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In vivo electrochemical detection of nitric oxide in tumor-bearing mice
Griveau S., Dumezy C, Seguin J., Chabot GG. Scherman D., Bedioui F.
Anal. Chem. - 79(3) :1030-3 - PMID:17263331 - 2007
Interest in elucidating the mechanisms of action of various classes of anticancer agents and exploring the pathways of the induced-nitric oxide (NO) release provides an impetus to conceive a better designed approach to locally detect NO in tumors, in vivo. We report here on the first use of an electrochemical sensor that allows the in vivo detection of NO in tumor-bearing mice. In a first step, we performed the electrochemical characterization of a stable electroactive probe, K4Fe(CN)6, directly injected into the liquid microenvironment especially created around the electrode in the tumor. Second, the ability of the inserted electrode system to detect the presence of NO itself in the tumoral tissue was achieved by using the chemically modified Pt/Ir electrode as NO sensor and two NO donor molecules: diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium 1,2-diolate (DEA-NONOate) and (Z)-1-[N-(2-aminopropyl)-N-(2-ammonio propyl)amino]diazen-1-ium 1,2-diolate (PAPA-NONOate). These two NO donor molecules allowed proving the electrochemical detection of (i) directly injected exogenous NO phosphate buffer solution into the tumor (decomposed DEA-NONOate) and (ii) biomimetically induced endogeneous release of NO in the tumoral tissue, upon injection of PAPA-NONOate into the tumor. This approach could be applied to the in vivo study of candidate anticancer drugs acting on the NO pathways.
Frontal analysis capillary electrophoresis hyphenated to electrospray ionization mass spectrometry for the characterization of the antithrombin/heparin pentasaccharide complex
Fermas S, Gonnet F, Varenne A, Gareil P, Daniel R.
Anal. Chem. - 79(13) :4987-93 - PMID:17536781 - 2007
The interaction of proteins with polysaccharides represents a major and challenging topic in glycobiology, since such complexes mediate fundamental biological mechanisms. A new strategy based on the hyphenation of frontal analysis capillary electrophoresis (FACE) with electrospray ionization mass spectrometry (ESIMS) is reported for the characterization of protein/carbohydrate complexes. While most of the previously reported CE-MS experiments were performed using capillary electrophoresis in zone format, we report for the first time CE-MS experiments in which CE was performed in frontal analysis (FACE-MS). We showed that the frontal mode offered a better sensitivity than zone mode and was well suited for the CE-MS coupling. This FACE-MS coupling was applied to the analysis of the complex between antithrombin and the sulfated pentasaccharide reproducing the antithrombin-binding sequence in heparin. The mixture of coincubated antithrombin and heparin pentasaccharide was continuously injected into the capillary, and the electrophoretic separation of the free and bound forms of the protein was achieved. The intact noncovalent complex antithrombin/heparin pentasaccharide was detected on-line by ESIMS in positive ionization mode and in nondenaturing sheath liquid conditions. The complex stoichiometry was determined from the mass measurement of the complex. In addition, the characterization of the sulfated pentasaccharide ligand dissociated from the complex was performed in negative ionization mode using a denaturing sheath liquid, allowing the determination of its molecular mass and sulfation features. This FACE-ESIMS strategy opens the way to ligand fishing experiments performed on heterogeneous carbohydrate mixtures and subsequent characterization of specifically bound carbohydrates.
Highly Parallel Mix-and-Match Fabrication of Nanopillar Arrays Integrated in Microfluidic Channels for Long DNA Molecule Separation
J. Shi, A. P. Fang, L. Malaquin, A. Pepin, D. Decanini, J. L. Viovy and Y. Chen
Applied Physics Letters - 91(15) :153114 - DOI:153114 10.1063/1.2793616 - 2007
We report on a mix-and-match method based on a combination of soft UV nanoimprint lithography, contact optical lithography, and reactive-ion-etch techniques, which is applicable for high throughput manufacturing of nanostructure integrated microfluidic devices. We demonstrate the integration of high density and high aspect ratio nanopillars into microfluidic channels as electrophoresis sieving matrices. As a result, ? DNA and T4 DNA can be separated within a few minutes. By changing the pattern design, the device could be used for separation of other types of molecules.
