基于CdSe/ZnS量子点荧光生物传感器构建与应用

设计了一种由CdSe/ZnS量子点和荧光染料Cy3(C31H37KN2O8S2)基于荧光共振能量转移(FRET)原理的生物传感器,并进行了该体系下不同浓度和不同pH溶液中荧光转移强度的实验。实验表明:CdSe/ZnS荧光半导体量子点作为供体对Cy3(C_(31)H_(37)KN_2O_8S_2)染料的荧光增强作用明显。在CdSe/ZnS量子点与Cy3的比例为1∶1.2时,荧光转移效率达到83.68%,对细胞外液p H值荧光变化敏感(pH=5.93～8.36)。此外,该生物传感器可以清楚地识别前列腺癌细胞。该实验结果对前列腺癌细胞的早期诊断和前列腺癌生物传感器的设计提供了一种新的方法。     

ZnS掺Mn磷光量子点对金属离子传感机理的探讨

合成了以3-巯基丙酸或L-半胱氨酸修饰的水溶性ZnS掺Mn磷光量子点,磷光发射峰在590 nm,产生于Mn2+的4T1-6A1跃迁.磷光信号稳定,不易受溶解氧的影响.检测了七种常见金属离子对磷光性质的影响,结果表明:对于3-巯基丙酸修饰的ZnS:Mn量子点,Cu2+,Mn2+,Fe3+,Co2+,pb2和Hg2+离子能...     

基于CdSe/ZnS核壳型量子点的高灵敏、快速细菌计数新方法的研究

以乙酰丙酮镉和硬脂酸锌为前驱体,合成了巯基丙酸修饰的CdSe/ZnS核壳型量子点(QDs)。并将其作为荧光探针,以金黄色葡萄球菌(S.aureus)为目标细菌,建立了一种高灵敏的、简单快速的细菌计数新方法,并借助荧光显微镜成功的进行成像探测研究。通过考察量子点浓度、孵育时间等因素的影响,确定了细菌定量检测的最佳条件。在最优化的实验条件下,体系的相对荧光强度随细菌数量的增加而增大。该方法的线性范围为102CFU/mL～106CFU/mL,检测限为102CFU/mL,线性回归方程为Y=427.586X-677.022(R=0.996 49)。本方法有效克服了传统的细菌计数方法存在的缺陷,具有较高的灵敏度和较好的重现性(实际样品检测的RSD=3.6%～8.1%),且操作简单、检测时间短、成本低,有很好的潜在应用价值。     

PVP／CdS量子点修饰电极的制备及其对肌红蛋白的直接电化学研究

该文采用溶胶-凝胶法制备了聚乙烯吡咯烷酮(PVP)表面修饰的硫化镉(CdS)半导体量子点,用透射电镜(TEM)、X射线衍射(XRD)等手段进行了表征;将其修饰在玻碳电极(GC)表面制得量子点修饰电极,并研究了肌红蛋白(Myoglobin,Mb)在该量子点修饰电极上的电化学行为.实验结果表明,PVP/CdS量子点修饰电极对肌红蛋白具有催化还原作用,且还原峰电流与被测蛋白质浓度呈良好线性关系.流动注射分析结果进一步表明该量子点修饰电极具有高的稳定性和好的重现性,检出限为2.0×10.mol/L,该电极可作为检测肌红蛋白的新型高灵敏度电化学传感器.     

基于CdTe／CdS量子点与金纳米粒子的荧光共振能量转移测定三聚氰胺

量子点具有良好的光学性能和高的光致发光量子产率,已广泛应用于生物分析。该文利用金纳米粒子（AuNPs）与CdTe／CdS量子点相互作用,发生荧光共振能量转移（FRET）而猝灭Cdrre／CdS量子点的荧光．加入三聚氰胺后使量子点的荧光恢复这一现象,建立了一种基于CdTe／CdS量子点与AuNPs的FRET测定三聚氰胺的高灵敏方法。     

CdTe/CdS量子点在Nafion/羟基磷灰石膜上的电化学发光及其应用于肌红蛋白的高灵敏检测

利用羟基磷灰石(HAp)和Nation将CdTe/CdS量子点(QDs)修饰到玻碳电极表面,研究了固定在复合膜内的CdTe/CdS量子点的电化学发光行为.相比水溶液中的量子点在裸电极上的电化学发光,CdTe/CdS修饰到复合膜内后的电化学发光更加稳定,且发光强度增加数十倍.在pH为6.5的磷酸盐缓冲溶液(PBS)中,以...     

