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

Abstract

Research into nanostructured materials, inspired by the topography of certain insect wings, has provided a potential pathway toward drug-free antibacterial surfaces, which may be vital in the ongoing battle against antimicrobial resistance. However, to produce viable antibacterial nanostructured surfaces, we must first understand the bactericidal mechanism of action and how to optimize them to kill the widest range of microorganisms. This review discusses the parameters of nanostructured surfaces that have been shown to influence their bactericidal efficiency and highlights the highly variable nature of many of the findings. A large-scale analysis of the literature is also presented, which further shows a lack of clarity in what is understood about the factors influencing bactericidal efficiency. The potential reasons for the ambiguity, including how the killing effect may be a result of multiple factors and issues with nonstandardized testing of the antibacterial properties of nanostructured surfaces, are then discussed. Finally, a standard method for testing of antimicrobial killing is proposed that will allow comparison between studies and enable a deeper understanding about nanostructured surfaces and how to optimize their bactericidal efficiency.

Two-photon lithography for customized microstructured surfaces and their influence on wettability and bacterial load

“…However, as there is no consensus in the literature for the optimal topographical features to prevent bacterial adhesion and biofilm formation, a fast, reproducible production technique with sufficient resolution is required to produce test surfaces and to examine their effectiveness with regard to their antibacterial properties [ 11 , 19 ].…”

Learning from Nature: Fighting Pathogenic Escherichia coli Bacteria Using Nanoplasmonic Metasurfaces

“…Alternatively, nanostructures can induce mechanical rupture of bacteria by puncturing their membranes similar to natural surfaces. [ 21 ]…”

“…Alternatively, nanostructures can induce mechanical rupture of bacteria by puncturing their membranes similar to natural surfaces. [21] In addition to the mechano-bactericidal effects which could be created by bioinspired surfaces, a second tool to fight bacteria is to illuminate the surfaces with a specific wavelength of light which can effectively reduce the population of pathogenic microorganisms. In nature, this happens all the time by sunlight.…”

“…[18] Altogether, by learning from nature, researchers were able to fabricate bioinspired antibacterial surfaces by manipulating the shape, size, and arrangement of synthetic nanostructures, to alter the surface texture of materials and to control the interactions between the surface and bacteria, thus achieving antibacterial properties through mechanical effects. [21] One such mechanobactericidal effect is the reduced adhesion of bacteria to a surface resulting from a high contact angle due to nanotextures on the surface. Alternatively, nanostructures can induce mechanical rupture of bacteria by puncturing their membranes similar to natural surfaces.…”

Cell Adhesion, Elasticity, and Rupture Forces Guide Microbial Cell Death on Nanostructured Antimicrobial Titanium Surfaces

“…One promising technology is surface nanostructuring, whereby a nanoarchitecture is incorporated onto the surface of a material, rendering it unsuitable for microbial colonization. − Nanostructures can either limit the attachment of microbes and therefore the initial formation of a biofilm ,,− or induce cell lysis upon surface contact via damage of the cell membrane leading to cellular death. ,− The latter mechanism is referred to as a mechano-microbiocidal response, whereby bacterial and fungal cells self-rupture as they adsorb onto the nanostructured surface. Here, the membranes of a microbe must stretch beyond their elastic limit under the influence of natural adhesion forces.…”