Nature Commun. 6, 8032 (2015)

DNA is a natural polymer that has emerged as a versatile material for the construction of intricate nanostructures. The conductance of the molecule has also long been a topic of fascination, but a series of contradictory results has stifled many thoughts of developing DNA-based nanoelectronics. Nongjian Tao and colleagues at Arizona State University and Northwestern University have now shown that single molecules of DNA can exhibit piezoresistivity, a result that provides additional insight into the issue of charge transport in DNA.

Piezoresistivity is a change in the electrical resistivity of a material due to mechanical force and has been observed before in single (non-DNA) molecules that were positioned between two electrodes. In such cases, the effect is typically due to the coupling between molecule and electrode. The researchers examined the molecular conductance and piezoresistivity of single double-stranded DNA molecules that had different sequences and lengths by positioning the molecules between a gold surface and the tip of a scanning tunnelling microscope. With the help of calculations, they were able to determine that the observed piezoresistivity is an intrinsic property of the molecule and is due to force-induced changes in the π–π coupling between neighbouring bases and changes in the activation energy of hole hopping.

Tao and colleagues also suggest that the observed effect indicates that DNA nanostructures could be of value in the development of microelectromechanical systems (MEMS) applications.