【作者】 任呼博；

【导师】 严秀平；

【作者基本信息】 南开大学 ， 分析化学， 2012， 博士

【摘要】 相比于传统的有机荧光染料来说，量子点具有明显的优越性，包括宽而连续的激发光谱、窄而对称的发射光谱、精确可调的发射波长以及强的抗光漂白能力。随着量子点合成和表面功能化研究的发展，量子点在生物样品检测和成像中发挥着越来越重要的作用。本论文旨在合成功能化的Mn掺杂ZnS量子点用于生物样品检测和成像，并简要讨论了量子点与目标物相互作用的机理。主要研究内容如下：（1）发展了一种简便、快速合成高质量水溶性Mn掺杂ZnS量子点的方法，以带正电荷的聚乙烯亚胺为稳定剂，通过微波和超声波的协同作用合成粒径均匀的带正电荷的Mn掺杂ZnS量子点，该量子点对三磷酸鸟苷有高的选择性和灵敏度，能区别于三磷酸腺苷、三磷酸胞苷、三磷酸尿苷、二磷酸腺苷和一磷酸腺苷，为三磷酸鸟苷的检测提供了新方法。在pH7.2的条件下得到了量子点磷光增强值与三磷酸鸟苷浓度之间的线性关系，检出限为0.6μM。对不含三磷酸鸟苷和含有15μM三磷酸鸟苷体系的磷光差值平行测定11次的相对标准偏差为1.7%。聚乙烯亚胺包覆的Mn掺杂ZnS量子点对三磷酸鸟苷的响应在3分钟内就能达到稳定。此外，我们详细考察了聚乙烯亚胺包覆的Mn掺杂ZnS量子点的合成条件、检测过程中的pH值和检测过程中盐度的影响。最终，实现该探针对实际样品中三磷酸鸟苷的检测。结果表明，微波超声波辅助合成的聚乙烯亚胺包覆的Mn掺杂ZnS量子点是一种性能优良的光学探针。（2）采用超声波辅助法合成了具有优良光学性质的三磷酸腺苷包覆的Mn掺杂ZnS量子点，基于超分子Mg²⁺-三磷酸腺苷-精氨酸三元体系，在Mg²⁺存在的条件下，三磷酸腺苷包覆的Mn掺杂ZnS量子点实现了对精氨酸和甲基化精氨酸的快速、高选择性和高灵敏度检测。在量子点合成过程中，三磷酸腺苷作为配体可以增强量子点的水溶性和防止量子点聚集，并且保留三磷酸腺苷对目标物识别的特殊官能团。为了考察超声波辅助水相合成方法比传统合成方法的优势，将两种合成方法所得的三磷酸腺苷包覆的Mn掺杂ZnS量子点进行了对比，结果显示，超声波辅助水相合成法对比传统合成方法，不但合成时间短，而且合成量子点的光强比传统方法合成的量子点光强强2.3倍。此外，我们详细考察了三磷酸腺苷包覆的Mn掺杂ZnS量子点对精氨酸检测过程中紫外光谱、共振光散射光谱、磷光寿命和核磁信号的变化。考察了体系的pH值、缓冲溶液的浓度、量子点的浓度和Mg²⁺的浓度对量子点响应信号的影响。通过实验条件的优化，三磷酸腺苷包覆的量子点在Mg²⁺存在下对精氨酸和甲基化精氨酸的检测限为0.23μM。最终，实现该探针对实际样品中精氨酸和甲基化精氨酸的检测。（3）设计合成了具有优良性质和低毒的二氧化硅包覆硫离子富集的Mn掺杂ZnS量子点（SiO2-S2--Mn-ZnS）探针，实现了细胞内锌离子的原位成像。额外包入探针的硫离子使Mn掺杂的ZnS量子点表面产生悬空键，外加的锌离子与硫离子相互作用，消除了量子点表面由硫离子引起的悬空键，使得SiO2-S2--Mn-ZnS量子点的光谱增强。二氧化硅的包覆，不但增强了该探针的稳定性和生物相容性，而且在细胞成像过程中刺激了细胞对探针的内吞作用。该方法对Zn2+的检出限为80nM，线性范围在0.3¹5μM，对不含锌离子和含有3μM锌离子体系的光强差值平行测定11次的相对标准偏差为1.2%。更多还原

