Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving nucleic acid
Reexamination Certificate
2001-03-28
2004-06-15
Riley, Jezia (Department: 1637)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving nucleic acid
C435S007100, C435S007200, C536S023100, C536S024300, C536S024330, C536S025300
Reexamination Certificate
active
06750016
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to methods of detecting analytes, including nucleic acids and proteins, whether natural or synthetic, and whether modified or unmodified. The invention also relates to materials for detecting analytes, including nucleic acids and proteins, and methods of making those materials. The invention further relates to methods of nanofabrication. Finally, the invention relates to methods of separating a selected nucleic acid from other nucleic acids.
BACKGROUND OF THE INVENTION
The development of methods for detecting and sequencing nucleic acids is critical to the diagnosis of genetic, bacterial, and viral diseases. See Mansfield, E. S. et al.
Molecular and Cellular Probes,
9, 145-156 (1995). At present, there are a variety of methods used for detecting specific nucleic acid sequences. Id. However, these methods are complicated, time-consuming and/or require the use of specialized and expensive equipment. A simple, fast method of detecting nucleic acids which does not require the use of such equipment would clearly be desirable.
Colloidal gold-protein probes have found wide applications in immunocytochemistry [S. Garzon and M. Bendayan, “Colloidal Gold Probe: An Overview of its Applications in Viral Cytochemistry,” in “Immuno-Gold Electron Microscopy,” Ed. A. D. Hyatt and B. T. Eaton, CrC Press, Ann Arbor, Mich. (1993); J. E. Beesley, Colloidal Gold: A New Perspective for Cytochemical marking,” Oxford University Press, Oxford, (1989)]. These probes have been prepared by adsorbing the antibodies onto the gold surface from an aqueous solution under carefully defined conditions. The complexes produced in this manner are functional but suffer from several drawbacks: e.g., some of the protein desorbs on standing, liberating antibody into solution that competes with adsorbed antibodies for the antigen target; the activity is low since the amount adsorbed is low and some of the antibody denatures on adsorption; and the protein-coated particles are prone to self aggregation, especially in solutions of high ionic strength. An alternative means for preparing nanoparticle-protein probes has been described by J. E. Hainfeld, R. D. Leone, F. R. Furuya, and R. D. Powell (U.S. Pat. No. 5,521,289, May 28, 1996, “Small Organometallic Probes”). Typically, this procedure involves reduction of a gold salt in an organic solvent containing a triarylphosphine or mercapto-alkyl derivative bearing a reactive substituent, X, to give small nanoparticles (50-70 gold atoms) carrying X substituents on linkers bound to the surface through Au—P or Au—S bonds. Subsequently the colloidal solution is treated with a protein bearing a substituent Y that reacts with X to link the protein covalently to the nanoparticle. Work with these nanoparticle is limited by the poor water solubility of many proteins, which limits the range of protein-nanoparticle conjugates that can be utilized effectively. Also, since there are only a few gold atoms at the surface of these particles, the number of “capture” strands that can be bound to the surface of a given particle is very low.
A variety of methods have been developed for assembling metal and semiconductor colloids into nanomaterials. These methods have focused on the use of covalent linker molecules that possess functionalities at opposing ends with chemical affinities for the colloids of interest. One of the most successful approaches to date, Brust et al.,
Adv. Mater.,
7, 795-797 (1995), involves the use of gold colloids and well-established thiol adsorption chemistry, Bain & Whitesides,
Angew. Chem. Int. Ed. Engl.,
28, 506-512 (1989) and Dubois & Nuzzo,
Annu. Rev. Phys. Chem.,
43, 437-464 (1992). In this approach, linear alkanedithiols are used as the particle linker molecules. The thiol groups at each end of the linker molecule covalently attach themselves to the colloidal particles to form aggregate structures. The drawbacks of this method are that the process is difficult to control and the assemblies are formed irreversibly. Methods for systematically controlling the assembly process are needed if the materials properties of these structures are to be exploited fully.
The potential utility of DNA for the preparation of biomaterials and in nanofabrication methods has been recognized. In this work, researchers have focused on using the sequence-specific molecular recognition properties of oligonucleotides to design impressive structures with well-defined geometric shapes and sizes. Shekhtman et al.,
New J. Chem.,
17, 757-763 (1993); Shaw & Wang,
Science,
260, 533-536 (1993); Chen et al.,
J. Am Chem. Soc.,
111, 6402-6407 (1989); Chen & Seeman,
Nature,
350, 631-633 (1991); Smith and Feigon,
Nature,
356, 164-168 (1992); Wang et al.,
Biochem.,
32, 1899-1904 (1993); Chen et al.,
Biochem.,
33, 13540-13546 (1994); Marsh et al.,
Nucleic Acids Res.,
23, 696-700 (1995); Mirkin,
Annu. Review Biophys. Biomol. Struct.,
23, 541-576 (1994); Wells,
J. Biol. Chem.,
263, 1095-1098 (1988); Wang et al.,
Biochem.,
30, 5667-5674 (1991). However, the theory of producing DNA structures is well ahead of experimental confirmation. Seeman et al.,
New J. Chem.,
17, 739-755 (1993).
SUMMARY OF THE INVENTION
The invention provides methods of detecting nucleic acids. In one embodiment, the method comprises contacting a nucleic acid with a type of nanoparticles having oligonucleotides attached thereto (nanoparticle-oligonucleotide conjugates). The nucleic acid has at least two portions, and the oligonucleotides on each nanoparticle have a sequence complementary to the sequences of at least two portions of the nucleic acid. The contacting takes place under conditions effective to allow hybridization of the oligonucleotides on the nanoparticles with the nucleic acid. The hybridization of the oligonucleotides on the nanoparticles with the nucleic acid results in a detectable change.
In another embodiment, the method comprises contacting a nucleic acid with at least two types of nanoparticles having oligonucleotides attached thereto. The oligonucleotides on the first type of nanoparticles have a sequence complementary to a first portion of the sequence of the nucleic acid. The oligonucleotides on the second type of nanoparticles have a sequence complementary to a second portion of the sequence of the nucleic acid. The contacting takes place under conditions effective to allow hybridization of the oligonucleotides on the nanoparticles with the nucleic acid, and a detectable change brought about by this hybridization is observed.
In a further embodiment, the method comprises providing a substrate having a first type of nanoparticles attached thereto. The first type of nanoparticles has oligonucleotides attached thereto, and the oligonucleotides have a sequence complementary to a first portion of the sequence of a nucleic acid. The substrate is contacted with the nucleic acid under conditions effective to allow hybridization of the oligonucleotides on the nanoparticles with the nucleic acid. Then, a second type of nanoparticles having oligonucleotides attached thereto is provided. The oligonucleotides have a sequence complementary to one or more other portions of the sequence of the nucleic acid, and the nucleic acid bound to the substrate is contacted with the second type of nanoparticle-oligonucleotide conjugates under conditions effective to allow hybridization of the oligonucleotides on the second type of nanoparticles with the nucleic acid. A detectable change may be observable at this point. The method may further comprise providing a binding oligonucleotide having a selected sequence having at least two portions, the first portion being complementary to at least a portion of the sequence of the oligonucleotides on the second type of nanoparticles. The binding oligonucleotide is contacted with the second type of nanoparticle-oligonucleotide conjugates bound to the substrate under conditions effective to allow hybridization of the binding oligonucleotide to the oligonucleotides on the nanoparticles. Then, a third type of na
Letsinger Robert L.
Mirkin Chad A.
Park So-Jung
McDonnell & Boehnen Hulbert & Berghoff
Nanosphere Inc.
Riley Jezia
LandOfFree
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