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.     

荧光量子点免疫标记法检测炭疽芽孢杆菌

建立了荧光量子点标记-免疫分析技术联用检测炭疽芽孢杆菌的方法.通过抗原抗体反应,结合生物素与亲和素间的特异性相互作用,将QDs特异性标记在炭疽芽孢杆菌上,并利用荧光显微镜和荧光分光光度计进行了验证.采用实验室自制的便携式荧光检测系统对标记QDs的炭疽芽孢杆菌样品进行定量检测.结果表明,在炭疽芽孢杆菌浓度在100～1×1...     

基于水溶性CdTe量子点-绿原酸-血管紧张素Ⅰ 相互作用的荧光可逆调控

在水相中合成了巯基丙酸(MPA)包覆的CdTe量子点(QDs), 采用透射电子显微镜和原子力显微镜对其进行表征. 利用荧光光谱、紫外-可见吸收光谱和红外光谱研究了CdTe QDs与绿原酸(CHA)的相互作用. 结果表明, CHA可显著猝灭CdTe QDs的荧光, 在一定的浓度范围内, 荧光猝灭值与CHA的浓度呈现一定的线性关系. 推断其主要猝灭机理为动态猝灭, 并实现了荧光光谱法测定CHA. 向CdTe QDs-CHA体系中加入血管紧张素Ⅰ(AngⅠ)后, CdTe QDs荧光在一定浓度范围内逐渐恢复, 从而实现了CdTe QDs的荧光可逆调控. CdTe QDs荧光的猝灭与恢复过程对于荧光传感的设计以及荧光可逆调控机理的研究具有指导意义.     

Reversible Control of Fluorescence Based on the Interaction Among CdTe QDs, CHA and Ang I

在水相中合成了巯基丙酸( MPA)包覆的CdTe量子点(QDs),采用透射电子显微镜和原子力显微镜对其进行表征.利用荧光光谱、紫外-可见吸收光谱和红外光谱研究了CdTe QDs与绿原酸(CHA)的相互作用.结果表明,CHA可显著猝灭CdTe QDs的荧光,在一定的浓度范围内,荧光猝灭值与CHA的浓度呈现一定的线性关系.推断其主要猝灭机理为动态猝灭,并实现了荧光光谱法测定CHA.向CdTe QDs-CHA体系中加入血管紧张素Ⅰ (Ang Ⅰ)后,CdTe QDs荧光在一定浓度范围内逐渐恢复,从而实现了CdTe QDs的荧光可逆调控.CdTe QDs荧光的猝灭与恢复过程对于荧光传感的设计以及荧光可逆调控机理的研究具有指导意义.     

NEWS——CdTe量子点/过氧化物酶体系用于灵敏检测酚类化合物和过氧化氢

半导体纳米粒子（量子点,quantum dots,QDs）由于其独特的电子量子限域及尺寸相关的荧光发射性质,已经在电子学,发光装置和生物分析领域中引起了广泛的的兴趣。发展基于QDs的化学及生物分析尤其是传感器是分析化学领域的前沿之一。由于量子点的荧光对其表面非常敏感,物质与量子点表面的相互作用可能会导致荧光的变化;研究发现,电子／空穴受体（如苯醌、对苯胺等）会猝灭量子点的荧光。     

荧光可逆调控研究CdTe量子点-吖啶橙-小牛胸腺DNA的相互作用及分析应用

水相合成了谷胱甘肽(GSH)修饰的CdTe 量子点(QDs). 在PH＝7.4的Tris-HCl缓冲溶液中, 吖啶橙(AO)通过静电引力吸附到GSH-CdTe QDs 的表面, 与GSH-CdTe QDs形成了基态复合物, 导致GSH-CdTe QDs的荧光猝灭. 在GSH-CdTe QDs-AO体系中加入小牛胸腺DNA (ctDNA), ctDNA诱导AO从GSH-CdTe QDs表面脱落嵌入其双螺旋结构中, 导致GSH-CdTe QDs的荧光恢复. 根据GSH-CdTe QDs荧光的猝灭和恢复, 实现了量子点荧光的可逆调控. ctDNA引起GSH-CdTe QDs-AO体系荧光恢复强度与ctDNA浓度成良好的线性关系, 检出限为0.13 ng•mL^－1, 据此提出了简便快捷、准确、高灵敏测定ctDNA的新方法. 还结合共振瑞利散射(RRS)光谱、吸收光谱和原子力显微镜照片研究了GSH-CdTe QDs-AO-ctDNA三者之间的相互作用, 对相互作用机理进行了讨论并提出了相应的作用模型.     

