Concentration-Dependent Nanosheet and Nanotube Networks: Ice-Water Interface Control for Antifreeze Application

Cyclic peptides (CPs) are versatile building blocks whose conformational constraints foster ordered supramolecular architectures with potential in biomedicine, nanoelectronics, and catalysis. Herein, we report the development of biomimetic antifreeze materials by conjugating CPs bearing ice-binding residues to 4-arm polyethylene glycol (PEG) via click chemistry. The concentration-dependent self-assembly of these CP-PEG conjugates induces programmable morphological transitions, forming nanotube networks above the critical aggregation concentration (CAC) and two-dimensional nanosheet networks near the CAC. Strategic incorporation of ice-binding residues (Threonine, Valine, and Serine) systematically enhanced antifreeze activity, with threonine-functionalized nanotubes exhibiting the most pronounced ice recrystallization inhibition. Overall, nanotube assemblies demonstrated superior antifreeze and ice-nucleation inhibition capabilities, whereas nanosheets provided moderate yet significant cryoprotection. Dynamic ice shaping studies revealed distinct morphology-dependent mechanisms: nanotubes induced faceted ice crystals through specific binding, while nanosheets produced rounded crystals via surface interactions. This study establishes that by coupling rational sequence design with controlled self-assembly, these synthetic CP-PEG conjugates can effectively modulate ice-water interfaces through multiple, distinct mechanisms. This offers a highly tunable and robust platform for developing next-generation cryoprotectants and advanced materials for cold-environment applications, overcoming limitations of antifreeze proteins.