Bernard Bennetau

University of Bordeaux, Burdeos, Aquitaine, France

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Publications (78)170.5 Total impact

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    ABSTRACT: Enterolactone (ENL) is produced by the gut microflora from lignans found in edible plants. ENL is estrogenic with no effect on the E-screen test and is a natural Selected Estrogen Receptor Modulator (SERM) with health interests that have to be checked in clinical studies with bioavailability assessment. Two haptens of ENL were synthesized, with a spacer arm at the C5 position having either 2 or 4 carbon atoms (ENLΔ2 and ENLΔ4, respectively). Hapten coupling to bovine serum albumin (BSA) was characterized by MALDI mass spectrometry. Polyclonal antibodies were obtained against the BSA conjugates. Additional conjugates were generated by coupling to swine thyroglobulin (Thyr). Homologous and heterologous competitive ELISAs were developed with Thyr or BSA conjugates as coating. The best assays were validated on biological samples from mice. Both antibodies exhibited the same IC50 at 1.5 ng mL−1 with a detection limit below 0.5 ng mL−1. Most cross-reactions with structurally related lignans were lower than 0.03%. This new assay type is faster, more specific and more reliable than existing ones.
    Talanta 02/2014; 119(1):116-124. · 3.51 Impact Factor
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    ABSTRACT: In this work, we propose "single-image analysis", as opposed to multi-image averaging, for extracting valuable information from AFM images of single bio-particles. This approach allows us to study molecular systems imaged by AFM under general circumstances without restrictions on their structural forms. As feature exhibition is a resolution correlation, we have performed AFM imaging on surfaces of tobacco mosaic virus (TMV) to demonstrate variations of structural patterns with probing resolution. Two AFM images were acquired with the same tip at different probing resolutions in terms of pixel width, i.e., 1.95 and 0.49 nm per pixel. For assessment, we have constructed an in silico topograph based on the three-dimensional crystal structure of TMV as a reference. The prominent artifacts observed in the AFM-determined shape of TMV were attributed to tip convolutions. The width of TMV rod was systematically overestimated by ∼10 nm at both probing resolutions of AFM. Nevertheless, the effects of tip convolution were less severe in vertical orientation so that the estimated height of TMV by AFM imaging was in close agreement with the in silico X-ray topograph. Using dedicated image processing algorithms, we found that at low resolution (i.e., 1.95 nm per pixel), the extracted surface features of TMV can be interpreted as a partial or full helical repeat (three complete turns with ∼7.0 nm in length), while individual protein subunits (∼2.5 nm) were perceivable only at high resolution. The present study shows that the scales of revealed structural features in AFM images are subject to both probing resolution and processing algorithms for image analysis.
    Nanoscale 09/2013; · 6.74 Impact Factor
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    ABSTRACT: The covalent grafting on silica surfaces of a functional dendritic organosilane coupling agent inserted, in a long alkyl chain monolayer, is described. In this paper, we show that, depending on experimental parameters, particularly the solvent, it is possible to obtain a nanodesigned surface via a bottom-up approach. Thus, we succeed in the formation of both homogeneous dense monolayer and a heterogeneous dense monolayer, the latter being characterized by a nanosized volcano-type pattern (4-6 nm of height, 100 nm of width and around 3 volcanos/µm2) randomly distributed over the surface. The dendritic attribute of the grafted silylated coupling agent affords enough anchoring sites to immobilize covalently functional gold nanoparticles (GNPs), coated with amino PEG polymer to resolve the chemical nature of the surfaces and especially the volcano type nanopattern structures of the heterogeneous monolayer. Thus, the versatile surface chemistry developed herein is particularly challenging as the nanodesign is straightforward achieved in a bottom-up approach without any specific lithography device.
    ACS Applied Materials & Interfaces 07/2013; · 5.90 Impact Factor
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    ABSTRACT: Novel urea coupling agent possessing a vinyl-terminal group and trimethoxysilyl anchoring group was synthesized and grafted onto SiO2/Au substrates. This ureido coupling agent exhibits a good capacity to directly yield homogeneous SAMs with a surface smoothing. Polarization Modulation InfraRed Reflection-Absorption Spectroscopy (PM-IRRAS) was used to monitor these SAMs since the different functional groups (alkyl chain, urea, vinyl) of the coupling agent were clearly observed. Chemical modifications of the terminal function for the covalent immobilization of biomolecules were also easily monitored by PM-IRRAS. We have demonstrated the successful reactions of the conversion of the vinyl-terminated SAMs successively into SAM-COOH and SAM-NHS without any degradation of the monolayer. The reactivity of activated esters was successfully investigated in order to immobilize the protein A.
