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.