Preparation of Sample
Use 0.1 mm beads for bacteria, 0.5 mm beads for yeast, fungi and tissue culture cells and 1.0 mm or 2.5 mm beads for fresh plant and animal tissue. If you have solid tissue, pre-chop it into pieces with a single-edge razor blade**. Up to 400 mg (wet wt) of biomaterial can be disrupted per ml of extraction media. In most applications, beads made of glass or zirconia-silica give excellent results. In special cases (grinding dry leaf material, wet grinding soaked seeds, disrupting skin or cartilage) beads made of denser material such as zirconia or steel may be required. Click here for additional guidelines on selecting bead media.
** Tissue samples sizes over a few tens of milligrams should be prechopped into pieces less than 1 mm in cross-section. If your sample is already harvested and frozen, do not thaw. This is especially important if you are isolating nucleic acids. Rather, Cryopulverize the sample. For information on this method see http://www.biospec.com/product/40/biopulverizer
Fill the screw-cap vial at least 1/2 full (1/2-3/4 is okay) with beads. Then add extraction media and cells, being sure to fill the microtube almost to the top. Exclude as much air from the microtube as possible. Use screw-cap microtubes with integral o-ring seals in order to eliminate aerosol formation during the homogenization. Be sure there are no beads on the threads of the microtubes when screwing down the cap.
(CAUTION - snap-top microtubes release aerosol. Nevertheless, it is possible to use snap-top microtubes in the MBB-24. However, a special adapter ring will be required. Call for information)
Operating the Mini-BeadBeater
1) Load 1 to 24 microtubes into the clear, vial holder ring holder. Distribute them symmetrically as you would do with a centrifuge. If using less than 4 sample vials, insert vials so that at least four vials are in the holder.
2) Place the loaded vial holder ring on the aluminum wiggle head (the later being attached to the motor). Rotate the loaded vial holder ring to a position where the hole in the vial holder ring is aligned with the anti-rotation pin sticking out of the wiggle head. Slide the vial holder ring down the pin and seat it on the wiggle head. Next, align the large, black plastic hold-down cap and slide it down to contact the tops of the microtubes.
3) Screw on and firmly hand tighten the aluminum knob. To do this, the locking pin, which is part of the knob, must be in the down position. A slight twist of the pin keeps it in either a down or raised position. As you tighten the aluminum knob a clicking sound will be heard as the locking pin engages holes in the black hold-down cap.
IMPORTANT! The locking pin is an important safety feature. Test that the pin has engaged into one of the ring of holes on the hold down cap. To do this, attempt to further tighten the knob. Do not proceed if the cap does not lock. Raise up the pin on the aluminum knob and repeat the tightening, locking and testing process. Failure to sufficiently tighten the aluminum knob or to engage the locking pin can result in rapid distruction of the central shaft of the aluminum wiggle head.
4) Set the timer. A typical setting for cell disruption is 2-3 minutes. (Note: If you are working with heat-sensitive material, consider homogenizing for a shorter period, say 1 minute, then remove the vial holder with its vials and cooling the vials in ice-water mix for 1 minute. Cycle thus, for a total runtime of three minutes. No cooling is needed for nucleic acid extraction providing you are doing cell disruption in nucleic acid extraction media).
5) Select the shaking speed with the slide knob on the top of the MBB-24. The speed can be varied from about 2000 oscl/min (2.0 on the speed label) to 3450 oscl/min. Speeds lower than the maximum are seldom used in cell disruption applications except in special circumstances. Converting low settings discribed in the literature for FastPrep 24 (MP Biomedicals) machines are problematic as their speed setting are defined in confusing units of M/sec. As a rule, operating a MBB-24 at its maximum 3450 rpm will deliver optimal cell disruption yields.
6) Start the machine by pressing the start/stop button. The timer resets itself automatically at the end of the run.
7) To remove the vials and vial holding ring, first raise the locking pin in the up position (a slight turn of the locking pin knob will keep it in the raised positon). Unscrew the aluminum knob, remove the black vial hold down cap and, finally the vials in their vial holding ring. The vial holding ring can be conviently be place on our provided blue vial ring holder.
The MBB-24 will only operate with the black plastic hood closed over the shaking mechanism. This prevents the user from coming in contact with the shaker during operation and helps trap any material that might leak or break free.
Internal components of the MBB-24 have no servicable parts. Bearings sealed inside the wiggle head can get hot during prolonged operation. While not a requirement, allowing the bearing to cool down between runs will increase the lifetime of the bearing.
The large, black O-ring just below the aluminum wiggle head will need to be replaced from time to time. Without the O-ring the aluminum wiggle head will spin rather than shake. See BioSpec for a repair kit should the O-ring break. Replacement is a simple, 10 minute proceedure.