Dendritic Poly Research Articles

Synthesis and aqueous solution behaviors of sodium sulfonate‐terminated dendritic poly(ester‐amine)

AbstractSodium sulfonate‐terminated dendritic poly(ester‐amine) (SPEA) was synthesized by sulfonation of acrylic double bond‐terminated dendritic poly(ester‐amine) (APEA) with sodium hydrogen sulfite (NaHSO3) in mixture of diglycol and 2‐butanone under normal pressure. The structure of SPEA was characterized by IR, 1H‐NMR, and elemental analysis. SPEA was water‐soluble. 1.0–40.0% (mass) SPEA aqueous solutions appeared as dilatant fluid. When pH value varied from 1.5 to 12.0, the viscosity of 1–5% (mass) SPEA aqueous solutions changed very small, and the electric conductivity almost kept stable within pH 3.0–10.0. The relationship between the viscosity and the concentration of SPEA water solutions was similar to that of NaCl water solutions. The surface tension of SPEA water solutions was lower than that of polyethylene glycol 2000 water solutions with the same concentration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Efficient delivery of siRNA using dendritic poly( l-lysine) for loss-of-function analysis

RNA interference (RNAi) is a valuable tool for the validation of gene identification and functional genomics. Previously, it was reported that 6th generation dendritic poly( l-lysine) (KG6) transfected DNA into several cultivated cell lines with high efficiency and without any cytotoxic effects. In this study, the potential of KG6 to be an efficient siRNA carrier is investigated. KG6 showed effective knockdown of GAPDH with low cytotoxicity in combination with the weak-base amphiphilic peptide, Endo-Porter. In addition, the knockdown of PEPCK, which is the rate-limiting enzyme for gluconeogenesis, led to a reduction in glucose production in rat hepatoma H4IIEC3 cells. Knockdown of organic cation transporter 1 (OCT1), which is thought to be the gene that influences metformin action, was shown to successfully diminish the ability of metformin to inhibit gluconeogenesis in H4IIEC3 cells. In conclusion, using a combination of KG6 and Endo-Porter, a model system in which genes that influence metformin action can be identified was successfully constructed.

A novel density-tunable nanocomposites of CdTe quantum dots linked to dendrimer-tethered multi-wall carbon nanotubes

A novel nanocomposite of CdTe–PAMAM–MWNT was synthesized by covalently linking CdTe quantum dots (QDs) onto highly water-soluble multi-wall carbon nanotubes (MWNTs) functionalized with dendritic poly(amidoamine) (PAMAM). The IR, UV–vis and TEM methods has been used for the characterization of the composites. A facile method for controlling the density of QDs in the composite by simply changing the ratio of CdTe QDs/PAMAM–MWNT, as was verified by the TEM images. The experiments revealed that PAMAM and PAMAM–MWNT, once covalently linked with CdTe QDs, had remarkable effect on their fluorescence property. The fluorescence intensity of the CdTe–PAMAM hybrid was substantially enhanced as a compared to that of QDs, and the fluorescence was quenched greatly when QDs reacted with PAMAM–MWNT. The experimentally observed phenomena indicate that electron and energy transfer took place efficiently between CdTe QDs, PAMAM and MWNTs in the novel composite. These nanocomposits might hold great potential in photoelectron device and biotechnology applications.

Synthesis and Cylinder Microdomain Structures of Hybrid Block Copolymers of π-Conjugated and Dendritic Poly(phenylazomethine)s and Flexible and Linear PEO. Volume 40, Number 7, April 3, 2007, pp 2606−2612.

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionSynthesis and Cylinder Microdomain Structures of Hybrid Block Copolymers of π-Conjugated and Dendritic Poly(phenylazomethine)s and Flexible and Linear PEO. Volume 40, Number 7, April 3, 2007, pp 2606−2612.Yang Gao, Xiwen Zhang, Miao Yang, Xinjun Zhang, Wei Wang, Gerhard Wegner, and Christian BurgerCite this: Macromolecules 2007, 40, 17, 6439Publication Date (Web):July 18, 2007Publication History Published online18 July 2007Published inissue 1 August 2007https://doi.org/10.1021/ma071500gCopyright © 2007 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views273Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (42 KB) Get e-Alerts Get e-Alerts

933. In Vivo siRNA Delivery Mediated by Dendritic Poly(L-Lysine)

933. In Vivo siRNA Delivery Mediated by Dendritic Poly(L-Lysine)

Novel Symmetric Amphiphilic Dendritic Poly(l-lysine)-b-Poly(l-lactide)-b-Dendritic Poly(l-lysine) with High Plasmid DNA Binding Affinity as a Biodegradable Gene Carrier

