The flow of two immiscible liquids or fluids in bounded systems where confinement
geometry varies can lead to drop or bubble formation. This phenomenon has been reported
in the context of oil recovery and named snap-off, or exploited for making emulsions,
and then foams, by using microfluidic systems, namely, microchannel emulsification or
step emulsification. We report a comprehensive experimental investigation of such an
emulsification process occurring at the end of a glass rectangular tube filled with oil and
immersed in a water bath. This allows us to clearly visualize the breakup event of the
dispersed phase liquid finger at the capillary’s end. Below a critical flow rate, the drop size
varies slowly with the flow rate and it is linked to the pinching time of the dispersed phase.
A semiempirical law that gives the resulting drop size as a function of fluid and geometrical
properties is proposed. However, this feature is altered for an aspect ratio of the rectangular
tube below 2.5 where the forming drop hinders the counterflow of the continuous phase
leading to larger drops. Then, above a critical flow rate, or capillary number that weakly
depends on the viscosity ratio of the two liquids, the neck adopts a quasistatic shape well
accounted for by a model based on a Hele-Shaw flow. In that case, drop formation is
driven by gravity and a transition from a dripping regime to a jetting regime is observed
at higher flow rates. Monodisperse foam can also be formed by injecting air. While the
overall dynamics of bubble formation shares similarities with an incompressible fluid, the
bubble size and the critical capillary number do not follow the same scaling laws.

Convective dispersion of solutes is inherent to flow in channels because of the nonuniformity of the velocity profile. When diffusion is negligible, for large particles for example,
the trajectory of particles can be solely described by a kinematic approach. Here, we
investigate such a phenomenon for micrometer-size beads flowing in a circular pipe. We
show that the presence of large bubbles, namely in the case of a segmented flow, either
prevents the convective dispersion or leads to the accumulation of particles at the rear of
the bubble moving in front. The destabilization of the initially homogeneous suspension
occurs when liquid inertia comes into play. Indeed, for moderate Reynolds number of
the particles, particles move away from the wall, thus exploring different flow lines that
finally impact the axial dispersion features. Moreover, since the bubbles impose an axial
boundary condition of the mean velocity, a net flux of particles directed along the flow
direction is built up above a critical particle Reynolds number. This work is motivated by
the understanding of the flow behavior of biological samples, and especially in the context
of cell encapsulation.

In many cell types, migration can be oriented towards a chemical stimulus. In mammals, for example, embryonic cells migrate to follow developmental cues, immune cells migrate toward sites of inflammation, and cancer cells migrate away from the primary tumour and toward blood vessels during metastasis. Understanding how cells migrate in 3D environments in response to chemical cues is thus crucial to understanding directed migration in normal and disease states. To date, chemotaxis in mammalian cells has been primarily studied using 2D migration models. However, it is becoming increasingly clear that the mechanisms by which cells migrate in 2D and 3D environments dramatically differ, and cells in their native environments are confronted with a complex chemical milieu. To address these issues, we developed a microfluidic device to monitor the behaviour of cells embedded in a 3D collagen matrix in the presence of complex concentration fields of chemoattractants. This tuneable microsystem enables the generation of (1) homogeneous, stationary gradients set by a purely diffusive mechanism, or (2) spatially evolving, stationary gradients, set by a convection-diffusion mechanism. The device allows for stable gradients over several days and is large enough to study the behaviour of large cell aggregates. We observe that primary mature dendritic cells respond uniformly to homogeneous diffusion gradients, while cell behaviour is highly position-dependent in spatially variable convection-diffusion gradients. In addition, we demonstrate a directed response of cancer cells migrating away from tumour-like aggregates in the presence of soluble chemokine gradients. Together, this microfluidic device is a powerful system to observe the response of different cells and aggregates to tuneable chemical gradients.

A molecularly imprinted polymer (MIP) was designed in order to allow the selective solid-phase extraction of carbamazepine (CBZ), an anticonvulsant and mood-stabilizing drug, at ultra-trace level from aqueous environmental samples. A structural analog of CBZ was selected as a dummy template and different synthesis conditions were screened. The selectivity of the resulting imprinted polymers was evaluated by studying the retention of CBZ in a solvent similar to the one used for the synthesis. The presence of imprinted cavities in the polymers was then demonstrated by comparing the elution profiles (obtained by using MIP and a non-imprinted polymer, NIP, as a control) of the template, of CBZ, and of a structural analog of CBZ. Then, the extraction procedure was further optimized for the treatment of aqueous samples on the two most promising MIPs, with special attention being paid to the volume and composition of the percolation and washing solutions. The best MIP provided a highly selective retention in tap water with 81% extraction recovery for CBZ in the elution fraction of the MIP and only 14% for NIP. The repeatability of the extraction procedure was demonstrated for both tap and river waters (RSD below 4% in river water) for the drugs CBZ, oxcarbamazepine, and one metabolite (carbamazepine 10,11-epoxide). A MIP capacity of 1.15 μmol g-1 was determined. Finally, an analytical procedure involving the MIP was developed allowing the detection of CBZ at a concentration level of only a few nanograms per liter in river water. The selectivity provided by the MIP resulted in a 3000-fold increase of the signal-to-noise ratio in LC/MS analysis as compared to the use of conventional sorbent. Graphical abstract.

