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The application of nanotechnology in biological and medical fields have resulted in the creation of new devices, supramolecular systems, structures, complexes, and composites. Dendrimers are relatively new nanotechnological polymers with unique features; they are globular in shape, with a topological structure formed by monomeric subunit branches diverging to the sides from the central nucleus. This review analyzes the main features of dendrimers and their applications in biology and medicine regarding cancer treatment. Dendrimers have applications that include drug and gene carriers, antioxidant agents, imaging agents, and adjuvants, but importantly, dendrimers can create complex nanosized constructions that combine features such as drug/gene carriers and imaging agents. Dendrimer‐based nanosystems include different metals that enhance oxidative stress, polyethylene glycol to provide biosafety, an imaging agent (a fluorescent, radioactive, magnetic resonance imaging probe), a drug or/and nucleic acid that provides a single or dual action on cells or tissues. One of major benefit of dendrimers is their easy release from the body (in contrast to metal nanoparticles, fullerenes, and carbon nanotubes), allowing the creation of biosafe constructions. Some dendrimers are already clinically approved and are being used as drugs, but many nanocomplexes are currently being studied for clinical practice. In summary, dendrimers are very useful tool in the creation of complex nanoconstructions for personalized nanomedicine. This article is categorized under:Diagnostic Tools > Diagnostic NanodevicesDiagnostic Tools > In Vivo Nanodiagnostics and ImagingTherapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease [ABSTRACT FROM AUTHOR]

Two families of phosphorhydrazone dendrons having either an azide or an alkyne linked to the core and diverse types of pyridine derivatives as terminal functions have been synthesized and characterized. These dendrons were grafted via click reaction to graphene oxide (GO) functionalized with either alkyne or azide functions, respectively. The resulting modified‐GO and GO‐dendrons materials have been characterized by Fourier Transform Infrared (FTIR), Raman spectroscopy (RS), and Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) analyses. In addition, the free dendrons and the dendrons grafted to GO were tested toward cancerous (HCT116) and non‐cancerous (RPE1) cell lines. [ABSTRACT FROM AUTHOR]

First‐in‐class CuII and AuIII metaled phosphorus dendrons were synthesized and showed significant antiproliferative activity against several aggressive breast cancer cell lines. The data suggest that the cytotoxicity increases with reducing length of the alkyl chains, whereas the replacement of CuII with AuIII considerably increases the antiproliferative activity of metaled phosphorus dendrons. Very interestingly, we found that the cell death pathway is related to the nature of the metal complexed by the plain dendrons. CuII metaled dendrons showed a potent caspase‐independent cell death pathway, whereas AuIII metaled dendrons displayed a caspase‐dependent apoptotic pathway. The complexation of plain dendrons with AuIII increased the cellular lethality versus dendrons with CuII and promoted the translocation of Bax into the mitochondria and the release of Cytochrome C (Cyto C). [ABSTRACT FROM AUTHOR]

Irresponsiveness of triple negative breast cancer (TNBC) toward conventional therapies has drawn attention toward siRNA therapeutics. In gene delivery, dendrimers are gaining significant attention due to their characteristic features and polo‐like kinase (PLK1) is reported as a potential target for TNBC. In this work, phosphorus and polyamidoamine dendrimer (generation 3 and 4 of each type) are explored to address delivery challenges of PLK1 siRNA (siPLK1). Dendriplexes were formed and complexation was found at 3:1 N/P ratio for all dendrimers by gel electrophoresis. Complexation was also supported by zeta potential, circular dichroism and intercalation assay. Dendriplexes were found to be stable in presence of ribonuclease and serum. Dendriplexes resulted in enhanced cell uptake of siPLK1 compared to siPLK1 solution in MDA‐MB‐231 and MCF‐7 cells. Dendriplexes caused increased cell arrest in sub‐G1 phase compared to solution. These observations suggested phosphorus and polyamidoamine dendrimers as potential carriers for siPLK1 delivery to treat TNBC. [ABSTRACT FROM AUTHOR]

Fluorescent derivatives of phosphorhydrazone dendrimers are reviewed. Diverse types of fluorophores have been used, such as pyrene, naphthol, anthracene, dansyl, diketone, phthalocyanine, maleimide, julolidine, rhodamine, fluorescein, or fluorene derivatives. The fluorescent groups can be located either as terminal groups on the surface, at the core, linked to the core (off‐center), or to the branches of the dendritic structure. After fundamental research on their synthesis, these compounds have been used in the fields of catalysis, nanomaterials, OLEDs, sensors and biology/nanomedicine, in particular for monitoring transfection, or for their anti‐inflammatory or anti‐cancer properties. [ABSTRACT FROM AUTHOR]