This study communicates the molecular design, preparation, and biological application of novel symmetric amphiphilic polycationic dendritic poly(L-lysine)-b-poly(L-lactide)-b-dendritic poly(L-lysine) D2-LLA15-D2 bearing two two-generation poly(L-lysine) PLL dendrons D2 and a central hydrophobic biodegradable poly(L-lactide) block LLA15. First, an amino-protected precursor of L1-OH was designed and synthesized and was further employed to prepare L1-LLA15 with an organic 4-(dimethylamino)-pyridine-mediated living-ring-opening polymerization of l-lactide. Subsequently, the hydroxy end-capped L1-LLA15 was coupled to synthesize a new triblock L1-LLA15-L1 with two one-generation amino-protected PLL dendrons L1. Furthermore, with a repeated trifluoroacetic-acid-mediated amino deprotection-protection cycle, new amphiphilic triblock D2-LLA15-D2 was successfully prepared. By means of NMR, mass spectrometry, and gel permeation chromatography, these synthetic precursors and final amphiphilic product were characterized to bear well-defined triblock structures. In addition, this synthesized amphiphilic triblock polycationic macromolecule was applied as a new polycationic plasmid DNA carrier, and its DNA binding affinity was examined via an agarose electrophoresis and a fluorescence titration assay along with two important references of hydrophilic dendritic D2-HEX-D2 and double-hydrophilic D2-PEG-4K-D2 bearing the same two D2 dendrons; much enhanced DNA binding affinity was interestingly revealed for the new amphiphilic structural D2-LLA15-D2. Moreover, the assembled polyplex microparticles of plasmid DNA/polycationic carrier were further analyzed by dynamic light scattering and transmission electron microscopy, indicating their averaged nanoparticle size around 150-200 nm. As for the cytotoxicity of the new D2-LLA15-D2, MTT assays were conducted with a human hepatocellular carcinoma cell line (SMMC-7721), indicating a very low cytotoxicity as compared with commercial linear PLL-23K and PEI-2K, and a DNase I degradation of the assembled polyplex particles was also done in the HBS buffer solution to evaluate their stabilities. Finally, employing the new amphiphilic D2-LLA15-D2 as gene carrier, in vitro gene transfection experiments were conducted with the SMMC-7721 cell line, indicating a transfection efficiency increase of at least 10 times higher than that of the naked plasmid DNA under a N/P charge ratio of 10. Therefore, these interesting results may provide a new possible way to construct efficient polycationic macromolecular gene carriers with low toxicity and less expensive low-generation PLL dendrons.

Synthesis and characterization of dendritic poly( l-lysine) containing porphyrin–fullerene moieties

Amphiphilic l-lysine dendrons containing porphyrin and fullerene bearing amino acids with the ratio of 2:0, 2:1 and 1:1 were synthesized and characterized using UV–visible absorption spectroscopy, fluorescence emission spectroscopy and transmission electron microscopy. Photoluminescence spectra of these dendrimers showed photoluminescence quenching due to photoinduced electron transfer from porphyrin to fullerene moieties. Transmission electron microscopic observation evidenced the self-association of these dendrimers in water. Controllable and reversible dissociation and re-aggregation of some of the water soluble dendrimers have been investigated using electronic absorption and fluorescence spectra upon the addition of 2-hydroxypropyl-β-cyclodextrin and 1-adamantanecarboxylic acid in their aqueous dispersion. Enhanced ellipticity of dendritic porphyrin–fullerene conjugate compared to that only dendritic porphyrin indicates intramolecular porphyrin–fullerene interactions.

Crystallization behavior and micelle formation of star-shaped amphiphilic block copolymer based on dendritic poly(ether-amide)

The star-shaped amphiphilic block copolymer (DPEA-PCL-PEG) was prepared through ring opening polymerization of ε-caprolactone (CL) initiated by hydroxyl end-capped dendritic poly(ether-amide) (DPEA-OH), then coupling with monomethoxy-terminated poly(ethylene-glycol) (PEG) via an esterification process. The molecular structure was verified by FT-IR, 1H NMR and gel permeation chromatography (GPC). The number average molecular weight of the PCL arm was calculated to be about 1910 g mol −1 by 1H NMR analysis. The number average molecular weight of the copolymer was determined to be 74,020 with the molecular weight distribution of 1.15 by GPC. The DSC and X-ray diffraction analysis indicated that the copolymer possesses double melting and crystallization peaks, attributed to PCL and PEG segments in DPEA-PCL-PEG. The corresponding melting and crystallization temperature, and value of crystallinity are much lower than that of their individual homopolymers. The copolymer easily formed the core–shell structural nanoparticles as micelles in water with a lower critical micelle concentration of 5.524 mg l −1.

