Study On The Preparation And Performance Of Magnetic Photothermal Drug Carrier For Diagnosis And Treatment Integration

Cancer reduces the quality of human life and endangers life,which is one of the health problems that has plagued human beings for a long time.Thus,finding a cure for cancer has always been the research hotspot and target of biomedical researchers.Based on the magnetic resonance imaging diagnosis and the new emerged photo-thermal therapy,we prepared magnetic photo-thermal materials as a drug carrier in antineoplastic therapy through the functional design and structure adjustment according to the requirement of unifinication of diagnosis and treatment.As a drug carrier,chemotherapy drug loaded magnetic photo-thermal materials can produce a synergistic effect with both photo-thermal therapy and chemotherapy based on the magnetic resonance imaging function.Thus,composite materials can improve the curative effect with real-time monitoring which offered new ways to treat cancers.In this thesis,we aimed to construct a non-toxic or low-toxic magnetic photothermal dual-functional composite material,remedying the poor photo-thermal performance of single magnetic material and the imaging monitoring deficiency of single photo-thermal material.We further studied the role of the composite materials in cells and model animals,and discussed the drug delivery effect of the composite materials in animals,providing theoretical basis and experimental data for the clinical application of such composite materials.The specific research contents and conclusions are as follows:1.Study on the preparation of Fe3O4@GO@CS magnetic photothermal microsphere via electrostatic droplet method and its stimulus-response drug release properties.In order to get the magnetic photo-thermal microspheres,we selected chitosan with good biocompatibility in this chapter as coating material,incorporating Fe3O4 magnetic nanoparticles and Graphite Oxide(GO)with good photothermal ability.Electrostatic droplet method with high efficiency and reliability was chosen to prepare particle size controllable and monodispersed Fe3O4@GO@CS magnetic photo-thermal microspheres.The particle size of the microspheres could be controlled from 100 to 1100?m with the relative deviation ranged from 0.18%to 5.78%.The effects of chitosan concentration,electric field intensity and pump speed etc.on the synthesis of Fe3O4@GO@CS magnetic microspheres were studied.The particle size increased with the chitosan concentration,pump speed and chitosan molecular weight.The distance between the tip and the receiver,voltage of the direct current field had no significant effect on the particle size.The differences of adsorption and embedding method on drug loading capacity were discussed using doxorubicin hydrochloride(DOX · HCl)as a model drug.The vitro drug release was also studied.The results indicated that the introduction of GO can obviously improve the loading capacity of DOX,and GO could make the surface of the microsphere more compact and dense.The adsorption method had a high encapsulation rate of 80.9%under a low concentration of DOX.The capacity and encapsulation rate of the embedding method were both higher,reaching 186.9mg/g and 71.3%,respectively.The microsphere had good magnetic and pH responsiveness.The saturation magnetization of the microspheres was related to the proportion of Fe3O4nanoparticles.External stimuli such as NIR radiation and ultrasonic could accelerate drug release.2.Study on synthesis,drug loading and controlled release properties of Fe3O4-NH2@MIL101-NH2 magnetic core-shell nanoparticles.In order to improve the drug loading capacity of pure magnetic nanoparticles,Fe3O4-NH2 magnetic nanoparticles with easy surface modification property were selected as the core in this chapter while MIL101-NH2 with high drug loading capacity was chosen as the shell.Microwave method with the characteristics of fast reaction,uniform heating and low energy consumption was chosen to synthesize Fe3O4-NH2@MIL101-NH2 magnetic core-shell nanoparticles in water phase.The effects of molar ratio of reactants,microwave heated time etc.experimental conditions on the morphologies and properties of Fe3O4-NH2@MIL101-NH2 magnetic core-shell nanoparticles were studied.The optimum reaction conditions were determined as follows:microwave heating power 400watt,heating time 5min,molar ratio of Fe3O4-NH2 and BDC-NH2 were 1:1.The physical and chemical properties of Fe3O4-NH2@MIL101-NH2 magnetic nanoparticles were characterized using FT-IR,XRD,BET,SEM,HAADF-STEM and VSM etc.The results revealed that the Fe3O4-NH2@MIL101-NH2 magnetic nanoparticles have a core-shell structure with an average particle size of 268nm,a saturation magnetization of 20.47emu/g,a specific surface area of 96.04m2/g,pore volume of 22.07cm3/g and an average aperture of 6.68nm.The drug loading and control release properties of Fe3O4-NH2@MIL101?NH2 magnetic core-shell nanoparticles were studied using DOX as a model drug.The shell of MIL101-NH2 could significantly improve the drug loading capacity of the nanoparticles,the maximum value of DOX could reach 