Chitin

The high molecular weight of chitin, as a biopolymer, challenges its extraction due to its insolubility in the solvents. Also, chitosan, as the N-deacetylated form of chitin, can be employed as a primary material for different industries. The low mechanical stability and poor plasticity of chitosan films, as a result of incompatible interaction between chitosan and the used solvent, have limited its industrialization. Deep eutectic solvents (DESs), as novel solvents, can solve the extraction difficulties of chitin, and the low mechanical stability and weak plasticity of chitosan films. Also, DESs can be considered for the different chitosan and chitin productions, including chitin nanocrystal and nanofiber, N,N,N-trimethyl-chitosan, chitosan-based imprinted structures, and DES-chitosan-based beads and monoliths. This review aims to focus on the preparation and characterization (chemistry and morphology) of DES-chitin-based and DES-chitosan-based structures to understand the influence of the incorporation of DESs into the chitin and chitosan structure.

Chitosan is a versatile biopolymer due to its biocompatibility, biodegradability, antimicrobial, non-toxic, mucoadhesive, and highly adsorptive properties. Chitosan and its derivatives have been used for many biomedical applications. Currently, crustacean shells and other marine organisms are the significant sources of chitin/chitosan production worldwide. However, extraction from marine sources presents several challenges, including an unstable supply of raw materials. Large-scale chitosan extraction from crustacean sources harms the environment by involving harsh processing steps such as alkali deproteinization. Recently many studies have been carried out focusing on alternative sources or eco-friendlier routes for production of chitosan. This paper briefly overviews recent studies on fungi and insect cuticles as alternative chitosan sources. Milder extraction processes for fungal chitosan and the superior quality of the resultant polymer make it highly desirable for biological applications. Biological techniques involving fermentation and enzymatic processing of the raw materials are looked at in detail. In the concluding remarks, the paper highlights the potential of using a combination of "green" technologies and briefly looks at potential biological/biomedical applications of extracted chitinous materials.

Chitin as one of the fundamental structural biological materials widely occurring in broad diversity of uni- and multicellular organisms focuses attention of experts in biomedicine, materials science, and technology. We are the first to present a patentological overview of chitin as a renewable bioactive material that has stimulated the progress in many fields of applied science worldwide. Such directions as biomedicine, materials science and engineering, chemistry and biochemistry, biotechnology, pharmaceutics, cosmetics, food and feed additives, agriculture as well as environmental science are considered. The overview provides crucial information for progression in modern patentology of chitin and corresponding derivatives. For the first time, we would like to discuss the challenges, solutions, and future directions of chitin related patents for applied materials science.