A completely new voltammetric method has been developed for quantitative determination of food additive Taurine (Tau) in energy drinks. This electroanalytical method is based on voltammetric oxidation of o-phthalaldehyde-ethanthiol derivative of Tau at glassy carbon electrode in 95% methanol containing 0.1 mol L-1 lithium perchlorate. Working conditions necessary for quantitative Tau derivatization reaction and electrochemical detection using square wave voltammetry were optimized. Linear range from 1.0 × 10-5 to 1.0 × 10-4 mol L-1 characterized by coefficient of determination 0.9998, limits of quantification 6.8 × 10-6 mol L-1 and detection 2.1 × 10-6 mol L-1 were obtained at pulse amplitude 50 mV and frequency 80 Hz. Analytical method of calibration curve was used for evaluation of Tau content in several commercially available energy drinks. The procedure was validated using standard reference high performance liquid chromatography (HPLC) method. Both methods showed nearly identical Tau content, around 0.35% (w/w). Besides its reliability to the Tau determination, that is totally comparable to reference method used, present voltammetric approach is more advantageous on the economic and simplicity basis. Finally, developed voltammetric method could find employment in food quality control.
- Klíčová slova
- Derivatization, Food analysis, Glassy carbon electrode, Square wave voltammetry, Taurine, o-phthalaldehyde,
- MeSH
- elektrochemické techniky * MeSH
- energetické nápoje analýza MeSH
- kalibrace MeSH
- kvalita jídla MeSH
- o-ftalaldehyd chemie MeSH
- sulfhydrylové sloučeniny chemie MeSH
- taurin analýza MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- ethanethiol MeSH Prohlížeč
- o-ftalaldehyd MeSH
- sulfhydrylové sloučeniny MeSH
- taurin MeSH
Cancer is a widespread disease characterized by high mortality. To improve the survival rate or facilitate effective therapy, accurate and reliable diagnosis at an early stage is needed. For this reason, there is a continuous push to develop sensitive methods which can be used in cancer diagnosis. Current diagnosis relies on the quantification of cancer biomarkers defined as molecules that are measurable in body fluids or tissues and indicate a change in physiological processes with subsequent pathological manifestations. This contribution reviews recent developments in the area of electrochemical immunosensors applicable for the detection of cancer biomarkers that occur in a wide concentration range including extremely low levels, which are typical for the early stage of the disease. A summary of various antibody labels used for biomarker analysis and combined with electrochemical detection is presented. The potential of multiple biomarker analysis, with its indisputable clinical impact for accurate diagnosis, is also highlighted.
- Klíčová slova
- Cancer, biomarker, diagnosis, electrochemical detection, immunosensors, multiplex assay.,
- MeSH
- biosenzitivní techniky * MeSH
- časná detekce nádoru přístrojové vybavení metody MeSH
- elektrochemické techniky přístrojové vybavení metody MeSH
- lidé MeSH
- nádorové biomarkery analýza MeSH
- nádory diagnóza imunologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- nádorové biomarkery MeSH
The features and applications of silver amalgam electrodes in electroanalysis of pharmaceuticals and vitamins are summarized in this review. The state-of-the-art in the preparation and construction of solid silver amalgam electrodes for prolonged and userfriendly use is presented. Although not as widely spread as other electrode materials, silver amalgam possesses a unique and viable combination of favorable electrochemical properties, which are close to ideal mercury electrodes, non-toxic character, high durability and mechanical stability, if properly prepared. Its capability of conducting the redox processes at highly negative potentials is essential for the analysis of large number of bioactive organic compounds. The review features also overview information for each application in drug or vitamin analysis divided to the sections according to the construction variants of silver amalgam electrodes.
