PhD subjects

This thesis project aims to exfoliate new nanostructured architectures based on two-dimensional inorganic phases. These nanostructures will be designed for filtration devices and tested using our microfluidic platform. The target application is water purification and the selective separation of metal ions. The doctoral student will interact with chemists, physicists and electrochemists in a real multidisciplinary environment, on a fundamental research subject directly connected to application needs. Thus, during his thesis, the student will be exposed to a multidisciplinary environment and brought to carry out experiments in various fields such as inorganic chemistry, physical chemistry, micro / nano-fabrication and nano-characterization methods. In In this context, this project should potentially lead to significant societal benefits.

For the realization of the latter, he will have access to a very wide and varied range of equipment ranging from optical microscopes to the latest generation synchrotron (ESRF), including field effect or electron microscopes and galvanostats.

This thesis is therefore an excellent opportunity for professional growth, both in terms of your knowledge and your skills.

Nuclear Nuclear magnetic resonance (NMR) is a robust, non-invasive technique of analysis. It provides valuable information about chemical reactions, which can then be better characterised and optimised. However, NMR is poorly sensitive, and low-concentrated solutes, such as intermediates of reaction, may be unobservable by conventional NMR. One method known to drastically but temporarily increase the sensitivity of NMR is to create a hyperpolarised state in the system of nuclear spins, i.e. a polarisation much greater than that accessible with available magnetic fields. One hyperpolarisation method uses the specific properties of parahydrogen. A catalyst is required to add parahydrogen to a multiple bond or a metal.

The present thesis will investigate the combined contribution of (i) parahydrogen-based hyperpolarisation [1], (ii) the grafting of the appropriate catalyst onto nanoparticles [2], and (iii) a continuous analysis method [3] to detect and identify chemical intermediates, areas in which the laboratory has acquired experience. This subject involves a major investment in instrumentation, as well as skills in synthetic chemistry and NMR.

The thesis will be carried out at NIMBE, a joint CEA/CNRS unit at CEA Saclay. The hyperpolarised NMR and the synthesis will take place under the respective responsibility of Gaspard HUBER, from LSDRM, and Stéphane CAMPIDELLI, from LICSEN. These two NIMBE laboratories are located in nearby buildings.

References:
[1] Barskiy et al, Prog. Nucl. Magn. Reson. Spectrosc. 2019, 33, 114-115,.
[2] Hijazi et al., Org. Biomol. Chem., 2018, 16, 6767-6772.
[3] Carret et al., Anal. Chem. 2018, 90, 11169-11173.

The recycling and chemical recovery of plastics are necessary and crucialsteps to accelerate the transition to a circular economy and reduce the pollution associated with these materials.

The aim of this project is to develop catalytic systems for depolymerizing oxygenated and nitrogenous plastics into their monomers or derivatives (alcohols, amines, halides or even hydrocarbons). These methods, which enable the carbonaceous matter in polymers to be recovered under mild conditions in the form of chemical products useful to the chemical industry, are still underdeveloped and will, in the future, be virtuous processing routes for recycling certain plastics.

The aim of this doctoral project is to develop and use new metal molecular complexes (aluminium, zirconium, rare earths, etc.) and organic catalysts (boron-based), which

- are simple, inexpensive, recyclable and more selective than current catalysts (composed of iridium, ruthenium and boron), to depolymerize different types of plastics (polyesters, polycarbonates, polyurethanes and polyamides),
- allow, in the case of reductive catalysis, the use of hydrosilanes and hydroboranes, as well as the use of new reducing agents acting by transfer hydrogenation routes.

Finally, we will also consider the use of organic anhydrides to transform plastics into reactive organic compounds useful in organic chemistry.

Graphene as a constituent of graphite was close to us for almost 500 years. However, it is only in 2005 that A. Geim and K. Novoselov (Nobel Prize in 2010) reported for the first time the obtaining of a nanostructure composed by a single layer of carbon atom. The exceptional electronic properties of graphene make it a very promising material for applications in electronic and renewable energies.

For many applications, one should be able to modify and control precisely the electronic properties of graphene. In this context, we propose to synthesize chemically graphene nanoparticles and study their absorption and photoluminescence properties. We will focus on their solubilty in water in order to study potential applications in biology. This project will be developed in collaboration with Physicists so the candidate will work in a multidisciplinary environment.

Glycomics involves identifying oligosaccharides (OS) present in a biological fluid as a source of biomarkers for diagnosing various pathologies (cancers, Alzheimer's disease, etc.). To study these OS, sample preparation involves 2 key phases, enzymatic cleavage (breaking the bond between OS and proteins) followed by purification and extraction (separation of OS and proteins). However, the materials currently used in the protocols impose numerous manual and time-consuming steps, incompatible with high-throughput analysis.

In this context, the LEDNA laboratory specialized in materials science has recently developed a sol-gel process for the manufacture of Hierarchical Porosity Monoliths (HPMs) in miniaturized devices. These materials have provided a proof of concept demonstrating their value for the second stage of glycomic analysis, i.e. the purification and extraction of oligosaccharides. The LEDNA is now looking to improve the first step, corresponding to enzymatic cleavage, which has become a limiting factor in the glycomics analysis process. Functionalization of porous materials, in particular HPMs, with enzyme would enable simple sample preparation in just a few hours with a single step.

The aim of this thesis is therefore to show that the use of porous materials with a dual function - catalytic and filtration - applied to the preparation of samples for glycomic analysis is a relevant means of simplifying and accelerating glycomic analysis, as well as employing them in hospital-related studies to identify new biomarkers of pathologies.

The research project will involve developing a device incorporating porous materials with catalytic and filtration functions. Several aspects will be addressed, ranging from the synthesis and shaping of these materials to characterization of their textural and physico-chemical properties. Particular emphasis will be placed on enzyme immobilization. The most promising prototype(s) will be evaluated in a glycomic analysis protocol, verifying the oligosaccharide profiles obtained from human biofluids (plasma, milk). Physico-chemical characterization will involve a variety of techniques (SEM, TEM, etc.), as well as characterization of porosity parameters (nitrogen adsorption, Hg porosimeter). Oligosaccharides will be analyzed by high-resolution mass spectrometry (mainly MALDI-TOF).

For this multidisciplinary thesis project, we are looking for a student chemist or physical chemist, interested in materials chemistry and motivated by the applications of fundamental research in the field of new technologies for health. The thesis will be carried out in two laboratories, LEDNA for the materials part and LI-MS for the use of materials in glycomics analysis. The research activity will be carried out at the Saclay research center (91).