Nucleic Acid Isolation Using pH-Dependent Silica Binding
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Solution Overview
Problem
Conventional nucleic acid isolation methods using chaotropic agents and organic solvents are inhibitory to enzymatic reactions, toxic, and require special handling and storage, leading to interference in subsequent processing and increased costs due to the need for enzymes like proteinase K.
Innovation Solution
A method involving binding nucleic acid to a solid phase at a first pH, washing with a buffer at a pH within the binding buffer's range but lower than the wash buffer's range, and eluting at a second pH higher than the first, without the use of chaotropic agents or organic solvents, utilizing a kosmotropic agent and a silica-based solid phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chaotropic agents and organic solvents are used for nucleic acid isolation, then cell lysis and protein denaturation are effective, but enzymatic reactions are inhibited and toxicity increases
Solution Approach 1:
The invention changes the chemical parameters of the isolation buffer by replacing chaotropic agents with a specific buffer system (Tris-HCl at pH 7.5-8.5) that maintains different ionic strength and pH conditions. This parameter change allows effective nucleic acid binding to silica particles without the harmful effects of chaotropic agents, resolving the contradiction between isolation effectiveness and enzymatic compatibility
Solution Approach 2:
The invention introduces an intermediary buffer system that mediates between the lysis step and the enzymatic processing step. The buffer contains Tris-HCl at a pH that promotes nucleic acid binding to silica while being compatible with subsequent enzymatic reactions, thus acting as a bridge that eliminates the need for harsh chaotropic agents
2Reliability
If chaotropic agents are used in high molarities, then nucleic acid binding is enhanced, but precipitation occurs during storage requiring heating
Solution Approach 1:
The invention changes the ionic composition and pH parameters of the binding buffer, using Tris-HCl at pH 7.5-8.5 with specific salt concentrations. This parameter change maintains effective nucleic acid binding to silica particles without causing precipitation during refrigerated storage, eliminating the need for heating before use
3Reliability
If enzymes like proteinase K are used for protein digestion, then protein removal is effective, but cost increases and special storage conditions are required
Solution Approach 1:
The invention extracts or removes the need for enzymatic protein digestion by using a buffer system that allows direct protein removal through silica particle binding. The Tris-HCl buffer at pH 7.5-8.5 enables proteins to be removed alongside nucleic acid binding, eliminating the requirement for separate enzymatic digestion steps and their associated storage complexities
Solution Approach 2:
The buffer system performs multiple functions simultaneously: it maintains pH for nucleic acid binding, facilitates protein removal, and is compatible with subsequent enzymatic reactions. This self-service approach eliminates the need for separate proteinase K treatment, simplifying the protocol and reducing storage requirements
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 nucleic acid yield, avoids interference with enzymatic processing, and eliminates the need for enzyme storage and handling, providing a safer and more cost-effective solution for nucleic acid isolation.
Implementation Method 1
Released nucleic acid binds to the silica particles
Implementation Method 2
washing the bound nucleic acid with a wash solution
Implementation Method 3
eluting the nucleic acid from the solid phase at a second pH which is higher than the first pH
Data Source
AI summary
A method for isolating a nucleic acid comprises: binding the nucleic acid to a solid phase at a first pH in the presence of a binding buffer, washing the bound nucleic acid with a wash solution, and eluting the nucleic acid from the solid phase at a second pH which is higher than the first pH. The wash solution comprises a buffer with a buffering range that encompasses a pH that is higher than the first pH, and the wash solution is at a pH that is within a buffering range of the binding buffer but lower than the buffering range of the buffer of the wash solution. Solutions, compositions, and kits for use in the methods are described.