Preparation Of Chitosan-based Targeting Carriers And Their Conjugates With Antitumor Drugs

This dissertation was mainly to explore the methods of coupling the antitumor drugs to chitosan by the covalent bonds, and provide references for the study of targeting, sustained and controlled release delivery systems of antitumor drugs.In order to explore the relationship between Molecular Weight of N-Succinyl-Chitosan and effect about targeting tumor site in vitro, a serial of chitosan with different molecular weight were prepared by depolymerization with hydroperoxide in this dissertation, and used to synthesize N-Succinyl-Chitosan (SUC-CS) which labeled with FITC. Incubated FITC-SUC-CS with K562 leukemia cells, and determined flourence intensity of cells by flow cytometry to assess the affinity of N-Succinyl-Chitosan for K562 leukemia cell. The results indicated that N-Succinyl-Chitosan demonstrated high affinity for K562 leukemia cell declining with the increasing of MW of chitosan.Because galactose could specifically bind asialoglycoprotein receptor (ASGPR) on the surface of hepatocyte, this dissertation prepared N-Lactosyl-Chitosan using lactcbionic acid and chitosan under the catalysis of l-[(3-Dimethylamino)propyl]-3-ethylcarbodiimide methiodide (EDCI). In the radioactive experiment in vitro, NGA was prepared and then labeled with ¹²⁵I. N-Lactosyl-Chitosan could competitively bind ASGPR with ¹²⁵I NGA. Thus, the measurement of radioactive intensity could be used to determine the binding capacity of N-Lactosyl-Chitosan to ASGPR. The results indicated that N-Lactosyl-Chitosan was a good ligand for ASGPR, and could be used as hepatic targeting carrier of antitumor drugs.Two targeting antitumor drugs were prepared in this dissertation as follows: firstly coupled MTX with Chitosan under the catalysis of EDCI, then treated with succinic anhydride and lactcbionic acid respectively to synthesize MTX-Succinyl-Chitosan and MTX-Lactosyl-Chitosan conjugates. And their structures were confirmed by UV, IR,¹H-NMR and ¹³C-NMR. These two conjugates were easy soluble in water (pH=l¹4). The dynamic dialysis study showed MTX-Succinyl-Chitosan was stable, and could slowly release MTX. MTT assay showed MTX-Succinyl-Chitosan could efficiently inhibit the growth of K562 tumor cells.Some antitumor drugs such as Taxol were lipid soluble, so it was very difficult to directly couple them to chitosan. This dissertation also prepared lipid-soluble chitosan derivative-6-O-(Triphenylmethyl)-Chitosan, then coupled with Hydrocortisone Succinate to prepare N-Hydrocortisone succinyl-Chitosan under the catalysis of EDCI and in DMF, and its structure was confirmed by UV and IR. Although Hydrocortisone was steriod anti-inflammatory drug, its structure and some physicochemical properties were similar to some antitumor drugs, therefore selected as lipid-soluble drug to explore an effective route to prepare drug-chitosan conjugates.