We are exploring how DNA behaves in volumes comparable or small relative to its persistence length (about 50-60 nm, crudely the “average bending radius”) of the molecule. We are then using this knowledge to design devices in which molecular biology techniques are performed on a single-molecule basis, and more efficiently than in conventional bulk methods.

To see the importance, one needs to know that DNA is a semiflexible polymer, and forms random coil in solution. Hence, not much can be said about a short DNA molecule just by looking at it with an ordinary microscope. Using an electron microscope, the finer structure becomes apparent, but translating a spatial position into a genomic position is nearly impossible even for an ordinary piece of viral DNA.

The problem can be overcome by stretching DNA molecules, which we do inside nanochannels. Once the channel width becomes comparable in size to the persistence length of DNA, molecules are stretched out to a well-defined faction of their contour length. It then becomes possible to directly observe the length of DNA, image binding of proteins to DNA, or to monitor site-selective biochemistry.

Specific Projects

DNA physics – Controlling DNA using confinement and electric fields

Flow stabilized solids – Colloids at the verge of stability

Epigenetic analysis – Single cell epigenetics

DNA compaction by proteins

Plasmonic sensor for bioanalytics