In-line coupling of an aptamer based miniaturized monolithic affinity preconcentration unit with capillary electrophoresis and Laser Induced Fluorescence detection.

A composite 30-cm capillary was prepared. The head of the capillary was a 1.5-cm original and miniaturized aptamer-based monolithic affinity support that was in-line coupled to the end of the capillary used for capillary electrophoresis (CE) with laser induced fluorescence (LIF) detection. The device was used for the preconcentration, separation and quantification of ochratoxin A (OTA) as a test solute. The 1.5-cm preconcentration unit consists of a fritless affinity monolithic bonded with 5'-SH-modified oligonucleotide aptamers. A vinyl spacer was used for thiol-ene photoclick chemistry with a 5min irradiation at 365nm. Photografting allowed to confine the binding reaction to the desired silica monolithic segment, upstream the empty section of the CE capillary using an UV mask. The photografting procedure was optimized preparing 10-cm capillary monoliths for nano-LC. The retention factors of cationic solutes in ion-exchange nano-LC allowed to follow the aptamer binding on the monolith. The reproducibility of the photografting process was satisfactory with inter-capillary variation lower than 10%. The aptamer bonding density can be increased by successive graftings of 100µM aptamer concentration solution (5pmol/cm/grafting). The optimal conditions to successfully perform the in-line coupling (preconcentration, elution and separation of OTA) with the composite capillary were adjusted depending on individual requirements of each step but also insuring compatibility. Under optimized conditions, OTA was successfully preconcentrated and quantified down to 0.1pg (percolation of 2.65µL of a 40ng/L OTA solution). A quantitative recovery of OTA (93±2%) was achieved in a single elution of 30pg percolated OTA amount. The reproducibility of the overall process was satisfactory with a relative standard deviation lower than 10% with negligible non-specific adsorption. This device was applied for the preconcentration and analysis of OTA in beer and wine at the ppb level within a total analysis time of 30min.

Versatile ene-thiol photoclick reaction for preparation of multimodal monolithic silica capillary columns.

This paper presents a photografting process of monolithic silica capillary columns based on the ene-thiol click chemistry. This study is performed on a "generic" vinyl-functionalized silica monolith (Hmin 6±1µm). The photoclick reaction is investigated using different thiol monomers (octadecanethiol, cysteine and sodium mercaptoethanesulfonate) to prepare capillary columns dedicated to various chromatographic modes (reversed-phase, HILIC and strong cation exchange). Whatever the monomer used, the photografting reaction is achieved in less than 5min with a relatively high thiol monomer content. This allows preparing highly retentive and efficient monolithic columns while avoiding polymerization and/or column clogging. In addition to the aforementioned properties (duration, versatility, efficiency), this photo-triggered chemical reaction allows addressing several appropriate surface functionalizations inside a single monolithic column in order to prepare nanovolume multimodal capillary columns. A multimodal biphasic monolithic column with a 1cm length cation-exchange segment followed by a 9cm length reversed-phase segment (SCX-RP) is prepared through two successive photografting reactions using a UV-mask to localize the reactions. This multimodal biphasic column is investigated using a model sample for the selective fractionation and separation of cationic and neutral compounds and is applied to the on-line preconcentration and separation of ß-blockers.

"Thiol-ene" photoclick chemistry as a rapid and localizable functionalization pathway for silica capillary monolithic columns.

Herein, we report the "ene-thiol" photografting of 1-octadecanethiol onto vinyl pre-functionalized silica monolith to prepare clicked reversed-phase silica monolithic columns with high permeability and performances. The experimental conditions (concentration of thiol in solution, irradiation duration) are optimized with respect to highest retention and methylene selectivity, i.e. to the highest surface coverage of the monolith. It is demonstrated that an irradiation duration of 5min is enough with a 0.8M concentration of 1-octadecanethiol in solution or that it may be replaced by successive irradiations at a lower ODT concentration (0.19M) with renewing of the solution between the illuminations. Retention factors as high as those obtained with standard silanization are reached while keeping the intrinsic monolith permeability and efficiency (160,000plates/m in nano-LC at 0.7mm/s). The absence of polymerization, in the "ene-thiol" version, is demonstrated. Indeed, the steric selectivity of our clicked-material is characteristic of monolayer-like functionalized silica and significantly lower than the steric selectivity measured on polymeric-like functionalized silica.

Photopolymerization of acrylamide as a new functionalization way of silica monoliths for hydrophilic interaction chromatography and coated silica capillaries for capillary electrophoresis.

