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近年来,环境污染问题愈趋严峻,其中重金属对环境的污染和破坏作用尤为突出,严重危害人类的健康和生存[1 − 3]. 汞是环境中毒性最强的重金属元素之一,汞离子在生物体内能和蛋白质及各种酶发生强烈的相互作用,使生物体失去活性,进而导致机体产生病变或表现出毒性[4 − 5]. 汞离子具有不易降解性、易迁移性和高度生物蓄积性的特点,当在人体内积累达到一定程度时,即可呈现出毒性作用,从而危害人体健康[6 − 7]. 世界卫生组织(WHO)将Hg2+视为能够造成重大公共健康风险的十大化学品或物质之一[8 − 9]. 探索水环境中高选择性、高灵敏度检测Hg2+的方法已成为环境生态科学领域的研究热点[10 − 11].
荧光探针检测技术具有操作简单、高选择性、高灵敏度、响应时间迅速等优点,近年来已被广泛应用于环境污染物的检测研究[12 − 14]. 利用Hg2+与S原子的强结合能力,多种以硫代苯甲酸酯为识别基团的荧光探针被开发应用于环境和生物体内Hg2+的高选择性和高灵敏度识别检测[15 − 17]. 孙艳丽等[18]以半花菁染料为荧光基团,设计合成了一个席夫碱型荧光探针用于实际水样中Hg2+的高选择性检测. 李淑雅等[19]以7-羟基吩恶嗪酮为荧光基团,开发了一个比色荧光双通道探针,该探针对Hg2+检测的线性范围为0—10 μmol·L−1,检出限为17 nmol·L−1. Wang等[20]以苯并噻唑作为荧光基团,设计合成了一个比率型荧光探针,通过405 nm和525 nm处荧光强度的比值变化,对50—100 μmol·L−1浓度范围内的Hg2+进行准确定量检测. Jiang等[21]以香豆素为荧光基团,构建了一个近红外荧光探针,该探针通过695 nm处的强荧光发射实现Hg2+的检测,同时展现出巨大的斯托克斯位移(316 nm). 此类荧光探针大多以硫代苯甲酸酯为识别基团,本文选择以N,N-二甲氨基硫代甲酸酯为识别基团构建荧光探针,丰富了Hg2+识别基团的选择.
半花菁染料是由氮杂环阳离子通过π共轭桥连与电子供体连接而成的D-π-A体系,因其具有良好且稳定的光学性质、较高的结构修饰度、溶解度好、荧光量子产率高及较大的Stokes位移等优点,被广泛应用于构建荧光探针和生物传感器[22 − 25]. 本文以半花菁类染料为荧光信号基团,以N,N-二甲基硫代甲酸酯为识别基团,构建了一个高选择性高灵敏度检测Hg2+的荧光探针,并研究了该探针在环境水Hg2+检测中的应用.
一种反应型荧光探针的构建及其在环境水汞离子检测中的应用
Construction of a reaction-based fluorescent probe and its application in the detection of mercury ions in environmental water
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摘要: 汞因具有高毒性、迁移性等特点对环境及人体产生巨大的伤害. 因此,建立便捷、高效、快速检测Hg2+的分析方法具有重要意义. 本文以半花菁染料为荧光基团,N,N-二甲氨基硫代甲酸酯为识别基团,设计合成了一种反应型荧光探针Cy-DMTC. 荧光光谱滴定分析显示探针Cy-DMTC能够特异性识别Hg2+,且灵敏度高、抗干扰能力强. 随着Hg2+浓度增加,其512 nm处荧光强度不断增强且呈现出强绿色荧光,同时产生了显著的stokes位移(156 nm). 探针的荧光强度与Hg2+浓度在2.0×10−6—12.5×10−6 mol·L−1范围内呈现良好的线性相关(R2=0.9955),检出限为8.65×10−8 mol·L−1. 机理研究证实由于Hg2+诱导硫代甲酸酯发生水解反应,导致电荷转移荧光增强,从而实现对Hg2+的定性定量检测. 探针Cy-DMTC已被成功应用于实际水样中Hg2+的检测,可为Hg2+的检测提供了一种高效的解决方案.
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关键词:
- 荧光探针 /
- 半花菁 /
- N,N-二甲氨基硫代甲酸酯 /
- 汞离子 /
- 反应型探针.
