**1. Introduction**

Chitin is the most abundant polysaccharide in nature after cellulose and is commercially produced from the waste shells of lobster, shrimp, crabs, etc. obtained. Chitosan is obtained by removing the acetyl group of chitin from the structure in a basic medium. Chitosan is a copolymer formed by connecting N-acetyl-D-glucose amine and D-glucose amine with β-1,4 glycosides bonds (**Figure 1**). Since chitosan contains free amino groups, it is a neutral polysaccharide at neutral and basic pH and is insoluble in water. However, at acidic pH, amino groups are soluble because they are protonated. Its solubility depends on the distribution of free amino and N-acetyl groups and is readily soluble in dilute 1–3% acetic acid [1]. Chitosan does not cause allergic reactions and is biocompatible with living tissues. Amino sugars are gradually broken down into harmless products in the body and are completely absorbed by the human body, and they can be easily removed from the organism without causing local side effects in the body [2]. Chitosan is a bioactive ingredient with numerous properties such as antitumor, immune enhancer, antifungal, antimicrobial, antioxidant, and

**Figure 1.** *Chemical structure of chitosan.*

wound healing. In addition to these features, it also has features such as being biodegradable, biocompatible, low cost, and non-antigenic [3].

Chitosan also has good adhesion and coagulation properties. The presence of primary amine groups and primary and secondary hydroxyl groups in chitosan makes it very useful in biological applications. Compared to other biopolymers, chitosan is positively charged and has a structure that can adhere to the mucosa [4]. Chitosan is widely used in many industrial applications due to the following properties [1, 5].

