CdSe/ZnS量子点探针用于检测猪链球菌2型溶菌酶释放蛋白(MRP)抗原的新方法研究

合成了高发光效率的CdSe/ZnS量子点并制备了CdSe/ZnS量子点-溶菌酶释放蛋白(MRP)抗体探针, 利用凝胶电泳和分子光谱法研究了MRP抗体与CdSe/ZnS量子点的结合机理. 荧光光谱法优化了CdSe/ZnS量子点-MRP抗体探针制备的影响因素, 建立了一种测定MRP抗原的新方法, 其线性范围为5.0×10－8～1.5×10－6 mol/L, 线性相关系数为0.9976, 检测限为 1.9×10－8 mol/L.     

基于CdSe/ZnS量子点构建乙酰甲胺磷荧光检测方法研究

本文以CdSe/ZnS量子点为荧光探针,基于乙酰甲胺磷对CdSe/ZnS量子点的荧光猝灭效应,建立了一种可快速测定乙酰甲胺磷的荧光检测方法。通过透射电子显微镜(TEM)、紫外-可见吸收光谱和荧光光谱对CdSe/ZnS量子点进行表征。在反应时间为5 min条件下,乙酰甲胺磷的浓度在0.487×10~(-6)～7.225×10~(-6) mol/L范围内与CdSe/ZnS量子点的荧光猝灭强度比值呈良好的线性关系(R~2=0.9987),方法检出限为2.55×10~(-7) mol/L。在2.0、5.0μmol/L加标水平下的回收率为94.5%～102.8%,相对标准偏差(RSD,n=5)小于4%。该方法选择性好,灵敏度高,可用于水果和蔬菜中农药乙酰甲胺磷的快速检测。     

基于CdSe/ZnS量子点构建多巴胺荧光检测方法的研究

以CdSe/ZnS量子点为荧光探针,基于多巴胺对CdSe/ZnS量子点的荧光猝灭效应,建立了一种可快速测定多巴胺的荧光检测方法。在最优实验条件下(pH7.4,反应时间20min),多巴胺浓度在0.01~0.7μmol/L范围内与CdSe/ZnS量子点的荧光猝灭强度比值呈良好的线性关系(r=0.996),方法检出限为1.6×10-4μmol/L,相对标准偏差为1.2%。与文献报道的方法相比,该方法的检出限更低,更为灵敏,可用于多巴胺注射液及人体尿样中多巴胺的快速检测。     

水溶性CdTe量子点荧光法测定青霉素的研究

以巯基乙酸为稳定剂合成水溶性CdTe量子点(QDs),利用CdTe QDs荧光猝灭-恢复技术,建立了一种测定青霉素的新方法。考察了不同缓冲溶液、pH值、Co2+浓度等因素对体系的影响。结果表明,在pH=10的硼砂缓冲溶液中,Co2+能猝灭CdTe QDs的荧光,体系中加入青霉素后,CdTe QDs的荧光得到恢复且恢复强度与青霉素的浓度呈良好的线性关系,方法的线性范围为2.0×10-5~1.0×10-4 mol/L,检出限为2.2×10-6 mol/L,应用于实际样品测定,结果较好。     

CdTe量子点的制备及其与Au(Ⅲ)的作用

以金属铝作为还原剂,制备(NH4)2Te前体,合成了水溶性荧光CdTe量子点(QDs),该QDs在紫外光照射下有较强的荧光且发射波长可调谐,并可稳定放置.计算了发射峰位置在575 nm CdTe QDs的粒径为2.82 nm,与TEM图像进行对比,计算了量子产率为28%;讨论了在不同的实验条件下,Au(Ⅲ)对CdTe QDs的荧光猝灭,Au(Ⅲ)的浓度在2.1×10-8～6.0×10-7 mol·L-1与荧光猝灭值呈线性关系,线性方程为△F=0.0903+1.713c,r=0.9984,检出限为9.4×10-9 mol·L-1.     

