Cholesterol plays a vital role in a human body. It is known as one of the most important sterols, because it forms cell walls and participates in signal transduction. Moreover, cholesterol was recognized as biomarker of cardiovascular diseases and of some metabolic disorders. As a result, cholesterol blood levels should be controlled in a variety of diseases such as ischemic heart disease, cerebrovascular ischemia, stroke, hypertension, type II diabetes, and many others. Hence, the accurate cholesterol quantification plays an important role in diagnosis and treatment of these diseases. Modern voltammetric and amperometric methods are increasingly used for cholesterol monitoring. Consequently, the problem of electrode fabrication for cholesterol detection has high importance for clinical tests. Novel electrode materials initiated the fast growth of electrochemical biosensors. Biomaterials are still the most frequently used modifiers for cholesterol sensors due to their high selectivity. However, biomaterials have low stability complicating their practical applications. This fact is crucial for analytical parameters such as limit of detection (LOD) and sensitivity. Therefore, nanomaterials are used to eliminate disadvantages of biomaterials and to improve sensors performance by increasing the electrode surface, conductivity and sensitivity. This review is focused on the use of non-enzymatic electrodes for cholesterol quantification and on different approaches to their fabrication. Firstly, the necessity and role of modifier is discussed. Afterwards, the advantages and disadvantages of currently used modifiers are critically compared together with all aspects and approaches to sensors fabrication. Finally, the prospects of non-enzymatic electrodes application for cholesterol sensors engineering are summarised.

• Klíčová slova
• Cholesterol, Clinical analysis, Electrochemistry, Modified electrodes, Nanomaterials,
• MeSH
• biosenzitivní techniky * MeSH
• cholesterol MeSH
• diabetes mellitus 2. typu * MeSH
• elektrochemické techniky MeSH
• elektrody MeSH
• lidé MeSH
• limita detekce MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• cholesterol MeSH

The inhibition effect of the selected heavy metals (Ag+, Cd2+, Cu2+, and Hg2+) on glucose oxidase (GOx) enzyme from Aspergillus niger (EC 1.1.3.4.) was studied using a new amperometric biosensor with an electrochemical transducer based on a glassy carbon electrode (GCE) covered with a thin layer of multi-wall carbon nanotubes (MWCNTs) incorporated with ruthenium(IV) oxide as a redox mediator. Direct adsorption of multi-wall carbon nanotubes (MWCNTs) and subsequent covering with Nafion® layer was used for immobilization of GOx. The analytical figures of merit of the developed glucose (Glc) biosensor are sufficient for determination of Glc in body fluids in clinical analysis. From all tested heavy metals, mercury(II) has the highest inhibition effect. However, it is necessary to remember that cadmium and silver ions also significantly inhibit the catalytic activity of GOx. Therefore, the development of GOx biosensors for selective indirect determination of each heavy metal still represents a challenge in the field of bioelectroanalysis. It can be concluded that amperometric biosensors, differing in the utilized enzyme, could find their application in the toxicity studies of various poisons.

• Klíčová slova
• amperometric biosensor, glucose oxidase, heavy metals, non-competitive inhibition,
• MeSH
• Aspergillus niger enzymologie   MeSH
• biosenzitivní techniky * MeSH
• elektrochemické techniky přístrojové vybavení   metody   MeSH
• elektrody MeSH
• glukosa analýza   MeSH
• glukosaoxidasa antagonisté a inhibitory   metabolismus   MeSH
• inhibitory enzymů farmakologie   toxicita   MeSH
• kalibrace MeSH
• limita detekce MeSH
• nanotrubičky uhlíkové MeSH
• peroxid vodíku analýza   MeSH
• sloučeniny ruthenia chemie   MeSH
• těžké kovy farmakologie   toxicita   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• glukosa MeSH
• glukosaoxidasa MeSH
• inhibitory enzymů MeSH
• nanotrubičky uhlíkové MeSH
• peroxid vodíku MeSH
• ruthenium tetraoxide MeSH Prohlížeč
• sloučeniny ruthenia MeSH
• těžké kovy MeSH

A porous layer of copper was formed on the surface of screen-printed carbon electrodes via the colloidal crystal templating technique. An aqueous suspension of monodisperse polystyrene spheres of 500 nm particle diameter was drop-casted on the carbon tracks printed on the substrate made of alumina ceramic. After evaporation, the electrode was carefully dipped in copper plating solution for a certain time to achieve a sufficient penetration of solution within the polystyrene spheres. The metal was then electrodeposited galvanostatically over the self-assembled colloidal crystal. Finally, the polystyrene template was dissolved in toluene to expose the porous structure of copper deposit. The morphology of porous structures was investigated using scanning electron microscopy. Electroanalytical properties of porous copper film electrodes were evaluated in amperometric detection of selected saccharides, namely glucose, fructose, sucrose, and galactose. Using hydrodynamic amperometry in stirred alkaline solution, a current response at +0.6 V vs. Ag/AgCl was recorded after addition of the selected saccharide. These saccharides could be quantified in two linear ranges (0.2-1.0 μmol L-1 and 4.0-100 μmol L-1) with detection limits of 0.1 μmol L-1 glucose, 0.03 μmol L-1 fructose, and 0.05 μmol L-1 sucrose or galactose. In addition, analytical performance of porous copper electrodes was ascertained and compared to that of copper film screen-printed carbon electrodes, prepared ex-situ by the galvanostatic deposition of metal in the plating solution. After calculating the current densities with respect to the geometric area of working electrodes, the porous electrodes exhibited much higher sensitivity to changes in concentration of analytes, presumably due to the larger surface of the porous copper deposit. In the future, they could be incorporated in detectors of flow injection systems due to their long-term mechanical stability.

