http://hdl.handle.net/2268.2/175 Wed, 19 Aug 2026 09:44:08 GMT 2026-08-19T09:44:08Z http://hdl.handle.net/2268.2/25436 Title: Development of thermoresponsive polyphosphate covalent hydrogels for biomedical applications Abstract: Les polyphosphates dégradables et biocompatibles suscitent un intérêt croissant en tant que candidats pour des applications biomédicales et pharmaceutiques, en particulier dans l’ingénierie tissulaire et la délivrance de médicaments. En effet, la chaîne latérale présente sur chaque atome de phosphore de l’unité répétitive influence les propriétés des polyphosphates, telles que l’hydrophilie . Lorsque la chaîne latérale est un groupement éthyle, le poly(phosphate d’éthyle) correspondant possède la propriété remarquable de thermorépondance, présentant une température critique inférieure de solubilité (LCST) dans l’eau, dans laquelle il est soluble jusqu’à une température d’environ 35 °C. Dans ce contexte, la synthèse d’hydrogels covalents à partir de ces polyphosphates thermosensibles paraît prometteuse, en particulier pour le développement d’implants à libération prolongée de protéines thérapeutiques, un domaine qui reste encore aujourd’hui un défi. En principe, à température ambiante (c’est-à-dire en dessous de la LCST), le gonflement de l’hydrogel permettrait le chargement de protéines par diffusion au sein du réseau de polyphosphate. Une fois placé à température corporelle, c’est-à-dire au-dessus de la LCST, la contraction et l’effondrement du réseau de polyphosphate piégeraient les protéines à l’intérieur, la libération étant alors contrôlée par la vitesse de dégradation des chaînes de polyphosphate. Ce travail décrit la synthèse de polyphosphates thermosensibles. Des copolymères de polyphosphate bien définis, contenant des unités d’éthylphosphate et des groupements photoréactifs, sont synthétisés en faisant varier la masse molaire, la composition et l’architecture. L’impact de ces paramètres macromoléculaires sur la LCST des copolymères est étudié. La photo-réticulation de ces copolymères en réseaux covalents est ensuite examinée. Enfin, le comportement thermosensible et les propriétés mécaniques des hydrogels covalents obtenus ont été étudiés .; Degradable and biocompatible polyphosphates are getting increasing attention as candidates for biomedical and pharmaceutical applications, particularly in tissue engineering and drug delivery. Indeed, the pendant chain present on each phosphorus atom of the repeating unit influences the polyphosphate properties, such as the hydrophilicity. Remarkably, when the pendant chain is an ethyl group, the corresponding poly(ethyl phosphate) exhibits a lower critical solution temperature (LCST) in water, where it is soluble up to a temperature around 35°C. In this scope, the synthesis of hydrogels from these thermosensitive polyphosphates appears promising, especially for developing carriers for the sustained release of therapeutic proteins, which remains a challenge today. In principle, at room temperature (i.e. below the LCST), swelling of the hydrogel would allow loading of proteins by efficient diffusion within the polyphosphate network. Once placed at body temperature, i.e. above the LCST, shrinkage and collapse of the polyphosphate network would trap the proteins inside, with release controlled by the rate of degradation of the polyphosphate chains. This work describes the synthesis of thermosensitive polyphosphate. Well-defined polyphosphate copolymers containing ethylphosphate and photoreactive groups are synthesised by varying the molar mass, composition and architecture. The impact of these macromolecular parameters on the LCST of the copolymers is studied. The photo-crosslinking of these copolymers into covalent networks is then investigated. The temperature responsive behaviour and the mechanical properties of the resulting hydrogels have been finally studied. Sun, 18 Jan 2026 23:00:00 GMT http://hdl.handle.net/2268.2/25436 2026-01-18T23:00:00Z http://hdl.handle.net/2268.2/25433 Title: Proteomic Characterisation of Venom-Antivenom Interactions using Magnetic Bead-Based Immunoprecipitation and LC-MS/MS Abstract: The diversity and complexity of venoms require a precise understanding of their interactions with antivenoms to identify which toxins are truly recognised and captured. This information is essential to assess the quality of available antivenoms, improve their production, and guide the development of next-generation antivenoms. In this context, it is important to have rapid, robust and reproducible in vitro methods capable of characterising these interactions in a reliable and directly actionable manner. In this thesis, venom-antivenom interactions were studied in the Echis romani - EchiTabG pair using a magnetic bead-based immunocapture approach, coupled to LC-MS/MS and LC-IMS-MS/MS. Biolayer