

    Directory of Open Access Journals (Sweden)

    Nergis Abay

    2016-01-01

    Full Text Available Designing and providing a scaffold are very important for the cells in tissue engineering. Polybutylene succinate (PBS has high potential as a scaffold for bone regeneration due to its capacity in cell proliferation and differentiation. Also, stem cells from 3rd molar tooth germs were favoured in this study due to their developmentally and replicatively immature nature. In this study, porcine dental germ stem cells (pDGSCs seeded PBS scaffolds were used to investigate the effects of surface modification with fibronectin or laminin on these scaffolds to improve cell attachment, proliferation, and osteogenic differentiation for tissue engineering applications. The osteogenic potentials of pDGSCs on these modified and unmodified foams were examined to heal bone defects and the effects of fibronectin or laminin modified PBS scaffolds on pDGSC differentiation into bone were compared for the first time. For this study, MTS assay was used to assess the cytotoxic effects of modified and unmodified surfaces. For the characterization of pDGSCs, flow cytometry analysis was carried out. Besides, alkaline phosphatase (ALP assay, von Kossa staining, real-time PCR, CM-Dil, and immunostaining were applied to analyze osteogenic potentials of pDGSCs. The results of these studies demonstrated that pDGSCs were differentiated into osteogenic cells on fibronectin modified PBS foams better than those on unmodified and laminin modified PBS foams.

  9. Influence of spaceflight on succinate dehydrogenase activity and soma size of rat ventral horn neurons

    Science.gov (United States)

    Ishihara, A.; Ohira, Y.; Roy, R. R.; Nagaoka, S.; Sekiguchi, C.; Hinds, W. E.; Edgerton, V. R.

    1996-01-01

    Succinate dehydrogenase (SDH) activities and soma cross-sectional areas (CSA) of neurons in the dorsolateral region of the ventral horn at the L5 segmental level of the spinal cord in the rat were determined after 14 days of spaceflight and after 9 days of recovery on earth. The results were compared to those in age-matched ground-based control rats. Spinal cords were quick-frozen, and the SDH activity and CSA of a sample of neurons with a visible nucleus were determined using a digitizer and a computer-assisted image analysis system. An inverse relationship between CSA and SDH activity of neurons was observed in all groups of rats. No change in mean CSA or mean SDH activity or in the size distribution of neurons was observed following spaceflight or recovery. However, there was a selective decrease in the SDH activity of neurons with soma CSA between 500 and 800 microns2 in the flight rats, and this effect persisted for at least 9 days following return to 1 g. It remains to be determined whether the selected population of motoneurons or the specific motor pools affected by spaceflight may be restricted to specific muscles.

  10. Investigation on growth, structure and characterization of succinate salt of 8-hydroxyquinoline: An organic NLO crystal

    Science.gov (United States)

    Thirumurugan, R.; Babu, B.; Anitha, K.; Chandrasekaran, J.

    2015-04-01

    8-Hydroxyquinolinium succinate (8-HQSU) has been synthesized and single crystals were grown from ethanol solvent by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated by single crystal X-ray diffraction analysis. It reveals that 8-HQSU crystallizes in monoclinic system with non-centro symmetric space group P21. FTIR, 1H and 13C NMR spectral investigations have been carried out to identify the vibrational modes of various functional groups and placement of proton and carbon in the 8-HQSU compound, respectively. UV-vis-NIR transmission spectrum shows the cutoff wavelength around 357 nm. In addition, a photoluminescence spectral analysis was carried out for 8-HQSU crystals. The thermal properties of crystals were evaluated from TGA and DTA techniques and the crystal was found to be stable up to 145 °C. The dielectric studies show that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures. Photoconductivity studies were carried out on the grown crystals it reveals the positive photo conducting nature. Powder second harmonic generation property of the crystal was confirmed by Kurtz and Perry powder SHG technique and it is found to be 1.3 times greater than that of KDP.

  11. Tocopherol Succinate: Modulation of Antioxidant Enzymes and Oncogene Expression, and Hematopoietic Recovery

    International Nuclear Information System (INIS)

    Purpose: A class of naturally occurring isoforms of tocopherol (tocols) was shown to have varying degrees of protection when administered before radiation exposure. We recently demonstrated that α-tocopherol succinate (TS) is a potential radiation prophylactic agent. Our objective in this study was to further investigate the mechanism of action of TS in mice exposed to 60Co γ-radiation. Methods and Materials: We evaluated the effects of TS on expression of antioxidant enzymes and oncogenes by quantitative RT-PCR in bone marrow cells of 60Co γ-irradiated mice. Further, we tested the ability of TS to rescue and repopulate hematopoietic stem cells by analyzing bone marrow cellularity and spleen colony forming unit in spleen of TS-injected and irradiated mice. Results: Our results demonstrate that TS modulated the expression of antioxidant enzymes and inhibited expression of oncogenes in irradiated mice at different time points. TS also increased colony forming unit-spleen numbers and bone marrow cellularity in irradiated mice. Conclusions: Results provide additional support for the observed radioprotective efficacy of TS and insight into mechanisms.

