水相合成CdX (X＝Te, Te/CdS, Te/ZnS)红色量子点及毒性效应

分别以巯基乙酸(Mercaptoacetic Acid, MA)、还原型谷胱甘肽(Glutathione, GSH)为稳定剂在水相中直接合成了巯基乙酸CdTe (CdTe-MA)、红色巯基乙酸CdTe/CdS (CdTe/CdS-MA)、巯基乙酸CdTe/ZnS (CdTe/ZnS-MA)及谷胱甘肽CdTe (CdTe-GSH)量子点. 其中, CdTe-GSH量子点的量子产率可达47.3%. 体外溶血实验证实CdTe/ZnS-MA和CdTe-GSH量子点的溶血率较CdTe-MA和CdTe/CdS-MA低, 浓度为0.05 mmol/L的量子点溶血率＜5%, 达到了生物医用材料的要求. 活体实验证实: 通过尾静脉方式把量子点注入小鼠体内后, 荧光显微镜观察发现高剂量的量子点(0.4 mmol/10 g)在体内主要在心、肝、脾、肾组织中分布较多, 且引起不同程度的组织病变.     

高量子产率水溶性CdTe量子点的制备与表征

以巯基乙酸(HSCH2 COOH,TGA)为稳定剂,在水相中合成高量子产率CdTe量子点(QDs),产率达68%.用紫外.可见分光光度计、荧光分光光度计、红外光谱仪、透射电子显微镜等对制备的样品进行表征.结果表明:CdTe Ods紫外吸收峰及荧光发射峰均随回流时间延长而红移,即粒径在不断增大;荧光发射峰窄而对称,表明QDs分散性好、大小较均一,半峰宽随回流时间延长而逐渐变宽,表明粒径在增大的同时粒径分布范围也变宽;从TEM及紫外.可见光谱推算,可知其粒径约为3 nm;红外光谱图说明作为稳定剂的巯基乙酸对QDs表面起到修饰作用.     

水溶性CdTe量子点的合成及影响因素研究

本文以巯基乙酸(TGA)为稳定剂,在水相中合成了高荧光CdTe量子点.其荧光发射波长在507 ～ 628nm范围内可调,最窄半峰宽37 nm,粒径约3.4nm,量子产率达42.1％.本实验在固定前躯体配比不变的情况下,考察了前躯体中镉离子的浓度、pH及回流时间对CdTe生长的影响.并用透射电子显微镜(TEM),荧光分光光度计(FS),X射线衍射仪(XRD)等手段对制备的量子点进行了表征.结果表明:CdTe量子点的尺寸随回流时间而增长;反应的pH对量子点的荧光强度有显著影响;镉离子的浓度越大,量子点的生长速度越快,荧光强度却随之降低.     

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CdTe量子点对人宫颈癌细胞(SiHa)的毒性研究

以人宫颈癌细胞(SiHa)为模型,采用WST-1试剂法对实验室合成的水溶性CdTe量子点的细胞毒性进行了考察.研究发现,CdTe量子点毒性具有明显的尺寸效应、时间效应和剂量效应,且量子点表面状态对其毒性有较大影响.采用生物大分子变性牛血清白蛋白(dBSA)修饰量子点,其毒性与裸量子点无明显差异;经巯基聚乙二醇(thio...     

不同尺寸量子点-菲啰啉体系对镉检测的影响

采用不同尺寸的高荧光量子产率、单分散性水溶性CdTe量子点(QDs)与菲啰啉(Phen)配体结合,组装成QDs-Phen荧光探针。Phen对不同尺寸量子点荧光猝灭效率以及光致空穴转移效率表现为:2.3 nm的绿色CdTe量子点2.8 nm的黄色CdTe量子点3.3 nm的橙色CdTe量子点;不同粒径QDs-Phen荧光探针对Cd~(2+)的检测发现:粒径2.3 nm QDs-Phen荧光探针对Cd~(2+)检测线性范围为0.02~0.6μmol/L,检测限为0.01 mol/L;粒径2.8 nm QDsPhen荧光探针对Cd~(2+)检测线性范围为0.1 nmol/L~1.0μmol/L,检测限为0.05 nmol/L;而粒径3.3 nm QDs-Phen荧光探针对Cd~(2+)检测线性范围为0.2 nmol/L~1.5μmol/L,检测限为0.1 nmol/L。为选择合适粒径量子点的荧光探针对Cd~(2+)实际检测提供依据。     