• Klíčová slova
• amperometric detection, colloidal crystal templating, non-enzymatic sensors, porous copper electrodes, sensing of saccharides,
• MeSH
• elektrody MeSH
• fruktosa MeSH
• galaktosa MeSH
• glukosa MeSH
• měď * chemie   MeSH
• polystyreny MeSH
• sacharosa MeSH
• uhlík * chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fruktosa MeSH
• galaktosa MeSH
• glukosa MeSH
• měď * MeSH
• polystyreny MeSH
• sacharosa MeSH
• uhlík * MeSH

Electric spark discharge was employed as a green, fast and extremely facile method to modify disposable graphite screen-printed electrodes (SPEs) with copper, nickel and mixed copper/nickel nanoparticles (NPs) in order to be used as nonenzymatic glucose sensors. Direct SPEs-to-metal (copper, nickel or copper/nickel alloys with 25/75, 50/50 and 75/25wt% compositions) sparking at 1.2kV was conducted in the absence of any solutions under ambient conditions. Morphological characterization of the sparked surfaces was performed by scanning electron microscopy, while the chemical composition of the sparked NPs was evaluated with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The performance of the various sparked SPEs towards the electro oxidation of glucose in alkaline media and the critical role of hydroxyl ions were evaluated with cyclic voltammetry and kinetic studies. Results indicated a mixed charge transfer- and hyroxyl ion transport-limited process. Best performing sensors fabricated by Cu/Ni 50/50wt% alloy showed linear response over the concentration range 2-400μM glucose and they were successfully applied to the amperometric determination of glucose in blood. The detection limit (S/N 3) and the relative standard deviation of the method were 0.6µM and <6% (n=5, 2µM glucose), respectively. Newly devised sparked Cu/Ni graphite SPEs enable glucose sensing with distinct advantages over existing glucose chemical sensors in terms of cost, fabrication simplicity, disposability, and adaptation of green methods in sensor's development.

• Klíčová slova
• Green method, Mixed copper nickel nanoparticles, Non enzymatic glucose sensor, Screen-printed electrodes, Sparked electrodes,
• MeSH
• biosenzitivní techniky metody   MeSH
• elektrochemické techniky metody   MeSH
• elektrody * MeSH
• glukosa analýza   MeSH
• grafit chemie   MeSH
• lidé MeSH
• limita detekce MeSH
• měď chemie   MeSH
• nikl chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• glukosa MeSH
• grafit MeSH
• měď MeSH
• nickel copper alloy MeSH Prohlížeč
• nikl MeSH

We report a novel approach for the synthesis of silver nanoparticles (NPs) stabilized on polymer-wrapped carbon nanotubes (Ag@polymer/CNTs) for the non-enzymatic glucose sensing and antibacterial activity applications. Poly(styrene-alt-maleic anhydride) (PSM) was functionalized with amino furan to obtain furan-modified poly(styrene-alt-maleic anhydride) (PSMF), which was later grafted onto the surface of CNTs by Diels-Alder "click" reaction to afford a polymer/CNTs hybrid material. The photo-deposition technique was applied to immobilized small-sized (∼10 nm) AgNPs on the surface of the polymer/CNTs hybrid material using visible light irradiation. The resulting material, Ag@polymer/CNTs, showed promising electrocatalytic activity for the non-enzymatic glucose sensing and antibacterial activity in vitro assays toward Escherichia coli, Staphylococcus aureus, and Bacillus cereus bacteria strains. Covalent-bonded polymer layer-bearing carboxylic pendent groups to the CNTs might be playing a pivot role in not only stabilizing AgNPs but also facile electron-transfer reaction, thus demonstrating better activity.

