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In this manuscript, we have demonstrated an efficient and rapid synthetic strategy for preparation of new fluorene–dendron-hybridized blue light-emitting polymers P1–P7 by the reaction of 9,9 long-chain dialkylated fluorenes M2–M8 with dendronized monomer (M1) under microwave-assisted reaction condition. These fluorene–dendron-hybridized polymers P1–P7 were characterized using different spectroscopic techniques. Furthermore, the optophysical properties of these polymers P1–P7 were studied which revealed that these synthesized polymers P1–P7 have potential to emerge as capable materials in the development of diodes, particularly for blue light emission. In the future, similar approaches would be utilized for preparation of light-emitting polymer composite. [ABSTRACT FROM AUTHOR]

In this manuscript, we discussed the synthesis of non-ionic (C18) and (C18-cis) amphiphiles from [PG]-dendron-based biocompatible starting materials. The physicochemical studies of amphiphiles show some significant results. The presence of an amide as a linker group has affected the hydrophilicity of the amphiphiles to respond to a low critical micelle concentration. The graph of surface tension versus concentration shows that the CMC of non-ionic amphiphiles falls in the range of 18.10 µmol L−1–00.61 µmol L−1. The dynamic light scattering study of the synthesized compounds confirmed that the G.n-amide amphiphiles with the unsaturation 6, 8 and 10 have an average aggregated particle size range of 93.0 nm–13.0 nm, while the average aggregated particle size of saturated amphiphiles 13, 15 and 17 showed a range from 28.0 nm to 7.5 nm. The morphological study of self-aggregated particles of amphiphiles using transmission electron microscopy studies in an aqueous medium showed the worm-like shape for G.1 amphiphiles and circular shape for G.2 and G.3 amphiphiles. [ABSTRACT FROM AUTHOR]

Purpose: The present study reports synthesis, characterization and in vitro evaluation of physicochemical and biological properties of dendritic lipopeptide oligomers comprising L-glutamic acid dendrons and myristoyl tails such that termini of the molecules carry carboxylic ester, carboxylic acid or alcohol functions, which account for nonpolar neutral, polar anionic and polar neutral surfaces, respectively. Methods: Reactions adopted in the current work were fairly rapid, moderately simplified and required fewer coupling reagents. As inherent physicochemical and biological properties depend upon structural details, synthesized compounds were tested for the presence of foaming, nanoparticle formation, antibacterial and anticancer potential, if any. Results: The synthesized nonpolar molecule demonstrated potential to form self-assembled polymeric nanoparticles, whereas the polar molecules demonstrated surfactant-like properties. None of the synthesized molecules demonstrated any inherent antibacterial activity against gram-positive as well as gram-negative bacterial strains, but compound with hydroxyl termini showed anticancer activity hint as a result of preliminary screening. Conclusion: The synthesized molecules demonstrate potential for their application as drug delivery materials and hold scope for further investigations. [ABSTRACT FROM AUTHOR]

Dendritic nanomaterials are unique due to their flexible architectures. So far, many structural analogues of dendritic poly(l-lysine) have been developed. Since its monomer unit is a biodegradable amino acid, poly(l-lysine) derived nanocarriers are biocompatible and safe. In this overview, structural diversity of dendritic poly(l-lysine) scaffold and patents filed on them so far are described. Furthermore, biopharmaceutical properties and therapeutic activity modulations observed from their drug delivery applications are highlighted. Poly(l-lysine) based dendriplexes, dendrosomes and dendrisomes remain novel and nearly unexplored. Since structural modifications can control the biopharmaceutical properties of aforementioned scaffold, achieving programmed drug delivery is possible. Many such structures have demonstrated not only excellent carrier characteristics but few intrinsic therapeutic activities also. A poly(l-lysine) dendrimer product VivaGel is currently under consideration in a new drug application category of various regulatory bodies. As dendritic poly(l-lysine) scaffold is biocompatible unlike many other nanocarriers, its clinical utilization would prove considerably beneficial. [ABSTRACT FROM AUTHOR]

