A ratiometric luminescence sensing platform based on lanthanide-based silica nanoparticles for selective and...

Detection of Fe(III) and Cu(II) in water is highly desirable because their abnormal levels can cause serious harm to human health and environmental safety. In this work, a ratiometric luminescence sensing platform based on lanthanide-based silica nanoparticles was constructed for the detection of Fe³⁺ and Cu²⁺ ions. The terbium-silica nanoparticles (named SiO₂@Tb) with dual-emission signals were successfully prepared by grafting Tb³⁺ ions onto trimellitic anhydride (TMA) functionalized silica nanospheres. It can serve as a ratiometric fluorescent probe for the detection of Fe³⁺ and Cu²⁺ ions in water with the green emission of Tb³⁺ ions as a response signal and the blue emission of silica nanospheres as the reference signal. Significantly, an easy-to-differentiate color change for visual detection was also realized. SiO₂@Tb shows high sensitivity even in very low concentration regions towards the sensing of Fe³⁺ and Cu²⁺ with low detection limits of 0.75 μM and 0.91 μM, respectively. Moreover, the mechanism for the luminescence quenching of SiO₂@Tb was systematically investigated, and was attributed to the synergetic effect of the absorption competition quenching (ACQ) mechanism and cation exchange. This study demonstrates that SiO₂@Tb can be employed as a promising fluorescent probe for the detection of Fe³⁺ and Cu²⁺ ions, and the combination of lanthanide ions with silica nanoparticles is an effective strategy to construct a ratiometric fluorescent sensing platform for the determination of analytes in environmental detection.