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Dendritic hydrogels based on carbosilane crosslinkers are promising drug delivery systems, as their amphiphilic nature improves the compatibility with poorly water-soluble drugs. In this work, we explored the impact of the complementary polymer on the amphiphilic properties of the dendritic network. Different polymers were selected as precursors, from the highly lipophilic propylene glycol (PPG) to the hydrophilic polyethylene glycol (PEG), including amphiphilic Pluronics L31, L35 and L61. The dithiol polymers reacted with carbosilane crosslinkers through UV-initiated thiol–ene coupling (TEC), and the resultant materials were classified as non-swelling networks (for PPG, PLUL31 and PLUL61) and high-swelling hydrogels (for PEG and PLUL35). The hydrogels exhibited thermo-responsive properties, shrinking at higher temperatures, and exhibited an intriguing drug release pattern due to internal nanostructuring. Furthermore, we fine-tuned the dendritic crosslinker, including hydroxyl and azide pendant groups in the focal point, generating functional networks that can be modified through degradable (ester) and non-degradable (triazol) bonds. Overall, this work highlighted the crucial role of the amphiphilic balance in the design of dendritic hydrogels with thermo-responsive behavior and confirmed their potential as functional networks for biomedical applications. [ABSTRACT FROM AUTHOR]

Cationic dendritic amphiphiles were prepared through the linkage of interesting hydrophobic molecules such as cholesterol or vitamin E to the focal point of carbosilane dendrons. These new dendritic systems self-assembled in saline, producing micellar aggregates with hydrodynamic diameters ranging from 6.5 to 9.2 nm, and critical micelle concentrations of approximately 5 and 10 μM for second- and third-generation systems, respectively. The assemblies were able to encapsulate drugs of different charges (anionic, neutral, and cationic). Surprisingly, a 92% encapsulation efficiency for diclofenac was achieved in micelles prepared from second-generation dendrons. Toxicity measurements on peripheral blood mononuclear cells indicated different behavior depending on the generation, corresponding to the micellar regime. In contrast to the third-generation system, the second-generation system was non-toxic up to 20 μM, opening a window for its use in a micellar regimen, thereby operating as a drug delivery system for different biomedical applications. [ABSTRACT FROM AUTHOR]

This review describes the synthesis of polyphosphorhydrazone (PPH) dendrimers,which are highly branched macromolecules, having a phosphorus atom at each branching point. The properties of these PPH dendrimers in the field of catalysis are then described. The review is organized to illustrate in the first part how the specificities of dendrimers could contribute to green chemistry. This concerns in particular the dendritic effect that is an increased efficiency (yield, enantioselectivity, etc.) when the size of the dendrimer increases, the recovery and reuse of the dendritic catalyst, the decreased leaching, and the entrapping of nanoparticles. In a second part, some even greener approaches of catalysis with dendrimers will be displayed, such as catalysis in water, switchable catalysis, and organocatalysis (nometal used). Different types of catalytic reactions have been studied, such as Stille, Suzuki and Sonogashira couplings, Knoevenagel condensations, Michael additions, asymmetric allylic alkylations, O- and N-arylation and vinylation reactions, [2+2+2]-cycloaddition reactions, isomerization of 1-octan-3-ol, Friedel--Crafts acylations, Heck reactions, hydrogenations, hydrations, transfer hydrogenations, amination of β-dicarbonyl compounds, etc. [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]

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]

This review presents the synthesis of dendrons (dendritic wedges) based on cyclotriphosphazene cores, in which one function is a fluorescent group, and the five remaining functions are used for growing the dendritic branches. The growing of the branches is carried out by a divergent method, using a two‐step process which implies hydroxybenzaldehyde and the phosphorhydrazide H2NNMeP(S)Cl2. Four different fluorophores have been used, derived from maleimide, julolidine, pyrene, or from a near‐infra‐red fluorophore. Depending on the type of fluorophore and on the type of terminal functions of the dendrons, different applications have been targeted. One can cite experiments in catalysis or for the elaboration of materials, transfection experiments, the study of anti‐cancer properties, and imaging in relation with the human immune system. [ABSTRACT FROM AUTHOR]

Dendritic hydrogels based on carbosilane crosslinkers are promising drug delivery systems, as their amphiphilic nature improves the compatibility with poorly water-soluble drugs. In this work, we explored the impact of the complementary polymer on the amphiphilic properties of the dendritic network. Different polymers were selected as precursors, from the highly lipophilic propylene glycol (PPG) to the hydrophilic polyethylene glycol (PEG), including amphiphilic Pluronics L31, L35 and L61. The dithiol polymers reacted with carbosilane crosslinkers through UV-initiated thiol–ene coupling (TEC), and the resultant materials were classified as non-swelling networks (for PPG, PLUL31 and PLUL61) and high-swelling hydrogels (for PEG and PLUL35). The hydrogels exhibited thermo-responsive properties, shrinking at higher temperatures, and exhibited an intriguing drug release pattern due to internal nanostructuring. Furthermore, we fine-tuned the dendritic crosslinker, including hydroxyl and azide pendant groups in the focal point, generating functional networks that can be modified through degradable (ester) and non-degradable (triazol) bonds. Overall, this work highlighted the crucial role of the amphiphilic balance in the design of dendritic hydrogels with thermo-responsive behavior and confirmed their potential as functional networks for biomedical applications.