  12. Dispersion of multi-walled carbon nanotubes in biodegradable poly(butylene succinate) matrix.

    Science.gov (United States)

    Ray, Suprakas Sinha; Vaudreuil, Sébastien; Maazouz, Abderrahim; Bousmina, Mosto

    2006-07-01

    This communication describes the preparation, characterization and properties of biodegradable poly(butylene succinate) (PBS)/multi-walled carbon nanotubes (MWCNTs) nanocomposite. Nanocomposite was prepared by melt-blending in a batch mixer and the amount of MWCNTs loading was 3 wt%. State of dispersion-distribution of the MWCNTs in the PBS matrix was examined by scanning and transmission electron microscopic observations that revealed homogeneous distribution of stacked MWCNTs in PBS matrix. The investigation of the thermomechanical behavior was performed by dynamic mechanical thermal analysis. Results demonstrated substantial enhancement in the mechanical properties of PBS, for example, at room temperature, storage flexural modulus increased from 0.64 GPa for pure PBS to 1.2 GPa for the nanocomposite, an increase of about 88% in the value of the elastic modulus. The tensile modulus and thermal stability of PBS were moderately improved after nanocomposite preparation with 3 wt% of MWCNTs, while electrical conductivity of neat PBS dramatically increased after nanocomposite formation. For example, the in plane conductivity increased from 5.8 x 10(-9) S/cm for neat PBS to 4.4 x 10(-3) for nanocomposite, an increase of 10(6) fold in value of the electrical conductivity. PMID:17025148

  13. Development and optimization of press coated floating pulsatile drug delivery of sumatriptan succinate.

    Science.gov (United States)

    Jagdale, Swati C; Pawar, Chandrakala R

    2014-01-01

    Floating pulsatile is combined approach designed according to circadian rhythm to deliver the drug at right time, in right quantity and at right site as per pathophysiological need of disease with prolong gastric residence and lag phase followed by burst release. As the migraine follows circadian rhythm in which headache is more painful at the awakening time, the dosage form should be given during night time to release drug when pain get worsen. Present work deals with formulation and optimization of floating pulsatile tablet of sumatriptan succinate. Core tablet containing crospovidone as superdisintegrant (10%) showed burst release. Lag time was maintained using swellable polymer as polyoxN12K and xanthum gum. 3(2) experimental design was carried out. Developed formulations were evaluated for physical characteristics, in vitro and in vivo study. Optimized batch F2 with concentration of polyox N12K (73.43%) and xanthum gum (26.56%) of total polymer weight showed floating lag time 15±2 sec, drug content 99.58±0.2 %, hardness 6±0.2 Kg/cm(2) and drug release 99.54±2% with pulsatile manner followed lag period of 7±0.1h. In vivo x-ray study confirms prolong gastric residence of system. Programmable pulsatile release has been achieved by formulation F2 which meet demand of chronotherapeutic objective of migraine. PMID:24893996

  14. Succinate Dehydrogenase B Subunit Immunohistochemical Expression Predicts Aggressiveness in Well Differentiated Neuroendocrine Tumors of the Ileum

    Energy Technology Data Exchange (ETDEWEB)

    Milione, Massimo [Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan I-20133 (Italy); Pusceddu, Sara [Department of Medical Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan I-20133 (Italy); Gasparini, Patrizia [Molecular Cytogenetics Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan I-20133 (Italy); Melotti, Flavia [Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan I-20133 (Italy); Maisonneuve, Patrick [Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan 20141 (Italy); Mazzaferro, Vincenzo [Division of Gastrointestinal Surgery and Liver Transplantation, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan I-20133 (Italy); Braud, Filippo G. de [Department of Medical Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan I-20133 (Italy); Pelosi, Giuseppe, E-mail: giuseppe.pelosi@unimi.it [Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan I-20133 (Italy); Department of Medicine, Surgery and Dentistry, Università degli Studi, Facoltà di Medicina, Milan 20122 (Italy)

    2012-08-16

    Immunohistochemical loss of the succinate dehydrogenase subunit B (SDHB) has recently been reported as a surrogate biomarker of malignancy in sporadic and familial pheocromocytomas and paragangliomas through the activation of hypoxia pathways. However, data on the prevalence and the clinical implications of SDHB immunoreactivity in ileal neuroendocrine tumors are still lacking. Thirty-one consecutive, advanced primary midgut neuroendocrine tumors and related lymph node or liver metastases from 24 males and seven females were immunohistochemically assessed for SDHB. All patients were G1 tumors (Ki-67 labeling index ≤2%). SDHB immunohistochemistry results were expressed as immunostaining intensity and scored as low or strong according to the internal control represented by normal intestinal cells. Strong positivity for SDHB, with granular cytoplasmatic reactivity, was found in 77% of primary tumors (T), whilst low SDHB expression was detected in 90% of metastases (M). The combined analysis (T+M) confirmed the loss of SDHB expression in 82% of metastases compared to 18% of primary tumors. SDHB expression was inversely correlated with Ki-67 labeling index, which accounted for 1.54% in metastastic sites and 0.7% in primary tumors. A correlation between SDHB expression loss, increased Ki-67 labeling index and biological aggressiveness was shown in advanced midgut neuroendocrine tumors, suggesting a role of tumor suppressor gene.

  15. Effect of hydrophilic and hydrophobic polymers on release kinetics of metoprolol succinate extended release tablets

    Directory of Open Access Journals (Sweden)

    Ramani Gade

    2011-01-01

    Full Text Available The purpose of the present work is to design and evaluate extended release matrix tablets of metoprolol succinate to reduce the dosing frequency and to improve patient compliance. The matrix tablets were prepared by the combination of hydrophilic and hydrophobic polymers, using methocel 10000 Cps in combination with ethyl cellulose 7 Cps, Eudragit® RS100, Eudragit® S100, and Eudragit® L100.The tablets were prepared by direct compression technique. Prepared formulations were evaluated for various parameters like weight variation, thickness, hardness, friability, and % drug content. Tablets were subjected to in vitro drug release studies. The formulations containing methocel 10000 Cps, Eudragit® L100 showed good release retardation. All the prepared formulations showed first-order release kinetics with matrix diffusion mechanism of release. The formulation containing 52.06% w/w of methocel 10000 Cps, 8.75% Eudragit® L100 offered the required release rate according to USP Pharmacopoeial guidelines. The combination of hydrophilic and hydrophobic polymers can effectively control the drug release for freely water-soluble drugs in case of extended release formulations which are the upcoming dosage forms for patient compliance in all aspects.

