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Sample records for amphiphilic octenyl succinic

  1. 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 ...

  2. 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...

  3. 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% (...

  4. Preparation, characterization and antibacterial activity of octenyl succinic anhydride modified inulin.

    Science.gov (United States)

    Zhang, Xiaoyun; Zhang, Ye-Wang; Zhang, Hongyin; Yang, Qiya; Wang, Haiying; Zhang, Guochao

    2015-01-01

    Octenyl succinic anhydride modified inulin (In-OSA) was synthesized via chemical modification of inulin with octenyl succinic anhydride (OSA). The esterification of inulin with OSA was confirmed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and degree of substitution (DS) calculation. Antibacterial activity of In-OSA against Staphylococcus aureus and Escherichia coli was investigated by minimum inhibitory concentration (MIC) and inhibition rate determination. The results showed that inhibition rates against both E.coli and S. aureus increased with the increase of the In-OSA concentration. And the MICs against E. coli and S. aureus were 1% and 0.5% (w/v), respectively. The antibacterial mechanism was analyzed with the results of the proteins and nucleic acids leakage, SEM and negative staining transmission electron microscopy (TEM). Both the leakages of proteins and nucleic acids increased with the increase of the In-OSA concentration. The leakage occurred mainly in the early stage which indicated that cell membrane and wall were destroyed by In-OSA quickly. The images of SEM and negative staining TEM suggested that the cell membranes and cell walls of S. aureus were damaged more severely and even destroyed completely; but only pores appeared on the surface of E. coli.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. Synthesis Technology of Octenyl Succinic Acid Cross - Link Starch Esters%辛烯基琥珀酸交联淀粉酯合成工艺研究

    Institute of Scientific and Technical Information of China (English)

    石海信; 谢新玲; 张友全; 童张法

    2009-01-01

    以木薯淀粉为原料,用环氧氯丙烷作交联剂,辛烯基琥珀酸酐作酯化剂,采用湿法工艺合成辛烯基琥珀酸交联淀粉酯.探讨了淀粉乳浓度、反应温度、反应时间、pH和沉降积对辛烯基琥珀酸交联淀粉酯取代度的影响,确定制备辛烯基琥珀酸交联淀粉酯的最佳工艺参数为:淀粉乳浓度35%,酯化pH 8.0,酯化温度35℃,酯化时间3 h.交联淀粉的沉降积对酯化取代度影响较小,在生产中可根据最终产品的用途选用合适沉降积的交联淀粉进行酯化复合变性.复合变性淀粉符合食品行业标准,可以在食品工业中应用.扫描电镜对其结构进行观察显示淀粉中受侵蚀颗粒增多,颗粒表面的小凹痕数量增加.%Octenyl succinic acid cross - link starch esters were prepared by wet process with cassava starch as raw material, epichlorohydrin as cross - link agent and octenyl succinic anhydride as esterifying agent. The effects of starch slurry concentration, reaction temperature, reaction time, pH and sediment volume on the substitution degree of octenyl succinic acid cross - link starch esters were studied. Results; The optimal conditions for preparing octenyl succinic acid cross -link starch esters are starch slurry concentration 35% , esterification pH 8.0, esterification temperature 35 ℃ and esterification time 3 h. The sediment volume of cross - link starch has little effect on the substitution degree. Thus, a proper sediment volume can be determined according to the usage of final octenyl succinic acid cross - link starch esters. The produced octenyl succinic acid cross - link starch esters are identified safe to be used in food industry. The result of scanning electron microscope observation shows that the number of dents and splits in the granule surface of the prepared starch increases.

  10. 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

  11. Preparation of Octenyl Succinic Anhydride Modified Broken Rice Starch%辛烯基琥珀酸碎米淀粉酯的制备

    Institute of Scientific and Technical Information of China (English)

    苟林; 王泽南; 韩堂健; 蒋艳; 徐春泽

    2011-01-01

    Broken rice starch was modified with octenyl succinic anhydride in aqueous slurry system.The modification process was optimized by one-factor-at-a-time and orthogonal array design methods to achieve maximum degree of substitution(DS).The results showed that the optimal process conditions were found to be: starch slurry concentration 30%,pH 8.5,reaction time 5 h,and reaction temperature 35 ℃.Under the optimal conditions,the degree of substitution was 0.01445.%以碎米淀粉为原料,采用湿法制备辛烯基琥珀酸碎米淀粉酯,以取代度为评价指标,确定辛烯基琥珀酸酐添加量为3%,通过单因素与正交试验确定辛烯基琥珀酸碎米淀粉酯的最佳制备工艺。结果显示:淀粉乳质量分数30%、pH8.5、反应时间5h、反应温度35℃为最佳工艺条件,在此条件下所得产品取代度可达0.01445。

  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. 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

    and structurally characterised by Fourier transform-infrared spectroscopy and proton nuclear magnetic resonance spectroscopy (1H NMR). The influence of four reaction parameters on the DS of the derivatives was studied by means of an experimental design. The results showed that the OSA/HA molar ratio, the buffer...

  15. Optimization condition of octenyl succinic anhydride hydrolysis starch by enzymolysis%酶法制备辛烯基琥珀酸酐水解淀粉的工艺及其优化

    Institute of Scientific and Technical Information of China (English)

    邹建; 刘亚伟

    2011-01-01

    以玉米淀粉为原料,用α-淀粉酶对合成的辛烯基琥珀酸酐淀粉水解,研究酶法制备辛烯基琥珀酸酐水解淀粉的工艺条件,并通过响应面分析实验对工艺进行优化。确定合成的最佳工艺参数为:酶用量115U/g,水解温度95℃,水解时间49min,所得产品辛烯基琥珀酸酐水解淀粉的DE值为8.01。通过响应面方差分析可以得出,三个因素对辛烯基琥珀酸酐水解淀粉的DE值的影响显著,且加酶量与水解温度、水解温度与水解时间之间的交互影响作用也显著。%The synthesis process condition of enzymatic octenyl succinic anhydride(OSA)corn starch was researched.Through hydrolysis response surface analysis,the results showed that the optimum condition of synthesizing enzymatic OSA corn starch(DE=8.01)was enzyme dosage 115U/g,hydrolysis temperature 95℃,hydrolysis time 49 minutes;enzyme dosage and hydrolysis temperature,hydrolysis temperature and hydrolysis time interacted significantly;DE value increased significantly higher in high temperature than in low temperature.

  16. Properties of Octenyl Succinic Anhydride Modified Starch and Its Application in Chicken Sausages%辛烯基琥珀酸淀粉酯的特性分析及在鸡肉灌肠中的应用

    Institute of Scientific and Technical Information of China (English)

    宋晓燕; 董振江; 李真; 杨延超; 裴亚琼

    2012-01-01

    以早籼米淀粉为原料,采用水相体系制备不同黏度的辛烯基琥珀酸淀粉酯,并对其糊化特性、冻融稳定性及在鸡肉灌肠中的应用进行研究。结果表明:淀粉经酸解和辛烯基琥珀酸酐改性后,可以得到不同黏度的辛烯基琥珀酸淀粉酯,具有良好的冻融稳定性。在鸡肉灌肠中应用时,加入早籼米辛烯基琥珀酸淀粉酯的鸡肉灌肠与加入木薯变性淀粉的鸡肉灌肠相比较,其硬度、弹性和咀嚼性都有不同程度的提高(p〈0.05)。扫描电子显微镜分析显示,添加木薯变性淀粉的样品,内部结构比较蓬松,而添加早籼米OSA-H6的样品,其内部组织则相对紧实细腻。该研究表明,辛烯基琥珀酸酐改性淀粉(烯基琥珀酸淀粉酸)可以改善肉制品的质构特性,在肉制品中具有潜在的应用价值。%Octenyl succinic anhydride (OSA) modified starches with different viscosities were prepared from early indica rice starch in aqueous slurry systems. The pasting property and freeze-thaw stability of the products were analyzed and their application in chicken sausages was evaluated. The results showed that acid hydrolysis of starch followed by OSA modification produced OSA modified starch, which had better freeze-thaw stability than its native counterpart. The texture of sausages with added OSA modified indica rice starch was improved in hardness, springiness and chewiness when compared to sausages with added modified tapioca starch (P 〈 0.05). SEM observations revealed that sausages with the addition of tapioca modified starch had large pores in its structure and fluffy texture, while sausages with the addition of OSA modified indica rice starch was compact in texture. In summary, OSA modified starch can improve texture characteristics of meat products and consequently holds potential for applications in meat products.

  17. Process Optimization for Synthesis of Octenyl Succinic Anhydride Modified Oxidized Sweet Potato Starch by Response Surface Analysis%响应面法优化氧化辛烯基琥珀酸甘薯淀粉酯的制备工艺

    Institute of Scientific and Technical Information of China (English)

    刘强; 邬应龙; 何靖柳

    2011-01-01

    以氧化甘薯淀粉(oxidation sweet potato starch,OSPS)为原料,制备氧化辛烯基琥珀酸甘薯淀粉酯(octenylsuccinate anhydride-oxidation sweet potato starch,OSA-OSPS)。运用响应面分析(response surface method analysis,RSA)辛烯基琥珀酸酐(octenyl succinate anhydride,OSA)添加量、pH值、温度和时间对OSA-OSPS取代度(degreeof substitution,DS)的影响,得出最佳制备工艺:酸酐添加量7%、pH8.40、温度40℃,反应时间10h。采用快速黏度分析仪(rapid viscosity analyzer,RVA)分析表明:氧化甘薯淀粉峰值黏度较低,而经过OSA酯化后,峰值黏度又会有一定程度的提高,且随DS的增加呈上升趋势。%Oxidized sweet potato starch was used as the raw material to prepare octenyl succinic anhydride(OSA) modified oxidized sweet potato starch.The effects of OSA amount,pH,temperature and reaction time on degree of substitution(DS) of OSA-modified oxidized sweet potato starch were studied employing response surface analysis.The optimum process conditions determined were as follows: OSA amount 7%,pH 8.40,temperature 40 ℃,and reaction time 10 h.Rapid viscosity analyzer(RVA) analysis showed that the peak viscosity of sweet potato starch decreased after oxidation,and increased after furthermodification with OSA with a positive correlation with DS.

  18. Study on Preparation of Cross-Linked Cassava Starch Octenyl Succinate by the Mothod of Extrusion and Structure Characterization%挤压法制备交联辛烯基琥珀酸木薯淀粉酯工艺与结构表征

    Institute of Scientific and Technical Information of China (English)

    李彬; 王金鹏; 谢正军; 徐学明; 田耀旗; 金征宇

    2012-01-01

    The preparation of cassava cross-linked starch octenyl succinate by the mothod of extrusion was studied in this manuscript. The effect of the content of sodium trimetaphosphate. sodium hydroxide,moisture,reaction temperature and screwing speed on the emulsifying capacity were carefully investigated by single factor experiment. The optimum conditions of cassava cross-linked starch octenyl succinate preparation were- 1.0% sodium trimetaphosphate,0. 6 % sodium hydroxide,moisture 35 %,barrel temperature 120 ℃,and screwing speed 110 r/min. the emulsifying capacity of the product reached at 58. 56 %. The structure of the product was determined by means of Fourier transform infrared spectroscopy(FT-IR),scanning e-lectron microscopy(SEM) and X-ray diffraction(XRD).%采用挤压法研究了交联辛烯基琥珀酸木薯淀粉酯的工艺.探讨三偏磷酸钠、氢氧化钠、水分质量分数,以及出料温度和螺杆转速对交联淀粉酯乳化能力的影响,并对影响因素进行了正交优化.结果表明,在三偏磷酸钠质量分数1.0%,氢氧化钠质量分数0.6%,水分质量分数35%,出料温度120℃,螺杆转速110 r/min的反应条件下,制备得到的交联辛烯基琥珀酸木薯淀粉酯的乳化能力可以达到58.56%.同时,采用红外光谱、电镜扫描和X射线衍射等手段对产物进行了结构分析和表征.

  19. Performance of non-crystal cross-linked octenyl succinic anhydride starch ester synthesized through one-step process%非晶交联辛烯基琥珀酸淀粉酯的一步法合成及其性能

    Institute of Scientific and Technical Information of China (English)

    陆来仙; 童张法; 石海信; 张友全

    2014-01-01

    Using non-crystal starch (N-NS) as raw material,sodium trimetaphosphate (STMP) and Octenyl Succinic Anhydride (OSA) as modification agents,non-crystal cross-linked octenyl succinic anhydride starch ester (N-1-COSAS) was synthesized by one-step process. The properties of N-1-COSAS,such as degree of substitution,combined phosphorus,intrinsic viscosity,transparency, apparent viscosity and blue value,were comparatively studied by the product synthesized by three-step process (N-3-COSAS) to analyze their similarities and differences. The functional groups, morphology,crystal structure and thermostability of the products were characterized by Fourier transform infrared spectroscopy (FT-IR),scanning electron microscopy (SEM),X-ray diffraction and differential scanning calorimetry (DSC). The results showed that the degree of substitution,combined phosphorus and intrinsic viscosity for N-1-COSAS were greater than those by N-3-COSAS. The new absorption peak at 1600 cm-1 appeared in the FT-IR spectrum of the two starch esters demonstrated that the esterification reaction were occurred in both processes. The results of XRD indicated that the dispersion degrees of the peaks in N-1-COSAS and N-3-COSAS were similar to those of N-NS but the crystallinities of N-1-COSAS and N-3-COSAS were lower than that of NS. The particle surfaces of N-1-COSAS and N-3-COSAS were rougher than that of N-NS. Moreover , thermostabilities of N-1-COSAS and N-3-COSAS were better than that of N-NS.%以非晶木薯淀粉(N-NS)为原料,三偏磷酸钠(STMP)和辛烯基琥珀酸酐(OSA)为变性剂,采用一步法合成非晶交联辛烯基琥珀酸淀粉酯(N-1-COSAS),测定产物的取代度、结合磷含量、透明度、表观黏度、特性黏度和蓝值,并与三步法合成的非晶交联辛烯基琥珀酸淀粉酯(N-3-COSAS)作对比。同时采用傅里叶红外光谱仪(FT-IR)、扫描电镜(SEM)、X射线衍射仪(XRD)和差示扫描量热仪(DSC)

  20. 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

  1. 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.

  2. Bis(4-methylimidazolium succinate succinic acid solvate

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available In the title compound, 2C4H7N2+·C4H4O42−·C4H6O4, the asymmetric unit consists of two 4-methylimidazolium cations, one succinate dianion and one netrual succinic acid molecule and within the latter components, the C—O, C=O and C...;O bonds are clearly evidenced from their relative distances. In the crystal structure, the individual components are linked by intermolecular N—H...O, O—H...O and C—H...O hydrogen bonds into a two-dimensional network parallel to the (101 plane in which R33(9, R33(12 and R44(18 hydrogen-bond motifs are present.

  3. The role of amphiphiles

    NARCIS (Netherlands)

    Hoekstra, F.A.; Golovina, E.A.

    2002-01-01

    This paper reviews our work on the partitioning of amphiphilic compounds from the cytoplasm into membranes during drying of plant systems, and discusses how relevant this phenomenon might be for anhydrobiosis. Amphiphilic guest molecules do partition into membranes and oil bodies, as demonstrated by

  4. Succination of proteins in diabetes.

    Science.gov (United States)

    Frizzell, Norma; Lima, Maria; Baynes, John W

    2011-01-01

    Cysteine is arguably the most reactive amino acid in protein. A wide range of cysteine derivatives is formed in vivo, resulting from oxidation, nitrosation, alkylation and acylation reactions. This review describes succination of proteins, an irreversible chemical modification of cysteine by the Krebs cycle intermediate, fumarate, yielding S-(2-succinyl)cysteine (2SC). Intracellular fumarate concentration and succination of proteins are increased by hyperpolarization of the inner mitochondrial membrane and develop in concert with mitochondrial and oxidative stress in diabetes. Increased succination of glyceraldehyde-3-phosphate dehydrogenase explains the loss in specific activity of this enzyme in muscle of streptozotocin-diabetic rats and increased succination of adiponectin may explain the decreased secretion of adiponectin from adipose tissue in type 2 diabetes. In addition to GAPDH and adiponectin, other succinated proteins identified in adipocytes include cytoskeletal proteins (tubulin, actin) and chaperone proteins in the endoplasmic reticulum. Succination of adipocyte protein in vitro is inhibited by uncouplers of oxidative phosphorylation and by inhibitors of ER stress. 2SC serves as a biomarker of mitochondrial stress and recent studies suggest that succination is the mechanistic link between mitochondrial and ER stress in diabetes.

  5. 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)

  6. 21 CFR 582.1091 - Succinic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Succinic acid. 582.1091 Section 582.1091 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1091 Succinic acid. (a) Product. Succinic acid. (b) Conditions of use. This substance is...

  7. Amphiphilic dendronized homopolymers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of second generation of amphiphilic dendronized homopolymers are efficiently synthesized,and their thermoresponsiveness in aqueous solutions and secondary structures in methanol solutions are described.These polymers are constructed in each repeat unit with various generations of hydrophobic 4-aminoproline and hydrophilic oligoethylene glycol (OEG)-based dendrons,and their over-all hydrophilicity is tuned by varying these dendron generations.Polymers with or without the first generation of proline dendron show good water solubility at room temperature,but exhibit typical thermoresponsive behaviors at elevated temperatures as characterized by turbidity measurements using UV-vis spectroscopy,while the polymer with the secondary generation of proline dendron is not soluble in water.All polymers show ordered secondary structures as evidenced by the optical rotation and circular dichroism experiments.Finally,assembly of these amphiphilic homopolymers into porous films via breath figure (BF) technique is described,and polymer structures are found to show significant influence on the morphology of porous film.

  8. 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

  9. Succinic acid production from Jerusalem artichoke

    DEFF Research Database (Denmark)

    Gunnarsson, Ingólfur Bragi; Karakashev, Dimitar Borisov; Angelidaki, Irini

    In this work, A. succinogenes 130Z was used to produce succinic acid from Jerusalem artichoke tuber hydrolysate. Results showed that both fructose and glucose in the tuber hydrolysate were utilized for succinic acid production. The sugar utilization was found to be dependent on process control......, hence, when pH was fixed at 6.8 the sugar utilization of fructose was increased from 68.6% to 96.5% and the succinic acid production was also increased by 26.4% to yield 26.8 g/L succinic acid. In this study a one-step pretreatment/hydrolysis method was used where no enzymes were used. Our work suggests...... that Jerusalem artichoke tubers could be utilized for production of bio-succinic acid....

  10. 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.

  11. 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.

  12. Downstream processing of biotechnological produced succinic acid.

    Science.gov (United States)

    Cheng, Ke-Ke; Zhao, Xue-Bing; Zeng, Jing; Wu, Ru-Chun; Xu, Yun-Zhen; Liu, De-Hua; Zhang, Jian-An

    2012-08-01

    Succinic acid is a promising chemical which has a wide range of applications and can be biologically produced. The separation of succinic acid from fermentation broth makes more than 50 % of the total costs in their microbial production. This review summarizes the present state of methods studied for the recovery and purification of biologically produced succinate. Previous studies on the separation of succinic acid primarily include direct crystallization, precipitation, membrane separation, extraction, chromatography, and in situ separation. No single method has proved to be simple and efficient, and improvements are especially needed with regard to yield, purity, and energy consumption. It is argued that separation technologies coupled with upstream technology, in situ product removal, and biorefining strategy deserve more attentions in the future. PMID:22707056

  13. 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.

  14. 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.

  15. Tandem Facial Amphiphiles for Membrane Protein Stabilization

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Gotfryd, Kamil; Pacyna, Jennifer;

    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....

  16. 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.

  17. Recovery of succinic acid from fermentation broth.

    Science.gov (United States)

    Kurzrock, Tanja; Weuster-Botz, Dirk

    2010-03-01

    Succinic acid is of high interest as bio-feedstock for the chemical industry. It is a precursor for a variety of many other chemicals, e.g. 1,4-butandiol, tetrahydrofuran, biodegradable polymers and fumaric acid. Besides optimized production strains and fermentation processes it is indispensable to develop cost-saving and energy-effective downstream processes to compete with the current petrochemical production process. Various methods such as precipitation, sorption and ion exchange, electrodialysis, and liquid-liquid extraction have been investigated for the recovery of succinic acid from fermentation broth and are reviewed critically here. PMID:19898782

  18. 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

  19. 21 CFR 172.275 - Synthetic paraffin and succinic derivatives.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Synthetic paraffin and succinic derivatives. 172... FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.275 Synthetic paraffin and succinic derivatives. Synthetic paraffin and succinic derivatives identified in this section may be...

  20. 21 CFR 184.1091 - Succinic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Succinic acid. 184.1091 Section 184.1091 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS §...

  1. 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.

  2. Bis(ethanolaminium succinate–succinic acid (1/1

    Directory of Open Access Journals (Sweden)

    Miao Zhang

    2011-09-01

    Full Text Available The asymmetric unit of the title compound, 2C2H8NO+·C4H4O42−·C4H6O4, consists of half a succinate anion, half a succinic acid molecule and one ethanolaminium cation. The succinate anion and succinic acid molecule, both of which are located on inversion centres, are linked by O—H...O hydrogen bonds, forming a chain along the [2overline{1}0] direction. The chain and the ethanolaminium cation are further connected by O—H...O and N—H...O hydrogen bonds.

  3. Succinic acid adsorption from fermentation broth and regeneration.

    Science.gov (United States)

    Davison, Brian H; Nghiem, Nhuan P; Richardson, Gerald L

    2004-01-01

    More than 25 sorbents were tested for uptake of succinic acid from aqueous solutions. The best resins were then tested for successive loading and regeneration using hot water. The key desired properties for an ideal sorbent are high capacity, complete stable regenerability, and specificity for the product. The best resins have a stable capacity of about 0.06 g of succinic acid/g of resin at moderate concentrations (1-5 g/L) of succinic acid. Several sorbents were tested more exhaustively for uptake of succinic acid and for successive loading and regeneration using hot water. One resin, XUS 40285, has a good stable isotherm capacity, prefers succinate over glucose, and has good capacities at both acidic and neutral pH. Succinic acid was removed from simulated media containing salts, succinic acid, acetic acid, and sugar using a packed column of sorbent resin, XUS 40285. The fermentation byproduct, acetate, was completely separated from succinate. A simple hot water regeneration successfully concentrated succinate from 10 g/L (inlet) to 40-110 g/L in the effluent. If successful, this would lower separation costs by reducing the need for chemicals for the initial purification step. Despite promising initial results of good capacity (0.06 g of succinic/g of sorbent), 70% recovery using hot water, and a recovered concentration of >100 g/L, this regeneration was not stable over 10 cycles in the column. Alternative regeneration schemes using acid and base were examined. Two (XUS 40285 and XFS-40422) showed both good stable capacities for succinic acid over 10 cycles and >95% recovery in a batch operation using a modified extraction procedure combining acid and hot water washes. These resins showed comparable results with actual broth. PMID:15054284

  4. Computational Amphiphilic Materials for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Naresh eThota

    2015-10-01

    Full Text Available Amphiphilic materials can assemble into a wide variety of morphologies and have emerged as a novel class of candidates for drug delivery. Along with a large number of experiments reported, computational studies have been also conducted in this field. At an atomistic/molecular level, computations can facilitate quantitative understanding of experimental observations and secure fundamental interpretation of underlying phenomena. This review summarizes the recent computational efforts on amphiphilic copolymers and peptides for drug delivery. Atom-resolution and time-resolved insights are provided from bottom-up to microscopically elucidate the mechanisms of drug loading/release, which are indispensable in the rational screening and design of new amphiphiles for high-efficacy drug delivery.

  5. 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.

  6. 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.

  7. 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.

  8. Preparation and Structure Characterization of Non-crystal Crosslinked Octenyl Succinic Anhydride Starch%非晶交联辛烯基琥珀酸淀粉酯的制备与结构表征

    Institute of Scientific and Technical Information of China (English)

    陆来仙; 童张法; 石海信; 张友全

    2014-01-01

    以木薯淀粉为原料,三偏磷酸钠(STMP)和辛烯基琥珀酸酐(OSA)为变性剂,用乙醇溶剂法合成非晶交联辛烯基琥珀酸淀粉酯(N-COSAS).以结合磷含量(CP)、取代度(DS)、黏度(η)为评价指标,探讨STMP用量(占淀粉干基的质量分数),交联时间、交联温度、交联pH值和酯化时间、酯化温度、酯化pH值等因素对CP或DS和η的影响.通过单因素和正交试验,得出制备低黏度N-COSAS的较佳工艺条件:在加入STMPl.5%时,交联反应的时间、温度和pH值分别为4h,45℃和10.0,酯化反应的时间、温度和pH值分别为3h、35℃和8.5.扫描电镜观察显示N-COSAS颗粒表面有明显裂痕,表面被卷起;X射线衍射图谱显示,N-COSAS的相对结晶度为8.24%,晶型属于Ⅴ型;红外光谱显示,N-COSAS在1570.06 cm-1处出现新的吸收峰,在929.69 cm-1处峰的强度增加,证明在淀粉分子中引入了辛烯基琥珀酸基团和交联键.

  9. 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.

