Montpellier, France


Montpellier, France
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Oukacine F.,Montpellier University | Oukacine F.,COLCOM SARL | Quirino J.P.,University of Tasmania | Garrelly L.,COLCOM SARL | And 3 more authors.
Analytical Chemistry | Year: 2011

A repeatable preconcentration electrophoretic methodology for the analysis of bacteria was developed. This method is based on an isotachophoretic mode coupled with a simultaneous hydrodynamic-electrokinetic injection in conditions of field-amplified sample injection. This electrophoretic method allows the quantification of Enterobacter cloacae (studied as a model of Gram negative bacteria) with a limit of detection of 2 × 10 4 cells/mL. With the optimized conditions, a preconcentration factor of about 500-fold was obtained as compared to a standard hydrodynamic injection. The RSD (n = 5) on the migration time and on the peak area were 3% and 5%, respectively. This capillary electrophoretic methodology has been applied for the quantification of microbes in natural water (river and natural spring waters). Filtration of the sample prior to injection was required to remove ions present in the water and to keep the field-amplified sample injection condition at the injection. Filtrated bacteria were then recovered in terminating electrolyte diluted 10 times with water. Good agreements were obtained between cellular ATP measurements and the proposed CE methodology for the quantification of bacteria in waters. © 2011 American Chemical Society.

Oukacine F.,Montpellier University | Oukacine F.,COLCOM SARL | Quirino J.P.,Montpellier University | Quirino J.P.,University of Tasmania | And 2 more authors.
Journal of Chromatography A | Year: 2012

The isotachophoretic analysis of different bacterial strains was studied using capillaries with different internal diameters from 50 to 250μm. Several injection modes were investigated and compared in order to improve the limit of detection of bacteria by capillary isotachophoresis. A system suitability test obtained from the separation voltage was developed to ensure reliable results. As expected, the use of wider bore capillaries improved the analytical sensitivity of the isotachophoretic method when compared to the 50μm capillary. With the optimized conditions, the isotachophoretic method presented in this work allows the quantification of Erwinia carotovora (Gram negative bacteria) with a limit of detection as low as ∼3000cellsmL-1. The proposed methodology does not require any additive in the electrolyte such a fluorescent or chromophoric dye to reach these limits of detection. © 2012 Elsevier B.V.

Cadiere A.,University of Paris Pantheon Sorbonne | Cadiere A.,French Institute of Health and Medical Research | Couturaud B.,Charles Gerhardt Institute | Boismard J.,University of Paris Pantheon Sorbonne | And 9 more authors.
Journal of Applied Microbiology | Year: 2013

Aims: Virus detection has often been difficult due to a low concentration in water. In this study, we developed a new procedure based on concentration of virus particles on an innovative support: poly-l-lysine dendrigrafts (DGL), coupled with directed nucleic acid extraction and real-time PCR quantification. Methods and Results: This method was evaluated using the bacteriophage MS2 as a model virus. This virus exhibited the size and structural properties of human pathogenic enteric viruses and has often been used to assess new supports of concentration. Moreover, this bacteriophage is also a faecal contamination indicator. In this study, many water filtration conditions were tested (volume of water, concentration, etc.), and more than 80% of bacteriophage were recovered after filtration on polymer, in most conditions. We demonstrated that the method was linear (slope = 0·99 ± 0·04 and Y intercept when x = -0·02 ± 0·28), valid (as manipulators, tested concentrations, volumes of sample and batch of polymer did not have any influence on concentration) and sensitive (allowing to concentrate up to 16 600-fold 1 l of sample and to detect and quantify down to 750 GC l-1 and 7500 GC l-1, respectively). Conclusions: To conclude, this support exhibits high interest to retain viruses and to allow to detect low concentration of virus in water. Significance and Impact of the Study: This study gives valuable advance in the methods of concentration and diagnosis of virus in water. © 2013 The Society for Applied Microbiology.

Maret B.,Max Mousseron Institute of Biomolecules | Maret B.,COLCOM SARL | Regnier T.,COLCOM SARL | Rossi J.-C.,Max Mousseron Institute of Biomolecules | And 3 more authors.
RSC Advances | Year: 2014

Herein, we demonstrate the effectiveness of the water-friendly S-sulphonate group as an alternative to traditional thiol protecting groups for subsequent deprotection-bioconjugation reactions, under conditions that are compatible with the use of biochemical samples. © 2014 The Royal Society of Chemistry.

Liu T.,Montpellier University | Oukacine F.,Montpellier University | Oukacine F.,COLCOM SARL | Collet H.,Montpellier University | And 3 more authors.
Journal of Chromatography A | Year: 2013

Click chemistry by copper-mediated azide/alkyne cycloaddition reaction is known as a very efficient synthetic pathway for chemical coupling and for surface functionalization. The attractiveness of this reaction is due to the selectivity of the reaction of azides and alkynes. Nevertheless, the control of the kinetics of the reaction and the characterization of the reaction products requires the use of adequate analytical techniques. This is especially the case for the monitoring of the functionalization of polymeric compounds and the control of the homogeneity of the chemical composition of these products. In this work, the third generation of dendrigraft poly-l-lysines derivatized with acetylenic groups was decorated with tryptophan-PEG-azide arms via triazole ring formation. Pressure assisted capillary electrophoresis was used to monitor the progress and the kinetics of the click chemistry reaction. As expected the click product was obtained with excellent yields within 20. min reaction time at room temperature. Diffusion coefficients and hydrodynamic radii of dendrigraft poly-l-lysines and their click reaction products were determined by Taylor dispersion analysis. Finally, capillary electrophoresis was found very useful to check the purity and the homogeneity in the chemical composition of the decorated structures. © 2012 Elsevier B.V.

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