The Construction Of Multistage Targeted Fe₃O₄@mSiO₂@liposome Nanocarrier System And Its Chemo-photodynamic Combination Therapy Under The Guidance Of Magnetic Resonance-fluorescence Imaging

Dox is the most effective chemotherapeutic drug in the clinical treatment of cancer.It could cause the severe side effects and induce the multidrug resistance easily due to lack of targeting moieties,resulting in the failure of chemotherapy.Therefore,the development of novel nanodrug formulation highly integrating actively targeted delivery,multimodal combination therapy,and integration of diagnosis and therapy has become an important research direction in the modern tumor therapy.Multimodal imaging-guided multistage targeted synergistic combination therapy possesses many advantages including increased tumoricidal effect,reduced toxicity,and retarded drug resistance.Herein,we have elaborately developed a core-interlayer-shell structure Fe3O4@mSiO2@lipid-PEG-methotrexate nanoparticle(FMLM)to realize photodynamic-chemical combination therapy under the guidance of magnetic resonance-fluorescence imaging.The study was designed that the Fe3O4 core was used for magnet-stimulate-response drug release,magnetic resonance imaging(MRI),and early-phase magnet targeting ability;the mSiO2 layer could encapsulate anticancer drug Doxorubicin(Dox)for chemotherapy;and the protective shell of lipid-PEG and lipid-PEG-methotrexate offered later-phase specific cellular targeting ability,good water dispersibility,and loading of photosensitizer zinc phthalocyanine(ZnPc)for simultaneous near-infrared fluorescence imaging and photodynamic therapy.Based on the above design research,the paper mainly discusses the content of the following aspects:In construction of drug-loading nanoparticles,we surveyed the preparation methods of Fe3O4,FM,FML,and FMLM nanoparticles,respectively.To guarantee the controllable synthesis method,the single factor and orthogonal experiment design were conducted to optimize experiment conditions.Particle size,potential,TEM,SEM,EDS,XRD,N2 adsorption desorption,IR spectra,time of flight mass spectrometry and hysteresis curve etc were used to characterize the Fe3O4,FM,FML,and FMLM nanoparticles.These results demonstrated that the prepared FMLM nanoparticles had a clear core-interlayer-shell structure,the structure was intact,and nearly spherical.The both Dox and ZnPc-loaded FMLM nanoparticles(Dox/ZnPc-FMLM)had a hydrodynamic particle size of 233.60 nm,a zeta potential of-22.60 mV.The drug encapsulation efficacy of ZnPc was 98.80%,drug-loading content of Dox was 0.4959 mg/mg.So the FMLM nanoparticles have the potential to be a good nanoscaled drug carrier.To study the application of FMLM nanoparticles drug delivery system in photodynamic-chemical combination therapy under the guidance of magnetic resonance-fluorescence imaging,we conducted a systematic evaluation of in vivo and in vitro.Experiments had studied the in vitro release curve of Dox-FM and Dox-FMLM,and explore its mechanism of drug release.Meanwhile,under the additional alternating magnetic field(AMF),drug release was increased,indicating the drug release behavior has the characteristics of pH-sensitivity and magnetic responsiveness.We further explored the ability of singlet oxygen generation of drug-loading nanoparticles,the result proved that the ZnPc-nanoparticles have the feasibility of photodynamic therapy;Furthermore,we have carried on the evaluation system of the cells,such as cytotoxicity,cellular uptake,Cell apoptosis,etc.These results confirmed the difference of FMLM nanoparticles caused by MTX cell active targeting cell in cytotoxicity and cellular uptake.Besides,the preliminary mechanism of apoptosis of HeLa was explored.In vivo evaluation of drug-loading nanoparticles were conducted,such as in vivo pharmacokinetic,living fluorescence test,animal toxicity test and tumor inhibition experiment,confirming the superiority of the magnetic targeting and cell active targeting multistage targeted,the safety of drug-loading nanoparticles and the feasibility of chemotherapy-photodynamic collaboration for the treatment of tumor.In vivo experiment,we verified the potential of Dox/ZnPc-FMLM in multimodal imaging.Integrate fluorescence imaging(FI),MRI and photoacoustic imaging(PAI)into Dox/ZnPc-FMLM nanoparticles can make up the shortcomings of individual imaging,foster strengths and circumvent weaknesses,to achieve accurate diagnosis and treatment.These results indicated magnet targeting cooperative with methotrexate macromolecular prodrug targeting is successfully exploited to develop a promising versatile theranostic nanoplatform for dual-modal fluorescence and magnetic resonance imaging-guided combined chemo-photodynamic cancer therapy.