Raphaël Doineau

Développement de la technologie de microfluidique en gouttelettes pour le criblage phénotypique à haut débit à l'échelle de la cellule unique de répertoires de lymphocytes B: Le système immunitaire adaptatif joue un rôle de premier plan dans la défense contre les infections. La réponse humorale, impliquant la production d'anticorps, est un élément important de la réponse immunitaire adaptative. Au cours d'une infection, des cellules B spécifiques du système immunitaire prolifèrent et libèrent de grandes quantités d'anticorps qui se lient sélectivement à la protéine cible (antigène) trouvée sur le pathogène invasif, induisant la destruction du pathogène.Cependant, le système immunitaire ne répond pas toujours suffisamment efficacement pour détruire les agents pathogènes, et les mécanismes de tolérance empêchent la génération d'anticorps contre les protéines humaines - comme les marqueurs de surface cellulaire sur les cellules cancéreuses ou les cytokines impliquées dans des maladies inflammatoires et auto-immunes - qui pourraient être des cibles thérapeutiques importantes. Par conséquent, il existe un grand intérêt pour la recherche et le développement d'anticorps spécifiques qui peuvent être utilisés pour le traitement des patients par immunothérapie. En raison de leur grande affinité et de leur liaison sélective aux antigènes, les anticorps monoclonaux (mAbs) sont apparus comme des agents thérapeutiques puissants. Les anticorps monoclonaux dérivés de cellules B individuelles ont une séquence unique et présentent une affinité de liaison pour un antigène spécifique. Cependant, jusqu'à maintenant, la découverte des mAbs a été limitée par l'absence de méthodes à haut débit pour le criblage direct et à grande échelle de cellules B primaires non immortalisées pour découvrir les rares cellules B qui produisent des anticorps spécifiques d'intérêt clinique. Ceci est maintenant possible avec l'émergence et l'amélioration des méthodes de compartimentation in vitro pour l'encapsulation et le criblage de cellules uniques dans des gouttelettes picolitriques. Dans mon projet de doctorat, je décris le développement d'immunodosages et de dispositifs microfluidiques pour le criblage phénotypique direct de cellules individuelles à partir de populations de cellules B enrichies. Ce développement a permis une analyse détaillée de la réponse immunitaire humorale, avec une résolution à l’échelle de la cellule unique. C’est aussi un élément essentiel d'un pipeline de détection d'anticorps couplant le criblage phénotypique de cellules individuelles au séquençage d'anticorps sur cellules uniques. Il est maintenant possible, pour la première fois, de cribler des millions de cellules B individuelles en fonction de l'activité de liaison des anticorps sécrétés et de récupérer les séquences d'anticorps

Shaping piezoelectrics into innovative 3D microstructures is an emerging field, offering the potential to unlock new functionalities through topological engineering. Existing methods can create 3D piezoelectric composites and origami‐inspired structures, but they often reduce electromechanical resonance quality, especially when using organic elastic backbones with low mechanical quality factors. At the same time, 2D free‐standing piezoelectric nanomembranes used in acoustic wave resonators require thin film materials with low intrinsic stress to prevent device rupture as lateral dimensions increase. In this work, the first example of 3D self‐assembled piezoelectrics composed entirely of inorganic materials is presented. By precisely controlling mechanical stress and the nanomembrane release process, free‐standing nanomembranes are shaped into conformably stable tubular structures. The resulting rolled‐up piezoelectric (RUP) structures can be tuned in diameter, length, and winding number to optimize their performance for either actuation or sensing applications. Tubes up to 11 mm in length and 3.5 mm in rolling length are demonstrated, with functionality confirmed through 1‐port interdigital transducers (IDT) and 2‐port delay‐line architectures, integrating up to 10 mm ² of a free‐standing nanomembrane. Such devices can open new application possibilities for miniaturized medical devices, telecommunication, microfluidics, and energy harvesting, considering the large functional surface which adds another degree of freedom for topological design.

Understanding the impact of the aluminum zinc oxide (AZO) seed layer thickness on zinc oxide nanowires (ZnO NWs) growth is decisive in attaining high‐quality NWs with higher transparency and without cracking issues when using flexible substrates, especially for optoelectronic applications. Therefore, herein, ZnO NWs have been grown on various thicknesses of AZO films deposited onto flexible substrates (PET, PET/ITO (60 Ω sq⁻¹) and (200 Ω sq⁻¹)) through a simple, low‐temperature hydrothermal growth process. Based on AZO layer thickness, structural, optical, morphological, and topographical properties have been systematically investigated. The results demonstrate that 1) thicker AZO films (≈250 nm) increase the crystallinity of the ZnO NWs than thinner AZO films (≈200 and 100 nm). 2) ZnO NWs on the thicker AZO films with different ITO grades (60 or 200 Ω sq⁻¹) provide an optical bandgap value of 3.24–3.27 eV and offer good transmittance (>80%) in the visible range. 3) The AZO film thickness strongly influences ZnO NWs growth, especially NWs’ average diameter and density. 4) Annealing the samples at 100 °C after NW growth is pointless. Overall, the findings demonstrate efficient tuning of the ZnO NW properties that exhibit promising potentiality for perovskite solar cells, which have also been preliminarily tested.

