Dendrimers are new class of polymeric materials. It is generally described as a macromolecule, which is characterized by its extensively branched 3D structure that provides a high degree of surface ...functionality and versatility. The unique properties associated with these dendrimers such as uniform size, high degree of branching, water solubility, multivalency, well-defined molecular weight and available internal cavities make them attractive for biological and drug-delivery applications. Commercialization of dendrimers is now forthcoming. The present review briefly describes about dendrimer synthesis strategies, types of dendrimers with different functionalities, properties which having crucial importance and their potential applications.
This review presents an overview of 1→2 branched dendrimers and dendrons, created by a divergent procedure, from their synthesis to modern day applications. The first members of this branched class ...of fractal macromolecules were prepared through a cascade synthesis, which was later replaced by the iterative divergent synthetic approach. Most classes of this 1→2 N-, Aryl-, C-, Si-, and P-branched families are included and catalogued by their mode of connectivity. Dendritic macromolecules have had significant impact in the field of material sciences and are one of the major starting points for nanotechnology as a result of the numerous modifications that can be conducted, either on the surface or within their molecular infrastructure, thus taking advantage of their unimolecular micelle properties. These host cavities, maintained by the dendritic branches, allow for the incorporation of nanoparticles as well as metal particles, which make these attractive in catalysis and imaging studies. The solubility of these fractal constructs can be tailored depending on their surface modifications. Highly water-soluble, neutral dendrimers appended with, grown from, or acting as hosts to specific molecules give rise to a wide variety of biomedical applications such as drug delivery systems and MRI imaging agents. The inherent supramolecular or supramacromolecular chemistry has been exploited but the design and construction of uniquely tailored macrostructures have just begun. Laser dyes, as well as electron and energy donor and acceptor functionality, have also been paired with these fractal constructs in order to probe their uses in the field of molecular electronics. With their synthetic control, seemingly limitless modifications and wide variety of potential applications, as well as their now commercial availability, these 1→2 branched dendrimers have become an important nanostructured tools for diverse utilitarian applications. This review mainly covers 1→2 branched non-chiral dendrimers prepared by a divergent process but selected chiral surfaces are considered as well as metal encapsulation and a few hyperbranched routes to related imperfect dendrimers.
In this study, we aimed to develop a polyethylene glycol (PEG)-conjugated third generation polyamidoamine (PAMAM) dendrimer with multiple carboxylic acids as a bone-targeting carrier for the ...treatment of bone diseases. We conjugated PAMAM backbones to various carboxylic acids aspartic acid (Asp), glutamic acid (Glu), succinic acid (Suc), or aconitic acid (Aco) to obtain four different types of carboxylic acid-modified PAMAMs. PEG was covalently bound to carboxylic acid-modified PAMAMs to obtain PEGylated carboxylic acid-modified PAMAMs. In a tissue distribution study, the amount of 111In-labeled unmodified PAMAM taken up by the bone after intravenous injection in mice was 11.3%. In contrast, the dose of 111In-labeled PEG(5)-Asp-PAMAM, PEG(5)-Glu-PAMAM, PEG(5)-Suc-PAMAM, or PEG(5)-Aco-PAMAM that accumulated in the bone after injection was approximately 46.0, 15.6, 22.6, and 24.5%, respectively. The bone clearance rates of 111In-labeled PEGylated carboxylic acid-modified PAMAMs were proportional to their affinities to hydroxyapatite and Ca2+. An intra-bone distribution study showed that fluorescein isothiocyanate-labeled PEG(5)-Asp-PAMAM predominantly accumulated on eroded and quiescent surfaces, a pattern associated with the pathogenesis of bone diseases, such as rheumatoid arthritis and osteoporosis. Our findings indicate that PEG(5)-Asp-PAMAM is a promising drug carrier for efficient drug targeting to the bones.
Efficient bone targeting by a polyamidoamine (PAMAM) dendrimer was successfully achieved by carboxylic acids. A combination of Asp and PEG modifications represented an optimal approach for effective bone targeting. Display omitted
The formation of particulate systems with well-defined sizes and shapes is of eminent interest in certain medical applications such as drug delivery, gene transfection, and imaging. The high level of ...control possible over the architectural design of dendrimers; their size, shape, branching length/density, and their surface functionality, clearly distinguishes these structures as unique and optimum carriers in those applications. The bioactive agents may be encapsulated into the interior of the dendrimers or chemically attached/physically adsorbed onto the dendrimer surface, with the option of tailoring the carrier to the specific needs of the active material and its therapeutic applications. In this regard, the high density of exo-presented surface groups allows attachment of targeting groups or functionality that may modify the solution behavior or toxicity of dendrimers. Quite remarkably, modified dendrimers have been shown to act as nano-drugs against tumors, bacteria, and viruses. Recent successes in simplifying and optimizing the synthesis of dendrimers such as the ‘lego’ and ‘click’ approaches, provide a large variety of structures while at the same time reducing the cost of their production. The reflections on biomedical applications of dendrimers given in this review clearly demonstrate the potential of this new fourth major class of polymer architecture and indeed substantiate the high hopes for the future of dendrimers.
An amphiphilic dendrimer bearing a hydrophobic alkyl chain and hydrophilic poly(amidoamine) dendrons is able to combine the advantageous features of lipid and dendrimer vectors to deliver a heat ...shock protein 27 siRNA and produce potent gene silencing and anticancer activity in vitro and in vivo in a prostate cancer model (see picture). This dendrimer can be used alternatively for treating various diseases.
