engleski

Probing Polymer Adsorption by Cell Adhesion

Adsorption of biopolymers is probed by cell adhesion at the mercury electrode/aqueous solution interface using electrochemical technique - chronoamperometry. The surface charge density of mercury electrode immersed in an aqueous electrolyte solution can be finely tuned by controlling the electrode potential. We have previously shown that the signal frequency of cell adhesion is dependant on biopolymer surface concentration.[1, 2] Dextrans are known for their specific adsorption (displacement of water molecules and ions) at mercury electrode/aqueous solution interface in a range of positive but also negative surface charges.[3] Adsorption of dextran molecules is fast and controlled by mass transport from the solution. Dextran sulfate with average molecular weight of 500 000 was chosen as negatively charged biopolymer. On the other hand, unicellular marine algae Dunaliella tertiolecta (cell diameter 6-9 &micro ; m) can be characterized through their adhesion at mercury electrode that results in well-defined electrical attachment signals at millisecond time scale.[4] For the given cell density frequency of cell adhesion decreases with the increase in surface coverage of dextran molecules. The extent of adsorption of dextran sulfate was probed at positively (σ = +3.8 &micro ; C cm^ -2) and negatively (σ = -6.5 &micro ; C cm^ -2) charged mercury electrode/0.1M NaCl solution interface. For dextran concentrations >50 mg L^ -1 cell adhesion was significantly suppressed only at positively charged mercury electrode. Our results clearly show the evidence of the electrostatic repulsion between dextran sulfate molecules and negatively charged mercury electrode. References [1] Žutić, V. ; Svetličić, V. ; Tomaić, J. Pure & Appl. Chem. 1990, 62, 2269. [2] Kovač, S. ; Svetličić, V. ; Žutić, V. Colloids Surf. A. 1999, 149, 481. [3] Malfoy, B. ; Reynaud, J.A. Anal. Biochem. 1988, 84, 1. [4] Svetličić, V. ; Ivošević, N. ; Kovač, S. ; Žutić, V. Langmuir. 2000, 16, 8217.

adsorption of biopolymers; cell adhesion; mercury electrode; dextran sulfate adsorption; electrode charge density

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