Christian Pichot

Synthesis and characterization of cationic amino functionalized polystyrene latexes

Amino-functionalized latex particles were obtained batchwise by emulsion copolymerization of styrene and vinylbenzylamine hydrochloride (VBAH) in the presence of 2-2′-Azobis(2-amidinopropane) HCl (V50). Size monodispersity of the particles was improved by using divinylbenzene (DVB) as a third monomer at a 2% molar ratio. Surface amino group titration was performed spectrometrically with N-succinimidyl 3-(2 pyridyldithio)propionate (SPDP). The yields of functional monomer incorporation were up to 85%.

Hydrophilic and cationic latex particles for the specific extraction of nucleic acids

The adsorption of BSA and RNA onto hydrophilic and thermosensitive poly(N-isopropyl-acrylamide) (NIPAM) latex particles was described as a function of pH, ionic strength and temperature. The hydrogel poly(NIPAM) latex was synthesized by precipitation polymerization in the presence of a cationic amino-containing monomer. The latex obtained was characterized in terms of particle size, and electrophoretic mobility as a function of pertinent variables: pH, temperature and ionic strength. The adsorption of BSA onto the latex was investigated to identify the conditions at which the adsorbed amount of BSA was negligible. The adsorption of RNA was studied to establish the conditions which give rise to maximal adsorption of RNA. In order to favor the desorption of RNA, desorption was investigated by changing the pH, ionic strength, and temperature. The adsorption of BSA was found to be lower at 20 than at 40 degrees C. However, the adsorption of RNA is drastically affected by the pH and the ionic strength of the medium. Maximal adsorbed amounts were obtained at acidic pH, 20 degrees C, and low ionic strength. The adsorption is shown to decrease when the pH, temperature and ionic strength increase, implying that the adsorption was mainly governed by electrostatic interactions. Maximal release of RNA molecules was obtained at high ionic strength and basic pH.

Synthesis and characterization of cationic latex particles bearing sulfhydryl groups and their use in the immobilization of Fab antibody fragments (1)

Emulsion copolymerization of styrene and a cationic monomer vinylbenzyl-isothiouronium chloride (VBIC) with initiation by 2,2′ azobis(2-amidinopropane)-dihydrochloride (V-50) gave monodisperse latex particles. After post-stabilization with cationic or non-ionic surfactants, the colloids were diluted in basic buffers with concomitant deprotection of the sulfhydryl groups. Therefore, coupling reactions on the latex beads were possible. Coupling conditions were determined with Ellmans reagent.14C iodoacetamide and anti C-reactive protein antibody Fab fragments were immobilized and finally, the immunological activity of the sensitized latex was assessed.

Styrene-terminated poly(vinyl alcohol) macromonomers: 1. Synthesis by aldol group transfer polymerization

Abstract Aldol group transfer polymerization of t-butyldimethylsilyl vinyl ether initiated by an unsaturated compound, p -formylstyrene, and catalysed by zinc bromide allowed synthesis of styryl-silylated poly(vinyl alcohol) macromonomers bearing an aldehyde end-function. Various macromonomers with average degrees of polymerization up to 28 were prepared and characterized according to different analytical methods, such as 1 H and 13 C nuclear magnetic resonance and ultra-violet spectroscopy and gel permeation chromatography. In order to improve the stability of the end-group, the aldehyde function was reacted with a silylketene acetal compound, 1-methoxy-2-methyl-1-trimethylsiloxypropene, which leads to a β-hydroxy ester end-group, much more stable towards side-reactions. Afterwards, the silyl ether side-groups were hydrolysed with tetrabutylammonium fluoride in order to obtain hydrophilic styryl-poly(vinyl alcohol) macromonomers.

Covalent grafting of polythymidylic acid onto amine-containing polystyrene latex particles.

The covalent grafting of a 35-base poly(thymidylic) acid(dT35) onto aminated polystyrene latex has been studied. The oligonucleotide was activated by 1,4-phenylene diisothiocyanate (PDC) prior to grafting reaction. The influence of various experimental conditions related either to the medium (pH, ionic strength) or to the latex (nature and surface charge density, presence of adsorbed nonionic surfactant) was studied. Discrimination between covalent grafting and adsorption was achieved by desorbing the non-covalently grafted dT35 induced by consecutive washings with a suitable buffer solution. The amount of covalently grafted oligonucleotide directly correlated to the concentration and accessible functional groups at the particle surface.

