DNA-templated Ag nanocluster formation

The high affinity of Ag+ for DNA bases has enabled creation of short oligonucleotide-encapsulated Ag nanoclusters without formation of large nanoparticles. Time-dependent formation of cluster sizes ranging from Ag-1 to Ag-4/oligonucleotide were observed with strong, characteristic electronic transitions between 400 and 600 nm. The slow nanocluster formation kinetics enables observation of specific aqueous nanocluster absorptions that evolve over a period of 12 h. Induced circular dichroism bands confirm that the nanoclusters are associated with the chiral ss-DNA template. Fluorescence, absorption, mass, and NMR spectra all indicate that multiple species are present, but that their creation is both nucleoticle- and time-dependent.