Synthesis of Thin and Highly Conductive DNA‐Based Palladium Nanowires

Abstract

Nanotechnology aims to produce and manipulate well-defined structures at the nanoscale level with high accuracy. However, it has become quite clear in recent years that conventional ''top-down'' approaches are beset with perhaps insurmountable experimental difficulties owing to various physical effects that are not easily scalable, and most importantly, because of the cost issues associated with nanoscale fabrication processes. This state of affairs has led to great interest in the development of new methodologies based on bottom-up approaches. In this context, the DNA motif is of particular interest because of its unique intra-and intermolecular recognition properties. In particular, DNA has already been extensively used to construct nanostructures, [1,2] biomolecule/nanoparticle conjugates, and scaffolds for the assembly of nanoparticles. [3][4][5][6][7] The use of DNA for the assembly of devices can also be easily envisioned. Our goal is to use DNA not only as a positioning scaffold for nanodevices, but also as a support for the conducting element. For this purpose, we have developed a novel approach to metallize DNA molecules that have been previously deposited on a dry substrate in a typical nanodevice configuration. Several methods have been developed to metallize DNA scaffolds over the last 10 years, [8] and different metals have been used in the metallization process. One of the most common approaches involves ion-exchange on the DNA backbone for the deposition of silver [9,10] or copper.[11] Alternatively, positively charged gold nanoparticles have been deposited on DNA via electrostatic interactions with the negatively charged DNA backbone. [12,13] In another approach, Pt [14][15][16][17][18][19][20][21] and Pd [22][23][24][25][26][27] complexes have been extensively used for metallizing DNA based on the insertion of metal complexes between the DNA bases.Most DNA electroless-plating metallization techniques use a sequence of three main steps.[8] The first step consists of the binding of metal ions or metal complexes to DNA strands to create reactive metal sites. This step is usually called the activation step and is based either on exchanging ions into the DNA backbone, [9,10] or the insertion of metal complexes between the DNA bases. [14][15][16][17][18][19][20][21][22][23][24][25][26][27] In the second step, the reactive metal sites are usually treated with a reducing agent. This converts the metal ions or metal complexes into metal nanoclusters fixed onto the DNA strand. The third step of the metallization process consists of the autocatalytic growth of these affixed metal nanoclusters, which are now able to act as seeds because of the simultaneous presence of both metal-ions/metalcomplexes as well as reducing agents in the growth solution. Previous reports in the literature have illustrated the growth of metallic Pd nanowires by this approach. [20][21][22][23][24][25][26][27] However, the major drawback of this fabrication method is the fast kinetics of the growth reaction. Reducing agents dissolved...

Spontaneous formation of aligned DNA nanowires by capillarity-induced skin folding

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Efficient DNA-assisted synthesis of trans-membrane gold nanowires

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Synthesis and Applications of Noble Metal and Metal Silicide and Germanide 1-Dimensional Nanostructures

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