Self-aggregated Nanoparticles From Monomethoxy Poly(Ethylene-glycol)-grafted-chitosan: Preparation, Characterization And Its Primary Use As Drug Carrier

This dissertation designed a series of methoxy poly(ethylene glycol) modified chitosan derivatives that have unique chemical structures to prepare self-aggregated nanoparticles. The self-aggregation mechanism was primarily deduced. The self-aggregated nanoparticle system that had good morphology were chosen to be used as carriers of model drug to asses their potential use as drug delivery systems. The main investigations of this dissertation are shown as follows.The methoxy poly(ethylene glycol) modified chitosan derivatives were synthesized by formaldehyde linking method from chitosan and methoxy poly(ethylene glycol) and characterized by Fourier transform infrared spectroscopy(FT-IR) and proton nuclear magnetic resonance (~1H-NMR).The methoxy poly(ethylene glycol) modified chitosan self-aggregated nanoparticles were prepared by dialysis method. The morphology and size of nanoparticles were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic laser light scattering (DLLS).These chitosan derivatives were amphiphilic in nature and their self-aggregation behavior in aqueous media was evaluated by the fluorescence probe technique. The self-aggregated nanoparticles were formed when the material concentration is above the critical aggregation concentration. The morphology of the self-aggregated nanoparticles with degree of substitute about 19% is better. The self-aggregated nanoparticles had a roughly spherical shape and a core-shell structure. The chains from methoxy poly(ethylene glycol) are hydrophilic. They are the outer parts of core-shell structure. And also, the core is formed by winding of the chitosan main chains.The methotrexate loaded self-aggregated nanoparticles were prepared by dialysis method. The drug-loading content and loading efficiency were determined by ultro violet spectrum. Drug release behavior was studied in the pH 7.4 phosphate buffered saline. The drug loaded self-aggregated nanoparticles delayed the drug release.