  10. Self-Assembly and Hydrogelation of Peptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Wahyudi Priyono Suwarso

    2012-04-01

    Full Text Available Seven peptide amphiphiles were successfully synthesized using solid phase peptide synthesis method. Peptide amphiphiles were characterized using matrix assisted laser desorption/ionization (MALDI. Atomic force microscopy (AFM study showed that peptide amphiphiles having glycine, valine, or proline as linker, self-assembled into 100-200 nm nanofibers structure. According to our research, both peptide amphiphile with positive and negative charges bear similar self-assembly properties. Peptide amphiphile also showed its capability as low molecular weight gelator (LMWG. Peptide amphiphiles bearing C-16 and C-12 as alkyl showed better hydrogelation properties than C-8 alkyl. Five out of seven peptide amphiphiles have minimum gelation concentration (MGC lower than 1% (w/v.

  11. 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

  12. 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...

  13. 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.

  14. 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...

  15. Data on the mechanisms underlying succinate-induced aortic contraction.

    Science.gov (United States)

    Gonzaga, Natália A; Simplicio, Janaina A; Leite, Letícia N; Vale, Gabriel T; Carballido, José M; Alves-Filho, José C; Tirapelli, Carlos R

    2016-12-01

    We describe the mechanisms underlying the vascular contraction induced by succinate. The data presented here are related to the article entitled "Pharmacological characterization of the mechanisms underlying the vascular effects of succinate" (L.N. Leite, N.A. Gonzaga, J.A. Simplicio, G.T. Vale, J.M. Carballido, J.C. Alves-Filho, C.R. Tirapelli, 2016) [1]. Succinate acts as a signaling molecule by binding to a G-protein-coupled receptor termed GPR91, "Citric acid cycle intermediates as ligands for orphan G-protein-coupled receptors" (W. He, F.J. Miao, D.C. Lin, R.T. Schwandner, Z. Wang, J. Gao, J.L. Chen, H. Tian, L. Ling, 2004) [2]. Here we include data on the contractile effect of succinate in the aorta. Succinate contracted both endothelium-intact and endothelium-denuded aortic rings isolated from male Wistar rats or C57BL/6 mice. Succinate was less effective at inducing contraction in arteries isolated from GPR91-deficient mice, when compared to its vascular effect in aortas from wild type mice. SB203508 (p38MAK inhibitor), SP600125 (JNK inhibitor) and Y27632 (Rho-kinase inhibitor) reduced succinate-induced contraction in both endothelium-intact and endothelium-denuded rat aortic rings, while PD98059 (ERK1/2 inhibitor) did not affect succinate-induced contraction. The contractile response induced by succinate on endothelium-intact and endothelium-denuded rat aortic rings was reduced by indomethacin (non-selective cyclooxygenase inhibitor), H7 (protein kinase C inhibitor), verapamil (Ca(2+) channel blocker) and tiron (superoxide anion scavenger).

  16. 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...

  17. 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 ...

  18. 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 ...

  19. Novel membrane-based biotechnological alternative process for succinic acid production and chemical synthesis of bio-based poly (butylene succinate).

    Science.gov (United States)

    Wang, Caixia; Ming, Wei; Yan, Daojiang; Zhang, Congcong; Yang, Maohua; Liu, Yilan; Zhang, Yu; Guo, Baohua; Wan, Yinhua; Xing, Jianmin

    2014-03-01

    Succinic acid was produced in a novel membrane-based fermentation and separation integrated system. With this integrated system, product inhibition was alleviated by removing acids and replenishing fresh broth. High cell density maintain for a longer time from 75 to 130h and succinic acid concentration increased from 53 to 73g/L. In the developed separation process, succinic acid was crystallized at a recovery of 85-90%. The purity of the obtained succinic acid crystals reached 99.4% as found by HPLC and (1)H NMR analysis. A crystallization experiment indicated that among by-products glucose had a negative effect on succinic acid crystallization. Poly (butylene succinate) (PBS) was synthesized using the purified succinic acid and (1)H NMR analysis confirmed that the composition of the synthesized PBS is in agreement with that from petro-based succinic acid. PMID:24472699

  20. 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

  1. Succination of thiol groups in adipose tissue proteins in diabetes: succination inhibits polymerization and secretion of adiponectin.

    Science.gov (United States)

    Frizzell, Norma; Rajesh, Mathur; Jepson, Matthew J; Nagai, Ryoji; Carson, James A; Thorpe, Suzanne R; Baynes, John W

    2009-09-18

    S-(2-Succinyl)cysteine (2SC) is formed by reaction of the Krebs cycle intermediate fumarate with cysteine residues in protein, a process termed succination of protein. Both fumarate and succination of proteins are increased in adipocytes cultured in high glucose medium (Nagai, R., Brock, J. W., Blatnik, M., Baatz, J. E., Bethard, J., Walla, M. D., Thorpe, S. R., Baynes, J. W., and Frizzell, N. (2007) J. Biol. Chem. 282, 34219-34228). We show here that succination of protein is also increased in epididymal, mesenteric, and subcutaneous adipose tissue of diabetic (db/db) mice and that adiponectin is a major target for succination in both adipocytes and adipose tissue. Cys-39, which is involved in cross-linking of adiponectin monomers to form trimers, was identified as a key site of succination of adiponectin in adipocytes. 2SC was detected on two of seven monomeric forms of adiponectin immunoprecipitated from adipocytes and epididymal adipose tissue. Based on densitometry, 2SC-adiponectin accounted for approximately 7 and 8% of total intracellular adiponectin in cells and tissue, respectively. 2SC was found only in the intracellular, monomeric forms of adiponectin and was not detectable in polymeric forms of adiponectin in cell culture medium or plasma. We conclude that succination of adiponectin blocks its incorporation into trimeric and higher molecular weight, secreted forms of adiponectin. We propose that succination of proteins is a biomarker of mitochondrial stress and accumulation of Krebs cycle intermediates in adipose tissue in diabetes and that succination of adiponectin may contribute to the decrease in plasma adiponectin in diabetes.

  2. Fluctuations and structure of amphiphilic films; Fluctuations et structure de films d`amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Gourier, CH

    1996-07-01

    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.)

  3. 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

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

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Rana, Rohini R; Gotfryd, Kamil;

    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...

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

    Science.gov (United States)

    Ramanathan, Muruganathan; Shrestha, Lok Kumar; Mori, Taizo; Ji, Qingmin; Hill, Jonathan P; Ariga, Katsuhiko

    2013-07-14

    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 in nanostructure formation combine simple processes of assembly with the more advanced concept of nanoarchitectonics. In this perspective, 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 and practical applications, latter of which are often accomplished by amphiphile-like polymers. Because the fundamental science of amphiphiles was initially developed for their solution assembly then transferred to assemblies on surfaces as a development of nanotechnological techniques, this perspective attempts to mirror 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.

  6. 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

  7. 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.

  8. 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.

  9. The Behavior of Amphiphile at Oil-Water Interface by Monte Carlo Simulation

    Institute of Scientific and Technical Information of China (English)

    潘海华; 李啸风; 李浩然; 刘迪霞; 韩世钧

    2003-01-01

    A novel simple two-dimensional square-lattice model of amphiphile at oil-water interface is developed,in which oil and water act as solvent and occupy empty sites and amphiphile occupies chains of sites. In this model, the oil-water interface is fixed, And amphiphile molecules will be enriched at the oil-water interface. The interfacial concentration of amphiphile calculated by Monte Carlo method shows that it is easier for the hydrophilic-hydrophobic balanced amphiphile to stay at the interface. And the adsorption of amphiphile increases with the increase of amphiphile concentration and the decrease with temperature.

  10. 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...... acid has been derivatised with the anhydride form of phenyl succinic acid (PheSA). The fluorescence of PheSA was efficiently quenched by the HA matrix. HA also acted as a singlet oxygen scavenger. Fluorescence lifetime(s) of PheSA in solution and when attached to the HA matrix has been monitored...

  11. 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.

  12. Simulating Succinate-Promoted Dissolution at Calcite {104} Steps

    Science.gov (United States)

    Mkhonto, D.; Sahai, N.

    2008-12-01

    Organic molecules of a wide range of molecular weights from small organic acids, amino-acids, acidic peptides and acidic proteins to humic and fulvic acids play a key role in modulating nucleation, crystal growth and dissolution of calcium carbonate polymorphs. In general, these acidic molecules inhibit calcite growth and, promote dissolution preferentially along specific crystallographic directions, in the process, regulating crystal shape and size, and even whether a metastable polymorph (e.g., vaterite or aragonite) is nucleated first. For example, chiral faces of calcite are selected by chiral amino-acids and the unusual {hk0} faces are expressed in the presence of amino-acids [Orme et al., 2001], and unusual heptagonal dissolution etch-pit are seen in the presence of succinate compared to the normal rhombohedral pits in water alone [Teng et al., 2006]. Thus, the presence of unusual crystal morphologies may indicate organic-mediated growth, thus serving as a biosignature. We have conducted the Molecular Dynamics (MD) simulations using the Consistent Valence Force Field (CVFF) as implemented in the FORCITE© module of the Materials Studio © software package (Accelrys, Inc. TM) to model the adsorption of succinate, a dicarboxylic acid, and charge- balancing Na+ ions on dry and hydrated steps in different directions on the {104} cleavage face of calcite [Mkhonto and Sahai, in prep.]. At the site of succinate adsorption, we find elongation of the interatomic distances (Ca-OCO3,i) between surface Ca2+ cation and the oxygen of the underlying inorganic CO32- anion the first surface layer of calcite, compared to the corresponding distances in the presence of water alone, suggesting greater ease of surface Ca2+ detachment. This result is consistent with the empirically observed increase in overall dissolution rate with succinate [Teng et al., 2006]. Furthermore, succinate adsorption lowers the step energies, which explains the appearance of steps in the unsusual [42

  13. 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

  14. 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.

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

    DEFF Research Database (Denmark)

    De Vadder, Filipe; Kovatcheva-Datchary, Petia; Zitoun, Carine;

    2016-01-01

    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...

  16. Nucleation kinetics of urea succinic acid -ferroelectric single crystal

    Science.gov (United States)

    Dhivya, R.; Vizhi, R. Ezhil; Babu, D. Rajan

    2015-06-01

    Single crystals of Urea Succinic Acid (USA) were grown by slow cooling technique. The crystalline system was confirmed by powder X-ray diffraction. The metastable zonewidth were carried out for various temperatures i.e., 35°, 40°, 45° and 50°C. The induction period is experimentally determined and various nucleation parameters have been estimated.

  17. 21 CFR 522.1884 - Prednisolone sodium succinate injection.

    Science.gov (United States)

    2010-04-01

    ... inflammatory, allergic and less severe stress conditions, where immediate effect is not required, at 1 to 5...-1, 4-diene-3, 20-dione 21-succinate sodium salt. (b) Specifications. Each milliliter of prednisolone... other stress conditions at intervals of 12, 24, or 48 hours, depending upon the size of the animal,...

  18. Pharmacological characterization of the mechanisms underlying the vascular effects of succinate.

    Science.gov (United States)

    Leite, Letícia N; Gonzaga, Natália A; Simplicio, Janaina A; do Vale, Gabriel T; Carballido, José M; Alves-Filho, José C; Tirapelli, Carlos R

    2016-10-15

    We investigated the mechanisms underlying the vascular effects of succinate. Vascular reactivity experiments were performed in aortic rings isolated from male Wistar rats and C57BL/6 wild type (WT) or GPR91(-/-) mice. Nitrate/nitrite (NOx) was measured colorimetrically whereas 6-keto-prostaglandin F1α (stable product of prostacyclin) was measured by enzyme immunoassay (EIA). Phosphorylation of endothelial nitric oxide synthase (eNOS) was assessed by western immunoblotting. Functional assays revealed that the direct effect of succinate in the vasculature is biphasic. At lower concentrations succinate induced relaxation while at higher concentrations succinate induced vascular contraction. Succinate concentration dependently relaxed rat aortic rings with intact endothelium. Endothelial removal reduced, but not abolished succinate-induced relaxation. Similarly, succinate relaxed endothelium-intact and endothelium-denuded aortas isolated from both C57BL/6 and GPR91(-/-) mice. Pre-incubation of endothelium-intact, but not endothelium-denuded rat aortic rings with l-NAME, indomethacin and tetraethylammonium (TEA) reduced succinate-induced relaxation. In endothelium-intact rings, succinate-induced relaxation was attenuated by ODQ, haemoglobin, Rp-8-Br-Pet-cGMPS, thapsigargin, wortmannin and SC-560. Blockade of K(+) channels with 4-aminopyridine, apamin and charybdotoxin reduced succinate-induced relaxation. Succinate increased the concentration of NOx and 6-keto-prostaglandin F1α as well as eNOS phosphorylation at ser(1177) residue. CaCl2-induced contraction of endothelium-intact or endothelium-denuded aortas was not affected by succinate. The major finding of our study is that it first demonstrates a direct effect of succinate in the vasculature. Succinate displays a biphasic and concentration-dependent effect. The vascular relaxation induced by succinate is partially mediated by endothelial GPR91 receptors via the NO-cGMP pathway, a vasodilator cyclooxygenase (COX

  19. 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.

  20. 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.

  1. 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...

  2. Amphiphilic vinyl polymers effectively prolong liposome circulation time in vivo.

    Science.gov (United States)

    Torchilin, V P; Shtilman, M I; Trubetskoy, V S; Whiteman, K; Milstein, A M

    1994-10-12

    Newly synthesized amphiphilic polyacrylamide and poly(vinyl pyrrolidone), single terminus-modified with long-chain fatty acyl groups, are able to incorporate into the liposomal membrane, and similar to poly(ethylene glycol) prolong liposome circulation in vivo and decrease liposome accumulation in the liver. Protective efficacy of modified polymers increases with the increase in the length of acyl moiety and decreases for higher molecular weight polymers. The data on amphiphilic polymer-modified liposome biodistribution are presented.

  3. Elementary Mode Analysis for the Rational Design of Efficient Succinate Conversion from Glycerol by Escherichia coli

    Directory of Open Access Journals (Sweden)

    Zhen Chen

    2010-01-01

    Full Text Available By integrating the restriction of oxygen and redox sensing/regulatory system, elementary mode analysis was used to predict the metabolic potential of glycerol for succinate production by E. coli under either anaerobic or aerobic conditions. It was found that although the theoretical maximum succinate yields under both anaerobic and aerobic conditions are 1.0 mol/mol glycerol, the aerobic condition was considered to be more favorable for succinate production. Although increase of the oxygen concentration would reduce the succinate yield, the calculation suggests that controlling the molar fraction of oxygen to be under 0.65 mol/mol would be beneficial for increasing the succinate productivity. Based on the elementary mode analysis, the rational genetic modification strategies for efficient succinate production under aerobic and anaerobic conditions were obtained, respectively. Overexpressing the phosphoenolpyruvate carboxylase or heterogonous pyruvate carboxylase is considered to be the most efficient strategy to increase the succinate yield.

  4. 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)].

  5. Revealing Amphiphilic Nanodornains of Anti-Biofouling Polymer Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Amadei, CA; Yang, R; Chiesa, M; Gleason, KK; Santos, S

    2014-04-09

    Undesired bacterial adhesion and biofilm formation on wetted surfaces leads to significant economic and environmental costs in various industries. Amphiphilic coatings with molecular hydrophilic and hydrophobic patches can mitigate such biofouling effectively in an environmentally friendly manner. The coatings are synthesized by copolymerizing (Hydroxyethyl)methacrylate and perfluorodecylacrylate via initiated chemical vapor deposition (iCVD). In previous studies, the size of the patches was estimated to be similar to 1.4-1.75 nm by fitting protein adsorption data to a theoretical model. However, no direct observations of the molecular heterogeneity exist and therefore the origin of the fouling resistance of amphiphilic coatings remains unclear. Here, the amphiphilic nature is investigated by amplitude modulation atomic force microscopy (AM-AFM). High-resolution images obtained by penetrating and oscillating the AFM tip under the naturally present water layer with sub-nanometer amplitudes reveal, for the first time, the existence of amphiphilic nanodomains (1-2 nm(2)). Compositional heterogeneity at the nanoscale is further corroborated by a statistical analysis on the data obtained with dynamic AM-AFM force spectroscopy. Variations in the long range attractive forces, responsible for water affinity, are also identified. These nanoscopic results on the polymers wettability are also confirmed by contact angle measurements (i.e., static and dynamic). The unprecedented ability to visualize the amphiphilic nanodomains as well as sub-nanometer crystalline structures provides strong evidence for the existence of previously postulated nanostructures, and sheds light on the underlying antifouling mechanism of amphiphilic chemistry.

  6. 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

  7. A novel organic nonlinear optical crystal: Creatininium succinate

    Energy Technology Data Exchange (ETDEWEB)

    Thirumurugan, R.; Anitha, K., E-mail: singlecerystalxrd@gmail.ciom [School of Physics, Madurai Kamraj University, Madurai 625021 (India)

    2015-06-24

    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.

  8. 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

  9. 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

  10. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    DEFF Research Database (Denmark)

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C.;

    2016-01-01

    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 the...... 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...... 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...

  11. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Anne-Marie Ellegaard

    2016-07-01

    Full Text Available 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.

  12. 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

  13. 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

  14. Synthesis of Bioinspired Carbohydrate Amphiphiles that Promote and Inhibit Biofilms.

    Science.gov (United States)

    Dane, Eric L; Ballok, Alicia E; O'Toole, George A; Grinstaff, Mark W

    2014-02-01

    The synthesis and characterization of a new class of bioinspired carbohydrate amphiphiles that modulate Pseudomonas aeruginosa biofilm formation are reported. The carbohydrate head is an enantiopure poly-amido-saccharide (PAS) prepared by a controlled anionic polymerization of β-lactam monomers derived from either glucose or galactose. The supramolecular assemblies formed by PAS amphiphiles are investigated in solution using fluorescence assays and dynamic light scattering. Dried samples are investigated using X-ray, infrared spectroscopy, and transmission electron microscopy. Additionally, the amphiphiles are evaluated for their ability to modulate biofilm formation by the Gram-negative bacterium Pseudomonas aeruginosa. Remarkably, from a library of eight amphiphiles, we identify a structure that promotes biofilm formation and two structures that inhibit biofilm formation. Using biological assays and electron microscopy, we relate the chemical structure of the amphiphiles to the observed activity. Materials that modulate the formation of biofilms by bacteria are important both as research tools for microbiologists to study the process of biofilm formation and for their potential to provide new drug candidates for treating biofilm-associated infections.

  15. 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

  16. 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

    deletions and over-expression, mutants that overproduce succinic acid have been engineered and thoroughly characterised. Metabolic engineering approaches developed promise to have broad applicability to industrial biotechnology platforms, as well as enhancing fundamental understanding of central carbon...... products is 18, 14, 54, and 9 C-mol/C-mol-glucose, respectively, with biotechnology production is C4 organic acids, encompassing fumaric, malic, and succinic acid. Succinic acid is a key building block molecule...... of systems biology tools to drive C6 carbon flux to succinic acid by enhancement of the two native pathways for succinic acid production: the TCA and glyoxylate cycles. S. cerevisiae does not naturally accumulate succinic acid; however, through the use of in silico metabolic predictions guiding targeted gene...

  17. Adipocyte protein modification by Krebs cycle intermediates and fumarate ester-derived succination.

    Science.gov (United States)

    Manuel, Allison M; Frizzell, Norma

    2013-11-01

    Protein succination, the non-enzymatic modification of cysteine residues by fumarate, is distinguishable from succinylation, an enzymatic reaction forming an amide bond between lysine residues and succinyl-CoA. Treatment of adipocytes with 30 mM glucose significantly increases protein succination with only a small change in succinylation. Protein succination may be significantly increased intracellularly after treatment with fumaric acid esters, however, the ester must be removed by saponification to permit 2SC-antibody detection of the fumarate adduct.

  18. Recovery of succinic acid produced by fermentation of a metabolically engineered Mannheimia succiniciproducens strain.

    Science.gov (United States)

    Song, Hyohak; Huh, Yun Suk; Lee, Sang Yup; Hong, Won Hi; Hong, Yeon Ki

    2007-12-01

    There have recently been much advances in the production of succinic acid, an important four-carbon dicarboxylic acid for many industrial applications, by fermentation of several natural and engineered bacterial strains. Mannheimia succiniciproducens MBEL55E isolated from bovine rumen is able to produce succinic acid with high efficiency, but also produces acetic, formic and lactic acids just like other anaerobic succinic acid producers. We recently reported the development of an engineered M. succiniciproducens LPK7 strain which produces succinic acid as a major fermentation product while producing much reduced by-products. Having an improved succinic acid producer developed, it is equally important to develop a cost-effective downstream process for the recovery of succinic acid. In this paper, we report the development of a simpler and more efficient method for the recovery of succinic acid. For the recovery of succinic acid from the fermentation broth of LPK7 strain, a simple process composed of a single reactive extraction, vacuum distillation, and crystallization yielded highly purified succinic acid (greater than 99.5% purity, wt%) with a high yield of 67.05wt%. When the same recovery process or even multiple reactive extraction steps were applied to the fermentation broth of MBEL55E, lower purity and yield of succinic acid were obtained. These results suggest that succinic acid can be purified in a cost-effective manner by using the fermentation broth of engineered LPK7 strain, showing the importance of integrating the strain development, fermentation and downstream process for optimizing the whole processes for succinic acid production. PMID:17765349

  19. A New Class of Amphiphiles Bearing Rigid Hydrophobic Groups for Solubilization and Stabilization of Membrane Proteins

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Rasmussen, Søren G F; Rana, Rohini R;

    2012-01-01

    Non-traditional amphiphiles: Conferring aqueous solubility on membrane proteins generally requires the use of a detergent or other amphiphilic agent. A new class of amphiphiles was synthesized, based on steroidal lipophilic groups, and evaluated with several membrane proteins. The results show th...

  20. Redox-controllable amphiphilic [2]rotaxanes.

    Science.gov (United States)

    Tseng, Hsian-Rong; Vignon, Scott A; Celestre, Paul C; Perkins, Julie; Jeppesen, Jan O; Di Fabio, Alberto; Ballardini, Roberto; Gandolfi, M Teresa; Venturi, Margherita; Balzani, Vincenzo; Stoddart, J Fraser

    2004-01-01

    With the fabrication of molecular electronic devices (MEDs) and the construction of nanoelectromechanical systems (NEMSs) as incentives, two constitutionally isomeric, redox-controllable [2]rotaxanes have been synthesized and characterized in solution. Therein, they both behave as near-perfect molecular switches, that is, to all intents and purposes, these two rotaxanes can be switched precisely by applying appropriate redox stimuli between two distinct chemomechanical states. Their dumbbell-shaped components are composed of polyether chains interrupted along their lengths by i) two pi-electron rich recognition sites-a tetrathiafulvalene (TTF) unit and a 1,5-dioxynaphthalene (DNP) moiety-with ii) a rigid terphenylene spacer placed between the two recognition sites, and then terminated by iii) a hydrophobic tetraarylmethane stopper at one end and a hydrophilic dendritic stopper at the other end of the dumbbells, thus conferring amphiphilicity upon these molecules. A template-directed protocol produces a means to introduce the tetracationic cyclophane, cyclobis(paraquat-p-phenylene) (CBPQT(4+)), which contains two pi-electron accepting bipyridinium units, mechanically interlocked around the dumbbell-shaped components. Both the TTF unit and the DNP moiety are potential stations for CBPQT(4+), since they can establish charge-transfer and hydrogen bonding interactions with the bipyridinium units of the cyclophane, thereby introducing bistability into the [2]rotaxanes. In both constitutional isomers, (1)H NMR and absorption spectroscopies, together with electrochemical investigations, reveal that the CBPQT(4+) ring is predominantly located on the TTF unit, leading to the existence of a single translational isomer (co-conformation) in both cases. In addition, a model [2]rotaxane, incorporating hydrophobic tetraarylmethane stoppers at both ends of its dumbbell-shaped component, has also been synthesized as a point of reference. Molecular synthetic approaches were used to

  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. Competitive Binding of Natural Amphiphiles with Graphene Derivatives

    Science.gov (United States)

    Radic, Slaven; Geitner, Nicholas K.; Podila, Ramakrishna; Käkinen, Aleksandr; Chen, Pengyu; Ke, Pu Chun; Ding, Feng

    2013-07-01

    Understanding the transformation of graphene derivatives by natural amphiphiles is essential for elucidating the biological and environmental implications of this emerging class of engineered nanomaterials. Using rapid discrete-molecular-dynamics simulations, we examined the binding of graphene and graphene oxide with peptides, fatty acids, and cellulose, and complemented our simulations by experimental studies of Raman spectroscopy, FTIR, and UV-Vis spectrophotometry. Specifically, we established a connection between the differential binding and the conformational flexibility, molecular geometry, and hydrocarbon content of the amphiphiles. Importantly, our dynamics simulations revealed a Vroman-like competitive binding of the amphiphiles for the graphene oxide substrate. This study provides a mechanistic basis for addressing the transformation, evolution, transport, biocompatibility, and toxicity of graphene derivatives in living systems and the natural environment.

  3. 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)

  4. 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

    in the highest overall sugar yield (73.5%), maximum succinic acid titer (21.9gL-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.......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...

