Facile Nonenzymatic Glucose Electrode Composed of Commercial CuO Powder and Ionic Liquid Binder

Commercially available micro-sized CuO powder was dispersed in the mixture of ethanol and protonated betaine bis((trifluoromethyl)sulfonyl)amide ([Hbet][TFSA]), a hydrophobic amide-type protic ionic liquid (IL), to prepare a composite paste for the modification of screen-printed carbon electrode (SPCE) via spin-coating. The fabricated SPCE\CuO−IL composite-based electrode showed a comparable activity as that of the nanonized metal-oxide based electrodes towards the electrochemical oxidation of glucose in alkaline solutions. Hydrodynamic chronoamperometry tests performed at +0.55 V showed a linear dynamic response of the electrode over the concentration range of 1 μM–2.8 mM with a sensor-sensitivity of 0.16 μA μM⁻¹ in 0.1 M NaOH. The data also showed a linear dynamic response over the concentration range of 1 μM–4.6 mM with a sensor-sensitivity of 0.10 μA μM⁻¹ in 0.1 M NaOH with 0.1 M NaCl, indicating that the major interferant Cl⁻ had negligible effects on glucose detection. Ascorbic acid (AA) (in the physiological level) and ethanol also did not interfere with the detection. Detection of glucose in real samples showed the recovery ratios higher than 95 %. This study has clearly demonstrated that commercial CuO powder without nanostructure can provide sufficient reactivity to the electrocatalytic oxidation of glucose by using IL as the organic binder. Facile preparation of the micro-sized metal oxide-modified electrodes can be accordingly pursued.