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.
During these early stages, separation processes are usually developed on a small scale using existing laboratory magnetic racks. Once the kit has been developed, the batch volume is increased and a different magnetic separator is used. If the working conditions are not well defined, the magnetic force over the beads is completely different with the new system, which is when losses and irreversible aggregation problems occur. A costly re-engineering process is then needed to resolve these issues and to keep losses and clump formation to levels low enough to provide a cost-effective and efficient production process.
Figure 11. Schematic representation of magnetic force on a small scale (left) and a large scale (right) inhomogeneous magnetic separation racks
Remember to download our free guide Five critical mistakes in CLIA IVD-kits manufacturing to learn about all these mistakes:
On a small scale, it is easy to have a high magnetic field gradient. Even if all the beads are not magnetically saturated the separation time is short because the distances travelled are also short. But inhomogeneous conditions on a larger scale involves greater losses (lower force at larger distances) and exponentially longer separation times. Over short distances, forces can be higher, increasing the risk of irreversible aggregation. The latter issue is aggravated by longer separation times.
In contrast, homogenous Biomagnetic Separation conditions are easy to scale up. When using homogenous gradient the force can be kept constant even at large volumes. As a result, a biomagnetic separation process without magnetic beads losses, and without irreversible aggregation of the beads can be reproduced at different volumes. To do this, beads need to be magnetically saturated for optimal performance (constant force). In advanced biomagnetic systems like SEPMAG® systems, the device always maintains the same suboptimal volume at instant t=0 (about 7% of the volume), guaranteeing that the whole batch volume is subject to constant force whatever the scale.
Figure 12 Advanced Biomagnetic Separation systems at different scales.
The key to avoiding Mistake #4 (Neglecting process scalability) is to correctly validate the magnetic separation conditions early on in the development process, preferably when working on a small scale.
Working with homogenous Biomagnetic Separation from the initial small volume, will give you a well-defined process condition, which makes scaling-up straightforward. It also drastically reduces the length of time and the resources needed to move from R&D to production, and to scale up larger volumes when the demand for kits so requires.
Figure 13 Use of small tubes in homogenous biomagnetic separation systems. The magnetic force over all beads is the same when a large bottle is placed in the system.
- Mistake #1 in CLIA IVD-kit manufacturing: Blaming the magnetic beads
- Mistake #2 in CLIA IVD-kit manufacturing: Using bigger magnets to avoid losses
- Mistake #3 in CLIA IVD-kit manufacturing: Defining the process based purely on the separation time