Synthesis of Platinum Cluster Chains on DNA Templates:  Conditions for a Template-Controlled Cluster Growth

Abstract

We investigate the conditions which should be fulfilled to grow chains of nanosized noble metal clusters on DNA templates according to a selectively heterogeneous, template-controlled mechanism. A long incubation of double-stranded DNA molecules with Pt(II) complexes is necessary to obtain a template-directed formation of thin and uniform cluster chains after chemical reduction of the DNA/salt solution. Without this “activation” step, DNA acts as a nonspecific capping agent for the formed clusters and does not hinder the formation of random cluster aggregates. The effect of binding Pt(II) complexes to the DNA is investigated by UV−vis spectroscopy, electrophoresis experiments, and scanning force microscopy, revealing that the base stacking along the DNA molecule is significantly distorted but the double-stranded DNA configuration is retained. Citrate ions can be used as additional stabilizers for the heterogeneously grown metal clusters, leading to significantly more regular metal cluster chains. After a systematic variation of the absolute concentration of the reactants (Pt salt, DNA, reducing agent), we can conclude that there is an optimum concentration value for the fabrication of cluster chains and that small variations around the optimum value do not have noticeable effects on the quality of the metallization products. The described metallization procedure can be resolved into a series of simple and efficient steps, which is essential for a biomimetic fabrication of nanostructures in a reproducible way.

Small‐Angle Scattering of S‐Layer Metallization

“…Inspired by the process of biomineralization, preformed organic matrices may be employed to direct the nucleation and growth of inorganic nanoparticles.[1] In this way, synthetic colloidal self-assemblies [2] as well as natural (biomolecular) structures such as DNA [3][4][5] or viruses [6,7] can be used as templates for the formation of nanoparticles. Crystalline bacterial cell surface layers (S layers), which represent one of the most common cell-envelope components of bacteria and archaea, [8] have been proven to be a suitable biomolecular template for the formation of regular two-dimensional semiconducting [9,10] and metal [11][12][13] nanoparticle arrays.…”

The Application of Biomolecules in the Preparation of Nanomaterials

“…By using DNA molecule as template, many metal nanowires and polymer nanowires, such as Pd nanowires (Deng et al, 2003;Richter et al, 2000Richter et al, , 2001, Pt nanowires (Ford et al, 2001;Seidel et al, 2004), Cu nanowires (Monson etal., 2003) and polynailine nanowires (Ma et al, 2004), have been produced by reducing the metal ions or polymerizing the monomers that bound on the DNA template. For example, Deng et al have fabricated the parallel arrays or crossed arrays of Pd nanowire (Deng et al, 2003).…”

Biomolecular Assembly of Gold Nanocrystals

“…Biotemplating has also been used to synthesize magnetite nanocrystals [79] and platinum nanocrystals [80] along the length of DNA. Nickel oxide nanocrystals have been synthesized with the assistance of bovine serum albumin [81], and tellurium wires have been synthesized with the assistance of alginic acid.…”