Facile synthesis of dumbbell‐shaped dendritic‐linear‐dendritic triblock copolymer via reversible addition‐fragmentation chain transfer polymerization

AbstractWe report the first instance of facile synthesis of dumbbell‐shaped dendritic‐linear‐dendritic triblock copolymer, [G‐3]‐PNIPAM‐[G‐3], consisting of third generation poly(benzyl ether) monodendrons ([G‐3]) and linear poly(N‐isopropylacrylamide) (PNIPAM), via reversible addition‐fragmentation chain transfer (RAFT) polymerization. The key step was the preparation of novel [G‐3]‐based RAFT agent, [G‐3]‐CH2SCSSCH2‐[G‐3] (1), from third‐generation dendritic poly(benzyl ether) bromide, [G‐3]‐CH2Br. Due to the bulky nature of [G‐3]‐CH2Br, its transformation into trithiocarbonate 1 cannot go to completion, a mixture containing ∼80 mol % of 1 and 20 mol % [G‐3]‐CH2Br was obtained. Dumbbell‐shaped [G‐3]‐PNIPAM310‐[G‐3] triblock copolymer was then successfully obtained by the RAFT polymerization of N‐isopropylacylamide (NIPAM) using 1 as the mediating agent, and trace amount of unreacted [G‐3]‐CH2Br was conveniently removed during purification by precipitating the polymer into diethyl ether. The dendritic‐linear‐dendritic triblock structure was further confirmed by aminolysis, and fully characterized by gel permeation chromatography (GPC) and 1H‐NMR. The amphiphilic dumbbell‐shaped triblock copolymer contains a thermoresponsive PNIPAM middle block, in aqueous solution it self‐assembles into spherical nanoparticles with the core consisting of hydrophobic [G‐3] dendritic block and stabilized by the PNIPAM central block, forming loops surrounding the insoluble core. The micellar properties of [G‐3]‐PNIPAM310‐[G‐3] were then fully characterized. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1432–1445, 2007

Synthesis and Cylinder Microdomain Structures of Hybrid Block Copolymers of π-Conjugated and Dendritic Poly(phenylazomethine)s and Flexible and Linear PEO

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTADDITION / CORRECTIONThis article has been corrected. View the notice.Synthesis and Cylinder Microdomain Structures of Hybrid Block Copolymers of π-Conjugated and Dendritic Poly(phenylazomethine)s and Flexible and Linear PEOYang Gao, Xiwen Zhang, Miao Yang, Xinjun Zhang, Wei Wang, Gerhard Wegner, and Christian BurgerView Author Information The Key Laboratory of Functional Polymer Materials and Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China Max-Planck-Institute for Polymer Research, Ackermannweg 10, Postfach 3148, D-55128, Mainz, Germany Chemistry Department, Stony Brook University, Stony Brook, New York 11794-3400 Cite this: Macromolecules 2007, 40, 7, 2606–2612Publication Date (Web):March 1, 2007Publication History Received17 December 2006Revised26 January 2007Published online1 March 2007Published inissue 1 April 2007https://doi.org/10.1021/ma062881lCopyright © 2007 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views559Altmetric-Citations17LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (320 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Chemical structure,Copolymers,Dendrons,Lattices,Molecular structure Get e-Alerts

Synthesis and thermally responsive characteristics of dendritic poly(ether-amide) grafting with PNIPAAm and PEG

A series of thermally responsive dendritic core–shell polymers were prepared based upon dendritic poly(ether-amide) (DPEA), modified with carboxyl end-capped linear poly( N-isopropylacrylamide) (PNIPAAm-COOH) or both PNIPAAm-COOH and carboxyl end-capped methoxy polyethylene glycol (PEG-COOH) in different ratios via an esterification process to obtain DPEA–PNIPAAm or DPEA–PNIPAAm–PEG. Their molecular structures were verified by gel permeation chromatography, and 1H NMR and FTIR spectroscopy. The temperature-dependent characteristics study has revealed that DPEA–PNIPAAm exhibits a lower critical solution temperature (LCST) of about 34 °C, whereas DPEA–PNIPAAm–PEG polymers with the PNIPAAm/PEG ratio of about 1.0 and 0.4 possess about 36 °C and 39 °C, respectively, compared with 32 °C for homopolymer PNIPAAm. The critical aggregation temperature was investigated using fluorescence excitation spectrum of pyrene as a sequestered guest molecule based upon the sharp increase of the I 338/ I 333 value.

