engleski

Controlling Cell Adhesion by Mercury Electrode

Electrical charge on any biological surface plays a crucial role in its interaction with other molecules or surfaces. In literature there are no data on the surface charge densities of planktonic algal cells although their interfacial properties appear to have a central role in aggregation phenomena in marine environments. The general method for analysis of the surface charge and potential of nonconductive microparticles is microelectrophoresis, where mobility measurements are transformed into zeta potentials using known mathematical relations. Here, we set out to explore the possibility to measure cell surface charge density directly, using a novel approach based on single particle adhesion at charged mercury electrode in aqueous electrolyte solution. We present the amperometric response of single cell adhesion in a real time, from the initial attachment to a finite state of spread cell. The technique is based on measurement of double-layer charge displacement at the mercury drop electrode. The flow of compensating current reflects the dynamics of adhesive contact formation and subsequent spreading of a cell. The spike-shaped signals have the peak current in microampere range, duration in milliseconds, and displaced charge in the nanocoulomb range. A surprising similarity to adhesion signals of droplets of liquid hydrocarbons (C12-C18) suggests that collective properties of cell exterior govern the dynamics of adhesion and rate of spreading, with the fluidity playing a major role. The characteristic potential range of adhesion can serve to study the interplay of complex surface forces involved in cell - electrical double-layer interactions. The only hypothesis used in interpreting the experimental results is the validity of the classical electrical double-layer model in terms of charge distribution at electrode/solution interface. References: 1. R. J. Hunter. Zeta Potential in Colloid Science, Principles and Applications, Academic Press, London 1981. 2. A. L. Alldredge and G. A. Jackson (Eds.). Aggregation in Marine Systems. Deep Sea Res. Part II. 1995, 42, 1-273. 3. V. Žutić, T. Pleše, J. Tomaić and T. Legović. 1984. Electrochemical characterization of fluid vesicles in natural waters. Mol. Cryst. Liq. Cryst. 113: 131-145. 4. N. Ivošević and V. Žutić. 1998. Spreading and detachment of organic droplets at an electrified interface. Langmuir. 14: 231-234. 5. V. Svetličić, N. Ivošević, S. Kovač and V. Žutić. 2000. Charge displacement by adhesion and spreading of a cell: Amperometric signals of living cells. Langmuir. 16: 8217-8220. 6. V. Svetličić, N. Ivošević, S. Kovač and V. Žutić. 2000. Charge displacement by adhesion and spreading of a cell. Bioelectrochem. 53: 79-86. 7. V. Svetličić, A. Hozić, Probing Cell Surface Charge by Scanning Electrode Potential, Electrophoresis. 2002. 23: 2080-2086.

cell adhesion; cell surface charge density

nije evidentirano