Fe-MOF-NH₂@Metformin as a Peroxidase-Like Activity for Fluorometric Glucose Sensing

In this research, an amine-containing metal-organic framework was modified with metformin (Fe-MOF-NH₂@metformin) and used as peroxidase-like activity for fluorometric determination of glucose. The best fluorescence emission intensity (λ_m = 450 nm) was found at the excitation wavelength of λ_ex = 350 nm. Results indicated that H₂O₂ and glucose can effectively quench the fluorescence emission of Fe-MOF-NH₂@metformin, and the fluorescence intensity linearly decreased with increasing concentration of H₂O₂ or glucose. Moreover, the quenching effect of H₂O₂ is considerably enhanced in the presence of dopamine, and hence, this compound plays a role of synergistic effect in the quenching process, and accordingly, the spectra are more differentiated and more distinguishable. The Stern-Volmer quenching constant (K_SV) for H₂O₂ and glucose were obtained at 0.005 and 0.004 M^-1, respectively. The binding constant (K_b) and the site number (n) of Fe-MOF-NH₂@metformin were also investigated and discussed. The K_b and n for glucose were obtained at 209 and 0.6839, likewise for H₂O₂, 77 and 0.5484, respectively. The detection limits for measuring glucose and H₂O₂ were obtained 0.511 and 0.351 μM, respectively.