Quantifying Cross-Contamination from Tissue Homogenization with a Rotor-Stator Homogenizer Equipped with a Stainless Steel Generator Probe

In research labs, rotor-stator homogenizers are critical pieces of equipment as they are routinely used as the first step in many experimental workflows. Rotor-stator homogenizers are used to break down solid samples to create a homogenous mixture and release internal analytes such as proteins and nucleic acids prior to downstream analyses. The rotor-stator homogenizer functions by rapidly spinning the rotor with high speed, creating a vacuum that pulls the media between the rotor and outer stator. The media is pushed axially until they reach the gaps in the stator at which point the media is subjected to rapid deceleration forces that lead to sample disruption; a process known as shearing (Figure 1).

While rotor-stator homogenizers are extremely effective, with the exception of automated platforms like the Omni Prep 96 and LH96 workstations, they are one use tools in which samples must be processed on an individual bases. Between samples, researchers must clean the generator probe to remove sample particulate in order to prevent cross-contamination between samples. Typically the cleaning method involves running the homogenizer at low speed in a clean liquid to “spin out” particulate retained in the probe. In some cases solvents such as ethanol can expedite the cleaning procedure. To reduce cross-contamination risk significantly, especially for studies involving nucleic acids, the generator probe must be fully disassembled, cleaned and autoclaved prior to the next sample being processed. 
As an alternative to stainless steel generator probes, disposable plastic Omni Tip™ generator probes can be disposed of after each use to significantly reduce cross-contamination risk (Figure 2).

Herein, we evaluate the effectiveness of standard generator probe cleansing processes to quantify the degree of DNA and protein carryover from sample to sample using a standard stainless steel generator probe.

Table 1. Protein and DNA concentrations as a function of wash steps. LOD indicates limit of detection.