The stabilization of the reduction state of proteins and peptides is very important for the monitoring of protein-protein, protein-DNA and protein-xenobiotic interactions. The reductive state of protein or peptide is characterized by the reactive sulfhydryl group. Glutathione in the reduced (GSH) and oxidized (GSSG) forms was studied by cyclic voltammetry. Tris(2-carboxyethyl)phosphine (TCEP) as the disulfide bond reductant and/or hydrogen peroxide as the sulfhydryl group oxidant were used. Cyclic voltammetry measurements, following the redox state of glutathione, were performed on a hanging mercury drop electrode (HMDE) in borate buffer (pH 9.2). It was shown that in aqueous solutions TCEP was able to reduce disulfide groups smoothly and quantitatively. The TCEP response at -0.25 V vs. Ag/AgCl/3 M KCl did not disturb the signals of the thiol/disulfide redox couple. The origin of cathodic and anodic signals of GSH (at -0.44 and -0.37 V) and GSSG (at -0.69 and -0.40 V) glutathione forms is discussed. It was shown that the application of TCEP to the conservation of sulfhydryl groups in peptides and proteins can be useful instrument for the study of peptides and proteins redox behavior.

• MeSH
• biokompatibilní materiály chemie   MeSH
• disulfidy analýza   chemie   MeSH
• elektrochemie metody   MeSH
• fosfiny chemie   MeSH
• glutathion analýza   chemie   MeSH
• glutathiondisulfid analýza   chemie   MeSH
• oxidace-redukce MeSH
• testování materiálů metody   MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• biokompatibilní materiály MeSH
• disulfidy MeSH
• fosfiny MeSH
• glutathion MeSH
• glutathiondisulfid MeSH
• tris(2-carboxyethyl)phosphine MeSH Prohlížeč

Electrochemical characteristics of native and denatured calf thymus DNA have been studied by voltammetry on a silver electrode (AgE). Experimental results obtained from linear sweep or cyclic voltammetry (LSV or CV) have been employed in elimination voltammetry. The elimination voltammetry with linear scan (EVLS), using the linear combination of the total currents measured at different scan rates, enables one or two selected particular currents to be eliminated. The best results have been obtained by using a function eliminating the kinetic and charging currents (I(k),I(c)), and conserving the diffusion current (I(d)). This function makes it possible to increase significantly voltammetric signals of native and denatured DNAs, and to reveal processes not detectable by conventional electrochemical methods. The influence of electrochemical pretreatment of silver electrode surfaces and of starting and switching potentials on DNA voltammetric signals have been discussed. Silver electrodes coupled with elimination voltammetry represent promising tools for developing new nucleic acids biosensors.

• Publikační typ
• časopisecké články MeSH

Machine learning is increasingly integrated into chemistry research by guiding experimental procedures, correlating structure and function, interpreting large experimental datasets, to distill scientific insights that might be challenging with traditional methods. Such applications, however, largely focus on gaining insights via big data and/or big computation, while neglecting the valuable chemical prior knowledge dwelling in chemists' minds. In this paper, we introduce an Electrochemistry-Informed Neural Network (ECINN) by explicitly embedding electrochemistry priors including the Butler-Volmer (BV), Nernst and diffusion equations on the backbone of neural networks for multi-task discovery of electrochemistry parameters. We applied the ECINN to voltammetry experiments of F e 2 + / F e 3 + ${{\rm F}{{\rm e}}^{2+}/{\rm F}{{\rm e}}^{3+}}$ and R u N H 3 6 2 + / R u N H 3 6 3 + ${{\rm R}{\rm u}{\left({\rm N}{{\rm H}}_{3}\right)}_{6}^{2+{\rm \ }}/{\rm R}{\rm u}{\left({\rm N}{{\rm H}}_{3}\right)}_{6}^{3+{\rm \ }}}$ redox couples to discover electrode kinetics and mass transport parameters. Notably, ECINN seamlessly integrated mass transport with BV to analyze the entire voltammogram to infer transfer coefficients directly, so offering a new approach to Tafel analysis by outdating various mass transport correction methods. In addition, ECINN can help discover the nature of electron transfer and is shown to refute incorrect physics if imposed. This work encourages chemists to embed their domain knowledge into machine learning models to start a new paradigm of chemistry-informed machine learning for better accountability, interpretability, and generalization.

