Radio frequency-mediated local thermotherapy for destruction of pancreatic tumors using Ni-Au core-shell nanowires.

We present a novel method of radio frequency (RF)-mediated thermotherapy in tumors by remotely heating nickel (Ni)-gold (Au) core-shell nanowires (CSNWs). Ectopic pancreatic tumors were developed in nude mice to evaluate the thermotherapeutic effects on tumor progression. Tumor ablation was produced by RF-mediated thermotherapy via activation of the paramagnetic properties of the Ni-Au CSNWs. Histopathology demonstrated that heat generated by RF irradiation caused significant cellular death with pyknotic nuclei and nuclear fragmentation dispersed throughout the tumors. These preliminary results suggest that thermotherapy ablation induced via RF activation of nanowires provides a potential alternative therapy for cancer treatment.

Ultrahigh Tensile Strength Nanowires with a Ni/Ni-Au Multilayer Nanocrystalline Structure.

Superior mechanical properties of nanolayered structures have attracted great interest recently. However, previously fabricated multilayer metallic nanostructures have high strength under compressive load but never reached such high strength under tensile loads. Here, we report that our microalloying-based electrodeposition method creates a strong and stable Ni/Ni-Au multilayer nanocrystalline structure by incorporating Au atoms that makes nickel nanowires (NWs) strongest ever under tensile loads even with diameters exceeding 200 nm. When the layer thickness is reduced to 10 nm, the tensile strength reaches the unprecedentedly high 7.4 GPa, approximately 10 times that of metal NWs with similar diameters, and exceeding that of most metal nanostructures previously reported at any scale.

Magnetic nanodiscs fabricated from multilayered nanowires.

We report a simple, high throughput synthesis method of producing magnetic nanodiscs, in which the diameter and thickness are easily controlled. This method consists of two steps: (1) Electrodeposition for growing multilayered nanowires and (2) Selective etching of sacrificial layers. The electrodeposition step results in a bundle of multilayered nanowires. The nanowires consist of alternating layers of magnetic (e.g., Co) and sacrificial materials (e.g., Cu) inside the nanometer-sized pores of an anodized aluminum oxide (AAO) template. The diameter of each layer is determined by pore size, while the thickness is controlled by electrodeposition time. The selective wet etching step removes sacrificial layers, leaving the magnetic nanodiscs. Through this process, the magnetic nanodiscs are fabricated with aspect ratios ranging from 0.25 to 2.0.

Fabrication of monolithic polymer nanofluidic channels using nanowires as sacrificial templates.

We report a facile and reliable method to fabricate polymer-based monolithic nanofluidic channels. The nanochannels are obtained via three main steps: (1) fabrication of nanowire-transistor like structures, which are silver or zinc oxide nanowires horizontally bridging two electrodes made of zinc oxide on SiO(2)/Si substrates; (2) casting and curing polyimide solution on the nanowire structures; and (3) selective etching of the nanowire and electrode templates against the polyimide substrates. This process leads to the production of nanochannels with a diameter down to ∼ 50 nm. Our method is based on nanowires that are chemically synthesized whereas nanopattern fabrication conventionally relies on expensive equipment. Moreover, the polymer nanochannels are fabricated monolithically while a process of bonding two different materials is required in traditional methods where leakage problems are often identified at the interface. Construction of nanofluidic circuitry could be expected in the future based on the current work.