Magnetic bead separation is a quick, efficient, clean process that scientists use to replace filtration, centrifugation and separation techniques. Magnetic beads and particles are
used as carriers of antigens, antibodies,
catalyzers, proteins and nucleic acids, enabling action on cells, bacteria, viruses and other biological entities.
Genomic sequencing and molecular analysis have become so standard to biological research that they are now all but required for work to be published in high profile journals. Outside the scientific realm, magnetic DNA purification is also fundamental to forensic analysis in the criminal justice system. Therefore, a method to rapidly extract and purify high-quality DNA and RNA from a variety of tissues is indispensable, and improvements to the technique are desired.
The first four mistakes we described in the last weeks are related to the production process of CLIA IVD-kits. However, even if you get a perfect reproducible, high performant process, it is a last mistake you should avoid. We have frequently see IVD-manufacturers to adopt solutions implying high safety risk for the operators and the equipment.
When developing a CLIA IVD-kit, the initial focus is on the biomarker and how to coat the magnetic beads. Biomagnetic separation conditions usually get swept to one side.
Not all mistakes made in CLIA-IVD kit manufacturing involve the magnetic rack itself. Besides the two mistakes we reviewed during the last weeks, the third mistake we have detected involves process validation. Biomagnetic separation processes are often validated solely by specifying a separation time.
Product development is a time-consuming, expensive process for CLIA-IVD kit manufacturers. There are several steps involved:
- Selecting the biomarker
- Choosing the right coupling
- Selecting the right magnetic bead
You are well versed with the first two points but what is “the right bead”? Assuming you have the right biomarker and a perfect coupling, the ideal magnetic bead should have the following properties:
- High recovery/fast separation, compatible with the timing of the analyzer step. It needs to be fast enough during large-scale production processes without high bead and coupled biomarker losses.
- No aggregation problems. Beads should be easy to re-suspend. It makes no sense to separate quickly if several additional sonication steps are required, which are difficult processes to control/implement in large volumes.
- Low kit-to-kit variability. Batch aliquots (typically less than a milliliter) of production batches (liters scale) must be consistent. If not, variability causes problems when interpreting the results in the analyzer.
When a new CLIA-IVD kit is transferred from R&D to production, all the manufacturing protocols should be adapted to the new throughput and volume. Biomarker specifications, buffers and coating protocols would benefit from the cumulated experience in non-magnetic kits. Coupling an antibody to magnetic beads is quite similar to doing it in colloidal gold or latex particles. But the washing protocols using Biomagnetic Separation are something new. The use of classical (and dirty) centrifugation method makes not so much sense when we can use the magnetic properties of the beads. Similar reasoning applies to the use lateral flow filtration or other complex and time-consuming non-magnetic separation techniques.
The most frequent concern when considering the use of modern Biomagnetic Separation Systems is their compatibility with specific magnetic beads. Although Sepmag® devices are already working successfully in IVD labs and production lines, this is a very legitimate question.