• Publikační typ
• časopisecké články MeSH

We designed and synthesized nucleosides bearing aminophenyl- or aminonaphthyl-3-methoxychromone fluorophores attached at position 5 of cytosine or thymine and converted them to nucleoside triphosphates. The fluorophores showed solvatochromic fluorescence with strong fluorescence at 433-457 nm in non-polar solvents and very weak fluorescence at 567 nm in alcohols. The nucleosides and nucleotides also showed only negligible fluorescence in alcohols or water. The triphosphates were substrates for DNA polymerase in the enzymatic synthesis of modified DNA probes that showed only very weak fluorescence in aqueous buffer but a significant light-up and blue shift were observed when they interacted with proteins (histone H3.1 or p53 for double-stranded DNA probes or single-strand binding protein for single-stranded oligonucleotide probes). Hence, nucleotides have good potential in the construction of DNA sensors for studying protein-DNA interactions. The modified dNTPs were also transported into cells using a cyclodextrin-based transporter but they were not incorporated into the genomic DNA.

• MeSH
• chromony chemie   MeSH
• DNA sondy chemie   MeSH
• DNA chemie   MeSH
• enzymy chemie   MeSH
• fluorescence MeSH
• fluorescenční barviva chemie   MeSH
• nukleotidy chemie   MeSH
• proteiny chemie   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chromony MeSH
• DNA sondy MeSH
• DNA MeSH
• enzymy MeSH
• fluorescenční barviva MeSH
• nukleotidy MeSH
• proteiny MeSH

Flubendazole, methyl ester of [5-(4-fluorobenzoyl)-1H-benzimidazol-2-yl]carbamic acid, belongs to the group of benzimidazole anthelmintics, which are widely used in veterinary and human medicine. The phase I flubendazole biotransformation includes a hydrolysis of the carbamoyl methyl moiety accompanied by a decarboxylation (hydrolysed flubendazole) and a carbonyl reduction of flubendazole (reduced flubendazole). Flubendazole is a prochiral drug, hence a racemic mixture is formed during non-stereoselective reductions at the carbonyl group. Two bioanalytical HPLC methods were developed and validated for the determination of flubendazole and its metabolites in pig and pheasant hepatic microsomal and cytosolic fractions. Analytes were extracted from biomatrices into tert-butylmethyl ether. The first, achiral method employed a 250 mm x 4 mm column with octylsilyl silica gel (5 microm) and an isocratic mobile phase acetonitrile-0.025 M KH(2)PO(4) buffer pH 3 (28:72, v/v). Albendazole was used as an internal standard. The whole analysis lasted 27 min at a flow rate of 1 ml/min. The second, chiral HPLC method, was performed on a Chiralcel OD-R 250 mm x 4.6 mm column with a mobile phase acetonitrile-1 M NaClO(4) (4:6, v/v). This method enabled the separation of both reduced flubendazole enantiomers. The enantiomer excess was evaluated. The column effluent was monitored using a photodiode-array detector (scan or single wavelength at lambda=246 nm). Each of the analytes under study had characteristic UV spectrum, in addition, their chemical structures were confirmed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) experiments. Stereospecificity in the enzymatic carbonyl reduction of flubendazole was observed. While synthetic racemic mixture of reduced flubendazole was separated to equimolar amounts of both enantiomers, practically only one enantiomer was detected in the extracts from all incubates.

• MeSH
• anthelmintika analýza   MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací metody   MeSH
• kalibrace MeSH
• mebendazol analogy a deriváty   analýza   MeSH
• prasata MeSH
• ptáci MeSH
• spektrofotometrie ultrafialová metody   MeSH
• stereoizomerie MeSH
• tandemová hmotnostní spektrometrie metody   MeSH
• vysokoúčinná kapalinová chromatografie metody   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• validační studie MeSH
• Názvy látek
• anthelmintika MeSH
• flubendazole MeSH Prohlížeč
• mebendazol MeSH

Hydrogen peroxide (H2O2) is known to be generated in Photosystem II (PSII) via enzymatic and non-enzymatic pathways. Detection of H2O2 by different spectroscopic techniques has been explored, however its sensitive detection has always been a challenge in photosynthetic research. During the recent past, fluorescence probes such as Amplex Red (AR) has been used but is known to either lack specificity or limitation with respect to the minimum detection limit of H2O2. We have employed an electrochemical biosensor for real time monitoring of H2O2 generation at the level of sub-cellular organelles. The electrochemical biosensor comprises of counter electrode and working electrodes. The counter electrode is a platinum plate, while the working electrode is a mediator based catalytic amperometric biosensor device developed by the coating of a carbon electrode with osmium-horseradish peroxidase which acts as H2O2 detection sensor. In the current study, generation and kinetic behavior of H2O2 in PSII membranes have been studied under light illumination. Electrochemical detection of H2O2 using the catalytic amperometric biosensor device is claimed to serve as a promising technique for detection of H2O2 in photosynthetic cells and subcellular structures including PSII or thylakoid membranes. It can also provide a precise information on qualitative determination of H2O2 and thus can be widely used in photosynthetic research.

• Klíčová slova
• EPR-spin trapping, amperometric biosensor, hydrogen peroxide, photosystem II, reactive oxygen species, superoxide anion radical,
• Publikační typ
• časopisecké články MeSH