Dendrimer as a versatile platform for biomedical application: A review

Modern chemistry is vastly fascinated by dendrimer chemistry, an area that is rapidly expanding and brimming with potential applications. Dendrimers are highly branched polymers that have multiple peripheral groups, interior cavities and they have many structural properties therefore Dendrimers play a crucial role in the fields of nanotechnology, pharmaceuticals, and medicinal chemistry. The terminal functional groups of dendrimers may be chemically linked to other moieties in order to adjust surface properties for applications such as biomimetic nanodevices. A variety of biologically active agents can be incorporated into dendrimers to create biologically active conjugates, including novel drug carriers, by utilizing the homogeneity of their three-dimensional architecture. The purpose of this review is to provide a brief overview of bio-inspired dendrimer applications, highlighting their use as drug and gene delivery agents, and biomedical diagnostic agents. In addition, the review mentions briefly some dendrimer applications in cosmetics, agrochemicals, and catalyst.     

Simplifying the synthesis of dendrimers: accelerated approaches

Dendrimers are highly branched and monodisperse macromolecules that display an exact and large number of functional groups distributed with unprecedented control on the dendritic framework. Based on their globular structure, compared to linear polymers of the same molecular weight, dendrimers are foreseen to deliver extraordinary features for applications in areas such as cancer therapy, biosensors for diagnostics and light harvesting scaffolds. Of the large number of reports on dendrimer synthesis only a few have reached commercial availability. This limitation can be traced back to challenges in the synthetic paths including a large number of reaction steps required to obtain dendritic structures with desired features. Along with an increased number of reaction steps come not only increased waste of chemical and valuable starting materials but also an increased probability to introduce structural defects in the dendritic framework. This tutorial review briefly covers traditional growth approaches to dendrimers and mainly highlights accelerated approaches to dendrimers. A special focus capitalizes on the impact of the click chemistry concept on dendrimer synthesis and the promise it has to successfully accomplish highly sophisticated dendrimers, both traditional as well as heterofunctional, in a minimum number of chemical steps. It is clear that accelerated synthetic approaches are of greatest importance as these will encourage the scientific community to synthesize and access dendrimers for specific applications. The final goal of accelerated synthesis is to deliver economically justified dendritic materials for future applications without compromising the environmental perspective.     

Editorial

This review details the combination of supramolecular chemistry and dendrimer chemistry. The use of supramolecular chemistry in the synthesis and modification of dendrimers, along with the application of dendrimers in supramolecular chemistry, is described. Many excellent examples exist within these areas; this review includes key examples intended to illustrate the main principles involved, and demonstrate the large number of possibilities presented through combining supramolecular and dendrimer chemistry.     

Small-molecule analysis by surface-assisted laser desorption/ionization mass spectrometry

In order to meet the challenges facing modern chemistry, biology, and medicine, methods are required capable of performing rapid and reliable analysis of both individual compounds and complex mixtures at the molecular level. Matrix-assisted laser de-sorption/ionization mass spectrometry meets these requirements; however, some limitations complicate its application for the analysis of small molecules. Recently, small-molecule analysis has greatly progressed owing to development of surface-assisted laser desorption/ionization mass spectrometry involving approaches which combine the unique properties of nanostructured surface chemistry and morphology. This review examines such approaches and their specific application in small-molecule mass analysis.     

The power of thiol‐ene chemistry

As a tribute to Professor Charlie Hoyle, we take the opportunity to review the impact of thiol‐ene chemistry on polymer and materials science over the past 5 years. During this time, a renaissance in thiol‐ene chemistry has occurred with recent progress demonstrating its unique advantages when compared with traditional coupling and functionalization strategies. Additionally, the robust nature of thiol‐ene chemistry allows for the preparation of well‐defined materials with few structural limitations and synthetic requirements. To illustrate these features, the utility of thiol‐ene reactions for network formation, polymer functionalization, dendrimer synthesis, and the decoration of three‐dimensional objects is discussed. Also, the development of the closely related thiol‐yne chemistry is described. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 743–750, 2010     

含有杯芳烃的树枝状分子

杯芳烃与树枝状大分子是超分子化学中两类极为重要的主体分子,将这两种主体分子结合在一起所得到的基于杯芳烃的树枝状大分子,不仅仅能够将两者的优点集中到一个分子之中,同时还有可能产生一些新颖的性能,成为新型的智能材料、分子器件或是纳米材料。本文按照杯芳烃的类型,在树枝状大分子中的位置,综述了到目前为止有关这一新型主体分子的研究成果,展望了它在将来的发展。     

Functionalizing the interior of dendrimers: Synthetic challenges and applications

