Emulsion Microdroplet MDA-PCR Nucleic Acid Amplification
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Solution Overview
Problem
Existing droplet digital PCR techniques often require higher input DNA quantities and can introduce contaminating DNA during sorting, limiting their effectiveness in DNA library preparations and subsequent sequencing steps.
Innovation Solution
An improved emulsion droplet-based nucleic acid amplification method that uses Multiple Displacement Amplification (MDA) in conjunction with PCR, allowing for the detection, quantitation, and sorting of nucleic acids within emulsion microdroplets, which can contain cells, viruses, or free-floating nucleic acids, using techniques like microfluidics and fluorescence-activated cell sorting (FACS).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If droplet digital PCR techniques are used for nucleic acid amplification, then detection and quantitation can be achieved, but the quantity of target nucleic acid is insufficient for subsequent sequencing steps
Solution Approach 1:
The patent combines MDA and PCR amplification techniques within the same emulsion microdroplet system. The MDA reagents and PCR reagents are both introduced into the microdroplets, allowing sequential amplification reactions to occur in the same compartment, thereby increasing the final quantity of target nucleic acid while maintaining detection precision
Solution Approach 2:
The MDA amplification is performed as a preliminary step before PCR amplification within the microdroplet. This preliminary action generates sufficient template DNA that enables subsequent PCR to produce adequate quantities for sequencing, while the microdroplet containment preserves the digital PCR detection accuracy
2Productivity
If FACS is used to sort microdroplets, then nucleic acids can be sorted based on detection signals, but contaminating DNA is introduced that overwhelms the sorted DNAs of interest
Solution Approach 1:
The patent extracts the target nucleic acids from the contaminated sorted mixture by performing amplification reactions within isolated emulsion microdroplets. The microdroplet membrane acts as a barrier that separates the target DNA (amplified within the droplet) from contaminating DNA (present in the external sorting buffer), thereby extracting pure target sequences from the contamination
Solution Approach 2:
The patent segments the amplification reaction into isolated microdroplet compartments. Each microdroplet contains and protects its amplified target DNA separately, preventing contamination from other droplets or the sorting buffer. This segmentation allows FACS sorting to proceed efficiently while maintaining DNA purity through physical compartmentalization
3Reliability
If higher input DNA quantities are required for droplet PCR, then amplification can be more effective, but the method becomes less suitable for low-input samples
Solution Approach 1:
The patent merges MDA and PCR amplification in a sequential manner within the same microdroplet. The MDA step provides robust amplification that works effectively with low-input samples, generating sufficient template for the subsequent PCR step to produce high-quality amplification products, thereby achieving both low-input adaptability and amplification effectiveness
Solution Approach 2:
The patent changes the amplification parameters by using MDA conditions (isothermal, random hexamer priming) followed by PCR conditions (thermal cycling, specific primers). This parameter transition allows the system to first amplify low-input DNA efficiently under MDA conditions, then optimize for high-fidelity amplification under PCR conditions, accommodating both low-input samples and high effectiveness requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances the quantity of target nucleic acids available for sequencing, reduces contamination, and enables more efficient DNA library preparation by amplifying and sorting nucleic acids within microdroplets, improving the accuracy and throughput of nucleic acid analysis.
Implementation Method 1
Non-specific amplification techniques, such as Multiple Displacement Amplification (MDA), can be performed in the same emulsion microdroplet as Polymerase Chain Reaction (PCR)
Implementation Method 2
subsequent sequencing steps will benefit from greater quantities of input DNA than is currently provided by such techniques
Implementation Method 3
fluorogenic assay, such as Sybr staining of amplified DNA or TaqMan PCR
Implementation Method 4
encapsulating a sample, which may include a heterogeneous population of cells, viruses, and/or nucleic acids, in a plurality of emulsion microdroplets
Data Source
AI summary
The methods and systems described herein provide an improved emulsion droplet based nucleic acid amplification method, which allows nucleic acids contained in biological systems to be detected, quantitated and/or sorted based on their sequence as detected with nucleic acid amplification techniques, e.g., polymerase chain reaction (PCR). The nucleic acids can be free floating or contained within living or nonliving structures, including particles, viruses, and cells. The nucleic acids can include, e.g., DNA or RNA.