Ultra-sensitive detection of hydrogen peroxide and levofloxacin using a dual-functional fluorescent probe

Herein, a flower-shaped fluorescent probe was proposed for hydrogen peroxide (H2O2) and levofloxacin (LVF) sensing based on MoOx QDs@Co/Zn-MOFs with porous structure. Both MoOx QDs and Co/Zn-MOFs exhibited peroxidase-like properties, and the combination of them greatly aroused the synergistic catalytic capabilities between them. In o-Phenylenediamine (OPD)−H2O2 system, MoOx QDs@Co/Zn-MOFs efficiently catalyzed H2O2 to produce •OH and then oxidized OPD to its oxidation product (OxOPD). The OxOPD could not only emit blue fluorescence, but also inhibit the fluorescent intensity of MoOx QDs through fluorescence resonance energy transfer (FRET). Moreover, when introducing LVF into the system, the fluorescent intensities of MoOx QDs increased along with the aggregation of themselves while that of OxOPD remained unchanged, which was explained by the joint behavior of FRET and photo-induced electron transfer (PET) instead of the conventional aggregation-induced emission enhancement (AIEE). With these observation, the proposed probe was employed for H2O2 and LVF determination in biological samples with the limit of detection (LOD) of 32.60 pmol/L and 0.85 μmol/L, respectively, suggesting the method holds great promises for trace H2O2 and LVF monitoring in eco-environment. [Display omitted] •The MoOx QDs@Co/Zn-MOFs probe with hydrangea shape was facile synthesized.•The probe combines fluorescent and synergistic enzyme-like catalytic properties.•The probe shows superior sensing performance for H2O2 with a LOD of 32.60 pM.•The probe holds great promise for H2O2 and LVF monitoring in authentic samples.