A facile Au nanoplates and reduced graphene oxide (RGO) modified glassy carbon electrode (GCE) was fabricated via a simple electrochemical method, denoted as Au/RGO/GCE. The Au/RGO/GCE electrode was used for the simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The modified electrodes fabricated by different methods presented different morphologies and performances for determination of AA, DA, and UA. Three well-defined voltammetric peaks along with remarkable increasing electrooxidation currents were obtained on the Au/RGO/GCE with needle-like Au nanoplates in differential pulse voltammetry (DPV) measurements. It was found that there are linear relationships between the peak currents and the concentrations in the range of 2.4 × 10 −4 to 1.5 × 10 −3  M (AA), 6.8 × 10 −6 to 4.1 × 10 −5  M (DA), and 8.8 × 10 −6 to 5.3 × 10 −5  M (UA), and the limits of simultaneous determination (based on S/N  =  3) are 5.1 × 10 −5  M, 1.4 × 10 −6  M, and 1.8 × 10 −6  M for AA, DA and UA, respectively. Additionally, the Au/RGO/GCE electrode presented well anti-interference ability, stability and reproducibility.

A facile electrochemical sensor based on reduced graphene oxide and Au nanoplates modified glassy carbon electrode for simultaneous detection of ascorbic acid, dopamine and uric acid

Since the early 70s electrochemistry has been used as a powerful analytical technique for monitoring electroactive species in living organisms. In particular, after extremely rapid evolution of new micro and nanotechnology it has been established as an invaluable technique ranging from experiments in vivo to measurement of exocytosis during communication between cells under in vitro conditions. This review highlights recent advances in the development of electrochemical sensors for selective sensing of one of the most important neurotransmitters—dopamine. Dopamine is an electroactive catecholamine neurotransmitter, abundant in the mammalian central nervous system, affecting both cognitive and behavioral functions of living organisms. We have not attempted to cover a large time-span nor to be comprehensive in presenting the vast literature devoted to electrochemical dopamine sensing. Instead, we have focused on the last five years, describing recent progress as well as showing some problems and directions for future development.

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New trends in the electrochemical sensing of dopamine.

Building with bubbles: the formation of high surface area honeycomb-like films via hydrogen bubble templated electrodeposition

In this paper we will review the state-of-the-art in the application of shape-controlled metal nanoparticles in Electrocatalysis, especially in reactions of interest in PEMFCs such as O2reduction and CO, methanol, ethanol and formic acid electrooxidations. In particular, we will focus our attention on shape-controlled platinum (Pt), gold (Au) and palladium (Pd) nanoparticles. In addition, electrocatalytic applications of shape-controlled Pt-based alloy nanoparticles will be also reviewed. The results reported will highlight how important can be controlling the shape of the nanocatalyst and how effective this parameter may be to improve the activity and thus, develop highly active electrocatalysts.

Shape dependent electrocatalysis

A cotton fabric was coated with a polymer that contains both poly(dimethyl siloxane) (PDMS) and poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA). When the repeat unit number of PDMS is about three-fold that of PDMAEMA and the fabric is exposed to air, the fabric is superhydrophobic because PDMS in the coating covers the PDMAEMA chains. Upon contact with an oil-in-water emulsion, the water-soluble PDMAEMA rises to the top and the side in contact with the emulsion becomes hydrophilic. The emerged PDMAEMA chains then cause the emulsion droplets to coagulate, and the aggregated oil fills the pores on the superhydrophobic side of the fabric. The oil-impregnated side remains hydrophobic even upon prolonged contact with water. Thus, a Janus fabric is elegantly generated in situ and sustained. This easy-to-prepare Janus fabric rapidly and efficiently separates oil from emulsions and may find practical applications.