Cationic dendritic amphiphiles were prepared through the linkage of interesting hydrophobic molecules such as cholesterol or vitamin E to the focal point of carbosilane dendrons. These new dendritic systems self-assembled in saline, producing micellar aggregates with hydrodynamic diameters ranging from 6.5 to 9.2 nm, and critical micelle concentrations of approximately 5 and 10 μM for second- and third-generation systems, respectively. The assemblies were able to encapsulate drugs of different charges (anionic, neutral, and cationic). Surprisingly, a 92% encapsulation efficiency for diclofenac was achieved in micelles prepared from second-generation dendrons. Toxicity measurements on peripheral blood mononuclear cells indicated different behavior depending on the generation, corresponding to the micellar regime. In contrast to the third-generation system, the second-generation system was non-toxic up to 20 μM, opening a window for its use in a micellar regimen, thereby operating as a drug delivery system for different biomedical applications.

The Staudinger reaction between a phosphine and an azide, applied to phosphorus azides, has been used for the synthesis of a large variety of dendritic structures, incorporating P=N−P=X moieties (X = mainly S, but also O and N−R). Conjugation of the P=N bond with the P=X bond greatly stabilizes the P=N bond. Highly branched structures such as dendrons, dendrimers, Janus dendrimers, layered dendrimers, surface‐block dendrimers, and diverse other dendritic structures incorporating such linkage have been elaborated. Accelerated methods of synthesis of dendrimers are also based on the Staudinger reaction. A versatile reactivity was observed exclusively on the sulfur atom of P=N−P=S linkages, such as alkylation or complexation. Alkylation on S induces a weakening of the strength of the P=S bond, which can be easily cleaved to generate phosphines able to react in Staudinger reactions inside the structure of dendrimers, thus affording highly sophisticated dendritic structures. [ABSTRACT FROM AUTHOR]

Hydrogels are hydrophilic, three-dimensional networks able to imprison large amounts of water and are largely used in pharmaceutical formulations. Hydrogels are frequently obtained from hydrophilic polymers, either natural, biohybrid, or synthetic. Owing to their peculiar structure, dendrimers can be considered prospective building blocks for hydrogel networks. This review gathers the use of different types of amphiphilic dendritic structures able to generate physical hydrogels alone. Such dendritic structures comprise dendrimers, Janus dendrimers, and dendrons. The first part concerns different types of positively charged phosphorus dendrimers used to generate hydrogels, which are also suitable to form fibers, and for encapsulating diverse substances, or forming complexes with genetic materials for their slow delivery. The second part concerns PAMAM dendrimers functionalized with collagen mimetics. The third part concerns amphiphilic Janus dendrimers, whereas the fourth part displays different types of amphiphilic dendrons and their use, in particular in the fields of materials and drug delivery. [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]

Functional supramolecular gel materials have potential applications in sensors, optical switches, artificial antennae, drug delivery and so on. In this paper, quinoline‐cored poly(aryl ether) dendritic organogelators were designed, synthesized and fully characterized. The gelation behaviour of the dendritic organogelator was tested in organic solvents, mixed solvents and ionic liquids. The dendron Q‐G1 was found to be an efficient and versatile organogelator toward various apolar and polar organic solvents with the critical gelation concentrations (CGCs) approaching 1.2×10−2 mol/L, indicating one dendritic organogelator could immobilize 1.2×103 solvent molecules in the organogel network. Interestingly, these dendrons exhibited excellent gel formation in ionic liquids. Notably, these dendritic organogels were found to display multiple stimuli‐responsive properties toward external stimuli including heat, ultrasound and shear stress, with a reversible sol‐gel phase transition. In addition, the dendritic organogel could effectively adsorb heavy metals and organic dyes. The removal rate of Pb2+ was up to 20% and the adsorption rate for Rhodamine B was as high as 89%. [ABSTRACT FROM AUTHOR]

