Search PubMed⌕ Search

Biomedical subjects

Anne-Marie Caminade

Publications and source records attributed to Anne-Marie Caminade.

At least 19 recordsLinked to original sources
PubMed2006

Enhanced catalytic properties of copper in O- and N-arylation and vinylation reactions, using phosphorus dendrimers as ligands.

Imino pyridine-capped phosphorus dendrimers were found to strongly enhance the catalytic activity of copper in arylations and vinylations of O- and N-nucleophiles. These reactions could indeed be performed under very mild conditions, often the mildest to date. Interestingly, such performances could not be obtained when using the monomeric imino pyridine chelating ligand alone. To the best of our knowledge, this constitutes a rare example of such a positive dendritic effect in the field of organometallic catalysis.

Catalysis↗
PubMed2006

Simultaneous excitation of propagating and localized surface plasmon resonance in nanoporous gold membranes.

Materials multifunctionality for optical sensing of adsorbates has obvious advantages-in addition to the potential for greater sensitivity, the different length scales associated with a variety of optical phenomena allow a greater variety of adsorption characteristics to be examined. Here, we show that ultrathin (approximately 100 nm) nanoporous gold membranes possess features of both planar metal films that exhibit propagating SPR excitations and nanofeatured metals that exhibit localized SPR excitations. This is the first report of such multifunctionality in an optically active metal. We give illustrative examples of using this material to probe biorecognition reactions and to probe the structure evolution of a layer-by-layer deposition of charged dendrimers. Our results are consistent with the very different lengths of the tail of the evanescent field decays associated with each of these plasmon excitation modes.

Journal Article↗
PubMed2006

Design of phosphorylated dendritic architectures to promote human monocyte activation.

As first defensive line, monocytes are a pivotal cell population of innate immunity. Monocyte activation can be relevant to a range of immune conditions and responses. Here we present new insights into the activation of monocytes by a series of phosphonic acid-terminated, phosphorus-containing dendrimers. Various dendritic or subdendritic structures were synthesized and tested, revealing the basic structural requirements for monocyte activation. We showed that multivalent character and phosphonic acid capping of dendrimers are crucial for monocyte targeting and activation. Confocal videomicroscopy showed that a fluorescein-tagged dendrimer binds to isolated monocytes and gets internalized within a few seconds. We also found that dendrimers follow the phagolysosomial route during internalization by monocytes. Finally, we performed fluorescence resonance energy transfer (FRET) experiments between a specifically designed fluorescent dendrimer and phycoerythrin-coupled antibodies. We showed that the typical innate Toll-like receptor (TLR)-2 is clearly involved, but not alone, in the sensing of dendrimers by monocytes. In conclusion, phosphorus-containing dendrimers appear as precisely tunable nanobiotools able to target and activate human innate immunity and thus prove to be good candidates to develop new drugs for immunotherapies.

Adult↗
PubMed2005

Octasubstituted metal-free phthalocyanine as core of phosphorus dendrimers: a probe for the properties of the internal structure.

The synthesis of a new family of phosphorus dendrimers built from an octasubstituted metal-free phthalocyanine core is described up to generation 5. This core is used as a sensor and a probe for analyzing the properties of the internal structure and the influence of each structural part (core, branches, surface) upon the whole structure. UV-visible spectra show both a hyperchromic and bathochromic effect on the Q-bands with increasing generation, indicating that the chromophore is more isolated, and that the dendritic shell mimics a highly polar solvent. There is no evidence for aggregation, except for generation 0, showing again the isolation of the core. However, the dendritic shell is permeable to aqueous acids and bases, as demonstrated by the reversible splitting of the Q-band in an acidic medium (neutral form of the phthalocyanine) and the single Q-band in a basic medium (dianionic form), even for generation 4. The fluorescence quantum yield for the neutral form increases with increasing generation. The dianionic form of generation 0 is poorly fluorescent, whereas generations 3 and 4 (G3 and G4) exhibit better fluorescence. The cores of G3 and G4 are highly sensitive optical sensors for H3O+ and OH-. These experiments are carried out in THF/water mixtures, and the influence of water on the structure has been checked. The hydrodynamic radius of generation 4 is measured by NMR diffusion (pulse gradient spin-echo) experiments. R(H) varies from 35.4 A at 4 mol % of water to 32.5 A at 64 mol % of water in THF, indicating the hydrophobic nature of these dendrimers.

Journal Article↗
PubMed2005

Characterization of dendrimers.

Dendrimers pertain both to the molecular chemistry world for their step by step controlled syntheses, and to the polymer world because of their repetitive structure made of monomers; thus they benefit from analytical techniques from both worlds. This review is a survey of the main analytical techniques used for the characterization of the chemical composition, the morphology, the shape, and the homogeneity of dendrimers. It includes NMR, IR, Raman, UV-Visible, fluorescence, circular dichroism, X-ray diffraction, mass spectrometry, SAXS, SANS, Laser Light Scattering, microscopy, SEC, EPR, electrochemistry, electrophoresis, intrinsic viscosity, DSC, and dielectric spectroscopy.

Chemical Phenomena↗
PubMed2005

Assembly and mechanical properties of phosphorus dendrimer/polyelectrolyte multilayer microcapsules.

