Many bacterial cells are able to connect their metabolism with an electrode. Since the publication of the pioneering articles of 2002, the variety of bacterial species that have proved to be capable of extracellular electron transfer (EET) has been constantly expanding, and it now seems to be a current and ubiquitous lifestyle for microbial cells. EETs are most often correlated with essential metabolic pathways, particularly the respiratory metabolism of bacteria. The electrochemical approach of EETs is thus revolutionizing the understanding of microbial processes in most ecosystems. Numerous elements of the biomedical literature show that similar EETs, i.e. involving metabolic pathways, exist with human cells. For example, stem cells are commonly grown on conductive materials whose electrochemical properties drive differentiation into the different phenotypes. The exchange of extracellular electrons, in the form of "bioelectricity", is known to play essential roles in tissue repair or organ morphogenesis. In addition, human cells are eukaryotic cells and EETs associated with metabolic pathways have already been evidenced with yeasts, which are also eukaryotic cells. Despite the accumulation of indirect evidence of the occurrence of EETs with human cells, electrochemical approaches have never been implemented in this context before. Using the experience gained on microbial EETs by the consortium, the TECH project aims to build the electrochemical devices that will bring to light metabolic EETs with human cells. Three types of cells will be implemented: i) MRC5 lung cells, which have already given promising preliminary results, ii) progenitor cells from human adipose tissue, whose differentiation into white or beige adipocytes is related to the status of the respiratory metabolism and, iii) different cancer cell lineages, as the cancerous state of the cells could be correlated with dysfunction of the respiratory metabolism. The objective is to create the electrochemical reactors and electrode surfaces and to design the operating and analytical procedures that will allow EETs to be characterized during the development and/or differentiation of cells. The project will build synergy between two research groups belonging to the same laboratory, one mastering the EETs of microbial cells and the other the culture of human cells. In addition, two experts in the cellular metabolism of stem cells and cancer cells are associated as consultants. An interdisciplinary group will thus be created to combine skills in bioelectrochemistry, electroanalysis, cell adhesion, culture and cellular metabolism, and to couple electrochemical analysis methods with biochemical, biological and imaging techniques by microscopy. The project is submitted to the “Défi des autres savoirs” because the objective is to bring experimental evidence of a new paradigm. The project is applying for a modest budget because the objective is not to push investigations towards fundamental biology. This is a seminal project that intends to prove the concept of EET with human cells in order to convince the biomedical communities and to build further projects with them, having larger budgets on specific applied objectives. Demonstrating the occurrence of EETs with human cells will pave the way to new stem cell culture techniques, new tools for investigating cellular metabolisms and the pathologies, such as obesity and cancer, which are associated with their dysfunction and, we hope, will bring to light new therapeutic pathways.

Gas-solid fluidized beds are widely used in processes for energy. In all these processes the short-range (van der Waals forces) and medium-range (electrostatic) particle-particle interaction forces may have a strong influence and reduce the operation energetic efficiency. In these processes electrostatic charge generation is undesired and needs to be minimized as much as possible. Due to the very nature of gas-solid fluidization, which involves significant particle-particle and particle-reactor wall interactions the occurrence of electrostatic charge generation, is almost unavoidable. The overall process upsets associated with this phenomenon includes particle agglomeration, reactor wall fouling generated by particle-wall adhesion, defluidization and electrostatic discharge. Generation of high-voltage electrical fields could cause electrical interference, adversely affecting process instrumentation, physical shocks to operating personal and, most significantly, fires, explosions and therefore be a major hazard. The excess accumulation of electrostatic charges can have a severe impact on fluidized-bed dynamics, particle mixing, and fines elutriation which is a major cause of inefficiency. For particles the van der Waals forces can have an effect, as it is known for the cohesive powders (very fine particles), combined electrostatic charges. In that case, the short-range interactions lead to attractive