DNA-Mediated Assembly of Nanotube Devices
An effective strategy for assembly of devices at the nano scale should provide low-error, parallel, autonomous construction of well-ordered structures. An effort was made in our group to develop a DNA-based, bio-inspired strategy for organizing carbon nanotubes, fullerenes, and other components for nano devices. To the “programmed” assembly scheme we envision, DNA contributes molecular recognition, convenient (de-) hybridisation conditions, and compatibility with existing biotechnological tools, such as gel electrophoresis, enzymatic cutting, and PCR. In this project, the specific goals were to: Chemically modify nanotubes and fullerenes with oligonucleotides, to serve as components for nanodevices:
- Use DNA to encode the assembly instructions for prototype devices;
- Investigate ways to operate on these devices with enzymes and proteins;
- Most fundamentally: explore the interface, at the nano scale, between the biological and inorganic worlds.
As attractive as it may seem to attach DNA directly to nanotubes, this is not easily accomplished. On the one hand, DNA is a water-soluble, rather fragile organic polymer; by contrast, nanotubes are water insoluble and remarkably inert in the harshest chemical environments. The gap between these two chemistries was bridged in our group by the successful derivatization of single-walled carbon nanotubes (SWNT) with PNA (peptide nucleic acid, a DNA mimick). The colorized AFM image above shows a nanotube (purple) attached to DNA via PNA adducts on the nanotube. The derivatization of nanotubes by PNA was published in Nature 420(6917) 761 (2002). For a related general overview see: R. Service, Science 298 2322-3 (2002).