Synthesis And Properties Of Tumor-targeting Polymeric Drug Delivery Systems

Biomaterials are the novel substances contained in therapeutic,diagnostic, or tissue grafting and replacing systems that are in contact withtissue or biological fluids. The polymeric nanoparticles can entrap or attachthe anticancer drugs in order to not only reduce the adverse effects of drugson normal tissues to enhance the selectivity of drugs but also increaseanticancer efficacy. Therefore, the polymeric nanoparticles have been widelyused in medical drug controlled release, immunity analysis, and interventionaldiagnosis, etc..The partly deprotected polycarbonate (P(DTC-co-PTC) containinghydroxyl group was a biodegradable material and was used as the drug carrierin this work. Folic acid (FA) was chosen as a tumor-targeting group. Folicacid-containing polycarbonate was synthesized by the incorporation of folicacid into polycarbonate to make the tumor-targeting polymeric drug carrier.Drug-loaded polymer nano-micelles or nanoparticles were prepared by themethods of dialysis and high-voltage electrostatic field-assisted atomization.The particle size of drug-loaded nanometerials and drug release properties invitro were also studied. Experimental data indicated that5-fluorouracil (5-Fu)from nanometerials showed that these drug-loaded nanometerials had thesteady drug release rates and nice controlled release properties. Moreover,anticancer drug loaded polycarbonate nanoparticles prepared by high-voltageelectrostatic field-assisted atomization possessed the smaller particle size andfaster drug release rates than those of anticancer drug loaded polycarbonatenanoparticles prepared by dialysis method.Magnetic resonance imaging (MRI) is a non-invasive clinical imagingmodality, which has become widely used in the diagnosis of human diseasessuch as tumors around the world. One promising approach for increasing thelocal concentration of paramagnetic conjugates in tumor tissue is to conjugate Gd-DTPA and targeting molecules that have a high affinity to tumor cells withthe water-soluble macromolecules. Sulfadiazine-containing dextrangadolinium complex (SD-Dextran-DTPA-Gd), porphyrin-containing dextrangadolinium complex (APTSPP-Dextran-DTPA-Gd), and folicacid-containing dextran gadolinium complex (FA-Dextran-DTPA-Gd) weresynthesized as the tumor-targeting macromolecular MRI contrast agents. Thecell uptake assay indicated that these contrast agents had a high affinity totumor cells and can be taken up selectively by tumors. In vivo and in vitromagnetic resonance imaging tests showed that these contrast agents possessedthe higher relaxation effectiveness than that of Gd-DTPA and can enhance thecontrast of MR images of the tumors.