cDNA Synthesis Method Eliminating Organic Solvents
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Solution Overview
Problem
The existing methods for nucleic acid extraction using silica particles and chaotropic agents face challenges with the use of organic solvents like ethanol, which inhibit enzymatic reactions, are time-consuming to dry, and pose fire risks, leading to reduced nucleic acid yield and reproducibility.
Innovation Solution
A cDNA synthesis method involving adsorption of RNA on a nucleic acid-binding solid-phase carrier, followed by reverse transcription without releasing the RNA, and elution with a DNA polymerase-containing eluent at elevated temperatures, eliminating the need for organic solvents and enhancing cDNA efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-soluble organic solvent (ethanol) is used in the washing step to dissolve chaotropic agent and prevent nucleic acid elution, then washing effectiveness is improved, but enzymatic reaction is inhibited and fire risk increases
Solution Approach 1:
The patent removes the harmful organic solvent (ethanol) from the washing step while maintaining washing effectiveness through optimized washing solutions containing chaotropic agents and surfactants that achieve proper cleaning without introducing flammable or enzyme-inhibiting substances
Solution Approach 2:
The patent introduces an intermediate drying step using centrifugation or filtration to remove excess washing solution before elution, allowing thorough washing without residual solvent that would inhibit subsequent enzymatic reactions
2Loss of substance
If organic solvent (ethanol or acetone) is used for drying the carrier, then organic solvent removal is achieved, but drying time increases and nucleic acid yield decreases
Solution Approach 1:
The patent replaces the thermal drying process with mechanical separation methods (centrifugation, filtration, or magnetic separation) to remove excess washing solution, dramatically reducing drying time from minutes to seconds while preventing nucleic acid dehydration
Solution Approach 2:
The patent optimizes the washing solution composition and volume, and controls the washing speed and temperature to achieve optimal carrier wetness that allows complete solvent removal through brief centrifugation without causing nucleic acid loss or requiring prolonged drying
3Ease of operation
If RNA is released from the carrier before reverse transcription, then RNA accessibility is improved, but process complexity and time increase
Solution Approach 1:
The patent combines the washing step and reverse transcription setup into a single integrated process where the carrier with adsorbed RNA is directly transferred to the reverse transcription reaction mixture without elution, reducing the number of steps from 4 to 2 while maintaining reaction efficiency
Solution Approach 2:
The nucleic acid-binding carrier serves multiple functions: it acts as both the adsorption medium for RNA concentration and the reaction support for reverse transcription, eliminating the need for separate elution and transfer steps
4Productivity
If chaotropic agent is used in high concentration for RNA adsorption, then adsorption efficiency is improved, but RNA yield decreases due to nucleic acid solidification
Solution Approach 1:
The patent uses different chaotropic agent concentrations in different steps: high concentration (4-7 M) during adsorption to maximize RNA binding to the carrier, then lower concentration or complete removal during washing to prevent RNA solidification and enable efficient elution, with the carrier acting as a localized high-affinity binding site
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 allows for efficient cDNA synthesis and PCR performance by directly incorporating the synthesized cDNA into the PCR reaction mixture, improving yield and reproducibility while avoiding the risks associated with organic solvents.
Implementation Method 1
a step of adsorbing nucleic acids on a nucleic acid-binding solid-phase carrier in the presence of a chaotropic agent (adsorption step)
Implementation Method 2
reverse-transcribing the RNA adsorbed on the carrier while keeping the RNA adsorbed on the carrier in a reverse transcription reaction mixture, thereby synthesizing cDNA
Implementation Method 3
eluting the synthesized cDNA with an eluent
Data Source
AI summary
A cDNA synthesis method includes: mixing a lysis solution containing a chaotropic substance and a nucleic acid-binding solid-phase carrier in a sample containing a ribonucleic acid (RNA), thereby adsorbing the RNA on the carrier; reverse-transcribing the RNA adsorbed on the carrier while keeping the RNA adsorbed on the carrier in a reverse transcription reaction mixture, thereby synthesizing cDNA; and eluting the synthesized cDNA with an eluent.