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 AgNO₃ 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 (AFM) and single-molecule two-photon fluorescence lifetime imaging (FLIM) 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.