Site-Specific Assembly of DNA-Based Photonic Wires by Using Programmable Polyamides**

The first example of a programmable DNA photonic wire is reported utilizing fluorophore-tethered pyrrole-imidazole polyamides for site-directed fluorophore assembly along a pre-formed DNA duplex (see scheme; PB=Pacific Blue, Cy3=Cyanine 3; orange rectangles=fluorophore). The importance of such control is revealed by efficient energy transport over distances in excess of 27 nm

Electrical Manipulation of DNA on Metal Surfaces

Summary We review recent work on the active manipulation of DNA on metal substrates by electric fields. This includes the controlled positioning, alignment, or release of DNA on or into dedicated locations and the control of hybridization. In this context, we discuss techniques for immobilizing DNA on metal surfaces and methods of characterizing such hybrid systems. In particular, we focus on electrically induced, conformational changes of monolayers of short oligonucleotides on gold substrates. Such switchable layers allow for molecular dynamics studies at interfaces and have demonstrated large potential in label-free biosensing applications

Measuring Influenza A Virus and Peptide Interaction Using Electrically Controllable DNA Nanolevers

Electrically controllable deoxyribonuclic acid (DNA) nanolevers are used to investigate the binding interaction between Influenza A/Aichi/2/1968 and the peptide called “PeB”, which specifically binds the viral surface protein hemagglutinin. PeB is immobilized on gold electrodes of a “switchSENSE” biochip by conjugation to DNA-strands that are hybridized to complementary anchors. The surface-tethered DNA strand carries a fluorophore while the complementary strand is a multivalent arrangement carrying up to three PeB peptides. The nanolevers are kept upright (static) by applying a negative potential. Signal read-out for this static measurement mode is the change in fluorescence intensity due to changes in the local environment of the dye upon binding. Measurements of virus-peptide interaction show that the virus material specifically binds to the immobilized peptides and remains bound throughout the measurement time. Immobilized viruses are subsequently used as ligands to characterize oligovalent peptide binding to hemagglutinin, revealing rate constants of the interaction. Moreover, three Influenza A subtypes are compared in their binding behavior. Overall, this paper shows the ability to immobilize virus material on a sensor surface, which allows to target virus-proteins in their native environment. The “switchSENSE” method is therefore applicable to characterize virus-receptor interactions