Antibacterial properties of metal and PDMS surfaces under weak electric fields

Abstract

The adhesion of several species of bacteria on two parallel rectangular electrodes under weak electric fields was studied. The electrodes were based on native metal or PDMS coated Cu. After 2 h of contact at a voltage of 0.2 to 1 V without any current, the Zn cathode showed a bacterial repellent effect with a difference in bacterial adhesion of about 1.5 to 2 log CFU/cm2 on the anode. Al electrodes were inactive due to their passivation by the alumina layer. At 1 V, both Zn and Al exhibited more than 80% mortality of suspended bacteria. The Cu electrodes showed a very high bactericidal effect even at 0 V, and the bacterial adhesion on its surface was too weak to see a difference between the two electrodes. A similar study carried out on PDMS surfaces, covering Cu electrodes, revealed that a difference of 1 log CFU/cm2 of bacterial adhesion between the cathode and anode surfaces can be obtained by applying a voltage ranging from 10 to 30 V. This cathodic repellent effect was specific to staphylococcus species, suggesting that in the presence of a PDMS coating, the electrostatic forces on the surface are too low to be the main factor governing bacterial adhesion.