We show that group actions on many treelike compact spaces are not too complicated dynamically. We first observe that an old argument of Seidler (1990) implies that every action of a topological group G on a regular continuum is null and therefore also tame. As every local dendron is regular, one concludes that every action of G on a local dendron is null. We then use a more direct method to show that every continuous group action of G on a dendron is Rosenthal representable, hence also tame. Similar results are obtained for median pretrees. As a related result, we show that Helly's selection principle can be extended to bounded monotone sequences defined on median pretrees (for example, dendrons or linearly ordered sets). Finally, we point out some applications of these results to continuous group actions on dendrites. [ABSTRACT FROM AUTHOR]

Abstract: A series of first-, second-, and third-generation dendronic triazolo-pyridazinones were synthesized in good yields via the CuI-catalyzed azide-alkyne cycloaddition reactions of 4,6-diphenyl-2-(prop-2-yn-1-yl)pyridazin-3(2H)-one, possessing a terminal alkyne functional group with aromatic mono- and diazides with long alkyl and chiral glycol side-chain substituents. The chemical structures of the new compounds were characterized using different spectroscopic methods. The morphology of the dendrons was examined using the scanning electron microscope (SEM) analysis, which revealed the formation of highly ordered nanofiber and nanorod aggregations, directed by π-stacking interactions and van der Waals forces.Graphical abstract: [ABSTRACT FROM AUTHOR]

Gene therapy is a promising means to treat or prevent diseases either through gene silencing or expression. Some of the most effective delivery agents are polycationic dendrimers, which are highly branched constructs incorporating many positively charged groups. Two of the most effective dendrimers are polyethyleneimine (PEI) and poly(amidoamine) (PAMAM), which show high proficiency at overcoming barriers to oligonucleotide delivery. However, because of their abundance of cationic charge, they are associated with severe toxicity. We have therefore aimed to develop a low toxicity oligonucleotide delivery system, incorporating multiple components that have been selected and optimised to overcome the barriers to efficient oligonucleotide delivery. In this work we have focused on improving the toxicity, cellular uptake, and condensation of plasmid DNA (pDNA) through the fusion of synthetic poly- l-lysine (PLL) dendrons with the cell penetrating peptide TAT(48-60). A library of dendron structures, from 4 to 16 charge, and constructs containing six histidine residues, were synthesised. The effects of each modification on pDNA binding and condensation; cellular uptake and toxicity; and the size and zeta-potential of the complexes were assessed to identify the optimum dendron for incorporation into our systems. This work concluded that increasing the dendron charge from 4 to 16 significantly improved cellular uptake and pDNA condensation, with no effect on toxicity, while PLL dendrons with greater than 16 charge could not be efficiently produced. In comparison, the incorporation of six histidines into these constructs had a variable effect on cellular uptake, and generated larger sized complexes, but did not affect toxicity. [ABSTRACT FROM AUTHOR]

A number of dendrons of various chain lengths derived from the esters of 3,4,5-tris(tetradecyloxy)benzoic acid were synthesized. These esters were used as building blocks in the design of polyester molecules. Intermediate products, such as branched compounds with variation of functional groups in focal point (aromatic acids and their benzyl esters, aldehydes of different generation) were obtained. The structure and purity of all the compounds were determined by elemental analysis, FT-IR, NMR spectroscopy, mass spectrometry (MALDI-ToF). The phase behavior was investigated by differential scanning calorimetry and confirmed by polarized optical microscopy. Consequently, it was established that the liquid-crystalline properties of this series of dendrons arise from the degree of branching. This behavior can be explained by the formation of hydrogen bonds, as well as microsegregation processes of the links of the macromolecule. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Poly(aryl ether) dendrons ( 2) bearing long alkyl chains can undergo physical gelation in various organic solvents, especially alkanes and alcoholic solvents. In contrast, 3,4,5-trialkoxyphenyl derivatives ( 1), which are the building blocks of the dendrons ( 2), do not exhibit any gelation properties; thus, revealing the key role of the dendron structure in the aggregation/gelation process. Hansen solubility parameters allow us to gain a detailed understanding of the role of solvent in gelation. Critical gel concentrations, FT-IR spectroscopy, NMR spectroscopy, T measurements, and scanning electron microscopy are used to characterize the gel structures. [ABSTRACT FROM AUTHOR]

