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International audience; The possibility to incorporate diverse chemical species inside clays, especially swelling clay minerals, has been known for more than two millennia, but the first examples of man-made polymers interacting with clays only date back to about 30 years ago. Dendrimers and hyper-branched polymers differ from classical polymers by their intrinsically 3-dimensional structure, and by their large number of reactive functional groups. The study of their interaction with clays/clay minerals is relatively recent. Besides the fundamental research done on these kinds of organoclays, different potential uses have already been investigated. In this review, we will present an overview of the studies dealing with the synthetic processes, and the characterization of the resulting dendrimer/hyper-branched polymer–clay mineral (nano)composites. Special attention will be focussed on the properties of these new hybrid smart materials, in different fields ranging from catalysis, trapping gases (in particular CO2 and H2), energy conversion and storage, flame retardants, and biology (biosensors, hydrogels, and drug delivery) to water treatment (wastewater and water-based drilling fluids).

International audience; The versatile functionalization of thiazoles and benzothiazoles at different locations in their backbone offers the possibility to design many substituted heterocyclic derivatives bearing active groups for applications in coordination chemistry, catalysis, and medicinal chemistry. The grafting of various phosphorus groups (phosphines, phosphine oxides, phosphonates, phosphinic acids, etc.) via different strategies leads to many phosphorus thiazoles and benzothiazoles acting per se as catalysts for a number of reactions for complexation with metals such as Ir, Au, Pt, Pd, and Cu, for which the catalytic properties were investigated.

International audience; For the first time, an overview of dendrimers in combination with natural products and analogues as anti-cancer agents is presented. This reflects the development of drug delivery systems, such as dendrimers, to tackle cancers. The most significant advantages of using dendrimers in nanomedicine are their high biocompatibility, good water solubility, and their entry - with or without encapsulated, complexed or conjugated drugs - through an endocytosis process. This strategy has accelerated over the years in order to develop nanosystems as nanocarriers, to decrease the intrinsic toxicity of anti-cancer agents, to decrease the drug side effects, to increase the efficacy of the treatment, and consequently to improve patient compliance.

International audience; Dendrimers are hyperbranched polymers having a perfectly defined structure because they are synthesized step-by-step in an iterative fashion, and not by polymerization reactions. Some dendrimers are considered as inorganic, as they possess inorganic atoms at each branching point. Among numerous examples, two families of inorganic dendrimers have emerged as particularly promising: silicon-containing dendrimers, particularly carbosilanes, and phosphorus-containing dendrimers, particularly phosphorhydrazones. This tutorial review will display the main properties of both families of dendrimers in the fields of catalysis, materials and biology/nanomedicine. Emphasis will be put on the most recent and promising examples.

Open Access Article. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence., Two different novel families of bifunctional water-soluble dendrimers are synthesized, using the specific functionalization of one function of the cyclotriphosphazene core. Dendrimers are grown from the 5 remaining functions, up to generation 2. Water-solubility is attained in the last step of the synthesis by grafting either ammonium terminal groups or carboxylate terminal groups, on generations 1 and 2 of these bifunctional dendrimers. 12 new compounds are synthesized and fully characterized, in particular by multi-nuclear NMR. The function linked to the core is thioctic acid, suitable for grafting onto gold, thus both types of water-soluble dendrimers can be used to coat gold surfaces. These macromolecular assemblies are characterized by surface plasmon resonance (SPR). In a preliminary attempt, the gold surfaces modified by either positively or negatively charged dendrimers are used for studying their interaction with cells. Exposed to human osteoblast cells (OBC), the influence of the surface coatings on the cell responses is investigated. Polycationic dendrimers provoke cell apoptosis, whereas negatively charged dendrimers support cell adhesion and proliferation.

