A sensitive ratiometric fluorescence method for visual detection of aluminum ion based on chelation-enhanced photoluminescence

In this work, a simple, sensitive and cost-effective ratiometric fluorescence probe was developed for visual sensing of aluminum ion based on the Chelation-Enhanced Photoluminescence (CHEP) of ciprofloxacin (CIP). In weak basic medium, CIP can sensitize Eu 3+ to emit red fluorescence based on antenna effect, and Al 3+ can enhance the blue fluorescence of CIP via CHEP. When Al 3+ was added, the CIP fluorescence intensity increased and the red fluorescence intensity decreased. And the ratiometric fluorescence intensity is proportional to the content of Al 3+ , and then the ratiometric fluorescence assay and visual sensor of Al 3+ have been proposed. The ratiometric fluorescence assay exhibits good selectivity and sensitivity with a limit of detection (LOD) of 0.60 μmol/L and a linear range of 0.6–120 μmol/L. Fluorescence lifetime , scanning electron microscopy (SEM) images, Fourier transform infrared (FTIR), UV–Visible absorption (Abs) spectra and X-ray photoelectron spectra (XPS) were characterized for the mechanism study. The proposed method has been successfully applied for Al 3+ sensing in real samples with a recovery of 99.46%–105.42% and RSD ≤ 3.03%.