This work reveals the growing potential of novel electrochemical methods that are applicable for polysaccharides. It was shown for the first time that the molecules of hyaluronic acid (HA) exhibit electrochemical response using phase-sensitive alternating current (AC) voltammetry in phase-out mode. Adsorption and desorption processes of HA fragments at a charged interface of mercury electrode were observed in buffered HA solutions. Electrostatic and hydrophobic manners of interactions were distinguished for native hyaluronan fragments in a wide electric potential range. The AC voltammetry response depended on the temperature, concentration, and length of HA chains. Results of this work open possibilities for further structural characterization of widely used HA fragments and understanding manners of interactions with charged hydrophobic surfaces that could be useful in the future for understanding HA interactions at biological levels.

• Publication type
• Journal Article MeSH

We report a new configuration for enhancing the performance of scanning electrochemical microscopy (SECM) via heating of the substrate electrode. A flattened Pt microwire was employed as the substrate electrode. The substrate was heated by an alternating current (AC), resulting in an increased mass transfer between the wire surface and the bulk solution. The electrochemical response of the Pt wire during heating was investigated by means of cyclic voltammetry (CV). The open circuit potential (OCP) of the wire was recorded over time, while varied heating currents were applied to investigate the time needed for establishing steady-state conditions. Diffusion layer studies were carried out by performing probe approach curves (PACs) for various measuring modes of SECM. Finally, imaging studies of a heated substrate electrode surface, applying feedback, substrate generation/tip collection (SG/TC), and the competition mode of SECM, were performed and compared with room temperature results.

• MeSH
• Electrochemistry instrumentation   methods   MeSH
• Electrodes * MeSH
• Microscopy, Electrochemical, Scanning * MeSH
• Hot Temperature * MeSH
• Publication type
• Journal Article MeSH

Previously, it has been shown that proteins and some polysaccharides (PSs) catalyse hydrogen evolution, producing electrochemical signals on mercury electrodes. The catalytic hydrogen evolution reaction (CHER) of the above-mentioned biomacromolecules was studied by voltammetric and chronopotentiometric stripping (CPS) methods. To obtain more information about electrode processes involving CHER, here we used protein such as BSA, and chitosan as a PS; in addition, we investigated dextran as a control PS not involved in CHER. We studied biomacromolecules by phase-sensitive alternating current (AC) voltammetry. Using phase-in AC voltammetry, for CHER-involved biomacromolecules we observed a CHER peak at highly negative potentials, similar to that observed with other voltammetric and CPS methods. On the other hand, by means of the adsorption/desorption processes studied in phase-out AC voltammetry, we uncovered a sharp and narrow decrease of capacitive current in the potential range of the CHER peak, denominated as the tensammetric minimum. This minimum was closely related to the CHER peak, as demonstrated by similar dependences on specific conditions affecting the CHER peak such as buffer capacity and pH. A tensammetric minimum was not observed for dextran. Our results suggest specific organization of biopolymer layers at negative potentials observed only in biomacromolecules involved in CHER.

• MeSH
• Adsorption MeSH
• Chitosan chemistry   MeSH
• Dextrans chemistry   MeSH
• Electrodes MeSH
• Helix, Snails chemistry   MeSH
• Catalysis MeSH
• Conductometry instrumentation   MeSH
• Concanavalin A chemistry   MeSH
• Mercury MeSH
• Serum Albumin, Bovine chemistry   MeSH
• Cattle MeSH
• Hydrogen chemistry   MeSH
• Animals MeSH
• Check Tag
• Cattle MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Herein, the direct electroanalytical determination of antidepressant imipramine using a boron-doped diamond electrode is presented. Cyclic and linear sweep voltammetric measurements revealed one distinct, irreversible and diffusion-controlled oxidation peak at +0.75 V (vs. Ag/AgCl) and oval-shaped peaks at +1.0 V and +1.5 V in the presence of Britton-Robinson buffer at pH 9. Using differential pulse voltammetry, the peak current of IMIP was found to be linear function of the concentration from 1.5 to 19.4 μM with the obtained detection limit of 0.5 μM and good repeatability (relative standard deviation of 5.4 % for n = 20 at 1.5 μM IMIP). The practical usefulness of the developed method was successfully manifested on the analysis of pharmaceutical tablets with significant recoveries (99.0–100.4 %). Finally, boron-doped diamond electrode could be considered as an alternative to widely used chemically modified electrodes in antidepressant sensing and may be applied as a sensitive electrochemical sensor in routine pharmaceutical analysis.

