共查询到20条相似文献,搜索用时 31 毫秒
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Shi L De Paoli V Rosenzweig N Rosenzweig Z 《Journal of the American Chemical Society》2006,128(32):10378-10379
Preparation of FRET-based quantum dots as protease sensors-RGDC peptide molecules are bound to the surface of CdSe/ZnS quantum dots. The peptide molecules are then labeled with rhodamine dye molecules. The emission color of the quantum dots change from green to orange due to fluorescence resonance energy transfer (FRET) between the quantum dots and the bound rhodamine molecules. Cleavage of the peptide by selective proteases releases the rhodamine molecules from the quantum dots surface, which results in decreasing FRET efficiency between the quantum dots and the rhodamine molecules. The emission color of the quantum dots changes back to green. 相似文献
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Photoluminescence of nanocomposites of liquid-crystalline polymers and cadmium selenide quantum dots
G. I. Tselikov G. A. Shandryuk I. Yu. Kutergina A. M. Shatalova A. S. Merekalov V. Yu. Timoshenko R. V. Talroze 《Polymer Science Series A》2014,56(6):781-785
The role of specific interactions between a polymer matrix and incorporated quantum dots is one of the critical problems for understanding the effect of the polymer matrix on the optical properties of quantum dots in a nanocomposite material and for creating new photonic materials and related instruments. In this study, cadmium selenide quantum dots have been incorporated into a liquid-crystalline polymer via the interaction of carboxyl groups of the polymer with the quantum-dot surfaces through ionic bonds. From the data of transmission electron microscopy, it has been shown that this interaction provides the localization of quantum dots in the environment of the liquid-crystalline phase of the polymer. Various features of photoluminescent properties have been observed and interpreted in terms of the emission recombination of excitons in CdSe quantum dots, light reabsorption by quantum dots, the effect of the electronic states on the surface CdSe-liquid crystal, and the energy transfer from quantum dots to the polymer liquid-crystalline matrix. 相似文献
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The blinking phenomena of the quantum dots have been utilized in the super-resolution localization microscopy to map out the locations of individual quantum dots on a total internal reflection microscope. Our result indicated that the reconstructed image of quantum dots agreed with the topographic image measured by atomic force microscopy. Because of the superior optical properties of the quantum dots, the high localization resolution can be achieved in the shorter acquisition time with larger detected photon numbers. When the cells were labeled with quantum dots, the sub-cellular structures could be clearly seen in the reconstructed images taken by a commercial microscope without using complicated optical systems, special photo-switchable dye pairs or photo-activated fluorescence proteins. 相似文献
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In-situ encapsulation of quantum dots into polymer microspheres 总被引:2,自引:0,他引:2
Sheng W Kim S Lee J Kim SW Jensen K Bawendi MG 《Langmuir : the ACS journal of surfaces and colloids》2006,22(8):3782-3790
We have incorporated fluorescent quantum dots (QDs) into polystyrene microspheres using functionalized oligomeric phosphine (OP) ligands. We find that a uniform distribution of quantum dots is loaded inside each polymer bead. Some local close-packing of quantum dots in the beads is attributed to the self-polymerization of the functionalized ligands. The presence of quantum dots disturbs the nucleation and growth processes during the formation of polymer microspheres and results in a wider size distribution of the quantum dot-embedded polystyrene beads than for the control without dots. The change in quantum efficiency of the quantum dots before (approximately 20%) and after (12%) loading into the beads substantiates the protection of oligomeric phosphine ligands yet indicates that the properties of these quantum dots are still affected during processing. 相似文献
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TsingHai Wang HuiAn Hsieh YiKong Hsieh ChiShiun Chiang YuhChang Sun ChuFang Wang 《Analytical and bioanalytical chemistry》2012,404(10):3025-3036