[Display omitted] • 'Hard' and 'soft' nanoparticles differently affected phospholipase A 2. • 'Soft' nanoparticles formed aggregates/micelles with protein. • 'Hard' nanoparticle had bimolecular interaction with protein. The interaction of nanoparticles (NP) with proteins (the so-called 'protein corona') is a huge challenge in attempting to apply them in personalized nanomedicine. We have analyzed the interaction between A) two 'soft' NPs (a cationic phosphorus dendrimer of generation 3; a cationic phosphorus amphiphilic dendron of generation 2), and B) one 'hard' nanoparticle (silver NP covered with cationic carbosilane dendritic moieties); and membrane-bound protein phospholipase A2 from bovine pancreas. The hard and soft NPs have differences in the nature of their interactions with phospholipase A2. This enzyme surrounds hard AgNP, whereas dendrimer and amphiphilic dendron form aggregates/micelles with phospholipase A2. There is a difference in action of phospholipase A2 bound to the core of dendrimer, and of micelles formed from non-covalent interactions between the amphiphilic dendron. These data are important in understanding the nature of interaction between different kinds of nanoparticles and proteins. [ABSTRACT FROM AUTHOR]

Acute stress is a potent suppressor of pulsatile luteinizing hormone (LH) secretion, but the mechanisms through which corticotrophin-releasing hormone (CRH) neurons inhibit gonadotropin-releasing hormone (GnRH) release remain unclear. The activation of paraventricular nucleus (PVN) CRH neurons with Cre-dependent hM3Dq in Crh-Cre female mice resulted in the robust suppression of pulsatile LH secretion. Channelrhodopsin (ChR2)-assisted circuit mapping revealed that PVN CRH neuron projections existed around kisspeptin neurons in the arcuate nucleus (ARN) although many more fibers made close appositions with GnRH neuron distal dendrons in the ventral ARN. Acutely prepared brain slice electrophysiology experiments in GnRH- green fluorescent protein (GFP) mice showed a dose-dependent (30 and 300 nM CRH) activation of firing in ~20% of GnRH neurons in both intact diestrus and ovariectomized mice with inhibitory effects being uncommon (<8%). Confocal GCaMP6 imaging of GnRH neuron distal dendrons in acute para-horizontal brain slices from GnRH-Cre mice injected with Cre-dependent GCaMP6s adeno-associated viruses demonstrated no effects of 30 to 300 nM CRH on GnRH neuron dendron calcium concentrations. Electrophysiological recordings of ARN kisspeptin neurons in Crh-Cre,Kiss1- GFP mice revealed no effects of 30 -300 nM CRH on basal or neurokinin B-stimulated firing rate. Similarly, the optogenetic activation (2-20 Hz) of CRH nerve terminals in the ARN of Crh-Cre,Kiss1- GFP mice injected with Cre-dependent ChR2 had no effect on kisspeptin neuron firing. Together, these studies demonstrate that PVN CRH neurons potently suppress LH pulsatility but do not exert direct inhibitory control over GnRH neurons, at their cell body or dendron, or the ARN kisspeptin neuron pulse generator in the female mouse. [ABSTRACT FROM AUTHOR]

Background/AimsDirect sequencing is the gold standard for the detection of drug-resistance mutations in hepatitis B virus (HBV); however, this procedure is time-consuming, labor-intensive, and difficult to adapt to high-throughput screening. In this study, we aimed to develop a dendron-modified DNA microarray for the detection of genotypic resistance mutations and evaluate its efficiency.Methods : The specificity, sensitivity, and selectivity of dendron-modified slides for the detection of representative drug-resistance mutations were evaluated and compared to those of conventional slides. The diagnostic accuracy was validated using sera obtained from 13 patients who developed viral breakthrough during lamivudine, adefovir, or entecavir therapy and compared with the accuracy of restriction fragment mass polymorphism and direct sequencing data.Results : The dendron-modified slides significantly outperformed the conventional microarray slides and were able to detect HBV DNA at a very low level (1 copy/μL). Notably, HBV mutants could be detected in the chronic hepatitis B patient sera without virus purification. The validation of our data revealed that this technique is fully compatible with sequencing data of drug-resistant HBV.Conclusion : sWe developed a novel diagnostic technique for the simultaneous detection of several drug-resistance mutations using a dendron-modified DNA microarray. This technique can be directly applied to sera from chronic hepatitis B patients who show resistance to several nucleos(t)ide analogues.

The neural mechanisms generating pulsatile GnRH release from the median eminence (ME) remain unclear. Studies undertaken in the mouse demonstrate that GnRH neurons extend projections to the ME that have properties of both dendrites and axons, termed "dendrons," and that the kisspeptin neuron pulse generator targets these distal dendrons to drive pulsatile GnRH secretion. It presently remains unknown whether the GnRH neuron dendron exists in other species. We report here the generation of a knock-in Gnrh1-Ires-Cre rat line with near-perfect targeting of Cre recombinase to the GnRH neuronal phenotype. More than 90% of adult male and female GnRH neurons express Cre with no ectopic expression. Adeno-associated viruses were used in adult female Gnrh1-Ires-Cre rats to target mCherry or GCAMP6 to rostral preoptic area GnRH neurons. The mCherry tracer revealed the known unipolar and bipolar morphology of GnRH neurons and their principal projection pathways to the external zone of the ME. Synaptophysin-labeling of presynaptic nerve terminals revealed that GnRH neuron distal projections received numerous close appositions as they passed through the arcuate nucleus and into the median eminence. Confocal GCaMP6 imaging in acute horizontal brain slices demonstrated that GnRH neuron distal projections lateral to the median eminence were activated by kisspeptin. These studies indicate the presence of a dendron-like arrangement in the rat with GnRH neuron distal projections receiving synaptic input and responding to kisspeptin. [ABSTRACT FROM AUTHOR]

