Aušra Valiūnienė

Investigation of the electroreduction of silver sulfite complexes by means of electrochemical FFT impedance spectroscopy

The electroreduction kinetics of silver sulfite complexes was investigated by electrochemical fast Fourier transform (FFT) impedance spectroscopy (0.061-1500 Hz). The time dependences of the real and imaginary components of impedance were determined in a solution containing 0.05 M Ag (I) and 1M Na(2)SO(3). The mean duration of silver ad-atom diffusion on the surface to the nearest crystallization centre was calculated: during the first 210 s of contact with the electrolyte, these values increase from 0.66 up to 1.77 s; thereafter, this variation stabilizes and the mean duration of silver ad-atom diffusion reaches an almost constant value (1.56 s).

Formation of hybrid bilayers on silanized thin-film Ti electrode

Phospholipid bilayer membranes are essential elements of living organisms as they form boundaries between the intracellular cytoplasm and the extracellular environment, as well as organelles. In this work we report on our attempts to assemble artificial phospholipid bilayer model membranes on Ti surface. To provide hydrophobic cushion for phospholipids, the surface of a thin-film Ti electrode was initially functionalized with trichloro(octadecyl)silane (OTS). Increased hydrophobicity of the solid support allowed vesicle fusion and the formation of a hybrid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayer, as probed by the electrochemical impedance spectroscopy (EIS), contact angle measurements (CA) also by the Fourier transform-infrared (FT-IR) spectroscopy, spectroscopic ellipsometry (SE) and atomic force microscopy (AFM). Our study demonstrates the applicability of thin-film Ti electrodes for the formation of hybrid bilayer membranes. These membranes allow functional reconstitution of the pore-forming toxins and provide a bioanalytical platform for the detection of the activity of the cholesterol-dependent cytolysins.