水合肼还原二氧化碲水相合成CdTe量子点

以巯基乙酸为稳定剂, 氯化镉为镉源, 二氧化碲为碲源, 水合肼为还原剂, 一步合成了CdTe量子点. 研究了反应时间、 碲与镉的摩尔比及巯基乙酸与镉的摩尔比等实验条件对CdTe量子点生长过程的影响. 采用荧光光谱、 X射线粉末衍射和透射电子显微镜等对量子点的性能进行了表征. 结果表明, 反应时间及反应物的相对用量对量子点的生长和荧光光谱有明显影响, 所得CdTe量子点具有立方晶型, 发光颜色从绿色到红色连续可调, 荧光量子产率可达26%.     

镉(Ⅱ)-半胱氨酸配合物对CdS量子点的荧光增强作用及其在离子检测中的应用

合成了弱配体柠檬酸三钠修饰的CdS量子点(Cit-CdS QDs), 透射电子显微镜表征结果表明, Cit-CdS QDs的粒径分布均匀(4~6 nm), 分散性好。 研究了金属离子(银(Ⅰ)离子、镉(Ⅱ)离子)、巯基化合物(巯基乙酸、半胱氨酸)以及金属离子(银(Ⅰ)离子、镉(Ⅱ)离子)与巯基化合物形成的配合物对Cit-CdS QDs荧光的影响。 发现金属离子(银离子、镉离子)与巯基化合物(巯基乙酸、半胱氨酸)形成的水溶性配合物可以显著增强Cit-CdS QDs的荧光, 配合物对Cit-CdS QDs的增强程度比单独的金属离子或巯基化合物均要高, 而且配合物修饰的CdS QDs对铜(Ⅱ)离子的响应要高于单独用金属离子或巯基化合物修饰的量子点。 建立了铜(Ⅱ)离子高灵敏度荧光检测方法, 该方法检测范围宽(1.0×10^-8~1.0×10^-6 mol/L), 检测限低(1.0×10^-9 mol/L)且具有很好的选择性, 拓展了配合物作为量子点修饰剂的应用。     

高性能CdTe/CdS核壳型量子点的制备及应用于小麦面粉中呕吐毒素的荧光免疫检测研究

量子点荧光免疫法的广泛应用迫切需要提高量子点的发光强度和抗体的稳定性. 分别采用巯基乙酸和谷胱甘肽作稳定剂, 水相合成CdTe量子点, 再包覆CdS制备核壳型CdTe/CdS量子点. 以EDC/NHS作交联剂将CdTe/CdS量子点标记到呕吐毒素抗体上, 然后用牛血清蛋白封闭抗体. 研究发现, 谷胱甘肽稳定剂优于巯基乙酸. 与CdTe量子点相比, 谷胱甘肽修饰的CdTe/CdS量子点其荧光的强度和稳定性分别提高6倍和2倍以上. 谷胱甘肽碳链较长, 减少了量子点对抗体尤其是活性位点处的空间构型影响, 从而大大提高抗体的稳定性. 监测不同储藏时间(4 ℃)的CdTe/CdS量子点-抗体偶联复合物与呕吐毒素免疫反应前后荧光强度变化值, 结果显示抗体至少可以稳定7 d. 基于谷胱甘肽稳定的高性能CdTe/CdS量子点, 我们建立了一种新的呕吐毒素荧光免疫检测方法. 呕吐毒素浓度在0～0.9 ng•mL^－1之间相对荧光强度呈线性关系, 相关系数(R²)为0.9992, 检出限是0.038 ng•mL^－1. 方法的灵敏度高于文献报道的其它方法, 如GC-ECD, HPLC和HPLC-MS, 已成功应用于小麦面粉样品中痕量呕吐毒素的测定.     

