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.     

电化学法合成强荧光CdTe量子点

采用电化学方法产生的H2Te为碲源(Te2-),快速合成了水溶性强荧光的CdTe量子点.该方法具有操作简单、安全、快速廉价和可大量制备等优点.合成过程中考察了合成温度,pH值和配体比例对制备CdTe量子点的影响.在最优化的实验条件下,电化学方法合成的巯基丙酸配位的CdTe荧光量子产率可达到55％;通过紫外可见光谱(UV...     

CdTe量子点-罗丹明6G荧光共振能量转移体系的构建及其应用研究

采用巯基化合物修饰的CdTe量子点构建了量子点(供体)-罗丹明6G(受体)荧光共振能量转移体系, 研究了CdTe量子点与牛血清白蛋白(BSA)的相互作用. 结果表明, CdTe量子点与BSA相互作用后提高了CdTe量子点-罗丹明6G 体系的荧光共振能量转移(FRET)效率, 减小了CdTe量子点和罗丹明6G分子间的距离(r), 证实BSA是通过其色氨酸(Trp)残基与CdTe量子点表面金属发生配位作用而直接结合到量子点表面的.     

碲化镉/马来酰亚胺三嗪纳米杂化材料的制备及其光性能研究

利用低温水相法, 以巯基丙酸(MPA)作为稳定剂制备了碲化镉(CdTe)量子点, 通过马来酰亚胺三嗪(TMT)中的三嗪基团与CdTe量子点表面富含的羧基之间的氢键作用, 得到了分散性能优良的纳米杂化材料. 利用紫外-可见吸收光谱、荧光光谱以及透射电子显微镜等手段对产物的光物理性质和形貌进行了表征. 结果表明, 马来酰亚胺三嗪与CdTe量子点杂化后, CdTe量子点的荧光发射峰有明显的蓝移, 在CdTe量子点和马来酰亚胺三嗪之间存在着能量转移, 并且纳米杂化材料的分散性也有明显的改善.     

颜色可调的高荧光CdTe量子点的水相合成

以亚碲酸钠为碲源,硼氢化钠为还原剂,一步合成了巯基丁二酸(MSA)稳定的CdTe量子点.研究了反应液pH值、镉与碲的摩尔比及镉与巯基丁二酸的摩尔比等实验条件对CdTe量子点体系荧光量子产率的影响,并用荧光光谱、X射线粉末衍射及透射电子显微镜等对其进行了表征.结果表明,CdTe量子点具有闪锌矿结构,形貌呈球状;在pH=1...     

水溶性量子点的制备及其与壳聚糖衍生物的自组装

以3-巯基丙酸(HS-CH2CH2COOH)为稳定剂, 制备了水溶性的碲化镉(CdTe)量子点(QDs), 考察了制备条件对QDs荧光性能的影响及CdTe QDs与壳聚糖及叶酸和聚乙二醇改性的壳聚糖的自组装. 研究发现, 壳聚糖及改性壳聚糖与QDs的复合物荧光强度相对纯的CdTe QDs明显增强, 且QDs被包裹在内核, 复合粒子呈明显的核/壳结构. 改性壳聚糖/QDs复合物较小且尺寸分布更为均一.     

硫脲修饰法制备高发光性能CdTe量子点

通过巯基水解制备了具有优异荧光特性的碲化镉量子点. 详细研究前驱体镉离子与巯基丙酸(MPA)摩尔比、镉离子浓度等制备条件对大尺寸、高量子产率的亲水性碲化镉量子点光学性能的影响. 在不同的水热生长时间下, 可制备出荧光发射峰位于485-660 nm范围内的不同尺寸的碲化镉水溶性量子点, 荧光发射峰半高宽控制在40-75 nm之间, 量子点的最高量子产率(QY)达到了45%. 并利用硫脲缓慢水解和光解释放自由硫离子, 修饰碲化镉表面, 检测修饰后的量子点在12天内光学性能的变化情况. 通过考察硫脲用量对量子点修饰效果, 发现当n(CdTe)/n(thiourea)=1:4(量子点浓度以镉离子浓度计)时, 硫脲对发射峰为505 nm的碲化镉量子点修饰效果最为理想, 量子点荧光强度加强了5倍, 量子产率达到68.3%.     

水相合成近红外CdTe量子点用于体液中硫醇的检测

通过降低反应物中L-半胱氨酸(L-Cys)的比例,在水相快速合成了近红外CdTe量子点,使之对巯基化合物产生荧光响应. 并以此构建了一种基于表面配体缺失的CdTe近红外荧光量子点的巯基探针,为生物样品中的硫醇检测提供简便经济、高灵敏度和高选择性的新方法. 在其它多种氨基酸和生物液体中主要离子、分子共存的情况下,我们所制备的近红外量子点对L-Cys、同型半胱氨酸(Hcy)和谷胱甘肽(GSH)的荧光检测中显示了良好的选择性和灵敏度. 在血清和细胞提取液中,加标5.0 μmol·L^-1硫醇的回收率均在90%～109%范围内. 该方法对L-Cys,Hcy和GSH的检出限(3s)分别为43,46和63 nmol·L^-1.     