The study of glycoproteins is a rapidly growing field, which is not surprising considering that approximately 70% of human proteins are glycosylated and that numerous biological functions are associated to the glycosylation. In this work, our interest focused on the heterodimeric human Chorionic Gonadotropin (hCG) glycoprotein that is the specific hormone of the human pregnancy, consisting of an α and a β subunit, so-called hCGα and hCGβ, respectively. This protein possesses a very high structural heterogeneity, essentially due to the presence of 8 glycosylation sites, but also other types of post-translational modifications. In this study, for the first time, the potential of hydrophilic interaction liquid chromatography (HILIC) was investigated to separate the intact hCG isoforms. Three different HILIC stationary phases were tested using an hCG-based drug as standard, a recombinant hCG. For each stationary phase, the effect of the initial mobile phase composition based on ACN/H2O mixture, the slope of the gradient, the content and nature of the acidic additive (formic acid and trifluoroacetic acid (TFA)), and the addition of a volatile salt (ammonium formate) on the retention and the resolution were studied. The best HILIC separation was obtained with the amide column and a mobile phase composed of water/ACN containing 0.1% of TFA. The repeatability in terms of retention times and peak areas was then assessed. Finally, the method was applied to the analysis of a second hCG-based drug obtained from urine of pregnant women. Both drugs gave chromatograms with more than 10 peaks. However, they were significantly different, which demonstrated the potential of HILIC method for hCG isoform fingerprinting

With the increasing impact of the global warming, occurrences of cyanobacterial blooms in aquatic ecosystems are becoming a main worldwide ecological concern. Due to their capacity to produce potential toxic metabolites, interactions between the cyanobacteria, their cyanotoxins and the surrounding freshwater organisms have been investigated during the last past years. Non-targeted metabolomic analyses have the powerful capacity to study simultaneously a high number of metabolites and thus to investigate in depth the molecular signatures between various organisms encountering different environmental scenario, and potentially facing cyanobacterial blooms.

In this way, the liver metabolomes of two fish species (Perca fluviatilis and Lepomis gibbosus) colonizing various peri-urban lakes of the Île-de-France region displaying high biomass of cyanobacteria, or not, were investigated. The fish metabolome hydrophilic fraction was analyzed by 1H NMR analysis coupled with Batman peak treatment for the quantification and the annotation attempt of the metabolites. The results suggest that similar metabolome profiles occur in both fish species, for individuals collected from cyanobacterial blooming lakes compared to organism from non-cyanobacterial dominant environments. Overall, such environmental metabolomic pilot study provides new research perspectives in ecology and ecotoxicology fields, and may notably provide new information concerning the cyanobacteria/fish ecotoxicological interactions.

In the present work, the first characterizations by Capillary Electrophoresis of the human Chorionic Gonadotropin (hCG) hormone at the intact level were carried out. hCG is a hetero-dimeric glycoprotein, specific to the human pregnancy, consisting of an α and a β subunit, so-called hCGα and hCGβ, respectively. hCG has 8 potential glycosylation sites leading to a high number of isoforms (including glycoforms and other post-translational modifications) that we are interesting to characterize. First, Capillary Gel Electrophoresis (CGE) was used to separate the isoforms of two hCG-based drugs: Ovitrelle® (recombinant r-hCG) and Pregnyl (hCG isolated from the urine of pregnant women, u-hCG). As expected, CGE led to a better resolution than SDS-PAGE and confirmed the large heterogeneity of hCG. Different CGE profiles were obtained for the two hCG-based drugs, varying in number of peaks, migration times, and peak intensities, thus demonstrating that the drugs contain isoforms, different in nature and proportion. This result was confirmed by Capillary IsoElectrophoretic Focusing (CIEF). The pI ranges of the hCG isoforms were found between 3.4 and 4.7, and 4.5 and 5.2 for r-hCG and u-hCG, respectively. This information was further used to develop the separation of the hCG isoforms by Capillary Zone Electrophoresis (CZE). The pH, the nature, and the concentration of the background electrolyte as well as the nature and the content of its organic modifier were optimized. The use of a coated capillary to avoid protein adsorption was also evaluated. The final CZE-UV method allowed distinguishing at least 6 peaks, corresponding to different hCG isoforms. To significantly improve the level of information obtained, the CZE instrument was then coupled by means of an electrospray ionization source to a triple quadrupole (TQ) mass spectrometer. Two detection strategies were used, one focusing on the lower m/z values (100-1000) in order to identify some sugar residues as diagnostic ions to confirm the presence of glycan chains, and the second focusing on the higher m/z values (1000-2000), corresponding to the multiple charged intact protein isoforms. For both approaches, the fragmentor and capillary voltage values were optimized. The composition and the flow-rate of the sheath liquid were then optimized for the strategy focusing on the higher m/z values in order to both increase the charge state of the ionized intact isoforms and the signal-to-noise ratio. The final method was used to compare the two hCG-based drugs, demonstrating the potential of the developed CZE-MS method for isoforms fingerprinting.