The role of phosphorhydrazide derivatives, in particular of type RP(X)(NMeNH2)2 for the synthesis of macrocycles and of type Cl2P(X)NMeNH2 (X = O, S in both cases) for the synthesis of dendrimers, will be shown in this review. In both cases, condensation reactions with different types of aldehydes (often aromatic) afford phosphorhydrazone derivatives, which are the building blocks for these special architectures. After the synthetic aspects, selected properties related to catalysis, nanomaterials, and biology/nanomedicine will be displayed. The condensation reactions of phosphorhydrazide linkages with aldehydes have been successfully used for the synthesis of special macromolecular architectures such as macrocycles and dendrimers. [ABSTRACT FROM AUTHOR]

The synthesis and the photophysical properties of a new class of fully organic monodisperse nanoparticles for combined two‐photon imaging and photodynamic therapy are described. The design of such nanoparticles is based on the covalent immobilization of a dedicated quadrupolar dye that combines excellent two‐photon absorbing (2PA) properties, fluorescence and singlet oxygen generation ability, in a phosphorous‐based dendrimeric architecture. First, a bifunctional quadrupolar dye bearing two different grafting moieties, a phenol function and an aldehyde function, was synthesized. It was then covalently grafted through its phenol function to a phosphorus‐based dendrimer scaffold of generation 1. The remaining aldehyde functions were then used to continue the dendrimer synthesis up to generation 2, introducing finally 24 water‐solubilizing triethyleneglycol chains at its periphery. A dendrimer confining 12 photoactive quadrupolar units in its inner scaffold and showing water solubility was thus obtained. Interestingly, the G1 and G2 dendrimers retain some fluorescence as well as significant singlet oxygen production efficiencies while they were found to show very high 2PA cross‐sections in a broad range of the NIR biological spectral window. Hydrophilic dendrimer G2 was tested in vitro on breast cancer cells, first in one‐ and two‐photon microscopy, which allowed for visualization of their cell internalization, then in two‐photon photodynamic therapy. While being nontoxic in the dark and, more importantly, under exposure to daylight, dendrimer G2 proved to be a very efficient cell‐death inducer only under two‐photon irradiation in the NIR. (Cell) death by day or night: New dendrimers combining high two‐photon brightness and photosensitizing properties are efficient cell‐death inducers under two‐photon irradiation in the NIR, while being non‐toxic in the dark and under exposure to daylight. [ABSTRACT FROM AUTHOR]

A versatile reactivity from the cage compound P(NMeNMe)3P is presented. The Staudinger reaction with Me3SiN3 is carried out. The crystal structure of the compound issued from the reaction on both sides (Me3SiN=P(NMeNMe)3P=NSiMe3) is reported. When the reaction occurs on only one side, the remaining free phosphorus atom is complexed with RuCl2(p-cymene). P(NMeNMe)3P reacts with PCl3, leading to the heterocyclic compound ClP(NMeNMe)2PCl. This heterocycle also displays a versatile reactivity. Substitution reaction with HNiPr2 leads to iPr2NP(NMeNMe)2PNiPr2. Very complex ¹H and 13C NMR spectra suggest that the cis isomer is the largely major isomer of this compound. The cis structure is confirmed by X-ray diffraction. Besides the reaction on the P-Cl functions, the reaction on the lone pair of ClP(NMeNMe)2PCl is carried out, leading to the complex (p-cymene) Cl2RuPCl(NMeNMe)2ClPRuCl2(p-cymene). Characterization of this compound by X-ray diffraction displays a cis isomer for this compound also. [ABSTRACT FROM AUTHOR]

A new concept is presented, namely the synthesis of dendrimers intrinsically composed in alternation of building blocks pertaining to two known families of dendrimers: phosphorhydrazone dendrimers and triazine-piperazine dendrimers. These mixed dendrimers with layered controlled architecture inherit their easy 31P NMR characterization and their thermal stability from the phosphorhydrazone family, and their decreased solubility from the triazine-piperazine family. However, they have also their own and original characteristics. Both parent families are white powders, whereas the mixed dendrimers are yellow, orange, or red powders, depending on the generation. DFT calculations were carried out on model dendrons to understand these special color features. Remarkably, these dendrimers incorporating redox-active organic entities allow for the first time the monitoring of the growth of an organic dendrimer by electrochemistry while highlighting an even-odd generation behavior. [ABSTRACT FROM AUTHOR]

