Non-specific background and auto-aggregation in chemiluminescent immunoassays are often caused by the presence of exposed hydrophobic surfaces on the magnetic beads. The use of a blocking reagents combined with gentle homogenous bio-magnetic separation will help reduce background and auto-aggregation of your coated beads.
Lluis M. Martínez, SEPMAG Chief Scientific Officer
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It is vitally important to understand the process and all of the variables of the process when scaling up a biomagnetic separation in a magnetic separation rack. If you do not understand the details of your process, you will throw away your initial investment you made in validating your initial process and jeopardize the product’s time to market.
Stability of magnetic bead IVD kits over time is important and should reflect the environment that is typically encountered by their reagents. For example, if the reagents will be frozen and thawed, stability should be addressed in these conditions. Magnetic beads, such as streptavidin beads, may behave heterogeneusly in different conditions, so these should be preserved when performing stability studies.
The most common mistake when attempting to scale up production of magnetic beads using a classical magnetic separation rack is to use the same magnetic field that was used at smaller volumes. But keeping the magnetic field constant at different volumes will not give you the same results because the separation conditions are completely different.
Sometimes companies scale up production in a magnetic separation rack in order to produce large quantities. However, for validation batches or new processes, they may not need to work at the large scale level. In addition, different steps of the process may require different volumes. For example, if you are producing a large ‘mother batch’ of magnetic beads, different portions of that ‘mother lot’ may be used for unique coatings. Another example is when small validation lots of a product need to be produced before launching full scale production of the product.
As we have explained in previous posts, magnetic beads can aggregate due to different reasons, bringing problems to the processes they are used for. If you want to learn more about breaking up irreversible magnetic bead aggregates, with techniques such as the sonication method, keep reading!
Although there are many choices you can make when determining bead surfaces, there are five predominant types of magnetic beads currently used most often by Chemiluminescent Immunoassay (CLIA) companies.
Chemiluminescent immunoassays (CLIAs) are excellent assays for high-throughput, low analyte concentration and time sensitive testing and isolation. Using coated magnetic beads, such as streptavidin beads, as the reagent in a CLIA is an easy and established technique favored among many clinical scientists.
The main consumers of magnetic beads are In Vitro Diagnostic (IVD) companies who utilize these materials for their kits. Since some of these companies are highly successful, as they obviously need to cope with higher demand for their kits by increasing production in a magnetic separation rack.
When you decide to scale up your process, one of the most difficult parameters to determine in a non-homogeneous magnetic separation rack is the separation time. In scaled-up non-homogeneous devices, you must use longer separation times in order to gain the same bead yield as a smaller process. However, it is still difficult to determine when the separation is complete.
