Ultrasonication of chitosan nanoparticle suspension: Influence on particle size

Chitosan nanoparticles have been prepared using an ionic gelation method. The effects of freeze-drying, cryoprotectant (D-trehalose) utilisation and ultrasonication time on the mean particle size, size distribution and stability of nanoparticles were investigated. The size distribution results indicated that freeze-drying caused the particles to agglomerate. Addition of the cryoprotectant and ultrasonication led to a decrease in the particle size. However the sizes of the nanoparticles increased with increasing ultrasonication time. Transmission electron microscopy images revealed that spherical chitosan nanoparticles ranging from 3 to 12 nm were obtained by means of freeze-drying in the presence of cryoprotectant and ultrasonication. These results suggest that cryoprotectant utilisation and controlled ultrasonic treatment are effective for imparting nanoparticle stability. (C) 2014 Elsevier B.V. All rights reserved.