基于CdSe/ZnS量子点构建丝裂霉素荧光检测体系的研究

建立了一种基于CdSe/ZnS量子点的快速、高效的检测丝裂霉素的荧光方法。pH=7.4,反应10 min,CdSe/ZnS量子点的荧光随丝裂霉素浓度增加而猝灭,量子点的荧光强度与丝裂霉素的浓度呈良好的线性关系,适用于丝裂霉素浓度1.8~60 μmol/L,且相关系数为0.996,丝裂霉素的检测限为0.11 μmol/L,该方法相对无共存物质的干扰,并证明完全适用于丝裂霉素注射液与尿液中丝裂霉素的测定。     

CdSe量子点的合成及标记胃蛋白酶的研究

以硒粉及镉盐为反应前体,通过固相/液相沉淀反应及室温乙二胺溶剂体系两种方法合成了平均粒径为8～10nm的CdSe量子点,以巯基乙酸修饰量子点使之可溶,并标记胃蛋白酶。CdSe量子点在350和380nm附近有明显尖锐的紫外吸收,有481.6nm的荧光带边发射,标记胃蛋白酶后,紫外吸收峰位不变而吸光度增强,荧光峰位蓝移至467.2nm,荧光强度降低。在最佳实验条件下,胃蛋白酶浓度在5～50mg/L范围内与荧光降低值之间呈线性关系;检出限(3σ)为0.36mg/L(n=10),方法已用于人体胃液胃蛋白酶的测定。     

基于Mn掺杂ZnS量子点的室温磷光猝灭法测定H2O2

以N-乙酰基-L-半胱氨酸为稳定剂,合成了具有独特光学性质的水溶性Mn掺杂ZnS量子点(QDs)。该量子点在室温不除氧的条件下即可发射较强的磷光信号,最大发射波长位于592nm处。在pH=7.0的磷酸盐缓冲溶液中,H2O2对量子点有显著的磷光猝灭作用,且在一定的范围内H2O2的浓度与磷光猝灭值(P0/P)呈现良好的线性关系,以此建立了测定H2O2的新方法。在最佳的实验条件下,该方法的检出限为1.0×10-6 mol/L,线性范围为1.0×10-5～2.5×10-2 mol/L,相关系数为0.9978。通过测定猝灭过程的时间分辨磷光光谱,推断猝灭机理为动态猝灭。     

巯基化壳聚糖包覆CdS量子点荧光猝灭法测定环境水样中的Hg~(2+)

合成了新型巯基化壳聚糖,并采用一步法合成了巯基化壳聚糖包覆的水溶性CdS量子点(QDs)。结果表明制备的巯基化壳聚糖包覆CdS QDs粒径均匀,该量子点在水溶液中稳定性好并且Hg2+对其荧光具有明显的猝灭作用。在最佳测定条件下,标准曲线的线性范围为3.0×10-7~5.0×10-5 mol/L,检出限为5.3×10-8 mol/L,且方法抗干扰性好,日内及日间精密度在5.8%之内。该方法应用于实际水样检测,回收率在86.4%~104.6%之间。     

基于L-半胱氨酸功能化的MoS_2荧光量子点检测Hg~(2+)

本文采用水热法,以Na_2MoO_4为钼源,L-半胱氨酸作为硫源及稳定剂,合成荧光二硫化钼量子点(MoS2QDs),利用紫外-可见光谱、荧光光谱和红外光谱对量子点的结构和性能进行了表征。所合成MoS2QDs呈现较强蓝色荧光的性能,并具有较好的分散性。MoS_2QDs作为探针与Hg~(2+)作用后产生荧光猝灭现象,由此建立了一种测定Hg~(2+)的荧光分析新方法。该方法对Hg~(2+)测定的线性范围是5.0×10-7~2.0×10-4 mol/L,检测限为2.3×10-7 mol/L,相关系数为0.998。该方法具有操作简单、灵敏度高和选择性好等特点,可用于自来水水样中痕量Hg~(2+)的测定。     

Preparation and characterization of thiacalix[4]arene coated water-soluble CdSe/ZnS quantum dots as a fluorescent probe for Cu2+ ions

