Oligonucleotide probe array with electronic detection system
The present disclosure provides methods, device, and system for a hybridization assay to detect nucleic acid targets. The assay may use a probe array format with addressable microwells. Each microwell may retain a plurality of copies of one probe which may be complementary to a portion of a specific nucleic acid target. The plurality of copies of probes may be produced from a pooled library of probe sequences by amplification techniques, including, rolling circle amplification and emulsion-PCR. Detection of hybridization may rely on methods using ion-sensitive field effect transistor (ISFET) and optical detectors to detect signals indicating the presence of the nucleic acid targets.
1. A method for assaying a presence of a target nucleic acid in a sample, comprising:
(a) providing a chip comprising a sensor adjacent to a sample chamber, wherein the sample chamber retains a plurality of copies of a capture probe, wherein the capture probe is part of a library of a plurality of capture probes, wherein the plurality of copies of the capture probe are not attached to a surface of the sample chamber, directly or indirectly, via a covalent bond,
wherein the capture probe comprises:
1) a sequence of a nucleic acid fragment that is complementary to at least a portion of the target nucleic acid; and
2) a barcode sequence attached to a first end of the sequence of the nucleic acid fragment in 1);
(b) providing a sample in the sample chamber under conditions that permit the capture probe to selectively couple to a target nucleic acid in the sample, wherein the capture probe selectively couples to the target nucleic acid;
(c) detecting, by the sensor, at least one signal indicative of a presence or absence of the target nucleic acid in the sample chamber; and
(d) determining the presence or absence of the target nucleic acid in the sample.
2. The method of claim 1 , wherein the sensor is in an array of a plurality of sensors in the chip, wherein the sample chamber is in an array of a plurality of sample chambers in the chip, and wherein each of the plurality of sample chambers is adjacent to at least one sensor of the array of the plurality of sensors.
3. The method of claim 1 , wherein the target nucleic acid is a fragment of a first nucleic acid.
4. The method of claim 1 , further comprising prior to (a):
(a1) circularizing an adaptor-coupled capture probe template; and
(a2) amplifying the adaptor-coupled capture probe template to form a linear amplified concatamer molecule comprising a plurality of copies of the capture probe.
5. The method of claim 1 , wherein the barcode sequence is between 3 and 30 nucleotides in length.
6. The method of claim 1 , further comprising prior to (a):
(a1) delivering a single copy of a template for the capture probe or a single copy of a double-stranded nucleic acid comprising the capture probe into an aqueous microreactor in a water-in-oil emulsion, wherein the microreactor comprises a plurality of a primer capable of annealing to the capture probe, a single bead capable of binding to the template of the capture probe and amplifying a first copy of the capture probe which becomes attached to the bead, and an amplification reaction solution containing reagents necessary to perform nucleic acid amplification;
(a2) subjecting the microreactor to a nucleic acid amplification reaction under conditions that yield the first copy of the capture probe;
(a3) repeating step (a2) multiple times; and
(a4) breaking the water-in-oil emulsion and producing multiple copies of the capture probe attached to the bead.
7. The method of claim 1 , wherein the sample comprises a plurality of target nucleic acid molecules, including the target nucleic acid.
8. The method of claim 7 , wherein the sensor is part of an array of a plurality of sensors, wherein each of the plurality of sensors detects the presence or absence of at least one of the plurality of target nucleic acid molecules, and wherein each sensor of the array of the plurality of sensors is individually addressable.
9. The method of claim 8 , wherein each capture probe comprises:
1) a sequence of a nucleic acid fragment that is complementary to a portion of one of the target nucleic acids; and
2) a barcode sequence attached to a first end of the sequence of the nucleic acid fragment;
and wherein (d) comprises:
(d1) decoding the barcode sequence of the capture probe retained at the corresponding sample chamber associated with the individually addressable sensor.
10. The method of claim 1 , wherein the chip comprises an additional sensor, wherein the sample comprises the target nucleic acid and an additional target nucleic acid, and wherein the additional sensor detects the additional target nucleic acid.
11. The method of claim 10 , wherein the additional sensor is adjacent to an additional sample chamber, wherein the additional sample chamber is configured to retain a plurality of copies of an additional capture probe, wherein the additional capture probe selectively couples to the additional target nucleic acid.
12. The method of claim 1 , wherein the sensor comprises an ion-sensitive field effect transistor (ISFET).
13. The method of claim 1 , wherein the sensor comprises a chemically-sensitive field effect transistor (chemFET).
14. The method of claim 1 , wherein the at least one signal comprises a change of pH.
15. A system for assaying a presence of a target nucleic acid in a sample, comprising:
(a) a chip comprising a sensor adjacent to a sample chamber, wherein the sample chamber is configured to retain the sample having the target nucleic acid and a plurality of copies of a capture probe, wherein the capture probe selectively couples to the target nucleic acid, wherein the plurality of copies of the capture probe are not attached to a surface of the sample chamber via a covalent bond, and wherein the sensor detects at least one signal from the sample, which at least one signal is indicative of a presence or absence of the target nucleic acid;
(b) a computer processor coupled to said chip and programmed to (i) measure the at least one signal while subjecting the chip in contact with the sample; and (ii) determine the presence or absence of the target nucleic acid in the sample.
16. The system of claim 15 , wherein the sensor is in an array of a plurality of sensors in the chip, wherein the sample chamber is in an array of a plurality of sample chambers in the chip, wherein each of the plurality of sample chambers is adjacent to at least one sensor of the array of the plurality of sensors, and wherein each sensor is individually addressable.
17. The system of claim 16 , wherein the computer processor is further programmed to (iii) map the array of individually addressable sensors; and (iv) when the capture probe contains a barcode sequence, to associate the barcode sequence with the corresponding individually addressable sensor.
18. The system of claim 15 , wherein the sensor is ion-sensitive filed effect transistor (ISFET), chemically-sensitive filed effect transistor (chemFET), or optical sensor.