量子点在法庭科学手印显现中的研究进展

随着纳米技术的进步,纳米颗粒正在被逐步应用到法庭科学领域的手印检验之中。近年来,半导体量子点因其良好的荧光特性而备受国内外法庭科学家的推崇,但大多数半导体量子点具有毒性,且会对环境造成污染,这些问题制约了半导体量子点在法庭科学领域中的应用。与传统有机染料和金属内核的半导体量子点相比,碳量子点具有毒性低、污染小、生物相容性优异的特点,现已应用于医学、生物、化学等多个领域。本文综述了半导体量子点在手印显现中的应用,介绍了碳量子点的研究进展,并指出碳量子点显现手印是今后法庭科学领域的重要研究方向。     

利用水相合成的量子点标记木瓜蛋白酶的研究

利用半导体纳米粒子 (也称半导体量子点 ,Quantum Dots,以下简称 QDs)和表面修饰技术制备的半导体荧光探针具有极其优良的光谱特征和光化学稳定性 [1] .自 1 997年以来 ,随着量子点制备技术的不断提高 ,量子点在生物医学方面已有应用 . 1 998年 ,Alivisatos[1] 和 Nie[2 ] 两个研究小组分别将结合了生物分子的 QDs作为荧光探针应用于生物体系 ,开创了纳米粒子应用的新领域 .最近 Nie等 [3 ]在利用量子点编码生物分子的研究中取得了突破性进展 .目前 ,纳米粒子与生物分子的连接以共价键方式相结合最为常见 [1,2 ,4 ,5] ,而且在这些应用中…     

荧光量子点的水相合成及其在化学和生物分析中的应用

荧光量子点(又称为半导体纳米晶体)是一种新兴的无机发光材料, 由于其具有独特的结构和光电性能, 在发光二极管、太阳能电池及生命科学等领域有广泛的应用. 目前, 有机相合成法和水相合成法已被成功地用于荧光量子点的合成. 与有机相合成法相比, 水相合成量子点方法简单、绿色且廉价, 合成的量子点水溶性好, 在生物医学等领域具有很好的应用前景. 本文主要介绍荧光量子点的水相合成方法及其在化学和生物分析中的应用, 并对其发展趋势进行了展望.     

硅量子点合成方法的研究进展

与传统的Ⅱ-Ⅵ族和Ⅲ-Ⅴ族半导体化合物相比,硅量子点性质独特,不仅无毒无害、环境友好,而且储量丰富,可以大量生产,目前已在光电子学、太阳能转换、生物传感器、荧光探针等方面具有广泛的应用.本文作者对液相合成方法、高温气相还原法和热分解法制备硅量子点进行了综述,并对硅量子点在光电器件领域的应用前景进行了展望.     

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.     

基于量子点的检测技术在法庭科学物证鉴定中的应用研究进展

由于具有独特的纳米尺寸效应和高灵敏度的光电效应,碳量子点以及半导体量子点技术已经被广泛应用于材料科学、生物和医药等领域。本文在简述量子点结构、合成方法等基础上,着重介绍了基于量子点的检测技术在法庭科学领域毒物、毒品和微量物证鉴定中的应用,旨在分析基于量子点的检测技术研究与应用现状,展望其在法庭科学领域中的应用前景。     

QDs标记免疫调节肽及其与T细胞作用的表征

量子点是直径为1~10 nm的球形半导体纳米晶体, 也被称为半导体量子点, 简称QDs. 与有机荧光染料相比, QDs具有激发光谱单一、 荧光谱线窄、 发光效率高、 发光颜色可调、 可进行多色联合标记, 并且光稳定性好等优点, 所以量子点是非常有前途的生物标记物[^1,2]. 研究结果表明, 量子点可以与许多生物分子如蛋白质、多肽、核酸及小分子配体等偶联. 现已有许多关于量子点标记生物分子的报道, 如用量子点标记木瓜蛋白酶、 胰蛋白酶、 天花粉蛋白和表皮生长因子等^[3-5].用量子点标记生物分子作为荧光探针已成功地应用于多种生物分析, 如DNA杂交监测、 免疫分析和用QDs检测ATP推动的反应等^[4,6,7]. 目前, 对量子点标记生物分子的报道多为对大分子蛋白质的标记, 而对小分子肽标记的报道却很少.     