Understanding the cytotoxicity of quantum dots strongly relies upon the development of new analytical techniques to gather information about various aspects of the system. In this study, we demonstrate the in vivo biodistribution and fate of CdSe quantum dots in the murine model by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). By comparing the hot zones of each element acquired from LA-ICP-MS with those in fluorescence images, together with hematoxylin and eosin-stained images, we are able to perceive the fate and in vivo interactions between quantum dots and rat tissues. One hour after intravenous injection, we found that all of the quantum dots had been concentrated inside the spleen, liver and kidneys, while no quantum dots were found in other tissues (i.e., muscle, brain, lung, etc.). In the spleen, cadmium-114 signals always appeared in conjunction with iron signals, indicating that the quantum dots had been filtered from main vessels and then accumulated inside splenic red pulp. In the liver, the overlapped hot zones of quantum dots and those of phosphorus, copper, and zinc showed that these quantum dots have been retained inside hepatic cells. Importantly, it was noted that in the kidneys, quantum dots went into the cortical areas of adrenal glands. At the same time, hot zones of copper appeared in proximal tubules of the cortex. This could be a sign that the uptake of quantum dots initiates certain immune responses. Interestingly, the intensity of the selenium signals was not proportional to that of cadmium in all tissues. This could be the result of the decomposition of the quantum dots or matrix interference. In conclusion, the advantage in spatial resolution of LA-ICP-MS is one of the most powerful tools to probe the fate, interactions and biodistribution of quantum dots in vivo. 相似文献
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采用低温水热技术,分别以柠檬酸(CA)和巯基丙酸(MPA)为稳定剂,在70℃的水相中合成了单分散的,粒子尺寸约为4 nm的ZnS∶Co半导体量子点.研究了稳定剂、Co2+掺杂剂及其掺杂量对掺杂量子点发光性能和结构的影响.XRD结果表明,Co2+离子主要掺杂在量子点表面,对主体ZnS晶格没有影响.当采用MPA为稳定剂,掺杂量为5%(摩尔分数)时,掺杂量子点的荧光发射强度最高;而同样掺杂量下采用CA为稳定剂时,量子点的荧光发射强度有所下降.循环伏安研究显示,与空白ZnS量子点相比,Co2+离子的掺杂在ZnS的禁带中形成杂质能级,相应地,ZnS∶Co量子点的吸收边发生红移.与未掺杂ZnS量子点相比,掺杂量子点具有较少的表面非辐射复合中心,因而荧光发射强度显著提高. 相似文献
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Zhen Li Liwei Peng Yaoguo Fang Zhiwen Chen Dengyu Pan Minghong Wu 《Radiation Physics and Chemistry》2011,80(12):1333-1336
Water-soluble orthorhombic colloidal SnSe quantum dots with an average diameter of 4 nm were successfully prepared by a novel irradiation route using an electronic accelerator as a radiation source and hexadecyl trimethyl ammonium bromide (CTAB) as a surfactant. The quantum dots exhibit a large direct bandgap of 3.89 eV, greatly blue shifted compared with that of bulk SnSe (1.0 eV) due to the quantum confinement effect. The quantum dots show blue photoluminescence at ∼420 nm. The influence of CTAB on the growth of the quantum dots was investigated and a possible reaction/growth mechanism was proposed. 相似文献
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Blum AS Moore MH Ratna BR 《Langmuir : the ACS journal of surfaces and colloids》2008,24(17):9194-9197
In this work, we examine the dependence of the fluorescence quantum yield of water-soluble CdSe/ZnS quantum dots on the local environment. The hydrophobicity of the local environment was modified by using different alkyl chain lengths in a set of oligo-ethylene glycols. Our results show that the quantum yield of CdSe/ZnS quantum dots is highest for the longest alkyl chain length, suggesting that a more hydrophobic environment is beneficial for generating bright, water-soluble quantum dots. 相似文献
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Ji-Yao Chen Yee-Man Lee Dan Zhao Nai-Ki Mak Ricky Ngok-Shun Wong Wing-Hong Chan Nai-Ho Cheung 《Photochemistry and photobiology》2010,86(2):431-437
While semiconductor quantum dots produce little singlet oxygen, they may undergo Type I photoreactions to produce other reactive oxygen species (ROS) to kill cells. CdTe quantum dots coated with thioglycolic acid were used to test that possibility. Some thiol ligands were purposely removed to regenerate the surface electron traps that were passivated by the ligand. This allowed photoinduced electrons to dwell on the surface long enough to be gathered by nearby oxygen molecules to produce ROS. The photocytotoxicity of these quantum dots was tested on nasopharyngeal carcinoma cells. Photokilling was shown to be drug and light dose dependent. Using 0.6 μm quantum dots for incubation and 4.8 J cm−2 for irradiation, about 80% of the cells were annihilated. These quantum dots promised to be potent sensitizers for photoannihilation of cancer cells. 相似文献
