Near-Infrared Mediated Modulation Of Ice Crystallization By Two-Dimensional Nanosheets And Its Application In Cell Vitrification

Two-dimensional(2D)graphene oxide(GO)and molybdenum disulfide(MoS2)nanosheets(NSs)have been widely used as photothermal agents as potential carriers for anti-tumor drugs.Both NSs have also significantly transformed the research of nanotechnology,and sufficiently improve the many application of theranostic,energy conversion and applications.Their spatial thermal effects have been extensively explored for use at physiological and hyperthermic temperatures(37 to 46 ?).However,modulation of the spatial thermal distributions with these NSs may have even more profound applications in micro structural control of biomaterials at cryogenic temperatures(-196 to 37 ?).These applications include bioinspired micro fabrication via freezing,food and drug freeze-drying,and biomaterial cryopreservation.Such thermal effect of the NSs and their applications at cryogenic temperatures have never been fully explored.In this study,we have utilized the near-infrared laser-induced photothermal impact of GO and MoS2 NSs to suppress the ice nucleation and ice crystal growth during the warming of the cell specimen.With this approach,the biological cells subjected to fast cooling to deep frozen state(-196 ?)were successfully recovered with high survival rates and full biological functions.The application of NSs photothermal effect has never been explored in the field of cryopreservation for achieving fast enough risen temperature for reducing recrystallization during a rewarming process.To overcome cryopreservation-recrystallization,we purpose to utilize the photothermal effect of NSs.In this study,NSs of GO and MoS2 were synthesized via a chemical route hummer's method and a facile hydrothermal method respectively.We successfully utilized the photothermal effect of GO and MoS2 for rewarming cryopreserved-human umbilical vein endothelial cells(HUVECs).Intended for near-infrared laser curvature,we developed home build stand structure to absorb the pulse energy in the suspension utterly.To offer a more inclusive assessment of cooling and rewarming responses of the cell suspension,we used the finite element method to investigate the heat transfer of the cell sample inside the plastic straw(PS)during the laser irradiation on the water bath.Our experimental and simulation results show that extracellular NS of GO and MoS2 may significantly improve the freezing rate of cells and efficiently decrease the devitrification and recrystallization during the rewarming process.Moreover,we optimized the concentration of both NSs and the amount of pulse energy laser for maintaining maximum cell viability.Our outcomes indicated that the photothermal effect of 808 nm laser with 0.03%and 0.06%(w/v)of GO and MoS2 respectively,enhanced the vitrification cryopreservation recovery of HUVECs.The GO and MoS2 NS application for achieving the spatial and homogeneous temperature as a photothermal agent is promising strategy for improving the cryopreservation of many cell lines.Thus,we provide NSs based useful approach for control the crystallization behaviors of the vitrified specimen during warming at cryogenic temperatures,as may have broad applications in both materials science and bioengineering.