抗冻水凝胶可以在零下温度环境中调节内部水分子的冻结行为，从而保持其优异特性（如智能响应性和液体运输）以及拓展其在寒冷条件下的应用。本文开发了一系列具有聚集诱导发光（AIE）活性的抗冻水凝胶，可实现在零下温度的信息加密和解密。通过改变水凝胶内的甜菜碱含量，该水凝胶可呈现出不同的冻结温度（T_f）。当温度高于/低于T_f时，编码于水凝胶内的AIE荧光分子不发射/发射荧光，从而可以实现信息的加密和解密。此外，通过调控水凝胶的冻结程序或者在水凝胶内原位引入具有光热效应的硫化铜纳米颗粒并结合特定的照射条件，可以实现信息的多级加密和解密，从而增强信息的安全性。最后，由于解密的信息图案对温度波动具有不可逆性，因此该具有AIE活性的抗冻水凝胶可作为无需外界供能的防伪标签，用于实时和可视化监测冷冻运输（−80 ℃）过程中生物样本（如间充质干细胞和红细胞）的活性。

Freeze-tolerant hydrogels can regulate the freezing behavior of the water inside them at subzero temperatures, thus maintaining their exceptional properties (e.g., intelligent responsiveness and liquid transporting) and extending their applications under cold conditions. Herein, a series of aggregation-induced emission (AIE)-active freeze-tolerant hydrogels are developed, which enable information encryption and decryption at subzero temperatures. The hydrogels possess varied freezing temperatures (T_f) depending on their betaine concentration. Above/below T_f, the information in the hydrogels that is encoded by means of AIE luminogens presents turn-off/-on fluorescence, thereby enabling the use of these hydrogels for information encryption and decryption. Moreover, by tuning the cooling procedures or introducing photothermal copper sulfide nanoparticles into the hydrogels via an in situ sulfidation process, together with certain irradiation conditions, multistage information readouts can be obtained, significantly enhancing the information security. Finally, because the decrypted information in the hydrogels is irreversibly sensitive to temperature fluctuation, external energy-free cryogenic anticounterfeiting labels built with the hydrogels are demonstrated, which can realize the visual and real-time viability monitoring of cryopreserved biosamples (e.g., mesenchymal stem cells and red blood cells) during cold-chain transportation (–80 °C).