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 small 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.
How the BioSqueezer is operated...
A small beaker, styrofoam cup, or similar vessel is placed on the BioSqueezer 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. The cooling process takes about a minute and, once cooled to the desired temperature, the stainless metal clamp head will remain adequately cold for several minutes. The vessel is removed and the fresh sample, by itself or already placed in a sterile poly-bag, is placed on the platform. The s.s. head is quickly lowered and clamped. Clamping 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 easily adjusted by changing the position of the metal clamp head with the wing nut, black plastic nut and stainless steel hex bolt.
The thin wafer of tissue can be manually fragmented inside the poly bag while still hard frozen. Fragmenting hard frozen tissue into small pieces speeds up subsequent chemical extraction or mechanical homogenization and also inhances the penetration of RNAlater™ and other expediants used for tissue preservation and stabilization of intracellular biochemicals.