Abstract
DNA serves as a versatile template for few-atom silver clusters and their organized self-assembly. These clusters possess unique structural and photophysical properties that are programmed into the DNA template sequence, resulting in a rich palette of fluorophores which hold promise as chemical and biomolecular sensors, biolabels, and nanophotonic elements. Here, we review recent advances in the fundamental understanding of DNA-templated silver clusters (AgN-DNAs), including the role played by the silver-mediated DNA complexes which are synthetic precursors to AgN-DNAs, structure–property relations of AgN-DNAs, and the excited state dynamics leading to fluorescence in these clusters. We also summarize the current understanding of how DNA sequence selects the properties of AgN-DNAs and how sequence can be harnessed for informed design and for ordered multi-cluster assembly. To catalyze future research, we end with a discussion of several opportunities and challenges, both fundamental and applied, for the AgN-DNA research community. A comprehensive fundamental understanding of this class of metal cluster fluorophores can provide the basis for rational design and for advancement of their applications in fluorescence-based sensing, biosciences, nanophotonics, and catalysis.
Highlights
Metal “nanoclusters” are the smallest of nanoparticles, consisting of only 2 to 102 metal atoms and possessing remarkable properties which are very nely tuned by cluster size, shape, and charge
This review focuses on the recent advances in fundamental understanding of AgN-DNAs, with a particular emphasis on the recent detailed studies of compositionally pure AgN-DNAs
Review advancements have been enabled by compositionally pure AgNDNAs isolated using HPLC53 or size-exclusion chromatography (SEC).[37,38,62]. These techniques separate different DNA complexes by exploiting variations in size and polarity that are induced by different silver products on the DNA template strands. (Methods for isolating AgN-DNAs using high performance liquid chromatography (HPLC) have been reviewed in detail previously.66) Puri cation prior to characterization is crucial because assynthesized solutions contain multiple dark and uorescent products, including Ag nanoparticles, AgN-DNAs and Ag+–DNA complexes, as supported by LC-tandem mass spectrometry (MS).[24,57]
Summary
Metal “nanoclusters” are the smallest of nanoparticles, consisting of only 2 to 102 metal atoms and possessing remarkable properties which are very nely tuned by cluster size, shape, and charge. This method is robust to varying solution compositions, stoichiometries, and speci c mixing/ heating.[7,8,11,49,50,51,52] In contrast to the simplicity of synthesis, achieving compositionally pure solutions of AgN-DNAs is more challenging because reduction forms a heterogeneous mixture of silver-bearing DNA products containing varying numbers of silver atoms, Ntot, and numbers of DNA strands, ns The majority of these products are non uorescent[53] and include clusters, Ag+–DNA complexes, and larger silver nanoparticles.[54,55] It is possible for a given DNA template to stabilize multiple different emissive cluster species,[56] as has been observed for up to 25% of randomly selected DNA template sequences.[57] Due to characterization of as-synthesized AgN-DNAs without puri cation and/or due to fragmentation during mass spectrometry (MS), early reports underestimated AgN-DNA sizes[8,11] or found no correlation of uorescence color with silver cluster size.[58] A lack of awareness of this heterogeneity continues to hinder accurate characterization of AgN-DNAs, and the assumption that the composition of AgN-DNAs is uncorrelated to the optical properties of these nanoclusters still persists.[59]. It is our intent to provide a comprehensive and current picture of the properties of AgNDNAs which is accessible to researchers from many backgrounds, in order to aid others in developing applications of these unique nanoclusters and to inspire new experimental and computational studies of their fundamental properties
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call