Abdelhamid Elaissari

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.

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.

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 ...