【作者】 魏源；

【导师】 孙康宁；

【作者基本信息】 山东大学 ， 材料学， 2008， 硕士

【摘要】 肿瘤热疗当前最迫切需要解决的问题是如何对需加热的组织进行均匀加热,使其达到有效的治疗温度（42℃以上）,但又不致引起附近正常组织的永久性损伤。研发一种吸波性能优异、产热率高、生物相容性好的新型肿瘤热种子材料,实现微波靶向定位热疗,将为肿瘤的医治开辟一条高效的新途径,具有十分重要的科学意义与实用价值。本文利用铁氧体及碳纳米管各自良好的吸波特性进行复合互补,采用化学合成-水热处理的方法成功制备出Fe₃O₄/CNTs纳米吸波生物材料。系统研究了制备工艺中的几个影响因素,优化了工艺路线。对复合材料粉体的微观结构、吸波性能及介电常数进行测试、表征和分析。具体研究内容如下:采用化学沉淀结合水热法成功制备了Fe₃O₄/CNTs纳米吸波生物材料。借助XRD、TEM及VSM等手段分析制备样品表明:该复合材料中Fe₃O₄纳米小粒子在CNTs的表面均匀包覆,实现了Fe₃O₄对CNTs的表面修饰,具有普遍性;包覆Fe₃O₄后的CNTs具有纯四氧化三铁相似的亚铁磁性,可以实现复合材料体系在磁场中的定向。在成功制得复合材料粉体的基础上,对工艺路线进行了优化处理,摸索合适的工艺参数。主要讨论了制备过程中Fe³⁺/Fe²⁺的比值R、水热过程中温度与时间、碳纳米管预处理方法、碳纳米管含量等因素对复合材料的影响。借助XRD及TEM等手段分析表明:（1）制备反应过程中的Fe³⁺与Fe²⁺的最佳配比R=1.75时,制备的复合材料中铁氧体的成分是单一相的Fe₃O₄。（2）经过工艺优选,水热温度为160℃、保温时间6h条件下制备的复合材料粉体晶粒尺寸比较符合要求。（3）碳纳米管经过酸化氧化处理,且碳纳米管质量分数不要超过5%时,其表面包覆的Fe₃O₄粒子比较均匀,呈现全面包覆状态,获得的结果比较理想。以Fe₃O₄/CNTs复合材料和切片石蜡为原料制备了Fe₃O₄/CNTs/石蜡复合材料,采用矢量网络分析仪测试碳纳米管复合材料的微波电磁参数,对实测的电磁参数数据进行计算获得反射率R（dB）-f（GHz）曲线,并讨论了碳纳米管预处理方法、碳纳米管含量等因素对复合材料吸波性能的影响。结果表明:Fe₃O₄对碳纳米管包覆起到了调整碳纳米管电磁参数的作用,在原有的介电损耗的同时又增加了四氧化三铁的磁滞损耗和共振吸收等损耗机制。Fe₃O₄/CNTs复合材料在0.5-3GHz范围内具有较好的吸波性能,当使用经过酸化氧化的碳纳米管,并且碳纳米管的质量分数为4%时,复合材料的吸收峰在2.2 GHz附近,反射率达-20dB,频宽为1G左右,能够满足微波热疗用热种子材料对吸波性能的要求。通过复合材料在微波场中的升温实验,表征了材料的热效应,实验结果表明:Fe₃O₄/CNTs复合材料在微波治疗仪理疗探头的辐照下,热效应效果明显;复合材料体系的温度可以升高到42℃以上。从阻抗匹配及损耗机制等方面探讨了Fe₃O₄/CNTs复合材料的吸波机理。研究表明,Fe₃O₄/CNTs纳米粉体由于具有表面与界面效应、特别的微观结构、复合的包覆效应等,将多种损耗机制有效结合,形成了符合需要的宽频、强吸收的复合材料。通过制备工艺,调整复合材料体系的复介电常数和复磁导率,可以实现阻抗匹配,使材料在医用微波频率有较好的吸收性能。更多还原

【Abstract】 One of the major problems of tumor hyperthermia is how to heat up the tumor,and the temperature in tumor can be increased to 42℃and therefore kill the tumor cells,but do not damage normal tissue nearby.A novel thermo-seed material with high thermal efficiency and good biocompatibility can carry out tumor target therapy in microwave hyperthermia.It will be a new and highly effective way for the tumor hyperthermia.In this experiment,ferrite materials and carbon nanotubes were used to compound for their good wave absorption properties respectively.Fe₃O₄/CNTs nano wave-absorbing material was made by means of chemistry precipitation and hydrothermal treatment method.Some influencing factors were studied systematically, and the preparation process was optimized.The microstructure,wave absorption properties and dielectric constant of the composite material powder were tested, attributed and analyzed.It contains as follows.Fe₃O₄/CNTs nano wave-absorbing material was successfully prepared by a simple and effective chemistry precipitation and hydrothermal treatment method.By the testing methods of XRD and TEM,Fe₃O₄ nanoparticles were densely decorated on CNTs, which in the surface of carbon nanotubes is uniform and universal;the hysteresis loops of the decorated CNTs were measured by vibrating sample magnetometer（VSM）,and the result showed that Fe₃O₄/CNTs composite can be easily magnetized in a magnetic field orientation.This material can be used as a new tumor targeting hyperthermia material.Base on the preparation of material powder,the process was optimized to search for the suitable parameters.These factors were mainly discussed:the ratio of Fe³⁺/Fe²⁺ when preparation;temperature and holding time of the hydrothermal treatment;the content and preprocessor of the CNTs;Those conclusions can be indicated by means of XRD and TEM:（1）When the ratio of Fe³⁺/Fe²⁺in the prepare reaction R equals to 1.75, the constituent of ferrite in the composite was pure phase of Fe₃O₄.（2）When prepared by the temperature at 160℃and holding time for 6 hours,the size of crystal of the powder was satisfied.（3）Those powder whose CNTs treated by acidification and oxidation,and the mass percentage of CNTs not exceeding 5%,the Fe₃O₄ particles covered on can be more homogeneous,exhibiting overall covertures.This result was satisfied. The complex permittivity and complex permeability and microwave absorption properties of Fe₃O₄/CNTs/paraffin wax composite were measured by the transmission/reflection coaxial line method.Base on the theoretical calculation of reflection loss,the microwave absorption propertie of carbon nanotube composite has been made in the frequency range from 0.5-3 GHz.The results showed that: Fe₃O₄/CNTs composite also has good absorbing properties in the 0.5-3 GHz range. When CNTs content is 4%,the reflection loss value of-20dB,the bandwidth of 1G has been obtained at 2.2GHz.The result indicates that this composite has significant potential for electromagnetic wave absorption application in tumor hyperthermia.The thermal effect of thermo-seed material was described by heating experiment in the microwave field.The temperature of the system increased over 42℃.The results showed that:The thermal effect of Fe₃O₄/CNTs composite was evident in the microwave field.The microwave absorption mechanisms of those composites were analyzed.The Fe₃O₄/CNTs powder has many good features,including the effect of surface and interface,special microstructure,etc.It combined much deterioration and formed a composite material with broad banding and high absorption.By adjusting the preparation process to impact the complex dielectric constant and complex permeability, the impedance matching can be realized.The material can have good performance in medical microwave frequency.更多还原