硫化镉纳米微粒与某些氨基糖苷类抗生素相互作用的共振瑞利散射光谱及其分析应用

在pH为2.0～7.0的水溶液中,硫化镉纳米微粒[(CdS)n]与氨基糖苷类抗生素阿米卡星(AMK)、卡那霉素(KANA)、妥布霉素(TOB)和庆大霉素(GEN)借静电引力、疏水作用力结合,形成粒径更大的聚集体,导致共振瑞利散射(RRS)的增强并产生新的RRS光谱,最大RRS峰位于289 nm(AMK体系)、291 nm(KANA和TOP体系)和287 nm(GEN体系).在一定条件下,RRS散射强度(△I)均与药物的浓度成正比,反应具有高灵敏度,对于4种药物的检出限在7.7～8.8 ng/mL之间.其中(CdS)n-AMK体系灵敏度最高,对AMK的检出限为7.7 ng/mL.据此发展了一种用纳米硫化镉作探针,灵敏、简便、快速测定氨基糖苷类抗生素药物的共振瑞利散射新方法.     

硫化镉纳米微粒与某些氨基糖苷类抗生素相互作用的共振瑞利散射光谱及其分析应用

在pH为2.0～7.0的水溶液中,硫化镉纳米微粒[（CdS）n]与氨基糖苷类抗生素阿米卡星（AMK）、卡那霉素（KANA）、妥布霉素（TOB）和庆大霉素（GEN）借静电引力、疏水作用力结合,形成粒径更大的聚集体,导致共振瑞利散射（RRS）的增强并产生新的RRS光谱,最大RRS峰位于289 nm（AMK体系）、291 nm（KANA和TOP体系）和287 nm（GEN体系）.在一定条件下,RRS散射强度（ΔI）均与药物的浓度成正比,反应具有高灵敏度,对于4种药物的检出限在7.7～8.8 ng/mL之间.其中（CdS）n-AMK体系灵敏度最高,对AMK的检出限为7.7 ng/mL.据此发展了一种用纳米硫化镉作探针,灵敏、简便、快速测定氨基糖苷类抗生素药物的共振瑞利散射新方法.     

纳米锑掺杂氧化锡水悬液分散稳定性研究

通过测定纳米锑掺杂氧化锡(Antimony doped Tin Oxide, ATO)水分散液的纳米粒子粒径分布、沉降性能、黏度、以及Zeta电位等,探讨了黏度、纳米ATO粒子的粒径分布、粒子Zeta电位、分散剂的类型对悬液分散稳定性的影响.结果表明,悬液的黏度、粒子粒径分布以及Zeta电位间具有良好的相关性;同时发现以聚乙烯吡咯烷酮/十六烷基三甲基溴化铵(Poly(vinylpyrrolidine)/cetyltrimethyl-ammonium bromine,PVP/CTAB)作为复合分散剂时,在pH<3.0时也能得到黏度低、粒径小、分散稳定的纳米ATO悬液.     

发光细菌法检测不同形状CdS纳米材料毒性

采用发光细菌法考察了纳米材料的形状对其毒性的影响.通过对硫化镉(CdS)量子点、米粒状的硫化镉棒以及多臂硫化镉棒毒性的评价,发现多臂硫化镉棒在三者中尺寸最大,毒性最大;而粒径最小的硫化镉量子点毒性最小.实验证实,这3种硫化镉纳米粒子均可进入细菌,产生不同的毒性.紫外照射和维生素C实验证明了这几种硫化镉纳米材料的毒性差异与其形状有关,其原因在于不同形状的纳米粒子对细胞膜具有不同的刺伤能力.     

