Measurement of effective thermophysical properties for Cryopreserved-State evaluation in frozen red blood cells suspension

The purpose of this study is to estimate the viability of frozen biological materials during cryopreservation with the thermophysical properties. Human red blood cells are selected as test biological material. Propylene glycol (0, 10 and 35%w/w) was selected as cryoprotectant. The test chamber was contacted with carbon heater on a copper block immersed in liquid nitrogen, and cooled from room temperature to -196°C at a cooling rate of 1 to 300°C/min. Temperature rise of 5°C was applied to the suspension at -190°C, the effective thermal diffusivity was determined with Laplace transform method. As a result, the effective thermal diffusivity decreased with decrease of intra-and extracellular ice formation fraction in their suspension, which affects their survival after thawing. Thus assessment of cryopreserved biological materials can be achieved with the thermophysical properties.