Ice Recrystallization Inhibition Activity of Protein Mimetic Peptoids

Natural antifreeze proteins are known for their excellent control of ice formation and growth, while synthetic molecules seldom have the similar effects. Here we report a series of protein mimetic peptoids with different side chains exhibiting significant ice recrystallization inhibition activity, and their structure–property relationships are also studied. The presence of peptoid can clearly slow down ice growth and decrease ice crystal grain size, but shows no thermal hysteresis, which make peptoids great antifreeze agent candidates in cryopreservation. Peptoids with methyl, ethyl and amino groups on side chains can modulate ice crystal shape, while peptoids bearing hydroxyl and ethyl groups decrease ice growth rate the most. All peptoids can reduce ice crystal grain size and the one with hydroxyl groups give the smallest grain size. This study reveals peptoid structure effects on ice growth and points to the design rules for biomimetic antifreeze agents.