A molecularly imprinted polymer (MIP) was designed in order to allow the selective solid-phase extraction of carbamazepine (CBZ), an anticonvulsant and mood-stabilizing drug, at ultra-trace level from aqueous environmental samples. A structural analog of CBZ was selected as a dummy template and different synthesis conditions were screened. The selectivity of the resulting imprinted polymers was evaluated by studying the retention of CBZ in a solvent similar to the one used for the synthesis. The presence of imprinted cavities in the polymers was then demonstrated by comparing the elution profiles (obtained by using MIP and a non-imprinted polymer, NIP, as a control) of the template, of CBZ, and of a structural analog of CBZ. Then, the extraction procedure was further optimized for the treatment of aqueous samples on the two most promising MIPs, with special attention being paid to the volume and composition of the percolation and washing solutions. The best MIP provided a highly selective retention in tap water with 81% extraction recovery for CBZ in the elution fraction of the MIP and only 14% for NIP. The repeatability of the extraction procedure was demonstrated for both tap and river waters (RSD below 4% in river water) for the drugs CBZ, oxcarbamazepine, and one metabolite (carbamazepine 10,11-epoxide). A MIP capacity of 1.15 μmol g-1 was determined. Finally, an analytical procedure involving the MIP was developed allowing the detection of CBZ at a concentration level of only a few nanograms per liter in river water. The selectivity provided by the MIP resulted in a 3000-fold increase of the signal-to-noise ratio in LC/MS analysis as compared to the use of conventional sorbent. Graphical abstract.

Plastic pollution is a global problem since 2016 when its production reached 322 million tonnes, excluding fibers. Daily discharges of microplastics (MPs, defined as <5 mm in size) are estimated in the range of 50,000 up to 15 million particles, whereas no information on nanoplastic (NP, <100 nm) release is available yet. Different processes further degraded these materials producing more MPs and NPs. This review attempts to fill the void of information on the state-of-art analysis of MPs and NPs (recently identified as emerging contaminants) and provides a critical overview on modern instrumentation, newly developed workflows, and promising techniques for their characterization (Raman and FT-IR spectroscopies and microscopies, pyrolysis and thermal desorption gas chromatography, imaging techniques, etc.). Available analytical methods, validation as well as applications with cells have been taken into account. MP and NP sampling, identification, and characterization are discussed. Finally, recent applications to establish their occurrence in freshwater ecosystems and the effectiveness of the proposed remediation technologies are considered.

The blend MEA/MDEA (5/25%wt.) was studied on the LEMEDES-CO2 lab-scale pilot plant, with representative conditions of post-combustion CO2 capture for power generation during 900 h. CO2 loadings were determined and showed average values of 0.12 and 0.40 respectively for the lean and rich solvents. Stability of the two amines, namely MEA and MDEA, was monitored using ionic chromatography; results did not show any significant degradation of MDEA during the campaign, in contrary to MEA which showed a significant degradation in the range of 0.03 points per day. Analytical methods involving GC–MS and IC were developed in order to identify potential degradation products in the liquid phase of the solvent. Study of the gaseous emissions’ composition was also realized using sampling on different solid sorbents followed by thermal desorption and GC–MS analysis. A total of 22 compounds were listed including amines, organic acids, and pyrazines derivatives. 12 degradation products were found in the solvent itself and 11 in the treated flue gas among which MDEA, the constituent amine of the blend. A quantitative monitoring was carried out for formic and oxalic acids. Results showed concentrations reaching 500 mg/L for oxalic acid and 1400 mg/L for formic acid.