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When a magnetic field gradient is applied to a solution containing magnetic particles, aggregates of magnetic particles will separate out of the solution faster than individual magnetic beads. The increased speed is due to an increased magnetic moment as the beads gather and influence the magnetization of those nearby, and also due to a decreased drag force if the beads form chains. Therefore, it could be beneficial to attach a polymer to the surface of the magnetic beads that would help with aggregation.

Sepmagrecently connected with a new audience by publishing an article with theonline Oxford magazine Bang! Science.

Scaling up biomagnetic separation process is not just about quantity and quality of the production. One of the main concerns is the operational safety of using ‘big magnets’. As most of the classical magnetic separators are assemblies of permanent magnets in an open configuration, the use of large versions of these devices raises legitimate concerns about the risk for the operators and other laboratory/production equipment. As we will discussed later, the problem does not longer exist using advanced biomagnetic separation systems, but understanding the risks is also key for successfully implement in production environment.

A group of Iranian researchers have created a specialized biomagnetic sorbent using technology, which can be used to remove metallic ions from water with a view to being able to separate pollutants from the liquid and extract them.

Successfully scaling-up biomagnetic separation processes relies on determining the right working conditions. Having a constant magnetic force in the whole working volume guarantees the in-lot consistency, but manufacturing also needs to guarantee the lot-to-lot consistency.

Superparamagnetic iron oxide nanoparticles (SPIONs) are used widely in both research and clinical realms for magnetic separation, isolation, drug delivery, cancer therapy, and imaging. It is important to examine how these particles change during storage in order to ensure accuracy and consistency. A recent study of  particles stored for 12 weeks at temperatures ranging from 4°C to 45°C indicates that the particles significantly change in composition and biocompatibility over time, and that a storage temperature of 4°C allows the smallest magnitude of change.

Almost all life science magnetic beads projects start at small volume. The high cost of the biomolecules (antibodies, protein, nucleic acids….) and the uncertainties involved –what would be the right surface and protocol to coat the beads- make sound to work initially at scales of few milliliters.

As previously discussed, the problem is not working at small scale, but that we don’t pay careful attention when defining the biomagnetic separation conditions. If we leave this task for later stages of the development, we may find important bottlenecks for the scaling-up and, many times, jeopardize the whole project, as the initial conditions may not be scalable at a reasonable cost.

To scale-up a Biomagnetic Separation process, selecting the correct working conditions is beyond paramount. Almost any set of conditions may appear to work well enough at very small volume. Classical magnetic separators generate inhomogeneous magnetic force, having some beads magnetically saturated on regions near the retention areas and non-saturated beads in the rest of the working volume. For tubes of one milliliter or less the separation may apparently seems working fine, as the irreversible aggregation problem would not be noticed, the separation time is short and the magnetic beads losses not appreciable.

 To successfully scale-up a biomagnetic separation process it is necessary to understand how the magnetic beads behave. The separation speed depends on the balance between the magnetic force (generated by the field pattern and the moment of the beads) and the drag force (caused by the buffer viscosity). Thus, it is important to understand how this two forces act on a real magnetic bead suspension.

Through a statistical mechanism lens, magnetism can be explained by a lattice of binary spins that can range from a completely random arrangement to total alignment. The percentage of alignment determines the magnetization of the material. These spins are typically denoted as up (+1) or down (-1), and the energy states of the system are defined by an equation involving the spin values, the applied magnetic field, and the interaction strength between neighboring spins. These energy states can be averaged to calculate a total energy or magnetization of the system. Exact mathematical solutions have been defined for the first and second dimensions, but the third dimension continues to elude mathematicians. However, computer simulation makes it possible to model the behavior of magnets in any dimension in various applied magnetic fields at different temperatures.