  16. Effects of Radiation on Mechanical Properties of Poly (butylene succinate) and Cassava Starch Blends

    International Nuclear Information System (INIS)

    This research compared the effects of gamma and electron beam irradiation at different doses on the mechanical properties of polymer blends between poly(butylene succinate) (PBS) and cassava starch. Two types of starch were used to prepare thermoplastic starch (TPS), native cassava starch and hydrophobic starch. PBS/TPS blends were compounded at five different weight ratios using a twin-screw extruder. Mechanical properties and degradation were evaluated in comparison to unirradiated samples. Results indicated that the incorpora- tion of TPS prepared from native cassava starch decreased the mechanical properties of PBS/TPS blends, whereas the addition of TPS prepared from hydrophobic starch improved the mechanical properties of the blends. In addition, the maximum mechanical properties of PBS/TPS blends were achieved when samples were exposed to irradiation at 120 kGy. Using soil burial evaluation, the degradation rate of blends was found to increase with the addition of TPS. Therefore we have demonstrated in this study that the type of TPS and irradiation treatment can significantly alter the mechanical properties and degradation of PBS/TPS blends.

  17. Analysis of Gas Permeability Characteristics of Poly(Lactic Acid/Poly(Butylene Succinate Nanocomposites

    Directory of Open Access Journals (Sweden)

    Amita Bhatia

    2012-01-01

    Full Text Available Gas permeability and morphological properties of nanocomposites prepared by the mixing of poly(lactic acid (PLA, poly(butylene succinate (PBS, and clay was investigated. While the composition of PLA and PBS polymers was fixed as 80% and 20% by weight, respectively, for all the nanocomposites, clay contents varied from 1 to 10 wt%. From the morphological studies using both wide angle X-ray diffraction and transmission electron microscopy, the nanocomposite having 1 wt% of clay was considered to have a mixed morphology of intercalated and delaminated structure, while some clusters or agglomerated particles were detected for nanocomposites having 3 and more than 3 wt% of clay content. However, the average particle size of the dispersed PBS phase was reduced significantly from 7 μm to 30–40 nm with the addition of clay in the blend. The oxygen barrier property was improved significantly as compared to the water vapor. A model based on gas barrier property was used for the validation of the oxygen relative permeabilities of PLA/PBS/clay nanocomposites. PLA/PBS/clay nanocomposites validated the Bharadwaj model up to 3 wt% of clay contents only, while for nanocomposites of higher clay contents the Bharadwaj model was invalid due to the clusters and agglomerates formed.

  18. RING OPENING COPOLYMERIZATION OF SUCCINIC ANHYDRIDE-ETHYLENE OXIDE BY Al (Ⅲ) ORGANOMETALLIC CATALYSTS

    Institute of Scientific and Technical Information of China (English)

    CHEN Xianhai; ZHANG Yifeng; SHEN Zhiquan

    1997-01-01

    Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at 62±2℃. The results showed that in-situ AlR3-H2O (R=ethyl, iso-butyl) catalysts gave higher molecular weight ((-M)w ~ 104), while Al(OR)3 catalysts gave the higher alternating copolymer structure with slightly lower molecular weight. The in-situ AlR3-H2O systems have been evaluated in more detail for the reaction which showed the optimum H2O/Al molar ratio to be 0.5. The copolymers with different composition (FSA/FEO = 36/64 to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melting point (Tm), glass transition temperature (Tg) and enthalpy of fusion (ΔHf) of these copolymers are depended on the copolymer composition and in the range of 87~ 102℃,-12 ~ -18℃, and 37 ~ 66J/g, respectively. The second heating scan of DSC also indicated that the higher alternating copolymer was more easily recrystallized. The onset decomposition temperature was more than 300℃ under nitrogen and influenced by the copolymer composition.

  19. POLYSACCHARIDE GUM (KONDAGOGU GUM MATRIX TABLETS FOR ORAL SUSTAINED DELIVERY OF METOPROLOL SUCCINATE

    Directory of Open Access Journals (Sweden)

    N. Aswani

    2011-04-01

    Full Text Available The present study has been undertaken to develop a sustained-release tablet dosage form for metoprolol succinate using kondagugu gum as the rate-controlling polymer. The prepared tablets were coated will shellac as an enteric coat polymer and evaluated for tablet properties. In vitro release studies of prepared tablets were carried out for 2 hrs in pH 1.2 HCl buffer and 22 hrs in pH 6.8phosphate buffer. In addition, swelling, kinetics of drug release from the matrices and stability of the tablet formulations were also investigated. Mathematical analysis of the release kinetics showed that the nature of drug release from the matrix tablets has followed super case II transport. FTIR and DSC studies have shown that no chemical interaction occurred between the drug and polymers used. The optimized formulation (F4 showed negligible difference in release mechanism as well as release kinetics when stability study was done for three months at 40±20 C and 75±5% RH.