Synthesis of amphiphilic poly(ether-amide) dendrimer endcapped with poly(ethylene glycol) grafts and its solubilization to salicylic acid

An amphiphilic dendrimer (DPEA-PEG) grafting polyethylene glycol at the terminals was prepared by endcapping of dendritic poly(ether-amide) (DPEA) with isocyanate terminated linear polyethylene glycol (PEG-NCO). The molecular structure was verified by gel permeation chromatography (GPC), 1H NMR and FT-IR. The micelle characteristic of DPEA-PEG in water was investigated. The critical micelle concentration (CMC) was determined by a fluorescence technique to be 55.5mg/L. The hydrodynamic radius of micelles was measured by dynamic light scattering (DLS) to be 76.2nm. The UV–vis spectrum showed that the solubility of salicylic acid increased from 1.91 to 2.78mg/L when the concentration of DPEA-PEG attained 5mg/mL in an aqueous solution.

Synthesis of Water‐Soluble Dendritic Conjugated Polymers for Fluorescent DNA Assays

AbstractSummary: Cationic water‐soluble dendritic poly(fluorene)s with positively charged amines on the exterior (PFP‐G0–2) can be prepared by a macromonomer (generation‐by‐generation) approach. The charge densities of PFP‐G0–2 can control their distances to DNA by electrostatic interactions. The PFP‐G2 with higher generation of dendritic side chains possesses a higher charge density, and gives rise to efficient fluorescence resonance energy transfer (FRET) to a signaling fluorescein labeled at the terminus of DNA. These new conjugated polymers form less aggregates and yield more efficient FRET in a tetrahydrofuran/H2O mixed solvent as compared to in pure water. The sensitivity of the DNA sensor is improved by utilizing highly dendritic conjugated polymers.Structure of the dendritic conjugated polymer PFP‐G2.magnified imageStructure of the dendritic conjugated polymer PFP‐G2.

Structural advantage of dendritic poly( l-lysine) for gene delivery into cells

This study aimed to investigate the relationships between structures of gene carrier molecules and their activities for gene delivery into cells. We compared 2 types of poly( l-lysine) as carriers, that is, dendritic poly( l-lysine) (KG6) and linear poly( l-lysine) (PLL). KG6 formed a neutral DNA complex, and its DNA compaction level was weaker than that of PLL. The amount of DNA binding and uptake into cells mediated by PLL was 4-fold higher than that with KG6. However, KG6-mediated gene expression was 100-fold higher than that by PLL. Since p K a values of terminal amines of KG6 were lowered even though small amounts of DNA were internalized into cells, sufficient DNA amounts for effective gene expression escaped to the cytosol due to the proton sponge effect in the endosome. In addition, weakly compacted DNA with KG6 was advantageous in accessing RNA polymerase in the cell nucleus. On the other hand, PLL did not show the proton sponge effect in the endosome and resulted in strong compaction of DNA. Even though large DNA amounts were internalized into cells, most of the DNA would not take part in gene expression systems in the nucleus. Amount of induced cytokine production after intravenous injection of DNA complexes with KG6 and PLL was low, and was similar to the case when DNA was injected alone. Therefore, no significant difference in effects on cytokine production was observed between KG6 and PLL.

Synthesis of dendritic poly(urethane acrylate) used for UV-curable coatings

The UV-curable dendritic poly(urethane acrylate) (DPUA) was prepared from 2,4-toluene diisocyanate (TDI), β-hydroxyethyl arcylate (HEA) and dendritic polyamine (DPAM). The structure of the material was characterized by 1H NMR and FT-IR spectroscopes. The viscosity of the obtained products, the hardness, flexibility, curing speed, mechanical and thermal stability of UV-cured films were also examined. Results showed that this dendrimer has some superior properties and can be used for UV curing coating.

Biodistribution characteristics of amino acid dendrimers and their PEGylated derivatives after intravenous administration

In this study, we synthesized dendritic poly( l-lysine)s (DPKs), dendritic poly( l -ornithine)s (DPOs), which are constructed as novel amino acid dendrimers, and PEGylated KG6 (the sixth generation of DPKs), and evaluated the physicochemical properties and biodistribution characteristics of these dendrimers. The particle size of DPKs and DPOs was well controlled in the nanometer range. The zeta-potential of these dendrimers was slightly positive and this gradually increased in association with their generation. After intravenous administration to mice, all tested dendrimers cleared rapidly from blood flow and mainly accumulated in the liver and kidney. The hepatic and renal accumulation changed in a generation-dependent manner. In contrast, no significant distributional differences between same generation of DPK and DPO were observed, although the constituent amino acids, particle size, and zeta-potential were different. However, PEGylation of KG6 caused great changes in particle size, zeta-potential, blood retention and organ distribution in vivo, indicating that the PEGylation is applicable strategy to improve biodistribution characteristics of dendrimeric molecules. The information provided by this study will be helpful for the development of future drug delivery systems using amino acid dendrimers as safe drug carriers.

