Motif-based design of DNA templates for fluorescent silver clusters

Few-atom silver clusters encapsulated by DNA1 (AgN-DNA) possess unique fluorescence properties that depend on the specific DNA template that stabilizes the cluster.2,3 Particular choices of this template select for fluorescent silver clusters with peak emission wavelengths throughout the visible and near-IR spectrum.4,5 This wide color palette, combined with proposed low toxicity, high quantum yields of some clusters,6 low synthesis costs, and compatibility with DNA have enabled many applications that employ AgN-DNA, including colorimetric sensing for single base mutations,7,8 metal ions,9,10 and microRNAs,11 as well as logic devices12 and cell labeling.13,14 Yet despite the rapid growth of applications relying on these silver clusters, it is not understood why certain mixed-base DNA templates produce brightly fluorescent solutions that are temporally stable while other apparently similar sequences do not. For this reason, template design15 relies on experimentally testing oligomers with sequences selected by informed guessing. To aid development of applications employing AgN-DNA, we explore methods to efficiently select DNA template sequences that stabilize brightly fluorescent clusters