Université PSL



Laboratory :
Author :
Revue :
Year :
Development of oligonucleotide microarray involving plasma polymerized acrylic acid” Thin Solid Films
R. Jafari , M. Tatoulian, D. Le Clerre, L. Talini, F. Richard, F. Arefi-Khonsari
Thin Solid Films - 517(19) :5763-8 - DOI:10.1016/j.tsf.2009.03.217 - 2009
This paper presents the manufacturing of biochips by using the COOH– derived polymer coating deposited by plasma polymerization of acrylic acid. This technology is based on depositing a thin layer obtained by plasma polymerization of acrylic acid which allows a further covalent immobilization of biomolecules on glass substrates. The plasma power value was optimized to maximize the stability of plasma polymerized acrylic acid (PPAA) coatings in water, which has a very important role for such applications. In order to obtain a covalent immobilization of DNA probes on the PPAA coated surface, the activation protocol of carboxylic function was carried out with the help of N-Hydroxy Succinimide and 1-Ethyl-3-(3-DimethylAminopropyl) Carbodiimide. The efficiency of PPAA coated in microarray applications was compared with two types of commercial slides. Such surfaces have shown very interesting results in terms of relative density of attached DNA probe molecules and signal-to-background ratio measured for target DNA hybridization. Nonspecific DNA bonding measurements showed only a small amount of nonspecific physisorption between the DNA probe and the PPAA-activated surfaces. This work shows that the plasma polymerization technique can be successfully applied to produce a high-quality glass surface for the manufacturing of DNA arrays.
Charge-based characterization of nanometric cationic bifunctional maghemite/silica core/shell particles by capillary zone electrophoresis
d'Orlye F, Varenne A, Georgelin T, Siaugue JM, Teste B, Descroix S, Gareil P
Electrophoresis - 30(14) :2572-82 - DOI:10.1002/elps.200800835. - 2009
In view of employing functionalized nanoparticles (NPs) in the context of an immunodiagnostic, aminated maghemite/silica core/shell particles were synthesized so as to be further coated with an antibody or an antigen via the amino groups at their surface. Different functionalization rates were obtained by coating these maghemite/silica core/shell particles with 3-(aminopropyl)triethoxysilane and 2-[methoxy(polyethyleneoxy)propyl]-trimethoxysilane at different molar ratios. Adequate analytical performances with CE coupled with UV-visible detection were obtained through semi-permanent capillary coating with didodecyldimethyl-ammonium bromide, thus preventing particle adsorption. First, the influence of experimental conditions such as electric field strength, injected particle amount as well as electrolyte ionic strength and pH, was evaluated. A charge-dependent electrophoretic mobility was evidenced and the separation selectivity was tuned according to electrolyte ionic strength and pH. The best resolutions were obtained at pH 8.0, high ionic strength (ca. 100 mM), and low total particle volume fraction (ca. 0.055%), thus eliminating interference effects between different particle populations in mixtures. A protocol derived from Kaiser's original description was performed for quantitation of the primary amino groups attached onto the NP surface. Thereafter a correlation between particle electrophoretic mobility and the density of amino groups at their surface was established. Eventually, CE proved to be an easy, fast, and reliable method for the determination of NP effective surface charge density.
Cell shape and cell division in fission yeast
Piel M, Tran PT
Curr Biol. - 17(19) :R823-7 - DOI:10.1016/j.cub.2009.08.012 - 2009
The fission yeast Schizosaccharomyces pombe has served as an important model organism for investigating cellular morphogenesis. This unicellular rod-shaped fission yeast grows by tip extension and divides by medial fission. In particular, microtubules appear to define sites of polarized cell growth by delivering cell polarity factors to the cell tips. Microtubules also position the cell nucleus at the cell middle, marking sites of cell division. Here, we review the microtubule-dependent mechanisms that regulate cell shape and cell division in fission yeast.
Simple and rapid process for single cell micro-patterning
Ammar Azioune, Marko Storch, Michel Bornens, Manuel Théry and Matthieu Piel
Lab. Chip - 9(11) :1640-2 - DOI:10.1039/b821581m - 2009
We present a simple and environmentally friendly process for cell patterning on glass covered with an ultrathin layer of poly-l-lysine-grafted-polyethylene glycol (PLL-g-PEG) by exposure to deep UV light. The patterned substrates are stable for months in the lab atmosphere before incubation with proteins. Incubation with proteins resulted in well defined patterns, with high feature resolution. RPE-1 cells seeded on fibronectin/fibrinogen-Alexa 488 patterns were constrained for days on the deep UV exposed regions. Finally, large glass plates were patterned with high homogeneity enabling the assembly of micro-patterned microplates in 96-well format.
