Patent Application
20140141211
(1) Technical Field
The present invention relates to DNA-based nanotechnology. More specifically, the present invention relates to a method for the creation of arbitrarily-shaped metal nanostructures using DNA and other nucleic acid scaffolds.
(2) Description of Related Art
DNA-based nanotechnology is a growing field. The specificity and combinatorial programmability of the Watson-Crick binding interactions between the subunits of DNA makes the molecule an ideal candidate for creating nanostructures of set patterns. The nanometer scale structural geometry of the DNA self-assembled nanostructures also provides an ideal building block for directed self-assembly of nanometer-scale materials with sub-nanometer precision and programmability. The resulting nanostructures created from nanometer-scale materials such as metals may be used to construct devices in the fields of nanoelectronics and nanophotonics.
Previously in the field, those of ordinary skill in the art have used electroless plating techniques to plate metal upon the self-assembled DNA nanostructures. However, the metal plating is uncontrolled and results in metallization of the entire DNA nanostructure scaffold. More recently, nanowires have been fabricated using DNA scaffolds. However, no other specific shapes of metal nanostructures have been created upon DNA scaffolds that are not constrained by the structure of the scaffold itself.
Additionally, those of ordinary skill in the art have only plated metal upon double-stranded DNA scaffolds. Previous methods have not incorporated arranging seed nuclei such as nanoparticles, single-stranded DNA or any other single-stranded nucleic acid in specific patterns upon a scaffold prior to plating a metal on the scaffold and thus create arbitrarily-shaped metal nanostructures that are not constrained by the DNA scaffold itself.
The ability to form patterns upon a scaffold upon which electro-less metal plating can be directed allows for higher precision in the formation of specifically-shaped metal nanostructures. Methods with controlled-growth processes allow for active selection of the dimensions, positions, and alignments of patterns on scaffolds to create the different shapes of the metal nanostructures. Such metal nanostructures may provide for novel uses in the field of nanoelectronics and nanophotonics. Other applications include quantum electronic devices based on quantized conductance, control of electronic properties of patterned materials, plasmonic materials for concentration of light, plasmonic materials for waveguiding, plasmonic materials for nonlinear optics, X-ray and short-wavelength optics, including waveguides and gratings, semiconductor metrology standards, nanometer-scale non-local energy transport, microwave and terahertz applications including field effect transistors and emitters, coupling to quantum dots to make composite materials and/or circuits and/or luminescence enhancement, bright tags through plasmon enhancement of dies or q-dots, plasmonic circuits for light manipulation, and surface adsorption chemical sensors, surface enhanced raman scattering, etc.
Therefore, a need exists in the art for a method for self-assembly of arbitrarily-shaped metal nanostructures that uses a specifically-placed pattern of a material upon a nucleic acid scaffold as a template for plating metal.
The present invention overcomes the aforementioned limitations and fills the aforementioned needs by providing methods for assembly of arbitrarily-shaped metal nanostructures.
In one aspect, the method comprises acts of fabricating a scaffold, patterning a first material on a scaffold, and plating a metal on the first material, whereby an arbitrarily-shaped metal nanostructure is created based on a pattern formed by the first material on the scaffold and whereby the metal nanostructure is not constrained by a shape of the scaffold itself.
In another aspect, the scaffold is fabricated from a material selected from a group consisting of a plurality of nucleic acids, DNA origami, DNA ribbons, two-dimensional DNA crystals, and three-dimensional DNA constructions.
In another aspect, the plurality of nucleic acids is selected from a group consisting of a charged nucleic acid strands, an uncharged nucleic acid strands, DNA, PNA, RNA, LNA, chemically modified DNA, nucleoside analogues, and combinations thereof.
In another aspect, the act of plating comprises an electro-less plating process.
In another aspect, the first material comprises a single-stranded material selected from a group consisting of single-stranded forms of DNA, RNA, LNA, PNA, a nucleoside analogue, a polymer, and combinations thereof.
In another aspect, the first material has a first end and second end.
