A modular strategy for hydrogel formation based on the self‐organization of well‐defined ABA triblock copolyelectrolytes through ionic interactions in water is reported. The nature of the ionic domains, which constitute the physical crosslinks, provides for robust, yet highly tunable materials. These materials represent a diverse platform for hydrogel formation with enhanced mechanical properties and ease of synthesis while retaining a dynamic responsive nature.

Unsymmetrical dendrimers, containing both mannose binding units and coumarin fluorescent units, have been prepared using click chemistry and shown to be highly efficient, dual-purpose recognition/detection agents for the inhibition of hemagglutination.

The synthesis of core-shell star copolymers via living free radical polymerization provides a convenient route to three-dimensional nanostructures having a poly(ethylene glycol) outer shell, a hydrophilic inner shell bearing reactive functional groups, and a central hydrophobic core. By starting with well-defined linear diblock copolymers, the thickness of each layer, overall size/molecular weight, and the number of internal reactive functional groups can be controlled accurately, permitting detailed structure/performance information to be obtained. Functionalization of these polymeric nanoparticles with a DOTA-ligand capable of chelating radioactive 64 Cu nuclei enabled the biodistribution and in vivo positron emission tomography (PET) imaging of these materials to be studied and correlated directly to the initial structure. Results indicate that nanoparticles with increasing PEG shell thickness show increased blood circulation and low accumulation in excretory organs, suggesting application as in vivo carriers for imaging, targeting, and therapeutic groups.

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A simple synthetic strategy has been developed for accessing internally functionalized dendrimers. The key feature of this approach is the use of two orthogonal and efficient reactions--'epoxy-amine' and 'thiol-ene' coupling--for rapid growth of the dendritic scaffold. This sequence of reactions allows for the introduction of reactive hydroxyl groups at each dendritic layer.

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Dendrimers O 0450 Multivalent, Bifunctional Dendrimers Prepared by Click Chemistry -[containing mannose binding units and coumarin fluorescent units]. -(WU, P.; MALKOCH, M.; HUNT, J. N.; VESTBERG, R.; KALTGRAD, E.; FINN*, M. G.; FOKIN, V. V.; SHARPLESS*, K. B.; HAWKER, C. J.; Chem. Commun. (Cambridge) 2005, 46, 5775-5777; Dep. Chem., Scripps Res. Inst.,

Craig Hawker, Ed Kramer, and co‐workers report on a modular strategy for hydrogel formation based on the self‐organization of welldefined ABA triblock co‐polyelectrolytes through ionic interactions in water. The nature of the ionic domains, which constitute the physical crosslinks, provides for robust, yet highly tunable materials. These materials represent a diverse platform for hydrogel formation with enhanced mechanical properties and ease of synthesis while retaining a dynamic responsive nature.