Visual Monitoring of Levofloxacin in Biofluids by Europium(III)-Functionalized Mesoporous Silica Nanoparticles

Excess intake of levofloxacin (LVFX), an extensively used fluoroquinolone antibiotic, may trigger severe adverse symptoms. Developing a rapid and sensitive approach for LVFX detection in biofluids is vital to monitor the real-time body content. Herein, we report ammoniated mesoporous silica nanoparticles functionalized with Eu(III) to fabricate a fluorescent probe, whose fluorescence can be effectively turned on by LVFX via the fluorescent resonant energy transfer process, thus achieving its recognition of LVFX. The fabricated probe demonstrates high sensitivity (ppb level), fast response (within 1 min), and refraining from the interference of other coexisting species in biofluids. Such good sensing performance enables the nanoprobe to practically monitor LVFX levels in serum and urine. Serous LVFX is determined with a low detection limit (LOD) of 33.46 ng/mL and a linear range of 0.10–14.00 μg/mL. Urinary LVFX is determined with a LOD of 42.60 ng/mL and a linear range of 0.13–14.00 μg/mL. Moreover, a portable solid-gel-based device is also prepared for the visual detecting of LVFX, indicating the great potential of this platform to be a powerful tool for the point-of-care monitoring of the LVFX dose in the human body.