  Based on modern single molecule techniques, we devise a number of possible
experimental setups to probe local properties of DNA such as the presence of
DNA-knots, loops or folds, or to obtain information on the DNA-sequence.
Similarly, DNA may be used as a local sensor. Employing single molecule
fluorescence methods, we propose to make use of the physics of DNA denaturation
nanoregions to find out about the solvent conditions such as ionic strength,
presence of binding proteins, etc. By measuring dynamical quantities in
particular, rather sensitive nanoprobes may be constructed with contemporary
instruments.
