CdS纳米晶与多肽相互作用研究

研究了半导体CdS纳米晶的表面功能化及荧光光谱特性,并利用静电/配位自组装方法实现了多肽和CdS纳米晶的生物无机偶联,研究了纳米晶多肽偶联体系的荧光光谱以及多肽与CdS纳米晶之间的相互作用.结果表明:含巯基多肽对CdS纳米晶表面形成完善包覆,消除CdS纳米晶表面缺陷,使CdS纳米晶荧光增强;含端氨基多肽使CdS纳米晶荧光出现先升后降趋势;其余不含巯基和氨基的多肽均猝灭CdS纳米晶荧光,猝灭机制属于形成化合物所引起的静态猝灭,它们的结合常数约为2×104,结合位点数约为0.87～1.00.     

表面富S2-的CdS量子点的合成及其与甲硝唑的作用

在冰水浴条件下,用柠檬酸三钠和六偏磷酸钠为稳定剂,通过控制较低浓度的氯化镉溶液和硫化钠溶液缓慢反应,合成了荧光稳定性好、表面富硫的水溶性CdS量子点。利用荧光光谱、紫外-可见吸收光谱和共振光散射光谱研究了CdS量子点与甲硝唑相互作用的光谱行为,发现甲硝唑与CdS富硫表面的过量S2-的结合引起量子点的荧光猝灭效应,甲硝唑对CdS荧光量子点的荧光猝灭为静态猝灭,它们主要以静电引力结合。     

碲化镉纳米晶溶液的荧光和共振瑞利散射特性及碲化镉纳米晶与氨基糖苷类抗生素相互作用

以氯化镉、碲氢化钾为原料,巯基乙酸钠为包裹剂水相合成了碲化镉纳米晶,通过透射电镜、高分辨透射电镜、能量色散谱、荧光光谱、紫外可见光谱、X射线衍射对碲化镉纳米晶进行了表征,所合成的纳米晶直径为5nm左右,属立方结构。碲化镉纳米晶溶液在制备后放置19d其荧光量子产率从初始的37％达到97％,而最大荧光发射波长（λem）从543nm移至510nm,蓝移33nm,而且在冰箱4℃可稳定至少10个月。同时碲化镉纳米晶溶液也具有一定的共振瑞利散射（RRS）,其最大散射峰位于554nm附近。研究了碲化镉纳米晶与硫酸阿米卡星和硫酸小诺霉素的相互作用对荧光和RRS的影响。结果表明：当两者反应形成结合产物时,将使纳米晶溶液荧光显著猝灭并使RRS明显增强,并且荧光猝灭作用和RRS增强在一定的范围内与药物的浓度成正比,对于硫酸阿米卡星和硫酸小诺霉素的检出限分别为3.4和2.6ng／mL（荧光猝灭法）及15.2和14.0ng／mL（RRS法）,方法具有高灵敏度。因此为用碲化镉纳米晶作荧光探针荧光猝灭法和RRS法测定氨基糖苷类药物创造了条件。     

CdTe/CdS量子点-蛋白质与头孢曲松钠的相互作用

以3-巯基丙酸为稳定剂,采用水热法合成了具有优异光学性质的CdTe/CdS核壳型量子点,量子产率为13.8%。量子点与牛血清白蛋白(BSA)偶联后荧光强度明显增大。通过测定荧光强度确定了偶联的最佳反应条件:pH7.4,反应温度37℃,反应时间40min。研究了溶液pH值和NaCl浓度对量子点及量子点-BSA溶液荧光强度的影响。对牛血清白蛋白测定的线性范围为1.1~19.5mg/L;检出限为0.47mg/L。头孢曲松钠对量子点-BSA的荧光有明显猝灭作用,荧光猝灭程度与其浓度有良好的线性关系。实验结果表明为静态猝灭,头孢曲松钠与BSA按1∶1结合,结合常数为6.31×103L/mol。用圆二色光谱技术探讨了其对BSA构象的影响。     

氧化石墨烯表面生长铕配合物纳米晶及其荧光性能研究

本文利用π-π堆积的方式在氧化石墨烯(GO)表面生长了Eu(Ⅲ)配合物纳米晶。傅立叶变换红外光谱(FTIR),透射电子显微镜(TEM),X-射线衍射(XRD)的表征证明,Eu(Ⅲ)配合物纳米晶成功地生长在氧化石墨烯表面。荧光光谱分析证明,复合材料具有一定的荧光性能,其中Eu³⁺的猝灭浓度为18wt%。热重分析显示,复合材料的热稳定性也比纯配合物有了明显的提高。     

氨基黑10B与牛血清白蛋白作用的光谱法研究

用紫外、荧光、圆二色光谱法研究了氨基黑10B与牛血清白蛋白(BSA)结合反应的光谱特性.结果表明氨基黑10B对牛血清白蛋白的荧光有猝灭作用,其猝灭类型属于静态猝灭;得到了不同温度下的结合常数和结合位点数;利用Gibbs-Helmholtz方程计算得到该猝灭反应的热力学参数,表明氨基黑10B主要以氢键和范德华力与BSA相互作用;圆二色和同步荧光光谱显示氨基黑10B对BSA构象产生了影响.     

