Enhanced glucose sensing based on a novel composite CoII-MOF/Acb modified electrode

Abstract

A novel electrochemical sensor composed of a composite of Co ^II-MOF/acetylene black exhibits enhanced sensing behavior for glucose detection.

Abstract

In this work, we demonstrate the synthesis and application of a novel Co ^II-based metal–organic framework {[Co ₂(Dcpp)(Bpe) _0.5 (H ₂O)(μ ₂-H ₂O)]·(Bpe) _0.5} _n (Co ^II-MOF, H ₄Dcpp = 4,5-bis(4′-carboxylphenyl)-phthalic acid, Bpe = 1,2-bis(4-pyridyl)ethane) as an electrochemical sensor for glucose detection. Single-crystal X-ray diffraction analysis shows that the Co ^II-MOF has a two-dimensional (2D) bilayer structure composed of Co ₂ units and Dcpp ⁴⁻ ligands. There are two kinds of Bpe in the structure: one serves as a bidentate ligand linking two Co1 atoms in each 2D layer; the other is just free in the lattice. The Co ^II-MOF modified glassy carbon electrode (GCE) shows good electrocatalytic activity towards glucose oxidation. To further improve the catalytic activity of the electrode, a new composite of Co ^II-MOF/acetylene black (Co ^II-MOF/Acb) was constructed. The Co ^II-MOF/Acb modified electrode exhibits enhanced sensing behavior for glucose detection. The sensing performance of Co ^II-MOF/Acb/GCE with different Acb loadings was investigated in detail. The results demonstrate that Co ^II-MOF/GCE with 2% Acb (Co ^II-MOF/Acb-2%/GCE) exhibits the best sensing behavior, including a high sensitivity of 0.255 μA μM ⁻¹ cm ⁻² and a wide linear range of 5–1000 μM, as well as a low detection limit of 1.7 μM (S/N = 3). It's worth noting that the linear range of Co ^II-MOF/Acb-2%/GCE was extended by more than ten times when compared to that of Co ^II-MOF/GCE without Acb addition. In addition, Co ^II-MOF/Acb-2%/GCE shows good selectivity and stability in the sensing process.