几种纳米颗粒的光学性质研究及其在生物成像中的应用

发布时间：2018-02-12 12:39

本文关键词： 单光子荧光双光子荧光光学非线性效应量子点 AIE染料纳米金棒光学生物成像深层组织成像　出处：《浙江大学》2015年博士论文　论文类型：学位论文

【摘要】：随着社会的进步,健康问题愈受重视。生物成像为医学研究与临床的诊断治疗提供了很好的辅助,是现代医学的重要组成部分。相较于广泛使用的X射线,B超,磁共振等成像手段,光学生物成像具有分辨率高,无辐射污染,适用范围广等优点,而倍受人们关注。本文介绍了以几种光学效应为核心,采用纳米颗粒作为辅助显色剂的生物成像方面的许多研究工作。主要的研究内容包括：1、采用高量子产率的量子点来做单光子荧光成像。疏水的CdSe/Zn S量子点通过SiO2包覆与羧基修饰,转化为亲水性,以与生物环境相匹配。包覆后它们具有良好的均一性,稳定性,与分散性。将它们与转铁蛋白连接后,用于对HeLa细胞的单光子荧光成像,实现了对癌细胞的特异性标记,这在肿瘤的识别与治疗中具有重要意义。2、采用具有高荧光亮度的AIE染料来做双光子荧光成像。对有机染料BT3的AIE特性进行了表征,并将它们包覆成纳米颗粒。BT3纳米颗粒发红光,并且有很大的Stokes频移,有利于生物成像。通过双光子诱导荧光法测得BT3纳米颗粒在1040 nm处的双光子吸收(2PA)截面达到了2.9×106GM,比770-860 nm范围内的值都要高,也比许多商用染料(如若丹明B)的2PA截面要大很多。采用蒙特卡洛仿真发现了1040 nm比800 nm激光束在生物组织中有更好的穿透能力。观察了BT3纳米颗粒在小鼠体内的分布与代谢情况,发现它们主要集中在肝脏,并且可以通过代谢排出体外。采用1040 nm的飞秒光源激发,用BT3纳米颗粒注射小鼠,实现了鼠脑活体的双光子荧光成像,可以清晰地看到各种血管,成像中深度达到了700 μm。这种合适的激发光源与大2PA截面的AIE纳米颗粒的结合对提高成像浓度非常有效。3、采用具有丰富非线性信号的纳米金棒来实现非线性光学效应成像。制备了多种纳米金棒,并对它们分别进行了高分子聚合电解质包覆,SiO2包覆,与PEG包覆以适应不同的需求。利用离散偶极子近似(DDA)对纳米金棒的吸收、散射与表面电场特性进行了模拟。采用自搭建的系统测量了纳米金棒在近红外飞秒光激发下的非线性信号。用纳米金棒来标记细胞,分别以1260 nm与1580 nm飞秒光作为激发光源,利用纳米金棒的二次谐波、三次谐波等信号实现了细胞的多通道非线性成像,这对于今后将纳米金棒应用于活体的第二与第三光学组织窗口非线性成像提供了很好的基础。
[Abstract]:With the progress of society, the health problems are paid more and more attention. Biomedical imaging provides a good aid for medical research and clinical diagnosis and treatment, is an important part of modern medicine. Compared with the widely used X-ray, B-ultrasound, Magnetic resonance imaging and other imaging methods, optical biological imaging has the advantages of high resolution, no radiation pollution, wide range of application, and has attracted much attention. This paper introduces several optical effects as the core. Many research work on biological imaging using nanoparticles as auxiliary chromogenic agent. The main research contents include: 1, single photon fluorescence imaging using quantum dots with high quantum yield. Hydrophobic CdSe/Zn s quantum dots pass through SiO2. Coating with carboxyl group, They were transformed into hydrophilic to match the biological environment. They were coated with good uniformity, stability, and dispersion. They were connected with transferrin and used for single photon fluorescence imaging of HeLa cells. The specific labeling of cancer cells was realized, which is of great significance in the recognition and treatment of cancer cells. Two-photon fluorescence imaging was performed with AIE dyes with high fluorescence brightness. The AIE characteristics of organic dyes BT3 were characterized. They are coated into nanoparticles. BT3 nanoparticles glow red and have a large Stokes shift. The two-photon absorption 2PA cross-section of BT3 nanoparticles at 1040nm is 2.9 脳 106GM, which is higher than that in the range of 770-860 nm. The cross section of 2PA was also much larger than that of many commercial dyes (such as Rhodamine B). Monte Carlo simulation showed that 1040nm laser beam had better penetration ability in biological tissue than 800nm laser beam. The BT3 nanoparticles were observed in mice. Distribution and metabolism, It is found that they are mainly concentrated in the liver and can be excreted from the body by metabolism. By using 1040nm femtosecond light source and injecting mice with BT3 nanoparticles, two-photon fluorescence imaging of the brain is realized, and various blood vessels can be clearly seen. The depth of the imaging is 700 渭 m. The combination of the suitable excitation source and the AIE nanoparticles with large 2PA cross-section is very effective to increase the imaging concentration. The gold nanorods with abundant nonlinear signals are used to realize the nonlinear optical effect. A variety of nanocrystalline gold rods have been prepared. They were coated with polyelectrolyte and PEG respectively to meet different requirements. The absorption of nanocrystalline gold rods was obtained by using discrete dipole approximation (DDAA). The characteristics of scattering and surface electric field were simulated. The nonlinear signals of nanocrystalline gold rods excited by near-infrared femtosecond light were measured by a self-built system. The cells were labeled with nanocrystalline gold rods, using 1260nm and 1580nm femtosecond light sources, respectively. The second harmonic and third harmonic signals of gold nanorods are used to realize the multichannel nonlinear imaging of cells, which provides a good basis for the application of nanocrystalline gold bars to the nonlinear imaging of the second and third optical tissue windows in vivo in the future.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：Q-33

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