• Klíčová slova
• Cyclic Voltammetr, Electrochemistry, Multi-Task Discovery, Physics-Informed Neural Networks, Tafel Analysis,
• Publikační typ
• časopisecké články MeSH

We have previously shown that a DNA-modified electrode can be prepared by immersing the hanging mercury drop electrode (HMDE) in a small volume (about 5-10 microliters) of a DNA solution. Within a short period of time the DNA is irreversibly adsorbed at the electrode, resisting subsequent washing. The electrode is then transferred into a voltammetric cell filled with the background electrolyte (that does not contain any nucleic acid) in which the voltammetric measurements are performed. This procedure is called adsorptive transfer stripping voltammetry (AdTSV). In this paper AdTS cyclic voltammetry (CV) peaks of DNA were measured to report on the stability of the attachment of plasmid DNA molecules to the electrode surface. It was shown that the attachment of plasmid DNA to the electrode was, like the case of calf thymus DNA, sufficiently stable. If the DNA-modified electrode was immersed in a protein solution no significant exchange between the DNA and protein was observed. Submicrogram amounts of DNA were sufficient to attain full coverage of the electrode at relatively short waiting times and the detection limit of the denatured DNA was below 2 ng. The intensity of the AdTS CV signals of supercoiled, linearized and thermally denatured linear DNAs differed from one another. It was shown that alkaline denaturation of linear and supercoiled DNA in solution can be studied using AdTS CV technique. It was further shown that at neutral pH the linearized plasmid undergoes denaturation due to a prolonged contact with the electrode charged to potentials around -1.2 V. Such a surface denaturation has been previously observed with calf thymus DNA and synthetic double-stranded polynucleotides. Our results show that in contrast to linear DNA, supercoiled DNA was not significantly denatured as a result of its prolonged contact with the electrode charged to various potentials in the range between -0.1 to -1.5 V.

• MeSH
• adsorpce MeSH
• denaturace nukleových kyselin * MeSH
• DNA chemie   MeSH
• elektroforéza v agarovém gelu MeSH
• mikroelektrody MeSH
• osmolární koncentrace MeSH
• plazmidy MeSH
• poškození DNA MeSH
• rtuť chemie   MeSH
• skot MeSH
• superhelikální DNA chemie   MeSH
• thymus chemie   MeSH
• zvířata MeSH
• Check Tag
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA MeSH
• rtuť MeSH
• superhelikální DNA MeSH

BACKGROUND: Spectroelectrochemistry (SEC) is a valuable analytical tool providing insights to reaction mechanisms and the structure of species involved in charge transfer reactions. Most of commercial SEC setups are based on platinum working electrodes where the adsorption of species involved in reactions often complicates their analysis. RESULTS: In this work, we employ an array of pencil graphite rods as an optically transparent working electrode in a custom-made air-tight thin-layer cell suitable for the SEC analysis performed here in acetonitrile as a representative non-aqueous solvent. The functionality of the device was demonstrated by UV-Vis SEC sensing of charge transfer reactions of ruthenium acetylacetonate, ferrocene and ethylviologen dibromide redox probes performed employing the cyclic voltammetry. The SEC response obtained for all three probes confirmed no adsorption and the absence of oxygen in the cell. Furthermore, we have developed and utilized finite element method numerical simulations considering charge transfer reactions coupled with the diffusional mass transport to model the cyclic voltammetric response and the reaction conversion in the thin-layer SEC cell. SIGNIFICANCE: Our work paves the way for easy-to-assemble customized air-tight adsorption-free SEC devices with the manufacturing costs well below those of commercially available platforms. Developed computational approaches have the predictive power for optimizing reaction conditions and the geometry of the SEC cell.

• Klíčová slova
• 3D printing, Charge transfer, Cyclic voltammetry, Numerical simulations, Pencil graphite electrode, Spectroelectrochemistry,
• Publikační typ
• časopisecké články MeSH

Voltammetric behavior of 2-aminobiphenyl, 3-aminobiphenyl, and 4-aminobiphenyl at a boron-doped nanocrystalline diamond film electrode was investigated using cyclic voltammetry and differential pulse voltammetry. Optimum conditions have been found for the determination of those genotoxic substances by differential pulse voltammetry at the above given electrode in the concentration range of 2 x 10(-7) to 1 x 10(-5) mol/L.

• MeSH
• aminobifenylové sloučeniny analýza   MeSH
• bor chemie   MeSH
• diamant chemie   MeSH
• elektrochemie MeSH
• elektrody MeSH
• kalibrace MeSH
• koncentrace vodíkových iontů MeSH
• kovové nanočástice chemie   MeSH
• mutageny analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aminobifenylové sloučeniny MeSH
• bor MeSH
• diamant MeSH
• mutageny MeSH

The interaction of genotoxic environmental pollutant 2-nitrofluorene (2-NF) with double-stranded DNA has been studied using a hanging mercury drop electrode (HMDE) as an electrochemical sensor. Two types of DNA damage were investigated and electrochemically detected using cyclic voltammetry and differential pulse voltammetry: (i) DNA damage caused by the direct interaction with 2-NF and (ii) DNA damage caused by short-lived radicals generated by the electrochemical reduction of 2-NF. For the study of the direct interaction, the HMDE was modified by DNA and the interaction of DNA with 2-NF was studied after their mutual interaction right at the HMDE surface, or DNA was preincubated with 2-NF in solution and, subsequently, the interaction was studied voltammetrically. Using both detection techniques, the formation of DNA-2-NF complex was observed and the mutual interaction was interpreted as an intercalation between DNA base pairs. On the basis of obtained results, we suppose that expected formation of 8-oxoguanosine leads to guanosine-cytidine base pair interruption and DNA double-strand break formation. The binding constants (K) of the DNA-2-NF complex formed in solution and on the HMDE surface (DNA/HMDE) were determined from the changes in the voltammetric peaks of the studied analyte.

