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医用纳米功能探针的研制及其在荧光、磁性标记和靶向光热治疗方面的应用

Development of Medical Nanoprobes and Their Applications in Fluorescent, Magnetic Labeling and Photothermal Therapy

【作者】 尹乃强

【导师】 许小亮;

【作者基本信息】 中国科学技术大学 , 凝聚态物理, 2014, 博士

【摘要】 随着科学技术的高速发展,器件、设备的小型化已成为其发展的主要趋势,纳米材料也因此得到了科研工作者的高度关注。半导体荧光量子点(优异的发光特性)、纳米金属(等离子体共振效应)以及磁性材料(磁学性能)是目前纳米材料领域中的三类热门材料。相比于传统的荧光染料,半导体荧光量子点具有发射峰较窄、发射波长连续可调、抗漂白能力强、发光强度高、热稳定性好等特点,更利于在实际生产和生活中应用,如生物医学中作为示踪剂、在页岩气开采中作为标记物等。纳米金属因其优良的等离子共振效应,可用其散射效应增强其周围发光物质的发光强度,进而提高检测灵敏度;利用其吸收效应制成的光热探针,对癌细胞进行光热治疗,是一种非介入、无痛楚治疗手段。磁性纳米材料具有超顺磁性,可以实现定向输运药物、磁分离、增强磁共振成像、磁热治疗等功能。然而纳米材料单一的优良性质往往不能满足实际的需要,因此多功能复合材料已逐渐登上历史的舞台,复合材料集多种功能于一体,极大地提高了效率、降低了成本。基于此,本论文除了通过不同手段制备多种纳米材料之外,还制备了多种复合纳米材料,并对制备的纳米材料进行了表征分析和应用研究。本论文的主要研究内容如下:第一章主要对半导体荧光量子点、纳米金属以及磁性材料的基本概念、性质、制备方法以及应用进行了综述。第二章首先对半导体荧光量子点的结构和光学特性进行了描述;通过液相法制备了水溶性CdTeS量子点(发射波长从536nm至774nm连续可调),为了进一步提高量子点的发光稳定性和发光强度,制备了CdTeS(?)CdS核壳量子点,CdS壳的包覆时间为14min时荧光量子点的荧光强度达到最大(0.6倍提高),并利用此量子点成功实现了对乳腺癌细胞的荧光标记;为了解决Cd系量子点的毒性问题,通过液相法制备了锰掺杂的硫化锌量子点,并对影响量子点发光的因素(Mn2+的掺杂浓度、宿主元素锌与硫的比例、反应所处的气氛)进行了讨论分析,当Mn2+掺杂浓度为5%、锌与硫的比例为5:4.5、氮气下反应时量子点具有最佳的荧光发射效果,最后在锰掺杂硫化锌量子点外面包覆硫化锌壳同样提高了量子点的发光强度,其最高实现了0.3倍的荧光增强。第三章主要研究了基于纳米金属局域表面等离子体共振特性的荧光增强效应。我们首先对其荧光增强原理进行了归纳总结;然后通过两种方法(籽晶生长法和一步生长法)制备了金纳米棒,对其结构特征及其光学特性进行了讨论分析,金纳米棒具有两个分立的局域表面等离子体共振峰,通过控制硝酸银的用量实现了对金纳米棒的吸收峰的有效调控(600nm至800nmm);使用多元醇方法制备了银纳米立方体,并研究了其结构和光学特性,通过时域有限差分方法(FDTD)软件对银纳米立方体(外来光入射条件下)周围的电场分布情况进行了模拟计算,在银纳米立方体的拐角和拐边处有强的电场分布;制备了Ag@dye-doped SiO2复合纳米材料,利用银纳米球的局域表面等离子体共振效应实现了对荧光染料的发光增强,当染料掺杂的二氧化硅层厚度为10nm时,此复合材料实现了高达11倍的荧光增强。第四章研究了纳米金属局域表面等离子体共振吸收特性及其光热效应。通过液相法制备了金纳米笼、金纳米星、金纳米球壳,研究了不同因素对其光学特性的影响,并将这种结构应用于对癌细胞的光热治疗,都实现了对癌细胞的有效杀灭作用;利用逐层生长方法制备了光热/荧光复合纳米材料(金纳米星@SiO2@CdTeS@SiO2),研究了其光热特性及荧光特性,复合纳米材料具有分散性好的特点,相比于纯CdTeS量子点,复合纳米材料的发光强度提高了23%,利用复合纳米材料表面链接抗体的方式实现了对特定癌细胞的靶向标记,同时也实现了对癌细胞的特异性杀伤,此效果高达99.8%;通过多种方法制备了价格低廉、尺寸小、无毒型的光热材料硫化铜和硒化铜,研究了影响其吸收特性的多种因素,并探讨了硫化铜对癌细胞的光热治疗效果,它也具有比较好的光热治疗效果。第五章研究了磁性材料Fe304的超顺磁性。通过共沉淀法、水热法以及高温裂解法制备了Fe304纳米颗粒,研究了其结构特性和磁学性能,它们都具有好的颗粒分散性、高的饱和磁化强度(40emu/g以上)等特点;通过传统的Stober方法,制备Fe3O4@SiO2复合纳米颗粒,此种纳米颗粒具有较好的均匀性和分散性,对共沉淀方法制备的Fe304纳米颗粒首先用油酸进行表面修饰,然后进行二氧化硅包覆,得到了颗粒分布均匀的Fe3O4@多孔Si02结构,其中多孔结构可以实现对分子(如药物分子)的负载作用;通过逐层生长法制备了磁性/荧光双功能复合纳米颗粒,同时实现了超顺磁性和荧光标记示踪的功能。第六章对全文进行了概括,总结了本文的创新点以及存在的问题,并对下一步可进行的工作进行展望。

