Microfluidic Droplet Multiplexing for Nucleic Acid Analysis

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Solution Overview

Problem

Current PCR technologies face challenges in multiplexing, particularly in real-time PCR, due to limited spectral resolution of fluorophores, leading to restricted capacity for detecting multiple targets simultaneously, and digital PCR methods struggle with stochastic sampling bias and polymerase errors, resulting in inefficiencies and inaccuracies in nucleic acid analysis.

Innovation Solution

The method involves forming microfluidic droplets containing a single nucleic acid template and multiple primer pairs specific for different target sites, with probes that hybridize to amplicons, allowing for simultaneous amplification and detection of multiple targets in a single reaction, while excluding polymerase errors and optimizing probe concentrations for efficient multiplexing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple primer pairs are combined in a single qPCR reaction for multiplexing, then the capacity to detect multiple targets simultaneously is improved, but the thermodynamic efficiencies and chemical kinetics change, requiring extensive troubleshooting and optimization

Engineering Contradiction:
Improvemultiplexing capacityVSAvoidoptimization complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention divides the multiplexing problem into two independent stages: (1) pre-amplification of multiple targets using separate primer pairs in individual reactions, and (2) detection of all amplicons using a single fluorescent probe in a shared reaction. This segmentation eliminates the need to optimize multiple primer-probe combinations simultaneously, as each target is amplified independently before the final detection step.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention extracts the primer-specific functions into the first amplification stage, where each target is amplified by its dedicated primer pair. The detection function is then extracted into the second stage, where a universal fluorescent probe detects all amplicons. This separation removes the conflicting requirements of maintaining specific primer thermodynamics while accommodating multiple targets in a single reaction.

Inventive Principle:
Principle #2Taking out (Extraction)

2Adaptability or versatility

If the number of fluorophores is increased to detect more targets in real-time PCR, then the multiplexing capacity is improved, but the spectral resolution of common fluorophores limits detection to only 4 colors

Engineering Contradiction:
Improvemultiplexing capacityVSAvoidspectral resolution limitation
Core Design Contradiction:
Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The invention introduces a universal fluorescent probe as an intermediary that does not distinguish between different targets during detection. Instead of using multiple fluorophores with overlapping spectra, a single probe binds to all amplicons and generates a unified signal. The differentiation of targets is achieved through the presence or absence of specific amplicons rather than through spectral discrimination, thereby overcoming the 4-color limitation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention replaces the optical discrimination mechanism (spectral resolution of fluorophores) with a molecular recognition mechanism (specific hybridization of probes to amplicons). Instead of relying on the physical property of light emission at different wavelengths, the system uses the chemical specificity of nucleic acid hybridization to identify different targets, enabling multiplexing beyond the spectral limits of available fluorophores.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If digital PCR is used to avoid interpreting fluorescence intensity and non-exponential amplification, then measurement accuracy is improved, but stochastic sampling bias and polymerase errors still affect analysis efficiency

Engineering Contradiction:
Improvequantification accuracyVSAvoidanalysis efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The invention performs preliminary amplification of all target sequences before the final detection step. By pre-amplifying multiple targets in separate reactions and then pooling the products for simultaneous detection, the system ensures that sufficient amplicon material is available for accurate measurement, reducing the impact of stochastic sampling bias while maintaining the quantitative accuracy benefits of digital PCR.

Inventive Principle:
Principle #10Preliminary action

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 enables increased amplicon yield and reduced DNA consumption, improves multiplexing capacity, and enhances the accuracy of nucleic acid analysis by minimizing bias and detecting multiple targets with high sensitivity and specificity.

Implementation Method 1

The droplet also includes reagents for conducting a PCR reaction

Methodology Applied
Scientific EffectPCR amplification: Enzyme

Implementation Method 2

The probe is specific for an amplicon produced in the droplet

Methodology Applied
Scientific EffectHybridization: Absorption (physical)

Data Source

PatentEP2986762B1Digital analyte analysis
Publication Date: 2019.11.06 BIO RAD LABORATORIES INC
  • EP2986762B1 patent drawingFigure 1~2
  • EP2986762B1 patent drawingFigure 3A~3C
  • EP2986762B1 patent drawingFigure 4A~4C

AI summary

The invention generally relates to detecting target molecules.