Spectrophotometric determination of total protein in serum using a novel near-infrared cyanine dye, 5,5′-dicarboxy-1,1′-disulfobutyl-3,3,3′,3′-tetramethylindotricarbocyanine

The application of near-infrared (NIR) dyes (λ _em > 750 nm) to the analysis of biological samples shows much promise, because the long emission wavelengths of such dyes allow interferences from biomolecule matrices to be minimized. In this paper, a novel NIR dye, 5,5′-dicarboxy-1,1′-disulfobutyl-3,3,3′,3′-tetramethylindotricarbocyanine (DCDSTCY) has been developed for the spectrophotometric determination of total protein in serum. Under acidic conditions, the binding of DCDSTCY to proteins caused a new peak at 878 nm, the height of which was proportional to the concentration of protein. The linear range of the method was found to be 0.04–0.5 μg mL⁻¹ for bovine serum albumin (BSA) and human serum albumin (HSA), and detection limits of 5 ng mL⁻¹ were obtained for these substances. The maximum binding number of BSA with DCDSTCY was measured to be 133. The method proposed here has been applied to the quantitation of total protein in serum, and recoveries of 96.6–104% were achieved. Figure Near-infrared probe for protein determination     

Rapid screening and detection of XOD inhibitors from S. tamariscina by ultrafiltration LC-PDA–ESI-MS combined with HPCCC

Xanthine oxidase (XOD) catalyzes the metabolism of hypoxanthine and xanthine to uric acid, the overproduction of which could cause hyperuricemia, a risk factor for gout. Inhibition of XOD is a major treatment for gout, and biflavonoids have been found to act as XOD-inhibitory compounds. In this study, ultrafiltration liquid chromatography with photodiode-array detection coupled to electrospray-ionization tandem mass spectrometry (UF-LC-PDA–ESI-MS) was used to screen and identify XOD inhibitors from S. tamariscina. High-performance counter-current chromatography (HPCCC) was used to separate and isolate the active constituents of these XOD inhibitors. Furthermore, ultrahigh-performance liquid chromatography (UPLC) and triple-quadrupole mass spectrometry (TQ-MS) was used to determine the XOD-inhibitory activity of the obtained XOD inhibitors, and enzyme kinetics was performed with Lineweaver–Burk (LB) plots using xanthine as the substrate. As a result, two compounds in S. tamariscina were screened as XOD inhibitors: 65.31 mg amentoflavone and 0.76 mg robustaflavone were isolated from approximately 2.5 g?S. tamariscina by use of HPCCC. The purities of the two compounds obtained were over 98 % and 95 %, respectively, as determined by high-performance liquid chromatography (HPLC). Lineweaver–Burk plot analysis indicated that amentoflavone and robustaflavone were non-competitive inhibitors of XOD, and the IC ₅₀ values of amentoflavone and robustaflavone for XOD inhibition were 16.26 μg mL^?1 (30.22 μmol L^?1) and 11.98 μg mL^?1 (22.27 μmol L^?1), respectively. The IC ₅₀ value of allopurinol, used as the standard, was 7.49 μg mL^?1 (46.23 μmol L^?1). The results reveal that the method for systematic screening, identification, and isolation of bioactive components in S. tamariscina and for detecting their inhibitory activity using ultrafiltration LC–ESI-MS, HPCCC, and UPLC–TQ-MS is feasible and efficient, and could be expected to extend to screening and separation of other enzyme inhibitors. Graphical Abstract

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(R)- and (S)-α-Methoxy-(1-naphthyl) acetic acids: resolution by fractional crystallization and use for the NMR stereochemical analysis of alkylsulfoxides

Both enantiomers of α-methoxy-(1-naphthyl) acetic acid (1-NMA) were conveniently obtained via fractional crystallization using the enantiomers of 1-(1-naphthyl) ethylamine. 1-NMA was shown to be very powerful for differentiating the enantiomeric signals of quasi-symmetrical aliphatic sulfoxides.     

Synthesis of ω- and (ω – 1)-acetylenic acids from five-, six-, or seven-membered cycloalkanones

A convenient method for the synthesis of - and ( – 1)-acetylenic acids involves free-radical oxidative scission of cycloalkanones containing five-, six, or seven-membered cycles to give the corresponding -olefinic acids followed by bromination of the latter and subsequent dehydrobromination under the action of alkalis.     