黄芩活性组分与牛血清白蛋白相互作用的热力学分析

用荧光光谱和紫外可见吸收光谱法研究了在不同温度下,中草药黄芩的水提取液中的活性成分(RS)与牛血清白蛋白(BSA)的相互作用的光谱行为,试验发现,RS对BSA有较强的荧光猝灭作用.用Stern-Volmer和Lineweaver-Burk方程分别处理试验数据,发现RS与BSA反应生成新的复合物且发生了分子内的非辐射能量转移,属于是静态荧光猝灭类型,并计算出不同温度下形成复合物的形成常数KLB(288 K:4.538×10-4L·mol-1;308 K:3.488× 104 L·mol-1)及对应温度下结合反应的热力学参数(ΔHθ=-9.71 kJ·mol-1;△Sθ=55.45/55.42kJ·mol-1;△Gθ=-25.68/-26.78kJ·mol-1),证明二者主要靠疏水作用力结合.这为了解中草药中的活性小分子与蛋白质等生物大分子的弱相互作用提供有益的参考和依据.     

量子点荧光标记技术在生物医学领域的应用

量子点作为一种新型的纳米荧光材料在生物学领域的应用已引起国际上的普遍关注,量子点独特的荧光性能使其在这一领域的应用有着无可比拟的优越性.该文主要就量子点的荧光性能,基于量子点标记的生物荧光探针的制备及其在生物医学领域中的应用研究进展作一概述.     

动态加权蛋白质相互作用网络构建及其应用研究

一个蛋白质可能在不同条件或不同时刻与不同的蛋白质发生相互作用,这称为蛋白质的动态特性.蛋白质在分子处理的不同阶段参与到不同的模块,与其他的蛋白质共同完成某项功能.因此, 动态蛋白质相互作用的研究有助于提高蛋白质功能预测的准确率.结合蛋白质相互作用网络和时间序列基因表达数据,构建动态蛋白质相互作用网络.为降低PPI网络中假阴性对功能预测产生的负面影响,结合结构域信息和复合物信息,预测和产生新的相互作用,并对相互作用加权.基于构建的动态加权网络,提出一种功能预测方法D-PIN (Dynamic protein interaction networks). 基于三个不同的酵母相互作用网络实验结果表明, D-PIN 方法的综合性能比现有方法提高了14%以上.结果验证了构建的动态加权蛋白质相互网络的有效性.     

基于近红外荧光量子点的防伪技术基础研究

提出了一种新型的利用近红外荧光量子点作为载体的防伪方法,并进行了相关基础研究,应对了产品市场对防伪技术不断革新的需要;设计了微弱荧光光谱测试系统,系统研究了双波长荧光量子点防伪识别技术,得出双波长荧光光谱识别的基本方法,将近红外荧光量子点的荧光强度之间的差异作为识别的依据,设计出相应的编码方法即可以对信息进行加密;测试结果表明该方法切实可行;研究结果对近红外荧光量子点的防伪识别有重要的指导意义,为防伪技术打开了更广阔的发展空间。     

Amplification of fluorescence emission of CdSe/ZnS QDs entrapped in a sol-gel matrix, a new approach for detection of trace level of PAHs

