【作者】 薛国胜；

【导师】 郭光灿； 李银妹；

【作者基本信息】 中国科学技术大学 ， 光学与光学工程， 2014， 博士

【摘要】 光镊是利用高度聚焦的激光微束形成的光学梯度力势阱来实现对微纳米量级粒子的捕获与操控的技术,它所产生的皮牛量级的力正好适用于操控微纳米量级的粒子。随着各种新技术的出现,光镊技术近年来发展十分迅速,出现了阵列光镊,表面等离子体光镊,涡旋光镊等新型光镊。同时光镊技术与其他技术相结合,比如光刀、双光束干涉技术、微弱荧光检测技术、扫描共焦显微技术、电泳及光谱分析,拉曼光谱等,更是扩大了其应用领域。Raman光谱是分析物质化学组分和结构的重要检测技术,它具有化学指纹识别的功效,与荧光光谱相比,Raman光谱具有不受水的吸收影响,不需要对样品进行复杂的荧光标记,样品用量少等优点。我们将显微拉曼光谱技术和光镊操纵技术相结合,利用785nm激光做光源,研制了一台拉曼光镊系统,该系统可以同时实现稳定捕获单个微米粒子并长时间稳定激发收集拉曼光谱信号的功能。由于粒子被稳定的俘获在远离波片表面的液体中,可以避免样品池表面对探测信号的干扰,因此在悬浮胶体体系微粒光谱探测中具有很大的优势。两亲嵌段共聚物具有亲水和疏水两部分,能够自组装形成微米尺度的聚集体,胶束。嵌段共聚物的组装和小分子表面活性剂一样,在溶液中能够呈现出不同的形态,如复合胶束、圆球状、长棒状、空心囊泡等。由于嵌段共聚物制备的囊泡的研究在微反应器,药物输运,对比增强成像和模拟生物膜等方面的应用潜力很大,聚合物囊泡研究引起了科学家们的广泛兴趣。在溶液中,含有偶氮生色团的亲疏水两嵌段聚合物在光辐照下具有光响应特性,如光诱导沉淀,凝聚和自组织等。最近,含有偶氮苯生色团的两亲性嵌段共聚物受到人们广泛的关注。不同波长光照下,偶氮基团的顺反异构反应将使偶氮聚合物的结构和性质发生变化,这种微观变化会导致宏观转变。正是由于聚合物囊泡的巨大应用前景,我们利用拉曼光镊对偶氮囊泡体系的光响应行为进行了一系列实验研究。本文工作主要包括：研制具有光镊捕获,拉曼光谱探测,紫外激发等多种探测功能的拉曼光镊系统,对偶氮聚合物组装的囊泡结构的光响应行为进行表征,通过探测交联剂以及间隔基对囊泡膜性质的影响,推理囊泡光致形变过程中的反应机理；组装双组份偶氮囊泡发现了微相分离现象,并对微区内光致异构速率进行分析；利用微针吸附方法探测了偶氮囊泡的表面弹性模量。本论文内容一共九章。第一章绪论,主要介绍拉曼光镊的研究背景,应用和研究现状以及将拉曼光镊应用于偶氮囊泡的研究意义。第二章首先介绍拉曼光镊实验设备的设计原理,系统构成,应用范围以及使用方法。然后介绍将拉曼光镊系统应用于偶氮囊泡的光响应研究而进行的几个实验。第三章是交联囊泡的伸缩膨胀速率分析,第四章是对不同间隔基长度的偶氮囊泡发生不同的光致可逆形貌转化的机理分析,第五章是甲氧基偶氮囊泡的破裂重组,第六章介绍双组份囊泡的微相分离,第七章讲述偏振拉曼探测囊泡表面基团取向等。第八章将微针与光镊结合起来探测囊泡膜的弹性模量。最后第九章是论文的总结与展望。本文的创新点主要在于发展光镊技术使之与拉曼光谱技术相结合形成一套多功能探测系统。利用这套系统应用于对偶氮聚合物囊泡的光响应特性进行研究,得到一系列新现象比如光致形貌转化,微相分离运动,破裂重组等,并根据这些过程中拉曼光谱信号演化对其机理做了解释。这项研究对于探索新型功能囊泡制备有很大的借鉴意义。更多还原

