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Transport of divalent cations across the gel supported phospholipid membranes
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
This contribution deals with elucidation of principles of transporting processes of heavy metals (mainly lead, cadmium) across the biological membranes. The real membranes were for purposes of described experiments, replaced by model membranes, which were composed of phospholipid bilayers. Two different phorpholipids (1,2-dipalmitoyl-sn-glycero-3-phosphocholine and the mixture of phospholipids obtained from soybeans (under commercial name Asolectin)) were used as the building elements for the formation of these membranes on the surface of the constructed gel electrode. The registered transporting processes have been characterized using voltammetry, and electrochemical impendance spectrometry (EIS). The impact of some parameters on these systems and processes was investigated.
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Monolayers at electrodes as basis for models of natural membranes
Josypčuk, Bohdan ; Mareček, Vladimír
Properties of thiol (HS(CH2)10COOH) monolayers were investigated at stationary electrodes based on silver, copper, bismuth and cadmium solid amalgams covered by a mercury meniscus or by a mercury film. For comparison, parallel experiments were performed at a classical hanging mercury drop electrode. Dependences of monolayer parameters on time of electrochemical deposition of thiol and on scan rate were performed. Statistical evaluation of all obtained results has confirmed that solid amalgam electrodes are a convenient tool for research of thiol layers.
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Electrochemical properties of thiol monolayers at surfaces of different electrodes
Josypčuk, Bohdan ; Mareček, Vladimír
Solid amalgam electrodes covered by a mercury meniscus or by mercury film (m-AgSAE, MF-AgSAE, m-CuSAE, m-BiAgSAE and m-CdSAE) are convenient for obtaining thiol films which are bound to different metals. By choosing an appropriate metal for the amalgam preparation, a thiol monolayer can be created which is stable in the given potential range. After a short accumulation time (1-2 min), the area of the reduction peak (charge) practically does not change it the monolayer is created from 1 nM thiol solution. Statistical results based on many times repeated formation and desorption of thiol monolayers (RSD = 2-3 %) attest that the stationary SAEs are convenient tools for study of electrochemical properties of thiol films.
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Studium transportu iontů přes modelové fosfolipidové membrány
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
Synthetically prepared model phospholipid bilayers (PLBs) in the form of black membranes, vesicles or supported membranes, with incorporated ionophores or real ion channels (i.e., artificially synthesized or gained from real living cells, e.g. protoplasts) are promising for study and simulations of transporting processes across the real cell membranes and the membranes surrounding sub-cellular structures. The electrochemical methods were found to be very suitable and sensitive enough for characterization of such processes.
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Cd and Pb Speciation in Thlaspi caerulescens Presl Rhizosphere
Jakl, M. ; Jaklová Dytrtová, J. ; Šestáková, Ivana ; Tlustoš, P.
In this study the influence of Thlaspi caerulescens Presl rhizosphere on Cd and Pb complex formation and their total amount in soil solution of contaminated fluvisol from Litavka river alluvium was investigated. The soil solution was sampled from roots surrounding and from bulk behind rhizobag. The content of free Cd and Pb ions was measured by the differential pulse anodic stripping voltammetry in unchanged pH and in pH 2 in rhizosphere and bulk soil. The bimetallic Cd-Pb-oxalic acid complexes were detected in unchanged pH only.
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Preparation and Properties of Mercury Films on Solid Amalgam Surface
Josypčuk, Bohdan
There have been suggested a simple electrolyzer and a reliable procedure for preparation of mercury films with precisely defined thickness on a conducting surface. A small volume of electrolyte which can be used more times and a paste amalgam which cannot spill substantially decrease a risk of environment contamination. Measurements were parallelly performed on a liquid mercury free silver solid amalgam electrode (AgSAE), on a mercury meniscus modified AgSAE and on HMDE for comparing their properties with those of the mercury film electrodes (MF-AgSAE). A current response of the film electrodes is the biggest. The peak width, which determines the method resolution, is smallest on the film electrodes. Range of working potentials on MF-AgSAE is comparable with one on HMDE in different supporting electrolytes.
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