Silica DNA Size Selection via pH Control
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Solution Overview
Problem
Current methods for size selective isolation of DNA molecules, particularly in next-generation sequencing, are time-consuming and inefficient, especially when removing adapter monomers and dimers from sequencing libraries, as they often rely on gel-based techniques or polyethylene glycol precipitation, which are cumbersome and prone to errors.
Innovation Solution
A method utilizing a silicon-containing surface with a chaotropic salt and a buffering agent to control the pH value for precise size selection of DNA molecules, allowing DNA molecules above a certain cut-off size to bind while smaller molecules are removed, thereby enriching target DNA molecules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gel-based techniques or polyethylene glycol precipitation are used for size selective isolation of DNA molecules, then separation of adapter monomers and dimers from sequencing libraries can be achieved, but the process becomes time-consuming and cumbersome
Solution Approach 1:
The patent changes the pH parameter of the binding buffer to control DNA binding to silica surfaces. By adjusting pH to alkaline conditions (pH 8.0-9.5), the method achieves size-selective binding where larger DNA fragments bind while smaller adapter monomers and dimers remain in solution, enabling rapid separation without time-consuming gel electrophoresis or PEG precipitation steps
Solution Approach 2:
The patent replaces mechanical separation methods (gel electrophoresis, centrifugation with PEG) with a chemical binding approach based on pH-controlled silica surface interaction. This substitution eliminates the need for complex mechanical operations while achieving comparable or superior separation efficiency
2Measurement precision
If gel-based techniques are used for size selective isolation, then precise size separation can be achieved, but the device complexity and operational difficulty increase
Solution Approach 1:
The patent uses pH as a control parameter to achieve precise size selection. By maintaining alkaline pH conditions during binding, the method creates a sharp cutoff where DNA fragments above a certain size bind to silica while smaller fragments remain unbound, providing precise size selection with a simple buffer-based approach rather than complex gel-based systems
Solution Approach 2:
The patent extracts only the essential binding function from complex separation systems. By using pH-controlled silica binding, it isolates the size-selection capability from the complexity of gel matrices, electrophoresis apparatus, and PEG precipitation protocols, achieving precise size selection through a single binding step
3Reliability
If conventional size selection methods are used to remove adapter monomers and dimers, then sequencing library quality can be improved, but the overall library preparation productivity decreases
Solution Approach 1:
The patent enables continuous processing by integrating pH-controlled binding directly into the library preparation workflow. The alkaline binding buffer can be added directly to reaction mixtures without intermediate steps, allowing continuous flow processing and eliminating bottlenecks that reduce productivity in conventional batch-based size selection methods
Solution Approach 2:
The patent segments the size selection process into a simple binding step followed by straightforward separation of bound vs. unbound fractions. This segmentation eliminates the need for time-consuming intermediate steps in gel-based or PEG-based methods, thereby increasing overall library preparation throughput while maintaining quality
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 enables fast, reliable, and precise size selection of DNA molecules, improving the quality of sequencing libraries by efficiently removing adapter monomers and dimers, and can be integrated into existing sequencing protocols, reducing the time and complexity of library preparation.
Implementation Method 1
A method utilizing a silicon-containing surface with a chaotropic salt and a buffering agent to control the pH value for precise size selection of DNA molecules
Implementation Method 2
control the pH value for precise size selection of DNA molecules, allowing DNA molecules above a certain cut-off size to bind
Implementation Method 3
binding DNA molecules having a size above the cut-off value to a binding matrix which has a silicon containing surface
Data Source
AI summary
The present invention provides method for isolating DNA molecules having a size above a certain cut-off value from a DNA containing sample, comprising a) contacting the sample with a binding buffer which comprises a chaotropic agent and a buffering agent to provide a binding mixture and binding DNA molecules having a size above the cut-off value to a binding matrix which has a silicon containing surface, wherein the cut-off value is determined by the pH value of the binding mixture; b) separating the bound DNA from the remaining sample; c) optionally washing the bound DNA; and d) optionally eluting the bound DNA from the binding matrix. Said method allows the size selective purification of DNA molecules.