Copper hydroxide nanostructure-modified carbon ionic liquid electrode as an efficient voltammetric sensor for detection of metformin: a theoretical and experimental study

The electrocatalytic oxidation of metformin (MET) was investigated at Cu(OH)2 nanoparticle-modified carbon ionic liquid electrode (Cu(OH)2/CILE). This electrode exhibited excellent characteristic for the electrocatalytic oxidation of metformin at the potential of +0.6 V with good sensitivity and selectivity. The presence of Cu(OH)2 nanostructures in the composite electrode leads to the appearance of oxidation peak of MET. Under optimal experimental conditions, the peak current response increased linearly with metformin concentration over the range of 1 µM–4 mM. The detection limit of the method is 0.5 µM. Moreover, the closer look was taken at the electronic properties of MET and its Cu (II) complexes such as frontier molecular orbital (HOMO and LUMO) and binding interaction energies using density functional theory. Effect of pH was also investigated at B3LYP/6-311++g** level. Theoretical results confirmed the experimental evidences of Cu (II) complexation. Therefore, Ease of preparation, wide linear range, low overpotential, high sensitivity and selectivity provide the possibility of applying this method for the detection of MET in biological samples.