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Marie-Christine Daniel

Publications and source records attributed to Marie-Christine Daniel.

11 recordsLinked to original sources
PubMed2007

Core-controlled polymorphism in virus-like particles.

This study concerns the self-assembly of virus-like particles (VLPs) composed of an icosahedral virus protein coat encapsulating a functionalized spherical nanoparticle core. The recent development of efficient methods for VLP self-assembly has opened the way to structural studies. Using electron microscopy with image reconstruction, the structures of several VLPs obtained from brome mosaic virus capsid proteins and gold nanoparticles were elucidated. Varying the gold core diameter provides control over the capsid structure. The number of subunits required for a complete capsid increases with the core diameter. The packaging efficiency is a function of the number of capsid protein subunits per gold nanoparticle. VLPs of varying diameters were found to resemble to three classes of viral particles found in cells (T=1, 2, and 3). As a consequence of their regularity, VLPs form three-dimensional crystals under the same conditions as the wild-type virus. The crystals represent a form of metallodielectric material that exhibits optical properties influenced by multipolar plasmonic coupling.

Crystallization↗
PubMed2006

Nanoparticle-templated assembly of viral protein cages.

Self-assembly of regular protein surfaces around nanoparticle templates provides a new class of hybrid biomaterials with potential applications in medical imaging and in bioanalytical sensing. We report here the first example of efficiently self-assembled virus-like particles (VLPs) having a brome mosaic virus protein coat and a functionalized gold core. The present study indicates that functionalized gold particles can initiate VLP assembly by mimicking the electrostatic behavior of the nucleic acid component of the native virus. These VLP constructs are symmetric, with the protein stoichiometry and packaging properties indicating similarity to the icosahedral packing of the capsid. Moreover, a pH-induced swelling transition of the VLPs is observed, in direct analogy to the native virus.

Biomimetic Materials↗
PubMed2006

Quantum dot encapsulation in viral capsids.

Incorporation of CdSe/ZnS semiconductor quantum dots (QDs) into viral particles provides a new paradigm for the design of intracellular microscopic probes and vectors. Several strategies for the incorporation of QDs into viral capsids were explored; those functionalized with poly(ethylene glycol) (PEG) can be self-assembled into viral particles with minimal release of photoreaction products and enhanced stability against prolonged irradiation.

Capsid↗
PubMed2004

Assemblies of redox-active metallodendrimers using hydrogen bonding for the electrochemical recognition of the H2PO4- and adenosine-triphosphate (ATP2-) anions.

Two families of five metallodendrimers have been assembled by hydrogen bonding between the primary amino groups of DSM dendrimers G(n)-DAB-dendr-(NH(2))x (n = 1-5; x = 4, 8, 16, 32, 64) and the OH group of phenol dendrons containing a triallyl or a triferrocenylalkyl tripod in para position. These H-bonded dendrimers noted G(1)-DAB-12Fc, G(2)-DAB-24Fc, G(3)-DAB-48Fc, G(4)-DAB-96Fc, and G(5)-DAB-192Fc have been characterized as resulting from fast, reversible hydrogen bonding by the single broad signal observed in (1)H NMR for the three NH(2) + OH protons whose location depends on the concentration. The cyclic voltammograms (CVs) show a single reversible ferrocenyl wave due to the equivalence of these groups and the fast rotation of the supramolecular ensemble compared to the CV time scale. A new CV wave appears at less anodic potential upon addition of H(2)PO(4)(-) or adenosine-triphosphate (ATP(2)(-)) anion as a tetrabutylammonium salt as with previously studied ferrocenyl dendrimers. In addition, other specific and remarkable features are the fact that the new CV wave is much less intense than the initial one and the dramatically sudden disappearance of the initial CV wave at the equivalent point indicating the formation of a large supramolecular assembly with the hydrogenophosphate groups. Finally, the variation of the number of equivalent anions with the generation number to reach the equivalent point also suggests that the competition between the amino- and amido group for the interaction with hydrogenophosphate depends on the generation number. Recognition by these supramolecular dendrimers of H(2)PO(4)(-) and ATP(2)(-) follows the model of the relatively strong-interaction type in the Kaifer-Echegoyen model, which allows access to the ratio of association constants K(+)/K(0). A positive dendritic effect is found for the recognition of H(2)PO(4)(-) (i.e., the difference of potentials DeltaE(1/2) between the initial CV wave and the new one and the K(+)/K(0) value increase as the generation number increases) whereas the dendritic effect is slightly negative for the recognition of ATP(2)(-).

Adenosine Triphosphate↗
PubMed2004

Dendrimers and gold nanoparticles as exo-receptors sensing biologically important anions.

Dendrimers, alkylthiol-gold nanoparticles and gold-nanoparticle-cored dendrimers containing tethers terminated by a redox group (typically an iron sandwich) attached to a hydrogen-bonding group (amido, amino, silyl) are selective and efficient exo-receptors for the recognition, sensing and titration of oxo-anions, including ATP(2-), or halogens, mostly using cyclic voltammetry. Various positive dendritic effects were disclosed (in contrast to catalysis), and large gold-nanoparticle-cored redox dendrimers of this type that contain several hundred equivalent ferrocenyl groups readily adsorb on Pt electrodes, providing useful regenerable electrochemical sensors.

