Dendritic Materials Research Articles

FeNi alloys with controllable composition for tunable magnetic properties and broadband absorption

For the further enhancement to the microwave absorbing capabilities of magnetic dendritic materials, this work has successfully prepared dendritic FexNi1-x (x = 0.5, 0.33, 0.25, 0.2) alloys through a facile electrodeposition method. FexNi1-x alloy composition can be easily tuned by changing iron ion concentration in the electrolyte. We investigate the effects of alloy composition on the crystal structure and morphology whereby we intrinsically analyzes the magnetic characteristics and microwave absorbing performance of FexNi1-x alloys. Particularly, Fe0.25Ni0.75 alloy demonstrates the strongest microwave absorption intensity, achieving the minimum reflection loss (RLmin) of −59.02 dB at 4.96 GHz. Comprehensively, Fe0.33Ni0.67 alloy (RLmin = −49.42 dB, d = 1.68 mm) attains optimal microwave absorption performance when combining the perspectives of absorber thickness, RLmin and effective bandwidth (RL<-20 dB). RL values of Fe0.33Ni0.67 alloy at the thickness of 1.4–2.5 mm, exceed −20 dB over a wide frequency range, covering almost the whole X and Ku band (8–18 GHz). Such exceptional microwave absorption performance is attributed to the unique dendritic structure which conduces to the multiple scattering of electromagnetic microwave, hence improving impedance matching and promoting energy dissipation. In addition, the practicability of FexNi1-x alloys is further confirmed by simulating the RCS value in the far field environment.

Removing lead from water with carboxylate dendrimers and magnetic nanoparticles modified with carboxylate dendrimers

Contamination of water with heavy metals as lead (Pb2+) is a relevant problematic issue. In this work, we have tested different types of dendritic materials for lead removal from water and further recovery. The systems employed are magnetic nanoparticles (MNP) modified with monocarboxylate and dendritic carboxylate ligands, and they are compared to pristine MNP and carbosilane dendrimers. They are all effective at removing Pb2+, but the key variations are in their recyclability. The usage of a filtering membrane was required for dendrimers, which was significantly degraded by the acidic media. In terms of MNP, those that were covered by dendritic molecules were clearly less damaged in acidic media. Finally, isotherm analysis revealed that Pb2+ interacts differently with unmodified and modified MNP.

Stimuli‐Responsive Dendritic Supramolecular Vector for Tumor‐Specific Gene Delivery

To simplify the preparation of dendritic materials, host–guest molecular recognition and self‐assembly are utilized to form a supramolecular dendritic gene vector (DNCVP). DNCVP is constructed from an amino dendron‐conjugated naphthol, viologen containing pH‐sensitive hydrazone‐bond‐linked PEG, and CB[8] with a molar ratio of 1:1:1. The pH‐ and reducing‐sensitivity of DNCVP is verified, and the stimuli‐responsive capacity enables the vector tumor targeting gene delivery ability. Owing to the protection of surface PEG, the supramolecular engineering endows the delivery vector with low cytotoxicity and good biocompatibility that are confirmed by the MTT assay. The excellent delivery ability of genes is investigated by in vitro transfection of pEGFP, pGL3, and silencing of siGAPDH. In vivo studies demonstrate promoted tumor accumulation of genes mediated by the dual‐responsive DNCVP and the transfection efficiency at the tumor site is greatly improved benefiting from the dynamic nature of noncovalent interactions. This study reveals DNCVP is a promising supramolecular dendritic gene delivery vector, providing a sophisticated strategy for precise gene therapy.

Carbosilane dendritic nanostructures, highly versatile platforms for pharmaceutical applications.

Dendrimers are multifunctional molecules with well-defined size and structure due to the step-by-step synthetic procedures required in their preparation. Dendritic constructs based on carbosilane scaffolds present carbon-carbon and carbon-silicon bonds, which results in stable, lipophilic, inert, and flexible structures. These properties are highly appreciated in different areas, including the pharmaceutical field, as they can increase the interaction with cell membranes and improve the therapeutic action. This article summarizes the most recent advances in the pharmaceutical applications of carbosilane dendritic molecules, from therapeutics to diagnostics and prevention tools. Dendrimers decorated with cationic, anionic, or other moieties, including metallodendrimers; supramolecular assemblies; dendronized nanoparticles and surfaces; as well as dendritic networks like hydrogels are described. The collected examples confirm the potential of carbosilane dendrimers and dendritic materials as antiviral or antibacterial agents; in therapy against cancer, neurodegenerative disease, or oxidative stress; or many other biomedical applications. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Amine-terminated dendritic polymers as promising nanoplatform for diagnostic and therapeutic agents' modification: A review.