    Langmuir 11/2012; · 4.38 Impact Factor
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    ABSTRACT: Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was used to characterize self-assembled monolayers (SAMs). Novel ester-terminated organosilicon coupling agents possessing a trialkoxysilyl headgroup and a urea group in the linear alkyl chains (4) were synthesized and grafted onto SiO(2)/Au substrates (SiO(2) film of 200 Å thickness deposited on gold mirror). This composite substrate allowed the anchoring of SAMs and preserved the high reflectivity for infrared radiation. PM-IRRAS spectra with very high signal-to-noise ratios have been obtained in the mid-infrared spectral range allowing monitoring of the grafted SAMs. Quantitative analysis of the measured signal is described to compare PM-IRRAS and conventional IRRAS spectra. This quantitative analysis has been validated since the band intensities in the corrected PM-IRRAS and conventional IRRAS spectra are identical. Orientation information on the different functional groups has been obtained comparing the corrected PM-IRRAS spectrum with the one calculated using isotropic optical constants of ester-terminated organosilicon coupling agents 4. The carbonyls of the urea groups are preferentially parallel to the substrate surface favoring intermolecular hydrogen bonding and consequently a close packing of the molecules attached to the surface. By contrast, the alkyl chains present gauche defects and are poorly oriented.
    Langmuir 05/2011; 27(10):6076-84. · 4.38 Impact Factor
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    ABSTRACT: Competitive inhibition serological assay for detection of the phytoestrogen glycitein (Glyc) was developed using surface plasmon resonance (SPR) technique with protein conjugates and polyclonal antibodies initially designed for the enzyme-linked immunosorbent assays (ELISA). The efficiency of the approach to the quantification of the soy isoflavone glycitein in water was investigated using the competitive reaction of analyte (free Glyc)and immobilized Glyc-BSA-conjugate with polyclonal antibodies. It was shown that the efficiency to detect Glyc drastically depends on the pH level of the probe solution. With the decrease in pH from 7.4 to 4.0, (i) the affinity of the specific reaction increases and (ii) the level of unspecific sorption becomes saturated. Non-specific adsorption to a SPR sensor surface obscures the specific component and shaded specific response at higher pH (6.0-7.4) when used serum for the quantification of specific analytes. The standard curves obtained in acidic solutions (pH 4-5) indicate that the linear part of the dependence completely covers the range between detection limit (0.1 μg/ml) and Glyc solubility in water (0.9 μg/ml). The difference in SPR- and ELISA-based analytical protocols as well as the requirements for increasing the efficiency in quantitative SPR analysis using purified antibodies is discussed.
    Talanta 05/2011; 84(3):867-73. · 3.50 Impact Factor
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    ABSTRACT: Competitive inhibition serological assay for detection of the phytoestrogen glycitein (Glyc)wasdeveloped using surface plasmon resonance (SPR) technique with protein conjugates and polyclonal antibodies initially designed for the enzyme-linked immunosorbent assays (ELISA). The efficiency of the approach to the quantification of the soy isoflavone glycitein in water was investigated using the competitive reaction of analyte (free Glyc)and immobilized Glyc–BSA-conjugate with polyclonal antibodies. It was shown that the efficiency to detect Glyc drastically depends on thepHlevel of the probe solution. With the decrease in pH from 7.4 to 4.0, (i) the affinity of the specific reaction increases and (ii) the level of unspecific sorption becomes saturated. Non-specific adsorption to a SPR sensor surface obscures the specific component and shaded specific response at higher pH (6.0–7.4) when used serum for the quantification of specific analytes. The standard curves obtained in acidic solutions (pH 4–5) indicate that the linear part of the dependence completely covers the range between detection limit (0.1�g/ml) and Glyc solubility in water (0.9�g/ml). The difference in SPR- and ELISA-based analytical protocols as well as the requirements for increasing the efficiency in quantitative SPR analysis using purified antibodies is discussed.
