Metal oxide nanoparticles for the decontamination of toxic chemical and biological compounds.

For several years, the international context is deeply affected by the use of chemical and biological weapons. The use of CBRN (Chemical Biological Radiological Nuclear) threat agents from military stockpiles or biological civilian industry demonstrate the critical need to improve capabilities of decontamination for civilians and military. Physical decontamination systems that operate only by adsorption and displacement such as Fuller's Earth, have the drawback of not neutralizing hazardous agents, giving place to cross contaminations. Consequently, the development of a formulation based on metal oxide nanoparticles attracts considerable interest, since they offer physicochemical properties that allow them to both adsorb and degrade toxic compounds. Thus, the aim of this study is to found metal oxide nanoparticles with a versatile activity on both chemical and biological toxic agents. Therefore, several metal oxides such as MgO, TiO2, CeO2, ZnO and ZrO2 were characterized and their decontamination kinetics of less-toxic surrogate of VX, paraoxon, were studied in vitro. To determine the antimicrobial activity of these nanoparticles, simulants of biological terrorist threat were used by performing a 3-hours decontamination kinetics. This proof-of-concept study showed that MgO is the only one that exhibits both chemical and antibacterial actions but without sporicidal activity.

Development of a new in-line coupling of a miniaturized boronate affinity monolithic column with reversed-phase silica monolithic capillary column for analysis of cis-diol-containing nucleoside compounds.

In-line coupling of capillary columns is an effective means for achieving miniaturized and automated separation methods. The use of multimodal column designed to allow the direct integration of a sample preparation step to the separation column is one example. Herein we propose a novel in-line coupling at the capillary scale between a boronate affinity capillary column (µBAMC unit) and a reversed-phase separation column. This has been made possible due to the elaboration of a new and efficient µBAMC unit. A thiol-activated silica monolithic capillary column was functionalized through thiol-ene photoclick reaction. This simple and fast reaction allows to prepare stable µBAMC units having grafting densities of 1.93 ± 0.17 nmol cm-1. This grafting strategy increases the surface density by a factor 4 compared to our previous strategies and opens the frame to in-line coupling with reversed-phase capillary column. Proof of concept of the in-line coupling was done by coupling a 1-cm length µBAMC unit to a 7-cm length reversed phase capillary column. The conditions of loading, elution and separation were optimized for cis-diol nucleosides analysis (uridine, cytidine, adenosine, guanosine). A loading volume (at pH 8.5) of up to 21 hold volume (i.e 1 µl) of the µBAMC unit can be loaded without sample breakthrough. For the least retained nucleoside (uridine) a limit of detection of 50 ng mL-1 was estimated. Elution and full separation of the four nucleosides was triggered by flushing the multimodal column with an acetic acid (50 mM) / methanol (98/2, v/v) mobile phase.

Evaluation of boronate affinity solid-phase extraction coupled in-line to capillary isoelectric focusing for the analysis of catecholamines in urine.

In this study, a new miniaturized and integrated analytical system was developed based on the in-line coupling of boronate affinity solid phase extraction with capillary isoelectric focusing separation and UV detection. This original coupling takes advantage of the selective enrichment of cis-diol-containing compounds using a boronate affinity sorbent and the exceptional focusing features of isoelectric focusing process. Such coupling has been used for preconcentration/purification and separation of urinary catecholamines (dopamine, adrenaline and noradrenaline) as proof of concept. Poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolithic capillary column (8 cm) was chosen as solid phase extraction support due to its good chemical stability and its easy and versatile surface functionalization. Characterization of the miniaturized boronate affinity monolith column (µBAMC) was done by frontal affinity chromatography. An active-site amount of about 0.16 nmol cm-1 (75 µm i. d.) of phenyl boronic acid groups and Kd values ranging from 224 to 106 µM were obtained for catechol and catecholamines. A high loading volume (up to 15 times the affinity column volume) can be introduced with quantitative recovery yields. Optimization of the in-line coupling concerned the adaptation of (i) the µBAMC volume, (i.e. length and inner diameter of the monolithic column) for loading of large sample volumes and (ii) the CIEF experimental conditions. The ampholyte mixture was adapted (i.e. nature and concentration of carrier ampholytes, volume of sacrificial electrolytes) in order to ensure elution and separation of catecholamines and to decrease limit of detection down to 10-20 ng ml-1. The optimized method was applied to analyze urine samples.

Development and application of a new in-line coupling of a miniaturized boronate affinity monolithic column with capillary zone electrophoresis for the selective enrichment and analysis of cis-diol-containing compounds.

An integrated, miniaturized and fully automated system was developed for the analysis (preconcentration/purification, separation and detection) of cis-diol containing molecules in complex matrices. This innovative in-line coupling system was achieved via the in-situ and localized synthesis of a short segment of silica-based monolith at the inlet of a 75-µm inner diameter fused silica capillary. The monolithic segment was locally functionalized with an acrylamide derivative of phenylboronic acid by free radical photopolymerization within 10min of irradiation time. Efficiency of the photopolymerization reaction was followed by frontal affinity chromatography of 1,2-dihydroxybenzene (catechol) as cis-diol model solute. An active-site amount of 0.43nmolcm-1 (9.8nmolµL-1) of phenylboronic acid moieties was obtained, with a Kd value of about 290µM close to reported value for the phenyl boronate-catechol complex. The optimal conditions of use of the miniaturized boronate affinity monolithic column (µBAMC) were determined and adapted to the in-line coupling with capillary electrophoresis. Catechol was specifically preconcentrated in a pH 8.5 phosphate buffer/MeOH (80/20, v/v) mixture. A volume up to 20 times the monolith volume can be percolated with a quantitative recovery yield. Three catecholamines were purified, preconcentrated and in-line separated. Elution from the µBAMC was performed with a small plug of acidic solution, allowing field amplified sample stacking of solutes within the plug before their in-line electrophoretic separation at pH 8.75. This unique in-line coupling was successfully used for the fully automated analysis of catecholamines neurotransmitters in urine samples, highlighting the purification efficiency of the µBAMC and the potential of such a fully integrated approach. In addition to the low sample volume required (less than 2µL), the limits of detection (LOD) accomplished with this coupling were estimated at 9.0, 9.5 and 4.8ngmL-1 for dopamine, adrenaline and noradrenaline respectively, which improves the LOD of theses solutes compared to other CE methods.