石墨相氮化碳量子点的简易水热制备和荧光性能

本文以线状石墨相氮化碳(Lg-CN)为原料,在无需强酸加入的情况下,利用简单的纯水中的水热反应成功制得了氮化碳量子点(CN QDs),并利用傅里叶变换红外光谱、X射线粉末衍射、透射电镜、X射线光电子能谱等对所得量子点的形貌和结构进行了表征,进而解释了量子点的形成机理;利用紫外-可见吸收光谱和荧光光谱对其光学性质进行了研究。结果发现,所制备的CN QDs具有良好的光学性能,其荧光光谱不仅与激发波长有关,荧光发射位置和强度还受溶液pH的影响,在pH为7时,荧光强度最大。此外,Fe~(3+)对CN QDs的荧光具有良好的猝灭效果,可用于Fe~(3+)的选择性测定。该工作为CN QDs的制备提供了一种新的方法,既可避免繁琐的操作,也可避免强酸等的使用带来的危害。     

活细胞合成量子点等生物纳米标记材料一种"时空耦合"合成新策略

通常,将三维受限的零维无机半导体纳米晶体称为量子点(Quantum dots,QDs).量子点具有优异的荧光性质,在荧光标记、激光、发光二极管、太阳能电池等前沿领域有着十分广泛的应用前景.就生物标记而言,与传统的有机荧光染料和荧光蛋白相比,量子点优异的荧光性质体现在,具有发光颜色可通过不同粒径和(或)组成进行调控、激发光谱宽而连续、发射光谱窄而对称、荧光量子产率高、荧光亮度高、光稳定性好(耐光漂白)等优点.     

微波加热法水相合成梯度合金CdSeS量子点及其环境暴露下荧光稳定性研究

采用微波辅助加热法在水相中一步合成了梯度合金CdSeS量子点,荧光光谱和紫外吸收光谱表明,合成的CdSeS合金量子点具有较高的量子产率(30%左右)。X射线衍射分析和光电子能谱表征证明,合成的CdSeS量子点具有立方晶型,梯度合金结构,内部以CdSe为主,而外部主要以CdS为主;电子透射显微镜下观察到的量子点结晶度高,粒径小(仅2~3 nm),粒度分布均一。在此基础上探讨了所合成的合金量子点在氧化剂过氧化氢、不同的酸碱介质中及350 W氙灯的作用下其荧光光谱的稳定性。结果表明,该合金量子点的光稳定性与CdTe QDs相当,但具有更好的抗氧化性能和抗酸刻蚀性能,具有良好的应用前景。     

CdTe量子点与罗丹明6G荧光共振能量转移体系的构建及机理研究

以巯基乙酸为修饰剂,水相合成不同尺寸的CdTe量子点(QDs),研究不同发射波长的CdTe QDs与罗丹明6G(R6G)之间的荧光共振能量转移(FRET)规律。结果发现,以发射波长为515nm的CdTe QDs为供体与R6G能量转移效率为58.5%,以R6G为供体与发射波长为605nm的CdTe QDs能量转移效率为49.4%,即在CdTe QDs-R6G的FRET体系中,量子点既可作为供体也可作为受体。在此基础上,构建了CdTe QDs(供体)-R6G(第一受体)-CdTe QDs(第二受体)的三元FRET体系,并研究了其双荧光共振能量转移的机理。     

Trichosanthin induced calcium-dependent generation of reactive oxygen species in human choriocarcinoma cells

