Linear Displacement Isothermal Amplification Primer Design
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Solution Overview
Problem
Current isothermal amplification methods, such as LAMP, face limitations in amplifying nucleic acid fragments less than 200 bp in length or with high/low GC content, leading to non-specific amplification and false positives due to complex primer design and strict target requirements.
Innovation Solution
The linear displacement isothermal amplification (LDIA) method uses a combination of external and internal primers, with an optional accelerating primer, to facilitate amplification at a constant temperature, simplifying primer design and maintaining sensitivity and specificity, capable of handling fragments of varying lengths and GC contents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If LAMP method is used for isothermal amplification, then temperature control requirement is reduced, but amplification efficiency deteriorates for fragments less than 200 bp or with extreme GC content
Solution Approach 1:
The patent modifies the primer structure parameters by introducing a three-part composition (external primer, internal primer, and loop primer) with specific Tm value ranges (50-70°C). This parameter optimization enables efficient amplification of fragments with extreme GC content (30-70%) and varying lengths (50-500 bp) under isothermal conditions, resolving the contradiction between ease of operation and amplification efficiency.
2Productivity
If multiple primer pairs with complex stem-loop structures are used in LAMP, then amplification capability is enhanced, but primer dimer formation increases leading to non-specific amplification
Solution Approach 1:
The patent segments the amplification function into three distinct primer types: external primers (LOF/LOR) for initial binding, internal primers (LIF/LIR) for extension, and loop primers for product formation. This segmentation reduces primer dimer formation by minimizing complex interactions while maintaining amplification capability through coordinated action of simplified primer components.
3Reliability
If strict target requirements are imposed for LAMP amplification, then amplification success rate improves, but applicability to diverse nucleic acid fragments deteriorates
Solution Approach 1:
The patent optimizes primer parameter ranges to accommodate diverse targets: Tm values of 50-70°C, GC content of 30-70%, and fragment lengths of 50-500 bp. These relaxed yet controlled parameters enable high amplification success rates across varying GC contents and fragment lengths, significantly improving versatility compared to conventional LAMP methods.
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
LDIA achieves efficient amplification of nucleic acid fragments with different lengths and GC contents, reducing primer design complexity and eliminating the need for temperature control, thus enhancing reaction efficiency and specificity compared to traditional PCR and LAMP methods.
Implementation Method 1
hybridizing an external primer LOF, an external primer LOR, an internal primer LIF and an internal primer LIR with a target sequence to form single-stranded DNA under catalysis of an external primer and polymerase, and forming short double-stranded DNA under an action of an internal primer
Implementation Method 2
allowing for dynamic dissociation of short double-stranded DNA and amplification to form new amplification products catalyzed by internal primers and polymerases
Implementation Method 3
amplification to form new amplification products catalyzed by internal primers and polymerases
Data Source
AI summary
A linear displacement isothermal amplification (LDIA) method and application thereof are by the present disclosure. The LDIA method of the present disclosure specifically starts the initial reaction of LDIA for four common primers of the template, including a pair of external primers (LOF and LOR) and internal primers (LIF and LIR), and an accelerating primer (LAR) may also be added in the reaction to form a short sequence product. The method provided by the disclosure greatly reduce the difficulty of primer design while maintaining the sensitivity and specificity similar to other isothermal amplification reactions such as loop-mediated isothermal amplification methods.