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There has been a lot of discussion surrounding RNA purification for the purposes for testing people for the presence of  viruses from liquid biopsies. Using magnetic beads for the purification, many kits for individual sample preparations are required. At this time there is also potential for use of magnetic beads for large-scale purification of RNA in research towards the development of vaccines and tests. 

Free guide: The basic guide to scale-up biomagnetic separation processes

Current use of RNA magnetic purification at lab scale.

Magnetic beads are currently used in laboratories for RNA purification. The beads offer a large surface area for nucleic acid binding which can make the purification process simple and fast by binding many RNA’s tightly. The speed and simplicity are what make magnetic beads an attractive and probable choice for high throughput purification. The general protocol is only a few steps:

  1. Cells are lysed and incubated with magnetic beads that bind RNA
  2. The solution is placed in a magnet to magnetize the beads
  3. RNA bound by beads can be washed several times, and can be released when removed from the magnet
  4. RNA is resuspended in buffer and removed from the beads

 

Limitations for scaling-up

There are several methods currently used to purify RNA, but they do not scale well for large volume RNA purification. Large volume purification requires simplicity and an iterative protocol that can be applied equally to the whole sample. Methods such as polyacrylamide gel electrophoresis or precipitation don’t have the capacity to be scaled for large volumes due to the size of the apparatus or the manual precision required. Magnetic separation can be scalable, but must be done so with several considerations. Currently magnetic separators have the advantage of making the purification process simple and iterative, but require optimization to apply it’s method equally to large whole samples. For large volume RNA purification, there needs to be biomagnetic separation systems that are capable of applying equal force to a whole large sample, and conditions for the beads and size of container need to be optimized for best separation. 

Large scale magnetic separation is already in used at Immunoassays Production

To address the need for large volume RNA purification and the potential for magnetic beads to accomplish this goal, some companies have begun making such a product. Magnetic beads for RNA purification serve to provide optimized beads, but beyond the beads it is important to consider the magnetic device used for separation. As the purification volume gets larger the magnetic force that needs to be applied requires careful scaling. As for any magnetic purification, a constant force is important for controlling the speed and strength of the reaction to safely and precisely separate your magnetic beads. The availability of a proper biomagnetic separation system for a constant magnetic field for large volume purification allows for the creation of a large scale RNA purification setup such as is seen in Sarafik et al. 

Large-scale RNA magnetic purification has become available through the innovation in magnets that allow for constant magnetic force across a biological sample. These kinds of products will allow large scale purification of RNA using magnets in laboratories and manufacturing. 

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Lluis M. Martínez | SEPMAG Chief Scientific Officer

Founder of SEPMAG, Lluis holds a PhD in Magnetic Materials by the UAB. He has conducted research at German and Spanish academic institutions. Having worked in companies in Ireland, USA and Spain, he has more than 20 years of experience applying magnetic materials and sensors to industrial products and processes. He has filed several international patents on the field and co-authored more than 20 scientific papers, most of them on the subject of magnetic particle movement.

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