Publications by authors named "Marie-Christine Daniel"

25 Publications

  • Page 1 of 1

Crotamine Cell-Penetrating Nanocarriers: Cancer-Targeting and Potential Biotechnological and/or Medical Applications.

Methods Mol Biol 2020 ;2118:61-89

Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD, USA.

Crotamine is a basic, 42-residue polypeptide from snake venom that has been shown to possess cell-penetrating properties. Here we describe the preparation, purification, biochemical and biophysical analysis of venom-derived, recombinant, chemically synthesized, and fluorescent-labeled crotamine. We also describe the formation and characterization of crotamine-DNA and crotamine-RNA nanoparticles; and the delivery of these nanoparticles into cells and animals. Crotamine forms nanoparticles with a variety of DNA and RNA molecules, and crotamine-plasmid DNA nanoparticles are selectively delivered into actively proliferating cells in culture or in living organisms such as mice, Plasmodium, and worms. As such, these nanoparticles could form the basis for a nucleic acid drug-delivery system. We also describe here the design and characterization of crotamine-functionalized gold nanoparticles, and the delivery of these nanoparticles into cells. We also evaluated the viability of using the combination of crotamine with silica nanoparticles in animal models, aiming to provide slow delivery, and to decrease the crotamine doses needed for the biological effects. In addition, the efficacy of administering crotamine orally was also demonstrated.
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http://dx.doi.org/10.1007/978-1-0716-0319-2_5DOI Listing
January 2021

Set of Highly Stable Amine- and Carboxylate-Terminated Dendronized Au Nanoparticles with Dense Coating and Nontoxic Mixed-Dendronized Form.

Langmuir 2019 03 18;35(9):3391-3403. Epub 2019 Feb 18.

Department of Chemistry and Biochemistry , University of Maryland Baltimore County (UMBC) , Baltimore , Maryland 21250 , United States.

The synthesis of a novel poly(propyleneimine) (PPI) dendron in gram scale as well as its use in the formation of a highly stable, dendronized gold nanoparticle (AuNP)-based drug delivery platform is described herein. The AuNP-based platform is composed of three complementary parts: (i) a 15 nm AuNP core, (ii) a heterofunctional thioctic acid-terminated tetraethylene glycol spacer, and (iii) a third-generation PPI dendron with a unique protonation profile and diverse end-group functionalization that allows for further derivatization. The prepared dendronized AuNPs are able to withstand several rounds of lyophilization cycles with no sign of aggregation, are stable in phosphate-buffered saline and Hanks' buffer as well as in serum, and are resistant to degradation by glutathione exchange reactions. This nanocarrier platform displays a dense coating, with >1400 dendrons/AuNPs, which will enable very high payload. Furthermore, while amine-terminated AuNPs expectedly showed cytotoxicity against the MCF-7 breast cancer cell line from a NP concentration of 1 nM, the mixed monolayer AuNPs (coated with 40/60 amine/carboxylate dendrons) interestingly did not exhibit any sign of toxicity at concentrations as high as 15 nM, similar to the carboxylate-terminated AuNPs. The described dendronized AuNPs address the current practical need for a stable NP-based drug delivery platform which is scalable and easily conjugable, has long-term stability in solution, and can be conveniently formulated as a powder and redispersed in desired buffer or serum.
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http://dx.doi.org/10.1021/acs.langmuir.8b03196DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6499480PMC
March 2019

Single nanomaterial level investigation of ZnO nanorod sulfidation reactions via position resolved confocal Raman spectroscopy.

Nanoscale 2019 Jan;11(3):1147-1158

Department of Chemistry, Georgetown University, 37th & O Sts. NW., Washington, DC 20057, USA.

