J. Am. Chem. Soc. doi:10.1021/ja800266p (2008)

Nanoscale synthetic channels that are opened and closed by a DNA 'switch' have been constructed by a team in China. Such channels could form part of a selective membrane for filtering and purifying water or for mimicking the changeable permeability of biological ion channels.

Yugang Wang of Peking University and his colleagues etched funnel-shaped holes, 5–44 nanometres wide at the narrowest point, into polymer membranes and lined the pores' mouths with single strands of DNA. The DNA in the pore is tightly folded in acidic conditions but unravels into loose chains at pH 8.5. This alters the diameter of the hole and therefore the flux of ions through it.