What is Chitin?

Chitin is a naturally occurring polysaccharide found in the shells of living organisms such as crabs, lobsters, tortoise, shrimps, and insects or it can be generated via fungal fermentation processes. Chitin is a naturally occurring polymer consisting of 2-acetamido-2- deoxy-D-glucose via a β(1-4) linkage . Three forms of chitin are available, namely α-, β-, and γ-chitin, however, the structure of α-chitin has been investigated more extensively than that of either the β- or γ- form. Very few studies have been carried out on γ-chitin because γ-chitin may be a distorted version of either α- or β-chitin. 

Preparation

A suspension of chitin crystallite particles was first prepared by Marchessault et al. in 1959. In this method, 2.5 N hydrochloric acid solution was used to treat purified chitin under reflux for 1 h. After the reflux, the excess acid was separated by a decantation process and then distilled water was added to obtain the suspension. It was observed from their method that the acid-hydrolyzed chitin spontaneously dispersed into rod-like particles that could be concentrated to a liquid  crystalline phase and self-assembled to a cholesteric liquid crystalline phase above a certain concentration. 

Though chitins are present within numerous taxonomic groups, on the commercial scale they are usually extracted from marine crustaceans, mainly because a large amount of waste is available as a by-product of food processing.  

Application

According to the literature, chitin is mainly applicable in pharmaceutical and biomedical fields. For example, chitin has been receiving great interest in drug delivery, colon or nasal delivery, and gene delivery applications. 

Because of their advantageous properties, such as nontoxicity, biocompatibility, biodegradability, and availability of terminal functional groups, chitin has been widely used for controlled release of drugs in the area of drug delivery systems. 

For various drug release applications, like oral and nasal drug delivery, various types of chitin, such as microparticles, tablets, films, beads, and gels, have been proposed by many researchers.