UC Irvine

DNA-stabilized silver nanoclusters (DNA-AgN) are atomically precise and sequence-tuned nanomaterials with potential applications for deep tissue biomedical imaging. Here, a dual-emissive DNA-AgN is presented with fluorescence in the first near-infrared (NIR-I) spectral window and microsecond-lived photoluminescence in the second near-infrared (NIR-II) spectral window. High-resolution electrospray ionization mass spectrometry showed that the emitter has the molecular formula (DNA)2[Ag17]11+. The crystallization of (DNA)2[Ag17]11+ was unsuccessful, which prevented the use of X-ray diffraction to determine its structure. However, sequence variations of the templating DNA oligomer provided insights into nucleobases that are critical for stabilizing the Ag1711+. Moreover, addition of an adenosine or thymidine at the 5′-end of the stabilizing DNA strand maintained the composition and photophysical properties of the (DNA)2[Ag17]11+, suggesting a potential site for conjugation with biomolecules to enable targeted labeling in future bioimaging applications.