Patent GB-942632-A (GB)
Title: Process and apparatus for storing biological substances at low temperatures
IPC: A61M1/02
Filed: 1962-03-29
Abstract: 942,632. Preserving biological substances. UNION CARBIDE CORPORATION March 29, 1962 [April 24, 1961], No. 12013/62. Heading A2D. [Also in Division F4] A container for the low temperature preservation of biological substances has at least two corrugated walls arranged and positioned in parallel relationship and being joined at their opposing ends by other walls so as to form an enclosed space between the corrugated walls for storing the biological substances, a sterile opening communicating with the enclosed space for the passage of the biological substances, and the container walls are constructed by a material having a K/L value of at least 2500 wherein K is the thermal conductivity of the material in B.T.U./(hr.)(ft.)(‹F.) and L is the material thickness in feet (or 10.3 when K is expressed in g.-cal./sec.-cm.‹C.). The corrugations which may sinusoidal or saw-tooth shaped, preferably have a uniform pitch of at least <SP>5</SP>/ 8  inch and a uniform depth of less than <SP>3</SP>/ 8  inch; the peaks of the corrugations of one wall are aligned with the troughs of the corrugations of the opposing parallel wall. In operation, a container filled to the extent of from 40 to 60% of its volume with a biological substance such as blood is immersed and shaken in an outer container containing a cryogenic fluid so as to provide a cooling rate of at least 10‹ C. per second in the temperature range 0‹ C. to -50‹ C.; the blood freezes as a thin shell less than 5 mm. thick formed over the entire inside wall surface of the container, as shown in Fig. 5. Enhanced cooling rates are achieved by coating the container with an insulating material having a thermal conductivity below 0.15 B.T.U./(hr.)(ft.)(‹F.) -(or 0.0006 g.-cal./sec.-cm.-‹C.). Biological substances: blood, bone marrow, and other suspensions of cells and biological fluids: Container construction: magnesium, aluminium or stainless steel employing wall thicknesses of from 0.007 to 0.050 inch, or plastics; copper is stated to give rise to objectionable toxicity: Insulating materials: epoxyresin adhesives, varnishes, vulcanised rubber, paraffin, rubber latex, paper masking tape, electrical insulation tape, petroleum jelly, asbestos, sodium silicate, kaolin and plaster of Paris: Cryogenic fluids: liquid nitrogen (preferred), liquid air, helium, neon, argon or krypton, and saturated solutions of dry ice in methyl alcohol: Thawing media: water or radio frequency energy. One of several examples is concerned with storing 293 cc. of whole blood in an aluminium container having a wall thickness of 0.024 inch, two sterile openings, and height 16 cm., length 18 cm., cross-sectional thickness 25 mm., in which the two opposing and largest walls had saw-tooth shaped corrugations; the walls were coated with an insulating mixture composed of 25% glycerol, 25% methanol and 50% of a light-weight, porous, dehydrolised, high-oil absorbent silica aerogel. The container was filled with the 293 cc. of whole blood and protective additives, immersed and shaken in a liquid nitrogen bath at 200 cycles/min. at an amplitude of 5 inches for 45 seconds. After storage, the container was thawed by immersion and shaking in a water bath at a temperature of 45‹ C.; the red blood cell recovery amounted to 95%. Specification 907,921 is referred to.