forces between the particles and consequently modify the bubble size and thus the macroscopic behavior of a fluidized-bed reactor. Depending on the process requirements, the particle size of the solid material ranges from several microns to few millimeters. The objective of this project is twofold: to develop a new experimental technique to characterize the coupling between hydrodynamics of the gas-solid suspension and inter-particle short and medium-range action forces in fluidized bed reactor and to develop CFD models through a multi-scale approach to take into account these forces to simulate pilot plant reactor in order to design, to control the process and to optimize industrial fluidized bed reactors. In this project, multi-scale numerical and experimental approaches are coupled. Mathematical models to represent inter-particle forces at micro-scale will be implemented in the Euler-Euler formalism at macro-scale scale according to the kinetic theory of granular material. Euler-Euler simulations will be carried out and the results will be compared to the hydrodynamic measurements realized on a fluidized bed mock-up submitted to inter-particle short and medium-range action forces. The hydrodynamics measurements will be carried out according to a new technique never applied, to our knowledge, to fluidized bed in Europe. This technique, called Electrical Capacitance Volume Tomography (ECVT), provides 3D non-intrusive measurements of the flow structure. This technique will be coupled to measurements of electrostatic charge of the particles and the wall. When the Euler-Euler simulations are validated, numerical simulations on industrial scale will be carried out. This project involves the LGC and the IMFT, which have strong complementary approaches and skills on the fluidized bed. It allows the coordinator to develop a real autonomy and his own research activity. The originality of this project lies in several points: 1-Experimental measurements on particles with different electrostatic charges from particles of different size and different materials. 2-Local non-intrusive measurements of gas-particle suspension hydrodynamics by ECVT. 3-ECVT system applied to fluidized bed submitted to electrostatic and van der Walls forces. 4-Three dimensional numerical simulations of dense fluidized bed influenced by inter-particle forces. 5-Coupled experimental, theoretical and numerical approaches to study inter-particle short and medium-range action forces in fluidized bed coupled in the same project

The delivery of polynucleotides such as messenger RNA is now industrialized via vectorization in lipid nanoparticles. These nano-objects are nanocomposites in which the mRNA is condensed by complexation with a cationic lipid and coated with a shell of phospholipids and cholesterol. Their synthesis involves several rapid supramolecular assembly processes, including nanoprecipitation of hydrophobic lipids by solvent switching, electrostatic complexation of mRNA with cationic lipids to form a coacervate, and self-assembly of lipids. If the industrial production of these objects is now recorded, several challenges remain to be met to ensure their full development and generalization as a vaccine and therapeutic tool. Thus, their structure is complex, highly dependent on the formulations and the process, and there is no consensus. The efficiency of encapsulation and delivery remains very empirical and improvable. The process conditions, in particular the mixing of the species and the purification by filtration, are not optimized because the elementary mechanisms and their kinetics are not described. Storage conditions remain complex and the efficiency of encapsulation and delivery must also be improved. Finally, costs must be lowered. The Prosalide project targets to deliver a detailed understanding of the complete manufacturing chain thanks to a multidisciplinary team combining skills in physical-chemistry of assemblies, micro and millifluidics, filtration, hydrodynamics, microbiology, structural characterization. We will study in detail the assembly phenomena via the intensified establishment of phase diagrams. We will deploy a micro/millifluidic tandem allowing rapid mixing of solutions, in operando characterization and purification by tangential filtration. This approach will make it possible both to exploit the potential of microfluidics for the screening and characterization of mechanisms and that of millifluidics, which is the industrial production scale for these objects. We will propose new synthetic routes based on the use of composition sequences. Finally, we will quantify in detail the internal structure of the objects, their ability to encapsulate and deliver the polynucleotide, and their metastability. The PROSALIDE project will thus provide generic and free knowledge to understand the link between formulation, synthesis path, mesostructure, metastability, encapsulation and delivery.

