DNA and RNA extraction with magnetic beads – How it works

In this video, we're going to explain to you how DNA and RNA extraction with magnetic beads works. Magnetic bead extraction, also known as magnetic bead separation or isolation, involves a series of steps consisting of cell lysis, binding, washing and elution.

Cell lysis
Cell lysis is the process of breaking down the membrane of your sample cells to release the cell contents, including DNA or RNA molecules. The lysis step can be performed using chemical methods, physical disruption, or a combination of both. The result of the lysis step is a cell lysate.

Binding
To perform the binding step, magnetic beads and a binding buffer are added to the cell lysate. Magnetic beads are tiny particles that are superparamagnetic which means that they only display magnetic behavior in the presence of an external magnetic field. On the surface of the beads, there are ligands that can reversibly bind nucleic acids under optimized buffer conditions. Some nucleic acid extraction beads bind DNA, some RNA and others total nucleic acids. When the sample, magnetic beads and binding buffer are incubated, the nucleic acids specifically bind to the magnetic beads. Following this, the sample is then placed on a magnetic separator or stand to attract the magnetic beads carrying the nucleic acids. By aspirating and discarding the supernatant, most of the unwanted particles, like cell debris, can be removed.

Washing
Next up is the washing step, where a washing buffer containing ethanol is added to the sample and mixed. Remaining unwanted particles are separated from the bead pellet and can be eliminated by aspirating and discarding the supernatant. More than one washing step may be needed to remove all the unwanted molecules. After the last washing step, the samples are left on the magnet for a couple of minutes to allow the remaining washing buffer to evaporate.

Elution
Finally, the samples are removed from the magnet and an elution buffer or nuclease-free water is added. The samples are then incubated, and the nucleic acids are released from the magnetic beads. The samples are placed on the magnet again, a bead pellet forms, and the purified nucleic acids can be transferred into a second recipient vessel.

PCR purification
Please note that the nucleic acid extraction workflow described in this video applies to samples like blood, microbes or tissue that contain intact cells. Magnetic beads can also be used to purify samples that have previously undergone PCR amplification, to prepare them for downstream applications. The main difference in this protocol is that a cell lysis step is not required.

Learn more about PCR purification with magnetic beads:
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Check out how INTEGRA's modules and magnetic beads can help you with magnetic bead workflows:
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Video content
[00:00] – What are magnetic beads?
[00:42] – DNA & RNA extraction steps
[00:56] – Cell lysis step
[01:15] – Binding step
[01:49] – Washing step
[02:33] – Elution step
[02:52] – DNA & RNA extraction applications
[03:06] – PCR purification with magnetic beads
[03:27] – Outro

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