Structural Insights into Ice Recrystallization Activity of Helical Disubstituted Polypeptoids

A major challenge in cryopreservation lies in controlling ice recrystallization during freeze-thaw processes. Here, inspired by natural helical antifreeze (glyco)proteins (AF(G)Ps), helical disubstituted polypeptoids with different hydrophilic groups, hydrophobic segments, and side-chain sequences were efficiently synthesized using ring-opening polymerization and thiol-ene click reactions. Their rigid helical backbones facilitated the exposure of substituents, inducing the segregation of hydrophilic and hydrophobic domains that resemble those in AF(G)Ps. Polypeptoids with increased hydrophobic domains exhibited stronger ice-binding interactions and higher ice recrystallization inhibition (IRI) activity. Preliminary cryopreservation studies showed that the helical disubstituted polypeptoids enhanced post-thaw recovery rates of blood cells compared to the commonly used hydroxyethyl starch (HES). With facile synthesis, helical stability, structural tunability, biocompatibility, and IRI activity, disubstituted polypeptoids represent a promising platform for advanced cryopreservation materials. Moreover, the structural insights into the IRI activity of disubstituted polypeptoids pave the way for the rational design of efficient cryoprotective agents.