Anions↗
PubMed2003

Synthesis of five generations of redox-stable pentamethylamidoferrocenyl dendrimers and comparison of amidoferrocenyl- and pentamethylamidoferrocenyl dendrimers as electrochemical exoreceptors for the selective recognition of H2PO4-, HSO4-, and adenosine 5'-triphosphate (ATP) anions: stereoelectronic and hydrophobic roles of cyclopentadienyl permethylation.

A family of five metallodendrimers with pentamethylamidoferrocenyl termini were synthesized from the DSM dendrimers G(n)-DAB-dend-(NH(2))(x) (x=4, 8, 16, 32, 64) and characterized by standard techniques, including prominent molecular peaks (broad for x=64) in their MALDI-TOF mass spectra. Oxidation of G(4)-DAB-dend-(NHCOFc*)(x) (Fc*=C(5)H(4)FeCp*, Cp*=eta(5)-C(5)Me(5)) with SbCl(5) in CH(2)Cl(2) yields the stable 17-electron pentamethylferrocenium analogue, which can be characterized by ESR and Mössbauer spectroscopy and reduced back to the initial Fe(II) dendrimer, the cycle being carried out without decomposition. The cyclic voltammograms (CVs) of all dendrimers, recorded in CH(2)Cl(2) or DMF, show a fully reversible ferrocenyl wave without adsorption. They are much cleaner than those of the parent ferrocenyl analogues previously synthesized and studied by Cuadrado et al. These properties allow much easier recognition and titration of H(2)PO(4) (-) and ATP(2-) by CV with the permethylated series than with the parent series. On the other hand, permethylation reduces the difference between the potentials recorded before and after titration. This is not crucial for H(2)PO(4) (-) and ATP(2-), but it is for HSO(4) (-), because of the weak interaction in this case. Thus recognition and titration in CH(2)Cl(2) proceeds best with the parent series, and a positive dendritic effect is revealed by the appearance of a new wave whose difference in potential relative to the initial wave increases with increasing generation number. In DMF, recognition and titration are only possible with the permethylated series and are subject to a dramatic dendritic effect. Indeed, the titration is followed by only a shift of the initial wave with G(1) and by the appearance of a new wave with G(2) and G(3). In conclusion, the permethylated dendrimers allow excellent recognition and titration of the oxoanions by CV due to the stereoelectronic stabilization of the 17-electron form and their hydrophobic effect. The magnitude of the recognition and positive dendritic effects is very sensitive to the dendrimer structure and to the nature of the solvent. The recognition is of the strong-interaction type (square scheme) between these dendrimers and ATP(2-) with a stoichiometry of 0.5 equiv ATP(2-) per ferrocenyl branch.

Adenosine Triphosphate↗
PubMed2003

Nanoscopic assemblies between supramolecular redox active metallodendrons and gold nanoparticles: synthesis, characterization, and selective recognition of H2PO4-, HSO4-, and adenosine-5'-triphosphate (ATP2-) anions.

Tri- and nonaferrocenyl thiol dendrons have been synthesized and used to assemble dendronized gold nanoparticles either by the ligand-substitution method from dodecanethiolate-gold nanoparticles (AB(3) units) or Brust-type direct synthesis from a 1:1 mixture of dodecanethiol and dendronized thiol (AB(9) units). The dendronized colloids are a new type of dendrimers with a gold colloidal core. Two colloids containing a nonasilylferrocenyl dendron have been made; they bear respectively 180 and 360 ferrocenyl units at the periphery. These colloids selectively recognize the anions H(2)PO(4)(-) and adenosine-5'-triphosphate (ATP(2)(-)) with a positive dendritic effect and can be used to titrate these anions because of the shift of the CV wave even in the presence of other anions such as Cl(-) and HSO(4)(-). Recognition is monitored by the appearance of a new wave at a less positive potential in cyclic voltammetry (CV). The anion HSO(4)(-) is also recognized and titrated by the dendronized colloid containing the tris-amidoferrocenyl units, because of the progressive shift of the CV wave until the equivalence point. These dendronized colloids can form robust modified electrodes by dipping the naked Pt electrode into a CH(2)Cl(2) solution containing the colloids. The robustness is all the better as the dendron is larger. These modified electrodes can recognize H(2)PO(4)(-), ATP(2)(-) and HSO(4)(-), be washed with minimal loss of adsorbed colloid, and be reused.

Adenosine Triphosphate↗
PubMed2003

Supramolecular H-bonded assemblies of redox-active metallodendrimers and positive and unusual dendritic effects on the recognition of H2PO4-.

The DSM polyamine dendrimers dend-DAB-(NH2)x of generations 1 (x = 4) to 4 (x = 32) form H-bonded dendritic assemblies with the phenol AB3 units p-HOC6H4C(CH2CHCH2)3 and p-HOC6H4C{(CH2)3SiCH2NHCOFc}3 (Fc = ferrocenyl), as shown by the shifts of the NH2 and OH signals giving a concentration-dependent common signal between 2.4 and 4.1 ppm in CDCl3. The supramolecular dendrimers efficiently recognize H2PO4- anions with positive and unusual dendritic effects upon electrochemical titration involving half-stoichiometry for G1, a sudden cyclovoltammetry wave change at the equivalent point, and a dramatic intensity decrease of the new wave.

Ferrous Compounds↗