Electrografting on nanoparticles: A new way toward polymer stabilized nanoparticle suspensions

Abstract: Nowadays, nanomaterials keep sparking interest tremendously because of the unique properties materials exhibit at the nanoscale. However, the stabilization of nanoparticles against aggregation is a prerequisite to exploit their remarkable properties, since they are very prone to aggregation. Moreover, even if many synthetic methods have been reported to prepare nanoparticles, achieving an efficient and convenient stabilization, without an alteration of the properties nanoparticles remains a challenge up to now. Therefore, a novel approach toward polymer stabilized metal based nanoparticles was developed using sonoelectrochemistry combined to electrografting to form a protective polymer layer in-situ directly on the generated particles. Nanopaticles prepared using this new approach were characterized. The influence of major experimental parameters on the characteristics of the produced polymer coated particles was also studied.Résumé: Les nanomatériaux suscitent énormément d´intérêt à cause des propriétés uniques des matériaux à l'échelle nanométrique. Toutefois, la stabilisation de nanoparticules contre l'agrégation est une condition préalable à l´exploitation de leurs propriétés remarquables, car elles ont tendance à s´agréger. En outre, même si de nombreuses méthodes de synthèse des nanoparticules ont été développées, une stabilisation efficace, aisée et sans altération des propriétés des nanoparticules reste un défi. Par conséquent, une nouvelle approche pour la préparation de nanoparticules à base de métaux métalliques stabilisées par un revêtement polymère a été développée en utilisant sonoélectrochimie combinée à l´électrogreffage pour créer un revêtement polymère in situ sur les particules produites. Des nanoparticules préparées en utilisant cette nouvelle approche ont été caractérisées. L'influence des paramètres expérimentaux majeurs sur les caractéristiques des nanoparticules stabilisées par un revêtement polymère obtenues a été également étudiée

Untersuchung der koordinationschemischen Eigenschaften von Myxochelin A und weiteren Catecholamid-Liganden mit den Metallen Fe(III), Ga(III), und Al(III)

The pKa-values of all phenolic hydroxy groups in the ligand Myxochelin A have been determined, by using potentiometric titrations of highly concentrated ligand ([L] = 10-20 mM) in aqueous DMSO solution (xDMSO = 0.2). In this medium, potassium methane sulfonate (KMS), could be used as inert salt with a concentration of 1 mol/L. Oxidation of the catecholates was inhibited by accurately replacing solved oxygen in solution with argon gas. Furthermore, potentiometric and spectrophotometric titrations were carried out using continuous techniques instead of discontinuous titrations. In this way, the coordination chemistry of Myxochelin A, Methyl-Myxochelin A and 2,3-dihydroxybenzamide with iron(III) could be studied in the pH-range from pH = 0 to pH > 12. Only complexes of 2-hydroxy-3-methoxybenzamide with iron(III) were to weak, so that iron hydroxide precipitated at pH > 6. At a pH of about 6, Myxochelin A starts to form 2:3-complexes (metal:ligand) with iron(III). The pFe-value of Myxochelin A was determined to be 25.9. The methylated derivate even forms 2:3-complexes with iron(III), the pFe-value is 23.7. Myxochelin A even forms 2:3-complexes with gallium(III) at pH > 8. In a 1:1-ratio of metal and ligand it seems, that Myxochelin A forms binuclear hydroxo-bridged complexes (M2L2(µ-OH)2) with the metals Fe(III), Ga(III) and Al(III).Über potentiometrische Titrationen partiell wässriger DMSO-Lösungen hoher Ligand-Konzentrationen ([L] = 10-20 mM, xDMSO = 0.2), konnten die pKS-Werte aller vier phenolischer Hydroxygruppen von Myxochelin A bestimmt werden. Kaliummethansulfonat (KMS) konnte in diesem Medium als Inertelektrolyt mit einer Konzentration von 1 mol/L eingesetzt werden. Die Komplexbildung von Myxochelin A, Methyl-Myxochelin A, 2,3-Dihydroxybenzamid und 2-Hydroxy-3-methoxybenzamid mit Eisen(III) wurde über potentiometrische und spektrophotometrische Titrationen im kontinuierlichen Verfahren (max. 24 h / Messung) unter Argon-Atmosphäre untersucht. Die Messungen wurden im pH-Bereich von pH = 0 bis pH > 12 (xDMSO =0.2, 1 M KMS) durchgeführt. Lediglich die Komplexbildung von 2-Hydroxy-3-methoxybenzamid mit Eisen(III) war zu schwach, sodass ab einem pH-Wert von ca. 6 Eisen(III)hydroxid als Niederschlag ausfiel. Myxochelin A bildet mit Eisen(III) bereits ab einem pH-Wert von ca. 6 stabile 2:3-Komplexe (Metall:Ligand). Der pFe-Wert von Myxochelin A wurde zu 25.9 berechnet. Das methylierte Derivat Methyl-Myxochelin A bildet ebenfalls 2:3-Komplexe mit Eisen(III), der pFe-Wert beträgt 23.7. Mit Gallium(III) bildet Myxochelin A ab einem pH-Wert von ca. 8 ebenfalls einen 2:3-Komplex. Im M:L-Verhältnis von 1:1 bilden sich mit allen untersuchten Metallen im Basischen sehr wahrscheinlich zweikernige Hydroxy-verbrückte Myxochelin A-Komplexe (M2L2(µ-OH)2)

