Discrete Melt Analysis for dPCR Signal Discrimination
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Solution Overview
Problem
Current methods for digital polymerase chain reaction (dPCR) face challenges in accurately and efficiently performing melt analysis due to time-consuming data collection, non-specific amplification, and limitations in detecting multiple targets, particularly in distinguishing between positive and negative partitions with intermediate fluorescence intensities.
Innovation Solution
A method involving measuring signals from labeled duplex nucleic acids at temperatures below and above their predetermined melting points, without measuring at the exact melting point, to determine specific hybridization of target-specific probes, allowing for efficient discrimination between target and non-target sequences using cleavable probes and signal-generating labels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If melt analysis is performed by acquiring images at many different temperatures (35-70 unique temperatures) to generate complete melt profiles, then measurement precision of nucleic acid identification is improved, but loss of time increases significantly (image acquisition alone may take more than 10 minutes)
Solution Approach 1:
The patent divides the continuous temperature range into discrete temperature points for measurement. Instead of continuously scanning through 35-70 temperature points, the method selects specific discrete temperatures (e.g., below Tm and above Tm) to capture the essential melt transition information, significantly reducing measurement time while maintaining identification accuracy.
Solution Approach 2:
The patent applies partial action by measuring fluorescence at only two critical temperature points (below and above the melting temperature) rather than performing complete melt curves at multiple temperatures. This partial measurement approach captures sufficient information to distinguish specific from non-specific hybridization without the time cost of comprehensive melt analysis.
2Measurement precision
If DNA intercalating dyes and TaqMan probes are used for endpoint PCR quantification, then sensitivity of nucleic acid detection is improved, but object-generated harmful factors increase due to non-specific amplification producing false positive signals
Solution Approach 1:
The patent changes the detection parameter from endpoint fluorescence intensity alone to a combination of fluorescence intensity and temperature-dependent melt behavior. By measuring fluorescence at different temperatures (below and above Tm), the method distinguishes specific hybridization (which shows characteristic melt transitions) from non-specific amplification (which does not), thereby eliminating false positives while maintaining sensitivity.
Solution Approach 2:
The patent introduces feedback by using the temperature-dependent fluorescence signal to verify specific hybridization. The system measures fluorescence at multiple temperature points and uses the melt transition pattern as feedback to confirm that detected signals result from specific target hybridization rather than non-specific amplification, thus eliminating false positive signals.
3Device complexity
If classification of partitions relies solely on endpoint fluorescence intensity, then device complexity is reduced, but measurement precision decreases due to rain phenomenon causing intermediate intensity values that confound classification
Solution Approach 1:
The patent adds another dimension to the classification system by incorporating temperature as an additional parameter alongside fluorescence intensity. Instead of relying solely on single-point intensity measurements, the method measures fluorescence at multiple temperature points (below and above Tm), creating a two-dimensional classification space that resolves the rain phenomenon and enables accurate distinction between positive and negative partitions.
4Adaptability or versatility
If multiple fluorescence channels are used to detect multiple targets in dPCR, then adaptability of the detection system is improved, but device complexity increases due to limitations in available fluorescence channels
Solution Approach 1:
The patent makes a single fluorescence channel universal by using temperature-dependent measurements to distinguish different targets. Instead of requiring separate fluorescence channels for each target, the method uses the same fluorescence detector to measure signals at different temperatures, where each target's unique melting temperature serves as an identifier, enabling multi-target detection with a single channel.
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 reduces data collection time, enhances specificity, and improves the ability to detect multiple targets by utilizing discrete temperature measurements to differentiate between hybridized and denatured states of probes, thereby accurately identifying target nucleic acid sequences.
Implementation Method 1
measuring a first signal from a labeled duplex nucleic acid at a first temperature that is lower than the predetermined Tm of the labeled duplex nucleic acid; measuring a second signal from the labeled duplex nucleic acid at a second temperature that is higher than the predetermined Tm
Data Source
AI summary
Methods and reagent for determining the presence and/or for quantifying the amount of a target nucleic acid sequences in a sample are provided. In some aspects, the methods comprise performing a melt analysis by detecting, a signal from a probe at a temperature that is lower than the Tm of the probe and a signal at a temperature that is higher than the Tm of the probe, without detecting a signal at the Tm of the probe.