Quantizing DNA Metallization for Site‐Defined Growth of Single Quantum Emitters

DNA‐templated silver nanoclusters promise subwavelength light control for quantum photonics, sensing, and bioimaging. Yet deterministic one‐per‐site growth has lacked explicit quantitative criteria. Here, we define quantitative thresholds that render site‐specific nucleation of single silver nanoclusters reliable on DNA origami. By systematically varying oligocytosine (OligoC) handle number and Ag ⁺ reduction conditions, we identify a cooperative rule‐of‐10 OligoC handles per site and an AgNO ₃ loading window that together produce one nanocluster per site with nanometer registration. To enable tailored emitter permutations, we program one‐, two‐, and three‐site arrays and show that the same thresholds hold for both substrate‐bound and solution‐phase syntheses. Correlative atomic force microscopy and single‐molecule two‐photon fluorescence lifetime imaging microscopy verify single‐emitter behavior, bright two‐photon fluorescence, single‐step photobleaching, and ≈1.2 ns lifetimes. We expect that these explicit rules provide physical insight into DNA‐directed nucleation and open practical routes to addressable quantum emitters and scalable nanocluster arrays for integrated nanophotonics and single‐molecule sensing.