In this work, CdSe/ZnS core/shell QDs with emission wavelengths of 535 nm, 545 nm, 555 nm and 575 nm were synthesized and the ligands on their surface were exchanged with mercaptopropionic acid (MPA) to make them water-soluble. Hydrophilic QDs were incorporated into a sol-gel GA matrix of 3-aminopropyl trimethoxysilane (APTMS) and 3-glycidoxypropyl trimethoxysilane (GPTMS) to fabricate QD-entrapped membranes. The fluorescence intensity of the QDs entrapped in the sol-gel membrane was increased after being activated by the energy transfer from polycyclic aromatic hydrocarbon compounds (PAHs). The signal increase of the QDs was proportional to the increase in the concentration of the PAHs. Herein, trace levels of anthracene (ANT), phenanthrene (PHE) and pyrene (PYR) were detected through the enhancement of the fluorescence intensity of the CdSe/ZnS QD-entrapped membranes. The linear detection ranges were 0.01-0.1 μM for ANT and PHE and 0.005-0.05 μM for PYR. The QD-entrapped sol-gel membranes also showed quite good stability for the detection of PAHs over a period of 2 months.     

Red light emission from hybrid organic/inorganic quantum dot AC light emitting displays

An alternating current electroluminescent display has been direct written onto a flexible plastic substrate. A hybrid layer of poly(2-methoxy,5(2-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV) and CdSe quantum dots (QDs) were used to convert the light emitted by electroluminescent ZnS phosphor into red light. The emission wavelength of the display is found to be directly related to the emission of CdSe quantum dots. The integration of QDs into thin film electroluminescent (TFEL) displays has the potential to enhance its color spectrum.     

Luminescent quantum dot-bioconjugates in immunoassays, FRET, biosensing, and imaging applications

Colloidal semiconductor nanocrystals (quantum dots, QDs), such as CdSe-ZnS core-shell, are highly luminescent and stable inorganic fluorophores that represent a promising alternative to organic dyes for a variety of biotechnological applications. They show size-tunable narrow photoluminescence spectra spanning nearly the full visible region of the optical spectrum for QDs with CdSe cores. We have developed several approaches to conjugate either one type or a combination of biologically distinct proteins to CdSe-ZnS core-shell QDs rendered water-soluble by surface ligation with dihydrolipoic acid (DHLA) groups. QD-protein conjugates prepared using these approaches were found to exhibit high specificity and stability in immunoassays and in Förster resonance energy transfer (FRET) assays as well as in prototype QD bioconjugate sensors. Tunable QD emission over a wide range of wavelengths permitted effective tuning of the degree of energy overlap between the QD donor and an acceptor dye, allowing control over the rate of FRET. Additionally, we have used these QD-bioconjugates in live cell labeling. These hybrid bioinorganic conjugates represent a promising tool for use in many biotechnological applications.     

Color tuning of indium phosphide quantum dots for cadmium‐free quantum dot light‐emitting devices with high efficiency and color saturation

Semiconductor quantum dots (QDs) promise facile color tuning and high color saturation in quantum‐dot light‐emitting devices (QD‐LEDs) by controlling nanoparticle size and size distribution. Here, we demonstrate how this promise can be practically realized for the cadmium‐free InP/ZnSe/ZnS multishell quantum dots. We developed a set of synthesis conditions and core/shell compositions that result in QDs with green, yellow, and red emission color. The QD‐LEDs employing these QDs show efficient electroluminescence (EL) with luminance up to 1800 cd/m² and efficiency up to 5.1 cd/ A . The color coordinates calculated from the EL spectra clearly demonstrate the outstanding color saturation as an outcome of the narrow particle size distribution. These results prove that the performance gap between cadmium‐free and cadmium‐based QDs in QD‐LEDs is shrinking rapidly.     

