Biomagnetic separation is a versatile and widely used tool in both industrial and small laboratory settings. It is used for the isolation of target drug molecules in the pharmaceutical realm, for the enrichment of enzymes in industry, and for in-vitro diagnostics in medicine. It is especially useful in the small-scale research environment for inexpensive target cell enrichment, protein isolation, or nucleic acid capture. In the early days of biomagnetic separation it was thought that the process was only reliable for small volumes. However, the development of modern biomagnetic separation racks has made it possible to scale up the process to large volumes and to enable process validation and consistency between batches.
Process validation
Whether the process takes place in industry or small laboratory research, it is essential to collect data throughout the process in order to evaluate consistency and reliability of a product or experimental result. Additionally, commercial products are susceptible to examination by regulatory authorities. When using biomagnetic separation the separation conditions must be well defined and consistent. This means controlling for buffer composition, incubation time, magnetic bead type, size, shape, and concentration, working volume, and separation conditions. Traditional separation racks rely on separation time as the only method to define separation conditions, but this is unreliable if any other parameter in the process is changed. Additionally, traditional separation racks are only good for small volumes and have poor in-batch separation consistency
The problem with traditional separation racks
Traditional separation racks (where magnetic force is variable with distance from the magnet) are difficult to scale up from small to large working volumes. They might work fine at a small volume where the effects of distance from the magnet are negligible, but when they are scaled up the beads farthest from the magnet may experience low magnetic force and move very slowly or not at all. One way to overcome this problem is to use a bigger magnet to increase magnetic force at distances farthest from the retention area, but this can cause problems such as irreversible bead clumping or cell membrane breakage due to extremely high magnetic force closest to the magnet. Additionally, since the particles feel variable magnetic force it is nearly impossible to define separation conditions within a single batch.
Modern separation racks: homogeneous magnetic force for consistency
Modern separation racks are engineered to ensure that every magnetic particle throughout the working volume experiences the same magnetic force. Therefore, magnetic force is not dependent on distance from the magnet. This feature allows for in-batch consistency of separation time and efficiency. It improves cell viability and greatly increases bead recovery while also avoiding irreversible clumping. All of these features are important for process validation within a batch and between batches. This separation technology also allows for large-volume biomagnetic separation because the beads farthest from the magnet are easily recoverable.
Another useful feature of some modern separation racks is optical monitoring electronics. The system collects optical data throughout the process to track the transition from an opaque to transparent solution as the magnetic beads collect in the retention area. The associated software makes it possible to generate standard curves for each separation step of a given product, which allows for process validation between batches, and to validate batch-to-batch consistency.
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