Today we'll learn more about breaking up irreversible magnetic bead aggregates with different methods such as the sonication method, are you ready?
Lluis M. Martínez, SEPMAG Chief Scientific Officer
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End product variability is caused in large part by resuspension problems in your process. During a magnetic separation process, the retention forces in the system need to be high enough that losses of the beads will be avoided when the buffer is pumped out. But the forces should not be too great because if they are excessive, beads will aggregate.
Bioreactors are an advanced phase of any production process, as small scale production has been left behind and scale up is being developed. Increasing the working and production volume brings many benefits to the process, but it is also more difficult to work with larger volumes, including when we work with magnetic beads.
Large magnetic systems create potentially high risk environments in terms of safety during a magnetic separation process. These systems generate large magnetic fields which result in the generation of large stray fields. The stray fields affect the surrounding environment and can attract ferromagnetic objects, potentially injuring system operators. The larger the system, the higher the risk, especially if workers do not follow Health and Safety protocols.
At the end of the month (July 28-August 1) Houston will host the AACC 2013 Annual Meeting, which includes the Clinical Lab Expo. The organizers claim that Clinical Lab Expo is the largest in the World. I am not in a position to endorse or refute this claim, but even if it is true, it is irrelevant from the perspective of the magnetic beads supply chain.
The concentration of magnetic beads is an important step in a magnetic separation process. Separation time is dependent on magnetic bead concentration, and final kit performance is also very dependent on accurate concentrating techniques, but liquid handling inaccuracies can lead to serious errors. If these concentration errors are not detected early in the process, excessive time, money and effort will need to be spent to either correct or redo the batch.
The sonication method is a very effective method for breaking up magnetic bead aggregates, but it is not a panacea. It is an efficient technique once all of the parameters are set, but it is a complex technique with some important limitations, especially for high volume processes.
Irreversible aggregation of magnetic beads is a great concern among researchers because of the variability it introduces into the process. Knowing how to deal with these aggregates when they do form, with techniqes like the sonication method, is the best way to increase in-lot consistency.
When one scales up production using a classic magnetic separation system, one finds that the separation time increases quickly with an increase in production volume. An increase in separation time means that material losses are higher and aggregation problems become a serious problem. By using homogenous separation time, one finds that the magnetic separation process is shorter and the separation time can be easily estimated. In homogeneous systems material loss and bead aggregation is minimized.
Magnetic beads need to be constantly mixed and homogenized to avoid sedimentation and clumping problems. Even when the sonication method is necessary to break up aggregates, mixing and homogenization is necessary.
