比率荧光传感器对硝酸根的快速可视化检测

Rapid visual detection of nitrate by ratiometric fluorescent sensor

采用简单、低成本的方法合成一种金纳米团簇(Au NCs)/蓝色碳点(BCDs)体系的比率荧光探针,用于可视化的快速检测亚硝酸根(NO2-)。NO2-可快速且选择性地淬灭Au NCs的红色荧光,BCDs的蓝色荧光作为参考信号不受NO2-的影响。在紫外光激发下,比率荧光探针的荧光颜色随着NO2-的增加从红色变成蓝色。通过研究比率荧光探针的响应时间,该反应体系可以在2 min内完成反应。比率荧光探针的荧光强度比与NO2-浓度在75~200μmol/L范围内有良好的线性关系,检测限(LOD)低至0.8μmol/L。以钒离子作为还原剂将NO3-还原为NO2-,还原率达到90%以上,比率荧光探针可以间接检测NO3-浓度,检测限低至0.6μmol/L。采用该探针对水样和土样测定,加标回收率为94.7%~104.51%。测定结果与分光光度法基本一致,实现了对NO2-的快速、灵敏、准确的检测。基于此,构建了荧光试纸,其展现出对NO2-的高选择性和高灵敏性。荧光试纸不仅提高了检测效率,还降低了检测成本,通过实验证明其快速半定量检测真实样品中NO3-的可行性。

One Au NCs/blue carbon dots-based ratiometric fluorescent probe, which was synthesized by a simple and low-cost method, was developed to detect NO2-rapidly and visually. The red fluorescence of Au NCs can be quenched by NO2-sensitively and selectively, while the fluorescence of BCDs acting as background reference, remained blue. The probe showed colour changes from red to blue under ultraviolet in response to NO2-. By studying the response time of the ratiometric fluorescence probe, the reaction system could complete the reaction within 2 minutes. The fluorescence intensity ratio of the ratiometric fluorescent probe had a good linear relationship with NO2-concentration in the range of 75-200 μmol/L with a detection limit(LOD) as low as 0.8 μmol/L. NO3-was reduced to NO2-with vanadium ion as reducing agent, and the reduction rate can reach more than 90%. Therefore, NO■ concentration was detected by ratiometric fluorescent probe indirectly, with a detection limit of 0.6 μmol/L. The method was applied to the determination of NO■ in water and soil samples, and the spiked recovery rate was between 94.7%-104.51%. The measured results were basically consistent with the spectrophotometric method, which realized the rapid, sensitive and accurate detection of NO3-. Based on this, a fluorescent test paper has been constructed and it showed high selectivity and sensitivity to NO2-. The fluorescent test paper not only extraordinarily improved the detection efficiency, but also cut down its cost. The feasibility of rapid semi-quantitative detection of NO3-in real samples by fluorescent test paper was proved by experiments.