Formation of Bimetallic Ag–Au Nanowires by Metallization of Artificial DNA Duplexes

Abstract

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.

Click chemistry with DNA

“…The same group has also used click chemistry to produce bimetallic Au/Ag nanowires, 38 and chain-like assembles of gold nanoparticles by growth on artificial DNA templates. 39 An ultrasensitive method has also been developed 40 for the detection of DNA and RNA in the diagnosis of genetically related diseases such as cancer.…”

On the application potential of gold nanoparticles in nanoelectronics and biomedicine

“…Utilizing DNA as a template is attractive owing to the fact that the extraordinary self-recognition properties, and the possibility of directing the sequence by modern synthetic methods enables the template to be programmed to a high degree. This concept has already been applied in many approaches ranging from electrostatic interactions to full metallization Loweth et al 1999a,b;Niemeyer 2001a;Xiao et al 2002;Warner & Hutchison 2003;Le et al 2004;Li et al 2004;Woehrle et al 2004;Braun et al 2005;Deng et al 2005a,b;Noyong et al 2007a;Fischler et al 2007). …”

Postsynthetische DNA‐Modifizierung mithilfe der kupferkatalysierten Azid‐Alkin‐Cycloaddition

“…Dieses atomare Silber kann in einer nachfolgenden Entwicklungsreaktion wie bei der Schwarzweißphotographie entwickelt werden. In einem zweiten Schritt kann diese DNA mit einer Goldsalzlösung (AuSCN, Hydrochinon) [41] behandelt werden; dadurch scheiden sich um die Silbernanocluster herum Goldatome ab, bis die DNA am Ende mit einem dünnen Mantel aus metallischem Gold überzogen ist. Die so erzeugten Gold-DNA-Nanodrähte haben sehr gleichförmige Durchmesser, die durch Begrenzung der Entwicklungszeit auf 10 nm eingestellt werden können.…”