Spatially Organized Nanopillar Arrays Dissimilarly Affect the Antifouling and Antibacterial Activities of Escherichia coli and Staphylococcus aureus

Abstract

Bacterial attachment and proliferation on surfaces threaten human health and negatively impact the medical, food processing, and marine industries. In this study, we synthetically produced bioinspired nanotopographies to probe the structure− property relationship between feature size/spacing and the outcome behavior of two distinct microorganisms, Escherichia coli and Staphylococcus aureus. Two different poly(dimethylsiloxane) (PDMS) pillar arrays with characteristic pitches of 480 and 1100 nm were fabricated using nanoimprint lithography, which is a lowcost, scalable, and time-efficient method to create numerous replicates from one precious master mold. The effect that the pillar arrays had on the short-term antifouling activity, viability, and/or patterning of the two microorganisms was determined and compared to that of flat PDMS surfaces. The larger P1100 pillar arrays showed antifouling behavior against the larger microbe, E. coli, whereas the same pillars spontaneously patterned the smaller S. aureus cells. Smaller P480 nanopillar arrays expressed bactericidal effects toward E. coli, whereas antifouling behavior was observed for S. aureus. This work aims to improve our basic understanding of how microorganisms interact with bioinspired nanotopographies as well as contribute to the development of engineered surfaces that can be used in industrial settings to control microbial attachment and/or viability.

Encapsulating bacteria in alginate-based electrospun nanofibers

“…A two-sided unpaired Student's t-test was used to determine statistical significance reports in figures, consistent with previous work from our group. [57][58][59]…”

Biomimetic Polymer Surfaces by High Resolution Molding of the Wings of Different Cicadas

“…Previous work in this area showed that microstructured PDMS surfaces could reduce bacterial adherence when structures were comparable in size to the bacterial cells tested [ 12 , 19 ]. Along with the antibiofouling properties of micropatterned surfaces, E. coli has been shown to be susceptible to cell death when structures on a replicated polymer surface are smaller in diameter and spacing than the bacterial cells tested [ 19 ]. Having produced a replica mold of a number of cicada wings, we then proceeded to test the antibacterial activity of a PEG replica of a cicada wing known to possess antibacterial properties, the ME wing [ 6 ].…”

“…As with the ME wing tested here, no significant cell death was observed against Gram-positive S. epidermidis when subjected to PEG replicas of the wing. As mentioned, this was thought to be due to differences in their cell membrane characteristics compared to Gram-negative species [ 19 , 67 ]. The bacterial cell surface coverage was compared for the ME wing and the PEG replica, for both P. fluorescens and S. epidermidis ( Supplementary Materials Figure S11 ).…”

“…However, this does not agree with our own experimental findings where pillars that were close together did more damage to bacteria. Similarly, recent work by Heckmann et al showed that closely packed microscale pillars of polydimethylsiloxane (PDMS) also caused greater cell damage against E. coli and S. aureus than pillars spaced further apart [ 19 ]. The work by Bandara in 2017 proposes that the membrane stress is a result of a combination of strong adhesion between pillars and the bacterium extracellular membrane as well as shear force when immobilized bacteria attempt to move across the structure, and not, in fact, as a result of direct contact of the bacterial cell membrane with the nanopillars [ 9 ].…”

“…We identified limitations in drop cast molding of tightly packed features and developed a molding method to overcome this by using low-viscosity polymers and a molding chamber to control the molding process. Being able to produce surfaces where sub-200 nm diameter features can be replicated is important to enable these materials to be tested for activity, as smaller features have thus far been reported as some of the most active against bacteria [ 4 , 19 ]. Initial biological testing on a replica sample shows that the polymeric molds possess the same antibacterial activity as the corresponding wing.…”