Synthesis of a novel kind of uniform fluorescent silica colloids and their assembled photonic film for sensitive detection of Cu2+ ions

A novel fluorescent photonic crystal (FPC) film is created for the first time via self-assembly of a new kind of uniform fluorescent silica colloids. The fluorescent silica colloids have first been synthesized by combination of stöber method and direct calcination, which are then used as building blocks for formation of FPC films with opal structure via vertical deposition method. The FPC films with brilliant structural colors could be obtained, depending on fluorescent silica colloids with various diameters. Importantly, the FPC films exhibit good fluorescent property, e.g., emitting blue under 365 nm UV light. Moreover, the FPC films could be used as a sensor for highly sensitive detection of copper ions concentration via dual detection mode, fluorescence and reflection mode. The FPC films not only appear low detection of limit (DOL), but show good selectivity for copper ions, various concentrations (from 1 nM to 100 μM) of copper ions could be precisely confirmed.