Ice-Water Interfacial SERS/SEIRAS Reveals Novel Antifreeze Peptide Icing Inhibition Dynamics at the Molecular Level.

Abstract

Unravelling ice-water interface water structure evolution is essential for understanding ice growth, but interfacial water is notoriously difficult to probe. We developed a Cryo-Raman/Infrared interaction profiling (CRIP/CIIP) technique to establish molecule-level correlations between ice growth and interfacial water structures. Antifreeze oligopeptides were localized on Au/Ag nanocubes (NCs) through mercaptobenzoic linker/Raman tags. Findings decrypt that the interfacial water structure is directly correlated to the ice recrystallization inhibition (IRI) activity of oligopeptides on NCs. With increasing density of oligopeptides, interfacial water is gradually subjected to a transition from 4-coordinated hydrogen-bonded water (4-HB·H₂O) to 2-HB·H₂O and π-hydrogen bond water (π-HB·H₂O). This study finds π-HB·H₂O acting as a new anti-icing force, with implications for designing IRI-active materials. Our CRIP technique enables the rapid recognition of IRI-active materials through benzene ring conformation allostery on NCs, establishing a general molecular strategy for screening antifreeze materials.