用于生物标记的半导体量子点研究

半导体量子点的独特光学性质使之成为理想的荧光探针材料，在生物医学领域具有广阔的应用前景．本文评述了目前量子点合成、表面修饰、结合生物分子的方法，以及半导体量子点在生物标记应用中相对于传统有机染料的优点．     

Sensing and Biosensing with Semiconductor Quantum Dots

Due to an internal error, the following article was added after the original publication of the special issue on Nanochemistry (11-12/2012). Semiconductor quantum dots (QDs) exhibit unique photophysical properties, turning these nanomaterials into ideal components for the development of optical or optoelectronic sensors and biosensors. Various methods and mechanisms of using QDs for sensing have been implemented, including the probing of recognition events by the luminescence of the QDs, their application in fluorescence resonance energy transfer (FRET), electron transfer (ET), chemiluminescence resonance energy transfer (CRET), and photoelectrochemical generation of photocurrents. These different mechanisms are exemplified by discussing the QD-based sensing of low-molecular-weight substrates, chiroselective sensing of amino acids, probing of the catalytic activities of enzymes (casein kinase, tyrosinase, NAD⁺-dependent enzymes), and analysis of DNA and of aptamer-substrate complexes. Specifically, the amplified QD-based sensing of DNA using exonuclease III as target regeneration biocatalyst and the multiplexed detection of DNAs using differently sized QDs are discussed. Also, the implementation of the CRET process for the multiplexed analysis of DNA using differently sized QDs is addressed. Finally, the use of semiconductor QDs for the photoelectrochemical detection of DNA, aptamer-substrate complexes and enzyme activities are discussed. Specifically, the use of QDs for photoelectrochemical sensors, using the CRET process as internal excitation light source, is described. The future applications of the various QD-based sensors as analytical devices and as nanotools that probe intracellular processes are discussed.     

基于半导体量子点的电致化学发光试剂的研究进展

电致化学发光因为不需要激发光源,没有杂散光的干扰,实验设备简单且具有背景信号低、灵敏度高的优点,近年来在环境监测、食品安全分析、生物传感和成像等领域都引起了科学家们广泛的关注.在电致化学发光技术中,发光试剂无疑是最重要的组成部件.随着纳米科学和技术的迅猛发展,半导体量子点由于尺寸调控带隙、表面易于改性和表面态依赖性的电...     

硅壳包裹核/壳型CdSe/CdS纳米晶的制备与性能研究

采用低温水热技术,分别以柠檬酸、聚乙二醇(PEG400)和甲硫氨酸为稳定剂,在水相中合成了核壳型CdSe/CdS量子点,研究了稳定剂、CdSe与CdS物质的量比对量子点发光性能和结构的影响。XRD结果表明,当CdSe∶CdS在1∶3~4时,CdS主要在CdSe的外延生长,形成核壳型纳米粒子,当比例达到1∶5时,CdS单独成晶现象严重。CdSe∶CdS=1∶4时,核壳型量子点具有较高的荧光发射效率。TEM研究表明CdS在CdSe外表面生长形成较为完整的壳层,有效钝化CdSe表面,减少表面缺陷,从而显著提高CdSe量子点的发光效率。CdSe核尺寸为2~3nm的核壳型纳米粒子外包裹一层SiO2壳后,荧光发射效率没有显著提高,发射峰位置无明显红移。量子点包壳后能有效提高该量子点的光化学稳定性,提高量子点的生物相容性。     

Influence of GaAs Substrate Orientation on InAs Quantum Dots: Surface Morphology, Critical Thickness, and Optical Properties

InAs/GaAs heterostructures have been simultaneously grown by molecular beam epitaxy on GaAs (100), GaAs (100) with a 2° misorientation angle towards [01−1], and GaAs (n11)B (n = 9, 7, 5) substrates. While the substrate misorientation angle increased from 0° to 15.8°, a clear evolution from quantum dots to quantum well was evident by the surface morphology, the photoluminescence, and the time-resolved photoluminescence, respectively. This evolution revealed an increased critical thickness and a delayed formation of InAs quantum dots as the surface orientation departed from GaAs (100), which was explained by the thermal-equilibrium model due to the less efficient of strain relaxation on misoriented substrate surfaces.     