• Klíčová slova
• 2-Nitrofluorene, DNA biosensor, DNA damage, Electrochemical detection, Hanging mercury drop electrode,
• MeSH
• DNA * metabolismus   MeSH
• elektrody MeSH
• fluoreny MeSH
• poškození DNA MeSH
• rtuť * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 2-nitrofluorene MeSH Prohlížeč
• DNA * MeSH
• fluoreny MeSH
• rtuť * MeSH

The potentials of electrochemical processes in ideal aqueous media are related to the potential of a normal hydrogen electrode (NHE). However, in non-ideal media, the potentials of a metallocene redox couple are used as a reference. Such measurements with free metallocene in solution are complicated by adsorption and mass transport phenomena and solvation effects. Herein, a platinum electrode with an anchored ferrocene moiety (Pt,Fc) was used for cyclic voltammetric measurements of the potential of ferrocene/ferrocenium (Fc/Fc+) redox transformation in not only non-aqueous but, for the first time, aqueous solutions as well. This enabled us to eliminate the aforementioned problems associated with the application of free metallocene molecules in solution and, thus, to relate the midpoint potential (Epm) of the Fc/Fc+ redox couple to a NHE. After elimination of the liquid junction potential in an aqueous 0.1 M KCl solution at 25 °C, the average intraday Epm value obtained with freshly prepared Pt,Fc electrodes was found to be 0.312 ± 0.008 V versus the secondary Ag|AgCl electrode. The Pt,Fc electrode can be applied for the standardization of electrochemical measurements and investigation of solvation phenomena at interfaces in non-ideal media.

• Publikační typ
• časopisecké články MeSH

Voltammetric determination of Tartrazine (Tz) and Brilliant Blue FCF (BB) in their mixture using novel type of carbon black-polyethylene composite electrode (CBPCE) with renewable surface modified by carbon ink (CI) was developed. Electrochemical properties of the tested dyes were investigated in 0.1 mol L-1 Britton-Robinson (BR) buffer by cyclic voltammetry (CV) and linear scan voltammetry (LSV). Simultaneous determination of the dyes is based on the application of supporting electrolytes with different pH: 2.0 for Tz and 10.0 for BB. Under the optimum experimental conditions, linear concentration dependences in the concentration ranges from 0.037 to 1.38 μmol L-1 for Tz and from 0.025 to 2.52 μmol L-1 for BB were obtained by LSV in the first-order derivative mode. Limits of detection (LODs) for Tz and BB were 0.019 and 0.011 μmol L-1, respectively. The modified electrode showed good stability and reproducibility and was successfully applied for the determination of the mixture Tz and BB in a candy and soft drink products.

• Klíčová slova
• Brilliant blue FCF, Linear scan voltammetry, Modified electrode, Tartrazine,
• Publikační typ
• časopisecké články MeSH

Osmium tetroxide complexes with nitrogen ligands (L) are probes of DNA structure and electroactive labels of DNA. Here adducts of single-stranded (ss) DNA with osmium tetroxide 2,2'-bipyridine (DNA-Os,bipy) were studied by cyclic voltammetry for the first time. It was found that at neutral pH DNA-Os,bipy produces three redox couples in the potential range between 0 and -1 V (peaks I-III) and a cathodic peak at about -1.3 V (peak IV). The latter peak decreased with increasing scan rate, and peaks arising from the forward and reverse scans exhibited the same direction, suggesting catalytic nature of the electrode process. We concluded that this peak corresponds to the known differential pulse voltammetric (polarographic) peak of DNA-Os,L adducts for which catalytic hydrogen evolution is responsible. In contrast, currents of cathodic peaks II and III increased almost linearly with increasing scan rate, suggesting involvement of adsorption in the electrode processes. Adsorptive stripping square-wave voltammetry was used to analyze the DNA-Os,bipy at low concentrations. It was shown that at neutral pH, peak III can offer sensitivity in the ppb range, which is only little lower than that reached by catalytic peak IV. The latter peak is, however, superior in sensitivity at acid pH values.

• MeSH
• 2,2'-dipyridyl analogy a deriváty   analýza   chemie   MeSH
• barvení a značení metody   MeSH
• biokompatibilní potahované materiály chemie   MeSH
• biosenzitivní techniky metody   MeSH
• DNA sondy chemie   MeSH
• DNA analýza   chemie   MeSH
• elektrochemie metody   MeSH
• elektrody * MeSH
• hybridizace nukleových kyselin metody   MeSH
• organokovové sloučeniny analýza   chemie   MeSH
• rtuť chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• 2,2'-dipyridyl MeSH
• biokompatibilní potahované materiály MeSH
• calf thymus DNA MeSH Prohlížeč
• DNA sondy MeSH
• DNA MeSH
• organokovové sloučeniny MeSH
• osmium tetroxide-2,2'-bipyridine MeSH Prohlížeč
• rtuť MeSH