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苯硫酚(thiophenol, PhSH)是一种有用的有机合成中间体,广泛应用于制药、农用化学品和各种工业产品的制备[1]. 它们也是具有剧毒和污染的化学物质,被美国环境保护署列为优先处理的污染物之一[2]. 长时间接触PhSH会导致严重的健康问题,包括中枢神经系统损伤、呼吸困难、呕吐、甚至死亡. 此外,PhSH不仅毒性大,还具有强烈的刺激性和挥发性,接触时间不能超过15 min[3-4]. 然而,即使在浓度很低的溶液中,PhSH也有一种可怕的气味,长时间接触会导致恶心和头痛,应尽量缩短与PhSH的接触时间[5-6]. 因此,构建可快速、高选择性识别PhSH的荧光探针在环境科学和生物科学领域都具有重要的意义.
近年来,硫醇类荧光探针的开发引起了人们的极大兴趣[7-14]. Wang课题组报道了首个基于分子内光诱导电荷转移(photoinduced charge transfer, PET)机理的PhSH探针,该探针以4-氨基-7-硝基-2,1,3-苯并恶二唑(NBD)作为荧光团,2,4-二硝基苯磺酰胺(2, 4-dinitrobenzene sulfonamide, DNBS)为识别基团,具有良好的水溶性和选择性,但由亲核取代释放的荧光团的荧光量子产率较低(Φ = 0.02),且反应时间太长[15]. 随后,科研工作者以DNBS为识别基团,构建了多种能够区分脂肪族硫醇和PhSH类化合物的荧光探针,然而它们有的显示相对较弱的荧光强度,一些需要有机化合物作为助溶剂,有些则受需要使用高pH值的影响,有的选择性较差,有的检测过程耗时较长(孵育时间长达1 h),只有少数几种方法可以应用于实际检测[4, 16-18]. 因此,一种反应速度快、适用于实际环境和生物样品中PhSH检测的荧光探针还有待开发.
香豆素染料具有高的荧光强度、良好的溶解性、高效的细胞渗透等优点,是荧光探针的理想荧光团[19-21]. 本文以香豆素衍生物CP为荧光团、强吸电子基团DNBS为识别基团,成功构建了荧光增强型香豆素类荧光探针CPH. 由于CP和DNBS之间的PET过程,探针CPH自身没有荧光. 向探针溶液中加入PhSH后,由于PhSH介导的裂解反应,荧光团CP被释放,探针CPH溶液的荧光恢复,从而实现水溶液中PhSH的检测(图1). 探针CPH的荧光强度随PhSH浓度的增加而增加,线性范围为0—16 μmol·L−1. 该方法对PhSH的检测具有响应速度快(荧光强度在5 min时可达到平台期)、选择性好(不受生物硫醇的干扰)且灵敏度较高(检出限为0.13 μmol·L−1)的特点. 此外,CPH可用于HeLa细胞和环境水样中PhSH的定量测定.
一种快速识别苯硫酚的荧光探针的构建及其在细胞和环境样品中的应用
Construction of a fluorescent probe for rapid recognition of thiophenol and its application in living cells and environmental samples
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摘要: 由于苯硫酚(thiophenol, PhSH)在环境及生物体系中的剧毒性,开发可特异性识别PhSH的探针具有重要意义。本研究以香豆素为荧光团,2, 4 - 二硝基苯磺酰胺为识别单元,基于分子内光诱导电荷转移机制,开发了一种新型的荧光增强型探针CPH,实现PhSH的检测。该探针能高选择性、高灵敏度地区分生物硫醇和PhSH,具有细胞渗透性好、毒性低、响应快的特点。值得注意地是,探针CPH可对不同浓度的PhSH迅速做出反应,具有良好的定量检测PhSH的能力,线性响应范围为0—16 μmol·L−1,检出限为0.13 μmol·L−1。此外,新型探针可成功检测HeLa细胞中的PhSH,且可定量测定水样中PhSH的含量,回收率可达95%以上。实验结果表明探针在环境科学和生物科学领域具有广阔的应用前景。Abstract: Due to the extreme toxicity of thiophenol in environmental and biological systems, it is of great significance to develop a probe for the specific recognition of thiophenol. In this study, a novel off-on fluorescent probe CPH was developed using coumarin as the fluorophore and 2, 4-dinitrobenzene sulfonate as the recognition unit based on intramolecular photo-induced charge transfer mechanism. This probe exhibiting good cell permeability, low toxicity and fast response can distinguish thiophenol from biothiols with high selectivity and sensitivity. It is noteworthy that the probe CPH can quickly respond to different concentrations of thiophenol, and a good linear relationship between the fluorescence intensity of CPH and thiophenol concentration (0—16 μmol·L−1) was performed, displaying a limit of detection of 0.13 μmol·L−1. In addition, the new probe has been successfully used for determining thiophenol in HeLa cells and environmental water samples with a recovery of more than 95%, indicating that the probe CPH has a broad application prospect in environmental science and biological science.
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Key words:
- fluorescent probe /
- thiophenol /
- high selectivity /
- cell imaging /
- environmental water samples
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表 1 CPH检测环境水样中的PhSH(n = 3)
Table 1. CPH detection of PhSH in environmental water samples (n = 3)
样品
Sample加入量/(μmol·L−1)
Adding amount测得量a± SDb/(μmol·L−1)
Determinations回收率/%
Recovery rateRSD/% 自来水 0.0 0.0±0.1 — — 2.0 1.9±0.1 95.0 3.0 6.0 5.9±0.1 98.3 1.2 10.0 10.4±0.2 104.0 1.5 汉江水 0.0 0.0±0.1 — — 2.0 1.9±0.1 95.0 3.3 6.0 6.1±0.2 101.7 2.8 10.0 10.3±0.3 103.0 2.7 a3次测量平均值. aMean of three determinations。b标准偏差. bStandard deviation -
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