International audience; Dendrimers are nano-materials with perfectly defined structure and size, and multivalency properties that confer substantial advantages for biomedical applications. Previous work has shown that phosphorus-based polyphosphorhydrazone (PPH) dendrimers capped with azabisphosphonate (ABP) end groups have immuno-modulatory and anti-inflammatory properties leading to efficient therapeutic control of inflammatory diseases in animal models. These properties are mainly prompted through activation of monocytes. Here, we disclose new insights into the molecular mechanisms underlying the anti-inflammatory activation of human monocytes by ABP-capped PPH dendrimers. Following an interdisciplinary approach, we have characterized the physicochemical and biological behavior of the lead ABP dendrimer with model and cell membranes, and compared this experimental set of data to predictive computational modelling studies. The behavior of the ABP dendrimer was compared to the one of an isosteric analog dendrimer capped with twelve azabiscarboxylate (ABC) end groups instead of twelve ABP end groups. The ABC dendrimer displayed no biological activity on human monocytes, therefore it was considered as a negative control. In detail, we show that the ABP dendrimer can bind both non-specifically and specifically to the membrane of human monocytes. The specific binding leads to the internalization of the ABP dendrimer by human monocytes. On the contrary, the ABC dendrimer only interacts non-specifically with human monocytes and is not internalized. These data indicate that the bioactive ABP dendrimer is recognized by specific receptor(s) at the surface of human monocytes.

International audience; Due to their nanometric size, dendrimers have been considered as potentially suitable as new vehicles for drug delivery since their infancy. The association of a dendrimer and a drug may occur in different ways, either through covalent or non-covalent interactions. A non-covalent interaction can be the simple encapsulation inside dendrimers that enhances the solubility of lipophilic drugs in water, or electrostatic interactions between the surface and charged drugs (or DNA, RNA, or siRNA). The covalent association may occur through stable bonds, in particular for dendrimers that are considered as active per se, or through cleavable bonds that should be cleaved only when reaching the target (often cancerous cells). In addition, the full structure of the dendrimer can be disassembled under the influence of a trigger such as pH variations. This review will present these strategies and their consequences for drug delivery.

Four series of phosphorus dendrimers (generations 1 and 4) having various types of amine terminal groups (pyrrolidine, morpholine, methyl piperazine, or phenyl piperazine) are synthesized. After protonation, the fourth generations of three of them are found water-soluble, and used for several biological experiments. First, the cytotoxicity of these polycationic dendrimers towards three cell strains (one healthy: HUVEC, and two cancerous: HEK 293 and HeLa) is assayed and found low. Second, their ability to interact with DNA is tested by electrophoresis: the dendrimer terminated by pyrrolidinium groups is found efficient to form dendriplexes. Finally, the polycationic dendrimers are used as transfection agents to deliver single- and double-stranded DNA into the three above-mentioned cell strains. Here also the dendrimer having pyrrolidinium groups is found the most efficient.

Dendrimers are hyperbranched nanosized and precisely defined molecules, attracting increasing attention each year due to their numerous properties in catalysis, materials science, and biology. This tutorial review concerns the use of dendrimers as catalysts and focuses more precisely on their properties as enantioselective catalysts. Emphasis is put on chiral phosphine complexes constituting the core or the end groups of various types of dendrimers. The effect of the location of the catalytic entities, the effect of the size (generation) and the nature of the dendritic skeleton on the enantiomeric excesses are discussed.

Besides properties commonly found for all types of dendrimers, phosphorus-containing dendrimers possess some specific properties seldom or never found for other types of dendrimers. Emphasis will be put on these specificities.

The use of divergent strategies is a fruitful approach for the synthesis of phosphorus-containing dendrons (dendritic wedges). Different synthetic processes have been devised, depending on the type of function located at the core (alkenyl groups, pyridine derivatives, chloromethyl or azidomethyl groups). In all cases, the divergent strategy easily allows one to have very reactive functional groups such as P–Cl, amine, phosphine or aldehyde groups on the surface of the dendron.

Phosphorus dendrimers containing terminal phosphoramidite ligands have been found to be highly effective and recoverable catalysts for the rhodium(i) catalyzed [2+2+2] cycloaddition reactions. A strong positive dendritic effect is observed both in the activity and enantiodiscrimination leading to axially chiral biaryl compounds We would like to thank the Spanish MICINN (project CTQ2011-23121), the Generalitat de Catalunya (project 2009SGR637) and the CNRS (France) for their financial support. L. G. thanks the Universitat de Girona (UdG) for a predoctoral fellowship

We report the synthesis and the supramolecular auto-assembly of catanionic phosphorus-containing dendrimers mimicking multisite analogs of galactosylceramide.