【Abstract】 With the rapid development of science and technology, miniaturization is the goal of equipment and instrument. Thus nanomaterials are gained much attention, duo to their special structural characteristics and optical characteristics. Quantum dots with excellent emission property, nanometal with surface plasmons resonance (SPR) properties, magnetic nanoparticles with superparamagnetism are three important nanomaterials. Compared to traditional fluorescent dyes, quantum dots have many advantages, such as continuously adjustable emission spectrum, good resistance to bleach, good stability and so on. Due to the localized surface plasmons, metal nanoparticles can enhance the fluorescence intensity of luminescent materials, which distribute around the metal particles. Metal nanoparticle with special structure can work as light absorbers and produce localized high temperatures to kill tumor cells. Photothermal therapy is a non-interventive, non-complaints care method. Magnetic nanoparticles with superparamagnetism have many applications such as drug delivery magnetic separation and hyperthermia. Recently, increasing attention has been diverted to the fabrication of bifunctional nanostructures consisting two kinds of materials with different properties, such as the nanoparticles possessing magnetic and luminescent property.In chapter1, we carry out a brief overview on the quantum dots, metal nanoparticles and magnetic nanoparticles. The overview includes the concept, property, the preparation method and relative application.In chapter2, we study the relative properties about quantum dots at first. Due to the quantum size effect, quantum dots (CdTeS) with various emission wavelengths were parpared through liquid phase method. In order to improve the fluorescence intensity, we coated a shell (CdS) on the surface of the CdTeS quantum dots. We studied the biomedical application of CdTeS@CdS core-shell quantum dots. We prepared Mn-doped ZnS quantum dots in order to avoid the toxicity of Cd ion. The influence factors on the optical property of Mn-doped ZnS quantum dots were discussed, which contain manganese ion concentration, ratio between Zn and S, reaction atmosphere. Through coated a shell (ZnS) onto the surface of Mn-doped ZnS quantum dots, the fluorescence intensity of quantum dots was also imporved.In chapter3, we carried out a study on the fluorescent enhancing effect using the metal nanoparticles, dut to its local surface plasmons. The fluorescence enhancement principle was firstly discussed. Two methods (seed crystal growth method and non-seed crystal growth method) were used to prepare gold nanorod with different size. We talked about the morphologies and optical properties of these gold nanorods. Silver nanocube and nanosphere were produced by reduction of aqueous silver nitrate with ethylene glycol in the presence of PVP as stabilizer. Finite-difference time-domain (FDTD) method was used to model the electrodynamics around the metal nanoparticles with certain incident light. Composite Ag@dye-SiO2particles were synthesized through a liquid phase method with good homogeneity and dispersity. The optical properties of Ag@dye-SiO2nanoparitcle with different thickness of dye-SiO2layer were investigated. The fluorescence signal of Ag@dye-SiO2nanoparticle was enhanced compared to the sample without silver core.In chapter4, we prepared several photothermal materials include metal nanoparticle and semiconductor nanoparticle. The photothermal materials are based on the strong absorption ability, through which the light energy is converted into heat energy effectively. Through liquid phase method, various gold nanoparticles (Au nanocage, Au nanostar, Au nanoshell) were prepared. The morphology and the optical property of these gold nanoparticles were discussed. FDTD solution also used to model the electrodynamics around the gold nanoparticles. We prepare gold nanostar/quantum dots-doped SiO2structured nanocomposite, which is composed of gold nanostar as the core with excellent photothermal property and quantum dots-doped SiO2as the shell layer with good fluorescence signal. We prepared a kind of non-toxicity copper material (CuSe and CuS). We studied the influence factors on the the optical property of copper material. We also studied the material’s photothermal effect on the cancer cell.In chapter5, we studied the superparamagnetism of magnetic nanoparticles. Three methods (coprecipitation method, hydrothermal method, high temperature pyrolysis) were used to prepare Fe3O4nanoparticles. The structure and properties of the nanoparticles were studied. A novel nontoxic, magnetic and luminescent nanoprobe was prepared by complex nanoparticles, which is composed of Fe3O4nanoparticle and Mn-doped ZnS quantum dots (QDs). The nanocomposite probe can provide both visible optical and magnetic resonance imaging simultaneously.In chapter6, we carry out a general summary about this thesis and analysis the potential work, which can be carried out in the future.

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