Most bacteria live in multicellular communities known as biofilms that are adherent to surfaces in our environment, from sea beds to plumbing systems. Biofilms are often associated with clinical infections, nosocomial deaths and industrial damage such as bio-corrosion and clogging of pipes. As mature biofilms are extremely challenging to eradicate once formed, prevention is advantageous over treatment. However, conventional surface chemistry strategies are either generally transient, due to chemical masking, or toxic, as in the case of leaching marine antifouling paints. Inspired by the nonfouling skins of echinoderms and other marine organisms, which possess highly dynamic surface structures that mechanically frustrate bio-attachment, we have developed and tested a synthetic platform based on both uniaxial mechanical strain and buckling-induced elastomer microtopography. Bacterial biofilm attachment to the dynamic substrates was studied under an array of parameters, including strain amplitude and timescale (1–100 mm s−1), surface wrinkle length scale, bacterial species and cell geometry, and growth time. The optimal conditions for achieving up to ~ 80% Pseudomonas aeruginosa biofilm reduction after 24 h growth and ~ 60% reduction after 48 h were combinatorially elucidated to occur at 20% strain amplitude, a timescale of less than ~ 5 min between strain cycles and a topography length scale corresponding to the cell dimension of ~ 1 μm. Divergent effects on the attachment of P. aeruginosa, Staphylococcus aureus and Escherichia coli biofilms showed that the dynamic substrate also provides a new means of species-specific biofilm inhibition, or inversely, selection for a desired type of bacteria, without reliance on any toxic or transient surface chemical treatments.
We thank Tom Blough for valuable assistance with tensile system upgrade work and integration, Jack Alvarenga for assistance with substrate fabrication development, Ilana Kolodkin for advice and culturing medium and the Professor Losick Lab (Harvard Department of Molecular and Cellular Biology) for use of autoclave facilities. DH was funded by the NSF Research Experience for Undergraduates (REU) program under award no. DMR-0820484. This work was funded in part by the Office of Naval Research under award no. N00014-11-1-0641 and BASF Advanced Research Initiative at Harvard University.