We have investigated the effects of localized surface plasmons (LSPs) on the performance of quasi-solid-state dye-sensitized solar cells (DSSCs). Ag and Au nanoparticles (NPs) were prepared by photoreduction in the presence of generation 5 polyester hydroxyl acetylene bis(hydroxymethyl)propanoic acid dendrons (Dendron) as a stabilizer. The plasmon-enhanced DSSCs were achieved by incorporating metal@Dendron NPs into TiO photoanodes. The presence of dendrons prevents the photoelectrons from recombining on the surface of TiO semiconductor and improves the stability of metal NPs. With the addition of Ag@Dendron NPs, the photocurrent and the power conversion efficiency of quasi-solid-state DSSCs increased due to the LSP effect of metal NPs and the barrier effect of dendron, which were confirmed by the increased incident photon-to-photocurrent efficiency and by electrochemical impedance spectroscopy analysis. [ABSTRACT FROM AUTHOR]

We developed a polyamidoamine (PAMAM) conjugated disulfide-linked chitosan (dsCS-PAM) for nonviral gene delivery. At weight ratio of 128, dsCS and dsCS-PAM showed positive zeta potential of around 9.5 mV and 14.5 mV, respectively, demonstrating their ability to form complexes with plasmid DNA (pDNA) for cell transfection. CS-PAM and dsCS-PAM formed complexes with pDNA in a reducing environment containing 5 mM DLdithiothreitol (DTT) at weight ratio 32 and 16, respectively. PAMAM conjugated chitosan derivatives, dsCS-PAM and CS-PAM, showed higher in vitro transfection efficiency than unconjugated derivatives dsCS and CS. Approximately 80% of A549 and 293 cells were viable in the presence of up to 100 μg/mL of dsCS-PAM. The results of this study demonstrate that dsCS-PAM has the potential to be a safe gene delivery carrier. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Two poly(benzyl ether) dendrons, decorated in their periphery with nitrile groups, were divergently synthesized and fully characterized. Their gelation properties were studied by using scanning electron microscopy (SEM), X-ray crystal structure analysis and concentration- and temperature-dependent H NMR spectroscopy. It was found that the gelation capability of these dendrons was highly dependent on dendron generation, and the second-generation dendron G-CN proved to be highly efficient organogelator despite the lacking of any conventional gelation motifs, such as amides, long alkyl side chains and steroidal groups. The multiple strong π-π stacking interactions and hydrogen bonding interactions due to the peripheral isophthalonitrile motifs were proved to be the main driving forces to form the self-assembled gel. [ABSTRACT FROM AUTHOR]

Insulated molecular wires of poly(phenylenevinylene) (PPV) were prepared by wrapping the conjugated backbones with dendrons through a noncovatent approach. It was found that electrostatic interaction between the quaternary ammonium groups of PPV-1 and the carboxylate moieties in dendrons induced the packing of dendrons along PPV-1 conjugated backbones. Absorption and emission spectroscopic examinations in solution and solid film indicated that the PPV-1 backbones adopted a more planar and isolated conformation in the complexes. Furthermore, interchain interactions in the complexes could be greatly reduced, improving the quantum yield of PPV-1. [ABSTRACT FROM AUTHOR]

This article presents abstracts of the comprehensive papers submitted to the "Japanese Journal of Polymer Science and Technology." Some of the abstracts are as follows: "Novel Precision Cyclopolymerization of Dienes by Late Transition Metal Catalysts," by Daisuke Takeuchi and others; "Polymerization of Lactones and Lactides Initiated by Cyclodextrins," by Motofumi Osaki; "Precise Cross-Coupling Control During Oxidative Coupling Polymerization," by Shigeki Habaue; "Precise Synthesis of Functional Polymers by RAFT Polymerization," by Hideharu Mori and others.