In another aspect, the act of patterning the first material on the scaffold further comprises an act of attaching the first material with the scaffold so that the first material projects from the scaffold.
In another aspect, the act of attaching the first material to the scaffold comprises an attachment mechanism selected from a group consisting of attaching the first end of the first material with the scaffold, attaching the first end and the second end of the first material with the scaffold, and a combination thereof, whereby a plurality of conformations of the first material are projected from the scaffold.
In another aspect, the plurality of conformations is selected from a group consisting of single open strands, loops, closed rings, a series of interlocking rings, and locked knotted topologies.
In another aspect, the electro-less plating process further comprises using a 2+ cationic solution whereby the solution blocks the plating of metal on the scaffold and thereby allows plating of metal on the first material.
In another aspect, the method further comprises an act of placing the scaffold on a negatively charged surface.
In another aspect, the negatively charged surface comprises a material selected from a group consisting of muscovite mica, cleaned silicon dioxide, and a surface that has been modified to display negatively charged groups at a specific surface density.
In another aspect, the first material is a nanowire.
In another aspect, the nanowire comprises metal.
In another aspect, the first material comprises a plurality of nanoparticles.
In another aspect, the nanoparticle comprises a metal nanoparticle selected from a group consisting of gold, silver, molybdenum, nickel, copper, and commercially-available nanoparticles.
In another aspect, the nanoparticle further comprises a nucleic acid strand, wherein the nucleic acid strand further comprises a linker, whereby the linker will bind to a complementary nucleic acid pattern on the scaffold.
In another aspect, the act of fabricating the scaffold further comprises the act of incorporating a plurality of nanoparticle attachment linker sites on the scaffold.
In another aspect, the plurality of nanoparticle attachment linker sites is selected from a group consisting of biotin, primary amines, thiols, and commercially-available nanoparticle attachment linker sites.
In another aspect, the act of patterning the first material on the scaffold further comprises the act of attaching the first material with the plurality of nanoparticle attachment linker sites.
In another aspect, the metal is selected from a group consisting of gold, silver, platinum, copper, titanium, nickel, zinc, lead, uranium, iron, palladium, and a metal structure.
Another method according to the present invention comprises the acts of fabricating a DNA scaffold, selecting a sequence-specific DNA hook projecting from the DNA scaffold, fabricating a single-stranded DNA lantern strand, attaching one or more single-stranded DNA lantern strands with two or more sequence-specific DNA hooks projecting from the DNA scaffold and plating a metal on the single stranded DNA lantern strand whereby an arbitrarily-shaped metal nanostructure may be created based on a pattern formed by the nanoparticles attached with the single-stranded DNA lantern strands and whereby the metal nanostructure is not constrained by a shape of the scaffold itself.
In another aspect, the single-stranded DNA lantern strand further comprises one or more nanoparticle attachment linker sites.
In another aspect, the method comprises the acts of attaching one or more nanoparticles with the nanoparticle attachment linker sites and plating a metal on the nanoparticles whereby an arbitrarily-shaped metal nanostructure may be created based on a pattern formed by the nanoparticles attached with the nanoparticle attachment linker sites and whereby the metal nanostructure is not constrained by the shape of the scaffold itself.
In another aspect, the method comprises the acts of attaching one or more nanowires with the nanoparticle attachment linker sites and plating a metal on the nanowires whereby an arbitrarily-shaped metal nanostructure may be created based on a pattern formed by the nanowires attached with the nanoparticle attachment linker sites and whereby the metal nanostructure is not constrained by the shape of the scaffold itself.
In another aspect, the scaffold is fabricated by a material selected from a group consisting of a plurality of nucleic acids, DNA origami, DNA ribbons, two-dimensional DNA crystals, and three-dimensional DNA constructions.
In another aspect, the plurality of nucleic acids is selected from a group consisting of a charged nucleic acid strands, an uncharged nucleic acid strands, DNA, PNA, RNA, LNA, chemically modified DNA, nucleoside analogues, and combinations thereof.
In another aspect, the act of plating comprises an electro-less plating process.
