ED Sciences Chimiques
The merging of photoredox catalysis and supramolecular chemistry: application in C-H bond functionalization
by Victor CARRE (Institut des Sciences Moléculaires)
The defense will take place at 9h30 - Salle de conférence ISM 3e EST 351 Cr de la Libération, Bâtiment A12, 33405 Talence
in front of the jury composed of
- Jean-Marc VINCENT - Directeur de recherche - Institut des Sciences Moléculaires (Bat A12) - Directeur de these
- Samuel MARRE - Directeur de recherche - ICMCB – UMR5026 - CoDirecteur de these
- Tatiana BESSET - Directrice de recherche - Université de Rouen (Laboratoire COBRA, UMR6014) - Rapporteur
- Abderrahmane AMGOUNE - Professeur - Université Claude Bernard Lyon 1 (ICBMS, Bâtiment Edgar Lederer, UMR 5246) - Rapporteur
- Sébastien TILLOY - Professeur - Université d'Artois (UCCS, UMR 8181) - Examinateur
- Yannick LANDAIS - Professeur - Institut des Sciences Moléculaires (Bat A12) - Examinateur
The chlorine radical Cl• is a well-known and powerful reagent for abstracting hydrogen atoms from C(sp3)−H bonds, including that of methane. Recent developments in photoredox catalysis have shown that Cl• can be efficiently generated by photo-oxidation of the chloride ion, although requiring the use of photoredox catalysts whose excited states are highly oxidizing. The objective of the thesis was to develop an efficient and recyclable photocalytic system for the functionalization of alkanes, and in particular methane. Towards this goal, a dual catalysis process combining a photoredox catalytic cycle and a catalytic cycle allowing the generation of Cl• from Cl− was considered. In this context, fluorophilic derivatives of 4CzIPN, a photoredox catalyst belonging to the family of carbazole-dicyanoarene donor-acceptor compounds, were synthesized. It was shown that one of the electronically depleted derivatives, 8Rf8-4CzIPN, is not only a better photo-oxidant than the reference catalyst, but also becomes an excellent host for the chloride ion. Spectroscopic studies and DFT calculations revealed that the combination of these two properties made the 8Rf8-4CzIPN•Cl– supramolecular assembly extremely reactive for the photo-generation of Cl•. Catalysis studies showed that 8Rf8-4CzIPN•Cl– very efficiently photocatalyzed the alkylation of C(sp3)−H bonds proceeding by a Giese-type reaction. It was also shown that the photoredox catalyst could be partially recycled. Finally, preliminary studies were carried out in order to adapt the photocatalytic process for flow chemistry (microfluidics).
Synthesis of bioactive hydrogels for the control of stem cell differentiation: impact on bone tissue engineering
by Cristina LOPEZ SERRANO (Institut de Chimie & de Biologie des Membranes & des Nano-objets)
The defense will take place at 15h00 - Salle Manon Cormier Université de Bordeaux, 6 avenue Léon Duguit, 33600 Pessac
in front of the jury composed of
- Marie-Christine DURRIEU - Directrice de recherche - Université de Bordeaux - Directeur de these
- Susana DE MATOS FERNANDES - Professeure - Université de Pau et des Pays de l'Adour - Rapporteur
- Emmanuel PAUTHE - Professeur - CY Cergy Paris Université - Rapporteur
- Nick VIRGILIO - Professeur - Polytechnique Montréal - Examinateur
- Jean RUEL - Professeur - Université Laval - Examinateur
- Gaétan LAROCHE - Professeur - Université Laval - CoDirecteur de these
Mesenchymal Stem Cells (MSCs) are adult multipotent stem cells, widely used in tissue engineering thanks to their ability to differentiate into various cell lineages, making them suitable in many applications. However, tightly controlling their differentiation to yield a single cell type, such as bone cells, remains challenging. Achieving improved bone regeneration will likely involve mimicking the MSC's native microenvironment, known as the stem cell niche To achieve this, it is essential to develop advanced biomaterial scaffolds with properties that can be tuned to replicate the in vivo cellular environment on a cell culture plate. In this context, hydrogels have gained significant interest since they can mimic many aspects of native extracellular matrices (ECM). It is known that the in vitro differentiation of stem cells is affected by the stiffness and viscoelasticity of the substrate on and in which they are cultured. However further investigation is needed to understand the specific effects of matrix elasticity and viscoelasticity on osteogenic differentiation, as well as the interplay between these mechanical properties and the presence of bioactive molecules such as adhesion or differentiation peptides. In this context, our research challenge is to develop a material that encompasses the optimal properties to obtain osteogenic differentiation of MSCs. This thesis presents the development of poly(ethylene glycol) diacrylate (PEGDA) hydrogels with tunable mechanical properties, in terms of elasticity and viscoelasticity, and targeted biofunctionalization. Hydrogels with a broad range of compressive Young's moduli, from 2 to 128 kPa, were synthesized, successfully spanning the stiffness of most human soft tissues. The viscoelasticity of these materials was also tuned, from loss tangent values of 0.15 up to 0.35. The choice of technique to characterize the elasticity and viscoelasticity of the hydrogels is not trivial. There is no standard for the mechanical evaluation of hydrogels for biomedical applications and comparing results obtained with different techniques becomes challenging. To address this issue, we performed a comprehensive mechanical characterization of our hydrogels with multiple techniques (compression, rheology and AFM). Our findings reveal that while all methods produce consistent trends, each provides unique and complementary insights into the material's mechanical properties. The materials are functionalized by covalently grafting RGD and BMP-2 peptides, for adhesion and differentiation respectively. The biofunctionalization of the materials was verified via X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. hMSCs were cultured on different hydrogels and their osteogenic differentiation was evaluated via immunocytochemistry of key protein markers and qPCR. Our findings revealed that cells on stiff and viscoelastic hydrogels exhibited an overexpression of osteoblast and osteocyte markers. This suggests that the combination of the functionalization procedure with the mechanical properties of the hydrogel provides a potent approach to promoting the osteogenic differentiation of hMSCs.