Whether we use it to manufacture increasingly complex materials or because our bodies have developed solutions to resist it, drying is a ubiquitous process in our lives. Water has a preponderant role in our world and undergoes a crucial cycle based on phase transitions. Water evaporation occurs as soon as an aqueous system is placed in open air. From a thermodynamic perspective, the system is submitted to a water chemical potential difference and as a result a free energy field builds up at the air/liquid interface. Colloidal systems surround us since they contain a large diversity of species and can thus produce a large array of structures, properties and functions. Their versatility is ensured by weak interactions within the system, typical of soft matter. As a result, colloidal systems are extremely sensitive to free-energy gradients and will typically change dramatically their structuration with the local chemical potential. In project COATING, we investigate the feedback loop operating between transport and structuration, which are coupled during drying of an aqueous system. We will develop a generic experimental methodology to monitor composition and structuration gradients arising through evaporation and relate them to the system’s transport properties. The novelty of the approach rests on a fully quantitative characterization, the implementation of non-ideality in the description of drying, through thermodynamics, and an interdisciplinary approach encompassing drying of complex colloidal dispersions and biointerphases (lung, tear and skin films). We will use drying cells consisting of millifluidic capillary channels placed in a constant chemical potential difference, which is achieved by attaching the channel on one end to a solution reservoir and by exposing the other end to an air flow of controlled relative humidity. Aqueous colloidal systems placed in these cells will undergo controlled evaporation, which will correspond to the build-up of composition and structuration gradients. These gradients will be monitored through a combination of techniques such as Raman and optical microscopy and small-angle X-ray scattering microscopy. Transport will be monitored through mass loss experiments. Non-ideality will be quantified through experimental thermodynamics. This methodology will be applied to two important problems. Firstly, the transition in drying behaviour between simple and complex colloidal dispersions. This complexity notably corresponds to softer particles, colloidal surfaces grafted with polymeric layers or the addition of polymers of surfactant in the aqueous bulk. In practice, real systems of interest to the industry belong to this category of complex systems and this project will thus open new technological developments. Secondly, the study of three biointerphases shielding us from the outside air, the lung film, the skin outer layer and the tear film. We will investigate the structuration of these lipid-based films with relative humidity and notably evaluate the impact of humidity cycles for the lung and tear films and the influence of surfactants on skin. This will shed a new light on self-regulation mechanisms in biological membranes and open new strategies for curing related diseases and optimize formulations.

“Crystallization from solution must surely rank as the oldest unit operation, in the chemical engineering sense and it is known since the dawn of civilization” (Mullin, 1960). However, despite many experimental and theoretical developments, and despite its great interest in chemical, biological and natural processes, crystallization remains a puzzling phenomenon coupling several mechanisms (nucleation, growth, aggregation, agglomeration) occurring at different time and length scales. The crystallization process is still poorly understood mainly because crystal nucleation mechanisms are not clearly identified. The essential difficulties of studying nucleation and developing an accurate theory of the process arise from: 1/ the stochastic nature of nucleation, 2/ the fact that the objects involved during the process are small 3/ and are short lived (few ns). In the CNOC project, we propose a basic research, combining original theoretical and experimental approaches involving a theoretical physicist, bio-physicists and chemical engineers, to get a better understanding of the nucleation mechanism involved during crystallization. This project aims at a real breakthrough in our understanding of the nucleation process by associating modern experimental techniques (droplet microfluidics), powerful characterization technique (Small Angle X-Ray Scattering (SAXS) from a synchrotron source) and a new and original Monte Carlo simulation. The combination of microfluidics and SAXS enables in-situ measurements, at the nanoscale, of structures involved during the nucleation process and reduce the limit of time resolution at the micro/milli second range (due the spatial-to-time conversion offered by microfluidic devices). The theoretical description of nucleation from the Monte Carlo approach, enabling to treat complex and large systems (comparable to the one expected in microfluidics), will give a general picture of the mechanism involved during the nucleation. The project stretches over 48 months, includes five main tasks and gathers researcher from four French academic laboratories internationally renowned: the Laboratoire de Génie Chimique in Toulouse, the Institut des Biomolécules Max Mousseron in Avignon, the Laboratoire de Physique des Solides in Orsay and the European Molecular Biology Laboratory in Grenoble providing complementary specialties, domains of knowledge, know-how and expertise for the good development of this inter- and multidisciplinary project. Strong interactions between each participant will enable to design and build microfluidic chips compatible with intense X-ray radiations from a synchrotron source, to perform in-situ SAXS experiments for following molecular cluster in solution during the nucleation process, and to build a new theory of nucleation. The results obtained, from a carefully chosen biological macromolecule model, in this project will highlight mechanisms involved during the nucleation process by following experimentally and numerically the temporal evolution of size, number and shape of the molecular clusters in solution: from the formation of pre-critical nuclei (before nucleation) until the emergence of the crystal.