The Antibacterial Activity of Hierarchical Patterns of Nanostructured Silicon Fabricated Using Block Copolymer Micelle Lithography

Herein, the fabrication of four different nanostructured silicon surfaces by using a combination of block copolymer micelle lithography is reported on. Nanoparticle hard masks are evaluated for their ability to produce single-height nanoneedle arrays. Low-density (3 features mu m-2) and high-density (201 features mu m-2) single-height arrays are produced from Au or alpha-Fe2O3 masks, respectively. These single-height arrays are then used as substrates to produce nanostructured surfaces with two distinct nanoneedle arrays concerning height, diameter, and density. These dual-height arrays have feature densities of 31 and 9 features mu m-2. All surface types are then tested for their antibacterial activity against Gram-negative bacteria, Pseudomonas fluorescens, over 24 h. No difference in surface coverage of P. fluorescens when comparing the structured silicon surface types to planar controls is observed. However, all of the structured silicon types show an increase in dead cell surface coverage ranging from 9 to 29% compared to planar controls. Density of the pillars appears to be more important than the difference in height of pillars when it comes to antibacterial activity. This work seeks to add to the literature by investigating the effects of feature density, as well as the impact of a dual-height arrangement of nanoneedles against P. fluorescens. Nanostructured dual-height silicon surfaces are fabricated by using a combination of sequential block copolymer micelle lithography steps and plasma etching. All surfaces are tested for their antibacterial activity against Pseudomonas fluorescens. Density of the pillars is identified as more important than the difference in height when it comes to antibacterial activity.image (c) 2024 WILEY-VCH GmbH