Electric Potential Induced Prevention and Removal of an Algal Biofoulant from Planar SERS Substrates

Ulva zoospores are widespread marinemacroalgaeand a common organism found in biofouling communities due to theirstrong adhesive properties and quick settlement times. Using Ulva as a model organism, a strategy is presented wheredirect-current (DC) electric potentials are applied in conjunctionwith surface-enhanced Raman spectroscopy (SERS) to characterize, remove,and prevent Ulva from forming a biofilm on gold-cappednanopillar SERS substrates. Experiments were conducted within a poly(tetrafluoroethylene)(PTFE) flow channel device where the SERS substrates were used asan electrode. Ulva density, determined in situ bySERS and ex situ by electron and fluorescence microscopy, decreasedunder successively increasing low negative potentials up to -1.0V. The presence of damaged Ulva suggests that theapplied potential led to spore rupture. At the highest negative appliedpotential (-1.0 V), microparticles containing copper, whichis known for its antimicrobial properties, were associated with Ulva on the SERS substrate and the lowest Ulva density was observed. These findings indicate that (1) SERS canbe employed to study biofilm formation on nanostructured metal surfacesand (2) applying low-voltage electric potentials may be used to control Ulva biofouling on SERS marine sensors. Nanostructured marine sensors requireanti-biofouling strategies.This study shows that low-voltage electric potentials can disruptformed biofilms and inhibit biofilm formation on gold nanopillar SERSsubstrates.