Research Highlights

• Subject Categories:
  • Biotechnology
  • Genetics
  • Materials

Published online: 6 June 2007 | doi:10.1038/nchina.2007.96

Nanochannels: Switchable membrane

Felix Cheung

Introduction

© (2007) Nature Nanotech.

Biological channels made from proteins regulate the flow of ions across the membranes of all living cells. Now, Qi Ouyang, Lei Jiang and co-workers in Beijing have made similar channels from DNA and used them to build a complex gated system for the controlled release of certain molecules¹.

Previous studies have shown that the 'dsDNA membrane' — a compact array of double-stranded DNA — is impermeable to any molecules larger than one nanometre, but that a single mutation in the DNA will introduce a small leak, or 'channel', enabling molecules of comparable size to the channel diameter to escape. This mutation can be caused by the stress exerted by an increased concentration of solute molecules at the membrane surface.

Based on this concept, the researchers built a gated system for thionine molecules that consists of two components (pictured): a gold substrate coated with a layer of PDC (a chemical that thionine molecules attach to) and a single-stranded DNA spacer layer with dsDNA at the end segments. The researchers slowly raised the temperature, causing the PDC layer to release thionine molecules. They noticed sudden drops and plateaux in the thionine concentration in the spacer layer, indicating that, at critical maximum and minimum concentrations, the dsDNA channel opened and closed respectively, controlling the diffusion of thionine.

The novel gated system has potential applications in nanomedicine, where the controlled release of drug molecules is needed.

The authors of this work are from:
School of Physics and Center for Theoretical Biology, Peking University, Beijing, China; National Center for Nanoscience and Technology, Beijing, China; Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.

References

1. Mao, Y., Chang, S., Yang, S., Ouyang, Q. & Jiang, L. Tunable non-equilibrium gating of flexible DNA nanochannels in response to transport flux. Nature Nanotech. doi: 10.1038/nnano.2007.148 (2007).  | Article |