DNA Origami-Guided Assembly of the Roundest 60–100 nm Gold Nanospheres into Plasmonic Metamolecules

DNA origami can provide programmed information to guide the self-assembly of gold nanospheres (Au NSs) into higher-order supracolloids. Molecularly precise and truly 2D/3D integration of Au NSs is possible using DNA origami-enabled assembly, and the resulting assemblies have potential applications in plasmonics and metamaterials. However, the relatively small size (<60 nm) and randomly faceted Au NSs that have been used thus far in DNA origami-enabled assembly have limited their nanophotonic applications. Here, the robust self-assembly of the 60–100 nm roundest Au NSs into metamolecular assemblies using 3D DNA origami is described. These Au NSs are successfully conjugated with DNA oligonucleotides and are therefore stable at high salt concentrations even without backfilling using organic ligands. The roundest Au NSs are successfully assembled into supracolloidal metamolecules and chains via 3D DNA origami. These plasmonic metamolecules and chains display strong electric and unnatural magnetic resonances that can be deterministically controlled.