Inhibition Effect of TiCT MXene on Ice Crystals Combined with Laser-Mediated Heating Facilitates High-Performance Cryopreservation.

The phenomena of ice formation and growth are of great importance for climate science, regenerative medicine, cryobiology, and food science. Hence, how to control ice formation and growth remains a challenge in these fields and attracts great interest from widespread researchers. Herein, the ice regulation ability of the two-dimensional MXene TiCT in both the cooling and thawing processes is explored. Molecularly speaking, the ice growth inhibition mechanism of TiCT MXene is ascribed to the formation of hydrogen bonds between functional groups of -O-, -OH, and -F distributed on the surface of TiCT and ice/water molecules, which was elucidated by the molecular dynamics simulation method. In the cooling process, TiCT can decrease the supercooling degree and inhibit the sharp edge morphology of ice crystals. Moreover, taking advantage of the outstanding photothermal conversion property of TiCT, rapid ice melting can be achieved, thus reducing the phenomena of devitrification and ice recrystallization. Based on the ice restriction performance of TiCT mentioned above, TiCT is applied for cryopreservation of stem-cell-laden hydrogel constructs. The results show that TiCT can reduce cryodamage to stem cells induced by ice injury in both the cooling and thawing processes and finally increase the cell viability from 38.4% to 80.9%. In addition, TiCT also shows synergetic antibacterial activity under laser irradiation, thus realizing sterile cryopreservation of stem cells. Overall, this work explores the ice inhibition performance of TiCT, elucidates the physical mechanism, and further achieves application of TiCT in the field of cell cryopreservation.