Controlled titanium alkoxide mineralization in the presence of phosphonated, dendrimeric nano-building blocks provides a new family of hierarchically porous dendrimer-bridged titanium dioxide materials.

The synthesis of a new series of phosphorus-containing dendrimers bearing as terminal groups triazatriolefinic macrocycles is reported, from generation 1 (6 macrocycles) to generation 4 (48 macrocycles). These macrocycles are linked to the dendrimers through diazaphospholane moieties (5-membered rings). The complexation ability of these dendrimers and of a compound possessing a single macrocycle was tested towards Pt2(dba)3. A discrete complex could be isolated only in the case of the model compound, whereas the dendrimers afford highly branched networks of Pt(0) nanoparticles interweaved with the dendrimers.

Using single strand DNA (ssDNA) target as a “vehicle” and Cy5 dye molecule as “cargo”, the selective encapsulation of Cy5 by DNA hybridization in dendrimer/polymer multilayer microcapsules is reported. This approach can be applied for many low molecular weight molecules, which are usually difficult encapsulate because of their diffusion.

A novel approach for selectively encapsulating Cy5 dye molecules via DNA hybridization in cationic phosphorus dendrimers (G(4)(+))/polystyrenesulfonate (PSS) microcapsules has been developed. The hybridization between Cy5 labeled single strand DNA (ssDNA) targets and complementary ssDNA probes was performed in the microcapsules. During hybridization, the ssDNA targets acted as 'vehicles' and Cy5 dye molecules as 'cargos', which led to the selective encapsulation of the Cy5 molecules inside the capsules. The approach may be applied for many small molecules, which are usually difficult to be encapsulated due to their diffusion properties in microcapsules.

This review will display the special role played by phosphorus-containing dendrimers when interacting with biological systems. After some synthetic aspects, the usefulness of these dendrimers for elaboration of highly sensitive bio-sensors and for in vitro drug delivery (for instance as transfection agents, or against HIV-1 and the scrapie form of prions) will be demonstrated. Then, emphasis will be put on the favourable influence of these dendrimers on cells growth, in particular for neuronal cells, and for human immune blood cells such as monocytes and Natural Killer cells, the latter playing a key-role for fighting against viral infections and cancers. This review will finally describe in vivo biological properties of these phosphorus dendrimers as anti-prion agents, for ocular drug delivery, and for imaging rat brain blood vessels. Some of these properties can be found also with other types of dendrimers, but others, in particular the interaction with the human immune blood cells, occur only and specifically with phosphorus dendrimers.

Electroactive conjugated polymers have been synthesized by electropolymerisation of increasing generations of dendrimers derivatized by peripheral bithiophene groups.

Multilayer thin films of anionic gold nanoparticles (AuNPs) and cationic phosphorus dendrimers were deposited on 3-(diethoxymethyl-silyl)propylamine (3-APDMES)-coated substrates using layer-by-layer (LbL) assembly driven by electrostatic interactions. The growth of Au/dendrimer multilayers composed of AuNPs with diameters of ∼3 nm and ∼16 nm and dendrimer with ∼2 nm diameter was monitored by UV-vis spectroscopy. The relative amounts of AuNPs and dendrimers in the multilayer films were calculated using a quartz crystal microbalance. The Au-containing multilayers have two surface plasmon bands at ∼530 nm and ∼600 nm, where the latter exhibits a red shift upon increasing the areal density of AuNPs as well as increasing the layer number. The localized surface plasmon resonance (LSPR) band of the hybrid films can be tuned by adding NaCl to the dendrimer solution or by removing the organic matrix. These results demonstrate that the near-field coupling between the LSPR bands of neighboring Au layers is responsible for the controlled absorption behavior. Au mesoporous films after removing dendrimers show LSPR sensing properties for alcohols with different refractive indices in the range 1.33–1.41. A linear relationship was obtained between the LSPR peak wavelength and the refractive index of the surrounding medium.

Heparin is involved in the pathogenesis of prion diseases, affecting the process of fibril formation. It has been shown that whether it accelerates or inhibits fibrilogenesis depends on its concentration: prion peptide PrP 185-208 aggregates in the presence of 0.04 mg ml−1 heparin, but concentrations ten times lower or higher cause no aggregation. Polyamidoamine, polypropyleneimine and phosphorus dendrimers that previously exhibited anti-prion activity have been shown to interact with heparin. The interactions between cationic dendrimers and anionic heparin are mainly electrostatic. The present study shows that these interactions are indirectly responsible for the inhibition or enhancement of fibril formation by dendrimers.

