In situ continuous electrochemical quantification of bacterial adhesion to electrically polarized metallic surfaces under shear.

Biofouling creates significant human and economic losses through infections, corrosion, and drag losses on ships and in oil and food distribution pipelines. Organisms adhered to these surfaces contend with high shear rates and are actively transported to the surface. The metallic surfaces to which these organisms are adhered also conduct charge at various potentials, and the effects of surface charge on adhesion rates are little addressed in the literature. We demonstrate that mass-transport limiting current, chronoamperometry, and cyclic voltammetry can be combined to provide resulting adhesion rates similar to those in the literature. Furthermore, we demonstrate that rotating disk electrodes can be used to study adhesion of bacteria to electrically polarized metallic surfaces under shear. We study the adhesion of Escherichia coli, Bacillus subtilis, and 1μm silica microspheres over a range of shear stress from 0.15 to 37  dyncm-2 or shear rates of 14.7-3730  s-1. Unlike quartz-crystal microbalance, our methodology measures changes in the area instead of mass, simultaneously providing measurements of the protein binding. Our deposition rates agree with those found using optical systems. However, unlike optical systems, our methods apply to a wider range of materials than on-chip flow devices.