International Journal of Molecular Sciences

256 KiB

Open AccessArticle

Asymmetric Glyoxylate-Ene Reactions Catalyzed by Chiral Pd(II) Complexes in the Ionic Liquid [bmim][PF₆]

by Xi Jun He, Zhen Lu Shen, Wei Min Mo, Bao Xiang Hu and Nan Sun

Int. J. Mol. Sci. 2007, 8(6), 553-563; https://doi.org/10.3390/i8060553 - 22 Jun 2007

Cited by 6 | Viewed by 9987

The room temperature ionic liquid [bmim][PF₆] was employed as the reactionmedium in the asymmetric glyoxylate-ene reaction of α-methyl styrene (4a) with ethylglyoxylate using chiral palladium(II) complexes as the catalysts. [Pd(S-BINAP)(3,5-CF₃-PhCN)₂](SbF₆)₂ (1b) showed the highest [...] Read more.

The room temperature ionic liquid [bmim][PF₆] was employed as the reactionmedium in the asymmetric glyoxylate-ene reaction of α-methyl styrene (4a) with ethylglyoxylate using chiral palladium(II) complexes as the catalysts. [Pd(S-BINAP)(3,5-CF₃-PhCN)₂](SbF₆)₂ (1b) showed the highest catalytic activity. Under the reaction conditionsof 40 oC, 0.5 h, and 1b/4a molar ratio of 0.05, ethyl α-hydroxy-4-phenyl-4-pentenoate wasobtained in excellent chemical yield (94 %) with high enantioselectivity (70 %). Otherα-hydroxy esters can also be obtained in high chemical yields and enantioselectitiesthrough the glyoxylate-ene reactions of alkenes with glyoxylates catalyzed by 1b in[bmim][PF₆]. Moreover, the ionic liquid [bmim][PF₆] which contained the palladium(II)complex could be recycled and reused several times without significant loss of the catalyticactivity. Full article

(This article belongs to the Special Issue Ionic Liquids)

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334 KiB

Open AccessArticle

Near Infrared Spectroscopy for On-line Monitoring of Alkali- Free Cloth /Phenolic Resin Prepreg During Manufacture

by Bo Jiang and Yu Dong Huang

Int. J. Mol. Sci. 2007, 8(6), 541-552; https://doi.org/10.3390/i8060541 - 19 Jun 2007

Cited by 16 | Viewed by 10488

Abstract

A NIR method was developed for the on-line monitoring of alkali-freecloth/phenolic resin prepreg during its manufacturing process. First, the sizing content ofthe alkali-free cloth was analyzed, and then the resin, soluble resin and volatiles content ofthe prepreg was analyzed simultaneously using the FT-NIR [...] Read more.

A NIR method was developed for the on-line monitoring of alkali-freecloth/phenolic resin prepreg during its manufacturing process. First, the sizing content ofthe alkali-free cloth was analyzed, and then the resin, soluble resin and volatiles content ofthe prepreg was analyzed simultaneously using the FT-NIR spectrometer. Partial leastsquare (PLS) regression was used to develop the calibration models, which for the sizingcontent was preprocessed by 1stDER MSC, for the volatile content by 1stDER VN, forthe soluble resin content by 1stDER MSC and for the resin content by the VN spectraldata preprocessing method. RMSEP of the prediction model for the sizing content was0.732 %, for the resin content it was 0.605, for the soluble resin content it was 0.101 andfor volatiles content it was 0.127. The results of the paired t-test revealed that there was nosignificant difference between the NIR method and the standard method. The NIRspectroscopy method could be used to predict the resin, soluble resin and the volatilescontent of the prepreg simultaneously, as well as sizing content of alkali-free cloth. Theprocessing parameters of the prepreg during manufacture could be adjusted quickly withthe help of the NIR analysis results. The results indicated that the NIR spectroscopymethod was sufficiently accurate and effective for the on-line monitoring of alkali-freecloth/phenolic resin prepreg. Full article