基于反相微乳液法的尺寸可控性二氧化硅基于反相微乳液法的尺寸可控性二氧化硅纳米颗粒制备研究

通过考察水与表面活性剂的摩尔比(R),TEOS的量、氨水的量及包壳次数对基于Triton X 100/环已烷/正已醇/水反相微乳液体系制备二氧化硅纳米颗粒尺寸的影响,开展了基于反相微乳液法的尺寸可控性二氧化硅纳米颗粒制备研究.结果表明:在其他参数都恒定的情况下,通过改变微乳液体系中上述某一组分的量,可以在一定程度上实现二氧化硅纳米颗粒的尺寸可控性合成.首先,水与表面活性剂的摩尔比(R)对二氧化硅纳米颗粒的尺寸影响最大,随着R值的增大,颗粒的粒径逐渐减小,当R值达到18时,二氧化硅纳米颗粒的形貌变得不再是很规则的球形结构,并且分散性降低,团聚现象明显;其次是氨水的量,随着氨水量的增多,颗粒的粒径先减小,之后不再发生明显变化;另外随着包壳次数的增多,颗粒的粒径随之增大,并且颗粒之间的分散性也有所提高;但是TEOS的量对颗粒粒径的影响不明显.     

海藻酸钠修饰的水溶性壳聚糖药物载体

[目的]改善水溶性壳聚糖（WSC）作为蛋白药物载体的作用。[方法]采用离子交联法制备海藻酸钠修饰的WSC纳米粒子并测定粒子的TEM、粒径和zeta-电位。[结果]WSC、负载BSA的WSC以及海藻酸钠修饰的WSC纳米粒子均呈球状,纳米粒子的粒径基本在200 nm以内,WSC和海藻酸钠修饰的WSC纳米粒子的粒径较小,在100 nm左右;而负载BSA的WSC粒子的粒径较大,在200 nm左右。当海藻酸钠浓度从0.1 mg/m l增大到0.3 mg/m l时,WSC纳米粒子的BSA负载率从32%增加到94%,载药量从4.8%增加到24.0%。在3 d内,WSC和海藻酸钠修饰的WSC纳米粒子的BSA释放量分别是40%和13%。[结论]海藻酸钠与WSC之间产生了较强的化学交联作用,且海藻酸钠的修饰提高了WSC纳米粒子的药物负载能力。     

CdS量子点的水相合成及其荧光猝灭法测定铜离子

常温下在水溶液中制备了的以巯基乙酸修饰的CdS纳米溶胶,并用荧光光谱对其进行了表征。以修饰的纳米粒子为荧光探针,建立了荧光猝灭定量测定铜离子的方法。考察了不同缓冲体系、缓冲液pH值、纳米粒子浓度等多种因素的影响,在最佳实验条件下,测定铜离子的线性区间为16．7—83．3μL,检出限为0．29μL,该方法经济、简单、快速、灵敏度高、检出限比较低、检测范围比较宽。     

磁性靶向药物的制备与性能分析

采用化学共沉淀法制备磁性Fe3O4纳米粒子;用乳化-交联法制备环丙沙星磁性明胶微球;在高倍显微镜下观察微球粒径大小及形态,用紫外分光光度法检测微球中环丙沙星的含量;观察磁响应性;绘制药物微球体外释放曲线.结果显示:环丙沙星磁性明胶微球粒径40~58μm,在外加磁场的作用下动作距离为65~70 mm,微球载药率为16.5%,240 min.体外累积释放量为90%以上.说明环丙沙星磁性明胶微球成球性好,具有较好的磁响应性和一定缓释性,是一种较好的靶向药物.     

MoO2纳米球的水热合成与光催化性能

以钼酸铵为原料,在酸性条件下加入酒石酸作为辅助剂水热合成粒径小于10 nm的MoO2.对合成粉体进行XRD,SEM,TEM表征,讨论了合成粉体的结构与粒径,并探究了由MoO3纳米棒向MoO2纳米球转变的最佳制备条件,同时研究了MoO2纳米粒子的光催化性能.     

