DNA-programmed nanoseeding via a depletion layer effect

Nanoscale synthesis has produced rich colloidal materials with distinct compositions and geometries, where heterogeneous nucleation on pre-formed nanoparticle seeds often plays a key role in dictating the crystallinity and morphologies of the nano-products. Different from a regular nanosynthesis with individual nanoparticles as nucleation seeds, a strategy based on self-assembled nanoseeds to direct the formation of nanophase materials depicts an emerging direction in modern chemical nanofabrication. Accordingly, understanding the coupled depletion-layer effect between adjacent seeding units and its influence on the nucleation and growth of nanomaterials becomes an urgent while quite tough task. To achieve this goal, the present work takes advantage of DNA-programmable gold nanoparticle (AuNP) dimers to probe the underlying rules governing a silver-plating reaction, which are related to coupled (i.e. spatially overlapped) diffusional depletion layers of reactive species around the AuNP seeds. Particularly, the study unambiguously discloses that size disparity of AuNPs, inter-particle distance, and the mechanical rigidity of DNA linkage together contribute to the suppressed silver growth on a small AuNP seed situated in the depletion layer of a large AuNP. These previously unreported findings are highly valuable toward a fusion between DNA nanotechnology and colloidal synthesis to produce compositionally and structurally customizable metamaterials with previously unattainable functions.