基于CdSe/ZnS量子点构建多巴胺荧光检测方法的研究

以CdSe/ZnS量子点为荧光探针,基于多巴胺对CdSe/ZnS量子点的荧光猝灭效应,建立了一种可快速测定多巴胺的荧光检测方法。在最优实验条件下(pH7.4,反应时间20min),多巴胺浓度在0.01~0.7μmol/L范围内与CdSe/ZnS量子点的荧光猝灭强度比值呈良好的线性关系(r=0.996),方法检出限为1.6×10-4μmol/L,相对标准偏差为1.2%。与文献报道的方法相比,该方法的检出限更低,更为灵敏,可用于多巴胺注射液及人体尿样中多巴胺的快速检测。     

谷胱甘肽稳定的CdTe量子点荧光猝灭法测定痕量过氧化氢

以谷胱甘肽稳定的CdTe量子点作为荧光探针,基于荧光猝灭法对过氧化氢进行了定量检测,考察了缓冲溶液体系、量子点浓度、反应时间等多种因素的影响。实验结果表明,在pH=7.2的Na2HPO4-NaH2PO4缓冲液中,反应时间为15min,过氧化氢浓度为1.0×10-6～3.0×10-5 mol/L范围时,其线性回归方程为△F=9.78+7.56c(10-6 mol/L),线性相关系数和检测限分别为0.9992和1.27×10-8 mol/L。谷胱甘肽稳定的CdTe量子点荧光猝灭法已用于水样的测定,回收率在96%～103%之间,相对标准偏差RSD不大于3.3%,结果令人满意。     

CdTe量子点荧光猝灭法测定对硝基苯胺的含量

以CdTe量子点作为荧光探针,基于荧光猝灭法对对硝基苯胺进行了定量检测,考察了缓冲溶液体系、量子点浓度、反应时间等多种因素的影响.实验结果表明,在pH7.7的0.2 mol/L Na2HPO4-NaH2PO4缓冲液中,反应时间为10 min,对硝基苯胺浓度为1.2×10-6～2.0×10-5 mol/L范围时,其线性回...     

水溶性量子点碲化镉测定同型半胱氨酸的研究

以巯基丙酸为稳定剂,在水溶液中一步合成了CdTe量子点,以该量子点为荧光探针,基于荧光增敏法对同型半胱氨酸(Hcy)进行选择性测定,考察了缓冲体系、缓冲液浓度、缓冲液pH值、反应时间、量子点浓度等多种因素的影响.在0.05 mol/L、pH 8.8的磷酸二氢钠-磷酸氢二钠缓冲液中,当量子点浓度为1.2 mmol/L、反应时间为10 min时,该方法的线性区间为0.1 ～60 μmol/L,检出限为8×10-8 mol/L.     

CdTe量子点荧光猝灭法测定痕量铬(Ⅲ)

以CdTe量子点作为荧光探针,基于荧光猝灭法对Cr(Ⅲ)进行了定量检测,考察了缓冲溶液、量子点浓度、反应时间等多种因素的影响.实验结果表明,在0.1mL pH 7.3的0.2 mol/L Na<,2>HPO<,4>-NaH<,2>PO<,4>缓冲液中,反应时间为20 min,Cr(Ⅲ)浓度为2.4×10<'-7>～6.0×10<'-6>mol/L范围时,其线性回归方程为F<,0>/F=1.1274+0.0640 c(10<'-7>mol/L),相关系数和检测限分别为0.9984和4.5×10<'-8>mol/L.为Cr(Ⅲ)的测定提供了新的方法.     

以碲化镉量子点为荧光探针测定西红柿中残留吗啉胍

利用吗啉胍使CdTe量子点荧光增强的特性,建立了西红柿中吗啉胍残留量的检测新方法。研究了影响量子点荧光探针行为的因素,确定最佳工作条件:量子点浓度为1×10-4mol/L,pH=5.6,反应温度为20℃,反应时间为20 min。在最佳测定条件下,CdTe量子点荧光探针对吗啉胍响应的线性范围为1.0×10-12~5.0×10-10mol/L,检出限为5.2×10-13mol/L,线性相关系数R=0.9981,方法的回收率97%~106%,常见共存离子、抗生素、维生素等共存物质对吗啉胍的测定不产生干扰。本方法用于西红柿中吗啉胍残留量的测定,结果令人满意。     

