Due to their interesting properties, research on colloidal nanocrystals has moved in the last few years from fundamental research to first applications in materials science and life sciences. In this review some recent biological applications of colloidal nanocrystals are discussed, without going into biological or chemical details. First, the properties of colloidal nanocrystals and how they can be synthesized are described. Second, the conjugation of nanocrystals with biological molecules is discussed. And third, three different biological applications are introduced: (i) the arrangement of nanocrystal-oligonucleotide conjugates using molecular scaffolds such as single-stranded DNA, (ii) the use of nanocrystal-protein conjugates as fluorescent probes for cellular imaging, and (iii) a motility assay based on the uptake of nanocrystals by living cells.
Colloidal nanocrystal/DNA conjugates hold the promise of becoming powerful probes for biological diagnostics as well as versatile building blocks for nanotechnology. To fully realize this potential, it is important to precisely control the number of oligonucleotides bound to the nanocrystal. Here we demonstrate electrophoretic isolation of 5 and 10 nm gold nanocrystals bearing discrete numbers of single-stranded DNA (1−5). The potential use of these discrete conjugates in the fabrication of novel nanostructures is discussed.
The bottom-up spatial organization of potential nanoelectronic components is a key intermediate step in the development of molecular electronics. We describe robust 3-space-spanning DNA motifs that are used to organize nanoparticles in 2D. One strand of the motif ends in a gold nanoparticle; only one DNA strand is attached to the particle. By using two of the directions of the motif to produce a two dimensional crystalline array, one direction is free to bind gold nanoparticles. Identical motifs, tailed in different sticky ends enable the 2D periodic ordering of 5 nm and 10 nm diameter gold nanoparticles. KeywordsDNA self-assembly; 2D DNA arrays; Organizing Matter with DNA; Atomic Force Microscopy; Metallic Nanoparticles; Robust DNA Motifs Metallic and semiconductor nanoparticles exhibit quantized optical and electronic properties that might be exploited in the design of future nanoelectronic devices. 1-3 However, this application requires the deliberate and precise organization of nanoparticles into specific designed structural arrangements. The control of the structure of matter on the finest possible scale entails the successful design of both stiff intramolecular motifs and robust intermolecular interactions. The specificity of DNA base-pairing has provided a 'smart-glue' approach to programming interactions between particles via hybridization of specifically designed linker strands. 4,5 Previously, stiff motifs 6 based on branched DNA have been used to produce DNA structures with a variety of patterns that are visible in the AFM; these include stripes from double crossover (DX) molecules, 7 arrays with tunable cavities from DNA parallelograms, 8 and honeycombs from DX triangles. 9 DNA-functionalized 1.4 nm gold nanoparticles have been assembled into linear arrays forming parallel stripes on a 2D DNA striped scaffolding by self-assembly during scaffolding formation 10 and 6 nm gold nanoparticles with multiple DNA attachments have been fashioned into similar arrays by in situ hybridization to a pre-assembled scaffolding on a striped DX surface. 11 Sequenceencoded in situ assembly of 5 nm and 10 nm gold particles in alternating stripes has also been achieved. 12 While such linear nanoparticle arrays are of interest for some applications, * Address correspondence to this author at ned.seeman@nyu.edu. Supporting Information Available:The sequences of the molecules used and experimental methods. This material is available free of charge via the Internet at http://pubs.acs.org/. Our experience with honeycomb lattices demonstrates that cohesion by two sticky ends on each end of a DX molecule is more robust than a single sticky end; we were unable to obtain the honeycomb arrays if only a single sticky end was used. 9 We have built several motifs that span 3-space (e.g., 6-helix bundles 15 ); one of these motifs (termed a 3D-DX triangle) is based on Mao et al.'s tensegrity triangle, 16 but contains DX molecules, instead of single helices in each of its three domains (Fig. 1). It is possible to produce 2D lat...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.