engleski

Molecular adsorption vs. cell adhesion at the dropping mercury electrode

Studies of biofilm formation are essential for understanding and control of processes in natural aquatic systems, for industrial applications and in medicine and stomatology where the most extensive studies have been performed (1). Our investigations of adhesion of droplets (2) and microorganisms (3,4) at the expanding mercury electrode/seawater interface offer a new approach to studies of initial monolayer formation in complex mixtures of dissolved and dispersed surfactants. Dynamics of film formation is measured as a time which is necessary to reach a full coverage at the fast dropping mercury electrode in the scale 10-2000 ms by adsorption of dissolved biomolecules and/or adhesion of cells suspended in an aqueous electrolyte solution. Phytoplankton organism Dunaliella tertiolecta (8-10mm) has been chosen as a model organism. It has fluid cell wall and the attachment of individual cells at the mercury electrode yields well-defined electrical signals in millisecond scale, and amplitudes 0.6-2.2 mA. Measurable concentration range 103-105 cells/ml was limited by frequency of attachment signals (0.05-10 signals per 2 seconds). Dextran, albumine and nonionic detergent Triton T-X-100 were chosen as soluble molecules in concentration range 0.05-500 mg/l. Measurement of attachment signals of Dunaliella tertiolecta cells is proposed to probe mechanisms of transport and adsorption process in the molecular film formation. References: 1) W.G.Characklis, K.C.Marshal, Biofilms, Wiley, 1989. 2) V.Žutić, S.Kovač, J.Tomaić, V.Svetličić, J.Electroanal.Chem., 349 (1993) 173. 3) S.Kovač, M.Sc.Thesis, Faculty of Zagreb, 1993. 4) V.Svetličić, N.Ivošević, V.Žutić, Croat.Chem.Acta, in press.

film formation dynamics; cell adhesion; biomolecules adsorption

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