Visual and Real-Time Luminescence Detection of Norfloxacin Based on a High-Nuclearity Cd(II)–Eu(III) Nanomolecular Sensor through Functionalized Sodium Alginate Film and Smartphone Scanning

Rapid and accurate detection of norfloxacin (NFX), which is one of the most consumed multifluorinated quinolone antibiotics, has attracted much attention due to the fact that the excessive use of NFX may cause serious health complications, and it has been considered as a harmful pollutant to the environment. We report the construction of linear 20-metal Cd(II)–Eu(III) nanocluster 1 (1.0 nm × 1.5 nm × 4.2 nm) by the use of a vanillin-type ligand for luminescence detection of NFX with high sensitivity and selectivity. The enhancement of Eu(III) emission of 1 caused by NFX is expressed by I_615nm = k × [NFX] + a. The luminescence color change of 1 to dark red caused by NFX is used to qualitatively check NFX by prepared test strips and 1@SA films. Furthermore, the accurate and real-time detection of NFX can be achieved by smartphone scanning.