Ratiometric fluorescence nanoplatform integrated with smartphone as readout device for sensing trace water

In our investigation, a smartphone-integrated ratiometric fluorescent sensing system with lanthanide-based infinite coordination polymers (Ce-GMP-DPA@Tb-DPA) as signal probe has been successfully constructed for sensitive and portable detection of water in organic solvents. The Ce-GMP-DPA presents blue luminescence which is suppressed once the Tb-DPA is integrated to form the complex of Ce-GMP-DPA@Tb-DPA. Due to the energy transfer from Ce to Tb, the as-formed Ce-GMP-DPA@Tb-DPA exhibits green fluorescence of Tb-DPA. The presence of water can decompose the Tb-DPA, which blocks energy transfer from Ce to Tb, resulting in the decrease of green emission of Tb-DPA and the recovery of blue emission of Ce-GMP-DPA. Therefore, a ratiometric fluorescence assay is established for quantitative water detection within a wide linear range from 0.2 to 90.0% in ethanol. The limit of detection (LOD) reaches as low as 0.16% in ethanol, 0.62% in THF, and 0.0076% in acetonitrile, respectively. Furthermore, a smartphone installed with Color Picker APP as signal reader and analyzer is designed to integrate with the detection assay. With white spirit as real sample, water can be on-site detected with high accuracy (RSD < 2.81%). The developed platform presents great potential for portable water detection in practical application with merits of low cost, easy carry, and simple operation.