ED Droit
The subjective private rights of individuals in administrative litigation
by Marina LIQUET (INSTITUT LÉON DUGUIT)
The defense will take place at 9h30 - 1K Pôle Juridique et Judiciaire 35 Place Pey Berland 33000 Bordeaux
in front of the jury composed of
- Aude ROUYERE - Professeure des universités - Université de Bordeaux - Directeur de these
- Xavier BIOY - Professeur des universités - Université Toulouse Capitole - Rapporteur
- Sébastien HOURSON - Professeur des universités - Université Paris-Nanterre - Rapporteur
- Cécile CASTAING - Professeure des universités - Université de Bordeaux - Examinateur
- Valérie REAUT - Première conseillère à la Cour administrative d'appel de Bordeaux - Cour administrative d'appel de Bordeaux - Examinateur
The aim of this study is to highlight the existence of administrative litigation concerning the subjective private rights of individuals and to measure its impact. The administrative judge is undoubtedly familiar with concepts of private law understood strictly as individual rights, such as the right to privacy, the right to one's image, the right to the presumption of innocence, or even the right to human dignity, the right to life, and so on. Traditionally, however, these personal rights are understood as fundamental rights or even as subjective public rights in administrative disputes. However, it is possible to maintain the privatist qualification of subjective private rights since the advent of a recent and unique configuration of administrative litigation, similar to judicial litigation. In this case, it is a confrontation between the rights of the private individual and a general interest, and no longer between the rights of a constituent and a public interest. The private individual, who is then no longer considered in his capacity as a constituent, can demand the protection of his rights from an administration that is merely an interlocutor. In addition, the results of our research show the multiple implications of the emergence of private law issues before the administrative judge, whether in terms of adapting the office of the administrative judge or in terms of functional rapprochement with the judicial judge.
ED Sciences Physiques et de l'Ingénieur
Control of organic semiconductor nanoparticles morphology for water-processable photovoltaic solar cells.
by Hugo LAVAL (Laboratoire de l'Intégration du Matériau au Système)
The defense will take place at 9h00 - Amphithéâtre 3 16 avenue Pey Berland, 33600 Pessac, France
in front of the jury composed of
- Isabelle SEGUY - Chargée de recherche - LAAS - CNRS - Examinateur
- Mariano CAMPOY-QUILES - Professeur - Materials Science Institute of Barcelona - Rapporteur
- Anne HEBRAUD - Maîtresse de conférences - ICPEES - CNRS - Rapporteur
- Francesca BRUNETTI - Professeur - University of Rome - Examinateur
- Serge RAVAINE - Professeur - Université de Bordeaux - Examinateur
In order to improve the sustainability of the organic photovoltaics, the use of toxic solvents for processing organic solar cells needs to be replaced by a cleaner alternative. The present thesis tackles this issue by exploring a way of replacing these solvents by water. As most organic semiconductors are not soluble in water, the strategy to overcome this constrain is to form nanoparticles from these materials, that are thus able to be dispersed in water. Two main methods are employed in the community to obtain such an aqueous dispersion, the miniemulsion and the nanoprecipitation. Nanoparticles synthesised with the latter method are known to present a more favourable internal morphology between the donor and acceptor materials as compared to the former method. As a result, water-processable organic solar cells prepared from nanoprecipitation demonstrate much higher efficiencies. The work undertaken in this thesis aims to understand and overcome the limitations arising from the internal morphology of the nanoparticles prepared by miniemulsion. In particular, we studied the influence of the interfacial energy between the donor and acceptor material on the nanoparticle internal morphology. Composite nanoparticles of PTQ10 associated with various acceptor small molecules were formed and studied with advanced microscopy techniques (STXM, AFM, cryo-TEM). The analysis showed that having a system with a low interfacial energy, such as PTQ10:Y6, is beneficial in obtaining nanoparticles with intimate morphology. As a result, organic solar cells fabricated with nanoparticles of PTQ10:Y6 have hence reached a power conversion efficiency of 9.98 %. A thermal treatment at high temperature was necessary in order to sinter the nanoparticles while keeping a favourable morphology and crystallinity. Such a high temperature is yet not suitable for an industrial process. To reduce this temperature, the alkyl chains length of both the donor and acceptor materials were found to play an important role. Through the screening of polymers having short and long alkyl chains associated with the acceptor material Y6, the polymer with the longer chains enabled processing at a lower temperature, achieving efficiencies exceeding 10%. Moreover, this work explores the link between nanomorphology and charge transport within nanoparticles by developing nanogap devices. Dielectrophoresis force has been successfully used to insert core-shell nanoparticles in the nanogap. This result shows that nanoparticle morphology and shell composition do not have a dramatic impact on the charge mobility within the nanoparticle or the overall performance of the solar cells.