Microcontact Printing of Living Bacteria Arrays with Cellular Resolution
L. P. Xu, L. Robert, O. Y. Qi, F. Taddei, Y. Chen, A.B. Lindner, D. Baigl
Nano Lett. - 7(7) :2068-72 - DOI:10.1021/nl070983z - 2007
Arrays of living bacteria were printed on agarose substrate with cellular resolution using elastomeric stamps with a high aspect ratio generated by reverse in situ lithography (RISL). The printed bacteria reproduced the original stamp patterns with high fidelity and continued growing as in bulk culture. This methodology provides a simple route to any desired bacterial spatial 2D distribution and may be applied to screening as well as to studies of bacteria phenotypic variability, population dynamics, and ecosystem evolution.
Stable Modification of PDMS surface properties by plasma polymerization: Application to the formation of double emulsions in microfluidic systems
Vanessa Barbier, Michaël Tatoulian, Hong Li, Farzaneh Arefi-Khonsari ,Armand Ajdari and Patrick Tabeling
Langmuir - 22(12) :5230-2 - DOI:10.1021/la053289c - 2006
We describe a method based on plasma polymerization for the modification and control of the surface properties of poly(dimethylsiloxane) (PDMS) surfaces. By depositing plasma polymerized acrylic acid coatings on PDMS, we succeeded to fabricate stable (several days) hydrophilic and patterned hydrophobic/hydrophilic surfaces. We used this approach to generate direct and (for the first time in this material) double emulsions in PDMS microchannels.
A conductive hydrogel based on alginate and carbon nanotubes for probing microbial electroactivity
Léopold Mottet, Domitille Le Cornec, Jean-Marc Noël, Frédéric Kanoufi, Brigitte Delord, Philippe Poulin, Jérôme Bibettea and Nicolas Bremond
- 14 1434-1441 - 10.1039/C7SM01929G -
Some bacteria can act as catalysts to oxidize (or reduce) organic or inorganic matter with the potential of generating electrical current. Despite their high value for sustainable energy, organic compound production and bioremediation, a tool to probe the natural biodiversity and to select most efficient microbes is still lacking. Compartmentalized cell culture is an ideal strategy for achieving such a goal but the appropriate compartment allowing cell growth and electron exchange must be tailored. Here, we develop a conductive composite hydrogel made of a double network of alginate and carbon nanotubes. Homogeneous mixing of carbon nanotubes within the polyelectrolyte is obtained by a surfactant assisted dispersion followed by a desorption step for triggering electrical conductivity. Dripping the mixture in a gelling bath through simple extrusion or a double one allows the formation of either plain hydrogel beads or liquid core hydrogel capsules. The process is shown to be compatible with the bacterial culture (Geobacter sulfurreducens). Bacteria can indeed colonize the outer wall of plain beads or the inner wall of the conductive capsules' shell that function as an anode from which electrons produced by the cells are collected.