(This article belongs to the Section Physical Chemistry, Theoretical and Computational Chemistry)

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106 KiB

Open AccessArticle

Irradiation Effect on Oxidative Condition and Tocopherol Content of Vegetable Oils

by Stavros Lalas, Olga Gortzi, John Tsaknis and Konstantinos Sflomos

Int. J. Mol. Sci. 2007, 8(6), 533-540; https://doi.org/10.3390/i8060533 - 15 Jun 2007

Cited by 20 | Viewed by 7378

Abstract

The effect on induction period and tocopherol content after γ-irradiation onsamples of olive oil and seed oils (sunflower and soybean) was determined. In seed oilsamples 0, 100, 200 and 300 ppm of δ-tocopherol were added before irradiation with 1, 2and 3kGy. The results [...] Read more.

The effect on induction period and tocopherol content after γ-irradiation onsamples of olive oil and seed oils (sunflower and soybean) was determined. In seed oilsamples 0, 100, 200 and 300 ppm of δ-tocopherol were added before irradiation with 1, 2and 3kGy. The results of induction period showed that, after irradiation, all samplespresented a significant decreased in resistance to oxidation. However, this decrease wasminimized when δ-tocopherol was added. Irradiation significantly decreased the level oftocopherols. δ-Tocopherol appeared more sensitive in irradiation process than α- andγ-tocopherol. The addition of δ-tocopherol significantly reduced, in most cases, thedepletion of the other tocopherols. Full article

664 KiB

Open AccessArticle

A Centrifugation-based Method for Preparation of Gold Nanoparticles and its Application in Biodetection

by Zhiqiang Liang, Juan Zhang, Lihua Wang, Shiping Song, Chunhai Fan and Genxi Li

Int. J. Mol. Sci. 2007, 8(6), 526-532; https://doi.org/10.3390/i8060526 - 13 Jun 2007

Cited by 35 | Viewed by 12080

Abstract

Gold nanoparticles (AuNPs) have found widespread applications in lifesciences. While synthesis of monodispersed AuNPs has been fairly convenient by usingchemical reduction of chloroauric acid by sodium citrate, we found that AuNPs of highquality and high concentrations were not readily obtained via this method. [...] Read more.

Gold nanoparticles (AuNPs) have found widespread applications in lifesciences. While synthesis of monodispersed AuNPs has been fairly convenient by usingchemical reduction of chloroauric acid by sodium citrate, we found that AuNPs of highquality and high concentrations were not readily obtained via this method. As an example,we showed that monodispersed 13-nm AuNPs were readily synthesized at relatively lowconcentrations (e.g. 3.5 nM); in contrast, 13-nm AuNPs of 17 nM obtained by the directreduction method were irregularly shaped and not well dispersed. In this work, wedemonstrated that AuNPs of high concentration could be prepared by a two-step approach,i.e. chemical reduction at low concentrations and subsequent centrifugation. Compared tothe direct reduction method, this new two-step method led to AuNPs with high saltresistance and high stability, which are essential for the preparation of DNA-AuNPsconjugates for DNA biodetection. Full article

(This article belongs to the Special Issue Nucleic Acid Derivatives in Emerging Technologies)

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471 KiB

Open AccessArticle

Branched-chain Amino Acid Biosensing Using Fluorescent Modified Engineered Leucine/Isoleucine/Valine Binding Protein

by Sakura Chino, Akane Sakaguchi, Rie Yamoto, Stefano Ferri and Koji Sode

Int. J. Mol. Sci. 2007, 8(6), 513-525; https://doi.org/10.3390/i8060513 - 13 Jun 2007

Cited by 10 | Viewed by 9953

Abstract

A novel fluorescence sensing system for branched-chain amino acids (BCAAs)was developed based on engineered leucine/isoleucine/valine-binding proteins (LIVBPs)conjugated with environmentally sensitive fluorescence probes. LIVBP was cloned fromEscherichia coli and Gln149Cys, Gly227Cys, and Gln254Cys mutants were generated bygenetic engineering. The mutant LIVBPs were then modified [...] Read more.

