Isabelle Leray

The monitoring of glyphosate (GlyP), the most widely used herbicide in the world, and aminomethylphosphonic acid (AMPA), its primary degradation product, in surface water is a public health concern due to their association with various diseases and carcinogenicity. In this study, we describe a novel terpyridine derivative incorporating recognition moieties specific for carboxylate, phosphonic acid and amine functionalities present in glyphosate and AMPA. The fluorescent molecular probe was synthesised and then activated through the formation of a Zn(II) complex. The photophysical properties of the probe and its complexation abilities with target analytes in aqueous solution (MeOH/HEPES buffer mixture) were characterized using both experimental approaches and computational modelling based on (TD-)DFT. The fluorescent molecular probe displayed high selectivity and sensitivity for both analytes, with detection limits of 51 nM for glyphosate and 70 nM for AMPA. The two different mechanisms for glyphosate and AMPA, respectively, complexation, with a high log(β) of 6.8, and covalent binding, even allowed for sequential detection of both analytes from the same sample. Owing to its efficiency and robustness, the molecular probe was successfully integrated into an embedded sensor system, whose performance was validated by analyzing real water samples (e.g. river water) with high recovery rates.

In this work, we prepare complex functional surfaces based on porphyrins by associating direct laser writing with nanometrology strategies. Precise microscale patterns of arbitrary geometry are obtained bearing different photophysical properties.

The precise monitoring of pH is critical in various applications, particularly in biology-related areas. In this work, we report the synthesis and characterization of a novel cyanine-based fluorescent pH sensor with a pK _a around 6. This pH-sensitive dye features a cyanine chromophore coupled to a piperazine moiety, which modulates the protonation equilibrium and thus the optical response. DTF calculation corroborates the changes in the photophysical properties upon protonation. Upon immobilization within a hydrophilic polymer matrix, the resulting fluorescent sensor is exhibited a pK _a around 4.5, facilitating ratiometric pH measurements for acidic media (for instance in food—examples given in milk and fresh yogurt). Importantly, this probe design allowed a less than 5 min response time to pH changes while avoiding cytotoxic effects towards E. coli. The development of such a fluorescent pH indicator is motivated by the growing need for optical monitoring tools capable of providing real-time, non-invasive readouts of pH dynamics in complex media and microfluidic systems. Graphical abstract

In this study, we have undertaken the development of two fluorescent sensors based on calixarene compounds for the purpose of detecting cesium in water. By introducing the sulfonate functional groups, we have considerably improved the water solubility of sensors, enabling complete dissolution of products in aqueous media and direct analysis of polluted water samples. Through rigorous experiments, we have demonstrated that the complexation of Cs⁺ ions with sensors 1 and 2 in water leads to a remarkable enhancement of fluorescence. This fluorescence enhancement serves as a reliable indication of cesium presence and allows for sensitive detection. To further advance the practical application of our sensors, we have successfully integrated calixarene sensors 1 and 2 into a microfluidic sensor chip. This integration has enabled real-time, on-line measurements and has resulted in the development of a portable detection device capable of detecting cesium ions in water samples at parts per billion (ppb) levels. This device holds great promise for environmental monitoring and assessment, providing a convenient and efficient solution for cesium detection. Our work represents a significant advancement in the field of cesium detection, displaying the efficacy of calixarene-based fluorescent sensors and their integration into microfluidic systems. The enhanced water solubility, fluorescence response, and portability of our detection device offers tremendous potential for applications in environmental monitoring, water quality assessment, and emergency response scenarios where rapid and accurate cesium detection is crucial.

Presynaptic glutamate replenishment is fundamental to brain function. In high activity regimes, such as epileptic episodes, this process is thought to rely on the glutamate-glutamine cycle between neurons and astrocytes. However the presence of an astroglial glutamine supply, as well as its functional relevance in vivo in the healthy brain remain controversial, partly due to a lack of tools that can directly examine glutamine transfer. Here, we generated a novel fluorescent probe that tracks glutamine in live cells, which provided direct visual evidence of an activity-dependent glutamine supply from astroglial networks to presynaptic structures under physiological conditions. This mobilization is mediated by connexin43, an astroglial protein with both gap-junction and hemichannel functions, and is essential for synaptic transmission and object recognition memory. Our findings uncover an indispensable recruitment of astroglial glutamine in physiological synaptic activity and memory via an unconventional pathway, thus providing an astrocyte basis for cognitive processes.

In the present work, we propose a new salicylaldehyde azine based water-soluble fluorescent sensor (PSSA – 4-propoxysulfonate salicylaldehyde azine) dedicated to aluminium(III) detection in aqueous solutions. The introduction of sulfonate functional groups provides the probe with enhanced water-solubility, which is crucial for the direct analysis of polluted samples. We proved that aluminium(III) complexation with PSSA in water induces an aggregation-induced emission enhancement (AIEE) process leading to the formation of well-defined dendritic structures which have been characterized by different analysis techniques (DLS, SEM, and FLIM). A limit of detection towards aluminium(III) of 153 nM has been determined, which is more than one order of magnitude below the World Health Organization (WHO) guideline (≈3.7 μM). Moreover, satisfactory selectivity for this compound has been demonstrated over a large variety of metal cations. Finally, PSSA has been introduced into a digital microfluidic sensor chip, thus providing a sub-micromolar portable detection device devoted to aluminium(III) polluted water samples.