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Uniform bimetallic nanowires, tunable in size, have been grown on artificial DNA templates via a two-step metallization process. Alkyne-modified cytosines were incorporated into 900-base-pair polymerase-chain-reaction fragments. The alkyne modifications serve as addressable metal-binding sites after conversion to a sugar triazole derivative via click chemistry. Reaction of the Tollens reagent with these sugar-coated DNA duplexes generates Ag0 metallization centers around the sugar modification sites of the DNA. After a subsequent enhancement step using gold, nanowires < or = 10 nm in diameter with a homogeneous surface profile were obtained. Furthermore, the advantage of this two-step procedure lies in the high selectivity of the process, due to the exact spatial control of modified DNA base incorporation and hence the confinement of metallization centers at addressable sites. Besides experiments on a membrane as a proof for the selectivity of the method, atomic force microscopy (AFM) studies of the wires produced on Si-SiO2 surfaces are discussed. Furthermore, we demonstrate time-dependent metallization experiments, monitored by AFM.

Using DNA molecules to construct a structural scaffold for nanotechnology is largely accepted. In this article, we report on two methods for constructing a figure-eight structure of DNA molecules having a relatively high yield that could be used further as a scaffold for nanotechnology applications. In the first method, two plasmids were constructed that, on digestion with a restriction endonuclease producing nicks in the corresponding sites and after heating, produced complementary single-stranded sequences, enabling the plasmids to hybridize to each other and forming a figure-eight structure. The formation of the figure-eight structure was analyzed by restriction analysis and gel electrophoresis as well as by atomic force microscopy. The second method makes use of the bacteriophage M13 that is obtained as either a single- or double-stranded circular DNA molecule. Two M13 molecules harboring complementary sequences were constructed and produced a figure-eight structure on hybridization. The methods described here could be used further for the construction of nanoelectronic devices.

This article presents information on the DNA metallization procedures that was developed in order to increase the conductivity of subsequent DNA nanostructures. Since the construction of nanodevices requires the preparation of long DNA double-stranded scaffolds from several to hundreds of nanometers in length, the author's surmised that selective aldehyde labeling could be achieved via an enzymatic method. The article informs that the direct incorporation of an aldehyde-modified triphosphate analogue provides a more expeditious route toward aldehyde-modified DNA. Their enzymatic incorporation provided mixed results.