Cell Fate Decision during C. elegans Gonadogenesis
Michelle A. Wolfgang Keil, Justin M. Benavidez Iva Greenwald
- - DOI:https://doi.org/10.1016/j.cub.2019.07.062 -
Large-Scale Lineage Analysis Refines the Relationship between Birth Order and Cell Fate
The anchor cell (AC) is a unique cell in the proximal region of the developing gonad that serves as the signaling nexus for uterine and vulval patterning and in connecting the uterus and the vulva [12, 13]; its correct specification is therefore critical for maximizing reproductive success. Initially, four cells in the developing somatic primordium have the potential to be the AC (Figure 1A). As described further below, the conserved transcription factor HLH-2 is required to endow these cells with AC potential. The “β cells” soon lose AC potential and always become ventral uterine precursor cells (VUs); the two α cells maintain AC potential and interact via LIN-12/Notch to resolve which will become the AC and which will become another VU
Micropipette-powered droplet based microfluidics
Krzysztof Langer, Nicolas Bremond, Laurent Boitard, Jean Baudry, Jerome Bibette
Biomicrofluidics - 12 44106 - https://doi.org/10.1063/1.5037795 -
Droplet-based microfluidics, using water-in-oil emulsion droplets as micro-reactors, is
becoming a widespread method for performing assays and especially in the cell biol-
ogy field. Making a simple and highly portable system for creating emulsion droplets
would help to continue the popularization of such a technique. Also, the ability to
emulsify all the samples would strengthen this compartimenlization technique to han-
dle samples with limited volume. Here, we propose a strategy of droplet formation
that combines a classical flow-focusing microfluidic chip, which could be commer-
cially available, with a standard laboratory adjustable micropipette. The micropipette
is used as a negative pressure generator for controlling liquid flows. In that way, emul-
sification does neither require any electrical power supply nor a cumbersome device
and functions with small liquid volumes. Droplet formation can be easily and safely
performed in places with limited space, opening a wide range of applications espe-
cially in biological laboratory environments with higher level of safety regulations,
i.e., BSL-3/4. Fortunately, the present methodology that involves small fluid vol-
umes, and thus possible time dependent flow conditions, allows to minimize dead
volume while keeping drops’ size homogeneous. A physical characterization
of droplet production and a model that describes the emulsion features, in terms of
drop size and size distribution, are proposed for rationalizing the performances of
the micropipette-powered emulsification process.
Published by AIP Publishing.
A conductive hydrogel based on alginate and carbon nanotubes for probing microbial electroactivity
Léopold Mottet, Domitille Le Cornec, Jean-Marc Noël, Frédéric Kanoufi, Brigitte Delord, Philippe Poulin, Jérôme Bibette and Nicolas Bremond
- 14 1434 - DOI: 10.1039/c7sm01929g -
Some bacteria can act as catalysts to oxidize (or reduce) organic or inorganic matter with the potential
of generating electrical current. Despite their high value for sustainable energy, organic compound
production and bioremediation, a tool to probe the natural biodiversity and to select most efficient
microbes is still lacking. Compartmentalized cell culture is an ideal strategy for achieving such a goal but
the appropriate compartment allowing cell growth and electron exchange must be tailored. Here, we
develop a conductive composite hydrogel made of a double network of alginate and carbon nanotubes.
Homogeneous mixing of carbon nanotubes within the polyelectrolyte is obtained by a surfactant
assisted dispersion followed by a desorption step for triggering electrical conductivity. Dripping the
mixture in a gelling bath through simple extrusion or a double one allows the formation of either plain
hydrogel beads or liquid core hydrogel capsules. The process is shown to be compatible with the
bacterial culture (
Geobacter sulfurreducens
). Bacteria can indeed colonize the outer wall of plain beads
or the inner wall of the conductive capsules’ shell that function as an anode from which electrons
produced by the cells are collected
Micropipette-powered droplet based microfluidics
Krzysztof Langer, Nicolas Bremonda), Laurent Boitard, Jean Baudry, and Jérôme Bibette
Biomicrofluidics - 44106 - 10.1063/1.5037795 -
Droplet-based microfluidics, using water-in-oil emulsion droplets as micro-reactors, is becoming a widespread method for performing assays and especially in the cell biology field. Making a simple and highly portable system for creating emulsion droplets would help to continue the popularization of such a technique. Also, the ability to emulsify all the samples would strengthen this compartimenlization technique to handle samples with limited volume. Here, we propose a strategy of droplet formation that combines a classical flow-focusing microfluidic chip, which could be commercially available, with a standard laboratory adjustable micropipette. The micropipette is used as a negative pressure generator for controlling liquid flows. In that way, emulsification does neither require any electrical power supply nor a cumbersome device and functions with small liquid volumes. Droplet formation can be easily and safely performed in places with limited space, opening a wide range of applications especially in biological laboratory environments with higher level of safety regulations, i.e., BSL-3/4. Fortunately, the present methodology that involves small fluid volumes, and thus possible time dependent flow conditions, allows to minimize dead volume while keeping drops' size homogeneous. A physical characterization of droplet production and a model that describes the emulsion features, in terms of drop size and size distribution, are proposed for rationalizing the performances of the micropipette-powered emulsification process.

410 publications.