Abstract: Mercury is extremely harmful to ecosystems and human health due to its toxicity and mobility. Consequently, the development of a convenient, efficient, and rapid analytic method for the detection of Hg2+ is of great importance. Herein, Cy-DMTC was designed and synthesized as a reaction-based fluorescent probe by using hemicyanine dye as the fluorescent group and N,N-dimethylthiocarbamoyl as the recognition group. The results of the fluorescence titration investigation demonstrate that Cy-DMTC can specifically recognize Hg2+ with high sensitivity and strong anti-interference ability. The fluorescence intensity at 512 nm exhibits a consistent increase as the concentration of Hg2+ is raised, resulting in strong green fluorescence and a substantial Stokes shift (156 nm). The fluorescence intensity of Cy-DMTC exhibits an excellent linear correlation with Hg2+ concentration in the range of 2.0×10−6—12.5×10−6 mol·L−1 (R2=0.9955), with a detection limit of 8.65×10−8 mol·L−1. Mechanism studies revealed that Hg2+ triggers the hydrolysis of thiocarbonate, thereby enhancing charge transfer fluorescence and making Hg2+ detectable both qualitatively and quantitatively. Cy-DMTC has been successfully used to detect Hg2+ in real water samples, thus providing an effective method for Hg2+ detection.-
Key words:
- fluorescent probe /
- hemicyanine /
- N,N-dimethylthiocarbamoyl /
- mercury ion /
- reaction-based probe.
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图 4 (a)探针Cy-DMTC (5×10−6 mol·L−1)选择性识别实验;(b)探针Cy-DMTC+Hg2+ (5×10−6 mol·L−1)与干扰离子共存实验;(c)探针Cy-DMTC (5×10−6 mol·L−1)的选择性识别及抗干扰性实验的柱状图;(d)探针Cy-DMTC(5×10−6 mol·L−1)识别各种金属离子的荧光变化
Figure 4. (a) Selectivity of probe Cy-DMTC (5×10−6 mol·L−1) towards Hg2+; (b) Fluorescence spectra of Cy-DMTC+Hg2+ (5×10−6 mol·L−1) coexists with interfering metal ions; (c) Histogram of selective recognition and anti-interference experiments with the probe Cy-DMTC (5×10−6 mol·L−1); (d) Fluorescence change for probe Cy-DMTC (5×10−6 mol·L−1) in the presence of various metal ions
图 5 (a)探针Cy-DMTC(5×10−6 mol·L−1)与不同浓度Hg2+ (0—2.0×10−5 mol·L−1)反应后的荧光光谱图;(b)探针Cy-DMTC在512 nm处的荧光强度与Hg2+浓度的变化趋势图
Figure 5. (a) Fluorescence spectra of Cy-DMTC (5×10−6 mol·L−1) with increasing concentrations of Hg2+ (0—2.0×10−5 mol·L−1); (b) Plot of Hg2+ concentration with fluorescence intensity of Cy-DMTC at 512 nm
图 6 (a)探针Cy-DMTC+Hg2+ (5×10−6 mol·L−1)随时间变化的荧光光谱图;(b)探针Cy-DMTC+Hg2+ (5×10−6 mol·L−1)在512 nm处的荧光强度与时间(s)拟合曲线图
Figure 6. (a) Fluorescence spectral changes of probe Cy-DMTC+Hg2+ (5×10−6 mol·L−1) in the presence of Hg2+ over time; (b) Time dependent increase of fluorescence intensities of Cy-DMTC at 512 nm after addition of Hg2+
表 1 探针Cy-DMTC对实际水样中Hg2+的检测
Table 1. Detection of Hg2+ in actual water samples by probe Cy-DMTC
样品
Sample加标量/(μmol·L−1)
Hg2+ Add回收量/(μmol·L−1)
Hg2+ RecoveryRSD/%
(n=3)回收率/%
Recovery矿泉水
Mineral water0.00 — — — 2.00 1.98 1.21 98.95 5.00 4.97 1.05 99.45 10.00 9.67 1.25 96.75 自来水
Tap water0.00 — — — 2.00 1.99 1.16 99.85 5.00 4.90 1.03 97.93 10.00 10.11 1.12 101.13 湖水
Lake water0.00 — — — 2.00 1.98 1.89 98.93 5.00 5.10 1.73 102.05 10.00 9.61 1.81 96.10 -
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