Radiotherapy Based On Tumor Targeting Magnetic Nanoparticles Synthesis And Modification

Magnetic polymer nanospheres are new polymer materials with surface functionality and magnetic responsiveness,which offer great potential applications in a variety of biomedical fields,such as cell separation,immobilized enzyme,and as magnetic field-guided carriers for localizing drugs,thermal therapies and radioactive therapies.Magnetic nanospheres with high magnetic content,well-dispersed,functional groups are mainly studied in this paper.(1) The Fe₃O₄ nanoparticles were successfully prepared by co-precipitation in the presence of oleic acid/undecylenic acid.According to the test results,the magnetic nanoparticles can be dispersed stably in octane with uniform particle size(8 nm),high magnetic content(85.9%) and saturation magnetization value(42.5 emu/g).(2) Unfunctional Fe₃O₄/P(St) magnetic microspheres were obtained by miniemulsion polymerization.The results showed that the microspheres were well-dispersed, well-encapsulated and the magnetic content and the saturation magnetization value reached 35.1%,29.5 emu/g respectively,which provided a good way for systhesising functional magnetic nanospheres.(3) We developed two alternative approaches to synthesize carboxylated magnetic nanospheres.For one thing,the surface carboxyl groups were introduced directly by the carboxylated initiator(4,4'-azobis(4-cyanopentanoic acid),ACPA) during a miniemulsion polymerization.For another thing,the indirect-carboxylated Fe₃O₄/P(St/MMA) magnetic nanospheres can be obtained by co-miniemulsion polymerization with functional monomer (methyl methacrylate,MMA) and main monomer(styrene,St).We discussed the effects of factors,such as ferrofluids with various concentration,DVB with various content,various MMA to SDBS,KPS with various content on the properties of magnetic nanospheres, including diameter,morphologies,magnetic content and encapsulation.The results indicated that it failed to synthesize direct-carboxylated magnetic nanospheres,while the indirect-carboxylated magnetic nanospheres were successfully prepared.Under the optimal condition,we esterified the magnetic nanospheres,namely the carboxyl groups were introduced indirectly on the surface of nanosphere.Moreover,the mangnetic nanospheres had properties with good dispersion and encapsulation,nano-diameter(50nm),high magnetic content(60.9%) and saturation magnetization value(50 emu/g).(4) The indirect-amino Fe₃O₄/P(St/AM) magnetic nanospheres can be obtained by co-miniemulsion polymerization with functional monomer(acrylamide,AM) and main monomer(styrene,St).The results indicated that the indirect-amino magnetic nanospheres were successfully prepared.We found that the factors,such as ferrofluids with various concentration,DVB with various content,various AM to SDBS,KPS with various content had great effects on the properties of magnetic nanospheres,including diameter,morphologies, magnetic content and encapsulation.Under the optimal condition,we amidated the magnetic nanospheres,namely the amide groups were introduced indirectly on the surface of nanosphere.Moreover,the mangnetic nanospheres had properties with good dispersion and encapsulation,nano-diameter(60 nm),magnetic content(36.8%) and saturation magnetization value(27 emu/g).