Single-Stranded DNA Synthesis via USER Self-Looping and Rolling Circle Replication
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Solution Overview
Problem
Current methods for producing single-stranded DNA templates are expensive, have low yield, and are limited by the length of the DNA sequences they can produce, with existing techniques like exonuclease digestion, asymmetric PCR, and magnetic bead adsorption being inefficient and costly, especially due to reliance on high-cost imported materials.
Innovation Solution
A process involving uracil-specific excision reagent (USER)-mediated self-looping of double-stranded DNA combined with auto-folding during annealing, using special sequence design and type II restriction endonucleases for accurate cleavage, followed by rolling circle replication, to produce high-purity, long single-stranded DNA templates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods (exonuclease digestion, asymmetric PCR, magnetic bead adsorption) are used to produce single-stranded DNA, then production cost is reduced or process is simplified, but yield remains low and purity is insufficient
Solution Approach 1:
The production process is divided into distinct functional modules: USER-mediated self-looping to create circular templates, rolling circle replication to amplify single-stranded DNA, and type II restriction endonuclease cleavage to release final products. Each module optimizes for its specific function, achieving both high yield and high purity simultaneously
Solution Approach 2:
Double-stranded DNA circular templates serve as intermediaries that enable high-yield rolling circle replication. The circular structure allows continuous replication without termination, dramatically increasing yield while maintaining purity through the self-contained replication mechanism
2Length of moving object
If chemically synthesized single-stranded DNA is used, then sequence precision is achieved, but length is limited to 200 bases and wrong sequences cannot be removed
Solution Approach 1:
Rolling circle replication provides continuous DNA synthesis around the circular template, enabling production of very long single-stranded DNA molecules (thousands of bases) in a single continuous process, overcoming the 200-base limitation of chemical synthesis
Solution Approach 2:
The circular dsDNA template and replication system are self-sustaining, automatically producing identical high-fidelity copies through the replication machinery's inherent accuracy, maintaining sequence fidelity without requiring post-synthesis purification to remove errors
3Ease of manufacture
If biotin-streptavidin magnetic bead adsorption is used, then operation simplicity and production stability are achieved, but cost increases due to expensive imported magnetic beads and waiting time
Solution Approach 1:
The method uses conventional, inexpensive reagents (USER enzyme, T4 DNA ligase, type II restriction endonucleases, standard PCR components) that can be readily purchased or prepared, replacing expensive imported magnetic beads while maintaining operational simplicity and eliminating waiting times
Solution Approach 2:
The process changes the fundamental parameters of the production system by using enzymatic reactions with standard incubation times and temperatures, replacing the magnetic bead adsorption process and its associated cost structure, achieving the same operational simplicity at lower cost
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 significantly increases the yield of single-stranded DNA from micrograms to nanomoles, achieving high purity and sequence fidelity, reducing production costs and eliminating the need for expensive imported materials, making it suitable for large-scale and stable production.
Implementation Method 1
uracil-specific excision reagent (USER)-mediated self-looping of double-stranded DNA
Implementation Method 2
ligating the two cohesive terminuses of the product double-stranded DNA molecule in the presence of a ligase, to form a circular double-stranded DNA
Implementation Method 3
rolling circle replication of thermostatically amplified single-stranded DNA
Implementation Method 4
a type II restriction endonuclease that can accurately cleave a target single-stranded fragment
Implementation Method 5
auto-folding during the annealing process of single-stranded DNA
Data Source
AI summary
A method for synthesizing single-stranded DNA, specifically a process for producing single-stranded DNA without base mutations, is provided, by which single-stranded DNA is produced by uracil-specific excision reagent (USER)-mediated self-looping of double-stranded DNA combined with rolling circle replication.