Pushing off the walls: a mechanism of cell motility in confinement
Hawkins RJ, Piel M, Faure-Andre G, Lennon-Dumenil AM, Joanny JF, Prost J, Voituriez R
Phys. Rev. Lett. - 102(5) :58103 - DOI:10.1103/PhysRevLett.102.058103 - 2009
We propose a novel mechanism of cell motility, which relies on the coupling of actin polymerization at the cell membrane to geometric confinement. We consider a polymerizing viscoelastic cytoskeletal gel confined in a narrow channel, and show analytically that spontaneous motion occurs. Interestingly, this does not require specific adhesion with the channel walls, and yields velocities potentially larger than the polymerization velocity. The contractile activity of myosin motors is not necessary to trigger motility in this mechanism, but is shown quantitatively to increase the velocity. Our model qualitatively accounts for recent experiments which show that cells without specific adhesion proteins are motile only in confined environments while they are unable to move on a flat surface, and could help in understanding the mechanisms of cell migration in more complex confined geometries such as living tissues.
Photomanipulation of a Droplet by the Chromocapillary Effect
A. Diguet, R. M. Guillermic, N. Magome, A. Saint-Jalmes, Y. Chen, K. Yoshikawa and D. Baigl
Angew Chem Int Ed Engl. - 48(49) :9281-4 - DOI:10.1002/anie.200904868 - 2009
Ace of hearts: Liquid droplets can be manipulated in a controlled fashion along trajectories of any desired shape (such as a heart, see picture) by using light to create a wavelength-dependent interfacial tension gradient at a liquid/liquid interface. In this new phenomenon, the “chromocapillary effect”, an interfacial flow generates droplet motion in the direction opposite to the gradient.
Sequence-Independent and Reversible Photocontrol of Transcription/Expression Systems Using a Photosensitive Nucleic Acid Binder
A. Estevez-Torres, C. Crozatier, A. Diguet, T. Hara, H. Saito, K. Yoshikawa and D. Baigl
Proc. Nat. Acad. Sci. USA - 106(30) :12219-23 - DOI:10.1073/pnas.0904382106 - 2009
To understand non-trivial biological functions, it is crucial to develop minimal synthetic models that capture their basic features. Here, we demonstrate a sequence-independent, reversible control of transcription and gene expression using a photosensitive nucleic acid binder (pNAB). By introducing a pNAB whose affinity for nucleic acids is tuned by light, in vitro RNA production, EGFP translation, and GFP expression (a set of reactions including both transcription and translation) were successfully inhibited in the dark and recovered after a short illumination at 365 nm. Our results indicate that the accessibility of the protein machinery to one or several nucleic acid binding sites can be efficiently regulated by changing the conformational/condensation state of the nucleic acid (DNA conformation or mRNA aggregation), thus regulating gene activity in an efficient, reversible, and sequence-independent manner. The possibility offered by our approach to use light to trigger various gene expression systems in a system-independent way opens interesting perspectives to study gene expression dynamics as well as to develop photocontrolled biotechnological procedures.
A caged retinoic acid for one- and two-photon excitation in zebrafish embryos
P. Neveu, I. Aujard, C. Benbrahim, T. Le Saux, J.-F. Allemand, S. Vriz, D. Bensimon and L. Jullien
Angew Chem Int Ed Engl. - 47(20) :3744–46 - DOI:10.1002/anie.200800037 - 2008
A simple and universal tool to remove on-line impurities in mono- or two-dimensional liquid chromatography–mass spectrometry analysis
Hesse A-M, Marcelo P, Rossier J and Vinh J.
J. Chrom. A - 1189(1-2) :175-82 - DOI:10.1016/j.chroma.2007.12.060 - 2008
Several recurrent problems have always hindered mono-dimensional liquid chromatography-mass spectrometry proteomic analyses. Polymer contamination is a major problem because polymers could co-elute with compounds of interest (peptides). In this case spectral suppression degrades dynamic range and sensitivity. Polyethylene glycol derivatives count among the major contaminants. They are targeted in this work. They are eluted at 35-40% acetonitrile from C18 phase in every single reversed-phase run. Moreover, they are also observed in two-dimensional liquid chromatography in every salt fraction. A simple and robust method is presented here for rapid and efficient on-line removal of these impurities using self-regenerating purification microdevices.
Chiral Colloidal Clusters
D. Zerrouki, J. Baudry, D. Pine, P. Chaikin, J. Bibette
Nature - 455 :380-2 - DOI:10.1038/nature07237 - 2008
Chirality is an important element of biology, chemistry and physics. Once symmetry is broken and a handedness is established, biochemical pathways are set. In DNA, the double helix arises from the existence of two competing length scales, one set by the distance between monomers in the sugar backbone, and the other set by the stacking of the base pairs1. Here we use a colloidal system to explore a simple forcing route to chiral structures. To do so we have designed magnetic colloids that, depending on both their shape and induced magnetization, self-assemble with controlled helicity. We model the two length scales with asymmetric colloidal dumbbells linked by a magnetic belt at their waist. In the presence of a magnetic field the belts assemble into a chain and the steric constraints imposed by the asymmetric spheres force the chain to coil. We show that if the size ratio between the spheres is large enough, a single helicity is adopted, right or left. The realization of chiral colloidal clusters opens up a new link between colloidal science and chemistry. These colloidal clusters may also find use as mesopolymers, as optical and light-activated structures2, and as models for enantiomeric separation.

391 publications.