a b s t r a c tEnsembles of copper nanowire electrodes (CuWNEEs) are prepared via electrodeposition in track-etched polycarbonate membranes. Three different preparation methods are compared showing that the better results in terms of sensor durability and reproducibility are achieved by pre-sputtering a thin gold film on the templating membrane and attaching it to a supporting electrode by exploiting the adhesion property and ionic conductivity of a thin Nafion interlayer. SEM-EDS analyses together with double layer charging currents measurements indicate that these arrays are formed by copper nanowires with 400 nm diameter, 10 m length distributed with a spatial density of 1 × 10 8 nanowires/cm 2 . The voltammetric reduction of nitrate at CuWNEEs is characterized by a well-resolved cathodic peak at approximately −0.680 V vs Ag/AgCl, whose current scales linearly with the nitrate concentration in the 10-400 M range. The limit of detection (LOD) achieved by simple linear sweep voltammetry is in the 1.7-3.0 M range, depending on the CuWNEE preparation method, such LOD values being among the lowest reported up to now in the literature. The possibility to use CuWNEEs in chloride and nitrite containing water samples is demonstrated.

This review deals with recent advances in bioelectroanalytical applications of nanostructured electrodes, in particular nanoelectrode ensembles (NEEs) and arrays (NEAs). First, nanofabrication techniques, principles of function, and specific advantages and limits of NEEs and NEAs are critically discussed. In the second part, some recent examples of bioelectroanalytical applications are presented. These include use of nanoelectrode arrays and/or ensembles for direct electrochemical analysis of pharmacologically active organic compounds or redox proteins, and the development of functionalized nanoelectrode systems and their use as catalytic or affinity electrochemical biosensors.

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We demonstrate the application of closed bipolar electrochemistry for the asymmetrical deposition of metals and metal oxides on bipolar electrodes of decreasing dimensions, down to the nanoscale. We focus on the asymmetrical deposition of semiconducting oxides (TiO2, Cu2O, or Co2O3) and Pt on glassy carbon disks, carbon microwires, and gold nanowires. The optimization of the process is studied by using a four‐electrode voltammetric cell. Scanning electron microscopies and energy‐dispersive X‐ray spectroscopy confirm the achievement of the desired deposition. Electron backscatter diffraction identifies cuprite in all of the Cu2O deposits. Closed bipolar electrochemistry allows the bipolar functionalization of carbon materials and gold nanowires by using electrolytes that are unsuitable for open bipolar electrochemistry, applying a potential difference as low as 1 V. For the first time, Janus like nanosized objects are obtained by closed bipolar electrochemistry.