Issue 41, 2023

Electron count and ligand composition influence the optical and chiroptical signatures of far-red and NIR-emissive DNA-stabilized silver nanoclusters

Abstract

Near-infrared (NIR) emissive DNA-stabilized silver nanoclusters (AgN-DNAs) are promising fluorophores in the biological tissue transparency windows. Hundreds of NIR-emissive AgN-DNAs have recently been discovered, but their structure–property relationships remain poorly understood. Here, we investigate 19 different far-red and NIR emissive AgN-DNA species stabilized by 10-base DNA templates, including well-studied emitters whose compositions and chiroptical properties have never been reported before. The molecular formula of each purified species is determined by high-resolution mass spectrometry and correlated to its optical absorbance, emission, and circular dichroism (CD) spectra. We find that there are four distinct compositions for AgN-DNAs emissive at the far red/NIR spectral border. These emitters are either 8-electron clusters stabilized by two DNA oligomer copies or 6-electron clusters with one of three different ligand compositions: two oligomer copies, three oligomer copies, or two oligomer copies with additional chlorido ligands. Distinct optical and chiroptical signatures of 6-electron AgN-DNAs correlate with each ligand composition. AgN-DNAs with three oligomer ligands exhibit shorter Stokes shifts than AgN-DNAs with two oligomers, and AgN-DNAs with chlorido ligands have increased Stokes shifts and significantly suppressed visible CD transitions. Nanocluster electron count also significantly influences electronic structure and optical properties, with 6-electron and 8-electron AgN-DNAs exhibiting distinct absorbance and CD spectral features. This study shows that the optical and chiroptical properties of NIR-emissive AgN-DNAs are highly sensitive to nanocluster composition and illustrates the diversity of structure–property relationships for NIR-emissive AgN-DNAs, which could be harnessed to precisely tune these emitters for bioimaging applications.

Graphical abstract: Electron count and ligand composition influence the optical and chiroptical signatures of far-red and NIR-emissive DNA-stabilized silver nanoclusters

Supplementary files

Article information

Article type
Edge Article
Submitted
07 jun 2023
Accepted
09 sep 2023
First published
11 sep 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2023,14, 11340-11350

Electron count and ligand composition influence the optical and chiroptical signatures of far-red and NIR-emissive DNA-stabilized silver nanoclusters

R. Guha, A. Gonzàlez-Rosell, M. Rafik, N. Arevalos, B. B. Katz and S. M. Copp, Chem. Sci., 2023, 14, 11340 DOI: 10.1039/D3SC02931J

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