可视化辅助碳点荧光比色法检测水中痕量汞离子

Visualization-assisted fluorescent detection of trace mercury ions in water based on carbon dots

利用巯基功能化碳点(M-CDs)构建用于检测水中Hg^2+的荧光探针。红外光谱证实M-CDs被巯基(-SH)成功修饰,透射电镜显示M-CDs的平均粒径约为4.88 nm。XRD晶型表征显示M-CDs具有类石墨烯结构。由于银硫醇盐的团聚作用,M-CDs溶液中加入Ag^+可快速形成M-CDs/Ag的棕色沉淀,并引起M-CDs的荧光猝灭。用PBS缓冲液(0.01 mol/L,pH 7.4)溶解沉淀物而形成检测Hg^2+的荧光传感器。在传感体系中加入Hg^2+后,M-CDs荧光明显恢复。在Hg^2+浓度为0.01~0.55 nmol/L范围内,检测体系荧光恢复强度与Hg^2+浓度成良好线性关系,检测限(LOD,3σ/k)4.2 pmol/L。该探针对Hg^2+表现出良好的选择性,同时可以通过可视化辅助判断探针的选择性。该传感器可用于对实际水样的检测,为Hg^2+污染监测提供技术依据。

Mercapto functionalized carbon dots(M-CDs)were used to develop a fluorescent probe for the determination of trace Hg^2+in aqueous solutions.FTIR confirmed the successful modification of-SH on the surface of M-CDs.TEM revealed that the M-CDs had an average diameter of 4.88 nm.XRD indicated the graphene-like structure of the M-CDs.Brown precipitates of M-CDs/Ag were formed with the addition of Ag^+into M-CDs solution due to the agglomeration of silver-thiolate,leading to strong fluorescence quenching of MCDs.The fluorescent sensor for detection of Hg^2+was achieved by dissolving the precipitates in PBS buffer(0.01 mol/L,pH 7.4).Significant fluorescent recovery was observed upon the addition of Hg^2+into the nanosensor.Fluorescent intensities of M-CDs/Hg were recovered linearly in the Hg^2+concentrations range of0.01-0.55 nmol/L with an extremely low detection limit(LOD,3σ/k)of 4.2 pmol/L.The probe exhibited higher specificity to Hg^2+with the co-existence of interference metal ions.These results demonstrated that a sensitive and selective nanosensor was successfully developed for ultra-trace determination of Hg^2+.