In another aspect, the nanoparticle comprises a metal nanoparticle selected from a group consisting of gold, silver, molybdenum, nickel, copper, and commercially-available nanoparticles.
In another aspect, the plurality of nanoparticle attachment linker sites is selected from a group consisting of biotin, primary amines, thiols, and commercially-available nanoparticle attachment linker sites.
In another aspect, the metal is selected from a group consisting of gold, silver, platinum, copper, titanium, nickel, zinc, lead, uranium, iron, palladium, and a metal structure.
Finally, the present invention includes an arbitrarily-shaped metal nanostructures formed according to all methods described herein.
The objects, features and advantages of the present invention will be apparent from the following detailed descriptions of the preferred aspects of the invention in conjunction with reference to the following drawings, where:
The present invention relates to methods for creating self-assembled arbitrarily-shaped metal nanostructures. More specifically, the present invention relates to methods for self-assembly of arbitrarily-shaped metal nanostructure using patterns placed upon a nucleic acid scaffold. The following description, taken in conjunction with the referenced drawings, is presented to enable one of ordinary skill in the art to make and use the invention and to incorporate it in the context of particular applications. Various modifications, as well as a variety of uses in different applications, will be readily apparent to those skilled in the art, and the general principles, defined herein, may be applied to a wide range of aspects. Thus, the present invention is not intended to be limited to the aspects presented, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Furthermore, it should be noted that unless explicitly stated otherwise, the figures included herein are illustrated diagrammatically and without any specific scale, as they are provided as qualitative illustrations of the concept of the present invention.
(1) Introduction
In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without necessarily being limited to these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention.
The reader's attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All the features disclosed in this specification, (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
Furthermore, any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. Section 112, Paragraph 6. In particular, the use of “step of or “act of in the claims herein is not intended to invoke the provisions of 35 U.S.C. 112, Paragraph 6.
The description outlined below sets forth methods for self-assembly of arbitrarily-shaped metal nanostructure patterned on nucleic acid scaffolds. The methods herein use controlled-growth processes to actively select the dimensions, positions, and alignments of patterns to create different shapes of metal nanostructures. Three methods according to the present invention are individually addressable.
(2) Method for self-assembly of arbitrarily shaped metal nanostructures using single-stranded molecules patterned on nucleic acid scaffolds.
This method, as illustrated in
As shown in
Referring again to
In this method, the definition of electro-less plating is the deposition of metal from metal ions dissolved in aqueous solution without use of electrodes. During the electro-less plating process, the metal begins as an ion in solution, but when it is deposited, it gains the missing electrons and becomes a metal. The chemistry for reduction of the positive metal ions on an existing metal surface or a seed nucleus is the mechanism that deposits the metal on the surface. The plating metal could be a variety of metals, including gold, silver, platinum, copper, titanium, nickel, zinc, lead, uranium, iron, palladium, and a metal structure. A metal structure can be an alloy, a mixture of metals, or a layered composition of metal.
The electro-less plating process is performed in a solution containing a source of metal ions, a reducing agent, a surfactant, and a buffer (to create the proper pH). When using a DNA scaffold, a pH buffer with an approximate pH of 5 prevents denaturing and provides for optimal performance. The buffer comprise of a mixture of a salt species to generate cations, for example, sodium chloride to generate sodium ions, magnesium acetate or magnesium chloride to generate magnesium ions, and nickel acetate to generate nickel ions, etc. The buffer could also contain a metal ion chelator, such as ethylenediamine tetraacetic acid, to act as a buffer for metal concentrations. A typical buffer used with nucleic acid-based scaffolds is magnesium acetate or magnesium chloride with a tris acetate base to buffer the pH and optional ethylenediamine tetraacetic acid to buffer ion concentrations.
Different monovalent, divalent, or multi-valent cationic species such as sodium chloride, nickel acetate, ammonium acetate, potassium chloride, calcium chloride, lithium chloride, organic zwitterions such as 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), and ionic liquids could be used as buffers to control the rate and specificity of deposition. The pH, salt concentrations, and concentrations of the metal ion species during plating can be used to adjust the rate of deposition.