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The application of quantum dots in capillary electrophoresis immunoassay was studied for the first time. Quantum dots were conjugated with antibody and subsequently tested by electrophoretic separation of free antibody and antibody-antigen complex. Antibody was fluorescently labeled by quantum dots via conjugation procedures and its electrophoretic characteristics were effectively modified due to the attachment of quantum dots. The determination of human IgM by direct CE based immunoassay could be easily achieved by simply changing the pH value of separation buffer. Polymer additive influenced the separation too but the effect was not as significant as buffer pH adjustment. Satisfactory separation of complex from free antibody could be achieved with 20mM sodium tetraborate as separation buffer, at pH 9.8. The immunoassay application of quantum dots in CE offers considerable advantages and can be readily applied to other large bio-molecules. 相似文献
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水溶性ZnO量子点制备及其光学性质 总被引:2,自引:1,他引:1
利用3-巯丙基三乙氧基硅烷对ZnO进行表面修饰后沉积SiO2, 制备出水溶性SiO2包覆ZnO的量子点. 与直接采用正硅酸乙酯沉积包覆SiO2的ZnO量子点相比, 362 nm处的激子荧光发射峰的强度提高了将近4倍. 由于表面引入了巯基官能团, 量子点的水溶性明显提高, 稳定性增强, 即使在较高的盐浓度下也不会团聚. 通过改变条件, 制备出了发光波长在420 nm的蓝色荧光量子点. 相似文献
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CdSe quantum dots are the most studied Cd-based quantum dots with their high quantum yield, high photostability, narrow emission band, and easy synthesis procedure. They are frequently used to develop light emitting diode (LED) due to their unique photophysical properties; however, their narrow emission band causes a challenge to design white LEDs because white light emission requires emission in multiple wavelengths with broad emission bands. Here in this study, we developed CdSe quantum dots with a narrow band-edge emission band and broad defect-state emission band through a modified two-phase synthesis method. Our results revealed that defect-state emission is directly linked to the surface of quantum dots and can be excited through exciting surfactant around the quantum dot. The effect of surfactant on emission properties of CdSe quantum dots diminished upon growing a shell around CdSe quantum dots; as a result, surface-dependent defect-state emission cannot be observed in gradient heterogeneous alloyed CdSxSe1-x quantum dots. 相似文献
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采用巯基化合物修饰的CdTe量子点构建了量子点(供体)-罗丹明6G(受体)荧光共振能量转移体系, 研究了CdTe量子点与牛血清白蛋白(BSA)的相互作用. 结果表明, CdTe量子点与BSA相互作用后提高了CdTe量子点-罗丹明6G 体系的荧光共振能量转移(FRET)效率, 减小了CdTe量子点和罗丹明6G分子间的距离(r), 证实BSA是通过其色氨酸(Trp)残基与CdTe量子点表面金属发生配位作用而直接结合到量子点表面的. 相似文献
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Shouzhu Li Yan Ma Xiuli Yue Zhong Cao Shaoqin Liu 《Journal of Dispersion Science and Technology》2013,34(12):1727-1731
A one-pot strategy for the fabrication of the quantum dots loaded cerasome has been successfully developed based on the condensation of dihexadecylamine and 3-isocyanatopropyltriethoxysilane, followed by spontaneous encapsulation and solubilization of hydrophobic quantum dots into the hybrid liposomal cerasomes in combination of self-assembly and sol-gel process. Fourier transform infrared spectroscopy and mass spectra prove the formation of the intermediate organoalkoxysilane with a lipid-like structure, which forms cerasome vesicles. After encapsulation into cerasome, quantum dots become well dispersed in aqueous solution. Such water-soluble QD cerasomes exhibit a better photostability and retain the luminescence property of the original hydrophobic quantum dots. 相似文献
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A novel approach to preparing PbSe quantum dots in a high-boiling-point solvent (paraffin liquid) was studied. PbSe quantum
dots obtained were transferred from the organic phase to aqueous phase. The PbSe samples were characterized by transmission
electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis, which demonstrated that high-quality PbSe quantum
dots with regular shape and uniform size were prepared. The mechanism of PbSe quantum dot formation was briefly discussed.
The text was submitted by the authors in English. 相似文献