Tuning the surface properties of polypyrrole films for modulating bacterial adhesion

Tuning the physical-chemical properties of Polypyrrole (PPy) opens up potentially exciting new applications, especially in the area of bacterial adhesion. Polypyrrole is electrochemically synthesised under various conditions and the physical properties of the films and their effects on bacterial adhesion characterised. Five types of dopants, chloride (Cl), Perchlorate (ClO4), pToluene-sulfonate (ToS), Dodecylbenzene sulfonate (DBS) and Poly sodium styrene sulfonate (PSS), are used to fabricate PPy films at two different constant potentials (0.500 and 0.850 V) with and without Fe3+. Their thickness, roughness and wettability are measured. The adhesion tendency of Escherichia coli, as a model bacterium, to the four polymers is studied. E.coli shows greater adhesion tendency to the hydrophobic, rough surface of PPy-DBS and less adhesion tendency to the smooth and hydrophilic surface of PPy-PSS. The results facilitate the choice of appropriate electropolymerisation conditions to modulate bacterial adhesion.