Luminescent CdS quantum dots as selective ion probes
Luminescent CdS quantum dots as selective ion probes
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DOI：
10.1021/ac0258251
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发表时间：
2002-10-01
影响因子：
7.4
通讯作者：
Rosenzweig, Z
中科院分区：
文献类型：
--
作者：
Chen, YF;Rosenzweig, Z
在水溶液中合成了聚磷酸盐、L-半胱氨酸和硫代甘油包覆的水溶性发光CdS量子点。配体被发现对CdS量子点对生理上重要的金属阳离子的发光响应具有深远的影响。聚磷酸盐封端的CdS量子点敏感，几乎所有的一价和二价阳离子，显示没有离子选择性。相反，巯基甘油封端的CdS量子点只对铜和铁离子敏感。类似浓度的生理相关的阳离子，如锌，钠，钾，钙，镁离子没有影响硫代甘油封端的CdS量子点的发光。另一方面，L-半胱氨酸封端的CdS量子点是敏感的锌离子和不敏感的其他生理上重要的阳离子，如铜，钙，镁离子。为了证明这些新的离子探针的检测能力，L-半胱氨酸和巯基甘油封端的CdS量子点被用来检测生理缓冲液样品中的锌和铜离子。检测限为0.8 μ M的锌（II）和0.1 μ M的铜（II）离子。锌（II）的量子点的发射增强归因于表面态的活化，而铜（II）的有效还原铜（I）可以解释的硫代甘油封端的CdS量子点的发射减少时，与铜离子充电。与有机荧光染料不同，硫代甘油封端的发光CdS量子点区分铜离子和锌离子，因此适合于在生理浓度的锌离子存在下分析生物样品中的铜离子。铁离子对锌和铜离子检测的干扰是由于内过滤效应，通过加入氟离子形成无色络合物FeF 63-消除。据我们所知，这是第一次使用发光半导体量子点作为水溶液样品中的选择性离子探针。
Water-soluble luminescent CdS quantum dots (QDs) capped by polyphosphate, L-cysteine, and thioglycerol were synthesized in aqueous solution. The ligands were found to have a profound effect on the luminesence response of CdS QDs to physiologically important metal cations. Polyphosphate-capped CdS QDs were sensitive to nearly all mono- and divalent cations, showing no ion selectivity. Conversely, thioglycerol-capped CdS QDs were sensitive to only copper and iron ions. Similar concentrations of physiologically relevant cations, such as zinc, sodium, potassium, calcium, and magnesium ions did not affect the luminescence of thioglycerol-capped CdS QDs. On the other hand, L-cysteine-capped CdS QDs were sensitive to zinc ions and insensitive to other physiologically important cations, such as copper, calcium, and magnium ions. To demonstrate the detection capability of these new ion probes, L-cysteine and thioglycerol-capped CdS QDs were used to detect zinc and copper ions in physiological buffer samples. The detection limits were 0.8 muM for zinc (II) and 0.1 muM for copper (II) ions. The emission enhancement of the QDs by zinc (II) is attributed to activation of surface states, whereas the effective reduction of copper (II) to copper (I) may explain the emission decrease of the thioglycerol-capped CdS QDs when charged with copper ions. Unlike organic fluorescent dyes, the thioglycerol-capped luminescent CdS QDs discriminate between copper and zinc ions and are therefore suitable for the analysis of copper ions in biological samples in the presence of physiological concentrations of zinc ions. The interference of iron ions with zinc and copper ion detection is attributed to an inner filter effect, which is eliminated by adding fluoride ions to form the colorless complex FeF63-. To the best of our knowledge, this is first use of luminescent semiconductor quantum dots as selective ion probes in aqueous samples.