Methods of analyte detection
Disclosed herein are methods and systems for detection and discrimination of optical signals from a densely packed substrate. These have broad applications for biomolecule detection near or below the diffraction limit of optical systems, including in improving the efficiency and accuracy of polynucleotide sequencing applications.
1. A method for processing a plurality of analytes at a reduced error rate of less than 3% for at least 19 cycles, the method comprising:
a. providing said plurality of analytes disposed adjacent to N spatially separate regions of a substrate;
b. performing a plurality of cycles of probe binding to at least a subset of said plurality of analytes and imaging of at least a subset of said plurality of analytes, wherein said plurality of cycles comprises said at least 19 cycles, wherein a cycle of said plurality of cycles comprises:
i. bringing an analyte of said plurality of analytes in contact with a probe comprising an optically detectable label, to permit said probe to couple to said analyte;
ii. imaging said substrate using an imaging system, wherein said imaging system comprises at least 2 pixels/μm 2 , to detect an optical signal from said optically detectable label of said probe coupled to said analyte to generate an image of one or more observed optical signals that are digitized as bits of information, said bits of information comprising one or more parity bits of information; and
c. using an error correction algorithm to process said bits of information, to generate decoded signal sequences corresponding to at least said subset of said plurality of analytes, which decoded signal sequences are generated at said error rate less than 3% for at least 19 cycles.
2. The method of claim 1 , wherein said digitizing said observed optical signal sequences expands a measure of dynamic range for detecting said at least said subset of said plurality of analytes.
3. The method of claim 1 , wherein an analyte of said plurality of analytes is a nucleic acid molecule.
4. The method of claim 1 , wherein an analyte of said plurality of analytes is a protein or a polypeptide.
5. The method of claim 1 , wherein said probe comprises a nucleotide analog.
6. The method of claim 1 , wherein said probe comprises a polynucleotide.
7. The method of claim 1 , wherein said probe comprises a polypeptide.
8. The method of claim 7 , wherein said polypeptide comprises an antibody.
9. The method of claim 1 , wherein said performing said plurality of cycles of probe binding to at least a subset of said plurality of analytes comprises using an enzyme to couple said probe to said analyte.
10. The method of claim 9 , wherein said analyte is a polynucleotide, said probe is a nucleotide, and said enzyme is a polymerase.
11. The method of claim 1 , wherein a plurality of probes comprising said probe are contacted with said plurality of analytes in a predetermined order.
12. The method of claim 11 , wherein said predetermined order is generated by a computer.
13. The method of claim 11 , wherein said predetermined order is digitized to generate one or more expected signal sequences.
14. The method of claim 13 , wherein said decoded signal sequences are generated based on said expected signal sequences.
15. The method of claim 1 , wherein a plurality of probes comprising said probe are contacted with said plurality of analytes in a random order.
16. The method of claim 1 , wherein said plurality of analytes are disposed on said substrate at a density such that said optical signal from said detectable label is imaged on more than one pixel of said imaging system.
17. The method of claim 1 , wherein said optical signal is a dark level.
18. The method of claim 1 , wherein said probe is conjugated directly to said detectable label.
19. The method of claim 1 , wherein said probe is bound to another probe conjugated to said detectable label.