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．     

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。     

CdTe量子点荧光猝灭法测定四环素

以巯基乙酸为稳定剂水热法制备Cd Te量子点,考察不同条件下四环素对Cd Te量子点的荧光猝灭作用,建立一种荧光测定四环素含量的新方法。该方法的线性范围为1.0²0.0μg/m L,工作曲线为ΔF=2.308 2+9.679 3c(μg/m L),相关系数r为0.999 5,检出限(3SD/斜率)为0.025μg/m L。该方法应用于实际样品中四环素含量的测定,相对标准偏差<2.3%,回收率在97.5%20.0μg/m L,工作曲线为ΔF=2.308 2+9.679 3c(μg/m L),相关系数r为0.999 5,检出限(3SD/斜率)为0.025μg/m L。该方法应用于实际样品中四环素含量的测定,相对标准偏差<2.3%,回收率在97.5%¹03.3%。     

CdTe量子点荧光猝灭法测定四环素

以巯基乙酸为稳定剂水热法制备Cd Te量子点,考察不同条件下四环素对Cd Te量子点的荧光猝灭作用,建立一种荧光测定四环素含量的新方法。该方法的线性范围为1.0~20.0μg/m L,工作曲线为ΔF=2.308 2+9.679 3c(μg/m L),相关系数r为0.999 5,检出限(3SD/斜率)为0.025μg/m L。该方法应用于实际样品中四环素含量的测定,相对标准偏差2.3%,回收率在97.5%~103.3%。     

CdTe量子点的水相制备

在水相中以巯基丙酸作为稳定剂,合成出具有不同荧光发射波长的CdTe量子点（QDs）,利用紫外吸收光谱（UV）、荧光光谱（FS）以及透射电子显微镜（TEM）对CdTeQDs进行了表征。研究了反应温度及pH值对所制备的CdTeQDs光学性质的影响。实验结果表明,合成CdTeQDs的最佳温度为96℃,pH值为10,且随着时间的增加量子点的粒径增大。     

量子点的应用及研究进展

量子点因具有宽的激发光谱、窄的发射光谱、高的荧光量子产率和寿命长等特殊的性质,是一种比荧光染料分子更理想的生物探针。详细介绍了国内外的几种量子点制备方法及其表面修饰,另外综述了量子点在生物学的应用。     

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。     

CdTe/CdS量子点荧光猝灭法测定十六烷基三甲基溴化铵

以巯基乙酸为稳定剂,在水溶液中合成了CdTe/CdS量子点,基于十六烷基三甲基溴化铵(CTAB)与CdTe/CdS量子点的荧光猝灭作用,建立了用CdTe/CdS量子点作为荧光探针测定水中微量十六烷基三甲基溴化铵的新方法。考察了缓冲溶液、pH和量子点浓度等因素对体系荧光强度的影响。结果表明,在pH为6.8的磷酸二氢钾-硼砂缓冲溶液中,当CdTe/CdS量子点浓度为3.75×10-4mol/L时,体系的相对荧光强度与十六烷基三甲基溴化铵的浓度在5.49×10-7~4.12×10-5mol/L范围内呈现良好的线性关系,相关系数为0.999 7,检出限为5.43×10-8mol/L。方法应用于水中微量十六烷基三甲基溴化铵测定,回收率在96.7%~101.7%。     

CdTe量子点化学发光法检测多巴胺

制备了巯基丙酸包裹的CdTe量子点,并研究了其在共氧化剂过氧化氢的参与下,碱性介质氢氧化钠中的化学发光行为。结果表明,在过氧化氢为共氧化剂时,CdTe量子点具有很强的化学发光信号。探讨了过氧化氢浓度、氢氧化钠浓度、量子点浓度以及进样顺序对CdTe量子点化学发光信号的影响。利用多巴胺对CdTe量子点/NaOH-过氧化氢发光体系具有抑制作用实现对多巴胺的灵敏检测。该方法在5.0×10~(-5)~1.0×10~(-3)mol·L~(-1)范围内呈良好的线性关系,为化学发光方法检测多巴胺提供了新的方法。     

水溶性CdTe量子点的合成及表征

量子点具有独特的光学特性,被越来越广泛地应用于生物研究和医学临床等领域。本文采用水相合成法,制备了不同表面修饰CdTe量子点,并运用紫外-可见吸收光谱、荧光发射光谱、X射线衍射(XRD)、X射线光电子能谱(XPS)以及透射电子显微镜(TEM)等,对所合成的量子点进行了表征,并探讨了pH值对量子点制备的影响。     

Enhanced electrochemiluminescence of CdTe quantum dots with carbon nanotube film and its sensing of methimazole

A novel analytical method was reported based on electrochemiluminescence (ECL) of CdTe quantum dots (QDs) using carbon nanotube (CNT) modified glass carbon (GC) electrode. It was found that the CNT film on the GC electrode could greatly enhance the ECL intensity of CdTe QDs dispersed in aqueous solution, and the ECL peak potential and ECL onset potential both shifted positively. Influences of some factors on the ECL intensity were investigated using CNT modified GC electrode, and a high sensitive method for the determination of methimazole was developed under the optimal conditions. The ECL intensity decreased linearly in the concentration range of 1.0 × 10⁻⁹ to 4.0 × 10⁻⁷ M for methimazole with the relative coefficient of 0.995, which showed finer sensitivity than that at bare electrode. Thus, CNT modified electrode would have a great merit to expand the application of QD ECL.     