Chemists' fascination with dendrimers mainly originates from their unique architecture and its exploitation for the design of well‐defined functional macromolecules. Depending on the nature of the synthesis, functionalization is traditionally introduced at the core, the periphery, or both. However, the specific incorporation of functional groups at the interior layers, i.e., generations, represents a considerable synthetic hurdle that must be overcome for the full potential of dendrimers to be realized. This review covers recent advances in this emerging frontier of dendrimer science with a particular focus on covalent modifications. Monomer design, syntheses, and properties of various dendritic backbone types are discussed. Internal functionalization dramatically increases the degree of complexity that can be implemented into a dendrimer macromolecule and, therefore, promises to lead to smart materials for future applications in bio‐ and nanotechnologies. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1047–1058, 2003     

Nanoscopic supermolecules with linear-dendritic architecture: Their preparation and their supramolecular behavior

The design, synthesis, and properties of supermolecules consisting of well defined assemblies of linear and globular macromolecules is studied. Therefore, several families of hybrid block polymers based on polyether dendrimers linked to well-defined blocks of polyethylene oxide, polyethylene glycol, polyester, or polystyrene have been prepared. The unique topological macromolecules that result from the assembly of such components having different shapes and internal densities can assemble in highly stable supramolecular micelles whose characteristics vary as a function of the medium. The hybrid macromolecules are usually prepared by the nucleophilic displacement of a reactive functionality located at the focal point of a convergent polyether dendrimer, with a nucleophilic anion located at one or both chain ends of a linear polymer. Alternately, the focal point of the dendrimer may be used to attach a polymerizable vinyl group affording a dendritic macromonomer that may be used to create variety of copolymers. Finally, the focal point of the convergent dendrimer may serve as an initiator in the polymerization of a linear chain thereby affording the hybrid linear-dendritic entity. In the latter case the unique microenvironment provided by the dendrimer is useful in the prevention of undesirable side-reactions during growth of the linear block. This demonstrates that the differences between the globular and linear fragments of these unique molecules can be used to design nanoscale reactors that perform functions not normally achieved with small molecules. The very unusual solution properties of the dendritic-linear supermolecules are a direct result of the forced combination of their dissimilar building blocks.     

Starburst pamam dendrimers: Synthetic approaches,surface modifications,and biomedical applications

Dendrimers are having novel three dimensional, synthetic hyperbranched, nano-polymeric structure. Among all of the dendrimers, Poly-amidoamine (PAMAM) dendrimer are used enormously applying materials in supramolecular chemistry. This review described the structure, characteristic, synthesis, toxicity, and surface modification of PAMAM dendrimer. Various strategies in supramolecular chemistry of PAMAM for synthesizing it at commercial and laboratory scales along with their limitations and applications has also discussed. When compared to other nano polymers, the characteristics of supramolecular PAMAM dendrimers in nanopolymer science has shown significant achievement in transporting drugs for molecular targeted therapy, particularly in host–guest reaction. It also finds its applications in gene transfer devices and imaging of biological systems with minimum cytotoxicity. From that viewpoint, this review has elaborated the structural and safety aspect of PAMAM for targeted drug delivery with pharmaceuticals in addition to the biomedical application.     

Inverse quantum chemistry: Concepts and strategies for rational compound design

The rational design of molecules and materials is becoming more and more important. With the advent of powerful computer systems and sophisticated algorithms, quantum chemistry plays a decisive role in the design process. While traditional quantum chemical approaches predict the properties of a predefined molecular structure, the goal of inverse quantum chemistry is to find a structure featuring one or more desired properties. Herein, we review inverse quantum chemical approaches proposed so far and discuss their advantages as well as their weaknesses. © 2014 Wiley Periodicals, Inc.     

树状大分子在有机合成中的应用

近20年来树状大分子由于其特殊的结构而引起了科学家们的广泛关注;作为一类新型的高负载量载体应用于有机合成和催化是树状大分子重要的应用领域之一。本文主要介绍树状大分子和树脂固载树状大分子两类载体,重点对它们作为高负载量载体在有机合成和非均相催化反应中的应用研究进行了总结。     

树状大分子在有机合成中的应用

近20年来树状大分子由于其特殊的结构而引起了科学家们的广泛关注;作为一类新型的高负载量载体应用于有机合成和催化是树状大分子重要的应用领域之一。本文主要介绍树状大分子和树脂固载树状大分子两类载体,重点对它们作为高负载量载体在有机合成和非均相催化反应中的应用研究进行了总结。     

PAMAM Dendrimer‐Based Nanodevices for Nuclear Medicine Applications

Nuclear medicine, involving nuclear medicine imaging and radiotherapy (RT), has become a mainstay of theranostics in the field of nanomedicine and several examples have been successfully translated into clinical practice. The combination of radionuclides with dendrimers has long been investigated in nuclear imaging, such as positron emission tomography (PET) and single‐photon emission computed tomography (SPECT), providing functional information for whole body quantitative analysis with high sensitivity due to the unique structural advantages of the dendrimer platform. Besides, radioisotopes with both therapeutic and imaging functionalities can also be combined with dendrimer platforms for theranostic applications. In this review, the recent advances in the development of radionuclide‐labeled poly(amidoamine) dendrimer‐based nanodevices for targeted PET, SPECT, SPECT/computed tomography, SPECT/magnetic resonance imaging of tumors, RT, as well as for SPECT‐imaging‐guided RT of cancer are summarized. Current restrictions hindering the clinical translation of dendrimer‐based nuclear nanodevices and future prospects are also discussed.     

