Research On The Ice-control Properties Of Graphene Oxide Nanosheets And Their Application In Cell Cryopreservation

In the process of low-temperature freezing and rewarming of cells,the damage caused by the formation and recrystallization of ice crystals directly affects the activity and survival rate of cells.Therefore,there has been considerable interest in biomimetic antifreeze materials with ice crystal inhibition effects.These materials aim to ensure the safe survival of cells during the rewarming process.By utilizing biomimetic antifreeze materials with photothermal conversion properties as auxiliary heating agents,the heating rate can be increased,and the recrystallization of ice crystals can be reduced.Graphene oxide has demonstrated the ability to modify ice crystal morphology and inhibit ice crystal recrystallization in cell cryopreservation.Additionally,it exhibits infrared absorption in the near-infrared band.Hence,the ice crystal inhibition effect of graphene oxide nanosheets size and its impact on cell survival during cell photothermal-assisted recovery have been studied.These investigations not only contribute to the theoretical research of biomimetic antifreeze materials but also hold practical value as a cell cryoprotectant.Therefore,this thesis focuses on the preparation of five different-sized graphene oxide nanosheets as cryopreservation agents in cell cryopreservation.The graphene oxide nanosheets were prepared using an improved Hummers method and an ultrasonic process.These methods addressed the limitations of traditional preparation methods,such as their explosiveness and flammability.The micromorphology and structural composition of the graphene oxide nanosheets of varying sizes were characterized using transmission electron microscopy(TEM),ultraviolet-visible-near-infrared photometer(UV-vis),and X-ray photoelectron spectrometer(XPS).Their photothermal effects and ice crystal inhibition properties were tested.Furthermore,the nanosheets were successfully applied in the cryogenic freezing and recovery of Hela and A549 cells.The main research work and conclusions are as follows:(1)Graphene oxide nanosheets exhibit remarkable ice crystal inhibition properties,as well as effective light absorption and heat conversion capabilities.These characteristics make them highly suitable as cryoprotectants,as they can minimize cell damage and enhance cell viability during cryopreservation.The synthesis of graphene oxide powder involved the utilization of the Hummers method,while the production of graphene oxide nanosheets with different sizes was achieved through an ultrasonic process(2)Graphene oxide was characterized using an ultraviolet-visible-near-infrared spectrophotometer.The study focused on investigating the photothermal conversion effect of graphene oxide nanosheets with varying sizes.Specifically,the photothermal conversion efficiency of GO-90 was calculated to be 43.5% under 808 nm laser irradiation,indicating a significant photothermal conversion effect(3)The study aimed to characterize the size of ice crystals formed during the freezerewarming process in the presence of graphene oxide nanosheets.The results demonstrated a substantial ice crystal inhibition effect of the graphene oxide nanosheets,with GO-90 reducing the average maximum grain size of ice crystal recrystallization by17%.(4)GO-90,which exhibited a notable ice crystal inhibition effect,was utilized in the cryopreservation and recovery of Hela and A549 cells.The results showed a high cell survival rate after water bath heating and 808 nm laser resuscitation.These findings not only provided an experimental foundation but also served as a theoretical reference for the study of biomimetic antifreeze materials.