Chloride Ligands on DNA-Stabilized Silver Nanoclusters

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  • Anna Gonzàlez-Rosell
  • Sami Malola
  • Rweetuparna Guha
  • Nery R. Arevalos
  • María Francisca Matus
  • Meghen E. Goulet
  • Esa Haapaniemi
  • Benjamin B. Katz
  • Vosch, Tom André Jos
  • Jiro Kondo
  • Hannu Häkkinen
  • Stacy M. Copp

DNA-stabilized silver nanoclusters (AgN-DNAs) are known to have one or two DNA oligomer ligands per nanocluster. Here, we present the first evidence that AgN-DNA species can possess additional chloride ligands that lead to increased stability in biologically relevant concentrations of chloride. Mass spectrometry of five chromatographically isolated near-infrared (NIR)-emissive AgN-DNA species with previously reported X-ray crystal structures determines their molecular formulas to be (DNA)2[Ag16Cl2]8+. Chloride ligands can be exchanged for bromides, which red-shift the optical spectra of these emitters. Density functional theory (DFT) calculations of the 6-electron nanocluster show that the two newly identified chloride ligands were previously assigned as low-occupancy silvers by X-ray crystallography. DFT also confirms the stability of chloride in the crystallographic structure, yields qualitative agreement between computed and measured UV-vis absorption spectra, and provides interpretation of the 35Cl-nuclear magnetic resonance spectrum of (DNA)2[Ag16Cl2]8+. A reanalysis of the X-ray crystal structure confirms that the two previously assigned low-occupancy silvers are, in fact, chlorides, yielding (DNA)2[Ag16Cl2]8+. Using the unusual stability of (DNA)2[Ag16Cl2]8+ in biologically relevant saline solutions as a possible indicator of other chloride-containing AgN-DNAs, we identified an additional AgN-DNA with a chloride ligand by high-throughput screening. Inclusion of chlorides on AgN-DNAs presents a promising new route to expand the diversity of AgN-DNA structure-property relationships and to imbue these emitters with favorable stability for biophotonics applications.

Original languageEnglish
JournalJournal of the American Chemical Society
Volume145
Issue number19
Pages (from-to)10721−10729
Number of pages9
ISSN0002-7863
DOIs
Publication statusPublished - 2023

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© 2023 The Authors. Published by American Chemical Society.

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