Zinc oxide (ZnO) nanomaterials have been used as desulfurizing sorbents for gaseous streams, zinc sulfide (ZnS)-forming template lattices in nanomaterial synthesis, and agriculturally produced sulfur (S)-removing reagents from the environment. Although various nanoscale forms of ZnO have already been utilized widely for such purposes, there is currently a lack of fundamental insight into the sulfidation of ZnO nanomaterials at the single nanocrystal level. We demonstrate that position-resolved confocal Raman spectroscopy can be successfully used to reveal the sulfidation process of ZnO NRs occurring at the single nanomaterial level. We attained a single crystal level understanding of the facet-dependent sulfidation reactivity of ZnO NRs by tracking the same NRs with Raman spectroscopy before and after the sulfidation reaction and quantitatively analyzing various ZnS-induced phonon scattering intensities from different positions on the NRs. The trend in NR facet-dependent sulfidation reactivity is further substantiated by correlating it with the electron microscopy and fluorescence data measured from the same NRs. The insight obtained from this study may provide the much-needed fundamental knowledge base for designing optimal ZnO nanostructures beneficial to many technological and industrial applications exploiting the ZnO-to-ZnS conversion. Taken together with the well-established methods to synthesize ZnO nanomaterials of specific crystal shapes and structures, our findings from this study may be broadly applicable in formulating and optimizing more advanced, low-dimensional ZnO sorbents and scrubbers for highly effective S removal.
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http://dx.doi.org/10.1039/c8nr06039hDOI Listing
January 2019

Strong coupling and induced transparency at room temperature with single quantum dots and gap plasmons.

Nat Commun 2018 10 1;9(1):4012. Epub 2018 Oct 1.

Department of Physics, UMBC (University of Maryland, Baltimore County), Baltimore, MD, 21250, USA.

Coherent coupling between plasmons and transition dipole moments in emitters can lead to two distinct spectral effects: vacuum Rabi splitting at strong coupling strengths, and induced transparency (also known as Fano interference) at intermediate coupling strengths. Achieving either strong or intermediate coupling between a single emitter and a localized plasmon resonance has the potential to enable single-photon nonlinearities and other extreme light-matter interactions, at room temperature and on the nanometer scale. Both effects produce two peaks in the spectrum of scattering from the plasmon resonance, and can thus be confused if scattering measurements alone are performed. Here we report measurements of scattering and photoluminescence from individual coupled plasmon-emitter systems that consist of a single colloidal quantum dot in the gap between a gold nanoparticle and a silver film. The measurements unambiguously demonstrate weak coupling (the Purcell effect), intermediate coupling (Fano interference), and strong coupling (Rabi splitting) at room temperature.
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http://dx.doi.org/10.1038/s41467-018-06450-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6167320PMC
October 2018

Controlled etching and tapering of Au nanorods using cysteamine.

Nanoscale 2018 Sep;10(35):16830-16838

Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, USA.

While gold nanorods (AuNRs) have found many applications due to their unique optical properties, a few challenges persist in their synthesis. Namely, it is often difficult to reproducibly synthesize AuNRs with specific and monodisperse sizes, especially at shorter aspect ratios. Here, we report a method of post-synthesis precise tailoring of AuNRs by etching with cysteamine. Cysteamine selectively etches AuNRs from their ends while preserving the initial rod shape and monodispersity, making this a viable means of obtaining highly monodisperse short AuNRs down to aspect ratio 2.3. Further, we explore the effect of this etching method on two types of silica-coated AuNRs: silica side-coated and silica end-coated AuNRs. We find that the etching process is cysteamine concentration-dependent and can lead to different degrees of sharpening of the silica-coated AuNRs, forming elongated tips. We also find that cysteamine behaves only as a ligand at concentrations above 200 mM, as no etching of the AuNRs is observed in this condition. Simulations show that excitation of plasmon resonances in these sharpened AuNRs produces local electric fields twice as strong as those produced by conventional AuNRs. Thus, cysteamine etching of AuNRs is shown to be an effective means of tailoring both the size and shape of AuNRs along with their corresponding optical properties. At the same time, the resulting cysteamine coating on the etched AuNRs displays terminal amino groups that allow for further functionalization of the nanorods.
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http://dx.doi.org/10.1039/c8nr05325aDOI Listing
September 2018

Dendronized Systems for the Delivery of Chemotherapeutics.

