Aqueous synthesis of type-II core/shell CdTe/CdSe quantum dots for near-infrared fluorescent sensing of copper(II).
Aqueous synthesis of type-II core/shell CdTe/CdSe quantum dots for near-infrared fluorescent sensing of copper(II).
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DOI：
10.1039/b801963k
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发表时间：
2008-06
期刊：
影响因子：
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通讯作者：
Yunsheng Xia;Chang-qing Zhu
中科院分区：
文献类型：
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作者：
Yunsheng Xia;Chang-qing Zhu
以巯基封端的CdTe量子点为核模板，CdCl（2）和Na（2）SeSO（3）为壳前体，在水溶液中合成了II型核壳结构的CdTe/CdSe量子点。与原来的CdTe核相比，由于形成了间接激发，核/壳结构的CdTe/CdSe量子点在近红外波段表现出明显的红移发射，并具有颜色调谐能力。所制备的量子点具有较高的稳定性和中等的荧光量子产率（10-20%），并通过紫外-可见吸收光谱、稳态和时间分辨荧光光谱、X射线粉末衍射、X射线光电子能谱和高分辨透射电子显微镜表征了其核/壳异质结构。Cu（II）和相近浓度的Zn（II）、Ca（II）、Na（I）和K（I）等生理上重要的阳离子都能显著地猝灭核/壳量子点的荧光，对荧光没有影响。在此基础上，提出了一种以近红外CdTe/CdSe量子点为荧光探针，简单快速测定Cu（II）的方法。在最佳条件下，Cu（Ⅱ）的浓度在0.05 ~ 50.0 × 10（-6）mol L（-1）范围内与响应呈线性关系，检测限为2.0 × 10（-8）mol L（-1）。该方法已成功应用于真实的样品中痕量Cu（II）的测定。
Type-II core/shell CdTe/CdSe quantum dots (QDs) were synthesized in aqueous medium by employing thiol-capped CdTe QDs as core template and CdCl(2) and Na(2)SeSO(3) as shell precursors, respectively. Compared with the original CdTe cores, the core/shell CdTe/CdSe QDs showed an obvious red-shifted emission with the color-tune capability to the near-infrared (NIR) wavelength, because of the formation of an indirect excitation. The prepared QDs exhibited high stability and moderate fluorescence quantum yields (10-20%), and their core/shell heterostructure was characterized by UV-vis absorption, steady-state and time-resolved fluorescence spectra, X-ray powder diffraction, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. The fluorescence of the core/shell QDs could be markedly quenched by Cu(II), and approximate concentrations of other physiologically important cations, such as Zn(II), Ca(II), Na(I) and K(I) etc., had no effect on the fluorescence. Based on this, a simple and rapid method for Cu(II) determination was proposed using the NIR CdTe/CdSe QDs as fluorescent probes. Under optimal conditions, the response was linearly proportional to the concentration of Cu(II) between 0.05 to 50.0 x 10(-6) mol L(-1), the limit of detection was 2.0 x 10(-8) mol L(-1). The developed method was successfully applied to the detection of trace Cu(II) in real samples.