Synergetic effects between a bipyridyl-functionalized metal-organic framework and graphene for sensitive electrochemical detection of norepinephrine

A sensitive and simple electrochemical sensor for determination of norepinephrine (NE) was developed. The electrode (ERG-UiO-67-bpy/GCE) was fabricated by modifying the glassy carbon electrode with a Zr (IV) metal-organic framework (MOF) with 2,2-bipyridyl-5,5-dicarboxylate (UiO-67-bpy) and graphene oxide (GO), followed by electrochemical reduction of GO to ERG (electrochemically reduced graphene). The ERG and UiO-67-bpy components of the composite electrode show a synergic electrocatalytic effect, leading to much enhanced voltammetric response to the oxidation of NE. Comparative studies indicate that the hydrogen bonds between the bipyridyl moiety of the MOF and the 2-aminoethanol moiety of NE play an important role in promoting electron transfer on the electrode surface. Differential pulse voltammetry using the composite electrode shows a wide linear-response concentration range with a submicromolar detection limit of 0.026 μM. The sensor shows good reproducibility and stability and also be used for sensitive simultaneous detection of NE and uric acid.