In this article, we report a detailed characterization of C 12-based templates designed for creation of larger NA assemblies. Importantly, NA template sequence can be varied to produce fluorescent silver clusters of distinct optical properties. It is especially exciting because AgNCs can be naturally integrated with NA assemblies and NA assemblies can be tracked with AgNCs formation. Additionally, AgNCs are more resistant to photobleaching than widely used organic dyes, quantum dots, or fluorescent proteins, which makes these structures suitable for a plethora of practical applications, including optoelectronics and nanophotonics. With discrete states, the nanoclusters resemble molecular-like behavior with strong fluorescence observed in the visible-near IR range of the spectrum. In this “few atoms” size regime, the continuous density of states breaks up into discrete energy levels in the nanoclusters. Unique optical properties of AgNCs originate from their size. The resultant silver nanoclusters are only a few atoms in size. DNA protects the metallic core of the clusters and also determines the size and geometry of the AgNCs, which in turn dictates the optical properties and stability of the nanoclusters.

DNA oligonucleotides have been widely utilized for making AgNCs (reviewed in ). AgNCs cannot exist on their own-they have to be stabilized with capping agents that (1) limit their size, (2) stabilize nanoclusters, and (3) modify their electronic properties. Silver nanoclusters (AgNCs) represent a family of such novel functionalities. One example is the use of DNA template to arrange gold nanoparticles in a plasmonic linear array. NA nanotechnology opens large prospects for practical applications of novel materials design, diagnostics, and nanomedicine.īesides being used as architectural elements for construction of complex nanostructures, NA can be utilized as scaffolds for hosting various functionalities including moieties with unique optical, electronic, and magnetic properties. All these combined properties of NA provide a remarkable control over the versatile molecular structures that they can be programmed to assemble. Additional flexibility is added by the architectural elements of NA that employ tertiary interactions, such as kissing loops, loop receptor interactions, paranemic motifs, G-quadruplexes, and i-motifs, just to name a few. The NA nanotechnology toolbox utilizes not only traditional DNA and RNA bases but also their chemical analogs and backbone modifications, for example peptide nucleic acid (PNA). The progress already made in the field makes nucleic acid molecules very promising candidates for fabrication of complex shapes and functional structures at the nanoscale. The field of nucleic acid (NA) nanotechnology has brought various designs of materials and devices created with facilitation of nucleic acids both DNA and RNA. We also compare properties of silver nanoclusters, which were incorporated into a dimeric structure-a first step towards a larger assembly. A new population of “blue” emitting clusters forms only when ssDNA templating sequence is placed on the 5′ end of the double-stranded core. The addition of double-stranded DNA core, required for the larger assemblies, changes optical properties of the silver nanoclusters by adding a new population of clusters emitting in “green”.

AgNCs synthesized on a single “basic” templating element, (dC) 12, emit in “red”.

We observe differences between designs containing the same AgNC templating sequence-twelve consecutive cytosines, (dC) 12. The effects of close proximity of the double-stranded DNA, the directionality of templating single-stranded sequence, and conformational heterogeneity of the template are presented. In this study, we explore the properties of AgNCs manufactured on a short DNA sequence-an individual element designed for a construction of a larger DNA-based functional assembly. Only a few atoms in size, the properties of AgNCs can be tuned using a variety of templating DNA sequences, overhangs, and neighboring duplex regions. Besides being a passive carrier of genetic information, DNA can also serve as an architecture template for the synthesis of novel fluorescent nanomaterials that are arranged in a highly organized network of functional entities such as fluorescent silver nanoclusters (AgNCs).

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