The BioSqueezer is used to quickly freeze 10-100 mg of soft animal and human tissue. Fresh tissue is compressed into a thin disc about the size of a coin under the pressure of a stainless steel clamp head that has been pre-cooled in liquid nitrogen or dry ice. Freezing occurs in a few milliseconds, thus giving a snapshot of metabolic events in the cells. The hard frozen disc is easily fragmented or ground without thawing for subsequent extraction of labile nucleic acids, proteins and intracellular metabolite products.
A small beaker, styrofoam cup, or similar vessel is placed on the platform and the metal clamp is lowered. Liquid nitrogen is slowly and carefully poured into the vessel until the boiling action of the liquid nitrogen subsides. This cooling process takes about a minute and, once cooled to the desired temperature, the stainless or aluminum metal clamp head will remain adequately cold for several minutes. The vessel is removed and the sample, by itself or already in a poly-bag, is placed on the platform and the knob quickly lowered and clamped. The clamping step must be done rapidly or the sample will freeze uncompressed.
It may be necessary to adjust the BioSqueezer using 'practice' tissue. The optimal clamp setting can vary with the softness and size of the tissue sample. Clamping force and the degree of squeezing on the tissue can be adjusted by changing the position of the metal clamp head with the wing nut, black plastic nut and the stainless steel hex bolt.
The thin wafer of tissue can be manually fragmented inside the poly bag while still frozen. Presenting the tissue in small, thin pieces is ideal for quick homogenization and extraction or for storage in appropriate stabilizing solutions such as RNAlater™ or other excipients.