Ján Labuda

Electrochemical nucleic acid-based biosensors: Concepts, terms, and methodology (IUPAC Technical Report)

An electrochemical nucleic acid (NA)-based biosensor is a biosensor that integrates a nucleic acid as the biological recognition element and an electrode as the electrochemical signal transducer. The present report provides concepts, terms, and methodology related to biorecognition elements, detection principles, type of interactions to be addressed, and construction and performance of electrochemical NA biosensors, including their critical evaluation, which should be valuable for a wide audience, from academic, biomedical, environmental, and food-testing, drug-developing, etc. laboratories to sensor producers.

Electroanalytical chemistry for the analysis of solids: Characterization and classification (IUPAC Technical Report)

Solid state electroanalytical chemistry (SSEAC) deals with studies of the processes, materials, and methods specifically aimed to obtain analytical information (quantitative elemental composition, phase composition, structure information, and reactivity) on solid materials by means of electrochemical methods. The electrochemical characterization of solids is not only crucial for electrochemical applications of materials (e.g., in batteries, fuel cells, corrosion protection, electrochemical machining, etc.) but it lends itself also for providing analytical information on the structure and chemical and mineralogical composition of solid materials of all kinds such as metals and alloys, various films, conducting polymers, and materials used in nanotechnology. The present report concerns the relationships between molecular electrochemistry (i.e., solution electrochemistry) and solid state electrochemistry as applied to analysis. Special attention is focused on a critical evaluation of the different types of analytical information that are accessible by SSEAC.

Voltammetric Detection of the DNA Interaction with Copper Complex Compounds and Damage to DNA

Binding reactions of copper(II) complexes of 1,10-phenanthroline (phen) and tetraaza macrocyclic ligand TAAB with calf thymus DNA have been investigated voltammetrically at bare and DNA modified glassy carbon electrodes. The values of binding constant, binding site size, ratio of binding constants for the reduced and oxidized copper complex forms as well as information on the electrostatic and intercalative binding modes were obtained by solution and surface-based methods. The Cu(phen)22+complex mediates the dsDNA cleavage to a higher degree than Cu(TAAB)2+as indicated by the redox marker Co(phen)33+and the anodic signal of the DNA base. A procedure for the damage to DNA detection using dsDNA/GCE biosensor is proposed.

Electrochemical determination of guanine and adenine by CdS microspheres modified electrode and evaluation of damage to DNA purine bases by UV radiation.

Sensitive electrochemical sensor based on a composite of novel pearl-like CdS microspheres and chitosan (CdS-CHIT/GCE) was constructed and characterized using cyclic voltammetry. Single-stranded (ssDNA) and double-stranded (dsDNA) deoxyribonuleic acid were electrochemically adsorbed onto CdS-CHIT/GCE and a significant difference in electrochemical impedance spectra of the ssDNA/CdS-CHIT/GCE and dsDNA/CdS-CHIT/GCE electrodes was found. Electrocatalytic properties of CdS allowed to use the CdS-CHIT/GCE successfully for the trace determination of simple guanine and adenine with nanomolar detection limits by differential pulse voltammetry (DPV). Moreover, damage to the DNA purine bases, guanine and adenine, liberated in previously hydrolyzed calf thymus dsDNA, caused by UV-B, UV-C, and visible light was evaluated. While only minor changes in anodic DPV response of guanine and adenine could be seen after 60 min exposition to UV-B and visible light, total degradation of DNA bases was observed after 20 min exposure to UV-C. A great potential of the CdS microspheres used as the interface at the nucleic acid based biosensors was demonstrated.

Damage to DNA indicated by an electrically heated DNA-modified carbon paste electrode

The behaviour of an electrically heated carbon paste electrode (CPE) with the surface modified by a calf thymus double stranded (ds) DNA adsorption layer was investigated in the medium of a copper(II) complex with 1,10-phenanthroline (phen) as the chemical nuclease. Damage to DNA is affected strongly by the electrode temperature within the range of 22–38°C as indicated by the square-wave voltammetric signals of the DNA redox marker Co(phen)33+ as well as the DNA guanine moiety. No significant effect of temperature on the binding constant was found at the titration of Cu(phen)22+ with dsDNA in solution. Thus, the formation of radical species and irreversible DNA damage are affected by DNA/CPE heating. The heated electrode can be applied advantageously to the real-time detection of traces of DNA-damaging agents.

