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First-generation Dendrimers (first-generation + dendrimer)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

Branched KLVFF Tetramers Strongly Potentiate Inhibition of ,-Amyloid Aggregation

CHEMBIOCHEM, Issue 15 2007
Sidhartha M. Chafekar
Abstract The key pathogenic event in the onset of Alzheimer's disease (AD) is the aggregation of ,-amyloid (A,) peptides into toxic aggregates. Molecules that interfere with this process might act as therapeutic agents for the treatment of AD. The amino acid residues 16,20 (KLVFF) are known to be essential for the aggregation of A,. In this study, we have used a first-generation dendrimer as a scaffold for the multivalent display of the KLVFF peptide. The effect of four KLVFF peptides attached to the dendrimer (K4) on A, aggregation was compared to the effect of monomeric KLVFF (K1). Our data show that K4 very effectively inhibits the aggregation of low-molecular-weight and protofibrillar A,1,42 into fibrils, in a concentration-dependent manner, and much more potently than K1. Moreover, we show that K4 can lead to the disassembly of existing aggregates. Our data lead us to propose that conjugates that bear multiple copies of KLVFF might be useful as therapeutic agents for the treatment of Alzheimer's disease. [source]

Tailored Control and Optimisation of the Number of Phosphonic Acid Termini on Phosphorus-Containing Dendrimers for the Ex-Vivo Activation of Human Monocytes

CHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2008
Olivier Rolland
Abstract The syntheses of a series of phosphonic acid-capped dendrimers is described. This collection is based on a unique set of dendritic structural parameters,cyclo(triphosphazene) core, benzylhydrazone branches and phosphonic acid surface,and was designed to study the influence of phosphonate (phosphonic acid) surface loading towards the activation of human monocytes ex vivo. Starting from the versatile hexachloro-cyclo(triphosphazene) N3P3Cl6, six first-generation dendrimers were obtained, bearing one to six full branches, that lead to 4, 8, 12, 16, 20 and 24 phosphonate termini, respectively. The surface loading was also explored at the limit of dense packing by means of a first-generation dendrimer having a cyclo(tetraphosphazene) core and bearing 32 termini, and with a first-generation dendrimer based on a AB2/CD5 growing pattern and bearing 60 termini. Human monocyte activation by these dendrimers confirms the requirement of the whole dendritic structure for bioactivity and identifies the dendrimer bearing four branches, thus 16 phosphonate termini, as the most bioactive. [source]

Vapor Sorption and Electrical Response of Au-Nanoparticle, Dendrimer Composites,

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2007
N. Krasteva
Abstract Films comprising Au nanoparticles and polyphenylene dendrimers (first and second generation) are deposited onto transducer substrates via layer-by-layer self-assembly and characterized by atomic force microscopy and X-ray photoelectron spectroscopy. Their sorption behavior is studied by measuring the uptake of solvents from the vapor phase with quartz crystal microbalances (QCMs). The resistance of the films is simultaneously monitored. Both sensor types, QCMs and chemiresistors, give qualitatively very similar response isotherms that are consistent with a combination of Henry- and Langmuir-type sorption processes. The sorption-induced increase in relative differential resistance scales linearly with the amount of analyte accumulated in the films. This result is in general agreement with an activated tunneling process for charge transport, if little swelling and only small changes in the permittivity of the film occur during analyte sorption (a first-order approximation). The relative sensitivity of the films to different solvents decreases in the order toluene,,,tetrachloroethylene,>,1-propanol,,,water. Films containing the larger second-generation dendrimers show higher sensitivity than films containing first-generation dendrimers. [source]

Dendrimeric Oligo(phenylenevinylene)-Extended Dithieno[3,2- b:2,,3,- d]phospholes,Synthesis, Self-Organization, and Optical Properties

CHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2009
Carlos Romero-Nieto
Abstract A boost from the branches: Incorporation of the dithieno[3,2- b:2,,3,- d]phosphole system as a core in oligo(phenylenevinylene) dendrimers (an example is shown here) provides materials that exhibit energy-transfer features relaying incoming photons from the dendrons towards the core, which in turn shows enhanced emission intensity. The optical properties and self-assembly features of the dendrimers can be impacted by the terminal groups (-H, -CF3, or -NPh2) employed. To establish this system as a fluorescent core in ,-conjugated dendrimers, a series of oligo(phenylenevinylene) (OPV)-extended dithieno[3,2- b:2,,3,- d]phospholes has been prepared by means of a Wittig,Horner protocol with a dithienophosphole dialdehyde and appropriately functionalized phosphonates. The "zero-generation" model compounds have provided the general accessibility of OPV-functionalized dithienophospholes, and show varying emission colors covering the optical spectrum from green to red. Expansion of the synthetic strategy towards the corresponding first-generation dendrimers has provided materials that show intriguing self-organization features in case of the phenyl-terminated dendrimer, forming large one-dimensional microfibres, as well as desirable energy-transfer processes from the dendrons to the dithienophoshole core resulting in an enhanced emission intensity for the latter. The present study has revealed that the terminal end-groups of the OPV branches have significant impact on the optical features of the OPV dendrimers as a whole. [source]

Tailored Control and Optimisation of the Number of Phosphonic Acid Termini on Phosphorus-Containing Dendrimers for the Ex-Vivo Activation of Human Monocytes