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The electrochemical performance of gold electrode in sulfuric acid was studied with addition of different concentrations of dissolved fullerenol-d with C60(OH)24 chemical formula. Based on the cyclic voltammetry data, the conclusion of surface complexation of Au(III) with fullerenol was made. The scheme was suggested to describe the electrode process, based on catalysis of anodic Au dissolution by fullerenol molecules. The technique was suggested to detect fullerenol-d (C60(OH)24) in concentration range from 2.6·10–9 M to 2.0·10–7 M by means of cyclic voltammetry of gold in aqueous sulfuric acid solution. [ABSTRACT FROM AUTHOR]

The evaluation of histamine levels in saliva can be used as one of the diagnostic criteria for detecting many diseases. Therefore, a sensitive, simple, and low-cost method for determining histamine concentrations is needed for point-of-care diagnostics. In this work, the use of a glassy carbon disk electrode, bulk graphite composite electrode, and graphite screen-printed electrode modified with CuO nanoparticles and CuSO4 for histamine quantification by cyclic voltammetry was studied. The best results were obtained using the screen-printed sensor with the working electrode modified by a CuSO4 aqueous solution and covered with a Nafion-like polymer film. The developed sensor showed a 5 × 10–9 M detection limit with a broad linear range from 5 × 10–9 to 1 × 10–6 M of histamine in a phosphate buffer solution, providing sufficient reliability for saliva analysis after simple sample preparation. The analysis of real saliva samples revealed no significant interfering matrix effect. The total analysis time, including sample preparation, did not exceed 15 minutes. [ABSTRACT FROM AUTHOR]

A review of new results on the application of layer-by-layer (LbL) chemical assembly procedures to the production of thin-layer structures on the surfaces of various substrates in order to develop active elements (AEs) of chemoresistive gas sensors for the determination of inorganic and organic compounds in air and controlled gas atmospheres is presented. The LbL assembly procedures and their features, such as the possibility of synthesis under the conditions of soft chemistry, the precise setting of the thicknesses of applied layers, and the production of multilayers consisting of individual layers with predicted compositions, are considered. Charge transfer between analyte molecules in the layers and oxidation–reduction centers on the AE surface is briefly discussed, and conditions for the functioning of optimal AEs are formulated. The capabilities of the LbL assembly method to precisely control the thickness of each layer in a multilayer system on the electrode surface and thus directionally change the sensor response and select a layer responsible for the best practically important characteristics are emphasized. The role of catalysts in these processes is noted. The results of original publications on the application of LbL assembly procedures to the development of a wide range of AEs for sensors are presented, and the analytical characteristics of the sensors are compared. In conclusion, the prospects for using these procedures in the manufacture of new AEs with high sensitivity and selectivity and a short response time are considered. [ABSTRACT FROM AUTHOR]

We studied methods of the in situ synthesis of gold nanostructures on the electrode surface and of the directed electrochemical synthesis of nanodendrites to create biosensors based on horseradish peroxidase. The effect of nanostructuring of the transducer surface and its subsequent modification on the electroanalytical characteristics of sensors for the determination of hydrogen peroxide was studied. The use of these methods can significantly improve the performance characteristics of the biosensors, such as the sensitivity coefficient, limit of detection, and stability in the range of micromolar and submicromolar concentrations of hydrogen peroxide. The electrodes modified by the in situ synthesis of nanostructures with subsequent treatment with Meerwein's reagent, as well as ultramicroelectrodes prepared by directional electrochemical synthesis, show low limits of detection for hydrogen peroxide, 0.2 and 0.08 µM, and high sensitivity coefficients, 0.71 and 0.84 A M–1 cm–2, respectively. [ABSTRACT FROM AUTHOR]

Electrochemical methods of analysis are usually characterized by high sensitivity, ease of automation, and a wide range of analytes and test samples. The development of electrochemical methods of analysis at the present stage is mostly determined by the creation of new nanostructured electrode materials with electrocatalytic properties. The use of such materials ensures an increase in the sensitivity and selectivity of the determination of a number of analytes. Another conventional way to decreasing the limit of detection for electrochemically active substances is the development of new measurement methods for improving the signal-to-noise ratio in nonequilibrium electrochemical methods of analysis. This article is devoted to the consideration of some new electrode materials and methods of electrochemical measurements. [ABSTRACT FROM AUTHOR]

In this review, peculiarities of the Gold nanoparticles synthesis on the solid support are discussed. This article focuses on the recent developments in various methods for immobilization of gold nanoparticles on solid surface. Particular attention is given to the synthesis of nanoparticles by Layer-by-Layer method and on the advances in the Successive Ionic Layer Deposition (SILD) methodology. The present review summarizes SILD work in this field to date and contributes a new experimental date for application SILD method in field of electrochemical sensor design. As an example the conditions of synthesis of gold nanoparticles on the surface of indium-tin oxide (ITO) electrode are described in this article. It has been shown that the size of synthesized nanostructures can be controlled by formation of intermediated layer. It was found that preliminary SILD synthesis of AuxSnO2·nH2O nanolayer on the ITO surface leads to significant changes in the morphology of subsequently synthesized gold nanoparticles. In this case the same number of cycles provides the formation of significantly smaller (10-20 nm) nanoparticles and greater surface coverage density. Electrodes obtained by this technique demonstrate lower oxidation and reduction potentials of gold as well as higher currents of these reactions. [ABSTRACT FROM AUTHOR]