We report the preparation, characterization, and mechanical properties of polyelectrolyte/phosphorus dendrimer multilayer microcapsules. The shells of these microcapsules are composed either by alternating poly(styrenesulfonate) (PSS) and positively charged dendrimer G4(NH+Et2Cl-)96 or by alternating poly(allylamine hydrochloride) (PAH) and negatively charged dendrimer G4(CH-COO-Na+)96. The same multilayers were constructed on planar support to examine their layer-by-layer growth and to measure the multilayer thickness. Surface plasmon resonance spectroscopy (SPR) showed regular linear growth of the assembly upon each bilayer deposited. We probe the mechanical properties of these polyelectrolyte/dendrimer microcapsules by measuring force-deformation curves with the atomic force microscope (AFM). The experiment suggests that they are much softer than PSS/PAH microcapsules studied before. This softening is attributed to an enhanced permeability of the polyelectrolyte/dendrimer multilayer shells as compared with multilayers formed by linear polyelectrolytes. In contrast, Young's modulus of both dendrimer-based multilayers was found to be on the same order as that of PSS/PAH multilayers.

Adsorption↗
PubMed2005

Dendritic catanionic assemblies: in vitro anti-HIV activity of phosphorus-containing dendrimers bearing galbeta1cer analogues.

Two series of water-soluble dendritic catanionic assemblies, acting as multisite analogues of galactosylceramide (Galbeta1cer), have been prepared with the goal of blocking HIV infection prior to the entry of the virus into human cells. Trifunctional and hexafunctional cinnamic acid-terminated dendrimers have been synthesized from phosphorus-containing dendrimers bearing aldehyde end groups. A classical acid-base reaction performed in water between acid-terminated dendrimers and stoichiometric amounts of N-hexadecylamino-1-deoxylactitol provided the expected catanionic assemblies. Antiviral assays on these supramolecular entities confirmed the crucial roles both of multivalency effects and of lipophilicity on the biological activity of Galbeta1cer analogues. Moreover, correlation between in vitro tests and molecular modeling highlights the specific influence of the assembly shape on the anti-HIV efficiency, with the tri- and hexafunctional cored dendrimers, both decorated with 12 sugar moieties, exhibiting IC50 values of 1.1 and 0.12 microM, respectively.

Anti-HIV Agents↗
PubMed2004

Self-assembly of water-soluble dendrimers into thermoreversible hydrogels and macroscopic fibers.

Hydrogels and macroscopic fibers are formed through the salt-induced self-assembly of water-soluble polycationic phosphorus dendrimers. Interestingly, the hydrogels are thermoreversible and the sol-gel transition temperature can be easily tuned in a wide range of temperatures (approximately 2-80 degrees C). The effects of different parameters, such as salt nature, dendrimer generation, concentration, and temperature, on dendrimer aggregation are examined. The macroscopic fibers are prepared by flocculation under flow and observed using scanning electron microscopy (SEM) which reveals a microscopic fibrillar substructure. We interpret the gelation and flocculation of the polycationic dendrimers in terms of colloidal flocculation.

Dendrimers↗
PubMed2004

Synthesis of hybrid dendrimer-star polymers by the RAFT process.

A first generation phosphorus-containing dendrimer with twelve terminal benzyl dithiobenzoate functions was designed and subsequently used as a multifunctional agent to derive hybrid star copolymers consisting of a dendritic core surrounded by twelve polystyrene branches by reversible addition-fragmentation chain transfer (RAFT).

Journal Article↗
PubMed2004

Does charge carrier dimensionality increase in mixed-valence salts of tetrathiafulvalene-terminated dendrimers?

[structure: see text] In four new dendrimers terminated by 12 electroactive tetrathiafulvalenyl substituents, the tridimensional character of the inter- and intradendrimeric charge and electron transfer, and hence of the electroconductivity, is evidenced by examination of the electronic spectra of their corresponding neutral state and cation radical, dication, and mixed-valence salts, including a closed-shell anion.

Journal Article↗
PubMed2004

Thioacylation reactions for the surface functionalization of phosphorus-containing dendrimers.

The functionalization of phosphorus-containing dendrimers was easily achieved through thioacylation reactions involving new dendrimers capped with dithioester end groups and various functionalized amines. These reactions were successfully applied to the first generation (12 end groups) and the third generation of the dendrimer (48 end groups) and allowed their functionalization by various primary or secondary amines, alcohols, glycols, and azides. [reaction: see text]

Acylation↗
PubMed2004

Nanometric sponges made of water-soluble hydrophobic dendrimers.

The behavior of a fifth generation phosphorus dendrimer having a hydrophobic interior and hydrophilic end groups is studied in solution in water using the pulsed-field gradient spin-echo NMR technique. Addition of THF to this solution induces dramatic changes concerning the size of the dendrimer (+150% in volume), T1 relaxation of THF, and viscosity. This dendrimer behaves like a highly singular nanotool, able both to modify its environment and to be modified by it.

Journal Article↗
PubMed2004

Nanomaterials based on phosphorus dendrimers.

Dendrimers constitute an increasingly important field of research in chemistry for more than 15 years. After pioneering works concerning synthesis, the interest in dendrimers is now mainly driven by their properties and applications. This Account will emphasize the properties of a special class of dendrimers, that is, phosphorus-containing dendritic macromolecules, as tools for the elaboration of nanomaterials. Indeed, these dendrimers can be considered themselves as materials, or they can be used as an intrinsic constituent of a material or as a modifier of the surface of a material. In this latter case, a fundamental work about surfaces covalently modified by dendrimers recently opened the way to the elaboration of DNA chips.

Journal Article↗