Three new amino-s-triazine-based dendrons, 1a, 1b, and 1c, containing an aryl-CN moiety in the dendritic skeleton were prepared in 72–81% yields (1a: R1 = − N(n-C8H17)2, R2 = n-OC8H17, 1b: R1 = R2 = − N(n-C8H17)2, 1c: R1 = − N(n-C8H17)2, R2 = − N(n-C4H9)2). Dendrons 1a with N(n-C8H17)2 and n-OC8H17 peripheral substituents, surprisingly, did not show any mesogenic phase during the thermal process. However, non-mesogenic 1a can be converted to mesogenic 1b or 1c by eliminating the peripheral dipole arising from the alkoxy substituent; dendron 1b only comprising the same N(n-C8H17)2 peripheral groups showed a ~25 °C mesogenic range on heating and ~108 °C mesogenic range on cooling. In contrast, dendron 1c possessing different N(n-CmH2m+1)2 (m = 8 versus m = 4) peripheral units, having similar stacking as 1b, exhibited a columnar phase on thermal treatment, but its mesogenic range (~9 and ~66 °C on heating and cooling, respectively) was much narrower than that of 1b, attributed to 1c’s less flexible alkyl chains in the peripheral part of dendron. Dendron 1a with the alkoxy substituent in the peripheral skeleton, creating additional dipole correspondingly, thus, leads to the dendritic molecules having a non-mesogenic stacking. Without the peripheral dipole for intermolecular side-by-side interaction, dendrons 1b and 1c exhibit a columnar phase on thermal treatment because of the vibration from the peripheral alkyl chain.

Carbon-carbon cross-coupling reactions are among the most important synthetic tools for the preparation of pharmaceuticals and bioactive compounds. However, these reactions are normally carried out using copper, phosphines, and/or amines, which are poisonous for pharmaceuticals. The use of nanocomposite catalysts holds promise for facilitating these reactions and making them more environmentally friendly. In the present work, the PEGylated (PEG stands for poly(ethylene glycol) pyridylphenylene dendrons immobilized on silica loaded with magnetic nanoparticles have been successfully employed for the stabilization of Pd2+ complexes and Pd nanoparticles. The catalyst developed showed excellent catalytic activity in copper-free Sonogashira and Heck cross-coupling reactions. The reactions proceeded smoothly in green solvents at low palladium loading, resulting in high yields of cross-coupling products (from 80% to 97%) within short reaction times. The presence of magnetic nanoparticles allows easy magnetic separation for repeated use without a noticeable decrease of catalytic activity due to the strong stabilization of Pd species by rigid and bulky dendritic ligands. The PEG dendron periphery makes the catalyst hydrophilic and better suited for green solvents. The minor drop in activity upon the catalyst reuse is explained by the formation of Pd nanoparticles from the Pd2+ species during the catalytic reaction. The magnetic separation and reuse of the nanocomposite catalyst reduces the cost of target products as well as energy and material consumption and diminishes residual contamination by the catalyst. These factors as well as the absence of copper in the catalyst makeup pave the way for future applications of such catalysts in cross-coupling reactions.

AB5 compounds issued from the reactivity of hexachlorocyclotriphosphazene are relatively easy to obtain using two ways: either first the reaction of one chloride with one reagent, followed by the reaction of the five remaining Cl with another reagent, or first the reaction of five chlorides with one reagent, followed by the reaction of the single remaining Cl with another reagent. This particular property led to the use of such compounds as core for the synthesis of dendrons (dendritic wedges), using the five functions for growing the dendritic branches. The single function can be used for the synthesis of diverse types of dendrimers (onion peel, dumbbell-shape, Janus), for covalent or non-covalent grafting to solid surfaces, providing nanomaterials, for grafting a fluorophore, especially for studying biological mechanisms, or for self-associations to get micelles. All these properties are reviewed in this paper.

