CdS纳米晶与多肽分子相互作用研究

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.     

荧光CdS纳米晶的合成与表征

采用有机金属液相法,在较低温度下制备了高质量的荧光CdS纳米晶.TEM、UV-Vis、PL及XRD等研究表明,表面活性剂的浓度、反应时间及反应物配比等对所制备的CdS纳米晶的形貌与尺寸、光谱性能及结晶性能等具有显著的影响.控制合适的反应条件,可以获得单分散、光谱性能优异且结晶性好的CdS纳米晶.     

CdTe纳米晶与苯丙氨酸相互作用的研究

以巯基乙酸为稳定剂,在水相中合成了CdTe纳米晶,通过考察红外光谱、紫外光谱和光致发光光谱的变化,确定了苯丙氨酸(Phe)对CdTe纳米晶的光致发光效率以及稳定性的影响.结果表明苯丙氨酸与CdTe纳米晶之间存在着较强的相互作用,这种作用导致CdTe纳米晶的发光强度增大,稳定性增强,苯丙氨酸不仅是配位剂,它同时又起到了稳定剂的作用,并初步确认这种加强和稳定作用来自于苯丙氨酸和CdTe纳米晶之间所形成的配位键和静电作用以及苯丙氨酸与巯基乙酸之间形成的氢键.此外,苯丙氨酸的特殊结构对防止纳米晶的聚集有很大作用.     

表面修饰CdS和(CdS)ZnS纳米晶的性能研究

在水相中合成了CdS纳米微粒,以ZnS对其进行表面修饰,得到具有核壳结构的(CdS)ZnS水溶性纳米晶。采用红外光谱、X射线衍射(XRD)、透射电镜(TEM)表征其粒度和形貌,紫外-可见吸收光谱(UV)、荧光光谱表征其光学特性。制得的CdS近似呈球形,直径为8nm;CdS纳米颗粒表面经ZnS修饰后,其荧光发射峰强度显著增强,表面态发射减弱。     

聚合物-二氧化硅复合基材中CdS纳米晶的合成

本文报道在Sol-gel基材中制备由聚合物稳定的CdS纳米晶的新方法， 即通过甲基丙烯酸镉与甲基丙烯酸羟乙酯共聚合合成了含有Cd 2+的聚合物微凝胶, 在聚合物微凝胶网络中原位聚合正硅酸乙酯形成聚合物互穿的Sol-gel复合基材. 再向该聚合物/二氧化硅复合基材中通入H2S气体得到CdS纳米晶. 在聚合物网络中原位聚合正硅酸乙酯可以降低纯二氧化硅材料的脆性; 另一方面, 二氧化硅可以作为增强剂增加聚合物材料的强度. 因此, 在我们合成的聚合物/二氧化硅复合基材中制备的CdS纳米晶将具有很好的应用前景.     

低温固相反应法合成水分散性CdS纳米晶

A novel solid-state method for the preparation of the CdS nanoparticles at the room temperature has been developed. The nanoparticles were characterized with FT-IR, XRD, TEM, XPS and PL techniques. The results indicated that the surfaces of the CdS nanoparticles were modified with sodium thioglycollate and thus they were water-dispersive. The mean particle size was about 3～5 nm. A blue shift has been observed in the photoluminescence emission spectrum.     

功能性CdSe纳米晶的合成及自组装膜光致发光

以巯基丙酸(RSH)为稳定剂,采用湿化学法合成了功能性CdSe纳米晶,用XRD、TEM表征其粒度和形貌,用UV-Vis监测成核及成膜过程。结果表明：制得的CdSe近似呈球形,平均粒径为48 nm。利用静电自组装法层层组装成CdSe-PDDA复合膜,荧光测试表明：所得CdSe纳米晶自组装复合膜(CdSe-PDDA)的荧光强度随着组装层数的增加而呈线性增强,该复合膜在582 nm附近有黄绿色荧光发射。     

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.     

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…     

Cu2+掺杂CdS纳米晶的制备与表征

以巯基乙酸为稳定剂,采用水相合成法制备了Cu2+掺杂的CdS纳米晶. 分别用电感耦合等离子体发射光谱仪、原子力显微镜测试技术对样品的化学成分及形状进行分析表征,研究了掺杂CdS纳米晶的荧光激发与发射光谱. 实验结果表明,在样品制备过程的溶液中回流2 h后,组成为Cd0.99Cu0.01S的样品形状有棒状和粒状2种,Cu2+的掺入使得CdS纳米晶的荧光发射光谱红移,没有掺杂的样品在回流前的最大发射波长在520 nm处,而组成为Cd0.99Cu0.01S和Cd0.98Cu0.02S的样品在回流前的最大发射波长分别为595和610 nm,通过改变Cu与Cd摩尔比可调控CdS纳米晶的发射波长范围.     

溶剂热合成单分散硫化镉纳米晶

在双表面活性剂十八胺和油酸存在条件下, 以氯化镉和硫粉作为反应前驱物, 通过简单的溶剂热方法合成单分散性闪锌矿硫化镉纳米晶, 粒径大小在13 nm. 用X射线衍射(XRD)、透射电子显微镜(TEM)对产物的结构和形貌进行了表征, 同时对硫化镉纳米晶的紫外吸收谱和光致发光谱(PL)性能进行了表征. 实验结果表明合成的样品具有很好的发光性能, 此外溶剂热反应的温度对纳米晶的单分散性有重要影响. 并对硫化镉纳米晶的形成机理做了初步的研究.     