量子点抗体偶联技术研究进展

量子点是一种半导体纳米晶体,其具有激发光谱宽、发射光谱窄,光稳定性好,良好的生物相容性等各种优越的性能,目前广泛应用于生物标记、生物传感和生物成像的研究中。量子点生物学应用中最为关键的一步,是如何将抗体等生物大分子有效的偶联于量子点表面并保持其生物活性。近年来,尽管对量子点的制备方法和生物学应用进行了较为深入的研究,但量子点和生物分子之间偶联技术的综述还少见报道。本文从非共价偶联技术和共价偶联技术两个方面对各种量子点抗体偶联技术的特性进行分析,也对未来量子点生物学应用中将会遇到的挑战和发展趋势进行展望。     

新型荧光物质——量子点在生命科学领域的应用研究进展

半导体荧光量子点因其特有的荧光性质而成为生命科学领域生物标记材料研究的前沿内容。本文综述了高荧光效率量子点的各种制备方法以及在生命科学领域应用的研究进展。     

基于量子点标记的适配体技术在分析检测中的研究进展

由于光学性质独特,量子点成为近年来发展起来的极具应用前景的半导体纳米材料,作为荧光标记物在生物和化学领域备受关注。随着生物技术的发展,适配体以其高特异性、强亲和力等特点被用作生物探针或生物传感元件,在分析检测中得到广泛应用。将量子点与适配体结合构建的纳米生物识别体系,互补结合适配体和量子点的特殊性质,可实现对靶标物质的超灵敏、高选择性及快速检测。本文概述了量子点的合成、修饰及其与适配体的偶联,重点介绍了近几年基于量子点标记的适配体技术在生物分子、病原微生物、细胞、真菌毒素等方面的应用,并展望了该技术在分析检测领域的发展趋势。     

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.     

Surface Chemistry Studies of Quantum Dots (QDs) Modified with Surfactants

Since luminescent CdSe quantum dots (QDs) have shown great potential in biological labeling, the surface chemistry behavior of QDs at interfaces is of great research interest. In the present study, CdSe QDs with green luminescence were modified with hydrophobic chains of varying lengths [from C6 to C18]. These modified QDs can be utilized to form stable monolayers at the air/water interface. Surface pressure-area isotherms of modified QDs have been measured and limiting molecular areas have also been extrapolated in order to analyze the size of the QDs. UV absorption spectra of modified QDs at various surface pressures were also determined. Surface chemistry, as well as the topographic properties, of modified QDs in Langmuir and L-B films was discussed.     

量子点与蛋白质相互作用热力学

量子点(QDs)具有宽激发窄发射、量子产率高、发射波长可调和抗光漂白等优异的光学性质,因而在生物医学成像与示踪、生物传感等方面有着广泛的应用前景。量子点进入生命体系后,首先会遇到蛋白质,量子点与蛋白质之间发生相互作用后,蛋白质的结构和功能会因此发生变化,量子点的性能及应用也会发生改变。研究量子点与蛋白质的相互作用规律,可以为量子点的精细设计、高效应用以及生物安全性评价提供理论依据。本文在总结国内外相关文献和本课题组工作的基础上,介绍了量子点与蛋白质相互作用的热力学方法;重点从热力学角度揭示量子点与蛋白质相互作用的机制。     

Controllable Blinking‐to‐Nonblinking Behavior of Aqueous CdTeS Alloyed Quantum Dots

Semiconductor quantum dots (QDs) are very important optical nanomaterials with a wide range of potential applications. However, the blinking of single QDs is an intrinsic drawback for some biological and photoelectric applications based on single‐dot emission. In this work, we systematically investigated the effects of certain synthetic conditions on the blinking behavior of aqueous CdTeS alloyed QDs, and observed that blinking behaviors of QDs were able to be controlled by the structure and concentration of the thiol compounds that were used as surface ligands. In optimal conditions, completely nonblinking QDs were prepared using certain thiol ligands as stabilizers in aqueous phase. The suppressed blinking mechanism was mainly attributed to elimination of QDs surface traps by coordination of thiol ligands with vacant Cd atoms, formation of appropriate CdS coating on QDs, and controlling the growth dynamics of QDs. Nonblinking QDs show high quantum yield, small size, and good solubility, and will be applied to some fields that were previously limited by blinking of traditional QDs.     