In the rapidly advancing field of medical microrobotics, designing robots capable of addressing various challenges—such as imaging, biodegradation, and multifunctionality—is crucial. Departing from conventional research that often focuses on isolated aspects of microrobot functionality, this study presents an innovative approach to comprehensive microrobot design. Soft capsule microrobots that integrate capabilities such as magnetic navigation, autonomous maneuverability, in situ biodegradation, biosafe imaging, and drug delivery are reported. These microrobots are fabricated within the range of 20–120 μm, with a notable throughput of ≈10²–10³ microrobots per second. Furthermore, their locomotion performance has been demonstrated to remain stable for a period exceeding 10 h, all while employing real‐time optical closed‐loop control. The incorporation of ultrasound contrast agents not only amplifies imaging resolution but also ensures imaging contrast stability in a biological environment for over a period of 3 h. Second, the intentional integration of enzyme‐loaded nanometric polymersomes establishes a self‐contained, biodegradable system, accentuating the microrobots’ capacity to degrade without the addition of high enzyme concentrations. This integrated approach lays the groundwork for minimally invasive treatments toward personalized and targeted medicine.

Electron and hole transport layers (ETL and HTL) play an essential role in shaping the photovoltaic performance of perovskite solar cells. While compact metal oxide ETL have been largely explored in planar n-i-p device architectures, aligned nanowires or nanorods remain highly relevant for efficient charge extraction and directional transport. In this study, we have systematically grown ZnO nanowires (ZnO NWs) over aluminum-doped zinc oxide (AZO) substrates using a low-temperature method, hydrothermal growth (HTG). The main growth parameters were varied, such as hydrothermal precursors concentrations (zinc nitrate hexahydrate, hexamethylenetetramine, polyethylenimine) and growing time, in order to finely control NW properties (length, diameter, density, and void fraction). The results show that ZnO NWs grown on AZO substrates offer highly dense, well-aligned nanowires of high crystallinity compared to conventional substrates such as FTO, while demonstrating efficient FACsPb(IBr)₃ perovskite device performance, without the requirement of conventional compact hole blocking layers. The device performances are discussed based on NW properties, including void fraction and aspect ratio (NW length over diameter). Finally, AZO/ZnO NW-based devices were fabricated with a recent HTL material based on a carbazole moiety (Cz–Pyr) and compared to the spiro-OMeTAD reference. Our study shows that the Cz–Pyr-based device provides similar performance to that of spiro-OMeTAD while demonstrating a promising stability in ambient conditions and under continuous illumination, as revealed by a preliminary aging test.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Mining the antibody repertoire of plasma cells and plasmablasts could enable the discovery of useful antibodies for therapeutic or research purposes¹. We present a method for high-throughput, single-cell screening of IgG-secreting primary cells to characterize antibody binding to soluble and membrane-bound antigens. CelliGO is a droplet microfluidics system that combines high-throughput screening for IgG activity, using fluorescence-based in-droplet single-cell bioassays², with sequencing of paired antibody V genes, using in-droplet single-cell barcoded reverse transcription. We analyzed IgG repertoire diversity, clonal expansion and somatic hypermutation in cells from mice immunized with a vaccine target, a multifunctional enzyme or a membrane-bound cancer target. Immunization with these antigens yielded 100–1,000 IgG sequences per mouse. We generated 77 recombinant antibodies from the identified sequences and found that 93% recognized the soluble antigen and 14% the membrane antigen. The platform also allowed recovery of ~450–900 IgG sequences from ~2,200 IgG-secreting activated human memory B cells, activated ex vivo, demonstrating its versatility.

Studies of the dynamics of the antibody-mediated immune response have been hampered by the absence of quantitative, high-throughput systems to analyze individual antibody-secreting cells^1,2,3,4,5. Here we describe a simple microfluidic system, DropMap, in which single cells are compartmentalized in tens of thousands of 40-pL droplets and analyzed in two-dimensional droplet arrays using a fluorescence relocation-based immunoassay. Using DropMap, we characterized antibody-secreting cells in mice immunized with tetanus toxoid (TT) over a 7-week protocol, simultaneously analyzing the secretion rate and affinity of IgG from over 0.5 million individual cells enriched from spleen and bone marrow. Immunization resulted in dramatic increases in the range of both single-cell secretion rates and affinities, which spanned at maximum 3 and 4 logs, respectively. We observed differences over time in dynamics of secretion rate and affinity within and between anatomical compartments. This system will not only enable immune monitoring and optimization of immunization and vaccination protocols but also potentiate antibody screening^6,7.