- Chitosan is a naturally derived polysaccharide obtained by the partial deacetylation of chitin, which is one of the most abundant biopolymers in nature and a major structural component of the exoskeletons of crustaceans, insects, and the cell walls of fungi.
- Chemically, chitosan is composed of β-(1→4)-linked D-glucosamine and N-acetyl-D-glucosamine units, with its physicochemical properties depending on the degree of deacetylation (DD) and molecular weight. Unlike most natural polysaccharides, chitosan carries a positive charge under acidic conditions due to the protonation of amino groups, which confers it with unique solubility, bioadhesion, and antimicrobial properties. This cationic character makes chitosan highly versatile for applications in biomedicine, food technology, agriculture, and environmental science.
- In the biomedical field, chitosan has been extensively studied for its biocompatibility, biodegradability, and non-toxicity, which make it an attractive material for therapeutic use. It is widely used in drug delivery systems, where it can form nanoparticles, hydrogels, or films that encapsulate and release drugs in a controlled manner. Its mucoadhesive nature enhances drug absorption through mucosal surfaces such as nasal, ocular, and gastrointestinal tissues. Chitosan and its derivatives have also been explored in gene delivery, as their positive charges allow them to form complexes with negatively charged DNA or RNA molecules, protecting genetic material and facilitating cellular uptake. In addition, chitosan is a promising material for wound healing due to its antimicrobial activity, hemostatic effect (promoting blood clotting), and ability to accelerate tissue regeneration.
- In the food industry, chitosan serves as a natural preservative, stabilizer, and dietary fiber. Its antimicrobial and antifungal properties help extend the shelf life of fruits, vegetables, and perishable foods by preventing microbial contamination and delaying spoilage. Chitosan-based edible films and coatings are widely used to improve food safety and quality while being biodegradable and environmentally friendly. As a dietary supplement, chitosan is marketed for its cholesterol-lowering and fat-binding properties, though its clinical effectiveness remains debated.
- In agriculture, chitosan functions as a biostimulant and plant protector. It enhances plant growth, boosts resistance to pathogens, and induces defense responses by activating plant immune systems. It is also used as a coating for seeds and fertilizers to improve germination rates and nutrient release. In environmental science, chitosan is recognized as an efficient biosorbent for removing heavy metals, dyes, and other pollutants from wastewater, thanks to its abundance of reactive amino and hydroxyl groups that bind contaminants.
- Chitosan also has growing applications in cosmetics and personal care products. It is incorporated into hair care formulations for film-forming and conditioning effects, into skincare products for its moisturizing and antimicrobial properties, and into oral care products for its role in reducing dental plaque and bacterial growth.
- From a scientific perspective, chitosan is a model functional biopolymer, as its properties can be tailored by modifying its degree of deacetylation, molecular weight, or by introducing chemical modifications (e.g., quaternized, carboxymethylated, or grafted chitosan derivatives). These modifications broaden its solubility profile and enhance specific biological activities, making chitosan a platform for advanced material design.