  20. Effect of vitamin E succinate on the proliferation of human breast cancer cells

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; ZHANG Jun-chu; ZHU Da-qiao; YE Lai-ying; ZHANG Ling-zhen; WANG Qiang

    2005-01-01

    Objective:To investigate the growth inhibition and apoptosis induced by vitamin E succinate (VES) on human breast cancer cells and to analyze the possible mechanism in this process. Methods: Human breast cancer cell line Bcap-37 was treated with VES for 12, 24 and 48 h at the concentrations of 5,10 and 20 μg/ml. Then MTT assay was employed to detect the inhibitory effect of VES on the growth of breast cancer cells. Flow cytometry was used to analyze the cell cycle and apoptosis. To find out whether the Fas/FasL pathway was involved in this process, RT-PCR and flow cytometry assay were used to detect the Fas expression at the mRNA and protein level. Results: VES exhibited a significant inhibitory effect on the growth of human breast cancer cells, presenting in a dose- and time-dependant manner. The apoptotic rate of Bcap-37 cells was 0.6%, rose to 21.0% and 37.5% after treated with VES for 24 and 48h at the concentration of 20μg/ml. Fas mRNA transcription was upregulated after VES treatment and cell surface Fas expression increased according to the flow cytometry assay. Conclusion:Significant growth inhibition and apoptosis are induced in human breast cancer cells after treated with VES. The modulation of Fas/FasL pathway may related to the upregulation of Fas molecule on the cancer cell surface.

  1. Aerogel Poly(butylene succinate) Biomaterial Substrate for RF and Microwave Applications

    Science.gov (United States)

    Habib Ullah, M.; Mahadi, W. N. L.; Latef, T. A.

    2015-01-01

    Polybutylene succinate (PBS) has become a potential candidate, similar to polypropylene (PP) and acrylonitrile butadiene styrene (ABS), for use as an organic plastic material due to its outstanding mechanical properties as well as high thermal deformation characteristics. A new composition of silica aerogel nanoparticles extracted from rice waste with PBS is proposed for use as a dielectric (εr = 4.5) substrate for microwave applications. A microstrip patch antenna was fabricated on the proposed dielectric substrate for multi-resonant ultra-wideband (UWB) applications. The performance characteristics of the proposed biomaterial-based antenna were investigated in a far-field measurement environment. The results indicate that the proposed biocompatible material-based antenna covered a bandwidth of 9.4 (2.3–11.7) GHz with stop bands from 5.5 GHz to 5.8 GHz and 7.0 GHz to 8.3 GHz. Peak gains of 9.82 dBi, 7.59 dBi, 8.0 dBi and 7.68 dBi were measured at resonant frequencies of 2.7 GHz, 4.6 GHz, 6.3 GHz and 9.5 GHz, respectively. PMID:26238975

  2. Novel bioactive polyester scaffolds prepared from unsaturated resins based on isosorbide and succinic acid.

    Science.gov (United States)

    Smiga-Matuszowicz, Monika; Janicki, Bartosz; Jaszcz, Katarzyna; Łukaszczyk, Jan; Kaczmarek, Marcin; Lesiak, Marta; Sieroń, Aleksander L; Simka, Wojciech; Mierzwiński, Maciej; Kusz, Damian

    2014-12-01

    In this study new biodegradable materials obtained by crosslinking poly(3-allyloxy-1,2-propylene succinate) (PSAGE) with oligo(isosorbide maleate) (OMIS) and small amount of methyl methacrylate were investigated. The porous scaffolds were obtained in the presence of a foaming system consisted of calcium carbonate/carboxylic acid mixture, creating in situ porous structure during crosslinking of liquid formulations. The maximum crosslinking temperature and setting time, the cured porous materials morphology as well as the effect of their porosity on mechanical properties and hydrolytic degradation process were evaluated. It was found that the kind of carboxylic acid used in the foaming system influenced compressive strength and compressive modulus of porous scaffolds. The MTS cytotoxicity assay was carried out for OMIS using hFOB1.19 cell line. OMIS resin was found to be non-toxic in wide range of concentrations. On the ground of scanning electron microscopy (SEM) observations and energy X-ray dispersive analysis (EDX) it was found that hydroxyapatite (HA) formation at the scaffolds surfaces within short period of soaking in phosphate buffer solution occurs. After 3h immersion a compact layer of HA was observed at the surface of the samples. The obtained results suggest potential applicability of resulted new porous crosslinked polymeric materials as temporary bone void fillers. PMID:25491802

  3. NMR investigations of the conformation of new cyclodextrin-based amphiphilic transporters for hydrophobic drugs: molecular lollipops

    Science.gov (United States)

    Bellanger, Nathalie; Perly, Bruno

    1992-10-01

    Amphiphilic compounds, obtained by grafting aliphatic acids onto a modified cyclodextrin, have been synthesized and studied by solution NMR. The large chain-length dependence of the NMR spectra in aqueous media is explained by the possible formation of auto-inclusion complexes. This process has been evidenced by extensive NMR experiments and by competition with potential guests. This new class of molecules ("lollipops") provides important information for the optimization of a design for amphiphilic transporters to be included in organized phases such as micelles or liposomes.

  4. Rapidly recovering hydrogel scaffolds from self-assembling diblock copolypeptide amphiphiles

    Science.gov (United States)

    Nowak, Andrew P.; Breedveld, Victor; Pakstis, Lisa; Ozbas, Bulent; Pine, David J.; Pochan, Darrin; Deming, Timothy J.

