Electrochemiluminescence immunosensor based on CdSe nanocomposites

A novel strategy for the enhancement of electrochemiluminescence (ECL) was developed by combining CdSe nanocrystals (NCs), carbon nanotube-chitosan (CNT-CHIT), and 3-aminopropyl-triethoxysilane (APS). A label-free ECL immunosensor for the sensitive detection of human IgG (HIgG) was fabricated. The colloidal solution containing CdSe NCs/CNT-CHIT composite was first covered on the Au electrode surface to form a robust film, which showed high ECL intensity and good biocompatibility. After APS as a cross-linker was covalently conjugated to the CdSe NCs/CNT-CHIT film, the ECL intensity was greatly enhanced. And, an intensity about 20-fold higher than that of the CdSe NCs/CNT-CHIT film was observed. After antibody was bound to the functionalized film via glutaric dialdehyde (GLD), the modified electrode could be used as an ECL immunosensor for the detection of HIgG. The specific immunoreaction between HIgG and antibody resulted in the decrease in ECL intensity. The ECL intensity decreased linearly with HIgG concentration in the range of 0.02-200 ng mL(-1), and the detection limit was 0.001 ng mL(-1). The immunosensor has the advantages of high sensitivity, speed, specificity, and stability and could become a promising technique for protein detection.     

嵌段聚合物模板合成CdSe纳米粒子及表征

以羟基化SBS(SBS-OH)为模板,N,N-二甲基甲酰胺(DMF)为溶剂,硒代硫酸钠及乙酸镉为前驱物,"原位反应"制备了CdSe纳米粒子.通过紫外-可见吸收光谱、荧光光谱(PL)和透射电子显微镜(TEM)等方法对CdSe纳米粒子的光学性质及形貌进行了表征.结果表明,利用SBS-0H的两亲性质,可以在DMF中得到具有明...     

CTAB下真空搅拌制备车用AZ80合金阳极氧化膜腐蚀性能分析

在氧化液中加入2 g/L十六烷基三甲基溴化铵(CTAB)的情况下测试了车用AZ80镁合金表面形成的阳极氧化膜特性,并分析CTAB和基体组织之间的具体反应机制以及极氧化膜腐蚀性能。研究结果表明:在加入CTAB的情况下,CTAB与部分分解产物会在孔洞附近与镁反应。添加CTAB之后,氧化膜孔隙率减小近50%,并且孔洞尺寸与数量发生降低。添加CTAB氧化膜内并未形成大尺寸孔洞,小孔数量也明显减少,形成了更加致密的氧化膜。相比较未添加CTAB,添加CTAB氧化膜厚度增大明显,可见CTAB有助于氧化膜的成长。发生火花放电时,熔融物获得了更强的流动能力,孔隙率与孔径尺寸都发生了减小。添加CTAB氧化膜获得了比未添加CTAB更高的自腐蚀电位,能够显著增强阳极氧化膜的耐蚀能力。在添加CTAB氧化膜内存在C₄H₆MgO₄、MgO、Mg₂SiO₄多种成分。     

Synthesis and Characterization of Fe-Doped CdSe Nanoparticles as Dilute Magnetic Semiconductor

Cd_1?x Fe _x Se (0??x??0.1) nanoparticles were synthesized by hydrothermal method. The solubility limit of Fe in CdSe nanoparticles was found to be less than 6?% as obtained from X-ray diffraction (XRD) study. With the increase in doping concentration at and above it, secondary phase of FeSe₂ starts appearing. The presence of Cd, Se, and Fe has been confirmed by energy dispersive X-ray spectroscopy (EDS). The increase in band gap value has been confirmed by UV-visible spectra and the variation in emission intensity of photoluminescence (PL) measurements further indicates the incorporation of Fe in CdSe nanoparticles. Transmission electron microscopy (TEM) reveals the spherical nature of synthesized nanoparticles, and the particle size decreases with increasing Fe doping concentration. Fourier transform Infrared spectra (FTIR) confirm the capping of sodium dodecyl sulfate (SDS) surfactant on pure and Fe-doped CdSe nanoparticles. The synthesized nanoparticles show room-temperature ferromagnetic behavior, and the saturation magnetization value was found to increase with Fe doping concentration.     

