基于CdS量子点-CNTs复合物的无标记电化学发光免疫传感器

由于尺寸效应的影响,半导体纳米晶体(NCs,又称量子点QDs)具有优良的电学、光学、磁学和电化学性质~([1～3]).半导体纳米晶体因其独特的荧光特性而广泛应用于发光装置与生物标记领域~([4]).     

荧光量子点及其在生物检测中的应用

量子点(QDs)是一种零维的半导体纳米晶体,与传统的有机染料相比,具有独特的光学特征。由于它们具有激发光谱宽、发射光谱窄、发射波长精确可调、量子产率高和荧光稳定性好等特点,作为新一代的生物荧光探针,已被广泛应用于生物检测。本文介绍了QDs的基本概念和性质,探讨了QDs的制备方法及表面修饰,对其毒性也作了简要分析,提供了QDs在荧光免疫分析、生物芯片、生物传感器及体内成像等方面的应用实例。随着技术发展的不断进展,QDs在生物分析领域有着更为广泛的潜在的应用前景。     

量子点在电化学生物传感研究中的应用*

量子点( Quantum dots,QDs )由于具有独特的光学、电化学和电致化学发光特性已受到广泛地重视,而利用量子点构建电化学生物传感器则是量子点最有前途的应用领域之一。量子点具有的高比表面积、高表面活性及小尺寸等特性使它对外界的光、电、温度等十分地敏感,外界环境的微小改变就会迅速引起其表面或界面粒子价态和电子转移行为的显著变化,基于生物大分子引起的QDs表面电化学行为变化而构建的电化学生物传感器,其特点是响应灵敏高、速度快且选择性优良。本文对量子点的光学、电化学和电致化学发光特性作了简单介绍,并重点回顾了其在电致化学发光、免疫分析、DNA杂交、蛋白质检测、农药检测和糖类检测电化学生物传感研究中的应用。同时,对量子点在电化学生物传感研究中的应用前景及研究方向进行了评述和展望。     

镉系量子点的生物毒性及相应机制

量子点(quantum dots,QDs)由于其优异的荧光特性在生物学和生物医学领域具有广泛的应用,并且在肿瘤的诊断和治疗方面也表现出巨大的潜力,但是随之而来的生物毒性问题近几年备受研究者们的高度关注。本文选取研究最多的Cd系量子点为代表,总结了量子点体外体内生物毒性的一般规律和特点,重点从量子点进入体内途径、内吞进入细胞方式和细胞内发挥功能等方面探讨了其毒性效应的机制。希望以此为发展安全低毒量子点提供指导和建议,促进量子点的临床应用。     

基于Mn掺杂ZnS量子点磷光内滤效应检测β-葡萄糖醛酸酶

高效荧光内滤分析的关键是使猝灭剂的吸收峰与荧光团的激发峰或发射峰最大限度地重叠.本研究将Mn掺杂ZnS量子点(Mn-ZnS QDs)作为内滤体系的荧光体,4-硝基苯-β-D-葡糖苷酸(PNPG)作为吸收体,实现了β-葡萄糖醛酸酶(GUS)的特异性检测.PNPG的吸收光谱与Mn-ZnS QDs的激发光谱大幅重叠,能够高效猝灭Mn-ZnS QDs的磷光.由于Mn-ZnS QDs具有较大的斯托克斯位移(约300 nm),其激发光谱和发射光谱与GUS的酶解产物PNP的吸收光谱几乎无重叠,因而实现了GUS的磷光Turn-on检测.此外,Mn-ZnS QDs具有优异的室温磷光性质,可以避开生物组织荧光背景,从而可有效应用于生物样品分析.据此建立了一种基于内滤效应的GUS磷光探针,实现了对大肠杆菌的测定.本方法在最优的实验条件下对10~300 U/L的GUS有线性响应,检出限为7 U/L,且本策略相对于紫外-可见光谱法有很好的抗基底干扰能力.     

蛋白包覆的作用模式对CdTe量子点光稳定性及细胞毒性的影响

<正>量子点(quantum dots,QDs)是一种新型荧光纳米材料,具有宽带吸收与窄带发射、发射波长随粒径可调、双光子吸收截面大和抗光漂白等优异性质,在细胞和活体成像、化学和生物传感等领域正在得到越来越广泛的应用。随着应用研究的不断深入,量子点的生物效应特别是其细胞毒性引起了人们的普遍关注,提高量子点的稳定性及生物相容性已成为一个重要的研究课题。本论文通过系统研究牛血清白蛋白(bovine serum albumin,BSA)包覆的三种作用模式(静电模式、     

