DNA-programmed galvanic Ostwald ripening in nanoparticle assemblies

Ostwald ripening of nanoparticles, where larger particles grow at the expense of smaller ones, is typically a thermodynamically driven process that is difficult to control. Here, we report contact-dependent, localized galvanic Ostwald ripening, a mechanism that can harness Ostwald ripening of nanoparticles as a programmable tool for nanofabrication. Using DNA origami to precisely control interparticle distances, we show that silver grows homogeneously on gold seeds until nanoparticle electrical contact triggers asymmetric ripening, driven by size-dependent electrochemical potentials. By programming when and where nanoparticles touch, we direct ripening pathways to create designer heterogeneous nanoparticle structures with enhanced plasmonic properties. In this work, we elucidate the origin of heterogeneous silver growth in nanoparticle clusters and establish design principles for engineering asymmetric nanostructures with predetermined morphologies, advancing both fundamental colloidal nanoscience and plasmonic device fabrication. Ostwald ripening is a stochastic process in nanoparticle systems. Here, the authors use DNA origami to program contact-dependent, localized galvanic Ostwald ripening, directing growth pathways to build asymmetric nanostructures with intense plasmonic hotspots.