Formation and Structure of Fluorescent Silver Nanoclusters at Interfacial Binding Sites Facilitating Oligomerization of DNA Hairpins

Abstract

Fluorescent, DNA‐stabilized silver nanoclusters (DNA‐AgNCs) are applied in a range of applications within nanoscience and nanotechnology. However, their diverse optical properties, mechanism of formation, and aspects of their composition remain unexplored, making the rational design of nanocluster probes challenging. Herein, a synthetic procedure is described for obtaining a high yield of emissive DNA‐AgNCs with a C‐loop hairpin DNA sequence, with subsequent purification by size‐exclusion chromatography (SEC). Through a combination of optical spectroscopy, gel electrophoresis, inductively coupled plasma mass spectrometry (ICP‐MS), and small‐angle X‐ray scattering (SAXS) in conjunction with the systematic study of various DNA sequences, the low‐resolution structure and mechanism of the formation of AgNCs were investigated. Data indicate that fluorescent DNA‐AgNCs self‐assemble by a head‐to‐head binding of two DNA hairpins, bridged by a silver nanocluster, resulting in the modelling of a dimeric structure harboring an Ag12 cluster.

Studies on the interactions of Ag(i) with DNA and their implication on the DNA-templated synthesis of silver nanoclusters and on the interaction with complementary DNA and RNA sequences

“…59 Another interesting head-tohead binding of two DNA hairpins, bridged by a silver nanocluster, resulting in the modelling of a dimeric structure harboring an Ag 12 cluster. 53 Overall, these values agree well with the stoichiometries determined in our work for the long sequences, suggesting that the 1 : 25 complex depicted in Fig. 4a-c would correspond to a dimer.…”

“…The nature of the DNA-stabilized AgNCs was also studied by means of SE-HPLC. 44,52,53 For 12yellow and 12IR ( Fig. 8) and…”

Photoluminescent nanocluster-based probes for bioimaging applications

“…DNA and artificial DNA-like molecules, e.g., peptide nucleic acid (PNA), locked nucleic acid (LNA), and phosphoramidate morpholino oligomers (MORF), have been investigated over the last several years as a class of powerful templates for synthesizing metal NCS with improved photophysical and biomedical performance [79][80][81][82][83][84][85]. The possibility to exploit several advantages, including tailored sequences and structures, tuneable size, and the presence of multiple coordination sites for metal ions, made DNA strands very appealing for the design of a wide variety of hybrid NC-based systems, with a proper modulation of their luminescence properties.…”

Hg2+ Detection with Rational Design of DNA-Templated Fluorescent Silver Nanoclusters

“…DNA-templated silver nanoclusters that are comprised of only a few silver atoms display attractive optical properties. Measuring less than two nm in size, AgNCs are highly luminescent [1,2]. The unique optical properties of AgNCs stem from their intermediate nature between atomic and bulk metal [3].…”

“…(B) Stern-Volmer, F 0 /F vs. C Hg2+ , plot indicative of unusual quenching behavior of AgNC@HL-T 0 C 13 fluorescence due to Hg 2+ . Red solid line is the fit of data points at low Hg 2+ concentrations (0-2 µM)to Equation (1) and blue solid line is the fit to Equation(2). The inset in Figure4Bshows an enlarged region of low Hg 2+ concentrations between 0-2 µM.…”