MoO2纳米球的水热合成与光催化性能

以钼酸铵为原料,在酸性条件下加入酒石酸作为辅助剂水热合成粒径小于10 nm的MoO2.对合成粉体进行XRD,SEM,TEM表征,讨论了合成粉体的结构与粒径,并探究了由MoO3纳米棒向MoO2纳米球转变的最佳制备条件,同时研究了MoO2纳米粒子的光催化性能.     

The role of particle morphology in interfacial energy transfer in CdSe/CdS heterostructure nanocrystals

Nanoscale semiconductor heterostructures such as tetrapods can be used to mimic light-harvesting processes. We used single-particle light-harvesting action spectroscopy to probe the impact of particle morphology on energy transfer and carrier relaxation across a heterojunction. The generic form of an action spectrum [in our experiments, photoluminescence excitation (PLE) under absorption in CdS and emission from CdSe in nanocrystal tetrapods, rods, and spheres] was controlled by the physical shape and resulting morphological variation in the quantum confinement parameters of the nanoparticle. A correlation between single-particle PLE and physical shape as determined by scanning electron microscopy was demonstrated. Such an analysis links local structural non-uniformities such as CdS bulbs forming around the CdSe core in CdSe/CdS nanorods to a lower probability of manifesting excitation energy-dependent emission spectra, which in turn is probably related to band alignment and electron delocalization at the heterojunction interface.     

Size Dependence of a First Order Solid-Solid Phase Transition: The Wurtzite to Rock Salt Transformation in CdSe Nanocrystals

Measurements of the size dependence of a solid-solid phase transition are presented. High-pressure x-ray diffraction and optical absorption are used to study the wurtzite to rock salt structural transformation in CdSe nanocrystals. These experiments show that both the thermodynamics and kinetics of this transformation are altered in finite size, as compared to bulk CdSe. An explanation of these results in the context of transformations in bulk systems is presented. Insight into the kinetics of transformations in both bulk and nanocrystal systems can be gained.     

n-Type conducting CdSe nanocrystal solids

A bottleneck limiting the widespread application of semiconductor nanocrystal solids is their poor conductivity. We report that the conductivity of thin films of n-type CdSe nanocrystals increases by many orders of magnitude as the occupation of the first two electronic shells, 1Se and 1Pe, increases, either by potassium or electrochemical doping. Around half-filling of the 1Se shell, a peak in the conductivity is observed, indicating shell-to-shell transport. Introducing conjugated ligands between nanocrystals increases the conductivities of these states to approximately 10(-2) siemens per centimeter.     

Quantum-confined stark effect in single CdSe nanocrystallite quantum dots

The quantum-confined Stark effect in single cadmium selenide (CdSe) nanocrystallite quantum dots was studied. The electric field dependence of the single-dot spectrum is characterized by a highly polarizable excited state ( approximately 10(5) cubic angstroms, compared to typical molecular values of order 10 to 100 cubic angstroms), in the presence of randomly oriented local electric fields that change over time. These local fields result in spontaneous spectral diffusion and contribute to ensemble inhomogeneous broadening. Stark shifts of the lowest excited state more than two orders of magnitude larger than the linewidth were observed, suggesting the potential use of these dots in electro-optic modulation devices.     

CdSe/ZnS量子点对雄性尼罗罗非鱼红细胞微核率及核异常率的影响

[目的]探究CdSe/ZnS量子点对尼罗罗非鱼(Oreochromis niloticus)的遗传毒性。[方法]分别设空白对照组、NaCl对照组和Cd2+对照组以及浓度分别为20、200、2 000和4 000 nmol/L 4个量子点处理组,以腹腔注射方式对雄性尼罗罗非鱼体进行暴露,暴露后1、4、7、14及28 d进行静脉取血制作血涂片,通过微核率、核异常率及总核异常率检测其遗传毒性。[结果]各NaCl对照组与空白对照组均无显著差异。暴露1 d后各量子点处理组产生的微核率达到峰值后总体呈下降趋势。Cd2+对照组的微核率在整个试验期间均与NaCl对照组有显著差异,其微核率14 d达到峰值。核质外凸和核质内凹是核异常的主要类型,核固缩及不均等缢裂细胞类型在前期易被诱导。[结论]量子点外壳及表面修饰基团的综合作用对鱼体有诱导微核率及核异常率增加的效应,但随着时间的推移,罗非鱼能逐步解除该负面效应,由此推测鱼体最终能解除由QDs诱导的遗传毒性。     