Highly fluorescent water-soluble CdSe/ZnS (core/shell) quantum dots (QDs) as a fluorescent Cu2+ ion probe were synthesized using thiacalix[4]arene carboxylic acid (TCC) as a surface coating agent. Hydrophobic trioctylphosphine oxide (TOPO) capped CdSe/ZnS QDs were overcoated with TCC in tetrahydrofuran at room temperature, and deprotonation of the carboxyl groups of TCC resulted in the formation of water-soluble QDs. The surface structure of the QDs was characterized by using transmission electron microscopy (TEM) and fluorescence correlation spectroscopy (FCS). TEM images showed that TCC-coated QDs were monodispersed with the particle size (core-shell moiety) of approximately 5 nm. Hydrodynamic diameter of the TCC-coated QDs was determined to be 8.9 nm by FCS, showing that the thickness of the surface organic layer of the QDs was approximately 2 nm. These results indicate that the surface layer of TCC-coated QDs forms a bilayer structure consisting of TOPO and TCC molecules. TCC-coated CdSe/ZnS QDs were highly fluorescent (quantum yield, 0.21) compared to the QDs surface-modified with mercaptoacetic acid and mercaptoundecanoic acid. Fluorescence of the TCC-coated QDs was effectively quenched by Cu2+ ions even in the presence of other transition metal ions such as Cd2+, Zn2+, Co2+, Fe2+, and Fe3+ ions in the same solution. The Stern-Volmer plot for the fluorescence quenching by Cu2+ ions showed a linear relationship up to 30 microM of Cu2+ ions. The ion selectivity of TCC-coated QDs was determined by measurements of fluorescence responses towards biologically important transition metal ions (50 microM) including Fe2+, Fe3+, Co2+>Zn2+, Cd2+. The fluorescence of TCC-coated QDs was almost insensitive to other biologically important ions such as Na+, K+, Mg2+, and Ca2+, suggesting that TCC-coated QDs can be used as a fluorescent Cu2+ ion probe for biological samples. A possible quenching mechanism by Cu2+ ions was also discussed on the basis of a Langmuir-type adsorption isotherm.     

Imaging pancreatic cancer using surface-functionalized quantum dots

In this study, CdSe/CdS/ZnS quantum dots (QDs) were used as optical contrast agent for imaging pancreatic cancer cells in vitro using transferrin and anti-Claudin-4 as targeting ligands. CdSe/CdS/ZnS was chosen because the CdSe/CdS/ZnS QDs have better photoluminescence (PL) efficiency and stability than those of CdSe/ZnS. The transferrin-mediated targeting is demonstrated in both a cell-free coprecipitation assay as well as using in vitro confocal microscopy. Pancreatic cancer specific uptake is also demonstrated using the monoclonal antibody anti-Claudin-4. This targeted QD platform will be further modified for the purpose of developing as an early detection imaging tool for pancreatic cancer.     

水溶性的CdSe/CdS/ZnS量子点的合成及表征

用L-半胱氨酸盐(Cys)作为稳定剂,合成了水溶性的双壳结构的CdSe/CdS/ZnS半导体量子点。吸收光谱和荧光光谱结果表明,双壳结构的CdSe/CdS/ZnS纳米微粒比单一的CdSe核纳米粒子和单核壳结构的CdSe/CdS纳米粒子具有更优异的发光特性。用透射电子显微镜(TEM)、ED、XRD、XPS和FTIR等方法对CdSe核和双壳层的CdSe/CdS/ZnS纳米微粒的结构、分散性及形貌分别进行了表征。     

Long-term exposure to CdTe quantum dots causes functional impairments in live cells