Thermal decomposition and thermal stability of potassium 3,3′-dinitrimino-5,5′-bis(1H-1,2,4-triazole)

Journal of Thermal Analysis and Calorimetry - Potassium 3,3′-dinitrimino-5,5′-bis(1H-1,2,4-triazole) (K2DNABT), a new potential green primary explosive, was synthesized and...     

Enantioselective recognition of α-hydroxycarboxylic acids and N-Boc-amino acids by counterion-displacement assays with a chiral nickel(II) complex

A new chiral sensor based on an N,N'-dioxide nickel(II) complex was prepared, which could visually recognize a series of chiral α-hydroxycarboxylic acid enantiomers by coordination and self-assembly forming into nanospheres or nanofibers. With the help of various techniques, the morphology structures of the colloid or suspension were obtained and the counterion-displacement assays were also confirmed. In addition, this metal complex could act as a highly enantioselective fluorescence sensor to recognize N-Boc-amino acids and chiral α-hydroxycarboxylic acids.     

Synthesis of 1-(4-Antipyrinyl)-3-(3-Chlorophenyl)-Triazene and Its Colour Reaction with Mercury

TheantiPyrinldiazoaminoreagentsweresensitivefOrCd(II)andHg(II)11-3l-Receatly,anewreagrntlK4-antiPyrinl)-3<3-Chlorophenylytrime(APPT)wasSynthsized.ThecolourreahonofAnCPTwithmerCurywasstUdied-ThemethodfordeterminingmicroaznountofmempwithAPCPTwasmoresensitiveandhighlyselective.AnditwasusedtodeterIninemercmpcoboinnatUralwaterwithsatisfactryresults.ExperimeutalAPP~:Model75lspectrophotOmeter,ModelpH-2meter(madeinShanghai).Sbodard~solution:DissolveHgCl2(A.R.)inWate.AddseveraldroPso…     

Intramolecular O-Sn coordination in (Z)-1-(triphenylstannyl)-3-phenyl-1-buten-3-ol: Evidence by X-ray diffracation analysis and bromination

The synthesis and properties of (Z)-1-(triphenylstannyl)-3-phenyl-1-buten-3-ol (1) are described. Compound 1 crystallizes from alcohol in the monoclinic space group P21/c with unit-cell dimensions a=9.296(2), 6=14.081(3), c=18.390(5) A,B=97.70(2), V=2385.5(1) A3, Z=4, F(000)=1008, Dc=1.38 g.cm-3,u=10.88 cm-1, final R=0.0359 for 3079 observed reflection [I > 3(I)]. The X-ray diffraction analysis of this compound shows the presence of an intramolecular coordination to the tin atom giving rise to a five-membered ring in which the metal exhibits a distroted trignoal bipyramidal geometry; as a consequence, a phenyl group, probably the apical one, is cleaved more easily by bromine than the vinyl substituent.     

Rapid speciation of Se(IV) and Se(VI) by flow injection–capillary electrophoresis system with contactless conductivity detection

A flow injection–capillary electrophoresis system with contactless conductivity detection and hydrostatic-pressure-generated flow was used for the fast and sensitive speciation of Se(IV) and Se(VI). The sample throughput was 25 samples per hour using a background electrolyte solution containing 8.75 mM l-histidine (His) adjusted to pH 4.00 with acetic acid. The repeatability of peak areas (n=8) was better than 1.41% and the limits of detection were 190 g L^–1 and 7.5 g L^–1 for Se(IV) and Se(VI), respectively. The interference from carbonate, typically present in water samples, was eliminated by using a low-pH electrolyte in which carbonate is uncharged and migrates at the EOF front. The method was applied to the analysis of Se(IV) and Se(VI) in soil samples that were spiked with both selenium species and the results for recovery of both selenium species were in good agreement with their introduced concentrations.     