What is the contribution of dendrimers to the field of nanomedicine? Rather than disclosing an exhaustive catalogue of their possible applications, this review article sets a putative answer by showing the basics and the underlying concepts that make dendrimeric systems so attractive to nanomedicine, emphasizing on the extraordinary possibilities offered by their multivalent and defined structure.

Organic nanodots based on the gathering of an exponentially increasing number of two-photon fluorophores on a dendritic platform of controlled size and symmetry represent a promising nontoxic alternative to quantum dots for (bio)imaging purposes. This modular route offers a number of advantages in terms of versatility but also raise a number of questions to be addressed. In particular, possible interactions between fluorophores, due to confinement effects, have to be taken into account. With this aim in mind we have investigated and compared the photophysical and two-photon absorption (TPA) properties of two series of organic nanodots of different geometries: spherical-like organic nanodots derived from a dendritic scaffold built from a cyclotriphosphazene core and dumbbell-like organic nanodots derived from a dendritic scaffold built from an elongated rod-like chromophore. The study provides evidence that the different topology and nature of the dendritic architecture lead to significant changes in photoluminescence characteristics as well as to subtle variations of the TPA efficiency. As a result, the dumbbell-like nanodots although less promising in terms of two-photon induced fluorescence (due to partial quenching of fluorescence efficiency) also demonstrate that improvement of the TPA efficiency can be achieved by playing on the nature and topology of the dendritic scaffold of the nanodots.

Polycationic or neutral dendrons of generation 1 to 3 bearing protonated (or not) amino end groups and a vinyl group at the focal point as well as polyanionic or neutral dendrons of generation 1 to 3 decorated with carboxylate or carboxylic groups on their surface and exhibiting a vinyl group at the core were prepared. Addition of ethylenediamine to the vinyl core of dendrons having amino end groups allowed the synthesis of uniquely tailored water-soluble phosphorus bis-dendrons via core to core assembling of dendrons having a vinyl core. In preliminary experiments layer-by-layer deposition of bis-dendrons on silica surface was demonstrated.

Organic–inorganic materials in which the organic part is constituted of dendrimers possessing one phosphorus atom at each branching point are reviewed. These dendrimers are either inside the materials and contribute to their elaboration, or they are linked to the surface of inorganic materials by covalent or electrostatic interactions. In the first case, the dendrimers have been used to organize and “glue” the inorganic elements or to generate nanoporosities after removal of the dendrimers used as templates. The non-covalent approach for controlled modifications of inorganic surfaces allows the synthesis of nanotubes made of 20 bilayers of oppositely charged dendrimers deposited on porous alumina templates. The covalent approach allowed the elaboration of stable, reusable, and highly sensitive DNA chips as well as piezoelectric membranes usable as biosensors.

Addition of bis(η-cyclopentadienyi)zirconium hydride (Cp2ZrHCl) to phospha-alkenes and phosphaimines leads either to a functionalized bis(η-cyclopentadienyl)zirconium phosphirane and azaphosphirane or to a protonated dico-ordinated phosphorus species.

Phosphorus cryptands 3–5 are obtained via[2 + 3] cyclocondensations between phosphodiydrazides 1a, b and phosphorus-p,p-dialdehydes 2a, b while another phosphorus cryptand 10 is prepared by treatment of the sodium salt of a phosphodihydrazone 8 with a dihalogenated phosphorus-containing macrocycle 9.

Low temperature laser irradiation of trans-diphosphene (1), followed using u.v., and 31P and 1H n.m.r. spectroscopy, gives an equilibrium between (1) and the unstable cis-isomer (2): the activation free energy of the (2)→(1) reaction is 20.3 kcal mol–1(1 kcal = 4.18 kJ).

The unexpected synthesis of new free or complexed P-functionalized diphosphiranes is reported.

Ozonolysis of the diphosphene (1) occurs with a 2 : 1 stoicheiometry (ozone : diphosphene);the reaction carried out at low temperature, gives a relatively stable cyclic diperoxide(2).