A unique property of 2,4,6-trichloro-1,3,5-triazine (TCT) is its ability to undergoes a nucleophilic aromatic substitution reaction (SNAr) under temperature-controlled conditions. Using a convenient and biologically friendly protocol, mono-substituted s-triazines were treated with excess nucleophiles to obtain tri-substituted triazines in 1 + 2 mode (one nucleophile as the first substitution followed by another nucleophile for the other two positions). The nucleophiles used for this study were phenol, thiol and amine, and the best order of incorporation was phenol or thiol for the first position followed by amine for the last two positions. [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]

A novel silica‐based fluorescent sensor, (S‐DPP), was prepared via grafting of dimethyl 3,3′‐(propylazanediyl)(1Z,1′Z)‐bis(N‐(9H‐fluoren‐2‐yl)propanimidate) (DPP), onto the pore walls of SBA‐15 channels. DPP was prepared by growing of dendrimer (G= 0.5) onto the amino functionalized surface of SBA‐15, followed by anchoring of 2‐aminflourene via imine condensation. Synthesized materials were characterized using FT‐IR, PXRD, SEM, TEM, BET and TGA techniques. Fluorescence properties of the sensor were investigated in aqueous solution towards various metal ions. The signal quenching of sensor at λ=380 nm is based on complex formation between the S‐DPP and Fe3+ or Hg2+ ions, leading to the inhibition of reverse intramolecular charge transitions at the probe and appearance of new transitions at Mn+—S‐DPP complex. Furthermore, the limit of detection of both ions were calculated as 2.4 × 10−8 M and 6.3 × 10−8 M, respectively. A reversibility in fluorescence behavior of the probe was found in the presence of Cl−, and was demonstrated a circuit logic system with the Fe3+, Hg2+ and Cl− ions. Finally, density functional theory (DFT) and time‐dependent density functional theory (TDDFT) computational studies were performed in order to obtain a detailed electronic description of the quenching mechanism by Hg2+ and Fe3+ as well as studying the structure and bonding in the complexes. [ABSTRACT FROM AUTHOR]

• Three rhodamine conjugated novel dendron-based fluorophores were synthesized. • Hydrophobicity of the fluorophores were tailored for increased intracellular uptake. • The dendron-based fluorophores self-assembled to form spherical aggregates. • The fluorophores could effectively sense mercury ion in vitro with high selectivity. • Optimally hydrophobic fluorophore exhibited effective intracellular uptake in HEK293 cells. Fluorophores are used for sensing biologically relevant ions, toxic metals or pathogenic markers. However, the mode of entry of such fluorophores into the cell greatly depends on their size, shape, surface charge, functional groups, and hydrophobicity. In particular, the influence of hydrophobicity on the intracellular uptake of fluorophores is poorly investigated. Self-assembly is a recent strategy to tune the intracellular uptake of fluorophores, facilitating increased intracellular sensing and fluorescence. Herein, self-assembly of three novel poly(aryl ether) dendron derivatives that contain rhodamine units was used to investigate the effect of hydrophobicity on the intracellular uptake of self-assembled fluorophores. The results suggest that monomer hydrophobicity plays an important role in the uptake. The dendron-based fluorophores, which upon self-assembly, formed stable spherical aggregates ranging from 300 to 500 nm. The rhodamine-based dendrons could selectively sense Hg2+ ions in the presence of other competing metal cations. Intracellular imaging of the dendron-based fluorophores displayed bright red fluorescence in human embryonic kidney cells. The rate of intracellular uptake of the three dendron-based fluorophores was analyzed by flow cytometry. The results establish the importance of the hydrophilic-lipophilic balance of the self-assembled amphiphiles for tuning the intracellular uptake. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract This investigation reports a novel nanoGold-core multifunctional dendrimer for pulsatile chemo-, photothermal- and photodynamic- therapy of rheumatoid arthritis (RA). Architecturally, the nanocomposites comprised of a nanoGold (Au) at the focal whose surface is functionalized by hydroxy-terminated thiolated-dendrons following Au-thiol bond formation to produce nanoGold-core multifunctional dendrimer (Au-DEN). The surface hydroxyl groups of Au-DEN were then conjugated with methotrexate (MTX; a disease-modifying first line anti-rheumatic drug; DMARD; 74.29 ± 0.48% loading) to form Au-DEN-MTX-NPs (Particle size: 100.15 ± 28.36 nm; poly dispersibility index, PDI: 0.39 ± 0.02; surface zeta potential, ζ: −22.45 ± 1.06 mV). MTX was strategically selected to serve as an anti-rheumatic DMARD as well as a targeting ligand to attain selective localization of the formulation in arthritic tissue via folate receptors upregulated on arthritic tissues. The docking study was performed to confirm the viable binding efficiency of MTX towards β-folate receptors that are overexpressed on arthritic tissues taking folic acid as a reference standard. The IR780, a NIR active bioactive was also loaded in Au-DEN-MTX NPs to offer photothermal benefit upon irradiation with NIR laser (wavelength: 808 nm). The hypothesis was tested by elucidation of in vitro drug release profile, photothermal activity, cellular uptake (Fluorescence and confocal laser scanning microscopy; CLSM), cell viability assay (MTT protocol) and Intracellular reactive oxygen species (ROS) generation in mouse macrophage RAW264.7 cells and Lipopolysaccharide (LPS) activated RAW264.7 cells. Furthermore, the hemolytic toxicity and stability studies were also investigated to determine the blood compatibility as well as ideal storage condition of NPs. The outcome of this investigations presents developed multifunctional targeted NPs to be potential therapeutics for the improved treatment of RA. The approach can also be applied to other clinical interventions involving countering inflammatory conditions. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The engineering of iron oxide nanoparticles (IONPs) for biomedical use has received great interest over the past decade. In the present study we investigated the biocompatibility of IONPs grafted with linear (2P) or generation 1 (2PG1) or 2 (2PG2) dendronized oligoethyleneglycol units in THP-1-derived macrophages. To evaluate IONP effects on cell functionality and homeostasis, mitochondrial function (MTT assay), membrane permeability (LDH release), inflammation (IL-8), oxidative stress (reduced glutathione, GSH), NLRP3 inflammasome activation (IL-1β) and nanoparticle cellular uptake (intracellular iron content) were quantified after a 4-h or 24-h cell exposure to increasing IONP concentrations (0–300 µg Fe/mL). IONPs coated with a linear molecule, NP10COP@2P, were highly taken up by cells and induced significant dose-dependent IL-8 release, oxidative stress and NLRP3 inflammasome activation. In comparison, IONPs coated with dendrons of generation 1 (NP10COP@2PG1) and 2 (NP10COP@2PG2) exhibited better biocompatibility. Effect of the dendritic architecture of the surface coating was investigated in a kinetic experiment involving cell short-term exposure (30 min or 1 h 30) to the two dendronized IONPs. NP10COP@2PG2 disrupted cellular homeostasis (LDH release, IL-1β and IL-8 secretion) to a greater extend than NP10COP@2PG1, which makes this last IONP the best candidate as MRI contrast or theranostic agent. [ABSTRACT FROM AUTHOR]