- Klíčová slova
- Silver amalgam electrodes, clinical analysis, drugs, food analysis, pharmaceuticals, vitamins.,
- MeSH
- elektrody * MeSH
- léčivé přípravky analýza MeSH
- stříbro chemie MeSH
- vitaminy analýza MeSH
- zubní amalgam chemie MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- léčivé přípravky MeSH
- stříbro MeSH
- vitaminy MeSH
- zubní amalgam MeSH
Nowadays in biosensing, development of analytical techniques is focused on improvement for monitoring biologically active species in living organisms, especially in real-time analysis. This article provides an overview of applications of electrochemical tyrosinase biosensors in the analysis of medicinally significant substances, also known as biomarkers. At the beginning, special attention is paid to characterisation of the tyrosinase enzyme, explanation of reaction mechanisms of tyrosinase with various types of electrochemical transducers and techniques needed for stable immobilization of this biocatalyst on the transducer surface used. In this case, amperometric transducers represent the most frequently used type of electrochemical sensing because they usually provide sensitive current response to the presence of analyte in the sample. Many scientific works suggest that these very selective bioanalytical devices could find application in the clinical diagnosis of various serious diseases because they represent the effective analytical tools for diagnosis of neurodegenerative disorders, detection of microbial pathogens responsible for foodborne illness and diagnosis of cytopathology, especially melanoma cancer. Additionally, various kinds of electrochemical tyrosinase biosensors are presented which were developed to determine the catalytic activity of other enzymes significant for human metabolism, medicaments and their metabolic products, several hormones, amino acids and proteins. Despite all of their advantages, it is necessary to state that tyrosinase biosensors are still not used in the routine laboratory practice due to their relatively short service life which is not longer than one month unfortunately. Never-ending development of catalytic polymers imitating the tyrosinase active site could be one of ways to solve this serious drawback.
- Klíčová slova
- Biosensor, biological markers, diagnosis, electroanalysis, medicine, tyrosinase.,
- MeSH
- aminokyseliny analýza MeSH
- Bacteria izolace a purifikace MeSH
- biologické markery analýza MeSH
- biosenzitivní techniky * MeSH
- elektrochemické techniky přístrojové vybavení MeSH
- elektrody MeSH
- fenoly analýza MeSH
- hormony analýza MeSH
- katalýza MeSH
- léčivé přípravky analýza MeSH
- lidé MeSH
- nádorové biomarkery analýza MeSH
- nádory diagnóza MeSH
- neurotransmiterové látky analýza MeSH
- tyrosinasa antagonisté a inhibitory metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- aminokyseliny MeSH
- biologické markery MeSH
- fenoly MeSH
- hormony MeSH
- léčivé přípravky MeSH
- nádorové biomarkery MeSH
- neurotransmiterové látky MeSH
- tyrosinasa MeSH
Two multiwalled carbon nanotubes-based composites modified with bismuth and bismuth-oxychloride particles were synthesized and attached to the glassy carbon electrode substrate. The resultant configurations, Bi/MWCNT-GCE and BiOCl/MWNT-GCE, were then characterized with respect to their physicochemical properties and electroanalytical performance in combination with square-wave anodic stripping voltammetry (SWASV). Further, some key experimental conditions and instrumental parameters were optimized; namely: the supporting electrolyte composition, accumulation potential and time, together with the parameters of the SWV-ramp. The respective method with both electrode configurations has then been examined for the trace level determination of Pb(2+) and Cd(2+) ions and the results compared to those obtained with classical bismuth-film modified GCE. The different intensities of analytical signals obtained at the three electrodes for Pb(2+) and Cd(2+) vs. the saturated calomel reference electrode had indicated that the nature of the modifiers and the choice of the supporting electrolyte influenced significantly the corresponding stripping signals. The most promising procedure involved the BiOCl/MWCNT-GCE and the acetate buffer (pH 4.0) offering limits of determination of 4.0 μg L(-1) Cd(2+) and 1.9 μg L(-1) Pb(2+) when accumulating for 120 s at a potential of -1.20 V vs. ref. The BiOCl/MWCNT electrode was tested for the determination of target ions in the pore water of a selected sediment sample and the results agreed well with those obtained by graphite furnace atomic absorption spectrometry.
A new procedure was elaborated to determine mercury(II) using an anodic stripping square-wave voltammetry at the antimony film carbon paste electrode (SbF-CPE). In highly acidic medium of 1M hydrochloric acid, voltammetric measurements can be realized in a wide potential window. Presence of cadmium(II) allows to separate peaks of Hg(II) and Sb(III) and apparently catalyses reoxidation of electrolytically accumulated mercury, thus allowing its determination at ppb levels. Calibration dependence was linear up to 100 ppb Hg with a detection limit of 1.3 ppb. Applicability of the method was tested on the real river water sample.
