It's a wrap

Strands of DNA perform remarkable acrobatics to wrap themselves around carbon nanotubes, forming very useful hybrid structures

Credit: © 2007 ACS

Hybrid structures that combine biological molecules with inorganic nanomaterials are finding applications in electronics, medicine and security. One particularly promising structure arises when a strand of DNA, one of the most important biomolecules, becomes wrapped around a carbon nanotube. Now, Charlie Johnson and co-workers¹ at the University of Pennsylvania in Philadelphia have used computer simulations to explain how this unexpected marriage comes about.

The researchers simulated the molecular dynamics of a 14-base random segment of single-stranded DNA being adsorbed onto a single-walled carbon nanotube, under typical experimental conditions. Owing to strong van der Waals interactions, the nucleotide bases on the DNA molecule rotate by up to 90° to stack on the nanotube surface. Within a few nanoseconds, the entire DNA strand wraps itself around the nanotube in either a right or left-handed helix, in loops, or in a disordered kinked structure, depending on the initial configuration of the molecules.

These remarkable arrangements seem to be caused by electrostatic interactions that rearrange the angles of bonds in the DNA sugar-phosphate backbone. This new understanding could allow scientists to exploit DNA-nanotube hybrids in novel methods of chemical sensing, nanotube sorting and even ultrafast DNA sequencing.