DNA, the carrier of genetic information, has become established as a highly useful building material in nanotechnology. One requirement in many applications is the controlled, switchable assembly of nanostructures. In the journal Angewandte Chemie, scientists have now introduced a new strategy for control through altering pH value. It is based on ethylenediamine, which only supports the assembly of DNA components in a neutral to acidic environment—independent of the base sequences and without metal ions.