CdX(X=Se,Te,Te/ZnS)量子点脂质体的制备及毒性比较

在水相中以巯基乙酸(mercaptoacetic acid, MA)为稳定剂合成了CdSe、CdTe、CdTe/ZnS量子点及谷胱甘肽(glutathione, GSH)为稳定剂合成了CdTe量子点,然后通过卵磷脂和胆固醇修饰制得相应的量子点脂质体。溶血实验证实GSH修饰量子点的溶血率低于MA修饰的量子点45%;脂质体修饰后,量子点的溶血率＜5%,达到生物医用材料要求。不同表面修饰的量子点对小鼠毒性存在明显差异,荧光显微镜观察组织切片证实量子点在小鼠体内主要分布在肺、肾、胸腺等组织中,而脂质体量子点在脑组     

Purification of denatured bovine serum albumin coated CdTe quantum dots for sensitive detection of silver(I) ions

CdTe quantum dots (QDs) were synthesized in aqueous solution with 3-mercaptopropionic acid as the stabilizer. Chemically reduced bovine serum albumin (BSA) was used to modify the surface of the QDs. Experimental results showed that the denatured BSA (dBSA) could be effectively conjugated to the surface of CdTe QDs. Column chromatography was used to purify the conjugates and determine the optimal ratio of dBSA to QDs. Further experimental results showed that the conjugation of QDs by dBSA efficiently improved the photoluminescence quantum yield, the chemical stability of QDs and their stability against photobleaching. A facile and sensitive method for determination of silver(I) ions was proposed based on the fluorescence quenching of the dBSA–QDs. Under the optimal conditions, the relative fluorescence intensity decreased linearly with the concentration of the silver(I) ions in the range 0.08–10.66 μM. The detection limit was 0.01 μM. This study provides a new method for the detection of metal cations. Figure In this work, denatured BSA was used to modify the surface of CdTe QDs by a simple and rapid method. And the conjugates of dBSA-QDs were purified by column of Sephadex G-100. After the purification of the conjugates, the sensitivity was greatly increased as silver (I) ions probe.     

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.     

Use of surface-modified CdTe quantum dots as fluorescent probes in sensing mercury (II)

Thioglycolic acid (TGA)-capped CdTe quantum dots (QDs) were synthesized in aqueous medium, and their interaction with metal cations was studied with UV-vis absorption, steady-state and time-resolved fluorescence spectra. The results demonstrated that Hg(II), Cu(II) and Ag(I) could effectively quench the QD emission based on different action mechanisms: Cu(II) and Ag(I) quenched CdTe QDs because they bound onto particle surface and facilitated non-radiative electron/hole recombination annihilation of QDs; electron transfer process between the capping ligands and Hg(II) was mainly responsible for the remarkable quenching effect of Hg(II). To prevent the approach of metal cations to QD core, the original TGA-capped CdTe QDs were further coated by denatured bovine serum albumin (dBSA). It was found that the dBSA-coated CdTe QDs could be quenched effectively by Hg(II), but Cu(II) and Ag(I) could hardly quench the QDs even at fairly higher concentration levels because the dBSA shell layer effectively prevented the binding of metal cations onto the QD core. On the basis of this fact, a simple, rapid and specific method for Hg(II) determination was proposed. Under optimal conditions, the quenched fluorescence intensity increased linearly with the concentration of Hg(II) ranging from 0.012 x 10(-6) to 1.5 x 10(-6) mol L(-1). The limit of detection for Hg(II) was 4.0 x 10(-9) mol L(-1). The developed method was successfully applied to the detection of trace Hg(II) in real samples.     

