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Magnetic Beads

Home > DNA Extraction & Quantitation > Other Extraction Techniques > Other Techniques > Magnetic Beads

The use of magnetic beads is another solid phase extraction method.

These methods:

• Can be automated
• Increase throughput
• Demonstrate the ability to remove amplification inhibitors
• Use no hazardous chemicals.

These kits can also be used as adjuncts to traditional methods, when additional clean-up is warranted.

The principle underlying magnetic bead procedures involves attracting DNA to magnetic beads, holding the beads in place using a magnetized source, such as a rack or tube holder, and washing away other components of the sample.

Invitrogen's ChargeSwitch^® Technology (CST^®) involves the use of magnetic beads whose surface bears a charge that can be switched based on the pH of the surrounding buffer environment. At low pH, the beads are positively charged, attracting the negatively charged DNA molecules and allowing proteins and contaminants to be removed by washing.

The ChargeSwitch^® Forensic DNA Purification Kit includes:

• Lysis buffer
• Magnetic beads
• Proteinase K
• Purification buffer
• Wash buffer
• Elution buffer

Click here to view an animation on magnetic beads.

The DNA IQ™ System by Promega uses silica-coated magnetic beads. DN™ was designed for automation on robotic systems. The quantity of beads used in the procedure defines the binding capacity, which is approximately 100ng of DNA. This relative quantitative capability makes it ideal for databasing and paternity applications because consistent quantities of DNA are isolated.

The DNA IQ™ kit contains the proprietary resin and several specialized buffers, including lysis, wash, and elution. The method demonstrates efficient DNA extraction from small samples and the removal of inhibiting compounds. For example, internal validation studies of DN™ were successful in the extraction of DNA from small stains deposited on difficult substrates, such as denim, leather, and soil.

Promega also offers a special buffer for the extraction of DNA from bone and a procedure for differential extraction.

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