Glass has a density of 2.5 g/cc and is the most commonly used bead media for 'Beadbeating'. Beads are sold in one pound bottles.
SIX SIZES AVAILABLE:
Cat. #LS-79101 0.1mm diameter Glass Beads
Cat. #LS-79105 0.5mm diameter Glass Beads
Cat. #LS-79110 1.0mm diameter Glass Beads
Cat. #LS-79127 2.7mm diameter Glass Beads
Cat. #LS-79135 3.5mm diameter Glass Beads
Cat. #LS-79635 6.5mm diameter Glass Beads
CLICK HERE for Information on Bead options.
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Information For Cell Disruption Applications
Size of Beads
- When working with Bacteria use the 0.1mm diameter glass beads.
- When working with Yeast/Fungi use the 0.5mm diameter glass beads.
- When working with Most Tissue use the 1.0mm diameter glass beads or zirconia/silica beads.
- When working with Skin or 'soft' plant material use a 2.0mm diameter zirconia beads.
- When working with tough or fibrous tissue use the same sized beads (see above) but choose a more dense bead material. For example, researchers prefer 0.1mm zirconia-silica beads for disruption of spores or 2.3 mm chrome-steel beads for extraction of tough fibrous plant material like monocotyledon leaves. Some users have had good results using the MiniBeadbeater in a 'dry grinding' process - either at ambient or at liquid nitrogen temperatures. For example, a single seed can be pulverized into a fine powder in 30 seconds using one 6.3 mm diameter chrome steel bead in our 2 or 7 ml vials.
- Critique: Special and supposedly unique combinations of different sizes and types of beads in the same vial are mostly marketing hype from certain vendors of pre-filled microvials. There is little, if any, comparative documentation available to back up their claims of enhanced performance. With limited exception, measurable improvements in cell lysis derived from "magic" bead combinations are marginal.
Density of Beads
- Glass has a density of 2.5 g/cc (most commonly used bead media for 'Beadbeating')
- Zirconia/Silica has a density of 3.7g/cc (50% more dense than glass - good for spores and most tissues)
- Silicon Carbide (sharp particle, not a bead) has a density of 3.2 g/cc (May work faster on tough tissue samples because the particles have sharp cutting edges. Their utility is still under investigation, but see Brein's comments below)
- Garnet (an iron-aluminum silicate, sharp particle) has a density of 4.1 g/cc. Like SiC particles, it may accelerate lysis of tough tissue due to its sharp edges. However, garnet particles are easily fragmented during beadbeating. Facile separation of the final grinding media from the homogenate can be problematic. Nevertheless, this very fragementation during beadbeating may be useful when homogenizing tissue, fecal or soil samples containing bacteria because you end up with a useful size mix of grinding media that can both rapidly disperse the sample and also disrupt the microorganism. For this specialized application, start off with the vial containing 1 or 2 mm sized grinding particles.
- Zirconia has a density of 5.5g/cc (100% more dense than glass - good for tough tissue). Chemically inert and resistant to fragmentation.
- ChromeSteel and Stainless Steel has a density of 7.9g/cc . Used mostly for grinding leaves and seeds. Only 1-3 steel beads are added to the microvial. Stainless steel beads are expensive but reusable. Chrome steel beads are a recommended substitute for s.s. beads. They are 10X cheaper...cheap enough to be use once and thrown away. Thus, no cleaning or cross-contamination concerns.
- Tungsten Carbide has a density of 14.9g/cc. While very dense, this bead is generally not used for biopreps - it leaves prep dirty.
Cleaning Your Beads
In most cases, cleaning new glass or ceramic bead media is unnecessary. Most researchers use them straight out of the bottle. The only contaminate - carbon black - is so inert that its presence in your prep has no effect. And, it is soon removed upon centrifugation or filtration in the steps that usually follow cell disruption. Do not acid wash beads. It is a waste of time.
Clean used glass or ceramic beads for reuse by soaking in a solution of laboratory detergent (the kind used to wash labware). Now and then, agitate the beads by swirling. Then rinse away all detergent with several changes of tap water and then with RO- or distilled water. Dry the beads in an open stainless steel or glass tray at 40 to 70ºC. If the dried beads do not pour freely (i.e., they are caked together), then they were not cleaned or rinsed well enough. Repeat the cleaning protocol.
Cleaning chrome steel or stainless steel beads requires a modified procedure. The washing step must be short - lasting only a few minutes. Ditto for the water rinse. Then, promptly remove all water from the surface of the beads by washing the beads with three changes of absolute (100%) ethanol, pure (100%) isopropanol or acetone. Air dry at RT or in a warm oven to flash evaporate the solvent. Store clean, dry beads in a sealed bottle.
If you are isolating nucleic acids from disrupted cells, an alternate cleaning method is to immerse the beads in a 1:10 dilution of ordinary household bleach (Clorox or equivalent) for 5 minutes. This not only cleans and sterilizes the beads, but completely destroys contaminating nucleic acids (see Biotechniques, Vol 12, 358-360 (1992)) and nucleases. Thoroughly rinse the beads with water afterwards.
All beads can be autoclaved with steam. But first make sure the beads are clean. Note a recent report in Biotechniques (Vol.55, Issue 6, p.296-299, Dec 2013). The authors state: "Autoclaving at standard conditions (121º C for 20 min) does not sufficiently remove the template activity of contaminating DNA. Autoclaving at 121º C for 80 min is recommended. The presence of air during autoclaving also facilitates nucleic acid decomposition."
Finally, a sucessful proceedure to sterilize and also destroy any residual nucleic acids on clean glass, ceramic or steel beads is baking the beads at 550º F for 2h or 400º F for 4 h.
You can reuse beads about ten times before they wear down to too small a size.