Electrografting of thin polymer films: Three strategies for the tailoring of functional adherent coatings

Cathodic electrografting is an efficient technique to impart adhesion to poly(meth)acrylate coatings onto inorganic conducting surfaces. Although this technique was restricted for many years to very few monomers ((meth)acrylonitrile and (meth)acrylates) and to deposition of very thin polymer films, recent developments have overcome these limitations. First of all, classical controlled/living polymerization techniques have been combined with cathodic electrografting as a powerful strategy for tuning thickness, properties and reactivity of the chemisorbed organic films. Secondly, thanks to the successful electrografting of a new reactive monomer bearing an activated ester, electrografted surfaces are now available for further derivatization by a wide variety of nucleophiles. Finally, the electrografting process has been extended to the direct electrografting of reactive polymers, i.e. preformed polymers beating pendant acrylic functions, which opens the way to the grafting of, e.g., polycondensates

Human DEF6 deficiency underlies an immunodeficiency syndrome with systemic autoimmunity and aberrant CTLA-4 homeostasis

Immune responses need to be controlled tightly to prevent autoimmune diseases, yet underlying molecular mechanisms remain partially understood. Here, we identify biallelic mutations in three patients from two unrelated families in differentially expressed in FDCP6 homolog (DEF6) as the molecular cause of an inborn error of immunity with systemic autoimmunity. Patient T cells exhibit impaired regulation of CTLA-4 surface trafficking associated with reduced functional CTLA-4 availability, which is replicated in DEF6-knockout Jurkat cells. Mechanistically, we identify the small GTPase RAB11 as an interactor of the guanine nucleotide exchange factor DEF6, and find disrupted binding of mutant DEF6 to RAB11 as well as reduced RAB11+CTLA-4+ vesicles in DEF6-mutated cells. One of the patients has been treated with CTLA-4-Ig and achieved sustained remission. Collectively, we uncover DEF6 as player in immune homeostasis ensuring availability of the checkpoint protein CTLA-4 at T-cell surface, identifying a potential target for autoimmune and/or cancer therapy.Mechanistically, we identify the small GTPase RAB11 as an interactor of the guanine nucleotide exchange factor DEF6, and find disrupted binding of mutant DEF6 to RAB11 as well as reduced RAB11+CTLA-4+ vesicles in DEF6-mutated cells. One of the patients has been treated with CTLA-4-Ig and achieved sustained remission. Collectively, we uncover DEF6 as player in immune homeostasis ensuring availability of the checkpoint protein CTLA-4 at T-cell surface, identifying a potential target for autoimmune and/or cancer therapy

Branding in Pharmamarketing

Die vorliegende Arbeit beschäftigt sich mit dem Branding im Pharmamarketing. Konkret wird die Gestaltung und Form des externen Branding für verschreibungspflichtige Arzneimittel in Deutschland am Beispiel der Patienten-Kommunikations-Plattformen von Novartis für Atemwegserkrankungen behandelt