配体对CdTe量子点与BSA的选择性相互作用的影响

以巯基乙酸(TGA)、巯基丙酸(MPA)、巯基甘油(TG)、L-半胱氨酸(L-cys)和谷胱甘肽(GSH)等5种巯基分子为稳定剂, 水相合成了5种CdTe量子点. 以牛血清白蛋白(BSA)作为靶分子, 通过吸收光谱、荧光光谱和时间分辨荧光动力学等手段研究了各种配体分子稳定的CdTe量子点与BSA的直接相互作用. 结果表明, 5种量子点均能有效猝灭BSA的荧光, 其猝灭程度按配体次序为GSH>L-cys>TGA>TG>MPA; 而BSA对不同配体稳定的CdTe量子点的荧光光谱的影响则具有明显的选择性. BSA对TGA-CdTe和MPA-CdTe量子点的荧光先敏化增强而后猝灭下降; L-cys分子由于同时具有氨基和羧基而与BSA的相互作用较强, 因此BSA能显著猝灭L-cys-CdTe量子点的荧光; 而BSA对TG-CdTe量子点的荧光猝灭程度较小; GSH分子的空间效应使GSH-CdTe量子点的荧光被BSA猝灭的程度最小. 吸收光谱和时间分辨荧光动力学研究表明, 5种量子点与BSA之间的相互作用均为静态过程. 探讨了量子点的配体分子结构与蛋白质的相互作用机理.     

Synthesis of NAC capped near infrared-emitting CdTeS alloyed quantum dots and application for in vivo early tumor imaging

The synthesis of water-soluble near-infrared (NIR)-emitting quantum dots (QDs) has recently received extensive attention for non-invasive detection of biological information in living subjects. Highly fluorescent CdTeS alloyed QDs for biological application are introduced in this paper. QDs were synthesized by a hydrothermal method and coated with N-acetyl-l-cysteine (NAC) as both bioactive ligand and sulfur source for biocompatibility and biological stability. The optical properties, morphology and structure of CdTeS alloyed QDs were characterized. The in vitro and in vivo toxicity was intensively investigated. Furthermore, the dynamics and bio-distribution of CdTeS alloyed QDs on living mice were studied. To explore biomedical application, folate-polyethylene glycol (FA-PEG) was used to decorate the CdTeS alloyed QDs (FP-CdTeS QDs) for targeted imaging of tumors over-expressing the folate receptor (FR). The tumor targeting capability of FP-CdTeS QDs on tumor bearing nude mice was demonstrated. The results showed that the prepared CdTeS QDs have excellent optical properties and low toxicity, which makes them an ideal inorganic material for biomedical imaging. In addition, the folate-PEG conjugated NIR-QDs displayed good biocompatibility as well as excellent sensitivity and specificity for optical imaging of tumors which can extend the application of CdTeS QDs.     

Studies on bioconjugation of quantum dots using capillary electrophoresis and fluorescence correlation spectroscopy

In this paper, we systematically investigated the conjugation of quantum dots (QDs) with certain biomolecules using capillary electrophoresis (CE) and fluorescence correlation spectroscopy (FCS) methods. Commercial QDs and aqueous-synthesized QDs in our lab were used as labeling probes, certain bio-macromolecules, such as proteins, antibodies, and enzymes, were used as mode samples, and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysulfo-succinimide (Sulfo-NHS) were used as linking reagents. We studied the effects of certain factors such as the isoelectric points (pIs) of bio-macromolecules and buffer pH on the bioconjugation of QDs, and found that the pIs of bio-macromolecules played an important role in the conjugation reaction. By the optimization of the buffer pH some proteins with different pIs were efficiently conjugated with QDs using EDC and Sulfo-NHS as linking agents. Furthermore, we on-line investigated the kinetic process of QDs-bioconjugation by FCS and found that the conjugation reaction of QDs with protein was rapid and the reaction process almost completed within 10 min. We also observed that QDs conjugated with proteins were stable for at least 5 days in phosphate buffer. Our work described here will be very helpful for the improvement of the QDs conjugation efficiency in bioapplications.     

