Preparation of chitosan nanoparticles
Chitosan was dissolved in a dilute aqueous acetic acid solution of 0.5% (w/v) under microwave irradiation. Aqueous ammonia was then dropped into the chitosan solution to precipitate the chitosan. The obtained gel-like swollen chitosan was washed to neutral with DI water, and was then transferred into a 25 ml volumetric flask. The total volume of liquid was added to 25 ml with DI water. An ultrasound processor with a 6 mm probe was used and it was put into the volumetric flask. Ultrasound treatment was conducted under an ice-water bath. Finally, a milky nano-emulsion chitosan was obtained.