Adv Cancer Res 2018 18;139:85-120. Epub 2018 May 18.

Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD, United States. Electronic address:

This chapter reviews the use of dendronized systems as nanocarriers for the delivery of chemotherapeutic drugs. Dendronized systems include dendrimers prepared through convergent methods as well as other systems containing dendrons (e.g., polymers, nanoparticles, liposomes). The preparation of such systems is detailed, followed by the various conjugation techniques used for the transport of chemotherapeutic drugs and their specific delivery to tumor cells. In addition, the ability of dendronized systems to provide passive and active targeting to tumors is discussed. The efficacy of drug delivery using dendronized systems is also illustrated through specific examples of kinetic and biological studies. Finally, the newest trends in conjugation of the most common chemotherapeutics to dendronized systems are described. Overall, this chapter highlights dendronized systems as a way to improve the therapeutic efficiency of drugs for the treatment of cancer. All the recent developments in areas, such as biodegradable dendrimers, modifications to enhance biocompatibility, selectively cleavable drug conjugations, ligand-mediated targeting, and the potential for multifunctional properties, show promises for future advances in cancer therapy.
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http://dx.doi.org/10.1016/bs.acr.2018.04.003DOI Listing
September 2019

Spatially Correlated, Single Nanomaterial-Level Structural and Optical Profiling of Cu-Doped ZnO Nanorods Synthesized via Multifunctional Silicides.

Nanomaterials (Basel) 2018 Apr 7;8(4). Epub 2018 Apr 7.

Department of Chemistry, Georgetown University, 37th & O Sts. NW., Washington, DC 20057, USA.

We demonstrate a straightforward and effective method to synthesize vertically oriented, Cu-doped ZnO nanorods (NRs) using a novel multipurpose platform of copper silicide nanoblocks (Cu₃Si NBs) preformed laterally in well-defined directions on Si. The use of the surface-organized Cu₃Si NBs for ZnO NR growth successfully results in densely assembled Cu-doped ZnO NRs on each NB platform, whose overall structures resemble thick bristles on a brush head. We show that Cu₃Si NBs can uniquely serve as a catalyst for ZnO NRs, a local dopant source of Cu, and a prepatterned guide to aid the local assembly of the NRs on the growth substrate. We also ascertain the crystalline structures, optical properties, and spectroscopic signatures of the Cu-doped ZnO NRs produced on the NBs, both at each module of NRs/NB and at their ensemble level. Subsequently, we determine their augmented properties relative to the pristine form of undoped ZnO NRs and the source material of Cu₃Si NBs. We provide spatially correlated structural and optical data for individual modules of Cu-doped ZnO NRs assembled on a Cu₃Si NB by resolving them along the different positions on the NB. Ensemble-averaged versus individual behaviors of Cu-doped ZnO NRs on Cu₃Si NBs are then compared. We further discuss the potential impact of such ZnO-derived NRs on their relatively unexplored biological and biomedical applications. Our efforts will be particularly useful when exploiting each integrated module of self-aligned, Cu-doped ZnO NRs on a NB as a discretely addressable, active element in solid-state sensors and miniaturized luminescent bioprobes.
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http://dx.doi.org/10.3390/nano8040222DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5923552PMC
April 2018

Design and characterization of crotamine-functionalized gold nanoparticles.

Colloids Surf B Biointerfaces 2018 Mar 11;163:1-8. Epub 2017 Dec 11.

