title: Cryoprotectant redistribution along the frozen straw probed by Raman spectroscopy.
abstract: The distribution of cryoprotectant (10% glycerol) and ice along the frozen plastic straw (the most useful container for freezing mammalian semen, oocytes and embryos) was studied by Raman scattering technique. Raman spectroscopy being a contactless, non-invasive tool was applied for the straws filled with the cryoprotectant solution and frozen by controlled rate programs commonly used for mammalian embryos freezing. Analysis of Raman spectra measured at different points along the straw reveals a non-uniform distribution of the cryoprotectant. The ratio between non-crystalline solution and ice was found to be increased by several times at the bottom side of the solution column frozen by the standard freezing program. The increase of the cryoprotectant fraction occurs in the area where embryos or oocytes are normally placed during their freezing. Possible effects of the cooling rate and the ice nucleation temperature on the cryoprotectant fraction at the bottom side of the solution column were considered. Our findings highlight that the ice fraction around cryopreserved embryos or oocytes can differ significantly from the averaged one in the frozen plastic straws.
authors.affiliation: Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk, 630090, Russia.
authors.forename: Yu A
authors.initials: YA
authors.lastname: Karpegina
authors.affiliation: Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk, 630090, Russia.
authors.forename: K A
authors.initials: KA
authors.lastname: Okotrub
authors.affiliation: Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk, 630090, Russia.
authors.forename: E Yu
authors.initials: EY
authors.lastname: Brusentsev
authors.affiliation: Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk, 630090, Russia; Novosibirsk State University, Novosibirsk, 630090, Russia.
authors.forename: S Ya
authors.initials: SY
authors.lastname: Amstislavsky
authors.affiliation: Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk, 630090, Russia; Novosibirsk State University, Novosibirsk, 630090, Russia. Electronic address: lab21@iae.nsk.su.
authors.forename: N V
authors.initials: NV
authors.lastname: Surovtsev
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004622:Embryo, Mammalian / Q000187:drug effects; D005615:Freezing; D005990:Glycerol / Q000494:pharmacology*; D007053:Ice / Q000032:analysis; D008297:Male; D009865:Oocytes / Q000187:drug effects; D012662:Semen Preservation / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013094:Spermatozoa / Q000187:drug effects; D013696:Temperature
chemical_list: D003451:Cryoprotective Agents; D007053:Ice; D005990:Glycerol
keywords: Cryoprotectant redistribution; French straw; Glycerol; Program freezing; Raman spectroscopy