Development and Evaluation of Copper Electrodes, Modified with Bimetallic Nanoparticles, to be Used as Sensors of Cysteine-Rich Peptides Synthesized by Tobacco Cells Exposed to Cytotoxic Levels of Cadmium

Recent Advances in Electrochemical Sensors for Sulfur-Containing Antioxidants

Sulfur-containing antioxidants are an important part of the antioxidant defense systems in living organisms under the frame of a thiol-disulfide equilibrium. Among them, l-cysteine, l-homocysteine, l-methionine, glutathione, and α-lipoic acid are the most typical representatives. Their actions in living systems are briefly discussed. Being electroactive, sulfur-containing antioxidants are interesting analytes to be determined using various types of electrochemical sensors. Attention is paid to the chemically modified electrodes with various nanostructured coverages. The analytical capabilities of electrochemical sensors for sulfur-containing antioxidant quantification are summarized and discussed. The data are summarized and presented on the basis of the electrode surface modifier applied, i.e., carbon nanomaterials, metal and metal oxide nanoparticles (NPs) and nanostructures, organic mediators, polymeric coverage, and mixed modifiers. The combination of various types of nanomaterials provides a wider linear dynamic range, lower limits of detection, and higher selectivity in comparison to bare electrodes and sensors based on the one type of surface modifier. The perspective of the combination of chromatography with electrochemical detection providing the possibility for simultaneous determination of sulfur-containing antioxidants in a complex matrix has also been discussed.

Simultaneous quantification of Cd(II) and Pb(II) in surface marine sediments using Ag-Hg and Ag-Bi nanoalloys glassy carbon modified electrodes

The evaluation of glassy carbon (GC) electrodes modified with a Nafion (Nf) film and doped with nanoalloys (Nys) deposits of Ag-Hg and Ag-Bi and their application to determination of Cd (II) and Pb(II) in marine sediments, is described. Deposited Ag-Hg and AgBi Nys have a size of approximately ~80 nm dispersed and embedded inside the booths of the Nf net, while other of them remained on Nf net surface. For the AgBiNysNf-GC electrode, a detection limit (DL), 3 s criterion, slightly higher than for the AgHgNysNf-GC modified electrode was obtained. Accuracy of measurements was asserted by comparison with quantification of Cd and Pb in three sets of marine sediments samples previously analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The values of the standard deviation and the coefficients of variation are very low, and also comparable between the different determinations.