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[en] Metal assembly to a dendrimer can provide various functionalities based on the branched structure. Here, we researched assembly phenomena of bismuth salts in the phenylazomethine dendrimer and achieved enhancement of emission intensity per metal unit by using Bi(OTf)3. This enhancement suggested increasing of Bi–N coordination bonds derived from the bismuth units in the dendrimer.
[en] Phosphorus-containing dendrimers are defined as dendrimers having at least one phosphorus atom at each branching point. In this review, we will show how phosphorhydrazone dendrimers can be modified at will at the level of the core and of the branches, to afford specific properties, such as fluorescence to image biological events. Accelerated methods of synthesis of phosphorus (one step for one generation) will be also displayed, as well as the specific reactivity of P=N–P=S linkages obtained in most of these accelerated method of synthesis, which has led to particularly original dendritic architectures, such as dendrons included in dendrimers. Finally, we will display how modifications of the internal structure of a series of dendrimers having the same type and number of terminal functions can deeply modify their biological anti-inflammatory properties. Among the six critical nanoscale design parameters (CNDP), we will show how two of them, i.e., architecture and elemental composition, have been particularly engineered to modify phosphorus-containing dendrimers, in order to fulfill the desired properties.
[en] Hydrophobicity is known to play a key role in the biological distribution of materials but is often an overlooked parameter when conjugating targeting agents, drugs, and dyes to dendrimers. This review examines the impact of hydrophobic variation in stochastically conjugated dendrimers as well as materials where synthetic methods or approaches to purification provide more controlled samples. Hydrophobic interactions are considered for three general classes: (1) terminal functional group modifications, (2) bioactive small molecules chosen to interact with receptors and proteins as targeting agents and/or drugs, and (3) imaging agents to track biological activity. Impacts on membrane interaction and cellular uptake, biodistribution, interaction with transport proteins, and pharmacokinetics are discussed. The size range of the dendrimers discussed is ~ 1–10 nm.
[en] Main approaches to the design of organic bulk heterojunction photovoltaic structures are generalized and systematized. Novel photovoltaic materials based on fullerenes, organic dyes and related compounds, graphene, conjugated polymers and dendrimers are considered. The emphasis is placed on correlations between the chemical structure and properties of materials. The effect of morphology of the photoactive layer on the photovoltaic properties of devices is analyzed. Main methods of optimization of the photovoltaic properties are outlined. The bibliography includes 338 references
[en] A new magnetic adsorbent PAMAMG_3-Fe_3O_4/P(GMA-AA-MMA) was prepared by growing third generation poly(amido) amine (PAMAMG_3) on the surface of superparamagnetic polymer microspheres Fe_3O_4/P(GMA-AA-MMA). The maximum sorption capacity of U(VI) (395.2 mg g"-"1) on the sorbent was much higher than those of U(VI) on many other reported materials. The sorption of U(VI) on the magnetic adsorbent obeyed the Langmuir mode. The selectivity of the sorbent could reach up to 91.8 % at pH 4.5. Furthermore, PAMAMG_3-Fe_3O_4/P(GMA-AA-MMA) could also be reused at least five times without any noticeable loss of its sorption capacity. (author)
[en] Highlights: • Multifunctional (adamantane – β-cyclodextrin – dendrimer) iron oxide - based delivery system was produced. • Antiviral adamantane derivative (ADMA) was covalently attached to the iron oxide nanoparticles. • Adamantane formed inclusion complex with β-cyclodextrin bearing ionically bounded dendrimer. • Dendrimer was a carrier for two model drugs – ibuprofen (IBU) and methotrexate (MTX). • The release of the drugs encapsulated at different parts of the system studied was dependant on pH conditions.
[en] General, fast, and efficient methods for the synthesis of Frechet-type dendrimers having core diversities were elaborated. Two core building blocks, 4,4'-(3,5-bis(propargyloxy)benzyloxy)bisphenyl and N,N,N',N'-tetra(prop-2- ynyloxycarbonylethyl)-1,2-diaminoethane, were designed to serve as the alkyne functionalities for dendrimer growth via click reactions with the azide-dendrons. The synthetic strategy involved an 1,3-dipolar cycloaddition reaction between an alkyne and an azide- functionalized Frechet-type dendrons in the presence of Cu(I) species which is known as the best example of click chemistry
[en] Creation of diverse ordered nanostructures via self-assembly of macromolecules is a promising “bottom-up” approach towards next-generation nanofabrication technologies. It is therefore of critical importance to explore the possibilities to form new self-assembled phases in soft matter systems. In this review, we summarized recent advances on the identification of several unconventional spherical phases in the self-assembly of functional macromolecules, including Frank-Kasper (F-K) phases and quasicrystals originally observed in metal alloys. We believe that these results provide a new strategy towards the rational design of novel functional materials with hierarchically ordered structures.
[en] Dendrimers are a promising class of polymeric nanoparticles for delivery of therapeutics and diagnostics. Polyamidoamine (PAMAM) dendrimers have shown significant efficacy in many animal models, with performance dependent on surface functionalities. Understanding the effects of end groups on biological interactions is critical for rational design of dendrimer-mediated therapies. In this study, we quantify the cellular trafficking kinetics (endocytosis and exocytosis) of generation 4 neutral (D4-OH), cationic (D4-NH2), anionic (D3.5-COOH), and generation 6 neutral (D6-OH) PAMAM dendrimers to investigate the nanoscale effects of surface functionality and size on cellular interactions. Resting and LPS-activated microglia were studied due to their central roles in dendrimer therapies for central nervous system disorders. D4-OH exhibits greater cellular uptake and lower retention than the larger D6-OH. D4-OH and D3.5-COOH exhibit similar trafficking kinetics, while D4-NH2 exhibits significant membrane interactions, resulting in faster cell association but lower internalization. Cationic charge may also enhance vesicular escape for greater cellular retention and preferential partitioning to nuclei. LPS activation further improves uptake of dendrimers, with smaller and cationic dendrimers experiencing the greatest increases in uptake compared to resting microglia. These studies have implications for the dependence of trafficking pathway on dendrimer properties and inform the design of dendrimer constructs tailored to specific therapeutic needs. Cationic dendrimers are ideal for delivering genetic materials to nuclei, but toxicity may be a limiting factor. Smaller, neutral dendrimers are best suited for delivering high levels of therapeutics in acute neuroinflammation, while larger or cationic dendrimers provide robust retention for sustained release of therapeutics in longer-term diseases.
[en] Nanoparticles (NPs) have been widely used in biomedical research, but the difficulty in determining their in vivo characteristics limits their clinical translation. So far, positron emission tomography (PET), which requires that the NPs are labeled with an appropriate positron nuclide, appears to be the most likely solution to this problem. 64Cu is the most frequently used positron emitter in NP research and 64Cu radiolabeling using chelators is the most commonly used strategy, although this method has some shortcomings in practice. In the present study, we directly integrated 64Cu into the internal cavities of generation 5 polyamidoamine (G5 PAMAM), a commercially available NP, without the need for chelators. The labeling time, pH level, temperature, and amount of precursor were systematically varied to determine the optimum labeling conditions. Preliminary biological evaluation in mice revealed that the 64Cu direct labeling method was feasible for the preparation of labeled PAMAM for in vivo studies. This study introduced a novel idea for 64Cu labeling of dendrimers (and other NPs with a similar structure) and should facilitate the application of NPs in biomedical studies.