Tailored nanogels by precipitation polymerization to open the therapeutic Window of gene delivery

223 p.Gene therapy holds immense promise as a revolutionary approach in medicine, offering the potential to treat and cure a wide range of genetic and acquired diseases. To achieve transfection of therapeutic genetic materials in targeted cells, viral and non-viral carriers have been developed. While viral vectors initially opened new avenues, their potential to activate the immune system have been unveiled during unfortunate clinical trials. In that context, nanogels have shown great advantages over other non-viral vectors for their stability, tunability, encapsulation capacity, and responsive behavior.In this thesis, we have designed temperature-responsive nanogels with a high level of control in the location of positive charges. We synthesized three very distinct structures via precipitation polymerization. The first structure presents a homogeneous distribution of positive charges in the nanogels and serve as a reference. In the two other structures, the positive charges are restricted to the core of the nanogels respectively by chemical and physical interactions. The thermo-responsive behavior permits a tuning of the positive charge availability on the surface of the nanogels. Finally, the cytotoxicity of the NGs, along with the gene loading and release performance were evaluated. The NGs showed high biocompatibility but limited transfection ability

Dramatic acceleration by visible light and mechanism of AuPd@ZIF-8-catalyzed ammonia borane methanolysis for efficient hydrogen production

The generation of H2 from materials with a high content of H atoms is attractive for both sustainable energy and convenient hydrogenation. We report that the novel synthesized AuPd@ZIF-8-alloyed nanoparticles (ZIF = zeolitic imidazolate framework) in which the AuPd nanoparticles (NPs) have a size of 2.43 nm and are shown by Brunauer–Emmett–Teller (BET) surface to be encapsulated into ZIF-8. The AuPd and ZIF-8 nanoparticle is an excellent nanocatalyst for the evolution of H2 in the methanolysis reaction of aminoborane (AB) under visible light irradiation. Visible-light-induced acceleration is due to the Au plasmonic excitation provoking hot electron transfer from Au to Pd-substrate ensemble, whereas the reactions catalyzed by monometallic Au@ZIF-8 or Pd@ZIF-8 undergo only few minutes or no acceleration (respectively) under visible light irradiation. Three mol H2 per mol AB are produced in 6 min at 25 °C (TOF: 86.8 mol H2 molatom−1 min−1) with AuPd@ZIF-8 under visible light compared with incomplete H2 formation in 30 min in the dark. A comparison of various heterogeneous supports shows that the ZIF-8 encapsulation of the nanoalloy is by far the best support for this reaction. The large primary kinetic isotope effect (KIE) kH/kD = 3.4 with visible-light irradiation, the high turnover frequency (TOF) under light illumination (3.7 times higher than in the dark), and density functional theory (DFT) calculations confirm the mechanism and illustrate the more difficult O–H oxidative addition on Pd in methanol than in water in this process. This is due to the weaker acidity of methanol compared to that of water. Coupling labeling and tandem reactions with styrene hydrogenation showed that one H atom of H2 formed is provided by AB, while the other one is from methanol. The cleanness of the H2 generated and the recyclability of the NH4B(OMe)4 product render AB methanolysis attractive for low-temperature H2 production devices and tandem reactions

Facile MOF Support Improvement in Synergy with Light Acceleration for Efficient Nanoalloy-Catalyzed H2 Production from Formic Acid

International audienceHydrogen (H2) generation and storage are actively investigated to provide a green source of energy, and formic acid (HCOOH), a major product obtained from the biomass, is regarded as a productive source of H2. Therefore, improvements in heterogeneous catalysts are called for. Here, a novel type of catalyst support is proposed involving simple addition of the mixture of metal ion precursors to core-shell ZIF-8@ZIF-67, followed by reduction with NaBH4, with performances surpassing those obtained using nanocatalysts in ZIF-8 or ZIF-67. The nanocatalysts PdxAg were optimized with ZIF-8@Pd2Ag1@ZIF-67 under visible-light illumination for selective HCOOH dehydrogenation involving a turnover frequency value of 430 h-1 under light irradiation at 353 K. These results also reveal the crucial roles of the Pd sites electronically promoted in the presence of visible by the plasmon resonance and the core-shell light by Ag plasmon advantageous MOF structure. In order to examine the potential of extending this catalyst improvement principle to other catalytic reactions, 4nitrophenol reduction, a benchmarking model of catalytic reaction, was tested, and the results also confirmed the superiority of the performance of ZIF-8@Pd2Ag1@ZIF-67 over Pd2Ag1@ZIF-8 and Pd2Ag1@ZIF-67, confirming the interest in the novel catalyst design