Multidrug‐resistant opportunistic bacteria, such as Pseudomonas aeruginosa, represent a major public health threat. Antimicrobial peptides (AMPs) and related peptidomimetic systems offer an ...attractive opportunity to control these pathogens. AMP dendrimers (AMPDs) with high activity against multidrug‐resistant clinical isolates of P. aeruginosa and Acinetobacter baumannii were now identified by a systematic survey of the peptide sequences within the branches of a distinct type of third‐generation peptide dendrimers. Combined topology and peptide sequence design as illustrated here represents a new and general strategy to discover new antimicrobial agents to fight multidrug‐resistant bacterial pathogens.
Multidrug‐resistant bacteria, such as Pseudomonas aeruginosa and Acinetobacter baumannii, are a major public health threat. By combining topology and amino acid sequence design, new antimicrobial peptide dendrimers with high activity against these pathogens were found, which represents a new and general approach for the discovery of antimicrobial agents.
Dendrimers are emerging class of nanoparticles used in targeted drug delivery systems. These are radially symmetric molecules with well-defined, homogeneous, and monodisperse structures. Due to the ...nano size, they can easily cross the biological membrane and increase bioavailability. The surface functionalization facilitates targeting of the particular site of action, assists the high drug loading and improves the therapeutic efficiency of the drug. These properties make dendrimers advantageous over conventional drug delivery systems. This article explains the features of dendrimers along with their method of synthesis, such as divergent growth method, convergent growth method, double exponential and mixed method, hyper-core and branched method. Dendrimers are effectively used in anticancer delivery and can be targeted at the site of tumor either by active or passive targeting. There are three mechanisms by which drugs interact with dendrimers, and they are physical encapsulation, electrostatic interaction, chemical conjugation of drug molecules. Drug releases from dendrimer either by in vivo cleavage of the covalent bond between drugdendrimer complexes or by physical changes or stimulus like pH, temperature, etc.
•Silica gel supported salicylaldehyde modified PAMAM dendrimers were synthesized.•SiO2-G0-SA∼SiO2-G2.0-SA were promising adsorbents for the removal of Hg(II).•The pseudo-second-order model described ...adequately the adsorption kinetics data.•The film diffusion mechanism dominated the adsorption processes of Hg(II).•Langmuir model provide best correlation of the experimental data.
A series of silica gel supported salicylaldehyde modified PAMAM dendrimers (SiO2-G0-SA∼SiO2-G2.0-SA) were synthesized and their structures were characterized by FTIR, XRD, SEM, TGA, and porous structure analysis. The feasibility of these adsorbents for the removal of Hg(II) from aqueous solution was first described and the adsorption mechanism was proposed. The adsorption was found to depend on solution pH, the generation number of salicylaldehyde modified PAMAM dendrimers, contact time, temperature, and initial concentration. Results showed that the optimal pH was about 6 and the adsorption capacity increased with the increasing of generation number. Density functional theory (DFT) method was used to investigate the coordination geometries and the chelating mechanism. Adsorption kinetics was found to follow the pseudo-second-order model with film diffusion process as rate controlling step. Adsorption isotherms revealed that adsorption capacities increased with the increasing of temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models were employed to analyze the equilibrium data. The adsorption can be well described by Langmuir isotherm model and took place by chemical mechanism. The thermodynamics properties indicated the adsorption processes were spontaneous and endothermic nature. The maximum adsorption capacity of SiO2-G0-SA, SiO2-G1.0-SA, and SiO2-G2.0-SA were 0.91, 1.52, and 1.81mmolg−1, respectively. The considerable higher adsorption capacity compared with other adsorbents indicates SiO2-G0-SA∼SiO2-G2.0-SA are favorable and useful for the uptake of Hg (II), and can be potentially used as promising adsorbents for the effective removal of Hg(II) from aqueous solution.
Advances in Light‐Emitting Dendrimers Abd‐El‐Aziz, Alaa S.; Abdelghani, Amani A.; Wagner, Brian D. ...
Macromolecular rapid communications.,
January 2019, Letnik:
40, Številka:
1
Journal Article
Recenzirano
The design of dendrimers with various chromophores has attracted significant attention in light of the dual effect of the luminescence of the chromophores and the morphology of the synthesized ...dendrimers. Recent developments in this field stem from their wide potential applications, including organic light‐emitting diodes, photonic switches and upconversion lasers, as well as sensors and electronic devices. The focus of this comprehensive review is on the design and properties of various classes of light‐harvesting dendrimeric materials.
A tremendous increase in research in the field of light‐emitting dendrimers has emerged in the past few decades. There are many representative examples where dendrimers have become the architecture of choice for the design of light‐harvesting antenna, two photon upconversion systems, fluorescent sensors, photoinduced electron‐transfer‐based electronic devices, aggregation‐induced emission systems, and other functional materials.
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Drug delivery systems or vectors are usually needed to improve the bioavailability and effectiveness of a drug through improving its pharmacokinetics/pharmacodynamics at an organ, ...tissue or cellular level. However, emerging technologies with sensitive readouts as well as a greater understanding of physiological/biological systems have revealed that polymeric drug delivery systems are not biologically inert but can have innate or intrinsic biological actions. In this article, we review the emerging multiple innate biological/toxicological properties of naked polyamidoamine (PAMAM) dendrimer delivery systems in the absence of any drug cargo and discuss their correlation with the defined physicochemical properties of PAMAMs in terms of molecular size (generation), architecture, surface charge and chemistry. Further, we assess whether any of the reported intrinsic biological actions of PAMAMs such as their antimicrobial activity or their ability to sequester glucose and modulate key protein interactions or cell signaling pathways, can be exploited clinically such as in the treatment of diabetes and its complications.
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