The type-I ribosome-inactivating protein trichosanthin (TCS) has a broad spectrum of biological and pharmacological activities, including abortifacient, anti-tumor and anti-HIV. We found for the first time that TCS induced the generation of reactive oxygen species (ROS) in human choriocarcinoma cells (JAR cells) at the level of the single cell by using the fluorescent probe 2',7'-dichlorofluorescein diacetate with confocal laser scanning microscopy. TCS-induced ROS formation was shown to be dependent on the presence of extracellular Ca2+ and was further reduced when cytosolic Ca2+ was chelated by BAPTA-AM. The production of ROS increased rapidly after the application of TCS, which paralleled TCS-induced increase in intracellular calcium monitored using fluo 3-AM. Simultaneous observation of the nuclear morphological changes via two-photon laser scanning microscopy and production of ROS via confocal laser scanning microscopy revealed that ROS were involved in the apoptosis of JAR cells. The contribution of ROS was confirmed by experiments in which the antioxidant alpha-tocopherol prevented TCS-induced ROS formation and cell death. The finding that TCS induced calcium-dependent generation of ROS in JAR cells and that ROS were involved in the apoptosis of JAR cells might provide new insight into the anti-tumor and anti-HIV mechanism of TCS.     

Exploring Feasibility for Application of Luminescent CdTe Quantum Dots Prepared in Aqueous Phase to Live Cell Imaging

Due to the quantum confinement, semiconductor quantum dots (QDs) show some unique and fascinating optical properties, such as, sharp and symmetrical emission spectra, high quantum yield (QY), good chemical and photo-stability. These excellent optical prop…     

Preparation of cellulose-based fluorescent materials using Zinc sulphide quantum dot-decorated graphene by a one-step hydrothermal method

Cellulose-based fluorescent materials using Zinc sulphide (ZnS) quantum dot-decorated graphene were prepared by a one-step hydrothermal method. X-ray photoelectron spectroscopy analysis identified the chemical states of Zn, S, C, O, and N in the composite paper. Transmission electron microscopy showed that the graphite oxide was reduced to graphene sheets, and ZnS nanoparticles (<10 nm) were deposited on the surface of these sheets. Scanning electron microscopy indicated that graphene sheets were attached to the surface of paper fibers, and the paper structure and morphology of the fibers were not observably damaged during the hydrothermal reaction. The cellulose-based composite had strong ultraviolet absorption in the range of 200–340 nm, and its main absorption peak was at approximately 296 nm. The band edge emission of photoluminescence spectrum of the composite occurred at 466 nm with an excitation wavelength of 320 nm. The laser scanning confocal microscope image of the composite exhibited an intense blue fluorescence under UV light at 405 nm.     

FSiNPs mediated improved double immunofluorescence staining for gastric cancer cells imaging

A fluorescent silica nanoparticles (FSiNPs) mediated double immunofluorescence staining technique has been proposed for MGC-803 gastric cancer cells imaging by confocal laser scanning microscopy. Anti-CEA antibody and anti-CK19 antibody which can be both bonded to MGC-803 gastric cancer cells were first conjugated to fluorescein isothiocyanate (FITC) doped fluorescent silica nanoparticles (FFSiNPs) and RuBPY doped fluorescent silica nanoparticles (RFSiNPs), respectively. The MGC-803 gastric cancer cells were incubated with the mixture of anti-CEA antibody-conjugated FFSiNPs and anti-CK19 antibody-conjugated RFSiNPs, and subsequently imaged using confocal laser scanning microscopy. With this method, the in vitro cultured MGC-803 gastric cancer cells lines were successfully doubled labeled and distinguished through antigen-antibody recognition, together with the green and red signal of FFSiNPs and RFSiNPs simultaneously obtained without crossreactivity by confocal laser scanning microscopy imaging. By comparison with the conventional double immunofluorescence staining using green-emitting and red-emitting dyes, the photostability of this proposed method for confocal laser scanning microscopy imaging has been greatly improved. Furthermore, the ex vivo imaging of primary MGC-803 gastric cancer cells samples came from the tumor tissues of mice bearing the MGC gastric cancer tumor xenografts by this method have also been explored. The results demonstrate that the method offers potential advantage of photostability for the confocal laser scanning microscopy imaging of MGC-803 gastric cancer cells, and is applicable to the imaging of primary MGC-803 gastric cancer cells from the tumor tissues.     

Fluorescence turn-on chemosensor for Hg~(2+) based on a rhodamine derivative and its application in bioimaging

A fluorescence turn-on chemosensor based on rhodamine B derivative (FD10) has been developed as a highly sensitive chemosensor for Hg2+. A prominent fluorescence enhancement was measured in the presence of Hg2+, which was in agreement with the changes in the absorption spectrum. Furthermore, by means of laser scanning fluorescence microscopy experiments, it was demonstrated that FD10 was cell-permeable and could be used as a fluorescent probe for monitoring Hg2+ in living cells.     