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    ABSTRACT: We have recently reported the analytical performance of an immunosensor comprising one mm-scale parallel plate laminar flow chamber and applied to capture MCF7 breast cancer cells (Ehrhart et al., Biosens. Bioelectr. 24, 467, 2008). Herein we present a new multiplex immunosensor embodying four parallel plate laminar flow chambers that fit onto a standard, functionalized, microscopy glass slide. The four surfaces are coated with long alkyl chain spacers of 21-aminohenicosyl trichlorosilane (AHTS) and then grafted with a monoclonal anti-human epithelial cell adhesion molecule (EpCAM) antibody specific of target cells to immobilize. We first demonstrate a significantly (P < 0.01) improved capacity of each of the four flow chambers of the multiplex immunosensor to capture MCF7 cells compared to the previous single chamber device. Second, in addition to an increase of cell immobilization, the multiplex device offers a versatile tool easily grafted with various purified antibodies onto the four surfaces. Third, we obtained high cell capture rate and efficiency of various numbers of MCF7 cells spiked in buffer containing an equal number of background leukocytes. And fourth, we demonstrate isolation efficiency of circulating tumor cells (CTCs) from peripheral blood drawn from a small cohort of patients with localized or metastatic breast cancer. This new multiplex immunosensor could be tested for its potential to capture different subpopulations of CTCs.
    Biomedical Microdevices 02/2011; 13(1):1-9. · 2.72 Impact Factor
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    ABSTRACT: Novel silsesquioxane thin films were conveniently synthesized by the sol-gel route under mild conditions. Thus, a sol was prepared from 4,4[prime or minute]-bis(triethoxysilyl)-1,1[prime or minute]-biphenyl (4,4[prime or minute]-BTEBp) under a hydroalcoholic medium without a surfactant, deposited by spin-coating on silica supports, and dried at 280 [degree]C. The resulting biphenylene-bridged films exhibited very smooth surfaces, excellent mechanical behavior and no cracks. Moreover, SEM and TEM studies showed flawless, homogeneous interfaces with silica substrates. The acoustic waveguide properties of these films on piezoelectric quartz microsensors were investigated at high frequency through a network analyzer. For an optimal thickness close to 1 [small mu ]m, a marked frequency shift of the main broad lobe and a decrease of the insertion loss were observed. These results show a strong effect of the waveguide for trapping the acoustic energy, promising an unprecedented ability to provide a new generation of sensors. The capability of this device in the detection of mass is also demonstrated through the immobilization of Bovine Serum Albumin (BSA). This novel approach appears very promising in view of the development of surface acoustic wave sensors and biosensors.
    Journal of Materials Chemistry 01/2011; 21(38):14581-14586. · 6.63 Impact Factor
  • ChemInform 12/2010; 26(52).
  • Pierre Babin, Bernard Bennetau
    ChemInform 11/2010; 32(46).
  • B. BENNETAU, M. KREMPP, J. DUNOGUES
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 11/2010; 25(44).
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    ABSTRACT: A four-step purification method was developed to isolate a citrus odorant detected by gas chromatography-olfactometry (GC-O), which was apparently specific to Sauternes botrytized wines. A fragmentation pattern of the odorant was obtained by multidimensional gas chromatography-mass spectrometry-olfactometry (MDGC-MS-O). The exact mass measurement was used to determine its elemental formula as C(6)H(12)OS. On the basis of these data, the unusual structure of 3-propyl-1,2-oxathiolane was synthesized and characterized for the first time. This confirmed its identification. Its occurrence in Sauternes wine extracts was demonstrated to result from the thermal oxidative degradation of 3-sulfanylhexanol disulfide (3,3'-disulfanediyldihexan-1-ol) in the GC injector. This disulfide was synthesized and then firmly identified for the first time in Sauternes wine. Although the presence of 3-sulfanylhexanol oxidation products had previously been reported in natural extracts (but not wine), the full oxidation pathway from 3-sulfanylhexanol to 3-propyl-γ-sultine via 3,3'-disulfanediyldihexan-1-ol was clearly established for the first time. Because the disulfide has mainly been detected in Sauternes botrytized wines, this finding suggested a singular reactivity of 3-sulfanylhexanol in botrytized wines, thus opening up a wide range of new opportunities in wine chemistry.
    Journal of Agricultural and Food Chemistry 10/2010; 58(19):10606-13. · 3.11 Impact Factor
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 09/2010; 26(37).
  • [Show abstract] [Hide abstract]
    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 07/2010; 27(31).