Study on Interaction between Chitosan and CdS Quantum Dots via Photoluminescence Spectra

The interaction between CdS quantum dots and amino polysaccharide chitosan in aqueous solution was studied via photoluminescence (PL) spectra.The surface binding of chitosan with different molecular weight (MW) quenched the luminescence of QDs due to the elimination of radioactive anion vacancy centers.This process fits well with the Perrin model;lower MW chitosan exhibits higher quenching efficiency due to better availability to the surface.     

表面缺陷与钯的沉积对硫化镉纳米晶粒的光催化制氢性能的影响

The development of the photocatalytic production of hydrogen from water splitting has attracted immense attention in recent years. CdS is a potential photocatalyst with a visible light response, though it still suffers from a limited activity for hydrogen production due to the fast recombination of photo-induced electron/hole pairs and the low reaction rate of hydrogen evolution on the surface. Studies on the effect of CdS surface structure and properties on hydrogen production are still very limited. In this work, we prepared three CdS nanocrystals with different morphologies: long rod, short rod, and triangular plate. The prepared samples were well characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface area analysis, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). From the results of TEM, XRD and XPS, we find that the three CdS nanocrystals with different morphologies were successfully synthesized. From the PL spectra, we conclude that the area of exposed nonpolar surface and degree of surface defects increase with an increase in aspect ratio. We also performed the photocatalytic hydrogen production reaction using the three CdS crystals. Long rod-like CdS (lr-CdS) exhibits the highest photocatalytic activity, with a hydrogen production rate of 482 μmol·h^-1·g^-1, which is 2.6 times that of short rod-like CdS (sr-CdS) (183 μmol·h^-1·g^-1) and 8.8 times that of triangular plate-like CdS (tp-CdS, 55 μmol h^-1·g^-1). It is found that lr-CdS shows a higher hydrogen production rate than sr-CdS and tp-CdS. We find that the hydrogen production rate is related to the degree of surface defects. Surface defects can trap the photo-induced electrons/holes, thus decreasing their probability of recombination. In addition, these defects can be used to anchor Pd particles to form a heterojunction structure that facilitates the separation of photo-induced charges. Therefore, we also compared three CdS/Pd nanocrystals synthesized with the three abovementioned morphologies with respect to hydrogen production. With 1% (w, mass fraction) Pd, the hydrogen production rate was greatly enhanced compared to all the CdS catalysts. Compared to the unpromoted CdS, the reaction rate is enhanced 43.1, 10.7 and 6.0 times over those of sr-CdS, lr-CdS and tp-CdS, respectively. Notably, the hydrogen production rate with short rod-like CdS/Pd reaches 7884 μmol·h^-1·g^-1, which can be favorably compared with the ever-increasing values reported in the literature. Hopefully, this work provides knowledge on the effect of crystal surface structure and properties on photocatalysis.     

Controllable synthesis of functionalized CdS nanocrystals and CdS/PMMA nanocomposite hybrids

We reported controllable synthesis of CdS nanocrystal-polymer transparent hybrids by using polymethylmethacrylate (PMMA) as a polymer matrix. In a typical run, the appropriate amounts of cadmium chloride (CdCl₂) and sodium sulfide (Na₂S) in the presence of 2-mercaptoethanol (ME) as the organic ligand are well dispersed in H₂O/DMF solution without any aggregation. From a combination of transmission electron microscopy (TEM) and a computing method of Brus’s model according UV-vis absorption spectra, the particle size of as-prepared hydroxyl-coated CdS nanocrystal was determined to be about 5 nm. Then, with the surface treatment with methacryloxypropyltrimethoxysilane (MPS), CdS-PMMA hybrids were obtained via free radical polymerization in situ. FT-IR characterization indicates the formation of robust bonding between CdS nanocrystals and the organic ligand and the formation of double-bond functional CdS nanocrystals. The TGA measurement displays CdS-PMMA hybrids possess better thermal stability compared with pure PMMA polymer. The fluorescence measurement shows that CdS nanocrystals and CdS-PMMA hybrids exhibit good optical properties. Also, the luminescent photographs taken under ultraviolet light prove the luminescence properties.     

Synthesis and Characterization of CdSe Nanocrystals Capped by CdS

CdSe semiconductor nanocrystals capped by CdS were synthesized in the aqueous solution with 2-mercaptoethanol as the stabilizer. The CdS capping with a higher band-gap than that of the core crystallite has successfully eliminated the surface traps. Optical absorption and fluorescence emission spectra were used to probe the effect of CdS passivation on the electronic structure of the nanocrystals. The composite CdSe/CdS nanocrystals exhibit strong, narrow(FWHM≤40 nm) and stable band-edge photoluminescence. X-ray powder diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy were used to analyze the composite nanocrystals and determine their average size, size distribution, shape, internal structure and elemental composition.     

微波萃取高效液相色谱法测定口红中芳香胺类化合物

利用微波萃取高效液相色谱法测定了口红中芳香胺类化合物.先将口红涂于玻璃片上,然后用微波萃取和高效液相色谱法测定萃取液中的芳香胺类化合物.研究了3种市售口红并得到了芳香胺类化合物的定量测定结果.考察了微波萃取的条件,并将薄层色谱等萃取分离方法和微波萃取法进行了比较,证明微波萃取法在萃取膏状物和蜡状物中的组分时,具有比其它方法更加方便、快速等优点.