3-巯基异丁酸衍生物对碲化镉量子点水相合成的影响

为探索适宜制备粒径分布窄、荧光量子产率高、发光区域在红光至近红外光区段的量子点的巯基酸的条件, 我们研究了三类3-巯基异丁酸(MIBA)衍生物在以亚碲酸钠为碲源的水相法水热制备CdTe量子点中的影响. 这三类衍生物包括设计合成的主链亲水性衍生物3-巯基异丁酰甘氨酸(MIBGly)、3-巯基异丁酰-3-氨基丙酸(MIBAPA)和3-巯基异丁酰天冬氨酸(MIBAsp), 支链亲水性衍生物N-乙酰基半胱氨酸(ACys)和支链疏水性衍生物3-巯基-2-甲基丁酸(MMBA)和3-巯基-2,2-二甲基丙酸(MDMPA). 以这三类MIBA 衍生物为修饰剂时,CdTe量子点均能够保持MIBA体系较窄的荧光半峰宽. 采用亲水性的MIBA衍生物(MIBGly、MIBAPA、MIBAsp和ACys)比采用疏水性的MIBA衍生物(MMBA和MDMPA)更有利于制备发射波长较长的量子点. 采用支链亲水性的MIBA衍生物((ACys)比采用主链亲水性的MIBA衍生物(MIBGly、MIBAPA和MIBAsp)更容易获得高荧光量子产率的量子点.     

半胱胺包被的碲化镉量子点的直接水相制备及其与DNA链接

用半胱胺作为表面修饰剂,在水相中制备了稳定的CdTe纳米量子点。吸收光谱和荧光光谱表明,所合成的CdTe量子点具有优异的发光特性。透射电子显微境(TEM)表征了纳米微粒的结构和粒径分布。与目前较为普遍的用巯基羧酸等其它稳定剂在水相中合成的CdTe量子点相比,半胱胺包被的CdTe量子点的前驱体不需要加热就能受激发出荧光,在100℃加热20min后,荧光明显增强;而巯基羧酸包被的CdTe量子点前驱体受激不能发光。本工作还利用量子点上包被的半胱胺上的氨基,实现了与单链DNA分子的直接链接,链接后溶液的发射峰位红移19nm,荧光强度增强。     

Highly efficient size separation of CdTe quantum dots by capillary gel electrophoresis using polymer solution as sieving medium

In this paper, we present a new method for highly efficient size separation of water-soluble CdTe quantum dots (QDs) based on CGE using polymer solution as sieving medium. CdTe QDs were synthesized in aqueous phase by a chemical route with mercaptopropionic acid as a ligand. In the alkaline solution, CdTe QDs possess negative charges and migrate to the anode in the electric field. In linear polyacrylamide sieving medium, the migration time of CdTe QDs was increased with the size of CdTe QDs. The effects of some factors, such as types, concentrations, and pH of sieving media, on the separation of CdTe QDs were investigated systematically. Highly efficient separation of CdTe QDs was obtained in linear polyacrylamide sieving medium, and collection of fractions was automatically accomplished by CGE technique. Our preliminary results show that CGE technique is an efficient tool for characterization and size-dependent separation of water-soluble nanoparticles. In addition, the fraction collection in CGE may be useful in certain special applications such as fabrication of nanodevices in the future.     

PEG-ylated cationic CdSe/ZnS QDs as an efficient intracellular labeling agent

Quantum dots (QDs) have size-tunable optical properties, such as photostability, strong photoluminescence and a large Stokes-shift, which make it possible to adapt them to various biological applications. In many cases, surface modification of QDs by carboxylate ligands has been extensively studied. However, there have been few applications on QDs modified with a potential cationic ligand such as amine. In this study, we synthesized robust amine-functionalized QDs and modified their surface with poly(ethylene glycol) for long-term stability. These QDs showed an excellent stability over a broad pH-range and remarkable internalization efficiency into living cells.     

Luminescent properties of water-soluble denatured bovine serum albumin-coated CdTe quantum dots

Chemically reduced bovine serum albumin (BSA) has been used to modify the surface of water-soluble CdTe quantum dots (QDs). It is demonstrated that the denatured BSA (dBSA) can be conjugated to the surface of CdTe QDs and thereby efficiently improve the chemical stability and the photoluminescence quantum yield (PL QY) of the QDs. It is inferred that a shell-like complex structure CdTe(x)(dBSA)(1-x) will form on the surface of the CdTe "core", resulting in the enhancement of PL intensity and the blue shift of the PL peak. This study of the effects of pH and dBSA concentration on optical properties of dBSA-coated QDs suggests that, at pH 6-9, the solution of dBSA-coated CdTe QDs can keep substantial stability and fluorescent brightness, whereas further increase of pH value leads to a dramatic decrease in PL QY and chemical stability. On the other hand, too high or too low initial dBSA concentration in the QD solution results in a decrease of PL QY for dBSA-coated CdTe QDs. This study provides a new approach of preparing stable water-soluble QDs with high PL QY and controllable luminescent colors for biological labeling applications.     

