Synergistic Photothermal Ice Inhibition Strategy for Scalable Cryopreservation of Macroscopic Spheroids and Immune Cells in Advanced Immunotherapy

Scalable and effective cryopreservation of human immune cells and biological samples is challenging for advanced cellular therapeutics. However, current cryoprotectants are limited due to trade-offs between robust ice inhibition and uniform thermal management to mitigate Ostwald ripening. Herein, we develop a nonpermeable nanocryoprotectant (PVA@PPy) by combining antifreezing poly(vinyl alcohol) (PVA) with photothermal polypyrrole (PPy). The strong hydration of pendant PVA chains limits ice growth, while the photothermal PPy enables bulky heating to prevent devitrification. A low concentration of 0.05% nanocryoprotectant enables the recovery of 0.5 mm neural spheroids, outperforming traditional cryopreservation methods employing 10% DMSO. We achieve >95% recovery rates across all tested human immune cell populations, including CD4+, CD8+, NK cells, and αβ T cells. This work underscores the unprecedented potential of PVA@PPy for the effective preservation of macroscopic biological samples and immune cells for advanced therapeutics.