Dynamic electrical switching of DNA layers on a metal surface

We report on the dynamic control over the orientation of short oligonucleotide strands which are tethered to gold surfaces in electrolyte solution. By applying alternating electrical bias potentials to the supporting electrodes we are able to induce a switching of the layer conformation between a lying and a standing state, simultaneously monitored in a contactless mode by fluorescence techniques. We demonstrate that our electrooptical experiments allow for an in-depth investigation of the intriguing molecular dynamics of DNA at surfaces and, moreover, how the dynamic response of these switchable biomolecular layers opens new prospects in label-free biosensing.