Rational design of the gram-scale synthesis of nearly monodisperse semiconductor nanocrystals

We address two aspects of general interest for the chemical synthesis of colloidal semiconductor nanocrystals: (1) the rational design of the synthesis protocol aiming at the optimization of the reaction parameters in a minimum number of experiments; (2) the transfer of the procedure to the gram scale, while maintaining a low size distribution and maximizing the reaction yield. Concerning the first point, the design-of-experiment (DOE) method has been applied to the synthesis of colloidal CdSe nanocrystals. We demonstrate that 16 experiments, analyzed by means of a Taguchi L16 table, are sufficient to optimize the reaction parameters for controlling the mean size of the nanocrystals in a large range while keeping the size distribution narrow (5-10%). The DOE method strongly reduces the number of experiments necessary for the optimization as compared to trial-and-error approaches. Furthermore, the Taguchi table analysis reveals the degree of influence of each reaction parameter investigated (e.g., the nature and concentration of reagents, the solvent, the reaction temperature) and indicates the interactions between them. On the basis of these results, the synthesis has been scaled up by a factor of 20. Using a 2-L batch reactor combined with a high-throughput peristaltic pump, different-sized samples of CdSe nanocrystals with yields of 2-3 g per synthesis have been produced without sacrificing the narrow size distribution. In a similar setup, the gram-scale synthesis of CdSe/CdS/ZnS core/shell/shell nanocrystals exhibiting a fluorescence quantum yield of 81% and excellent resistance of the photoluminescence in presence of a fluorescent quencher (aromatic thiol) has been achieved

PLoS Pathog

Cytomegalovirus (CMV) is a leading infectious cause of morbidity in immune-compromised patients. γδ T cells have been involved in the response to CMV but their role in protection has not been firmly established and their dependency on other lymphocytes has not been addressed. Using C57BL/6 αβ and/or γδ T cell-deficient mice, we here show that γδ T cells are as competent as αβ T cells to protect mice from CMV-induced death. γδ T cell-mediated protection involved control of viral load and prevented organ damage. γδ T cell recovery by bone marrow transplant or adoptive transfer experiments rescued CD3ε-/- mice from CMV-induced death confirming the protective antiviral role of γδ T cells. As observed in humans, different γδ T cell subsets were induced upon CMV challenge, which differentiated into effector memory cells. This response was observed in the liver and lungs and implicated both CD27+ and CD27- γδ T cells. NK cells were the largely preponderant producers of IFNγ and cytotoxic granules throughout the infection, suggesting that the protective role of γδ T cells did not principally rely on either of these two functions. Finally, γδ T cells were strikingly sufficient to fully protect Rag-/-γc-/- mice from death, demonstrating that they can act in the absence of B and NK cells. Altogether our results uncover an autonomous protective antiviral function of γδ T cells, and open new perspectives for the characterization of a non classical mode of action which should foster the design of new γδ T cell based therapies, especially useful in αβ T cell compromised patients

Qu est-ce qu un biomédicament en rhumatologie en 2013 ? (étude épistémologique)

Les biothérapies prennent une place croissante en rhumatologie, mais sont paradoxalement mal connues du grand public. Ce travail réalise l étude épistémologique de cette classe : son origine, ses mécanismes et modèles, son unité et son unicité. Il s attarde sur le choix étymologique du préfixe bios . A la fois réductionniste, et infiniment poétique, il est pourvoyeur d un imaginaire qu il faut connaitre pour comprendre les représentations des patients mais aussi la législation en cours. La variabilité intrinsèque du vivant entraine une distinction entre biosimilaire et générique. Comment alors concilier cette particularité législative avec le dogme de la non-brevetabilité du vivant ? De plus, ces thérapeutiques se basent sur le modèle immunologique du soi et du non-soi, dans la lignée du soi philosophique et psychanalytique du XXème siècle. Il permet de décrire l identité biologique avec plus de subjectivité et de temporalité que l identité génétique. Comment concevoir maladies auto-immunes et thérapeutiques immunomodulatrices ? Comment aider le patient à distinguer soi, identité biologique et individu? Leur application se fait selon les principes de l Evidence Based Medicine. Cet outil puissant a permis une grande amélioration médicale. Mais la connaissance de ses limites est importante. La médecine est une science humaine. En niant l importance de l expérience, le relationnel, la subjectivité, on réduit le médecin à un ordinateur. Les guidelines ne doivent pas décharger le praticien de son pouvoir décisionnel. Ce travail aide à comprendre la naissance d une classe thérapeutique et souhaite susciter la réflexion de chaque lecteur sur sa propre pratique médicale.Biologic agents are increasingly used in rheumatology. However, they are not well known by general public. This work is about epistemology of biologics: understanding theirs origins, mechanisms and models, their unity and uniqueness. We first consider the prefix bios which is both reductionist and incredibly poetic. But it mainly belongs to the vocabulary of imagination. Physicians must keep that in mind to understand the fears of their patients and legislation. The variability in living things explains the distinction between biosimilars and generic drugs. How to make compatible these definitions and the fact that living organisms are unpatentable? Moreover, biologics are based on the model of Self and not-self . This model is derived from the philosophical and psychoanalytic self of the XXth century. This self enables us to describe biological identity with more subjectivity and temporality than genetic identity. Thus, how to conceive autoimmune diseases and immunomodulation? How to help patients distinguish between the self, biological identity and the individual? At last, they are used according to principles of Evidence Based Medicine. This powerful tool has enabled great improvements. But we must know its limits. Medicine is a social science. Without experience, relational, subjectivity, doctor is reduced to a computer. Guidelines should not exonerate practitioner from his decision-making. This work helps to understand the origins of a therapeutic class, and invites the reader to reflect on his own medical practice.GRENOBLE1-BU Médecine pharm. (385162101) / SudocSudocFranceF

Rational design of the gram-scale synthesis of nearly monodisperse semiconductor nanocrystals

International audienc

Rational design of the gram-scale synthesis of nearly monodisperse semiconductor nanocrystals

International audienc

Rational design of the gram-scale synthesis of nearly monodisperse semiconductor nanocrystals

International audienc

Des m canismes articul s aux transformations du plan

SIGLEBSEB221293X / UCL - Université Catholique de LouvainBEBelgiu

Des mecanismes articules aux transformations du plan

SIGLEBSE B221293X / UCL - Université Catholique de LouvainBEBelgiu