Cryogenic homogenization can be very useful for disrupting highly resilient samples, or when isolating biochemicals that are extremely sensitive to thermal or enzymatic degradation. The traditional method of cryogenically grinding materials involves the use of a mortar and pestle placed in a liquid nitrogen bath. With bead beating, materials can be placed in a bath to chill, but homogenization vessels, grinding media, and sample must be removed from the bath for processing. Depending upon the processing conditions, it is very common for samples to warm and melt. Consequently, Cryoblocks were designed to act as a cold reservoir during processing in order to keep samples frozen.
Though Cryoblocks are not mandatory for cryogenic homogenization, they are very useful. Cryoblocks are solid rectangular bars of aluminum that have been machined to hold 4 ml and 50 ml polycarbonate vials. The blocks have essentially the same footprint as a 96 well plate. Prior to sample processing, Cryoblocks are placed in a CryoCooler™ or similar device and chilled with liquid nitrogen. Vials are loaded into the blocks (vials with sample can be pre-frozen) along with sample and allowed to chill. Balls are then dropped on top of the samples and also allowed to chill. Caps, however, are not pre-chilled because they are made of polypropylene and will become very brittle if chilled to cryogenic temperatures.
The vials are capped just prior to bead beating. The Cryoblock is removed from the CryoCooler and placed in the homogenizer. Only the GenoGrinder® and 1600 Mini G™ are capable of holding Cryoblocks. The GenoGrinder® can hold two while the 1600 Mini G™ can hold one. Processing the samples should yield a powder. Return the Cryoblock and samples back to the CryoCooler so that the samples do not melt.