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A simple and sensitive label-free electrochemical biosensor for nimodipine was fabricated by using nitrogen-doped graphene (NGE) modified electrode. The surface morphology and electron transfer behavior of the modified electrodes were studied by scanning electron microscopy and electrochemical impedance spectroscopy, respectively. The electrochemical behaviors of nimodipine at the modified electrodes were investigated by using cyclic voltammetry. On the basis of the excellent electrocatalytic activity of NGE, an obvious cathodic peak of nimodipine could be caused at the NGE modified glassy carbon electrode (GCE), moreover, the electrochemical signal was greatly enhanced compared with the undoped graphene modified GCE. Under the optimized conditions, the present sensor showed excellent performances for nimodipine detection including wide linear range of 0.02–3 μM, low detection limit (9.1 nM), good selectivity to the general coexisted interferences, etc. The proposed biosensor was also successfully applied to validate its capability for the analysis of nimodipine in tablets. The work would promote the potential application of NGE as an excellent material in fabricating electrochemical sensors for chemical or biochemical analysis. [ABSTRACT FROM AUTHOR]

A novel electrochemical sensor based on nitrogen doped graphene (NGE) and palygorskite (Pal) for the simultaneous detection of hydroquinone (HQ) and catechol (CT) has been proposed. Pal is particularly pointed out for its appreciable specific surface area and reactive-OH groups on its surface. Acid treatment Pal demonstrated better physico-chemical properties, which are propitious to electrochemical sensor construction. The introduction of NGE not only improved the poor conductivity of Pal but also served as an excellent adherent matrix. The modified electrode demonstrated the enhanced redox peak currents of HQ and CT with good discrimination. Under optimized conditions, the linear ranges for HQ and CT were 2–50 μM and 1–50 μM, with detection limit (LOD) of 0.8 μM and 0.13 μM, respectively. The result designates that the Pal/NGE composite promises to be a new eco-friendly modified material for sensor fabrication. [ABSTRACT FROM AUTHOR]

Highlights: [•] PEDOT/NGE modified electrode was fabricated via CV method using nitrogen-doped graphene (NGE) coated GCE. [•] Highly reversible and well-separated redox couples of hydroquinone (HQ) and catechol (CT) were obtained at PEDOT/NGE/GCE. [•] A facile electrochemical sensor based on PEDOT/NGE/GCE was developed for simultaneous detection of HQ and CT. [Copyright &y& Elsevier]