Amino functionalized thin films prepared from Gabriel synthesis applied on electrografted diazonium salts

International audienceA new diazonium salt bearing an aliphatic primary amine protected with a phthalimide group has been synthesized and isolated from the reaction of the corresponding aniline derivative with NOBF4 in acetonitrile. Electrochemical grafting of this compound in potentiodynamic conditions on vitreous carbon or on gold form thick, stable, adherent and insulating polyphenylene-like films on the electrode surface. Treatment with hydrazine of these polymers cleaves the imide functions to release amine groups prone to subsequent immobilization of molecules, biomolecules or particles via a covalent amide linkage. That primer polyphenylene-like layer establishes a good electrical communication between the surface of the electrode and the immobilized probe

How do surface properties of nanoparticles influence their diffusion in the extracellular matrix? A model study in Matrigel using polymer-grafted nanoparticles

International audienceDiffusion of nanomedicines inside the extracellular matrix (ECM) has been identified as a key factor to achieve homogeneous distribution and therefore therapeutic efficacy. Here, we sought to determine the impact of nanoparticles surface properties on their ability to diffuse in the ECM. As model nano-objects, we used a library of gold nanoparticles grafted with a versatile polymethacrylate corona which enabled to modify the surface properties. To accurately recreate the features of native ECM, diffusion studies were carried out in a tumor-derived gel (Matrigel®). We developed two methods to evaluate the diffusion ability of NPs inside this model gel: an easy to implement one based on optical monitoring and another one using small-angle X-ray scattering (SAXS) measurements. Both enabled to determine the diffusion coefficients of NPs and compare the influence of their various surface properties, while the SAXS technique also allowed to monitor the NPs structure as they diffused inside the gel. Positive charges and hydrophobicity were found to particularly hinder diffusion, and the different results suggested on the whole the presence of NPs-matrix interactions, therefore underlying the importance of the ECM model. The accuracy of the tumor-derived gels used in this study was evidenced by in vivo experiments involving intratumoral injections of NPs on mice, which showed that diffusion patterns in the peripheral tumor tissues were quite similar to the ones obtained within the chosen ECM model

Facile and tunable functionalization of carbon nanotube electrodes with ferrocene by covalent coupling and [pi]-stacking interactions and their relevance to glucose bio-sensing

International audienceFerrocene derivatives were [pi]-stacked or covalently grafted onto a film of carbon nanotubes (CNTs) in order to determine the most effective method to immobilize redox centres on those high-surface area electrodes for sensors or catalytic applications. The immobilization of the ferrocene moiety via [pi]-[pi] interactions was done with a new ferrocene derivative bearing a pyrene group. The covalent grafting on the film of CNTs was achieved in two steps via the electroreduction of an aminoethylbenzenediazonium salt followed by post-functionalization with an activated ester derivative of ferrocene. Cyclic voltammetry and XPS measurements showed respectively that, in our conditions, the covalent grafting route gave more redox centres fixed on CNTs than the [pi]-stacking one and the probes are located differently on the electrodes. In the first case, the high specific area of the CNTs electrodes resulted in a 32-fold increase of the amount of immobilized redox species with respect to its projected plane surface. Finally, a preliminary activity test of our [pi]-stacked and covalently functionalized electrodes on glucose sensing was realized

Surfaces bactériostatiques

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Robust Grafting of Polyionenes: New Potent and Versatile Antimicrobial Surfaces

International audiencePolyionenes (PI) with stable positive charges and tunable hydrophobic spacers in the polymer backbone, are shown to be particularly efficient regarding antimicrobial properties. This effect can be modulated since it increases with the length of hydrophobic spacers, i.e., the number of methylene groups between quaternary ammoniums. Now, to further explore these properties and provide efficient antimicrobial surfaces, polyionenes should be grafted onto materials. Here a robust grafting strategy to covalently attach polyionenes is described. The method consisted in a sequential surface chemistry procedure combining polydopamine coating, diazonium-induced polymerization, and polyaddition. To the best of knowledge, grafting of PI onto surfaces is not reported earlier. All chemical steps are characterized in detail via various surface analysis techniques (FTIR, X-ray photoelectron spectroscopy, contact angle, and surface energy measurements). The antibacterial properties of polyionene-grafted surfaces are then studied through bacterial adhesion experiments consisting in enumeration of adherent bacteria (total and viable cultivable cells). PI-grafted surfaces are showed to display effective and versatile bacteriostatic/bactericidal properties associated with a proadhesive effect