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In a pandemic it becomes crucial to quickly design and manufacture a diagnostic device for large scale testing of human blood for viruses. Ideally, each step of the diagnosis protocol needs to scalable so that it can be done quickly. The first step, purification, needs to produce pure and clean samples for lower rates of false results. The use of RNA purification kits in coronavirus testing offers a solution to this problem. 

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Current state of RNA purification for coronavirus testing

The process of testing patient samples for coronavirus involves an RNA purification step. Most patient samples collected for coronavirus testing are nasopharyngeal or blood. After the RNA purification step, samples are sent to undergo Reverse-transcriptase polymerase chain reaction (RT-PCR) for detection of viral RNA amongst the RNA purified from the sample. In RT-PCR, nucleic acid primers are used to amplify an RNA of interest to detect it. Time and resources required for performing RNA purification have become limited during the pandemic and now hinder the gathering of efficient results in coronavirus research and diagnosis. Most clinical and research laboratories use kits for extraction, and those kits have been in limited supply since the outbreak of coronavirus. Kits may include columns and reagents that are used in a specific order to pull RNA from a sample. These kits are time consuming and have lower yield due to the many steps involved. There are other chemical, column-based, or gel-based approaches to RNA purification but they are even more time and reagent consuming than kits can be, which is not ideal in an outbreak situation where large-scale testing is pertinent. 

RNA purification magnetic kits for higher throughput testing for coronavirus

The use of magnetic beads or a magnetic kit can offer many advantages for RNA purification for coronavirus testing. Magnetic bead kits exist for the purpose of isolating mRNA by its poly-A tail by pre-conjugating beads with an oligo(dT) nucleic acid chain. A magnetic kit for extraction of total RNA relies on creating buffer conditions favorable for RNA binding to a silica coated bead. Optimized buffers can be purchased commercially with magnetic kits or made in laboratory to produce desired results. Using magnetic beads for separation of RNA from crude material can streamline the process of testing by expediting the purification process so that samples can quickly move onto the next step, RT-PCR. Beads offer this efficiency because the steps of the procedure are simple and straightforward, which also results in a purer sample than purification with non-magnetic bead kits, spin columns or phenol-chloroform extraction.  Once an ideal bead type or pre-conjugation is determined, beads are simply incubated with a patient sample to bind the beads. Subsequently, the separation of your target molecules from the solution can quickly begin and progress as soon as you place your solution into a magnetic field. Wash steps only require removing solution while in the magnetic field. Releasing the beads is as simple as removing the solution from the magnet. Biomagnetic separation systems for this purpose are made in the milliliters to liters range.

Magnetic beads offer a solution to current RNA purification challenges

Laboratories have already begun to realize the potential solution in the use of magnetic kits for RNA purification. Beads must only be purchased once as well as the proper magnet for the separation of the beads. Optimized reagents for RNA binding to the magnetic beads can be made in the laboratory using materials already typically available. Once a protocol is in place, the process can be scaled up for purifying RNA from hundreds to tens of thousands of samples because magnetic beads have a simple iterative process for washing, separating and resuspending. A magnetic kit for RNA purification goes a long way for large-scale testing. Beyond RNA purification, magnetic beads also offer a direct method of coronavirus testing with chemiluminescent immunoassays for coronavirus antibodies. Kits for magnetic beads pre-conjugated to antigens of SARS-CoV-2 are becoming more available. Magnetic beads for both RNA purification and for serology offer great advantages to bolster both testing and research with purity of sample and ease of use.

Conclusion

Research institutions and companies across the world are trying to develop the optimal protocol for coronavirus testing. This requires a scalable, quick, and cost-effective method for purifying patient samples and testing them. Magnetic bead technology has been bolstered by growing sizes of magnets available for separation techniques. Magnetic beads are being used for purification and for diagnostics, and such kits are becoming more available at a rapid rate as coronavirus testing continues to be a top priority. 

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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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