Split Cycle Amplification for Short Nucleic Acid Quantification
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Solution Overview
Problem
Conventional PCR amplification of nucleic acid targets shorter than 30 nucleotides is challenging due to the requirement for primers that are 15 to 30 nucleotides in length, which limits the minimum amplicon length and efficiency, especially for AT-rich targets.
Innovation Solution
A method involving the use of forward and reverse amplification primers with a 3' hybridization region that hybridizes to the target DNA and optionally a 5' tail region, which allows for thermal cycling conditions with a first set of temperature cycles below 50 °C and a second set above, enabling efficient amplification of target DNA templates less than 90 nucleotides in length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PCR amplification is used for short nucleic acid targets, then the method is simple and widely applicable, but the amplification efficiency is poor and sensitivity is low for targets shorter than 30 nucleotides
Solution Approach 1:
The amplification process is divided into two distinct temperature regimes: a first set of cycles at lower annealing temperature (35-45°C) to facilitate primer binding to short targets, and a second set of cycles at higher annealing temperature (50-65°C) to optimize polymerase activity. This segmentation allows each phase to be optimized independently for its specific function.
Solution Approach 2:
The patent employs dynamic adjustment of thermal cycling parameters, specifically transitioning from lower to higher annealing temperatures between the first and second sets of cycles. This parameter change enables the system to overcome the conflicting requirements of primer binding (favored by lower temperatures) and polymerase efficiency (favored by higher temperatures).
2Reliability
If primer length is increased to improve hybridization stability, then annealing is more reliable, but the minimum amplicon length requirement increases beyond 30-60 nucleotides
Solution Approach 1:
By changing the annealing temperature parameter between the first and second cycle sets, the patent enables reliable hybridization of shorter primers (15-30 nucleotides) without requiring extended amplicons. The lower temperature in the first set compensates for the shorter primer length, while the higher temperature in the second set ensures efficient extension.
3Manufacturing precision
If higher annealing temperature is used to improve primer binding specificity, then amplification specificity increases, but primer binding to short targets becomes less efficient
Solution Approach 1:
The amplification process is segmented into two temperature phases: the first set of cycles uses lower annealing temperature (35-45°C) to maximize primer binding efficiency to short targets, while the second set uses higher annealing temperature (50-65°C) to ensure amplification specificity and prevent non-specific binding. Both phases are necessary to achieve both efficiency and specificity.
Solution Approach 2:
The patent employs periodic alternation between two distinct thermal conditions throughout the amplification process. The repeated cycling between lower and higher temperatures allows the system to periodically optimize for binding efficiency followed by specificity, achieving both goals through rhythmic parameter variation.
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 method effectively amplifies and quantifies short DNA templates, improving specificity and sensitivity by incorporating a 5' tail region that lengthens the amplicon, allowing higher temperature annealing and extension, thus overcoming the limitations of conventional PCR for short nucleic acid sequences.
Implementation Method 1
the amplification primers comprise a 3' hybridization region that hybridizes to the target DNA template and primes template directed extension
Implementation Method 2
incubating the mixture partitions under thermal cycling conditions suitable for amplification of the target DNA template by a polymerase chain reaction, wherein the thermal cycling conditions comprise a first set of temperature cycles and a second set of temperature cycles
Implementation Method 3
a forward and a reverse amplification primer, wherein the amplification primers comprise a 3' hybridization region that hybridizes to the target DNA template and primes template directed extension of the primer in the presence of the DNA dependent DNA polymerase
Data Source
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AI summary
Methods of detecting or quantifying short RNA or DNA molecules using split cycle amplification are provided.