DNA Isolation Using Low Lithium and Chaotropic Agents
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Solution Overview
Problem
Existing methods for isolating DNA from biological materials using high lithium salt concentrations risk contamination and inhibit downstream applications like PCR, due to lithium chloride's inhibitory effects.
Innovation Solution
A method involving low lithium salt concentrations (0.05 to 1.0M) and the use of a chaotropic agent like guanidinium salts for lysing biological material, followed by immobilization on a solid support and multiple wash steps with alcohols to achieve high-purity DNA isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high lithium salt concentrations are used in the lysis composition, then DNA isolation is achieved, but lithium contamination occurs which inhibits downstream PCR reactions
Solution Approach 1:
The patent changes the concentration parameter of lithium salt from high (1-10M) to low (0.05-1.0M) while introducing a chaotropic agent (guanidinium salt at 0.1-2M) to compensate for the reduced lithium effectiveness, thereby maintaining DNA isolation capability while eliminating PCR inhibition
Solution Approach 2:
The patent introduces a chaotropic agent (guanidinium salt) as an intermediary substance that works synergistically with low concentrations of lithium salt to achieve effective cell lysis and DNA isolation without requiring high lithium concentrations that would contaminate the isolated DNA
2Reliability
If multiple wash steps with alcohol are performed, then lithium contamination is reduced, but processing time increases
Solution Approach 1:
The patent applies partial washing action with alcohol (20-90% v/v) in one or more steps rather than extensive washing, which is sufficient to remove lithium contamination when low lithium concentrations are used initially, thereby balancing purity achievement with time efficiency
Solution Approach 2:
The patent performs preliminary action by using low lithium concentrations and chaotropic agents from the beginning of the process, which reduces the need for extensive subsequent washing steps, thereby achieving both high purity and reduced processing time
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 results in the isolation of substantially pure and intact DNA with reduced lithium contamination, enabling effective downstream applications such as PCR and diagnostic analysis.
Implementation Method 1
treating the lysed composition with a solid support in the presence of a dissolved chaotropic agent
Implementation Method 2
contacting the resultant mixture with a solid support to immobilise DNA from the lysed material
Implementation Method 3
washing the support with a wash liquid containing an alcohol
Data Source
AI summary
Methods of isolating nucleic acids comprising DNA from biological material are disclosed. The methods comprise a lysis step using an aqueous composition which comprises lithium at a concentration of 0.05 to 1.0M, a chelating agent, and a surfactant to produce a lysed composition. The lysed composition is treated with a solid support that is capable of immobilising DNA in the presence of a dissolved chaotropic agent at a concentration of 0.05 to 2M and 25% to 60% by volume of a C1-3 alkanol. The support is then washed with a first wash solution containing lithium dissolved in a C1-3 alkanol. Subsequently, the support is washed with a liquid comprising at least 80% by volume of a C1-3 alkanol. The nucleic acid comprising DNA is then eluted from the support.