【作者】 梁森；

【导师】 任咏华； 杨柏；

【作者基本信息】 吉林大学 ， 物理化学， 2012， 博士

【摘要】 上转换发光纳米粒子具有吸收低能量的激发光子，并发射出一个高能量光子的独特性质，因此在过去的十几年中吸引了广泛的研究兴趣。由于性能独特，上转换发光纳米粒子潜在应用于固体激光器，光发射装置，高贯穿扫描，低密度红外成像，生物探针和生物检测等方向。当然，实现最终应用还有很多问题需要解决。例如：获得高强度、颜色可控的发光，提高生物兼容性，与其他材料进行复合等。基于上述考虑，我们在本文中选取上转换材料中稀土掺杂的氟钇化钠纳米粒子进行研究，因为氟钇化钠作为主体材料具有低的振动能量，低的非辐射衰减率，高的辐射发射率，是上转换纳米粒子中最好的主体材料。研究内容主要分为以下三个部分：第一，通过“一锅法”我们在相对低的温度利用更“绿色”的溶剂成功合成了晶型优良尺寸分布均匀的稀土掺杂氟钇化钠纳米粒子。通过改变投料比，加热时间或者加热温度以及金属掺杂，我们可以改变纳米粒子的形貌、尺寸、晶体类型、发光强度和颜色，为进一步的应用提供了优良的材料。第二，利用多种常见的两亲性表面活性剂去修饰有机相合成的纳米粒子，使其表面形成双层分子结构，从而把有机相纳米粒子以独立分散或组装体的形式转移到水相，根据不同表面活性剂赋予粒子的表面功能，再进行硅化作用或者聚合作用形成壳层，增加其生物稳定性和兼容性。第三，利用半导体或者贵金属纳米粒子与氟钇化钠纳米粒子组装，形成复合粒子，通过能量转移，改变原有发射峰之间的比率，从而实现功能集成和发光颜色可调，为生物应用提供更广阔的空间。更多还原

【Abstract】 Rare-earth doped nanoparticles, with a combination of nano-size and specialrare-earth characteristics, have been widely used in various fields such as optics,electrics and magnetics in recent decades. One of the rare-earth doped upconversionluminescent nanoparticles have become the focus since they have special luminescentproperties which is to emit a high-energy photon with absorbing tow or morelow-energy excitation photons. As a kind of upconversion luminescent particles whichis the most stable, most controllable in shape and pattern and has the least defect andmost intensive luminescence, the lanthanides doped NaYF4is applied in lasers,anti-counterfeit labels, fingerprint acquisition and so on, especially several applicationsin biomedical science these years. However, the previous synthesis routines are notsuitable for mass production because of high-energy consumption, high cost andpoisonous by-product. So a new synthesis method which is more environmental friendlywith lower energy consumption and cost is in urgent need. On the other hand, this kind biomedical science, which means the particles synthesized in organic phase should betransferred in to aqueous phase. The previous method is complicated since a newcondition should be made with every single function group. Thus it is necessary to finda simple, convenient and universal method for organic-to-aqueous phase transportation.While simply upconversion is not enough for imaging, a kind of composite luminescentparticles is needed for various colors or luminescent controllable composites.In Chapter II, on the premise of low energy consumption and low cost, we havesynthesized upconversion luminescent, uniform and hexagonal NaYF₄:Yb³⁺,Er³⁺(Tm³⁺)particles using oleic acid as the ligand and liquid paraffin as solvent at relatively lowtemperature （280℃）. Based on this method, the crystals phase can be changed fromcubic to hexagonal crystal. Particles sized from20nm to150nm can be prepared viacontrol of heat duration; and the shape can be ball, ellipse，plate，cubic through thechange of ligand and solvent; while the color of the luminescence can be tuned bydoping of different lanthanide. We studied the impacts of particle patterns, sizes, andcrystal types, the intensity of upconversion luminescence and color change throughrigid control of reaction condition, which is totally controllable. Finally we tunedupconversion luminescence color via doping of transition metal elements. This realizesthe excitation and emission ranging from red light to near-infrared, which make a easierimaging inside biological body. From the experiment above, we have lowered cost andenergy consumption for mass production in “green” and environment protection,providing promising application.In chapter III, we use common small molecule surfactants and particle claddingoleic acid ligand to build double-layer structure through hydrophobic-hydrophobicinteraction and outward hydrophilic end to transport particles from organic phase toaqueous phase. The aqueous phase particles showed good dispersion and upconversionluminescence. This method was easy to operate, and universal for ion-, anion-, and non-ionic surfactant. silicification on the surface and polymerization can be carried outwith different properties with the change of surfactant, forming SiO2or PPy core-shellstructure. Then we can obtain nanoparticles converted on independent dispersed ordifferent sized super structure assembly using microemulsion droplets template viachange of concentration of surfactant. Also, the size of super structure assembly canchange from100nm to500nm in different concentration of surfactant. Thesuperstructure assemblies can be well dispersed in water, and the luminescence intensityof upconversion assembly NaYF₄:Yb³⁺, Er³⁺(Tm³⁺) is1.5times as much as those ofsingle dispersed ones. Finally we chose amphipathic triblock copolymersF127（PEO-b-PPO-b-PEO） to transport different sized upconversion nanopartiles fromorganic phase to aqueous phase. The transported NaYF₄:Yb³⁺, Er³⁺(Tm³⁺) nanoparticleswere applied in biological labeling and imaging. Upconversion nanoparticles modifiedwith F127showed good biological stability and luminescence intensity. Compared withthose small surfactant, F127is almost non-toxic to organism. Our research has providednew idea for applications of upconversion nanoparticles in biological field.In chapter IV, we first use noble metal nanoparticles interaction between Au andNaYF₄:Yb³⁺,Er³⁺(Tm³⁺) nanoparticles to control the optical proterties ofNaYF₄:Yb³⁺,Er³⁺(Tm³⁺) nanoparticles. In the experiment, we preparedNaYF₄:Yb³⁺,Er³⁺(Tm³⁺) and Au composite via （1） host-guest interaction betweencyclodextrin and NaYF₄:Yb³⁺,Er³⁺(Tm³⁺) surface oleic acid;（2） microemulsion dropletstemplate;（3） insitu synthesis of nanoparticles. The three composite can be welldispersed in water. The study of the spectrum data showed that the relative intensity ofemmisiton peaks of NaYF₄:Yb³⁺,Er³⁺(Tm³⁺) nanoparticles have changed a lot due tointroduction of Au particles. Then we use mercaptoacetic acid stabled CdTe QDs totransport NaYF₄:Yb³⁺,Er³⁺(Tm³⁺) nanoparticles from organic phase to aqueous phase,obtaining CdTe modified NaYF₄:Yb³⁺,Er³⁺(Tm³⁺) nanoparticles in different size. Duringthe study of the optical properties of this composite, we have found that under excitation of980nm near infrared, energy transfer occurred between NaYF₄:Yb³⁺, Er³⁺(Tm³⁺)nanoparticles and CdTe QDs. The specific wavelength emmision of NaYF₄:Yb³⁺,Er³⁺(Tm³⁺) nanoparticles was effectively transferred to the adsorption band of CdTeQDs, thus leading to the emission of CdTe QDs and turning of the intensity of emissionpeaks among NaYF₄:Yb³⁺,Er³⁺(Tm³⁺) nanoparticles. The preparation of multifunctionalcomposite optical material can provide wider application in biological detection andlabeling.更多还原