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In the fight against COVID-19, testing of patient samples has been mostly conducted using standard techniques, which has kept clinics struggling to keep up with the demand for testing. The first step in coronavirus testing that needs to be more efficient is the RNA extraction.

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Why magnetic beads are an ideal candidate for serology tests, vaccines, and purification of RNA

Magnetic beads can be used as mobile solid support for capturing different substances present in a suspension and, just by applying a magnetic force, be immobilized (with the captured target), the supernatant removed and then re-suspended again in a clean buffer. This versatility allows to develop different protocols with the commercially available beads conjugate with different types of molecules. The resultant products and protocols can be used for detecting an analyte of interest in a solution or for purifying a biological substance present in a complex matrix.  Magnetic beads are used for testing at the laboratory research scale and clinical level, as well as for developing vaccines at a manufacturing scale, which becomes crucial during times such as a pandemic situation. Additionally, in the fight against COVID-19, magnetic bead chemiluminescent immunoassays can be used for serological tests. For scaling all these methods just require the right magnets for efficient and reliable separation, which now exists. 

General protocol for RNA purification using magnetic beads

The first step in coronavirus detection is RNA extraction. Only then can reverse-transcriptase polymerase chain reaction (RT-PCR) take place to amplify the RNA to detect the virus. RNA extraction can be done using magnetic beads specially functionalized to bind RNA, which are sold in kits from many companies. When the beads are mixed with the sample, they bind RNA. When this solution is placed in a magnetic field, the beads will be held in place while the rest of the solution can be removed. Once removed from the magnetic field, the beads can go back into solution, now as a pure nucleic acid sample. This process can easily be done in laboratories or at a manufacturing scale, now that there are proper small and large scale magnets available for biological separation techniques. 

Overcoming limitations to scale up RNA purification for diagnosis, vaccines, and serology

RNA purification on a large scale, such as for manufacturing purposes, is important as scientists search for ways to increase coronavirus testing as well as alternative vaccines that can provide increased protection with minimal negative effects as compared to current vaccines that often focus on less virulent virus particles or protein subunits. Research institutions as well as biotech and pharmaceutical companies are currently interested in scaling up purification of magnetic beads for chemiluminescent assays. These assays will be able to test human liquid biopsies for antibodies towards COVID-19. They are also interested in RNA vaccines to provide protection from the novel coronavirus by using the RNA to instigate an immune response towards the virus. An RNA vaccine requires large scale RNA purification techniques. With recent advances, it is possible to do a large purification like this by biomagnetic separation. The technology was once limited by the small volume the classical magnetic separator can efficiently and safely separate, but now the advanced biomagnetic separation systems can consistently purify batches up to 50 L. 

Conclusion, the future of magnetic beads for COVID-19 testing, research, and vaccine development

With the technology available and growing for small scale and large batches of magnetic bead separation, there is an opportunity to optimize protocols surrounding COVID-19. There are now many commercial kits available for magnetic bead serology and purification of RNA, and a range of magnets for separation. Magnetic beads will become part of the repertoire for those interested in pure samples that can be prepared with ease.

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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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