Chitosan Depolymerization and Nanochitosan Production Using a Single Physical Procedure

The many applications of the chitosan biopolymers in the areas of nanotechnology and nanomaterials have led to the need to develop novel techniques suitable for the production of nanochitosan. At present these typically involve the use of chemical agents to form chitosan nanoparticles. Physical, chemical, and enzymatic methods have been described for the depolymerizatiton of chitosan. In this work, evaluation was made of the efficiency of a combination of physical methods, including milling of the raw material and drying of the final chitosan, in order to obtain nanochitosan with low molar mass. The results revealed the effectiveness of the combination of milling the raw material under controlled conditions for 4.5 h and drying of the chitosan by thermal shock, which provided depolymerization of up to 10x and resulted in chitosan with M-v less than 21 kDa and hydrodynamic diameter below 30 nm.