Chitin nanofibers: preparations, modifications, and applications

Abstract

Chitin nanofibers are prepared from the exoskeletons of crabs and prawns by a simple mechanical treatment after the removal of proteins and minerals. The obtained nanofibers have fine nanofiber networks with a uniform width of approximately 10-20 nm and a high aspect ratio. The method used for chitin-nanofiber isolation is also successfully applied to the cell walls of mushrooms. They form a complex with glucans on the fiber surface. A grinder, a Star Burst atomization system, and a high speed blender are all used in the mechanical treatment to convert chitin to nanofibers. Mechanical treatment under acidic conditions is the key to facilitate fibrillation. At pH 3-4, the cationization of amino groups on the fiber surface assists nano-fibrillation by electrostatic repulsive force. By applying this finding, we also prepared chitin nanofibers from dry chitin powder. Chitin nanofibers are acetylated to modify their surfaces. The acetyl DS can be controlled from 1 to 3 by changing the reaction time. An acetyl group is introduced heterogeneously from the surface to the core. Nanofiber morphology is maintained even in the case of high acetyl DS. Optically transparent chitin nanofiber composites are prepared with 11 different types of acrylic resins. Due to the nano-sized structure, all of the composites are highly transparent. Chitin nanofibers significantly increase the Young's moduli and the tensile strengths and decrease the thermal expansion of all acrylic resins due to the reinforcement effect of chitin nanofibers. Chitin nanofibers show chiral separation ability. The chitin nanofiber membrane transports the d-isomer of glutamic acid, phenylalanine, and lysine from the corresponding racemic amino acid mixtures faster than the corresponding l-isomer. The chitin nanofibers improve clinical symptoms and suppress ulcerative colitis in a DSS-induced mouse model of acute ulcerative colitis. Moreover, chitin nanofibers suppress myeloperoxidase activation in the colon and decrease serum interleukin-6 concentrations.

Chitin Nanofiber Transparent Paper for Flexible Green Electronics

“…For example, Ifuku et al reported a composite-type ChNF transparent paper fabricated by filtering a ChNF/water slurry obtained using a high-speed mechanical grinder. [36,37] Such a top-down approach is often combined with specific chemical treatments, such as TEMPO-mediated oxidation, to promote the individualization of ChNF. [38,39] Meanwhile, in a bottomup route, Zhang and co-workers recently demonstrated a pure chitin transparent paper fabricated by coagulating ChNF (regeneration) from a chitin solution dissolved in NaOH/urea/ water; [40] for this type of method nonaqueous solvent systems, such as LiCl/DMAc [41] and CaCl 2 /MeOH [42] are also available.…”

Oral Administration of Surface-Deacetylated Chitin Nanofibers and Chitosan Inhibit 5-Fluorouracil-Induced Intestinal Mucositis in Mice

“…Simple methods for preparing chitin nanofibers have recently been established [10,11,12]. In surface-deacetylated chitin nanofibers (SDACNFs), the nanofiber surface was transformed into chitosan by deacetylation while the core was maintained as a chitin crystal [13].…”

Preparation of transparent self-standing thin films made from acetylated euglenoid β-1,3-glucans

“…The most extensively studied one has been cellulose, the most abundant biomass on the globe (Edgar et al, 2001;Isogai, Saito, & Fukuzumi, 2011;Iwatake, Nogi, & Yano, 2008;Kim, Kim, Kang, Marquez, & Joo, 2006;Teramoto, Yoshioka, Shiraishi, & Nishio, 2002). Chitin and chitosan derived from Crustacea, the second most abundant biomass, have also been well studied (Ifuku et al, 2013;Ifuku & Saimoto, 2012). Their characteristics differ from those of other polysaccharides primarily because of the presence of acetamide and amino groups.…”