Linear assemblies of nanoparticles electrostatically organized on DNA scaffolds.

A significant challenge faced in the use of nanoscale building blocks is developing parallel methods for interconnecting and patterning assemblies of the individual components. Molecular or polymeric scaffolds hold promise as a means of preparing closely spaced, specifically arranged nanoscale assemblies. Here we show how a biopolymer, DNA, can be used as a scaffold for the assembly of extended, close-packed, ligand-stabilized metal nanoparticle structures, including several desirable architectures (such as lines, ribbons, and branches). Electrostatic binding of ligand-stabilized nanoparticles to the DNA backbone results in extended linear chain-like structures, ribbon-like structures composed of parallel nanoparticle chains, and branched structures. High-resolution transmission electron microscopy shows that the particles are evenly spaced, separated only by the 15 A imposed by the intervening ligand shell. These studies demonstrate that biomolecular nanolithography (the arrangement of nanoscale building blocks on biomolecular scaffolds) is a viable approach to interconnecting individual devices into extended, closely spaced assemblies.