It is often challenging to design diagnostic and therapeutic agents that fulfill all functional requirements. So, bulk and surface modifications as a common approach for biomedical applications have been suggested. There have been considerable research interests in using nanomaterials to the prementioned methods. Among all nanomaterials, dendritic materials with three-dimensional structures, host-guest properties, and nano-polymeric dimensions have received considerable attention. Amine-terminated dendritic structures including, polyamidoamine (PAMAM), polypropyleneimine (PPI), and polyethyleneimine (PEI), have been enormously utilized in bio-modification. This review briefly described the structure of these three common dendritic polymers and their use to modify diagnostic and therapeutic agents in six major applications, including drug delivery, gene delivery, biosensor, bioimaging, tissue engineering, and antimicrobial activity. The current review covers amine-terminated dendritic polymers toxicity challenging and improvement strategies as well.

A Model for Late-Stage Modification of Polyurethane Dendrimers Using Thiol-Ene Click Chemistry.

Dendritic materials possessing urethane linkage are surprisingly more stable than similar structures having functional groups such as ether, ester, amide, or carbosilane. This generates profound interest in dendritic polyurethanes. Construction of a well-defined polyurethane dendrimer is, however, challenging because of isocyanates’ high reactivity. As a model of our ongoing dendrimer-research, herein, we report a protecting group-free one-pot multicomponent Curtius reaction to furnish a robust and versatile AB2-type dendron, which ensures late-stage modification of both the dendron and dendritic macromolecule yielding a surface functionalized polyurethane dendrimer. While 5-hydroxyisophthalic acid, 11-bromoundecanol, and 4-penten-1-ol were utilized in the construction of the dendron, thiol–ene click chemistry was employed for the late-stage modification. Novel dendrons and dendrimers synthesized were characterized by NMR (1D and 2D) and high-resolution MALDI-TOF analysis. This strategy allows an easy late-stage modification of dendritic macromolecules and is highly useful in the synthesis of both symmetrical and unsymmetrical dendrimers (Janus dendrimers).

Boronate-Modified Polyethyleneimine Dendrimer as Solid-Phase Extraction Adsorbent for the Analysis of Luteolin in Peanut Shell Samples Via High Performance Liquid Chromatography

Dendritic macromolecules can increase the number of recognition sites in the material, and have adjustable function and biofriendly novel macromolecules. In this work, we synthesized Ag-modified boronate affinity polyethyleneimine (PEI) dendritic materials for the enrichment of luteolin (LTL). A thin layer of polydopamine (PDA) was formed to coat the matrix surface through self-polymerization to prepare PS@PDA. The PEI contained enough active amino groups, was grafted to the surface of PS@PDA, PS@PDA@PEI was then embedded with Ag by reducing AgNO 3 with NaBH 4 . Finally, the multi-boronic acid sites were post-modified onto PS@PDA@PEI-Ag via condensation reaction between the PEI and the 4-carboxyphenylboronic acid (CPBA) and obtained PPEI-Ag@CPBA. The adsorption conditions were optimized, the optimal pH and the optimum amount of adsorbent were determined, and the maximum adsorption capacity was 2.41 mg g -1 . This method has been successfully applied to the selective identification of LTL in peanut shell samples, and provides a practical platform for the detection of LTL in complex substrates.

Extended-release essential oils from poly(acrylonitrile) electrospun mats with dendritic materials

There is an increasing demand to use products based on essential oils (EOs) in many applications such as food packaging, drug delivery system, face-mask active layer, pharmaceutical, and cosmetic products. Despite their antibacterial activity, it is necessary to control the release of EOs because of their volatility. The synergetic encapsulation of EOs in dendritic polymers and electrospun fibres as embedding compounds was investigated in the present work. In situ solutions were used that consisted of 18 wt. % polyacrylonitrile polymer, 15 wt. % tea tree (TEO) or eucalyptus (EEO) essential oil, and various concentrations ranging from 10 to 20 wt. % of second and fourth generations of polyamidoamine dendritic compounds (PAMAM). The fibre diameters were analysed using scanning electron microscopy (SEM) revealing that the additions of TEO, PAMAM and simultaneous additions of the TEO/PAMAM in to the electrospun solution reduced the diameter from 899 ± 10 to 640 ± 14, 486 ± 10 nm, and 395 ± 5 nm, respectively. Furthermore, a novel temperature-modulated gas diagnosis device was applied to assess the amount of odour, in which a single chemo-resistor gas sensor functioned as an electronic nose (E-nose). This apparatus results indicate that adding PAMAM to the electrospinning solutions extends the TEO encapsulation time from 5 to 27 days. The antibacterial properties of the samples were examined against two commonly used bacteria (S. aureus and E. coli). In addition, the correlation between the odour intensity and antibacterial activity were measured by passing time. The results reveal that the antibacterial activity the EOs samples without PAMAM reduced by passing time, while the sample contacting PAMAM possessed a more durable antibacterial property. The E-nose results revealed that the PAMAM-encapsulated mats had extended releases of 6–23 days and 5–27 days for the TEO and eucalyptus, respectively. These antibacterial, scented nanofibrous mats as fragrant layer with extended release of EOs and also active biological characteristics might provide a new potential as bioactive layer for a broad spectrum of applications.

