基于碳纳米点聚集诱导发光的比率荧光可视化检测土壤中Hg2+

Detection of Hg2+ in soil with high performance is of great significance for the ecological environment and human health. Ratiometric fluorescent sensors have been widely used for the detection of Hg2+. However, most of the ratiometric fluorescent probes for Hg2+ analysis are organic molecules, which have difficult synthesis route and poor solubility in water. Moreover, the signal output mode of most ratiometric fluorescent sensors is “turn off”, which has high optical background, thus the sensitivity and selectivity need to be further improved. For this purpose, the project is focus on synthesizing a novel ratiometric fluorescent probe and developing a “turn on” modal fluorescent sensor for Hg2+ detection. Firstly, carbon nanodots (CDs) with aggregation-induced emission (AIE) property will be prepared and combined with semiconductor quantum dots (QDs) to form a novel ratiometric fluorescent probe. The CDs-QDs probe possesses excellent water solubility as it is consist of two inorganic nanomaterials. Then, Hg2+ aptamer will be modified on the surface of the ratiometric fluorescent probe. Upon the addition of Hg2+, the probes will aggregate induced by the T-Hg-T interaction. Detection mechanism of Hg2+ on the sensing interface will be investigated and new sensing method will be developed to reduce the background signal and improve the sensitivity of turn off-based sensor. Finally, portable paper-based sensor will be fabricated to quickly and visually analyze Hg2+ in soil.

土壤中Hg2+的高性能检测对维护生态环境、保护人体健康具有重要意义。针对现有检测Hg2+比率荧光传感技术中探针合成难、水溶性差，荧光信号输出模式为猝灭（turn off）型、背景信号高等难题，本项目拟设计并合成具有聚集诱导发光（AIE）性能的碳纳米点（CDs），并与半导体量子点（QDs）复合，制备新型比率荧光探针，该探针由两种无机纳米材料组成，具有良好的水溶性；进一步在比率荧光探针表面修饰Hg2+适配体，建立信号输出模式为增强（turn on）型的新型比率荧光传感界面，利用T-Hg-T特异性作用引发比率荧光探针聚集，探究Hg2+在传感界面的检测机理，发展新型传感方法，解决turn off型传感器背景信号大、灵敏度低的问题；最后，构建纸基比率荧光传感器，根据其颜色与Hg2+浓度关系，实现土壤中Hg2+的高性能、可视化分析。

在国家基金委青年科学基金项目（61801195）资助下，我们在前期工作基础上，按照项目原定计划开展实验，发现碳基量子点（氮掺杂碳量子点、氮掺杂石墨烯量子点、氮化碳量子点等）可以作为电化学发光（ECL）试剂三联吡啶钌（Ru(bpy)32+）及其衍生物的新型共反应剂。因此，在新型自增强ECL复合材料的设计制备、传感器组装及重金属离子检测等方面，开展了一系列研究工作，并取得了多项有价值的研究成果，顺利完成了项目预期目标。主要工作包括：利用反相微乳法、静电作用、静电纺丝等技术，将Ru(bpy)32+和碳基量子点复合，成功制备了多种新型自增强ECL复合材料，为发展高灵敏的重金属离子检测方法提供了潜在的优势；在此基础上，引入具有特异性识别能力的适配体，实现了重金属离子的高灵敏、高选择性分析；进一步，耦合信号放大策略，提升传感器的分析性能。另外，我们还成功发展了一种基于碳基量子点-半导体量子点双荧光探针的比率荧光传感策略，实现了对目标物的灵敏、准确分析，研究内容具有重要意义和潜在的应用前景。项目资助期间（2019.01-2021.12），以第一作者或通讯作者在Biosensors and Bioelectronics、Journal of Hazardous Materials、Food Chemistry等国际期刊发表SCI学术论文14篇，其中，IF＞10.0的2篇；10.0>IF>5.0的10篇；一篇入选“ESI高被引论文”；授权中国发明专利1项，较好地完成了项目书中提出的论文产出目标。