新型低毒AgInS2量子点的制备和表征以及对肿瘤细胞的成像

在水相中快速合成AgInS2( AIS)量子点,并对其紫外-可见吸收光谱及荧光发射光谱进行了表征,通过电感耦合等离子体发射光谱仪分析了其元素组成,采用高分辨透射电镜观察其形貌与分布,并验证了它相对于传统的CdTe量子点在光稳定性和细胞毒性方面的优势。在AgInS2表面连接了叶酸实现了对肿瘤细胞的靶向成像。     

Preparation and characterization of thiacalix[4]arene coated water-soluble CdSe/ZnS quantum dots as a fluorescent probe for Cu2+ ions

Highly fluorescent water-soluble CdSe/ZnS (core/shell) quantum dots (QDs) as a fluorescent Cu2+ ion probe were synthesized using thiacalix[4]arene carboxylic acid (TCC) as a surface coating agent. Hydrophobic trioctylphosphine oxide (TOPO) capped CdSe/ZnS QDs were overcoated with TCC in tetrahydrofuran at room temperature, and deprotonation of the carboxyl groups of TCC resulted in the formation of water-soluble QDs. The surface structure of the QDs was characterized by using transmission electron microscopy (TEM) and fluorescence correlation spectroscopy (FCS). TEM images showed that TCC-coated QDs were monodispersed with the particle size (core-shell moiety) of approximately 5 nm. Hydrodynamic diameter of the TCC-coated QDs was determined to be 8.9 nm by FCS, showing that the thickness of the surface organic layer of the QDs was approximately 2 nm. These results indicate that the surface layer of TCC-coated QDs forms a bilayer structure consisting of TOPO and TCC molecules. TCC-coated CdSe/ZnS QDs were highly fluorescent (quantum yield, 0.21) compared to the QDs surface-modified with mercaptoacetic acid and mercaptoundecanoic acid. Fluorescence of the TCC-coated QDs was effectively quenched by Cu2+ ions even in the presence of other transition metal ions such as Cd2+, Zn2+, Co2+, Fe2+, and Fe3+ ions in the same solution. The Stern-Volmer plot for the fluorescence quenching by Cu2+ ions showed a linear relationship up to 30 microM of Cu2+ ions. The ion selectivity of TCC-coated QDs was determined by measurements of fluorescence responses towards biologically important transition metal ions (50 microM) including Fe2+, Fe3+, Co2+>Zn2+, Cd2+. The fluorescence of TCC-coated QDs was almost insensitive to other biologically important ions such as Na+, K+, Mg2+, and Ca2+, suggesting that TCC-coated QDs can be used as a fluorescent Cu2+ ion probe for biological samples. A possible quenching mechanism by Cu2+ ions was also discussed on the basis of a Langmuir-type adsorption isotherm.     

CdTe量子点与蛋白质相互作用的荧光猝灭效应

本文在水热法合成水溶性CdTe及核壳结构CdTe/CdS量子点的基础上,分别研究了细胞色素c对CdTe量子点及CdTe/CdS核壳量子点荧光的猝灭效应和CdTe量子点对牛血清白蛋白荧光的猝灭效应,并阐述了猝灭机理。结果显示,细胞色素c对CdTe量子点的荧光猝灭效应具有一定的粒径依赖性,粒径越小,猝灭效应越强;细胞色素c对CdTe/CdS核壳量子点的猝灭效应比对CdTe量子点的更强,揭示了受激电子的表面传递机理。CdTe量子点通过松散牛血清白蛋白的螺旋结构而猝灭其荧光。