Synthesis and Photoluminescence Enhancement of Silver Nanoparticles Decorated Porous Anodic Alumina

Silver nanoparticles(Ag NPs) were successfully assembled in porous anodic alumina(AAO) templates via a green silver mirror reaction.The Ag NPs/AAO composite templates then were characterized by field emission scanning electron microscopy(FESEM),energy-dispersive X-ray microanalysis(EDX),and X-ray diffraction(XRD).Furthermore,the photoluminescence(PL) properties were also investigated.Compared with the blank AAO,the PL intensity of Ag NPs/AAO templates are enhanced and the maximum enhancement is 2.58 times.Based on the local electric field enhancement effect,the theoretical values were also deduced,which are basically coincident with the experimental.     

Assembly of Colloidal Nanoparticles into Anodic Aluminum Oxide Templates by Dip-Coating Process

In this paper, the assembly behavior of colloidal nanoparticles into anodic aluminum oxide (AAO) templates is investigated. Approximately 20-nm-diameter iron oxide ($hbox{Fe}_{2}hbox{O}_{3}$ ) particles stabilized by oleic acid and 5-nm-diameter CdSe coated by thin ZnS and stabilized by trioctylphosphine oxide and dispersed in octane solvent are integrated into AAO pores with an average pore diameter of $sim$30–100 nm by dip-coating process. The particles assemble selectively at the bottom of pores. Also, the multiple stacks of particles are obtained selectively inside the pores by sequentially repeating dip coating and removing the surfactants (oleic acid) from the particle layer. The nanoparticles integrated into nanometer-scale AAO templates produce the nanostructures for potential applications such as high-density patterned magnetic media, patterned nanoparticle layers for memory device, seeds for nanowire growth, and so on.      

Electrochemiluminescence sensors for scavengers of hydroxyl radical based on its annihilation in CdSe quantum dots film/peroxide system

This work elucidated the detailed electrochemiluminescence (ECL) process of the thioglycolic acid-capped CdSe quantum dots (QDs) film/peroxide aqueous system. The QDs were first electrochemically reduced to form electrons-injected QDs approximately -1.1 V, which then reduced hydrogen peroxide to produce OH* radical. The intermediate OH* radical was a key species for producing holes-injected QDs. The ECL emission with a peak at -1.114 V was demonstrated to come from the 1Se-1Sh transition emission. Using thiol compounds as the model molecules to annihilate the OH* radical, their quenching effects on ECL emission were studied. This effect led to a novel strategy for ECL sensing of the scavengers of hydroxyl radical. The detection results of thiol compounds showed high sensitivity, good precision, and acceptable accuracy, suggesting the promising application of the proposed method for quick detection of both scavengers and generators of hydroxyl radical in different fields.     

多孔氧化铝模板在酸性和碱性介质中的腐蚀过程

将AAO模板分别在体积比为1:9(约15%(质量分数))的H_3PO_4溶液和10%(质量分数)的NaOH溶液中进行蚀刻处理,结果显示,AAO模板经过一个扩孔过程,最终孔间壁较薄部分被彻底蚀刻掉,孔间壁较厚部分留下形成氧化铝纳米线状结构.在2种蚀刻溶液中.NaOH溶液对模板的蚀刻比H_3PO_4溶液的快.这些结果对于AAO扩孔、氧化铝纳米结构的合成以及模板的去除具有一定的指导意义.     

Cytotoxicity of colloidal CdSe and CdSe/ZnS nanoparticles

Cytotoxicity of CdSe and CdSe/ZnS nanoparticles has been investigated for different surface modifications such as coating with mercaptopropionic acid, silanization, and polymer coating. For all cases, quantitative values for the onset of cytotoxic effects in serum-free culture media are given. These values are correlated with microscope images in which the uptake of the particles by the cells has been investigated. Our data suggest that in addition to the release of toxic Cd(2+) ions from the particles also their surface chemistry, in particular their stability toward aggregation, plays an important role for cytotoxic effects. Additional patch clamp experiments investigate effects of the particles on currents through ion channels.     

