Multivalent binding composition for nucleic acid analysis
Multivalent binding compositions including a particle-nucleotide conjugate having a plurality of copies of a nucleotide attached to the particle are described. The multivalent binding compositions allow one to localize detectable signals to active regions of biochemical interaction, e.g., sites of protein-protein interaction, protein-nucleic acid interaction, nucleic acid hybridization, or enzymatic reaction, and can be used to identify sites of base incorporation in elongating nucleic acid chains during polymerase reactions and to provide improved base discrimination for sequencing and array based applications.
1. A method for analyzing a target nucleic acid sequence in situ, the method comprising:
(a) providing a cell or a tissue comprising a plurality of nucleic acid molecules, wherein said plurality of nucleic acid molecules comprises said target nucleic acid sequence;
(b) contacting a subset of said plurality of nucleic acid molecules with a detectable nucleotide conjugate under conditions suitable to form a binding complex between (i) at least two nucleotide moieties of said detectable nucleotide conjugate and (ii) at least one nucleotide of each of at least two of said target nucleic acid sequence of said plurality of nucleic acid molecules within said cell or said tissue, wherein said subset of said plurality of nucleic acid molecules is primed;
(c) detecting said binding complex; and
(d) performing (b) to (c) for at least two other nucleotides of said at least two of said target nucleic acid sequence of said plurality of nucleic acid molecules, thereby identifying said target nucleic acid sequence.
2. The method of claim 1 , wherein said cell or said tissue is immobilized to an interior surface of a flow cell.
3. The method of claim 2 , wherein said interior surface of said flow cell comprises one or more hydrophilic polymer layers.
4. The method of claim 3 , wherein said one or more hydrophilic polymer layers comprises a polymer comprising polyethylene glycol (PEG).
5. The method of claim 4 , wherein said one or more hydrophilic polymer layers comprises a branched polymer.
6. The method of claim 3 , wherein said one or more hydrophilic polymer layers comprises a branched polymer.
7. The method of claim 2 , wherein said interior surface has a water contact angle comprising less than or equal to 45 degrees.
8. The method of claim 1 , further comprising permeabilizing said tissue or lysing said cell prior to said contacting in (b).
9. The method of claim 2 , wherein an image of said interior surface exhibits a contrast-to-noise ratio (CNR) of greater than or equal to about 10 when said CNR is measured by:
(a) contacting said interior surface with a fluorescently labeled nucleotide molecule comprising a nucleic acid sequence that is complementary to at least a portion of a capture oligonucleotide immobilized to said interior surface; and
(b) following (a), imaging said interior surface using an inverted microscope and a camera under non-signal saturating conditions while said interior surface is immersed in a buffer.
10. The method of claim 1 , wherein said identifying said target nucleic acid sequence in (d) is performed with an accuracy of base-calling that is characterized by a Q-score of greater than 25 for at least 80% of nucleotides identified.
11. The method of claim 1 , further comprising determining a spatial location of said target nucleic acid sequence within said cell or said tissue.
12. The method of claim 1 , further comprising determining a cell type of said cell based, at least in part, on said identifying said target nucleic acid sequence in (d).
13. The method of claim 1 , further comprising determining a tissue type of said tissue based, at least in part, on said identifying said target nucleic acid sequence in (d).
14. The method of claim 1 , wherein said detectable nucleotide conjugate comprises:
(a) a common core; and
(b) said at least two nucleotide moieties coupled to said common core, wherein said common core comprises a polymer, a micelle, a liposome, a microparticle, a nanoparticle, or a quantum dot.
15. The method of claim 14 , wherein said common core is spheroidal.
16. The method of claim 14 , wherein said detectable nucleotide conjugate further comprises a detectable moiety.
17. The method of claim 16 , wherein said detectable moiety is coupled to said common core.
18. The method of claim 1 , wherein in (b) said detectable nucleotide conjugate is included in a mixture of a plurality of detectable nucleotide conjugates, wherein each of said plurality of detectable nucleotide conjugates comprises different types of nucleotide moieties from each other.
19. The method of claim 18 , wherein said different types of said nucleotide moieties comprise at least three different types of said nucleotide moieties.
20. The method of claim 1 , wherein said at least two nucleotide moieties do not comprise a blocking group coupled thereto.
21. The method of claim 1 , wherein said plurality of nucleic acid molecules comprises a blocking group sufficient to prevent incorporation of said at least two nucleotide moieties into said at least two of said target nucleic acid sequence.
22. The method of claim 1 , wherein said tissue is a cancerous tissue.
23. The method of claim 1 , wherein said cell is a cancer cell.
24. The method of claim 1 , wherein said detecting said binding complex comprises imaging said cell or said tissue us in one or more image sensors.
25. The method of claim 24 , wherein said one or more image sensors comprises a photodetector array.
26. The method of claim 1 , further comprising washing said cell or said tissue following (c) to remove said detectable nucleotide conjugate from said cell or said tissue.