Template and template-free preparation of one-dimensional metallic nanostructures

In this article, we have studied and developed two approaches for organizing metallic nanoparticles into one-dimensional assemblies. The first uses DNA as a 'template' and allows the preparation of various silver nanostructures ('beads-on-a-string' or rod-like wires). The conductance of such nanostructures was demonstrated by employing a powerful technique, Electrostatic Force Microscopy (EFM). This technique gave us 'contactless' information about the electrical properties of silver nanostructures, aligned on a SiO(2)/Si surface. Additionally, I-V characteristics of a single silver nanowire crossing two microelectrodes were recorded. The nanowire resistivity was estimated at 1.46 x 10(-7) Omega m (at 300 K), which is one order of magnitude higher than that of bulk silver (1.6 x 10(-8) Omega m). The second approach is a 'template-free' one, and exploits the binding ability of l-arginine, which favours the self-assembling of capped gold nanoparticles into gold nanochains. The results suggest that gold nanochains were formed due to dipole-dipole interaction between adjacent nanoparticles, which fuse together through an oriented attachment mechanism. Atomic force microscopy, TEM, UV-vis spectroscopy and X-ray diffraction were used to characterize the morphological, optical and structural properties of these metallic nanostructures.