Three types of poly(phosphorhydrazone) dendrimeric structures bearing function(s) suitable for grafting to silica and trapping CO2 have been grafted to different types of silica with various textural properties (e.g., different surface areas, porous or nonporous, pore sizes). These hybrid hard/soft and inorganic/organic nanomaterials have been characterized. Some representative examples of these hybrid materials were chosen for trapping CO2 and their performances have been analyzed. [ABSTRACT FROM AUTHOR]

Four new phosphorus dendrimeric phase-transfer catalysts are prepared that contain 12 (+)-cinchoninium salts on the surface obtained by the quaternisation of the quinuclidinic N atom. The asymmetric alkylation of a glycinate Schiff base with benzyl bromide is used as a benchmark reaction, and the dendrimeric catalyst that contains an allyl group on the O-9 hydroxy group of the cinchonine units is the most active. The recovery and reuse of the catalyst are possible for five consecutive runs without loss of activity and with only a slight decrease in enantioselectivity. If other electrophiles are used, substituted benzyl bromides give better results than other activated alkyl bromides to afford the corresponding R amino acid derivatives. A comparison of these results with those reported previously for similar cinchoninium salts shows that dendrimers could be a better support than other polymers for this type of organocatalysis. [ABSTRACT FROM AUTHOR]

First- and fourth-generation phosphorus dendrimers decorated on their surface with (+)-cinchonine moieties for the use as organocatalysts have been prepared. The first-generation dendrite showed the highest activity and enantioselectivity in the α-amination of several β-dicarbonyl compounds. A positive dendritic effect was observed. Its recovery and reuse over 10 cycles was demonstrated without loss of activity. Preliminary studies of the scope of the reaction have been performed. [ABSTRACT FROM AUTHOR]

The preparation of novel families of phosphorus-based macromolecular architectures called 'onion peel' phosphorus nanodendritic systems is reported. This construct is based on the versatility of methods of synthesis using several building blocks and on the capability of these systems to undergo regioselective reactions within the cascade structure. Sustainable metal-free routes such as the Staudinger reaction or Schiff-base condensation, involving only water and nitrogen as byproducts, allow access to several dendritic macromolecules bearing up to seven different phosphorus units in their backbone, each of them featuring specific reactivity. The presence of the highly aurophilic PNPS fragment enables selective ligation of AuI within the dendritic framework. [ABSTRACT FROM AUTHOR]

A series of supermolecular liquid crystals has been synthesized by combining phosphorus dendrimers of the zero, first, and fourth generations with sulfonamide derivatives, thus generating dendromesogens bearing 6, 12, and 96 mesogenic units on their surfaces. The relevant reactions could be monitored by 1H, 19F, and 31P{1H} NMR spectroscopies. The thermal and mesomorphic properties of the products have been studied by optical microscopy, differential scanning calorimetry, and X-ray diffraction. All of the new macromolecules prepared in this work have been found to show mesomorphic properties over a wide temperature range; moreover, for all of the compounds, the columnar mesophases observed were maintained or vitrified at room temperature. On increasing the generation of these dendromesogens, mesophases appear at lower temperatures and remain stable over a wider temperature interval. In all cases, on the basis of X-ray analysis, a cylindrical symmetry of the molecules can be proposed to promote the supramolecular columnar arrangement observed in the mesophases. In this type of model, the height of the dendrimer clearly increases with increasing dendrimer generation, whereas its cross-sectional area increases only slightly, probably due to compression of the highly hyperbranched structures as a consequence of their progressive steric constraints. The mesomorphic arrangement is governed by the peripheral sulfonamide units. [ABSTRACT FROM AUTHOR]

Novel silicates were prepared by using silylated natural fatty acids (derived from triglyceride renewable oils) as co-condensing reagents in presence of tetraethyl orthosilicate (TEOS) and the triblock copolymer, pluronic P123, as a structure directing agent. A series of carboxylic acid functionalized SBA-15-type mesoporous silicates were obtained with tunable nanoscopic order and reactive functional groups that allow the conjugation of amino probes by peptide coupling. Photophysical studies of the covalently linked aminopyrene substantiated that the internal framework of these materials have pronounced hydrophobicity. Moreover, phase separation that can emanate from the bulkiness of the starting fatty silanes has been ruled out owing to the absence of excimers after aminopyrene grafting. The hemotoxicity, cytotoxicity, and antimicrobial activity of these novel silicates were then evaluated. Without discrimination, the functionalized silicates show a significant decrease of red blood cell hemolysis as compared to bare SBA-15-silica material. Within the modified silicate series, germanium-free mesoporous silicates induce only a slight decrease in cell viability and, more interestingly, they exhibit negligible hemolytic effect. Moreover, increasing their concentration in the medium reduces the concentration of released hemoglobin as a result of Hb adsorption. Promising antimicrobial properties were also observed for these silicates with a slight dependency on whether phenylgermanium fragments were present within the silicate framework. [ABSTRACT FROM AUTHOR]

