Nanochitin and Nanochitosan: Chitin Nanostructure Engineering with Multiscale Properties for Biomedical and Environmental Applications

Abstract

Nanochitin and nanochitosan (with random‐copolymer‐based multiscale architectures of glucosamine and N‐acetylglucosamine units) have recently attracted immense attention for the development of green, sustainable, and advanced functional materials. Nanochitin and nanochitosan are multiscale materials from small oligomers, rod‐shaped nanocrystals, longer nanofibers, to hierarchical assemblies of nanofibers. Various physical properties of chitin and chitosan depend on their molecular‐ and nanostructures; translational research has utilized them for a wide range of applications (biomedical, industrial, environmental, and so on). Instead of reviewing the entire extensive literature on chitin and chitosan, here, recent developments in multiscale‐dependent material properties and their applications are highlighted; immune, medical, reinforcing, adhesive, green electrochemical materials, biological scaffolds, and sustainable food packaging are discussed considering the size, shape, and assembly of chitin nanostructures. In summary, new perspectives for the development of sustainable advanced functional materials based on nanochitin and nanochitosan by understanding and engineering their multiscale properties are described.

Biobased Nanomaterials─The Role of Interfacial Interactions for Advanced Materials

“…In the transition from fossil-based resources to renewables, biobased nanomaterials are pursued as one of the most promising alternatives to address these challenges. Cellulose nanomaterials (CNMs) are by far the most researched plant-based nanomaterial, − followed by lignin nanoparticles (LNPs). , Other renewable nanomaterials include chitin and chitosan, − starch, , and hemicelluloses, − but these have, to date, attracted less attention. Biobased nanomaterials combine the possibilities of nanotechnology with the typical advantages of renewables, like abundance, biodegradability, recyclability, biocompatibility, and low production costs.…”

Mechanism of the Temperature-Dependent Self-Assembly and Polymorphism of Chitin

“…Following cellulose, chitin is the second most abundant naturally occurring polymer on earth. Owing to the biodegradability and high tensile strength, chitin derivatives have been found in diverse applications, such as tissue engineering, drug carriers, cosmetics, wound dressing, and recently pickering emulsion. − However, to make functional materials from chitin, a challenge is to find effective and environmentally friendly ways to dissolve it in solution, , and once dissolved, another challenge is to achieve controlled fabrication. , Thus, a detailed understanding of chitin’s self-assembly mechanism is important.…”

“…Chitin is a homopolymer composed of β-(1–4)-linked N -acetylglucosamine units. Native chitin is a semicrystalline fibril material consisting of crystalline (microfibers) and amorphous regions, where the crystal is composed of a 2–5 nm thick fibril made up of 18–25 chains . Chitin’s crystalline structures have been studied by numerous groups using electron microscopy and X-ray diffraction for over 50 years, which revealed three (α, β, and γ) polymorphic forms depending on the natural sources (Figure a,b). − The most abundant allomorph is α-chitin, which contains antiparallel chains in the crystalline structure and can be found in hard shells of various crustaceans and cell walls of select fungi (Figure a).…”

“…1−6 However, to make functional materials from chitin, a challenge is to find effective and environmentally friendly ways to dissolve it in solution, 7,8 and once dissolved, another challenge is to achieve controlled fabrication. 4,9 Thus, a detailed understanding of chitin's selfassembly mechanism is important.…”

Sustainable, High-Performance, and Biodegradable Plastics Made from Chitin

“…Nevertheless, compared with various renewable resources, chitin has the characteristics of abundant reserves, biodegradability, film-forming properties, nontoxicity, biocompatibility, and biochemical availability. Therefore, chitin is very attractive as a raw material for the preparation of bioplastics. − …”