基于CdSe/ZnS量子点构建乙酰甲胺磷荧光检测方法研究

本文以CdSe/ZnS量子点为荧光探针,基于乙酰甲胺磷对CdSe/ZnS量子点的荧光猝灭效应,建立了一种可快速测定乙酰甲胺磷的荧光检测方法。通过透射电子显微镜(TEM)、紫外-可见吸收光谱和荧光光谱对CdSe/ZnS量子点进行表征。在反应时间为5 min条件下,乙酰甲胺磷的浓度在0.487×10~(-6)～7.225×10~(-6) mol/L范围内与CdSe/ZnS量子点的荧光猝灭强度比值呈良好的线性关系(R~2=0.9987),方法检出限为2.55×10~(-7) mol/L。在2.0、5.0μmol/L加标水平下的回收率为94.5%～102.8%,相对标准偏差(RSD,n=5)小于4%。该方法选择性好,灵敏度高,可用于水果和蔬菜中农药乙酰甲胺磷的快速检测。     

抑制荧光动力学法测定痕量抗坏血酸

在Na2HPO4-NaH2PO4弱碱性介质中,痕量抗坏血酸对氮氧自由基使CdTe量子点荧光猝灭具有抑制作用,由此建立了动力学荧光法测定痕量抗坏血酸的新方法。考察了不同pH、CdTe量子点和氮氧自由基的用量、反应时间等条件对抑制反应的影响。在最佳实验条件下,方法线性范围为2×10-7～1.5×10-5mol/L,检出限为5×10-8mol/L。该方法用于饮料等实际样品中抗坏血酸的测定,回收率为98%～103%。     

荧光猝灭法测定叶酸

以维生素B2作为荧光探针,基于荧光猝灭法对叶酸进行了定量检测,考察了维生素B2浓度、激发波长、反应时间等多种因素的影响。实验结果表明,在水溶液中,反应时间为8 min,叶酸浓度在1.5×10-6～1.0×10-5mol/L范围内,其线性回归方程为F0/F=0.6838+0.214 c(×10-6mol/L),相关系数和检测限分别为0.9988和6.7×10-7mol/L。     

3-巯基丙酸修饰的CdTe量子点荧光探针用于碘酸根离子的检测

以3-巯基丙酸(MPA)为稳定剂,采用水相合成法制备了CdTe量子点(QDs)。基于IO-3可使CdTe QDs荧光显著猝灭的特性,建立了一种检测IO-3的荧光分析新方法。优化了实验条件,在pH=6.0、三酸缓冲溶液浓度为30mmol/L、QDs溶液浓度为8.66×10-6 mol/L、反应时间为24min最佳实验条件下,检测IO-3的线性范围为6.0×10-8~7.2×10-6 mol/L,检出限为4.92×10-8 mol/L,方法相对标准偏差为2.37%。实验表明,IO-3对CdTe QDs的荧光猝灭有较好的选择性。方法用于自来水中IO-3的回收率实验,回收率为92.17%~103.29%。对可能的机理进行了探讨。     

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.     

One-pot synthesis of strongly luminesencing CdTe quantum dots and their conjugation with mouse antibody to alpha-fetoprotein

In this paper, strongly luminescent CdTe quantum dots (QDs) were synthesized in aqueous solution by a facile one-pot method. The CdTe QDs were synthesized in a weakly acidic or neutral buffer solution composed of sodium borate (Na₂B₄O₇) and sodium citrate (C₆H₅Na₃O₇). The pH of buffer solution and the ratio of the precursors were systematically optimized; the high-quality CdTe QDs with progressively increasing fluorescence during 60 days storage were obtained. As-prepared QDs can be conjugated with a mouse antibody alpha-fetoprotein via the reaction mediated by N-hydroxysuccinimide and 1-ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride. The conjugate showed a red shift of 9 nm for the emission position.     