interferometry (BLI) was also used to monitor interactions in real time and to estimate the apparent affinity between Echis romani venom and the specific antivenom, EchiTabG, a monospecific antivenom composed of whole ovine IgG. Two experimental strategies based on magnetic beads were compared at different stages of the project: tosyl-activated beads enabling covalent immobilisation of antibodies, and protein G beads enabling oriented immobilisation via the Fc region of IgG. For the protein G strategy, two capture formats were evaluated: a solution pre-complexation format, where venom and antivenom are incubated together before bead capture, and a format where IgG are first immobilised on the beads, then incubated with the venom. LC-MS/MS analyses highlighted a significant proportion of nonspecific capture with tosyl-activated beads, mainly associated with a background signal carried by PLA2s, consistent with nonspecific interactions between these proteins and the polystyrene surface of the beads. However, after exclusion of PLA2s during data processing, eluates obtained with EchiTabG showed toxin enrichment clearly higher than the controls, which supports the existence of a specific immunocapture. In contrast, immunocapture based on protein G beads showed little nonspecific signal, but the distribution of toxin families differed between the two capture formats. This difference probably reflects variations in complex formation in solution and in their recovery during capture via the Fc region. Based on these results, a bead saturation assay was set up by adding a “background” composed of proteins derived from Michigan Cancer Foundation-7 (MCF-7) cells, to reduce the nonspecific capture of PLA2s observed with tosyl-activated beads. Among the conditions tested, only the protein G strategy with prior antibody immobilisation showed behaviour compatible with saturation. BLI assays confirmed the specificity of the approach and showed binding dependent on venom concentration. Fitting a 1:1 binding model to this complex mixture enabled estimation of apparent values of k_on, k_off and K_D. Ultimately, this work provides a solid methodological basis for the antivenomics of E. romani by showing that a magnetic bead immunocapture, validated and complemented by BLI, makes it possible to link toxin recognition coherently to measurable affinity parameters, paving the way for a finer evaluation of antivenoms. Sun, 18 Jan 2026 23:00:00 GMT http://hdl.handle.net/2268.2/25433 2026-01-18T23:00:00Z http://hdl.handle.net/2268.2/25434 Title: Mémoire, Partim B : Method development for the analysis of halogenated volatile and semi-volatile persistent organic pollutants (chlorinated, brominated, and fluorinated) using GC-APCI-TIMS-TOFMS Abstract: Volatile and semi-volatile halogenated persistent organic pollutants (POPs) are routinely monitored by gas chromatography coupled to mass spectrometry (GC-MS). However, the reliable identification and quantification of trace-level compounds can remain challenging, notably due to coeluting isomers and isobars. Adding an extra separation dimension by ion mobility spectrometry can improve overall separation performance and provide complementary identification information through collision cross section (CCS) values. The aim of this Master’s thesis was to develop and evaluate a gas chromatography–atmospheric pressure chemical ionization–trapped ion mobility spectrometry-time-of-flight mass spectrometry (GC-APCI-TIMS-TOFMS) workflow for the analysis of halogenated compounds relevant to POP monitoring. In Chapter 1, a targeted GC-APCI-TIMS-TOFMS method was developed for three volatiles per- and polyfluoroalkyl substances (PFAS): perfluorooctyl ethanol, N-methylperfluoro-1-octanesulfonamide, and 2-(N-methylperfluoro-1-octanesulfonamido) ethanol. Instrumental parameters were optimized using a combination of one-factor-at-a-time testing and design of experiments, and fragmentation behavior was investigated under TIMS-off and TIMS-on conditions. A specific analytical issue, namely the broad ion mobility peak observed for N-methylperfluoro-1-octanesulfonamide, was explored and discussed. In Chapter 2, food matrices prepared within the TEQfood project were analysed. Quantification results for emerging brominated and mixed halogenated POPs obtained using GC-APCI-TIMS-TOFMS were compared with those obtained using the reference GC-EI-sector high-resolution mass spectrometry (HRMS) method. While GC-APCI-TIMS-TOFMS enabled congener determination, it showed lower sensitivity for some ultra-trace congeners and tended to overestimate concentrations relative to GC-EI-sector HRMS for a subset of analytes. Finally, Chapter 3 investigated pollutants sorbed on microplastics and macroplastics collected from rivers in Madagascar and from the Sambre River (Belgium), using targeted analysis with