Inhibiting Ice Recrystallization by Nanocelluloses

Biocompatible materials with ice recrystallization inhibition (IRI) activity have potential applications in several fields. Emerging studies have associated the IRI activity of antifreeze proteins/glycoproteins and several mimics of synthetic materials with a facially amphipathic structure. Nanocelluloses are a new family of renewable materials that demonstrate amphiphilicity. Herein the IRI activity of cellulose nanocrystals (CNCs) and 2,2,6,6-tetramethylpiperidine-1-oxyl oxidized cellulose nanofibrils (TEMPO-CNFs) is reported. In 0.01 M NaCl, ice recrystallization was effectively inhibited by 5.0 mg/mL CNCs or 2.0 mg/mL TEMPO-CNFs. In phosphate-buffered saline, observable IRI activity was found with 30.0 mg/mL CNCs. IRI assays in sucrose solutions showed that the decreased IRI activity of nanocelluloses in saline was caused by the aggregation of nanocelluloses due to charge screening. Neither thermal hysteresis nor dynamic ice shaping activity was observed in nanocelluloses. These findings may lead to the use of nanocelluloses as novel ice recrystallization inhibitors.