Synergistic Promotion of Partial Vitrification and Ice Inhibition in Low-Concentration Cryoprotectant Solutions Using Graphene Quantum Dots and Poly(vinyl alcohol)

Vitrification is the direct conversion of free water from a liquid phase to a glassy solid phase without ice formation and is a widely used method for cryopreservation. However, high concentrations of penetrating cryoprotectants are usually required to achieve vitrification, which causes osmotic stress and toxic effects on cell organelles and membranes. Therefore, low-concentration penetrating cryoprotectants are crucial for vitrification and are urgently required. Herein, we developed a new low-concentration cryoprotectant solution for vitrification, containing ethylene glycol (EG), trehalose, and antifreeze protein mimetics (graphene quantum dots (GQDs) and poly(vinyl alcohol) (PVA)). The results showed that adding 1 mg/mL GQDs and 1% w/v PVA to a low-concentration 10% v/v EG-1 M trehalose solution can effectively promote partial vitrification and influence the phase change behaviors. Especially, a reduction of 25.8% in the melting enthalpy of the 10% v/v EG-1 M trehalose was achieved with 1 mg/mL of GQDs addition. Moreover, GQDs and PVA effectively suppressed the growth of ice crystals in low-concentration EG-trehalose solutions, while PVA exhibited superior inhibition compared to GQDs. In conclusion, we systematically explored the mechanism of the synergistic effect between nanomaterials (GQDs) and polymers (PVA) on low-concentration cryoprotectant solutions and provided experimental support for the development of a new type of cryoprotectant solution with low concentration and high efficiency.