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Anisotropic gold nanoparticles (AuNPs) have attracted the interest of scientists for over a century, but research in this field has considerably accelerated since 2000 with the synthesis of numerous 1D, 2D, and 3D shapes as well as hollow AuNP structures. The anisotropy of these nonspherical, hollow, and nanoshell AuNP structures is the source of the plasmon absorption in the visible region as well as in the near-infrared (NIR) region. This NIR absorption is especially sensitive to the AuNP shape and medium and can be shifted towards the part of the NIR region in which living tissue shows minimum absorption. This has led to crucial applications in medical diagnostics and therapy ("theranostics"), especially with Au nanoshells, nanorods, hollow nanospheres, and nanocubes. In addition, Au nanowires (AuNWs) can be synthesized with longitudinal dimensions of several tens of micrometers and can serve as plasmon waveguides for sophisticated optical devices. The application of anisotropic AuNPs has rapidly spread to optical, biomedical, and catalytic areas. In this Review, a brief historical survey is given, followed by a summary of the synthetic modes, variety of shapes, applications, and toxicity issues of this fast-growing class of nanomaterials.

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Two new water-soluble 1,2,3-triazole-containing nona-PEG-branched dendrimers are obtained with nine intradendritic 1,2,3-triazoles (trz). Addition of HAuCl4 in water to these dendrimers quantitatively leads to the intradendritic formation of AuCl3(trz) moieties subsequent to complete Cl(-) substitution by trz on Au(III), whereas the analogous complexation reaction of AuCl3 with a linear PEG trz ligand forms only an equilibrium between trz-coordinated Au(III) and Au(III) that is not coordinated to trz. Reduction of the dendrimer-Au(III) complexes to Au(0) by NaBH4 then leads to stabilization of gold nanoparticles (AuNPs) in water. The sizes of the AuNPs stabilized by the dendritic macromolecules are further controlled between 1.8 and 12 nm upon selecting the stoichiometry of Au(III) addition per dendritic trz followed by NaBH4 reduction. With a 1:1 Au/trz stoichiometry, the AuNP size depends on the length of the PEG tether of the dendrimer; small dendrimer-encapsulated AuNPs are formed with PEG2000, whereas large AuNPs are formed with PEG550. With Au/trz stoichiometries larger than unity, Au(III) is reduced outside the macromolecule, resulting in the formation of large interdendritically stabilized AuNPs. The formation of very small and only mildly stabilized AuNPs by neutral hydrophilic triazole ligands offers an opportunity for very efficient p-nitrophenol reduction by NaBH4 in water at the AuNP surface.

New therapeutics for glioblastoma multiforme and our ability to deliver them using efficient nanocarriers constitute topical areas of research. We report a comparative study of temozolomide and quercetin in the treatment of glioblastoma (GBM) in three-dimensions, and their incorporation into micelles obtained from synthetically articulated architectural copolymers, and a commercially available linear polymer poly(ethylene glycol)-poly(lactic-co-glycolic acid) (PEG-PLGA). A versatile synthetic methodology to telodendrimers, which can be easily adapted to the needs of other therapeutic interventions, is presented. These dendritic block copolymers self-assemble into micelles and offer a platform for single or combination drug therapy. Telodendrimer micelles loaded with quercetin did not exhibit superior cell killing effect over the free drug, but acetazolamide, an inhibitor carbonic anhydrase IX, significantly reduced GBM cell viability in 3D spheroids. Results from these studies show that high loading of drugs into telodendrimer micelles requires a physical fit between the biologically active agent and telodendrimer nanocarrier, and points toward new possibilities for incorporation of chemotherapeutic and other agents to enhance their effectiveness.

Macromolecules provide unique opportunities to inhibit scaling, a complex problem and a key challenge faced by water-based industries.

We report an efficient synthesis of glycerol dendrimers via thiol–yne chemistry for stabilization of AuNPs with X-ray attenuation properties.

We have engineered the molecular structure of dendrimers/dendrons to provide the first mechanistic study on the structure–property relationships of macromolecular antiscalants based on which an optimum structure has been developed to prevail the performance of the most efficient industrial scale inhibitors.