From chitosan flakes to chitosan nanospheres: investigation of nanosphere structure and factor related to nanosphere formation and model drug incorporation

Abstract

Development of chitosan as nanomaterial is proposed by modification of functional group on chitosan chain. Grafting phthalic anhydride and α-caboxylpropyl- ω-methoxy polyethylene glycol (mPEG-COOH) on chitosan exhibits spherical form via self-assembly process in aqueous system. The molecular weight of mPEG plays an important role to control the particle size. As compared to mPEG 2000, which gives a bimodal nanosphere (∼200, and ∼300 nm), mPEG 5000 initiates a monodispersed nanosphere with the smaller size (150 nm). In aqueous solution, the nanosphere surface is negatively charged resulting in a well dispersion in neutral to high pH but a significant precipitation in low pH. The studies on model drug (lidocaine, campthotecin, and proteins) incorporation with chitosan nanospheres exhibit efficiency of nanosphere as drug and/or vaccine carrier.