量子点CdSe-ZnS与乳酸共聚物复合薄膜QDs/PLGA的谱学性能及聚合物薄膜体外降解行为研究

采用简单的溶液浇铸法制备了不同硒化镉-硫化锌核壳结构量子点(CdSe-ZnSQDs)含量的QDs/乳酸-乙醇酸共聚物(PLGA)纳米复合材料薄膜,对薄膜的微观结构、谱学性能等进行了系统的研究后,重点研究了PLGA、QDs/PLGA复合材料的体外降解行为.荧光光谱、紫外-可见光谱分析结果显示QDs与PLGA复合后仍具有稳定优异的发光性能和吸光度,且发光和吸光强度随QDs含量增加而增大.在体外降解的研究中,凝胶渗透色谱结果和磷酸盐缓冲液的pH值变化显示量子点的加入加快了PLGA的降解;而复合材料的荧光效应随着降解的进行而逐渐减弱.以上结果证明CdSe-ZnSQDs/PLGA纳米复合材料可采用简单的溶液浇铸法成功制备,且可通过检测荧光效应变化来监测QDs/PLGA复合材料的降解进程.     

基于水溶性硅量子点的汞离子荧光传感器

本文基于Hg~(2+)对水溶性硅量子点(Si QDs)的荧光猝灭效应,构建了一种简单、快捷的Hg~(2+)荧光传感器。实验发现,当Si QDs表面的氨基与Hg~(2+)结合形成配合物时,Si QDs的荧光被猝灭,根据荧光猝灭程度与Hg~(2+)的浓度关系,可实现Hg~(2+)的检测。在优化的实验条件下,Si QDs的荧光猝灭程度与Hg~(2+)浓度在5.0×10-8~1.0×10-6 mol/L范围内呈良好的线性关系(R2=0.9978),检出限(3σ)为2.2×10-8 mol/L。在此基础上,借助Hg~(2+)易于与巯基结合形成稳定配合物的原理,选用治疗Hg~(2+)中毒的药品二巯基丙磺酸钠(DMPS)为模型,利用该巯基化合物可使Hg~(2+)猝灭Si QDs的荧光恢复的特性,建立了一种检测DMPS的新方法。     

基于量子点的电化学发光核酸分析传感器研究进展

核酸是一种十分重要的生物大分子,有关核酸分析的研究一直是生物分析中非常活跃的领域。电化学发光(ECL)技术具备灵敏度高、可控性强、选择性高等优点,广泛应用于生物分析领域。量子点(QDs)具有优异的光学特性和良好的电化学性能。量子点独特的光电特性可与电化学发光相结合,构建灵敏度高、特异性强及检出限低的电化学发光生物传感器用于核酸分析。本文简要地介绍了量子点并对其进行系统的分类,重点介绍了量子点作为发光体材料在电化学发光核酸分析传感器中的应用。     

CdSe量子点对雄性泥鳅的毒性效应研究

量子点（Quantum Dots,QDs）,也称纳米微晶体,由于其独特的荧光特性越来越受到研究者的关注.近年来,量子点的生物学毒性效应及其环境影响成为新的研究热点.本文通过活体实验,以雄性泥鳅为模型动物,以腹腔注射为染毒方式,研究了量子点的雌激素干扰效应、毒物动力学行为以及靶器官的氧化应激指标.结果显示,QDs能够显著抑制E2诱导产生的卵黄蛋白原（Vtg）含量,性腺切片的观察结果与其一致.通过游离Cd^2＋和其他几种纳米材料的对比实验,认为量子点对Vtg的抑制表达是游离Cd^2＋和QDs颗粒对E2的非特异性吸附的共同作用结果.毒物动力学结果表明,腹腔注射1h后,肌肉、骨头、肠、血液和性腺中QDs含量达到最大浓度（Cmax）,随后呈降低趋势 而在肝脏和肾脏中,QDs含量呈增加趋势,说明QDs在动物体内的半衰期较长,在体内能够持续存留.通过对靶器官肝脏相关抗氧化酶活性的测定结果发现,量子点由于壳层对Cd^2＋的保护,对抗氧化体系影响较小.本实验对量子点毒性的综合评价为其在活体生物学的应用提供了一定的参考.     