Three-dimensional solution NMR spectroscopy of complex structures and mixtures

This paper reviews the non-biological applications of three dimensional NMR (3D-NMR) spectroscopy methodologies for studying chemical structures in polymer science, dendrimer research, organometallic chemistry, organosilicon chemistry, and mixtures of small organic molecules. Four methodologies for solving chemical structure problems are described, where the appropriate method is determined by the presence or absence of a third X nucleus (in addition to (1)H and (13)C) with suitable NMR properties.     

Recent Advances in Imidazoliumyl‐Substituted Phosphorus Compounds

This review aims to highlight the recent developments in the chemistry of selected imidazoliumyl‐substituted phosphorus compounds. The synthetic approaches for their preparation with phosphorus in various oxidation states and coordination environments are discussed. Their intriguing properties and versatile chemistry strongly depends on the bonding motif at the P atoms, which is given special focus.     

Organometallic Ionic Liquids Containing Sandwich Complexes: Molecular Design,Physical Properties,and Chemical Reactivities

Ionic liquids (ILs) are salts with low melting points and are useful as electrolytes and solvents. We have developed ILs containing cationic metal complexes, which form a family of functional liquids that exhibit unique physical properties and chemical reactivities originating from metal complexes. Our study explores the liquid chemistry in the field of coordination chemistry, where solid-state chemistry is currently the main focus. This review describes the molecular design, physical properties, and reactivities of organometallic ILs containing sandwich or half-sandwich complexes. This paper mainly covers stimuli-responsive ILs, whose magnetic properties, solvent polarities, colors, or structures change by the application of external fields, such as light, heat, and magnetic fields, or by reaction with coordinating molecules.     

树状多肽的合成及应用

树状多肽作为树枝状大分子的一种,具有不同于链状多肽的独特理化特性,在生物学领域中具有广泛的应用.本文简要综述了树状多肽的合成方法,及其在诱导免疫反应、生物分子模拟、免疫诊断试剂、人工酶、药物及基因载体等方面的应用.     

Classical and interdisciplinary approaches to the design of organic and hybrid molecular systems

This review summarizes the recent advances in the construction of organic and hybrid systems having considerable potential for practical applications in pharmacology, medicine, materials science, petrochemistry, and chemistry of high-energy compounds. The methodological classification of the approaches into classical and interdisciplinary is proposed. Examples of the efficient application of these approaches for investigating complex molecular systems, as well as for developing new methods of synthesis are given.     

Dendrimer building toolkit: Model building and characterization of various dendrimer architectures

We have developed a graphical user interface based dendrimer builder toolkit (DBT) which can be used to generate the dendrimer configuration of desired generation for various dendrimer architectures. The validation of structures generated by this tool was carried out by studying the structural properties of two well known classes of dendrimers: ethylenediamine cored poly(amidoamine) (PAMAM) dendrimer, diaminobutyl cored poly(propylene imine) (PPI) dendrimer. Using full atomistic molecular dynamics (MD) simulation we have calculated the radius of gyration, shape tensor and monomer density distribution for PAMAM and PPI dendrimer at neutral and high pH. A good agreement between the available simulation and experimental (small angle X‐ray and neutron scattering; SAXS, SANS) results and calculated radius of gyration was observed. With this validation we have used DBT to build another new class of nitrogen cored poly(propyl ether imine) dendrimer and study it's structural features using all atomistic MD simulation. DBT is a versatile tool and can be easily used to generate other dendrimer structures with different chemistry and topology. The use of general amber force field to describe the intra‐molecular interactions allows us to integrate this tool easily with the widely used molecular dynamics software AMBER. This makes our tool a very useful utility which can help to facilitate the study of dendrimer interaction with nucleic acids, protein and lipid bilayer for various biological applications. © 2012 Wiley Periodicals, Inc.     

Phosphonates,their complexes and bio-applications: A spectrum of surprising diversity

This review provides a summary of the coordination chemistry of mono-, bis- and polyphosphonates, as well as of their functionalized analogues. Specific interactions with various metal ions will be discussed in the context of their biological, biomedical and nanotechnological applications. Several complexes will be shown to reveal a spectacular spectrum of possibilities, which the phosphonate moiety gives to coordination chemistry.We would like to show a link between coordination properties and unique functionality of particular phosphonate complexes which were developed and successfully applied in different branches of biological science.