含缩硫醛基团荧光染料的设计、合成及其对汞离子的传感研究

Recently, the design and development of sensors with excellent performance for mercury ions has been fuelled due to its serious hazard to both human health and the biological reproduction. As we know from the textbook of basic organic chemistry, mercury can promote the deprotection reaction of the dithioacetal to generate the corresponding aldehyde group, which can serve as the basis of mercury-selective sensor. This chemical reaction can be conducted rapidly at room temperature and the reaction condition is rather mild, which is beneficial to the rapid and real-time detection of mercury ion. On the other hand, traditional fluorescent dyes have been widely used in the design of chemosensors and possess innate performance because of their good water-solubility, photo-stability as well as biocompatibility. Moreover, such sensors can be conveniently used for in situ, real-time and non-destructive detection of target molecules in biological systems. With these considerations in mind, this project focuses on the design of special reaction-based sensors for mercury ion taking advantage of traditional fluorescent dyes as the fluorophore moiety and the dithioacetal group as a putative mercury-dependent reactive subunit. Through the ingenious molecular design, it is expected that new reactive chemsensors towards mercury can be designed and developed, featuring excellent sensing properties. First, taking advantage of the fluorescein, coumarin, and rhodamine dyes, new sensors with better water-solubility and higher sensitivity towards mercury ions are desired to realize the practical detection in real samples such as drinking water, food and environmental samples. Second, by virtue of the outstanding performance of cyanine dyes, it is expected to develop reaction-based near-infrared fluorescent chemosensors for mercury ions and achieve the successful application in fluorescent imaging of living cells and organisms. Last, we will summarize the structure-property relationship of the sensing system to guide the design of future sensors.

汞离子是一种严重危害人体健康及生物繁衍的有毒重金属离子，设计和开发优秀的汞离子传感器已成为研究的热点。缩硫醛脱保护反应可作为汞离子传感器设计的基础，其优势在于速率快、反应条件温和，有利于实现对汞离子的快速、实时检测。另一方面，传统荧光染料被广泛应用于化学传感器的设计之中，表现出良好的水溶性、光稳定性和生物相容性，可方便地用于生物体系中目标分子的原位、实时、无损伤检测。本项目中，我们拟以缩硫醛为反应活性基团，以传统荧光染料为荧光团，通过巧妙的分子设计将二者连接起来，希望获得性能优异的反应型汞离子传感器。首先，拟利用荧光素、香豆素、罗丹明类荧光染料的优异性能，发展水溶性好、灵敏度高的汞离子传感器，实现在饮用水、食品、环境样品等实际样品中的检测；其次，以菁染料为母体，获得反应型近红外荧光传感器，希望实现细胞及生物活体中汞离子的荧光成像分析；再次，归纳该传感体系的构效关系，以指导今后传感器的设计。

利用化学传感器来检测环境中的有害物质已成为一个新兴的研究热点。其中，光信号可以通过化合物发射或者吸收光谱的变化来反映分子之间的相互作用，具有灵敏度高、专一性强、样品处理简易及操作过程方便、响应速度快等优点，因此，近几年来，以光信号为输出信号的荧光化学传感器和比色化学传感器颇受人们的青睐。本项目中，我们设计并合成了一系列性能优异的光学传感器，通过光谱测试了它们对客体分子的传感性能，系统地研究了它们的传感机理，归纳总结了有机化合物分子的构效关系，取得一些有意义的结果。其中，基于缩硫醛脱保护反应的汞离子传感器，可实现对汞离子的快速、实时检测，尤其是生物细胞中的荧光成像；利用亚硫酸氢根与醛基的亲核加成反应，发展了可高灵敏度检测HSO3-离子的比率荧光传感器，发射光谱位移了120 nm, 检出限为9×10-7 mol/L；基于氧化反应的次氯酸根荧光传感器具有良好的水溶性，可以在含较少有机溶剂的混合溶剂中实现对次氯酸根的检测。化学反应选择性高，因此该传感器分子能够实现对次氯酸根的特异性识别与检测，即使在背景离子存在下仍然能够高效地检测出次氯酸根；基于置换法的阴离子传感器，可实现对硫离子的定量分析与检测，以及对生物氨基酸和酶活性的检测。综上所述，本项目的成果拓宽了该领域的研究，为新型化学传感器的设计提供了新的思路和方法。