Preparation And Characterization Of A Novel Amphiphilic Chitosan Derivative

Polymer micelle is a novel drug delivery system, formed from amphiphilic polymer by self-assembling. Polymer micelle has unique characteristics such as core-shell structure and nanosize, making it a good drug carrier for water-insoluble drugs and passive and active targeting of drug and accumulation in tumor tissues (EPR). Chitosan is a kind of good biocompatible and biodegradable polysaccharide, which has abundant -OH,-NH2, making it possible for grafting other groups. In this thesis, a series of chitosan derivatives including N-mPEG-N-acyl chitosan and N-acyl chitosan were synthized by using mPEG as hydrophilic group, lauric acid and sebacic acid as hydrophobic groups. Chitosan derivatives were characterized by FT-IR,1H-NMR,X-RAD. The degree of substitution (DS) was calculated by elemental analysis (EA). The dissolubility of chitosan derivatives was investigated. The results were showed that N-mPEG-N-acyl chitosan had good solubility both in water and organic solvents, but N-acyl chitosan could be dissolved in water only and could not be dissolved in organic solvents.As amphiphilic polymer has the ability to form micelles by self-assembling, in this thesis, chitosan derivatives were dissolved in double-distilled water to form micelles. The morphology of polymer micelles was measured by transmission electron microscopy (TEM), and the size and distribution of polymer micelles was determined by dynamic light scattering (DLS). The critical micelle concentration (CMC) was detected by a fluorescence technique using pyrene as a probe. It was found that the CMC was decreased by increasing the DS of acyl group, meanwhile the size of polymer micelles was decreased.