Introduction
DNA extraction technologies
DNA can be purified using many different methods and the downstream application determines how pure the DNA should be. In addition to isolation using home-made methods (e.g., CsCl gradients), DNA extraction kits are available from many suppliers. The characteristics of the 3 most common types of DNA extraction kit are shown in the table.
Characteristics of common DNA extraction technologies
| Anion-exchange | Silica-membrane technology | Magnetic-particle technology |
|
|---|---|---|---|
| What it is | Solid-phase, anion-exchange chromatography | Selective adsorption to silica membranes | Binding to magnetic silica particles under controlled ionic conditions |
| Procedure | Binding: variable salt and pH Elution: variable salt and pH Alcohol precipitation |
Binding: high salt Elution: low salt Ready-to-use eluate |
Binding: high salt Elution: low salt Ready-to-use eluate |
| Advantages | Delivers ultrapure, transfection-grade DNA for optimal results in sensitive applications |
Delivers high-purity nucleic acids for use in most downstream applications |
Delivers high-purity nucleic acids for use in most downstream applications |
| Fast, inexpensive | Fast, inexpensive | ||
| No silica-slurry carry over, no alcohol precipitation | Easy to automate; no alcohol precipitation |
Anion-exchange methods yield DNA of a purity and biological activity equivalent to at least two rounds of purification in CsCl gradients, in a fraction of the time. Purified nucleic acids are of the highest possible quality and are ideal for sensitive downstream biological applications, such as transfection, microinjection, sequencing, and gene therapy research.
Silica-membrane technology yields high-purity nucleic acids suitable for most molecular biology and clinical research applications, such as restriction digestion, ligation, labeling, amplification, and radioactive and fluorescent sequencing.
Magnetic-particle technology yields high-purity nucleic acids suitable for most molecular biology applications used in clinical and veterinary research, such as restriction digestion, ligation, labeling, amplification, and radioactive and fluorescent sequencing. Magnetic-particle technology can often be automated to enable fast and economical nucleic acid purification procedures.