DNA nanotechnology seeks to create synthetic functional entities inspired by nature. Interlocked DNA structures like rotaxanes and catenanes are possible versatile building blocks for such DNA machines, as they equip construction units with moving parts to build functional DNA machines that can perform specific tasks. An important step in controlling functionality is the ability to switch between different states of the DNA nanostructure. To this end, we are developing molecular switching elements that trigger specifically controllable structural rearrangements by light irradiation, toehold-extended nucleotides, or aptamer-mediated ligand binding, thereby conferring defined and controllable functionality to the DNA machine.