Growth of multi-amine terminated poly(amidoamine) dendrimers on the surface of carbonnanotubes

An in situ repetitive divergent polymerization strategy was employed to growmulti-amine poly(amidoamine) dendritic macromolecules on the surfaces ofmultiwalled carbon nanotubes (MWNTs), affording novel three-dimensional(3D) molecular nanocomposites. The crude MWNTs were oxidized usingH2SO4/HNO3 = 3:1 (v/v) and then reacted with thionyl chloride, resulting in MWNTs functionalized withchlorocarbonyl groups (MWNT-COCl). MWNT-COCl, when reacted with an excess ofethylenediamine, produced amine-functionalized MWNT supported initiators(MWNT-NH2). Usingthe MWNT-NH2 as the growth supporter and methylacrylate/ethylenediamine as building blocks,multi-amine dendritic poly(amidoamine) macromolecules were covalently grafted onto thesidewalls and ends of MWNTs via Michael addition reaction and amidation. Thermalgravimetric analysis (TGA) measurements showed that the weight ratio of theas-grown dendritic polymers on the MWNT surfaces lay in the 10%–50% range. Theproducts were also characterized by Fourier transform infrared (FTIR), Raman,nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM)analysis. The results indicate that the dendrimers are grafted onto the surface ofMWNTs. The as-prepared nanocomposites exhibit excellent dispersibility in water.

Modification and Electrochemical Properties of Poly(phenylazomethine) Derivatives

AbstractSummary: Oligo(phenylazomethine)s (OPAs) and aniline‐capped OPAs (OPA's) are used as model compounds of polyphenylazomethine (PPA), and their fundamental properties and their modification methods are investigated. Cyclic voltammograms of bis(diphenylmethyleneamino)benzene (OPA2′) showed irreversible redox response in the presence of trifluoroacetic acid. A selective synthesis of oligophenanthridine was achieved through the photocyclization of OPA2′ in concentrated sulfuric acid. Stepwise complexation behavior in dendritic poly(phenylazomethine)s (DPAs) was supported by the shell‐selective reduction of the imines. Using the shell‐selective reduction method and the terminal‐modification method of the DPAs, the core and terminals of DPAs were functionalized by ferrocene units, respectively.

Linear-Hyperbranched Block Copolymers Consisting of Polystyrene and Dendritic Poly(carbosilane) Block

A general strategy for the preparation of well-defined diblock copolymers combining a random cascade-branched dendritic (i.e., hyperbranched) and a linear block has been developed. The strategy is based on a linear poly(styrene-b-butadiene) (PS-b-PB) diblock copolymer with high molecular weight PS block and short, functional 1,2-PB block, prepared by conventional anionic polymerization. The functional PB block is used for the grafting of branched AB2-type carbosilane monomers, resulting in the attachment of a hyperbranched structure to the backbone. Slow addition of the methyldi(undecenyl)silane monomers using Karstedt's catalyst permits control of the molecular weight of the hyperbranched block, resulting in high molecular weight linear-hyperbranched diblock copolymers. Molecular weights of the block copolymers ranged between 72 800 and 106 400 g/mol for Mn, and polydispersity Mw/Mn was low (typically below 1.1), as predicted by theory for slow monomer addition. Morphological studies by TEM, AFM, and S...

Synthesis and self-assembly of dendritic-helical block copolypeptides.

Dendritic-helical diblock copolypeptides, dendritic poly(-lysine)--poly(γ-benzyl--glutamate) (PBLG-Lys) were synthesized up to 4th generation of dendritic poly(-lysine). PBLG was synthesized by conventional ring-opening polymerization of γ-benzyl--glutamate--carboxyanhydride with heptyl amine as an initiator. The -terminus of this PBLG was used for further coupling reactions with ,-bis(-butoxycarbonyl)--lysine pentafluorophenylester. These block copolypeptides possess well-defined 3-D structures in solution, and they self-assemble into a fibrous structure a nanoribbon mechanism in toluene. Amphiphilic block copolypeptides were obtained after deprotecting BOC groups at the periphery of the lysine dendrimer block. Due to the well-defined size and structure of the dendritic lysine block and well-defined α-helical conformation of the PBLG block, the block copolypeptides showed a generation-dependent self-assembly behavior in aqueous solution.