Spontaneous Formation of a Sustainable Antifreeze Coating by Peptide Self-Assembly

The formation of ice and frost on surfaces poses significant challenges to aviation, crop protection, organ preservation, and other fields. This paper presents the formation of sustainable antifreeze coating by the self-assembly of short peptides. The peptide design is inspired by and combines different elements from distinct natural proteins: (i) a sequence of amino acids from an antifreeze protein and (ii) the amino acids 3,4-dihydroxyphenylalanine (DOPA) and lysine from mussel adhesion proteins that anchor the peptide to a surface. The peptide, termed AFPep1, incorporates the repetitive ice-binding motif found in the antifreeze protein of the longhorn beetle (Rhagium inquisitor). Surfaces coated with the peptide exhibited antifreeze activity with a delay of the initial freezing of 5 °C degrees compared to a bare surface. Furthermore, AFPep1 exhibited relatively effective ice recrystallization inhibition (IRI) activity in solution compared to various other common substances, with an inhibition concentration of 0.5 ± 0.1 mM. Additionally, the presence of AFPep1 in the solution shaped ice crystals into hexagonal plates, indicating specific binding to ice. Moreover, thermal hysteresis results show that AFPep1 completely inhibits ice growth at supercooling levels of up to 0.04 °C at 2 mM, indicating the peptide's ability to self-assemble and create high-density anchoring points on the ice surface. These results highlight the significant potential of specific peptides as antifreeze coatings for technological infrastructure and agricultural applications.