【Abstract】 Optical tweezers(OT) are the beam gradient optical traps where micro particles could be trapped by focusing the laser beam using a microscope objective. The gradient force generated by optical tweezers is in the pinoNewton region and is suitable to trap and manipulate microscale and nano-scale particles. In the last ten years, with the advent of new technologies like plasma, hologram, and photon crystal fiber the OT technologies develops very quickly, a lot of new OTs have been created such as surface plasmon optical tweezers(SPOT), optical trap array and optical vertex trap and so on. When combined with other technologies such as weak fluorescence detection technology, dual-beam interference technique, scanning confocal microscopy and Raman spectrum, the application areas of OT are much more expansive.Raman spectroscopy is an important detection technique in analyzing the chemical composition and structure of matter. It is able to achieve chemical fingerprint recognition and plays a unique role in chemistry, materials science, biomedicine, food hygiene, environmental monitoring and other fields. Compared with the fluorescence detection technology, its ascendancy lie in weak absorption of water from the sample, is unnecessary complex fluorescent labeling, only require a small amount of sample etc. We employ the785nm diode laser as the light source of OT and combined the Raman spectrometer to build a set of optical tweezers Raman spectrum (OTRS) system. The OTRS system can capture a single micron particles to collect Raman spectra excitation signal stably for long time. Since the particle is stably trapped in liquid remote from the surface of glass-plate to avoid interference with the surface effect of the sample cell, it is suitable in the spectrum detection of suspended particle in colloidal system.Amphiphilic block copolymers can self-assemble to form micron size aggregates or micelles. Block copolymer aggregates, like small molecule surfactants, can assume a range of different morphologies in dilute solution, including spheres, rods, vesicles, compound micelles, and others. In the past years, vesicles prepared from block copolymers have been well investigated. The interest in polymer vesicles was motivated, in part, by their potential use as micro reactors, targeted drug delivery, contrast enhanced imaging, and mimic for biological membranes. In solutions of amphiphilic molecules or polymers containing suitable chromophores, exposure to light can be used to achieve photo responses, such as precipitation, aggregation, and self-assembly. Recently, azobenzene-containing amphiphilic block polymers have received considerable attention. Upon light irradiation, azobenzene polymers can show a variety of structure and property variations triggered by the trans-cis photoisomerization of the azo chromophores, which in turn triggers mesoscopic up to macroscopic changes. Base on the big application potential of the polymer vesicle system, we utilize the OTRS system to study the photoresponsive behaviors of azobenzene vesicles. They are described in the following part.There are nine chapters in this thesis. The first chapter is the introduction of my work, include the research background status of OTRS, and the significance of studying property of azobenzene containing vesicles. The second chapter we describe the design principles, system configuration of OTRS system and its applications and instruction. And then in the next six chapters, I present six experiments about the application of OTRS system in the photo response behaviors of azobenzene containing polymer vesicle. The first experiment is I add the cross linker (Dibromopropane, DBP) to the membrane of the azobenzene polymer vesicles (PNIPAM-b-PAzPy6), and detecte the photo induced shrink-expansion of vesicle under UV light. The next experiment is three kind of polymers with different space chain length self-assemble vesicle have different morphology change under UV light irradiation. We also used another azobenzene polymer (PNIPAM-b-PAzoMO) to prepare vesicle, and it ruptures and reconstructed in to small vesicle under UV light. When two different azobenzene polymer are combined in the same solution, they formed Janus vesicles. The two part of the binary vesicle have different rate of trans-cis isomerization. We add polarize element to the OTRS system to detect the orientation of azobenzene group in the shell of vesicle under UV light. Because the mechanical property is important in the stability of the vesicle, and it is harder than the small molecular vesicles, I used the micropipette absorption (MPA) technology to detect the elastic modular of the polymer vesicles.The main innovation of this dissertation is to develop optical tweezer technology. I combined optical tweezers and Raman spectroscopy to form a versatile detection system OTRS. I use this detect system to study the photo induced transform behaviors of azobenzene containing polymer vesicles, and base on the Raman change analyzed its mechanism. The study have major implications for the exploration of new functional vesicles.更多还原