Silica Nucleic Acid Binding Chemistry With TMAC at Acidic pH
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Solution Overview
Problem
Existing nucleic acid purification methods, such as the Boom protocol, require large volumes of chaotropic salts and alcohols, which are expensive, PCR-inhibitory, and not suitable for miniaturized Lab-on-a-Chip devices, particularly for processing liquid biopsies with scarce nucleic acid targets.
Innovation Solution
A novel silica-based nucleic acid purification chemistry using a small quaternary organic compound, like tetramethylammonium chloride (TMAC), at acidic conditions, reduces binding buffer volume and enables efficient isolation of both DNA and RNA without chaotropes, suitable for integrated molecular diagnostic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chaotropic salts and alcohols are used in large amounts for nucleic acid purification, then nucleic acid extraction yield is improved, but buffer volume and cost increase
Solution Approach 1:
The patent changes the chemical parameters of the binding buffer by using quaternary ammonium salts instead of traditional chaotropic salts, and by adjusting pH to acidic conditions (pH 3-6). This parameter change enables effective nucleic acid binding to silica with significantly reduced buffer volumes, resolving the contradiction between extraction yield and buffer volume requirements
Solution Approach 2:
The patent employs a disposable silica solid support column that can be used once and then discarded, eliminating the need for large volumes of expensive chaotropic salts and alcohols. This disposable approach reduces both buffer volume requirements and overall cost while maintaining effective nucleic acid purification
2Productivity
If chaotropic salts are used for nucleic acid purification, then extraction efficiency is improved, but PCR inhibition and manufacturing complexity increase
Solution Approach 1:
The patent extracts and removes the harmful chaotropic salts from the purification system entirely, replacing them with quaternary ammonium salts that do not inhibit PCR. This extraction of the harmful component maintains extraction efficiency while eliminating PCR inhibition and manufacturing complexity issues
Solution Approach 2:
The patent converts the potentially harmful effect of high salt concentrations into a beneficial binding condition by using quaternary ammonium salts at acidic pH. These salts provide effective nucleic acid binding without the harmful PCR inhibition associated with traditional chaotropic salts, turning a harmful factor into a beneficial one
3Productivity
If large volumes of binding buffer are used, then nucleic acid binding is improved, but device miniaturization is hindered
Solution Approach 1:
The patent changes the chemical concentration parameters by using quaternary ammonium salts at optimized concentrations (0.1-2.0 M) combined with acidic pH conditions. This parameter optimization achieves effective nucleic acid binding with much smaller buffer volumes, enabling device miniaturization while maintaining binding efficiency
Solution Approach 2:
The patent applies local quality by concentrating the binding buffer in a small volume within the silica column while maintaining high local concentration of quaternary ammonium salts and acidic pH conditions. This localized high-concentration environment enables efficient nucleic acid binding in miniaturized devices without requiring large overall buffer volumes
4Productivity
If chaotropic salts are used, then nucleic acid purification is effective, but cost and manufacturing complexity increase
Solution Approach 1:
The patent replaces expensive chaotropic salts with cheaper quaternary ammonium salts and uses a disposable silica column system. This substitution significantly reduces reagent costs and simplifies manufacturing while maintaining effective nucleic acid purification, resolving the contradiction between purification effectiveness and manufacturing ease
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
The method achieves nucleic acid yields comparable to chaotrope-based protocols while minimizing buffer volume, facilitating increased sample input and compatibility with miniaturized systems, especially for liquid biopsies.
Implementation Method 1
contacting a biological sample with a silica solid support at pH value between 3 and 6 and in the presence of a salt consisting of a small quaternary organic compound... which mediates binding of nucleic acids to silica
Data Source
AI summary
The present invention generally relates to the field of nucleic acid isolation on silica solid support. In particular, a novel silica-solid support nucleic acid binding buffer chemistry is hereby disclosed, which is based on the use of a small quaternary organic compounds, e.g. tetramethylammonium chloride (TMAC), at acidic conditions. This novel nucleic acid purification chemistry purifies not only RNA but also DNA and has the potential for being implementable in a wide variety of commercial kits ranging from the spin columns to integrated Lab-On-A-Chip (LOC) devices such as disposable cartridges that make use of a solid-phase extraction technology. Furthermore, the present methods may be performed using relatively small volumes of binding buffer and consequently in such integrated or closed molecular diagnostic devices, they have the potential of allowing increased volumes of sample input, which for liquid biopsy samples such as plasma or urine, can enhance the chances of detecting rare nucleic acid targets.