The programmed assembly of gold nanoparticles on DNA templates allows the design of nanostructures with optical properties that directly depend on the morphology of a biochemical scaffold. Indeed, the nanometer-scale sensitivity of plasmon coupling allows the translation of minute conformational changes into macroscopic optical signals. In particular, we showed that it is possible to design DNA-linked gold nanoparticle dimers that act as nanoscale actuators: nanostructures that change conformation under an external stimulus such as the hybridization of a specific DNA strand (L. Lermusiaux et al, ACS Nano 6, 10992 (2012)). Importantly, we are able to monitor, on a simple color camera, the conformational changes of a single DNA-assembled gold particle dimer as its gap is reduced from 20 nm to 1 nm when varying the local ionic strength (L. Lermusiaux et al, ACS Nano 9, 978 (2015)).
We will also discuss recent results on the use of 3D DNA origamis as scaffolds for the assembly of plasmonic nanostructures, demonstrating that the conformation of the origami can be correlated to single nanostructure spectroscopy measurements. The flexibility of these biochemical templates opens exciting perspectives for the optical sensing of specific physicochemical stimuli that actively modify their 3D conformation, such as short biomolecules, specific cations or organic trace elements in water.