What is the difference between the Bioruptor™ and a traditional probe system?

Traditional sonicators use a probe that is directly in contact with the biological sample.
This has major drawbacks in terms of reproducibility as the sonication energy depends on the depth
of the sonication probe in the liquid.
Moreover the probe system is tedious to work with, produces foam, and only one sample can be treated
at a time.
Also contamination between different samples is also frequently experienced.
Additionally, the probe system generates aerosols, which are hazardous by bio safety rules.

293T cells were fixed with 1, 5 % formaldehyde during five minutes at 37° C.
Each lane shows purified chromatin fragments from 5.10e6 cells lysed in 300 µl of buffer
and sonicated in Eppendorf 1, 5 ml tube.
Sonication during 5 cycles (30 sec. ON & 30 sec. OFF) at « High » settings.
First lane shows chromatin from an Eppendorf tube sonicated individually.
Lanes 2 to 7 show chromatin from 6 tubes sonicated at a time.
Unsonicated chromatin is shown in lane 9 .

What is the effect of ultrasound on biological samples?

A generally accepted view is that ultrasound produces a gaseous cavitation in the liquid.
This term describes the formation of small bubbles from dissolved gases or vapours due to alteration
of pressure. These bubbles are capable of resonance vibration and produce vigorous eddying or micro
streaming, which is sufficient to break cells.
Also, the fragmentation of DNA takes place as a consequence of mechanical stress or shear
from the bubbles.
With a probe sonicator, the micro streaming phenomenon is limited to the vicinity of the probe,
whereas for the Bioruptor™, the whole volume of water present in the tank is exposed to ultrasound energy.
For 15 ml or 50 ml tubes, a metallic bar in contact with the sample facilitates the transfer of the ultrasounds
inside the tubes. This metallic bar is not a probe but it “reflects” the ultrasound originated from the water
bath and improves the sample sonication efficiency by a patented resonance system.
As it is made of stainless steel it is not prone to corrosion.
The figure below schematizes the resonance of the ultrasound on the metallic bar.

The following references are useful to better understand the sonication process:
 
Elsner, H., Lindblad E. Ultrasonic degradation of DNA . DNA, 8, p697-701 (1989).
Hughes D., Nyborg W. Cell disruption by ultrasound. Science, 138, p108-14 (1962)

Why to buy a Bioruptor™:

SIMPLE OPERATING PROCEDURE:
 
•  Automatic power switch, no tuning button
•  Different adaptors available to sonicate variable volumes
•  Possible to sonicate small samples (down to 5µl)
•  Use of standard disposable containers (PCR tubes, Eppendorf, 15ml Corning / Falcon tubes)

SONICATION IN SEALED TUBES:
 
•  No aerosol formation - improved biosafety
•  No risk of contamination between samples
•  No tedious manipulation of probes
•  Reduced “foaming”

BETTER REPRODUCIBILITY OF RESULTS:
 
•  Sonicate up to 12 tubes in a single run
•  Continuous rotation of tubes allows even distribution of energy
•  Better temperature control improves preservation of epitopes
•  Allow standardized transfer of protocols between labs

VALIDATED ChIP PROTOCOLS:
 
•  Protocols available to obtain 500 bp DNA fragments or smaller
•  Proven performance in DNA disruption for ChIP assay