  5. 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

  6. 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

  7. 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

  8. 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

  9. Bio-based amphiphilic materials development and applications

    Science.gov (United States)

    Farm-based raw materials are increasingly used in the development of amphiphilic materials that have potential applications in the production of a variety of consumer and industrial products, including lubricants. Raw materials of interest include: starches, proteins, fats, oils, and sugars. These ...

  10. Amphiphiles containing aromatic groups in the hydrophobic part

    NARCIS (Netherlands)

    Visscher, Inge

    2004-01-01

    Aggregation processes are essential for life on this planet. For example, the membranes of all living cells are bilayered aggregates, consisting of lipid molecules, proteins and steroids. In many biological processes, aggregates play a role. The main driving force for aggregation of amphiphiles is h

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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...

  16. 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...

  17. 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.

  18. atp mutants of Escherichia coli fail to grow on succinate due to a transport deficiency

    DEFF Research Database (Denmark)

    Boogerd, Fred; Boe, Lars; Michelsen, Ole;

    1998-01-01

    Escherichia coli atp mutants, which lack a functional Hf-ATPase complex, are capable of growth on glucose but not on succinate or other C-4-dicarboxylates (Suc(-) phenotype). Suc(+) revertants of an atp deletion strain were isolated which were capable of growth on succinate even though they lack ...

  19. Krebs cycle metabolite profiling for identification and stratification of pheochromocytomas/paragangliomas due to succinate dehydrogenase deficiency

    NARCIS (Netherlands)

    Richter, S; Peitzsch, M.; Rapizzi, E.; Lenders, J.W.M.; Qin, N.; Cubas, A.A. de; Schiavi, F.; Rao, J.U.; Beuschlein, F.; Quinkler, M.; Timmers, H.J.L.M.; Opocher, G.; Mannelli, M.; Pacak, K.; Robledo, M.; Eisenhofer, G.

    2014-01-01

    CONTEXT: Mutations of succinate dehydrogenase A/B/C/D genes (SDHx) increase susceptibility to development of pheochromocytomas and paragangliomas (PPGLs), with particularly high rates of malignancy associated with SDHB mutations. OBJECTIVE: We assessed whether altered succinate dehydrogenase product

  20. Evaporation of methyl- and dimethyl-substituted malonic, succinic, glutaric and adipic acid particles at ambient temperatures

    DEFF Research Database (Denmark)

    Mønster, Jacob Garbrecht; Rosenørn, Thomas; Svenningsson, Birgitta;

    2004-01-01

    Evaporation; organic aerosols; vapor pressure; dicarboxylic acid; maonic acid; succinic acid; glutaric acid; adipic acid......Evaporation; organic aerosols; vapor pressure; dicarboxylic acid; maonic acid; succinic acid; glutaric acid; adipic acid...

  1. 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

  2. Self-assembly of fibronectin mimetic peptide-amphiphile nanofibers

    Science.gov (United States)

    Rexeisen, Emilie Lynn

    Many therapeutic strategies incorporate peptides into their designs to mimic the natural protein ligands found in vivo. A few examples are the short peptide sequences RGD and PHSRN that mimic the primary and synergy-binding domains of the extracellular matrix protein, fibronectin, which is recognized by the cell surface receptor, alpha5beta 1 integrin. Even though scaffold modification with biomimetic peptides remains one of the most promising approaches for tissue engineering, the use of these peptides in therapeutic tissue-engineered products and drug delivery systems available on the commercial market is limited because the peptides are not easily able to mimic the natural protein. The design of a peptide that can effectively target the alpha5beta1 integrin would greatly increase biomimetic scaffold therapeutic potential. A novel peptide containing both the RGD primary binding domain and PHSRN synergy-binding domain for fibronectin joined with the appropriate linker should bind alpha 5beta1 integrin more efficiently and lead to greater cell adhesion over RGD alone. Several fibronectin mimetic peptides were designed and coupled to dialkyl hydrocarbon tails to make peptide-amphiphiles. The peptides contained different linkers connecting the two binding domains and different spacers separating the hydrophobic tails from the hydrophilic headgroups. The peptide-amphiphiles were deposited on mica substrates using the Langmuir-Blodgett technique. Langmuir isotherms indicated that the peptide-amphiphiles that contained higher numbers of serine residues formed a more tightly packed monolayer, but the increased number of serines also made transferring the amphiphiles to the mica substrate more difficult. Atomic force microscopy (AFM) images of the bilayers showed that the headgroups might be bent, forming small divots in the surface. These divots may help expose the PHSRN synergy-binding domain. Parallel studies undertaken by fellow group members showed that human

  3. 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.

  4. Succination of proteins by fumarate: mechanism of inactivation of glyceraldehyde-3-phosphate dehydrogenase in diabetes.

    Science.gov (United States)

    Blatnik, Matthew; Thorpe, Suzanne R; Baynes, John W

    2008-04-01

    S-(2-succinyl)cysteine (2SC) is a chemical modification of proteins formed by a Michael addition reaction between the Krebs cycle intermediate, fumarate, and thiol groups in protein--a process known as succination of protein. Succination causes irreversible inactivation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in vitro. GAPDH was immunoprecipitated from muscle of diabetic rats, then analyzed by ultra-performance liquid chromatography-electrospray ionization-mass spectroscopy. Succination of GAPDH was increased in muscle of diabetic rats, and the extent of succination correlated strongly with the decrease in specific activity of the enzyme. We propose that 2SC is a biomarker of mitochondrial and oxidative stress in diabetes and that succination of GAPDH and other thiol proteins may provide the chemical link between glucotoxicity and the pathogenesis of diabetic complications.

  5. Succinic acid production from corn stover by simultaneous saccharification and fermentation using Actinobacillus succinogenes.

    Science.gov (United States)

    Zheng, Pu; Fang, Lin; Xu, Yan; Dong, Jin-Jun; Ni, Ye; Sun, Zhi-Hao

    2010-10-01

    Simultaneous saccharification and fermentation (SSF) technique was applied for succinic acid production by Actinobacillus succinogenes in a 5-l stirred bioreactor with corn stover as the raw material. The process parameters of SSF, including corn stover pretreatment condition, substrate concentration, enzyme loading and fermentation temperature were investigated. Results indicated that pretreating corn stover with diluted alkaline was beneficial for the succinic acid production, and succinic acid yield could be significantly increased when adding the cellulase supplemented with cellobiase. The maximal succinic acid concentration and yield could reach 47.4 g/l and 0.72 g/g-substrate, respectively. The corresponding operation conditions were summarized as follows: SSF operation at 38 °C for 48 h, diluted alkaline pretreated corn stover as substrate with concentration of 70 g/l, enzyme loading of 20FPU cellulase and 10 U cellobiase per gram substrate. This result suggested an industrial potential of succinic acid production by using SSF and corn stover.

  6. 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

  7. 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.

  8. 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.

  9. Periodically Grafted Amphiphilic Copolymers: Effects of Steric Crowding and Reversal of Amphiphilicity.

    Science.gov (United States)

    Mandal, Joydeb; Ramakrishnan, S

    2015-06-01

    Two series of periodically clickable polyesters were prepared; one of them carries alkylene segments along its backbone, whereas the other carries poly(ethylene glycol) (PEG) segments. These polyesters were clicked with either MPEG-350 azide or docosyl (C22) azide to yield periodically grafted amphiphilic copolymers (PGACs) carrying either flexible hydrophilic or crystallizable hydrophobic backbone segments. The immiscibility between hydrocarbon and PEG segments causes both of these systems to fold in either a zigzag or hairpin-like conformation; the hairpin-like conformation appears to be preferred when flexible PEG segments are present in the backbone. The folded chains further reorganize in the solid state to develop a lamellar morphology that permits the collocation of the PEG and hydrocarbon (HC) segments within alternate domains; evidence for the self-segregation was gained from DSC, SAXS, and AFM studies. SAXS studies revealed the formation of an extended lamellar structure, whereas AFM images showed uniform layered morphology with layer heights that matched reasonably well with the interlamellar spacing obtained from the SAXS study. Labeling one representative PGAC, carrying crystallizable long alkylene segments in the backbone and pendant PEG-350 side chains, with a small mole fraction of pyrene fluorophore permitted the examination of the conformational transition that occurs upon going from a good to a poor solvent; this single-chain folded conformation, we postulate, is the intermediate that organizes into the lamellar morphology.

  10. 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

  11. 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.

  12. 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.

  13. Mitochondrial stress causes increased succination of proteins in adipocytes in response to glucotoxicity.

    Science.gov (United States)

    Frizzell, Norma; Thomas, Sonia A; Carson, James A; Baynes, John W

    2012-07-15

    2SC [S-(2-succino)-cysteine] is a chemical modification formed by a Michael addition reaction of fumarate with cysteine residues in proteins. Formation of 2SC, termed 'succination' of proteins, increases in adipocytes grown in high-glucose medium and in adipose tissues of Type 2 diabetic mice. However, the metabolic mechanisms leading to increased fumarate and succination of protein in the adipocyte are unknown. Treatment of 3T3 cells with high glucose (30 mM compared with 5 mM) caused a significant increase in cellular ATP/ADP, NADH/NAD+ and Δψm (mitochondrial membrane potential). There was also a significant increase in the cellular fumarate concentration and succination of proteins, which may be attributed to the increase in NADH/NAD+ and subsequent inhibition of tricarboxylic acid cycle NAD+-dependent dehydrogenases. Chemical uncouplers, which dissipated Δψm and reduced the NADH/NAD+ ratio, also decreased the fumarate concentration and protein succination. High glucose plus metformin, an inhibitor of complex I in the electron transport chain, caused an increase in fumarate and succination of protein. Thus excess fuel supply (glucotoxicity) appears to create a pseudohypoxic environment (high NADH/NAD+ without hypoxia), which drives the increase in succination of protein. We propose that increased succination of proteins is an early marker of glucotoxicity and mitochondrial stress in adipose tissue in diabetes.

  14. 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

  15. 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

  16. 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.

  17. [Effects of furfural and 5-hydroxymethylfurfural on succinic acid production by Escherichia coli].

    Science.gov (United States)

    Wang, Dan; Wang, Honghui; Wang, Jing; Wang, Nan; Zhang, Jie; Xing, Jianmin

    2013-10-01

    Succinic acid production by fermentation from biomass, especially the lignocellulosic hydrolysate, is an alternative to chemical synthesis. Many studies report the inhibition of cell growth and succinic acid production from lignocellulosic hydrolysate, hardly is known about the actual kinetic and mechanism of the inhibition of individual factors. In this study, we studied inhibition effects of furfurals and 5-hydroxymethylfurfural (5-HMF) on cell growth and succinic acid production of engineered E. coli. Cell growth and succinic acid titer were severely inhibited by furfural and HMF with both concentrations higher than 0.8 g/L. Cell growth was totally inhibited when the concentration of furfural was above 6.4 g/L, or the concentration of HMF was above 12.8 g/L. At the concentration of maximum toleration, which was 3.2 g/L, furfural decreased the cell mass by 77.8% and the succinic acid titer by 36.1%. HMF decreased the cell mass by 13.6% and the succinic acid titer by 18.3%. Activity measurements of key enzymes revealed that phosphoenolpyruvate carboxylase, malate dehydrogenase, fumarate reductase all were inhibited by furfural and HMF. This study gave a quantitative view to the succinic acid production under the inhibition of lignocellulose degradation products and will help overcome the difficulties of the lignocellulosic hydrolysate fermentation.

  18. 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

  19. 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

  20. 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.

  1. Succinic acid production by Actinobacillus succinogenes from batch fermentation of mixed sugars.

    Science.gov (United States)

    Almqvist, Henrik; Pateraki, Chrysanthi; Alexandri, Maria; Koutinas, Apostolis; Lidén, Gunnar

    2016-08-01

    Succinic acid production from the monosaccharides xylose, arabinose, glucose, mannose and galactose was studied using the bacterium Actinobacillus succinogenes. In Duran bottle cultures, containing 10 g/L of each of sugar, succinic acid was produced from all sugars except for galactose. The highest succinate yield, 0.56 g/g, was obtained with glucose, whereas the succinate yield was 0.42, 0.38 and 0.44 g/g for xylose, mannose and arabinose, respectively. The specific succinate productivity was 0.7 g/g h for glucose, but below 0.2 g/g h for the other sugars. Batch bioreactor fermentations were carried out using a sugar mixture of the five sugars giving a total concentration of 50 g/L, mimicking the distribution of sugars in spent sulfite liquor (SSL) from Eucalyptus which is rich in xylose. In this mixture, an almost complete conversion of all sugars (except galactose) was achieved resulting in a final succinate concentration of 21.8-26.8 g/L and a total yield of 0.59-0.68 g/g. There was evidence of co-consumption of glucose and xylose, whereas mannose was consumed after glucose. The main by-products were acetate 0.14-0.20 g/g and formate 0.08-0.13 g/g. NADH balance calculations suggested that NADH required for succinate production was not met solely from formate and acetate production, but other means of NADH production was necessary. Results from mixed sugar fermentations were verified using SSL as substrate resulting in a succinate yield of 0.60 g/g. In addition, it was found that CO2 sparging could replace carbonate supply in the form of MgCO3 without affecting the succinate yield. PMID:27255975

  2. 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

  3. 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

  4. 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.

  5. 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...... 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 149 kg of EtOH and 115 kg of succinic acid can be obtained per 1 ton of dry hemp...

  6. 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

  7. 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.

  8. 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...

  9. 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...

  10. 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

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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

  16. High-Capacity Drug Carriers from Common Polymer Amphiphiles.

    Science.gov (United States)

    Zhou, Zhun; Munyaradzi, Oliver; Xia, Xin; Green, Da'Sean; Bong, Dennis

    2016-09-12

    We report herein a dual-purpose role for polyacidic domains in an aqueous-phase polymer amphiphile assembly. In addition to their typical role as ionized water-solubilizing and self-repulsive motifs, we find that polycarboxylic acid domains uniquely enable high levels of hydrophobic drug encapsulation. By attenuated total reflectance infrared spectroscopy, we find significant differences in the carbonyl stretching region of the nanoparticles formed by polyacidic amphiphiles relative to those in soluble, single-domain poly(acrylic acid), suggesting that stabilization may be derived from limited ionization of the carboxylate groups upon assembly. Acidic-hydrophobic diblock polyacrylates were prepared and coassembled with up to 60 wt % camptothecin (CPT) into nanoparticles, the highest loading reported to date. Controlled release of bioactive CPT from polymer nanoparticles is observed, as well as protection from human serum albumin-induced hydrolysis. Surface protection with PEG limits uptake of the CPT-loaded nanoparticles by MCF-7 breast cancer cells, as expected. Acidic-hydrophobic polymer amphiphiles thus have the hallmarks of a useful and general drug delivery platform and are readily accessible from living radical polymerization of cheap, commercially available monomers. We highlight here the potential utility of this common polymer design in high-capacity, controlled-release polymer nanoparticle systems. PMID:27476544

  17. Cationic amphiphiles with fatty acyl chain asymmetry of coconut oil deliver genes selectively to mouse lung.

    Science.gov (United States)

    Chandrashekhar, Voshavar; Srujan, Marepally; Prabhakar, Rairala; Reddy, Rakesh C; Sreedhar, Bojja; Rentam, Kiran K R; Kanjilal, Sanjit; Chaudhuri, Arabinda

    2011-03-16

    Recent structure-activity studies have revealed a dramatic influence of hydrophobic chain asymmetry in enhancing gene delivery efficacies of synthetic cationic amphiphiles (Nantz, M. H. et al. Mol. Pharmaceutics2010, 7, 786-794; Koynova, R. et al. Mol. Pharmaceutics2009, 6, 951-958). The present findings demonstrate for the first time that such a transfection enhancing influence of asymmetric hydrocarbon chains observed in pure synthetic cationic amphiphiles also works for cationic amphiphiles designed with natural, asymmetric fatty acyl chains of a food-grade oil. Herein, we demonstrate that cationic amphiphiles designed with the natural fatty acyl chain asymmetry of food-grade coconut oil are less cytotoxic and deliver genes selectively to mouse lung. Despite lauroyl chains being the major fatty acyl chains of coconut oil, both the in vitro and In vivo gene transfer efficiencies of such cationic amphiphiles were found to be remarkably superior (>4-fold) to those of their pure dilauroyl analogue. Mechanistic studies involving the technique of fluorescence resonance energy transfer (FRET) revealed higher biomembrane fusibility of the cationic liposomes of the coconut amphiphiles than that of the symmetric dilauroyl analogue. AFM study revealed pronounced fusogenic nonlamellar structures of the liposomes of coconut amphiphiles. Findings in the FRET and cellular uptake study, taken together, support the notion that the higher cellular uptake resulting from the more fusogenic nature of the liposomes of coconut amphiphiles 1 are likely to play a dominant role in making the coconut amphiphiles transfection competent.

  18. 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.

  19. Amphiphiles Self-Assembly: Basic Concepts and Future Perspectives of Supramolecular Approaches

    Directory of Open Access Journals (Sweden)

    Domenico Lombardo

    2015-01-01

    Full Text Available Amphiphiles are synthetic or natural molecules with the ability to self-assemble into a wide variety of structures including micelles, vesicles, nanotubes, nanofibers, and lamellae. Self-assembly processes of amphiphiles have been widely used to mimic biological systems, such as assembly of lipids and proteins, while their integrated actions allow the performance of highly specific cellular functions which has paved a way for bottom-up bionanotechnology. While amphiphiles self-assembly has attracted considerable attention for decades due to their extensive applications in material science, drug and gene delivery, recent developments in nanoscience stimulated the combination of the simple approaches of amphiphile assembly with the advanced concept of supramolecular self-assembly for the development of more complex, hierarchical nanostructures. Introduction of stimulus responsive supramolecular amphiphile assembly-disassembly processes provides particularly novel approaches for impacting bionanotechnology applications. Leading examples of these novel self-assembly processes can be found, in fact, in biosystems where assemblies of different amphiphilic macrocomponents and their integrated actions allow the performance of highly specific biological functions. In this perspective, we summarize in this tutorial review the basic concept and recent research on self-assembly of traditional amphiphilic molecules (such as surfactants, amphiphile-like polymers, or lipids and more recent concepts of supramolecular amphiphiles assembly which have become increasingly important in emerging nanotechnology.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    was investigated. Results: The transgenic E. coli strain could grow in modified M9 medium containing 20 v/v% AP-bio-oil with an increase in OD from 0.25 to 1.09. And 0.38 g/L succinic acid was produced. With the presence of 4 g/L glucose in the medium, succinic acid concentration increased from 1.4 to 2.4 g....../L by addition of 20 v/v% AP-bio-oil. When enzymatic hydrolysate of corn stover was used as carbon source, 10.3 g/L succinic acid was produced. The obtained succinic acid concentration increased to 11.5 g/L when 12.5 v/v% AP-bio-oil was added. However, it decreased to 8 g/L when 50 v/v% AP-bio-oil was added. GC...

  1. 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.

  2. 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

  3. 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...

  4. 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,...

  5. 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.

  6. Dehydration-induced redistribution of amphiphilic molecules between cytoplasm and lipids is associated with desiccation tolerance in seeds

    NARCIS (Netherlands)

    Buitink, J.; Leprince, O.; Hoekstra, F.A.

    2000-01-01

    This study establishes a relationship between desiccation tolerance and the transfer of amphiphilic molecules from the cytoplasm into lipids during drying, using electron paramagnetic resonance spectroscopy of amphiphilic spin probes introduced into imbibed radicles of pea (Pisum sativum) and cucumb

  7. Is it possible to produce succinic acid at a low pH?

    Science.gov (United States)

    Yuzbashev, Tigran V; Yuzbasheva, Evgeniya Y; Laptev, Ivan A; Sobolevskaya, Tatiana I; Vybornaya, Tatiana V; Larina, Anna S; Gvilava, Ilia T; Antonova, Svetlana V; Sineoky, Sergey P

    2011-01-01

    Bio-based succinate is still a matter of special emphasis in biotechnology and adjacent research areas. The vast majority of natural and engineered producers are bacterial strains that accumulate succinate under anaerobic conditions. Recently, we succeeded in obtaining an aerobic yeast strain capable of producing succinic acid at low pH. Herein, we discuss some difficulties and advantages of microbial pathways producing "succinic acid" rather than "succinate." It was concluded that the peculiar properties of the constructed yeast strain could be clarified in view of a distorted energy balance. There is evidence that in an acidic environment, the majority of the cellular energy available as ATP will be spent for proton and anion efflux. The decreased ATP:ADP ratio could essentially reduce the growth rate or even completely inhibit growth. In the same way, the preference of this elaborated strain for certain carbon sources could be explained in terms of energy balance. Nevertheless, the opportunity to exclude alkali and mineral acid waste from microbial succinate production seems environmentally friendly and cost-effective.

  8. [Succinic acid production from sucrose and sugarcane molasses by metabolically engineered Escherichia coli].

    Science.gov (United States)

    Li, Feng; Ma, Jiangfeng; Wu, Mingke; Ji, Yaliang; Chen, Wufang; Ren, Xinyi; Jiang, Min

    2015-04-01

    Sugarcane molasses containing large amounts of sucrose is an economical substrate for succinic acid production. However, Escherichia coli AFP111 cannot metabolize sucrose although it is a promising candidate for succinic acid production. To achieve sucrose utilizing ability, we cloned and expressed cscBKA genes encoding sucrose permease, fructokinase and invertase of non-PTS sucrose-utilization system from E. coli W in E. coli AFP111 to generate a recombinant strain AFP111/pMD19T-cscBKA. After 72 h of anaerobic fermentation of the recombinant in serum bottles, 20 g/L sucrose was consumed and 12 g/L succinic acid was produced. During dual-phase fermentation comprised of initial aerobic growth phase followed by anaerobic fermentation phase, the concentration of succinic acid from sucrose and sugarcane molasses was 34 g/L and 30 g/L, respectively, at 30 h of anaerobic phase in a 3 L fermentor. The results show that the introduction of non-PTS sucrose-utilization system has sucrose-metabolizing capability for cell growth and succinic acid production, and can use cheap sugarcane molasses to produce succinic acid.

  9. 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.

  10. Improving succinic acid production by Actinobacillus succinogenes from raw industrial carob pods.

    Science.gov (United States)

    Carvalho, Margarida; Roca, Christophe; Reis, Maria A M

    2016-10-01

    Carob pods are an inexpensive by-product of locust bean gum industry that can be used as renewable feedstock for bio-based succinic acid. Here, for the first time, unprocessed raw carob pods were used to extract a highly enriched sugar solution, afterwards used as substrate to produce succinic acid using Actinobacillus succinogenes. Batch fermentations containing 30g/L sugars resulted in a production rate of 1.67gSA/L.h and a yield of 0.39gSA/g sugars. Taking advantage of A. succinogenes' metabolism, uncoupling cell growth from succinic acid production, a fed-batch mode was implemented to increase succinic acid yield and reduce by-products formation. This strategy resulted in a succinic acid yield of 0.94gSA/g sugars, the highest yield reported in the literature for fed-batch and continuous experiments, while maintaining by-products at residual values. Results demonstrate that raw carob pods are a highly efficient feedstock for bio-based succinic acid production. PMID:27394995

  11. Succinic acid production from corn cob hydrolysates by genetically engineered Corynebacterium glutamicum.

    Science.gov (United States)

    Wang, Chen; Zhang, Hengli; Cai, Heng; Zhou, Zhihui; Chen, Yilu; Chen, Yali; Ouyang, Pingkai

    2014-01-01

    Corynebacterium glutamicum wild type lacks the ability to utilize the xylose fractions of lignocellulosic hydrolysates. In the present work, we constructed a xylose metabolic pathway in C. glutamicum by heterologous expression of the xylA and xylB genes coming from Escherichia coli. Dilute-acid hydrolysates of corn cobs containing xylose and glucose were used as a substrate for succinic acid production by recombinant C. glutamicum NC-2. The results indicated that the available activated charcoal pretreatment in dilute-acid hydrolysates of corn cobs could be able to overcome the inhibitory effect in succinic acid production. Succinic acid was shown to be efficiently produced from corn cob hydrolysates (55 g l(-1) xylose and 4 g l(-1) glucose) under oxygen deprivation with addition of sodium carbonate. Succinic acid concentration reached 40.8 g l(-1) with a yield of 0.69 g g(-1) total sugars within 48 h. It was the first report of succinic acid production from corn cob hydrolysates by metabolically engineered C. glutamicum. This study suggested that dilute-acid hydrolysates of corn cobs may be an alternative substrate for the efficient production of succinic acid by C. glutamicum. PMID:24078255

  12. Biological denitrification using poly(butanediol succinate) as electron donor.

    Science.gov (United States)

    Shen, Zhiqiang; Yin, Yanan; Wang, Jianlong

    2016-07-01

    Poly(butanediol succinate) (PBS), a biodegradable polymer, was used as both solid carbon source and biofilm carrier for biological nitrate removal process, in which PBS was filled in a packed-bed bioreactor. The denitrification performance and the microbial diversity of biofilm attached on the surface of PBS were investigated. The experimental results showed that the volumetric denitrification rate was 0.60 kg m(-3) day(-1) when NO3-N loading rate was 0.63 kg m(-3) day(-1), and the average NO2-N concentration was below 0.20 mg L(-1). The effluent pH value decreased slightly from a range of 6.98-7.87 to 6.46-7.18. The analysis of microbial community structure of biofilm by pyrosequencing method showed that Proteobacteria was the most abundant phylum (89.87 %), and β-Proteobacteria represented the most abundant class. Among the 76 identified genera, Dechloromonas (10.26 %), Alicycliphilus (9.15 %), Azospira (8.92 %), and Sinobacteraceae-uncultured (8.75 %) were the abundant genera. PBS, as a promising alternative carbon source, is a suitable solid carbon source and biofilm carrier for nitrate removal. PMID:26960320

  13. 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

  14. Composition and method for self-assembly and mineralization of peptide-amphiphiles

    Science.gov (United States)

    Stupp, Samuel I.; Beniash, Elia; Hartgerink, Jeffrey D.

