Mechano-bactericidal activity of two-photon polymerized micro-and nanoscale topographies against Pseudomonas aeruginosa: Surface interactions and antibacterial efficacy

The emergence of antimicrobial-resistant bacteria poses a significant health concern, stemming from chemically induced intrinsic and acquired-resistance responses in the microbe. Nanopatterns are an alternative bactericidal approach, employing physical features to prevent biofilm formation and kill bacteria. This work draws inspiration from the natural mechano-bactericidal properties of sub-micron scale surface structures present on cicada wings, with the fabrication of synthetic, chemically-inert surfaces using the two-photon polymerization (2PP) technique. In contrast to the random packing and distribution of the nanotopography of cicada wings, the 2PP synthetic surfaces were produced with highly uniform and precise surface geometries of nanopillars and micropillars. These synthetic topographies with hexagonal-arranged nano/micro features induced a spacing-dependent response in Pseudomonas aeruginosa, influencing their cell viability, adhesion property and biofilm formation ability. Optimized spacings similar to 500 nm between nanopillars were associated with higher proportions of distorted and ruptured bacteria cells, while up to 60 % reduction of biofilms were observed on micropillared surfaces with similar to 2 micron spacings between pillars. Whole transcriptome analysis of bacteria exposed to the synthetic surface indicated significant upregulation of a single pathway associated with quorum sensing. The PA3305.1 pathway induced quinolone signal synthesis in P. aeruginosa. The findings of this study establish the basis for developing complex antimicrobial surfaces using a physical approach, without reliance on chemical means.