Poly(ε-caprolactone)-banded spherulites and interaction with MC3T3-E1 cells

We report that protein adsorption, cell attachment, and cell proliferation were enhanced on spherulites-roughened polymer surfaces. Banded spherulites with concentric alternating succession of ridges and valleys were observed on spin-coated thin films of poly(ε-caprolactone) (PCL) and two series of PCL binary homoblends composed of high- and low-molecular-weight components when they were isothermally crystallized at 25-52 °C. Their thermal properties, crystallization kinetics, and surface morphology were examined. The melting temperature (T(m)), crystallinity (χ(c)), crystallization rate, and spherulitic patterns showed strong dependence on the crystallization temperature (T(c)) and the blend composition. The surface roughness of the spherulites was higher when T(c) was higher; thus, the larger surface area formed in banded spherulites could adsorb more serum proteins from cell culture media. In vitro mouse preosteoblastic MC3T3-E1 cell attachment, proliferation, and nuclear localization were assessed on the hot-compressed flat disks and spherulites-roughened films of the high-molecular-weight PCL and one of its homoblends. The number of attached MC3T3-E1 cells and the proliferation rate were greater on the rougher surfaces than those on the flat ones. It is interesting to note that cell nuclei were preferentially, though not absolutely, located in or close to the valleys of the banded spherulites. The percentage of cell nuclei in the valleys was higher than 78% when the ridge height and adjacent ridge distance were ~350 and ~35 nm, respectively. This preference was weaker when the ridge height was lower or at a higher cell density. These results suggest that isothermal crystallization of semicrystalline polymers can be an effective thermal treatment method to achieve controllable surface roughness and pattern for regulating cell behaviors in tissue-engineering applications.     

Functionalization of carbon nanotubes with biodegradable supramolecular polypseudorotaxanes from grafted-poly(ε-caprolactone) and α-cyclodextrins

Functionalization of multiwalled carbon nanotubes (MWNTs) with biodegradable supramolecular polypseudorotaxanes has been successfully performed by utilizing surface-initiated ring-opening polymerization of ε-caprolactone (CL) to yield poly(ε-caprolactone)-grafted MWNTs (MWNT-g-PCL), followed by forming inclusion complexes between grafted-PCL chains and α-cyclodextrins (α-CDs) to give α-CD-NTPCL hybrids. There are significant differences in the morphology and solubility of MWNTs before and after introduction of α-CD. Some protuberances are clearly observed for α-CD-NTPCL as compared with MWNT-g-PCL. Furthermore, the host-guest stoichiometry (monomeric unit of CL/α-CD molar ratio) for α-CD-NTPCL is much higher than that of polypseudorotaxanes consisted of linear PCL and α-CDs. This observation can be explained by a combination of several reasons including the steric hindrance of grafted-PCL, the competitive exclusion between adjacent PCL chains toward α-CD, and the addition order of α-CD as well as the host-guest feed ratio. The present methodology may open up a new opportunity toward the application of supramolecular chemistry for the chemical manipulation and processing of CNTs. Moreover, such novel supramolecular hybrids provide an entry to extend the applications of CNTs to medicine and biology fields through embedding the functional polymers and heterogeneous components.     

Reactions of Methyl 1-(Bromoacetyl)azulene-3-carboxylate with Thioamides and Thioureas: Synthesis of 1-(Thiazol-4-yl)-3-methoxycarbonylazulenes

Thiazole derivatives have attracted a great deal of interest owing to their physiological activities. In addition, thiazoles are also useful in dye and photographic industry.[1] In the present paper we report the synthesis of azulenes containing a thiazole moiety.     

Synthesis of enantiopure, axially chiral, C-tetrasubstituted α-amino acids with binaphthyl-based crowned side chains and 3D-structural analysis of their peptides

The syntheses of the terminally protected, crowned, C^α-tetrasubstituted α-amino acids with only axial chirality, the two diastereomers Boc-(S)-Bip[(R)-Binol-22-C-6]-OMe and Boc-(R)-Bip[(R)-Binol-22-C-6]-OMe, and their respective enantiomers Boc-(R)-Bip[(S)-Binol-22-C-6]-OMe and Boc-(S)-Bip[(S)-Binol-22-C-6]-OMe, all derived from 2′,1′:1,2; 1″,2″:3,4-dibenzcyclohepta-1,3-diene-6-amino-6-carboxylic acid (Bip), were performed by bis-alkylation with cyclization of racemic (R+S)-Boc-[HO]₂-Bip-OMe, possessing two phenolic OH groups at the 6,6′-positions of the biphenyl frame of Bip, using (+)-(R)- and (−)-(S)-Binol[(OCH₂CH₂)₂OTs]₂ (2,2′-bis[5-tosyloxy-3-oxa-1-pentyloxy]-1,1′-binaphthyl), respectively, as the alkylating agent followed by chromatographic separation. Two series of terminally protected model peptides to the hexamer level, containing the (R)-Bip[(S)-Binol-22-C-6] residue at i and i+3 positions of the sequence, combined with either l-Ala or l-Ala/Aib, were synthesized by solution methods. Their 3D-structural analyses by FTIR absorption and NMR suggest that these peptides preferentially adopt folded secondary structures.     

