DNA-Origami Enabled Distance-Dependent Sensing

Localized surface plasmon resonance is a popular optical detection technique due to its ease of use. However, the main issues of this technique are its selectivity and sensitivity towards (small) single molecules. We address these challenges by introducing a distance-dependent plasmonic sensing method based on a gold nanoparticle (AuNP) tethered by a single DNA hairpin to a gold film (Au-film). The plasmonic properties of a AuNP enable us to distinguish the z-height of the particle. In the absence of a target sequence, the hairpin keeps the AuNP close to the Au-film, while hybridization with a target sequence results in an extended state of the DNA tether. We experimentally confirmed the assembly of this sensor and by simulations, predicted the plasmonic signal of the two states. Finally, we showed experimental results as proof of concept of our sensing method.