Anne-Françoise Mingotaud

Polymeric Micelles Encapsulating Photosensitizer: Structure/Photodynamic Therapy Efficiency Relation

Various polymeric micelles were formed from amphiphilic block copolymers, namely, poly(ethyleneoxide-b-ε-caprolactone), poly(ethyleneoxide-b-d,l-lactide), and poly(ethyleneoxide-b-styrene). The micelles were characterized by static and dynamic light scattering, electron microscopy, and asymmetrical flow field-flow fractionation. They all displayed a similar size close to 20 nm. The influence of the chemical structure of the block copolymers on the stability upon dilution of the polymeric micelles was investigated to assess their relevance as carriers for nanomedicine. In the same manner, the stability upon aging was assessed by FRET experiments under various experimental conditions (alone or in the presence of blood proteins). In all cases, a good stability over 48 h for all systems was encountered, with PDLLA copolymer-based systems being the first to release their load slowly. The cytotoxicity and photocytotoxicity of the carriers were examined with or without their load. Lastly, the photodynamic activity was assessed in the presence of pheophorbide a as photosensitizer on 2D and 3D tumor cell culture models, which revealed activity differences between the 2D and 3D systems.

Hyperbranched polyamidoamine as stabilizer for catalytically active nanoparticles in water.

Poly(amidoamine) hyperbranched polymers (HYPAM) were successfully used to synthesize platinum nanoparticles of ca. 1.8 nm and to stabilize these particles in water. Furthermore these hyperbranched-stabilized platinum nanoparticles proved to be effective and robust for hydrogenation reaction in water.

Ring-opening metathesis polymerization on well defined silica nanoparticles leading to hybrid core–shell particles

The grafting and catalytic activity of a metathesis catalyst on well defined silica nanoparticles is described. The aim of this was to test the catalysis properties of a ligand-linked catalyst in ring-opening metathesis polymerization and also the possibility to obtain controlled hybrid materials. This was carried out by reaction of a synthesized hydroxy functionalized phosphine Cy2P(CH2)10OH with Cl2Ru(PPh3)2(CH–Ph), leading to a metathesis catalyst bearing a hydroxy group at the end of a ligand. This group was reacted with well defined silica nanoparticles with a diameter of 200 nm, that had acyl chloride functions at their surface. The grafting density was calculated from thermogravimetry experiments and found to be around 7 µmol m−2. The activity of the catalyst was tested for the ring-opening polymerization of norbornene. This showed that a fraction as high as 30% of the catalyst could initiate the polymerization and that the polymerization proceeded until completion. TEM characterization revealed that in diluted solutions, core–shell morphologies could be obtained. The efficiency of the polymerization may therefore lead to control of the thickness of the polymer coating.

Asymmetrical flow field-flow fractionation with multi-angle light scattering and quasi elastic light scattering for characterization of poly(ethyleneglycol-b-ɛ-caprolactone) block copolymer self-assemblies used as drug carriers for photodynamic therapy

Poly(ethyleneoxide-b-ɛ-caprolactone) (PEO-b-PCL) self-assemblies in water were characterized by asymmetrical flow field-flow fractionation (AsFlFFF), with on-line coupling with quasi-elastic light scattering (QELS), multi-angle light scattering (MALS), refractive index and UV/Vis detection. We report here the AsFlFFF analysis of three different nanoparticular self-assembled systems of PEO-PCL polymers in aqueous media, each polymer differing by the mass of the PEO and PCL fragments. Thus, self-assembled water samples of {PEO(2000)-b-PCL(2600)}, {PEO(5000)-b-PCL(1400)} and {PEO(5000)-b-PCL(4000)} were analyzed by AsFlFFF. In most cases, the size obtained by AsFlFFF was similar to the one characterized by DLS. However, in some instances, only AsFlFFF revealed the presence of several self-assemblies with very different sizes. These nanoparticles being used for the targeted delivery of photosensitizers in photodynamic therapy, it was important to fully characterize the samples in terms of size and size distribution, molecular weight, Ip, aggregation number and also to assess whether the photosensitizer was inside the nanoparticles. AsFlFFF proved to be a very efficient technique which enabled this study without any destruction of the nanoparticles.