CdTe量子点荧光猝灭法测定奥沙利铂中微量银

以谷胱甘肽作为稳定剂,100℃恒温回流,直接合成水溶性CdTe量子点。基于Ag+对合成的CdTe量子点的荧光猝灭效应,建立了测定抗癌药物奥沙利铂中微量银的方法。考察了量子点浓度、缓冲液种类、缓冲液浓度、缓冲液pH和反应时间对银离子测定的影响。当量子点浓度为0.004 g/L时,在0.10 mmol/LpH7.4的磷酸缓冲溶液中,反应时间为5 min,体系的相对荧光强度与Ag+的质量浓度呈良好的线性关系,其线性范围为16.42～98.50μg/L,线性相关系数为0.9975,检出限为0.12μg/L。     

Modification of CdTe quantum dots as temperature-insensitive bioprobes

CdTe quantum dots (QDs) were synthesized in aqueous solution with 3-mercaptopropionic acid (MPA) as the stabilizer. The photoluminescence (PL) of CdTe QDs (3.5nm) is found to be temperature-dependent: as the temperature arising from 278K to 323K, the PL intensity declines to 50.2% of its original and PL emission peak shows obvious red-shift ( approximately 7nm). After modification of the QDs surface with denatured ovalbumin, the PL is more temperature-insensitive than before. The PL intensity retains more than 70% of its original and the emission peak shows less red-shift ( approximately 2nm). Moreover, it is found that the PL intensity and wavelength of denatured ovalbumin coated CdTe QDs are reversible during heating (323K)-cooling (278K) cycles. All the studies provide an important theoretical basis for searching temperature-insensitive bioprobes.     

Electrochemiluminescence Enhancement of CdTe Quantum Dots by the Addition of Silver(I) Ions

Water-soluble CdTe quantum dots (QDs) were synthesized by using a 3-mercaptopropionic acid (MPA) capped method. Stable electrochemiluminescence (ECL) was obtained when the CdTe QDs were immobilized onto a glassy carbon electrode (GCE) by Layer-By-Layer (LBL) assembly of CdTe QDs and polydiallyldimethylam-monium chloride (PDDA) by using 2-(dibutylamino)-ethanol (DBAE) as a co-reactant. The ECL enhancement of CdTe QDs by the addition of silver(I) ions was also investigated. The maximum enhancement factor about 4 was obtained on a GCE in the presence and absence of the co-reactant. The enhancement was observed in phosphate-citric acid and phosphate buffer solutions (PBS), but not in borate buffer solution (BBS). This was newly formed Ag nanoparticles or silver(I) complex with large surface area and high catalytic activity in the phosphate-citric acid and phosphate buffer solutions, thus resulting in ECL enhancement.     

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.     

一锅合成绿色到近红外发射的CdTe量子点

以3-巯基丙酸(MPA)为稳定剂,采用水相合成法制备了从绿色到近红外发射的CdTe量子点。系统研究了反应液pH值、镉和碲的物质的量之比及镉和3-巯基丙酸的物质的量之比等实验条件对CdTe量子点体系的发射波长和荧光量子产率的影响。在pH值为10.5,且nCd2+∶nTe2-∶nMPA=1∶0.05∶1.1的条件下,回流0.5 h,CdTe量子点体系在569 nm波长处的荧光量子产率达到30.8%;在7 h的回流时间内,制备的量子点的波长覆盖范围为525～730 nm。分别用X射线粉末衍射、透射电镜和红外光谱对CdTe量子点的晶体结构、形貌及表面基团进行表征。     

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.     

Photoluminescence Stability of Colloidal CdTe Quantum Dots in Various Buffer Solutions

Mercaptoacetic acid-capped CdTe quantum dots (QDs) are potential luminescent markers for biological analysis. The photoluminescence (PL) stability of the QDs in buffer solutions determines their practicability as markers in electrophoresis. The stability of the QDs was thus investigated in electrophoresis buffers including tris–borate–ethylenediaminetetraacetic acid (TBE) and tris–acetate–ethylenediaminetetraacetic acid (TAE). The QDs were completely unstable in high-concentrated buffers (≥0.1×). In the case of low concentrations (≤0.07× for TAE, ≤0.035× for TBE), the PL intensity of the QDs in two kinds of buffers decreased with increasing buffer concentrations. A red-shifted PL peak wavelength and PL intensity fluctuation were observed after dispersing the QDs in diluted TAE buffer solutions with concentrations of ≤0.07× for long time. According to the Stern–Volmer plots of PL degradation, the factors leading to the degradation were complicated, which was attributed to the actions of the components including tris, borate or acetic acid, and ethylenediaminetetraacetic acid as well as their mutual effects.