Cu2＋和铜锌超氧化物歧化酶作用的光谱学研究

利用邻苯三酚自氧化法监测在磷酸盐缓冲体系中Cu^2＋对猪肝铜锌超氧化物歧化酶(CuZnSOD)活力的影响, 认为Cu^2＋与猪肝CuZnSOD存在直接相互作用. 通过荧光光谱方法研究了这种相互作用, 内源荧光的猝灭实验表明Cu^2＋与CuZnSOD形成1∶1型稳定配合物; 荧光猝灭的动力学分析表明配合物形成过程由两个独立步骤完成: 第一步是双分子快速缔合过程, 形成了结合疏松的配合物, 第二步是单分子慢速过程, 即松散的配合物“异构化”成为结合紧密的配合物. FTIR和CD证实相互作用过程伴随了蛋白分子构象的变化.     

低温水相合成巯基化聚乙烯醇/CdS量子点纳米复合物及用于测定环境水样中痕量Cu~(2+)

采用水相合成法,在低温N2气保护条件下,以巯基化聚乙烯醇(PVA)为基体材料合成一种环境友好型PVA/CdS量子点纳米复合物,并通过红外光谱(IR)、X射线粉末衍射(XRD)、透射电子显微镜(TEM)、热重(TG)、荧光光谱(PL)和紫外可见光谱(UV-Vis)等技术手段对复合物进行结构表征和光学性能研究。测试结果表明,复合物中CdS量子点为立方晶型结构,形状为球形,粒径小于5nm,具有很好的稳定性、分散性及发光性质。此外,Cu~(2+)对PVA/CdS水溶液荧光具有良好的猝灭作用,其荧光猝灭程度与Cu~(2+)浓度在1~1000nmol/L范围内呈良好的线性关系,线性相关系数为0.9923,方法检出限为0.12nmol/L。该纳米复合物荧光分析方法简便快速、灵敏度高、检出限低,已应用于实际黄河水样中痕量Cu~(2+)的分析与检测。     

Cu2＋和铜锌超氧化物歧化酶作用的光谱学研究

利用邻苯三酚自氧化法监测在磷酸盐缓冲体系中Cu^2＋对猪肝铜锌超氧化物歧化酶(CuZnSOD)活力的影响, 认为Cu^2＋与猪肝CuZnSOD存在直接相互作用. 通过荧光光谱方法研究了这种相互作用, 内源荧光的猝灭实验表明Cu^2＋与CuZnSOD形成1∶1型稳定配合物; 荧光猝灭的动力学分析表明配合物形成过程由两个独立步骤完成: 第一步是双分子快速缔合过程, 形成了结合疏松的配合物, 第二步是单分子慢速过程, 即松散的配合物“异构化”成为结合紧密的配合物. FTIR和CD证实相互作用过程伴随了蛋白分子构象的变化.     

金纳米颗粒表面能量转移及巯基化合物的检测

二氧化硅稳定的金纳米颗粒(Au-SiO₂)与罗丹明B之间发生表面能量转移,使罗丹明B荧光猝灭。 金纳米颗粒对罗丹明B的Stern-Volmer猝灭常数为4.3×10³ L/mol。 当荧光猝灭的混合体系中加入巯基化合物时,巯基化合物与金纳米颗粒发生强相互作用阻断罗丹明B-金纳米颗粒之间的能量转移,罗丹明B荧光恢复。 基于罗丹明B-Au-SiO₂体系对巯基化合物的单一响应,建立了一种简单快速检测巯基化合物的方法;并且由于二氧化硅对金纳米颗粒的稳定作用,金纳米颗粒成为一种可以回收利用的检测探针。     

CdTe纳米晶与蛋白相互作用研究

当半导体纳米晶的直径小于其电子的玻尔直径时 ,半导体纳米晶对电子具有量子限域效应 ,其发光波长与纳米晶的尺寸相关 .与有机荧光分子相比 ,荧光半导体纳米晶具有以下优点 :(1 )其激发谱在吸收阈值以上几乎是连续的 ,利于多波长激发 ;(2 )高强荧光发射 ,谱峰窄 ,峰形对称 ;(3 )发射波长随着粒径的增大而有规律地红移 ,只需改变粒径即可获得多色发光 ;(4)纳米晶的发光稳定性好 ,不易被光分解和漂白 .因此 ,半导体纳米晶作为新一代荧光生物标记物已有研究[1～ 6] .荧光生物标记要求使用水溶性的纳米粒子 ,水相合成半导体纳米晶操作简便、重复…     

