【作者】 王春蓉；

【导师】 周竹发；

【作者基本信息】 苏州大学 ， 材料学， 2011， 硕士

【摘要】 核壳结构复合材料不仅保持了纳米磁性粒子特殊的磁性能,还增强了粒子的生物相容性、热学、机械和化学稳定性等性能。因其特殊的结构和性质已经成为当前材料学一个越来越活跃的研究领域。α-Fe₂O₃纳米粉体具有良好的磁性,催化性,气敏性等性能,且制备工艺简单,价格低廉,用贵金属Ag包覆后,不仅增强了α-Fe₂O₃纳米粉体的拉曼活性,还能增加其化学稳定性、生物相容性等。目前关于这两种颗粒的包覆研究较少,特别是其作为拉曼衬底的研究还未见报道。课题研究成果具有较好的新颖性,并对其在生物医学领域中的靶向给药、检测生物分子等方面有着很好的应用价值。本研究主要采用硅烷偶联剂作为连接桥梁,制备α-Fe₂O₃/Ag核壳结构复合纳米颗粒,并研究其SERS活性。（1）采用水热法制备球形α-Fe₂O₃籽晶纳米颗粒,加入聚乙二醇（PEG）作为分散剂。系统研究了Fe³⁺浓度,PEG含量等条件变化对α-Fe₂O₃纳米颗粒的影响。以γ-氨丙基三乙氧基硅烷（APS）为改性剂,对α-Fe₂O₃籽晶纳米颗粒进行表面改性,并分析了改性机理,进一步通过红外分析,验证α-Fe₂O₃纳米粒子表面通过Fe-O-Si键包覆氨基硅烷分子。（2）采用籽晶法,以甲醛为还原剂,在[Ag （NH₃）₂]+溶液中制备α-Fe₂O₃/Ag核壳结构复合颗粒。研究了APS改性剂、醇水比、还原速度等条件对复合纳米颗粒包覆效果及性能的影响。采用粒度测试仪,XRD、SEM、TEM和EDX对样品进行测试和表征,并分析了包覆颗粒的制备原理。（3）采用吡啶（Py）为探针,并对α-Fe₂O₃/Ag核壳结构复合颗粒作为拉曼衬底的SERS活性和稳定性进行研究,计算它们的增强因子和稳定性。通过大量实验及分析得出如下结论:（1）水热法制备的α-Fe₂O₃籽晶为球形纳米颗粒,分布均匀,粒径大约在40nm左右。作为添加剂,PEG对α-Fe₂O₃颗粒的制备有一定的影响,当PEG=0.5%时,α-Fe₂O₃颗粒分散性有明显提高,但对颗粒形貌影响不大。且当Fe³⁺为0.5mol/L时,有利于α-Fe₂O₃晶核成核;红外分析表明,APS通过共价键结合的方式连接到α-Fe₂O₃籽晶表面,并使其表面富含氨基,便于Ag的包覆。（2）当APS=0.75wt%（质量分数）,醇水比=5:1时,α-Fe₂O₃/Ag核壳结构纳米颗粒的平均粒径为60nm左右,颗粒包覆完整,分散均匀。通过控制AgNO3和α-Fe₂O₃摩尔比可以制备银层可控的α-Fe₂O₃/Ag复合颗粒。当AgNO3和α-Fe₂O₃摩尔比为1时,制备的α-Fe₂O₃/Ag复合颗粒包覆完全且表面粗糙度较好。制备包覆颗粒时,甲醛浓度为3.7%,温度控制在常温下颗粒制备效果较好。（3）对比α-Fe₂O₃籽晶颗粒以及粗糙Ag膜作为拉曼衬底时Py的信号强度,可以得出α-Fe₂O₃/Ag包覆颗粒作为拉曼衬底时具有较强的拉曼信号,通过增强因子计算公式可得Ef =9.8×10⁵。当AgNO₃浓度为1mol/L时,醇水比=5:1时,α-Fe₂O₃/Ag颗粒在1010cm^-1和1038cm^-1处出现显著了SERS增强。在空气中放一段时间后仍能保持较好的增强效果,稳定性好。更多还原