Determination of selected pesticides by GC with simultaneous detection by MS (NCI) and μ-ECD in fruit and vegetable matrices

A gas chromatography–mass spectrometry method in negative chemical ionization mode has been developed incorporating simultaneous detection using a micro-electron capture detector (μ-ECD) for the determination of pesticides in fruits and vegetables. This instrument configuration uses a three-way splitter device which divides the effluent from the analytical column between the two detectors with the split ratio 1:0.1 (MSD/μ-ECD) in each run. The μ-ECD was used for confirmation purposes. Validation of the method was performed on three matrices: tomato, apple, and orange. The ethyl acetate method was assayed; recovery studies were performed at 10 and 100 μg/kg. Recoveries between 70% and 120% were achieved and relative standard deviations lower than 20% (n = 5) were obtained for all pesticides and matrices studied. Limits of quantification lower than 10 μg/kg were obtained for 100% of pesticides in all of the matrices. Limits of quantification lower than 2.5 μg/kg were achieved for 77.8% of pesticides in the tomato and apple matrices, and for 72.2% of pesticides in the orange matrix. The method showed linear response in the concentration range tested (2.5–500 μg/kg) with correlation coefficients >0.99. Good repeatability and reproducibility results were obtained in all cases, with relative standard deviations lower than 16.7% and 20%, respectively. Finally, 20 incurred samples were analyzed using the proposed method. The simultaneous use of the two detectors was satisfactory for the analysis of these real samples. The total number of pesticides identified was 25. The number of samples which contained at least one pesticide was 15—this represented 75% of the total number of samples studied.     

Theoretical am1 studies of inclusion complexes of α- and β-cyclodextrins with methylated benzoic acids and phenol,and γ-cyclodextrin with buckminsterfullerene

Semiempirical AM1 calculations have been performed on the inclusion complexes of - and -cyclodextrin with benzoic acid and phenol and -cyclodextrin with methylated benzoic acids in the head first and tail first positions. The results show that -cyclodextrin complexes with phenol and benzoic acid guests in the head first position are more stable than in the tail first position, while -cyclodextrin complexes with the same guests prefer the tail first position. The preferred orientation for -cyclodextrin with methylated benzoic acids is determined by the position of the methyl substituent(s). In general, para-methyl benzoic acid derivatives prefer the tail first position. -cyclodextrin forms a slightly unstable 1:1 complex with C₆₀ (3.4 kcal/mol), but two -cyclodextrins provide enough stabilization by about 10 kcal/mol to cage-in the C₆₀.     

Synthesis, Structure and Dielectric Property of Ba_(1- x)Sr_xZr_yTi_(1- y)O_3

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Speciation of mercury,tin, and lead compounds by gas chromatography with microwave-induced plasma and atomic-emission detection (GC–MIP–AED)

Because of their high toxicity and widespread distribution, the reliable selective quantification of alkyl and aryl species containing mercury, tin, or lead has been one of the goals of speciation analysis in recent years. Since becoming commercially available, GC-MIP-AED has been one of the most-used tools in this work. In this paper, the value and limitations of GC-MIP-AED for the speciation of Hg, Sn, and Pb compounds in environmental samples are reviewed and compared with the analytical characteristics of other hyphenated GC-based techniques. Because quantification of Hg, Sn, and Pb species by GC techniques normally requires complex sample preparation involving several steps, the effect of sample-preparation methods on the accuracy and precision of the results is discussed. Finally, we describe the current status of a rapid, low-cost GC-MIP-PED system specifically designed for routine quantification of Hg, Sn, and Pb species in environmental control laboratories.