Temperature-dependent photoluminescence of highly luminescent water-soluble CdTe quantum dots

Highly luminescent water-soluble CdTe quantum dots(QDs) have been synthesized with an electrogenerated precursor.The obtained CdTe QDs can possess good crystallizability,high quantum yield(QY) and favorable stability.Furthermore,a detection system is designed firstly for the investigation of the temperature-dependent PL of the QDs.     

CdTe量子点作为荧光探针测定水环境中微量镉离子

利用CdTe量子点(QDs)和乙二胺四乙酸(EDTA)构建的纳米探针,建立了一种能快速灵敏检测Cd2+的新方法。利用EDTA溶液与Cd2+的络合作用对QDs的表面进行化学蚀刻,在QDs表面形成了Cd2+的空腔,这些表面缺陷使得QDs荧光猝灭,而继续加入Cd2+后,新加入的Cd2+能够迅速补位空腔修复表面缺陷,使得QDs的荧光恢复。在最佳的实验条件下,当Cd2+浓度在3.3×10-9~6.7×10-6mol/L范围时,QDs恢复的荧光强度与Cd2+浓度之间呈良好的线性关系,检出限为1.0×10-9mol/L(S/N=3)。此外,相对于其他金属离子,该荧光探针对Cd2+具有高选择性,并且将其用于实际水样中Cd2+含量的检测,结果令人满意。     

High Sensibility of Quantum Dots to Metal Ions Inspired by Hydroxyapatite Microbeads

An approach for the sensitive and selective determination of Ag⁺, Cu²⁺ and Hg²⁺ ions was developed based on the fluorescence quenching of mercaptopropionic acid (MPA) capped CdTe quantum dots in the existence of hydroxyapatite (HAP) nanoribbon spherulites. Among various metal ions investigated, it was found that the fluorescence of CdTe QDs was only sensitive to Ag⁺, Cu²⁺ and Hg²⁺ ions. The addition of HAP into the CdTe system could bring forward a sensitivity improvement of about 1 to 2 orders of magnitude in the detection of Ag⁺ and Cu²⁺ compared with the plain CdTe system without the existence of HAP; while there was no sensitization effect for Hg²⁺. Under optimal conditions, the detection limits for Ag⁺, Cu²⁺ and Hg²⁺ were 20, 56 and 3.0 nmol·L^?1, respectively, and the linear ranges were 0.02–50, 0.056–54 and 0.003–2.4 µmol·L^?1, respectively. Mechanisms of both QDs fluorescence quenching by metal ions and the sensitization effect by HAP were also discussed.     

水热法合成巯基乙胺稳定的CdTe量子点

提出了一种以水热法合成巯基乙胺稳定的CdTe量子点的简单制备路线. 在优化的反应条件下, 产物的荧光量子效率最高达到19.7%, 接近已报道的其它方法的2倍. 考察了反应条件对产物的荧光性能的影响及产物在不同pH溶液中的稳定性.     

Simple and sensitive detection method for chromium(VI) in water using glutathione—capped CdTe quantum dots as fluorescent probes

Water-soluble and stable CdTe quantum dots (QDs) were synthesized in aqueous solution with glutathione (GSH) as the stabilizer. GSH is employed by nature to detoxify heavy metal ions. As a result of specific interaction, the fluorescence intensity of GSH-capped QDs is selectively reduced in the presence of Cr(VI). Under the optimum conditions, the relative fluorescence intensity decreases linearly with the Cr(VI) concentration in the range from 0.01 to 1.00?µg mL^?1, and the detection limit is 0.008?µg mL^?1. The luminescence response of the QDs to ions markedly depended on the particle size, and a new strategy for tuning the selectivity of luminescent QDs to certain ions without changing the capping layer of the QDs can be achieved by changing the crystallite size of the QDs.     

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.