Direct Fabrication of Nanoscale Light Emitting Diode on Silicon Probe Tip for Scanning Microscopy

We have fabricated a silicon microprobe integrated with a nanometer-sized light emitting diode (Nano-LED) on the tip. This paper describes the fabrication procedure and preliminary topographic testing results. The silicon probe with electrode pattern was made by wet-etching a silicon-on-insulator wafer using oxide as the mask. Subsequently, the probe tip was cut using a focused ion beam (FIB) to form a 150 nm-wide gap. Semiconductor nanoparticles (CdSe/ZnS core-shell nanoparticles) were electrostatically trapped and excited within the electrode gap made on the probe tip. The LED-tip is approximately 150 nm 150 nm. The nano-LED light intensity and current were measured as a function of the driving voltage up to 25 V. In addition to the electroluminescence peaks from the CdSe particles, possible emission from silicon dioxide doped in the FIB milling process was also observed in the measured spectra. Basic mechanical characteristics of the silicon probe were measured by mounting the probe on a tuning fork in a standard near-field scanning optical microscopy (NSOM) set up. It was observed that the drag force reduces the probe oscillation as the vibrating tip approached the near-field of the sample surface. The topographic images of a chromium test pattern on a glass substrate were successfully acquired by keeping the probe tip within roughly 5 nm from the sample surface. Although the probe tip shape and the location of the Nano-LED are yet to be further optimized before realizing near-field optical scanning experiment, the result showed its great promise as a new type of NSOM tip with the ldquoon-proberdquo light-source.     

A droplet-based microfluidic platform for rapid immobilization of quantum dots on individual magnetic microbeads

Quantum dots (QDs) provide opportunities for the development of bioassays, biosensors, and drug delivery strategies. Decoration of the surface of QDs offers unique functions such as resistance to non-specific adsorption, selective binding to target molecules, and cellular uptake. The quality of decoration has substantial impact on the functionality of modified QDs. Single-phase microfluidic devices have been demonstrated for decorating QDs with biological molecules. The device substrate can serve as a solid-phase reaction platform, with a limitation being difficulty in the realization of reproducible decoration at high density of coverage of QDs. Magnetic beads (MBs) have been explored as an alternative form of solid-phase reaction platform for decorating QDs. As one example, controlled decoration to achieve unusually high density can be realized by first coating MBs with QDs, followed by the addition of molecules such as DNA oligonucleotides. Uniformity and high density of coatings on QDs have been obtained using MBs for solid-phase reactions in bulk solution, with the further advantage that the MBs offer simplification of procedural steps such as purification. This study explores the use of a droplet microfluidic platform to achieve solid-phase decoration of MBs with QDs, offering control of local reaction conditions beyond that available in bulk solution reactions. A microchannel network with a two-junction in-series configuration was designed and optimized to co-encapsulate one single 1 µm MB and many QDs into individual droplets. The microdroplet became the reaction vessel, and enhanced conjugation through the confined environment and fast mixing. A high density of QDs was coated onto the surface of single MB even when using a low concentration of QDs. This approach quickly produced decorated MBs, and significantly reduced QD waste, ameliorating the need to remove excess QDs. The methodology offers a degree of precision to control conjugation processes that cannot be attained in bulk synthesis methods. The proposed droplet microfluidic design can be widely adopted for nanomaterial synthesis using solid-phase assays.     

Quantum dot phosphors free from hazardous elements: Current status and prospects for established materials and new ZnTe‐based alloys

Television broadcasts are moving to a digital video format based on ultra‐high‐definition (UHD). In addition to high resolution, such UHD displays require a wide color gamut. Quantum dots (QDs) have narrow and color‐tunable emission making these unique light sources for achieving a wide color gamut. Most progress in QDs has been made based on cadmium‐containing materials, as represented by CdSe. These systems have excellent performance in terms of their narrow‐band emission and high emission quantum yield; however, the toxicity of cadmium represents a barrier to practical applications of QD displays. Over the last decade, considerable efforts have been made to develop QDs that do not contain cadmium. Some established alternative materials include InP, CuInS₂, and lead halide perovskites. In addition, ZnTe‐based alloy QDs have recently been proposed as promising green and red phosphors. Narrow‐band and green emission (30 nm of full‐width at half‐maximum at a wavelength of 535 nm) has also been reported for Zn (Te, Se) alloy QDs. In this review article, we give a brief overview of progress in established cadmium‐free QDs and describe the current status and future challenges of new cadmium‐free QDs, ZnTe‐based alloy QDs.