Co-detection and digital quantification of bioassay
The present invention provides methods and devices for detecting and quantifying multiple biomolecules at single-molecule level using an integrated droplet microfluidic system. In one embodiment, the present invention provides real-time and digital measurement of multiple biomolecules in a sample, thereby quantifying multiple biomolecules in an absolute and simultaneous manner. In one embodiment, the present invention provides a diagnostic method for a disease, comprising real-time and digital measurement of multiple biomolecules in a sample using the method or device described herein.
1. A method for real-time and digital count of cells or exosomes containing target biomolecules in a sample containing said cells or exosomes, comprising the steps of:
a) providing to a droplet generator said sample and reagents suitable for said method;
b) generating droplets with said droplet generator, wherein some droplets contain said reagents and said cells or exosomes;
c) allowing some of said reagents to lyse said cells or exosomes to release said target biomolecules, and then some of said reagents to label said target biomolecules, producing fluorescent signals;
d) spreading the droplets in a one-layer configuration in a droplet storage chamber, wherein the droplet storage chamber comprises rows of anchoring structures for anchoring the droplets to pre-determined positions in the droplet storage chamber;
e) capturing an image of the droplets in the droplet storage chamber by a microscopic camera and detecting fluorescent signals from all droplets.
2. The method of claim 1 , wherein in step b) each of said some droplets contains no more than one copy of the target biomolecules of the same type.
3. The method of claim 1 , wherein the target biomolecules to be labelled in step c) are of the same type or different types.
4. The method of claim 1 , wherein the method detects 1-10 types of target biomolecules.
5. The method of claim 1 , wherein said target biomolecules are selected from the group consisting of nucleic acids, peptides, proteins, enzymes, viruses and microorganisms.
6. The method of claim 5 , wherein said nucleic acids are selected from the group consisting of coding DNA, non-coding DNA, messenger RNA, ribosomal RNA, micro-RNA and transfer RNA.
7. The method of claim 5 , wherein step (e) is performed continuously or intermittently when the target biomolecules are being labelled in step (c).
8. The method of claim 7 , wherein the droplets collected are introduced to a droplet sorting unit to select droplets containing a particular type of target biomolecules or having particular properties.
9. The method of claim 1 , wherein steps (c), (d) and (e) are performed concurrently to detect fluorescent signals in real time.
10. The method of claim 1 , wherein the method further comprises a step of collecting the droplets after any one of steps (c)-(e).
11. The method of claim 1 , wherein the droplets collected are disrupted to obtain a suspension comprising labelled target biomolecules.
12. The method of claim 1 , wherein the droplet generator comprises a structure selected from the group consisting of a flow focusing structure, a cross flowing structure, a co-flowing structure, a step emulsion structure and a microchannel emulsification structure.
13. The method of claim 1 , wherein the sample and reagents are introduced to the droplet generator through the same inlet or different inlets.
14. The method of claim 1 , wherein fluorescent signals are detected by a charge-couple device.
15. The method of claim 1 , wherein the droplets have a diameter in the range of 5 μm to 200 μm.
16. The method of claim 1 , wherein the quantity of droplets generated ranges from several hundreds to several millions.
17. The method of claim 1 , wherein the total number of said target biomolecules is indicative of the severity or lack of a disease.