Nanopillar Polymer Films as Antibacterial Packaging Materials

Abstract

This work presents a comprehensive analytical survey of the antibacterial and antibiofouling properties of sub-100-nanometer scale nanopatterned polymers fabricated using scalable industrial processes that are directly applicable for commercial use. Regular nanopillar arrays of 60 nm height and 60 nm pitch were fabricated on polyethylene terephthalate (PET), polypropylene (PP), acrylic, and nylon polymer films using nanoimprint lithography. Analyses of the influence of material type on antibacterial performance revealed that the nanoscale patterns produced using acrylic and nylon polymers were most suitable as anti-infective nanostructured materials. Further assessment of the influence of the nanopattern geometric parameters on the antibacterial efficacy of acrylic and nylon materials revealed the superlative pattern for inactivating and repelling both Gram-positive and Gram-negative bacteria. Acrylic nanostructured films consisting of nanopillars with a height of 60 nm and pitch of 30 nm, respectively, demonstrated distinctly superior antimicrobial and antibiofouling behavior toward both Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacterial species.

Combining Topography and Chemistry to Produce Antibiofouling Surfaces: A Review

“…aeruginosa and S. aureus . Furthermore, oppositely to in vitro experiments, in natural environments, one species of bacteria, or one marine species is rarely found alone, rather in a mixture with many other organisms.…”

“…Indeed, Linklater et al have published in February 2022 a first statistical study of the effect of different nanopillar polymers on P. aeruginosa and S. aureus. 95 Furthermore, oppositely to in vitro experiments, in natural environments, one species of bacteria, or one marine species is rarely found alone, rather in a mixture with many other organisms. Only a few of the articles in this review have mentioned experiments carried out with natural samples.…”

Designing Effective Antimicrobial Nanostructured Surfaces: Highlighting the Lack of Consensus in the Literature

“…It is well established that Gram-negative bacteria are more susceptible than Gram-positive bacteria to killing by NSS due to their thinner cell envelope. , Many investigations in the literature tested the NSS against E. coli (gram −ve), ,,,,,,, P. aeruginosa (gram −ve) ,,,,,,, or S. aureus (gram +ve). ,,,,− , However, many studies also use a range of different bacterial species ,,,, (illustrated by Figure a), and while this is useful to assess the breadth of organisms that the NSS is effective against, comparisons between the studies become difficult. Although work has been done to establish that the shape of the bacterium does not play a role in the bactericidal efficiency, there is some evidence that the optimal feature parameters may vary between different bacterial species, possibly due to the differences in cell wall structure requiring different levels of stress to initiate cell death. ,,, The presence of cell wall structures may also affect the bactericidal efficiency. Jindai et al demonstrated that flagella can become tangled in nanofeatures, causing the bacteria to become trapped near the surface and be damaged by the structures more frequently …”

“…Taking inspiration from these natural biological nanostructures has paved the way for a new class of antibacterial surface technology that acts through a mechano-physical mechanism, negating our reliance on chemicals or drugs. To date, these antibacterial nanostructured surfaces (NSS) have been fabricated from a wide range of materials including silicon, ,− diamond, , metals (e.g., gold, , stainless steel, ZnO − and titanium − ), and polymers (e.g., PMMA, − PET, , PEEK and PS). The fabrication methods for these synthetic NSS often allow close control over the parameters that define the NSS (the height, spacing, and diameter of the nanofeatures) and lead to bactericidal efficiencies that frequently exceed those of natural NSS, such as the cicada wing.…”

Micro-nano hierarchical pillar array structures prepared on curved surfaces by nanoimprinting using flexible molds from anodic porous alumina and their application to superhydrophobic surfaces

“…[5][6][7][8][9][10][11][12][13][14] Nanoimprinting molds are usually fabricated by a combination of electron beam lithography and dry etching. 15,16 However, these methods have some problems, such as the difficulty in fabricating molds with large-area patterns and high-aspect-ratio structures. We have been investigating the formation of ordered ne patterns by nanoimprinting using an anodic porous alumina mold obtained by the anodization of Al in an appropriate acidic electrolyte.…”