QIAshredder

Yield and integrity of genomic DNA depend on the disruption and homogenization method used with the Allprep DNA/RNA Kits.

Homogenization with the TissueRuptor (or other rotor–stator homogenizer, such as the Polytron) or the TissueLyser results in greater DNA fragmentation (depending on homogenization time and intensity). However, shorter DNA fragments are easier to elute, so DNA yields will be higher.

In contast, homogenization using the QIAshredder (or a syringe and needle) is more gentle, resulting in less DNA fragmentation. However, longer DNA fragments are more difficult to elute, so DNA yields may be lower.

The QIAshredder is a unique biopolymer shredding system in a microcentrifuge spin-column format. It homogenizes cell or tissue lysates to reduce viscosity. Homogenization shears the high-molecular weight genomic DNA and other high-molecular-weight cellular components to create a homogenous lysate. The QIAshredder is chemically inert and will not bind nucleic acids.

It cannot replace tissue disruption or enzymatic cell wall lysis by mechanical and chemical methods, respectively. Both, efficient cell wall disruption and lysate homogenization are fundamental for successful RNA isolation from all types of samples. Once complete disruption has been achieved, the QIAshredder Homogenizer can be used in place of needle and syringe, or rotor-stator homogenization.

For further information regarding sample disruption and homogenization please refer to the 'Disruption and homogenization of starting materials' section in the RNeasy Mini Handbook, and see FAQ 139.

The QIAshredder Maxi spin columns  from the DNeasy Plant Maxi Kit are not recommended for use in conjunction with QIAGEN's RNA isolation products. The filter can only tolerate low centrifugal forces not sufficient to shear genomic DNA. If genomic DNA is not sheared, there will be an increase in genomic DNA contamination in the purified RNA.

For an alternative to QIAshredder homogenization in combination with RNeasy Midi/Maxi Preps, please see FAQ 560.