Nano-softball made of DNA

In order for this process to result in a dodecahedron and not some other random geometric object, all of the DNA strands must have a different sequence. Among these, there must, however, be pairs of complementary strands that can bind to each other.

By using a computer program, the researchers identified a set of 30 independent, 15-base-pair-long, double-stranded DNA sequences with similar physical properties. The double-stranded sequences were assigned to the individual edges of the dodecahedron and to specific vertices for termination. It was then determined which three single-stranded sequences needed to be attached to each three-legged junction for the predetermined structure to form.

The team synthesized the 20 computed trisoligonucleotides by means of a solid-phase synthesis. The three DNA strands were always attached by way of an aromatic six-membered carbon ring. When mixed in equal parts in a buffer solution, these building blocks do aggregate to form the expected product: regular dodecahedra. Atomic force microscopy images reveal them to be uniform particles with a diameter of about 20 nm. Under pressure, the dodecahedra are quite flexible, the can be deformed like “soft balls” without incurring any damage.

If the trisoligonucleotides are equipped with pendant “arms”, the dodecahedra can be outfitted with additional functional molecules. In this way, highly complex nanoconstructs, resembling little viruses in shape and size, should be accessible in the future. Potential applications range from medical diagnostics to nanoelectronics.

Author: Günter von Kiedrowski, Ruhr-Universität Bochum (Germany), http://www.ruhr-uni-bochum.de/oc1/mitarbeiter/Guenter-Kiedrowski.html
Title: Self-Assembly of a DNA Dodecahedron from 20 Trisoligonucleotides with C3h Linkers
Angewandte Chemie International Edition, doi: 10.1002/anie.200702682