Several studies suggested that the cytotoxic effects of quantum dots (QDs) may be mediated by cadmium ions (Cd2+) released from the QDs cores. The objective of this work was to assess the intracellular Cd2+ concentration in human breast cancer MCF-7 cells treated with cadmium telluride (CdTe) and core/shell cadmium selenide/zinc sulfide (CdSe/ZnS) nanoparticles capped with mercaptopropionic acid (MPA), cysteamine (Cys), or N-acetylcysteine (NAC) conjugated to cysteamine. The Cd2+ concentration determined by a Cd2+-specific cellular assay was below the assay detection limit (<5 nM) in cells treated with CdSe/ZnS QDs, while in cells incubated with CdTe QDs, it ranged from approximately 30 to 150 nM, depending on the capping molecule. A cell viability assay revealed that CdSe/ZnS QDs were nontoxic, whereas the CdTe QDs were cytotoxic. However, for the various CdTe QD samples, there was no dose-dependent correlation between cell viability and intracellular [Cd2+], implying that their cytotoxicity cannot be attributed solely to the toxic effect of free Cd2+. Confocal laser scanning microscopy of CdTe QDs-treated cells imaged with organelle-specific dyes revealed significant lysosomal damage attributable to the presence of Cd2+ and of reactive oxygen species (ROS), which can be formed via Cd2+-specific cellular pathways and/or via CdTe-triggered photoxidative processes involving singlet oxygen or electron transfer from excited QDs to oxygen. In summary, CdTe QDs induce cell death via mechanisms involving both Cd2+ and ROS accompanied by lysosomal enlargement and intracellular redistribution.     

Optical properties of CdSe and CdSe/ZnS quantum dots dispersed in solvents of different polarity

Original organic capping TOPO/TOP groups of CdSe and CdSe/ZnS quantum dots (QDs), from mother solution were replaced with 2_mercaptoethanol, which was chosen as model compound, in order to achieve water solubility. Obtained water dispersions of CdSe and CdSe/ZnS QDs were characterized by UV/VIS absorption and luminescence techniques. Luminescence measurements revealed that bare cores are very sensitive to surface capping, transfer into water diminished emission intensity. Core/shell, CdSe/ZnS, QDs are much more resistant to changes of the capping and solvent, and significant part of emission intensity was preserved in water. The article is published in the original.     

Electrochemiluminescence resonance energy transfer between quantum dots (QDs) as the donor and Cy5 dye molecules as the acceptor in QD-Cy5 conjugates with biomolecules as the linker

Electrochemiluminescence resonance energy transfer (ECRET) between CdSe/Zns quantum dots (QDs) as the donor and cyanine dye (Cy5) molecules as the acceptor in QD-Cy5 conjugates with DNA or protein as the linker was reported. When a negative potential was applied, the excited-state CdSe/ZnS* was produced in 0.1 mol/L phosphate buffer (pH 7.4) containing 0.1 mol/L K₂S₂O₈ and 0.1 mol/L KNO₃ (PB-K₂S₂O₈). The CdSe/ZnS* went back to the ground-state CdSe/ZnS to emit light at 590 nm or to transfer energy to proximal ground-state Cy5 molecules. The resultant excited-state Cy5 molecules relaxed to their ground state by emitting a light at 675 nm. The ECRET between QDs and Cy5 was used to evaluate interactions between DNAs and to measure conformational changes of DNAs and proteins.     

Forming water-soluble CdSe/ZnS QDs using amphiphilic polymers, stearyl methacrylate/methylacrylate copolymers with different hydrophobic moiety ratios and their optical properties and stability

The amphiphilic stearyl methacrylate/methylacrylic acid copolymers (PSMs) were used as phase transfer reagents to convert CdSe/ZnS core-shell quantum dots (QDs) in chloroform to water-soluble PSMs-coated quantum dots (PSM-QDs). The optical properties and stability of PSM-QDs were influenced by the hydrophobic moiety ratios of PSMs, the PSM/QDs mass/volume ratio and the reaction time. The resulting PSM-QDs on optimum reaction conditions retained 60% of the photoluminescence value of the original CdSe/ZnS QDs in chloroform. The carboxylate-based PSM-QDs survived UV irradiation in air for at least 15 days. Upon UV irradiation, the PSM-QDs became about 2 times brighter than the original CdSe/ZnS QDs in chloroform, and the UV-brightened PL can retain the brightness for at least several months. Experimental results further confirmed the stability of PSM-QDs against strong acid, photochemical and thermal treatments. In addition to good performance of PSM-QDs, the synthesis of PSM and the corresponding water-soluble QDs is relatively simple.     