Departamento de Farmacologia, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, Brazil. Electronic address:

This paper describes the development of a facile and environmentally friendly strategy for supporting crotamine on gold nanoparticles (GNPs). Our approach was based on the covalent binding interaction between the cell penetrating peptide crotamine, which is a snake venom polypeptide with preference to penetrate dividing cells, and a polyethylene glycol (PEG) ligand, which is a nontoxic, water-soluble and easily obtainable commercial polymer. Crotamine was derivatized with ortho-pyridyldisulfide-polyethyleneglycol-N-hydroxysuccinimide (OPSS-PEG-SVA) cross-linker to produce OPSS-PEG-crotamine as the surface modifier of GNP. OPSS-PEG-SVA can serve not only as a surface modifier, but also as a stabilizing agent for GNPs. The successful PEGylation of the nanoparticles was demonstrated using different physicochemical techniques, while the grafting densities of the PEG ligands and crotamine on the surface of the nanoparticles were estimated using a combination of electron microscopy and mass spectrometry analysis. In vitro assays confirmed the internalization of these GNPs, into living HeLa cells. The results described herein suggest that our approach may serve as a simple platform for the synthesis of GNPs decorated with crotamine with well-defined morphologies and uniform dispersion, opening new roads for crotamine biomedical applications.
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http://dx.doi.org/10.1016/j.colsurfb.2017.12.013DOI Listing
March 2018

Dramatic Modification of Coupled-Plasmon Resonances Following Exposure to Electron Beams.

J Phys Chem Lett 2017 Aug 21;8(15):3607-3612. Epub 2017 Jul 21.

Department of Physics, University of Maryland, Baltimore County , Baltimore, Maryland 21250, United States.

Studies of the plasmon resonances in individual and coupled metal nanoparticles often involve imaging of the nanostructures of interest in an electron microscope. We show that this process can dramatically modify the optical spectra of coupled plasmonic nanoparticles, illustrated here with the case of gold nanorod-nanosphere dimers. The spectral changes are due to the thin, partially conductive carbonaceous layer that deposits onto the particles during imaging. These changes are particularly significant for coupled nanoparticles with subnanometer interparticle gaps but have largely been neglected in previous studies of such structures, including studies intended to probe quantum-mechanical effects in plasmon coupling. Accounting for the effects of the carbonaceous layer will lead to a more accurate understanding of such systems.
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http://dx.doi.org/10.1021/acs.jpclett.7b01601DOI Listing
August 2017

Small-angle X-ray scattering method to characterize molecular interactions: Proof of concept.

Sci Rep 2015 Jul 10;5:12085. Epub 2015 Jul 10.

Division of Imaging, Diagnostics, and Software Reliability, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, USA.

Characterizing biomolecular interactions is crucial to the understanding of biological processes. Existing characterization methods have low spatial resolution, poor specificity, and some lack the capability for deep tissue imaging. We describe a novel technique that relies on small-angle X-ray scattering signatures from high-contrast molecular probes that correlate with the presence of biomolecular interactions. We describe a proof-of-concept study that uses a model system consisting of mixtures of monomer solutions of gold nanoparticles (GNPs) as the non-interacting species and solutions of GNP dimers linked with an organic molecule (dimethyl suberimidate) as the interacting species. We report estimates of the interaction fraction obtained with the proposed small-angle X-ray scattering characterization method exhibiting strong correlation with the known relative concentration of interacting and non-interacting species.
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http://dx.doi.org/10.1038/srep12085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4498188PMC
July 2015

[Urinary incontinence in the elderly].

Soins Gerontol 2014 Sep-Oct(109):23-7

Urinary incontinence affects approximately three million women in France. Its frequency increases with age. It impacts quality of life. Interrogation and clinical examination usually allow understanding its mechanism, but some additional explorations may be necessary. When a curative treatment is not possible, absorbent pads or a penile sheath in males improve patient comfort.
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December 2014

Syntheses and characterization of lisinopril-coated gold nanoparticles as highly stable targeted CT contrast agents in cardiovascular diseases.

Langmuir 2012 Jul 5;28(28):10398-408. Epub 2012 Jul 5.