【Abstract】 Photoluminescence spectrometry is the technique of choice for biosensing andcell imaging owing to the apparent advantages of fluorescent probes over othermethods in virtue of sensitivity and convenience. Quantum dots （QDs） offer uniqueadvantages over organic dyes such as great photostability, high photoluminescenceefficiency, size-dependent emission wavelengths, broad excitation and sharp emissionprofiles, thus QDs have been widely explored for biosensing and cell imaging. Themain contents are summarized as follows:（1） Ultrasonic and microwave irradiation-assisted synthesis of PEI-capped Mn-dopedZnS QDs for selective detection of guanosine5’-triphosphate （GTP） wasinvestigated. Compared with fluorescent tags for biomolecules, Mn-doped ZnSQDs have many advantages, such as bright photoluminescence, broad ultraviolet,narrow emission, and high photostability. Application of ultrasonic andmicrowave technique for the synthesis of QDs is gaining importance. Theultrasonic and microwave technique gives several beneficial advantages such asrapid synthesis, formation of uniform crystals, homogeneous nucleation, facilemorphology control, energy efficiency and so on. Under the optimal conditions,the PEI-capped Mn-doped ZnS QDs gives excellent selectivity andreproducibility, and low detection limit （3s;0.6μM）. The developedphosphorescence probe favors biolobical applications since the interference fromscattering light and autofluorescence is effecitively eliminated.（2） Ultrasonic assisted synthesis of adenosine triphosphate （ATP）-capped Mn-dopedMn-doped ZnS QDs for rapid, selective and sensitive detection of arginine andmethylated arginine based on the supramolecular Mg²⁺-ATP-arginine ternarysystem was investigated. The ultrasonic approach was used for the synthesis ofATP-capped QDs because of its rapid, simple, low cost, and efficient merits. Thechoice of ATP as capping ligand in synthesis of functional QDs provided apowerful means of rationally controlling Mn-doped ZnS QDs properties. ATP could render Mn-doped ZnS QDs stable against aggregation and water soluble,and tetain the nucleotides structure needed to specially bind to its target. Thespecific binding of ATP-capped Mn-doped ZnS QDs in the presence of Mg²⁺gave excellent selectivity and reproducibility （1.7%relative standard deviationfor11replicate detections of10μM arginine） and low detection limit （3s;0.23μM） of arginine.（3） Silica-coated S2--enriched Mn-doped ZnS quantum dots （SiO2-S-Mn-ZnS QDs）was developed for imaging intracellular Zn2+ions. Detection of intracellular Zn2+has gained great attention because of its biological significances. Here we showthe fabrication of SiO2-S-Mn-ZnS QDs by enriching S2-with a silica shell on thesurface of Mn-doped ZnS QDs via a sol-gel process for imaging intracellularZn2+ions. Mn-doped ZnS QDs were chosen because of excellentphotoluminescence properties and a nontoxic nature. The prepared probe offershigh sensitivity and selectivity for Zn2+at physiological pH by taking advantageof the surface defects of the SiO2-S-Mn-ZnS QDs. The developed probe gave agood linearity for the calibration plot （the recovered photoluminescence intensityof the SiO2-S-Mn-ZnS QDs against the concentration of Zn2+from0.3to15μM）,excellent reproducibility （1.2%relative standard deviation for11replicatemeasurements of Zn2+at3μM）, and low detection limit （3s;80nM Zn2+）. TheSiO2-S-Mn-ZnS QDs showed negligible cytotoxicity, good sensitivity, andselectivity for Zn2+in a photoluminescence turn-on mode, being a promisingprobe for photoluminescence imaging of intracellular Zn2+.更多还原