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。

CdTe quantum dots as fluorescent probes for determination of trace cadmium ions in water environment

In recent years, environmental and health problems caused by heavy metals were more frequent, so we urgently need to develop a cheap, simple and new method for fast detection of heavy metal ions. In this study, a novel optical nanoprobe for Cd₂ detection has been constructed successfully based on CdTe quantum dots and ethylenediamine tetraacetic acid (EDTA). After chemical etching with EDTA, we find to generate cavities of Cd₂ on the surface of CdTe QDs, the surface defects cause fluorescence quenching. Continuing to add Cd₂ , specific Cd₂ recognition sites are created on the surface of the QDs, which can selectively bind Cd₂ , thereby repairing the surface defects and restoring the fluorescence of the QDs. Under optimal conditions, the change of the fluorescence intensity of quantum dots was in good linear relationship with the Cd₂ concentration in the range of 3.3×10_-9 to 6.7×10_-6 mol/L and the detection limit was 1.0×10_-9 mol/L (S/N=3). Furthermore, the present probe exhibited a high selectivity for Cd₂ over other metal ions and was successfully used in the detection of Cd₂ in real water samples.