A novel fluorescence sensing system for branched-chain amino acids (BCAAs)was developed based on engineered leucine/isoleucine/valine-binding proteins (LIVBPs)conjugated with environmentally sensitive fluorescence probes. LIVBP was cloned fromEscherichia coli and Gln149Cys, Gly227Cys, and Gln254Cys mutants were generated bygenetic engineering. The mutant LIVBPs were then modified with environmentallysensitive fluorophores. Based on the fluorescence intensity change observed upon thebinding of the ligands, the MIANS-conjugated Gln149Cys mutant (Gln149Cys-M) showedthe highest and most sensitive response. The BCAAs Leu, Ile, and Val can each bemonitored at the sub-micromolar level using Gln149Cys-M. Measurements were alsocarried out on a mixture of BCAFAs and revealed that Gln149Cys-M-based measurementis not significantly affected by the change in the molar ratio of Leu, Ile and Val in thesample. Its high sensitivity and group-specific molecular recognition ability make the newsensing system ideally suited for the measurement of BCAAs and the determination of theFischer ratio, an indicator of hepatic disease involving metabolic dysfunction. Full article

(This article belongs to the Section Molecular Recognition)

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235 KiB

Open AccessArticle

Changes in the Ratio of Tc1/Tc2 and Th1/Th2 Cells but Not in Subtypes of NK-Cells in Preeclampsia

by Yali Hu, Jianjun Zhou, Sha Hao, Zhiqun Wang, Yiming Dai, Jingxian Ling and Yayi Hou

Int. J. Mol. Sci. 2007, 8(6), 492-504; https://doi.org/10.3390/i8060492 - 8 Jun 2007

Cited by 3 | Viewed by 10472

Abstract

It has been suggested that natural killer (NK) cell activity and Th1 immunitymay be involved in the pathogenesis of preeclampsia. This study aimed to investigate theimmunophenotypes of NK cells and type 1/type 2 immunity in both decidua and maternalperipheral blood between normal (n=11) [...] Read more.

It has been suggested that natural killer (NK) cell activity and Th1 immunitymay be involved in the pathogenesis of preeclampsia. This study aimed to investigate theimmunophenotypes of NK cells and type 1/type 2 immunity in both decidua and maternalperipheral blood between normal (n=11) and preeclamptic pregnant women (n=20) by flowcytometry. The results showed that no significant difference was observed between patientsand controls by detecting CD56⁺ CD69⁺ and CD56⁺ CD94⁺ NK cells in both peripheralblood and decidua. Moreover, in preeclamptic patients, decreased percentages of Tc2 andTh2 cells and the increased ratios of Tc1/Tc2 were determined in both decidua andmaternal peripheral blood. In addition, the ratio of Th1/Th2 in peripheral blood alsoincreased. There was no significant difference of immunophenotypes of uNK cells betweenpreeclampsia and normal pregnancy. Local decidua and systematic immunity did notcorrelate with each other. These results suggest that the type 1/type 2 immunity shifted totype 1 immunity including Th1 and Tc1 cells may contribute to the patho-genesis ofpreeclampsia. Full article

(This article belongs to the Special Issue Interaction of Biological Molecules)

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203 KiB

Open AccessArticle

Efficient Copper-bisisoquinoline-based Catalysts for Selective Aerobic Oxidation of Alcohols to Aldehydes and Ketones

by Hao-Yu Shen, Li-Yan Ying, Hai-Liang Jiang and Zaher M. A. Judeh

Int. J. Mol. Sci. 2007, 8(6), 505-512; https://doi.org/10.3390/i8060505 - 6 Jun 2007

Cited by 24 | Viewed by 9259

Abstract

The selective oxidation of alcohols with molecular oxygen was efficientlycompleted in high conversion and selectivity using copper-bisisoquinoline-based catalystsunder mild reaction condition. The effects of various parameters such as reactiontemperature, reaction time, oxidant, ligands, etc, were studied. Solvent effect has been aswell studied in [...] Read more.