chlorinated biphenyl and polybrominated diphenyl ether standards combined with suspect screening to broaden chemical characterization. Overall, this work highlights both the potential and current limitations of GC-APCI-TIMS-TOFMS for halogenated POP analysis and identifies methodological improvements required to extend the approach towards broader PFAS coverage and robust screening workflows. Sun, 18 Jan 2026 23:00:00 GMT http://hdl.handle.net/2268.2/25434 2026-01-18T23:00:00Z http://hdl.handle.net/2268.2/25430 Title: Hammett acidity function for investigating ion pairing in an imidazolium-based ionic liquid Abstract: While ionic liquids were discovered more than a century ago, they have increasingly attracted significant interest in the last three decades due to their unique properties, such as non-volatility, non-flammability and recyclability. While these characteristics classify ionic liquids as “green solvents”, the property that has attracted the greatest attention is their tunability. Indeed, their physico-chemical properties can be finely adapted according to their cationic or anionic moieties, making ionic liquids particularly attractive for targeted applications. As applications for ionic liquids have expanded, the investigation of their fundamental properties remains essential for their use and understanding. This Master's thesis focuses on the acidity accessible in one of the most widely studied ionic liquids, namely 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIm][NTf2]). The acidity of this system was investigated through the Hammett acidity function, with peculiar attention to the influence originating from the colour indicator required for its determination. The acidity was probed using two spectroscopic methods: UV/Visible spectroscopy, which is the standard method for Hammett acidity determination, and Raman spectroscopy, which has recently been demonstrated as an alternative and viable approach. These two spectroscopic techniques led to different results, both in terms of acidity measured and influence of the indicator concentration, which was attributed to possible ion pairing in the solvent. Molecular solvents in which ion pairing is either well established or is negligible (glacial acetic acid and acetonitrile, respectively) were also studied to provide insights into the behaviour of this imidazolium-based ionic liquid. In addition to the influence of the indicator, the choice of acid added in the medium was also found to affect the acidity function, both in the ionic liquid and in glacial acetic acid, an effect attributed to ion pairing as well.; Les liquides ioniques ont, depuis plus de trente ans, attiré l’attention grâce à leurs propriétés, telles que leur non-volatilité, leur inflammabilité et leur recyclabilité, les rendant souvent considérés comme « solvants verts ». Cependant, la propriété attirant le plus d’intérêt dans le monde de la recherche est l’ajustabilité de leurs propriétés. En effet, l’introduction d’une modification dans l’anion ou le cation constituant le liquide ionique induit une modification de ses propriétés physico-chimiques, permettant l’utilisation de ces solvants dans différentes applications ciblées. Au regard de cela, l’étude et la compréhension de leurs propriétés fondamentales est de plus en plus importante. Dans ce mémoire, l’étude de l’acidité accessible dans un des liquides ioniques les plus répandus, le 1-butyl-3-méthyl-imidazolium bis(trifluorométhylsulfonyl)imide ([BMIm][NTf2]), a été effectuée. L’acidité est étudiée à travers la fonction d’acidité de Hammett, avec une étude particulière de l’effet de l’indicateur coloré nécessaire pour la mesure de cette fonction d’acidité. L’acidité a été déterminée à l’aide de deux méthodes spectroscopiques : la spectroscopie UV/Visible, méthode standard pour la détermination des fonctions d’acidité d’Hammett, ainsi que la spectroscopie Raman qui a récemment été démontrée comme une méthode alternative. Cependant, ces deux techniques spectroscopiques mènent à des résultats différents, à la fois pour la valeur d’acidité déterminée ainsi que l’influence de la concentration en indicateur, ce qui a été attribué à un effet de paires d’ions possible dans le liquide ionique. Afin de confirmer ou infirmer cet effet de paires d’ions, les fonctions d’acidité ont également été déterminées dans l’acide acétique glacial, un solvant dans lequel l’effet de paires d’ions est connu, ainsi que dans l’acétonitrile, dans lequel la formation de paires d’ions est limitée. L’impact de l’acidité sur le choix de l’acide ajouté dans le milieu a aussi été étudié, démontrant une différence dans l’acidité déterminée dans l’acide acétique glacial et le liquide ionique, effet qui a également été attribué aux paires d’ions. Sun, 18 Jan 2026 23:00:00 GMT http://hdl.handle.net/2268.2/25430 2026-01-18T23:00:00Z