Monolayers of Thiol-Terminated Dendrimers on the Surface of Planar and Colloidal Gold

Chechik, Victor; Crooks, Richard M.

doi:10.1021/la9817314

Cited by 114 publications

(97 citation statements)

References 39 publications

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“…PEI2-GNP conjugates were synthesized by reducing hydrogen tetrachloroaurate with sodium borohydride (39)(40)(41)(42) in the presence of the thiol-modified PEI2 (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

Conjugation to gold nanoparticles enhances polyethylenimine's transfer of plasmid DNA into mammalian cells

Thomas

Klibanov

2003

Proc. Natl. Acad. Sci. U.S.A.

515

322

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Branched polyethylenimine (PEI) chains with an average molecular mass of 2 kDa (PEI2) have been covalently attached to gold nanoparticles (GNPs), and the potency of the resulting PEI2-GNPs conjugates as vectors for the delivery of plasmid DNA into monkey kidney (COS-7) cells in the presence of serum in vitro has been systematically investigated. The transfection efficiencies vary as a function of the PEI͞gold molar ratio in the conjugates, with the best one (PEI2-GNPII) being 12 times more potent than the unmodified polycation. This potency can be further doubled by adding amphiphilic N-dodecyl-PEI2 during complex formation with DNA. The resulting ternary complexes are at least 1 order of magnitude more efficient than the 25-kDa PEI, one of the premier polycationic gene-delivery vectors. Importantly, although unmodified PEI2 transfects just 4% of the cells, PEI2-GNPII transfects 25%, and the PEI2-GNPII͞dodecyl-PEI2 ternary complex transfects 50% of the cells. The intracellular trafficking of the DNA complexes of these vectors, monitored by transmission electron microscopy, has detected the complexes in the nucleus <1 h after transfection.G ene therapy holds great promise for treating diseases ranging from inherited disorders to acquired conditions and cancer (1-4). The most common vectors (carriers) in current clinical trials are recombinant viruses, wherein the gene of interest is covalently inserted into the viral genome. Unfortunately, such severe side reactions encountered in patients as immune response and insertional mutagenesis leading to death, carcinogenesis, or germ-cell-line alterations pose serious concerns about the clinical application of viral vectors (5-7) and have prompted development of nonviral delivery systems (8-10). Unlike viral vectors, nonviral ones rely on the formation of noncovalent assemblies between DNA (a polyanion) and cationic polymers or liposomes. Vectors based on cationic polymers (polycations) are particularly attractive because of their synthetic maneuverability, allowing incorporation of multiple functional elements within the same molecule without compromising DNA-binding ability (11)(12)(13). And yet, available polycations are handicapped by their low potencies (14, 15), prompting the search for new ones with better transfection efficiencies (16)(17)(18)(19)(20). It is likely that major improvements may be brought about by elucidating the mechanism of gene delivery by those vectors already relatively competent, followed by their targeted chemical derivatization to overcome extra-and͞or intracellular barriers to nonviral gene delivery (10). For these reasons, polyethylenimine (PEI), a synthetic ''proton-sponge'' polycation (21-24) introduced for transfection a few years ago, is an ideal candidate for such a quest.The transfection efficiency and toxicity of PEI correlate strongly with its molecular mass. For example, PEI2 is some 2 orders of magnitude less efficient than its 25-kDa counterpart (PEI25) at the same concentration, presumably because of its inability to condense...

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“…PEI2-GNP conjugates were synthesized by reducing hydrogen tetrachloroaurate with sodium borohydride (39)(40)(41)(42) in the presence of the thiol-modified PEI2 (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

Conjugation to gold nanoparticles enhances polyethylenimine's transfer of plasmid DNA into mammalian cells

Thomas

Klibanov

2003

Proc. Natl. Acad. Sci. U.S.A.

515

322

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“…This can be done by adding different surfactants on the surface of the particles, thus making the surface non-polar and more compatible with the organic solvents used in inks. Typical surfactants include organic acids [8] and acid anhydrides, thiols, [9] organic phosphates [10], and polymers with reactive polar functional groups [11,12]. In order to achieve sufficient mechanical durability, both synthetic products and natural fatty acids are used as binders of the solid components in the printed patterns.…”

Section: Introductionmentioning

confidence: 99%

Formulation of Screen Printable Cobalt Nanoparticle Ink for High Frequency Applications

Nelo¹,

Sowpati²,

Palukuru³

et al. 2010

PIER

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Abstract-In this work, magnetic metallic cobalt nanoparticles with an average particle size of 28 nm were processed as a dry powder with surface coating material and other organic additives to form a screen-printable ink to be cured at 110 • C. EFTEM and TGA-DSC-MS-analyses were used to measure the thickness of the polymer, its coverage on cobalt nanoparticles and the inorganic solid content of the ink. The resolution of the printed patterns and the print quality were evaluated by surface profiler, FESEM and optical microscopy. The relative permeability of the thick film patterns with good printability was measured with a shorted microstrip structure over the frequency range of 0.2 to 4 GHz and complex permeability values were calculated from measured scattering parameter data. The ink attained real part of complex permeability values of up to 5.13 at 200 MHz with 70 wt.% of magnetic filler. The developed ink can be utilized in various printed electronics applications such as antenna substrates and magnetic sensors.

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“…Dendritic wedges can be coupled to the support through the focal point (Figure 11(a)), through aromatic fragments in the interior of the dendron (Figure 11(b)), or through the peripheral functionalities (Figure 11(c)), whereas dendrimers are usually immobilized through the peripheral functional groups. In addition, a covalent binding through the focal point onto a previously activated substrate usually leads to a dendron monolayer ( Figure 11 A common method to dendronize gold surfaces is by chemisorption of a thiol moiety [95] using focally-substituted organothiol dendrons. Gorman et al [96] found that as the number of hyperbranches in the thiolate dendron increased from one to three, the dendron adlayers became initially less and then more permeable.…”

Section: Organization Of the Dendron Layermentioning

confidence: 99%

Dendronization: A Useful Synthetic Strategy to Prepare Multifunctional Materials

et al. 2012

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Dendronization is a synthetic methodology that offers important advantages.The resulting products, which are called dendronized materials, present new and specific properties. This review shows numerous examples in which individual dendrons are used as building blocks to prepare more complex arrays via covalent or non-covalent interactions. In particular, it points out how the structural information programmed into the dendritic architecture can be used in the dendronization process to generate nanostructures with specific tailored properties. We emphasize the use of different dendrons, with diverse chemical structure and size, to functionalize diverse substrates like linear polymers, and plane and curved inorganic surfaces. Apart from this, the review also demonstrates that self-assembly represents an ideal approach to create well-defined hyperbranched surfaces and it includes some discussion about the ability of both organic and inorganic building blocks to direct this process.

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Monolayers of Thiol-Terminated Dendrimers on the Surface of Planar and Colloidal Gold

Cited by 114 publications

References 39 publications

Conjugation to gold nanoparticles enhances polyethylenimine's transfer of plasmid DNA into mammalian cells

Conjugation to gold nanoparticles enhances polyethylenimine's transfer of plasmid DNA into mammalian cells

Formulation of Screen Printable Cobalt Nanoparticle Ink for High Frequency Applications

Dendronization: A Useful Synthetic Strategy to Prepare Multifunctional Materials

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