Cooperative Nucleic Acid Molecules for Primer-Dimer Suppression
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Solution Overview
Problem
Current nucleic acid amplification methods face challenges with primer-dimers, which lead to false negatives and false positives, and are limited in detecting mutants in high backgrounds, especially when using probe-based methods like Taqman or Molecular Beacons, as they can only detect one mutant in a background of 10 to 20 wild-type sequences.
Innovation Solution
The use of cooperative nucleic acid molecules, comprising a primer and a capture sequence linked via a non-extendable linker, where the capture sequence hybridizes downstream of the primer, preventing primer-dimer formation and enhancing specificity by maintaining primer proximity to the target, even at low melting temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional primers are used in nucleic acid amplification, then amplification can proceed, but primer-dimers form causing false negatives and false positives
Solution Approach 1:
The primer is divided into two separate functional components: a 5′ portion that binds to the target sequence and a 3′ portion that serves as the actual primer for extension. This segmentation prevents the primer from forming dimers while maintaining its ability to amplify the target sequence accurately.
Solution Approach 2:
A linker sequence is introduced as an intermediary element connecting the 5′ binding portion and the 3′ primer portion. This linker acts as a spacer that physically separates the functional regions, preventing inappropriate interactions between primers while allowing both functions to operate effectively.
2Measurement precision
If probe-based methods like Taqman or Molecular Beacons are used to detect mutants, then specificity is improved, but the ability to detect mutants in high backgrounds of wild-type sequences is limited
Solution Approach 1:
The segmented primer design allows the 5′ binding portion to provide high specificity through stable hybridization to the target, while the 3′ primer portion enables efficient extension. This separation allows the method to detect mutants even when present in very low quantities against a high background of wild-type sequences.
Solution Approach 2:
The method changes the thermodynamic parameters of primer binding by using a two-part design with different melting temperatures for the binding portion and primer portion. This allows optimization of binding strength and extension efficiency independently, improving detection sensitivity in high-background samples.
3Adaptability or versatility
If primers with low melting temperatures are used, then hybridization flexibility is improved, but primer-dimer formation increases
Solution Approach 1:
By segmenting the primer into a 5′ binding portion and a 3′ primer portion, each can be optimized independently for its specific function. The binding portion can have lower melting temperature for flexible hybridization, while the linker and primer portion structure prevents dimer formation even at lower temperatures.
Solution Approach 2:
The linker sequence serves as a physical barrier that prevents the 3′ ends of different primers from annealing to each other, thereby preventing dimer formation. This intermediary element allows the use of primers with lower melting temperatures without increasing dimer formation, as the linker blocks the interaction that would lead to dimers.
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 significantly reduces primer-dimer interference, allowing for accurate amplification and detection of target nucleic acids, even in high backgrounds, with improved specificity and sensitivity, as demonstrated by higher fluorescent signals and reduced primer-dimer amplification.
Implementation Method 1
the second nucleic acid sequence hybridizes to the target nucleic acid sequence downstream from the 3′ end of the first nucleic acid sequence
Data Source
AI summary
Disclosed are compositions and a method relating to amplifying and detecting nucleic acids.