    2012-02-28

    The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

  15. Composition and method for self-assembly and mineralization of peptide amphiphiles

    Science.gov (United States)

    Stupp, Samuel I.; Beniash, Elia; Hartgerink, Jeffrey D.

    2009-06-30

    The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

  16. 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

    The self-assembly of cationic and anionic amphiphile mixtures into vesicles in aqueous media was studied using two different systems: i) decanoic acid and trimethyldecylammonium bromide ii) hexadecanedioic acid (a simple bola-amphiphile) and trimethyldecylammonium bromide. The resulting vesicles ...

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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...

  2. Synthesis of Amphiphilic Block Copolymers for Use in Biomedical Applications

    OpenAIRE

    Carmichael-Baranauskas, Anita Yvonne

    2010-01-01

    The research presented in this thesis focuses on the synthesis of three amphiphilic block copolymer systems containing poly(ethylene oxide) (PEO) blocks. The polymer systems were developed for use in biomedical applications. The first of these is a series of poly(ethylene oxide-b¬-oxazoline) (PEO-b-POX) diblock copolymers for use in the progress towards novel non-viral gene transfer vectors. Poly(ethylene oxide-b¬-2-ethyl-2-oxazoline) (PEO-b-PEOX) and poly(ethylene oxide-b¬-2-methyl-2-o...

  3. 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...

  4. 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...

  5. 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

  6. 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

  7. Amphiphilic biopolymers (amphibiopols) as new surfactants for membrane protein solubilization

    Science.gov (United States)

    Duval-Terrié, Caroline; Cosette, Pascal; Molle, Gérard; Muller, Guy; Dé, Emmanuelle

    2003-01-01

    The aim of this study was to develop new surfactants for membrane protein solubilization, from a natural, biodegradable polymer: the polysaccharide pullulan. A set of amphiphilic pullulans (HMCMPs), differing in hydrophobic modification ratio, charge ratio, and the nature of the hydrophobic chains introduced, were synthesized and tested in solubilization experiments with outer membranes of Pseudomonas fluorescens. The membrane proteins were precipitated, and then resolubilized with various HMCMPs. The decyl alkyl chain (C10) was the hydrophobic graft that gave the highest level of solubilization. Decyl alkyl chain-bearing HMCMPs were also able to extract integral membrane proteins from their lipid environment. The best results were obtained with an amphiphilic pullulan bearing 18% decyl groups (18C10). Circular dichroism spectroscopy and membrane reconstitution experiments were used to test the structural and functional integrity of 18C10-solubilized proteins (OmpF from Escherichia coli and bacteriorhodopsin from Halobacterium halobium). Whatever their structure type (α or β), 18C10 did not alter either the structure or the function of the proteins analyzed. Thus, HMCMPs appear to constitute a promising new class of polymeric surfactants for membrane protein studies. PMID:12649425

  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. DEFORMATION OF COPOLYMER MICELLES INDUCED BY AMPHIPHILIC DIMER PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Xiao-chun Qin; Chun-lai Ren

    2012-01-01

    Combining self-consistent-field theory and density-functional theory,we systematically study the deformation of copolymer micelles induced by the presence of amphiphilic dimer particles.Due to the amphiphilic nature,dimer particles tend to accumulate onto the interface of the copolymer micelle.With increasing concentration of the symmetric dimer particles,which are made of two identical spherical particles,the micelle deforms from the initial sphere to ellipse,dumbbell,and finally separates into two micelles.Furthermore,asymmetric dimer particles,composed by two particles with different sizes,are considered to investigate the influence of geometry of dimer particles on the deformation of the micelle.It is found that the micelle inclines to deform into dumbbell due to the additional curvature originating in the gathering of asymmetric dimer particles onto the interface of the micelle.The present study on the deformation of micelles is useful to understand the possible shape variation in the course of cell division/fusion.

  10. 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

  11. 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.

  12. The Behavior of Amphiphile at Oil-Water Interface by Monte Carlo Simulation%双亲分子在油水界面的行为研究

    Institute of Scientific and Technical Information of China (English)

    潘海华; 李啸风; 李浩然; 刘迪霞; 韩世钧

    2003-01-01

    A novel simple two-dimensional square-lattice model of amphiphile at oil-water interface is developed,in which oil and water act as solvent and occupy empty sites and amphiphile occupies chains of sites. In thismodel, the oil-water interface is fixed, And amphiphile molecules will be enriched at the oil-water interface. Theinterfacial concentration of amphiphile calculated by Monte Carlo method shows that it is easier for the hydrophilic-hydrophobic balanced amphiphile to stay at the interface. And the adsorption of amphiphile increases with theincrease of amphiphile concentration and the decrease with temperature.

  13. 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

  14. 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.

  15. 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.

  16. Ionic liquid pretreatment to increase succinic acid production from lignocellulosic biomass.

    Science.gov (United States)

    Wang, Caixia; Yan, Daojiang; Li, Qiang; Sun, Wei; Xing, Jianmin

    2014-11-01

    In this study, pinewood and corn stover pretreated with the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride (AmimCl) were used as a feedstock for succinic acid production. Results reveal that 5% (v/v) AmimCl inhibited bacterial growth, whereas 0.01% (v/v) AmimCl inhibited succinic acid production. AmimCl was effective in extracting cellulose from pinewood and in degrading pinewood into a uniform pulp, as revealed by scanning electron microscopy (SEM). The rate of enzymatic hydrolysis of pinewood extract reached 72.16%. The combinations of AmimCl pretreatment with steam explosion or with hot compressed water were effective in treating corn stover, whereas AmimCl treatment alone did not result in a significant improvement. Pinewood extract produced 20.7g/L succinic acid with an average yield of 0.37g per gram of biomass. Workflow calculations indicated pine wood pretreated with IL has a theoretical yield of succinic acid of 57.1%. IL pretreatment led to increase in succinic acid yields.

  17. 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

  18. 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.

  19. 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.

  20. Self-assembly of phosphate amphiphiles in mixtures of prebiotically plausible surfactants.

    Science.gov (United States)

    Albertsen, A N; Duffy, C D; Sutherland, J D; Monnard, P-A

    2014-06-01

    The spontaneous formation of closed bilayer structures from prebiotically plausible amphiphiles is an essential requirement for the emergence of early cells on prebiotic Earth. The sources of amphiphiles could have been both endo- and exogenous (accretion of meteorite carbonaceous material or interstellar dust particles). Among all prebiotic possible amphiphile candidates, those containing phosphate are the least investigated species because their self-assembly occurs in a seemingly too narrow range of conditions. The self-assembly of simple phosphate amphiphiles should, however, be of great interest, as contemporary membranes predominantly contain phospholipids. In contrast to common expectations, we show that these amphiphiles can be easily synthesized under prebiotically plausible environmental conditions and can efficiently form bilayer structures in the presence of various co-surfactants across a large range of pH values. Vesiculation was even observed in crude reaction mixtures that contained 1-decanol as the amphiphile precursor. The two best co-surfactants promoted vesicle formation over the entire pH range in aqueous solutions. Expanding the pH range where bilayer membranes self-assemble and remain intact is a prerequisite for the emergence of early cell-like compartments and their preservation under fluctuating environmental conditions. These mixed bilayers also retained small charged solutes, such as dyes. These results demonstrate that alkyl phosphate amphiphiles might have played a significant role as early compartment building blocks.

  1. 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.

  2. 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...... 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...

  3. Crystallization and immersion freezing ability of oxalic and succinic acid in multicomponent aqueous organic aerosol particles

    Science.gov (United States)

    Wagner, Robert; Höhler, Kristina; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin

    2015-04-01

    This study reports on heterogeneous ice nucleation efficiency of immersed oxalic and succinic acid crystals in the temperature range from 245 to 215 K, as investigated with expansion cooling experiments using suspended particles. In contrast to previous laboratory work with emulsified solution droplets where the precipitation of solid inclusions required a preceding freezing/evaporation cycle, we show that immersed solids readily form by homogeneous crystallization within aqueous solution droplets of multicomponent organic mixtures, which have noneutonic compositions with an excess of oxalic or succinic acid. Whereas succinic acid crystals did not act as heterogeneous ice nuclei, immersion freezing by oxalic acid dihydrate crystals led to a reduction of the ice saturation ratio at freezing onset by 0.066-0.072 compared to homogeneous freezing, which is by a factor of 2 higher than previously reported laboratory data. These observations emphasize the importance of oxalic acid in heterogeneous ice nucleation.

  4. 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.

  5. 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.

  6. 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.

  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. 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 ...

  9. 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

  10. Maintenance of homeostasis in the aging hypothalamus: The central and peripheral roles of succinate

    Directory of Open Access Journals (Sweden)

    Thomas T. Chen

    2015-02-01

    Full Text Available Aging is the phenotype resulting from accumulation of genetic, cellular, and molecular damages. Many factors have been identified as either the cause or consequence of age-related decline in functions and repair mechanisms. The hypothalamus is the source and a target of many of these factors and hormones responsible for the overall homeostasis in the body. With advanced age, the sensitivity of the hypothalamus to various feedback signals begins to decline. In recent years, several aging-related genes have been identified and their signaling pathways elucidated. These gene products include mTOR, IKK-β/NF-κB complex, and HIF-1α, an important cellular survival signal. All of these activators/modulators of the aging process have also been identified in the hypothalamus and shown to play crucial roles in nutrient sensing, metabolic regulation, energy balance, reproductive function, and stress adaptation. This illustrates the central role of the hypothalamus in aging.Inside the mitochondria, succinate is one of the most prominent intermediates of the Krebs cycle. Succinate oxidation in mitochondria provides the most powerful energy output per unit time. Extra-mitochondrial succinate triggers a host of succinate receptor (SUCN1 or GPR91-mediated signaling pathways in many peripheral tissues including the hypothalamus. One of the actions of succinate is to stabilize the hypoxia and cellular stress conditions by inducing the transcriptional regulator HIF-1α. Through these actions, it is hypothesized that succinate has the potential to restore the gradual but significant loss in functions associated with cellular senescence and systemic aging.

  11. 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...

  12. The possible role of hydrothermal vents in chemical evolution: Succinic acid radiolysis and thermolysis

    Science.gov (United States)

    Cruz-Castañeda, J.; Colín-García, M.; Negrón-Mendoza, A.

    2014-07-01

    In this research, the behavior under a high radiation field or high temperature of succinic acid, a dicarboxylic acid clue in metabolic routes, is studied. For this purpose, the molecule was irradiated with gamma rays in oxygen-free aqueous solutions, and the thermal decomposition was studied in a static system at temperatures up to 90 °C, simulating a white hydrothermal vent. Our results indicate that a succinic acid is a relatively stable compound under irradiation. The gamma radiolysis yields carbon dioxide and di- and tricarboxylic acids such as malonic, carboxysuccinic, and citric acids. The main products obtained by the thermal treatment were CO2 and propionic acid.

  13. Metabolic evolution of two reducing equivalent-conserving pathways for high-yield succinate production in Escherichia coli.

    Science.gov (United States)

    Zhu, Xinna; Tan, Zaigao; Xu, Hongtao; Chen, Jing; Tang, Jinlei; Zhang, Xueli

    2014-07-01

    Reducing equivalents are an important cofactor for efficient synthesis of target products. During metabolic evolution to improve succinate production in Escherichia coli strains, two reducing equivalent-conserving pathways were activated to increase succinate yield. The sensitivity of pyruvate dehydrogenase to NADH inhibition was eliminated by three nucleotide mutations in the lpdA gene. Pyruvate dehydrogenase activity increased under anaerobic conditions, which provided additional NADH. The pentose phosphate pathway and transhydrogenase were activated by increased activities of transketolase and soluble transhydrogenase SthA. These data suggest that more carbon flux went through the pentose phosphate pathway, thus leading to production of more reducing equivalent in the form of NADPH, which was then converted to NADH through soluble transhydrogenase for succinate production. Reverse metabolic engineering was further performed in a parent strain, which was not metabolically evolved, to verify the effects of activating these two reducing equivalent-conserving pathways for improving succinate yield. Activating pyruvate dehydrogenase increased succinate yield from 1.12 to 1.31mol/mol, whereas activating the pentose phosphate pathway and transhydrogenase increased succinate yield from 1.12 to 1.33mol/mol. Activating these two pathways in combination led to a succinate yield of 1.5mol/mol (88% of theoretical maximum), suggesting that they exhibited a synergistic effect for improving succinate yield.

  14. 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,...

  15. Bulk modification of PDMS microchips by an amphiphilic copolymer.

    Science.gov (United States)

    Xiao, Yan; Yu, Xiao-Dong; Xu, Jing-Juan; Chen, Hong-Yuan

    2007-09-01

    A simple and rapid bulk-modification method based on adding an amphiphilic copolymer during the fabrication process was employed to modify PDMS microchips. Poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) was used as the additive substance. Compared to the native PDMS microchips, both the contact angle and the EOF of the bulk-modified PDMS microchips decreased. The effects of the additive loading and the pH on the EOF were investigated in detail. The bulk-modified PDMS microchips exhibited reproducible and stable EOF behavior. The application of the bulk-modified PDMS microchips was also studied and the results indicated that they could be successfully used to separate amino acids and to suppress protein adsorption.

  16. [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

  17. Supramolecular chirality in self-assembled peptide amphiphile nanostructures.

    Science.gov (United States)

    Garifullin, Ruslan; Guler, Mustafa O

    2015-08-11

    Induced supramolecular chirality was investigated in the self-assembled peptide amphiphile (PA) nanosystems. Having shown that peptide chirality can be transferred to the covalently-attached achiral pyrene moiety upon PA self-assembly, the chiral information is transferred to molecular pyrene via weak noncovalent interactions. In the first design of a supramolecular chiral system, the chromophore was covalently attached to a peptide sequence (VVAGH) via an ε-aminohexanoic acid spacer. Covalent attachment yielded a PA molecule self-assembling into nanofibers. In the second design, the chromophore was encapsulated within the hydrophobic core of self-assembled nanofibers of another PA consisting of the same peptide sequence attached to lauric acid. We observed that supramolecular chirality was induced in the chromophore by PA assembly into chiral nanostructures, whether it was covalently attached, or noncovalently bound. PMID:26146021

  18. 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)

  19. 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

  20. 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

  1. 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.

  2. 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

  3. Non-Surface Activity of Cationic Amphiphilic Diblock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, Rati Ranjan; Yamada, Tasuku; Matsuoka, Hideki, E-mail: ratiranjan@immt.res.in, E-mail: matsuoka@star.polym.kyoto-u.ac.jp [Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2011-09-19

    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.

  4. 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.

  5. Nucleoside, nucleotide and oligonucleotide based amphiphiles: a successful marriage of nucleic acids with lipids.

    Science.gov (United States)

    Gissot, Arnaud; Camplo, Michel; Grinstaff, Mark W; Barthélémy, Philippe

    2008-04-21

    Amphiphilic molecules based on nucleosides, nucleotides and oligonucleotides are finding more and more biotechnological applications. This Perspective highlights their synthesis, supramolecular organization as well as their applications in the field of biotechnology.

  6. 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

    effect of amphiphiles, at concentrations often used in biological research, on the bilayer elastic response to a change in the hydrophobic length of an embedded protein. The effects of structurally diverse amphiphiles can be described by changes in a phenomenological bilayer spring constant (H......Many drugs are amphiphiles that, in addition to binding to a particular target protein, adsorb to cell membrane lipid bilayers and alter intrinsic bilayer physical properties (e. g., bilayer thickness, monolayer curvature, and elastic moduli). Such changes can modulate membrane protein function......-B) that summarizes the bilayer elastic properties, as sensed by a bilayer-spanning protein. Amphiphile-induced changes in H-B, measured using gA channels of a particular length, quantitatively predict changes in lifetime for channels of a different length-as well as changes in the inactivation of voltage...

  7. Amphiphilic organoplatinum(II) complexes: Self-assembly in solution and at interfaces

    Science.gov (United States)

    Maran, Umamageswaran

    Organoplatinum(II) gemini amphiphiles with three different chain lengths and a predefined angle of 60° are synthesized. Self-organization at the air-water interface is investigated as a function of chain length and reduction in surface area, by using Langmuir-trough techniques. The atomic force microscopy (AFM) images of the transferred Langmuir-Schaefer (LS) films reveals wormlike aggregates for the organoplatinum(II) gemini amphiphiles, possessing hexyloxy- and dodecyloxy-chains. A neutral crown ether functionalized [1+1] facial amphiphile was self-assembled from a flexible 32-membered dibenzo crown ether and a diplatinum acceptor clip. A homologous series of charged triangle-shaped amphiphilic metallomacrocyles was self-assembled from stoichiometric amounts of organoplatinum(II) gemini amphiphiles and bipyridyl donor molecules in quantitative yields. The amphiphilic triangular scaffolds were characterized by multinuclear NMR and ESI-MS. A new amphiphilic organoplatinum(II) precursor with a predefined angle of 90° was synthesized. The precursor was mixed in stoichiometric ratios with two different 3-substituted pyridines and a rigid bipyridyl ligand to construct three charged amphiphilic metallomacrocyles. The computational calculations on the assemblies constructed from flexible 3-substituted pyridines indicate that the assemblies exist largely as chair isomers. The self-organization of the hexacationic triangular amphiphiles at liquid-liquid, air-water and solid-air interfaces was studied using confocal microscopy, in situ Raman spectroscopy, Langmuir-trough techniques, fluorescence spectroscopy and AFM. The amphiphilic triangle with octadecyloxy-chains was found to form a bicontinuous coacervate with pores in a chloroform/water solvent mixture. The pressure-area isotherms revealed formation of surface aggregates at the air-water interface. Fluid AFM studies on the transferred LS layers reveal ridge-like patterns with a flat top. Models were constructed to

  8. 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

  9. 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...

  10. 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.

  11. SYNTHESIS OF AMPHIPHILIC COMB-SHAPED COPOLYMERS USED FOR SURFACE MODIFICATION OF PVDF MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    徐又一

    2009-01-01

    The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4- hydroxyphenyl) maleimide)(SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate(PEGMA) side groups was achieved by atom transfer radical polymerization(ATRP).The amphiphilic copolymers were characterized by ~1H-NMR, Fourier transform infrared(FTIR) spectroscopy and gel permeation chromatography(GPC).From thermogravimetric analysis (TGA),the decomposition temperature of SHMI-g-PEGMA is low...

  12. [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

  13. 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

  14. Complex formation and solubility of Pu(IV) with malonic and succinic acids

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, T.; Kobayashi, T.; Takagi, I.; Moriyama, H. [Kyoto Univ. (Japan). Dept. of Nuclear Engineering; Fujiwara, A. [Radioactive Waste Management Funding and Research Center, Tokyo (Japan); Kulyako, Y.M.; Perevalov, S.A.; Myasoedov, B.F. [Russian Academy of Sciences (RAS), Moscow (RU). V.I. Vernadsky Inst. of Geochemistry and Analytical Chemistry (GEOKHI)

    2009-07-01

    The complex formation constants of tetravalent plutonium ion with malonic and succinic acids in aqueous solution were determined by the solvent-extraction method. Also, by taking the known values of the solubility products, the hydrolysis constants and the formation constants, the experimental solubility data of plutonium in the presence of carboxylates were analyzed. (orig.)

  15. Amorphous/crystal and polymer/filler interphases in biocomposites from poly(butylene succinate)

    Energy Technology Data Exchange (ETDEWEB)

    Signori, Francesca [Consiglio Nazionale delle Ricerche - Istituto per i Processi Chimico-Fisici (CNR-IPCF), Via G. Moruzzi 1, I-56124 Pisa (Italy); Pelagaggi, Martina [Universita di Pisa - Dipartimento di Chimica e Chimica Industriale, Via Risorgimento 35, I-56126 Pisa (Italy); Bronco, Simona [Consiglio Nazionale delle Ricerche - Istituto per i Processi Chimico-Fisici (CNR-IPCF), Via G. Moruzzi 1, I-56124 Pisa (Italy); Righetti, Maria Cristina, E-mail: righetti@ipcf.cnr.it [Consiglio Nazionale delle Ricerche - Istituto per i Processi Chimico-Fisici (CNR-IPCF), Via G. Moruzzi 1, I-56124 Pisa (Italy)

    2012-09-10

    Highlights: Black-Right-Pointing-Pointer The existence of intermolecular interactions between poly(butylene succinate) and hemp fibres was proved from specific heat capacities data. Black-Right-Pointing-Pointer Different degrees of mobility of the poly(butylene succinate) amorphous segments were evidenced at the amorphous/crystal interphase. Black-Right-Pointing-Pointer Devitrification of the rigid amorphous fraction in poly(butylene succinate) was found to occur before and simultaneously with the fusion. - Abstract: Poly(butylene succinate)-hemp composites (PBS-hemp), with hemp content in the range 0-40 wt.%, were prepared in the melt and characterized. This paper focuses on the detailed analysis of the thermal behaviour of the PBS-hemp composites, investigated by differential scanning calorimetry (DSC), to enlighten the polymer/fibre interphase features. The occurrence of specific intermolecular interactions between PBS and hemp was assessed from specific heat capacity data. Different degrees of mobility of the PBS amorphous segments were found at the amorphous/crystal interphases. A broadening of the bulk glass transition was observed, and attributed to the presence of polymer segments slightly constrained. Moreover, a rigid amorphous fraction that devitrifies at temperatures higher than the bulk glass transition, partly before the melting region and partly simultaneously with the fusion, was observed and quantified, and attributed to the presence of major constraints probably occurring in geometrically restricted areas.

  16. 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)

  17. Acetate:succinate CoA-transferase in the hydrogenosomes of Trichomonas vaginalis: Identification and characterization

    NARCIS (Netherlands)

    K.W.A. Grinsven; S. Rosnowsky (Silke); S.W.H. van Weelden (Susanne); S. Pütz (Simone); M. van der Giezen (Mark); W. Martin (William); J.J. van Hellemond (Jaap); A.G.M. Tielens (Aloysius); K. Henze (Katrin)

    2008-01-01

    textabstractAcetate:succinate CoA-transferases (ASCT) are acetate-producing enzymes in hydrogenosomes, anaerobically functioning mitochondria and in the aerobically functioning mitochondria of trypanosomatids. Although acetate is produced in the hydrogenosomes of a number of anaerobic microbial euka

  18. 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

  19. 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.

  20. 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....

  1. Studies on Cross-linking of succinic acid with chitosan/collagen

    Directory of Open Access Journals (Sweden)

    Tapas Mitra

    2013-01-01

    Full Text Available The present study summarizes the cross-linking property of succinic acid with chitosan /collagen. In detail, the chemistry behind the cross-linking and the improvement in mechanical and thermal properties of the cross-linked material were discussed with suitable instruments and bioinformatics tools. The concentration of succinic acid with reference to the chosen polymers was optimized. A 3D scaffold prepared using an optimized concentration of succinic acid (0.2% (w/v with chitosan (1.0% (w/v and similarly with collagen (0.5% (w/v, was subjected to surface morphology, FT-IR analysis, tensile strength assessment, thermal stability and biocompatibility. Results revealed, cross-linking with succinic acid impart appreciable mechanical strength to the scaffold material. In silico analysis suggested the prevalence of non-covalent interactions, which played a crucial role in improving the mechanical and thermal properties of the cross-linked scaffold. The resultant 3D scaffold may find application as wound dressing material, as an implant in clinical applications and as a tissue engineering material.

  2. 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...

  3. Nucleation kinetics of urea succinic acid –ferroelectric single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Dhivya, R. [Crystal growth and Crystallography Division, School of Advanced Sciences, VIT University, Vellore-632014, Tamilnadu (India); Voohrees College, Vellore-632014, Tamilnadu (India); Vizhi, R. Ezhil, E-mail: rezhilvizhi@vit.ac.in, E-mail: revizhi@gmail.com; Babu, D. Rajan [Crystal growth and Crystallography Division, School of Advanced Sciences, VIT University, Vellore-632014, Tamilnadu (India)

    2015-06-24

    Single crystals of Urea Succinic Acid (USA) were grown by slow cooling technique. The crystalline system was confirmed by powder X-ray diffraction. The metastable zonewidth were carried out for various temperatures i.e., 35°, 40°, 45° and 50°C. The induction period is experimentally determined and various nucleation parameters have been estimated.