Liquid crystalline magnetic materials

This work deals with the synthesis of a new magnetic liquid crystalline material: a side chain liquid crystal silicone, doped with magnetic cobalt nanorods. This new material presents very promising magnetic properties, discussed in terms of the influence of the lateral liquid crystal groups.

Asymmetrical flow field-flow fractionation with multi-angle light scattering and quasi-elastic light scattering for characterization of polymersomes: comparison with classical techniques

AbstractPolymersomes formed from amphiphilic block copolymers, such as poly(ethyleneoxide-b-ε-caprolactone) (PEO-b-PCL) or poly(ethyleneoxide-b-methylmethacrylate), were characterized by asymmetrical flow field-flow fractionation coupled with quasi-elastic light scattering (QELS), multi-angle light scattering (MALS), and refractive index detection, leading to the determination of their size, shape, and molecular weight. The method was cross-examined with more classical ones, like batch dynamic and static light scattering, electron microscopy, and atomic force microscopy. The results show good complementarities between all the techniques; asymmetrical flow field-flow fractionation being the most pertinent one when the sample exhibits several different types of population. Figureᅟ

Anionic ring-opening polymerization of ε-caprolactone in supercritical carbon dioxide: parameters influencing the reactivity

The anionic ring-opening polymerization of var epsilon-caprolactone in supercritical CO2 is described using different metal alkoxides as initiators...

Artificial enzymes based on imprinted liquid‐crystalline materials

Liquid‐crystal elastomers, imprinted around indole, are assessed as artificial enzymes for the isomerisation of benzisoxazole into 2‐cyano phenol. Two types of material are synthesised, tested in the catalysis and compared with non‐liquid‐crystal imprinted polymers: an imprinted liquid‐crystalline elastomer and a semi‐interpenetrated imprinted liquid‐crystal network. The catalytic effect of all materials is close. However, the main benefit for the liquid‐crystal elastomer is shown to be the shape memory of the material at the molecular scale, because the isomerisation kinetics are found to be identical before and after deformation of the cavities either by thermal treatment up to the isotropic state or by solvent induced swelling. This fact is related to the coupling between the order and the conformation of the polymer chains, which is fixed by the crosslinking process. On the other hand, the imprinted sites of the semi‐interpenetrated imprinted liquid‐crystal elastomer are shown to be almost 100 times more active than the non‐imprinted sites in the catalysis. This factor is only 22 for the corresponding non‐liquid‐crystalline network.

First approach to the use of liquid crystal elastomers for chemical sensors

Liquid crystalline thin films elastomers that are able to bind pesticides have been developed. The synthesis involves grafting mesogen and crosslinkable groups on a polysiloxane chain in the presence of a template molecule. The molecular imprinted material is obtained after thin film deposition, UV crosslinking and washing. Experiments of readsorption of pesticide are presented. Development of a multisensor platform based on thermal and capacitive sensors is described and tests of deposition of the polymer film are presented.

Mesomorphic ionic hyperbranched polymers: effect of structural parameters on liquid-crystalline properties and on the formation of gold nanohybrids

Branched thermotropic liquid crystals were successfully obtained from ionic interactions between hyperbranched polyamidoamine and sodium dodecylsulfate. These complexes present columnar rectangular and lamellar thermotropic mesophases as demonstrated by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The relationships between the structural characteristics of the polymers (size of the hyperbranched core, hyperbranched or dendritic nature of the core, and substitution ratio) and the mesomorphic properties were studied. In situ formation of gold nanoparticles was then performed. The templating effect of the liquid crystal mesophase resulted in the formation of isotropic nanoparticles, the size of which was dictated by the local organization of the mesophase and by the molar mass of the hyperbranched complex.