MIL-100(Fe) Metal-Organic Framework Nanospheres Embedded in Graphene Matrixes for Xanthine Fluorescence Sensing

Study and application of MIL-100(Fe)-based two-dimensional graphene oxide (GO) nanocomposite was limited because the nucleation of the spherical structure of MIL-100(Fe) on GO along different directions hindered the formation of MOF-100(Fe). To address this issue, MIL-100(Fe)/three-dimensional graphene (3DG) nanocomposites (abbreviated as MIL-3DG-n, n = 25, 50, 75, and 100) were successfully fabricated via in situ growth of MIL-100(Fe) on 3DG matrixes in this work because the unique structure of 3DG can avoid the attachment with MIL-100(Fe) on nucleation sites along multiple directions, resulting in their ideal combination. The prepared MIL-3DG nanocomposites exhibited higher peroxidase-like catalytic activities than pure MIL-100(Fe), and MIL-3DG75 exhibited the best peroxidase-like activities for detecting xanthine with the detection limit of 0.0014 mu M in the linear range of 0-200 mu M to date, to the best of our knowledge, which is attributed to the higher affinity of MIL-3DG-75 nanocomposite to peroxidase substrates o-phenylenediamine (OPD) and H2O2, confirmed by the Michaelis-Menten kinetics (V-m: 49.5 x 10(-8) M s(-1) for H2O2, 18 x 10(-8) M s(-1) for OPD, K-m: 0.029 mM for H2O2, 0.011 mM for OPD). Owing to the high catalytic efficiency of the MIL-3DG-75 nanocomposite, a rapid and efficient strategy for the sensitive colorimetric detection of xanthine was established.

Automated summary

The study successfully fabricated MIL-100(Fe)/three-dimensional graphene (3DG) nanocomposites to address the issue of hindered formation of MOF-100(Fe) on two-dimensional graphene oxide. These nanocomposites showed higher peroxidase-like catalytic activities than pure MIL-100(Fe), with MIL-3DG75 exhibiting the best performance for detecting xanthine. This enhanced catalytic efficiency allowed for a rapid and efficient colorimetric detection strategy for xanthine.