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Bead mill benefits outweigh ultrasonic homogenizers: While both homogenization technologies are effective for a variety of sample types and specific applications, bead mill technology is increasingly becoming the sample processing solution of choice.

Sample homogenization is a common step prior to extraction or analysis. For example, the quantification of the amount of compound via mass spectrometry can only be achieved if the sample is fully homogenized without degradation or contamination. Many extractions, such as DNA, RNA, proteins, enzymes and drugs, can provide sufficient yield only if the right homogenizer is used. Ultrasonic homogenizing technology has been employed in laboratories for more than 40 years. Recently, the use of bead mill homogenizing has become more prevalent as researchers are homogenizing greater numbers of sealed samples, and are increasingly concerned with consistent results and minimum sample carry-over. Smaller samples are now being studied and homogenized in various fields of research, including clinical, pharmaceutical, forensic, food and toxicology.

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Ultrasonic homogenizers, like the Omni Sonic Ruptor, rely on the Cavitation phenomenon by energizing and vibrating a high grade Titanium probe in liquid. The vibration at the probe tip forms vapor bubbles that implode (cavitation), creating infinitesimal shock waves to break the covalent cellular bonds.

Bead mill homogenizers, such as the Omni Bead Ruptor 24, rely on the mechanical interaction between beads and the sample inside sealed tubes. During this

AT A GLANCE

* Bead mill homogenizing has become more popular recently.

* The Omni Bead Ruptor 24 relies on the mechanical interaction between beads and the sample inside sealed tubes.

* Nanoparticle reduction and degassing of liquids can only be performed with ultrasonic technology.

AT A GLANCE

* Bead mill homogenizing has become more popular recently.

* The Omni Bead Ruptor 24 relies on the mechanical interaction between beads and the sample inside sealed tubes.

* Nanoparticle reduction and degassing of liquids can only be performed with ultrasonic technology process, the beads move within the tubes and impact the sample as they collide with the cells to release their nucleic contents. A fundamental aspect of this technology is the choice of the beads used--ceramic/zirconium, garnet, stainless steel, glass or carbide. Ceramic beads are ideal for processing soft samples like brain, liver or leaves. Garnet beads, with their sharp edges, are designed for processing soil. Meanwhile, stainless steel beads are suitable for processing dry and hard samples, and glass beads are ideal for processing microbial samples from gram-positive to gram-negative bacteria. Finally, carbide beads are designed to extract RNA from microbial samples and soil.

Bead mills vs. ultrasonic

With sealed tubes and mechanically controlled motion and programmability, bead mill homogenizers can provide consistent and reproducible results. Typically, ultrasonic homogenizing provides less consistency because of the use of open vials and manual placement of the probe in the sample. Additionally, ultrasonic homogenizers are known for creating With sealed tubes and mechanically controlled motion and programmability, bead mill homogenizers can provide consistent and reproducible results. Typically, ultrasonic homogenizing provides less consistency because of the use of open vials and manual placement of the probe in the sample. Additionally, ultrasonic homogenizers are known for creating foaming, evaporation, aerosols and heating, which affect the reproducibility. However, it is possible to control these side effects by using an ice bath, continuous flow chamber or cup horn.

Sealed tube processing can also be achieved with a cup horn/bath assembly, but energy transfer to the sample is significantly diminished, resulting in insufficient homogenizing for many samples. Bead mill homogenizers typically generate less heat. Some brands of bead mills can be used in conjunction with a cooling option, like the Omni Cryo 24, in order to maintain a constant temperature of 4 C that will Sealed tube processing can also be achieved with a cup horn/bath assembly, but energy transfer to the sample is significantly diminished, resulting in insufficient homogenizing for many samples. Bead mill homogenizers typically generate less heat. Some brands of bead mills can be used in conjunction with a cooling option, like the Omni Cryo 24, in order to maintain a constant temperature of 4 C that will preserve RNA, proteins, enzymes, metabolites and other sensitive biological compounds, and lead to premium quality extractions.

Ultrasonic homogenizing technology has three main advantages over bead mill technology--it is easier to recover sample components (such as membranes), larger sample volumes can be processed and nano-particle reduction and degassing of liquids can only be performed with ultrasonic technology.

Benefits of bead mills

Many applications can be completed with either an ultrasonic homogenizer or a bead mill. For Ultrasonic homogenizing technology has three main advantages over bead mill technology--it is easier to recover sample components (such as membranes), larger sample volumes can be processed and nano-particle reduction and degassing of liquids can only be performed with ultrasonic technology. Benefits of bead mills Many applications can be completed with either an ultrasonic homogenizer or a bead mill. For example, soft animal or human samples can be processed with both. Liver, lung, brain and intestine samples can be homogenized in under a minute with a bead mill, while it may take three or more minutes to achieve the same results with an ultrasonic homogenizes

This leads to the five main benefits bead mill technology has over ultrasonic technology. Bead mills can process a broader spectrum of samples in less time. Soft samples, such as liver and leaves, to extremely tough and fibrous samples, such as skin and seeds, can usually be homogenized in less than one minute. Dry, paraffin-embedded, frozen and fresh samples can also be processed with or without buffers, while ultrasonic homogenizers only process samples in liquid.

A bead mill homogenizer is a good alternative to ultrasonic technology, especially for tough-to-disrupt cells like cyanobacteria, yeast, spores and microalgae, because ultrasonic homogenizers generally cannot homogenize those samples without the addition of glass beads inside the sample to assist the lysis.

Bead mills are also a good alternative for tough-to-disrupt tissues such as skin, tendon or plant leaves. Ultrasonic homogenizers cannot homogenize these samples without significant sample preparation, such as pre-cutting, pre-grinding or macerating.

Bead mills can usually process multiple samples with the same homogenization quality, ensuring consistent results. They are perfectly suited for aerosol, microbial, airborne and biohazard applications because of sealed processing tubes and processing chambers, ensuring complete safety for the end-user when processing is done in a fume hood enclosure.

Sealed and disposable vials avoid the formation of free-radicals, thus preserving the biological integrity of the samples. Ultrasonic technology, on the other hand, creates free-radicals during cavitation despite the use of protective atmosphere, such as helium, nitrogen gas or heat control.

Selective and specific homoge- Selective and specific homogenizations are possible using different bead sizes and speeds of bead agitation.

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It is also possible to selectively disrupt only a part of the sample, such as the epidermal layer of whole leaves. Bead mills can disrupt cellular structure and extract analytes from non-vascularized or low-water-content tissues such as bone, hair or cartilage. Conventionally, acids or enzymatic digestion are used for DNA or nucleic acids.

In summary, ultrasonic homogenizers are ideal for processing emulsions, larger microbial and soft samples. Alternatively, bead mill homogenizers increase throughput by processing multiple small volume samples at a time, and are a good alternative to ultrasonic homogenizers because they allow scientists to quietly process a broader range of sample types in less time with high quality and reproducibility. Both technologies are effective for a variety of sample types and specific applications, but the desire for increased productivity, reproducibility and higher throughput is increasingly making bead mill technology the sample processing solution of choice.

CONTACT

For more information, contact Omni International, Inc. at 770-421-0058, or visit www.omni-inc.com.

by Alexandra Guerin Buxton, Omni International Inc., Kennesaw, Ga.
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Title Annotation:Feature
Author:Buxton, Alexandra Guerin
Publication:Laboratory Equipment
Date:Sep 1, 2011
Words:1254
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