  4. Efficient production of succinic acid from Palmaria palmata hydrolysate by metabolically engineered Escherichia coli.

    Science.gov (United States)

    Olajuyin, Ayobami Matthew; Yang, Maohua; Liu, Yilan; Mu, Tingzhen; Tian, Jiangnan; Adaramoye, Oluwatosin Adekunle; Xing, Jianmin

    2016-08-01

    Succinic acid, a C4 dicarboxylic acid is used in many fields such as food, agriculture, pharmaceutical and polymer industries. In this study, microbial production of succinic acid from Palmaria palmata was investigated for the first time. In engineered Escherichia coli KLPPP, lactate dehydrogenase, pyruvate formate lyase, phosphotransacetylase-acetate kinase and pyruvate oxidase genes were deleted while phosphoenolpyruvate carboxykinase was overexpressed. The recombinant exhibited higher molar yield of succinic acid on galactose (1.20±0.02mol/mol) than glucose (0.48±0.03mol/mol). The concentration and molar yield of succinic acid were 22.40±0.12g/L and 1.13±0.02mol/mol total sugar respectively after 72h dual phase fermentation from P. palmata hydrolysate which composed of glucose (12.57±0.17g/L) and galactose (18.03±0.10g/L). The results demonstrate that P. palmata red macroalgae biomass represents a novel and an economically alternative feedstock for biochemicals production. PMID:27203224

  5. Co- and Terpolyesters based on isosorbide and succinic acid for coating applications : synthesis and characterization

    NARCIS (Netherlands)

    Noordover, B.A.J.; Staalduinen, van V.G.; Duchateau, R.; Koning, C.E.; Benthem, van R.A.T.M.; Mak, M.; Heise, A.; Frissen, A.E.; Haveren, van J.

    2006-01-01

    Co- and terpolyesters based on succinic acid and isosorbide in combination with other renewable monomers such as 2,3-butanediol, 1,3-propanediol, and citric acid were synthesized and characterized. Linear polyesters were obtained via melt polycondensation of nonactivated dicarboxylic acids with OH f

  6. Electrospun Nanoporous Poly(butylenes succinate-co-bytylene terephthalate Nonwoven Mats

    Directory of Open Access Journals (Sweden)

    Liang Wang

    2011-01-01

    Full Text Available A traditional Chinese drug “Yunnan Baiyao” is used as an additive in poly(butylenes succinate-co-bytylene terephthalate (PBST solution, which is a kind of biodegradable aliphatic-aromatic copolyesters, to produce microspheres with nanoporosity by electrospinning; the tunable size of nanoporosity can be controlled by changing the voltage applied in the electrospinning process.

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    M. V. Soura

    2008-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Keleş, Elif, E-mail: elifkelesh@hotmail.com [Department of Chemistry, Bülent Ecevit University, Zonguldak 67100 (Turkey); Hazer, Baki, E-mail: bhazer2@yahoo.com [Department of Chemistry, Bülent Ecevit University, Zonguldak 67100 (Turkey); Cömert, Füsun B. [Department of Microbiology, Faculty of Medicine, Bülent Ecevit University, 67600 Zonguldak (Turkey)

    2013-04-01

    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, {sup 1}H NMR, {sup 13}C 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.

  10. 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...

  11. 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.

  12. Photochemical Isomerization and Topochemical Polymerization of the Programmed Asymmetric Amphiphiles

    Science.gov (United States)

    Kim, Dae-Yoon; Lee, Sang-A.; Jung, Daseal; Jeong, Kwang-Un

    2016-06-01

    For the advancement in multi-stimuli responsive optical devices, we report the elaborate molecular engineering of the dual photo-functionalized amphiphile (abbreviated as AZ1DA) containing both a photo-isomerizable azobenzene and a photo-polymerizable diacetylene. To achieve the efficient photochemical reactions in thin solid films, the self-assembly of AZ1DA molecules into the ordered phases should be precisely controlled and efficiently utilized. First, the remote-controllable light shutter is successfully demonstrated based on the reversible trans-cis photo-isomerization of azobenzene group in the smectic A mesophase. Second, the self-organized monoclinic crystal phase allows us to validate the photo-polymerization of diacetylene moiety for the photo-patterned thin films and the thermo-responsible color switches. From the demonstrations of optically tunable thin films, it is realized that the construction of strong relationships between chemical structures, molecular packing structures and physical properties of the programmed molecules is the core research for the development of smart and multifunctional soft materials.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. Cholesterol-Targeted Anticancer and Apoptotic Effects of Anionic and Polycationic Amphiphilic Cyclodextrin Nanoparticles.

    Science.gov (United States)

    Varan, Gamze; Öncül, Selin; Ercan, Ayşe; Benito, Juan M; Ortiz Mellet, Carmen; Bilensoy, Erem

    2016-10-01

    Amphiphilic cyclodextrins (CDs) are biocompatible derivatives of natural CDs and are able to form nanoparticles or polyplexes spontaneously. In this study, nanoparticles prepared from nonionic (6OCaproβCD) or cationic amphiphilic CD (PC βCDC6) were used comparatively to develop nanoparticles intended for breast cancer therapy. The characterization of these nanoparticles was performed both by in vitro and cell culture studies. Furthermore, the apoptotic and cytotoxic effects of blank amphiphilic CDs were demonstrated by various mechanistic methods including Caspase-8 activity, lipid peroxidation assay, TUNEL assay, Tali(®)-based image analysis, cholesterol assay, and gene expression studies. Blank nanoparticles exerted cytotoxicity against a variety of cancer cells (MCF-7, HeLa, HepG2, and MB49) but none to healthy cells (L929, G/G). Interestingly, blank 6OCaproβCD and blank PC βCDC6 derivatives were found to be intrinsically effective on cell number and membrane integrity of MCF-7 cells in apoptosis studies. Further in-depth studies were performed to elucidate the selective mechanism of anticancer action in MCF-7 cells caused by these amphiphilic CDs. In conclusion, blank amphiphilic CD nanoparticles induced apoptosis through mitochondrial pathway targeted to cholesterol microdomains in cancer cell membrane. PMID:27488900

  5. 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

  6. 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

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

    DEFF Research Database (Denmark)

    Carrozzo, Rosalba; Verrigni, Daniela; Rasmussen, Magnhild;

    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 findings...... in these and 46 previously reported patients. PATIENTS AND RESULTS: Of the 71 patients, 50 had SUCLA2 mutations and 21 had SUCLG1 mutations. In the newly-reported 20 SUCLA2 patients we found 16 different mutations, of which nine were novel: two large gene deletions, a 1 bp duplication, two 1 bp deletions, a 3 bp...... insertion, a nonsense mutation and two missense mutations. In the newly-reported SUCLG1 patients, five missense mutations were identified, of which two were novel. The median onset of symptoms was two months for patients with SUCLA2 mutations and at birth for SUCLG1 patients. Median survival was 20 years...

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. Model-guided metabolic gene knockout of gnd for enhanced succinate production in Escherichia coli from glucose and glycerol substrates.

    Science.gov (United States)

    Mienda, Bashir Sajo; Shamsir, Mohd Shahir; Illias, Rosli Md

    2016-04-01

    The metabolic role of 6-phosphogluconate dehydrogenase (gnd) under anaerobic conditions with respect to succinate production in Escherichia coli remained largely unspecified. Herein we report what are to our knowledge the first metabolic gene knockout of gnd to have increased succinic acid production using both glucose and glycerol substrates in E. coli. Guided by a genome scale metabolic model, we engineered the E. coli host metabolism to enhance anaerobic production of succinic acid by deleting the gnd gene, considering its location in the boundary of oxidative and non-oxidative pentose phosphate pathway. This strategy induced either the activation of malic enzyme, causing up-regulation of phosphoenolpyruvate carboxylase (ppc) and down regulation of phosphoenolpyruvate carboxykinase (ppck) and/or prevents the decarboxylation of 6 phosphogluconate to increase the pool of glyceraldehyde-3-phosphate (GAP) that is required for the formation of phosphoenolpyruvate (PEP). This approach produced a mutant strain BMS2 with succinic acid production titers of 0.35 g l(-1) and 1.40 g l(-1) from glucose and glycerol substrates respectively. This work further clearly elucidates and informs other studies that the gnd gene, is a novel deletion target for increasing succinate production in E. coli under anaerobic condition using glucose and glycerol carbon sources. The knowledge gained in this study would help in E. coli and other microbial strains development for increasing succinate production and/or other industrial chemicals. PMID:26878126

  16. 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.

  17. 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

  18. Engineering of Corynebacterium glutamicum for growth and succinate production from levoglucosan, a pyrolytic sugar substrate.

    Science.gov (United States)

    Kim, Eun-Mi; Um, Youngsoon; Bott, Michael; Woo, Han Min

    2015-10-01

    Thermochemical processing provides continuous production of bio-oils from lignocellulosic biomass. Levoglucosan, a pyrolytic sugar substrate C6H10O5 in a bio-oil, has been used for ethanol production using engineered Escherichia coli. Here we provide the first example for succinate production from levoglucosan with Corynebacterium glutamicum, a well-known industrial amino acid producer. Heterologous expression of a gene encoding a sugar kinase from Lipomyces starkeyi, Gibberella zeae or Pseudomonas aeruginosa was employed for levoglucosan conversion in C. glutamicum because the wild type was unable to utilize levoglucosan as sole carbon source. As result, expression of a levoglucosan kinase (LGK) of L. starkeyi only enabled growth with levoglucosan as sole carbon source in CgXII minimal medium by catalyzing conversion of levoglucosan to glucose-6-phosphate. Subsequently, the lgk gene was expressed in an aerobic succinate producer of C. glutamicum, strain BL-1. The recombinant strain showed a higher succinate yield (0.25 g g(-1)) from 2% (w/v) levoglucosan than the reference strain BL-1 from 2% (w/v) glucose (0.19 g g(-1)), confirming that levoglucosan is an attractive carbon substrate for C. glutamicum producer strains. In summary, we demonstrated that a pyrolytic sugar could be a potential carbon source for microbial cell factories. PMID:26363018

  19. Synthesis of Vitamin E Succinate from Candida rugosa Lipase in Organic Medium

    Institute of Scientific and Technical Information of China (English)

    JIANG Xiang-jun; HU Yi; JIANG Ling; GONG Ji-hong; HUANG He

    2013-01-01

    A screening of commercially available lipases for the synthesis of vitamin E succinate showed that lipase from Candida rugosa presented the highest yield.The synthesis of vitamin E succinate in organic solvents with different lgP values ranging from-1.3 to 3.5 was investigated.Of particular interest was that dimethyl sulfoxide (DMSO) with the lowest lgP exhibited the highest yield among all the organic solvents used.It suggests that lgP is incapable of satisfactorily predicting the biocompatibility of organic solvents due to the complexity of enzymatic reaction with hydrophilic and hydrophobic substrates in organic solvent.Effects of different operating conditions,such as molar ratio of substrate,enzyme concentration,reaction temperature,mass transfer,and reaction time were also studied.Under the optimum conditions of 10 g/L enzyme,a stirring rate of 100 r/min,a substrate molar ratio of 5:1 at 55 C for 18 h,a satisfactory yield(46.95%) was obtained.The developed method has a potential to be used for efficient enzymatic production of vitamin E succinate.

  20. Redox stress is not essential for the pseudo-hypoxic phenotype of succinate dehydrogenase deficient cells.

    Science.gov (United States)

    Selak, Mary A; Durán, Raul V; Gottlieb, Eyal

    2006-01-01

    HIFalpha prolyl hydroxylases (PHDs) are a family of enzymes that regulate protein levels of the alpha subunit of the hypoxia inducible transcription factor (HIF) under different oxygen levels. PHDs catalyse the conversion of a prolyl residue, molecular oxygen and alpha-ketoglutarate to hydroxy-prolyl, carbon dioxide and succinate in a reaction dependent on ferrous iron and ascorbate as cofactors. Recently it was shown that pseudo-hypoxia, HIF induction under normoxic conditions, is an important feature of tumours generated as a consequence of inactivation of the mitochondrial tumour suppressor 'succinate dehydrogenase' (SDH). Two models have been proposed to describe the link between SDH inhibition and HIF activation. Both models suggest that a mitochondrial-generated signal leads to the inhibition of PHDs in the cytosol, however, the models differ in the nature of the proposed messenger. The first model postulates that mitochondrial-generated hydrogen peroxide mediates signal transduction while the second model implicates succinate as the molecular messenger which leaves the mitochondrion and inhibits PHDs in the cytosol. Here we show that pseudo-hypoxia can be observed in SDH-suppressed cells in the absence of oxidative stress and in the presence of effective antioxidant treatment.

  1. 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.

  2. 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

  3. Microbial production of Propionic and Succinic acid from Sorbitol using Propionibacterium acidipropionici.

    Science.gov (United States)

    Duarte, Juliana C; Valença, Gustavo P; Moran, Paulo J S; Rodrigues, J Augusto R

    2015-01-01

    Three sequential fermentative batches were carried out with cell recycle in four simultaneously operating bioreactors maintained at pH 6.5, 30°C, and 100 rpm. P. acidipropionici ATCC 4875 was able to produce propionic and succinic acid from sorbitol. The concentration of propionic acid decreased slightly from 39.5 ± 5.2 g L(-1) to 34.4 ± 1.9 g L(-1), and that of succinic acid increased significantly from 6.1 ± 2.1 g L(-1) to 14.8 ± 0.9 g L(-1) through the sequential batches. In addition, a small amount of acetic acid was produced that decreased from 3.3 ± 0.4 g L(-1) to 2.0 ± 0.3 g L(-1) through the batches. The major yield for propionic acid was 0.613 g g(-1) in the first batch and succinic acid it was 0.212 g g(-1) in the third batch. The minor yield of acetic acid was 0.029 g g(-1), in the second and third batches.

  4. 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

  5. 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.

  6. 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.

  7. Solid-Liquid Equilibria of Succinic Acid in Cyclohexanone, Cyclohexanol and Their Mixed Solvents

    Institute of Scientific and Technical Information of China (English)

    FAN Lihua; MA Peisheng; SONG Weiwei

    2007-01-01

    Solubilities were measured for succinic acid dissolved in cyclohexanone, cyclohexanol and 5 of their mixed solvents at the temperature range from 291.85 K to 358.37 K using a dynamic method. The solubility data were regressed by λh equation, withthe average absolute relative deviation 3.47%. The binary interaction parameter is 0.306 7 for the mixed solvent of cyclohexanone and cyclohexanol was determined by correlating the experimental solubilities with the modified λh equation. When the binary interaction parameter was determined, it can be used to extrapolate the solubilities of succinic acid in mixed solvents of cyclohexanone and cyclohexanol at any proportion. The average absolute relative deviation was 7.69% by using the modified λh equation to correlate the solubility data, however, the average absolute relative deviation was 8.89% by using NRTL equation to correlate the solubility data. The results show that the accuracy of the modified λh equation is better than that of the NRTL equation for the solubility of succinic acid in the 5 mixed solvents of cyclohexanone and cyclohexanol.

  8. 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.

  9. Tuning peptide amphiphile supramolecular structure for biomedical applications

    Science.gov (United States)

    Pashuck, Eugene Thomas, III

    The use of biomaterials in regenerative medicine has been an active area of research for more than a decade. Peptide amphiphiles, which are short peptide sequences coupled to alkyl tails, have been studied in the Stupp group since the beginning of the decade and been used for a variety of biomedical applications. Most of the work has focused on the bioactive epitopes places on the periphery of the PA molecules, but the interior amino acids, known as the beta-sheet region, give the PA nanofiber gel much of its mechanical strength. To study the important parameters in the beta-sheet region, six PA molecules were constructed to determine the influence of beta-sheet length and order of the amino acids in the beta-sheet. It was found that having beta-sheet forming amino acids near the center of the fiber improves PA gel stiffness, and that having extra amino acids that have preferences for other secondary structures, like alpha-helix decreased the gels stiffness. Using FTIR and circular dichroism it was found that the mechanical properties are influenced by the amount of twist in the beta-sheet, and PAs that have more twisted beta-sheets form weaker gels. The effect amino acid properties have on peptide amphiphile self-assembly where studied by synthesizining molecules with varying side group size and hydrophobicity. It was found that smaller amino acids lead to stiffer gels and when two amino acids had the same size the amino acid with the larger beta-sheet propensity lead to a stiffer gel. Furthermore, small changes in peptide structure were found to lead to big changes in nanostructure, as leucine and isoleucine, which have the same size but slightly different structures, form flat ribbons and cylindrical nanofibers, respectively. Phenylalanine and alanine were studied more indepth because they represent the effects of adding an aromatic group to amino acids in the beta-sheet regon. These phenylalanine PAs formed short, twisted ribbons when freshly dissolved in water

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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

  15. High Selective Performance of Designed Antibacterial and Anticancer Peptide Amphiphiles.

    Science.gov (United States)

    Chen, Cuixia; Chen, Yucan; Yang, Cheng; Zeng, Ping; Xu, Hai; Pan, Fang; Lu, Jian Ren

    2015-08-12

    Short designed peptide amphiphiles are attractive at killing bacteria and inhibiting cancer cell growth, and the flexibility in their structural design offers a great potential for improving their potency and biocompatibility to mammalian host cells. Amino acid sequences such as G(IIKK)nI-NH2 (n≥3) have been shown to be membrane lytic, but terminal amino acid modifications could impose a huge influence on their performance. We report in this work how terminal amino acid modifications to G(IIKK)3I-NH2 influence its α-helical structure, membrane penetrating ability, and selective actions against different cell types. Deletion of an N-terminal Gly or a C-terminal Ile did not affect their antibacterial activity much, an observation consistent with their binding behavior to negatively charged membrane lipid monolayers. However, the cytotoxicity against mammalian cells was much worsened by the N-terminal Gly deletion, consistent with an increase in its helical content. Despite little impact on the antibacterial activity of G(IIKK)3I-NH2, deletion of both terminal amino acids greatly reduced its antitumor activity. Cholesterol present in tumor cell membrane-mimic was thought to constrain (IIKK)3-NH2 from penetrating into the cancerous membranes, evident from its lowest surface physical activity at penetrating model lipid membranes. On the other hand, its low toxicity to normal mammalian cells and high antibacterial activity in vitro and in vivo made it an attractive antibacterial agent. Thus, terminal modifications can help rebalance the different interactions involved and are highly effective at manipulating their selective membrane responses.

  16. 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.

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

    Science.gov (United States)

    Chang, Hung-Yu; Tu, Sheng-Hung; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2014-08-01

    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.

  18. 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

  19. Sacrificial amphiphiles: Eco-friendly chemical herders as oil spill mitigation chemicals.

    Science.gov (United States)

    Gupta, Deeksha; Sarker, Bivas; Thadikaran, Keith; John, Vijay; Maldarelli, Charles; John, George

    2015-06-01

    Crude oil spills are a major threat to marine biota and the environment. When light crude oil spills on water, it forms a thin layer that is difficult to clean by any methods of oil spill response. Under these circumstances, a special type of amphiphile termed as "chemical herder" is sprayed onto the water surrounding the spilled oil. The amphiphile forms a monomolecular layer on the water surface, reducing the air-sea surface tension and causing the oil slick to retract into a thick mass that can be burnt in situ. The current best-known chemical herders are chemically stable and nonbiodegradable, and hence remain in the marine ecosystem for years. We architect an eco-friendly, sacrificial, and effective green herder derived from the plant-based small-molecule phytol, which is abundant in the marine environment, as an alternative to the current chemical herders. Phytol consists of a regularly branched chain of isoprene units that form the hydrophobe of the amphiphile; the chain is esterified to cationic groups to form the polar group. The ester linkage is proximal to an allyl bond in phytol, which facilitates the hydrolysis of the amphiphile after adsorption to the sea surface into the phytol hydrophobic tail, which along with the unhydrolyzed herder, remains on the surface to maintain herding action, and the cationic group, which dissolves into the water column. Eventual degradation of the phytol tail and dilution of the cation make these sacrificial amphiphiles eco-friendly. The herding behavior of phytol-based amphiphiles is evaluated as a function of time, temperature, and water salinity to examine their versatility under different conditions, ranging from ice-cold water to hot water. The green chemical herder retracted oil slicks by up to ~500, 700, and 2500% at 5°, 20°, and 35°C, respectively, during the first 10 min of the experiment, which is on a par with the current best chemical herders in practice. PMID:26601197

  20. Fusiogenic activity of natural amphiphiles, 5-n-alkylresorcinols in a yeast protoplast system.

    Science.gov (United States)

    Kozubek, A; Skała, J

    1995-01-01

    Two homologues of cereal grain resorcinolic lipids, 5-n-heptadecylresorcinol and 5-n-heptadecenylresorcinol studied in the system employing yeast cell protoplasts showed marked fusiogenic activity. The frequency of hybrid formation induced by studied amphiphiles was significantly higher than that obtained with the use of 40% (w/v) polyethylene glycol 4000. The resorcinolic lipids as fusion-inducing agents did not affect regeneration of the cellular wall. The fusiogenic activity of resorcinolic lipids lost when calcium ions were absent in the medium. Fusiogenic activity of studied amphiphiles is related to their ability to induce non-bilayer structures within the cellular membranes. PMID:8579682

  1. Monte Carlo simulation for the micellar behavior of amphiphilic comb-like copolymers

    Institute of Scientific and Technical Information of China (English)

    冯莺; 隋家贤; 赵季若; 陈欣方

    2000-01-01

    Micellar behaviors in 2D and 3D lattice models for amphiphilic comb-like copolymers in water phase and in water/oil mixtures were simulated. A dynamical algorithm together with chain reptation movements was used in the simulation. Three-dimension displaying program was pro-grammed and free energy was estimated by Monte Carlo technigue. The results demonstrate that reduced interaction energy influences morphological structures of micelle and emulsion ??stems greatly; 3D simulation showing can display more direct images of morphological structures; the amphiphilic comb-like polymers with a hydrophobic main chain and hydrophilic side chains have lower energy in water than in oil.

  2. Synthesis of amphiphilic aminated inulin via 'click chemistry' and evaluation for its antibacterial activity.

    Science.gov (United States)

    Dong, Fang; Zhang, Jun; Yu, Chunwei; Li, Qing; Ren, Jianming; Wang, Gang; Gu, Guodong; Guo, Zhanyong

    2014-09-15

    Inulins are a group of abundant, water-soluble, renewable polysaccharides, which exhibit attractive bioactivities and natural properties. Improvement such as chemical modification of inulin is often performed prior to further utilization. We hereby presented a method to modify inulin at its primary hydroxyls to synthesize amphiphilic aminated inulin via 'click chemistry' to facilitate its chemical manipulation. Additionally, its antibacterial property against Staphylococcus aureus (S. aureus) was also evaluated and the best inhibitory index against S. aureus was 58% at 1mg/mL. As the amphiphilic aminated inulin is easy to prepare and exhibits improved bioactivity, this material may represent as an attractive new platform for chemical modifications of inulin.

  3. Intra-chain organisation of hydrophobic residues controls inter-chain aggregation rates of amphiphilic polymers

    CERN Document Server

    Varilly, Patrick; Kirkegaard, Julius B; Knowles, Tuomas P J; Chandler, David

    2016-01-01

    Aggregation of amphiphiles through the action of hydrophobic interactions is a common feature in soft condensed matter systems and is of particular importance in the context of biophysics as it underlies both the generation of functional biological machinery as well as the formation of pathological misassembled states of proteins. Here we explore the aggregation behaviour of amphiphilic polymers using lattice Monte-Carlo calculations and show that the distribution of hydrophobic residues within the polymer sequence determines the facility with which dry/wet interfaces can be created and that such interfaces drive the aggregation process.

  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. Toward homosuccinate fermentation: metabolic engineering of Corynebacterium glutamicum for anaerobic production of succinate from glucose and formate.

    Science.gov (United States)

    Litsanov, Boris; Brocker, Melanie; Bott, Michael

    2012-05-01

    Previous studies have demonstrated the capability of Corynebacterium glutamicum for anaerobic succinate production from glucose under nongrowing conditions. In this work, we have addressed two shortfalls of this process, the formation of significant amounts of by-products and the limitation of the yield by the redox balance. To eliminate acetate formation, a derivative of the type strain ATCC 13032 (strain BOL-1), which lacked all known pathways for acetate and lactate synthesis (Δcat Δpqo Δpta-ackA ΔldhA), was constructed. Chromosomal integration of the pyruvate carboxylase gene pyc(P458S) into BOL-1 resulted in strain BOL-2, which catalyzed fast succinate production from glucose with a yield of 1 mol/mol and showed only little acetate formation. In order to provide additional reducing equivalents derived from the cosubstrate formate, the fdh gene from Mycobacterium vaccae, coding for an NAD(+)-coupled formate dehydrogenase (FDH), was chromosomally integrated into BOL-2, leading to strain BOL-3. In an anaerobic batch process with strain BOL-3, a 20% higher succinate yield from glucose was obtained in the presence of formate. A temporary metabolic blockage of strain BOL-3 was prevented by plasmid-borne overexpression of the glyceraldehyde 3-phosphate dehydrogenase gene gapA. In an anaerobic fed-batch process with glucose and formate, strain BOL-3/pAN6-gap accumulated 1,134 mM succinate in 53 h with an average succinate production rate of 1.59 mmol per g cells (dry weight) (cdw) per h. The succinate yield of 1.67 mol/mol glucose is one of the highest currently described for anaerobic succinate producers and was accompanied by a very low level of by-products (0.10 mol/mol glucose).