The selective oxidation of alcohols with molecular oxygen was efficientlycompleted in high conversion and selectivity using copper-bisisoquinoline-based catalystsunder mild reaction condition. The effects of various parameters such as reactiontemperature, reaction time, oxidant, ligands, etc, were studied. Solvent effect has been aswell studied in ionic liquids [bmim]PF₆, [omim]BF₄ and [hmim]BF₄, comparing totraditional volatile organic solvent. The use of ionic liquids was found to enhance thecatalytic properties of the catalysts used. Full article

(This article belongs to the Special Issue Ionic Liquids)

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380 KiB

Open AccessArticle

High-level Expression of Cecropin X in Escherichia coli

by Yi Shen, Xue Gang Lao, Yuan Chen, Hong Zu Zhang and Xian Xiu Xu

Int. J. Mol. Sci. 2007, 8(6), 478-491; https://doi.org/10.3390/i8060479 - 4 Jun 2007

Cited by 7 | Viewed by 10056

Abstract

Cecropin X is a short cationic peptide with a broad antibacterial and antitumorspectrum. Here, we report the production of a tumor necrosis factor (TNFα)-cecropin Xfusion protein under the control of a temperature-inducible PR promoter in the bacterialexpression vector pRC. During fermentation, we studied [...] Read more.

Cecropin X is a short cationic peptide with a broad antibacterial and antitumorspectrum. Here, we report the production of a tumor necrosis factor (TNFα)-cecropin Xfusion protein under the control of a temperature-inducible PR promoter in the bacterialexpression vector pRC. During fermentation, we studied and optimized essentialparameters including the type of host cells, medium, timing of induction, post-inductiontime and dissolved oxygen level. Using the suitable conditions in the fermentation, up to20 % ~ 23 % of the total cellular proteins is produced as the fusion protein, mostly in theform of inclusion bodies. After washing, on average about 5.27 g dried inclusion bodiescould be collected from 1 L broth and the purity of inclusion bodies reached 80 %.Cecropin X obtained by cleaving the fusion protein with cyanogen bromide showedremarkable tumorcidal activity against mouse Lewis lung carcinoma 3LL in vivo. Full article

(This article belongs to the Special Issue Interaction of Biological Molecules)

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184 KiB

Open AccessArticle

Hydrolysis and Partial Recycling of a Chloroaluminate Ionic Liquid

by Ming-Hong Fang and Li-Sheng Wang

Int. J. Mol. Sci. 2007, 8(6), 470-477; https://doi.org/10.3390/i8060470 - 4 Jun 2007

Cited by 10 | Viewed by 8491

Abstract

Hydrolysis of the ionic liquid Et3NHCl-2AlCl3 and a process for recycling thetriethylamine were studied. When the hydrolysis was carried out at a relatively hightemperature, the released HCl could be absorbed more easily. With addition of sodiumhydroxide to the aqueous hydrolysis solution, a feasible [...] Read more.

Hydrolysis of the ionic liquid Et3NHCl-2AlCl3 and a process for recycling thetriethylamine were studied. When the hydrolysis was carried out at a relatively hightemperature, the released HCl could be absorbed more easily. With addition of sodiumhydroxide to the aqueous hydrolysis solution, a feasible process for recycling triethylaminewas developed, involving first distillation of triethylamine, followed by filtration of thealuminium hydroxide. The yield of recovered triethylamine was about 95%. Thetriethylhydrogenammonium chloride prepared from the recycled triethylamine was of goodpurity and could be reused to synthesize new chloroaluminate ionic liquids. Full article

(This article belongs to the Special Issue Ionic Liquids)

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Int. J. Mol. Sci., Volume 8, Issue 6 (June 2007) – 9 articles , Pages 470-563

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