4.4 Radiation Degradation of Chitosan and Its Application in Aquiculture and Plant

摘要

Chitosan is an amino-polysaccharide derived from chitin by deacetylation. It is one of the most abundant resources in nature. Due to the poor microbial property and low bioactivity of high molecular weight chitosan, it's essential to decrease its molecular weight. Chitosan with low molecular weight is preferred for its extraordinary characteristics such as improving antivirus property of plant and animal, accelerating plant growth, etc. Therefore it may be a substitute for pesticide or antibiotic in the fields of aquiculture and crops in China. Antibiotic is an exceptive type of reagent because of its drug tolerance, which will increase drug dose and reduce drug effect. As a result, antibiotic may make the disease difficult to restrain and augment economic expenses. Chitosan can be degraded by three methods, i.e. chemical hydrolysis or oxidation, enzymatic catalysis, and radiation. The application of radiation to prepare low-molecular-weight chitosan has some advantages over other methods. For example, the depolymerization of chitosan can be carried out in the solid state without destroying the structure of amino group on the molecular chain. Moreover, it is easy to control the molecular weight by simply controlling the radiation dose.