engleski

Stvaranje Co(II)-Phen-PC mješanog kompleksa na modelu živine elektrode i Langmuirove kade

Cell membrane represents boundary between the cell and its environment. It consists of phospholipid bilayer in which are embedded functional molecules as membrane proteins, carbohydrates, protein channels, glycolipids which enable various membrane functions from which selective permeability for ions and organic molecules is important for our work. Cell physiology is strongly dependent on the interaction of hydrophobic cell membranes with hydrophilic inorganic ions. The key lipid-type defining membrane bilayers are phospholipids. Among which phosphatidylglycerol, phosphatidylethanolamin and phosphatidylcholine (PC) which is the subject of our investigation, are the most important, especially in algae species. Detailed investigation of Co (II) binding with natural lipid phosphatidylcholine (PC) in aqueous solution was carried out by voltammetric measurements at the mercury drop electrode, complemented by monolayer studies in a Langmuir trough used as model for hydrophobic cell membranes. Penetration of cobalt ions into the PC layer was facilitated by the formation of Co(II)-1, 10- Phenanthroline (Phen) complex in the subphase, followed by the hydrophobic mixed ligand Co(II)-1, 10-Phen-PC complex formation at the mercury drop interface. Investigation od cobalt complexation with phosphatidylcholine was performed by cathodic stripping voltammetry in 0.55 mol dm-3 NaCl solution at static mercury electrode. Complex Co- Phen was registred within pH range 4 to 10 at -1.0 V. Stoichiometry, stability and complex kinetics were determined. Co(II)-Phen-PC complex reduces irrreversibly indicating a two-electron transfer chemical reaction at -1.5 V vs Ag/AgCl including reactant adsorption with complex dissociation after reduction takes place. Investigation of Co(II) lipid mixed ligand complex adsorbed at the mercury electrode hydrophobic surface is a significant contribution to the understanding of the processes occurring on the cell membranes hydrophobic surface. Consequently, the surface concentration (γ) of the adsorbed [Co(II)PhenPC] complex at the mercury drop electrode surface was calculated to be 1.45 x10-10 mol cm-2. Information on the mechanism of Co (II) - lipid complex formation is a significant contribution to the understanding of complex processes at natural cell membranes.

cobalt ; complexation ; voltammetry ; phosphatidylcholine ; Langmuir method

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