A simple, rapid and localizable photochemical process for the preparation of hydrophilic coated capillary and silica-based monolithic capillary columns is described. The process involves the free radical polymerization of acrylamide monomers onto acrylate pre-activated silica surface triggered by UV photoinitiation. The experimental conditions (monomer content, time of irradiation) were optimized on silica monolithic columns by monitoring the evolution of the chromatographic properties (retention, permeability, efficiency) in HILIC mode using a set of nucleosides as test solutes. Compared to thermal polymerization process, the photoinitiation allows the preparation of highly retentive and efficient HILIC monolithic columns in less than 10min of irradiation. This process was then successfully applied to the surface coating of fused silica capillary walls. In addition to its relative high stability and ability to reduce the electroosmotic flow, this polyacrylamide coating is localizable. Benefits of this localizable photochemical process are highlighted through the conception of an in-line integrated bimodal microseparation tool combining a SPE preconcentration step on a photografted silica monolith and an electrokinetic separation step in a polyacrylamide photopolymerized capillary section. Two neuropeptides are used as model solutes to illustrate the suitability of this approach.

A multibiomarker approach in juvenile turbot, Scophthalmus maximus, exposed to contaminated sediments.

Juvenile turbot were exposed in laboratory conditions to a mixture of chemical contaminants associated with harbour and estuarine sediments for seven and 21 days. Several molecular biomarkers of exposure were then measured in fish liver: two biotransformation parameters [ethoxyresorufin-O-deethylase (EROD) and phase II glutathione S-transferase (GST) activities] and an antioxidant enzyme activity [catalase (CAT)]. Modifications at the histological level were analysed by the measurement of the number and size of melanomacrophage centres (MMCs) and disturbances to the immune function by the measurement of cytokine transforming growth factor-beta (TGF-ß) and development of the thymus. The responses of these molecular and immunological biomarkers were correlated with metal and PAH concentrations measured in sediments and with the physiological performance of turbot analysed in a previous study on the same fish (growth rates, condition factor K, RNA:DNA ratio and lipid index). While no difference was found in thymus analysis, some molecular and immunological responses were observed in fish exposed to contaminated sediments. Weak relationships between molecular biomarkers' responses and PAH concentrations were recorded, while their responses were significantly correlated with some metals. MMC and aggregates were weakly related to chemical contaminants whereas some significant correlations were found between TGF-b1 responses and some metal concentrations. However, molecular and immunological biomarkers were weakly related to fish physiological damages since low responses were observed in the condition which led to the lowest growth and condition indices. These data suggest the complexity of cause-effect relationships between exposure to pollutants, metabolisms and health damages. Precautions should be considered in the use of molecular and immunological biomarkers alone in biomonitoring programs. Their complementary use with physiological biomarkers, such as fish growth and condition indices, could improve their utilisation.

From alpha-carbamoyl-alpha-cyanooxiranes to 3-halogenopyruvamides.

The crystal structures of the first stable alpha-diol from the alpha-halogenopyruvamide series, 3-chloro-2, 2-dihydroxy-3-phenylpropanamide, C(9)H(10)ClNO(3), and three products [3-(4-chlorophenyl)-2-cyano-2,3-epoxypropanamide, C(10)H(7)ClN(2)O(2), 3-bromo-2-cyano-2-hydroxy-3-p-tolylpropanamide, C(11)H(11)BrN(2)O(2), 3-bromo-2-oxo-3-p-tolylpropanamide, C(10)H(10)BrNO(2)] obtained during the systematic synthesis of alpha-halogenopyruvamides are reported. The crystal structures are dominated by hydrogen bonds involving an amide group. The stability of the geminal diol could be ascribed to hydrogen bonds which involve both hydroxyl groups.

[Gastric leiomyosarcoma. Contribution of imaging to the diagnosis. Report of 2 cases]. / Les léiomyosarcomes gastriques. Apport de l'imagerie au diagnostic. A propos de deux cas.

Leiomyosarcomas, are rare gastric tumors with a tendency for extraluminal growth. In relation to two new cases, the authors report the various features and show the predominant value of computed tomography for the diagnosis.

[Giant diverticulum of the colon. Apropos of 2 cases]. / Le diverticule géant du côlon. A propos de 2 cas.

Two cases of giant colonic diverticulum are reported. Clinical and radiological features are described. Surgery is absolutely necessary.