    2002-05-01

    Protein-based hydrogels are used for many applications, ranging from food and cosmetic thickeners to support matrices for drug delivery and tissue replacement. These materials are usually prepared using proteins extracted from natural sources, which can give rise to inconsistent properties unsuitable for medical applications. Recent developments have utilized recombinant DNA methods to prepare artificial protein hydrogels with specific association mechanisms and responsiveness to various stimuli. Here we synthesize diblock copolypeptide amphiphiles containing charged and hydrophobic segments. Dilute solutions of these copolypeptides would be expected to form micelles; instead, they form hydrogels that retain their mechanical strength up to temperatures of about 90°C and recover rapidly after stress. The use of synthetic materials permits adjustment of copolymer chain length and composition, which we varied to study their effect on hydrogel formation and properties. We find that gelation depends not only on the amphiphilic nature of the polypeptides, but also on chain conformations-α-helix, β-strand or random coil. Indeed, shape-specific supramolecular assembly is integral to the gelation process, and provides a new class of peptide-based hydrogels with potential for applications in biotechnology.

  5. Progress in developing amphiphilic cyclodextrin-based nanodevices for drug delivery.

    Science.gov (United States)

    Yaméogo, Josias B G; Géze, Annabelle; Choisnard, Luc; Putaux, Jean-Luc; Semdé, Rasmané; Wouessidjewe, Denis

    2014-01-01

    Nowadays, colloidal drug carriers represent an alternative to solve drug bioavailabily problems. During the past two decades, colloidal drug carriers have proved to improve the therapeutic index of drugs and thus increase their efficacy and/or reduce their toxicity. However, the major challenge in the development of these drug carriers remains the search for materials able to self-organize into stable nanoscale systems. In particular, amphiphilic α-, β- and γ-cyclodextrins (CDs), grafted on their secondary or primary side with different aliphatic chains, have been investigated as drug delivery vehicles due to their ability to self-assemble and form various stable colloidal systems such as micellar aggregates, nanoreservoirs or nanoparticles exhibiting a matricial, multilamellar or hexagonal supramolecular organization. These self-assembled CD-based nanodevices show some advantages in terms of stability, good ability to associate lipophilic drugs and good in vivo tolerance. This review focuses on the potential of the structured nanoparticles obtained from nonionic amphiphilic CDs in drug delivery and targeting. We discuss the synthesis and characterization of the building blocks as well as the preparation and characterization of colloidal particles made from these materials. We also considered some pharmaceutical applications and identified opportunities for an optimum use of this CD-based nanotechnology approach in addressing worldwide priority health problems. PMID:24354667

  6. Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene

    Directory of Open Access Journals (Sweden)

    Ludmilla Lumholdt

    2014-11-01

    Full Text Available Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixture containing multiple pollutants. The volatile organic compounds are known to form stable inclusion complexes with cyclodextrins. Six different amphiphilic cyclodextrin derivatives were synthesised in order to elucidate whether or not the uptake abilities of the coating depend on the structure of the derivative. Headspace gas chromatography was used for quantification of the uptake exploiting the volatile nature of benzene and its derivatives. The capacity was shown to increase beyond the expected stoichiometries of guest–host complexes with ratios of up to 16:1.

  7. Amphiphilic nanocapsules entangled with organometallic coordination polymers for controlled cargo release.

    Science.gov (United States)

    Liang, Guodong; Ni, Huan; Bao, Suping; Zhu, Fangming; Gao, Haiyang; Wu, Qing; Tang, Ben Zhong

    2014-06-01

    A class of new amphiphilic nanocapsules entangled with organometallic coordination polymers has been developed for the first time. Poly(2-(N,N-dimethyl amino)ethyl methacrylate)-b-polystyrene capped with β-cyclodextrin (β-CD) (CD-PDMAEMA-b-PS) is first synthesized using sequent RAFT polymerization of styrene and 2-(N,N-dimethyl amino)ethyl methacrylate with xanthate modified β-CD as chain transfer agent. The end group of β-CD is allowed to include 4,4'-bipyridine through host-guest inclusion to yield PDMAEMA-b-PS terminated with an inclusion complex of β-CD and bipyridine (bpy-PDMAEMA-b-PS), which is then used as surfactant to prepare emulsion droplets in toluene/water mixture. Upon addition of Ni(II), bipyridine coordinates with Ni(II) to form coordination polymers in the periphery of emulsion droplets, affording amphiphilic capsules entangled with organometallic coordination polymers, as confirmed by GPC, (1)H NMR, SEM, TEM, DLS, and so on. The organometallic coordination polymer capsules are capable of encapsulating organic cargoes. Interestingly, encapsulated cargoes can be extracted from the capsules without damaging the capsules. Such capsules are potential candidates for encapsulating and controlled release of organic cargoes. PMID:24828951

  8. THE AMPHIPHILIC MULTIARM COPOLYMERS BASED ON HYPERBRANCHED POLYESTER AND LYSINE: SYNTHESIS AND SELF-ASSEMBLY

    Institute of Scientific and Technical Information of China (English)