CdTe量子点的纯化以及作为pH探针的研究

以巯基乙酸为稳定剂在水相中合成了CdTe量子点,并将合成的CdTe量子点进行表征、纯化。通过用0.05 mol.L-1PBS缓冲溶液调节不同的pH来考察量子点的荧光强度和pH的关系。研究发现,水溶性的CdTe量子点是pH敏感的,随着pH值的降低,量子点荧光强度的下降规律与溶液pH值呈现良好的线性关系。结果表明,CdTe量子点是一个令人满意的pH敏感的探针,有潜在的化学和生物传感能力。     

石墨烯量子点的制备与表征

介绍了一种改进的溶剂热法制备石墨烯量子点(GQDs)。该方法以N,N-二甲基甲酰胺(DMF)和氧化石墨烯(GO)作为溶剂和原料,过程中会对GO进行微波膨胀预处理,然后进行反应。分别采用紫外可见吸收、光致发光、红外、透射电镜对石墨烯量子点进行结构、形貌以及荧光性能的表征。通过该方法制备的GQDs的荧光发射光谱表明其具有可激发性且具有良好的荧光性能。     

Growth of InAs Quantum Dots on Germanium Substrate Using Metal Organic Chemical Vapor Deposition Technique

Self-assembled InAs quantum dots (QDs) were grown on germanium substrates by metal organic chemical vapor deposition technique. Effects of growth temperature and InAs coverage on the size, density, and height of quantum dots were investigated. Growth temperature was varied from 400 to 450 °C and InAs coverage was varied between 1.40 and 2.35 monolayers (MLs). The surface morphology and structural characteristics of the quantum dots analyzed by atomic force microscope revealed that the density of the InAs quantum dots first increased and then decreased with the amount of InAs coverage; whereas density decreased with increase in growth temperature. It was observed that the size and height of InAs quantum dots increased with increase in both temperature and InAs coverage. The density of QDs was effectively controlled by growth temperature and InAs coverage on GaAs buffer layer.     

量子点作为离子探针的分析应用

量子点（quantumdots,QDs）又称半导体纳米晶（semiconductornanocrystals）是一种高效的光致发光纳米晶体。近年来,量子点表面化学的快速发展,使其得到了越来越广泛的应用。本文评述了近年来量子点在无机离子以及H’分析中的应用及进展,阐述了量子点可用于离子探针的机理,介绍了量子点作为H’探针在生物以及小分子检测中的应用并对其未来的发展方向进行了展望。     

石墨烯量子点的制备及应用

石墨烯量子点(GQDs)作为石墨烯家族的最新一员,除了继承石墨烯的优异性能,还因量子限制效应和边界效应而显现出一系列新的特性,引起了化学、物理、材料和生物等各领域科研工作者的广泛关注。GQDs的制备方法通常分自上而下和自下而上的方法。对其各种制备方法和应用分别进行了介绍,并结合各种应用对GQDs的要求给出了制备方法的建议。指出了GQDs研究中存在的问题及发展方向。     

Lateral Ordering of InAs Quantum Dots on Cross-hatch Patterned GaInP

We report the use of partially relaxed tensile as well as compressively strained GaInP layers for lateral ordering of InAs quantum dots with the aid of misfit dislocation networks. The strained layers and the InAs QDs were characterized by means of atomic force microscopy, scanning electron microscopy, and X-ray reciprocal space mapping. The QD-ordering properties of compressive GaInP are found to be very similar with respect to the use of compressive GaInAs, while a significantly stronger ordering of QDs was observed on tensile GaInP. Furthermore, we observed a change of the major type of dislocation in GaInP layers as the growth temperature was modified.     

CdSe量子点的合成及其对潜指纹的荧光显现研究

以水热法在水相中直接合成了巯基乙酸修饰的CdSe量子点,并将合成的CdSe量子点进行表征、纯化。在波长365nm紫外光的激发下,CdSe量子点发射出明亮的黄绿色荧光,荧光发射峰约位于528nm,将得到的CdSe量子点纳米发光材料应用于非渗透性客体上潜指纹的荧光标记成像研究,发现CdSe量子点溶液显现的手印纹线流畅,显现细节特征明显,呈现明亮的黄绿色荧光指纹,具有很高的实用价值和鉴定价值。     

Overview of Computational Simulations in Quantum Dots

Quantum dots (QDs) are semiconductor nanocrystals that exhibit exceptional properties not found in their bulk counterparts. They have attracted extensive academic and industrial attentions due to their quantum confinement effects and unique photophysical properties. Computational approaches such as first principles and classical molecular dynamics simulations are indispensable tools in both scientific studies and industrial applications of QDs. In this review, the state‐of‐the‐art progress in computational simulations of optical, electronic and thermal properties of QDs is summarized and discussed. First, the physics of QDs in low dimensional materials are comprehensively reviewed. Then, the theoretical basis and practical applications of two main computational methods are presented. Properties of QDs revealed by computational studies are summarized respectively. Finally, the paper was concluded with comments on future directions in computational modeling of QDs.     