Supramolecular constructions of amphiphilic dendritic molecules are promising vehicles for anti-cancer drug delivery due to the flexibility of their architecture, high drug loading capacity and avoiding off-target effects of a drug. Herein, we report a new class of amphiphilic dendritic species—triazine-carbosilane dendrons readily self-assembling into pH-sensitive dendrimersomes. The dendrimersomes efficiently encapsulate anticancer drugs doxorubicin and methotrexate. Chemodrug-loaded dendrimersomes have dose-related cytotoxic activity against leukaemia cell lines 1301 and K562. Our findings suggest that triazine-carbosilane dendrimersomes are prospective drug carriers for anti-cancer therapy.

Background: Gene delivery to target cells is crucially important to establish gene therapy and regenerative medicine. Although various virus-based and synthetic molecule-based gene vectors have been developed to date, selective transfection in a site or a cell level is still challenging. For this study, both light-responsive and temperature-responsive synthetic gene vectors were designed for spatiotemporal control of a transfection system. Methods: 11-Mercaptoundecanoic acid-coated gold nanorods were mixed with polyamidoamine dendron-bearing lipids of two types having amino-terminus or ethoxydiethylene glycol-terminus to obtain hybrid vectors. Hybrid vectors were mixed further with pDNA. Then we investigated their physicochemical properties and transfection efficacy with or without near infrared laser irradiation. Results: Hybrid vectors formed complexes with pDNA and exhibited enhanced photothermal property under near infrared laser irradiation compared with parent gold nanorods. Transfection efficacy of complexes was promoted considerably by brief laser irradiation soon after complex application to the cells. Analysis of intracellular distribution revealed that laser irradiation promoted the adsorption of complexes to the cells and cytosolic release of pDNA, which is derived from the change in surface hydrophobicity of complexes through dehydration of temperature-responsive groups. Conclusions: Hybrid vector is promising as a light-activatable transfection system.

The explosive growth of nanotechnology has brought challenging innovations in the synthesis of multifunctional nano-objects able to revolutionize the field of diagnosis and therapy in medicine. Furthermore, one important input of today’s nanotechnology in biology is that their design will also allow real progress to achieve temporal and spatial site local therapy and imaging. Such a breakthrough is made possible by the development of multifunctional biocompatible nanosystems resulting from cutting-edge researches based on pluridisciplinary approaches. Among the challenges are the design of the organic coating and its grafting at the surface of NPs while preserving the properties of both NPs and molecules. The molecules should ensure the colloidal stability of NPs in physiological media, their biocompatibility and biodistribution, and may bear functions to couple bioactive groups. This paper aims at providing challenges in functionalization of iron oxide nanoparticles for biomedical applications.

Dendrimers are monodisperse polymers grown in a fractal manner from a central point. They are poised to become the cornerstone of nanoscale devices in several fields, ranging from biomedicine to light-harvesting. Technical difficulties in obtaining these molecules has slowed their transfer from academia to industry. In 2001, the arrival of the “click chemistry” concept gave the field a major boost. The flagship reaction, a modified Hüisgen cycloaddition, allowed researchers greater freedom in designing and building dendrimers. In the last five years, advances in click chemistry saw a wider use of other click reactions and a notable increase in the complexity of the reported structures. This review covers key developments in the click chemistry field applied to dendrimer synthesis from 2010 to 2015. Even though this is an expert review, basic notions and references have been included to help newcomers to the field.