• MeSH
• Antidepressive Agents analysis   MeSH
• Chemistry Techniques, Analytical * methods   MeSH
• Electrochemical Techniques methods   MeSH
• Imipramine * analysis   MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH

The prion protein (PrPC) can be structurally shifted to its PrPScisoform causing a wide range of neurodegenerative diseases, which are currently incurable. There is an evidence that metallothioneins (MTs), and especially MT-3, are associated with neurodegenerative diseases. PrPCand MTs play pivotal roles in maintaining metal homeostasis; therefore, it is conceivable that each of them has its own significance in prion diseases. In this paper, we study the nature of interactions between PrPC, MT, and copper ions, Cu(II), using the method of differential pulse voltammetry (DPV) coupled with adsorptive transfer stripping technique (AdTS). Electrochemical properties of PrP itself and its interactions with both the Cu(II) ions and MTs have been found. Based on the results obtained, we hypothesised the formation of the complex in molar ratio 2:1 (PrPC:MT). Surface plasmon resonance imaging (SPRi) was used as a control reference assay to further confirm results obtained by the electrochemical approach, such as the specific interactions between PrPCand MT-3.

• MeSH
• Electrochemical Techniques * MeSH
• Copper MeSH
• Metallothionein MeSH
• Prion Proteins MeSH
• Publication type
• Journal Article MeSH

Electrochemical methods, particularly when applied in connection with mercury-containing electrodes, are excellent tools for studying nucleic acids structure and monitoring structural transitions. We studied the effect of the length of the central (dG) n stretch (varying from 0 to 15 guanine residues) in 15-mer oligodeoxynucleotides (ODN, G0 to G15) on their electrochemical and interfacial behavior at mercury and carbon electrodes. The intensity of guanine oxidation signal at the carbon electrode (peak G(ox)) was observed to increase continuously with number of guanines between 0 and 15, with only a slight positive shift for ODNs with seven or more guanines in the central segment. Very different effects were observed when the peak G(HMDE) was measured at the mercury electrode. Intensity of the latter signal increased with number of guanines up to G5, and decreased sharply with further elongation of the (dG) n stretch. CD spectroscopy and electrophoresis experiments revealed formation of parallel intermolecular quadruplex structures for ODNs containing five or more G residues. Further measurements made by cyclic and alternating-current voltammetry revealed a strong influence of the ODN structure on their behavior at electrically charged surfaces.