Fluorescence for the ultrasensitive detection of peptides with functionalized nano-ZnS

The fluorescence emitted by the functionalized ZnS nanocrystal at 440 nm could be efficiently enhanced or quenched when various peptides were added. The mechanism of the fluorescence enchancement and quenching of ZnS nanocrystals was discussed. The binding constant and numbers of binding sites was obtained from the Scatchard plot. The change of fluorescence intensity was in proportion to the concentration of peptides. The limits of detection were in range of 0.011-0.028 μg mL⁻¹. Application results to synthetic samples showed simplicity, rapidity, high sensitivity and satisfactory reproducibility of the presented method. Measurements of real samples also give satisfactory results which were in good agreement with those obtained using high performance liquid chromatograph (HPLC) and liquid chromatograph-mass spectrograph (LC-MS) methods.     

Preparation and application of L-cysteine-modified CdSe/CdS core/shell nanocrystals as a novel fluorescence probe for detection of nucleic acid

The water-soluble L-cysteine-modified CdSe/CdS core/shell nanocrystals (expressed as CdSe/CdS/Cys nanocrystals) have been synthesized in aqueous by using L-cysteine as stabilizer. The size, shape, component and spectral property of CdSe/CdS/Cys nanocrystals were characterized by high-resolution transmission electron microscope (HRTEM), energy dispersive X-ray fluorescence (EDX), infrared spectrum (IR) and photoluminescence (PL). The results showed that the spherical CdSe/CdS/Cys nanocrystals with an average diameter of 2.3 nm have favorable fluorescent property, theirs photostability and fluorescence intensity are enhanced greatly after overcoating with CdS. The cysteine modified on the surface of core/shell CdSe/CdS nanocrystals renders the nanocrystals water-soluble and biocompatible. Based on the fluorescence quenching of the nanocrystals in the presence of calf thymus deoxyribonucleic acid (ct-DNA), a fluorescence quenching method has been developed for the determination of ct-DNA by using the nanocrystals as a novel fluorescence probe. The pH value of the system was selected at pH 7.4, with excitation and emission wavelength at 380 and 522 nm, respectively. Under the optimal conditions, the fluorescence quenching intensity of the system is linear with the concentration of ct-DNA in the range of 0.1-3.5 microg/mL (r=0.9987). The detection limit is 0.06 microg/mL. And two synthetic samples were analyzed satisfactorily.     

One-pot synthesis of high-quality zinc-blende CdS nanocrystals

This paper reports a one-pot synthetic method for producing CdS nanocrystals. We have demonstrated that the nanocrystal nucleation and growth stages can be automatically separated in a homogeneous system with the presence of nucleation initiators. Accelerators used for more than 70 years in rubber vulcanization (i.e., tetraethylthiuram disulfides, and 2,2'-dithiobisbenzothiazole) were found to be effective nucleation initiators for CdS nanocrystal synthesis. The as-prepared CdS nanocrystals are highly monodisperse and possess a zinc blende crystal structure. The quantum yield of the band-gap photoluminescence is up to 12% when the surface-trap emission was totally eliminated after a gentle oxidation under laboratory fluorescent light.     

Bioactivation and cell targeting of semiconductor CdSe/ZnS nanocrystals with phytochelatin-related peptides

Synthetic phytochelatin-related peptides are used as an organic coat on the surface of colloidal CdSe/ZnS semiconductor nanocrystals synthesized from hydrophobic coordinating trioctyl phosphine oxide (TOPO) solvents. The peptides are designed to bind to the nanocrystals via a C-terminal adhesive domain. This adhesive domain, composed of multiple repeats of cysteines pairs flanked by hydrophobic 3-cyclohexylalanines, is followed by a flexible hydrophilic linker domain to which various bio-affinity tags can be attached. This surface coating chemistry results in small, buffer soluble, monodisperse peptide-coated nanoparticles with high colloidal stability and ensemble photophysical properties similar to those of TOPO-coated nanocrystals. Various peptide coatings are used to modulate the nanocrystal surface properties and to bioactivate the nanoparticles. CdSe/ZnS nanocrystals coated with biotinylated peptides efficiently bind to streptavidin and are specifically targeted to GPI-anchored avidin-CD14 chimeric proteins expressed on the membranes of live HeLa cells. This peptide coating surface chemistry provides a novel approach for the production of biocompatible photoluminescent nanocrystal probes.     