360.2mg/g.In addition,the shell of MIL101-NH2 had a significant slow release effect on DOX.The release rate of DOX was related to the size of pore and pH value of release medium.DOX released faster in the case of larger pore size and lower pH value.Finally,the cytotoxicity of the nanoparticles was measured by MTT assay.The results showed that the Fe3O4-NH2@MIL101-NH2 magnetic core-shell nanoparticles had a low cytotoxicity,good biocompatibility,which was suitable as a drug carrier for potential drug delivery in vivo.3.Study on synthesis,drug loading and controlled release properties of Fe3O4-NH2@PDA@Au@MIL 101-NH2 core-shell-shell magnetic photo-thermal nanoparticles(MPNPs).In order to improve the photo-thermal property of pure magnetic nanoparticles,we prepared Fe3O4-NH2@PDA@Au@MIL101-NH2 core-shell-shell magnetic photo-thermal nanoparticles using layer-by-layer self-assembly principle based on the Fe3O4-NH2 magnetic nanoparticles in this chapter.Fe3O4-NH2 magnetic nanoparticles were firstly modified with a layer of poly-dopamine(PDA)under weak alkaline conditions.PDA,which had a similar structure of melanoidins,could enhance the photo-thermal property of Fe3O4-NH2@PDA nanoparticles.Au nanocages with excellent photo-thermal property were adhered to the surface of PDA layer,making further enhancement of photo-thermal property.Finally,the microwave method used in previous chapter was employed to modify a layer of MIL 101-NH2 on the surface of Fe3O4-NH2@PDA@Au magnetic core-shell photo-thermal nanoparticles to enhance the drug loading capacity.The effects of reaction time,reaction concentration of Fe3O4-NH2 on the thickness of PDA layer and dispersibility of the nanoparticles were discussed.The adsorption molar ratio of Fe3O4-NH2@PDA and Au nanocage was optimized.The optimal reaction conditions were determined as:DA reaction concentration of lmg/mL,initial Fe3O4-NH2 concentration of 500mg/L,pH8.5,reaction time for 1h,the molar ratio of Fe3O4-NH2@PDA and Au nanocage is 20:1,microwave heating 400Watt for 5min,molar ratio of Fe3O4-NH2@PDA@Au and BDC-NH2 is 1:1.The obtained Fe3O4-NH2@PDA@Au@MIL101-NH2 core-shell-shell MPNPs had good photo-thermal,adsorption properties and magnetic responsiveness with a particle size of 430nm,a saturation magnetization of 19.99emu/g,a specific surface area of 55.34m2/g,pore volume of 12.72cm3/g and average pore diameter of 11.32nm.The photo-thermal and drug loading capacity of the Fe3O4-NH2@PDA@Au@MIL101-NH2 core-shell-shell MPNPs were 3.11 and 5.52 times higher than that of Fe3O4-NH2 magnetic nanoparticles,respectively.Near-infrared radiation(NIR)could regulate and control the release performance of model drug-DOX by means of MPNPs.4.Study on antitumor and magnetic resonance imaging of Fe3O4-NH2@PDA@Au@MIL101-NH2 core-shell-shell MPNPs in vitro and in vivo.In order to study the in vitro and in vivo anti-tumor and magnetic resonance imaging effects of Fe3O4-NH2@PDA@Au@MIL101-NH2 core-shell-shell MPNPs,we used Hela cells,BALB/c nude mice and KM mice as models in this chapter.MTT assay was employed to investigate the cytotoxicity,semi-inhibitory concentration and contribution rate of photo-thermal therapy of Fe3O4-NH2@PDA@Au@MIL101-NH2 core-shell-shell MPNPs.The interaction between MPNPs and Hela cells was observed through a laser confocal microscope.The in vivo anti-tumor effect of MPNPs was studied using the tumor in-situ injection with MPNPs by local photo-thermal therapy with NIR.The result revealed that low concentration of Fe3O4-NH2@PDA@Au@MIL101-NH2 core-shell-shell MPNPs had little toxicity to the Hela cells.Certain toxicity to Hela cells when the concentration of MPNPs was higher than 50mg/L.Due to the slow release function of the coating materials,the semi-inhibitory concentration of the MPNPs was higher than that of DOX,reaching 2?g/mL.DOX loaded MPNPs could use NIR irradiation to realize synergistic effect of photo-thermal therapy and chemo-therapy of DOX,enhancing the killing effect of Hela cells.The survival rate of NIR groups was lower than that of non-NIR groups.MPNPs had good affinity and adhesiveness to Hela cells,but induced a change of cell morphology for longer time exposure.DOX entered the cell via the cytoplasm to the nucleus by diffusion,ultimately inhibiting the proliferation of Hela cells.MPNPs had good photothermal therapy effect in vivo of the tumor mice,and could synergize DOX enhanced the inhibition of the tumor.At the injection dose of 22mg/kg,5w/cm2 power density NIR for 2min,the tumor would be ablated in 10 days.The whole process of photothermal therapy did not produce acute toxicity and allergic reaction to the mice.There was also no damage to the liver and kidney functions of mice.The MPNPs had good magnetic resonance imaging effects in vitro and in vivo,and could be used as a contrast agent for the magnetic resonance imaging in vivo.The relaxation time and concentration of MPNPs were in good linear relationship,and the correlation coefficient R2 reached 0.94.As a drug carrier,MPNPs could synergize photothermal therapy and chemotherapy when using for the diagnosis and treatment of tumors.