Absolute PCR Quantification via Sample Segmentation
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Solution Overview
Problem
Current real-time PCR methods lack the sensitivity, fidelity, accuracy, and reproducibility necessary for absolute quantification of low abundance nucleic acid targets, leading to unreliable results in clinical diagnostics due to variations in samples and technical limitations, making it difficult to compare results across different laboratories and times.
Innovation Solution
The method involves splitting a nucleic acid sample into small, isolated volumes and performing PCR in each volume, detecting amplification products, and using Poisson statistics to calculate the initial number of target molecules without the need for external calibration, allowing for direct absolute quantification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time PCR methods use external calibration curves for quantification, then quantification can be performed, but the results show wide variability and lack reliability due to assumptions about reaction efficiency
Solution Approach 1:
The invention divides the sample into multiple small isolated sub-volumes (nanoliter or picoliter scale) and performs PCR in each sub-volume separately. This segmentation allows direct counting of positive reactions without relying on external calibration curves, eliminating the variability and reliability issues associated with traditional real-time PCR quantification methods
Solution Approach 2:
The method uses the PCR reaction outcomes themselves to provide the quantification data through statistical analysis of positive/negative reactions. The system is self-sufficient and does not require external calibration standards or reference materials, making the quantification process independent and more reliable
2Measurement precision
If PCR reaction volume is reduced to small isolated volumes, then sensitivity and accuracy of quantification improve, but the complexity of the device and method increases
Solution Approach 1:
The invention uses multiple copies of the same PCR reaction setup in parallel (arrays of identical nanoliter/picoliter volumes). This allows the complex small-volume reactions to be performed simultaneously in many copies, maintaining high precision while managing complexity through standardization and parallelization
Solution Approach 2:
The invention changes the scale parameter of the PCR reaction volume from microliter to nanoliter/picoliter scale. This parameter change enables higher sensitivity and accuracy for low abundance targets while the array format manages the operational complexity
3Productivity
If fluorescence detection is used to monitor PCR amplification in real-time, then kinetic data can be obtained, but background fluorescence and noise prevent early detection of low abundance targets
Solution Approach 1:
By segmenting the sample into many small sub-volumes, the method increases the probability that sub-volumes containing low abundance targets will show detectable amplification. The segmentation amplifies the signal from rare targets while the large number of sub-volumes provides statistical power for detection
Solution Approach 2:
The method uses many parallel copies of the PCR reaction in small sub-volumes. This multiplicative approach increases the overall signal from low abundance targets across the array, enabling detection despite high background fluorescence in individual reactions
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 approach provides highly accurate and sensitive absolute quantification of nucleic acid targets, enhancing the reliability and consistency of PCR results, thereby improving clinical diagnostics and research capabilities.
Implementation Method 1
conducting the method of polymerase chain reaction (PCR) on said volumes, detecting PCR amplification products
Implementation Method 2
Quantification of an amplified target in 'real-time' PCR is based on measuring the reaction product by sampling its fluorescence in the reaction mix during the course of the amplification reaction
Data Source
AI summary
The present application provides methods and devices for absolute quantification of polymerase chain reaction target nucleic acids. In particular, the methods and devices of the present application provide for splitting a nucleic acid sample to be analyzed into small, isolated volumes, conducting the method of polymerase chain reaction (PCR) on said volumes, detecting PCR amplification products, analyzing said detected PCR amplification products, performing absolute quantification of the PCR target and presenting said quantification results.