单分散CdS纳米晶/PNIPAM复合水凝胶的制备及其温敏荧光特性

采用液体-固体-溶液法(LSS)制备单分散CdS纳米晶;通过自由基聚合制备单分散CdS纳米晶/聚N-异丙基丙烯酰胺(CdS/PNIPAM)复合温敏水凝胶.采用HRTEM、XRD、FTIR、DSC、PL等对CdS纳米晶、CdS/PNIPAM温敏复合凝胶的微观结构与性能进行了表征,变温荧光光谱研究了温度对凝胶荧光性能的影响.结果表明,CdS纳米晶粒径约为2.8 nm,单分散性良好;复合凝胶的荧光发射强度与环境温度存在一定的关联性,且呈可逆性.     

A new two-phase route to high-quality CdS nanocrystals

A new two-phase route has been developed to synthesize high-quality CdS nanocrystals with a narrow size distribution and a high photoluminescence (PL) quantum yield (QY). In the two-phase system, toluene and water were used as separate solvents for cadmium myristate (CdM2) and thiourea, which served as cadmium source and sulfur source, respectively, and oleic acid (OA) was used as a ligand for stabilizing the nanocrystals. The reactions were completed in the heated autoclaves. The initial Cd/S molar ratio of the precursors and the reaction temperature were found to be factors that affected the growth of nanocrystals. Furthermore, a seeding-growth technique was developed to synthesize CdS nanocrystals of different sizes, which exhibit PL peaks with quite similar full width at half-maximum (FWHM) values compared to those of the initial nanocrystal seeds in all cases.     

Highly luminescent, stable, and water-soluble CdSe/CdS core-shell dendron nanocrystals with carboxylate anchoring groups

A dendron ligand with two carboxylate anchoring groups at its focal point and eight hydroxyl groups as its terminal groups was found to efficiently convert as-synthesized CdSe/CdS core-shell nanocrystals in toluene to water-soluble dendron-ligand stabilized nanocrystals (dendron nanocrystals). The resulting dendron nanocrystals retained 60% of the photoluminescence value of the original CdSe/CdS core-shell nanocrystals in toluene and were significantly brighter than the similar dendron nanocrystals with thiolate (deprotonated thiol group) as the anchoring group which retained just 10% of the photoluminescence value of the original CdSe/CdS core-shell nanocrystals in toluene. The carboxylate-based dendron nanocrystals survived UV irradiation in air for at least 13 days, about 9 times better than the thiolate-based dendron nanocrystals (35 h) and similar to that of the thiolate-based dendron-box stabilized CdSe/CdS core-shell nanocrystals (box nanocrystals). Upon UV irradiation, the dendron nanocrystals became even 2 times brighter than the original CdSe/CdS core-shell nanocrystals in toluene, and the UV-brightened PL can retain the brightness for at least several months. These stable and bright dendron nanocrystals were soluble in various aqueous media, including all common biological buffer solutions tested, for at least 1.5 years. In addition to their superior performance, the synthetic chemistry of carboxylate dendron ligands and the corresponding dendron nanocrystals is relatively simple and with high yield.     

Influence of surface modification on the luminescence of colloidal ZnO nanocrystals

The influence of surface modification on the luminescence of colloidal ZnO nanocrystals is described, with particular emphasis given to factors increasing excitonic emission quantum yields. Changes in nanocrystal size, shape, and luminescence intensities have been measured for nanocrystals capped by dodecylamine (DDA) and trioctylphosphine oxide after different growth times. Green trap emission intensities show a direct correlation with surface hydroxide concentrations. Contrary to expectations, there is no direct correlation between excitonic emission quenching and surface hydroxide concentrations. The nearly pure excitonic emission observed after heating in DDA is attributed to the removal of surface defects from the ZnO nanocrystal surfaces and to the relatively high packing density of DDA on the ZnO surfaces. Rapid, nondispersive ripening of ZnO nanocrystals upon heating in DDA is observed and explained using a colloidal growth model.     

Enhancing the photoluminescence of peptide-coated nanocrystals with shell composition and UV irradiation

The composition and structure of inorganic shells grown over CdSe semiconductor nanocrystal dots and rods were optimized to yield enhanced photoluminescence properties after ligand exchange followed by coating with phytochelatin-related peptides. We show that, in addition to the peptides imparting superior colloidal properties and providing biofunctionality in a single-step reaction, the improved shells and pretreatment with UV irradiation resulted in high quantum yields for the nanocrystals in water. Moreover, peptide coating caused a noticeable red-shift in the absorption and emission spectra for one of the tested shells, suggesting that exciton-molecular orbital (X-MO) coupling might take place in these hybrid inorganic-organic composite materials.