A nanoporous gold film (NPGF) was prepared onto a gold electrode surface using a facile and green electrochemical approach via anodization at 2.0 V in 0.5 mol L(-1) H2SO4. The as-synthesized NPGF electrode showed superior electrocatalytic activity towards dissolved oxygen reduction at a low overpotential (-0.045 V) along with 2-fold enhanced sensitivity.

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We report a novel seedless Hg(2+)-induced synthetic approach for the preparation of gold nanostructures. This protocol is demonstrated for the highly selective and sensitive naked eye detection of Hg(2+) based on the high affinity metallophilic Hg(2+)-Au(+) interaction. The response time upon exposure to Hg(2+) is almost instantaneous.

Nanoporous gold (NPG) structures were prepared on the surface of a gold microelectrode (Au-μE) by an anodization-reduction method. Cyclic voltammetry and field emission scanning electron microscopy were used to study the electrochemical properties and the morphology of the nanostructured film. Voltammetry showed an improved sensitivity for dopamine (DA) oxidation at this microelectrode when compared to a bare gold microelectrode, with a peak near 0.2 V (vs. Ag/AgCl) at a scan rate of 0.1 V s. This is due to the increased surface area and roughness. Square wave voltammetry shows a response that is linear in the 0.1-10 μmol L DA concentration range, with a 30 nmol L detection limit and a sensitivity of 1.18 mA (μmol L) cm. The sensor is not interfered by ascorbic acid. The reproducibility, repeatability, long-term stability and real sample analysis (spiked urine) were assessed, and acceptable performance was achieved. The "proof-of-concept" detection of dopamine release was demonstrated by using scanning electrochemical microscopy (SECM) with the aim of future applications for single cell analysis. Graphical abstract A reproducible electrochemical approach was proposed to fabricate an NPG-microelectrode for DA detection, with enhanced sensitivity and selectivity. Besides, a proof-of-concept detection of DA release was also demonstrated by using SECM.

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