Dielectric and dielectrophoretic properties of DNA

The physical properties of DNA are quite important for molecular genetics as well as for its nanotechnological applications. Studying the interactions of alternating current (AC) electric fields with deoxyribonucleic acid (DNA) allows one to draw conclusions about these properties. These interactions are usually investigated in two different ways. In dielectric spectroscopy, a DNA solution is placed in a homogeneous AC field and electronic parameters are measured over several frequency decades in the Hz to GHz range. These electronic data are then interpreted on the basis of physico-chemical models as a result of certain phenomena on the molecular level. In dielectrophoretic studies, a DNA solution is exposed to an inhomogeneous AC field and the spatial response of few or single molecules is monitored by optical or scanning force microscopy. This response can involve translation, elongation and orientation of the molecular strings. In this review, a survey is given of the literature dealing with the dielectric and dielectrophoretic properties of DNA as well as with applications of DNA dielectrophoresis.