Separation of PEGylated protein mixtures into individual species is a challenging procedure, and many efforts have been focused on creating novel chromatographic supports for this purpose. In this study, a new monolithic stationary phase with hyperbranched nanostructures was chemically synthesized. For this, monoliths with a support matrix of poly (glycidyl methacrylate-co-ethylene dimethacrylate) and ethylenediamine chemistry were modified with third-generation dendrons with butyl-end groups. The new monolith was analyzed by infrared spectroscopy, confirming the dendron with butyl ligands and exhibited low mass transfer resistance as observed by breakthrough frontal analysis. This support was able to separate mono-PEG ribonuclease A from the PEGylation mixture, indicated by a single band (∼30 kDa) in the electrophoretic analysis. Moreover, the separation of mono-PEGylated positional isomers was probably observed, as the protein with ∼30 kDa was found in two separate peaks. Interestingly, the dendronized monolith allowed the separation of the reaction mixture into individual PEGylated species when using high ammonium sulfate concentrations (2 M). A correlation between the PEGylation degree and the strength of the hydrophobic interactions on the monolith was observed. This chromatographic approach combines the natural branched architecture of dendrons and the higher capabilities of the monoliths enhancing the hydrophobic surface area, and therefore the interaction between the PEGylated proteins and ligands. Thus, the novel support represents a novel platform for the purification of PEGylated from non-PEGylated proteins with biotechnological applications., (© 2023 Wiley-VCH GmbH.)

Graphical abstract Abstract A series of small-sized (about 2.0 nm) gold nanoparticles (AuNPs) with apparent lattice fringes are synthesized by NaBH 4 reduction of HAuCl 4 in the presence of stabilizing linear or dendronized 1,2,3-triazolyl-containing ferrocenyl polymers. These AuNPs show high catalytic activity for biphasic 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) by NaBH 4. The lower generation G1 dendronized polymers (DPs) is a more efficient stabilizer for AuNP catalytic activity in the reduction of 4-NP than linear G0 polymers or bulky G2 DPs. The G1 DP-stabilized AuNPs are robust and easily recyclable, and the catalyst is recovered and reused at least twenty times with progressive smooth AuNP size increase along with some decrease of catalytic activity. [ABSTRACT FROM AUTHOR]

Syntheses of dendrons for dendrimer applications are described using napthyl and urethane derivatives. The napthol, 1‐(3‐hydroxy‐6‐(methoxymethoxy)naphthalen‐1‐yl)ethan‐1‐one (h), was synthesized by employing Au‐catalyzed cyclization of the corresponding propargylic carboxylates. Polynapthol dendrons (i, j, k, and l) were prepared from substitution reactions of napthyl derivative h with alkyl/aryl halides under basic conditions. Branched polyurethane compounds (q, r, and s) were also prepared from addition reactions of 1,3,5‐tris(6‐isocyanteohexyl)‐1,3,5‐triazine‐2,4,6‐trione (p) with various alcohols under Lewis acidic conditions. The photophysical properties of the synthesized compounds h, k, and j were studied. [ABSTRACT FROM AUTHOR]

This review highlights the utilization of dendron-polymer conjugates as building blocks for the fabrication of nanosized drug delivery vehicles. The examples given provide an overview of the evolution of these delivery platforms, from simple micellar containers to smart stimuli- responsive drug delivery systems through their design at the macromolecular level. Variations in chemical composition and connectivity of the dendritic and polymeric segments provide a variety of self-assembled micellar nanostructures that embody desirable attributes of viable drug delivery systems. [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]

A multi-ion fluorescent probe for Mg 2+ /Zn 2+ , 7-methoxychromone-3-carbaldehyde-(3′,4′,5′-tris(benzyloxy) benzoyl) hydrazone ( L ), based on a novel chromone-dendron Schiff base was designed and synthesized. The simultaneous detection of Mg 2+ and Zn 2+ was realized by regulating solvent: L showed excellent selectivity and high sensitivity toward Mg 2+ in ethanol and Zn 2+ in aqueous solution. The clear binding mode and corresponding turn-on mechanism (PET) were elucidated in this paper. [ABSTRACT FROM AUTHOR]

