ion transfer voltammetry
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Cytotoxic properties of radiosensitizers are due to the fact that, in the metabolic pathway, these compounds undergo one-electron reduction to generate radical anions. In this study we focused our interest on the electrochemical transfer of the first electron on radiosensitizer Etanidazole (ETN) and, consequently, on the ETN radical-anion formation in the buffered aqueous media. ETN was electrochemically treated in the broad pH range at various scan rates. Three reduction peaks and one oxidation peak were found. At strong alkaline pH the four-electron reduction peak was separated into one-electron and three-electron reductions. Under these conditions the standard rate constant k(0) for the redox couple ETN-NO(2)+e(-) <--> ETN-NO(2)(*-) was calculated. Moreover, the value of a so called E(7)(1) potential that accounts for the energy necessary to transfer the first electron to an electroactive group at pH=7 in aqueous medium to form a radical anion was also determined. The obtained value of E(7)(1) indicates that lower energy compared to the other possible chemical radiosensitizers is necessary for the system to transfer the first electron to ETN. On the other hand, the necessity of the strong alkaline pH may decrease the ability of ETN to act as hypoxic radiosensitizer in the human body.
- MeSH
- anionty chemie MeSH
- elektrická vodivost MeSH
- elektrochemie MeSH
- etanidazol chemie MeSH
- hypoxie buňky MeSH
- kinetika MeSH
- koncentrace vodíkových iontů MeSH
- radiosenzibilizující látky chemie MeSH
- transport elektronů MeSH
- voda chemie MeSH
- volné radikály chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In this work, we have examined an electrochemical behavior of the ephedrine at the polarized liquid-liquid interface (water/1,2-dichloroethane). In this respect, we first designed and then 3D printed polyamide-based electrochemical cell that was used as the liquid-liquid interface support during electroanalytical measurements. The protonated ephedrine undergoes a reversible ion transfer reaction with the standard Galvani potential difference equal to +0.269 V. This value was used to calculate the water - 1,2-dichloroethane logP equal to -4.6. Ion transfer voltammetry was used to build the calibration curve and allowed for the ephedrine detection from concentration equal to 20 μM. By varying the pH of the aqueous phase from 2 up to 12 we were able to plot the ion partition diagram that was further analyzed and provided several pharmacochemical information. To further push this work towards practical utility, we have formulated the artificial urine and studied the interfacial behavior of all its components at the polarized liquid-liquid interface. Ephedrine detection from real spiked urine samples was also performed.
- MeSH
- 3D tisk * MeSH
- efedrin * chemie MeSH
- ethylendichloridy * MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A novel sensor based on a modification of glassy carbon electrode (GCE) with NH2-functionalized multi-walled carbon nano-tubes (NH2fMWCNTs) is reported and its applicability to the electrochemical sensing of Propafenone (PPF) demonstrated. The electrochemical catalytic activity was also utilized as a sensitive detection method for the investigation of the detailed redox mechanism of PFF using cyclic and and differential pulse voltammetry. The surface morphology of the sensor was investigated by SEM armed with EDX probe. Electrochemical impedance spectroscopy was employed as well to define the electron transfer capability of modified and bare electrodes. Key experimental and instrumental conditions related to electrochemical determination by cyclic, differential pulse, and square wave voltammetry, such as amount of modifier, pH, scan rate, accumulation time and potential were studied and optimized. The results have shown a significant enhancement of the peak current after modifying the electrode; the calibration curves of PPF offering good linearity from 0.1 to 10 μM, limit of quantification (LOQ) being 0.03 μM and limit of detection (LOD) 0.01 μM, both when using DPV technique. The proposed sensor was successfully applied to the determination of PFF in dosage form without any special purification, separation or pre-treatment steps. The results of analyses obtained with the proposed sensor were satisfactory and fully statistically relevant.
- MeSH
- antiarytmika MeSH
- elektrody MeSH
- farmaceutická technologie přístrojové vybavení metody MeSH
- impedanční spektroskopie MeSH
- kalibrace MeSH
- koncentrace vodíkových iontů MeSH
- kyslík chemie MeSH
- lékové formy * MeSH
- limita detekce MeSH
- mikroskopie elektronová rastrovací MeSH
- nanomedicína MeSH
- nanotrubičky uhlíkové chemie MeSH
- propafenon aplikace a dávkování MeSH
- uhlík chemie MeSH
- Publikační typ
- časopisecké články 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.
The translation of metallothioneins (MTs) is one of the defense strategies by which organisms protect themselves from metal-induced toxicity. MTs belong to a family of proteins comprising MT-1, MT-2, MT-3, and MT-4 classes, with multiple isoforms within each class. The main aim of this study was to determine the behavior of MT in dependence on various externally modelled environments, using electrochemistry. In our study, the mass distribution of MTs was characterized using MALDI-TOF. After that, adsorptive transfer stripping technique with differential pulse voltammetry was selected for optimization of electrochemical detection of MTs with regard to accumulation time and pH effects. Our results show that utilization of 0.5 M NaCl, pH 6.4, as the supporting electrolyte provides a highly complicated fingerprint, showing a number of non-resolved voltammograms. Hence, we further resolved the voltammograms exhibiting the broad and overlapping signals using curve fitting. The separated signals were assigned to the electrochemical responses of several MT complexes with zinc(II), cadmium(II), and copper(II), respectively. Our results show that electrochemistry could serve as a great tool for metalloproteomic applications to determine the ratio of metal ion bonds within the target protein structure, however, it provides highly complicated signals, which require further resolution using a proper statistical method, such as curve fitting.
- MeSH
- chlorid sodný chemie MeSH
- elektrochemie MeSH
- elektrolyty MeSH
- komplexní sloučeniny chemie metabolismus MeSH
- kovy chemie metabolismus MeSH
- metalothionein chemie metabolismus MeSH
- protein - isoformy MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články 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
- elektrochemické techniky * MeSH
- měď MeSH
- metalothionein MeSH
- prionová bílkovina MeSH
- Publikační typ
- časopisecké články MeSH
