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sonication method

Mixing and Homogenizing Magnetic Beads without Touching the Suspension

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!

Download our Free Guide on magnetic bead resuspension HERE.
Avoiding contamination

One of the biggest worries of scientists and technicians in a lab is contamination. Avoiding contamination is best accomplished by using closed mixing vessels (normally closed roller bottles). Closed vessels allow constant mixing and homogenizing without worrying about contacting the suspension. Roller mixing can also be easily scaled up to tens of liters.

This post is about resuspension techniques, such as the sonication method, and how they can solve magnetic bead aggregation. If you are interested in this topic, download our free ebook The basic guide for resuspending magnetic beads:

Contamination can also be a problem if beads are stored for long periods of time. During this time in storage it is important that beads are constantly mixed and homogenized in order to avoid the sedimentation and aggregation that can increase variability and adversely affect in-lot consistency. Because of these potential difficultiess, closed roller bottles and roller mixers are commonly used for long term storage of magnetic beads.

The problem with closed bottles

The main problem of using closed bottles is that buffers need to be changed many times during the production process. During washing steps in biomagnetic separation, for example, the liquid needs to be manually extracted and replaced with new buffer several times. If mixing and homogenizing processes are performed using roller mixers requiring closed bottles the vessels must be closed tightly after each separation step. If the caps are too loose, or if the seal is compromised in any way, leakage can occur causing a loss of material and variability of the resulting product.

Roller mixers are used to homogenize, but sonication method breaks aggregation If roller mixers are still the homogenization method of choice, even with the above limitations, there is a way to use them with open bottles. The vessels must be placed in a near vertical position and then tilted for turning. If used in this way, the bottles should not be completely filled in order to avoid spills and contamination. The angle of tilt and the turning speed can be adjusted to guarantee optimal homogenization of the suspension. If the technique is done properly and care is taken to protect the beads and the liquid, one can easily change buffers and maintain the magnetic beads in a homogenized state with little difficulty.

Contamination should be a constant focus and concern when homogenizing magnetic beads or keeping magnetic beads in suspension over long periods of time. Although closed bottles are good protection against contamination during homogenization, constant opening and closing the bottles between wash steps can introduce contamination as well. Using open roller bottles on a tilted roller table affords the user the ability to homogenize without touching the liquid while not losing any of the solution, as long as the bottle angle and speed of rotation is carefully chosen.

Don’t forget to check these posts from our blog in order to get a deeper insight into magnetic bead resuspension:

Dr. Lluís Martínez

The basic guide for re-suspending magnetic beads

Lluis M. Martínez | SEPMAG Chief Scientific Officer

Founder of SEPMAG, Lluis holds a PhD in Magnetic Materials by the UAB. He has conducted research at German and Spanish academic institutions. Having worked in companies in Ireland, USA and Spain, he has more than 20 years of experience applying magnetic materials and sensors to industrial products and processes. He has filed several international patents on the field and co-authored more than 20 scientific papers, most of them on the subject of magnetic particle movement.

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