功能化硒化镉量子点的制备以及作为汞离子荧光探针的研究

以L-半胱氨酸为稳定剂,水溶液中通过简易的两步合成了CdSe(硒化镉)量子点,在磷酸盐的缓冲介质中,Hg2+对量子点有显著荧光猝灭作用。实验考察了缓冲液pH值、反应时间、量子点浓度等多种因素对Hg2+分析灵敏度的影响。结果表明,在最佳实验条件下,pH=7.75的Na2HPO4-NaH2PO4缓冲溶液中,反应时间为30分钟,量子点浓度为7.5×10-6mol/L,Hg2+在5.0×10-8~2.5×10-6mol/L的浓度范围内对量子点有较强的猝灭作用,且体系的发光强度与溶液中的Hg2+的浓度符合修正的斯特恩方程,常见的共存离子响应考察结果表明:该法具有较高的选择性,同时与常见的检测汞离子的荧光方法相比,该方法具有较高的灵敏度和较宽的线性范围。

Preparation of Functionalized CdSe Quantum Dots and Studies on the Selective Determination of Mercury Ion

Mono-disperse CdSe nanoclusters have been prepared facilely and functionalized with L-cysteine through two steps by using safe and low cost substances.They are water-soluble and biocompatible.Especially these functionalized quantum dots can be stably soluble in water more than for 30 days,and the intensity of fluorescence and absorbance was decreased less than 15% of fresh prepared CdSe colloids.These functionalized CdSe QDs exhibited strong specific affinity for mercury(II) through QDs interface functional groups.Based on the quenching of fluorescence signals of functionalized CdSe QDs at 530 nm and no obvious wavelength shift or no new emission band in present of Hg(II) at pH 7.75 of phosphate buffer solution,a simple,rapid and specific array for Hg(II) was proposed.In comparison with conventional organic fluorophores,these nanoparticles are brighter,more stable against photobleaching,and do not suffer from blinking.Under optimum conditions,the response of linearly proportional to the concentration of Hg(II) between 0 and 2.0×10-6 mol/L,and the limit of detection is 6.0 ×10-9 mol/L.The relative standard deviation of six replicate measurements is 1.8 % for 1.0×10-7 mol/L Hg(II).The mechanism of reaction is also discussed.