量子点在生物化学分析中的应用

量子点（quantumdots,QDs）由于其优异的光学和电学特性,作为新型的荧光试剂探针对生物大分子进行标记,成为近年来迅速发展的纳米材料在生化分析领域的重要应用之一。文章简述了量子点的基本特性,对制备和修饰量子点的各种方法进行比较总结,重点阐述量子点在生物化学分析中的新进展,尤其是对生物大分子的识别和标记作了详细的总结,并提出研究中存在的一些待解决的问题以及今后量子点的研究方向。     

Antioxidant activity assay based on the inhibition of oxidation and photobleaching of l-cysteine-capped CdTe quantum dots

Quantum dots (QDs) have recently been the focus of attention of many investigators for development of diagnostic tools in many research areas. In this work, we established a new QD-based assay to evaluate the antioxidant/polyphenolic activity. This assay is based on measurement of the inhibitory effect of the antioxidant/polyphenolic compounds on the UV-induced bleaching of CdTe QDs with l-cysteine capping. QDs exhibited excellent photostability without any UV exposure, while they bleached rapidly under UV irradiation. Generation of reactive oxygen species (ROS) under UV irradiation is probably the main cause of the photobleaching of QDs. By comparing the photostability of QDs in buffer solution in the absence and presence of sodium azide, as a known (1)O(2) quencher, the involvement of (1)O(2) in photobleaching of QDs was confirmed. The photobleaching effect induced by ROS could be reduced in the presence of antioxidant/polyphenolic compounds. We tested several antioxidant/polyphenolic compounds as well as known antioxidants such as trolox and 4 different types of tea. The results obtained by the QD-based assay revealed a very good correlation with the data acquired by Folin-Ciocalteu assay. Furthermore, a deeper understanding of the mechanism and the solution for photobleaching of QDs under UV irradiation might be very meaningful in promoting their clinical applications.     

Effect of Surface Modification on Semiconductor Nanocrystal Fluorescence Lifetime

Semiconductor nanocrystals, namely, quantum dots (QDs), present a set of unique photoluminescence properties, which has led to increased interest in using them as advantageous alternatives to conventional organic dyes. Many applications of QDs involve surface modification to enhance the solubility or biocompatibility of the QDs. One of the least exploited properties of QDs is the very long photoluminescence lifetime that usually has complex kinetics owing to the effect of quantum confinement. Herein, we describe the effect of different surface modifications on the photoluminescence decay kinetics of QDs. The different surface modifications were carefully chosen to provide lipophilic or water‐soluble QDs with either positive or negative surface net charges. We also survey the effect on the QD lifetime of several ligands that interact with the QD surface, such as organic chromophores or fluorescent proteins. The results obtained demonstrate that time‐resolved fluorescence is a useful tool for QD‐based sensing to set the basis for the development of time‐resolved‐based nanosensors.     

Self-Assembly of Semiconductor Quantum Dots using Organic Templates

Colloidal semiconductor nanocrystals, known as quantum dots (QDs), are regarded as brightly photoluminescent nanomaterials possessing outstanding photophysical properties, such as high photodurability and tunable absorption and emission wavelengths. Therefore, QDs have great potential for a wide range of applications, such as in photoluminescent materials, biosensors and photovoltaic devices. Since the development of synthetic methods for accessing high-quality QDs with uniform morphology and size, various types of QDs have been designed and synthesized, and their photophysical properties dispersed in solutions and at the single QD level have been reported in detail. In contrast to dispersed QDs, the photophysical properties of assembled QDs have not been revealed, although the structures of the self-assemblies are closely related to the device performance of the solid-state QDs. Therefore, creating and controlling the self-assembly of QDs into well-defined nanostructures is crucial but remains challenging. In this Minireview, we discuss the notable examples of assembled QDs such as dimers, trimers and extended QD assemblies achieved using organic templates. This Minireview should facilitate future advancements in materials science related to the assembled QDs.     

金属离子对CdS量子点/聚酰胺-胺树形分子纳米复合材料光致发光性能的影响

以聚酰胺-胺树形分子为模板制备了分散好、尺寸均匀的CdS量子点，并用分光光度滴定法研究了Cd²⁺、Zn²⁺、Pb²⁺、Cu²⁺、Mn²⁺几种金属离子对其光致发光性能的影响。发现不同离子对CdS量子点的发光性能影响不同:Cd²⁺和Zn²⁺使量子点荧光增强，Pb²⁺、Cu²⁺和Mn²⁺使其荧光有不同程度淬灭。这归因于金属离子对CdS量子点表面的修饰作用。Cd²⁺能减少由S^2-悬键构成的非辐射复合中心，增强树形分子对量子点表面缺陷的钝化作用，并能在量子点周围形成类肖特基能垒，从而显著增大CdS量子点的光致发光效率。由于ZnS与CdS的晶格参数非常接近，Zn²⁺能起到与Cd²⁺类似的作用，使CdS量子点的发光效率大大增强。Pb²⁺和Cu²⁺能取代Cd²⁺在CdS量子点表面生成窄带隙的壳层，对其发光有很强的淬灭作用。由于块体PbS的带隙比块体CuS窄，故Pb²⁺的淬灭能力强于Cu²⁺。Mn²⁺能破坏Cd²⁺与PAMAM树形分子的配位键，降低树形分子对CdS量子点表面缺陷的钝化作用，且其本身在量子点表面构成了新的荧光淬灭中心，但Mn²⁺也能形成较弱的类肖特基能垒，故对量子点的发光淬灭作用较弱。     