Silver nanoparticles protected by first to third generation poly(amido amine) dendrons with an anthracenyl-focal point were fabricated by photo-promotion of silver ions in aqueous dendron solutions. The reaction solutions colored from light to deep brown and displayed a broad plasmon band at 450nm, indicating the formation of silver nanoparticles. The formation of particles progressed with time, although it slowed down at the light-shielding (dark) condition. The light-promoted electron transfer from amine groups of dendron to silver ions through anthracenyl moiety might concern to the formation of silver nanoparticles. According to the images of transmission electron microscopy, the shape of nanoparticles was not only spherical (15-20 nm in size) but also polygonal (20-35 nm in size). It was confirmed from the crystallographic analysis of electron diffraction patterns that the polygon was a hexagonal-close-packing (hcp) single crystal, whereas the crystal structure of spherical nanoparticles was face-centered-cubic (fcc). The reaction was fastest when the second generation dendron was used, indicating the competition of increasing number of amine groups and reducing efficiency of photo-promoted electron transfer with generation. [ABSTRACT FROM AUTHOR]

A novel fabrication of the patterned surfaces in the polymer films was demonstrated by using the selforganizing character of the block copolymers of polystyrene- b-oligothiophenes and polystyrene- b-aromatic amide dendron. Hexagonally arranged open pores with a micrometer-size were spontaneously formed by casting the polymer solutions under a moist air flow. The amphiphilic character of the block copolymers played the crucial role as a surfactant to stabilize the inverse emulsion of water in the organic solvent, and subsequently the aggregated structure of the hydrophilic oligothiophene or aromatic amide dendron segments remained on the interiors of the micropores. The chemical composition on the top of the surface of the microporous films was characterized by energy-filtering transmission electron microscopy (EFTEM) or a time-of-flight secondary ion mass spectrometer (ToF-SIMS). The characterizations clearly indicated that the patterned surfaces in the self-organized block copolymer films with the hexagonally ordered microporous structures were fabricated in a single step. [ABSTRACT FROM AUTHOR]

Poly(phenylene sulfide) dendrimers up to fourth generation were synthesized by divergent method from 1,3,5-tris(4-chloro-phenylene-l-thio)benzene. All the dendrimers are soluble in polar organic solvents at room temperature. The chemical structures at the synthesis steps were confirmed by spectroscopic method. X-Ray diffraction study revealed that all dendrimers are semi-crystalline in nature. Carboxy focal poly(phenylene sulfide) dendrons were synthesized up to second generation by divergent method from 3,5-dichlorobenzoicacid. On surface pressure-area isotherm at air-water interface, third generation poly(phenylene sulfide) dendrimer displayed hysteresis. Its occupied surface area was smaller than the calculated values as well as a case of second generation poly(phenylene sulfide) dendron. Atomic force microscopic images of their LB films presented accumulation and aggregation of molecular layers. On the other hand, adsorption films of dendrimer and dendron were fundamentally monolayer. Molecular arrangements in the LB and adsorption films and the driving forces of the film formation were discussed. [ABSTRACT FROM AUTHOR]

Asynthetic scheme for a transport platform for the creation of new diagnostic and therapeutic antitumor drugs that was based on a dendrimer with a core of pentaerythritol tetraglycidyl ether (TGEPE) and dendra with diallylamine was developed. The transport platform was promising for designing targeted antitumor agents for magnetic resonance tomography and nuclear medicine. [ABSTRACT FROM AUTHOR]