Dear Lab Guy,
I have been trying to homogenize heart tissue in the Bel-Art Mini Liquid Nitrogen Cooled Mini-Mortar set (H37260-0100)
The pestle did not reach the bottom of the tube and the tissue got stuck at the bottom, so I did not achieve the desired result. I used regular 1.5ml Eppendorf tubes. Could you please advise me on what can be done about it? Thanks.
Lab Guy here! Sorry, you had trouble homogenizing. Depending on technique, a pestle can be used in tube to homogenize or “pelletize”. By ‘homogenize’, I mean that the pestle tip has reached the bottom of the MCT tube and that the side surfaces of the pestle are engaged, grinding, crushing, and mixing the sample for an even homogenization.
Now by ‘pelletize’, I mean that the hard, frozen sample is trapped at the bottom of the MCT tube and the only thing the pestle is able to accomplish is a pounding, compacting, and pelletizing of the sample as the tip of the pestle makes contact with the sample. It sounds like that was your case.
No matter how good our technique is, pelletization can happen, and in some cases, may be unavoidable.
The good news is, in almost all cases, you can overcome this pelletization by cutting or breaking apart the tissue mass prior to using your pestle. Being cognizant of sterility and contamination issues, I have found that a scalpel with a sterile #11 blade can easily reach the bottom of most tubes and nicely chop the pellet so it is easier to homogenize.
My goal is to move the pellet from the bottom of the tube in order to make room for the pestle to get in, so after 1 or 2 cuts, I momentarily remove the MCT from the mortar and carefully tap the contents to one side of the MCT, and while the tube is in this position quickly insert the pestle, wriggling it to the bottom while simultaneously turning the tube and then quickly placing it back into the cooled mortar. Time outside the mortar should be no more than 2-3 seconds. With the pestle now reaching the bottom, and my tissue samples along the pestle’s side, I can now resume the crushing and mixing pestle actions needed to successfully homogenize the sample.
I have used this method countless numbers of time and I have always found it to be quick and effective.
Thanks for writing to Lab Guy.