In Situ Generated Janus Fabrics for the Rapid and Efficient Separation of Oil from Oil-in-Water Emulsions

The synthesis of organic semiconducting materials based on silver and copper-TCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane) and their fluorinated analogues has received a significant amount of attention due to their potential use in organic electronic applications. However, there is a scarcity in the identification of different applications for which these interesting materials may be suitable candidates. In this work, we address this by investigating the catalytic properties of such materials for the electron transfer reaction between ferricyanide and thiosulphate ions in aqueous solution, which to date has been almost solely limited to metallic nanomaterials. Significantly it was found that all the materials investigated, namely CuTCNQ, AgTCNQ, CuTCNQF4 and AgTCNQF4, were catalytically active and, interestingly, the fluorinated analogues were superior. AgTCNQF4 demonstrated the highest activity and was tested for its stability and re-usability for up to 50 cycles without degradation in performance. The catalytic reaction was monitored via UV-vis spectroscopy and open circuit potential versus time measurements, as well as an investigation of the transport properties of the films via electrochemical impedance spectroscopy. It is suggested that morphology and bulk conductivity are not the limiting factors, but rather the balance between the accumulated surface charge from electron injection via thiosulphate ions on the catalyst surface and transfer to the ferricyanide ions which controls the reaction rate. The facile fabrication of re-usable surface confined organic materials that are catalytically active may have important uses for many more electron transfer reactions.

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Reusable surface confined semi-conducting metal-TCNQ and metal-TCNQF4 catalysts for electron transfer reactions

Electrochemical detection of dopamine and cytochrome c at a nanostructured gold electrode

Electrochemical formation of porous copper 7,7,8,8-tetracyanoquinodimethane and copper 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane honeycomb surfaces with superhydrophobic properties

A nanostructured gold surface consisting of closely packed outwardly growing spikes is investigated for the electrochemical detection of dopamine and cytochrome c. A significant electrocatalytic effect for the electrooxidation of both dopamine and ascorbic acid at the nanostructured electrode was found due to the presence of surface active sites which allowed the detection of dopamine in the presence of excess ascorbic acid to be achieved by differential pulse voltammetry. By simple modification with a layer of Nafion, the enhanced electrocatalytic properties of the nanostructured surface was maintained while increasing the selectivity of dopamine detection in the presence of interfering species such as excess ascorbic and uric acids. Also, upon modification of the nanostructured surface with a monolayer of cysteine, the electrochemical response of immobilised cytochrome c in two distinct conformations was observed. This opens up the possibility of using such a nanostructured surface for the characterisation of other biomolecules and in bio-electroanalytical applications.

The fabrication of a superhydrophobic nylon textile based on the organic charge-transfer complex CuTCNAQ (TCNAQ=11,11,12,12-tetracyanoanthraquinodimethane) is reported. The nylon fabric, which is metallized with copper, undergoes a spontaneous chemical reaction with TCNAQ dissolved in acetonitrile to form nanorods of CuTCNAQ that are intertwined over the entire surface of the fabric. This creates the necessary micro- and nanoscale roughness that often allows the Cassie-Baxter state to be obtained with high robustness, thereby achieving a superhydrophobic/superoleophilic surface without the need for a fluorinated surface. The material is characterized with SEM, FTIR spectroscopy, and X-ray photoelectron spectroscopy, and investigated for its ability to separate oil and water in two modes, namely through filtration and as an absorbent material. It is found that the fabric can separate dichloromethane, olive oil, and crude oil from water, and reduce the water content of the oil during the separation process. The fabric is reusable, highly durable, and tolerant to conditions such as seawater, hydrochloric acid, and extensive time periods on the shelf. Given that CuTCNAQ is a copper-based semiconductor, there may also be the possibility of other uses in areas such as photocatalysis and antibacterial applications.

Manika Mahajan

Papers

Reusable surface confined semi-conducting metal-TCNQ and metal-TCNQF4 catalysts for electron transfer reactions

Electrochemical detection of dopamine and cytochrome c at a nanostructured gold electrode

Electrochemical formation of porous copper 7,7,8,8-tetracyanoquinodimethane and copper 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane honeycomb surfaces with superhydrophobic properties

Electrochemical detection of dopamine and cytochrome c at a nanostructured gold electrode

Superhydrophobic Fabrics for Oil/Water Separation Based on the Metal–Organic Charge‐Transfer Complex CuTCNAQ