A novel dendronized poly(ferrocenylsilane) (PFS-D) is prepared by ionic self-assembly of cationic poly(ferrocenylsilane) of [Fe(η-C 5 H 4 ) 2 SiMe- (OCH 2 CH 2 NMe 3 I)] n (PFS) with anionic dendrons of 3,4,5-tris( n -octane-1-yloxy)- benzoic acid [(3,4,5)8G1-COOK]. XRD profiles and POM indicated the presence of the liquid crystalline phase in the PFS-D at room temperature that is resulted from the dendritic amphiphiles, which formed the end-to-end bilayer lamellar structure with the long period d = 3.27 nm. PFS-D coated on Ni foam (PFS-D/Ni) was applied as electrode materials for supercapacitors. CV measurements indicated that PFS-D/Ni exhibited a good reversible redox process and this observation was deemed to originate from its ferrocenyl moieties in liquid crystalline phase. The as-prepared PFS-D/Ni possessed a specific capacitance as high as 197 F g −1 calculated from discharge curve with current density 5 A g −1 . The long-term cycle life stability for PFS-D/Ni was examined and the results showed that the capacitance decay was ∼14% over 3000 cycles, indicating its long cycle life. Furthermore, they could also be used to assemble a simple solid-state supercapacitor. In a word, the PFS-D/Ni was reported as a promising electrode material for efficient pseudo-capacitors for the first time. [ABSTRACT FROM AUTHOR]

Tadpole-type amphiphilic dendrimers featuring a hexadecyl chain and two or three poly(amidoamine) dendrons (C 16 - m denG n , where m is the number of dendron scaffolds (2 or 3) and n is the dendron (den) generation (G) number (1, 2, 3, 4, or 5)) were synthesized using hexadecylamine or N -hexadecylethylenediamine as central scaffolds. These dendrimers were characterized by acid-base titration, surface tension, pyrene fluorescence, static light scattering (SLS), and small-angle neutron scattering (SANS), and showed clear breakpoints in their surface tension vs. concentration plots. This behavior was indicative of adsorption at the air/water interface and micelle formation in solution despite the bulky dendron structure (e.g., generations 3–5), contrasting the behavior of conventional surfactants. Contrary to our expectation, the C 16 - m denG n dendrimers could be densely packed at the air/water interface owing to enhanced hydrogen bonding between amide groups in the case of higher generation numbers. Furthermore, the above dendrimers formed spherical micelles in solution at a concentration of 5.00 mmol dm −3 (pH 9), regardless of the dendron generation number. As the generation number was increased to 4 for C 16 -2denG n and 3 for C 16 -3denG n , aggregates of spherical micelles were observed. The radius of gyration of C 16 - m denG n dendrimers was estimated as 2.0–2.5 nm, being almost independent of the hydrophilic dendron size. [ABSTRACT FROM AUTHOR]

Autologous chondrocyte transplantation for cartilage repair still has unsatisfactory clinical outcomes because of inter-donor variability and poor cartilage quality formation. Re-differentiation of monolayer-expanded human chondrocytes is not easy in the absence of potent morphogens. The Vascular Endothelial Growth Factor (VEGF) plays a master role in angiogenesis and in negatively regulating cartilage growth by stimulating vascular invasion and ossification. Therefore, we hypothesized that its sole microenvironmental blockade by either VEGF sequestration by soluble VEGF receptor-2 (Flk-1) or by antiangiogenic hyperbranched peptides could improve chondrogenesis of expanded human nasal chondrocytes (NC) freshly seeded on collagen scaffolds. Chondrogenesis of several NC donors was assessed either in vitro or ectopically in nude mice. VEGF blockade appeared not to affect NC in vitro differentiation, whereas it efficiently inhibited blood vessel ingrowth in vivo. After 8 weeks, in vivo glycosaminoglycan deposition was approximately two-fold higher when antiangiogenic approaches were used, as compared to the control group. Our data indicates that the inhibition of VEGF signaling, independently of the specific implementation mode, has profound effects on in vivo NC chondrogenesis, even in the absence of chondroinductive signals during prior culture or at the implantation site. [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]

Organic-inorganic layered materials, such as organotalcs, are a promising alternative as gelling agent for liquid electrolytes in dye-sensitized solar cells. Talcs could provide an abundant, low cost and environmentally friendly option for solidifying the electrolyte. This work focuses on generation 5 polyamideamino dendron-modified talc with emphasis is on how it affects the performance and stability of the DSSC. The talc was shown to improve the initial photocurrent by up to 39% by acting as a light scatterer and/or a recombination barrier compared to reference solar cells with liquid electrolyte. Non-destructive analysis based on photographic image technique revealed that during the aging the additive absorbed charge carriers, tri-iodide, from the electrolyte reducing the performance of the solar cells. The degradation could, however, be prevented by intercalating polyiodides into interlamellar space of the talc as the resulting dendron chains did not absorb tri-iodide charge carriers from the electrolyte. These quasi-solid solar cells maintained 95% of their initial efficiency under light-soaking at 1 Sun for about 1000 h. The cells with a quasi-solid electrolyte showed up to 5% higher efficiency than those with liquid electrolyte. [ABSTRACT FROM AUTHOR]