Engineering of dendritic dopant-free hole transport molecules: enabling ultrahigh fill factor in perovskite solar cells with optimized dendron construction

Developing dopant-free hole-transporting materials (HTMs) for high-performance perovskite solar cells (PVSCs) has been a very active research topic in recent years since HTMs play a critical role in optimizing interfacial charge carrier kinetics and in turn determining device performance. Here, a novel dendritic engineering strategy is first utilized to design HTMs with a D-A type molecular framework, and diphenylamine and/or carbazole is selected as the building block for constructing dendrons. All HTMs show good thermal stability and excellent film morphology, and the key optoelectronic properties could be fine-tuned by varying the dendron structure. Among them, MPA-Cz-BTI and MCz-Cz-BTI exhibit an improved interfacial contact with the perovskite active layer, and non-radiative recombination loss and charge transport loss can be effectively suppressed. Consequently, high power conversion efficiencies (PCEs) of 20.8% and 21.35% are achieved for MPA-Cz-BTI and MCz-Cz-BTI based devices, respectively, accompanied by excellent long-term storage stability. More encouragingly, ultrahigh fill factors of 85.2% and 83.5% are recorded for both devices, which are among the highest values reported to date. This work demonstrates the great potential of dendritic materials as a new type of dopant-free HTMs for high-performance PVSCs with excellent FF.

Morphometry of Dendritic Materials in Rechargeable Batteries

The formation of highly-branched dendrites during the charging period of the rechargeable batteries is a critical safety drawback, causing capacity decay in particular during utilization of high energy-density metallic elements as electrode. We develop a comparative framework for predicting the branching tendency of the conventional metallic candidates (Li,Na,Mg &Zn) in connection with their inherent material properties as well as representative spatial variants. Our framework covers the kinetic aspect of the electrodeposition, where the brownian motion leads to the formation randomly-branched microstructures. The ionic species are reduced in the proximity of the dendrite body and turn into the atom with the success probability derived from the electron transfer principles. Our development has been carried out in the atomic scale (∼Å) and the time interval of inter-ionic collisions (∼ps) and the determining sub-factors leading to branched evolution are analyzed separately. The results provide intuitive understanding for the effective utilization of the electrode materials in rechargeable batteries based on the given specific application, such as magnitude of the charge carriers, the applied current density or the thickness of the formed microstructures.

Dendrimers and Dendritic Materials: From Laboratory to Medical Practice in Infectious Diseases.

Infectious diseases are one of the main global public health risks, predominantly caused by viruses, bacteria, fungi, and parasites. The control of infections is founded on three main pillars: prevention, treatment, and diagnosis. However, the appearance of microbial resistance has challenged traditional strategies and demands new approaches. Dendrimers are a type of polymeric nanoparticles whose nanometric size, multivalency, biocompatibility, and structural perfection offer boundless possibilities in multiple biomedical applications. This review provides the reader a general overview about the uses of dendrimers and dendritic materials in the treatment, prevention, and diagnosis of highly prevalent infectious diseases, and their advantages compared to traditional approaches. Examples of dendrimers as antimicrobial agents per se, as nanocarriers of antimicrobial drugs, as well as their uses in gene transfection, in vaccines or as contrast agents in imaging assays are presented. Despite the need to address some challenges in order to be used in the clinic, dendritic materials appear as an innovative tool with a brilliant future ahead in the clinical management of infectious diseases and many other health issues.

