Recent advances in extraction of chitin and chitosan

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.