Novel water-dispersible lanthanide-grafted covalent organic framework nanoplates for luminescent levofloxacin sensing and visual pH detection

Levofloxacin (LVFX) is a fluoroquinolone antibacterial agent and widely used in the treatment of bacterial infections. However, the abuse of LVFX will do great harm to human being, and alkaline urine (pH > 7.0) with decreased solubility of LVFX will further cause adverse side effects. There is an urgent demand and great challenge to construct a mutlifunctional nano-system for the detection of LVFX and pH. We report a novel water-dispersible europium (Eu)-grafted covalent organic framework nanoplates (Eu@CON) with luminescent characteristics of Eu 3+ . Eu@CON shows high selective and sensitive luminescence sensing for LVFX with a limit of detection (LOD) at 0.51 μM. A visual test strip has been further designed and fabricated for on-site and rapid pH measurement with a detection range from 1 to 4 and 11 to 14. This proof-of-concept study not only reports a new type of luminescent LVFX and pH sensor, but also provides a promising strategy for the design of water-dispersible lanthanide-grafted luminescent CONs to further extends its application in chemo-biosensing.