  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. Self-assembling peptide amphiphile nanostructures for cancer therapy

    Science.gov (United States)

    Soukasene, Stephen

    The application of nanotechnology to cancer therapy shows great promise for reducing the burden of the disease. By virtue of their size, nanoscale objects preferentially accumulate in tumor tissue through an enhanced permeability and retention (EPR) effect. However, to fully overcome the issues that limit current cancer treatments, viable nanostructures must also impart multifunctionality and be fully compatible with their biological surrounds. The self-assembling peptide amphiphile (PA) materials studied extensively in the Stupp Research Group form very biocompatible high aspect ratio nanostructures that meet these criteria. This thesis investigates the development of PA nanostructures designed to treat cancer. We first look to use the PA as a drug delivery vehicle by entrapping a small hydrophobic anti-cancer drug, camptothecin, in the core of the nanostructures. Using a solvent evaporation technique to load the drug into the PA nanofibers, we are able to improve the aqueous solubility of the molecule by nearly 30-fold. TEM and AFM studies show that entrapment of drug molecules does not disrupt the self-assembled morphology of the nanofiber. In vitro and in vivo studies are also conducted to demonstrate the bioactivity of the drug after its entrapment. As a potential platform for novel therapeutics, we next develop techniques for using light irradiation to trigger self-assembly inside the confined space of liposomes. We encapsulate PA monomers that assemble under acidic conditions along with a photoacid generator inside liposomes. Upon exposure to 254 nm light, the PA monomers self assemble inside the liposome to form nanostructures, which we observe through a quick freeze/deep etch technique that allows us to look inside the liposomes by SEM and TEM. Last of all, the development and discovery of epitopes for targeting PA nanostructures to tumors are explored. Using phage display technology we generate two groups of peptide sequences, one of which can potentially

  8. 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

  9. Self-Assembling Peptide Amphiphiles for Targeted Drug Delivery

    Science.gov (United States)

    Moyer, Tyson

    The systemic delivery of therapeutics is currently limited by off-target side effects and poor drug uptake into the cells that need to be treated. One way to circumvent these issues is to target the delivery and release of therapeutics to the desired location while limiting systemic toxicity. Using self-assembling peptide amphiphiles (PAs), this work has investigated supramolecular nanostructures for the development of targeted therapies. Specifically, the research has focused on the interrelationships between presentation of targeting moeities and the control of nanostructure morphology in the context of systemic delivery for targeting cancer and vascular injuries. The self-assembly region of the PA was systematically altered to achieve control of nanostructure widths, from 100 nm to 10 nm, by the addition of valine-glutamic acid dimers into the chemical structure, subsequently increasing the degree of nanostructure twist. For the targeting of tumors, a homing PA was synthesized to include a dimeric, cyclic peptide sequence known to target the cancer-specific, death receptor 5 (DR5) and initiate apoptosis through the oligomerization of DR5. This PA presented a multivalent display of DR5-binding peptides, resulting in improved binding affinity measured by surface plasmon resonance. The DR5-targeting PA also showed enhanced efficacy in both in vitro and in vivo tumor models relative to non-targeted controls. Alternative modifications to the PA-based antitumor therapies included the use of a cytotoxic, membrane-lytic PA coassembled with a pegylated PA, which showed enhanced biodistribution and in vivo activity after coassembly. The functionalization of the hydrophobic core was also accomplished through the encapsulation of the chemotherapy camptothecin, which was shown to be an effective treatment in vivo. Additionally, a targeted PA nanostructure was designed to bind to the site of vascular intervention by targeting collagen IV. Following balloon angioplasty

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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)

  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. 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...

  18. 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...

  19. 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

  20. Self-assembly of block copolymer-based ionic supramolecules based upon multi-tail amphiphiles

    DEFF Research Database (Denmark)

    Asad Ayoubi, M.; Almdal, Kristoffer; Zhu, K.;

    2015-01-01

    Utilising simple acid-base titration chemistry, a new family of Linear-b-Amphiphilic Comb (L-b-AC) ionic supramolecules [Soft Matter 2013, 9, 1540-1555] featuring multi-tail side-chains have been synthesized and examined by synchrotron SAXS. To three different parent diblock copolymers of poly(st...

  1. Inducing spin crossover in metallo-supramolecular polyelectrolytes through an amphiphilic phase transition.

    Science.gov (United States)

    Bodenthin, Yves; Pietsch, Ullrich; Möhwald, Helmuth; Kurth, Dirk G

    2005-03-01

    A phase transition in an amphiphilic mesophase is explored to deliberately induce mechanical strain in an assembly of tightly coupled metal ion coordination centers. Melting of the alkyl chains in the amphiphilic mesophase causes distortion of the coordination geometry around the central transition metal ion. As a result, the crystal field splitting of the d-orbital subsets decreases resulting in a spin transition from a low-spin to a high-spin state. The diamagnetic-paramagnetic transition is reversible. This concept is demonstrated in a metallo-supramolecular coordination polyelectrolyte-amphiphile complex self-assembled from ditopic bis-terpyridines, Fe(II) as central transition metal, and dialkyl phosphates as amphiphiles. The magnetic properties are studied in a Langmuir-Blodgett multilayer. The modularity of this concept provides extensive control of structure and function from molecular to macroscopic length scales and gives access to a wide range of new molecular magnetic architectures such as nanostructures, thin films, and liquid crystals. PMID:15740150

  2. Transfection of small numbers of human endothelial cells by electroporation and synthetic amphiphiles

    NARCIS (Netherlands)

    van Leeuwen, E B; van der Veen, A Y; Hoekstra, D; Engberts, J B; Halie, M R; van der Meer, J; Ruiters, M H

    1999-01-01

    OBJECTIVES: This study compared the efficiency of electroporation and synthetic amphiphiles. (SAINT-2pp/DOPE) in transfecting small numbers of human endothelial cells. METHODS AND RESULTS: Optimal transfection conditions were tested and appeared to be 400 V and 960 microF for electroporation and a 1

  3. Oxidized potato starch based thermoplastic films : Effect of combination of hydrophilic and amphiphilic plasticizers

    NARCIS (Netherlands)

    Niazi, Muhammad Bilal Khan; Broekhuis, Antonius A.

    2016-01-01

    Different combinations of hydrophilic (glycerol and water) and amphiphilic (isoleucine) plasticizers were studied in the production of thermoplastic starch (TPS) powders and films from oxidized potato starch. All powder samples had an irregular and shrivelled morphology. In all mixtures containing i

  4. 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

  5. SYNTHESIS OF AMPHIPHILIC COMB-SHAPED COPOLYMERS USED FOR SURFACE MODIFICATION OF PVDF MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    Jian-hua Li; You-yi Xu; Jian-hua Wang; Chun-hui Du

    2009-01-01

    The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4-hydroxyphenyl) maleimide) (SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate (PEGMA) side groups was achieved by atom transfer radical polymerization (ATRP). The amphiphilic copolymers were characterized by ~1H-NMR, Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). From thermogravimetric analysis (TGA), the decomposition temperature of SHMI-g-PEGMA is lower than that of SHMI, and the graft ratio of PEGMA in the SHMI is 18.6%. The experimental results of solubilities showed that SHMI, SHMI-Br and SHMI-g-PEGMA had excellent solubility in polar solvents, such as DMF, DMSO and NMP. SHMI-g-PEGMA had higher solubilities in H_2O and methanol, while lower solubility in CHCl_3 than SHMI and SHMI-Br. PVDF blend membranes were prepared via the standard immersion precipitation phase inversion process, using amphiphilic SHMI-g-PEGMA copolymer as additives. The morphology and hydrophilicity of the blend membrane surfaces were characterized by SEM and water contact angle. It is demonstrated that the blend membranes display enhanced hydrophilicity compared to unmodified PVDF membranes. Finally, the permeation and anti-fouling properties were investigated. The result shows that amphiphilic SHMI-g-PEGMA copolymer increases the permeatability and anti-fouling property of PVDF membranes greatly.

  6. 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.

  7. 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

  8. 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

  9. Modulation of drug release rate of diltiazem-HCl from hydrogel matrices of succinic acid-treated ispaghula husk.

    Science.gov (United States)

    Gohel, M C; Amin, A F; Chhabaria, M T; Panchal, M K; Lalwani, A N

    2000-01-01

    The feasibility of using succinic acid-treated ispaghula husk in matrix-based tablets of diltiazem-HCl was investigated. The sample prepared using 4:1 weight ratio of ispaghula husk to succinic acid showed improved swelling and gelling. A 3(2) factorial design was employed to investigate the effect of amount of succinic acid-treated ispaghula husk and dicalcium phosphate (DCP) on the percentage of the drug dissolved in 60, 300, and 480 min from the compressed tablets. The results of multiple linear regression analysis revealed that the significance of the amount of succinic acid-treated ispaghula husk was greater in magnitude than that of the amount of DCP in controlling the drug release. Acceptable batches were identified from a contour plot with constraints on the percentage drug released at the three sampling times. A mathematical model was also evolved to describe the entire dissolution profile. The results of F-test revealed that the Higuchi model fits well to the in vitro dissolution data. The tablets showed considerable radial and axial swelling in distilled water. Succinic acid-treated ispaghula husk can be used as an economical hydrophilic matrixing agent.

  10. Enhanced succinic acid production in Aspergillus saccharolyticus by heterologous expression of fumarate reductase from Trypanosoma brucei.

    Science.gov (United States)

    Yang, Lei; Lübeck, Mette; Ahring, Birgitte K; Lübeck, Peter S

    2016-02-01

    Aspergillus saccharolyticus exhibits great potential as a cell factory for industrial production of dicarboxylic acids. In the analysis of the organic acid profile, A. saccharolyticus was cultivated in an acid production medium using two different pH conditions. The specific activities of the enzymes, pyruvate carboxylase (PYC), malate dehydrogenase (MDH), and fumarase (FUM), involved in the reductive tricarboxylic acid (rTCA) branch, were examined and compared in cells harvested from the acid production medium and a complete medium. The results showed that ambient pH had a significant impact on the pattern and the amount of organic acids produced by A. saccharolyticus. The wild-type strain produced higher amount of malic acid and succinic acid in the pH buffered condition (pH 6.5) compared with the pH non-buffered condition. The enzyme assays showed that the rTCA branch was active in the acid production medium as well as the complete medium, but the measured enzyme activities were different depending on the media. Furthermore, a soluble NADH-dependent fumarate reductase gene (frd) from Trypanosoma brucei was inserted and expressed in A. saccharolyticus. The expression of the frd gene led to an enhanced production of succinic acid in frd transformants compared with the wild-type in both pH buffered and pH non-buffered conditions with highest amount produced in the pH buffered condition (16.2 ± 0.5 g/L). This study demonstrates the feasibility of increasing succinic acid production through the cytosolic reductive pathway by genetic engineering in A. saccharolyticus.

  11. Stability-indicating micellar electrokinetic chromatography method for the analysis of sumatriptan succinate in pharmaceutical formulations.

    Science.gov (United States)

    Al Azzam, Khaldun M; Saad, Bahruddin; Tat, Chai Yuan; Mat, Ishak; Aboul-Enein, Hassan Y

    2011-12-15

    A micellar electrokinetic chromatography method for the determination of sumatriptan succinate in pharmaceutical formulations was developed. The effects of several factors such as pH, surfactant and buffer concentration, applied voltage, capillary temperature, and injection time were investigated. Separation took about 5 min using phenobarbital as internal standard. The separation was carried out in reversed polarity mode at 20 °C, 26 kV and using hydrodynamic injection for 10s. Separation was achieved using a bare fused-silica capillary 50 μm×40 cm and background electrolyte of 25 mM sodium dihydrogen phosphate-adjusted with concentrated phosphoric acid to pH 2.2, containing 125 mM sodium dodecyl sulfate and detection was at 226 nm. The method was validated with respect to linearity, limits of detection and quantification, accuracy, precision and selectivity. The calibration curve was linear over the range of 100-2000 μg mL(-1). The relative standard deviations of intra-day and inter-day precision for migration time, peak area, corrected peak area, ratio of corrected peak area and ratio of peak area were less than 0.68, 3.48, 3.28, 2.97 and 2.83% and 2.01, 5.50, 4.46, 4.92 and 4.07%, respectively. The proposed method was successfully applied to the determinations of the analyte in tablet. Forced degradation studies were conducted by introducing a sample of sumatriptan succinate standard solution to different forced degradation conditions using neutral (water), basic (0.1 M NaOH), acidic (0.1 M HCl), oxidative (10% H(2)O(2)) and photolytic (exposure to UV light at 254 nm for 2 h). It is concluded that the stability-indicating method for sumatriptan succinate can be used for the analysis of the drug in various samples.

  12. 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.

  13. 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.

  14. Prednisolone succinate-glucosamine conjugate: Synthesis, characterization and in vitro cellular uptake by kidney cell lines

    Institute of Scientific and Technical Information of China (English)

    Yan Lin; Xun Sun; Tao Gong; Zhi Rong Zhang

    2012-01-01

    Prednisolone succinate-glucosamine (PSG) conjugate,a prodrug for prednisolone,was synthesized and confirmed by NMR and MS spectrum.The stabilities of the prodrug in PBS (pH 2.50,5.00,7.20,and 7.89) were studied.Cytotoxicity and uptake assay of the prodrug were perfomed on HK-2 and MDCK cell lines.The results showed that compared with prednisolone,the PSG not only did not increase the cytotoxicity but also improved the uptake to 2.2 times of prednisolone by the cells.Thus,it indicated that glucosamine might be a potential carrier for kidney-targeting delivery of prednisolone.

  15. Studies on synthesis, growth, structural, optical properties of organic 8-hydroxyquinolinium succinate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Thirumurugan, R., E-mail: singlecrystalxrd@gmail.com; Anitha, K., E-mail: singlecrystalxrd@gmail.com [School of Physics, Madurai Kamaraj University, Madurai-625021 (India)

    2014-04-24

    8-hydroxyquinolinium succinate (8HQSU), an organic material has been synthesized and single crystals were grown by employing the technique of slow evaporation. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction analysis. 8HQSU crystal belongs to the monoclinic crystallographic system with non-centro symmetric space group of P2{sub 1}. FT-IR spectral investigation has been carried out to identify the various functional groups present in the grown crystal. UV–vis spectral studies reveal that 8HQSU crystals are transparent in the entire visible region and the cut-off wavelength has been found to be 220nm.

  16. 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.

  17. 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...

  18. 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.

  19. 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 ...

  20. Large organized surface domains self-assembled from nonpolar amphiphiles.

    Science.gov (United States)

    Krafft, Marie Pierre

    2012-04-17

    For years, researchers had presumed that Langmuir monolayers of small C(n)F(2n+1)C(m)H(2m+1) (FnHm) diblock molecules (such as F8H16) consisted of continuous, featureless films. Recently we have discovered that they instead form ordered arrays of unusually large (~30-60 nm), discrete self-assembled surface domains or hemimicelles both at the surface of water and on solid substrates. These surface micelles differ in several essential ways from all previously reported or predicted molecular surface aggregates. They self-assemble spontaneously, even at zero surface pressure, depending solely on a critical surface concentration. They are very large (~100 times the length of the diblock) and involve thousands of molecules (orders of magnitude more than classical micelles). At the same time, the surface micelles are highly monodisperse and self-organize in close-packed hexagonal patterns (two-dimensional crystals). Their size is essentially independent from pressure, and they do not coalesce and are unexpectedly sturdy for soft matter (persisting even beyond surface film collapse). We and other researchers have observed large surface micelles for numerous diblocks, using Langmuir-Blodgett (LB) transfer, spin-coating and dip-coating techniques, or expulsion from mixed monolayers, and on diverse supports, establishing that hemimicelle formation and ordering are intrinsic properties of (perfluoroalkyl)alkanes. Notably, they involve "incomplete" surfactants with limited amphiphilic character, which further illustrates the outstanding capacity for perfluoroalkyl chains to promote self-assembly and interfacial film structuring. Using X-ray reflectivity, we determined a perfluoroalkyl-chain-up orientation. Theoretical investigations assigned self-assembly and hemimicelle stability to electrostatic dipole-dipole interactions at the interface between Fn- and Hm-sublayers. Grazing-incidence small-angle X-ray scattering (GISAXS) data collected directly on the surface of water

  1. 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.

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

    Science.gov (United States)

    Hybertson, Brooks M

    2007-05-01

    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 supercritical carbon dioxide ranged from mole fractions of 0.28 × 10(-5) at 15.0 MPa and 50 °C to 2.56 × 10(-5) at 30.0 MPa and 50 °C.

  3. Uptake of vitamin E succinate by the skin, conversion to free vitamin E, and transport to internal organs.

    Science.gov (United States)

    Trevithick, J R; Mitton, K P

    1999-03-01

    The percent solubility at 34 degrees C (skin temperature) of radioactive tocopherol succinate was determined for a number of edible oils, and a semisynthetic oil, Myritol 318 (Henkel, Kankakee, IL, a medium chain triglyceride prepared from fractionated coconut oil). Its solubility in Myritol 318 was approximately 50% better than any of the other oils. 14C-tocopherol succinate was diluted (1) into pure Myritol 318, a cosmetic base or (2) 50% tocopherol succinate in Myritol 318. These preparations were applied topically to a 2 cm diameter circle of the back saddle skin of a hairless mouse (strain skh-1). After 24 hr, up to 65% of the label was absorbed by the skin and was also found in skin removed from areas of the back other than the application area, and internal organs such as liver and heart. Up to 6% was hydrolysed to free tocopherol. Topical treatment may be an alternative to oral administration in gastrointestinal malabsorption diseases.

  4. 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.

  5. Vortex flux pinning mechanism and enhancement of in-field Jc in succinic acid doped MgB2

    Science.gov (United States)

    Ghorbani, S. R.; Darini, M.; Wang, X. L.; Hossain, M. S. A.; Dou, S. X.

    2013-08-01

    The field dependence of the resistivity and the critical current density, Jc(B), of MgB2 doped with 10 wt% wet and dry succinic acid have been investigated by magnetic measurements. The dry succinic acid significantly enhanced the upper critical field, the irreversibility field, and the Jc(B) compared to the wet succinic acid doped MgB2 and the pure MgB2. The field dependence of Jc(B) was analyzed within the collective pinning model. The observed temperature dependence of the crossover field, Bsb(T), from the single vortex to the small vortex bundle pinning regime shows that flux pinning arising from variation in the critical temperature, δTc, is the dominant mechanism for the wet sample over the whole studied temperature range, while there is a competition between δTc pinning and the pinning from variation in the mean free path, δl, for the dry sample.

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

    Directory of Open Access Journals (Sweden)

    J. Vanhanen

    2008-08-01

    Full Text Available 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 concentration. Surface tensions of both binary solutions agreed well with the previous measurements. Succinic acid was found to lower the surface tension even if sodium chloride is present, indicating that succinic acid, as a surface active compound, tends to concentrate to the surface. An equation based on thermodynamical relations was fitted to the data and extrapolated to the whole concentration range by using estimated surface tensions for pure compounds. As a result, we obtained an estimate of surface tensions beyond solubility limits in addition to a fit to the experimental data. The parameterization can safely be used at temperatures from 10 to 30°C. These kinds of parameterizations are important for example in atmospheric nucleation models. To investigate the influence of surface tension on cloud droplet activation, the surface tension parameterization was included in an adiabatic air parcel model. Usually in cloud models the surface tension of pure water is used. Simulations were done for characteristic marine aerosol size distributions consisting of the considered ternary mixture. We found that by using the surface tension of pure water, the amount of activated particles is underestimated up to 8% if particles contain succinic acid and overestimated it up to 8% if particles contain only sodium chloride. The surface tension effect was found to increase with increasing updraft velocity.

  7. Microbial production of succinic acid using crude and purified glycerol from a Crotalaria juncea based biorefinery

    Directory of Open Access Journals (Sweden)

    Suvra Sadhukhan

    2016-06-01

    Full Text Available Microbial conversion of crude and purified glycerol obtained in the process of biorefining Crotalaria juncea is carried out to produce succinic acid using Escherichia coli. Batch tests are performed for nine different substrate concentrations of commercial, purified and crude glycerol, in order to observe cell growth and substrate utilization rate. Inhibitory (Halden-Andrew, Aiba-Edward, Tessier type and Andrews as well as non-inhibitory (Monod, Moser and Tessier models are fitted to the relationship between specific growth rate and substrate concentration obtained from the growth curves. Considering the inhibition effect, Aiba-Edward model ranked 1 out of 7 in case of two samples and Haldane-Andrew model ranked 1 in case of one sample. Aiba-Edward model gave the best fitment for a large range of concentrations of all the three types of glycerol, crude, purified and laboratory grade. Maximum production of succinic acid is obtained from commercial glycerol at pH 7 and 37.5 °C.

  8. Succinate Functionalization of Hyperbranched Polyglycerol-Coated Magnetic Nanoparticles as a Draw Solute During Forward Osmosis.

    Science.gov (United States)

    Yang, Hee-Man; Choi, Hye Min; Jang, Sung-Chan; Han, Myeong Jin; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo

    2015-10-01

    Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPG-MNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes.

  9. 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.

  10. 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.

  11. MW Spectroscopy Coupled with Ultrafast UV Laser Vaporization: Succinic Acid in the Gas Phase

    Science.gov (United States)

    Mendez, Estibaliz; Ecija, Patricia; Cocinero, Emilio J.; Castano, Fernando; Basterretxea, Francisco J.; Godfrey, Peter D.; McNaughton, Don; Jahn, Michaela K.; Nair, K. P. Rajappan; Grabow, Jens-Uwe

    2013-06-01

    Recent lab and field measurements have indicated critical roles of organic acids in enhancing new atmospheric aerosol formation. In order to understand the nucleation process, here we report an experimental and theoretical investigation of chemical structure of succinic acid. We have used the technique of Fourier Transform Microwave Spectroscopy (FTMW). Succinic acid was vaporized by UV ultrafast laser ablation to suppress thermal decomposition processes^a and seeded into an expanding stream of Ne forming a supersonic jet. The rotational spectrum detected the presence of a single most stable conformation in the cm- mm- wave regions for which accurate rotational and centrifugal distortion parameters have been determined. The study was extended to all monosubstituted isotopic species (^{13}C, ^{18}O, D(O)), which were positively identified, leading to an accurate determination of the effective and substitution structures of the molecule. The experimental study was supplemented by ab initio (MP2) and DFT (M06-2X and B3LYP) calculations. ^{a} E. J. Cocinero, A. Lesarri, P. écija, F. J. Basterretxea, J. U. Grabow, J. A. Fernández and F. Castaño, Angew. Chem. Int. Ed., 51, 3119-3124, 2012.

  12. Hypromellose succinate-crosslinked chitosan hydrogel films for potential wound dressing.

    Science.gov (United States)

    Jiang, Qiong; Zhou, Wei; Wang, Jun; Tang, Rupei; Zhang, Di; Wang, Xin

    2016-10-01

    The objective of this study was to develop novel hydrogel films based on carboxyl-modified hypromellose-crosslinked chitosan for potential wound dressing. Hypromellose (HPMC) was grafted with succinic acid to yield hypromellose succinate (HPMCS), and then the reinforced hydrogel films of HPMCS-crosslinked chitosan (HPMCS-CS) were prepared through amide bond formation using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N- hydroxysuccinimide (NHS) as a catalyst. Compared to that of blend film, mechanical properties of HPMCS-CS hydrogel films were significantly enhanced both in dry and swollen state. To assess the applicability of HPMCS-CS hydrogel films as wound dressing, the swelling behavior, water vapor transmission rate (WVTR), oxygen permeability, biocompatibility (cytotoxicity and hemolysis), in vitro drug release and bactericidal properties were analyzed. The results indicated that HPMCS-CS hydrogel films with good biocompatibility possess high swelling ratio, proper WVTR, and oxygen permeability, which might accelerate tissue regeneration. Meanwhile, gentamycin sulfate release from drug-loaded HPMCS-CS hydrogel films were sustained, which would help to protect wound from infection. PMID:27222285

  13. 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.

  14. 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.

  15. 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

  16. 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...

  17. Valorization of macroalga Saccharina latissima as novel feedstock for fermentation-based succinic acid production in a biorefinery approach and economic aspects

    DEFF Research Database (Denmark)

    Silva Marinho, Goncalo; Alvarado-Morales, Merlin; Angelidaki, Irini

    2016-01-01

    This study aimed to evaluate the potential of the macroalga Saccharina latissima as feedstock for fermentation-based succinic acid production in a biorefinery approach. Seasonal variations in the content of carbohydrates, and fermentable sugars, had a significant impact on the succinic acid yield...

  18. Adsorption of phthalic acid esters (PAEs) by amphiphilic polypropylene nonwoven from aqueous solution: the study of hydrophilic and hydrophobic microdomain.

    Science.gov (United States)

    Zhou, Xiangyu; Wei, Junfu; Zhang, Huan; Liu, Kai; Wang, Han

    2014-05-30

    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.

  19. 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.

  20. 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...

  1. 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.

  2. 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.

  3. Kinetic analysis of bifidobacterial metabolism reveals a minor role for succinic acid in the regeneration of NAD+ through its growth-associated production.