Voltammetric Detection of Antioxidative Properties of Flavonoids Using Electrically Heated DNA Modified Carbon Paste Electrode

A simple electrochemical sensor consisting of electrically heated carbon paste electrode with the surface modified by dsDNA is used to characterize voltammetric behaviour and antioxidative activity of four selected flavonoids. Quercetin, rutin, catechin and epigallocatechin gallate accumulate within the DNA layer. A positive effect of the electrode temperature within the range of 20 to 38 °C on the detection of a deep DNA degradation by a copper(II)/H2O2/ascorbic acid cleavage mixture as well as an antioxidative effect of flavonoids was evaluated.

Detection of damage to DNA and antioxidative activity of yeast polysaccharides at the DNA-modified screen-printed electrode

A simple procedure for the voltammetric detection of the DNA damage and antioxidants protecting DNA from its damage using a disposable electrochemical DNA biosensor is reported. The carbon-based screen-printed electrode (SPE) modified by a surface layer of the calf thymus double stranded (ds) DNA was used as a working electrode in combination with a silver/silver chloride reference electrode and a separate platinum auxiliary electrode. The [Co(phen)(3)](3+) ion served as the dsDNA redox marker and the [Cu(phen)(2)](2+) and [Fe(EDTA)](-) complex compounds were used as the DNA cleavage agents under the reduction by a chemical reductant (ascorbic acid). Four yeast polysaccharides with different chemical structure were investigated as the antioxidants within the concentration range of 0.05-4 mg ml(-1) in the cleavage mixture. A remarkable antioxidative activity of polysaccharides in order mannan (Candida krusei)>extracellular glucomannan (Candida utilis)>mannan (Candida albicans)>glucomannan (C. utilis) was found which is in agreement with that refered to trolox (a structural derivative of alpha-tocopherol) and determined by photochemiluminescent method.

Determination of dissolved manganese in natural waters by differential pulse cathodic stripping voltammetry

A procedure based on differential pulse cathodic stripping voltammetry on the graphite electrode is described for the determination of dissolved manganese in natural waters buffered at pH about 6.5 with acetate solution. In order to avoid interference of iron(II) the addition of fluoride is used. The limit of detection is 3 μg/l for a deposition time of 6 min. Acidification and UV-irradiation are recommended for samples containing dissolved organic matter. Results of manganese determination in table mineral waters are reported and the possibility of manganese speciation is discussed.

Complex electrochemical and impedimetric evaluation of DNA damage by using DNA biosensor based on a carbon screen-printed electrode

DNA biosensor (DNA/SWCNT-COOH-CHIT/SPCE) composed of dsDNA adsorptive layer on a carboxylated single-walled carbon nanotubes–chitosan composite deposited at a commercial carbon based screen-printed electrode has been prepared and applied to a complex investigation of damage to DNA by the Fenton type cleavage agent (hydroxyl radicals formed in the mixture of Cu2+, H2O2 and ascorbic acid) and copper(II)–quercetin system in 0.1 M PBS pH 7.0 under aerobic conditions. The dsDNA damage detection is performed by using square-wave voltammetry (SWV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1 × 10−7 M thioridazine and 1 × 10−3 M K4[Fe(CN)6]/K3Fe(CN)6 in the 0.1 M phosphate buffer solution, pH 7.0. Initial enhancement of the intrinsic guanine and adenine moieties SWV response over that of original dsDNA one indicates opening of the helix structure in the first stage of damage. At the same time, decrease in the intercalated thioridazine response confirms damage of the helix structure in parallel to deep degradation of the DNA chain and its removal from the electrode surface as indicated by the CV and EIS measurements in the presence of the [Fe(CN)6]3−/4−redox indicator in solution.

Polymer interfaces used in electrochemical DNA-based biosensors

Nowadays DNA-based biosensors represent powerful tools for the study of DNA sequence, DNA chemical interactions and damage. Among them, biosensors with an electrochemical signal transducer play the most important role. The performance of a biosensor strongly depends on the method of a biorecognition element being attached to the electrode. This review refers to polymer materials being used to create a DNA-electrode interface. The main terminology is given in Introduction followed by a description of polymers and polymer-based nanocomposites and their electrochemical properties. A comprehensive table reports examples of the electrochemical detection of DNA immobilized on the polymer matrix. Finally, a short survey is given.