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    ABSTRACT: A very-long-chain (C22) organosilicon self-assembled monolayer (SAM) with terminal glycidyl groups was used to immobilize antibodies on the silica waveguide of a Love mode surface acoustic wave (SAW) immunosensor. This route enabled us to specifically detect, in real time, living Escherichia coli bacteria by using monoclonal anti-E. coli antibodies, leading to a marked sensor response in liquid aqueous medium. Conversely, no bacteria detection could be observed by this direct method upon functionalization of the waveguide surface by a (3-glycidoxypropyl) trimethoxysilane (GPTS) monolayer. This improvement was attributed to a surface smoothing effect resulting from the very-long-chain SAM and a better accessibility of the surface epoxide groups.
    Sensors and Actuators B Chemical 04/2010; 146(1):289-296. · 3.84 Impact Factor
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    ABSTRACT: An original synthetic route to asymmetrically substituted methoxypyrazine (MP) derivatives is described. The first step of the synthesis is achieved by condensation of 1,2-aminoalcohols with Boc-protected aliphatic aminoacids followed by cycloimine formation and aromatization via chlorination. Introduction of methoxy group was then achieved by alkoxy-de-halogenation. The use of primary or secondary aminopropanol enabled the direct and selective introduction of methyl group, in 5- or 6-position, which can be easily functionalized. Aromatization of diketopiperazine, prepared from l-valine and l-glutamic acid dimethyl ester, made possible a direct introduction of a functionalized alkyl chain. These reactions are also suitable for the synthesis of naturally-occurring MPs such as wine flavor components and biologically active substances.
    Tetrahedron 03/2010; 66(13):2463-2469. · 2.82 Impact Factor
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    ABSTRACT: Sweet wines made from botrytized grapes contain much higher concentrations of volatile thiols, especially 3-sulfanylhexan-1-ol (3SH), than dry white wines. Three new specific volatile thiols (3-sulfanylpentan-1-ol (3SP), 3-sulfanylheptan-1-ol (3SHp), and 2-methyl-3-sulfanylbutan-1-ol (2M3SB) were recently identified in Sauternes wines. Like most volatile thiols, these compounds were almost totally absent from must, mainly being formed during alcoholic fermentation. In this work, we describe the identification and quantification of three new cysteine-S-conjugate precursors in must made from Botrytis-infected grapes. S-3-(pentan-1-ol)-L-cysteine (P-3SP), S-3-(heptan-1-ol)-L-cysteine (P-3SHp), and S-3-(2-methylbutan-1-ol)-L-cysteine (P-2M3SB) were identified by direct GC-MS analysis of their derivative forms obtained by silylation of an enriched fraction, isolated from must by affinity chromatography. Concentrations were considerably higher when Botrytis cinerea had developed on the grapes. In botrytized must, the mean levels of P-3SP, P-3SHp, and P-2M3SB were in the vicinity of 700, 50, and 500 nM, respectively, whereas concentrations in healthy must ranged from 0 to 50 nM. This indicated that these three new sulfanyl alcohols, responsible for the characteristic aroma of botrytized wines, were formed by the yeast metabolism during alcoholic fermentation from the corresponding non-volatile cysteine-S-conjugate precursors. Moreover, these results highlighted the predominant role of botrytization in developing grape aroma potential.
    Analytica chimica acta 02/2010; 660(1-2):190-6. · 4.31 Impact Factor
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    [Show abstract] [Hide abstract]
    ABSTRACT: An original synthetic route to asymmetrically substituted methoxypyrazine (MP) derivatives is described. The first step of the synthesis is achieved bycondensation of 1,2-aminoalcohols with Boc-protected aliphatic aminoacids followed by cycloimine formation and aromatization via chlorination. Introduction of methoxy group was then achieved by alkoxy-de-halogenation. The use of primary or secondary aminopropanol enabled the direct and selective introduction of methyl group, in 5- or 6-position, which can be easily functionalized. Aromatization of diketopiperazine, prepared from L-valine and L-glutamic acid dimethyl ester, made possible a direct introduction of a functionalized alkyl chain. These reactions are also suitable for the synthesis of naturally-occurringMPssuch as wine flavorcomponents and biologicallyactive substances.

Publication Stats

639 Citations
170.50 Total Impact Points

Institutions

  • 1983–2014
    • University of Bordeaux
      Burdeos, Aquitaine, France
  • 2000–2011
    • Université Bordeaux 1
      • • UMR ISM - Institut des Sciences Moléculaires
      • • UMR CPMOH - Centre de Physique Moléculaire Optique et Hertzienne
      Talence, Aquitaine, France
  • 2007–2008
    • Université Victor Segalen Bordeaux 2
      • Institut des Sciences de la Vigne et du Vin (ISVV)
      Bordeaux, Aquitaine, France