Effect of linker on the photosensitization of ZnO layers with CdSe quantum dots

In this work, zinc oxide (ZnO) nanoparticles (size <10 nm) were formed via precipitation in ethanolic solution. The zinc acetate and lithium hydroxide solutions in ethanol were mixed at 273 K temperatures under vigorous stirring. To study the effect of quantum dot (QD) coverage, we have prepared a colloidal suspension of capped CdSe QDs (size ~5 nm) by chemical route and anchored them to a nanoporous ZnO layer either by direct adsorption or through linker. Here a bifunctional molecule (mercaptopropionic acid, MPA, and thioglycolic acid, TGA) was previously adsorbed on the ZnO surface, which acted as a molecular cable. From TEM/SEM studies, it was observed that direct adsorption of CdSe QDs onto ZnO surface was not efficient. However, the bifunctional linker molecules particularly MPA facilitates binding of CdSe QDs to ZnO; and consequently, interparticle electron transfer is thus facilitated. The use of MPA linker despite of its long carbon chain also aids in the quenching of photoluminescence of CdSe on addition of ZnO in a more systematic manner indicating efficient charge transfer from CdSe into ZnO as compared with the without linker and with linker TGA case, respectively. Due to higher PL quenching and reduction in lifetime values, higher values of Stern–Volmer quenching constants were thus obtained for CdSe–ZnO composites with MPA as compared with TGA linker and without linker case, respectively. Nonlinear Stern–Volmer plots as observed for samples without linker case indicated heterogeneous quenching due to insufficient binding between CdSe QDs and ZnO. By means of spectroscopic (PL, UV–VIS, FTIR) and microscopic (TEM, SEM) techniques, we have demonstrated linker-dependent photosensitization mechanism of ZnO layers with CdSe QDs. Our data thus illustrate that interfacial-electron transfer kinetics in QD–linker–ZnO assemblies are almost independent of the length of alkyl-containing molecular linkers.     

Enhancing the device performance of a blue light‐emitting copolymer using CdSe/ZnS quantum dots

An alternating triarylamine‐functionalized fluorene‐based copolymer synthesized using a Suzuki–Miyaura cross‐coupling procedure is used as blue emitting layer in polymer light‐emitting diodes (PLEDs). Subsequently, the effects of CdSe/ZnS quantum dots (QDs) on the optoelectronic properties of the copolymer are investigated. Therefore, CdSe/ZnS QDs are embedded into the copolymer matrix and hybrid PLEDs are fabricated. The devices comprised of CdSe/ZnS QDs reveal enhanced performances, yielding about 3.4 times more luminous efficiency than that of the device without QDs. Further enhancement is achieved by using electron transport layer; the luminous efficiency rose from 0.065 to 1.740 cd A^?1 for the hybrid PLEDs, corresponding to a superb 27‐fold intensification of the efficiency. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 147–156     

基于石英纳米孔道的单颗粒尺寸分布分析

发展了一种基于石英纳米孔道的单颗粒电化学动态分析方法, 用于单个CdSe/ZnS量子点纳米颗粒的尺寸分布分析. 其机制是向石英纳米孔道两端施加电压, 表面带有正电荷的单个CdSe/ZnS量子点纳米颗粒在电场力驱动下由管内向管外运动, 当量子点纳米颗粒穿过纳米孔道尖端狭小的限域空间时, 其表面正电荷使石英纳米孔道内电荷密度增加, 孔道内的电化学限域效应进一步将电荷密度增加的信息放大并转变为可读的离子流增强信号. 通过对动态离子流信号解析可实时获取具有2种不同尺寸的量子点纳米颗粒所导致的2类过孔事件信息, 从而对在限域空间内运动的纳米颗粒进行尺寸分布分析.