A rapid fluorescent ratiometric Ag+ sensor based on synthesis of a dual-emission ternary nucleotide/terbium complex probe

Abstract To develop a fast, isothermal, enzyme-free and visible method for the on-site detection of silver ions (Ag+), a ratiometric Ag+ sensor was constructed based on a dual-emission ternary nucleotide terbium probe, fabricated by synthesizing the luminescent nanomaterial Luminol-GMP-Tb (LGT). We repositioned the fluorescent properties of the nanomaterial from the perspective of the inherent optical properties of two signal reporters (luminol and Tb3+) through highlighting the absorption, fluorescence steady-state measurement and time-resolved properties. Furthermore, based on the ingenious coordination interaction and energy transfer among Ag+, luminol and GMP-Tb, we hypothesized and confirmed that Ag+ induced morphology and luminescence changes of LGT through scanning electron microscopy and lifetime changes as well as fluorescence changes. Meanwhile, by means of a portable ultraviolet detector with dual wavelengths, based on the fluorescence excitation characteristics of each component, different photoluminescence color phenomena presented at different excitation wavelengths. Therefore, visual qualitative detection could be realized under a portable UV lamp with 254 nm for mainly visible green color change while 365 nm as built-in reference for blue-emitting luminol. The ratio calculation method and the enhanced luminescence ratio mechanism made LGT exhibited extremely high selectivity to Ag+. Quantitative detection Ag+ was realized in two ranges of 0.1 μM ~ 6 μM and 6 μM ~ 100 μM with a minimum detection limit of 65 nM. The method has been successfully exploited in real water samples with recovery rate between 99.7% and 106.38%, showing broad application prospects in food safety and environmental monitoring for the on-site detection of Ag+.