Hyperbranched polymers: from synthesis to applications

Polymer surface modification for the attachment of bioactive compounds

Crown ethers: sensors for ions and molecular scaffolds for materials and biological models.

Dendrimers are versatile, derivatisable, well-defined, compartmentalised chemical polymers with sizes and physicochemical properties resembling those of biomolecules e.g. proteins. The present critical review (citing 158 references) briefly describes dendrimer design, nomenclature and divergent/convergent dendrimer synthesis. The characteristic physicochemical features of dendrimers are highlighted, showing the effect of solvent pH and polarity on their spatial structure. The use of dendrimers in biological systems are reviewed, with emphasis on the biocompatibility of dendrimers, such as in vitro and in vivo cytotoxicity, as well as biopermeability, biostability and immunogenicity. The review deals with numerous applications of dendrimers as tools for efficient multivalent presentation of biological ligands in biospecific recognition, inhibition and targeting.
 Dendrimers may be used as drugs for antibacterial and antiviral treatment and have found use as antitumor agents. The review highlights the use of dendrimers as drug or gene delivery devices in e.g. anticancer therapy, and the design of different host–guest binding motifs directed towards medical applications is described.
 Other specific examples are the use of dendrimers as ‘glycocarriers’ for the controlled multimeric presentation of biologically relevant carbohydrate moieties which are useful for targeting modified tissue in malignant diseases for diagnostic and therapeutic purposes. Finally, the use of specific types of dendrimers as scaffolds for presenting vaccine antigens, especially peptides, for use in vaccines is presented.

Dendrimers in drug research

Dendron-mediated self-assembly, disassembly, and self-organization of complex systems have been investigated. The most ideal building blocks would need to display shape persistence in solution and in the solid state, since only this feature provides access to the use of complementary methods of structural analysis. Most supramolecular dendrimers are chiral even when they are constructed from nonchiral building blocks and are equipped with mechanisms that amplify chirality. This poses additional challenges associated with the understanding of the structural origin of chirality in different supramolecular structures through combinations of structural analysis methods. While many supramolecular structures assembled from dendrimers and dendrons resemble some of the related morphologies generated from block-copolymers, they are much more complex and are not determined by the volume ratio between the dissimilar parts of the molecule.

Dendron-Mediated Self-Assembly, Disassembly, and Self-Organization of Complex Systems

Dendrimer chemistry is one of the most fascinating and rapidly expanding areas of modern chemistry. This review attempts to uncover the appeal of these structurally-perfect branched macromolecules. The three intriguing regions of a dendritic molecule are discussed: the multifunctional surface, the tailored sanctuary within the branches, and the encapsulated core. The advantages of dendritic structures for property modification, and their potential applications in very diverse areas are illustrated. The exciting merger of dendrimer chemistry with self-assembly offers new, stimulating avenues for exploration. Consequently, self-assembling dendrimers comprise a major section of this article.

© 2001 Society of Chemical Industry

Dendrimers: a review of their appeal and applications

Supramolecular dendritic two-component gel

Supramolecular dendrimer chemistry: using dendritic crown ethers to reversibly generate functional assemblies

Individual dendritic branches can solubilise hydrophilic dyes in apolar media. The functional group at the focal point of the dendritic branch plays a key role in the dye uptake process. Supramolecular interactions between carboxylic acid and amine groups have been shown to be effective in enabling efficient solubilisation to occur. The necessary complementarity of this interaction is further illustrated by a series of control experiments. The extent of dendritic branching (i.e. dendritic generation) plays a key role in controlling the extent of dye uptake, with higher-generation dendritic branches exhibiting more efficient uptake at lower concentrations. UV/Visible spectroscopic methods have shown that the dendritic branches, in addition to the tuning of the extent of dye uptake, also tune the optical properties of the solubilised dye and this provides further insight into the interactions occurring between the solubilised dye and the individual dendritic branches. Furthermore, it is shown that suitably functionalised dendritic branches can transport hydrophilic dyes through an apolar phase and deliver them continuously into an aqueous medium.

Graham M. Dykes

Papers

Dendrimers: a review of their appeal and applications

Supramolecular dendritic two-component gel

Supramolecular dendrimer chemistry: using dendritic crown ethers to reversibly generate functional assemblies

Supramolecular solubilisation of hydrophilic dyes by using individual dendritic branches

Controlled release of a dendritically encapsulated template molecule.