As a non-limiting example, during electro-less plating of gold using gold chloride in a magnesium solution, gold preferentially nucleates on single-stranded DNA versus double stranded. The method is most effective when the scaffold is deposited on Muskovite mica using a 2+ cation as a salt bridge. The use of a multi-valent solution allows for selective deposition of metal on the single stranded DNA during electro-less plating because the monovalent (+) or multivalent (2+) cations in the solution form a charged layer that acts as diffusion barrier covering the scaffold, preventing access by metal ions used in the electro-less metal plating process from attaching to the scaffold itself The metal ions can then selectively attach on the single-stranded material or on other projected materials that have a lower charge concentration in its vicinity. The scaffold can be also placed on a negatively charged surface such as muscovite mica, cleaned silicon dioxide, or some other surface that has been modified to display negatively charged groups at some specific surface density, which can be adjusted to control the rate and the selectivity of metal deposition.
Once the metal is deposited upon a single-stranded material as seed nuclei, one or more additional metals may be used to plate existing metallic structures. As many additional layers of metal may be plated as needed. The buffer used during the depositing of the first metal as seed nuclei on the single-stranded material can be different from the buffer used in the subsequent plating of metal upon the seed nuclei. Also, if using two metals that like to alloy, such as gold and silver, a layer of another metal may be placed in between the two metals to stop the alloying reaction.
(3) Method for self-assembly of arbitrarily shaped metal nanostructures using metal nanoparticles patterned on nucleic acid scaffolds.
This method, as illustrated in
There are a number of commercially-available metal nanoparticles. More commonly used metal nanoparticles are gold, silver, iron, molybdenum, nickel, and copper. Many other nanoparticles are suitable as long as the nanoparticle is small enough to reproduce a desired pattern with accuracy and there exists a suitable linker chemistry.
Another option is to coat the nanoparticles 200 first with a DNA strand that has a linker, as illustrated in
(4) Method for self-assembly of arbitrarily shaped metal nanostructures using sequence-specific DNA hooks patterned on nucleic acid scaffolds.
Another method may be used for the arrangement of nanoparticle linker sites upon a DNA scaffold with reduced constraints from the shape and structure of the scaffold itself, for example, the dimensions of scaffolds such as DNA tiles in DNA ribbons. As illustrated in
As illustrated in
As a non-limiting example, this method can be used to create gold nanowires on DNA ribbon. As illustrated in
The single-stranded DNA lantern strands 302 attach to the sequence-specific DNA hooks 300 via complementary sequence-specific binding regions 304 on the single-stranded DNA lantern strands 302 and sequence-specific binding regions 306 on the sequence-specific DNA hooks 300. This creates a string of binding regions down the scaffold 104 with approximately 2 nm inter-site spacing. To prevent spurious attachment, two different sequence-specific single-stranded DNA hooks (i.e., having different sequences) can be projected from two different tiles on the DNA ribbon (the tiles repeat periodically down the length of the ribbon).
Optionally, as illustrated in
After incubating using standard procedures known in the art, the DNA scaffold 104 with or without docked nanoparticles 200 can be deposited on a negatively charged surface 312, for example, a mica substrate, as illustrated in
The present application claims the benefit of priority of U.S. Provisional Patent Application No. 60/854,595, filed Oct. 26, 2006, entitled “Method for self assembly of arbitrary contiguous metal patterns on DNA Scaffolds” and U.S. Provisional Patent Application No. 60/922,919, filed Apr. 11, 2007, entitled “Method for self assembly of arbitrary contiguous metal patterns on DNA scaffolds.”
The Unites States Government has certain rights in this invention pursuant to Grant No. FA9550-04-1-0434 awarded by the Air Force Office of Scientific Research (AFOSR).
| Number | Date | Country | |
|---|---|---|---|
| 60854595 | Oct 2006 | US | |
| 60922919 | Apr 2007 | US |