Luminescent properties of CdTe quantum dots synthesized using 3-mercaptopropionic acid reduction of tellurium dioxide directly

A facile one-step synthesis of CdTe quantum dots (QDs) in aqueous solution by atmospheric microwave reactor has been developed using 3-mercaptopropionic acid reduction of TeO₂ directly. The obtained CdTe QDs were characterized by ultraviolet–visible spectroscopy, fluorescent spectroscopy, X-ray powder diffraction, multifunctional imaging electron spectrometer (XPS), and high-resolution transmission electron microscopy. Green- to red-emitting CdTe QDs with a maximum photoluminescence quantum yield of 56.68% were obtained.     

Facile preparation of highly luminescent CdTe quantum dots within hyperbranched poly(amidoamine)s and their application in bio-imaging

A new strategy for facile preparation of highly luminescent CdTe quantum dots (QDs) within amine-terminated hyperbranched poly(amidoamine)s (HPAMAM) was proposed in this paper. CdTe precursors were first prepared by adding NaHTe to aqueous Cd²⁺ chelated by 3-mercaptopropionic sodium (MPA-Na), and then HPAMAM was introduced to stabilize the CdTe precursors. After microwave irradiation, highly fluorescent and stable CdTe QDs stabilized by MPA-Na and HPAMAM were obtained. The CdTe QDs showed a high quantum yield (QY) up to 58%. By preparing CdTe QDs within HPAMAM, the biocompatibility properties of HPAMAM and the optical, electrical properties of CdTe QDs can be combined, endowing the CdTe QDs with biocompatibility. The resulting CdTe QDs can be directly used in biomedical fields, and their potential application in bio-imaging was investigated.     

Transparent,fluorescent, and mechanical enhanced elastomeric composites formed with poly (styrene‐butadiene‐styrene) and SiO2‐hybridized CdTe quantum dots

Transparent poly(styrene‐butadiene‐styrene) (SBS)‐quantum dots (QDs) composites (SBS/CdTe QDs) that simultaneously possess strong photoluminescence (PL) and enhanced mechanical properties are presented for the first time based on the facile blending of SiO₂‐hybridized CdTe QDs with SBS. UV–vis spectrum and fluorescence measurement show that SBS/CdTe QDs composites exhibit good optical properties. The results of transmission electron microscopy show good dispersion of CdTe QDs in the SBS matrix. The results of dynamic mechanical thermal analysis indicate that the micro‐phase separated structure of the SBS is exist in the composites, and the presence of CdTe QDs can lead to an decrease of glass transition temperatures of polybutadiene (PB) and polystyrene(PS) domains. In addition, mechanical tests reveal that the addition of CdTe QDs is a useful approach to improve the mechanical properties of SBS. Meanwhile, the fluorescent photographs taken under ultraviolet light prove that SBS/CdTe QDs composites possess strong PL. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Direct electrochemiluminescence of CdTe quantum dots based on room temperature ionic liquid film and high sensitivity sensing of gossypol

A new method with high sensitivity was developed to determine gossypol content using CdTe quantum dot (QD) electrochemiluminescence (ECL) with a room temperature ionic liquid (RTIL) modified glassy carbon (GC) electrode. It was found that use of RTIL film on the GC electrode can greatly enhance the ECL intensity of CdTe QDs, and the ECL peak potential and ECL onset potential were both shifted positively. Under optimal conditions, the quenching effect of gossypol on the ECL emission of CdTe QDs was observed, and ECL intensity showed a good linear relationship in the gossypol concentration range of 5.0 × 10⁻⁷ to 5.0 × 10⁻⁹ M with a detection limit of 5.0 × 10⁻⁹ M. The proposed method was used to detect gossypol in cottonseed oil with satisfactory results. As a result, the introduction of an RTIL-modified electrode can extend the analytical applications of QD ECL systems.     

Graphene quantum dots doping SnO2 for improving carrier transport of perovskite solar cells

SnO₂ is recognized as an excellent electron transport layer. However, it does not possess the optimal morphology required by perovskite photovoltaic devices, and the conduction band of SnO₂ cannot match well with perovskite conduction bands. In the present study, we introduced graphene quantum dots (GQDs) into SnO₂. The results show that the introduction of graphene quantum dots effectively improved the morphology of the SnO₂ film, reduced the roughness of the surface, and increased the ohmic contact between the SnO₂ and perovskite layer. In addition, the conductivity of the SnO₂ film was improved, thereby facilitating the transfer of electrons. The optimized SnO₂: GQDs layer reduced the density of defect state, suppressed the pinholes appearance to a certain extent, and facilitated the extraction of electrons, thereby ultimately improving the FF, and increasing the efficiency of the perovskite photovoltaic device.