• MeSH
• DNA chemistry   MeSH
• Electrochemical Techniques methods   MeSH
• G-Quadruplexes * MeSH
• Nucleic Acid Conformation MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Genotoxic nitrated polycyclic aromatic hydrocarbons (NPAHs) are formed during incomplete combustion processes by reaction of polycyclic aromatic hydrocarbons (PAHs) with atmospheric nitrogen oxides. 1-Nitropyrene, 2-nitrofluorene, and 3-nitrofluoranthene as the dominating substances are used as markers of NPAHs formation by these processes. In the presented study, voltammetric properties and quantification of these compounds and of 5-nitroquinoline (as a representative of environmentally important genotoxic heterocyclic compounds) have been investigated using a mercury meniscus modified silver solid amalgam electrode (m-AgSAE), which represent a nontoxic alternative to traditional mercury electrodes. Linear calibration curves over three orders of magnitude and limits of determination mostly in the 10(-7) mol L(-1) concentration range were obtained using direct current and differential pulse voltammetry. Further, satisfactory HPLC separation of studied analytes in fifteen minutes was achieved using 0.01 mol L(-1) phosphate buffer, pH 7.0 : methanol (15 : 85, v/v) mobile phase, and C(18) reversed stationary phase. Limits of detection of around 1 · 10(-5) mol L(-1) were achieved using amperometric detection at m-AgSAE in wall-jet arrangement for all studied analytes. Practical applicability of this technique was demonstrated on the determination of 1-nitropyrene, 2-nitrofluorene, 3-nitrofluoranthene, and 5-nitroquinoline in drinking water after their preliminary separation and preconcentration using solid phase extraction with the limits of detection around 1 · 10(-6) mol L(-1).

• MeSH
• Nitrates chemistry   MeSH
• Electrochemical Techniques instrumentation   MeSH
• Electrodes MeSH
• Polycyclic Compounds chemistry   MeSH
• Silver MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Currently, the influenza virus infects millions of individuals every year. Since the influenza virus represents one of the greatest threats, it is necessary to develop a diagnostic technique that can quickly, inexpensively, and accurately detect the virus to effectively treat and control seasonal and pandemic strains. This study presents an alternative to current detection methods. The flow-injection analysis-based biosensor, which can rapidly and economically analyze a wide panel of influenza virus strains by using paramagnetic particles modified with glycan, can selectively bind to specific viral A/H5N1/Vietnam/1203/2004 protein-labeled quantum dots. Optimized detection of cadmium sulfide quantum dots (CdS QDs)-protein complexes connected to paramagnetic microbeads was performed using differential pulse voltammetry on the surface of a hanging mercury drop electrode (HMDE) and/or glassy carbon electrode (GCE). Detection limit (3 S/N) estimations based on cadmium(II) ions quantification were 0.1 μg/mL or 10 μg/mL viral protein at HMDE or GCE, respectively. Viral protein detection was directly determined using differential pulse voltammetry Brdicka reaction. The limit detection (3 S/N) of viral protein was estimated as 0.1 μg/mL. Streptavidin-modified paramagnetic particles were mixed with biotinylated selective glycan to modify their surfaces. Under optimized conditions (250 μg/mL of glycan, 30-min long interaction with viral protein, 25°C and 400 rpm), the viral protein labeled with quantum dots was selectively isolated and its cadmium(II) content was determined. Cadmium was present in detectable amounts of 10 ng per mg of protein. Using this method, submicrogram concentrations of viral proteins can be identified.

• MeSH
• Biosensing Techniques instrumentation   methods   MeSH
• Biotin chemistry   metabolism   MeSH
• Electrochemical Techniques instrumentation   methods   MeSH
• Electrodes MeSH
• Hemagglutinin Glycoproteins, Influenza Virus analysis   metabolism   MeSH
• Cadmium analysis   MeSH
• Quantum Dots MeSH
• Limit of Detection MeSH
• Linear Models MeSH
• Magnetite Nanoparticles chemistry   MeSH
• Flow Injection Analysis instrumentation   methods   MeSH
• Mercury chemistry   MeSH
• Cadmium Compounds chemistry   MeSH
• Streptavidin chemistry   metabolism   MeSH
• Sulfides chemistry   MeSH
• Carbon chemistry   MeSH
• Influenza A Virus, H5N1 Subtype chemistry   isolation & purification   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

• MeSH
• Biophysics MeSH
• Medical Laboratory Science MeSH

• Conspectus
• Biochemie. Molekulární biologie. Biofyzika
• Učební osnovy. Vyučovací předměty. Učebnice
• NML Fields
• fyzika, biofyzika
• technika lékařská, zdravotnický materiál a protetika
• NML Publication type
• učebnice vysokých škol