When designing a biomagnetic separation strategy it is easy to get caught up in the properties of the superparamagnetic beads and their functional coatings. It is exciting to choose a bead and tailor its surface ligands to perfectly match your target molecule, but don’t stop there! The magnetic separation rack is equally important to a successful identification, isolation, or enrichment protocol. After all, a perfectly designed bead will be useless without a properly designed magnetic rack to recover it from solution.
A properly designed magnetic separation rack is essential
A properly designed rack is tailored to the sample size and has well defined working conditions to ensure that all bead-target conjugates are recovered. Classic separation racks are not always properly designed as can lead to problems with bead recovery, target viability, and slow separation times. Advanced separation racks are engineered to obtain high recoverability rates and fast separation times to make the magnetic separation process easier and more effective.
- Classic separation racks generate a magnetic force that changes with distance from the retention area. The problem with this design is that a high retention force is needed to collect the beads farthest from the retention area at the expense of the beads closest to the retention area. Excessive force generates irreversible aggregates closest to the retention area, especially if the separation time is large due the slow separation speed of the beads farthest away. This lack of consistency may be confusing, and troubleshooters may erroneously look for problems with the beads or coating process. Much time and money can be wasted this way when the problem is really a result of the inhomogeneous force from a poorly designed separation device. The retention force must be uniform at any distance away from the retention area so that it can affect the farthest beads and avoid losses or very large separation times.
This is especially important during biomagnetic cell separation. The excessive force generated by a classical separation rack can damage cells by causing them to burst or break their cell membranes. A separation rack that generates a uniform retention force throughout the working volume will not have excessive force at the retention area and is gentle on cells. These types of separation racks will not cause cells to break or burst and will improve cell viability and separation efficiency. This feature will provide many benefits to downstream applications in cell culture and cell-based assays. If the cells are not stressed during the separation process then they will be healthier throughout the culturing and subsequent assays and have fewer confounding variables. Cells are very susceptible to stress and will release stress molecules that change their morphology and behavior. If a magnetic separation rack introduces too much stress due to excessive force at the retention area, then all downstream cell-based assays may be compromised.
- Advanced separation racks generate a magnetic force that is homogenous over the working volume (i.e. the force is constant regardless the distance to the retention area). That provides a larger force over the farthest beads, avoiding losses and speeding up the separation process as well as avoiding irreversible aggregation. These features open the door to multiple washings without losing material. Moreover, as all the beads experience the same force during the same time, the consistency is extremely high.
Sepmag manufactures advanced biomagnetic separation racks that offer fast separation time and high recoverability rates. These separation racks ensure that a gentle homogeneous magnetic force is applied during the separation process, and also incorporate real-time monitoring of the process. While the operator can often visualize when separation is complete by watching the solution change from cloudy to clear, software such as the Sepmag quality control recording (QCR) system can automatically track the progress of the sort, provide quantitative feedback, and diagnose problems as early as possible. Additionally, the use of standard separation curves for system calibration guarantees a high quality and consistent separation time after time.
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