    Jing Wang; Yuan Yao; Bing Ji; Wei Huang; Yong-feng Zhou; De-yue Yan

    2011-01-01

    The amphiphilic multiarm copolymers were synthesized through the modification of commercially available hyperbranched polyesters (Boltom H40) with N-ε-carbobenzoxy-L-Lysine N-carboxyanhydride (ZLys-NCA). After being condensed with N-Boc-phenylalanine (Boc-NPhe) and deprotected the Boc-groups in trifluoroacetic acid (TFA), the original terminal hydroxyl groups were transformed into the amino groups and then initiated the ring-opening polymerization of ZLys-NCA. The hydrophilic poly(L-lysine) was grafted to the surface of Boltorn H40 successfully after the protecting benzyl groups were removed by the HBr solution in glacial acetic acid (33 wt%). The resulting multiarm copolymers were characterized by the 1H-NMR, GPC and FTIR. The arm length calculated by NMR and GPC analysis was about 3 and 13 lysine-units for H40-Phe-PLysl and H40-Phe-PLys2 respectively. Due to the amphiphilic molecular structure, they displayed ability to self-assemble into spherical micelles in aqueous solution with the average diameter in the range from 70 nm to 250 nm. The CMC of H40-Phe-PLysl and H40-Phe-PLys2 was 0.013 mg/mL and 0.028 mg/mL, respectively,indicating that H40-Phe-PLysl with shorter arm length is easier to self-assemble than H40-Phe-PLys2 with longer arm length.

  9. Synthesis of an amphiphilic rhodamine derivative and characterization of its solution and thin film properties

    International Nuclear Information System (INIS)

    Here we present characterization of solution and thin film properties of Lissamine rhodamine B sulfonyl didodecyl amine (LRSD), an amphiphilic derivative of rhodamine. LRSD was synthesized by functionalizing Lissamine rhodamine B sulfonyl chloride (LRSC) with didodecylamine via a straightforward sulfonylation reaction. LRSD's long alkane chains make it highly soluble in chloroform, with a marked increase in brightness compared to the starting material. LRSD is shown to form well-defined robust micelles in water, without the addition of a co-surfactant and stable monolayers at the air–water interface. The greater lipophilicity of LRSD also enables doping into non-polar polymeric host matrices such as polystyrene with less aggregation and hence higher fluorescence quantum yield than LRSC or even rhodamine B. The monolayers of LRSD were prepared via Langmuir–Blodgett deposition and showed shifts in the photoluminescence peak from 575 nm to 595 nm, as the surface pressure is varied from 3 mN/m to 11 mN/m. - Highlights: • Lissamine rhodamine B sulfonyl didodecyl amine (LRSD) is soluble in chloroform. • LRSD shows robust quantum yield in solution and as a dopant in thin film. • LRSD is an amphiphilic rhodamine dye that forms compact fluorescent micelles. • LRSD forms a stable isotherm when spread at the air–water interface

  10. NOVEL AMPHIPHILIC FLUORESCENT GRAFT COPOLYMER: SYNTHESIS,CHARACTERIZATION AND ENCAPSULATION OF A HYDROPHOBIC AGENT

    Institute of Scientific and Technical Information of China (English)

    Zhao-qiang Wu; Shu Yang; Wen-yan Liao; Ling-zhi Meng

    2006-01-01

    Novel amphiphilic fluorescent graft copolymer (PVP-PyAHy) was successfully synthesized by the free radical copolymerization of hydrophobic monomer N-(1-pyrenebutyryl)-N'-acryloyl hydrazide (PyAHy) with hydrophilic precursor polymers of vinyl-functionalized poly(N-vinylpyrrolidone) (PVP) in DMF. The copolymer is amphiphilic and has intrinsic fluorescence. FT-IR, 1H-NMR, TEM, gel permeation chromatography-multi-angle laser light scattering, UV-Vis spectroscopy and fluorescence spectroscopy were used to characterize this copolymer. The TEM observation shows that the copolymer PVP-PyAHy forms micelles in aqueous solution. Results of fluorometric measurements illustrate that the critical micelle concentration (CMC) value of PVP-PyAHy in aqueous solution is about 0.90 mg/mL. To examine the encapsulation ability of the copolymer in aqueous media, methyl yellow was employed as a model hydrophobic agent. The loading level of the polymer to methyl yellow is 8.8 mg/g. The cytotoxicity assays for Madin Darby Canine Kidney (MDCK) cells shows good biocompatibility of PVP-PyAHy in vitro. These results suggest the potential of this copolymer PVP-PyAHy as drugs delivery carrier and fluorescent tracer.

  11. Hydrophobic cotton textile surfaces using an amphiphilic graphene oxide (GO) coating

    Science.gov (United States)

    Tissera, Nadeeka D.; Wijesena, Ruchira N.; Perera, J. Rangana; de Silva, K. M. Nalin; Amaratunge, Gehan A. J.

    2015-01-01

    We report for the first time hydrophobic properties on cotton fabric successfully achieved by grafting graphene oxide on the fabric surface, using a dyeing method. Graphite oxide synthesized by oxidizing natural flake graphite employing improved Hummer's method showed an inter layer spacing of ∼1 nm from XRD. Synthesized graphite oxide was exfoliated in water using ultrasound energy to obtain graphene oxide (GO). AFM data obtained for the graphene oxide dispersed in an aqueous medium revealed a non-uniform size distribution. FTIR characterization of the synthesized GO sheets showed both hydrophilic and hydrophobic functional groups present on the nano sheets giving them an amphiphilic property. GO flakes of different sizes were successfully grafted on to a cotton fabric surface using a dip dry method. Loading different amounts of graphene oxide on the cotton fiber surface allowed the fabric to demonstrate different degrees of hydrophobicity. The highest observed water contact angle was at 143° with the highest loading of graphene oxide. The fabric surfaces grafted with GO also exhibits adhesive type hydrophobicity. Microscopic characterization of the fiber surface using SEM and AFM reveals the deposition of GO sheets on the fiber surface as a conformal coating. Analysis of the fabric surface using UV-vis absorption allowed identification of the ratio of hydrophobic to hydrophilic domains present on the GO coated cotton fabric surface. Hydrophobic properties on cotton fabric are ascribed to two dimensional amphiphilic properties of deposited GO nano sheets, which successfully lower the interfacial energy of the fabric surface.

