Nucleic Acid Isolation Using Chaotropic and Chelating Agents
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Solution Overview
Problem
Current nucleic acid isolation methods, particularly for RNA from blood samples, face challenges in maintaining high yield and integrity due to variations in holding times between sample preparation and actual isolation, leading to precipitate formation and adherence to container walls, which reduces nucleic acid yield and quality.
Innovation Solution
Incorporating at least one chaotropic agent and one chelating agent into the sample preparation step to stabilize nucleic acids, reducing precipitate formation and adherence to container walls, thereby maintaining RNA integrity and yield even with prolonged holding times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If samples are prepared manually and processed in batches using automated robotic systems, then productivity is improved by reducing hands-on time, but variations in holding times between sample preparation and actual isolation occur, leading to reduced nucleic acid yield and quality
Solution Approach 1:
The invention applies preliminary action by adding chaotropic agent and chelating agent to the resuspension buffer before samples are processed. This pre-preparation ensures that samples are immediately stabilized upon resuspension, preventing precipitate formation during any subsequent holding time. The chaotropic agent denatures proteins and stabilizes nucleic acids, while the chelating agent binds metal ions that could catalyze degradation, thereby maintaining consistent nucleic acid quality regardless of variations in processing timing.
Solution Approach 2:
The invention changes the chemical parameters of the resuspension buffer by incorporating chaotropic agents (such as guanidinium thiocyanate) and chelating agents (such as EDTA). These parameter changes fundamentally alter the buffer's properties to prevent protein-nucleic acid interactions and metal ion-catalyzed degradation. The modified buffer composition maintains nucleic acid stability over extended periods, allowing automated systems to process samples without compromising yield or quality consistency.
2Reliability
If chaotropic agents are used to stabilize nucleic acids during holding, then nucleic acid integrity is improved, but precipitate formation occurs that adheres to container walls, reducing nucleic acid yield
Solution Approach 1:
The invention uses a composite chemical system combining chaotropic agents, chelating agents, and alcohol in the resuspension buffer. This composite approach leverages the synergistic effects of multiple components: the chaotropic agent stabilizes nucleic acids by denaturing proteins, the chelating agent prevents metal ion-catalyzed degradation, and the alcohol precipitates proteins without causing nucleic acid loss. Together, these components maintain nucleic acid integrity while preventing the formation of adherent precipitates that would reduce yield.
Solution Approach 2:
The chelating agent acts as an intermediary by binding metal ions that would otherwise catalyze the formation of precipitates between nucleic acids and container surfaces. By sequestering these metal ions, the chelating agent prevents the harmful interaction without interfering with the stabilizing action of the chaotropic agent on nucleic acids. This intermediary function resolves the contradiction by eliminating the precipitate formation pathway while preserving nucleic acid stability.
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 ensures consistent high yield and quality of isolated RNA across varying holding times, particularly beneficial for automated processing of multiple samples, reducing losses and maintaining RNA integrity.
Implementation Method 1
Incorporating at least one chaotropic agent and one chelating agent into the sample preparation step to stabilize nucleic acids
Implementation Method 2
Incorporating at least one chaotropic agent and one chelating agent into the sample preparation step to stabilize nucleic acids
Implementation Method 3
obtaining a sample which has been stabilised by the use of at least one cationic detergent, wherein the cationic detergent has formed complexes with the nucleic acids
Data Source
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AI summary
The present invention pertains to a method for isolating nucleic acids from a sample, preferably a blood sample, comprising the following steps: a) obtaining a sample which has been stabilised by the use of at least one cationic detergent, wherein the cationic detergent has formed complexes with the nucleic acids; b) obtaining the complexes optionally together with other sample components from the stabilised sample, wherein said complexes comprise the nucleic acids to be isolated; c) resuspending the complexes and optionally adding one or more additives before, during and/or after resuspension, thereby obtaining a resuspended sample comprising at least i) the nucleic acid to be isolated; ii) at least one chaotropic agent; and iii) at least one chelating agent; and d) isolating nucleic acids from the resuspended sample. It was found that adding a chelating agent during resuspension considerably increases the nucleic acid yield as the formation of precipitates which irreversibly adhere to the container wall is considerably reduced.