Out of the dirt: Assessing the antimicrobial properties of cicada-inspired nanostructured polymeric surfaces

Microbial contamination and biofouling are prevalent issues in the shipping industry, underwater pipelines, medical tubing and implants, etc. To prevent microbes from attaching to the surface, a surface coating is usually deposited, which is at risk of losing its efficacy due to erosion. Moreover, recent years have seen a rise in microbial resistance due to the increased use of antibiotics. It is therefore imperative to develop durable surfaces that are mechanically bactericidal. This study uses cicada wings as a model to guide the design of such a durable bactericidal surface. Cicada wings possess many nanoscale protrusions, which have been found to imbue the wings with excellent mechanical bactericidal properties. In this study, we used a flexible and versatile nanoscale replication method to replicate cicada wings. These replicates were made using polydimethylsiloxane (PDMS), a silicon-based organic polymer widely used in biomedical appliances because of its high flexibility and biocompatibility. It is therefore greatly desired to enhance the polymer’s bactericidal property to avoid cell contamination by adding surface structure. The fidelity of the replication was quantified using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and shown to be high. We determined that the cicada-inspired replicates have antimicrobial properties as measured using confocal microscopy and cell-viability assays. By adopting an interdisciplinary approach, this study bridges different branches of sciences and created a novel bioinspired surface that has bactericidal properties.