The synthesis of three new families of dendrimeric compounds possessing two different types of functions is reported. These functions are triethoxysilyl group(s), potentially suitable for grafting onto materials, in particular silica, and primary amines (in their protected form), potentially suitable for trapping CO2. All these dendrimeric compounds are based on phosphorus dendrimers, and possess either one Si(OEt)3 group at the core of dendrons or of 'off-centre' dendrimers, or several Si(OEt)3 groups precisely placed on half of the terminal groups. These compounds are characterized by 31P NMR spectroscopy, which affords precious information on the structure, confirmed, in one case, by the X-ray diffraction structure of a first-generation dendrimer. [ABSTRACT FROM AUTHOR]

The Jørgensen-Hayashi catalyst [( S)-α,α-diphenylprolinol trimethylsilyl ether] was grafted onto the surface of two different supports: phosphorus dendrimers (generations 1 to 3) and magnetic, polymer-coated cobalt/carbon (Co/C) nanobeads. These new supported catalysts displayed high activities and selectivities in the Michael additions of a wide range of aldehydes to different nitroolefins. Moreover, the dendrimer of the third generation displayed excellent recycling abilities since it could be recovered and reused in 7 consecutive runs without loss of activity. [ABSTRACT FROM AUTHOR]

Hold on to your palladium! Phosphines have been grafted on magnetic Co/C nanoparticles through π–π interactions. The resulting Pd complexes showed high activity for Suzuki couplings and the system involving a dendritic ligand was recyclable, allowing the preparation of the drug Felbinac over 12 consecutive runs with minimal Pd leaching. After extraction with CH2Cl2, Felbinac met the requirements of the pharmaceutical industry (<5 ppm Pd). [ABSTRACT FROM AUTHOR]

The photophysical and two-photon absorption (TPA) properties of biphotonic chromophores with one or two phenol pendant units were studied and compared with that of a model biphotonic quadrupolar chromophore. A water-soluble dendritic structure was then synthesized by using the pendant moieties as starting points for the construction of dendritic branches. We show that the polarity of the environment significantly modulates both the fluorescence and the TPA responses of the different chromophoric derivatives. This extends to more subtle effects that involve phenol pendant moieties that were found to act as discrete solvating units and to modify both the photophysics and the TPA response of the chromophore. This demonstrates the high sensitivity of the TPA response of quadrupolar derivatives to minute alterations in the environment. Moreover, the dendritic branches were found to behave as a peculiar cybotactic environment that was able to tune the fluorescence and TPA response of the inner chromophore by creating a polar environment. This reveals a new direction for exploiting such effects by playing on the dendritic architecture (e.g., the nature and shape of the building blocks, the geometry and position of the chromophore) to modulate the TPA responses. [ABSTRACT FROM AUTHOR]

As first defensive line, monocytes are a pivotal cell population of innate immunity. Monocyte activation can be relevant to a range of immune conditions and responses. Here we present new insights into the activation of monocytes by a series of phosphonic acid-terminated, phosphorus-containing dendrimers. Various dendritic or subdendritic structures were synthesized and tested, revealing the basic structural requirements for monocyte activation. We showed that multivalent character and phosphonic acid capping of dendrimers are crucial for monocyte targeting and activation. Confocal videomicroscopy showed that a fluorescein-tagged dendrimer binds to isolated monocytes and gets internalized within a few seconds. We also found that dendrimers follow the phagolysosomial route during internalization by monocytes. Finally, we performed fluorescence resonance energy transfer (FRET) experiments between a specifically designed fluorescent dendrimer and phycoerythrin-coupled anti-bodies. We showed that the typical innate Toll-like receptor (TLR)-2 is clearly involved, but not alone, in the sensing of dendrimers by monocytes. In conclusion, phosphorus-containing dendrimers appear as precisely tunable nanobiotools able to target and activate human innate immunity and thus prove to be good candidates to develop new drugs for immunotherapies. [ABSTRACT FROM AUTHOR]