Linearly polarized emission from colloidal semiconductor quantum rods

Colloidal quantum rods of cadmium selenide (CdSe) exhibit linearly polarized emission. Empirical pseudopotential calculations predict that slightly elongated CdSe nanocrystals have polarized emission along the long axis, unlike spherical dots, which emit plane-polarized light. Single-molecule luminescence spectroscopy measurements on CdSe quantum rods with an aspect ratio between 1 and 30 confirm a sharp transition from nonpolarized to purely linearly polarized emission at an aspect ratio of 2. Linearly polarized luminescent chromophores are highly desirable in a variety of applications.     

Slow electron cooling in colloidal quantum dots

Hot electrons in semiconductors lose their energy very quickly (within picoseconds) to lattice vibrations. Slowing this energy loss could prove useful for more efficient photovoltaic or infrared devices. With their well-separated electronic states, quantum dots should display slow relaxation, but other mechanisms have made it difficult to observe. We report slow intraband relaxation (>1 nanosecond) in colloidal quantum dots. The small cadmium selenide (CdSe) dots, with an intraband energy separation of approximately 0.25 electron volts, are capped by an epitaxial zinc selenide (ZnSe) shell. The shell is terminated by a CdSe passivating layer to remove electron traps and is covered by ligands of low infrared absorbance (alkane thiols) at the intraband energy. We found that relaxation is markedly slowed with increasing ZnSe shell thickness.     

Hybrid nanorod-polymer solar cells

We demonstrate that semiconductor nanorods can be used to fabricate readily processed and efficient hybrid solar cells together with polymers. By controlling nanorod length, we can change the distance on which electrons are transported directly through the thin film device. Tuning the band gap by altering the nanorod radius enabled us to optimize the overlap between the absorption spectrum of the cell and the solar emission spectrum. A photovoltaic device consisting of 7-nanometer by 60-nanometer CdSe nanorods and the conjugated polymer poly-3(hexylthiophene) was assembled from solution with an external quantum efficiency of over 54% and a monochromatic power conversion efficiency of 6.9% under 0.1 milliwatt per square centimeter illumination at 515 nanometers. Under Air Mass (A.M.) 1.5 Global solar conditions, we obtained a power conversion efficiency of 1.7%.     

Size Dependence of Structural Metastability in Semiconductor Nanocrystals

The kinetics of a first-order, solid-solid phase transition were investigated in the prototypical nanocrystal system CdSe as a function of crystallite size. In contrast to extended solids, nanocrystals convert from one structure to another by single nucleation events, and the transformations obey simple unimolecular kinetics. Barrier heights were observed to increase with increasing nanocrystal size, although they also depend on the nature of the nanocrystal surface. These results are analogous to magnetic phase transitions in nanocrystals and suggest general rules that may be of use in the discovery of new metastable phases.     

Activation volumes for solid-solid transformations in nanocrystals

The transition between four- and six-coordinate structures in CdSe nanocrystals displays simple transition kinetics as compared with the extended solid, and we determined activation volumes from the pressure dependence of the relaxation times. Our measurements indicate that the transformation takes place by a nucleation mechanism and place strong constraints on the type of microscopic motions that lead to the transformation. The type of analysis presented here is difficult for extended solids, which transform by complicated kinetics and involve ill-defined domain volumes. Solids patterned on the nanoscale may prove to be powerful models for the general study of structural transitions in small systems, as well as in extended solids.