Preparation Of Superparamagnetic Janus Nanoparticles And Its Preliminary Application In Tumor Chemotherapy-Magnetic Hyperthermia

BackgroundIn order to achieve the goal of high efficiency and non-invasive treatment,the combined therapy of cancer has become a hot research topic nowadays.Nanomaterials are widely used as drug carriers in cancer chemotherapy.Magnetic nanoparticles can not only solve the problem of poor hydrophilicity and instability of chemotherapy drugs,but also act as the medium of magnetic hyperthermia,thus realizing the combined therapy of chemotherapy and magnetic hyperthermia.Accordingly,based on magnetic materials,superparamagnetic amphiphilic Janus nanoparticles(J-NP)were designed and synthesized and used as drug carriers.The nanoparticles can be magnetically targeted to the tumor site.Under the action of alternating magnetic field(AMF),they can raise the temperature of the tumor tissue to 42?and promote drug release,leading to apoptosis and necrosis of the tumor cells,so as to achieve efficient and non-invasive combined therapy.Objective1.Design and synthesize superparamagnetic Janus nanoparticles and characterize their structure and properties.2.To explore the feasibility of Janus nanoparticles as an anti-cancer drug carrier,and to study the magnetocaloric properties of drug-loaded nanoparticles(J-NP/DOX)in alternating magnetic fields.3.To investigate the therapeutic effect of drug-loaded nanoparticles as a magnetic hyperthermia medium in combination with chemotherapy and hyperthermia for mouse breast cancer animal model.Methods1.Preparation and characterization of Janus nanoparticles.Carboxylated polymer brush PMMA was synthesized by atom transfer radical polymerization(ARGET-ATRP)using electron transfer activation regeneration catalyst and emulsified into spheres by solvent evaporation.Paramagnetic Fe₃O₄ nanoparticles were super-prepared by coprecipitation and deposited on the surface of PMMA microspheres in situ by ligand exchange reaction.ARGET-ATRP initiator was introduced by ligand exchange reaction again,and then in good environment.PMMA/Fe₃O₄/PAA magnetic composite microspheres were prepared by grafting polymer brush polyacrylic acid(PAA)in aqueous solution,and J-NP was obtained by etching with organic solvents,and their structures and properties were characterized.2.Evaluation of cytocompatibility.Mouse breast cancer cells(4T1)and mouse fibroblasts(NIH 3T3)were selected for MTT assay.The biocompatibility of Janus nanoparticles was evaluated.Then J-NP/DOX was prepared by self-assembly method and the drug loading and entrapment efficiency were calculated.Then the effects of free drugs DOX and J-NP/DOX on cell viability were evaluated by MTT assay.3.Magnetic properties of J-NP/DOX.Janus nanoparticles with different concentrations were placed in an alternating magnetic field(frequency 445 k Hz,current35.0 A),temperature changes were recorded by infrared camera,and their magnetocaloric properties were evaluated.Magnetic resonance imaging(MRI)was used to evaluate the ability of Janus nanoparticles as T₂ contrast agent.4T1 cells co-incubated with drug-loaded nanoparticles were placed in an alternating magnetic field for in vitro chemotherapy.To study the therapeutic effect of magnetic hyperthermia,a mouse model of subcutaneous tumors was constructed using 4T1 cell line.J-NP/DOX was guided to the tumor site by adding a constant magnetic field,and the therapeutic effect of chemotherapy combined with magnetic hyperthermia in vivo was studied.Results1.The structure,morphology and performance characterization analysis showed that:through characterization and analysis,we have successfully prepared Janus nanoparticles with uniform size and particle size of about 20 nm,high magnetic content(76.8%)and saturation magnetization(42.7 emu/g),coincidence of hysteresis loops,almost no remanence,and good superparamagnetism.2.Cell compatibility of materials.MTT assay showed that the survival rate of 4T1cells was higher than 85%after incubation with 0-800?g/m L of blank nanoparticles for 24h and 48 h,which indicated that Janus nanoparticles had good biocompatibility.Moreover,Janus nanoparticles had higher drug loading(8.95±0.26)%and entrapment efficiency(89.75±2.35)%.After incubation of free DOX and J-NP/DOX with 4T1 cells for 24 h or 48h respectively,J-NP/DOX had higher lethal rate.3.Study on magnetic properties.With the prolongation of J-NP/DOX in alternating magnetic field,the temperature of J-NP/DOX increases gradually,and the higher the concentration of Janus nanoparticles,the faster the temperature rises.After repeated heating of J-NP/DOX,the temperature can still reach the tumor hyperthermia temperature(42-46?).The results of MRI showed that Janus nanoparticles were a good contrast agent for T₂,which could enhance the contrast of the lesions.In vitro cell experiment of chemotherapy combined with magnetic hyperthermia showed that J-NP/DOX had higher cell lethality under alternating magnetic field than chemotherapy and hyperthermia alone.In vivo magnetic hyperthermia experiments showed that J-NP/DOX could be magnetic targeted to the tumor site,and chemotherapy combined with hyperthermia group significantly inhibited the growth of tumors.ConclusionIn this study,Janus nanoparticles were designed and synthesized,which were easy to operate,uniform in size,good in globularity and stability.Janus nanoparticles exhibit good cell compatibility and high drug loading in vitro,with high magnetic saturation and stable magnetothermal properties,and can be used in the dual therapy of cancer cell chemotherapy and magnetothermal therapy.