1-甲基-3-(2-甲基丙烯酰乙基)-咪唑氯离子液体/ 苯乙烯无规共聚物及其CdTe量子点复合物的合成

以偶氮二异丁腈(AIBN)为引发剂, 通过自由基聚合制备了1-甲基-3-(2-甲基丙烯酰乙基)-咪唑氯离子液体和苯乙烯的无规共聚物P(MMEIM⁺Cl^--co-St). 用红外光谱、核磁共振氢谱和凝胶渗透色谱表征了共聚物的结构. 共聚物的氯仿溶液与巯基乙酸稳定的CdTe量子点水溶液混合, 通过静电相互作用复合组装, 得到澄清透明且稳定的CdTe/P(MMEIM⁺Cl^--co-St)纳米复合物的氯仿溶液. 复合物的紫外吸收光谱、荧光发射光谱和透射电子显微镜的表征结果表明, 量子点均匀分散于共聚物中, 无团聚, 且保持了量子点的荧光性能.     

水溶性的高荧光CdTe/CdSeⅡ型核壳量子点的合成与表征

用L-半胱氨酸(L-cysteine)作为稳定剂,以制备的CdTe量子点为核模板,水相合成了具有近红外发光的Ⅱ型核壳CdTe/CdSe半导体量子点。实验考察了合成温度,核模板的尺寸和组分比等因素对合成高质量的CdTe/CdSe量子点的影响。用紫外-可见吸收和荧光光谱研究了合成的量子点的光学性质。在优化的合成条件下,荧光发射光谱在586～753nm范围连续可调,荧光量子产率高达68%;通过X-射线衍射(XRD),X射线光电子能谱(XPS)和透射电镜(TEM)对合成的Ⅱ型核壳CdTe/CdSe量子点进行了结构和形貌表征。     

CdTe量子点在液体石蜡体系的制备

选用液体石蜡作为高温反应溶剂, 油酸和TOP(三正辛基膦)分别作为镉源和碲源的溶剂兼配体, 利用高温热解法一步合成了高质量的CdTe量子点. 借助紫外-可见吸收光谱、荧光发射光谱、透射电子显微镜及X射线粉末衍射等分析手段对产物的性能进行表征. 结果表明, 反应的温度、反应时间、溶液的浓度、配体的数量均对量子点的生长过程和光学性质有明显影响. 利用这种方法制得的CdTe量子点均为立方闪锌矿结构, 粒径范围为3~7 nm, 最大发射波长在570~720 nm范围内连续可调, 荧光量子产率最高达到65%, 并且具有良好的热稳定性.     

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。     

高灵敏CdTe量子点探针的构建及与金属离子的作用

采用变性的牛血清白蛋白(dBSA)对水相合成的CdTe量子点进行修饰, 构建了高灵敏金属离子探针, 研究了其对重金属离子的检测性能并对机理进行了探讨. 通过优化反应条件, 合成了具有高量子产率的以巯基乙酸为稳定剂的水溶性CdTe量子点, 并采用变性的牛血清白蛋白分别对不同粒径的CdTe量子点进行修饰, 确定变性的牛血清白蛋白与不同粒径量子点之间的最佳比例. 在纯化变性的牛血清白蛋白修饰的量子点(dBSA-QDs)的基础上, 研究了该量子点与不同金属离子的作用. 结果表明, 量子点经修饰后, 其量子产率、 抗光漂白性及稳定性得到显著提高; 而且dBSA-QDs的荧光可被重金属离子有效猝灭, 与巯基乙酸稳定的量子点(TGA-QDs)相比, 检测灵敏度显著提高.     

Multifunctional compact zwitterionic ligands for preparing robust biocompatible semiconductor quantum dots and gold nanoparticles

We describe the synthesis of a series of four different ligands which are used to prepare hydrophilic, biocompatible luminescent quantum dots (QDs) and gold nanoparticles (AuNPs). Overall, the ligands are designed to be compact while still imparting a zwitterionic character to the NPs. Ligands are synthesized appended to a bidentate dihydrolipoic acid- (DHLA) anchor group, allowing for high-affinity NP attachment, and simultaneously incorporate tertiary amines along with carboxyl and/or hydroxyl groups. These are placed in close proximity within the ligand structure and their capacity for joint ionization imparts the requisite zwitterionic nature to the nanocrystal. QDs functionalized with the four different compact ligands were subjected to extensive physical characterization including surface charge, wettability, hydrodynamic size, and tolerance to a wide pH range or high salt concentration over time. The utility of the compact ligand coated QDs was further examined by testing of direct conjugation to polyhistidine-appended protein and peptides, aqueous covalent-coupling chemistry, and the ability to engage in F?rster resonance energy transfer (FRET). Conjugating cell penetrating peptides to the compact ligand coated QD series facilitated their rapid and efficient cellular uptake, while subsequent cytotoxicity tests showed no apparent decreases in cell viability. In vivo biocompatibility was also demonstrated by microinjecting the compact ligand coated QDs into cells and monitoring their stability over time. Inherent benefits of the ligand design could be extended beyond QDs as AuNPs functionalized with the same compact ligand series showed similar colloidal properties. The strong potential of these ligands to expand NP capabilities in many biological applications is highlighted.