Multisignal chemosensor for Cr(3+) and its application in bioimaging

A multisignal sensor based on rhodamine B with a ferrocene substituent (FD7) has been developed as a highly sensitive chemosensor for Cr(3+). A prominent fluorescence enhancement was found in the presence of Cr(3+), which was accompanied by changes in the absorption spectrum and the electrochemical parameters. Furthermore, by means of confocal laser scanning microscopy experiments, it has been demonstrated that FD7 can be used as a fluorescent probe for monitoring Cr(3+) in living cells.     

异硫氰酸荧光素-溶菌酶的制备及晶体生长预研究

迄今尚未有适用于光源为488 nm激光扫描共聚焦显微镜研究用的溶菌酶. 为此, 用异硫氰酸荧光素作为探针标记了溶菌酶, 测定了溶菌酶标记物的紫外-可见吸收光谱和荧光光谱, 摸索了其晶体的生长条件. 实验结果表明, 在标记过程中异硫氰酸荧光素没有影响溶菌酶的生化性质, 标记后的溶菌酶可用于激光扫描共聚焦显微镜进行后续研究.     

Synthesis and characterization of dually labeled Pickering-type stabilized polymer nanoparticles in a downscaled miniemulsion system

Dual fluorescently labeled polymer particles were prepared in a downscaled Pickering-type miniemulsion system. Stable dispersions were obtained and the size of the hybrid particles could be varied between ca. 180 and 430 nm. Silica nanoparticles were employed as sole emulsifier, which were labeled by a fluorescein dye (FITC) or (encapsulated) quantum dots, and the polymer core was labeled by a perylene derivative. Downscaling of the Pickering-type miniemulsion system is intriguing by itself as it allows the use of precious nanoparticles as emulsifiers. Here, silica particles with a fluorescent core and an overall diameter between 20 and 40 nm were prepared and employed as stabilizer. The dual excitation and emission of both dyes was tested by fluorescence measurements and confocal laser scanning microscopy (cLSM).     

An Anticoagulant Activity System Using Nanoengineered Autofluorescent Heparin Nanotubes

Heparin (HEP) and periodate‐oxidized heparin (O‐HEP) nanotubes were prepared by combining the template method with a layer‐by‐layer (LbL) technique. The tubular structure was obtained and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal laser scanning microscopy (CLSM). O‐HEP is one of the HEP derivatives that contains anticoagulant activity and preserves its ability for other effects. Chitosan (CHI) and O‐HEP have been used to fabricate nanotubes by covalent cross‐linking Schiff base reactions. It is demonstrated that the obtained nanotubes have the significant feature of autofluorescence without the addition of any fluorescent dyes and they retain their anticoagulation activity. Compared with O‐HEP/CHI nanotubes, HEP/CHI nanotubes show high anticoagulation activity and do not have autofluorescence. Furthermore, this method could be extended to other copolysaccharide derivatives for the preparation of autofluorescent nanomaterials.     

Scanning electrochemical microscopy study of laccase within a sol-gel processed silicate film

The enzyme p-diphenol:dioxygen oxidoreductase (laccase, EC 1.10.3.2) was isolated from Cerrena unicolor fungus and embedded in a sol-gel film obtained by acidic condensation of TMOS. The gel was cast to thin films on glass. The laccase-containing silicate films were inspected by confocal laser scanning microscopy (CLSM), scanning force microscopy (SFM) and scanning electrochemical microscopy (SECM). CLSM images in the reflection mode showed aggregates within the silicate films. SECM images in the substrate-generation/tip-collection mode using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as electron donor for laccase showed that the position of aggregates coincides with increased enzymatic activity within the silicate film. The flux from individual aggregates was detected. SECM images in the redox competition mode confirmed the assignment and could exclude that topographic features observed by CLSM and SFM could be the reason for the image contrast. SFM images showed that the aggregates partially dissolve during prolonged exposure to aqueous buffer. The experimental setup allowed following one individual aggregate over time with all three microscopic techniques which enabled the collection of complementing information on morphology and catalytic activity as well as their development over time.