【Abstract】 Core-shell structure composite materials not only maintain the properties of nanoparticles, but also enhance the biocompatibility, thermal, mechanical and chemical properties. Due to their special structures and properties of magnetic core-shell structure composites, they have become an increasingly active area.α-Fe₂O₃ nanoparticles with good magnetic, catalytic, gas sensitivity and other properties. The preparation methods are simple and the price is not expensive. After coating by Ag particles,α-Fe₂O₃ nanoparticles not only enhance their activity of Raman, but also increase their chemical stability, biocompatibility property and so on. At present, there has been a few aboutα-Fe₂O₃/Ag compound nanoparticles, especially for the less reported SERS. The study is quite novel and its research result may apply in the field of biomedical for target administration and detection of biological molecules.The main works of this thesis were that to prepare theα-Fe₂O₃/Ag core-shell structure composite nanoparticles and the study of their SERS activity using silane coupling agent as connecting bridge. （1） Sphericalα-Fe₂O₃ nanoparticles were prepared by hydrothermal method. It was added PEG as dispersant. The effects of the concentration of Fe³⁺, PEG on theα-Fe₂O₃ nanoparticles were analyzed. Theα-Fe₂O₃ nano-particles were modified byγ-aminopropyl triethoxysilane （APS） as a briage. And the mechanism for modification was analyzed. It is characterized by FTIR to further verify the surface ofα-Fe₂O₃ nanoparticles was coated by Fe-O-Si bond. （2） With the seeding method,α-Fe₂O₃/Ag core-shell composite nanoparticals were prepared by the reduction of [Ag（NH3）2]+ with formaldehyde as reductant. The influences of the concentrations of APS, the volume ratio of alcohol to water ratio, reaction speed and other conditions on the coated effect and performance of nanocomposites were investigated. It was characterized by XRD、SEM、TEM and EDX and so on. The mechanism of formationα-Fe₂O₃/Ag core-shell composite was investigated. （3） Pyridine （Py） as a molecule probe was studied Raman spectroscopy （SERS） properties and stability of theα-Fe₂O₃/Ag core/shell composite particles, and calculated the enhancement factors and their stability.According to large numbers of experiments, some conclusions have been drawn: （1） By hydrothermal method,α-Fe₂O₃ particles were spherical, well-dispersed and the average sizes were approximate 40nm. As an additive, PEG had effect on the preparation ofα-Fe₂O₃ nanoparticles. When the content of PEG was 0.5%,α-Fe₂O₃ particles dispersed significantly improved, but it had little effect on the particle morphology. When the concentration of Fe³⁺ was 0.5mol/L, it was better for the nucleation ofα-Fe₂O₃. It is characterized by FTIR to further verify the surface of Fe₂O₃ nanoparticles was coated by Fe-O-Si bond, which was easier to be coated by Ag particles. （2） When the content of APS was 0.75wt% and the volume ratio of alcohol to water was 5:1, the obtainedα-Fe₂O₃/Ag composites by the method were coated completely, well-dispersed and the average sizes were approximate 60nm. By contorting the molar ratio of AgNO3 andα-Fe₂O₃, the thickness of Ag cell composites were tuned. When the molar ratio of AgNO3 toα-Fe₂O₃ was 1,α-Fe₂O₃/Ag composite particles were coated fully and the surface roughness was good. When formaldehyde was 3.7%, and temperature was controlled at room temperature, the preparation effect of composites was better. （3） Compared the Raman substrates of Py signal intensity onα-Fe₂O₃ /Ag coated particles,α-Fe₂O₃ seeding particles and rough Ag film, it was known that the Raman signals was strong. By enhancing factor calculation formula, it can be got Ef = 9.8×105. By coating Ag layer,the intensities of SERS are enhanced at 1010cm-1 and 1038cm-1. And this substrate is fairly stable after being placed in air for a while.更多还原