A major challenge in nanoscience and nanotechnology is the rational assembly of nanoscale objects. Here we report that gold nanorods, aspect ratio 18, can be functionalized with a biotin disulfide, and subsequent addition of streptavidin links the rods together in an end-to-end manner much more often than expected.

We report a method to make crystalline silver nanowires in water, in the absence of a surfactant or polymer to direct nanoparticle growth, and without externally added seed crystallites. The reaction is one in which silver salt is reduced to silver metal, at 100 °C, by sodium citrate, in the presence of NaOH. Hydroxide ion concentration is key to producing nanowires, which are up to 12 microns long, instead of nanospheres.

The hardness and elastic modulus of a silver nanowire was measured using a nanoindenter. It was found that the silver nanowire has comparable hardness and elastic modulus to bulk silver. An array of nanoscale indents was successfully made on the wire by directly indenting the wire. The shape and size of the indents are controllable. The nanoindentation approach permits the direct machining of nanowires without the complications of conventional lithography.

No abstract

Genomic DNA contains many higher-order structural deviations from the Watson-Crick global average. The massive expansion and hypermethylation of the duplex triplet repeat (CCG)(n)(CGG)(n) has characteristic higher-order structures that are associated with the fragile X syndrome. We have used luminescent mineral nanoparticles of protein-sized cadmium sulfide in optical assays to detect anomalous DNA structures. The photoluminescence of these particles is sensitive to the presence and nature of adsorbates. We previously found that our nanoparticles bind the fragile X repeat well but do not bind to normal double-helical DNA. In this study, we have determined that these particles are also able to detect the hypermethylated forms of these triplet repeats. Therefore, these nanoparticles may form the basis for future optical assays of higher-order DNA structures, especially those associated with human disease.