- Publikační typ
- časopisecké články MeSH
The described glucose biosensor is based on a screen-printed carbon electrode (SPCE) modified by rhodium dioxide, which functions as a mediator. The electrode is further modified by the enzyme glucose dehydrogenase, which is immobilized on the electrode's surface through electropolymerization with m-phenylenediamine. The enzyme biosensor was optimized and tested in model glucose samples. The biosensor showed a linear range of 500-5000 mg L(-1) of glucose with a detection limit of 210 mg L(-1) (established as 3σ) and response time of 39 s. When compared with similar glucose biosensors based on glucose oxidase, the main advantage is that neither ascorbic and uric acids nor paracetamol interfere measurements with this biosensor at selected potentials.
- Publikační typ
- časopisecké články MeSH
In this article, some new approaches to characterize the carbon paste mixtures and the respective carbon paste electrodes (CPEs) are presented, discussed, and critically evaluated. Particular attention has been paid to the changes of the ohmic resistance, relative to the dependence on composition of the CPE, the materials used, the time, and the position of storage. Four types of carbon pastes were examined, and for the interpretation of experimental data, a new simple model of "close-packing of spheres" has been applied. This model resembles the percolation theory for solid matter. In our case, however, it is possible to explain not only the "bent" or "broken" shape of the dependence of the electrode resistance upon the binder:carbon ratio and the corresponding electrochemical current response, but also differences caused by various material used and three various effects observed during the electrode aging. Furthermore, the report presents the significance of practical utilization of the recently introduced carbon paste index (denoted as chi(CPE)), which is a qualitative hitherto unused factor based on the evaluation of cyclic voltammograms for standard redox systems (e.g., [Fe(CN)(6)](3-/4-)) and specifying the electrochemical properties of a CPE. Some problems connected with homogeneity and stability of carbon pastes, their handling, storage, or eventual aging effects are also discussed.
- MeSH
- elektrická impedance MeSH
- elektrochemie * MeSH
- elektrody * MeSH
- uhlík chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- uhlík MeSH
UV-vis reflection spectroelectrochemistry has proven to be a very useful multiresponse technique to evaluate the quality of bismuth films obtained by electrochemical deposition on glassy carbon electrodes (GCEs). Bismuth films have recently emerged as a promising and environmental friendly alternative to mercury electrodes for stripping analysis. Spectroelectrochemical measurements, carried out in a flow cell, allowed us to follow in situ the electrodeposition and stripping of bismuth and cadmium. Electrochemical and spectroscopic responses individually have led to successfully quantify the amount of cadmium in test solutions.
- MeSH
- bismut chemie MeSH
- časové faktory MeSH
- elektrody MeSH
- kadmium chemie MeSH
- pokovování galvanické * MeSH
- spektrofotometrie metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bismut MeSH
- kadmium MeSH
Electrochemical enzyme-linked techniques for sequence-specific DNA sensingare presented. These techniques are based on attachment of streptavidin-alkalinephosphatase conjugate to biotin tags tethered to DNA immobilized at the surface ofdisposable screen-printed carbon electrodes (SPCE), followed by production andelectrochemical determination of an electroactive indicator, 1-naphthol. Via hybridizationof SPCE surface-confined target DNAs with end-biotinylated probes, highly specificdiscrimination between complementary and non-complementary nucleotide sequences wasachieved. The enzyme-linked DNA hybridization assay has been successfully applied inanalysis of PCR-amplified real genomic DNA sequences, as well as in monitoring of planttissue-specific gene expression. In addition, we present an alternative approach involvingsequence-specific incorporation of biotin-labeled nucleotides into DNA by primerextension. Introduction of multiple biotin tags per probe primer resulted in considerableenhancement of the signal intensity and improvement of the specificity of detection.
- Klíčová slova
- DNA hybridization, PCR, electrochemical detection, enzyme-linked assay, gene expression, primer extension,
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
