Abstract：
Tetracycline (TC) is extensively utilized in livestock breeding, aquaculture, and medical industry. TC residues seriously harm food security, the environment, and human health. There is an urgent need to exploit a highly efficient and sensitive testing method to monitor TC residue levels in aquatic environments. In this study, graphitic carbon nitride quantum dots (g-CNQDs) were successfully synthesized by a one-step microwave-assisted method using citric acid and urea as precursors. The as-prepared g-CNQDs with size of 1.25-3.75 nm exhibited bright yellow fluorescence at 523 nm when excited at 397 nm. Interestingly, this characteristic fluorescence emission of g-CNQDs could be selectively and efficiently quenched by TC. Based on this phenomenon, for TC detection was successfully explored and applied in real water samples. Wide linear scope of 7-100 μM, low detection limit (LOD) of 0.48 μM, satisfactory recovery of 97.77%-103.4%, and good relative standard deviation (RSD) of 1.05-5.87% were obtained. Mechanism investigations revealed that the static quenching and the inner filter effect (IFE) were responsible for this fluorescence quenching between g-CNQDs and TC. This work not only provided a facile approach for g-CNQDs synthesis but also constructed a g-CNQDs-based fluorescent sensor platform for the highly sensitive and selective detection of TC in aquatic environments.
摘要：
四环素(TC)在家畜育种中被广泛应用,水产养殖,和医疗行业。TC残留严重危害食品安全,环境,和人类健康。迫切需要开发一种高效和灵敏的测试方法来监测水生环境中的TC残留水平。在这项研究中,以柠檬酸和尿素为前体，通过一步微波辅助法成功合成了石墨氮化碳量子点（g-CNQDs）。制备的大小为1.25~3.75nm的g-CNQD在397nm激发时，在523nm处表现出亮黄色荧光。有趣的是,g-CNQDs的这种特征荧光发射可以被TC选择性和有效地猝灭。基于这种现象,成功探索并应用于实际水样中的TC检测。7-100μM的宽线性范围，低检测限(LOD)为0.48μM，令人满意的回收率为97.77%-103.4%，相对标准偏差(RSD)为1.05-5.87%。机理研究表明，静态猝灭和内部过滤效应（IFE）是g-CNQD和TC之间荧光猝灭的原因。这项工作不仅为g-CNQDs的合成提供了一种简便的方法，而且还构建了基于g-CNQDs的荧光传感器平台，用于在水生环境中高度敏感和选择性地检测TC。
