Isothermal Amplification Low Salt Molecular Crowding
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Solution Overview
Problem
Current whole-genome amplification methods face challenges with low sequence coverage bias and high levels of non-specific background amplification, especially when amplifying trace amounts of target DNA, often resulting in incomplete amplification and the formation of undesirable chimeric products.
Innovation Solution
The use of molecular crowding reagents, such as polyethylene glycol, under low salt conditions in conjunction with a primer having a low melting temperature, in an isothermal amplification method to optimize the melting temperature of the primer, allowing for efficient and unbiased amplification of target nucleic acids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional whole-genome amplification methods are used, then amplification of target DNA can be achieved, but sequence coverage bias increases and non-specific background amplification occurs
Solution Approach 1:
The patent changes the salt concentration parameter from conventional high salt conditions to low salt conditions (10-30 mM), and introduces molecular crowding reagents to alter the reaction environment. This parameter change resolves the contradiction by enabling specific primer-template annealing while preventing non-specific amplification and reducing sequence coverage bias.
Solution Approach 2:
The patent uses molecular crowding reagents as intermediaries to modify the reaction environment. These reagents mediate between the primer and template DNA, facilitating specific annealing while preventing non-specific interactions, thereby improving both amplification reliability and sequence coverage uniformity.
2Quantity of substance
If amplification of trace amounts of DNA is performed, then sensitivity is improved, but incomplete amplification and dropouts in sequence coverage occur
Solution Approach 1:
The patent employs low salt conditions combined with molecular crowding reagents to optimize the reaction environment for trace DNA amplification. This parameter change enables complete and reliable amplification even from minimal input DNA by enhancing primer-template specificity and reducing non-specific background that would otherwise compete with the limited target DNA.
Solution Approach 2:
Molecular crowding reagents act as intermediaries that create a favorable environment for amplifying trace DNA. They mediate the interaction between primers and template DNA, ensuring that even minimal amounts of target DNA are efficiently amplified without dropouts or incomplete coverage.
3Stability of the object's composition
If high salt concentration is used, then primer stability is improved, but non-specific amplification and chimeric product formation increase
Solution Approach 1:
The patent inverts the conventional approach by using low salt conditions instead of high salt conditions. This parameter change, combined with molecular crowding reagents, maintains sufficient primer stability while dramatically reducing non-specific amplification and chimeric product formation that occur under high salt conditions.
Solution Approach 2:
Molecular crowding reagents serve as intermediaries that compensate for the reduced ionic strength. They provide the necessary stability for primer-template complexes under low salt conditions while preventing non-specific interactions and chimeric product formation that would otherwise occur.
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 enhances the reaction kinetics and sensitivity, reducing non-specific amplification and improving sequence coverage, enabling efficient amplification from trace amounts of DNA with reduced bias and fewer chimeric products.
Implementation Method 1
the salt concentration optimizes a melting temperature (Tm) of the primer at least 10° C. below the reaction temperature
Implementation Method 2
The complementary strand is assembled from deoxyribonucleoside triphosphates (dNTPs) by a DNA polymerase. The complementary strand synthesis proceeds in the 5′→3′ direction
Implementation Method 3
nucleic acid amplification methods are provided that utilize a molecular crowding reagent under low salt condition
Data Source
AI summary
Provided herein are methods and kits for isothermal nucleic acid amplifications that use a target nucleic acid template; a reaction mixture comprising a DNA polymerase having a strand displacement activity, a deoxyribonucleoside triphosphate (dNTP) mixture, a primer with a 3′ end and a 5′ end, a molecular crowding reagent, and a buffer solution for amplifying the target nucleic acid template. The buffer solution maintains a low salt concentration of the reaction mixture, and wherein the salt concentration results in a melting temperature (Tm) of the primer at least 10° C. below the reaction temperature. The amplification is effected under isothermal condition.