Preparation Of Fe@Fe 3 O 4 @Cu 2-x S Nanoparticles And Their Studies In Photodynamic Therapy Guided By MRI

In photodynamic therapy,the photosensitizer transfers absorbed light energy to the surrounding oxygen molecules,and then produces cytotoxic singlet oxygen?¹O₂?or other reactive oxygen species to kill cancer cells and destroy tumor tissue.Photodynamic therapy for tumor had an obvious advantage of its non-thermal,minimally invasive and non-invasive properties,especially the relatively deep tissue penetration depth in the near-infrared region?NIR-II,1000-1700 nm?.In addition,In addition,magnetic resonance imaging?MRI?had many advantages such as a high spatial resolution,soft tissue contrast,a high resolution of several tens of micrometers.Therefore,this thesis mainly focuses on photodynamic therapy guided by MRI as follows:Firstly,Fe@Fe₃O₄ core-shell nanoparticles were synthesized by the pyrolysis method at a high temperature,then oxidized at the air atmosphere.A nano-shell of Cu_2-xS was successfully coated on the surface of Fe@Fe₃O₄ nanoparticles by the seed method to obtain the novel core-shell nanoparticles of Fe@Fe₃O₄@Cu_2-xS?MNPs?.In order to improve the water solubility and biocompatibility of MNPs,distearyl phosphatidylethanolamine-polyethylene glycol?DSPE-PEG?was coated on the surface of Fe@Fe₃O₄@Cu_2-xS nanoparticles to obtain MNPs-PEG with a small diameter of¹3.6 nm.The solution experiments showed that MNPs-PEG had a good T₂-weighted imaging property and a high saturation magnetization of⁴4.5 mmol^-1s^-1.The good singlet generation property of MNPs-PEG under the 1064 nm laser irradiation?0.1 W/cm²?was determined by the fluorescent method.In the cell therapy experiment,when the incubation concentration increased from 0 to 200?g/mL under the irradiation of 1064 nm,the cell viability decreased from 100%to 67%.With the increase of the concentration,the cell viability gradually decreased,indicating that MNPs-PEG had an obvious therapeutic effect under the irradiation of the 1064 nm laser irradiation?0.1 W/cm²?.In a 4T1 tumor mice model,after 0.5 h intravenous injection of MNPs-PEG?20 mg/kg?,NPs-PEG in tumor reached the maximum enrichment amount compared with the tumor before injection.The relative signal intensity reduced to 42.6%.Under the guidance of MRI,After 30 min intravenous injection with the same dose,the tumor was irradiated with the 1064 nm laser?0.1W/cm²?for 30 min.After the treatment for two weeks,the growth of the tumor in the experimental group was significantly inhibited.The tumor volume was only³7.1%compared to that of the control group.The research in this thesis provides new ideas for the research of inorganic nanoparticles in near-infrared photodynamic therapy.