    Science.gov (United States)

    Van der Meulen, Roel; Adriany, Tom; Verbrugghe, Kristof; De Vuyst, Luc

    2006-08-01

    Several strains belonging to the genus Bifidobacterium were tested to determine their abilities to produce succinic acid. Bifidobacterium longum strain BB536 and Bifidobacterium animalis subsp. lactis strain Bb 12 were kinetically analyzed in detail using in vitro fermentations to obtain more insight into the metabolism and production of succinic acid by bifidobacteria. Changes in end product formation in strains of Bifidobacterium could be related to the specific rate of sugar consumption. When the specific sugar consumption rate increased, relatively more lactic acid and less acetic acid, formic acid, and ethanol were produced, and vice versa. All Bifidobacterium strains tested produced small amounts of succinic acid; the concentrations were not more than a few millimolar. Succinic acid production was found to be associated with growth and stopped when the energy source was depleted. The production of succinic acid contributed to regeneration of a small part of the NAD+, in addition to the regeneration through the production of lactic acid and ethanol.

  4. 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

  5. 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.

  6. 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

  7. Terpene and dextran renewable resources for the synthesis of amphiphilic biopolymers.

    Science.gov (United States)

    Alvès, Marie-Hélène; Sfeir, Huda; Tranchant, Jean-François; Gombart, Emilie; Sagorin, Gilles; Caillol, Sylvain; Billon, Laurent; Save, Maud

    2014-01-13

    The present work shows the synthesis of amphiphilic polymers based on the hydrophilic dextran and the hydrophobic terpenes as renewable resources. The first step concerns the synthesis of functional terpene molecules by thiol-ene addition chemistry involving amino or carboxylic acid thiols and dihydromyrcenol terpene. The terpene-modified polysaccharides were subsequently synthesized by coupling the functional terpenes with dextran. A reductive amination step produced terpene end-modified dextran with 94% of functionalization, while the esterification step produced three terpene-grafted dextrans with a number of terpene units per dextran of 1, 5, and 10. The amphiphilic renewable grafted polymers were tested as emulsifiers for the stabilization of liquid miniemulsion of terpene droplets dispersed in an aqueous phase. The average hydrodynamic diameter of the stable droplets was observed at about 330 nm.

  8. 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...... of the 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...

  9. Sustained release of protein from poly(ethylene glycol) incorporated amphiphilic comb like polymers.

    Science.gov (United States)

    Srividhya, M; Preethi, S; Gnanamani, A; Reddy, B S R

    2006-12-01

    Amphiphilic comb like macromonomer containing hydrophilic poly(ethylene glycol) groups covalently linked to poly(hydromethyl siloxane) (PHMS) were prepared by hydrosilylation reaction. The epoxy reacting sites were introduced to this amphiphilic system by the reaction with allyl epoxy propyl ether (AEPE). Bovine serum albumin (BSA), a model protein drug was loaded to the PEG-PDMS system and very thin membranes were made from this macromonomer adopting solution casting technique. The in vitro protein release studies at various pH conditions showed a controlled release profile without exhibiting any initial burst. The control of the initial burst might be due to the strong linkages of the protein with the membrane and the aggregation of the protein at the surface. The morphology of the membrane before and after the protein release, and the mechanical strength were evaluated. The surface properties of the membrane were studied using the contact angle measurements. PMID:16930885

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. New synthetic amphiphilic polymers for steric protection of liposomes in vivo.

    Science.gov (United States)

    Torchilin, V P; Trubetskoy, V S; Whiteman, K R; Caliceti, P; Ferruti, P; Veronese, F M

    1995-09-01

    Carboxy group-terminated synthetic polymers--branched poly(ethylene glycol), poly(acryloylmorpholine), and poly(vinylpyrrolidone)--were made amphiphilic by derivatization with phosphatidyl ethanolamine via the terminal carboxy group and then incorporated into lecithin-cholesterol liposomes prepared by the detergent dialysis method. Following the biodistribution of liposomes in mice, all three polymers were shown to be effective steric protectors for liposomes and were able to sharply increase liposome circulation times in a concentration-dependent manner. The accumulation of liposomes in the liver decreases. The effects observed are similar to those found for liposomes modified with linear poly(ethylene glycol). At low polymer concentration, amphiphilic branched poly(ethylene glycol) seems to be the most effective liposome protector, most probably, because at the same molar content of anchoring groups, each attachment point carries two polymeric chains and doubles the quantity of liposome-grafted polymer comparing to linear poly(ethylene glycol).

  18. 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.)

  19. 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...

  20. Amphiphilic Cellulose Ethers Designed for Amorphous Solid Dispersion via Olefin Cross-Metathesis.

    Science.gov (United States)

    Dong, Yifan; Mosquera-Giraldo, Laura I; Taylor, Lynne S; Edgar, Kevin J

    2016-02-01

    The design of cellulose ether-based amphiphiles has been difficult and limited because of the harsh conditions typically required for appending ether moieties to cellulose. Olefin cross-metathesis recently has been shown to be a valuable approach for appending a variety of functional groups to cellulose ethers and esters, provided that an olefin handle for metathesis can be attached. This synthetic pathway gives access to these functional derivatives under very mild conditions and at high efficiency. Modification of ethyl cellulose by metathesis to prepare useful derivatives, for example, for solubility and bioavailability enhancement of drugs by amorphous solid dispersion (ASD), has been limited by the low DS(OH) of commercial ethyl cellulose derivatives. This is problematic because ethyl cellulose is otherwise a very attractive substrate for synthesis of amphiphilic derivatives by olefin metathesis. Herein we explore two methods for opening up this design space for ether-based amphiphiles, for example, permitting synthesis of more hydrophilic derivatives. One approach is to start with the more hydrophilic commercial methyl cellulose, which contains much higher DS(OH) and therefore is better suited for introduction of high DS of olefin metathesis "handles". In another approach, we explored a homogeneous one-pot synthesis methodology from cellulose, where controlled DS of ethyl groups was introduced at the same time as the ω-unsaturated alkyl groups, thereby permitting complete control of DS(OH), DS(Et), and ultimately DS of the functional group added by metathesis. We describe the functionalized derivatives available by these successful approaches. In addition, we explore new methods for reduction of the unsaturation in initial metathesis products to provide robust methods for enhancing product stability against further radical-catalyzed reactions. We demonstrate initial evidence that the products show strong promise as amphiphilic matrix polymers for amorphous

  1. 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...

  2. 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

  3. 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...

  4. 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...

  5. Amphiphilic Cellulose Ethers Designed for Amorphous Solid Dispersion via Olefin Cross-Metathesis.

    Science.gov (United States)

    Dong, Yifan; Mosquera-Giraldo, Laura I; Taylor, Lynne S; Edgar, Kevin J

    2016-02-01

    The design of cellulose ether-based amphiphiles has been difficult and limited because of the harsh conditions typically required for appending ether moieties to cellulose. Olefin cross-metathesis recently has been shown to be a valuable approach for appending a variety of functional groups to cellulose ethers and esters, provided that an olefin handle for metathesis can be attached. This synthetic pathway gives access to these functional derivatives under very mild conditions and at high efficiency. Modification of ethyl cellulose by metathesis to prepare useful derivatives, for example, for solubility and bioavailability enhancement of drugs by amorphous solid dispersion (ASD), has been limited by the low DS(OH) of commercial ethyl cellulose derivatives. This is problematic because ethyl cellulose is otherwise a very attractive substrate for synthesis of amphiphilic derivatives by olefin metathesis. Herein we explore two methods for opening up this design space for ether-based amphiphiles, for example, permitting synthesis of more hydrophilic derivatives. One approach is to start with the more hydrophilic commercial methyl cellulose, which contains much higher DS(OH) and therefore is better suited for introduction of high DS of olefin metathesis "handles". In another approach, we explored a homogeneous one-pot synthesis methodology from cellulose, where controlled DS of ethyl groups was introduced at the same time as the ω-unsaturated alkyl groups, thereby permitting complete control of DS(OH), DS(Et), and ultimately DS of the functional group added by metathesis. We describe the functionalized derivatives available by these successful approaches. In addition, we explore new methods for reduction of the unsaturation in initial metathesis products to provide robust methods for enhancing product stability against further radical-catalyzed reactions. We demonstrate initial evidence that the products show strong promise as amphiphilic matrix polymers for amorphous

  6. Langmuir-Blodgett Films and Calcium Ion Coordination of Biliverdin and Its Amphiphilic Derivatives

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Monolayer formation and LB film fabrication of amphiphilic derivative of biliverdin 1,diododecyl biliverdinamide [B(CONHC12H25)2,2] at an air-water interface on pure water subphase and subphase containing calcium ion were investigated and compared with 1.The coordination in ordered molecular films is much different from that in bulk solution.The formation of ligand-calcium complex was confirmed by X-ray photoelectron spectroscopy.

  7. 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...

  8. 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...

  9. 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 ...

  10. 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;

    2014-01-01

    reversible addition–fragmentation chain transfer (RAFT) polymerization, copper-mediated atom transfer radical polymerization (ATRP), and a selective deprotection reaction. Initially, multifunctional ATRP macroinitiators based on PHEMA backbone are prepared by RAFT polymerization. Then ATRP......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...

  11. 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-...

  12. 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 ...

  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 amp...... network. References 1 Cape, J., et al. (2011) Chem. Sci., 2 (4), 661-667. 2 Maurer, S. E., et al. (2009) Astrobiology, 9, 979-987. 3 Caschera, F., et al. Langmuir, In press....

  14. 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...

  15. Elisapterosin F: a polycyclic gorgonian-derived diterpene with a facially amphiphilic structure

    Science.gov (United States)

    Rodríguez, Ileana I.; Rodríguez, Abimael D.

    2009-01-01

    Analysis of the terpene metabolites of Pseudopterogorgia elisabethae collected in San Andrés island, Colombia has resulted in the discovery of a novel metabolite, elisapterosin F (1). The tangled molecular structure of 1, which was elucidated after extensive spectroscopic data interpretation, possesses hydrophilic and hydrophobic groups located on two opposite faces, rather than at two ends as in the more conventional head/tail amphiphiles. PMID:20161151

  16. 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...

  17. 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.

  18. 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.

  19. Influence of salicylic and succinic acids on antioxidant enzymes activity, heat resistance and productivity of Panicum miliaceum L.

    Directory of Open Access Journals (Sweden)

    Miroshnichenko N.N.

    2011-05-01

    Full Text Available The influence of treatment of millet (Panicum miliaceum L. seeds with the solutions of salicylic and succinic acids on the heat resistance of plantlets and activity of antioxidant enzymes – superoxide dismutase (SOD, catalase and peroxidase – in them have been investigated. In the micro-field experiment the influence of these acids on the millet yield was estimated. The action of salicylic (10 μM and succinic (1 mM acids caused the increase of plantlets resistance to the damaging heating that expressed in the rise of relative quantity of survived plantlets in 5 days after heating at the temperature of 47°С and in the reduced content of lipid peroxidation product malonic dialdehyde during the poststress period. The increase of activity of SOD, catalase and peroxidase took place in millet plantlets under the influence of salicylic and succinic acids. The increase of productivity of millet grain under the action of salicylic and succinic acids on 13,3-52,0 and 6,4-38,8% respectively depending on weather conditions in the field experiments was noted.

  20. A novel mutation in the succinate dehydrogenase subunit D gene in siblings with the hereditary paraganglioma-pheochromocytoma syndrome.

    Science.gov (United States)

    Prasad, Chaithra; Oakley, Gerard J; Yip, Linwah; Coyne, Christopher; Rangaswamy, Balasubramanya; Dixit, Sanjay B

    2014-01-01

    Germline mutations in the succinate dehydrogenase complex subunit D gene are now known to be associated with hereditary paraganglioma-pheochromocytoma syndromes. Since the initial succinate dehydrogenase complex subunit D gene mutation was identified about a decade ago, more than 131 unique variants have been reported. We report the case of two siblings presenting with multiple paragangliomas and pheochromocytomas; they were both found to carry a mutation in the succinate dehydrogenase complex subunit D gene involving a substitution of thymine to guanine at nucleotide 236 in exon 3. This particular mutation of the succinate dehydrogenase complex subunit D gene has only been reported in one previous patient in Japan; this is, therefore, the first report of this pathogenic mutation in siblings and the first report of this mutation in North America. With continued screening of more individuals, we will be able to create a robust mutation database that can help us understand disease patterns associated with particular variants and may be a starting point in the development of new therapies for familial paraganglioma syndromes.

  1. A novel mutation in the succinate dehydrogenase subunit D gene in siblings with the hereditary paraganglioma–pheochromocytoma syndrome

    Directory of Open Access Journals (Sweden)

    Chaithra Prasad

    2014-10-01

    Full Text Available Germline mutations in the succinate dehydrogenase complex subunit D gene are now known to be associated with hereditary paraganglioma–pheochromocytoma syndromes. Since the initial succinate dehydrogenase complex subunit D gene mutation was identified about a decade ago, more than 131 unique variants have been reported. We report the case of two siblings presenting with multiple paragangliomas and pheochromocytomas; they were both found to carry a mutation in the succinate dehydrogenase complex subunit D gene involving a substitution of thymine to guanine at nucleotide 236 in exon 3. This particular mutation of the succinate dehydrogenase complex subunit D gene has only been reported in one previous patient in Japan; this is, therefore, the first report of this pathogenic mutation in siblings and the first report of this mutation in North America. With continued screening of more individuals, we will be able to create a robust mutation database that can help us understand disease patterns associated with particular variants and may be a starting point in the development of new therapies for familial paraganglioma syndromes.

  2. A novel mutation in the succinate dehydrogenase subunit D gene in siblings with the hereditary paraganglioma–pheochromocytoma syndrome

    Science.gov (United States)

    Oakley, Gerard J; Yip, Linwah; Coyne, Christopher; Rangaswamy, Balasubramanya; Dixit, Sanjay B

    2014-01-01

    Germline mutations in the succinate dehydrogenase complex subunit D gene are now known to be associated with hereditary paraganglioma–pheochromocytoma syndromes. Since the initial succinate dehydrogenase complex subunit D gene mutation was identified about a decade ago, more than 131 unique variants have been reported. We report the case of two siblings presenting with multiple paragangliomas and pheochromocytomas; they were both found to carry a mutation in the succinate dehydrogenase complex subunit D gene involving a substitution of thymine to guanine at nucleotide 236 in exon 3. This particular mutation of the succinate dehydrogenase complex subunit D gene has only been reported in one previous patient in Japan; this is, therefore, the first report of this pathogenic mutation in siblings and the first report of this mutation in North America. With continued screening of more individuals, we will be able to create a robust mutation database that can help us understand disease patterns associated with particular variants and may be a starting point in the development of new therapies for familial paraganglioma syndromes. PMID:27489656

  3. 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......-succinic acid using the bacterial strain Actinobacillus succinogenes 130Z, and simultaneously producing high purity CH4 (>95%). Results showed that when pressure during fermentation was increased from 101.325 to 140 kPa, higher CO2 solubility was achieved, thereby positively affecting final succinic acid yield...... and titre, CO2 consumption rate and CH4 purity. When using biogas as the only CO2 source at 140 kPa, the CO2 consumption rate corresponded to 2.59 L CO2 L-1 d-1 with a final succinic acid titre of 14.4 g L-1. Under this pressure condition the highest succinic acid yield and biogas quality reached...

  4. Experimental and quantum-chemical studies of the reactions of 6-methyluracil with succinic and fumaric acids

    Science.gov (United States)

    Terent'ev, A. O.; Borisova, N. S.; Khamitov, E. M.; Zimin, Yu. S.; Mustafin, A. G.

    2014-12-01

    Possible structures of 6-methyluracil complexes with succinic and fumaric acids are studied by quantum-chemical means. The possibility of complex formation occurring between 6-methyluracil and the acids in the ionized and nonionized states is evaluated. The form of the complexes containing the nonionized acid is found to dominate. The quantum-chemical calculation data are consistent with the experimental results.

  5. 双极膜电渗析制备琥珀酸%Production of succinic acid using bipolar membrane electrodialysis

    Institute of Scientific and Technical Information of China (English)

    范爱勇; 高学理; 付丽丽; 杨洋; 高从堦

    2013-01-01

    采用三室型双极膜电渗析从琥珀酸钠制备琥珀酸,考察了电流大小对电渗析过程中操作电压、琥珀酸浓度、电流效率和能耗等技术指标的影响.在2.0A的最佳操作电流下,对1L浓度为0.5 mol/L的琥珀酸钠进行处理.实验结果表明:产生的琥珀酸质量浓度可达52.55 g/L,平均能耗为3.24 kW.h/kg,电流效率可达88%.%Succinic acid is recovered from sodium succimte solution using bipolar membrane electrodialysis with three compartments.The influence of current for operating voltage,current efficiency,energy consumption and yield concentration of succinic acid are studied.The results showed that the yield concentration of succinic acid could exceed 52.55 g/L,the electric energy consumption is about 3.24 kWh/kg and the current efficiency is about 88% under the optimum operation current of 2.0 A for 1 L 0.5 mol/L sodium succinate solutions.

  6. Linear and cyclic ester Oligomers of succinic acid and 1,4-butanediol: Biocatalytic synthesis and characterization

    NARCIS (Netherlands)

    Habeych Narvaez, D.I.; Eggink, G.; Boeriu, C.G.

    2011-01-01

    The lipase-catalyzed synthesis of cyclic ester oligomers from non-activated succinic acid (A) and 1,4-butanediol (B) in the presence of immobilized Candida antarctica lipase B was investigated. Batch and pulse fed-batch systems were implemented to increase the formation of cyclic ester products. The

  7. 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.

  8. 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.

  9. 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

  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. 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

  12. 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

  13. 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.

  14. CONTROLLED SYNTHESIS OF AMPHIPHILIC BLOCK POLYMERS HAVING GLUCOSE RESIDUES AND THEIR STRUCTURE FORMATION

    Institute of Scientific and Technical Information of China (English)

    Takeaki Miyamoto; Masahiko Minoda; Yoshinobu Tsujii

    1999-01-01

    Vinyl ether (VE)-based amphiphilic block copolymers with D-glucose residues as hydrophilic pendants were synthesized by CH3CH(OiBu)Cl/ZnI2-initiated sequential living cationic copolymerization of 3-O-(vinyloxy)ethyl-1, 2:5, 6-di-O-isopropylidene-D-glucofuranose (IGVE) and isobutyl VE (IBVE) and subsequent deprotection. The precursor block copolymers had a narrow molecular weight distribution(Mw/Mn~1.1) and a controlled segmental composition. The solubility characteristics of the amphiphilic copolymer depended strongly on composition. Their solvent-cast thin films were examined, under a transmission electron microscope, and could be seen to exhibit various microphase-separated surface morphologies such as spheres, cylinders, and lamellae, depending on composition. The amphiphilic copolymers with the appropriate segmental composition were found to form a stable monolayer at the airwater interface, which was successfully transferred onto a substrate by the Langmuir-Blodgett (LB)technique. The layered structure of the built-up LB films was controlled by blending the homopolymer.

  15. 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

  16. 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.

  17. 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).

  18. Unsuspected task for an old team: succinate, fumarate and other Krebs cycle acids in metabolic remodeling.

    Science.gov (United States)

    Bénit, Paule; Letouzé, Eric; Rak, Malgorzata; Aubry, Laetitia; Burnichon, Nelly; Favier, Judith; Gimenez-Roqueplo, Anne-Paule; Rustin, Pierre

    2014-08-01

    Seventy years from the formalization of the Krebs cycle as the central metabolic turntable sustaining the cell respiratory process, key functions of several of its intermediates, especially succinate and fumarate, have been recently uncovered. The presumably immutable organization of the cycle has been challenged by a number of observations, and the variable subcellular location of a number of its constitutive protein components is now well recognized, although yet unexplained. Nonetheless, the most striking observations have been made in the recent period while investigating human diseases, especially a set of specific cancers, revealing the crucial role of Krebs cycle intermediates as factors affecting genes methylation and thus cell remodeling. We review here the recent advances and persisting incognita about the role of Krebs cycle acids in diverse aspects of cellular life and human pathology.

  19. 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)

  20. 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.

  1. Poly(butylene succinate-co-butylene adipate)/cellulose nanocrystal composites modified with phthalic anhydride.

    Science.gov (United States)

    Zhang, Xuzhen; Zhang, Yong

    2015-12-10

    As a kind of biomass nanofiller for polymers, cellulose nanocrystal (CNC) has good mechanical properties and reinforcing capability. To improve the compatibility of poly(butylene succinate-co-butylene adipate) (PBSA)/CNC composites, phthalic anhydride was used as a compatilizer during melt mixing, leading to the significant improvement of the mechanical properties and thermal stability of the composites, which is related to the better dispersion of CNC in the composites. The addition of phthalic anhydride could accelerate the crystallization of PBSA component as evidenced by the curves of isothermal crystallization of the composites, but had little effect on the crystalline polymorphs of PBSA component. The addition of phthalic anhydride could strongly improve the hydrophobicity of the composites. The good mechanical properties, fast crystallization and improved hydrophobicity of PBSA/CNC composites with phthalic anhydride are favor to their practical commercial utilization.

  2. Spectral, linear and nonlinear optical, electrical, mechanical behaviour of sodium succinate crystal

    Science.gov (United States)

    Venkatesan, G.; Pari, S.; Kathiravan, V.

    2016-09-01

    This article reports on the preparation and characterization of sodium succinate grown by the slow solvent evaporation method. The grown crystal was subjected to single crystal x-ray diffraction technique to determine the lattice parameters. Fourier transform infrared spectrum was recorded to identify the presence of functional groups. Linear optical studies were determined in the percentage of transmittance and other optical parameters like optical band gap, reflectance and refractive index. The nonlinear refractive index, absorption and optical limiting was measured through the z-scan technique using Nd:YAG laser. Fluorescence study was measured. The impedance spectrum used to determine the dc conductivity at first time. Dielectric constant, dielectric loss and ac conductivity of the crystal were measured. The mechanical properties were measured in the crystal. The predicted NLO properties, UV–vis absorption and Z-scan studies indicate that is an attractive material for nonlinear optics and photonics optical limiting applications.

  3. 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.

  4. 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.

  5. Reaction and characterization of crosslinking hyperbranched poly(amine-ester) with succine anhydride

    Institute of Scientific and Technical Information of China (English)

    XIAO Ling; WEI Xiuzhen; ZHU Baoku

    2007-01-01

    Basing on hydroxyl terminated hyperbranched poly(amine-ester)s (HPAEs),the cross-linking reactions and preparation of ester-crosslinked HPAE films were investigated using succine anhydride (SA) as crosslink reagent.It was proved that the cross-linking reaction between HPAE and SA followed a two-step mechanism.This mechanism provides an efficient route to prepare HPAE/SA cross-linked films,in which,the precursor films were prepared by casting HPAE/SA solution at a lower temperature,and then curing the films at a higher temperature.By varying SA content,the solid HPAE/SA films with different cross-linking degrees were prepared successfully.The highest tensile strength of the cross-linked film could reach 59.60 MPa.With all water contact angle smaller than 74.3°,the crosslinked films demonstrated good hydrophilic properties.

  6. 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

  7. 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

  8. 4-Chloro-6-methoxypyrimidin-2-amine–succinic acid (2/1

    Directory of Open Access Journals (Sweden)

    Kaliyaperumal Thanigaimani

    2012-12-01

    Full Text Available The asymmetric unit of the title compound, 2C5H6ClN3O·C4H6O4, consists of one 4-chloro-6-methoxypyrimidin-2-amine molecule and one half-molecule of succinic acid which lies about an inversion centre. In the crystal, the acid and base molecules are linked through N—H...O and O—H...N hydrogen bonds, forming a tape along [1-10] in which R22(8 and R42(8 hydrogen-bond motifs are observed. The tapes are further interlinked through a pair of C—H...O hydrogen bonds into a sheet parallel to (11-2.

  9. Synthesis and Crystal Structure of 2-(N-Cyclohexyl)-imino-1,4-succinic Acid Dihydrate

    Institute of Scientific and Technical Information of China (English)

    郭金波; 李森兰; 郁兆莲; 陈庆华

    2005-01-01

    The title compound, 2-(N-cyclohexyl)-imino-1,4-succinic acid dihydrate 4, has been prepared and structurally determined by X-ray diffraction analysis. Crystal data: monoclinic, space group Cc, a = 7.5790(15), b = 24.860(5), c = 7.1394(14)(A), β = 104.23(3)°, V = 1303.9(4) (A)3, C10H21NO6, Mr = 251.28, Z = 4, Dc = 1.280 g/cm3, μ = 0.105 mm-1, F(000) = 544, R = 0.0397 and wR = 0.0918 for 1212 observed reflections with I ≥ 2σ(I). X-ray structure analysis reveals that there exist two intramolecular and six intermolecular hydrogen-bonding interactions in the crystal lattice, which can stabilize the configuration of the α-imino acid dihydrate 4.