Progress in the electrochemical reduction of CO2 on hierarchical dendritic metal electrodes

Abstract Electrochemical reduction of CO2 (ERC) is a promising way to deal with CO2 emissions in the atmosphere, recycle CO2, and achieve a carbon-neutral economy. Electrodes made of hierarchical dendritic materials are investigated for the ERC owing to their structural advantages, including large surface areas, presence of facets with low-coordinated atoms, and needle-like tips. Selected examples are presented to illustrate the state-of-the-art investigation of these dendritic electrodes. The mechanisms and the function of the dendritic structure are discussed, combined with a comparison of performance results of ERC.

Uncovering the nature of electroactive sites in nano architectured dendritic Bi for highly efficient CO2 electroreduction to formate

Porous electrodes based on Bismuth dendrites (Biden) were fabricated using Dynamic Hydrogen Bubbling Templates (DHBT). Direct visualization of surface-active sites with the help of advanced transmission electron microscopic (TEM) imaging reveals the presence of abundant defect structures and high-index faceting, while selective decoration of low-index facets of Bi dendrites indicate that they are the most active Bi surface sites. The fabricated electrodes show high selectivity toward CO2 electroreduction to formate synthesis, with a 98% Faradaic Efficiency and a current density of 18.8 mA cm−2 (344 μmol cm−2 h–1) at –0.82 V vs RHE, which is only 600 mV more negative than the thermodynamic potential. Both the dendritic structure and CO2 electrolysis performances are remarkably stable over long electrolysis periods (∼15 h). Additionally, large production rates (1.63 mmol cm−2 h–1 or 95 mA cm−2 at –0.82 V vs RHE) without significant penalty on the formate Faradaic Efficiency (92 ± 4%) was achieved in high-pressure flow cell, where the CO2 flux is greatly enhanced compare to an H-cell. The work thus outlines an effective strategy for the development of dendritic materials with superior performance toward electroreduction of CO2.

Advances in drug delivery, gene delivery and therapeutic agents based on dendritic materials.

Dendrimers are synthetic polymers that grow in three dimensions into well-defined structures. Their morphological appearance resembles a number of trees connected by a common point. Dendritic nanoparticles have been studied for a large number of pharmaceutical and biomedical applications including gene and drug delivery, clinical diagnosis and MRI. Despite the application of dendrimers, research is still in its childhood in comparison with liposomes and other nanomaterials. They are now playing a key role in several therapeutic strategies, with dendrimer-based products in clinical trials. The aim of this review is to describe the state-of-the-art of biomedical applications of dendrimers - and dendrimer conjugates - such as drug and gene delivery and antiviral activity.

Dendritic post-cross-linked resin for the adsorption of crystal violet from aqueous solution

Herein we adopted methyl acrylate (MA) as the functional monomer and divinylbenzene (DVB) as the cross-linking agent, and performed the polymerization, Friedel-Crafts reaction, ammonolysis reaction, and acylation reaction, and hence developed a kind of dendritic post-cross-linked resin namely HCPDTa. The results indicate that HCPDTa is a microporous and mesoporous material with the Brunauer-Emmett-Teller (BET) surface area (SBET) of 599 m2∙g−1 and pore volume (Vtotal) of 0.65 cm3∙g−1, respectively, and it contains considerable amido, amino, and carboxyl groups on the dendritic structure. HCPDTa is employed to adsorb crystal violet from aqueous solution and it reveals that HCPDTa is effective for the adsorption, the maximum adsorption capacity (qm) reaches 497.5 mg∙g−1 at 298 K, 40 min is sufficient for adsorption reaching equilibrium, and the resin can be regenerated easily and repeatedly used. The synthetic strategy in this study can provide a new idea for the synthesis of some other dendritic materials, and the developed dendritic post-cross-linked resins have potential application in adsorptive removal of organic dyes.

Preparation of long-lasting fragrant worsted fabrics using polypropylene-imine (PPI) dendrimer

Purpose The production of long-lasting fragrant semi-worsted fabrics using dendritic compounds as one of the nano size materials is concerned. Also quantitative assessments of the odour intensity of the fragrant fabrics using an electronic-nose (E-nose) are made. The paper aims to discuss these issues. Design/methodology/approach The semi-worsted fabrics were perfumed using the second generation of polypropylene-imine (PPI) dendrimer as a host molecules. The ginseng and rosewater fragrances as guest molecules were applied into the PPI dendrimer to produce long-lasting fragrant fabrics. The odour intensity as well as long-lasting properties of the fragrant fabrics perfumed recently and the other sample perfumed one year ago were evaluated via E-nose fabricated in our laboratory. Physical properties of the fragrant fabrics were compared to the non-fragrant ones. Findings The interaction between ginseng and rosewater fragrances with the second generation of PPI dendrimer into the semi-worsted fabrics made a long-lasting fragrant fabrics without considerable impacts on bending length, air permeability and wrinkle recovery angles based on statistical analysis. However, the effects of making fragrant fabrics on the increasing weight are significant. In addition, the E-nose was successfully used to monitor the release of ginseng and rosewater fragrance from the fabrics by the response patterns of a temperature-modulated chemo-resistive gas sensor. E-nose analysis showed that the aroma intensity released from the old fragrant semi-worsted fabrics has no obvious diversity from that of new fragrant fabrics. Originality/value The findings suggest that the semi-worsted fabrics perfumed with dendritic materials revealed excellent sustained release property.