二氧化锡量子点的制备、表征及缺陷研究

以SnCl4·5H2O为原料、三重蒸馏水为溶剂,结合溶胶凝胶法与水热法合成了9种不同粒径的SnO2量子点胶体及其对应的粉末颗粒。分析了不同合成条件对量子点的影响,用XRD和TEM对其粉末结构和形貌进行了表征,对SnO2纳米粒子的Uv-Vis光谱以及光致发光光谱进行了分析,计算了量子点粒径大小以及禁带宽度,并对其荧光发光机理进行了探讨。结果表明,合成的Sn02量子点的粒径为3．2～4．6nm,粒径分布均匀,分散性较好。SnO2纳米粒子光致发光在430nm、530nm和600nm处有发光峰,分别是由锡间隙、单电子氧缺陷以及表面态引起的深能级跃迁所致。     

Graphene Quantum Dots Modified Upconversion Nanoparticles for Photodynamic Therapy

Photodynamic therapy (PDT), as a novel technique, has been extensively employed in cancer treatment by utilizing reactive oxygen species (ROS) to kill malignant cells. However, most photosensitizers (PSs) are short of ROS yield and affect the therapeutic effect of PDT. Thus, there is a substantial demand for the development of novel PSs for PDT to advance its clinical translation. In this study, we put forward a new strategy for PS synthesis via modifying graphene quantum dots (GQDs) on the surface of rare-earth elements doped upconversion nanoparticles (UCNPs) to produce UCNPs@GQDs with core-shell structure. This new type of PSs combined the merits of UCNPs and GQDs and produced ROS efficiently under near-infrared light excitation to trigger the PDT process. UCNPs@GQDs exhibited high biocompatibility and obvious concentration-dependent PDT efficiency, shedding light on nanomaterials-based PDT development.     

基于量子点荧光强度变化检测陶瓷疲劳微裂纹

量子点具有荧光光谱窄、激发光谱宽、荧光强度高、稳定性好等优势,将量子点应用于微裂纹的监测有极大的优越性.本文利用量子点涂层的荧光性能进行了陶瓷裂纹的直接检测,并与实际裂纹比较发现仅有2％的差别;借助ANSYS有限元软件计算模拟了陶瓷在产生疲劳裂纹后的应力分布.对比发现,涂层荧光强度变化和应力变化都呈区域性分布,而且应力越大,荧光强度越强,说明该方法是一种简单有效的裂纹测试手段.     

Transparent Conducting Electrodes for Quantum Dots Light Emitting Diodes

In this review, we briefly describe a recent research development of transparent conducting electrodes (TCEs) for next‐generation quantum dot‐based light‐emitting diodes (QDLEDs). Although sputtered Sn‐doped In₂O₃ (ITO) and chemically grown F‐doped SnO₂ (FTO) electrodes have mainly been employed as transparent electrodes for QDLEDs, there have been great advances in TCE materials and fabrication processes. This review presents important characteristics of various TCE and applications in QDLEDs as a transparent cathode or anode. In particular, we will focus on characteristics of metal grids, metal nanowire, carbon nanotube, graphene, and hybrid electrodes for QDLEDs as promising alternatives to typical ITO and FTO electrodes. In addition, we discuss the current status of transparent conducting oxide‐based QDLEDs. By comparing the performances of QDLED with different TCEs, we suggest promising alternatives ITO or FTO electrodes.     

量子点荧光探针在生物医学领域的研究进展

量子点是一种新型的半导体荧光纳米材料,由于其特殊的纳米结构所导致的表面、介电、量子等效应而具有许多优异的光学性能,近年来在分析化学、生物医学等领域得以快速应用和发展.介绍了量子点的制备方法、表面修饰及量子点荧光探针在生物医学领域的应用进展,并对未来的发展方向作出了展望.     

三乙醇胺包覆的CdTe量子点用于尿样中三聚氰胺的荧光传感

利用三聚氰胺对乙酰半胱氨酸-三乙醇胺复合包覆的碲化镉量子点荧光的猝灭作用,建立了快速测定尿样中三聚氰胺的荧光传感新技术。研究结果表明,三聚氰胺浓度在0.1~1.0μmol/L范围内,量子点的荧光强度猝灭值(ΔF)与三聚氰胺的浓度呈线性关系,线性方程为ΔF=202.89cMA+38.26,相关系数(r)为0.9959,方法检出限0.05μmol/L。本方法用于尿液加标样品中三聚氰胺的检测,RSD为2.67%,三聚氰胺的平均回收率为98%~106%。