Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
For full article and contact information, see Angew. Chem. Int. Ed. 1998, 37 (11), 1528
Biological Construction in the Laboratory
American Researchers build new compounds
from DNA and fullerenes
Chemists nowadays are very adept at designing and producing complex small molecules for use as pharmaceuticals and catalysts. But these advances are as nothing when compared to the vast yet highly ordered structures routinely put to use in nature - the coils of DNA, or collagen fibres, to mention just two examples. Certainly for the manufacture of miniature machines and the development of so-called "nanotechnology", it would be a huge step forward to prepare artificial compounds of similar dimensions to these natural models, but with different properties. James M. Tour, Alan M. Cassell and Walter A. Scrivens from the University of South Carolina, USA, have taken up the challenge and succeeded in preparing a new compound using strands of DNA itself as a template. Their macromolecule consists of a core of DNA carrying innumerable C60-spheres on its back.
The researchers didn't decide to focus on fullerenes - which look rather like miniature footballs - just in honour of the current soccer World Cup: it had rather more to do with the inherent problems presented to chemists working with giant molecules. In particular, they are often only sparingly soluble in most solvents, which tends to rule out a lot of investigative techniques. An exception to this rule is electron microscopy, which has recently allowed other workers superb views of single nanotubes of carbon. C60 spheres are closely related to these molecules; so it was not unreasonable to expect that a DNA molecule coated with fullerenes would prove just as cooperative a subject for observation with this technique.
The researchers were not disappointed: the DNA-"football" molecules showed up well under the electron microscope. The fullerene spheres could be seen to wrap up the DNA almost completely, leaving hardly a gap on the surface. Interestingly, the mega-molecules were more strongly coiled than the researchers had expected, rather like a tightly twisted telephone cable. The chemists hope to be able to prevent this twisting in future work by connecting the fullerenes themselves together. 'Natural' building materials are well on their way to becoming a hit in the laboratory too.