Linear Dendritic Block Copolymers as Promising Biomaterials for the Manufacturing of Soft Tissue Adhesive Patches Using Visible Light Initiated Thiol–Ene Coupling Chemistry

A library of dendritic–linear–dendritic (DLD) materials comprising linear poly(ethylene glycol) and hyperbranched dendritic blocks based on 2,2‐bis(hydroxymethyl) propionic acid is successfully synthesized and postfunctionalized with peripheral allyl groups. Reactive DLDs with pseudo‐generations of 3 to 6 (G3‐G6) are isolated in large scale allowing their thorough evaluation as important components for the development of biomedical adhesives. Due to their branched nature and inherent degradable ester‐bonds, promising biomaterial resins are accomplished with suitable viscosity, eliminating the excessive use of co‐solvents. By utilizing benign high‐energy visible light initiated thiol–ene coupling chemistry, DLDs together with tris[2‐(3‐mercaptopropionyloxy)ethyl] isocyanurate and surgical mesh enable the fabrication of soft tissue adhesive patches (STAPs) within a total irradiation time of 30 s. The STAPs display the ability to create good adhesion to wet soft tissue and encouraging results in cytotoxicity tests. All crosslinked materials are also found to degrade after being stored in human blood plasma and phosphate buffered saline. The proposed benign methodology coupled with the promising features of the crosslinked materials is herein envisioned as a soft tissue adhesive with properties that do not exist in currently available tissue adhesives.

ChemInform Abstract: From 1 → 3 Dendritic Designs to Fractal Supramacromolecular Constructs: Understanding the Pathway to the Sierpinski gasket

AbstractReview: 76 refs.

Recent Advances in Solution‐Processable Dendrimers for Highly Efficient Phosphorescent Organic Light‐Emitting Diodes (PHOLEDs)

AbstractPhosphorescent dendrimers together with dendritic host materials have inherent advantages in achieving highly efficient phosphorescent organic light‐emitting diodes (PHOLEDs) with low‐cost, solution‐processed device fabrication. Recently, much research effort has been devoted to developing these dendritic materials in the field of electroluminescence (EL). In this Focus Review, the major advances in this line of research are summarized and discussed. The crucial roles played by these dendritic organic electronic materials in coping with the key issues in the field of PHOLEDs have been specially emphasized. These include alleviating the triplet‐triplet annihilation effect through the site‐isolation effect associated with the dendritic structures, promoting charge‐carrier injection/transporting ability and ambipolar properties through functionalized dendrons, fulfilling simple PHOLEDs with high EL efficiencies, obtaining self‐hosting phosphorescent emitters, and avoiding undesired energy transfer process from phosphorescent cores to the dendrons. In addition, the future perspectives and ongoing challenges of this research frontier are also highlighted.

From 1 → 3 dendritic designs to fractal supramacromolecular constructs: understanding the pathway to the Sierpiński gasket.

The iterative synthetic protocols used for dendrimer construction were developed based on the desire to easily craft highly branched macromolecules with ideally an exact mass and tailored functionality. Inspired by arboreal design and precursors of the utilitarian macromolecules known as dendrimers today, our first examples employed predesigned, 1 → 3 or 1 → (1 + 2) C-branched, building blocks. Physical characteristics of the dendrimers, including their globular shapes, excellent solubility, and demonstrated aggregation, revealed the inherent supramolecular potential. The architecture that is characteristic of dendritic materials also exhibits obvious fractal qualities based on self-similar, repetitive, branched frameworks. Thus, both the fractal design and supramolecular aspects of these constructs are suggestive of a larger field of fractal materials that incorporate repeating geometries and are derived by complementary building block recognition and assembly. Use of 〈terpyridine-M(2+)-terpyridine〉 connectivity for the sides and tuned directed organic vertices has opened the door to other types of novel materials. This approach also circumvents the nonideality of dendrimers, since the heteroleptic, one-step, spontaneous self-assembly process facilitates quantitative outcomes.