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

    DEFF Research Database (Denmark)

    Gunnarsson, Ingólfur Bragi

    production mainly due to their high carbohydrate content. A case study of a proposed macroalgae biorefinery concept highlighted the potential of post hydrolysis solid residue (PHSR) for the production of numerous additional products such as ω-3 and ω-6 fatty acids, biodiesel, protein, feed, biogas......Biorefinery has the potential of displacing fossil fuels and oil-refinery based products. Within the biorefinery a palette of marketable commodities can be produced from biomass, including food, feed, biochemicals and biofuels. Which bioproducts are produced is largely dependent on the chemical....... The chemical composition of biomasses was determined in order to demonstrate their biorefinery potential. Bioethanol and biogas along with succinic acid production were the explored bioconversion routes, while potential production of other compounds was also investigated. Differences and changes in biomass...

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. Identification of succinic semialdehyde reductases from Geobacter: expression,purification, crystallization, preliminary functional, and crystallographic analysis

    Institute of Scientific and Technical Information of China (English)

    Yanfeng Zhang; Xiaoli Gao; Yi Zheng; R. Michae; Garavito

    2011-01-01

    Succinic semialdehyde reductase (SSAR) is an important enzyme involved in γ-aminobutyrate (GABA) metabolism.By converting succinic semialdehyde (SSA) to γ-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 coil 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+,and the resulting crystals diffracted to 1.89 (A) (GsSSAR) and 2.25 (A)(GmSSAR) resolution.The GsSSAR and GmSSAR crystals belong to the space groups P21221 (a =99.61 (A),b =147.49 (A),c =182.47 A) and P1 (a =75.97 (A) b =79.14 (A) c =95.47 (A),α =82.15°,β =88.80°,γ=87.66°),respectively.Preliminary crystallographic data analysis suggests the presence of eight protein monomers in the asymmetric units for both GsSSAR and GmSSAR.

  18. 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

  19. 离子色谱法测定丁二酸合成电解液中马来酸和丁二酸%IC Determination of Maleic Acid and Succinic Acid in Electrolyte from Synthesis of Succinic Acid

    Institute of Scientific and Technical Information of China (English)

    马淳安; 邱志军; 颜飞; 赵峰鸣; 徐颖华; 褚有群

    2013-01-01

    采用离子色谱法测定丁二酸合成电解液中原料马来酸和产物丁二酸的含量.试样经Ion Pac AG19保护柱及Ion Pac AS19分析柱分离,以25 mmol·L-1氢氧化钾溶液为淋洗液,采用抑制电导器检测.马来酸和丁二酸的质量浓度在1.0~10 mg·L-1范围内与峰面积与峰高均呈线性关系.方法可用于测定合成丁二酸生产过程的不同时段溶液(起始、结束和母液)中马来酸和丁二酸的含量,有助于实现丁二酸的连续式电解合成工艺路线.%Contents of maleic acid (the raw material) and succinic acid (the products) in electrolyte from synthesis of succinic acid were determined by ion chromatography. Ion Pac AG19 protective column and Ion Pac AS19 separation column were used for separation and 25 mmol · L-1 KOH solution was used as eluant. Inhibitory conductivity detection was adopted in the determinatioa Linear relationships between values of peak area or peak height and mass concentration of maleic acid and succinic acid were kept in the range of 1. 0—10 mg · L-1. The proposed method could be used in the determination of the 2 acids in the electrolyte at different time interval (at starting and ending of electrolysis) and in the mother liquid in the synthetic process. The data obtained were helpful for the realization of synthetic technology of the continuous electrolytic production of succinic acid.

  20. 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.

  1. 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...

  2. Synthesis of Dimethyl Succinate by Continuous Catalytic Distillation%连续催化精馏合成丁二酸二甲酯

    Institute of Scientific and Technical Information of China (English)

    霍稳周; 魏晓霞; 田丹; 李花伊; 刘野

    2013-01-01

    以丁二酸和甲醇为原料、自主开发的耐温阳离子交换树脂为催化剂,采用无催化剂连续预酯化和连续催化精馏组合工艺合成了丁二酸二甲酯.考察了丁二酸进料液态空速、原料配比、反应温度等因素对丁二酸转化率和产物选择性的影响,并考察了催化剂的稳定性.实验结果表明,耐温阳离子交换树脂催化剂的稳定性好,在反应温度为110 ℃、甲醇与丁二酸的摩尔比为9、丁二酸进料液态空速为0.7 h-1的条件下连续运转2000h,丁二酸的平均转化率为99.96%,丁二酸二甲酯的平均选择性为99.93%.FTIR表征结果显示,反应产物的FTIR谱图与丁二酸二甲酯的标准谱图基本一致.该工艺具有良好的工业应用前景%Dimethyl succinate was synthesized from succinic acid and methanol over a proprietary heat-resistant cation exchange resin catalyst in a combined process containing continuous catalystfree pre-esterification and continuous catalytic distillation.The influences of succinic acid LHSV,mole ratio of methanol to succinic acid and reaction temperature on the conversion of succinic acid and the selectivity to the product dimethyl succinate were investigated.The experimental results show that the stability of the heat-resistant resin catalyst is good.Under the conditions of 110 ℃,mole ratio of methanol to succinic acid 9 and LHSV of succinic acid 0.7 h-1,the conversion of succinic acid and the selectivity to dimethyl succinate reached 99.96% and 99.93% after running 2000 h respectively.The structure of the product dimethyl succinate was verified by means of FTIR.

  3. 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

  4. Micro- and nanophase separations in hierarchical self-assembly of strongly amphiphilic block copolymer-based ionic supramolecules

    DEFF Research Database (Denmark)

    Ayoubi, Mehran Asad; Zhu, Kaizheng; Nyström, Bo;

    2013-01-01

    block), a class of ionic supramolecules are successfully synthesized whose molecular architecture consists of a poly(styrene) PS block (Linear block) covalently connected to a strongly amphiphilic comb-like block (AmphComb block), i.e. Linear-b-AmphComb. In the melt state, these ionic supramolecules can......By a selective complexation between different alkyltrimethylammonium amphiphiles (C8, C12 and C16) and three different diblock copolymer systems of poly(styrene)-b-poly(methacrylic acid) at various grafting densities X (X = number of alkyl chains per acidic group of the poly(methacrylic acid) PMAA...... supramolecules, based on complexation between a homopolymer of PMAA and the various alkyltrimethylammonium amphiphiles, were prepared, which nanophase separated into S (C8) or C (C12 and C16) domains....

  5. 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.

  6. 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.

  7. 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

  8. A validity of the use of compositions on the basis of succinic acid in higher achievements sports.

    Directory of Open Access Journals (Sweden)

    Gunina L.М.

    2012-06-01

    Full Text Available A basic mechanism of influence on providing energy of muscular activity of succinic acid are analysed and the necessity of including in the complement of pharmacological facilities on her basis of other bioactive substances is reasonabled. In the 30 members of national team command of Ukraine on track-and-field at the level of cellular membranes at last 21 days a study of mechanisms of ergogenous action of dietary supplement "YantarIn-Sport" it was conducted and she's possesses a membranoprotective effect it was shown. In addition, a positive action of "YantarIn-Sport" on erythro- and leucopoiesis changes of bloods acid-base stat, as well as frequency of origin of sharp respiratory viral infections in sportsmen are well-proven. All of it is pre-conditions for including of facilities on the basis of succinic acid in the charts of the pharmacological providing of higher achievements sport.

  9. Identification of monomenthyl succinate, monomenthyl glutarate, and dimenthyl glutarate in nature by high performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Hiserodt, Richard D; Adedeji, Jide; John, T V; Dewis, Mark L

    2004-06-01

    Menthol, menthone, and other natural compounds provide a cooling effect and a minty flavor and have found wide application in chewing gum and oral care products. Monomenthyl succinate, monomenthyl glutarate, and dimenthyl glutarate provide a cooling effect without the burning sensation associated with menthol. Additionally, because they do not have a distinct flavor, they can be used in applications other than mint flavors. Because these menthyl esters have not been reported in nature, we undertook to identify a natural source for these cooling compounds. Using high performance liquid chromatography-tandem mass spectrometry, monomenthyl succinate was identified in Lycium barbarum and Mentha piperita, and monomenthyl glutarate and dimenthyl glutarate were identified in Litchi chinesis. The identifications were based on the correlation of mass spectrometric and chromatographic retention time data for the menthyl esters in the extracts with authentic standards which resulted in a 99.980% confidence in the identifications.

  10. 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.

  11. 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

    productivity of 0.50 g L− 1 h− 1. Removal of carbohydrates from the macroalgal biomass through enzymatic hydrolysis resulted in up-concentration of protein and lipid fractions in the post-hydrolysis solid residue (PHSR). Energy recovery of PHSR and fermentation broth through anaerobic digestion corresponded......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 overall...

  12. 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.

  13. 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.

  14. 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.

  15. Nonionic amphiphile nanoarchitectonics: self-assembly into micelles and lyotropic liquid crystals

    Science.gov (United States)

    Shrestha, Lok Kumar; Strzelczyk, Karolina Maria; Goswami Shrestha, Rekha; Ichikawa, Kotoko; Aramaki, Kenji; Hill, Jonathan P.; Ariga, Katsuhiko

    2015-05-01

    Amphiphiles, molecules that possess both hydrophilic and hydrophobic moieties, are architecturally simple molecules that can spontaneously self-assemble into complex hierarchical structures from lower to higher dimensions either in the bulk phase or at an interface. Recent developments in multifunctional nanostructure design using the advanced concept of nanoarchitectonics utilize this simple process of assembly. Amphiphilic self-assemblies involving lipids or proteins mimic the structure of biological systems, thus highlighting the necessity of a fundamental physical understanding of amphiphilic self-assembly towards a realization of the complex mechanisms operating in nature. Herein, we describe self-assembled microstructures of biocompatible and biodegradable tetraglycerol lauryl ether (C12G4) nonionic surfactant in an aqueous solvent system. Temperature-composition analyses of equilibrium phases identified by using small-angle x-ray scattering (SAXS) provide strong evidence of various spontaneously self-assembled mesostructures, such as normal micelles (Wm), hexagonal liquid crystal (H1), and reverse micelles (Om). In contrast to conventional poly(oxyethylene) nonionic surfactants, C12G4 did not exhibit the clouding phenomenon at higher temperatures (phase separation was not observed up to 100 °C), demonstrating the greater thermal stability of the self-assembled mesophases. Generalized indirect Fourier transformation (GIFT) evaluation of the SAXS data confirmed the formation of core-shell-type spherical micelles with a maximum dimension ca. 8.7 nm. The shape and size of the C12G4 micelles remained apparently unchanged over a wide range of concentrations (up to 20%), but intermicellar interactions increased and could be described by the Percus-Yevick (PY) theory (after Carnahan and Starling), which provides a very accurate analytical expression for the osmotic pressure of a monodisperse hard sphere.

  16. Effect of pH and succinic acid on the morphology of α-calcium sulfate hemihydrate synthesized by a salt solution method

    Science.gov (United States)

    Li, Fan; Liu, Jianli; Yang, Guangyong; Pan, Zongyou; Ni, Xiao; Xu, Huazi; Huang, Qing

    2013-07-01

    Well-crystallized α-calcium sulfate hemihydrate (α-CSH) powders useful for bone defect filling were synthesized using a salt solution method and their morphologies were effectively modified by adjusting the pH of the reaction solutions or by adding succinic acid. The effect and its mechanism of the pH and the succinic acid on the phase composition and the morphology of the crystals were discussed in detail.

  17. 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).

  18. 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

  19. 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.

  20. 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

  1. 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

  2. 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...

  3. 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

  4. 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...

  5. 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

  6. 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.

  7. 琥珀酸美托洛尔的合成分析%The Synthesis Analysis of Metoprolol Succinate

    Institute of Scientific and Technical Information of China (English)

    彭坤; 王京凯; 李晗

    2014-01-01

    Objective:To synthesize metoprolol succinate,and analyze the synthesize method.Method:Metoprolol succinate was synthesized from the 4-(2-methoxyethyl)phenol,etherification reaction of phenol with epichlorohydrin to 3-[4-(2-methoxy ethyl phenoxy)]-1,2-propylene oxide,ammonification reaction with isopropyl amine to metoprolol,and then reaction with succinic acid salt could be obtained by organic solvent.Result:The obtained Metoprolol succinate purity was over 99%,total yield was about 55%.Conclusion:This method is simple operation,mild conditions,environmental protection and efficient,the product of high purity,high yield,suitable for industrialization of green production.%目的:对琥珀酸美托洛尔进行合成,并对合成方法进行分析。方法:本文以对甲氧基乙基苯酚为起始物料,与环氧氯丙烷进行酚醚化反应得到3-[4-(2-甲氧基乙基苯氧基)]-1,2-环氧丙烷,与异丙胺进行氨化反应得到美托洛尔,再与琥珀酸在有机溶剂中成盐即可制得琥珀酸美托洛尔。结果:所得琥珀酸美托洛尔纯度在99%以上,总收率约55%。结论:本方法操作简便,条件温和,环保高效,所得产品纯度高、收率高,适合工业化绿色生产。

  8. 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...

  9. 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...

  10. 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

  11. 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

  12. The X-ray crystal structure of Escherichia coli succinic semialdehyde dehydrogenase; structural insights into NADP+/enzyme interactions.

    Directory of Open Access Journals (Sweden)

    Christopher G Langendorf

    Full Text Available BACKGROUND: In mammals succinic semialdehyde dehydrogenase (SSADH plays an essential role in the metabolism of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA to succinic acid (SA. Deficiency of SSADH in humans results in elevated levels of GABA and gamma-Hydroxybutyric acid (GHB, which leads to psychomotor retardation, muscular hypotonia, non-progressive ataxia and seizures. In Escherichia coli, two genetically distinct forms of SSADHs had been described that are essential for preventing accumulation of toxic levels of succinic semialdehyde (SSA in cells. METHODOLOGY/PRINCIPAL FINDINGS: Here we structurally characterise SSADH encoded by the E coli gabD gene by X-ray crystallographic studies and compare these data with the structure of human SSADH. In the E. coli SSADH structure, electron density for the complete NADP+ cofactor in the binding sites is clearly evident; these data in particular revealing how the nicotinamide ring of the cofactor is positioned in each active site. CONCLUSIONS/SIGNIFICANCE: Our structural data suggest that a deletion of three amino acids in E. coli SSADH permits this enzyme to use NADP+, whereas in contrast the human enzyme utilises NAD+. Furthermore, the structure of E. coli SSADH gives additional insight into human mutations that result in disease.

  13. 琥珀酸的生产技术及应用初探%Production and application of succinic acid

    Institute of Scientific and Technical Information of China (English)

    盛晓晓; 周如金; 邱松山

    2012-01-01

    Succinic acid is an organic acid that occurs naturally in amber, and can be produced by chemical synthesis or fermentation. Succinic acid is highly reactive and has many derivatives, which makes it being extensively used in chemical, medical and food industries as an important industrial organic chemical and intermediate. The chemical synthesis and fermentation production of succinic acid were discussed, as well as its current and future application.%琥珀酸是从琥珀中分离的天然有机酸,可通过化学合成或微生物发酵得到,本身具有良好的反应活性,衍生物众多,是一种重要的有机化工原料及中间体,目前广泛应用于化工、医药、食品等行业,本文分别探讨了琥珀酸的化学合成及生物发酵的方法,并对其应用现状和前景进行了展望.

  14. Succinic acid-based leaching system: A sustainable process for recovery of valuable metals from spent Li-ion batteries

    Science.gov (United States)

    Li, Li; Qu, Wenjie; Zhang, Xiaoxiao; Lu, Jun; Chen, Renjie; Wu, Feng; Amine, Khalil

    2015-05-01

    A hydrometallurgical method involving natural organic acid leaching has been developed for recovery of lithium and cobalt from the cathode active materials in spent lithium-ion batteries. Succinic acid is employed as leaching agent and H2O2 as reductant. The cobalt and lithium contents from the succinic acid-based treatment of spent batteries are determined by inductively coupled plasma-optical emission spectroscopy to calculate the leaching efficiency. The spent LiCoO2 samples after calcination and the residues after leaching are characterized by X-ray diffraction and scanning electron microscopy. The results show that nearly 100% of cobalt and more than 96% of lithium are leached under optimal conditions: succinic acid concentration of 1.5 mol L-1, H2O2 content of 4 vol.%, solid-to-liquid ratio of 15 g L-1, temperature of 70 °C, and reaction time of 40 min. Results are also given for fitting of the experimental data to acid leaching kinetic models.

  15. 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

  16. Research developments on amphiphilic hyperbranched polymers%两亲性超支化聚合物研究进展

    Institute of Scientific and Technical Information of China (English)

    强涛涛; 张国国; 王学川

    2013-01-01

    In this paper, the research progress in amphiphilic hyperbranched polymers is overviewed. Synthetic methods of amphiphilic hyperbranched polymers are introduced, which covers the modification of end groups of the hyperbranched polymers with long chain alkyl and polyethylene glycol, and the polymerization of vinyl derivatives through free radical polymerization or ring-opening polymerization, using hyperbranched polymers as macroinitiator. Different structures of amphiphilic hyperbranched polymers have their unique properties in solution, such as core-shell unimolecule micelles and different micellar conformation aggregates. Moreover, the application of amphiphilic hyperbranched polymers, such as drug delivery carrier, material modification, and the encapsulation of dye molecules is also introduced. Then, the development trend of amphiphilic hyperbranched polymers is proposed. The preparation of special properties of amphiphilic hyperbranched polymers and the application of amphiphilic hyperbranched polymers in biological medicine should be the main focus in the development of amphiphilic hyperbranched polymers.%介绍了两亲性超支化聚合物的合成方法,利用长链烷基和聚乙二醇对超支化聚合物端基接枝改性;或者对超支化聚合物改性引入活性位点,再利用其引发乙烯基单体,通过自由基聚合、开环聚合得到两亲性超支化聚合物.阐述了不同结构的两亲性超支化聚合物在溶液中的独特性质,如核壳型单分子胶束以及不同胶束形态的聚集体.详细介绍了两亲性超支化聚合物在药物输送载体、材料改性以及染料分子的封装等领域的应用现状,指出采用新的改性技术、聚合技术制备具有特殊性能的两亲性超支化聚合物以及探索其在生物医药领域的研究为今后的主要发展方向.

  17. 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.

  18. 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 anhydride...... analysis of the modified and native xylans showed a slight lowering of thermal stability with functionalization. Contact angle measurements on spin-coated surfaces of modified xylan films showed a significant increase in hydrophobicity with the introduction of the alkenyl-functionalized succinic anhydride...

  19. 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.

  20. 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.

  1. 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

  2. [Influence of salicylic and succinic acids on formation of active oxygen forms in wheat coleoptiles].

    Science.gov (United States)

    Kolupaiev, Iu Ie; Iastreb, T O; Shvidenko, M V; Karpets', Iu V

    2011-01-01

    The comparative study of influence of exogenous salicylic (SaA) and succinic (SuA) acids on the production of reactive oxygen species by isolated wheat coleoptiles has been provided. Under the action of both acids the increase of generation of superoxide anion-radical (O2(.-)) was observed. This increase was partially suppressed by treatment of coleoptiles with inhibitors of peroxidase (salicylhydroxamic acid) and NADP H-oxidase (imidazole and alpha-naphthol). The increase of hydrogen peroxide content, activity of peroxidase and superoxide dismutase (SOD) was registered under the influence of SaA and SuA; catalase activity did not change essentially. The treatment of coleoptiles with the indicated acids resulted in the increase of their resistance to abiotic stress (damaging heating, 43 +/- 0,1 degrees C, 10 min). The conclusion is made, that the increase of O2(.-) generation in wheat coleoptiles under the action of SaA and SuA is related, probably, to the increase of apoplast peroxidase and NADP.H-oxidase activity, and the rise of H2O2 content is related to the growth of SOD activity. These enzymatic systems are involved in the induction of plant cells protective reactions to the hyperthermia. PMID:22276431

  3. 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.

  4. 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.

    2015-08-01

    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 (ɛr = 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. A series of crystalline solids composed of aminopyridines and succinic, fumaric, and sebacic acids

    Science.gov (United States)

    Sandhu, Bhupinder; Fonari, Marina S.; Sawyer, Kayla; Timofeeva, Tatiana V.

    2013-11-01

    The cocrystallization of five mono- and diaminopyridines, namely 2-aminopyridine (2-AP), 2,3-diaminopyridine (2,3-DAP), 2,6-diaminopyridine (2,6-DAP), 4-aminopyridine (4-AP), and 3,4-diaminopyridine (3,4-DAP), with three dicarboxylic acids, namely, succinic (SUH2), fumaric (FUH2), and sebacic (SEH2) acids resulted in twelve organic salts including two hydrates, (2-HAP)2(SU)(SUH2) 1, (2,3-HDAP)2(SU) 2, (2,3-HDAP)2(SE) 3, (2,6-HDAP)2(FU) 4, (2,6-HDAP)2(SU) 5, (4-HAP)(SUH) 6, (4-HAP)2(FU) 7, (4-HAP)2(SE) 8, (3,4-HDAP)(SUH) 9, (3,4-HDAP)2(SE) 10, (4-HAP)2(FU)ṡ2H2O 11, (4-HAP)2(SU)ṡ2H2O 12. All compounds were characterized by single-crystal X-ray diffraction, IR spectra, and melting points. The proton transfer to the pyridine nitrogen in all compounds, and its location in carboxylic group in adducts with SUH2 (1, 6, and 9) were determined reliably from the low-temperature X-ray experiments. The impact of number and position of amino-groups in the pyridine molecules, as well as the conformational flexibility of the acids, and water inclusion on the final stoichiometries and supramolecular architectures is discussed.

  12. 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.

  13. 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.

  14. Efficacy of vigabatrin intervention in a mild phenotypic expression of succinic semialdehyde dehydrogenase deficiency.

    Science.gov (United States)

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

    2012-01-01

    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 the GHB levels in body fluids, a treatment with vigabatrin at low dose (25 mg/kg per day) was started, monitoring its efficacy by clinical and neurochemical follow-up. After 9 months of therapy with vigabatrin, a significant reduction of GHB concentrations in urine and CSF was observed; after 36 months, a significant improvement of communicative skills, not previously reported, was referred. These results support the hypothesis that the clinical improvement is correlated to the reduction in the GHB levels and the importance of considering the SSADH deficiency in the differential diagnosis of patients with mental retardation and language delay. PMID:23430864

  15. 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.

  16. 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.

  17. 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.

  18. Adsorption of poly(ethylene succinate) chain onto graphene nanosheets: A molecular simulation.

    Science.gov (United States)

    Kelich, Payam; Asadinezhad, Ahmad

    2016-09-01

    Understanding the interaction between single polymer chain and graphene nanosheets at local and global length scales is essential for it underlies the mesoscopic properties of polymer nanocomposites. A computational attempt was then performed using atomistic molecular dynamics simulation to gain physical insights into behavior of a model aliphatic polyester, poly(ethylene succinate), single chain near graphene nanosheets, where the effects of the polymer chain length, graphene functionalization, and temperature on conformational properties of the polymer were studied comparatively. Graphene functionalization was carried out through extending the parameters set of an all-atom force field. The results showed a significant conformational transition of the polymer chain from three-dimensional statistical coil, in initial state, to two-dimensional fold, in final state, during adsorption on graphene. The conformational order, overall shape, end-to-end separation statistics, and mobility of the polymer chain were found to be influenced by the graphene functionalization, temperature, and polymer chain length. Furthermore, the polymer chain dynamics mode during adsorption on graphene was observed to transit from normal diffusive to slow subdiffusive mode. The findings from this computational study could shed light on the physics of the early stages of aliphatic polyester chain organization induced by graphene. PMID:27560653

  19. 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.

  20. Succinate dehydrogenase gene mutations are strongly associated with paraganglioma of the organ of Zuckerkandl.

    Science.gov (United States)

    Lodish, Maya B; Adams, Karen T; Huynh, Thanh T; Prodanov, Tamara; Ling, Alex; Chen, Clara; Shusterman, Suzanne; Jimenez, Camilo; Merino, Maria; Hughes, Marybeth; Cradic, Kendall W; Milosevic, Dragana; Singh, Ravinder J; Stratakis, Constantine A; Pacak, Karel

    2010-09-01

    Organ of Zuckerkandl paragangliomas (PGLs) are rare neuroendocrine tumors that are derived from chromaffin cells located around the origin of the inferior mesenteric artery extending to the level of the aortic bifurcation. Mutations in the genes encoding succinate dehydrogenase subunits (SDH) B, C, and D (SDHx) have been associated with PGLs, but their contribution to PGLs of the organ of Zuckerkandl PGLs is not known. We aimed to describe the clinical presentation of patients with PGLs of the organ of Zuckerkandl and investigate the prevalence of SDHx mutations and other genetic defects among them. The clinical characteristics of 14 patients with PGL of the organ of Zuckerkandl were analyzed retrospectively; their DNA was tested for SDHx mutations and deletions. Eleven out of 14 (79%) patients with PGLs of the organ of Zuckerkandl were found to have mutations in the SDHB (9) or SDHD (2) genes; one patient was found to have the Carney-Stratakis syndrome (CSS), and his PGL was discovered during surgery for gastrointestinal stromal tumor. Our results show that SDHx mutations are prevalent in pediatric and adult PGLs of the organ of Zuckerkandl. Patients with PGLs of the organ of Zuckerkandl should be screened for SDHx mutations and the CSS; in addition, asymptomatic carriers of an SDHx mutation among the relatives of affected patients may benefit from tumor screening for early PGL detection.