Radical-initiated copolymers of N-vinyl pyrrolidone and N-acryloxy succinimide: kinetic and microstructure studies

Abstract Kinetics of solution (co)polymerization of N-vinyl pyrrolidone (NVP, or V) and N-acryloxy succinimide (NAS, or A) have been investigated at 60°C in N, N-dimethylformamide with 4,4′-azobis(4-cyanopentanoic acid) as initiator. First, the k p √k i value for homopolymerization of A monomer was estimated as 0.87 10.5 mol−0.5 s−0.5. The comonomer feed composition was observed to have a strong effect on the overall copolymerization rate. Reactivity ratios of the binary system were determined to be rNAS = 0.27 ± 0.04 and rNVP = 0.01 ± 0.01, indicating a strong alternating tendency in the formed copolymer. Copolymers were then characterized as regards to composition (by ultraviolet spectrophotometry) and monomer sequence distribution (by 13C nuclear magnetic resonance spectroscopy). The presence of a small fraction of VVA triads was clearly evidenced which was not expected from simulation based on a terminal kinetic model; the occurrence of a more complex model has been discussed.

Surface Functionalization of Polystyrene Nanoparticles with Liposaccharide Monomers: Preparation, Characterization and Applications

Latex particles bearing carbohydrate species were prepared by emulsion copolymerization of styrene or methyl methacrylate with polymerizable liposaccharide surfactants; 11-(N-p-vinylbenzyl) amido undecanoyl maltobionamide (LIMA), 6-(2-methylpropenoyloxy)hexyl β-d-cellobioside (CHMA) and 10-(2-methylpropenoyloxy)decyl β-d-cellobiouronoside (CDMA). Due to their amphiphilic structure, these three monomers exhibit surface active properties in dilute solutions and mesomorphic properties in concentrated solutions. Their incorporation onto latex particles was performed according to a batch process or a seed polymerization process. The presence of the carbohydrate residues at the particle surface was directly observed by NMR. The potential application of these functionalized latexes in the biomedical diagnostic field was evaluated by studying the adsorption of bovine serum albumin, and by performing covalent binding of antibodies and single-stranded DNA fragments on their surface.

Preparation and properties of comb-like polymers obtained by radical homo- and copolymerization of a liposaccharidic monomer with styrene

A new disaccharide polymerizable surfactant 11-N-p-vinyl benzyl) amidoundecanoyl maltobionamide (LIMA, 6), was synthesized through a five-step procedure. It was found to exhibit a Krafft point of 52°C and a critical micelle concentration of 1.2 × 10−3 moll−1 at 55°C (as measured by surface tension and fluorescence techniques). Radical-initiated homo- and copolymerization of LIMA (M) with styrene (S) have been performed at 60°C in deuterated dimethyl sulfoxide using 2,2′-azobisisobutyronitrile as initiator. Kinetics were followed both by 1H n.m.r. and gas chromatography analyses providing kp /kt12 value for LIMA homopolymerization and a set of reactivity ratios such as: rM = 0.86 ± 0.1 and rS = 1.23 ± 0.09. Homopoly(LIMA) and copolymers with styrene were characterized as regards to average composition and molecular weight. Comb-like polymers were examined by X-ray analysis in the solid state; they were found to exhibit lamellar liquid-crystalline structures (smectic) resulting from the superposition of hydrophilic and hydrophobic layers.

Characterization of the Grafting Reaction Between Oligodeoxyribonucleotides and N-Vinyl Pyrrolidone /N-Acryloxy Succinimide Copolymers by Size Exclusion Chromatography and Free Solution Capillary Electrophoresis

Abstract The grafting reaction of oligodeoxyribonucleotides (ODN) on N-vinyl pyrrolidone (NVP)/N-acryloxy succinimide (NAS) copolymers has been investigated. First, NVP/NAS copolymers were prepared by free-radical polymerization in N,N-dimethylformamide (DMF); characterization of the monomer sequence distribution by 13C NMR suggested a strongly alternating structure. Low-conversion copolymers were synthesized using azeotropic composition (60% molar NAS) and various overall monomer concentrations. These model copolymers were characterized by light scattering and viscosity measurements in a DMF-water (90/10 volume ratio) mixture. The covalent attachment of ODN (constituted of 20 bases terminated with a primary amine linker) onto one selected copolymer (60% molar NAS) was then examined. Size exclusion chromatography (SEC) and free solution capillary electrophoresis (FSCE) were performed in order to analyse the reaction products and to calculate the yield of grafting. After optimization of the immobilization ...

Liquid-Crystalline Properties of Comb-Like Polymers Prepared by Homo and Copolymerization with Styrene of Liposaccharidic Monomers

ABSTRACT Liposaccharidic monomers with 3 types of polymerizable groups: methacrylate, methacrylamide and styrene and 3 types of saccharides: N-methyl-D-glucamide, Maltosamide and Cellobiose were synthesized and homo and copolymerized with styrene via radical initiation. Their liquid crystalline behaviour was studied by X-ray diffraction. All the homopolymers and copolymers were found to exhibit lamellar liquid-crystalline structures (Smectic) resulting from the superposition of hydrophilic and hydrophobic layers; however the type of Smectic mesophase and the organization of the molecules in the hydrophilic and hydrophobic layers was found to depend upon the nature of their saccharidic parts and that dependence is described and explained.