  12. Dynamic Ordering Transitions of Liquid Crystals Driven by Interfacial Complexes Formed Between Polyanions and Amphiphilic Polyamines

    Science.gov (United States)

    Kinsinger, Michael I.; Buck, Maren E.; Campos, Fernando

    2011-01-01

    We report the design of an amphiphilic polyamine based on poly(2-alkenyl azlactone) (polymer 1) that strongly couples the formation of polyelectrolyte complexes at aqueous/liquid crystal (LC) interfaces to ordering transitions in the LC. We demonstrate that the addition of a strong anionic polyelectrolyte to aqueous solutions in contact with polymer 1-laden LC interfaces (prepared by Langmuir-Schaefer transfer of monolayers of polymer 1 onto micrometer-thick films of nematic LC) triggers ordering transitions in the LCs. We further demonstrate that changes in the ordering of the LCs (i) are driven by electrostatic interactions between the polyelectrolytes, (ii) involve multivalent interactions between the polyelectrolytes, and (iii) are triggered by reorganization of the hydrophobic side chains of amphiphilic polymer 1 upon formation of the interfacial complexes. The results presented in this paper lead us to conclude that ordering transitions in LCs can be used to provide insights into the structure and dynamics of interfacial complexes formed between polyelectrolytes. PMID:18991416

  13. Discriminating binding and positioning of amphiphiles to lipid bilayers by 1H NMR

    International Nuclear Information System (INIS)

    The binding and positioning in lipid bilayers of three well-known drugs--imipramine, nicotine, and caffeine--have been studied using 1H NMR. The membrane model system consisted of 'fast-tumbling' lipid bicelles, in which a bilayered lipid domain, composed of the unsaturated lipid, 1,2-dimyristelaidoyl-sn-glycero-3-phosphocholine (DMLPC) was surrounded by a rim of deuterated detergent-like lipids, consisting of 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC-d22). Binding and immersion depth information was obtained by three experiments. (1) 1H chemical shift perturbations, upon transfer of the amphiphiles from water to a bicelle mixture, were used to estimate regions of the amphiphiles that interact with the membrane. (2) Water contact to resolvable protons was measured through a Nuclear Overhauser Effect (NOE) between water and resolvable drug and lipid resonances. In the case of both lipids and membrane bound drugs, positive NOEs with large cross-relaxation rates were measured for most resonances originating from the membrane hydrophilic region, while negative NOEs were observed predominantly to resonances in the hydrophobic region of the membrane. (3) 1H NMR measurements of oxygen-induced (paramagnetic) spin-lattice relaxation rates, which are known to increase with membrane immersion depth, were used to corroborate conclusions based on chemical shift perturbations and water-ligand NOEs

  14. Comparison of facially amphiphilic versus segregated monomers in the design of antibacterial copolymers.

    Science.gov (United States)

    Gabriel, Gregory J; Maegerlein, Janet A; Nelson, Christopher F; Dabkowski, Jeffrey M; Eren, Tarik; Nüsslein, Klaus; Tew, Gregory N

    2009-01-01

    A direct comparison of two strategies for designing antimicrobial polymers is presented. Previously, we published several reports on the use of facially amphiphilic (FA) monomers which led to polynorbornenes with excellent antimicrobial activities and selectivities. Our polymers obtained by copolymerization of structurally similar segregated monomers, in which cationic and non-polar moieties reside on separate repeat units, led to polymers with less pronounced activities. A wide range of polymer amphiphilicities was surveyed by pairing a cationic oxanorbornene with eleven different non-polar monomers and varying the comonomer feed ratios. Their properties were tested using antimicrobial assays and copolymers possessing intermediate hydrophobicities were the most active. Polymer-induced leakage of dye-filled liposomes and microscopy of polymer-treated bacteria support a membrane-based mode of action. From these results there appears to be profound differences in how a polymer made from FA monomers interacts with the phospholipid bilayer compared with copolymers from segregated monomers. We conclude that a well-defined spatial relationship of the whole polymer is crucial to obtain synthetic mimics of antimicrobial peptides (SMAMPs): charged and non-polar moieties need to be balanced locally, for example, at the monomer level, and not just globally. We advocate the use of FA monomers for better control of biological properties. It is expected that this principle will be usefully applied to other backbones such as the polyacrylates, polystyrenes, and non-natural polyamides. PMID:19021176

  15. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    International Nuclear Information System (INIS)

    Fullerene C60 sub-colloidal particle with diameter ∼1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C60 fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent molecules—water retardation—in the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the “dangling” –OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some “dry” regions of C60 are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique

  16. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    Energy Technology Data Exchange (ETDEWEB)

    Varanasi, S. R., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de; John, A. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Guskova, O. A., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Sommer, J.-U. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Institut für Theoretische Physik, Technische Universität Dresden, Zellescher Weg 17, Dresden D-01069 (Germany)

    2015-06-14

    Fullerene C{sub 60} sub-colloidal particle with diameter ∼1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C{sub 60} fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent molecules—water retardation—in the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the “dangling” –OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some “dry” regions of C{sub 60} are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique.

