Construction Of PH / Temperature Sensitive Nano Magnetic Fluid And Efficacy Study

Compared with photothermal therapy,which is subject to the penetration ability of light,the advantage of magnetic fluid hyperthermia is that the radiation range of the magnetic field is not limited(the magnetic permeability of the human body is almost equal to the vacuum permeability),so the magnetic fluid hyperthermia can be applied to Hyperthermia on the whole body position.At the same time,this also brings about a new problem,that is,the effect of magnetic fluid depends entirely on the distribution of nano-magnetic fluid in the organism.At present,the particle size of the common nano-magnetic fluid is mainly concentrated in 50 nm～200 nm.After establishing a mouse model,it is generally concentrated in the liver and spleen after being injected through the tail vein,followed by kidneys and tumors.Even if the nano-magnetic fluid is given biological targeting,or magnetic targeting,compared with organs such as liver and spleen,the distribution of nano-magnetic fluid in tumor tissue is relatively small,which causes non-targeted heating of nano-magnetic fluid..In order to solve this problem,it is commonly used to endow nanomagnetic fluid with conditional responsiveness to enhance tumor targeting.However,the micelles relying solely on EPR effect(enhanced permeability and retention effect)are not enough to concentrate on the tumor site.In order to solve the above two problems at the same time,comprehensively improve the targeting of nano-magnetic fluid to tumors,and reduce the loss of magnetic fluid in non-targeted heating and hyperthermia,this paper uses a temperature-sensitive polymer with pH-sensitive properties as polymerization The material carrier,through the self-assembly package of superparamagnetic nanoparticles(SPIOs),uses the magnetocaloric effect to improve the tumor-targeting distribution of nano-magnetic fluids and the curative effect of tumor magneto-hyperthermia.The specific research content is as follows:The characterization of the morphology,particle size,and magnetocaloric properties of the related polymer materials proved that the magnetocaloric pH/temperature multiple sensitive composite micelles have excellent capacity to load magnetic nanoparticles,and have good saturation magnetization and magnetocaloric properties.Experiments such as MTT have fully proved the good biocompatibility of the pH/temperature multi-sensitive magnetic nanofluid.Due to the stable pH/temperature dual responsive amphiphilic macromolecules of the nanomagnetic fluid,the phase transition temperature(LCST)is 40～44℃ under the condition of low pH value(≤6.5)in the tumor microenvironment,while in the physiological environment(pH≥7.4)LCST>46℃,so the nano-magnetic fluid-mediated magnetothermal therapy is more likely to cause the hydrophobic phase transition of the temperature-sensitive polymer in the tumor tissue,resulting in the nano-magnetic fluid being able to stay in the tumor tissue,thereby achieving Targeted magnetic hyperthermia for tumor tissues.For this reason,we used phosphate buffered solution(PBS solution)of different pH to simulate the physiological environment of tumors and normal tissues,and confirmed the excellent magnetic retention ability of the nano magnetic fluid in tumors after magnetic hyperthermia.Therefore,this study provides another way of thinking for tumor hyperthermia,especially nano-magnetic fluid hyperthermia.