Polyelectrolyte/fluorinated polymer interpenetrating polymer networks as fuel cell membrane

International audienceOriginal membranes based on an interpenetrating polymer network (IPN) architecture combining a poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (AMPS) network and a fluorinated network were synthesized. The AMPS weight compositions were varied from 50 to 70 wt%. The first network was achieved by radical copolymerization of AMPS with a fluorinated telechelic diacrylate while the second one was obtained by photoinitiated cationic copolymerization of telechelic fluorinated diepoxide with trimethylol propane triglycidyl ether. The morphologies of these different IPNs were deduced from small-angle X-ray scattering (SAXS) spectra and dynamic thermomechanical analysis (DMTA). The main functional properties related to their use as proton exchange membrane in fuel cells were quantified, such as water vapor sorption, liquid water uptake (22-59 wt%), proton conductivity (1-63 mS/cm), gas permeability (0.06 and 0.80 barrer for dry oxygen and hydrogen, respectively), and oxidative and thermal stabilities. More precisely, the effects of the ionic exchange capacity (IEC) varying from 1.73 to 2.43 meq/g and the cross-linking density of the conducting phase on the morphology and the properties of IPN membranes were studied in detail. Finally, these IPN membranes were tested as fuel cell membrane and a correlation between the ex-situ and in-situ characterizations was established

Fluorohexane network and sulfonated PEEK based semi-IPNs for fuel cell membranes

International audienceThe purpose of this study has been to develop new proton-exchange membranes based on semiinterpenetrating polymer network (semi-IPN) architectures for application in polymer electrolyte fuel cells. A series of semi-IPNs combining a fluorinated hexane network and a linear sulfonated poly(aryl ether ether ketone) (SPEEK) has been obtained by varying the SPEEK content from 50 to 80 wt.%. A telechelic functionalized acrylate oligomer was obtained by acrylation of , -fluorinated hexanediol, while SPEEK was synthesized by polycondensation of sulfonated difluorobenzophenone with the bisphenol 6F. These semi-IPN membranes have been characterized by infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and small-angle X-ray scattering. A semi-IPN containing 60 wt.% SPEEK has been tested as a fuel cell membrane

Assembly and recognition mechanisms of glycosylated PEGylated polyallylamine phosphate nanoparticles: A fluorescence correlation spectroscopy and small angle X-ray scattering study

Hypothesis: Modification of polyallylamine hydrochloride (PAH) with heterobifunctional low molecular weight polyethylene glycol (PEG) (600 and 1395 Da), and subsequent attachment of mannose, glucose, or lactose sugars to PEG, can lead to formation of polyamine phosphate nanoparticles (PANs) with lectin binding affinity and narrow size distribution.Experiments: Size, polydispersity, and internal structure of glycosylated PEGylated PANs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). Fluorescence correlation spectroscopy (FCS) was used to study the association of labelled glycol-PEGylated PANs. The number of polymer chains forming the nanoparticles was determined from the changes in amplitude of the cross-correlation function of the polymers after formation of the nanoparticles. SAXS and fluorescence cross -correlation spectroscopy were used to investigate the interaction of PANs with lectins: concanavalin A with mannose modified PANs, and jacalin with lactose modified ones. Findings: Glyco-PEGylated PANs are highly monodispersed, with diameters of a few tens of nanometers and low charge, and a structure corresponding to spheres with Gaussian chains. FCS shows that the PANs are single chain nanoparticles or formed by two polymer chains. Concanavalin A and jacalin show specific interactions for the glyco-PEGylated PANs with higher affinity than bovine serum albumin

Cu(I)‐Glutathione Assembly Supported on ZIF‐8 as Robust and Efficient Catalyst for Mild CO2 Conversions

International audienceThe Cu‐glutathione (GSH) redox system, essential in biology, is designed here as a supramacromolecular assembly in which the tetrahedral 18e Cu(I) center loses a thiol ligand upon adsorption onto ZIF‐8, as shown by EXAFS and DFT calculation, to generate a very robust 16e planar trigonal single‐atom Cu(I) catalyst. Synergy between Cu(I) and ZIF‐8, revealed by catalytic experiments and DFT, affords CO2 conversion into high‐value‐added chemicals with a wide scope of substrates by reaction with terminal alkynes or propargyl amines in excellent yields under mild conditions and reuse at least 10 times without significant decrease in catalytic efficiency