  17. Hydration-Induced Phase Separation in Amphiphilic Polymer Matrices and its Influence on Voclosporin Release

    Energy Technology Data Exchange (ETDEWEB)

    Khan, I. John [The State Univ. of New Jersey, Piscataway, NJ (United States); Murthy, N. Sanjeeva [The State Univ. of New Jersey, Piscataway, NJ (United States); Kohn, Joachim [The State Univ. of New Jersey, Piscataway, NJ (United States)

    2015-10-30

    Voclosporin is a highly potent, new cyclosporine -- a derivative that is currently in Phase 3 clinical trials in the USA as a potential treatment for inflammatory diseases of the eye. Voclosporin represents a number of very sparingly soluble drugs that are difficult to administer. It was selected as a model drug that is dispersed within amphiphilic polymer matrices, and investigated the changing morphology of the matrices using neutron and x-ray scattering during voclosporin release and polymer resorption. The hydrophobic segments of the amphiphilic polymer chain are comprised of desaminotyrosyl-tyrosine ethyl ester (DTE) and desaminotyrosyl-tyrosine (DT), and the hydrophilic component is poly(ethylene glycol) (PEG). Water uptake in these matrices resulted in the phase separation of hydrophobic and hydrophilic domains that are a few hundred Angstroms apart. These water-driven morphological changes influenced the release profile of voclosporin and facilitated a burst-free release from the polymer. No such morphological reorganization was observed in poly(lactide-co-glycolide) (PLGA), which exhibits an extended lag period, followed by a burst-like release of voclosporin when the polymer was degraded. An understanding of the effect of polymer composition on the hydration behavior is central to understanding and controlling the phase behavior and resorption characteristics of the matrix for achieving long-term controlled release of hydrophobic drugs such as voclosporin.

  18. Effect of headgroup-substrate interactions on the thermal behavior of long-chain amphiphiles

    Science.gov (United States)

    Singla, Saranshu; Zhu, He; Dhinojwala, Ali

    The structure of amphiphilic molecules at liquid/solid and solid/solid interfaces is relevant in understanding lubrication, colloid stabilization, chromatography, and nucleation. Here, we characterize the interfacial structures of long chain amphiphilic molecules with different head groups (OH, COOH, NH2) using interface-sensitive sum frequency generation (SFG) spectroscopy. The behavior of these self-assembled monolayers (SAMs) on sapphire substrate is recorded in situ as a function of temperature (above and below bulk Tm) using SFG. Previous studies using synchrotron X-ray reflectivity and SFG show that the melting point of an ordered hexadecanol monolayer is around 30°C above its bulk Tm. The thermal stability of the monolayer is explained due to strong hydrogen bonding interactions between the head-group and the sapphire substrate. The strength of these hydrogen-bonding interactions between substrate and different head groups is calculated using the Badger-Bauer equation. Below Tm, the ordered monolayer influenced the structure of the interfacial crystalline layer, and the transition from monolayer to the bulk crystalline phases. The results with different head groups will be presented.

  19. Preparation of pH-responsive membranes with amphiphilic copolymers by surface segregation method☆

    Institute of Scientific and Technical Information of China (English)

    Yanlei Su; Yuan Liu; Xueting Zhao; Yafei Li; Zhongyi Jiang

    2015-01-01

    Novel pH-responsive membranes were prepared by blending pH-responsive amphiphilic copolymers with pol-yethersulfone (PES) via a nonsolvent-induced phase separation (NIPS) technique. The amphiphilic copolymers bearing Pluronic F127 and poly(methacrylic acid) (PMAA) segments, abbreviated as PMAAn–F127–PMAAn, were synthesized by free radical polymerization. The physical and chemical properties of the blend membranes were evaluated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrum, water con-tact angle, Zeta potential and X-ray photoelectron spectroscopy (XPS). The enrichment of hydrophilic PMAA seg-ments on the membrane surfaces was attributed to surface segregation during the membrane preparation process. The blend membranes had significant pH-responsive properties due to the conformational changes of surface-segregated PMAA segments under different pH values of feed solutions. Fluxes of the blend membranes were larger at low pH values of feed solutions than that at high pH values. The pH-responsive ability of the mem-branes was enhanced with the increase of the degree of PMAA near-surface coverage.

  20. Polydispersity-Driven Block Copolymer Amphiphile Self-Assembly into Prolate-Spheroid Micelles

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Andrew L.; Repollet-Pedrosa, Milton H.; Mahanthappa, Mahesh K. (UW)

    2013-09-26

    The aqueous self-assembly behavior of polydisperse poly(ethylene oxide-b-1,4-butadiene-b-ethylene oxide) (OBO) macromolecular triblock amphiphiles is examined to discern the implications of continuous polydispersity in the hydrophobic block on the resulting aqueous micellar morphologies of otherwise monodisperse polymer surfactants. The chain length polydispersity and implicit composition polydispersity of these samples furnishes a distribution of preferred interfacial curvatures, resulting in dilute aqueous block copolymer dispersions exhibiting coexisting spherical and rod-like micelles with vesicles in a single sample with a O weight fraction, w{sub O}, of 0.18. At higher w{sub O} = 0.51-0.68, the peak in the interfacial curvature distribution shifts and we observe the formation of only American football-shaped micelles. We rationalize the formation of these anisotropically shaped aggregates based on the intrinsic distribution of preferred curvatures adopted by the polydisperse copolymer amphiphiles and on the relief of core block chain stretching by chain-length-dependent intramicellar segregation.