Lisinopril was used as the targeting moiety to prepare gold nanoparticle-based functional CT contrast agents. Pure lisinopril, thioctic acid-lisinopril conjugate, and reduced thioctic acid-lisinopril conjugate were used to obtain GNP-Lis, GNP-TA-Lis, and GNP-RTA-Lis, respectively, via ligand exchange reaction on citrate-coated gold nanoparticles (GNPs). These lisinopril-decorated GNPs were fully characterized, and their chemical stabilities in biological relevant media and in high salt concentration were compared. Their relative stabilities toward lyophilization and against cyanide-induced decomposition were also investigated. Because of their higher stability, GNP-TA-Lis were used to assess the targeting of angiotensin converting enzyme (ACE) using X-ray computed tomography (CT). The images obtained displayed high contrast in the region of the lungs and heart, clearly indicating the targeting of ACE, whose overexpression is associated with development of cardiac and pulmonary fibrosis. Thus, the new nanoprobes prepared here will serve as very useful tools for the monitoring of cardiovascular pathophysiologies using CT imaging.
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http://dx.doi.org/10.1021/la301694qDOI Listing
July 2012

Role of surface charge density in nanoparticle-templated assembly of bromovirus protein cages.

ACS Nano 2010 Jul;4(7):3853-60

Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.

Self-assembling icosahedral protein cages have potentially useful physical and chemical characteristics for a variety of nanotechnology applications, ranging from therapeutic or diagnostic vectors to building blocks for hierarchical materials. For application-specific functional control of protein cage assemblies, a deeper understanding of the interaction between the protein cage and its payload is necessary. Protein-cage encapsulated nanoparticles, with their well-defined surface chemistry, allow for systematic control over key parameters of encapsulation such as the surface charge, hydrophobicity, and size. Independent control over these variables allows experimental testing of different assembly mechanism models. Previous studies done with Brome mosaic virus capsids and negatively charged gold nanoparticles indicated that the result of the self-assembly process depends on the diameter of the particle. However, in these experiments, the surface-ligand density was maintained at saturation levels, while the total charge and the radius of curvature remained coupled variables, making the interpretation of the observed dependence on the core size difficult. The current work furnishes evidence of a critical surface charge density for assembly through an analysis aimed at decoupling the surface charge and the core size.
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http://dx.doi.org/10.1021/nn1005073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2937271PMC
July 2010

Nanoporous magnets of chiral and racemic [{Mn(HL)}2Mn{Mo(CN)7}2] with switchable ordering temperatures (TC = 85 K <--> 106 K) driven by H2O sorption (L = N,N-dimethylalaninol).

J Am Chem Soc 2007 Nov 17;129(45):13872-8. Epub 2007 Oct 17.

Laboratoire de Chimie de Coordination du CNRS, Université Paul Sabatier, 205, Route de Narbonne, F-31077 Toulouse, France.

Molecule-based solids represent a rare opportunity to combine, adjust, and interrelate structural and physical functionalities to develop multifunctional materials. Here we report on a series of porous supramolecular magnets whose magnetic properties are related to their sorption state. A family of magnets of the formula [{Mn(HL)(H2O)}2Mn{Mo(CN)7}2].2H2O have been obtained by assembling the heptacyano-metalate building unit {Mo(CN)7}4- with Mn(II) in the presence of protonated N,N-dimethylalaninol (L) as ligand, the latter being either as a racemic mixture or as a chiral R- or S-enantiomer. The resulting magnets possess an open framework structure and exhibit a TC with a switching behavior (TC = 85 K <--> 106 K) as a function of the hydration state. Moreover, chiral magnets are formed with the optically active ligands. The H2O and gas (N2, CO2, CO) sorption features, the magnetic behavior of both the hydrated and dehydrated magnets, and the crystal structures of the hydrated chiral (S) and racemic magnets are described.
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http://dx.doi.org/10.1021/ja073612tDOI Listing
November 2007

Core-controlled polymorphism in virus-like particles.

Proc Natl Acad Sci U S A 2007 Jan 16;104(4):1354-9. Epub 2007 Jan 16.