CdSe and CdSe/ZnS quantum dots for the detection of C-reactive protein

In this study, a method for the detection of C-reactive protein (CRP) using CdSe and CdSe/ZnS quantum dots (QDs) is proposed. CdSe and CdSe/ZnS core-shell QDs are synthesised by using 2-mercaptosuccinic acid (MSA) as a capping agent. These QDs were then subjected to various characterisation studies, namely X-ray diffraction and transmission electron microscope for size and structure, Fourier transform infrared spectroscopy for the confirmation of functional groups, ultraviolet–visible absorption and fluorescence spectroscopy for optical characteristics and dynamic light scattering for hydrodynamic changes of QDs. Two biochemical mixtures were developed: one by mixing blood serum containing CRP and CdSe-phosphorylethanolamine (PEA) and the other by mixing blood serum with CdSe/ZnS-PEA. When these mixtures are observed for fluorescence due to interaction of QDs with CRP, a correlation between changes in fluorescence for different concentrations of CRP is noted. The result demonstrates that CRP can be detected with the help of QDs without using any antibodies.     

镁锂合金碱性硅酸盐阳极氧化膜的结构及其封孔前后的耐腐蚀性能

传统的阳极氧化工艺对环境有污染,为此,开发了环境友好的阳极氧化工艺.探讨了阳极氧化时间和电流密度对镁锂合金在碱性硅酸盐体系中阳极氧化膜结构及性能的影响,考察了膜封孔前后的耐腐蚀性能,并讨论了其耐蚀机理.利用X射线衍射(XRD)和扫描电镜(SEM)研究了氧化膜的组成、组织结构和形貌;利用无损涡流测厚仪测定了氧化膜层的厚度;利用极化曲线(Tafel)和电化学交流阻抗谱(EIS)等电化学方法评价了镁锂合金阳极氧化膜封孔前后的耐蚀性.结果表明:本体系下形成的阳极氧化膜主要由Mgo,Mg(OH)2和LiOH组成;氧化时间20 min,电流密度1.O A/dm2时,氧化膜平整致密,孔洞均匀,膜厚为18～22 μm;封孔后自腐蚀电流密度为1.12×10-7A/cm2,耐蚀性为封孔前的4倍;电化学阻抗谱与极化曲线对氧化膜耐蚀性变化规律的分析结果一致.     

Preparation of copper-doped CdSe nanocrystals

Sols of stabilized copper-doped CdSe nanocrystals in a nonpolar high-boiling solvent have been synthesized using cadmium oleate, copper stearate, and trioctylphosphine selenide as starting reagents. The average size of the nanocrystals is 2.8–2.9 nm, with a 10% variance, as evaluated from their absorption spectra. The samples show excitonic luminescence and bright near-IR (700–900 nm) luminescence with a lifetime on the order of 0.5–1 μs. The luminescence spectroscopy data are consistent with the assumption that the copper distribution over the nanocrystals follows Poisson’s law. The average copper content of the samples is 0.1–2 atoms per nanocrystal.     

Preparation of hollow CdSe nanospheres

Cadmium selenide (CdSe) hollow nanospheres (approximately 40–50 nm) have been successfully synthesized by γ-irradiating polyacrylamide (PAM) hydrogel template which contains CdCl₂ and Na₂SeO₃ aqueous solution at room temperature. The nanospheres were characterized by energy dispersive spectrum (EDS), field emission scanning electron micrograph (FESEM), transmission electron microscopy (TEM) and high-resolution transmission electron micrograph (HRTEM), respectively. EDS showed that nanospheres were composed of Cd and Se (atomic ratio, 1.15:1). A possible formation mechanism of CdSe hollow nanospheres through two-steps was presented.