基于Mn掺杂ZnS量子点的室温磷光传感应用的研究进展

与一般有机染料分子相比,半导体材料量子点具有优异的光学性能,在多个领域得到了广泛的应用.量子点具有窄而对称且可调的发射波长、宽激发强吸收、抗光漂白能力强以及水溶性好等诸多优势,引起了研究者广泛关注.为了增加量子点的斯托克斯位移从而很好地避免量子点的自猝灭现象,引入掺杂物是一种很有效的方式.掺杂量子点不仅保留了量子点原有的优点,而且还赋予量子点额外的优异性能.如Mn掺杂ZnS量子点生物相容性好,不含Cd和Hg等有害元素,而且Mn2+的加入使其具有优异的室温磷光特性.磷光检测能很好地避开生物背景荧光的干扰,使得Mn掺杂ZnS量子点能够广泛应用于磷光生物分析.本文综述了Mn掺杂ZnS量子点在室温磷光分析中的研究进展,着重介绍了几种具有启发意义的设计策略,包括其发光机理以及应用于离子、分子以及生物大分子等的检测.     

水溶性量子点的制备及应用

高量子产率的水溶性量子点在众多领域如发光晶体、薄膜光激发器件,尤其是生物荧光标记中展现出巨大的潜在应用价值.量子点荧光明亮、稳定,激发光谱宽,发射光谱窄,且发射波长可通过改变材料的粒径大小和组成来调控,因而在生物样本尤其是活组织的多色成像中极为有用,能有效避免因样本自身发光和光散射导致的信号干扰.量子点的研究已成为一门新兴的交叉科学,是目前最有吸引力的研究领域之一.近年来,水溶性量子点作生物荧光标记物的研究取得了长足的进展.本文简述了量子点的结构特征及光学特性,重点综述了水溶性量子点的制备方法及应用研究进展,特别是它在生物、医学中作荧光探针的最新研究.     

化学合成荧光量子点在指纹显现中的应用

简要阐述了量子点的光学特性、制备方法及其在指纹显现中的应用。重点介绍了Ⅱ~Ⅵ族的CdS基、CdTe基、CdSe基、ZnSe基量子点和Ⅲ~Ⅴ族的InP量子点的化学合成、修饰及其在指纹显现中的研究进展,最后介绍了第Ⅳ族C、Si量子点的研究现状,并对其在指纹显现中的潜在应用作了展望。     

Fluorescent nanoparticles for chemical and biological sensing

Fluorescent nanoparticles (NPs), including quantum dots (QDs), dye-doped NPs, and rare earth-based NPs, etc., have been a major focus of research and development during the past decade. The impetus behind such endeavors can be attributed to their unique chemical and optical properties, such as bright fluorescence, high photostability, large Stocks shift and flexible processability. The introduction of fluorescent NPs into analytical chemistry has opened up new venues for fluorescent analysis. In this review...     

Study of fluorescence quenching and dialysis process of CdTe quantum dots, using ensemble techniques and fluorescence correlation spectroscopy

Luminescence properties of quantum dots (QDs) are closely related to their surface structure and chemical properties. In this work some ensemble techniques and fluorescence correlation spectroscopy (FCS) were used to study the fluorescence quenching and dialysis process of CdTe QDs. It is found that when some heavy metal ions, such as silver ions (Ag+), quench QDs, the free Ag+ ions bind with bare Te atoms and form the AgTe structure on the surface. The FCS experimental results show that the quenching process is not the gradual reduction of fluorescence intensity of single QDs, but the decrease in the number of bright QDs with the addition of Ag+ ions. In other words, the bright QDs turn into dark directly in the quenching process. It is observed that some dark QDs converse into the bright QDs in the dialysis experiments and the dialysis process can improve the brightness per QDs. Furthermore, the results of FCS and fluorescence spectroscopy illustrate that the increase of the fluorescence quantum yield (QY) is mainly attributed to the removal of excess unreacted Cd-MPA complex and the possible chemical change of the QDs surface in the dialysis process. These new results can help us to further understand the complex surface structure of water-soluble QDs, improve their surface chemical features, and expand their applications in some fields.