Department of Biochemistry and Biophysics, and Microscopy and Imaging Center, Texas A&M University, College Station, TX 77843, USA.

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.
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http://dx.doi.org/10.1073/pnas.0610542104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1783121PMC
January 2007

Quantum dot encapsulation in viral capsids.

Nano Lett 2006 Sep;6(9):1993-9

Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.

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.
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http://dx.doi.org/10.1021/nl061165uDOI Listing
September 2006

Nanoparticle-templated assembly of viral protein cages.

Nano Lett 2006 Apr;6(4):611-5

Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.

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.
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http://dx.doi.org/10.1021/nl0600878DOI Listing
April 2006

Inhibition of the electrochemistry of ferrocenes by polyamine dendrimers and the key role of hydrogen-bonding with hydroxy groups.

Chem Commun (Camb) 2005 Mar 26(12):1569-71. Epub 2005 Jan 26.

Nanosciences and Catalysis Group, LCOO, UMR CNRS No 5802, Université Bordeaux I, 33405, Talence Cedex, France.

Commercial DSM polyamine dendrimers inhibit the observation of the cyclic voltammetry (CV) of simple ferrocenes all the more as they are larger (marked dendritic effect); the CV is re-established, however, if a OH-containing group is present in the ferrocene derivative.
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http://dx.doi.org/10.1039/b418437hDOI Listing
March 2005

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

Inorg Chem 2004 Dec;43(26):8649-57

Molecular Nanosciences and Catalysis Group, LCOO, UMR CNRS No. 5802, Université Bordeaux I, 33405 Talence Cédex, France.

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)(-).
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http://dx.doi.org/10.1021/ic0493999DOI Listing
December 2004

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

Chem Commun (Camb) 2004 Dec 4(23):2637-49. Epub 2004 Nov 4.

Nanosciences and Catalysis Group, LCOO, UMR CNRS No. 5802, Université Bordeaux I, 351 Cours de la Liberation, 33405 Talence Cedex, France.

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.
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http://dx.doi.org/10.1039/b410399hDOI Listing
December 2004

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Chem Rev 2004 Jan;104(1):293-346

Molecular Nanosciences and Catalysis Group, LCOO, UMR CNRS No. 5802, Université Bordeaux I, 33405 Talence Cedex, France.

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http://dx.doi.org/10.1021/cr030698+DOI Listing
January 2004

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.

Chemistry 2003 Sep;9(18):4371-9

Groupe Nanosciences Moléculaires et Catalyse, LCOO, UMR CNRS No. 5802, Université Bordeaux I, 33405 Talence Cedex, France.

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.
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http://dx.doi.org/10.1002/chem.200304886DOI Listing
September 2003

Redox-robust pentamethylamidoferrocenyl metallodendrimers that cleanly and selectively recognize the H2PO4- anion.

Chem Commun (Camb) 2003 Feb(4):464-5

LCOO, UMR CNRS No 5802, Université Bordeaux 1, 33405 Talence Cedex, France.

The first pentamethylferrocenyl (Fc*) dendrimers are synthesized from DSM polyamine dendrimers (generations 1 to 5) and cleanly and selectively recognize the H2PO4- anion.
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http://dx.doi.org/10.1039/b211772jDOI Listing
February 2003

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

J Am Chem Soc 2003 Mar;125(9):2617-28

Groupe Nanoscience et Catalyse, LCOO, UMR CNRS Nomicron. 5802, Université Bordeaux I, 33405 Talence Cedex, France.

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.
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http://dx.doi.org/10.1021/ja021325dDOI Listing
March 2003

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

J Am Chem Soc 2003 Feb;125(5):1150-1

Groupe Nanosciences Moléculaires et Catalyse, LCOO, UMR CNRS N degrees 5802, Université Bordeaux I, 33405 Talence Cedex, France.

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.
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http://dx.doi.org/10.1021/ja020833kDOI Listing
February 2003