Polyanionic dendrimers

Some polyanionic dendrimers act as micellar molecules [58]. Newkome et al. first synthesised water-soluble dendrimers, whose hydrophobic molecular niches can accommodate guests. The periphery of such dendrimers was furnished with 

Preparation of mono-adducts of fullerene - for studies on electrostatic interactions - was undertaken by cyclopropanation of fullerene with appropriately functionalised malonic esters 1 (Bingel reaction) to form 2. Coupling with the tert-butyl protected oligoamide-amino-dendron 3 and subsequent hydrolysis lead to the water-soluble fullerene dendron 5, which can carry up to nine negative charges after depro to nation. After association with the zinc complex of cytochrome C, photoinduced electron transfer (PET) from the redox protein to the fullerene can be accomplished, which was studied by fluorescence spectroscopy. 

Hyperbranched polymers of polybenzene type can be rendered water-soluble like the above-mentioned monodisperse species by introduction of carboxyl groups [62]. Starting from 3,5-dibromophenylboronic acid 1 as AB2 monomeric building block (Fig. 4.34), the polycondensate 2 was assembled in an aryl-aryl coupling analogous to Suzuki coupling in the presence of Pd(0), and subsequently reacted with carbon dioxide to form the hyperbranched compounds 3 with terminal carboxylate groups  

Polycationic dendritic molecules can generally be prepared in the following ways  

The ability to transport nucleic acid into cells depends upon the size of the dendrimer. Thus phosphorus-based dendrimers of the third, fourth, and fifth generation are more efficient than those of lower generations (Fig. 4.35). The nature of the quaternary ammonium end groups also has an influence on transfection ability A dendrimer that is methylated at the terminal nitrogens is less effective than a protonated dendrimer. 

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Fig. 1.34. The polyanionic dendrimer able to form a metallodendrimer with four Rh(I) olefin moieties.

A new class of hydrogels is also obtained when a polyanionic dendrimer such as, for example, 41-[Gi] (Scheme 28) is heated at 60°C for two days in the presence of Girard P reagents [43]. 

Figure 23 Illustration of hierarchical self-assembly of a C6-functionalized hexamer 80 and polyanionic dendrimer 81 into fibers using anion pairing approach, (a and b) TEM image of the fibers (c) SAED pattern from fiber (d) molecular model of packing. Adapted with permission from Ref 08AMi38i. Copyright 2008 WiLEY-VCH Verlag GmbH Co. KGaA, Weinheim.

Fig. 3 Polyanionic dendrimers interacting with histone proteins, (a) Molecular structure of the first generation polyanionic dendrimer. (b) Confocal scanning niit scope images shown the co-localization of poly anionic dendrimer (5, red) with histone H4 proteins (green), (c) Isothermal titratimi graph shows the strong interaction between histone HI with 5. (d) Spectral analysis of the 5/histones...

A simple, highly efficient method for the synthesis of polyanionic dendrimers (13) and (14) as potential antiviral drugs has been presented by Salamoficzyk. The mild conditions of both the coupling and virtually quantitative deprotection reactions, provided highly pure and water-soluble macromolecular materials in good overall yields. ... 

Braun M, Atalick S, Guldi Dirk M, Lanig H, Brettreich M, Burghardt S, Hatzimarinaki M, Ravanelli E, Prato M, Van Eldik R, Hirsch A (2003) Electrostatic Complexation and Photoinduced Electron Transfer between Zn-Cytochrome c and Polyanionic Fullerene Dendrimers. Chem. Eur. J. 9 3867-3875. 

Depending on the type of charges, polycationic PEG-P(Lys) and polyanionic PEG-P(Asp) are used for the preparation of such PIC micelles (Fig. 6). Based on recent research, core-shell type PIC micelles with a 52 nm diameter were prepared from a Zn-porphyrin-dendrimer with 32 carboxylate groups on the periphery, 32(-)DPZn, and PEG-P(Lys) block copolymers (56,57). On the contrary, when the dendrimer structure is cationic, a third-generation porph3rrin-dendrimer with 32 primary amine groups on the periphery, 32(+)DPZn, and PEG-P(Asp) were used to prepare a PIC micelle, and had a spherical structure with a 55 nm-sized diameter (58). Both... 

Figure 6 The PIC micelles loading photosensitizers for photodynamic therapy. PEG-P(Asp) (block polyanions) and PEG-P(Lys) (block polycations) are selected according to the surface charge of Zn-porphyrin-dendrimer s.

Witvrouw, M., Fikkert, V., Pluymers, W., Matthews, B., Mardel, K., Schols, D., Raff, J., Debyser, Z., De, C.E., Holan, G., Pannecouque, C. Polyanionic (i.e., polysulfonate) dendrimers can inhibit the replication of human immunodeficiency virus by interfering with both virus adsorption and later steps (Reverse transcriptase/integrase) in the virus replicative cycle. Mol. Pharmacol. 58(5), 1100-1108 (2000)... 

Polycationic and Polyanionic Core-Shell Polyphenylene Dendrimers. 214... 

The formation of vesicles can also be induced by electrostatic interaction or electrostatic self-assembly. Among others, it was shown that LUVs are obtained when a polycation is mixed with a polyanion-fc-poly(ethylene glycol). The vesicle size can be controlled by changing the polymer concentration. Vesicles are also obtained when a polyanion- -poly(ethylene glycol) is mixed with a cationic azobenzene surfactant. In that case, the vesicles are photoresponsive, that is, they dissemble if the azobenzene is isomerized from the irans form to the cis form. Finally, vesicles can also be prepared by mixing a cationic dendrimer and an anionic sulfonate dye. ... 

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