As reported by Schmidt and Heckel in the journal "Nano Letters" (online advance publication, dx.doi.org/10.1021/nl200303m), they first created two C-shaped DNA-fragments for the catenans. With the help of special molecules that act as sequence-specific glue for the double helix, they arranged the "Cs" in such a ways as to create two junctions, with the open ends of the "Cs" pointing away from each other (see images). The catenan was created by adding two strands that attach to the ends of the two ring fragments, which are still open. Thorsten Schmidt dedicated the publication to his wife Dr Diana Gonalves Schmidt, who also appreciates the work on scientific level, since she was also a part of Alexander Heckel's work group.
Since they are much smaller than the wavelengths of visible light, the rings cannot be seen with a standard microscope. "You would have to string together about 4000 such rings to even achieve the diameter of a human hair", says Thorsten Schmidt. He therefore displays the catenans with a scanning force microscope, which scans the rings that have been placed on a surface with an extremely fine tip.
|Contact: Dr. Thorsten Schmidt|
Goethe University Frankfurt